10 kA Joints for HTS Roebel Cables

Future HTS high field magnets using multi-tape HTS cables need 10 kA low resistance connections. The connections are needed between the poles of the magnets and at the terminals in a wide operating temperature range, from 1.9-85 K. The EuCARD WP10 Future Magnets collaboration aims at testing HTS based Roebel cables in an accelerator magnet. Usually, LTS cables are jointed inside a relatively short soldered block. Powering tests at CERN have highlighted excess heating of a joint following classical LTS joint design. The HTS Roebel cables are assembled from REBCO coated conductor tapes in a transposed configuration. Due to this, the tapes surface the cable at an angle with the cable axis. A low-resistance joint requires a sufficiently large interface area for each tape. Within one twist pitch length, each tape is located at the surface of the cable over a relatively small non-constant area. This geometry prevents making a well-controlled joint in a compact length along the cable. This paper presents a compact joint configuration for the Roebel cable overcoming these practical challenges. A new joint called fin-block is designed. The joint resistance is estimated computationally. Finally the test results as a function of current and temperature are presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Energy Engineering, European Organization for Nuclear Research
Contributors: Murtomaeki, J. S., Kirby, G., van Nugteren, J., Contat, P. A., Fleiter, J., De Frutos, O. S., Pincot, F. O., DeRijk, G., Rossi, L., Ruuskanen, J., Stenvall, A., Wolf, F.
Publication date: 2018
Peer-reviewed: Yes
Early online date: 9 Feb 2018

Publication information

Journal: IEEE Transactions on Applied Superconductivity
Volume: 28
Issue number: 3
ISSN (Print): 1051-8223
Ratings: 
  • Scopus rating (2018): CiteScore 1.65 SJR 0.406 SNIP 0.969
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Electrical and Electronic Engineering
Keywords: Cables and current leads, Heating systems, High-temperature superconductors, HTS Magnets, Pressure Measurement, Resistance, Resistance measurement, Soldering, Superconducting cables, Superconducting magnets, Superconducting Magnets, Temperature measurement
Source: Scopus
Source ID: 85041856536

Research output: Contribution to journalArticleScientificpeer-review

(16) Psyche: A mesosiderite-like asteroid?

Context. Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be related to iron meteorites. Such an association is however challenged by both its near- and mid-infrared spectral properties and the reported estimates of its density. Aims. Here, we aim to refine the density of (16) Psyche to set further constraints on its bulk composition and determine its potential meteoritic analog. Methods. We observed (16) Psyche with ESO VLT/SPHERE/ZIMPOL as part of our large program (ID 199.C-0074). We used the high angular resolution of these observations to refine Psyche's three-dimensional (3D) shape model and subsequently its density when combined with the most recent mass estimates. In addition, we searched for potential companions around the asteroid. Results. We derived a bulk density of 3.99 ± 0.26 ± cm-3 for Psyche. While such density is incompatible at the 3-sigma level with any iron meteorites (∼7.8 ± cm-3), it appears fully consistent with that of stony-iron meteorites such as mesosiderites (density ∼4.25 ± cm-3). In addition, we found no satellite in our images and set an upper limit on the diameter of any non-detected satellite of 1460 ± 200 m at 150 km from Psyche (0.2% × RHill, the Hill radius) and 800 ± 200 m at 2000 km (3% × RHill). Conclusions. Considering that the visible and near-infrared spectral properties of mesosiderites are similar to those of Psyche, there is merit to a long-published initial hypothesis that Psyche could be a plausible candidate parent body for mesosiderites.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Laboratoire d'Astrophysique de Marseille, Charles University in Prague, CNRS, Queen's University, Belfast, Northern Ireland, SETI Institute, IMCCE - Institut de Mecanique Celeste et de Calcul des Ephemerides, Adam Mickiewicz University, Thirty-Meter-Telescope, Jet Propulsion Laboratory, California Institute of Technology, ESTEC - European Space Research and Technology Centre, Université de Liège, Open University, Université de Versailles Saint-Quentin-en-Yvelines, Pontifical Catholic University of Peru San Miguel, University of Szczecin, Center for Solar System Studies, European Southern Observatory (ESO)
Contributors: Viikinkoski, M., Vernazza, P., Hanuš, J., Le Coroller, H., Tazhenova, K., Carry, B., Marsset, M., Drouard, A., Marchis, F., Fetick, R., Fusco, T., Ďurech, J., Birlan, M., Berthier, J., Bartczak, P., Dumas, C., Castillo-Rogez, J., Cipriani, F., Colas, F., Ferrais, M., Grice, J., Jehin, E., Jorda, L., Kaasalainen, M., Kryszczynska, A., Lamy, P., Marciniak, A., Michalowski, T., Michel, P., Pajuelo, M., Podlewska-Gaca, E., Santana-Ros, T., Tanga, P., Vachier, F., Vigan, A., Warner, B., Witasse, O., Yang, B.
Publication date: 1 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 619
Article number: L3
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2018): CiteScore 4.54 SJR 2.527 SNIP 1.233
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: Methods: observational, Minor planets, asteroids: general, Minor planets, asteroids: individual: (16) Psyche, Techniques: high angular resolution
Source: Scopus
Source ID: 85056511149

Research output: Contribution to journalArticleScientificpeer-review

20th Inverse Days 2014, Tampere 9th-11th December 2014: Abstracts

Proceedings of the Inverse Days 2014 conference organized in Tampere 9th - 11th December 2014. This document contains the schedule of the conference, the list of participants and the abstracts of the talks given at the conference.

General information

Publication status: Published
MoE publication type: D4 Published development or research report or study
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Åkerblom, M. (ed.)
Number of pages: 38
Publication date: 2014

Publication information

Publisher: Tampere University of Technology, Department of Mathematics
ISBN (Print): 978-952-15-3425-6
ISBN (Electronic): 978-952-15-3429-4
Original language: English

Publication series

Name: Tampere University of Technology. Department of Mathematics. Research Report
Publisher: Tampere University of Technology
Volume: 101
ISSN (Print): 1459-3750

Bibliographical note

Versio ok 14.12.2015

Research output: Book/ReportCommissioned reportProfessional

3D shape of asteroid (6) Hebe from VLT/SPHERE imaging: Implications for the origin of ordinary H chondrites

Context. The high-angular-resolution capability of the new-generation ground-based adaptive-optics camera SPHERE at ESO VLT allows us to assess, for the very first time, the cratering record of medium-sized (D ∼ 100-200 km) asteroids from the ground, opening the prospect of a new era of investigation of the asteroid belt's collisional history. Aims. We investigate here the collisional history of asteroid (6) Hebe and challenge the idea that Hebe may be the parent body of ordinary H chondrites, the most common type of meteorites found on Earth (∼34% of the falls). Methods. We observed Hebe with SPHERE as part of the science verification of the instrument. Combined with earlier adaptive-optics images and optical light curves, we model the spin and three-dimensional (3D) shape of Hebe and check the consistency of the derived model against available stellar occultations and thermal measurements. Results. Our 3D shape model fits the images with sub-pixel residuals and the light curves to 0.02 mag. The rotation period (7.274 47 h), spin (ECJ2000 λ, β of 343°, +47°), and volume-equivalent diameter (193 ± 6 km) are consistent with previous determinations and thermophysical modeling. Hebe's inferred density is 3.48 ± 0.64 g cm-3, in agreement with an intact interior based on its H-chondrite composition. Using the 3D shape model to derive the volume of the largest depression (likely impact crater), it appears that the latter is significantly smaller than the total volume of close-by S-type H-chondrite-like asteroid families. Conclusions. Our results imply that (6) Hebe is not the most likely source of H chondrites. Over the coming years, our team will collect similar high-precision shape measurements with VLT/SPHERE for ∼40 asteroids covering the main compositional classes, thus providing an unprecedented dataset to investigate the origin and collisional evolution of the asteroid belt.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Queen's University, Belfast, Northern Ireland, CNRS, IMCCE - Institut de Mecanique Celeste et de Calcul des Ephemerides, TMT Observatory, Charles University in Prague, Laboratoire d'Astrophysique de Marseille, Max-Planck-Institut für Extraterrestrische Physik, Université de Liège, Open University, European Southern Observatory (ESO), ONERA - The French Aerospace Lab, Planetary Science Institute, Universite de Geneve
Contributors: Marsset, M., Carry, B., Dumas, C., Hanuš, J., Viikinkoski, M., Vernazza, P., Müller, T. G., Delbo, M., Jehin, E., Gillon, M., Grice, J., Yang, B., Fusco, T., Berthier, J., Sonnett, S., Kugel, F., Caron, J., Behrend, R.
Publication date: 1 Aug 2017
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 604
Article number: A64
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2017): CiteScore 3.8 SJR 2.265 SNIP 1.257
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: asteroids: individual: (6) Hebe, Meteorites, meteoroids, meteors, Minor planets, Techniques: high angular resolution
Electronic versions: 
Source: Scopus
Source ID: 85027245899

Research output: Contribution to journalArticleScientificpeer-review

Absolute radiometric calibration of ALS intensity data: Effects on accuracy and target classification

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Kaasalainen, S., Pyysalo, U., Krooks, A., Vain, A., Kukko, A., Hyyppä, J., Kaasalainen, M.
Pages: 10586-10602
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 11
Issue number: 11
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2011): CiteScore 2.44 SJR 0.641 SNIP 1.462
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6257

Research output: Contribution to journalArticleScientificpeer-review

Abstractions for transition systems with applications to stubborn sets

Partial order reduction covers a range of techniques based on eliminating unnecessary transitions when generating a state space. On the other hand, abstractions replace sets of states of a system with abstract representatives in order to create a smaller state space. This article explores how stubborn sets and abstraction can be combined. We provide examples to provide intuition and expand on some recent results. We provide a classification of abstractions and give some novel results on what is needed to combine abstraction and partial order reduction in a sound way.

General information

Publication status: Published
MoE publication type: B2 Part of a book or another research book
Organisations: Research group: MAT Computer Science and Applied Logics, Mathematics
Contributors: Hansen, H.
Number of pages: 20
Pages: 104-123
Publication date: 1 Jan 2017

Host publication information

Title of host publication: Concurrency, Security, and Puzzles : Essays Dedicated to Andrew William Roscoe on the Occasion of His 60th Birthday
Publisher: Springer International Publishing
Editors: Gibson-Robinson, T., Hopcroft, P., Lazić, R.
ISBN (Print): 978-3-319-51045-3
ISBN (Electronic): 978-3-319-51046-0

Publication series

Name: Lecture Notes in Computer Science
Volume: 10160
ISSN (Print): 0302-9743
ISSN (Electronic): 1611-3349
ASJC Scopus subject areas: Theoretical Computer Science, Computer Science(all)
Source: Scopus
Source ID: 85006700598

Research output: Chapter in Book/Report/Conference proceedingChapterScientific

A case study of focal bayesian EEG inversion for whitney element source spaces: Mesh-based vs. cartesian orientations

This paper concentrates on the Bayesian detection of the neuronal current distributions in the electroencephalography (EEG) imaging of the brain activity. In particular, we focus on a hierarchical maximum a posteriori inversion technique applicable when the lead field matrix is constructed via the finite element method. We utilize the linear Whitney (Raviart-Thomas) basis functions as source currents. In the numerical experiments, the accuracy was investigated using two spherical head models. The results obtained suggest that the interpolation of the dipolar source space does not necessarily bring any advantage for FEM based inverse computations. Furthermore, the divergence conforming Whitney-type sources were found to be sufficient for precise and highly focal Bayesian modeling of dipole-like currents.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Mathematics, Research group: Inverse Problems
Contributors: Miinalainen, T., Pursiainen, S.
Number of pages: 4
Pages: 1065-1068
Publication date: 2018

Host publication information

Title of host publication: EMBEC and NBC 2017 - Joint Conference of the European Medical and Biological Engineering Conference EMBEC 2017 and the Nordic-Baltic Conference on Biomedical Engineering and Medical Physics, NBC 2017
Publisher: Springer Verlag
ISBN (Print): 9789811051210

Publication series

Name: IFMBE Proceedings
Volume: 65
ISSN (Print): 1680-0737
ASJC Scopus subject areas: Biomedical Engineering, Bioengineering
Keywords: Electroencephalography (EEG), Finite element method (FEM), Hierarchical Bayesian inverse model, Whitney elements

Bibliographical note

jufoid=58152

Source: Scopus
Source ID: 85021711207

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Accelerated simulation of a neuronal population via mathematical model order reduction

Mathematical modeling of biological neuronal net-
works is important in order to increase understanding of the
brain and develop systems capable of brain-like learning. While
mathematical analysis of these comprehensive, stochastic, and
complex models is intractable, and their numerical simulation
is very resource intensive, mean-field modeling is an effective
tool in enabling the analysis of these models. The mean-field
approach allows the study of populations of biophysically detailed
neurons with some assumptions of the mean behaviour of the
population, but ultimately requires numerical solving of high-
dimensional differential equation systems. Mathematical model
order reduction methods can be employed to accelerate the anal-
ysis of high-dimensional nonlinear models with a purely software-
based approach. Here we compare state-of-the-art methods for
improving the simulation time of a neuronal mean-field model
and show that a nonlinear Fokker-Planck-McKean-Vlasov model
can be accurately approximated in low-dimensional subspaces
with these methods. Using Proper Orthogonal Decomposition
and different variations of the Discrete Empirical Interpolation
Method, we improved the simulation time by over three orders
of magnitude while achieving low approximation error.

General information

Publication status: Accepted/In press
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Computing Sciences, Research group: Computational Neuro Science-CNS
Contributors: Lehtimäki, M., Seppälä, I., Paunonen, L., Linne, M.
Publication date: 10 Dec 2019

Host publication information

Title of host publication: Proceedings of the IEEE International Conference on Artificial Intelligence Circuits and Systems
Publisher: IEEE Xplore

Bibliographical note

Ei ilm. 9.1.20 M. K.

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Acceleration of the rotation of asteroid 1862 Apollo by radiation torques

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Kaasalainen, M., Durech, J., Warner, B., Krugky, Y., Gaftonyuk, N.
Pages: 420-422
Publication date: 2007
Peer-reviewed: Yes

Publication information

Journal: Nature
Volume: 446
ISSN (Print): 0028-0836
Ratings: 
  • Scopus rating (2007): SJR 10.344 SNIP 7.1
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 14506

Research output: Contribution to journalArticleScientificpeer-review

A characterization of level-continuous fuzzy numbers

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Kaleva, O.
Pages: 84-88
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
Volume: 209
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2012): CiteScore 2.97 SJR 1.472 SNIP 2.349
Original language: English

Bibliographical note

Published 16 December 2012<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Elsevier BV North-Holland

Source: researchoutputwizard
Source ID: 4387

Research output: Contribution to journalArticleScientificpeer-review

A comparison of confluence and ample sets in probabilistic and non-probabilistic branching time

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Hansen, H., Timmer, M.
Number of pages: 21
Pages: 103-123
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Theoretical Computer Science
Volume: 528
ISSN (Print): 0304-3975
Ratings: 
  • Scopus rating (2014): CiteScore 1.08 SJR 0.669 SNIP 1.139
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-05-31<br/>Publisher name: Elsevier

Source: researchoutputwizard
Source ID: 412

Research output: Contribution to journalArticleScientificpeer-review

Acoustic Modelling

Let us examine the behaviour of sound in a gas or in a liquid medium. From a physical point of view, the sound we hear is created by the pressure change in the medium surrounding us that is sensed by our ears. The equations describing the behaviour of a liquid or a gas are based on well-known equations of fluid mechanics. Therefore in acoustics, they are often referred to as fluids. In the following sections we present a simple wave equation, which is the simplest of (linear) equations used to model acoustical phenomena. Even though the wave equation is quite a simplified model, it has proven to be extremely useful for describing the behaviour of sound in the most common fluid we face every day, namely air.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory, Research group: MAT Mathematical and semantic modelling, Tampere Univ Technol, Tampere University of Technology
Contributors: Pohjolainen, S., Suutala, A.
Number of pages: 21
Pages: 185-205
Publication date: 30 Jun 2016

Host publication information

Title of host publication: Mathematical Modelling
Place of publication: Switzerland
Publisher: Springer
Editor: Pohjolainen, S.
ISBN (Print): 978-3-319-27834-6
ISBN (Electronic): 978-3-319-27836-0
ASJC Scopus subject areas: Applied Mathematics, Modelling and Simulation, Acoustics and Ultrasonics

Bibliographical note

INT=mat,”Suutala, Antti"

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

ADAM: A general method for using various data types in asteroid reconstruction

We introduce ADAM, the All-Data Asteroid Modelling algorithm. ADAM is simple and universal since it handles all disk-resolved data types (adaptive optics or other images, interferometry, and range-Doppler radar data) in a uniform manner via the 2D Fourier transform, enabling fast convergence in model optimization. The resolved data can be combined with disk-integrated data (photometry). In the reconstruction process, the difference between each data type is only a few code lines defining the particular generalized projection from 3D onto a 2D image plane. Occultation timings can be included as sparse silhouettes, and thermal infrared data are efficiently handled with an approximate algorithm that is sufficient in practice because of the dominance of the high-contrast (boundary) pixels over the low-contrast (interior) pixels. This is of particular importance to the raw ALMA data that can be directly handled by ADAM without having to construct the standard image. We study the reliability of the inversion, using the independent shape supports of function series and control-point surfaces. When other data are lacking, one can carry out fast non-convex lightcurve-only inversions, but any shape models resulting from it should only be taken as illustrative large-scale models.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Inverse Problems, Mathematical modelling with wide societal impact (MathImpact), Astronomical Institute, Faculty of Mathematics and Physics, Charles University in Prague
Contributors: Viikinkoski, M., Kaasalainen, M., Durech, J.
Number of pages: 11
Publication date: 1 Apr 2015
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 576
Article number: A8
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2015): CiteScore 3.5 SJR 2.545 SNIP 1.247
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: Methods: analytical, Methods: numerical, Minor planets, asteroids: general, Minor planets, asteroids: individual: 2000 ET70, Minor planets, asteroids: individual: Daphne
Electronic versions: 
Source: Scopus
Source ID: 84925251323

Research output: Contribution to journalArticleScientificpeer-review

Adaptive mobile tracking in unknown non-line-of-sight conditions with application to digital TV networks

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Chen, L., Piche, R., Kuusniemi, H., Chen, R.
Number of pages: 10
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2014
Article number: UNSP 22
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2014): CiteScore 0.7 SJR 0.286 SNIP 0.918
Original language: English

Bibliographical note

Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2014-05-25<br/>Publisher name: Springer

Source: researchoutputwizard
Source ID: 219

Research output: Contribution to journalArticleScientificpeer-review

Adaptive optics and lightcurve data of asteroids: Twenty shape models and information content analysis

We present shape models and volume estimates of twenty asteroids based on relative photometry and adaptive optics images. We discuss error estimation and the effects of myopic deconvolution on shape solutions. For further analysis of the information capacities of data sources, we also present and discuss ambiguity and uniqueness results for the reconstruction of nonconvex shapes from photometry.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Charles University in Prague, SETI Institute
Contributors: Viikinkoski, M., Hanuš, J., Kaasalainen, M., Marchis, F., Ďurech, J.
Publication date: 1 Nov 2017
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 607
Article number: A117
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2017): CiteScore 3.8 SJR 2.265 SNIP 1.257
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: Instrumentation: adaptive optics, Methods: analytical, Methods: numerical, Minor planets, asteroids: general, Techniques: photometric
Electronic versions: 
Source: Scopus
Source ID: 85035125736

Research output: Contribution to journalArticleScientificpeer-review

A differential form approach to Dirac operators on surfaces

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Orelma, H., Sommen, F.
Pages: 213-232
Publication date: 2011

Host publication information

Title of host publication: Hypercomplex Analysis and Applications. Trends in Mathematics
Place of publication: Basel
Publisher: Birkhäuser
Editors: Sabadini, I., Sommen, F.
ISBN (Print): 978-3-0346-0245-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6928

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Advanced boundary electrode modeling for tES and parallel tES/EEG

This paper explores advanced electrode modeling in the context of separate and parallel transcranial electrical stimulation (tES) and electroencephalography (EEG) measurements.We focus on boundary condition based approaches that do not necessitate adding auxiliary elements, e.g. sponges, to the computational domain. In particular, we investigate the complete electrode model (CEM) which incorporates a detailed description of the skin-electrode interface including its contact surface, impedance and normal current distribution. The CEM can be applied for both tES and EEG electrodes which is advantageous when a parallel system is used. In comparison to the CEM, we test two important reduced approaches: the gap model (GAP) and the point electrode model (PEM). We aim to find out the differences of these approaches for a realistic numerical setting based on the stimulation of the auditory cortex. The results obtained suggest, among other things, that GAP and GAP/PEM are sufficiently accurate for the practical application of tES and parallel tES/EEG, respectively. Differences between CEM and GAP were observed mainly in the skin compartment, where only CEM explains the heating effects characteristic to tES.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, University of Münster
Contributors: Pursiainen, S., Agsten, B., Wagner, S., Wolters, C. H.
Pages: 37-44
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Volume: 26
Issue number: 1
ISSN (Print): 1534-4320
Ratings: 
  • Scopus rating (2017): CiteScore 5.14 SJR 1.152 SNIP 2.092
Original language: English
ASJC Scopus subject areas: Neuroscience(all), Biomedical Engineering, Computer Science Applications
Keywords: Boundary conditions, Brain modeling, Complete electrode model (CEM), Computational modeling, Electric potential, Electrodes, Electroencephalography, Electroencephalography (EEG) electrode modeling, Finite element method (FEM)., Skin, Transcranial electrical stimulation (tES)
Source: Scopus
Source ID: 85030762392

Research output: Contribution to journalArticleScientificpeer-review

Advances in Augmented Reality Technologies

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Department of Mathematics
Contributors: Pylvänäinen, T.
Number of pages: 183
Publication date: 2011

Publication information

Place of publication: Tampere
Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-2611-4
Original language: Finnish

Publication series

Name: Tampere University of Technology. Publication
Publisher: Tampere University of Technology
Volume: 975
ISSN (Print): 1459-2045

Bibliographical note

Awarding institution:Tampere University of Technology

Source: researchoutputwizard
Source ID: 7069

Research output: Book/ReportDoctoral thesisCollection of Articles

A Feedforward Controller for Distributed Parameter Systems

A feedforward controller is introduced for an important class of distributed parameter systems. The purpose of the control is to regulate the outputs of the system in spite of some perturbations. The theory presented is clarified with an example.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Pohjolainen, S.
Pages: 173-184
Publication date: 1981
Peer-reviewed: Yes

Publication information

Journal: International Journal of Control
Volume: 34
Issue number: 1
ISSN (Print): 0020-7179
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

A field test of parametric WLAN-fingerprint-positioning methods

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Muller, P., Raitoharju, M., Piche, R.
Number of pages: 8
Pages: 1-8
Publication date: 2014

Host publication information

Title of host publication: 17th International Conference on Information Fusion (FUSION), 7-10 July 2014, Salamanca, Spain
Place of publication: Piscataway
Publisher: Institute of Electrical and Electronics Engineers
ISBN (Print): 978-84-9012-355-3

Bibliographical note

The paper is available in ieeexplore, and will later also appear at http://isif.org/content/conference-proceedings<br/>Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2014-11-21

Source: researchoutputwizard
Source ID: 1108

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A fractional representation approach to the robust regulation problem for SISO systems

The purpose of this article is to develop a new approach to the robust regulation problem for plants which do not necessarily admit coprime factorizations. The approach is purely algebraic and allows us dealing with a very general class of systems in a unique simple framework. We formulate the famous internal model principle in a form suitable for plants defined by fractional representations which are not necessarily coprime factorizations. By using the internal model principle, we are able to give necessary and sufficient solvability conditions for the robust regulation problem and to parameterize all robustly regulating controllers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Parc Scientifique de la Haute Borne
Contributors: Laakkonen, P., Quadrat, A.
Number of pages: 6
Pages: 32-37
Publication date: 1 May 2017
Peer-reviewed: Yes

Publication information

Journal: Systems and Control Letters
Volume: 103
ISSN (Print): 0167-6911
Ratings: 
  • Scopus rating (2017): CiteScore 3.4 SJR 1.939 SNIP 1.712
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Computer Science(all), Mechanical Engineering, Electrical and Electronic Engineering
Keywords: Fractional representation approach, Linear systems, Robust regulation
Source: Scopus
Source ID: 85016517305

Research output: Contribution to journalArticleScientificpeer-review

A Framework for Bayesian Receiver Autonomous Integrity Monitoring in Urban Navigation

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Pesonen, H.
Pages: 229-240
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Navigation
Volume: 58
Issue number: 3
ISSN (Print): 0028-1522
Ratings: 
  • Scopus rating (2011): CiteScore 0.97 SJR 0.453 SNIP 1.074
Original language: English

Bibliographical note

ei ut-numeroa 26.4.2014<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7006

Research output: Contribution to journalArticleScientificpeer-review

A general framework for island systems

The notion of an island defined on a rectangular board is an elementary combinatorial concept that occurred first in [3]. Results of [3] were starting points for investigations exploring several variations and various aspects of this notion. In this paper we introduce a general framework for islands that subsumes all earlier studied concepts of islands on finite boards, moreover we show that the prime implicants of a Boolean function, the formal concepts of a formal context, convex subgraphs of a simple graph, and some particular subsets of a projective plane also fit into this framework. We axiomatize those cases where islands have the property of being pairwise comparable or disjoint, or they are distant, introducing the notion of a connective island domain and of a proximity domain, respectively. In the general case the maximal systems of islands are characterised by using the concept of an admissible system. We also characterise all possible island systems in the case of connective island domains and proximity domains.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Bolyai Institute, University of Szeged, University of Miskolc
Contributors: Foldes, S., Horváth, E. K., Radeleczki, S., Waldhauser, T.
Number of pages: 22
Pages: 3-24
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Acta Universitatis Szegediensis: Acta Scientiarum Mathematicarum
Volume: 81
Issue number: 1-2
ISSN (Print): 0001-6969
Ratings: 
  • Scopus rating (2015): CiteScore 0.34 SJR 0.309 SNIP 0.73
Original language: English
ASJC Scopus subject areas: Analysis, Applied Mathematics
Keywords: Admissible system, CD-independent and CDW-independent sets, Connected subgraph, Convex subgraph, Distant system, Formal concept, Height function, Island domain, Island system, Point-to-set proximity relation, Prime implicant, Projective plane, Proximity domain
Source: Scopus
Source ID: 84938827353

Research output: Contribution to journalArticleScientificpeer-review

A Hyperbolic Dirac Operator and its Kernels

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S.
Number of pages: 15
Pages: 767-781
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Complex Variables and Elliptic Equations
Volume: 58
Issue number: 6
ISSN (Print): 1747-6933
Ratings: 
  • Scopus rating (2013): CiteScore 0.67 SJR 0.744 SNIP 1.122
Original language: Finnish

Bibliographical note

Taylor&Francis Online first: Forthcoming articles 12.10.2011.Poistettu Portfolio13:sta tupla r=1849.<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 2114

Research output: Contribution to journalArticleScientificpeer-review

A hyperbolic interpretation of Cauchy type kernels in hyperbolic function theory

General information

Publication status: Published
MoE publication type: D4 Published development or research report or study
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Publication date: 2010

Publication information

Place of publication: Tampere
Publisher: Unknown Publisher
ISBN (Print): 978-952-15-2334-2
Original language: English

Publication series

Name: Tampereen teknillinen yliopisto. Matematiikan laitos. Tutkimusraportti
Volume: 96
ISSN (Print): 1459-3750

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7883

Research output: Book/ReportCommissioned reportProfessional

A hyperbolic interpretation of Cauchy-type kernels in hyperbolic function theory in hypercomplex analysis

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Pages: 43-59
Publication date: 2011

Host publication information

Title of host publication: Hypercomplex Analysis and Applications. Trends in Mathematics
Place of publication: Basel
Publisher: Birkhäuser
Editors: Sabadini, I., Sommen, F.
ISBN (Print): 978-3-0346-0245-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5919

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Akustinen mallinnus

General information

Publication status: Published
MoE publication type: B2 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Pohjolainen, S., Suutala, A.
Pages: 238-259
Publication date: 2010

Host publication information

Title of host publication: Matemaattinen mallinnus
Place of publication: Helsinki
Publisher: WSOYpro
Editor: Pohjolainen, S.
ISBN (Print): 978-951-0-35408-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9008

Research output: Chapter in Book/Report/Conference proceedingChapterScientific

Algorithms and Logic as Programming Primers

To adapt all-immersive digitalization, the Finnish National Curriculum 2014 (FNC-2014) ‘digi-jumps’ by integrating programming into elementary education. However, applying the change to mathematics teachers’ everyday praxis is hindered by a too high-level specification. To elaborate FNC-2014 into more concrete learning targets, we review the computer science syllabi of countries that are well ahead, as well as the education recommendations set by computer science organizations, such as ACM and IEEE. The whole mathematics syllabus should be critically viewed in the light of these recommendations and feedback collected from software professionals and educators. The feedback reveals an imbalance between supply and demand, i.e., what is over-taught versus under-taught, from the point of the requirements of current working life. The surveyed software engineers criticize the unnecessary surplus of calculus and differential equations, i.e., continuous mathematics. In contrast, the emphasis should shift more towards algorithms and data structures, flexibility in handling multiple data representations, and logic: in short – discrete mathematics. The ground for discrete mathematics should be prepared early enough, started already from primary level and continued consistently throughout the secondary till tertiary education. This paper aims to contribute to the further refinement of the mathematics syllabus by proposing such a discrete mathematics subset that especially supports the needs of computer science education, the focus being on algorithms and data structures, and logic in particular.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, University of Jyväskylä
Contributors: Niemelä, P., Valmari, A., Ali-Löytty, S.
Pages: 357-383
Publication date: Jun 2019

Host publication information

Title of host publication: Computer Supported Education : 10th International Conference, CSEDU 2018, Revised Selected Papers
Publisher: Springer Nature
ISBN (Print): 9783030211509

Publication series

Name: Communications in Computer and Information Science
Volume: 1022
ISSN (Print): 1865-0929
Keywords: Computational thinking, algorithms, logic
URLs: 

Bibliographical note

jufoid=53801
EXT="Valmari, Antti"

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A linear state model for PDR+WLAN positioning

Indoor positioning based on WLAN signals is often enhanced using pedestrian dead reckoning (PDR) based on an inertial measurement unit. The state evolution model in PDR is usually nonlinear. We present a new linear state evolution model for PDR. In simulated-data and real-data tests of tightly coupled WLAN-PDR positioning, we find that the positioning accuracy with this linear model is almost as good as with traditional models when the initial state is known, and better when the initial state is not known. The proposed method is computationally light and is also suitable for smoothing.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Nurminen, H., Piche, R.
Number of pages: 6
Pages: 113-118
Publication date: 2013

Host publication information

Title of host publication: Proceedings of the 2013 Conference on Design and Architectures for Signal and Image Processing DASIP Cagliari, Italy, October 8-10, 2013
Place of publication: Belmont France
Publisher: European Electronic Chips & Systems Design Initiative (ECSI)
Editors: Morawiec, A., Hinderscheit, J.
ISBN (Print): 979-10-92279-02-3
ISBN (Electronic): 979-10-92279-01-6

Publication series

Name: Conference on Design and Architectures for Signal and Image Processing
Publisher: European Electronic Chips & Systems Design Initiative (ECSI)
ISSN (Print): 1966-7116

Bibliographical note

to appear in IEEEXPLORE<br/>Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2013-10-29

Source: researchoutputwizard
Source ID: 3209

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A Lukasiewicz-style Many-Valued Similarity Reasoning: Review

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Matematiikka
Contributors: Turunen, E.
Number of pages: 34
Pages: 315- 348
Publication date: 2003

Host publication information

Title of host publication: Beyond Two : Theory and Applications of Multiple-Valued Logic
Place of publication: Heidelberg
Publisher: Physica-Verlag
Editors: Fitting, M., Orlowska, E.
ISBN (Print): 3-7908-1541-1

Publication series

Name: Studies in Fuzziness and Soft Computing
ISSN (Print): 1434-9922

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Alumni Network Analysis

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Rubens, N., Russell, M. G., Perez, R., Huhtamäki, J., Still, K., Kaplan, D., Okamoto, T.
Pages: 606-611
Publication date: 2011

Host publication information

Title of host publication: 2011 IEEE 2nd Global Engineering Education Conference EDUCON, 4-6 April 2011, Amman, Jordan
Place of publication: Piscataway, NJ
Publisher: IEEE
ISBN (Print): 978-1-61284-642-2

Publication series

Name: IEEE Global Engineering Education Conference EDUCON
Publisher: IEEE

Bibliographical note

ei ut-numeroa 5.3.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 7152

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A Lyapunov approach to strong stability of semigroups

In this paper we present Lyapunov based proofs for the well-known Arendt-Batty-Lyubich-Vu Theorem for strongly continuous and discrete semigroups. We also study the spectral properties of the limit isometric groups used in the proofs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Paunonen, L., Zwart, H.
Number of pages: 6
Pages: 673-678
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Systems and Control Letters
Volume: 62
Issue number: 8
ISSN (Print): 0167-6911
Ratings: 
  • Scopus rating (2013): CiteScore 3.46 SJR 2.019 SNIP 1.963
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: Elsevier

Source: researchoutputwizard
Source ID: 3114

Research output: Contribution to journalArticleScientificpeer-review

A Mean-Value Theorem for Some Eigenfunctions of the Laplace -Beltrami Operator on the Upper-Half Space

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Number of pages: 10
Pages: 101-110
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Annales Academiae Scientiarum Fennicae-Mathematica
Volume: 36
ISSN (Print): 1239-629X
Ratings: 
  • Scopus rating (2011): CiteScore 0.79 SJR 1.467 SNIP 1.334
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5920

Research output: Contribution to journalArticleScientificpeer-review

A Measurement-based Statistical Model to Evaluate Uncertainty in Long-range Noise Assessments

Carefully validated long-range sound propagation measurements with extensive meteorological instrumentation were continued for 612 days without interruption, around the clock, resulting in a database with millions of files, terabytes of sound and environmental data, and hundreds of pages of documentation. More than 100 environmental variables were analysed by statistical means, and many statistically highly significant dependencies linked to excess attenuation were found. At a distance of 3 km from the source, excess attenuation was spread over a dynamic range of 80 dB, with differences of 10 dB between individual quarters of the year; also, negative excess attenuation at frequencies below 400 Hz existed. The low frequencies were affected mainly by the stability characteristics of the atmosphere and the lapse rate. Humidity; lapse rate; sensible heat flux; and longitudinal, transverse, and vertical turbulence intensities explain excess attenuation at higher frequencies to a statistically highly significant extent. Through application of a wide range of regression analyses, a set of criteria for frequency-dependent uncertainty in sound propagation was created. These criteria were incorporated into a software module, which, together with a state-of-the-art physical sound propagation calculation module, makes it possible to perform environmental noise assessments with known uncertainty. This approach can be applied to the short term measurements too and it was shown that some of the most complex meteorological variables, among them atmospheric turbulence, can be taken into account. Comparison with two standardized noise modelling methods showed that the statistical model covers well a range of uncertainty not matched with the standardized methods and the measured excess attenuation fit within the limits of predicted uncertainty.

General information

Publication status: Published
MoE publication type: G4 Doctoral dissertation (monograph)
Organisations: Department of Automation Science and Engineering
Contributors: Maijala, P.
Number of pages: 178
Publication date: 3 Jan 2014

Publication information

Publisher: VTT
ISBN (Print): 978-951-38-8109-2
ISBN (Electronic): 978-951-38-8110-8
Original language: English

Publication series

Name: VTT Science
Publisher: VTT
Volume: 48
ISSN (Print): 2242-119X
ISSN (Electronic): 2242-1203

Bibliographical note

Awarding institution:Tampereen teknillinen yliopisto - Tampere University of Technology<br/>Submitter:Submitted by Kaisa Kulkki (kaisa.kulkki@tut.fi) on 2013-12-18T08:26:49Z
No. of bitstreams: 1
maijala.pdf: 8876096 bytes, checksum: a9348271868d9cc37d85ecf3800e67ff (MD5)<br/>Submitter:Approved for entry into archive by Kaisa Kulkki (kaisa.kulkki@tut.fi) on 2013-12-18T09:39:44Z (GMT) No. of bitstreams: 1
maijala.pdf: 8876096 bytes, checksum: a9348271868d9cc37d85ecf3800e67ff (MD5)<br/>Submitter:Made available in DSpace on 2013-12-18T09:39:44Z (GMT). No. of bitstreams: 1
maijala.pdf: 8876096 bytes, checksum: a9348271868d9cc37d85ecf3800e67ff (MD5)

Source: researchoutputwizard
Source ID: 123456789/21918

Research output: Book/ReportDoctoral thesisMonograph

A method of tracking a state of a mobile electronic device

General information

Publication status: Published
MoE publication type: H1 Granted patent
Organisations: Former organisation of the author
Contributors: Sirola, N., Ali-Löytty, S.
Publication date: 2011

Publication information

Patent number: Pat. KR 101106276
Priority date: 18/01/12
Priority number: 10-2008-7024373
Original language: Korean

Bibliographical note

h3tut > h1 : Pat.Appl.PCT/EP2006/002272(2006.03.07)<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7276

Research output: PatentScientific

A method to enforce map constraints in a particle filter's position estimate

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Piche, R., Koivisto, M.
Number of pages: 4
Publication date: 2014

Host publication information

Title of host publication: 2014 11th Workshop on Positioning, Navigation and Communication (WPNC), 12-13 March 2014, Dresden, Germany
Publisher: IEEE

Bibliographical note

Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2014-09-05<br/>Publisher name: IEEE

Source: researchoutputwizard
Source ID: 1274

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A Mixed Finite Element Method to Solve the EEG Forward Problem

Finite element methods have been shown to achieve high accuracies in numerically solving the EEG forward problem and they enable the realistic modeling of complex geometries and important conductive features such as anisotropic conductivities. To date, most of the presented approaches rely on the same underlying formulation, the continuous Galerkin (CG)-FEM. In this article, a novel approach to solve the EEG forward problem based on a mixed finite element method (Mixed-FEM) is introduced. To obtain the Mixed-FEM formulation, the electric current is introduced as an additional unknown besides the electric potential. As a consequence of this derivation, the Mixed-FEM is, by construction, current preserving, in contrast to the CG-FEM. Consequently, a higher simulation accuracy can be achieved in certain scenarios, e.g., when the diameter of thin insulating structures, such as the skull, is in the range of the mesh resolution. A theoretical derivation of the Mixed-FEM approach for EEG forward simulations is presented, and the algorithms implemented for solving the resulting equation systems are described. Subsequently, first evaluations in both sphere and realistic head models are presented, and the results are compared to previously introduced CG-FEM approaches. Additional visualizations are shown to illustrate the current preserving property of the Mixed-FEM. Based on these results, it is concluded that the newly presented Mixed-FEM can at least complement and in some scenarios even outperform the established CG-FEM approaches, which motivates a further evaluation of the Mixed-FEM for applications in bioelectromagnetism.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, University of Utah, Cluster of Excellence EXC, University of Münster
Contributors: Vorwerk, J., Engwer, C., Pursiainen, S., Wolters, C. H.
Number of pages: 12
Pages: 930-941
Publication date: 1 Apr 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Medical Imaging
Volume: 36
Issue number: 4
Article number: 7731161
ISSN (Print): 0278-0062
Ratings: 
  • Scopus rating (2017): CiteScore 6.6 SJR 1.895 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Software, Radiological and Ultrasound Technology, Computer Science Applications, Electrical and Electronic Engineering
Keywords: EEG, forward problem, mixed finite element method, realistic head modeling, source analysis
Source: Scopus
Source ID: 85017598893

Research output: Contribution to journalArticleScientificpeer-review

A Molecular Camera Gyroscope

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Huttunen, V., Piche, R.
Pages: 69-81
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Giroskopiya I Navigatsiya
Volume: 77
ISSN (Print): 0869-7035
Original language: Russian

Bibliographical note

Ei UT-numeroa 14.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Tsentral'nyi Nauchno-Issledovatel'skii Institut Elektropribor

Source: researchoutputwizard
Source ID: 4270

Research output: Contribution to journalArticleScientificpeer-review

A Monocular Camera Gyroscope

We present a method for tracking the 3-axis orientation of a monocular camera using orthogonal vanishing points detected in individual frames of a sequence of images. Robust and real-time vanishing point detection is done using a standard line segment detection method and an adaptive RANSAC algorithm. Vanishing points and corresponding vanishing directions found in consecutive frames are associated with each other to produce a sequence of orientation quaternions, which is processed by an extended Kalman filter. Experiments with a consumer-level, handheld mobile device indicate that the accuracy of the proposed method is comparable with those of consumer-grade inertial motion sensors.

General information

Publication status: Published
MoE publication type: D4 Published development or research report or study
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Huttunen, V., Piche, R.
Number of pages: 16
Publication date: 2011

Publication information

Place of publication: Tampere
Publisher: Tampereen teknillinen yliopisto
ISBN (Print): 978-952-15-2627-5
Original language: English

Publication series

Name: Tampereen teknillinen yliopisto. Matematiikan laitos. Tutkimusraportti
Publisher: Tampereen teknillinen yliopisto
Volume: 98

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6150

Research output: Book/ReportCommissioned reportProfessional

A Monocular Camera Gyroscope

We present a method for tracking the 3-axis orientation of a monocular camera using orthogonal vanishing points detected in individual frames of a sequence of images. Robust and real-time vanishing point detection is done using a standard line segment detection method and an adaptive RANSAC algorithm. Vanishing points and corresponding vanishing directions found in consecutive frames are associated with each other to produce a sequence of orientation quaternions, which is processed by an extended Kalman filter. Experiments with a consumer-level, handheld mobile device indicate that the accuracy of the proposed method is comparable with those of consumer-grade inertial motion sensors.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Huttunen, V., Piche, R.
Pages: 124-131
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Gyroscopy and Navigation
Volume: 3
Issue number: 2
ISSN (Print): 2075-1087
Ratings: 
  • Scopus rating (2012): CiteScore 0.34 SJR 0.247 SNIP 0.357
Original language: English

Bibliographical note

Ei UT-numeroa 14.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC

Source: researchoutputwizard
Source ID: 4271

Research output: Contribution to journalArticleScientificpeer-review

A motion model for articulated vehicles and a distributed acceleration measurement system

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Sirola, N., Rouhe, J.
Pages: 164-167
Publication date: 2010

Host publication information

Title of host publication: Proceedings of the 7th Workshop on Positioning, Navigation and Communication 2010 WPNC'10, 11-12 March 2010, Dresden, Germany
ISBN (Print): 978-1-4244-7157-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9290

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

An Adaptive Derivative Free Method for Bayesian Posterior Approximation

In the Gaussian mixture approach a Bayesian posterior probability distribution function is approximated using a weighted sum of Gaussians. This work presents a novel method for generating a Gaussian mixture by splitting the prior taking the direction of maximum nonlinearity into account. The proposed method is computationally feasible and does not require analytical differentiation. Tests show that the method approximates the posterior better with fewer Gaussian components than existing methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Ali-Löytty, S.
Pages: 87-90
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 19
Issue number: 2
Article number: 12436433
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2012): CiteScore 2.59 SJR 0.91 SNIP 2.041
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 5135

Research output: Contribution to journalArticleScientificpeer-review

An algebraic study of Peterson´s Intermediate Syllogisms

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research Community on Data-to-Decision (D2D)
Contributors: Turunen, E.
Number of pages: 14
Pages: 1-14
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Soft Computing
ISSN (Print): 1432-7643
Ratings: 
  • Scopus rating (2014): CiteScore 2.01 SJR 0.744 SNIP 1.499
Original language: English

Bibliographical note

Published online: 21 January 2014<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-04-29<br/>Publisher name: Springer

Source: researchoutputwizard
Source ID: 1660

Research output: Contribution to journalArticleScientificpeer-review

Analysing and Improving Student's Mathematics Skills using ICT-tools

In this paper the supportive actions taken at Tampere University of Technology (TUT) for the first year students in engineering mathematics are discussed. The measures include Basic Skill’s Test (BST), Mathematics Remedial Instruction (MRI), and student profiling based on students' attitudes on learning. Specially, we describe how MRI was implemented in Math-Bridge and carried out at TUT. The effects of MRI for different learner groups using success indicators, log file analysis, and statistical methods are presented and clarified using data visualization.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics, School of Ylöjärvi
Contributors: Pohjolainen, S., Nykänen, O., Venho, J., Kangas, J.
Number of pages: 7
Pages: 1221-1227
Publication date: 8 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: EURASIA JOURNAL OF MATHEMATICS, SCIENCE & TECHNOLOGY EDUCATION
Volume: 14
Issue number: 4
Article number: 14(4)
ISSN (Print): 1305-8223
Ratings: 
  • Scopus rating (2018): CiteScore 1.27
Original language: English
Keywords: Science education, Teacher education, Biology Education, Environmental education
Electronic versions: 

Research output: Contribution to journalArticleScientificpeer-review

Analysis of common rail pressure signal of dual-fuel large industrial engine for identification of injection duration of pilot diesel injectors

In this paper, we address the problem of identification of injection duration of common rail (CR) diesel pilot injectors of dual-fuel engines. In these pilot injectors, the injected volume is small and the repeatability of injections and identification of drifts of injectors are important factors, which need to be taken into account in order to achieve good repeatability (shot-to-shot with every cylinder) and therefore a well-balanced engine and furthermore reduced overall wear. This information can then be used for calibration and diagnostics purposes to guarantee engine longevity facilitated by consistent operating conditions throughout the life of the unit. A diagnostics method based on analysis of CR pressure with experimental results is presented in this paper. Using the developed method, the relative duration of injection events can be identified for multiple injectors. We use the phenomenon of drop in rail pressure due to an injection event as a feature of the injection process. The method is based on filtered CR pressure data during and after the injection event. First, the pressure signal during injection is extracted after control of each injection event. After that, the signal is normalized and filtered. Then a derivative of the filtered signal is calculated. Change in the derivative of the filtered signal larger than a predefined threshold indicates an injection event that can be detected and its relative duration can be identified. We present the experimental results and demonstrate the efficacy of the proposed methods using two different
types of pressure sensors. We are able to properly identify a change of ≥10 μs (2%, 500 μs) in injection time. This shows that the developed method detects drifts in injection duration and the magnitude of drift. This information can be used for adaptive control of injection duration, so that finally the injected fuel volume is the same as the original.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation and Hydraulic Engineering
Contributors: Krogerus, T., Hyvönen, M., Huhtala, K.
Pages: 1-9
Publication date: Mar 2018
Peer-reviewed: Yes
Early online date: 6 Dec 2017

Publication information

Journal: Fuel
Volume: 216
ISSN (Print): 0016-2361
Ratings: 
  • Scopus rating (2018): CiteScore 5.8 SJR 1.745 SNIP 2.012
Original language: English
ASJC Scopus subject areas: Mechanical Engineering, Signal Processing, Modelling and Simulation, Applied Mathematics
Keywords: Analysis , Dual-fuel engine , Diesel , Common rail , Injector , Rail pressure
Electronic versions: 
URLs: 

Research output: Contribution to journalArticleScientificpeer-review

Analysis of geometric primitives in quantitative structure models of tree stems

One way to model a tree is to use a collection of geometric primitives to represent the surface and topology of the stem and branches of a tree. The circular cylinder is often used as the geometric primitive, but it is not the only possible choice. We investigate various geometric primitives and modelling schemes, discuss their properties and give practical estimates for expected modelling errors associated with the primitives. We find that the circular cylinder is the most robust primitive in the sense of a well-bounded volumetric modelling error, even with noise and gaps in the data. Its use does not cause errors significantly larger than those with more complex primitives, while the latter are much more sensitive to data quality. However, in some cases, a hybrid approach with more complex primitives for the stem is useful.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Inverse Problems, Mathematical modelling with wide societal impact (MathImpact), Centre for Sustainable Forestry and Climate Change, Forest Research
Contributors: Åkerblom, M., Raumonen, P., Kaasalainen, M., Casella, E.
Number of pages: 23
Pages: 4581-4603
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing
Volume: 7
Issue number: 4
ISSN (Print): 2072-4292
Ratings: 
  • Scopus rating (2015): CiteScore 3.76 SJR 1.349 SNIP 1.682
Original language: English
ASJC Scopus subject areas: Earth and Planetary Sciences(all)
Keywords: Biomass estimation, Error analysis, Shape fitting, Terrestrial laser scanning, Tree modelling
Source: Scopus
Source ID: 84937899906

Research output: Contribution to journalArticleScientificpeer-review

Analysis of Incidence Angle and Distance Effects on Terrestrial Laser Scanner Intensity: Search for Correction Methods

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Kaasalainen, S., Jaakkola, A., Kaasalainen, M., Krooks, A., Kukko, A.
Pages: 2207-2221
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing
Volume: 3
Issue number: 10
ISSN (Print): 2072-4292
Ratings: 
  • Scopus rating (2011): CiteScore 1.3 SJR 0.533 SNIP 1.323
Original language: English

Bibliographical note

Otsikko alunperin: Analysis of topographic and distance effects on TLS intensity: Search for correction methods<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6256

Research output: Contribution to journalArticleScientificpeer-review

Analysis of the rotation period of asteroids (1865) Cerberus, (2100) Ra-Shalom, and (3103) Eger - search for the YORP effect

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Durech, J., Vokrouhlicky, D., Baransky, A., Breiter, S., Burkhonov, O., Cooney, W., Fuller, V., Gaftonyuk, N., Gross, J., Inasaridze, R., Kaasalainen, M., Krugly, Y., Kvaratshelia, O., Litvinenko, E., Macomber, B., Marchis, F., Molotov, I., Oey, J., Polishook, D., Pollock, J., Pravec, P., Sarneczky, K., Shevchenko, V., Slyusarev, I., Stephens, R., Szabo, G., Terrell, D., Vachier, F., Vanderplate, Z., Viikinkoski, M., Warner, B.
Pages: 9
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 547
Article number: A10
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2012): CiteScore 3.14 SJR 2.903 SNIP 1.425
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: EDP Sciences

Source: researchoutputwizard
Source ID: 4017

Research output: Contribution to journalArticleScientificpeer-review

Analytics of the impact of user involvement in the innovation process and its outcomes. Case study: Media-Enhanced Learning (MEL) Service

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Still, K., Huhtamäki, J., Isomursu, M., Lahti, J., Koskela-Huotari, K.
Pages: 1740-1746
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Procedia: Social and Behavioral Sciences
Volume: 46
ISSN (Print): 1877-0428
Ratings: 
  • Scopus rating (2012): SJR 0.222 SNIP 0.23
Original language: English

Bibliographical note

4th World Conference on Educational Sciences, WCES 2012, 2-5 February 2012, Barcelona, Spain<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Elsevier

Source: researchoutputwizard
Source ID: 5355

Research output: Contribution to journalArticleScientificpeer-review

An architectural understanding of natural sway frequencies in trees

The relationship between form and function in trees is the subject of a longstanding debate in forest ecology and provides the basis for theories concerning forest ecosystem structure and metabolism. Trees interact with the wind in a dynamic manner and exhibit natural sway frequencies and damping processes that are important in understanding wind damage. Tree-wind dynamics are related to tree architecture, but this relationship is not well understood. We present a comprehensive view of natural sway frequencies in trees by compiling a dataset of field measurement spanning conifers and broadleaves, tropical and temperate forests. The field data show that a cantilever beam approximation adequately predicts the fundamental frequency of conifers, but not that of broadleaf trees. We also use structurally detailed tree dynamics simulations to test fundamental assumptions underpinning models of natural frequencies in trees. We model the dynamic properties of greater than 1000 trees using a finite-element approach based on accurate three-dimensional model trees derived from terrestrial laser scanning data. We show that (1) residual variation, the variation not explained by the cantilever beam approximation, in fundamental frequencies of broadleaf trees is driven by their architecture; (2) slender trees behave like a simple pendulum, with a single natural frequency dominating their motion, which makes them vulnerable to wind damage and (3) the presence of leaves decreases both the fundamental frequency and the damping ratio. These findings demonstrate the value of new three-dimensional measurements for understanding wind impacts on trees and suggest new directions for improving our understanding of tree dynamics from conifer plantations to natural forests.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, University of Oxford, SCION, University of Connecticut, Delft University of Technology, Wageningen University and Research Centre, University of Massachusetts Amherst, National Parks Board, University of Melbourne, Oregon State University, Universiteit Gent, National Physical Laboratory, University College London, NERC National Centre for Earth Observation (NCEO), 16 Center for International Forestry Research (CIFOR), Swedish University of Agricultural Sciences, INRA
Contributors: Jackson, T., Shenkin, A., Moore, J., Bunce, A., van Emmerik, T., Kane, B., Burcham, D., James, K., Selker, J., Calders, K., Origo, N., Disney, M., Burt, A., Wilkes, P., Raumonen, P., Gonzalez de Tanago Menaca, J., Lau, A., Herold, M., Goodman, R. C., Fourcaud, T., Malhi, Y.
Number of pages: 1
Publication date: 28 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of the Royal Society. Interface
Volume: 16
Issue number: 155
ISSN (Print): 1742-5689
Original language: English
ASJC Scopus subject areas: Biotechnology, Biophysics, Bioengineering, Biomaterials, Biochemistry, Biomedical Engineering
Keywords: finite-element analysis, fundamental frequency, natural frequencies, terrestrial laser scanning, tree architecture, wind damage
Source: Scopus
Source ID: 85067464325

Research output: Contribution to journalArticleScientificpeer-review

An empirical solar radiation pressure model for autonomous GNSS orbit prediction

GNSS satellite orbits can be predicted by integrating the satellites’ equation of motion. If the prediction is done in a consumer grade positioning device, a simplified version of the equation of motion is required. The forces due to Earth’s gravitation, solar gravitation and lunar gravitation should be included, but the models for the smaller non-gravitational forces can be fairly simple. This paper presents a simple empirical two parameter solar radiation pressure model for an orbit prediction application in a navigation device that does not have a network connection. The model is tested by predicting the orbits of GPS and GLONASS satellites up to 5 days into the future, using position and improved velocity from broadcast ephemerides as an initial state. The predicted orbits are compared to the precise orbits from International GNSS Service (IGS).

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Ala-Luhtala, J., Seppänen, M., Piche, R.
Pages: 568-575
Publication date: 2012

Host publication information

Title of host publication: 2012 IEEE/ION Position Location and Navigation Symposium PLANS, 23-26 April 2012, Myrtle Beach, SC, USA
Place of publication: Piscataway, NJ
Publisher: Institute of Electrical and Electronics Engineers IEEE
Article number: 12863831
ISBN (Print): 978-1-4673-0385-9

Publication series

Name: IEEE/ION Position Location and Navigation Symposium
ISSN (Print): 2153-358X
ISSN (Electronic): 2153-3598

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 3836

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A Network-Centric Snapshot of Value Co-Creation in Finnish Innovation Financing

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Huhtamäki, J., Russell, M. G., Still, K., Rubens, N.
Number of pages: 15
Pages: 1-15
Publication date: 2011

Host publication information

Title of host publication: EBRF 2010, Research Forum to Understand Business in Knowledge Society, September 15-17, 2010, Nokia, Finland
Place of publication: Nokia
Publisher: GVL Finland
Editors: Seppä, M., Helander, N., Ilvonen, I.
ISBN (Print): 978-952-15-2529-2

Publication series

Name: Research Forum to Understand Business in Knowledge Society EBRF
Publisher: GVL Finland
ISSN (Print): 1797-190X

Bibliographical note

ei ut-numeroa 8.3.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 6112

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A Network-Centric Snapshot of Value Co-Creation in Finnish Innovation Financing

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Huhtamäki, J., Russell, M. G., Still, K., Rubens, N.
Pages: 13-21
Publication date: 2011

Host publication information

Title of host publication: The Open Source Business Resource
Publisher: Talent First Network
Editors: McPhee, C., Seppä, M., Tanev, S.

Bibliographical note

ei ut-numeroa 8.3.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 6110

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

A New Cauchy Type Integral Formula for Quaternionic k-hypermonogenic Functions

In complex function theory holomorphic functions are conjugate gradient of real harmonic functions. We may build function theories in higher dimensions based on this idea if we generalize harmonic functions and define the conjugate gradient operator. We study this type of function theory in R3 connected to harmonic functions with respect to the Laplace–Beltrami operator of the Riemannian metric ds2=x−2k2(∑2i=0dx2i). The domain of the definition of our functions is in R3 and the image space is the associative algebra of quaternions H generated by 1, e1, e2 and e12 = e1e2 satisfying the relation e i e j + e j e i = –2δ ij , i, j = 1, 2. The complex field C is identified by the set {x0+x1e1|x0,x1εB}. The conjugate gradient is defined in terms of modified Dirac operator, introduced by Mkf=Df+kx−12Qf¯¯¯¯¯¯¯, where Qf is given by the decomposition f (x) = Pf (x) + Qf (x) e2 with Pf (x) and Qf (x) in C and Qf¯¯¯¯¯¯¯ is the usual complex conjugation.

Leutwiler noticed around 1990 that if the usual Euclidean metric is changed to the hyperbolic metric of the Poincaré upper half-space model (k = 1), then the power function (x0 + x1e1 + x2e2) n , calculated using quaternions, is the conjugate gradient of the a hyperbolic harmonic function. We study functions, called k-hypermonogenic, satisfying M k f = 0. Monogenic functions are 0-hypermonogenic. Moreover, 1-hypermonogenic functions are hypermonogenic defined by H. Leutwiler and the first author.

We prove a new Cauchy type integral formulas for k-hypermonogenic functions where the kernels are calculated using the hyperbolic distance and are k-hypermonogenic functions. This formula gives the known formulas in case of monogenic and hypermonogenic functions. It also produces new Cauchy and Teodorescu type integral operators investigated in the future research.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, University of Helsinki
Contributors: Eriksson, S., Orelma, H.
Number of pages: 15
Pages: 175-189
Publication date: 23 Nov 2016

Host publication information

Title of host publication: Modern Trends in Hypercomplex Analysis
Publisher: Springer International Publishing
Editors: Bernstein, S., Kähler, U., Sabadini, I., Sommen, F.
ISBN (Print): 978-3-319-42528-3
ISBN (Electronic): 978-3-319-42529-0

Publication series

Name: Trends in Mathematics
ISSN (Electronic): 2297-0215

Bibliographical note

EXT="Eriksson, Sirkka-Liisa"

Source: RIS
Source ID: Eriksson2016

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A New Characterization for n-Fold Positive Implicative BL-logics

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research Community on Data-to-Decision (D2D)
Contributors: Turunen, E., Tchikapa, N., Lele, C.
Pages: 552-560
Publication date: 2012

Host publication information

Title of host publication: Advances on Computational Intelligence 14th International Conference on Information Processing and Management of Uncertainty in Knowledge-Based Systems, IPMU 2012, Catania, Italy, July 9-13, 2012. Proceedings, Part I. Communications in Computer and Information Science
Place of publication: Berlin Heidelberg
Publisher: Springer
Editors: Greco, S., Bouchon-Meunier, B., Coletti, G., Fedrizzi, M., Matarazzo, B., Yager, R. R.
ISBN (Print): 978-3-642-31708-8
ISBN (Electronic): 978-3-642-31709-5

Publication series

Name: International Conference on Information Processing and Management of Uncertainty in Knowledge-Based Systems
Volume: 297
ISSN (Print): 1865-0929
ISSN (Electronic): 1865-0937

Bibliographical note

ei ut-numeroa 21.9.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Springer

Source: researchoutputwizard
Source ID: 5463

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A New Controller Structure for Robust Output Regulation

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Paunonen, L., Pohjolainen, S.
Number of pages: 6
Pages: 4721-4726
Publication date: 2014

Host publication information

Title of host publication: Proceedings of the 53rd IEEE Conference on Decision and Control, IEEE CDC 2014, 15-17 December, 2014, Los Angeles, CA, USA
Publisher: IEEE
ISBN (Print): 978-1-4673-6088-3

Publication series

Name: IEEE Conference on Decision and Control

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-12-18<br/>Publisher name: IEEE

Source: researchoutputwizard
Source ID: 1243

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A New Method and Format for Describing CANopen System Topology

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Department of Intelligent Hydraulics and Automation, Department of Mathematics
Contributors: Helminen, M., Salonen, J., Saha, H., Nykänen, O., Koskinen, K. T., Ranta, P., Pohjolainen, S.
Number of pages: 8
Pages: 1-8
Publication date: 2012

Host publication information

Title of host publication: Proceedings of the 13th International CAN Conference, iCC 2012 in Hambach Castle, March 5 to March 6, Germany
Publisher: CAN in Automation e.V.

Publication series

Name: International CAN Conference

Bibliographical note

ei ut-numeroa 13.8.2013<br/>Contribution: organisation=iha,FACT1=0.6<br/>Contribution: organisation=mat,FACT2=0.4<br/>Publisher name: CAN in Automation e.V.

Source: researchoutputwizard
Source ID: 4211

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

An implementation of a semantic, web-based virtual machine laboratory prototyping environment

Creation of virtual machine laboratories – simulated planning and learning environments demonstrating function and structure of working machines – often involve a lot of manual labor. A notable source of the labor is the programming required due to changes in structural and functional models of a system. As a result, rapid prototyping of a virtual machine laboratory becomes difficult, if not impossible. We argue that by using a combination of semantic modeling and prototyping with a web-based system, more rapid development of virtual machine laboratories can be achieved. In this paper, we present the design and implementation of a semantic, web-based virtual machine laboratory prototyping environment. Application of the environment to a case example is also described and discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Intelligent Hydraulics and Automation, Department of Mathematics
Contributors: Salonen, J., Nykänen, O., Ranta, P., Nurmi, J., Helminen, M., Rokala, M., Palonen, T., Alarotu, V., Koskinen, K., Pohjolainen, S.
Pages: 221-236
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Lecture Notes in Computer Science
Volume: 7032
ISSN (Print): 0302-9743
Ratings: 
  • Scopus rating (2011): CiteScore 0.49 SJR 0.338 SNIP 0.765
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=0.5<br/>Contribution: organisation=iha,FACT2=0.5

Source: researchoutputwizard
Source ID: 7197

Research output: Contribution to journalArticleScientificpeer-review

A NLOS-robust TOA positioning filter based on a skew-t measurement noise model

A skew-t variational Bayes filter (STVBF) is applied to indoor positioning with time-of-arrival (TOA) based distance measurements and pedestrian dead reckoning (PDR). The proposed filter accommodates large positive outliers caused by occasional non-line-of-sight (NLOS) conditions by using a skew-t model of measurement errors. Real-data tests using the fusion of inertial sensors based PDR and ultra-wideband based TOA ranging show that the STVBF clearly outperforms the extended Kalman filter (EKF) in positioning accuracy with the computational complexity about three times that of the EKF.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Nurminen, H., Ardeshiri, T., Piche, R., Gustafsson, F.
Number of pages: 7
Pages: 1-7
Publication date: 1 Oct 2015

Host publication information

Title of host publication: 2015 International Conference on Indoor Positioning and Indoor Navigation (IPIN)
Publisher: IEEE
ISBN (Print): 978-1-4673-8402-5
Keywords: Approximation methods, Computational modeling, Distance measurement, Gaussian distribution, Measurement errors, Noise measurement, Position measurement, NLOS, TOA, UWB, indoor positioning, robust filtering, skew t, skewness, variational Bayes
Electronic versions: 
Source: Bibtex
Source ID: urn:e960458d3c3e7f01508ed799f1fbe96d

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A note on compactness in a fuzzy metric space

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Kaleva, O., Kauhanen, J.
Number of pages: 5
Pages: 135-139
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
Article number: 238
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2013): CiteScore 2.55 SJR 1.342 SNIP 2.089
Original language: English

Bibliographical note

In Press, Corrected Proof.Accepted 29 May 2013.<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-10-29

Source: researchoutputwizard
Source ID: 2467

Research output: Contribution to journalArticleScientificpeer-review

Another paraconsistent algebraic semantics for Lukasiewicz-Pavelka logic

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research Community on Data-to-Decision (D2D)
Contributors: Rodriguez, J. T., Turunen, E., Ruan, D., Montero, J.
Number of pages: 16
Pages: 132-147
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
Volume: 242
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2014): CiteScore 2.67 SJR 1.369 SNIP 2.194
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-09-30<br/>Publisher name: Elsevier BV

Source: researchoutputwizard
Source ID: 1390

Research output: Contribution to journalArticleScientificpeer-review

A Notion of Positive Definiteness for Arithmetical Functions

In the theory of Fourier transform some functions are said to be positive definite based on the positive definiteness property of a certain class of matrices associated with these functions. In the present article we consider how to define a similar positive definiteness property for arithmetical functions, whose domain is not the set of real numbers but merely the set of positive integers. After finding a suitable definition for this concept we shall use it to construct a partial ordering on the set of arithmetical functions. We shall study some of the basic properties of our newly defined relations and consider a couple of well-known arithmetical functions as examples.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Tampere University
Contributors: Mattila, M., Haukkanen, P.
Number of pages: 14
Pages: 61-74
Publication date: 2019

Host publication information

Title of host publication: Matrices, Statistics and Big Data : Selected Contributions from IWMS 2016
Publisher: Springer Nature
Editors: Ahmed, S. E., Carvalho, F., Puntanen, S.
ISBN (Print): 978-3-030-17518-4
ISBN (Electronic): 978-3-030-17519-1

Publication series

Name: Contributions to Statistics
ISSN (Print): 1431-1968

Bibliographical note

jufoid=84299

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Antichain Cutsets of Strongly Connected Posets

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Foldes, S., Woodroofe, R.
Number of pages: 11
Pages: 351-361
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Order: A Journal on the Theory of Ordered Sets and Its Applications
Volume: 30
Issue number: 2
ISSN (Print): 0167-8094
Ratings: 
  • Scopus rating (2013): CiteScore 0.59 SJR 0.666 SNIP 1.133
Original language: English

Bibliographical note

Online first.Poistettu Portfolio13:sta tupla r=2900.<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Springer Netherlands

Source: researchoutputwizard
Source ID: 2143

Research output: Contribution to journalArticleScientificpeer-review

A Partial Internal Model for Approximate Robust Output Regulation of Boundary Control Systems

Introduced for finite-dimensional systems by Fran- cis and Wonham in the mid 70’s, the internal model principle states that a stabilizing controller achieves asymptotic output tracking and disturbance rejection robustly if and only if it contains a p-copy of the exosystem frequencies, where p is the dimension of the output space of the plant. Later, the internal model principle has been extended, e.g., to boundary control systems on multidimensional spatial domains, and in this setting it follows from the principle that every robust output regulator is necessarily infinite-dimensional. However, it was recently established by the authors that robust approximate output tracking can be achieved with a finite-dimensional controller, and in the present paper, we formulate an internal model for this purpose. The efficiency of the method is numerically demonstrated using the heat equation on the unit square in $\mathbb{R}^2$ with boundary control and boundary observation.

General information

Publication status: Published
MoE publication type: D3 Professional conference proceedings
Organisations: Mathematics, Research group: Computer Science and Applied Logics, Åbo Akademi University
Contributors: Humaloja, J., Paunonen, L., Kurula, M.
Number of pages: 6
Pages: 586-591
Publication date: 20 Jul 2018

Host publication information

Title of host publication: 23rd International Symposium on Mathematical Theory of Networks and Systems
Electronic versions: 

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Aperture size effects on backscatter intensity measurements in Earth and space remote sensing

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Kaasalainen, M., Kaasalainen, S.
Pages: 1142-1146
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Journal of the Optical Society of America A: Optics Image Science and Vision
Volume: 25
Issue number: 5
ISSN (Print): 1084-7529
Ratings: 
  • Scopus rating (2008): SJR 1.464 SNIP 1.509
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 12424

Research output: Contribution to journalArticleScientificpeer-review

A portrait of the nucleus of comet 67P

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Lamy, P., Toth, I., Davidsson, B., Groussin, O., Gutierrez, P., Jorda, L., Kaasalainen, M., Lowry, S.
Pages: 23-66
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Space Science Reviews
Volume: 128
Issue number: 1-4
ISSN (Print): 0038-6308
Ratings: 
  • Scopus rating (2006): SJR 2.306 SNIP 1.374
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 16896

Research output: Contribution to journalArticleScientificpeer-review

Apparent wind load effects on the tether of a kite power generator

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Argatov, I., Rautakorpi, P., Silvennoinen, R.
Pages: 1079-1088
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Wind Engineering and Industrial Aerodynamics
Volume: 99
Issue number: 10
ISSN (Print): 0167-6105
Ratings: 
  • Scopus rating (2011): CiteScore 2.3 SJR 0.902 SNIP 3.332
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5719

Research output: Contribution to journalArticleScientificpeer-review

Application and Theory of Petri Nets and Concurrency: 36th International Conference, PETRI NETS 2015 Brussels, Belgium, June 21-26, 2015 Proceedings

General information

Publication status: Published
MoE publication type: C2 Edited books
Organisations: Department of Mathematics, Research group: MAT Computer Science and Applied Logics, Regulation of learning and active learning methods (REALMEE), Embedded Electronics research unit of the Bio Electro and Mechanical Systems (BEAMS) department of the Université Libre de Bruxelles
Contributors: Devillers, R. (ed.), Valmari, A. (ed.)
Publication date: 2015

Publication information

Publisher: Springer Verlag
Volume: 9115
ISBN (Print): 978-3-319-19487-5
ISBN (Electronic): 978-3-319-19488-2
Original language: English

Publication series

Name: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume: 9115
ISSN (Print): 0302-9743
ISSN (Electronic): 1611-3349
ASJC Scopus subject areas: Computer Science(all), Theoretical Computer Science

Bibliographical note

JUFOID=62555

Source: Scopus
Source ID: 84937510301

Research output: Book/ReportAnthologyScientificpeer-review

Application and theory of Petri nets and other models of concurrency: Special issue of selected papers from Petri Nets 2015

General information

Publication status: Published
MoE publication type: B1 Article in a scientific magazine
Organisations: Department of Mathematics, Research group: MAT Computer Science and Applied Logics
Contributors: Devillers, R., Valmari, A., Penczek, W.
Pages: v-vi
Publication date: 13 Sep 2016
Peer-reviewed: No

Publication information

Journal: Fundamenta Informaticae
Volume: 146
Issue number: 1
ISSN (Print): 0169-2968
Ratings: 
  • Scopus rating (2016): CiteScore 0.86 SJR 0.371 SNIP 0.712
Original language: English
ASJC Scopus subject areas: Theoretical Computer Science, Algebra and Number Theory, Information Systems, Computational Theory and Mathematics
Source: Scopus
Source ID: 84988662462

Research output: Contribution to journalEditorialScientific

Application of Design Review to Probabilistic Risk Assessment in a Large Investment Project

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mechanical Engineering and Industrial Systems
Contributors: Virtanen, S., Penttinen, J., Kiiski, M., Jokinen, J.
Number of pages: 12
Pages: 1-12
Publication date: 2014

Host publication information

Title of host publication: Proceedings of the Probabilistic Safety Assessment and Management PSAM12, June 2014, Honolulu, Hawaii

Bibliographical note

Contribution: organisation=mei,FACT1=1<br/>Portfolio EDEND: 2014-12-13

Source: researchoutputwizard
Source ID: 1754

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Application of Hill-Clohessy-Wiltshire Equation in GNSS Orbit Prediction

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Research group: Positioning, Wireless Communications and Positioning (WICO), Automation and Hydraulic Engineering, Department of Automation Science and Engineering
Contributors: Zhang, X., Piche, R.
Number of pages: 6
Pages: 1-6
Publication date: 2014

Host publication information

Title of host publication: Proceedings of 2014 International Conference on Localization and GNSS (ICL-GNSS), Helsinki, Finland, June 24-26, 2014
Place of publication: Piscataway
Publisher: IEEE
Editors: Nurmi, J., Ruotsalainen, L., Lohan, E., Salcedo, J., Thombre, S.
ISBN (Print): 978-1-4799-5122-2

Bibliographical note

Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2014-10-30

Source: researchoutputwizard
Source ID: 1844

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Application of terrestrial LiDAR and modelling of tree branching structure for plant- scaling models in tropical forest trees

General information

Publication status: Published
MoE publication type: D3 Professional conference proceedings
Organisations: Department of Mathematics, Research group: MAT Inverse Problems, Wageningen University and the UNESCO-IHE Institute for Water Education, Delft, The Netherlands, 18.10.2013
Contributors: Lau Sarmiento, A., Bartholomeus, H., Herold, M., Martius, C., Malhi, Y., Patrick Bentley, L., Shenkin, A., Raumonen, P.
Number of pages: 3
Pages: 96-98
Publication date: 2015

Host publication information

Title of host publication: Proceedings of SilviLaser 2015 : 14th conference on Lidar Applications for Assessing and Managing Forest Ecosystems

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Applications of Spatially Localized Active-Intensity Vectors for Sound-Field visualization

This article details and evaluates three alternative approaches to sound-field visualization, which all employ the use of spatially-localized active-intensity (SLAI) vectors. SLAI vectors are particularly interesting as they allow direction-of-arrival (DoA) estimates to be extracted in multiple spatially-localized sectors, such that sound sources and/or noise present in one sector has reduced influence on the DoA estimate made in the other sectors. These DoA estimates may then be used to visualize the sound-field by either: i) directly depicting the estimates as icons, with their relative size dictated by the corresponding energy of each sector; ii) generating traditional activity-maps via histogram analysis of the DoA estimates; or iii) by using the DoA estimates to re-assign energy and subsequently sharpen traditional beamformer-based activity-maps. Since SLAI-based DoA estimates are continuous, these approaches are inherently computationally efficient, as they forgo the need for dense scanning grids to attain high-resolution imaging.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Aalto University, Department of Signal Processing and Acoustics, University of Crete, University of Parma
Contributors: McCormack, L., Delikaris-Manias, S., Politis, A., Pavlidi, D., Farina, A., Pinardi, D., Pulkki, V.
Pages: 840-854
Publication date: 22 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of the Audio Engineering Society
Volume: 67
Issue number: 11
ISSN (Print): 1549-4950
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Approach for Investigating Crowdfunding Campaigns with Platform Data: Case Indiegogo

Crowdfunding via the internet is a relatively new phenomenon in
research and gaining momentum currently. While taking a data-
driven approach into investigating the properties and dynamics of
crowdfunding campaigns would allow the use of computational
social science in investigations on crowdfunding, existing data-
driven research on crowdfunding remains very limited. This is
particularly true on the level of individual funder data. In this
study, we contribute to the empirical body of knowledge on
crowdfunding by introducing Indiegogo as a data source and,
more specifically, the development and implementation of a
crawler and scraper for accessing Indiegogo campaign data, and
sharing this openly for other researchers. Due to the extremely
dynamic and rapidly increasing amount of crowdfunding data in
terms of the number of crowdfunding campaigns and the available
investment and individual investor data, we believe our approach
is useful for supporting public and open data-driven research,
instead of providing merely a static data set.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory, Department of Information Management and Logistics, Research group: Novi, Managing digital industrial transformation (mDIT), Copenhagen Business School
Contributors: Huhtamäki, J., Lasrado, L., Menon, K., Kärkkäinen, H., Jussila, J.
Number of pages: 8
Publication date: 2015

Host publication information

Title of host publication: Academic MindTrek’15 : September 22-24, 2015, Tampere, Finland
Publisher: ACM
ISBN (Print): 978-1-4503-3948-3
Keywords: Crowdfunding, Data Extraction, Indiegogo, entrepreneur, crawling, scraping, computational social science

Bibliographical note

ORG=mat,0.5
ORG=tlo,0.5

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Approximate Bayesian inference methods for stochastic state space models

This thesis collects together research results obtained during my doctoral studies related to approximate Bayesian inference in stochastic state-space models. The published research spans a variety of topics including 1) application of Gaussian filtering in satellite orbit prediction, 2) outlier robust linear regression using variational Bayes (VB) approximation, 3) filtering and smoothing in continuous-discrete Gaussian models using VB approximation and 4) parameter estimation using twisted particle filters. The main goal of the introductory part of the thesis is to connect the results to the general framework of estimation of state and model parameters and present them in a unified manner.

Bayesian inference for non-linear state space models generally requires use of approximations, since the exact posterior distribution is readily available only for a few special cases. The approximation methods can be roughly classified into to groups: deterministic methods, where the intractable posterior distribution is approximated from a family of more tractable distributions (e.g. Gaussian and VB approximations), and stochastic sampling based methods (e.g. particle filters). Gaussian approximation refers to directly approximating the posterior with a Gaussian distribution, and can be readily applied for models with Gaussian process and measurement noise. Well known examples are the extended Kalman filter and sigma-point based unscented Kalman filter. The VB method is based on minimizing the Kullback-Leibler divergence of the true posterior with respect to the approximate distribution, chosen from a family of more tractable simpler distributions.

The first main contribution of the thesis is the development of a VB approximation for linear regression problems with outlier robust measurement distributions. A broad family of outlier robust distributions can be presented as an infinite mixture of Gaussians, called Gaussian scale mixture models, and include e.g. the t-distribution, the Laplace distribution and the contaminated normal distribution. The VB approximation for the regression problem can be readily extended to the estimation of state space models and is presented in the introductory part.

VB approximations can be also used for approximate inference in continuous-discrete Gaussian models, where the dynamics are modeled with stochastic differential equations and measurements are obtained at discrete time instants. The second main contribution is the presentation of a VB approximation for these models and the explanation of how the resulting algorithm connects to the Gaussian filtering and smoothing framework.

The third contribution of the thesis is the development of parameter estimation using particle Markov Chain Monte Carlo (PMCMC) method and twisted particle filters. Twisted particle filters are obtained from standard particle filters by applying a special weighting to the sampling law of the filter. The weighting is chosen to minimize the variance of the marginal likelihood estimate, and the resulting particle filter is more efficient than conventional PMCMC algorithms. The exact optimal weighting is generally not available, but can be approximated using the Gaussian filtering and smoothing framework.

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Mathematics
Contributors: Ala-Luhtala, J.
Number of pages: 56
Publication date: 23 Feb 2018

Publication information

Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-4091-2
ISBN (Electronic): 978-952-15-4106-3
Original language: English

Publication series

Name: Tampere University of Technology. Publication
Volume: 1528
ISSN (Print): 1459-2045

Research output: Book/ReportDoctoral thesisCollection of Articles

Approximate Controllability for Navier–Stokes Equations in 3D Rectangles Under Lions Boundary Conditions

The 3D Navier–Stokes system, under Lions boundary conditions, is proven to be approximately controllable provided a suitable saturating set does exist. An explicit saturating set for 3D rectangles is given.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Johann Radon Institute for Computational and Applied Mathematics
Contributors: Phan, D., Rodrigues, S. S.
Number of pages: 26
Pages: 351-376
Publication date: Jul 2019
Peer-reviewed: Yes
Early online date: 10 Jul 2018

Publication information

Journal: Journal of Dynamical and Control Systems
Volume: 25
Issue number: 3
ISSN (Print): 1079-2724
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Algebra and Number Theory, Numerical Analysis, Control and Optimization
Keywords: Approximate controllability, Navier–Stokes equations, Saturating set
Source: Scopus
Source ID: 85049619310

Research output: Contribution to journalArticleScientificpeer-review

Approximation of Volume and Branch Size Distribution of Trees from Laser Scanner Data

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Raumonen, P., Kaasalainen, S., Kaasalainen, M., Kaartinen, H.
Number of pages: 6
Pages: 1-6
Publication date: 2011

Host publication information

Title of host publication: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, ISPRS Workshop Laser Scanning, 2011, 29.-31.8.2011, Calgary, Canada
Place of publication: Calgary
Publisher: ISPRS

Publication series

Name: ISPRS Workshop Laser Scanning
Publisher: ISPRS
Volume: 38-5/W12
ISSN (Print): 1682-1750

Bibliographical note

ei ut-numeroa 3.5.2014<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7105

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Approximative solutions to the bicriterion Vechile Routing Problem with Time Windows

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Muller, J.
Pages: 223-231
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: European Journal of Operational Research
Volume: 202
Issue number: 1
ISSN (Print): 0377-2217
Ratings: 
  • Scopus rating (2010): SJR 2.383 SNIP 2.445
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8814

Research output: Contribution to journalArticleScientificpeer-review

A realistic, accurate and fast source modeling approach for the EEG forward problem

The aim of this paper is to advance electroencephalography (EEG) source analysis using finite element method (FEM) head volume conductor models that go beyond the standard three compartment (skin, skull, brain) approach and take brain tissue inhomogeneity (gray and white matter and cerebrospinal fluid) into account. The new approach should enable accurate EEG forward modeling in the thin human cortical structures and, more specifically, in the especially thin cortices in children brain research or in pathological applications. The source model should thus be focal enough to be usable in the thin cortices, but should on the other side be more realistic than the current standard mathematical point dipole. Furthermore, it should be numerically accurate and computationally fast. We propose to achieve the best balance between these demands with a current preserving (divergence conforming) dipolar source model. We develop and investigate a varying number of current preserving source basis elements n (n=1,…,n=5). For validation, we conducted numerical experiments within a multi-layered spherical domain, where an analytical solution exists. We show that the accuracy increases along with the number of basis elements, while focality decreases. The results suggest that the best balance between accuracy and focality in thin cortices is achieved with n=4 (or in extreme cases even n=3) basis functions, while in thicker cortices n=5 is recommended to obtain the highest accuracy. We also compare the current preserving approach to two further FEM source modeling techniques, namely partial integration and St. Venant, and show that the best current preserving source model outperforms the competing methods with regard to overall balance. For all tested approaches, FEM transfer matrices enable high computational speed. We implemented the new EEG forward modeling approaches into the open source duneuro library for forward modeling in bioelectromagnetism to enable its broader use by the brain research community. This library is build upon the DUNE framework for parallel finite elements simulations and integrates with high-level toolboxes like FieldTrip. Additionally, an inversion test has been implemented using the realistic head model to demonstrate and compare the differences between the aforementioned source models.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Signal Processing, Research group: Inverse Problems, University of Münster, University of Eastern Finland, Laboratory of Signal Processing
Contributors: Miinalainen, T., Rezaei, A., Us, D., Nüßing, A., Engwer, C., Wolters, C. H., Pursiainen, S.
Number of pages: 12
Pages: 56-67
Publication date: 2019
Peer-reviewed: Yes
Early online date: 28 Aug 2018

Publication information

Journal: NeuroImage
Volume: 184
Issue number: 1
ISSN (Print): 1053-8119
Original language: English
ASJC Scopus subject areas: Neurology, Cognitive Neuroscience
Keywords: Divergence conforming vector fields, DUNE toolbox, Electroencephalography (EEG), Finite element method (FEM), Focal sources
Source: Scopus
Source ID: 85053387965

Research output: Contribution to journalArticleScientificpeer-review

A Reduced-Order Two-Degree-of-Freedom Composite Nonlinear Feedback Control for a Rotary DC Servo Motor

We study in this paper nonlinear control of a rotary DC servo motor application. To be more specific, we design a reduced-order two-degree-of-freedom (2DOF) composite nonlinear feedback (CNF) controller for a Quanser QUBE-Servo 2 unit with a disc attachment. We compare our results with a carefully tuned proportional-derivative (PD) controller with set point weighting. Our simulation and experimental results show that the closed-loop system using 2DOF CNF controller yields much better set point tracking performance compared with the system using conventional PD-controller in terms of settling time.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Automation and Hydraulic Engineering, Research area: Information Systems in Automation, Research area: Dynamic Systems, Research area: Information Systems in Automation
Contributors: Pyrhönen, V., Koivisto, H., Vilkko, M.
Number of pages: 7
Pages: 2065-2071
Publication date: 12 Dec 2017

Host publication information

Title of host publication: Proceedings of the 56th IEEE Conference on Decision and Control
Place of publication: Melbourne, Australia
ISBN (Electronic): 978-1-5090-2872-6
ASJC Scopus subject areas: Control and Systems Engineering, Electrical and Electronic Engineering, Mechanical Engineering
Keywords: Nonlinear control, Composite nonlinear feedback, motion control, Robust control, High performance control, Servo systems

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A review on old and new results on robust regulation of DPS with infinite-dimensional exosystems

In this paper the robust regulation problem for infinite-dimensional systems
\begin{equation*}
\dot x = Ax + Bu + F_s v, \qquad
y = Cx + Du + F_m v,
\end{equation*}
with infinite-dimensional exosystems $\dot v = S v$ is discussed. The feedback controller is of the form
\begin{equation*}
\dot z = \mathcal{G}_1 z + \mathcal{G}_2 e, \qquad
u = K z.
\end{equation*}
All the spaces involved are infinite-dimensional. The purpose of the feedback controller is to stabilize the closed loop system and to asymptotically track the reference and perturbation signal generated by the exosystem.

The first key idea is the existence of a dynamic (bounded) steady state operator, which gives the asymptotic state of the stabilized closed loop system as time goes to infinity. This operator satisfies an operator Sylvester equation. The controller $(\mathcal{G}_1, \mathcal{G}_2)$ is robustly regulating if the Sylvester equation decomposes so that a regulation constraint will be satisfied. In the presentation various definitions of Internal Model Principle, including an infinite-dimensional one, guaranteeing robust regulation, will be discussed.

The second important step is in stabilizing the closed loop system by a proper choice of the controller. As the robust controller contains a $p$-copy of the exosystem, the closed loop system cannot be stabilized exponentially; instead strong or weak stabilization must be used.

A necessary condition for the existence of bounded dynamic steady state operator is the nonexistence of system zeros on the spectrum of the exosystem. In the infinite-dimensional case, the behaviour of the system transfer function at infinity also plays an important role.

The presentation reviews and combines the recent results of T. Hämäläinen, L. Paunonen. P. Laakkonen and S. Pohjolainen.

General information

Publication status: Published
Organisations: Department of Mathematics
Contributors: Hämäläinen, T.
Publication date: 4 Jan 2012
Peer-reviewed: Unknown
Event: Paper presented at Matematiikan päivät, 4-5.1.2012, Lappeenrannan Teknillinen Yliopisto, .

Research output: Other conference contributionPaper, poster or abstractScientific

A Self-Tuning Robust Regulator for Infinite-Dimensional Systems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Hämäläinen, T., Pohjolainen, S.
Pages: 2116-2127
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Automatic Control
Volume: 56
Issue number: 9
ISSN (Print): 0018-9286
Ratings: 
  • Scopus rating (2011): CiteScore 4.11 SJR 3.431 SNIP 2.858
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 6018

Research output: Contribution to journalArticleScientificpeer-review

A Simple Character String Proof of the "True but Unprovable'' Version of Gödel's First Incompleteness Theorem

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Regulation of learning and active learning methods (REALMEE)
Contributors: Valmari, A.
Number of pages: 15
Pages: 355-369
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Electronic Proceedings in Theoretical Computer Science
Volume: 151
Article number: 25
ISSN (Print): 2075-2180
Ratings: 
  • Scopus rating (2014): SJR 0.36 SNIP 0.719
Original language: English

Bibliographical note

Paper presented also in the Proceedings of the 14th International Conference Automata and Formal Languages (AFL 2014).<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-11-17<br/>Publisher name: Open Publishing Association

Source: researchoutputwizard
Source ID: 1692

Research output: Contribution to journalArticleScientificpeer-review

A Simple Controller with a Reduced Order Internal Model in the Frequency Domain

We use frequency domain methods to study robust output regulation of a stable plant in a situation where the controller is only required to be robust with respect to a predefined class of perturbations. We present a characterization for the solvability of the control problem and design a minimal order controller that achieves robustness with respect to a given class of uncertainties. The construction of the controller is illustrated with an example.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: MAT Mathematical and semantic modelling
Contributors: Laakkonen, A., Paunonen, L.
Number of pages: 5
Pages: 1988-1992
Publication date: 2016

Host publication information

Title of host publication: Proceedings of European Control Conference 2016
Publisher: IEEE
ISBN (Electronic): 978-1-5090-2590-9
ASJC Scopus subject areas: Applied Mathematics

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A simulator for infinite-dimensional systems with a self-tuning controller

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Åkerblom, M., Hämäläinen, T., Pohjolainen, S.
Pages: 5 p
Publication date: 2009

Host publication information

Title of host publication: IFAC Workshop on Control Applications of Optimization CAO'09, 6-8 May, 2009 Jyväskylä, Finland

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9710

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Assessing coupling dynamics from an ensemble of time series

Finding interdependency relations between time series provides valuable knowledge about the processes that generated the signals. Information theory sets a natural framework for important classes of statistical dependencies. However, a reliable estimation from information-theoretic functionals is hampered when the dependency to be assessed is brief or evolves in time. Here, we show that these limitations can be partly alleviated when we have access to an ensemble of independent repetitions of the time series. In particular, we gear a data-efficient estimator of probability densities to make use of the full structure of trial-based measures. By doing so, we can obtain time-resolved estimates for a family of entropy combinations (including mutual information, transfer entropy and their conditional counterparts), which are more accurate than the simple average of individual estimates over trials. We show with simulated and real data generated by coupled electronic circuits that the proposed approach allows one to recover the time-resolved dynamics of the coupling between different subsystems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, University of Electronic Science and Technology of China, Institute of Computer Science (ICS) of the Foundation for Research and Technology - Hellas (FORTH), Lab of Neurophysics and Neurophysiology, Hefei National Laboratory for Physical Sciences at the Microscale, Instituto de Fisica Interdisciplinar y Sistemas Complejos (CSIC-UIB), Campus Universitat de les Illes Balears, Institut für Kognitionswissenschaft, University of Osnabrück, University of Tartu, Netherlands Institute for Neuroscience
Contributors: Gómez-Herrero, G., Wu, W., Rutanen, K., Soriano, M. C., Pipa, G., Vicente, R.
Number of pages: 13
Pages: 1958-1970
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Entropy
Volume: 17
Issue number: 4
ISSN (Print): 1099-4300
Ratings: 
  • Scopus rating (2015): CiteScore 1.99 SJR 0.551 SNIP 1.116
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all)
Keywords: Ensemble, Entropy, Estimator, Time series, Transfer entropy, Trial

Bibliographical note

EXT="Gómez-Herrero,Germán"

Source: Scopus
Source ID: 84930319366

Research output: Contribution to journalArticleScientificpeer-review

Asteroid 2867 Steins - II. Multi-telescope visible observations, shape reconstruction, and rotational state

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Lamy, P., Kaasalainen, M., Lowry, S., Weissman, P., Barucci, M., Carvano, J., Choi, Y., Colas, F., Faury, G., Fornasier, S., Groussin, O., Hicks, M., Jorda, L., Kryszczynska, A., Larson, S., Toth, I., Warner, B.
Pages: 1179-1185
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 487
Issue number: 3
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2008): SJR 2.907 SNIP 1.336
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: EDP Sciences

Source: researchoutputwizard
Source ID: 12780

Research output: Contribution to journalArticleScientificpeer-review

Asteroid (2867) Steins: Shape, topography and global physical properties from OSIRIS observations

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Jorda, L., Lamy, P., Gaskell, R., Kaasalainen, M., Groussin, O., Besse, S., Faury, G.
Pages: 1089-1100
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Icarus
Volume: 221
Issue number: 2
ISSN (Print): 0019-1035
Ratings: 
  • Scopus rating (2012): CiteScore 3.08 SJR 2.32 SNIP 1.265
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Academic Press

Source: researchoutputwizard
Source ID: 4357

Research output: Contribution to journalArticleScientificpeer-review

Asteroid models from combined sparse and dense photometric data

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Durech, J., Kaasalainen, M., Warner, B., Fauerbach, M., Mark, S., Fauvaud, S., Fauvaud, M., Vugnon, J., Pilcher, F., Bernasconi, L., Behrend, R.
Pages: 291-297
Publication date: 2009
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 493
Issue number: 1
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2009): SJR 2.976 SNIP 1.438
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9916

Research output: Contribution to journalArticleScientificpeer-review

Asteroid Models from Multiple Data Sources

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Ďurech, J., Carry, B., Delbo, M., Kaasalainen, M., Viikinkoski, M.
Number of pages: 20
Pages: 183-202
Publication date: 2015

Host publication information

Title of host publication: Asteroids IV
Place of publication: Tucson
Publisher: UNIVERSITY OF ARIZONA PRESS
Editors: Michel, P., DeMeo, F. E., Bottke Jr., W. F.
ISBN (Print): 978-0-8165-3213-1

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Asteroid models from photometry and complementary data sources

I discuss inversion methods for asteroid shape and spin reconstruction with photometry (lightcurves) and complementary data sources such as adaptive optics or other images, occultation timings, interferometry, and range-Doppler radar data. These are essentially different sampling modes (generalized projections) of plane-of-sky images. An important concept in this approach is the optimal weighting of the various data modes. The maximum compatibility estimate, a multimodal generalization of the maximum likelihood estimate, can be used for this purpose. I discuss the fundamental properties of lightcurve inversion by examining the two-dimensional case that, though not usable in our three-dimensional world, is simple to analyze, and it shares essentially the same uniqueness and stability properties as the 3-D case. After this, I review the main aspects of 3-D shape representations, lightcurve inversion, and the inclusion of complementary data.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Kaasalainen, M.
Number of pages: 26
Publication date: 2016

Host publication information

Title of host publication: Graduate School In Astronomy : Xvi Special Courses At The National Observatory Of Rio De Janeiro: Xvi Cce
Publisher: AMER INST PHYSICS
Editors: Chavero, C., Cunha, K., Carvano, J., Fernandes, M., Dupke, R.
ISBN (Electronic): 978-0-7354-1383-2

Publication series

Name: AIP Conference Proceedings
Publisher: AMER INST PHYSICS
Volume: 1732
ISSN (Print): 0094-243X
Keywords: Asteroids, Inverse problems, Photometry, Adaptive optics, Interferometry, LIGHTCURVE INVERSION, OPTIMIZATION METHODS, SHAPE, RECONSTRUCTION, POLYHEDRON

Bibliographical note

JUFOID=50722

Source: WOS
Source ID: 000375932000003

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Asteroid models from the Pan-STARRS photometry

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Durech, J., Grav, T., Jedicke, R., Kaasalainen, M., Denneau, L.
Pages: 179-187
Publication date: 2005
Peer-reviewed: Yes

Publication information

Journal: Earth, Moon, and Planets
Volume: 97
Issue number: 3-4
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 18183

Research output: Contribution to journalArticleScientificpeer-review

A Stochastic Mixture Surrogate Model Algorithm for Computationally Expensive Black-Box Global Optimization Problems

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Müller, J., Shoemaker, C., Piche, R.
Number of pages: 4
Pages: 1-4
Publication date: 2012

Host publication information

Title of host publication: Proceedings of Global Optimization Workshop 2012, 26-29 June 2012, Natal, Brazil
Place of publication: Natal, Brazil
Publisher: Universidade Federal do Rio Grande do Norte

Publication series

Name: Global Optimization Workshop

Bibliographical note

ei ut-numeroa 22.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Universidade Federal do Rio Grande do Norte

Source: researchoutputwizard
Source ID: 4881

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

A study of crown development mechanisms using a shoot-based tree model and segmented terrestrial laser scanning data

Background and Aims Functional-structural plant models (FSPMs) allow simulation of tree crown development as the sum of modular (e.g. shoot-level) responses triggered by the local environmental conditions. The actual process of space filling by the crowns can be studied. Although the FSPM simulations are at organ scale, the data for their validation have usually been at more aggregated levels (whole-crown or whole-tree). Measurements made by terrestrial laser scanning (TLS) that have been segmented into elementary units (internodes) offer a phenotyping tool to validate the FSPM predictions at levels comparable with their detail. We demonstrate the testing of different formulations of crown development of Scots pine trees in the LIGNUM model using segmented TLS data. Methods We made TLS measurements from four sample trees growing in a forest on a relatively poor soil from sapling size to mature stage. The TLS data were segmented into internodes. The segmentation also produced information on whether needles were present in the internode. We applied different formulations of crown development (flushing of buds and length of growth of new internodes) in LIGNUM. We optimized the parameter values of each formulation using genetic algorithms to observe the best fit of LIGNUM simulations to the measured trees. The fitness function in the estimation combined both tree-level characteristics (e.g. tree height and crown length) and measures of crown shape (e.g. spatial distribution of needle area). Key Results Comparison of different formulations against the data indicates that the Extended Borchert-Honda model for shoot elongation works best within LIGNUM. Control of growth by local density in the crown was important for all shoot elongation formulations. Modifying the number of lateral buds as a function of local density in the crown was the best way to accomplish density control. Conclusions It was demonstrated how segmented TLS data can be used in the context of a shoot-based model to select model components.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Natural Resources Institute Finland (Luke), University of Helsinki
Contributors: Sievänen, R., Raumonen, P., Perttunen, J., Nikinmaa, E., Kaitaniemi, P.
Number of pages: 12
Pages: 423-434
Publication date: 27 Aug 2018
Peer-reviewed: Yes

Publication information

Journal: Annals of Botany
Volume: 122
Issue number: 3
ISSN (Print): 0305-7364
Ratings: 
  • Scopus rating (2018): CiteScore 4.24 SJR 1.705 SNIP 1.697
Original language: English
ASJC Scopus subject areas: Plant Science
Keywords: forest stand, Functional-structural model, Scots pine, terrestrial laser scanning
Source: Scopus
Source ID: 85054790809

Research output: Contribution to journalArticleScientificpeer-review

Asymptotic behaviour in the robot rendezvous problem

This paper presents a natural extension of the results obtained by Feintuch and Francis in (2012a,b) concerning the so-called robot rendezvous problem. In particular, we revisit a known necessary and sufficient condition for convergence of the solution in terms of Cesàro convergence of the translates Skx0, k≥0, of the sequence x0 of initial positions under the right-shift operator S, thus shedding new light on questions left open in Feintuch and Francis (2012a,b). We then present a new proof showing that a certain stronger ergodic condition on x0 ensures that the corresponding solution converges to its limit at the optimal rate O(t−1/2) as t→∞. After considering a natural two-sided variant of the robot rendezvous problem already studied in Feintuch and Francis (2012a) and in particular proving a new quantified result in this case, we conclude by relating the robot rendezvous problem to a more realistic model of vehicle platoons.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: MAT Mathematical and semantic modelling, St Giles
Contributors: Paunonen, L., Seifert, D.
Number of pages: 4
Pages: 127-130
Publication date: 1 May 2017
Peer-reviewed: Yes

Publication information

Journal: Automatica
Volume: 79
ISSN (Print): 0005-1098
Ratings: 
  • Scopus rating (2017): CiteScore 7.45 SJR 3.896 SNIP 3.422
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Electrical and Electronic Engineering
Keywords: Autonomous systems, Mobile robots, Rates of convergence, Stability
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85014150245

Research output: Contribution to journalArticleScientificpeer-review

Asymptotic Behaviour of Coupled Systems in Discrete and Continuous Time

This paper investigates the asymptotic behaviour of solutions to certain infinite systems of coupled recurrence relations. In particular, we obtain a characterisation of those initial values which lead to a convergent solution, and for initial values satisfying a slightly stronger condition we obtain an optimal estimate on the rate of convergence. By establishing a connection with a related problem in continuous time, we are able to use this optimal estimate to improve the rate of convergence in the continuous setting obtained by the authors in a previous paper. We illustrate the power of the general approach by using it to study several concrete examples, both in continuous and in discrete time.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Mathematical and semantic modelling, St Giles
Contributors: Paunonen, L., Seifert, D.
Number of pages: 13
Pages: 433-445
Publication date: Jun 2018
Peer-reviewed: Yes
Early online date: 22 Aug 2016

Publication information

Journal: JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS
Volume: 30
Issue number: 2
ISSN (Print): 1040-7294
Ratings: 
  • Scopus rating (2018): CiteScore 1.29 SJR 1.014 SNIP 1.055
Original language: English
ASJC Scopus subject areas: Analysis
Keywords: $C_0$-semigroups, Asymptotic behaviour, Power-boundeness, Rates of convergence, Recurrence relations, Spectral theory, System
Electronic versions: 
Source: Scopus
Source ID: 84983514153

Research output: Contribution to journalArticleScientificpeer-review

Asymptotic Behaviour of Platoon Systems

In this paper we study the asymptotic behaviour of various platoon-type systems using the general theory developed by the authors in a recent article. The aim is to steer an infinite number of vehicles towards a target configuration in which each vehicle has a prescribed separation from its neighbour and all vehicles are moving at a given velocity. More specifically, we study systems in which state feedback is possible, systems in which observer-based dynamic output feedback is required, and also a situation in which the control objective is modified to allow the target separations to depend on the vehicles’ velocities. We show that in the first and third cases the objective can be achieved, but that in the second case the system is unstable in the sense that the associated semigroup is not uniformly bounded. We also present some quantified results concerning the rate of convergence of the platoon to its limit state when the limit exists.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: MAT Mathematical and semantic modelling, University of Oxford
Contributors: Paunonen, L., Seifert, D.
Number of pages: 7
Pages: 830-836
Publication date: Jul 2016

Host publication information

Title of host publication: Proceedings of the 22nd International Symposium on Mathematical Theory of Networks and Systems
Publisher: University of Minnesota
ISBN (Electronic): 978-1-5323-1358-5
ASJC Scopus subject areas: Analysis, Control and Optimization
Keywords: Vehicle platoon, ordinary differential equations, asymptotic behaviour, state feedback, rates of convergence

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Asymptotic modeling of unconstrained control of a tethered power kite moving along a given closed-loop spherical trajectory

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Silvennoinen, R., Argatov, I.
Pages: 187-203
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Journal of Engineering Mathematics
Volume: 72
Issue number: 1
ISSN (Print): 0022-0833
Ratings: 
  • Scopus rating (2012): CiteScore 1.06 SJR 0.572 SNIP 1.064
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Springer Netherlands

Source: researchoutputwizard
Source ID: 5328

Research output: Contribution to journalArticleScientificpeer-review

Asymptotics for infinite systems of differential equations

This paper investigates the asymptotic behavior of solutions to certain infinite systems of ordinary differential equations. In particular, we use results from ergodic theory and the asymptotic theory of C0-semigroups to obtain a characterization, in terms of convergence of certain Cesàro averages, of those initial values which lead to convergent solutions. Moreover, we obtain estimates on the rate of convergence for solutions whose initial values satisfy a stronger ergodic condition. These results rely on a detailed spectral analysis of the operator describing the system, which is made possible by certain structural assumptions on the operator. The resulting class of systems is sufficiently broad to cover a number of important applications including, in particular, both the so-called robot rendezvous problem and an important class of platoon systems arising in control theory. Our method leads to new results in both cases.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics
Contributors: Paunonen, L., Seifert, D.
Number of pages: 26
Pages: 1153-1178
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: SIAM Journal on Control and Optimization
Volume: 55
Issue number: 2
ISSN (Print): 0363-0129
Ratings: 
  • Scopus rating (2017): CiteScore 1.94 SJR 1.399 SNIP 1.723
Original language: English
ASJC Scopus subject areas: Control and Optimization, Applied Mathematics
Keywords: Asymptotic behavior, C0-semigroup, Ergodic theory, Ordinary differential equations, Rates of convergence, Spectrum, System
Electronic versions: 
Source: Scopus
Source ID: 85018956934

Research output: Contribution to journalArticleScientificpeer-review

Asymptotics for periodic systems

This paper investigates the asymptotic behaviour of solutions of periodic evolution equations. Starting with a general result concerning the quantified asymptotic behaviour of periodic evolution families we go on to consider a special class of dissipative systems arising naturally in applications. For this class of systems we analyse in detail the spectral properties of the associated monodromy operator, showing in particular that it is a so-called Ritt operator under a natural ‘resonance’ condition. This allows us to deduce from our general result a precise description of the asymptotic behaviour of the corresponding solutions. In particular, we present conditions for rational rates of convergence to periodic solutions in the case where the convergence fails to be uniformly exponential. We illustrate our general results by applying them to concrete problems including the one-dimensional wave equation with periodic damping.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, St Giles
Contributors: Paunonen, L., Seifert, D.
Pages: 7152-7172
Publication date: May 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Differential Equations
Volume: 266
Issue number: 11
ISSN (Print): 0022-0396
Original language: English
ASJC Scopus subject areas: Analysis, Applied Mathematics
Keywords: Damped wave equation, Evolution family, Non-autonomous system, Periodic, Rates of convergence, Ritt operator
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85057519870

Research output: Contribution to journalArticleScientificpeer-review

Automatic tree species recognition with quantitative structure models

We present three robust methods to accurately and automatically recognize tree species from terrestrial laser scanner data. The recognition is based on the use of quantitative structure tree models, which are hierarchical geometric primitive models accurately approximating the branching structure, geometry, and volume of the trees. Fifteen robust tree features are presented and tested with all different combinations for tree species classification. The classification methods presented are k-nearest neighbours, multinomial regression, and support vector machine based approaches. Three mainly single-species forest plots of Silver birch, Scots pine and Norway spruce, and two mixed-species forest plots located in Finland and a total number of trees over 1200 were used for demonstration. The results show that by using single-species forest plots for training and testing, it is possible to find a feature combination between 5 and 15 features, that results in an average classification accuracy above 93% for all the methods. For the preliminary mixed-species forest plot testing, accuracy was lower but the classification approach presented potential to generalize to more diverse cases. Moreover, the results show that the post-processing of terrestrial laser scanning data of multi-hectare forest, from tree extraction and modelling to species classification, can be done automatically.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Natural Resources Institute Finland (Luke)
Contributors: Åkerblom, M., Raumonen, P., Mäkipää, R., Kaasalainen, M.
Number of pages: 12
Pages: 1-12
Publication date: 15 Mar 2017
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing of Environment
Volume: 191
ISSN (Print): 0034-4257
Ratings: 
  • Scopus rating (2017): CiteScore 7.16 SJR 3.121 SNIP 2.592
Original language: English
ASJC Scopus subject areas: Soil Science, Geology, Computers in Earth Sciences
Keywords: Quantitative structure model, Terrestrial laser scanning, Tree reconstruction, Tree species recognition
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85009742761

Research output: Contribution to journalArticleScientificpeer-review

Autonomous Prediction of GPS and GLONASS Satellite Orbits

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Seppänen, M., Ala-Luhtala, J., Piche, R., Martikainen, S., Ali-Löytty, S.
Pages: 119-134
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Navigation
Volume: 59
Issue number: 2
ISSN (Print): 0028-1522
Ratings: 
  • Scopus rating (2012): CiteScore 1.28 SJR 0.612 SNIP 1.484
Original language: English

Bibliographical note

ei ut-numeroa 29.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Navigation

Source: researchoutputwizard
Source ID: 5304

Research output: Contribution to journalArticleScientificpeer-review

Autonomous satellite orbit prediction

A method to predict satellite orbits in a GPS device without a network connection is presented. The motivation for this work was to improve the startup performance of a navigation device without Assisted GPS. Tests of our algorithm show that in 95% of the cases the error in satellite’s predicted position stays under 21 meters for one day and under 94 meters for three days.

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Seppänen, M.
Pages: 5-10
Publication date: 2011

Host publication information

Title of host publication: Digest of TISE Seminar 2011. TISE publications
Place of publication: Tampere
Publisher: Tampere Graduate School in Information Science and Engineering (TISE). Tampere University of Technology
Editor: Niemistö, A.
ISBN (Print): 978-952-15-2557-5

Publication series

Name: TISE Seminar
Publisher: Tampere Graduate School in Information Science and Engineering (TISE). Tampere University of Technology
Volume: 10
ISSN (Print): 1458-8463

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7236

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Autonomous satellite orbit prediction

A method to predict satellite orbits in a GPS device without a network connection is presented. The motivation for this work was to reduce time to first fix when assistance data is not available. The orbit of a satellite is predicted by numerically integrating the differential equation that models its motion. The initial position and velocity values used in prediction correspond to those received from the broadcast when the device was last operated. These initial values are given in the Earth centered, Earth fixed reference frame and have to be transformed into an inertial reference frame prior to substitution into the equation of motion and subsequent integration. For this purpose, one needs to predict the movement of Earth’s rotation axis with respect to both space (nutation and precession) and to the Earth’s crust (polar motion). Using precise ephemeris as the initial condition, we found that this kind of model gave quite accurate prediction results. However, the results were worse when initial conditions were computed from the less accurate broadcast ephemeris which, unfortunately, is the only ephemeris available to the navigation device without a network connection. In addition, we were not able to find a model that would be able to predict Earth’s polar motion with sufficient accuracy within the assumed lifetime of the device. Without the polar motion parameters, one cannot do the transformation from ECEF to an inertial reference frame. In this paper we will present a method to improve the accuracy of the initial velocity of the satellite computed from the broadcast and simultaneously solve the unknown polar motion parameters. Tests of our algorithm show that in 95%of the cases the error in satellite’s predicted position stays under 21 meters for one day and under 94 meters for three days.

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Seppänen, M., Perälä, T., Piche, R.
Pages: 554-564
Publication date: 2011

Host publication information

Title of host publication: Proceedings of The Institute of Navigation 2011 International Technical Meeting, January 24-26, 2011, San Diego, CA, USA
Place of publication: San Diego, CA
Publisher: The Institute of Navigation

Publication series

Name: Institute of Navigation International Technical Meeting
Publisher: The Institute of Navigation

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7237

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Axiomatic Extensions of Höhle's Monoidal Logic

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research Community on Data-to-Decision (D2D)
Contributors: Turunen, E.
Pages: 163-168
Publication date: 2011

Host publication information

Title of host publication: Proceedings of the 7th conference of the European Society for Fuzzy Logic and Technology EUSFLAT-LFA 2011, Aix-Les-Bains, France, 18 - 22 July 2011
Place of publication: Amsterdam
Publisher: Atlantis Press
ISBN (Print): 978-90-7877-00-0

Publication series

Name: Conference of the European Society for Fuzzy Logic and Technology EUSFLAT-LFA
Publisher: Atlantis Press

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7426

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Bagdad - matematiikkaa täältä ikuisuuteen matematiikkanäyttely

General information

Publication status: Published
MoE publication type: D1 Article in a trade journal
Organisations: Department of Mathematics
Contributors: Eriksson, S., Vainio, J.
Number of pages: 30
Pages: 17-46
Publication date: 2014
Peer-reviewed: Unknown

Publication information

Journal: Lumat
Volume: 2
Issue number: 1
ISSN (Print): 2323-7112
Original language: Finnish

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2015-01-14

Source: researchoutputwizard
Source ID: 288

Research output: Contribution to journalArticleProfessional

Bandwidth and Storage Reduction of Radio Maps for Offline WLAN Positioning

Most of the existing mobile device positioning methods require data connectivity, i.e. they work in the mobile-assisted, or online mode. However, this consumes energy, induces transmission costs and results in unnecessarily long time-to-first-fix. These issues can be alleviated using mobile-based, or offline, mode. In this mode the device carries a subset of the global radio map in memory for fast positioning without data connection. The challenge of this approach is the large size of the offline radio map that needs to be downloaded, stored and updated periodically in the mobile device. This paper presents a method to find the significant APs in the global radio map and proposes using only those in offline positioning in order to compress the size of the required offline radio map. We also propose a method to further compress the size of the offline radio map by hashing the globally unique AP BSSIDs into locally unique shortened BSSIDs. We test the proposed methods with real-world data.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Wirola, L., Wirola, L., Piche, R.
Number of pages: 9
Pages: 665-673
Publication date: 2013

Host publication information

Title of host publication: International Conference on Indoor Positioning and Indoor Navigation, IPIN 2013, 28-31 Oct 2013, Montbéliard-Belfort, France
Place of publication: Piscataway, NJ
Publisher: IEEE

Publication series

Name: International Conference on Indoor Positioning and Indoor Navigation

Bibliographical note

to appear in IEEEXPLORE<br/>Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2013-11-29<br/>Publisher name: IEEE

Source: researchoutputwizard
Source ID: 3746

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Bayes Forest: A data-intensive generator of morphological tree clones

Detailed and realistic tree form generators have numerous applications in ecology and forestry. For example, the varying morphology of trees contributes differently to formation of landscapes, natural habitats of species, and eco-physiological characteristics of the biosphere. Here, we present an algorithm for generating morphological tree "clones" based on the detailed reconstruction of the laser scanning data, statistical measure of similarity, and a plant growth model with simple stochastic rules. The algorithm is designed to produce tree forms, i.e., morphological clones, similar (and not identical) in respect to tree-level structure, but varying in fine-scale structural detail. Although we opted for certain choices in our algorithm, individual parts may vary depending on the application, making it a general adaptable pipeline. Namely, we showed that a specific multipurpose procedural stochastic growth model can be algorithmically adjusted to produce the morphological clones replicated from the target experimentally measured tree. For this, we developed a statistical measure of similarity (structural distance) between any given pair of trees, which allows for the comprehensive comparing of the tree morphologies by means of empirical distributions describing the geometrical and topological features of a tree. Finally, we developed a programmable interface to manipulate data required by the algorithm. Our algorithm can be used in a variety of applications for exploration of the morphological potential of the growth models (both theoretical and experimental), arising in all sectors of plant science research.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Department of Computer Science, Aalto University
Contributors: Potapov, I., Järvenpää, M., Åkerblom, M., Raumonen, P., Kaasalainen, M.
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: GigaScience
Volume: 6
Issue number: 10
Article number: gix079
ISSN (Print): 2047-217X
Ratings: 
  • Scopus rating (2017): CiteScore 6.81 SJR 5.022 SNIP 1.836
Original language: English
ASJC Scopus subject areas: Health Informatics, Computer Science Applications
Keywords: Empirical distributions, Large scale data, Morphological clone, Quantitative structure tree model, Stochastic data driven model, Terrestrial laser scanning
Electronic versions: 

Bibliographical note

EXT="Järvenpää, Marko"

Source: Scopus
Source ID: 85032857287

Research output: Contribution to journalArticleScientificpeer-review

Bayesian analysis of GUHA hypotheses

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Department of Mathematics, Research group: Positioning, Research Community on Data-to-Decision (D2D), Wireless Communications and Positioning (WICO)
Contributors: Piche, R., Järvenpää, M., Turunen, E., Simunek, M.
Number of pages: 28
Pages: 47-73
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Intelligent Information Systems
Volume: 42
Issue number: 1
ISSN (Print): 0925-9902
Ratings: 
  • Scopus rating (2013): CiteScore 1.13 SJR 0.37 SNIP 0.891
Original language: English

Bibliographical note

Online first<br/>Contribution: organisation=ase,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: Springer

Source: researchoutputwizard
Source ID: 3149

Research output: Contribution to journalArticleScientificpeer-review

Bayesian assaying of GUHA nuggets

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: Positioning
Contributors: Piche, R., Turunen, E.
Pages: 348-355
Publication date: 2010

Host publication information

Title of host publication: Information Processing and Management of Uncertainty in Knowledge-Based Systems. Theory and Methods, 13th International Conference, IPMU 2010, Dortmund, Germany, June 28 - July 2, 2010. Communications in Computer and Information Science
Editors: Hüllermeier, E., Kruse, R., Hoffmann, F.
ISBN (Print): 978-3-642-14054-9

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8997

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Bayesian Methods

Bayesian statistical methods are widely used in many science and engineering areas including machine intelligence, expert systems, medical imaging, pattern recognition, decision theory, data compression and coding, estimation and prediction, bioinformatics, and data mining. These course notes present the basic principles of Bayesian statistics. The first sections explain how to estimate parameters for simple standard statistical models (normal, binomial, Poisson, exponential), using both analytical formulas and the free WinBUGS data modelling software. This software is then used to explore multivariate hierarchical problems that arise in real applications. Advanced topics include decision theory, missing data, change point detection, model selection, and MCMC computational algorithms. Students are assumed to have knowledge of basic probability. A standard introductory course in statistics is useful but not necessary. Additional course materials (exercises, recorded lectures, model exams) are available at http://math.tut.fi/~piche/bayes

General information

Publication status: Published
MoE publication type: D5 Text book, professional manual or guide or a dictionary
Organisations: Department of Mathematics, Research group: Positioning
Contributors: Penttinen, A., Piche, R.
Number of pages: 82
Publication date: 2010

Publication information

Place of publication: Tampere
Publisher: Tampere University of Technology
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8978

Research output: Book/ReportBookProfessional

Bayesian Methods for Hybrid Indoor Positioning

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Automation Science and Engineering, Research group: Positioning
Contributors: Nurminen, H.
Number of pages: 2
Publication date: 2014

Host publication information

Title of host publication: IPIN 2014 - 5th International Conference on Indoor Positioning and Indoor Navigation, 27th - 30 th October, 2014, Busan, South Korea

Bibliographical note

siirretään 2015<br/>Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2015-01-14
xabstract

Source: researchoutputwizard
Source ID: 1166

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Bayesian Positioning Using Gaussian Mixture Models with Time-varying Component Weights

Gaussian mixture models are often used in target tracking applications to take into account maneuvers in state dynamics or changing levels of observation noise. In this study it is assumed that the measurement or the state transition model can have two plausible candidates, as for example in positioning with line-of-sight or non-line-sight-signals. The plausibility described by the mixture component weight is modeled as a time-dependent random variable and is formulated as a Markov process with a heuristic model based on the Beta distribution. The proposed system can be used to approximate some well-known multiple model systems by tuning the parameter of the state transition distribution for the component weight. The posterior distribution of the state can be solved approximately using a Rao-Blackwellized particle filter. Simulations of GPS pedestrian tracking are used to test the proposed method. The results indicate that the new system is able to find the true models and its root mean square error-performance is comparable to filters that know the true models.

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Pesonen, H., Piche, R.
Pages: 4516-4524
Publication date: 2011

Host publication information

Title of host publication: JSM 2011 Joint Statistical Meetings 2011, Miami Beach, Florida, USA, July 30-August 4, 2011
Place of publication: Miami Beach, FL
Publisher: American Statistical Association

Publication series

Name: Joint Statistical Meetings JSM
Publisher: American Statistical Association

Bibliographical note

ei ut-numeroa 26.4.2014<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7007

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Bayes trees and forests: combining precise empirical and theoretical tree models

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Kaasalainen, M., Potapov, I., Raumonen, P., Åkerblom, M., Sievänen, R., Kaasalainen, S.
Number of pages: 3
Pages: 61-63
Publication date: 2013

Host publication information

Title of host publication: 7th International Conference on Functional-Structural Plant Models, FSPM2013, FSPM2013, 9.-14.6.2013, Saariselkä, Finland
Place of publication: Vantaa
Publisher: Finnish Society of Forest Science; Finnish Forest Research Institute; University of Helsinki
Editors: Sievänen, R., Nikinmaa, E., Godin, C., Lintunen, A., Nygren, P.
ISBN (Print): 978-951-651-408-9

Publication series

Name: International Conference on Functional-Structural Plant Models

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: Finnish Society of Forest Science; Finnish Forest Research Institute; University of Helsinki

Source: researchoutputwizard
Source ID: 2449

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Binomial Gaussian mixture filter

In this work, we present a novel method for approximating a normal distribution with a weighted sum of normal distributions. The approximation is used for splitting normally distributed components in a Gaussian mixture filter, such that components have smaller covariances and cause smaller linearization errors when nonlinear measurements are used for the state update. Our splitting method uses weights from the binomial distribution as component weights. The method preserves the mean and covariance of the original normal distribution, and in addition, the resulting probability density and cumulative distribution functions converge to the original normal distribution when the number of components is increased. Furthermore, an algorithm is presented to do the splitting such as to keep the linearization error below a given threshold with a minimum number of components. The accuracy of the estimate provided by the proposed method is evaluated in four simulated single-update cases and one time series tracking case. In these tests, it is found that the proposed method is more accurate than other Gaussian mixture filters found in the literature when the same number of components is used and that the proposed method is faster and more accurate than particle filters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Department of Mathematics, Research group: MAT Positioning, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Ali-Löytty, S., Piché, R.
Publication date: 2 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2015
Issue number: 1
Article number: 36
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2015): CiteScore 0.83 SJR 0.351 SNIP 0.934
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Keywords: Estimation, Gaussian mixture filter, Nonlinear filtering
Electronic versions: 

Bibliographical note

ORG=ase,0.75
ORG=mat,0.25

Source: Scopus
Source ID: 84934283964

Research output: Contribution to journalArticleScientificpeer-review

Bistatic full-wave radar tomography detects deep interior voids, cracks and boulders in a rubble-pile asteroid model.

In this paper, we investigate full-wave computed radar tomography (CRT) using a rubble-pile asteroid model in which a realistic shape (Itokawa) is coupled with a synthetic material composition and structure model. The aim is to show that sparse bistatic radar measurements can distinguish details inside a complex-structured rubble-pile asteroid. The results obtained suggest that distinct local permittivity distribution changes such as surface layers, voids, low-permittivity anomalies, high-permittivity boulders, and cracks can be detected with bistatic CRT, when the total noise level in the data is around −10 dB with respect to the signal amplitude. Moreover, the bistatic measurement setup improves the robustness of the inversion compared to the monostatic case. Reconstructing the smooth Gaussian background distribution was found to be difficult with the present approach, suggesting that complementary techniques, such as gravimetry, might be needed to improve the reliability of the inference in practice.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Max Planck Institute for Solar System Research
Contributors: Sorsa, L., Takala, M., Bambach, P., Deller, J., Vilenius, E., Pursiainen, S.
Number of pages: 11
Publication date: 8 Feb 2019
Peer-reviewed: Yes

Publication information

Journal: Astrophysical Journal
Volume: 872
Issue number: 1
Article number: 44
ISSN (Print): 0004-637X
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Box Gaussian mixture filter

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Ali-Löytty, S.
Pages: 2165-2169
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Automatic Control
Volume: 55
Issue number: 9
ISSN (Print): 0018-9286
Ratings: 
  • Scopus rating (2010): SJR 2.752 SNIP 2.832
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7672

Research output: Contribution to journalArticleScientificpeer-review

Briefly about the root-locus of linear systems

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Department of Mathematics
Contributors: Laakkonen, P.
Number of pages: 6
Pages: 101-106
Publication date: 2010

Host publication information

Title of host publication: Digest of TISE Seminar 2010, Ylöjärvi, Finland, 26.5.2010. TISE Publications
Editor: Koivisto, P.
ISBN (Print): 978-952-15-2368-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8513

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Business Angels and Investment Organizations as Networked Co-creators of the Finnish Innovation Ecosystem

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Huhtamäki, J., Russell, M. G., Still, K., Rubens, N., Yu, J. (.
Number of pages: 15
Pages: 1-15
Publication date: 2011

Host publication information

Title of host publication: Proceedings of the Triple Helix IX International Conference: Silicon Valley: Global Model or Unique Anomaly? 11-14 July, 2011, Stanford, California, USA
Place of publication: Stanford, CA
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Publication series

Name: Triple Helix International Conference
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Bibliographical note

ei ut-numeroa 8.3.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 6111

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Canonical methods of constructing invariant tori by phase-space sampling

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Laakso, T., Kaasalainen, M.
Number of pages: 6
Pages: 14-19
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Physica D: Nonlinear Phenomena
Volume: 243
Issue number: 1
ISSN (Print): 0167-2789
Ratings: 
  • Scopus rating (2013): CiteScore 1.76 SJR 1.071 SNIP 1.337
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: Elsevier

Source: researchoutputwizard
Source ID: 2679

Research output: Contribution to journalArticleScientificpeer-review

Cauchy–Riemann Operators in Octonionic Analysis

In this paper we first recall the definition of the octonion algebra and its algebraic properties. We derive the so called e4-calculus and using it we obtain the list of generalized Cauchy–Riemann systems for octonionic monogenic functions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics, Civil Engineering
Contributors: Kauhanen, J., Orelma, H.
Publication date: 2018
Peer-reviewed: Yes
Early online date: Jan 2018

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 28
Issue number: 1
Article number: 1
ISSN (Print): 0188-7009
Ratings: 
  • Scopus rating (2018): CiteScore 0.9 SJR 0.4 SNIP 0.899
Original language: English
ASJC Scopus subject areas: Applied Mathematics
Keywords: Cauchy–Riemann operators, Dirac operators, Monogenic functions, Octonions
Electronic versions: 
Source: Scopus
Source ID: 85041309780

Research output: Contribution to journalArticleScientificpeer-review

Challenges in Heterogeneous Web Data Analytics - Case Finnish Growth Companies in Social Media

Diverse data about various phenomena are implicitly available in the modern web. In particular websites categorized as social media provide rich and heterogeneous data about various entities such as people, corporations, brands as well as their properties and relationships. An analyst who seeks to leverage this diverse data is faced with the challenge of integrating and making sense of a set of heterogeneous data sources. In this paper, we provide an introduction and a problem statement for heterogeneous web data analytics. To further highlight and discuss practical challenges, we introduce a case study of Finnish growth companies in social media. Instead of a purely data-driven approach, the presented approach is rooted in the idea that an analyst can actively participate in the data collection and integration process, while the process can still retain repeatability and transparency. The key contribution of this paper is the statement of the challenges related to heterogeneous web data analytics.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Salonen, J., Huhtamäki, J., Nykänen, O.
Number of pages: 8
Pages: 131-138
Publication date: 2013

Host publication information

Title of host publication: 17th International Academic MindTrek Conference, October 1-4, 2013, Tampere, Finland
Publisher: ACM
ISBN (Print): 978-1-4503-1992-8

Publication series

Name: MindTrek Conference

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: ACM

Source: researchoutputwizard
Source ID: 3354

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Change Detection of Tree Biomass with Terrestrial Laser Scanning and Quantitative Structure Modelling

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Kaasalainen, S., Krooks, A., Liski, J., Raumonen, P., Kaartinen, H., Kaasalainen, M., Puttonen, E., Anttila, K., Mäkipää, R.
Number of pages: 25
Pages: 3906-3922
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing
Volume: 6
Issue number: 5
ISSN (Print): 2072-4292
Ratings: 
  • Scopus rating (2014): CiteScore 3.23 SJR 1.275 SNIP 1.833
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-09-30<br/>Publisher name: MDPI AG

Source: researchoutputwizard
Source ID: 631

Research output: Contribution to journalArticleScientificpeer-review

Characterizing n-Fold Positive Implicative BL-logics

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Department of Mathematics
Contributors: Turunen, E., Lele, C., Tchikapa, N.
Pages: 60-64
Publication date: 2012

Host publication information

Title of host publication: ManyVal'12 In Honour of Antonio Di Nola's 65th Birthday, Salerno, Italy, 4.7.7.2012

Publication series

Name: ManyVal

Bibliographical note

ei ut-numeroa 21.9.2013<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5462

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Chasing the Rainbow Connection: Hardness, Algorithms, and Bounds

We study rainbow connectivity of graphs from the algorithmic and graph-theoretic points of view. The study is divided into three parts. First, we study the complexity of deciding whether a given edge-colored graph is rainbow-connected. That is, we seek to verify whether the graph has a path on which no color repeats between each pair of its vertices. We obtain a comprehensive map of the hardness landscape of the problem. While the problem is NP-complete in general, we identify several structural properties that render the problem tractable. At the same time, we strengthen the known NP-completeness results for the problem. We pinpoint various parameters for which the problem is fixed-parameter tractable, including dichotomy results for popular width parameters, such as treewidth and pathwidth. The study extends to variants of the problem that consider vertex-colored graphs and/or rainbow shortest paths. We also consider upper and lower bounds for exact parameterized algorithms. In particular, we show that when parameterized by the number of colors k, the existence of a rainbow s-t path can be decided in O∗ (2k ) time and polynomial space. For the highly related problem of finding a path on which all the k colors appear, i.e., a colorful path, we explain the modest progress over the last twenty years. Namely, we prove that the existence of an algorithm for finding a colorful path in (2 − ε)k nO(1) time for some ε > 0 disproves the so-called Set Cover Conjecture.

Second, we focus on the problem of finding a rainbow coloring. The minimum number of colors for which a graph G is rainbow-connected is known as its rainbow connection number, denoted by rc(G). Likewise, the minimum number of colors required to establish a rainbow shortest path between each pair of vertices in G is known as its strong rainbow connection number, denoted by src(G). We give new hardness results for computing rc(G) and src(G), including their vertex variants. The hardness results exclude polynomial-time algorithms for restricted graph classes and also fast exact exponential-time algorithms (under reasonable complexity assumptions). For positive results, we show that rainbow coloring is tractable for e.g., graphs of bounded treewidth. In addition, we give positive parameterized results for certain variants and relaxations of the problems in which the goal is to save k colors from a trivial upper bound, or to rainbow connect only a certain number of vertex pairs.

Third, we take a more graph-theoretic view on rainbow coloring. We observe upper bounds on the rainbow connection numbers in terms of other well-known graph parameters. Furthermore, despite the interest, there have been few results on the strong rainbow connection number of a graph. We give improved bounds and determine exactly the rainbow and strong rainbow connection numbers for some subclasses of chordal graphs. Finally, we pose open problems and conjectures arising from our work.

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Department of Mathematics
Contributors: Lauri, J.
Number of pages: 67
Publication date: 3 Nov 2016

Publication information

Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-3836-0
ISBN (Electronic): 978-952-15-3842-1
Original language: English

Publication series

Name: Tampere University of Technology. Publication
Volume: 1428
ISSN (Print): 1459-2045

Research output: Book/ReportDoctoral thesisCollection of Articles

Closed classes of functions, generalized constraints, and clusters

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Lehtonen, E.
Pages: 203-234
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Algebra Universalis
Volume: 63
Issue number: 2-3
ISSN (Print): 0002-5240
Ratings: 
  • Scopus rating (2010): SJR 0.638 SNIP 1.103
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8597

Research output: Contribution to journalArticleScientificpeer-review

Closed-form algorithms in mobile positioning: Myths and misconceptions

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Sirola, N.
Pages: 38-44
Publication date: 2010

Host publication information

Title of host publication: Proceedings of the 7th Workshop on Positioning, Navigation and Communication 2010 WPNC'10, 11-12 March 2010, Dresden, Germany
ISBN (Print): 978-1-4244-7157-7

Bibliographical note

poistettu tupla r=3045, esitelmä http://math.tut.fi/posgroup/sirola-wpnc2010-slides.ppt<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9289

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Closing the gap between Earth-based and interplanetary mission observations: Vesta seen by VLT/SPHERE

Context. Over the past decades, several interplanetary missions have studied small bodies in situ, leading to major advances in our understanding of their geological and geophysical properties. These missions, however, have had a limited number of targets. Among them, the NASA Dawn mission has characterised in detail the topography and albedo variegation across the surface of asteroid (4) Vesta down to a spatial resolution of ~20 m pixel -1 scale. Aims. Here our aim was to determine how much topographic and albedo information can be retrieved from the ground with VLT/SPHERE in the case of Vesta, having a former space mission (Dawn) providing us with the ground truth that can be used as a benchmark. Methods. We observed Vesta with VLT/SPHERE/ZIMPOL as part of our ESO large programme (ID 199.C-0074) at six different epochs, and deconvolved the collected images with a parametric point spread function (PSF). We then compared our images with synthetic views of Vesta generated from the 3D shape model of the Dawn mission, on which we projected Vesta's albedo information. Results. We show that the deconvolution of the VLT/SPHERE images with a parametric PSF allows the retrieval of the main topographic and albedo features present across the surface of Vesta down to a spatial resolution of ~20-30 km. Contour extraction shows an accuracy of ~1 pixel (3.6 mas). The present study provides the very first quantitative estimate of the accuracy of ground-based adaptive-optics imaging observations of asteroid surfaces. Conclusions. In the case of Vesta, the upcoming generation of 30-40 m telescopes (ELT, TMT, GMT) should in principle be able to resolve all of the main features present across its surface, including the troughs and the north-south crater dichotomy, provided that they operate at the diffraction limit.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Laboratoire d'Astrophysique de Marseille, Massachusetts Institute of Technology, Queen's University, Belfast, Northern Ireland, ONERA - The French Aerospace Lab, CNRS, SETI Institute, Charles University in Prague, IMCCE - Institut de Mecanique Celeste et de Calcul des Ephemerides, Adam Mickiewicz University, Jet Propulsion Laboratory, California Institute of Technology, ESTEC - European Space Research and Technology Centre, TMT Observatory, Université de Liège, Pontifical Catholic University of Peru San Miguel, University of Szczecin, European Southern Observatory (ESO)
Contributors: Fétick, R. J., Jorda, L., Vernazza, P., Marsset, M., Drouard, A., Fusco, T., Carry, B., Marchis, F., Hanuš, J., Viikinkoski, M., Birlan, M., Bartczak, P., Berthier, J., Castillo-Rogez, J., Cipriani, F., Colas, F., Dudziński, G., Dumas, C., Ferrais, M., Jehin, E., Kaasalainen, M., Kryszczynska, A., Lamy, P., Le Coroller, H., Marciniak, A., Michalowski, T., Michel, P., Mugnier, L. M., Neichel, B., Pajuelo, M., Podlewska-Gaca, E., Santana-Ros, T., Tanga, P., Vachier, F., Vigan, A., Witasse, O., Yang, B.
Publication date: 1 Mar 2019
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 623
Article number: A6
ISSN (Print): 0004-6361
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: Methods: observational, Minor planets, asteroids: individual: Vesta, Techniques: high angular resolution, Techniques: image processing
Electronic versions: 
Source: Scopus
Source ID: 85062791633

Research output: Contribution to journalArticleScientificpeer-review

Clustering and achievement of engineering students based on their attitudes, orientations, motivations and intentions

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Huikkola, M., Silius, K., Pohjolainen, S.
Pages: 342-354
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: WSEAS Transactions on Advances in Engineering Education
Volume: 5
Issue number: 5
Original language: English

Bibliographical note

Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 12277

Research output: Contribution to journalArticleScientificpeer-review

Column-partitioned matrices over rings without invertible transversal submatrices

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Foldes, S., Lehtonen, E.
Pages: 33-39
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Ars Combinatoria
Volume: 97
ISSN (Print): 0381-7032
Ratings: 
  • Scopus rating (2010): SJR 0.322 SNIP 0.529
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7914

Research output: Contribution to journalArticleScientificpeer-review

Combinational Studies of Vectors and Sequences

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Department of Mathematics
Contributors: Major, L.
Number of pages: 73
Publication date: 2014

Publication information

Place of publication: Tampere
Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-3311-2
Original language: English

Publication series

Name: Tampere University of Technology. Publication
Publisher: Tampere University of Technology
Volume: 1220
ISSN (Print): 1459-2045

Bibliographical note

Awarding institution:Tampere University of Technology

Source: researchoutputwizard
Source ID: 997

Research output: Book/ReportDoctoral thesisCollection of Articles

Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Durech, J., Kaasalainen, M., Herald, D., Dunham, D., Timerson, B., Hanus, J., Frappa, E., Talbot, J., Hayamizu, T., Warener, B. D., Pilcher, F., Galad, A.
Pages: 652-670
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Icarus
Volume: 214
Issue number: 2
ISSN (Print): 0019-1035
Ratings: 
  • Scopus rating (2011): CiteScore 3.2 SJR 2.542 SNIP 1.22
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5899

Research output: Contribution to journalArticleScientificpeer-review

Commutative bounded integral residuated orthomodular lattices are Boolean algebras

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research Community on Data-to-Decision (D2D)
Contributors: Tladlec, J., Turunen, E.
Pages: 635-636
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Soft Computing
Volume: 15
Issue number: 4
ISSN (Print): 1432-7643
Ratings: 
  • Scopus rating (2011): CiteScore 2.38 SJR 0.844 SNIP 1.804
Original language: English

Bibliographical note

online first March 10, 2010<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9410

Research output: Contribution to journalArticleScientificpeer-review

Compact YORP formulation and stability analysis

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Kaasalainen, M., Nortunen, H.
Number of pages: 8
Pages: 1-8
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 558
Article number: A104
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2013): CiteScore 2.01 SJR 2.747 SNIP 1.203
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: EDP Sciences

Source: researchoutputwizard
Source ID: 2447

Research output: Contribution to journalArticleScientificpeer-review

Comparing two stochastic differential equation models for protein kinase C activation pathway

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Signal Processing, Department of Mathematics, Research group: Computational Systems Biology, Research group: Computational Neuro Science-CNS
Contributors: Intosalmi, J., Manninen, T., Ruohonen, K., Linne, M.
Pages: 139
Publication date: 2010

Host publication information

Title of host publication: Abstracts of Papers, Posters and Talks presented at the 2010 Joint RECOMB Satellite Conference on Systems Biology - Regulatory Genomics - DREAM5, New York, USA, 16-20 November 2010

Bibliographical note

Yhteisjulkaisu MAT kanssa<br/>Contribution: organisation=sgn,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5

Source: researchoutputwizard
Source ID: 8160

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Comparison of wood volume estimates of young trees from terrestrial laser scan data

Many analyses in ecology and forestry require wood volume estimates of trees. However, non-destructive measurements are not straightforward because trees are differing in their three-dimensional structures and shapes. In this paper we compared three methods (one voxel-based and two cylinder-based methods) for wood volume calculation of trees from point clouds obtained by terrestrial laser scanning. We analysed a total of 24 young trees, composed of four different species ranging between 1.79 m to 7.96 m in height, comparing the derived volume estimates from the point clouds with xylometric reference volumes for each tree. We found that both voxel-and cylinder-based approaches are able to compute wood volumes with an average accuracy above 90% when compared to reference volumes. The best results were achieved with the voxel-based method (r2 = 0.98). Cylinder-model based methods (r2 = 0.90 and 0.92 respectively) did perform slightly less well but offer valuable additional opportunities to analyse structural parameters for each tree. We found that the error of volume estimates from point clouds are strongly species-specific. Therefore, species-specific parameter sets for point-cloud based wood volume estimation methods are required for more robust estimates across a number of tree species.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Vodafone Department of Mobile Communications Systems, Leuphana University Lüneburg, INRA Centre de Nancy
Contributors: Kunz, M., Hess, C., Raumonen, P., Bienert, A., Hackenberg, J., Maas, H. G., Härdtle, W., Fichtner, A., Von Oheimb, G.
Number of pages: 8
Pages: 451-458
Publication date: 1 Apr 2017
Peer-reviewed: Yes

Publication information

Journal: iForest - Biogeosciences and Forestry
Volume: 10
Issue number: 2
ISSN (Print): 1971-7458
Ratings: 
  • Scopus rating (2017): CiteScore 1.47 SJR 0.533 SNIP 0.793
Original language: English
ASJC Scopus subject areas: Forestry, Ecology, Nature and Landscape Conservation
Keywords: Mixed forests, Quantitative structure models, Voxel-based, Xylometry
Source: Scopus
Source ID: 85019560771

Research output: Contribution to journalArticleScientificpeer-review

Comparison Study for Whitney (Raviart-Thomas) Type Source Models in Finite Element Method Based EEG Forward Modeling

This study concentrates on finite element method (FEM)
based electroencephalography (EEG) forward simulation in which the
electric potential evoked by neural activity in the brain is to be calculated
at the surface of the head. The main advantage of the FEM is that it allows
realistic modeling of tissue conductivity inhomogeneity. However, it is not
straightforward to apply the classical model of a dipolar source with the
FEM, due to its strong singularity and the resulting irregularity. The focus
of this study is on comparing different methods to cope with this problem.
In particular, we evaluate the accuracy of Whitney (Raviart-Thomas) type
dipole-like source currents compared to two reference dipole modeling
methods: the St. Venant and partial integration approach. Common
to all these methods is that they enable direct approximation of the
potential field utilizing linear basis functions. In the present context,
Whitney elements are particularly interesting, as they provide a simple
means to model a divergence-conforming primary current vector field
satisfying the square integrability condition. Our results show that a
Whitney type source model can provide simulation accuracy comparable
to the present reference methods. It can lead to superior accuracy under
optimized conditions with respect to both source location and orientation
in a tetrahedral mesh. For random source orientations, the St. Venant
approach turns out to be the method of choice over the interpolated
version of the Whitney model. The overall moderate differences obtained
suggest that practical aspects, such as the focality, should be prioritized
when choosing a source model.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Pursiainen, S., Bauer, M., Vorwerk, J., Köstler, H., Wolters, C. H.
Number of pages: 9
Pages: 2648-2656
Publication date: Nov 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Biomedical Engineering
Volume: 62
Issue number: 11
ISSN (Print): 0018-9294
Ratings: 
  • Scopus rating (2015): CiteScore 3.74 SJR 1.133 SNIP 2.019
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Competence advancement supported by social media

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Former organisation of the author
Contributors: Väljataga, T., Fielder, S.
Pages: 54-66
Publication date: 2008

Host publication information

Title of host publication: Proceedings of the TEN Competence Special Technology Track on Technology Support for Self-Organised Learners
Place of publication: Salzburg

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 13716

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Complex-domain Joint Broadband Hyperspectral Image Denoising

In this paper, we propose a novel complex domain denoising algorithm for hyperspectral data. The algorithm is based on the Complex Domain Block-Matching 3D (CDBM3D) filter and on similarity of hyperspectral data, which are usually slow varying for close values of wavelengths. Singular Value Decomposition (SVD) of the hyperspectral data is used in order to define an optimal small dimension data subspace. The CDBM3D is applied for 2D images of this subspace. The efficiency of the algorithm is demonstrated in simulation tests and for experimental data obtained by spectrally resolved digital holography of a transparent color object. It is proved that the proposed filtering algorithm retrieves amplitude and phase distributions even from very noisy data.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Computational Imaging-CI, Institut für Lasertechnologien in der Medizin und Messtechnik, University of Stuttgart
Contributors: Katkovnik, V., Shevkunov, I., Claus, D., Pedrini, G., Egiazarian, K.
Number of pages: 7
Pages: 33-39
Publication date: 1 May 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors and Transducers
Volume: 233
Issue number: 5
ISSN (Print): 1726-5479
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Complexity of Rainbow Vertex Connectivity Problems for Restricted Graph Classes

A path in a vertex-colored graph G is vertex rainbow if all of its internal vertices have a distinct color. The graph G is said to be rainbow vertex connected if there is a vertex rainbow path between every pair of its vertices. Similarly, the graph G is strongly rainbow vertex connected if there is a shortest path which is vertex rainbow between every pair of its vertices. We consider the complexity of deciding if a given vertex-colored graph is rainbow or strongly rainbow vertex connected. We call these problems Rainbow Vertex Connectivity and Strong Rainbow Vertex Connectivity, respectively. We prove both problems remain NP-complete on very restricted graph classes including bipartite planar graphs of maximum degree 3, interval graphs, and kk-regular graphs for k≥3k≥3. We settle precisely the complexity of both problems from the viewpoint of two width parameters: pathwidth and tree-depth. More precisely, we show both problems remain NP-complete for bounded pathwidth graphs, while being fixed-parameter tractable parameterized by tree-depth. Moreover, we show both problems are solvable in polynomial time for block graphs, while Strong Rainbow Vertex Connectivity is tractable for cactus graphs and split graphs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Lauri, J.
Number of pages: 14
Pages: 132-146
Publication date: 11 Mar 2017
Peer-reviewed: Yes
Early online date: 15 Dec 2016

Publication information

Journal: Discrete Applied Mathematics
Volume: 219
ISSN (Print): 0166-218X
Ratings: 
  • Scopus rating (2017): CiteScore 1.05 SJR 0.785 SNIP 1.241
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Composite Nonlinear Feedback Control of a Chemical Reactor

This paper studies the application of composite nonlinear feedback (CNF) control for a continuous time stirred tank reactor. Inside the reactor, an exothermic chemical reaction occurs, which requires cooling when concentration is commanded from low to high conversion rate to prevent a thermal runaway. A full-state CNF controller is designed for adjusting the temperature of the cooling jacket using concentration and temperature measurements. A continuous time gain-scheduled cascade controller, as well as a model predictive controller (MPC) is also fabricated for comparison. The gain-scheduled cascade controller has a proportional-integral (PI) controller as a primary loop controller, and a P-controller as a secondary loop controller. The simulation results show that the CNF controller is able to offer the best overall tracking performance as measured by the integral-of-absolute-error (IAE) criterion. In addition, the CNF controller does not need gain-scheduling for tuning purposes; the CNF controller is capable of changing its tuning as a function of control error only.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research area: Information Systems in Automation, Research area: Dynamic Systems, Department of Automation Science and Engineering
Contributors: Pyrhönen, V., Koivisto, H.
Publication date: 18 Mar 2015

Host publication information

Title of host publication: Proceedings of AutomaatioXXI, The Industrial Revolution of Internet – From Intelligent Devices to Networked Intelligence
Place of publication: Helsinki, Finland
Publisher: Suomen Automaatioseura ry
ISBN (Electronic): 978-952-5183-46-7

Publication series

Name: SAS julkaisusarja
Publisher: Finnish Society of Automation
Volume: 44
Keywords: exothermic reaction, nonlinear control, nonlinear dynamics, cascade control

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Comprehensive Quantitative Tree Models from TLS Data

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Åkerblom, M., Raumonen, P., Kaasalainen, M., Kaasalainen, S., Kaartinen, H.
Pages: 6507-6510
Publication date: 2012

Host publication information

Title of host publication: IEEE International Geoscience and Remote Sensing Symposium, IGARSS, 2012, 22.-27.7.2012, Munich, Germany
Place of publication: Piscataway, NJ
Publisher: Institute of Electrical and Electronics Engineers IEEE
Article number: 13133382
ISBN (Print): 978-1-4673-1160-1
ISBN (Electronic): 978-1-4673-1158-8

Publication series

Name: IEEE International Geoscience and Remote Sensing Symposium
ISSN (Print): 2153-6996

Bibliographical note

Poistettu tupla r=3140<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 3825

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Computational Model for Simulating Multifocal Imaging in Optical Projection Tomography

We present a computational model describing the blurring of particles with respect to focal distance in 3D optical imaging. The model can be used to improve reconstructions in optical projection tomography.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Computational Biophysics and Imaging Group, Mathematics, Research group: Inverse Problems, International Iberian Nanotechnology Laboratory
Contributors: Koskela, O., Belay, B., Pursiainen, S., Figueiras, E., Hyttinen, J.
Number of pages: 3
Publication date: 2017

Host publication information

Title of host publication: Mathematics in Imaging 2017
Publisher: Optical Society of America
Article number: MTu1C.3
ISBN (Electronic): 978-1-943580-29-3
Electronic versions: 
URLs: 

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Computational study of noise in a large signal transduction network

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Department of Mathematics, Research group: Computational Neuro Science-CNS, Research group: Computational Systems Biology
Contributors: Intosalmi, J., Manninen, T., Ruohonen, K., Linne, M.
Number of pages: 8
Pages: 1-8
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: BMC Bioinformatics
Volume: 12
Article number: 252
ISSN (Print): 1471-2105
Ratings: 
  • Scopus rating (2011): CiteScore 3.34 SJR 1.662 SNIP 1.196
Original language: English

Bibliographical note

Contribution: organisation=sgn,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5

Source: researchoutputwizard
Source ID: 6171

Research output: Contribution to journalArticleScientificpeer-review

Compute mindlessly. Not! map consciously

This paper utilizes concept mapping as a tool for conscious and deliberate knowledge building in mathematics and its extension to algorithms. Currently, alleged defects in mathematics education are obvious: instead of conceptual elaboration, everyday praxis relies on routine computations that are likely to lead into alienated concepts with weak connections to prior knowledge. A concept map visualizes the existing conceptual structure, and whenever new information is brought in, it will be placed in the map by clearly explicating its linkage to the previous concepts. In the Finnish mathematics education, such new knowledge is programming content that is integrated into elementary school mathematics in 2014 Finnish National Curriculum. This content is crystallized as the requirements of computational and algorithmic thinking, the utilization of respective data structures, and adequate amount of hands-on practice to internalize good coding conventions. This study examines secondary (N = 19) and higher education students (N = 10) and their conceptual knowledge of mathematics concentrating on the domain of algorithms in particular. The concept maps drawn by the students are evaluated using the SOLO taxonomy. To conclude, a consensus map of algorithms is represented and linked to the elementary mathematics syllabus.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research area: Software engineering, Computing Sciences, Department of Education, Ideal Learning Oy
Contributors: Niemelä, P., Mikkolainen, V., Vuorinen, J.
Number of pages: 10
Pages: 2669-2678
Publication date: 1 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Universal Journal of Educational Research
Volume: 6
Issue number: 11
ISSN (Print): 2332-3205
Original language: English
ASJC Scopus subject areas: Education
Keywords: Concept Mapping, Meta-cognitive Skills, SOLO Taxonomy, Visualizations
Electronic versions: 
Source: Scopus
Source ID: 85061665318

Research output: Contribution to journalArticleScientificpeer-review

Computing minimum rainbow and strong rainbow colorings of block graphs

A path in an edge-colored graph G is rainbow if no two edges of it are colored the same. The graph G is rainbowconnected if there is a rainbow path between every pair of vertices. If there is a rainbow shortest path between every pair of vertices, the graph G is strongly rainbow-connected. The minimum number of colors needed to make G rainbow-connected is known as the rainbow connection number of G, and is denoted by rc(G). Similarly, the minimum number of colors needed to make G strongly rainbow-connected is known as the strong rainbow connection number ofG, and is denoted by src(G). We prove that for every k ≥ 3, deciding whether src(G) ≤ k is NP-complete for split graphs, which form a subclass of chordal graphs. Furthermore, there exists no polynomial-time algorithm for approximating the strong rainbow connection number of an n-vertex split graph with a factor of n1-2-ϵ for any ϵ > 0 unless P = NP. We then turn our attention to block graphs, which also form a subclass of chordal graphs. We determine the strong rainbow connection number of block graphs, and show it can be computed in linear time. Finally, we provide a polynomial-time characterization of bridgeless block graphs with rainbow connection number at most 4.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Michigan Technological University, Bell Labs
Contributors: Keranen, M., Lauri, J.
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: Discrete Mathematics and Theoretical Computer Science
Volume: 20
Issue number: 1
Article number: 22
ISSN (Print): 1462-7264
Original language: English
ASJC Scopus subject areas: Theoretical Computer Science, Computer Science(all), Discrete Mathematics and Combinatorics
Keywords: Block graph, Computational complexity, Rainbow coloring
Electronic versions: 
Source: Scopus
Source ID: 85049392046

Research output: Contribution to journalArticleScientificpeer-review

Considering learners' perspectives to personal learning environments in course design

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Former organisation of the author
Contributors: Väljataga, T., Pata, K., Tammets, K.
Number of pages: 24
Pages: 85-108
Publication date: 2010

Host publication information

Title of host publication: WEB 2.0 Based E-Learning: Applying Social Informatics for Tertiary Teaching
Place of publication: Hershey
Publisher: IGI Global
Editor: Lee, M.

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9503

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Constructing Minimal Coverability Sets

This publication addresses two bottlenecks in the construction of minimal coverability sets of Petri nets: the detection of situations where the marking of a place can be converted to ω, and the manipulation of the set A of maximal ω-markings that have been found so far. For the former, a technique is presented that consumes very little time in addition to what maintaining A consumes. It is based on Tarjan's algorithm for detecting maximal strongly connected components of a directed graph. For the latter, a data structure is introduced that resembles BDDs and Covering Sharing Trees, but has additional heuristics designed for the present use. Results from a few experiments are shown. They demonstrate significant savings in running time and varying savings in memory consumption compared to an earlier state-of-the-art technique.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Computer Science and Applied Logics
Contributors: Piipponen, A., Valmari, A.
Number of pages: 22
Pages: 393-414
Publication date: 4 Mar 2016
Peer-reviewed: Yes

Publication information

Journal: Fundamenta Informaticae
Volume: 143
Issue number: 3-4
ISSN (Print): 0169-2968
Ratings: 
  • Scopus rating (2016): CiteScore 0.86 SJR 0.371 SNIP 0.712
Original language: English
ASJC Scopus subject areas: Information Systems, Computational Theory and Mathematics, Theoretical Computer Science, Algebra and Number Theory
Keywords: antichain data structure, coverability set, Tarjan's algorithm
Source: Scopus
Source ID: 84959877143

Research output: Contribution to journalArticleScientificpeer-review

Context Awareness for Semantic Mobile Computing

In a plethora of smart phones and related mobile applications, users crave innovative and personalized services that adapt to their situation. To achieve that, smart phones need to understand user context and needs for latter providing them with adequate services. This chapter discusses how context can be understood, represented and exploited in smart phones, using techniques from the fields of Semantic Computing, Machine Learning and Graph Theory.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Mathematics, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Rivero-Rodriguez, A., Nykänen, O.
Number of pages: 17
Pages: 251-267
Publication date: 2017

Host publication information

Title of host publication: Multi-Technology Positioning
Place of publication: Cham
Publisher: Springer International Publishing
Editors: Nurmi, J., Lohan, E., Wymeersch, H., Seco-Granados, G., Nykänen, O.
ISBN (Print): 978-3-319-50426-1
ISBN (Electronic): 978-3-319-50427-8
Source: Bibtex
Source ID: urn:2f5582c69455f55e5551e9f220081242

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Context-Driven Social Network Visualisation: Case Wiki Co-Creation

Along social media and Web 2.0, the amount of data sources potentially available for social network visualisation has snowballed. Recent development on information visualisation technologies contribute to the availability of tools enabling visualisation of social media data. Yet, applying the tools in diff erent usage contexts is often diffcult. The data formats vary and many of the tools are platform-specific. Potential tools each have their strengths but often a single tool is not suffcient for covering all the aspects of analysis. In this paper, we describe the means of applying component-based information visualisation to streamline social network visualisation. Further, through our approach, we seek to narrow the gap between everyday knowledge work and visual social network analysis of the data that knowledge workers process. We acknowledge the need of programming skills in introducing the visualisations to different usage contexts but yet we see that teams of analysts can apply the approach when conducting network analysis in varying contexts. The main contributions of this article are the following: a description and an analysis of a streamlined social network visual analysis process and a brief review of the related applications and tools, based on the idea of conceptual integration of visual social network analysis and augmented browsing.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Huhtamäki, J., Salonen, J., Marttila, J., Nykänen, O.
Number of pages: 13
Pages: 1-13
Publication date: 2010

Host publication information

Title of host publication: Proceedings of the Knowledge Federation 2010: Self-Organizing Collective Mind, October 3-6, 2010, Dubrovnik, Croatia
Editors: Karabeg, D., Park, J.

Bibliographical note

Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 8103

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Controller Design for Robust Output Regulation of Regular Linear Systems

We present three dynamic error feedback controllers for robust output regulation of regular linear systems. These controllers are (i) a minimal order robust controller for exponentially stable systems (ii) an observer-based robust controller and (iii) a new internal model based robust controller structure. In addition, we present two controllers that are by construction robust with respect to predefined classes of perturbations. The results are illustrated with an example where we study robust output tracking of a sinusoidal reference signal for a two-dimensional heat equation with boundary control and observation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Mathematical and semantic modelling
Contributors: Paunonen, L.
Pages: 2974-2986
Publication date: 2016
Peer-reviewed: Yes
Early online date: 2015

Publication information

Journal: IEEE Transactions on Automatic Control
Volume: 61
Issue number: 10
ISSN (Print): 0018-9286
Ratings: 
  • Scopus rating (2016): CiteScore 5.54 SJR 3.232 SNIP 2.708
Original language: English
Keywords: Linear systems, Robustness, Robust output regulation, controller design, feedback, regular linear systems
Electronic versions: 
Source: Bibtex
Source ID: urn:da65ce94eaad6e902a97ef0e5d16351d

Research output: Contribution to journalArticleScientificpeer-review

Cubature-based Kalman filters for positioning

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Pesonen, H., Piche, R.
Pages: 45-49
Publication date: 2010

Host publication information

Title of host publication: Proceedings of the 7th Workshop on Positioning, Navigation and Communication 2010 WPNC'10, 11-12 March 2010, Dresden, Germany
ISBN (Print): 978-1-4244-7157-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8990

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Cuts for 3-D magnetic scalar potentials: Visualizing unintuitive surfaces arising from trivial knots

A wealth of literature exists on computing and visualizing cuts for the magnetic scalar potential of a current carrying conductor via Finite Element Methods (FEM) and harmonic maps to the circle. By a cut we refer to an orientable surface bounded by a given current carrying path (such that the flux through it may be computed) that restricts contour integrals on a curl-zero vector field to those that do not link the current-carrying path, analogous to branch cuts of complex analysis. This work is concerned with a study of a peculiar contour that illustrates topologically unintuitive aspects of cuts obtained from a trivial loop and raises questions about the notion of an optimal cut. Specifically, an unknotted curve that bounds only high genus surfaces in its convex hull is analyzed. The current work considers the geometric realization as a current-carrying wire in order to construct a magnetic scalar potential. Moreover, we consider the problem of choosing an energy functional on the space of maps, suggesting an algorithm for computing cuts via minimizing a conformally invariant functional utilizing Newton iteration.

General information

Publication status: Accepted/In press
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Boston University
Contributors: Stockrahm, A., Lahtinen, V., Kangas, J. J., Kotiuga, P. R.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Computers and Mathematics with Applications
ISSN (Print): 0898-1221
Original language: English
ASJC Scopus subject areas: Modelling and Simulation, Computational Theory and Mathematics, Computational Mathematics
Keywords: Homology, Magnetic fields, Visualization
Source: Scopus
Source ID: 85067239229

Research output: Contribution to journalArticleScientificpeer-review

CytoSpectre: A tool for spectral analysis of oriented structures on cellular and subcellular levels

Background: Orientation and the degree of isotropy are important in many biological systems such as the sarcomeres of cardiomyocytes and other fibrillar structures of the cytoskeleton. Image based analysis of such structures is often limited to qualitative evaluation by human experts, hampering the throughput, repeatability and reliability of the analyses. Software tools are not readily available for this purpose and the existing methods typically rely at least partly on manual operation.

Results: We developed CytoSpectre, an automated tool based on spectral analysis, allowing the quantification of orientation and also size distributions of structures in microscopy images. CytoSpectre utilizes the Fourier transform to estimate the power spectrum of an image and based on the spectrum, computes parameter values describing, among others, the mean orientation, isotropy and size of target structures. The analysis can be further tuned to focus on targets of particular size at cellular or subcellular scales. The software can be operated via a graphical user interface without any programming expertise. We analyzed the performance of CytoSpectre by extensive simulations using artificial images, by benchmarking against FibrilTool and by comparisons with manual measurements performed for real images by a panel of human experts. The software was found to be tolerant against noise and blurring and superior to FibrilTool when analyzing realistic targets with degraded image quality. The analysis of real images indicated general good agreement between computational and manual results while also revealing notable expert-to-expert variation. Moreover, the experiment showed that CytoSpectre can handle images obtained of different cell types using different microscopy techniques. Finally, we studied the effect of mechanical stretching on cardiomyocytes to demonstrate the software in an actual experiment and observed changes in cellular orientation in response to stretching.

Conclusions: CytoSpectre, a versatile, easy-to-use software tool for spectral analysis of microscopy images was developed. The tool is compatible with most 2D images and can be used to analyze targets at different scales. We expect the tool to be useful in diverse applications dealing with structures whose orientation and size distributions are of interest. While designed for the biological field, the software could also be useful in non-biological applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Integrated Technologies for Tissue Engineering Research (ITTE), Department of Automation Science and Engineering, Research area: Microsystems, Research area: Measurement Technology and Process Control, Univ Tampere, University of Tampere, Sch Med, Hearing & Balance Res Unit, Field Otolaryngol, Univ Tampere, University of Tampere, BioMediTech, BMT FM5, Univ Tampere, University of Tampere, Sch Informat Sci, Tampere Univ Technol, Tampere University of Technology, Heart Hosp
Contributors: Kartasalo, K., Polonen, R., Ojala, M., Rasku, J., Lekkala, J., Aalto-Setälä, K., Kallio, P.
Number of pages: 23
Publication date: 26 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: BMC Bioinformatics
Volume: 16
Issue number: 1
Article number: 344
ISSN (Print): 1471-2105
Ratings: 
  • Scopus rating (2015): CiteScore 2.77 SJR 1.737 SNIP 1.068
Original language: English
Keywords: Orientation, Isotropy, Spectral analysis, Fourier transform, Power spectrum, Image analysis, Microscopy, Artificial images, Cardiomyocytes, Stretching, FAST FOURIER-TRANSFORM, PLURIPOTENT STEM-CELLS, QUANTITATIVE-ANALYSIS, AUTOMATED MEASUREMENT, MICROSCOPY IMAGES, CARDIOMYOCYTES, ORIENTATION, ALIGNMENT, DIFFERENTIATION, MATURATION
Electronic versions: 
Source: WOS
Source ID: 000363375000001

Research output: Contribution to journalArticleScientificpeer-review

DAMIT: a database of asteroid models

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Durech, J., Sidorin, V., Kaasalainen, M.
Number of pages: 13
Pages: 1-13
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 513
Issue number: A46
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2010): SJR 2.849 SNIP 1.396
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7858

Research output: Contribution to journalArticleScientificpeer-review

Data-based stochastic modeling of tree growth and structure formation

We introduce a general procedure to match a stochastic functional-structural tree model (here LIGNUM augmented with stochastic rules) with real tree structures depicted by quantitative structure models (QSMs) based on terrestrial laser scanning. The matching is done by iteratively finding the maximum correspondence between the measured tree structure and the stochastic choices of the algorithm. First, we analyze the match to synthetic data (generated by the model itself), where the target values of the parameters to be estimated are known in advance, and show that the algorithm converges properly. We then carry out the procedure on real data obtaining a realistic model. We thus conclude that the proposed stochastic structure model (SSM) approach is a viable solution for formulating realistic plant models based on data and accounting for the stochastic influences.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Potapov, I., Järvenpää, M., Åkerblom, M., Raumonen, P., Kaasalainen, M.
Publication date: 2016
Peer-reviewed: Yes
Early online date: 3 Nov 2015

Publication information

Journal: Silva Fennica
Volume: 50
Issue number: 1
Article number: 1413
ISSN (Print): 0037-5330
Ratings: 
  • Scopus rating (2016): CiteScore 1.45 SJR 0.702 SNIP 1.116
Original language: English
ASJC Scopus subject areas: Ecological Modelling, Forestry
Keywords: Data fitting, Form diversity, Morphological plasticity, Plant model, Quantitative structure models, Stochastic functional-structural, Terrestrial lidar
Source: Scopus
Source ID: 84983200698

Research output: Contribution to journalArticleScientificpeer-review

Datamap Visualization Technique for Interactively Visualizing Large Datasets

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Nykänen, O.
Number of pages: 7
Pages: 52-58
Publication date: 2013

Host publication information

Title of host publication: 17th International Academic MindTrek Conference, October 1-4, 2013, Tampere, Finland
Publisher: ACM
Editors: Lugmayr, A., Franssila, H., Kärkkäinen, H., Paavilainen, J.
ISBN (Print): 978-1-4503-1992-8

Publication series

Name: MindTrek Conference

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: ACM

Source: researchoutputwizard
Source ID: 3027

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Datapohjaiset mallit

General information

Publication status: Published
MoE publication type: B2 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Merikoski, J., Turunen, E., Raivio, K., Mantere, T.
Pages: 77-146
Publication date: 2010

Host publication information

Title of host publication: Matemaattinen mallinnus
Place of publication: Helsinki
Publisher: WSOYpro
Editor: Pohjolainen, S.
ISBN (Print): 978-951-0-35408-7

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8774

Research output: Chapter in Book/Report/Conference proceedingChapterScientific

Designing controllers with reduced order internal models

In this technical note we study robust output tracking for autonomous linear systems. We introduce a new approach to designing robust controllers using a recent observation that a full internal model is not always necessary for robustness. Especially this may be the case if the control law is only required to be robust with respect to a specific predetermined class of uncertainties in the parameters of the plant. The results are illustrated with an example on robust output tracking for coupled harmonic oscillators.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Mathematical and semantic modelling
Contributors: Paunonen, L.
Number of pages: 6
Pages: 775-780
Publication date: 1 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Automatic Control
Volume: 60
Issue number: 3
Article number: 6826480
ISSN (Print): 0018-9286
Ratings: 
  • Scopus rating (2015): CiteScore 5.08 SJR 4.285 SNIP 3.218
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Control and Systems Engineering, Computer Science Applications
Source: Scopus
Source ID: 84923355671

Research output: Contribution to journalArticleScientificpeer-review

Detection of anomalies in radio tomography of asteroids: source count and forward errors

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Pursiainen, S., Kaasalainen, M.
Number of pages: 12
Pages: 36-47
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Planetary and Space Science
Volume: 99
ISSN (Print): 0032-0633
Ratings: 
  • Scopus rating (2014): CiteScore 1.96 SJR 1.118 SNIP 0.913
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-12-17<br/>Publisher name: Pergamon

Source: researchoutputwizard
Source ID: 1309

Research output: Contribution to journalArticleScientificpeer-review

Detection of the YORP effect in asteroid (1620) Geographos

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Durech, J., Vokrouhlicky, D., Kaasalainen, M., Higgins, D., Krugly, Y., Gaftonyuk, N., Shevchenko, V., Chiorny, V., Hamanowa, H., Reddy, V., Dyvig, R.
Pages: pp. L25-L28
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 489
Issue number: 2
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2008): SJR 2.907 SNIP 1.336
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 12021

Research output: Contribution to journalArticleScientificpeer-review

Developing Learning and Teaching in Engineering Mathematics with and without Technology

University teachers of mathematics have begun to observe that nowadays new students when beginning their studies do not have as good a mathematical proficiency as before. The phenomenon has been noticed in all western countries during recent decades [1, 2]. What shall we do? We think that there are at least two available courses of action for improved learning results in university mathematics: 1) to identify as soon as possible the students who have an insufficient knowledge base in mathematics, and to begin remedial instruction for them, and 2) to develop mathematics learning environments both with and without technology.

The aim of this paper is to describe how Tampere University of Technology (TUT) has developed learning environments in mathematics during the last decade. We focus in the paper on two cases: 1) a multisemiotic approach to mathematical concepts and procedures, and 2) computer aided assessment and learning systems.

The first case consists of developing studies in mathematical exercises in which new kinds of problem-solving have been constructed. In the second case new students have participated in an ICT –based basic skills test at the beginning of their mathematics studies, to enable them to practice mathematical procedures in solving processes [3]. Electronic and web-based tools make it possible for students to learn independently at any time, and for teachers, offer an effective way to evaluate students’ proficiency.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Mathematics, Research group: MAT Positioning, Research group: Positioning, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Joutsenlahti, J., Ali-Löytty, S., Pohjolainen, S.
Publication date: 15 Sep 2016

Host publication information

Title of host publication: SEFI 2016 Annual Conference Proceedings : Engineering Education on Top of the World: Industry University Cooperation
Publisher: European Society for Engineering Education SEFI
ISBN (Electronic): 9782873520144

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Device self-calibration in location systems using signal strength histograms

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Laoudias, C., Piche, R., Panayiotou, C. G.
Number of pages: 17
Pages: 165-181
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Location Based Services
Volume: 7
Issue number: 3
ISSN (Print): 1748-9725
Ratings: 
  • Scopus rating (2013): CiteScore 0.96 SJR 0.421 SNIP 0.923
Original language: English

Bibliographical note

Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: Taylor & Francis

Source: researchoutputwizard
Source ID: 2723

Research output: Contribution to journalArticleScientificpeer-review

Dimensional Reduction of Electromagnetic Boundary Value Problems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Department of Electronics
Contributors: Raumonen, P., Suuriniemi, S., Kettunen, L.
Number of pages: 25
Pages: 1-25
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Boundary Value Problems
Volume: 2011
Article number: 9
ISSN (Print): 1687-2762
Ratings: 
  • Scopus rating (2011): CiteScore 0.9 SJR 0.842 SNIP 0.639
Original language: English

Bibliographical note

50 % Matematiikka, 50 % Sähkömagnetiikka<br/>Contribution: organisation=mat,FACT1=0.5<br/>Contribution: organisation=ele smg,FACT2=0.5

Source: researchoutputwizard
Source ID: 7106

Research output: Contribution to journalArticleScientificpeer-review

Directed structure at infinity for infinite-dimensional systems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Laakkonen, P., Pohjolainen, S.
Pages: 702-715
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: International Journal of Control
Volume: 84
Issue number: 4
ISSN (Print): 0020-7179
Ratings: 
  • Scopus rating (2011): CiteScore 1.67 SJR 1.3 SNIP 1.326
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6490

Research output: Contribution to journalArticleScientificpeer-review

Discrete maximum principles for FE solutions of nonstationary diffusion-reaction problems with mixed boundary conditions

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Farago, I., Horvath, R., Korotov, S.
Pages: 702-720
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Numerical Methods for Partial Differential Equations
Volume: 27
Issue number: 3
ISSN (Print): 0749-159X
Ratings: 
  • Scopus rating (2011): CiteScore 1.54 SJR 1.167 SNIP 0.948
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5940

Research output: Contribution to journalArticleScientificpeer-review

DISCUS – The Deep Interior Scanning CubeSat mission to a rubble pile near-Earth asteroid

We have performed an initial stage conceptual design study for the Deep Interior Scanning CubeSat (DISCUS), a tandem 6U CubeSat carrying a bistatic radar as the main payload. DISCUS will be operated either as an independent mission or accompanying a larger one. It is designed to determine the internal macroporosity of a 260–600 m diameter Near Earth Asteroid (NEA) from a few kilometers distance. The main goal will be to achieve a global penetration with a low-frequency signal as well as to analyze the scattering strength for various different penetration depths and measurement positions. Moreover, the measurements will be inverted through a computed radar tomography (CRT) approach. The scientific data provided by DISCUS would bring more knowledge of the internal configuration of rubble pile asteroids and their collisional evolution in the Solar System. It would also advance the design of future asteroid deflection concepts. We aim at a single-unit (1U) radar design equipped with a half-wavelength dipole antenna. The radar will utilize a stepped-frequency modulation technique the baseline of which was developed for ESA's technology projects GINGER and PIRA. The radar measurements will be used for CRT and shape reconstruction. The CubeSat will also be equipped with an optical camera system and laser altimeter to support navigation and shape reconstruction. We provide the details of the measurement methods to be applied along with the requirements derived from the known characteristics of rubble pile asteroids. Additionally, an initial design study of the platform and targets accessible within 20 lunar distances are presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Max Planck Institute for Solar System Research, RST Radar Systemtechnik AG, MEW-Aerospace UG
Contributors: Bambach, P., Deller, J., Vilenius, E., Pursiainen, S., Takala, M., Braun, H. M., Lentz, H., Wittig, M.
Pages: 3357-3368
Publication date: Dec 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Advances in Space Research
Volume: 62
Issue number: 12
ISSN (Print): 0273-1177
Ratings: 
  • Scopus rating (2018): CiteScore 1.97 SJR 0.589 SNIP 1.186
Original language: English
ASJC Scopus subject areas: Aerospace Engineering, Space and Planetary Science
Keywords: Computed radar tomography, Deep-space CubeSat, Near earth asteroid, Radar, Rubble pile asteroid
Source: Scopus
Source ID: 85049333928

Research output: Contribution to journalArticleScientificpeer-review

Distribution of shape elongations of main belt asteroids derived from Pan-STARRS1 photometry

Context. A considerable amount of photometric data is produced by surveys such as Pan-STARRS, LONEOS, WISE, or Catalina. These data are a rich source of information about the physical properties of asteroids. There are several possible approaches for using these data. Light curve inversion is a typical method that works with individual asteroids. Our approach in focusing on large groups of asteroids, such as dynamical families and taxonomic classes, is statistical; the data are not sufficient for individual models.Aim. Our aim is to study the distributions of shape elongation ba and the spin axis latitude β for various subpopulations of asteroids and to compare our results, based on Pan-STARRS1 survey, with statistics previously carried out using various photometric databases, such as Lowell and WISE.Methods. We used the LEADER algorithm to compare the ba and β distributions for various subpopulations of asteroids. The algorithm creates a cumulative distributive function (CDF) of observed brightness variations, and computes the ba and β distributions with analytical basis functions that yield the observed CDF. A variant of LEADER is used to solve the joint distributions for synthetic populations to test the validity of the method.Results. When comparing distributions of shape elongation for groups of asteroids with different diameters D, we found that there are no differences for D < 25 km. We also constructed distributions for asteroids with different rotation periods and revealed that the fastest rotators with P = 0 - 4 h are more spheroidal than the population with P = 4-8 h.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Charles University in Prague, Harvard-Smithsonian Center for Astrophysics, Institute for Astronomy University of Hawaii, Northern Arizona University
Contributors: Cibulková, H., Nortunen, H., Ďurech, J., Kaasalainen, M., Vereš, P., Jedicke, R., Wainscoat, R. J., Mommert, M., Trilling, D. E., Schunová-Lilly, E., Magnier, E. A., Waters, C., Flewelling, H.
Number of pages: 10
Publication date: 1 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 611
Article number: A86
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2018): CiteScore 4.54 SJR 2.527 SNIP 1.233
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: asteroids, general, Methods, Minor planets, photometric, statistical, Techniques
Electronic versions: 
Source: Scopus
Source ID: 85045197138

Research output: Contribution to journalArticleScientificpeer-review

Distribution of spin-axes longitudes and shape elongations of main-belt asteroids

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Cibulkova, H., Durech, J., Vokrouhlicky, D., Kaasalainen, M., Oszkiewicz, D. A.
Number of pages: 10
Publication date: Dec 2016
Peer-reviewed: Yes
Early online date: 30 Nov 2016

Publication information

Journal: Astronomy and Astrophysics
Volume: 596
Article number: A57
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2016): CiteScore 3.68 SJR 2.234 SNIP 1.253
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Dual Look at Robust Regulation: Frequency Domain and State Space Approaches

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Laakkonen, P., Paunonen, L., Pohjolainen, S.
Pages: 136-141
Publication date: 2012

Host publication information

Title of host publication: Proceedings of MMAR 2012. 17th International Conference on Methods and Models in Automation & Robotics, MMAR 2012, 27-30 August 2012, Miedzyzdroje, Poland
Place of publication: Piscataway, NJ
Publisher: Institute of Electrical and Electronics Engineers IEEE
Article number: 13117991
ISBN (Print): 978-1-4673-2121-1
ISBN (Electronic): 978-1-4673-2123-5

Publication series

Name: International Conference on Methods and Models in Automation & Robotics

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 4592

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Dynamical tomography of gravitationally bound systems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Kaasalainen, M.
Pages: 527-546
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Inverse Problems and Imaging
Volume: 2
Issue number: 4
ISSN (Print): 1930-8337
Ratings: 
  • Scopus rating (2008): SJR 0.463 SNIP 1.294
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 12423

Research output: Contribution to journalArticleScientificpeer-review

Editorial: is Game-Based Math Learning Finally Coming of Age?

General information

Publication status: Published
MoE publication type: B1 Article in a scientific magazine
Organisations: Pori Department, Research group: TUT Game Lab, Stanford University
Contributors: Kiili, K., Devlin, K., Multisilta, J.
Number of pages: 4
Publication date: 8 Dec 2015
Peer-reviewed: No

Publication information

Journal: International Journal of Serious Games
Volume: 2
Issue number: 4
Article number: 1
ISSN (Print): 2384-8766
Original language: English

Research output: Contribution to journalEditorialScientific

Electroencephalography (EEG) forward modeling via H(div) finite element sources with focal interpolation

The goal of this study is to develop focal, accurate and robust finite element method (FEM) based approaches which can predict the electric potential on the surface of the computational domain given its structure and internal primary source current distribution. While conducting an EEG evaluation, the placement of source currents to the geometrically complex grey matter compartment is a challenging but necessary task to avoid forward errors attributable to tissue conductivity jumps. Here, this task is approached via a mathematically rigorous formulation, in which the current field is modeled via divergence conforming H(div) basis functions. Both linear and quadratic functions are used while the potential field is discretized via the standard linear Lagrangian (nodal) basis. The resulting model includes dipolar sources which are interpolated into a random set of positions and orientations utilizing two alternative approaches: the position based optimization (PBO) and the mean position/orientation (MPO) method. These results demonstrate that the present dipolar approach can reach or even surpass, at least in some respects, the accuracy of two classical reference methods, the partial integration (PI) and St. Venant (SV) approach which utilize monopolar loads instead of dipolar currents.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Pursiainen, S., Vorwerk, J., Wolters, C. H.
Number of pages: 19
Pages: 8502-8520
Publication date: 15 Nov 2016
Peer-reviewed: Yes

Publication information

Journal: Physics in Medicine and Biology
Volume: 61
Issue number: 24
ISSN (Print): 0031-9155
Ratings: 
  • Scopus rating (2016): CiteScore 3.08 SJR 1.381 SNIP 1.449
Original language: English
Source: PubMed
Source ID: 27845929

Research output: Contribution to journalArticleScientificpeer-review

Elementary Partial Differential Equations. Theory and Solved Problems.

General information

Publication status: Published
MoE publication type: C1 Separate scientific books
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning
Contributors: Piche, R.
Number of pages: 131
Publication date: 2012

Publication information

Place of publication: Saarbrücken, Germany
Publisher: Lambert Academic Publishing
ISBN (Print): 978-3-659-23987-8
Original language: English

Bibliographical note

ei ut-numeroa 28.8.2013<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5062

Research output: Book/ReportBookScientificpeer-review

Emptiness problems for distributed automata

We investigate the decidability of the emptiness problem for three classes of distributed automata. These devices operate on finite directed graphs, acting as networks of identical finite-state machines that communicate in an infinite sequence of synchronous rounds. The problem is shown to be decidable in LOGSPACE for a class of forgetful automata, where the nodes see the messages received from their neighbors but cannot remember their own state. When restricted to the appropriate families of graphs, these forgetful automata are equivalent to classical finite word automata, but strictly more expressive than finite tree automata. On the other hand, we also show that the emptiness problem is undecidable in general. This already holds for two heavily restricted classes of distributed automata: those that reject immediately if they receive more than one message per round, and those whose state diagram must be acyclic except for self-loops. Additionally, to demonstrate the flexibility of distributed automata in simulating different models of computation, we provide a characterization of constraint satisfaction problems by identifying a class of automata with exactly the same computational power.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Helsinki University, UPEM
Contributors: Kuusisto, A., Reiter, F.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Information and Computation
Article number: 104503
ISSN (Print): 0890-5401
Original language: English
ASJC Scopus subject areas: Theoretical Computer Science, Information Systems, Computer Science Applications, Computational Theory and Mathematics
Keywords: Distributed computing, Emptiness problem, Finite automata
Source: Scopus
Source ID: 85076991997

Research output: Contribution to journalArticleScientificpeer-review

Energy conversion efficiency of the pumping kite wind generator

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Argatov, I., Silvennoinen, R.
Pages: 1052-1060
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Renewable Energy
Volume: 35
ISSN (Print): 0960-1481
Ratings: 
  • Scopus rating (2010): SJR 1.459 SNIP 2.202
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7706

Research output: Contribution to journalArticleScientificpeer-review

Engineering Mathematics Education in Finland: A Comparative Analysis of EU, Russia, Georgia and Armenia

General information

Publication status: Published
MoE publication type: D2 Article in professional manuals or guides or professional information systems or text book material
Organisations: Mathematics, Research group: Computer Science and Applied Logics
Contributors: Pohjolainen, S., Myllykoski, T.
Number of pages: 7
Pages: 69-75
Publication date: 2018

Host publication information

Title of host publication: Modern Mathematics Education for Engineering Curricula in Europe
Publisher: Birkhäuser
Editors: Pohjolainen, S., Myllykoski, T., Mercat, C., Sosnovsky, S.
ISBN (Print): 978-3-319-71415-8
ISBN (Electronic): 978-3-319-71416-5

Research output: Chapter in Book/Report/Conference proceedingChapterProfessional

Engineering motif search for large graphs

In the graph motif problem, we are given as input a vertexcolored graph H (the host graph) and a multiset of colors M (the motif). Our task is to decide whether H has a connected set of vertices whose multiset of colors agrees with M. The graph motif problem is NP-complete but known to admit parameterized algorithms that run in linear time in the size of H. We demonstrate that algorithms based on constrained multilinear sieving are viable in practice, scaling to graphs with hundreds of millions of edges as long as M remains small. Furthermore, our implementation is topologyinvariant relative to the host graph H, meaning only the most crude graph parameters (number of edges and number of vertices) suffice in practice to determine the algorithm performance.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Aalto University, Lunds Universitet / Lunds Tekniska Högskola, Lund Univ, Lund University, University of Calgary, Institute for Biocomplexity and Informatics, Canada, Medical University of Warsaw, Helsinki Institute for Information Technology HIIT, Department of Computer Science and Information Systems
Contributors: Björklund, A., Kaski, P., Kowalik, Ł., Lauri, J.
Number of pages: 15
Pages: 104-118
Publication date: 2015

Host publication information

Title of host publication: 2015 Proceedings of the Seventeenth Workshop on Algorithm Engineering and Experiments (ALENEX)
ISBN (Electronic): 978-1-61197-375-4

Publication series

Name: Workshop on Algorithm Engineering and Experiments
ISSN (Print): 2164-0300
ASJC Scopus subject areas: Engineering(all), Applied Mathematics
Source: Scopus
Source ID: 84937777832

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Equal Opportunities in Education of Science, Mathematics and Technology

We are raising a question if our education system in Finland is still providing equal opportunities for everybody in education of Science and Mathematics and Technology. We are using as indicators recent results of three international assessments: The Program for International Student Assessment, Trends in International Mathematics and Science Study and The learning curve in Science and Mathematics. There are a lot of research done internationally and nationally based on the results of these assessments and the background information connected to them. These assessments have also started rich discussions in news and in newspapers.
Basic Education Act 1998 in Finland gives every child a right to go to the close by neighborhood school, assigned by the local school authorities, and parents a freedom to choose some another school for their child. In addition, some local schools have a right to emphasize certain areas of education and to choose their students based on suitability tests. Connected to these issues, we are describing some research results concerning the status of schools and selection of schools in Helsinki area.

General information

Publication status: Published
MoE publication type: D3 Professional conference proceedings
Organisations: Department of Mathematics, Research group: MAT Clifford analysis
Contributors: Eriksson, S. A.
Number of pages: 14
Publication date: 2015

Host publication information

Title of host publication: The Proceedings of International Symposium Justice and Solidarity : The European Utopia in a Globalising Era, Kuopio 2.-3. September 2014
Editors: Laurinkari, J., Tarvanen, M.

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Equivalence of Set- and Bag-Valued Orbits

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Ruohonen, K.
Pages: 247-253
Publication date: 2009
Peer-reviewed: Yes

Publication information

Journal: Journal of Automata, Languages and Combinatorics
Volume: 14
Issue number: 3/4
ISSN (Print): 1430-189X
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 11263

Research output: Contribution to journalArticleScientificpeer-review

Estimating Above Ground Biomass from Terrestrial Laser Scanning in Autralian Eucalypt Open Forest

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Calders, K., Newnham, G., Herold, M., Murphy, S., Culvenor, D., Raumonen, P., Burt, A., Armston, J., Avitabile, V., Disney, M.
Number of pages: 7
Pages: 1-7
Publication date: 2013

Host publication information

Title of host publication: 13th International Conference on LiDAR Applications for Assessing Forest Ecosystems, SilviLaser 2013, 9.-11.10.2013. Beijing, China
Place of publication: Beijing, China
Publisher: Silvilaser Beijing 2013

Publication series

Name: International Conference on LiDAR Applications for Assessing Forest Ecosystems

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-12-29<br/>Publisher name: Silvilaser Beijing 2013

Source: researchoutputwizard
Source ID: 2023

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Estimation of above-ground biomass of large tropical trees with terrestrial LiDAR

1. Tropical forest biomass is a crucial component of global carbon emission estimations. However, calibration and validation of such estimates require accurate and effective methods to estimate in situ above-ground biomass (AGB). Present methods rely on allometric models that are highly uncertain for large tropical trees. Terrestrial laser scanning (TLS) tree modelling has demonstrated to be more accurate than these models to infer forest AGB. Nevertheless, applying TLS methods on tropical large trees is still challenging. We propose a method to estimate AGB of large tropical trees by three-dimensional (3D) tree modelling of TLS point clouds.

2. Twenty-nine plots were scanned with a TLS in three study sites (Peru, Indonesia and Guyana). We identified the largest tree per plot (mean diameter at breast height of 73.5 cm), extracted its point cloud and calculated its volume by 3D modelling its structure using quantitative structure models (QSM) and converted to AGB using species-specific wood density. We also estimated AGB using pantropical and local allometric models. To assess the accuracy of our and allometric methods, we harvest the trees and took destructive measurements.

3. AGB estimates by the TLS–QSM method showed the best agreement in comparison to destructive harvest measurements (28.37% coefficient of variation of root mean square error [CV-RMSE] and concordance correlation coefficient [CCC] of 0.95), outperforming the pantropical allometric models tested (35.6%–54.95% CV-RMSE and CCC of 0.89–0.73). TLS–QSM showed also the lowest bias (overall underestimation of 3.7%) and stability across tree size range, contrasting with the allometric models that showed a systematic bias (overall underestimation ranging 15.2%–35.7%) increasing linearly with tree size. The TLS–QSM method also provided accurate tree wood volume estimates (CV RMSE of 23.7%) with no systematic bias regardless the tree structural characteristics.

4. Our TLS–QSM method accounts for individual tree biophysical structure more effectively than allometric models, providing more accurate and less biased AGB estimates for large tropical trees, independently of their morphology. This non-destructive method can be further used for testing and calibrating new allometric models, reducing the current under-representation of large trees in and enhancing present and past estimates of forest biomass and carbon emissions from tropical forests.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Wageningen Univ, Wageningen University & Research Center, Swedish University of Agricultural Sciences, University College London
Contributors: Gonzalez de Tanago, J., Lau, A., Bartholomeus, H., Herold, M., Avitabile, V., Raumonen, P., Martius, C., Goodman, R., Disney, M., Manuri, S., Burt, A., Calders, K.
Number of pages: 12
Publication date: 13 Nov 2017
Peer-reviewed: Yes

Publication information

Journal: Methods in Ecology and Evolution
ISSN (Print): 2041-210X
Ratings: 
  • Scopus rating (2017): CiteScore 6.72 SJR 4.018 SNIP 2.456
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Estimation of base station position using timing advance measurements

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Ali-Löytty, S., Wirola, L.
Pages: 182-186
Publication date: 2010

Host publication information

Title of host publication: 2010 International Conference on Signal and Information Processing ICSIP 2010, Changsha, China, 15.12.2010
ISBN (Print): 978-1-4244-9103-2

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9067

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Estimation of initial state and model parameters for autonomous GNSS orbit prediction

In self-assisted GNSS the orbit of a satellite is predicted by solving the differential equation that models its motion. Our motion model includes the most important forces: Earth's gravity, lunar and solar gravity and solar radiation pressure. Unmodeled forces are taken into account by using Gaussian white noise term with covariance matrix estimated offline from historical orbital data. The estimation of model parameters (solar radiation pressure and Earth orientation parameters) and initial state for the prediction includes both offline and online stages. In the offline stage, priors for the solar radiation pressure parameters are estimated using precise orbits issued by the International GNSS service (IGS). In the online stage, the satellite’s broadcast ephemeris is used to estimate the initial state and model parameters. The estimation of the initial state is formulated as non-linear continuous-time filtering problem with discrete-time measurements. The filtering equations are solved numerically and the performance of different numerical methods (Extended, Cubature and Unscented Kalman filters) is compared. Using the estimated initial state and model parameters, the satellite orbits are predicted 5 days into the future. The accuracy and consistency of the predicted orbits is analysed by comparing with the IGS precise ephemerides. In this paper only GPS satellites are considered, but the method can be extended to other satellite systems.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Department of Mathematics, Research group: Positioning
Contributors: Ala-Luhtala, J., Seppänen, M., Ali-Löytty, S., Piche, R., Nurminen, H.
Number of pages: 15
Pages: 1-15
Publication date: 2013

Host publication information

Title of host publication: International Global Navigation Satellite Systems Society IGNSS Symposium 2013, 16-18 July, 2013, Gold Coast, Queensland, Australia
Place of publication: Tweed Heads, NSW, Australia
Publisher: IGNSS Society

Bibliographical note

Book of Abstracts: http://issuu.com/robhen7979/docs/2013bookofabstracts.doc<br/>Contribution: organisation=mat,FACT1=0.5<br/>Contribution: organisation=ase,FACT2=0.5<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: IGNSS Society

Source: researchoutputwizard
Source ID: 1897

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Estimation of Linear Systems with Abrupt Changes of the Noise Covariances Using Variational Bayes Algorithm

The variational Bayes method is applied to the state-space estimation problem with maneuvers or changes in the covariance of the observation noise. The resulting algorithm is an off-line batch method that can be used to provide a baseline performance estimation results for the recursive methods. In addition to batch methods we introduce a heuristic approach to make the algorithm on-line. Through simulations we show how the introduced method achieves the best accuracy out of all compared approximative estimation methods.

General information

Publication status: Published
MoE publication type: D4 Published development or research report or study
Organisations: Department of Mathematics, Research group: Positioning
Contributors: Pesonen, H., Piche, R.
Number of pages: 4
Publication date: 2012

Publication information

Place of publication: Tampere
Publisher: Tampere University of Technology, Department of Mathematics
ISBN (Electronic): 978-952-15-2923-8
Original language: English

Publication series

Name: Tampereen teknillinen yliopisto. Matematiikan laitos. Tutkimusraportti
Publisher: Tampereen teknillinen yliopisto
Volume: 100
ISSN (Print): 1459-3750

Bibliographical note

Julkaistu DPubissa vuonna 2012.Tallennettu Portfolioon 2013.<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-04-29

Source: researchoutputwizard
Source ID: 5057

Research output: Book/ReportCommissioned reportProfessional

Estimation of Model Parameters

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Research group: Positioning
Contributors: Piche, R.
Number of pages: 22
Pages: 169-190
Publication date: 2013

Host publication information

Title of host publication: Mathematical Modeling with Multidisciplinary Applications
Place of publication: Hoboken, NJ, USA
Publisher: John Wiley & Sons
Editor: Yang, X.
ISBN (Print): 978-1-1182-9441-3
ISBN (Electronic): 978-1-118-45862-4

Bibliographical note

Contribution: organisation=ase,FACT1=1<br/>Portfolio EDEND: 2013-05-29

Source: researchoutputwizard
Source ID: 3147

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Estimation of the Mechanical Power of a Kite Wind Generator

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Mathematics
Contributors: Rautakorpi, P., Argatov, I., Silvennoinen, R.
Number of pages: 28
Pages: 1-28
Publication date: 2013

Host publication information

Title of host publication: Renewable Energy for Sustainable Future
Place of publication: Hong Kong
Publisher: ICONCEPT PRESS
Editor: Lohani, S. P.
ISBN (Print): 978-1-922227-10-2

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-07-29

Source: researchoutputwizard
Source ID: 3248

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

E-type asteroid Steins as imaged by OSIRIS on board Rosetta

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Keller, H., Barbieri, C., Koschny, D., Lamy, P., Rickman, H., Rodrigo, R., Sierks, H., A'Hearn, M., Angrilli, F., Barucci, M., Bertaux, J., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P., Hviid, S., Ip, W., Jorda, L., Knollenberg, J., Kramm, J., Kuhrt, E., Kuppers, M., Lara, L., Lazzarin, M., Lopez Moreno, J., Marzari, F., Michalik, H., Naletto, G., Sabau, L., Thomas, N., Wenzel, K., Bertini, I., Besse, S., Ferri, F., Kaasalainen, M., Lowry, S., Marchi, S., Mottola, S., Sabolo, W., Schröder, S., Spjuth, S., Vernazza, P.
Pages: 190-193
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Science
Volume: 327
Issue number: 5962
ISSN (Print): 0036-8075
Ratings: 
  • Scopus rating (2010): SJR 13.481 SNIP 7.754
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8329

Research output: Contribution to journalArticleScientificpeer-review

Evaluating the Consistency of Estimation

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Ivanov, P., Ali-Löytty, S., Piche, R.
Number of pages: 5
Publication date: 2014

Host publication information

Title of host publication: Proceedings of 2014 International Conference on Localization and GNSS (ICL-GNSS), Helsinki, Finland, June 24-26, 2014
Place of publication: Piscataway
Publisher: IEEE
ISBN (Print): 978-1-4799-5122-2

Bibliographical note

Contribution: organisation=ase,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5<br/>Portfolio EDEND: 2014-11-25

Source: researchoutputwizard
Source ID: 551

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Experienced risks in social media use – longitudinal study among university students

Several recent studies indicate that there is a need for increased use of ICT and social media in the Finnish education [1], [2]. This research was conducted in order to explore the attitude towards social media use among university students. The motivation for seeking answer to the research question: “What risks students experience in social media use?” derived from the need to discover learning barriers in social media based learning environments. In particular, there is a need for novel interaction means in order to co-create and learn informally [3] also beyond the traditional classroom. The assumptions, beliefs and attitudes towards social media are studied from the perspective of perceived risks of the students. The study was conducted among graduate students attending “Communities and Social Media in Knowledge Management” course between the years 2012-2016. A web-based survey was executed annually, with a total of 113 respondents. Based on the results we were able to categorize the perceived risks and derive implications on how to lower learning barriers of students in social media based learning environments.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Information Management and Logistics, Research group: Novi, Pori Department, Research group: Business Ecosystems, Networks and Innovations, Managing digital industrial transformation (mDIT)
Contributors: Jussila, J., Aramo-Immonen, H.
Number of pages: 6
Pages: 1255-1260
Publication date: 4 Jul 2016

Host publication information

Title of host publication: EDULEARN16 Proceedings : 8th annual International Conference on Education and New Learning Technologies, Barcelona (Spain). 4th - 6th of July, 2016.
Volume: 8
Publisher: IATED Academy
Editors: Gómez Chova, L., López Martínez, A., Candel Torres, I.
ISBN (Electronic): 978-84-608-8860-4

Publication series

Name: EDULEARN Proceedings
Publisher: IATED Academy
ISSN (Electronic): 2340-1117
Keywords: social media, social media risks, e-communication, knowledge management

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Explaining innovation with indicators of mobility and networks: Insights into central innovation nodes in Europe

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Still, K., Russell, M. G., Huhtamäki, J., Turpeinen, M., Rubens, N.
Number of pages: 17
Pages: 1-17
Publication date: 2011

Host publication information

Title of host publication: Proceedings of the Triple Helix IX International Conference: Silicon Valley: Global Model or Unique Anomaly? 11-14 July, 2011, Stanford, California, USA
Place of publication: Stanford, CA
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Publication series

Name: Triple Helix International Conference
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Bibliographical note

ei ut-numeroa 17.5.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 7311

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Facilitating active participation in web-based co-development

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Friedrich, P., Huhtamäki, J., Koskela-Huotari, K., Karppinen, K., Still, K.
Pages: 16-23
Publication date: 2012

Host publication information

Title of host publication: Proceedings of Innovation through Social Media, ISM 2012 workshop proceedings, December 3, 2012, Oslo, Norway
Place of publication: Trondheim, Norway
Publisher: AKADEMIKA FORLAG
ISBN (Print): 978-82-321-0088-0

Publication series

Name: Innovation Through Social Media

Bibliographical note

ei ut-numeroa 12.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Akademika forlag

Source: researchoutputwizard
Source ID: 4069

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Fair testing and stubborn sets

Partial order methods alleviate state explosion by considering only a subset of actions in each constructed state. The choice of the subset depends on the properties that the method promises to preserve. Many methods have been developed ranging from deadlock-preserving to CTL(Formula presented.)-preserving and divergence-sensitive branching bisimilarity preserving. The less the method preserves, the smaller state spaces it constructs. Fair testing equivalence unifies deadlocks with livelocks that cannot be exited and ignores the other livelocks. It is the weakest congruence that preserves whether or not the system may enter a livelock that it cannot leave. We prove that a method that was designed for trace equivalence also preserves fair testing equivalence. We demonstrate its effectiveness on a protocol with a connection and data transfer phase. This is the first practical partial order method that deals with a practical fairness assumption.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Augsburg
Contributors: Valmari, A., Vogler, W.
Number of pages: 22
Pages: 589-610
Publication date: 2018
Peer-reviewed: Yes
Early online date: 11 Dec 2017

Publication information

Journal: International Journal on Software Tools for Technology Transfer
ISSN (Print): 1433-2779
Ratings: 
  • Scopus rating (2018): CiteScore 2.39 SJR 0.472 SNIP 1.648
Original language: English
ASJC Scopus subject areas: Software, Information Systems
Keywords: Fair testing equivalence, Fairness, Partial order methods, Progress, Stubborn sets
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85037686390

Research output: Contribution to journalArticleScientificpeer-review

Far-Field Inversion for the Deep Interior Scanning CubeSat

This study aims at advancing mathematical and computational techniques for reconstructing the interior structure of a small Solar System body via Computed Radar Tomography (CRT). We introduce a far-field model for full-wave CRT and validate it numerically for an orbiting distance of 5 km using a synthetic 3D target asteroid and sparse limited-angle data. As a potential future application of the proposed method, we consider the Deep Interior Scanning CUbeSat (DISCUS) concept in which the goal is to localize macroporosities inside a rubble pile near-Earth asteroid with two small spacecraft carrying a bistatic radar.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Max Planck Institute for Solar System Research, MEW-Aerospace, RST Radar Systemtechnik AG
Contributors: Takala, M., Bambach, P., Deller, J., Vilenius, E., Wittig, M., Lentz, H., Braun, H. M., Kaasalainen, M., Pursiainen, S.
Number of pages: 27
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Aerospace and Electronic Systems
ISSN (Print): 0018-9251
Ratings: 
  • Scopus rating (2018): CiteScore 3.5 SJR 0.798 SNIP 1.749
Original language: English
ASJC Scopus subject areas: Aerospace Engineering, Electrical and Electronic Engineering
Keywords: Cathode ray tubes, Computed Radar Tomography, Extraterrestrial measurements, Far-Field Measurements, Frequency measurement, Inverse Imaging, Near-Earth Asteroids, Radar, Small Solar System Bodies, Space vehicles
Source: Scopus
Source ID: 85054614162

Research output: Contribution to journalArticleScientificpeer-review

Fast Automatic Method for Constructing Topologically and Geometrically Precise Tree Models from TLS Data

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Raumonen, P., Casella, E., Disney, M., Åkerblom, M., Kaasalainen, M.
Number of pages: 3
Pages: 89-91
Publication date: 2013

Host publication information

Title of host publication: 7th International Conference on Functional-Structural Plant Models, FSPM2013, 9.-14.6.2013, Saariselkä, Finland
Place of publication: Vantaa
Publisher: Finnish Society of Forest Science; Finnish Forest Research Institute; University of Helsinki
Editors: Sievänen, R., Nikinmaa, E., Godin, C., Lintunen, A., Nygren, P.
ISBN (Print): 978-951-651-408-9

Publication series

Name: International Conference on Functional-Structural Plant Models

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: Finnish Society of Forest Science; Finnish Forest Research Institute; University of Helsinki

Source: researchoutputwizard
Source ID: 3243

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Fast automatic precision tree models from terrestrial laser scanner data

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Inverse Problems, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Raumonen, P., Kaasalainen, M., Åkerblom, M., Kaasalainen, S., Kaartinen, H., Vastaranta, M., Holopainen, M., Disney, M., Lewis, P.
Number of pages: 30
Pages: 491-520
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing
Volume: 5
Issue number: 2
ISSN (Print): 2072-4292
Ratings: 
  • Scopus rating (2013): CiteScore 3.01 SJR 1.127 SNIP 1.944
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: MDPI

Source: researchoutputwizard
Source ID: 3244

Research output: Contribution to journalArticleScientificpeer-review

Fast fourier color constancy and grayness index for ISPA illumination estimation challenge

We briefly introduce two submissions to the Illumination Estimation Challenge, in the Int'l Workshop on Color Vision, affiliated to the 11th Int'l Symposium on Image and Signal Processing and Analysis. The fourier-transform-based submission is ranked 3rd, and the statistical Gray-pixel-based one ranked 6th.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, South China University of Technology
Contributors: Qian, Y., Chen, K., Yu, H.
Number of pages: 3
Pages: 352-354
Publication date: 17 Oct 2019

Host publication information

Title of host publication: ISPA 2019 - 11th International Symposium on Image and Signal Processing and Analysis
Publisher: IEEE
Editors: Loncaric, S., Bregovic, R., Carli, M., Subasic, M.
ISBN (Electronic): 9781728131405

Publication series

Name: International Symposium on Image and Signal Processing and Analysis, ISPA
Volume: 2019-September
ISSN (Print): 1845-5921
ISSN (Electronic): 1849-2266
ASJC Scopus subject areas: Computational Theory and Mathematics, Computer Graphics and Computer-Aided Design, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Color constancy, FFCC, Gray pixel, Illumination

Bibliographical note

EXT="Chen, Ke"

Source: Scopus
Source ID: 85074428933

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Feedforward Output Regulation for Distributed Parameter Systems with Infinite-Dimensional Exosystems

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Paunonen, L., Pohjolainen, S.
Pages: 1566-1571
Publication date: 2012

Host publication information

Title of host publication: Proceedings of the 51st IEEE Conference on Decision and Control, IEEE CDC 2012, December 10-13 2012, Maui, Hawaii, USA
Place of publication: Piscataway, NJ
Publisher: IEEE
ISBN (Print): 978-1-4673-2065-8
ISBN (Electronic): 978-1-4673-2064-1

Publication series

Name: IEEE Conference on Decision and Control
ISSN (Print): 0743-1546

Bibliographical note

ei ut-numeroa 27.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: IEEE

Source: researchoutputwizard
Source ID: 5027

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

FiB: Squeezing loop invariants by interpolation between forward/backward predicate transformers

Loop invariant generation is a fundamental problem in program analysis and verification. In this work, we propose a new approach to automatically constructing inductive loop invariants. The key idea is to aggressively squeeze an inductive invariant based on Craig interpolants between forward and backward reachability analysis. We have evaluated our approach by a set of loop benchmarks, and experimental results show that our approach is promising.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Mathematics, Research group: Computer Science and Applied Logics
Contributors: Lin, S., Sun, J., Xiao, H., Liu, Y., Sanán, D., Hansen, H.
Number of pages: 11
Pages: 793-803
Publication date: Oct 2017

Host publication information

Title of host publication: Proceedings of the 32nd IEEE/ACM International Conference on Automated Software Engineering : ASE 2017
Publisher: IEEE Press
Editors: Rosu, G., Di Penta, M., Nguyen, T. N.
ISBN (Electronic): 978-1-5386-2684-9

Publication series

Name: IEEE/ACM International Conference on Automated Software Engineering
Publisher: IEEE
ISSN (Print): 1938-4300

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Finite-dimensional regulators for a class of regular hyperbolic PDE systems

In this paper, the output regulation problem is addressed for a class of linear hyperbolic infinite-dimensional systems with spatially varying coefficients modelling a large class of convection-dominated transport reaction systems. In particular, distributed parameter systems with bounded input and unbounded output operators are considered. First, we demonstrate a general conclusion about the exponential stability of the considered system by relating the stability to the solution of an associated differential equation. Based on the assumption that the hyperbolic system satisfies the exponential stability conditions, the main manuscript contribution is the development of two novel finite-dimensional regulators, output and error feedback regulators, such that the controlled output of the plant tracks a reference signal generated by a known signal process (exosystem). In order to guarantee the feasibility of the proposed regulators, the solvability of the corresponding Sylvester equations is discussed and the solvability conditions are provided. Finally, simulations of output regulation of an axial dispersion reactor and a relevant numerical example illustrate the main results and performance of the proposed regulators synthesis.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics, Univ Alberta, University of Alberta
Contributors: Xu, X., Pohjolainen, S., Dubljevic, S.
Number of pages: 18
Pages: 1-18
Publication date: 30 Aug 2017
Peer-reviewed: Yes

Publication information

Journal: International Journal of Control
ISSN (Print): 0020-7179
Ratings: 
  • Scopus rating (2017): CiteScore 2.51 SJR 1.152 SNIP 1.267
Original language: English
Keywords: Hyperbolic PDE systems, finite-dimensional regulators, output feedback regulator, Sylvester equation

Research output: Contribution to journalArticleScientificpeer-review

Finite element analysis of trees in the wind based on terrestrial laser scanning data

Wind damage is an important driver of forest structure and dynamics, but it is poorly understood in natural broadleaf forests. This paper presents a new approach in the study of wind damage: combining terrestrial laser scanning (TLS) data and finite element analysis. Recent advances in tree reconstruction from TLS data allowed us to accurately represent the 3D geometry of a tree in a mechanical simulation, without the need for arduous manual mapping or simplifying assumptions about tree shape. We used this simulation to predict the mechanical strains produced on the trunks of 21 trees in Wytham Woods, UK, and validated it using strain data measured on these same trees. For a subset of five trees near the anemometer, the model predicted a five-minute time-series of strain with a mean cross-correlation coefficient of 0.71, when forced by the locally measured wind speed data. Additionally, the maximum strain associated with a 5 ms−1 or 15 ms-1 wind speed was well predicted by the model (N = 17, R2 = 0.81 and R2 = 0.79, respectively). We also predicted the critical wind speed at which the trees will break from both the field data and models and find a good overall agreement (N = 17, R2 = 0.40). Finally, the model predicted the correct trend in the fundamental frequencies of the trees (N = 20, R2 = 0.38) although there was a systematic underprediction, possibly due to the simplified treatment of material properties in the model. The current approach relies on local wind data, so must be combined with wind flow modelling to be applicable at the landscape-scale or over complex terrain. This approach is applicable at the plot level and could also be applied to open-grown trees, such as in cities or parks.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, University of Oxford, Facility for Airborne Atmospheric Measurements, Universiteit Gent, National Physical Laboratory, University College London, NERC National Centre for Earth Observation (NCEO), EFI Planted Forest Facility, Wageningen University and Research Centre, INRA
Contributors: Jackson, T., Shenkin, A., Wellpott, A., Calders, K., Origo, N., Disney, M., Burt, A., Raumonen, P., Gardiner, B., Herold, M., Fourcaud, T., Malhi, Y.
Number of pages: 8
Pages: 137-144
Publication date: 15 Feb 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Agricultural and Forest Meteorology
Volume: 265
ISSN (Print): 0168-1923
Original language: English
ASJC Scopus subject areas: Forestry, Global and Planetary Change, Agronomy and Crop Science, Atmospheric Science
Keywords: Critical wind speed, Finite element analysis, Resonant frequency, Terrestrial laser scanning, TLS, Wind damage
Electronic versions: 
Source: Scopus
Source ID: 85056823859

Research output: Contribution to journalArticleScientificpeer-review

Flexible Identification Procedure for Thermodynamic Constitutive Models for Magnetostrictive Materials

We present a novel approach for identifying a multiaxial thermodynamic magneto-mechanical constitutive law by direct bi- or trivariate spline interpolation from available magnetization and magnetostriction data. Reference data are first produced with a multiscale model in the case of a magnetic field and uniaxial and shear stresses. The thermodynamic model fits well to the results of the multiscale model, after which the models are compared under complex multiaxial loadings. A surprisingly good agreement between the two models is found, but some differences in the magnetostrictive behaviour are also pointed out. Finally, the model is fitted to measurement results from an electrical steel sheet. The spline-based constitutive law overcomes several drawbacks of analytical approaches used earlier. The presented models and measurement results are openly available.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Research area: Power engineering, Research group: Electromechanics, Civil Engineering, Research group: Structural Mechanics, Aalto University, Group of Electrical Engineering - Paris, CNRS, CNRS Centre National de la Recherche Scientifique
Contributors: Rasilo, P., Singh, D., Jeronen, J., Aydin, U., Martin, F., Belahcen, A., Daniel, L., Kouhia, R.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences
Article number: 20180280
ISSN (Print): 1364-5021
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Forecasting the diffusion of innovation: A stochastic bass model with log-normal and mean-reverting error process

Forecasting the diffusion of innovations plays a major role in managing technology development and in engineering management overall. In this paper, we extend the conventional Bass model stochastically by specifying the error process of sales as log-normal and mean-reverting. Our model satisfies the following reasonable properties, which are generally ignored in the existing literature: sales cannot be negative, the error process can have a memory, and sales fluctuate more when they are high and less when they are low. The conventional and widely used model that assumes normally distributed error term does not have these properties. We address how to forecast properly under the log-normal and mean-reverting error process, and show analytically and numerically that in our extended model sales forecasts can substantially alter conventional Bass forecasts. We also analyze the model empirically, showing that our extension can improve the accuracy of future sales forecasts.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Industrial Management, Department of Mathematics, Research group: Positioning, Research Community on Data-to-Decision (D2D), Managing digital industrial transformation (mDIT), Wireless Communications and Positioning (WICO)
Contributors: Kanniainen, J., Mäkinen, S., Piche, R., Chakrabarti, A.
Number of pages: 22
Pages: 1-22
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Engineering Management
Volume: 99
ISSN (Print): 0018-9391
Ratings: 
  • Scopus rating (2011): CiteScore 1.97 SJR 0.848 SNIP 1.361
Original language: English

Bibliographical note

Contribution: organisation=tta,FACT1=0.75<br/>Contribution: organisation=mat,FACT2=0.25

Source: researchoutputwizard
Source ID: 6284

Research output: Contribution to journalArticleScientificpeer-review

Formula size games for modal logic and mu-calculus

We propose a new version of formula size game for modal logic. The game characterizes the equivalence of pointed Kripke models up to formulas of given numbers of modal operators and binary connectives. Our game is similar to the well-known Adler–Immerman game. However, due to a crucial difference in the definition of positions of the game, its winning condition is simpler, and the second player does not have a trivial optimal strategy. Thus, unlike the Adler–Immerman game, our game is a genuine two-person game. We illustrate the use of the game by proving a non-elementary succinctness gap between bisimulation invariant first-order logic FO and (basic) modal logic ML⁠. We also present a version of the game for the modal μ-calculus Lμ and show that FO is also non-elementarily more succinct than Lμ⁠.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, University of Tampere
Contributors: Hella, L. T., Vilander, M. S.
Publication date: 13 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF LOGIC AND COMPUTATION
Article number: exz025
ISSN (Print): 0955-792X
Original language: English
ASJC Scopus subject areas: Logic, Computational Theory and Mathematics
Keywords: succinctness, formula size game, modal logic, modal mu-calculus, bisimulation invariant first-order logic

Bibliographical note

INT=comp."Hella, Lauri"

Research output: Contribution to journalArticleScientificpeer-review

Forward and Inverse Effects of the Complete Electrode Model in Neonatal EEG

This paper investigates finite element method (FEM) based modeling in the context of neonatal electroencephalography (EEG). In particular, the focus lies on electrode boundary conditions. We compare the complete electrode model (CEM) to the point electrode model (PEM), which is the current standard in EEG. In the CEM, the voltage experienced by an electrode is modeled more realistically as the integral average of the potential distribution over its contact surface, whereas the PEM relies on a point value. Consequently, the CEM takes into account the sub-electrode shunting currents which are absent in the PEM. In this study, we aim to find out how the electrode voltage predicted by these two models differ, if standard size electrodes are attached to a head of a neonate. Additionally, we study voltages and voltage variation on electrode surfaces with two source locations: (A) next to the 5-th electrode and (B) directly under the frontal fontanel. A realistic model of a neonatal head including a skull with fontanels and sutures is used. Based on the results, the forward simulation differences between CEM and PEM are in general small, but significant outliers can occur in the vicinity of the electrodes. The CEM can be considered as an integral part of the outer head model. The outcome of this study helps understanding volume conduction of neonatal EEG as it enlightens the role of advanced skull and electrode modeling in forward and inverse computations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Pursiainen, S., Lew, S., Wolters, C. H.
Pages: 876-884
Publication date: Mar 2017
Peer-reviewed: Yes
Early online date: 16 Nov 2016

Publication information

Journal: Journal of Neurophysiology
Volume: 117
Issue number: 3
ISSN (Print): 0022-3077
Ratings: 
  • Scopus rating (2017): CiteScore 2.51 SJR 1.65 SNIP 0.897
Original language: English

Bibliographical note

Copyright © 2016, Journal of Neurophysiology.

Source: PubMed
Source ID: 27852731

Research output: Contribution to journalArticleScientificpeer-review

Fractional Ornstein-Uhlenbeck Processes

In this monograph, we are mainly studying Gaussian processes, in particularly three different types of fractional Ornstein – Uhlenbeck processes. Pioneers in this field may bementioned, e.g. Kolmogorov (1903-1987) and Mandelbrot (1924-2010).The Ornstein – Uhlenbeck diffusion can be constructed from Brownian motion via a Doobtransformation and also from a solution of the Langevin stochastic differential equation. Both of these processes have the same finite dimensional distributions. However the solution of the Langevin stochastic differential equation, which driving process is fractionalBrownian motion and a Doob transformation of fractional Brownian motion do not havesame finite dimensional distributions. Indeed we verify, that the covariance of the fractionalOrnstein – Uhlenbeck process of the first kind (which we call the solution of the Langevin stochastic differential equation in which the driving process is fractional Brownian motion) behaves at infinity like a power function and the covariance of the fractional Ornstein –Uhlenbeck process (constructed by a Doob transformation of fractional Brownian motion) behaves at infinity like an exponential function. Moreover we study the behaviour of the covariances of these fractional Ornstein – Uhlenbeck processes. We also calculate the spectral density function for the Doob transformation of fractional Brownian motion using a Bochner theorem.We present the Doob transformation of fractional Brownian motion via solution of the Langevin stochastic differential equation. One of the main aims of our research is to analyse its driving process. This driving process is Y^((α))=e^(-tα) x_(τ_t ), where τ_t=(He^(αt/H))/α and {Z_t:t≥0 } is fractional Brownian motion. We find out that the process Y^((α)) := {Y_t^((α)): t ≥0}, if scaled properly, has the same finite dimensional distributions as the process Y^((1)) := {Y_t^((1)): t ≥0}. The main result in this monograph is that we define a stationary fractional Ornstein – Uhlenbeck process of the second kind as a process with a two-sided driving process {Y ̂_t^((1)): t∈R} and create a new family of fractional Ornstein-Uhlenbeck processes. We study many properties of the fractional Ornstein – Uhlenbeck process of the second kind. For example, we show that the fractional Ornstein – Uhlenbeck process of the second kind is Hölder continuous of any order β < H and find the kernel representation of its covariance.We research many properties of the processes Y^((α)) and Y^((1)) since they are quite interesting themselves. We represent these processes as stochastic integrals with respect to Brownian motion and prove that the sample paths of the process Y^((α)) are Hölder continuous of any order β < H. In the case H ∈(1/2,1), we find out the covariance kernel of increment process of Y^((α)), and using that we investicate the covariance of Y^((α)) and the variance of Y^((α)), when t tends to infinity. One of our main results is that the increment process of Y^((α)) is short-range dependent. We also study weak convergence and tightness and then finally prove that 1/√α Y_αt^((α)) converges weakly to scaled Brownian motion.In the case H ∈(1/2,1), fractional Brownian motion and the fractional Ornstein – Uhlenbeck process of the first kind both exhibit a long-range dependence, but the fractional Ornstein– Uhlenbeck process of the second kind exhibits a short-range dependence. This offers more opportunities to model network traffic or economic time series via tractable fractional processes. The fractional Ornstein – Uhlenbeck process of the first kind and the fractional Ornstein – Uhlenbeck process of the second kind are quite similar to simulate, since they can both be represented via stochastic differential equations.

General information

Publication status: Published
MoE publication type: G4 Doctoral dissertation (monograph)
Organisations: Department of Mathematics
Contributors: Kaarakka, T.
Number of pages: 102
Publication date: 6 Nov 2015

Publication information

Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-3604-5
ISBN (Electronic): 978-952-15-3620-5
Original language: English

Publication series

Name: Tampere University of Technology. Publication
Publisher: Tampere University of Technology
Volume: 1338
ISSN (Print): 1459-2045

Bibliographical note

Awarding institution:Tampere University of Technology
Versio ok 14.12.2015

Research output: Book/ReportDoctoral thesisMonograph

Frequency domain robust regulation of signals generated by an infinite-dimensional exosystem

This paper deals with frequency domain robust regulation of signals generated by an infinite-dimensional exosystem. The problem is formulated and the stability types are chosen so that one can generalize the existing finite-dimensional theory to more general classes of infinite-dimensional systems and signals. The main results of this article are extensions of the internal model principle, of a necessary and sufficient solvability condition for the robust regulation problem, and of Davison's simple servo compensator for stable plants in the chosen algebraic framework.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Laakkonen, P., Pohjolainen, S.
Number of pages: 28
Pages: 139-166
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: SIAM Journal on Control and Optimization
Volume: 53
Issue number: 1
ISSN (Print): 0363-0129
Ratings: 
  • Scopus rating (2015): CiteScore 1.92 SJR 2.017 SNIP 1.646
Original language: English
ASJC Scopus subject areas: Control and Optimization, Applied Mathematics
Keywords: Frequency domain, Infinite-dimensional exosystems, Infinite-dimensional systems, Internal model, Robust regulation
Source: Scopus
Source ID: 84923923144

Research output: Contribution to journalArticleScientificpeer-review

Function classes and relational constraints stable under compositions with clones

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Couceiro, M., Foldes, S.
Number of pages: 13
Pages: 109-121
Publication date: 2009
Peer-reviewed: Yes

Publication information

Journal: Discussiones Mathematicae - General Algebra and Applications
Volume: 29
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9861

Research output: Contribution to journalArticleScientificpeer-review

Fundamental solution of k-hyperbolic harmonic functions in odd spaces

We study k-hyperbolic harmonic functions in the upper half space . The operator is the Laplace-Beltrami operator with respect to the Riemannian metric . In case k = n - 1 the Riemannian metric is the hyperbolic distance of Poincare upper half space. The proposed functions are connected to the axially symmetric potentials studied notably by Weinstein, Huber and Leutwiler. We present the fundamental solution in case n is even using the hyperbolic metric. The main tool is the transformation of k-hyperbolic harmonic functions to eigenfunctions of the hyperbolic Laplace operator.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Clifford analysis
Contributors: Eriksson, S., Orelma, H.
Publication date: 13 Apr 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Physics: Conference Series
Volume: 597
Issue number: 1
Article number: 012034
ISSN (Print): 1742-6588
Ratings: 
  • Scopus rating (2015): CiteScore 0.35 SJR 0.252 SNIP 0.374
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all)
Source: Scopus
Source ID: 84928019119

Research output: Contribution to journalArticleScientificpeer-review

Further hardness results on rainbow and strong rainbow connectivity

A path in an edge-colored graph is rainbow if no two edges of it are colored the same. The graph is said to be rainbow connected if there is a rainbow path between every pair of vertices. If there is a rainbow shortest path between every pair of vertices, the graph is strong rainbow connected. We consider the complexity of the problem of deciding if a given edge-colored graph is rainbow or strong rainbow connected. These problems are called Rainbow connectivity and Strong rainbow connectivity, respectively. We prove both problems remain NP-complete on interval outerplanar graphs and k-regular graphs for k≥3. Previously, no graph class was known where the complexity of the two problems would differ. We show that for block graphs, which form a subclass of chordal graphs, Rainbow connectivity is NP-complete while Strong rainbow connectivity is in P. We conclude by considering some tractable special cases, and show for instance that both problems are in XP when parameterized by tree-depth.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Lauri, J.
Pages: 191-200
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Discrete Applied Mathematics
Volume: 201
ISSN (Print): 0166-218X
Ratings: 
  • Scopus rating (2016): CiteScore 1 SJR 0.863 SNIP 1.23
Original language: English
ASJC Scopus subject areas: Applied Mathematics, Discrete Mathematics and Combinatorics
Keywords: Computational complexity, Rainbow connectivity
Source: Scopus
Source ID: 84956591316

Research output: Contribution to journalArticleScientificpeer-review

Fuzzy Logic of Quasi-Truth: An Algebraic Treatment

General information

Publication status: Published
MoE publication type: C1 Separate scientific books
Organisations: Department of Mathematics, Research group: MAT Computer Science and Applied Logics
Contributors: Di Nola, A., Grigolia, R., Turunen, E.
Number of pages: 116
Publication date: 2016

Publication information

Place of publication: Switzerland
Publisher: Springer
ISBN (Print): 978-3-319-30404-5
ISBN (Electronic): 978-3-319-30406-9
Original language: English

Publication series

Name: Studies in Fuzziness and Soft Computing
Publisher: Springer
Volume: 338
ISSN (Print): 1434-9922
ISSN (Electronic): 1860-0808
ASJC Scopus subject areas: Mathematics(all)
Keywords: MV-algebra

Research output: Book/ReportBookScientificpeer-review

Gaussian filtering and variational approximations for Bayesian smoothing in continuous-discrete stochastic dynamic systems

The Bayesian smoothing equations are generally intractable for systems described by nonlinear stochastic differential equations and discrete-time measurements. Gaussian approximations are a computationally efficient way to approximate the true smoothing distribution. In this work, we present a comparison between two Gaussian approximation methods. The Gaussian filtering based Gaussian smoother uses a Gaussian approximation for the filtering distribution to form an approximation for the smoothing distribution. The variational Gaussian smoother is based on minimizing the Kullback-Leibler divergence of the approximate smoothing distribution with respect to the true distribution. The results suggest that for highly nonlinear systems, the variational Gaussian smoother can be used to iteratively improve the Gaussian filtering based smoothing solution. We also present linearization and sigma-point methods to approximate the intractable Gaussian expectations in the variational Gaussian smoothing equations. In addition, we extend the variational Gaussian smoother for certain class of systems with singular diffusion matrix.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO), Aalto University
Contributors: Ala-Luhtala, J., Särkkä, S., Piche, R.
Number of pages: 13
Pages: 124-136
Publication date: Jun 2015
Peer-reviewed: Yes

Publication information

Journal: Signal Processing
Volume: 111
ISSN (Print): 0165-1684
Ratings: 
  • Scopus rating (2015): CiteScore 3 SJR 0.898 SNIP 1.936
Original language: English

Bibliographical note

Available online 19 Dec,2014, preprint http://arxiv.org/abs/1407.5874 (vol 111, June2015, s. 124-136)<br/>Contribution: organisation=ase,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5<br/>Portfolio EDEND: 2015-01-09<br/>Publisher name: Elsevier <br /> publication_forum:67104

Source: researchoutputwizard
Source ID: 80

Research output: Contribution to journalArticleScientificpeer-review

Gaussian mixture filter allowing negative weights and its application to positioning using signal strength measurements

This paper proposes a novel Gaussian Mixture Filter (GMF) that allows components with negative weights. In case of a ring-shaped likelihood function, the new filter keeps the number of components low by approximating the likelihood as a Gaussian mixture (GM) of two components, one with positive and the other with negative weight. In this article, the filter is applied to positioning with received signal strength (RSS) based range measurements. The filter is tested using simulated measurements, and the tests indicate that the new GMF outperforms the Extended Kalman Filter (EKF) in both accuracy and consistency.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: MAT Positioning, Department of Mathematics, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Muller, P., Ali-Löytty, S., Dashti, M., Nurminen, H., Piche, R.
Pages: 71-76
Publication date: 2012

Host publication information

Title of host publication: Proceedings of WPNC 2012, 9th Workshop on Positioning, Navigation and Communication, March 15-16, 2012, Dresden, Germany
Place of publication: Piscataway, NJ
Publisher: Institute of Electrical and Electronics Engineers IEEE
ISBN (Print): 978-1-4673-1437-4

Publication series

Name: Workshop on Positioning, Navigation and Communication

Bibliographical note

ei ut-numeroa 22.8.2013<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Institute of Electrical and Electronics Engineers IEEE

Source: researchoutputwizard
Source ID: 4882

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Gaussian mixture filter in hybrid navigation

General information

Publication status: Published
MoE publication type: B3 Non-refereed article in conference proceedings
Organisations: Research group: MAT Positioning, Matematiikka, Research group: Positioning
Contributors: Ali-Löytty, S.
Number of pages: 5
Pages: 1-5
Publication date: 2007

Host publication information

Title of host publication: Digest of TISE Seminar 2007, Nokia, Finland, 5 June 2007
Editor: Koivisto, P.

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 13909

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientific

Gaussian Process Regression for Forest Attribute Estimation From Airborne Laser Scanning Data

While the analysis of airborne laser scanning (ALS) data often provides reliable estimates for certain forest stand attributes-such as total volume or basal area-there is still room for improvement, especially in estimating species-specific attributes. Moreover, while the information on the estimate uncertainty would be useful in various economic and environmental analyses on forests, a computationally feasible framework for uncertainty quantifying in ALS is still missing. In this paper, the species-specific stand attribute estimation and uncertainty quantification (UQ) is approached using Gaussian process regression (GPR), which is a nonlinear and nonparametric machine learning method. Multiple species-specific stand attributes are estimated simultaneously: tree height, stem diameter, stem number, basal area, and stem volume. The cross-validation results show that GPR yields on average an improvement of 4.6&#x0025; in estimate root mean square error over a state-of-the-art k-nearest neighbors (kNNs) implementation, negligible bias and well performing UQ (credible intervals), while being computationally fast. The performance advantage over kNN and the feasibility of credible intervals persists even when smaller training sets are used.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Eastern Finland
Contributors: Varvia, P., Lähivaara, T., Maltamo, M., Packalen, P., Seppänen, A.
Pages: 3361-3369
Publication date: Jun 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: IEEE Transactions on Geoscience and Remote Sensing
Volume: 57
Issue number: 6
ISSN (Print): 0196-2892
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Earth and Planetary Sciences(all)
Keywords: Area-based approach (ABA), forest inventory, Gaussian process (GP), light detection and ranging (LiDAR), machine learning.
Source: Scopus
Source ID: 85058898004

Research output: Contribution to journalArticleScientificpeer-review

Gaussian Scale Mixture Models For Robust Linear Multivariate Regression With Missing Data

We present an algorithm for multivariate robust Bayesian linear regression with missing data. The iterative algorithm computes an approximative posterior for the model parameters based on the variational Bayes (VB) method. Compared to the EM algorithm, the VB method has the advantage that the variance for the model parameters is also computed directly by the algorithm. We consider three families of Gaussian scale mixture models for the measurements, which include as special cases the multivariate t distribution, the multivariate Laplace distribution, and the contaminated normal model. The observations can contain missing values, assuming that the missing data mechanism can be ignored. A Matlab/Octave implementation of the algorithm is presented and applied to solve three
reference examples from the literature.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: MAT Positioning, Department of Automation Science and Engineering, Department of Mathematics, Research group: Positioning
Contributors: Ala-Luhtala, J., Piche, R.
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Communications in Statistics: Simulation and Computation
ISSN (Print): 0361-0918
Ratings: 
  • Scopus rating (2014): CiteScore 0.54 SJR 0.466 SNIP 0.765
Original language: English

Bibliographical note

Online first.Accepted author version posted online 19 Jun 2014<br/>Contribution: organisation=mat,FACT1=0.25<br/>Contribution: organisation=ase,FACT2=0.75<br/>Portfolio EDEND: 2014-11-25<br/>Publisher name: Taylor & Francis

Source: researchoutputwizard
Source ID: 79

Research output: Contribution to journalArticleScientificpeer-review

Gender and Innovation: Networks of Executive Women in Technology-Based Companies

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics
Contributors: Still, K., Russell, M. G., Huhtamäki, J., Yu, J. (., Rubens, N.
Number of pages: 20
Pages: 1-20
Publication date: 2011

Host publication information

Title of host publication: Proceedings of the Triple Helix IX International Conference: Silicon Valley: Global Model or Unique Anomaly? 11-14 July, 2011, Stanford, California, USA
Place of publication: Stanford, CA
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Publication series

Name: Triple Helix International Conference
Publisher: Stanford University, H-STAR Institute Center for Innovation and Communication

Bibliographical note

ei ut-numeroa 17.5.2014<br/>Contribution: organisation=mat hyplab,FACT1=1

Source: researchoutputwizard
Source ID: 7312

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

General Integral Formulas for k-hyper-mono-genic Functions

We are studying a function theory of k-hypermonogenic functions connected to k-hyperbolic harmonic functions that are harmonic with respect to the hyperbolic Riemannian metric k2=xn2k1-n(dx02+⋯+dxn2)in the upper half space R+n+1={(x0,…,xn)|xi∈R,xn>0}. The function theory based on this metric is important, since in case k= n- 1 , the metric is the hyperbolic metric of the Poincaré upper half space and Leutwiler noticed that the power function xm(m∈N0), calculated using Clifford algebras, is a conjugate gradient of a hyperbolic harmonic function. We find a fundamental k-hyperbolic harmonic function. Using this function we are able to find kernels and integral formulas for k-hypermonogenic functions. Earlier these results have been verified for hypermonogenic functions (k= n- 1) and for k-hyperbolic harmonic functions in odd dimensional spaces.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Clifford analysis
Contributors: Eriksson, S., Orelma, H.
Number of pages: 12
Pages: 99-110
Publication date: 2017
Peer-reviewed: Yes
Early online date: 22 Dec 2015

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 27
Issue number: 1
ISSN (Print): 1661-4909
Ratings: 
  • Scopus rating (2017): CiteScore 0.96 SJR 0.698 SNIP 1.444
Original language: English
Source: Bibtex
Source ID: urn:3be942d6de9c9305f7f491e2b5180855

Research output: Contribution to journalArticleScientificpeer-review

Generalized hyperbolic harmonic functions in the plane

We consider solutions of the equation yΔh (x,y)-k ah/ay=0 in the plane. These functions already have been investigated by Weinstein around 1950 in connection of generalized axially symmetric potential theory. We have found several results concerning these type of functions, called k-hyperbolic harmonic functions, in higher dimensions. In this paper, we show in the plane case that it is possible to compute the explicit fundamental solutions in terms of the hyperbolic metric. These results may be used to find fundamental solutions in all even dimensional spaces. The key tools are the transformation properties of hyperbolic metric of the Poincaré upper half space model.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Mathematics, Research group: MAT Clifford analysis
Contributors: Eriksson, S., Orelma, H., Vuojamo, V.
Publication date: 10 Mar 2015

Host publication information

Title of host publication: Proceedings of the International Conference on Numerical Analysis and Applied Mathematics 2014 (ICNAAM-2014)
Volume: 1648
Publisher: American Institute of Physics Inc.
Article number: 440007
ISBN (Print): 9780735412873
ASJC Scopus subject areas: Physics and Astronomy(all)
Keywords: axially symmetric, fundamental solution, Hyperbolic, Laplace-Beltrami
Source: Scopus
Source ID: 84939648578

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Graph Analysis and Applications in Clustering and Content-based Image Retrieval

About 300 years ago, when studying Seven Bridges of Königsberg problem - a famous problem concerning paths on graphs - the great mathematician Leonhard Euler said, “This question is very banal, but seems to me worthy of attention”. Since then, graph theory and graph analysis have not only become one of the most important branches of mathematics, but have also found an enormous range of important applications in many other areas. A graph is a mathematical model that abstracts entities and the relationships between them as nodes and edges. Many types of interactions between the entities can be modeled by graphs, for example, social interactions between people, the communications between the entities in computer networks and relations between biological species. Although not appearing to be a graph, many other types of data can be converted into graphs by cer- tain operations, for example, the k-nearest neighborhood graph built from pixels in an image.

Cluster structure is a common phenomenon in many real-world graphs, for example, social networks. Finding the clusters in a large graph is important to understand the underlying relationships between the nodes. Graph clustering is a technique that partitions nodes into clus- ters such that connections among nodes in a cluster are dense and connections between nodes in different clusters are sparse. Various approaches have been proposed to solve graph clustering problems. A common approach is to optimize a predefined clustering metric using different optimization methods. However, most of these optimization problems are NP-hard due to the discrete set-up of the hard-clustering. These optimization problems can be relaxed, and a sub-optimal solu- tion can be found. A different approach is to apply data clustering
algorithms in solving graph clustering problems. With this approach, one must first find appropriate features for each node that represent the local structure of the graph. Limited Random Walk algorithm uses the random walk procedure to explore the graph and extracts ef- ficient features for the nodes. It incorporates the embarrassing parallel paradigm, thus, it can process large graph data efficiently using mod- ern high-performance computing facilities. This thesis gives the details of this algorithm and analyzes the stability issues of the algorithm.

Based on the study of the cluster structures in a graph, we define the authenticity score of an edge as the difference between the actual and the expected number of edges that connect the two groups of the neighboring nodes of the two end nodes. Authenticity score can be used in many important applications, such as graph clustering, outlier detection, and graph data preprocessing. In particular, a data clus- tering algorithm that uses the authenticity scores on mutual k-nearest neighborhood graph achieves more reliable and superior performance comparing to other popular algorithms. This thesis also theoretically proves that this algorithm can asymptotically find the complete re- covery of the ground truth of the graphs that were generated by a stochastic r-block model.

Content-based image retrieval (CBIR) is an important application in computer vision, media information retrieval, and data mining. Given a query image, a CBIR system ranks the images in a large image database by their “similarities” to the query image. However, because of the ambiguities of the definition of the “similarity”, it is very diffi- cult for a CBIR system to select the optimal feature set and ranking algorithm to satisfy the purpose of the query. Graph technologies have been used to improve the performance of CBIR systems in var- ious ways. In this thesis, a novel method is proposed to construct a visual-semantic graph—a graph where nodes represent semantic concepts and edges represent visual associations between concepts. The constructed visual-semantic graph not only helps the user to locate the target images quickly but also helps answer the questions related to the query image. Experiments show that the efforts of locating the target image are reduced by 25% with the help of visual-semantic graphs.

Graph analysis will continue to play an important role in future data analysis. In particular, the visual-semantic graph that captures important and interesting visual associations between the concepts is worthyof further attention.

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Computing Sciences, Research group: Multimedia Research Group - MRG
Contributors: Zhang, H.
Number of pages: 122
Publication date: 9 Aug 2019

Publication information

Publisher: Tampere University
Volume: 101
ISBN (Print): 978-952-03-1183-4
ISBN (Electronic): 978-952-03-1184-1
Original language: English

Publication series

Name: Tampere University Dissertations
Volume: 101
ISSN (Print): 2489-9860
ISSN (Electronic): 2490-0028

Research output: Book/ReportDoctoral thesisCollection of Articles

Graph-Based Map Matching for Indoor Positioning

This article presents a probabilistic motion model that is based on an economical graph-based indoor map representation, such that the motion of the user is constrained according to the floor plan of a building. The floor plan is modeled as a combination of links and open space polygons that are connected by nodes. In the authors’ earlier work the link transition probabilities in this graph are proportional to the total link lengths that are the total lengths of the subgraphs accessible by choosing the considered link option, and this article extends this model to include open space polygons as well. A particle filter using the extended motion model in which all particles are constrained according to the map structure is presented. Furthermore, wireless local area network and Bluetooth Low Energy positioning tests show that the proposed algorithm outperforms comparison methods especially if the measurement rate is low.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: Wireless Communications and Positioning, Department of Automation Science and Engineering, Research area: Dynamic Systems, Department of Mathematics, Research group: MAT Positioning, Research group: Positioning
Contributors: Koivisto, M., Nurminen, H., Ali-Löytty, S., Piche, R.
Number of pages: 5
Publication date: 1 Dec 2015

Host publication information

Title of host publication: 10th International Conference on Information, Communications and Signal Processing (ICICS)
Publisher: IEEE
ISBN (Electronic): 9781467372176
Keywords: Indoor positioning, particle filter, motion model, map matching, graph
Electronic versions: 

Bibliographical note

ISBN of the USB proceedings. Will appear in IEEE Xplore.

ORG=ase,0.8
ORG=mat,0.2

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Graph entropy based on the number of spanning forests of c-cyclic graphs

Graph entropies have been introduced to quantitatively measure the structural information content of graphs and networks; they have plenty of applications in various fields. Utilizing the number of subgraphs to establish measures for determining the complexity of molecular graphs are also prevalent in the study of mathematical chemistry. In this paper, we develop a new graph entropy measure that is based on the number of spanning forests. We prove explicit expressions for the entropy for trees, unicyclic and bicyclic graphs, and show that the cycle graph Cn attains the maximal value of the entropy for unicyclic graphs with order n and large cycle lengths. Based on generating numerical results, we conjecture extremal unicyclic graphs with respect to the entropy as well as we compare the values of our entropy for c-cyclic graphs, and generate graphs of bicyclic graphs and tricyclic graphs with 6 vertices for performing further research.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Predictive Society and Data Analytics (PSDA), Northwestern Polytechnical University, Yulin University, Beijing University of Chemical Technology, University of Applied Sciences Upper Austria, School of Management, Nankai University, Hall in Tyrol, Mathematics Faculty of Information Technology and Communication Sciences
Contributors: Wan, P., Tu, J., Dehmer, M., Zhang, S., Emmert-Streib, F.
Publication date: 15 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Applied Mathematics and Computation
Volume: 363
Article number: 124616
ISSN (Print): 0096-3003
Original language: English
ASJC Scopus subject areas: Computational Mathematics, Applied Mathematics
Keywords: Graph entropy, Spanning forest, Subgraph
Source: Scopus
Source ID: 85073703315

Research output: Contribution to journalArticleScientificpeer-review

Gravitational scattering by giant planets

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Laakso, T., Rantala, J., Kaasalainen, M.
Pages: 373-378
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 456
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2006): SJR 3.646 SNIP 1.418
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 16838

Research output: Contribution to journalArticleScientificpeer-review

Guard-based Partial Order Reduction

This paper aims at making partial-order reduction independent of the modeling language. To this end, we present a guard-based method which is a general-purpose implementation of the stubborn set method. We approach the implementation through so-called necessary enabling sets and do-not-accord sets, and give an algorithm suitable for an abstract model checking interface. We also introduce necessary disabling sets and heuristics to produce smaller stubborn sets and thus better reduction at low costs. We explore the effect of these methods using an implementation in the model checker LTSmin. We experiment with partial-order reduction on a number of Promela models, on benchmarks from the BEEM database in the DVE language, and with several with LTL properties. The efficiency of the heuristic algorithm is established by a comparison to the subset-minimal Deletion algorithm and the simple closure algorithm. We also compare our results to the Spin model checker. While the reductions take longer, they are consistently better than Spin ’s ample set and often surpass the upper bound for the process-based ample sets, established empirically earlier on BEEM models.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Computer Science and Applied Logics
Contributors: Laarman, A., Pater, E., Van de Pol, J., Hansen, H.
Pages: 427-448
Publication date: Dec 2014
Peer-reviewed: Yes

Publication information

Journal: International Journal on Software Tools for Technology Transfer
Volume: