M1-teknologialla voidaan rakentaa virtuaalisia oppimisympäristöjä ja konelaboratorioita

General information

Publication status: Published
MoE publication type: B1 Article in a scientific magazine
Organisations: Department of Intelligent Hydraulics and Automation, Department of Mathematics
Contributors: Koskinen, K. T., Leino, T., Palonen, T., Ranta, P.
Pages: 18-20
Publication date: 2010
Peer-reviewed: No

Publication information

Journal: Fluid Finland
Issue number: 2/2010
ISSN (Print): 1458-7599
Original language: Finnish

Bibliographical note

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

Source: researchoutputwizard
Source ID: 8460

Research output: Contribution to journalArticleScientific

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

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

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

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

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

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 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 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 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: 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

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 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 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

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

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

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

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

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 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

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 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 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 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 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

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

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

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 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

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

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: 18
Issue number: 4
ISSN (Print): 1433-2779
Ratings: 
  • Scopus rating (2014): CiteScore 1.5 SJR 0.569 SNIP 1.565
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Harmonic Forms on Conformal Euclidean Manifolds: The Clifford Multivector Approach

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Orelma, H.
Pages: 143-158
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 22
Issue number: 1
ISSN (Print): 0188-7009
Ratings: 
  • Scopus rating (2012): CiteScore 0.62 SJR 0.575 SNIP 0.991
Original language: English

Bibliographical note

Online first, Springer<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 4989

Research output: Contribution to journalArticleScientificpeer-review

Hierarchical Bayesian inference for the EEG inverse problem using realistic FE head models: Depth localization and source separation for focal primary currents

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Lucka, F., Pursiainen, S., Burger, M., Wolters, C. H.
Pages: 1364-1382
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: NeuroImage
Volume: 61
Issue number: 4
ISSN (Print): 1053-8119
Ratings: 
  • Scopus rating (2012): CiteScore 6.86 SJR 4.026 SNIP 1.972
Original language: English

Bibliographical note

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

Source: researchoutputwizard
Source ID: 4745

Research output: Contribution to journalArticleScientificpeer-review

Homogeneous internal structure of CM-like asteroid (41) Daphne

Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy and numerical modeling of their early thermal evolution. Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3D shape, using our ADAM shape modeling algorithm. Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77 ± 0.26 g cm -3 (3 σ). This densityis consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (≈ 17%). Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, CNRS, IMCCE - Institut de Mecanique Celeste et de Calcul des Ephemerides, Queen's University, Belfast, Northern Ireland, Laboratoire d'Astrophysique de Marseille, Open University, Southwest Research Institute, Université Côte d'Azur, University of Arizona, Adam Mickiewicz University, University of Szczecin, Charles University in Prague, Thirty-Meter-Telescope, Leidos Inc., Binary Astronomy, Universite de Geneve, Cadi Ayyad University, Jet Propulsion Laboratory, California Institute of Technology, ESTEC - European Space Research and Technology Centre, Observatoire du Bois de Bardon, Université de Liège, Max Planck Institute for Astronomy, SETI Institute, Pontifical Catholic University of Peru San Miguel, Center for Solar System Studies, European Southern Observatory (ESO), Universidad Diego Portales
Contributors: Carry, B., Vachier, F., Berthier, J., Marsset, M., Vernazza, P., Grice, J., Merline, W. J., Lagadec, E., Fienga, A., Conrad, A., Podlewska-Gaca, E., Santana-Ros, T., Viikinkoski, M., Hanuš, J., Dumas, C., Drummond, J. D., Tamblyn, P. M., Chapman, C. R., Behrend, R., Bernasconi, L., Bartczak, P., Benkhaldoun, Z., Birlan, M., Castillo-Rogez, J., Cipriani, F., Colas, F., Drouard, A., Durech, J., Enke, B. L., Fauvaud, S., Ferrais, M., Fetick, R., Fusco, T., Gillon, M., Jehin, E., Jorda, L., Kaasalainen, M., Keppler, M., Kryszczynska, A., Lamy, P., Marchis, F., Marciniak, A., Michalowski, T., Michel, P., Pajuelo, M., Tanga, P., Vigan, A., Warner, B., Witasse, O., Yang, B., Zurlo, A.
Publication date: 1 Mar 2019
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 623
Article number: A132
ISSN (Print): 0004-6361
Original language: English
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Keywords: asteroids: general, Methods: observational, Minor planets, Minor planets, asteroids: individual: Daphne, Techniques: high angular resolution
Electronic versions: 
Source: Scopus
Source ID: 85063919795

Research output: Contribution to journalArticleScientificpeer-review

Hosoya entropy of fullerene graphs

Entropy-based methods are useful tools for investigating various problems in mathematical chemistry, computational physics and pattern recognition. In this paper we introduce a general framework for applying Shannon entropy to fullerene graphs, and used it to investigate their properties. We show that important physical properties of these molecules can be determined by applying Hosoya entropy to their corresponding graphs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Predictive Society and Data Analytics (PSDA)
Contributors: Ghorbani, M., Dehmer, M., Rajabi-Parsa, M., Emmert-Streib, F., Mowshowitz, A.
Number of pages: 11
Pages: 88-98
Publication date: 1 Jul 2019
Peer-reviewed: Yes

Publication information

Journal: Applied Mathematics and Computation
Volume: 352
ISSN (Print): 0096-3003
Original language: English
Keywords: Graph entropy, Graph automorphism, Fullerene graphs
Source: RIS
Source ID: urn:DFAB2DC41C0C5DDD065F5B790B659EFA

Research output: Contribution to journalArticleScientificpeer-review

How management intensity and neighborhood composition affect the structure of beech (Fagus sylvatica L.) trees

Key message: The intensity of silvicultural interventions and the neighborhood composition determine branching patterns, crown shape, and trunk attributes of beech (Fagus sylvaticaL.) trees.Abstract: The intensity of silvicultural interventions and the composition of tree species are important forest management decisions. Both determine tree shape and thus influence the value of a tree, be it in terms of economy (trunk form, branchiness), or in terms of ecology (microhabitats). However, our knowledge on the distinct changes in tree architecture due to silvicultural management intensity or different neighborhood diversities is still limited, especially if the focus is on single tree attributes, e.g., branching patterns or crown shapes. We used terrestrial laser scanner data to calculate 25 structural measures for 55 European beech (Fagus sylvatica L.) trees that grew either in pure stands along a gradient of management intensity or in intra or interspecific neighborhoods in unmanaged stands. We found a lower height of maximal horizontal crown extension, a higher crown surface area, and straighter trunks with increasing management intensity. Moreover, our study revealed that beech trees surrounded by valuable hardwoods showed a lower height of maximal horizontal crown extension, a lower height–diameter ratio, and longer branches with flatter branch angles than beech trees surrounded by conspecific neighbors. Our findings provide evidence of phenotypic plasticity of European beech to diverse environmental conditions. The differences in tree structure indicate an increasing crown competition with decreasing management intensity and stronger competitive pressure for beech surrounded by conspecific neighbors in comparison to alien neighbors.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, University of Goettingen, Department of Applied Health Research
Contributors: Juchheim, J., Annighöfer, P., Ammer, C., Calders, K., Raumonen, P., Seidel, D.
Number of pages: 13
Pages: 1723–1735
Publication date: 14 Jul 2017
Peer-reviewed: Yes

Publication information

Journal: TREES-STRUCTURE AND FUNCTION
Volume: 31
Issue number: 5
ISSN (Print): 0931-1890
Ratings: 
  • Scopus rating (2017): CiteScore 1.88 SJR 0.726 SNIP 0.945
Original language: English
ASJC Scopus subject areas: Forestry, Physiology, Ecology, Plant Science
Keywords: Competition, Crown plasticity, Quantitative structural models, Terrestrial laser scanning, Thinning, Tree architecture
Source: Scopus
Source ID: 85023781959

Research output: Contribution to journalArticleScientificpeer-review

Hubble Space Telescope observations of the nucleus and inner coma 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., Weaver, H., Jorda, L., Kaasalainen, M., Gutierrez, P.
Pages: 669-678
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 458
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: 16897

Research output: Contribution to journalArticleScientificpeer-review

Hyperbolic extensions of integral formulas

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S.
Pages: 575-586
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 20
Issue number: 3-4
ISSN (Print): 0188-7009
Ratings: 
  • Scopus rating (2010): SJR 0.383 SNIP 0.827
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7881

Research output: Contribution to journalArticleScientificpeer-review

Hyperbolic Function Theory in the Skew-Field of Quaternions

We are studying hyperbolic function theory in the total skew-field of quaternions. Earlier the theory has been studied for quaternion valued functions depending only on three reduced variables. Our functions are depending on all four coordinates of quaternions. We consider functions, called α-hyperbolic harmonic, that are harmonic with respect to the Riemannian metric dsα2=dx02+dx12+dx22+dx32x3αin the upper half space R+4={(x0,x1,x2,x3)∈R4:x3>0}. If α= 2 , the metric is the hyperbolic metric of the Poincaré upper half-space. Hempfling and Leutwiler started to study this case and noticed that the quaternionic power function xm(m∈Z), is a conjugate gradient of a 2-hyperbolic harmonic function. They researched polynomial solutions. Using fundamental α-hyperbolic harmonic functions, depending only on the hyperbolic distance and x3, we verify a Cauchy type integral formula for conjugate gradient of α-hyperbolic harmonic functions. We also compare these results with the properties of paravector valued α-hypermonogenic in the Clifford algebra Cℓ0,3.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Department of Mathematics and Statistics, Helsinki University
Contributors: Eriksson, S., Orelma, H.
Publication date: 1 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 29
Issue number: 5
Article number: 97
ISSN (Print): 0188-7009
Original language: English
ASJC Scopus subject areas: Applied Mathematics
Keywords: Clifford algebra, Hyperbolic Laplace operator, Hyperbolic metric, Laplace–Beltrami operator, Monogenic function, Quaternions, α-hyperbolic harmonic, α-hypermonogenic

Bibliographical note

EXT="Eriksson, Sirkka-Liisa"

Source: Scopus
Source ID: 85073523419

Research output: Contribution to journalArticleScientificpeer-review

Hyperbolic Laplace Operator and the Weinstein Equation in R^3

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Number of pages: 16
Pages: 1-16
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
ISSN (Print): 0188-7009
Ratings: 
  • Scopus rating (2013): CiteScore 0.66 SJR 0.427 SNIP 1.151
Original language: English

Bibliographical note

Online first; Published online: 22 October 2013<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-11-29<br/>Publisher name: Springer

Source: researchoutputwizard
Source ID: 2115

Research output: Contribution to journalArticleScientificpeer-review

Hypermonogenic Plane Wave Solutions of the Dirac Equation in Superspace

In this paper, we obtain Cauchy–Kovalevskaya theorems for hypermonogenic superfunctions depending only on purely bosonic and fermionic vector variables. In addition, we use these results to construct plane wave examples of such functions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Civil Engineering, Universiteit Gent
Contributors: Adán, A. G., Orelma, H., Sommen, F.
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 29
Issue number: 4
Article number: 71
ISSN (Print): 0188-7009
Original language: English
ASJC Scopus subject areas: Applied Mathematics
Keywords: Cauchy–Kovalevskaya extension, Clifford analysis, Hypermonogenic functions, Plane waves, Superspace
Source: Scopus
Source ID: 85069655339

Research output: Contribution to journalArticleScientificpeer-review

If a student takes control: facilitators' tasks and responsibilities

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Väljataga, T.
Pages: 390-399
Publication date: 2009
Peer-reviewed: Yes

Publication information

Journal: Lecture Notes in Computer Science
Volume: 5686
ISSN (Print): 0302-9743
Ratings: 
  • Scopus rating (2009): SJR 0.302 SNIP 0.576
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 11603

Research output: Contribution to journalArticleScientificpeer-review

Images of asteroid 21 Lutetia: A remnant planetesimal from the early solar system

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Sierks, H., Lamy, P., Barbieri, C., Koschny, D., Rickman, H., Rodrigo, R., A'Hearn, M., Angrilli, F., Barucci, M., Bertaux, J., Bertini, I., Besse, S., Carry, B., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., De Leon, J., Ferri, F., Fornasier, S., Fulle, M., Hviid, S., Gaskell, R., Groussin, O., Gutierrez, P., Ip, W., Jorda, L., Kaasalainen, M., Keller, H., Knollenberg, J., Kramm, R., Kührt, E., Küppers, M., Lara, L., Lazzarin, M., Leyrat, C., Lopez Moreno, J., Magrin, S., Marchi, S., Marzari, F., Massironi, M., Michalik, H., Moissl, R., Naletto, G., Preusker, F., Sabau, L., Sabolo, W., Scholten, F., Snodgrass, C., Thomas, N., Tubiana, C., Vernazza, P., Vincent, J., Wenzel, K., Andert, T., Pätzold, M., Weiss, B.
Pages: 487-490
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Science
Volume: 334
Issue number: 6055
ISSN (Print): 0036-8075
Ratings: 
  • Scopus rating (2011): CiteScore 11.97 SJR 14.238 SNIP 8.226
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7251

Research output: Contribution to journalArticleScientificpeer-review

Improved EEG source localization with Bayesian uncertainty modelling of unknown skull conductivity

Electroencephalography (EEG) source imaging is an ill-posed inverse problem that requires accurate conductivity modelling of the head tissues, especially the skull. Unfortunately, the conductivity values are difficult to determine in vivo. In this paper, we show that the exact knowledge of the skull conductivity is not always necessary when the Bayesian approximation error (BAE) approach is exploited. In BAE, we first postulate a probability distribution for the skull conductivity that describes our (lack of) knowledge on its value, and model the effects of this uncertainty on EEG recordings with the help of an additive error term in the observation model. Before the Bayesian inference, the likelihood is marginalized over this error term. Thus, in the inversion we estimate only our primary unknown, the source distribution. We quantified the improvements in the source localization when the proposed Bayesian modelling was used in the presence of different skull conductivity errors and levels of measurement noise. Based on the results, BAE was able to improve the source localization accuracy, particularly when the unknown (true) skull conductivity was much lower than the expected standard conductivity value. The source locations that gained the highest improvements were shallow and originally exhibited the largest localization errors. In our case study, the benefits of BAE became negligible when the signal-to-noise ratio dropped to 20 dB.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Bath, Institute for Biomagnetism and Biosignalanalysis, University of Münster, Aristotle University of Thessaloniki, Centrum Wiskunde & Informatica, University College London, The University of Auckland, University of Eastern Finland
Contributors: Rimpiläinen, V., Koulouri, A., Lucka, F., Kaipio, J. P., Wolters, C. H.
Number of pages: 9
Pages: 252-260
Publication date: 1 Mar 2019
Peer-reviewed: Yes
Early online date: 6 Dec 2018

Publication information

Journal: NeuroImage
Volume: 188
ISSN (Print): 1053-8119
Original language: English
ASJC Scopus subject areas: Neurology, Cognitive Neuroscience
Keywords: Bayesian inverse problem, Electroencephalography, Skull conductivity, Source localization, Uncertainty modelling
Electronic versions: 
URLs: 

Bibliographical note

EXT="Rimpiläinen, Ville"

Source: Scopus
Source ID: 85058408352

Research output: Contribution to journalArticleScientificpeer-review

Indirect Emissions of Forest Bioenergy: Detailed Modelling of Stump-Root Systems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Liski, J., Kaasalainen, S., Raumonen, P., Akujärvi, A., Krooks, A., Repo, A., Kaasalainen, M.
Number of pages: 8
Pages: 777-784
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Global Change Biology Bioenergy
Volume: 6
Issue number: 6
ISSN (Print): 1757-1693
Ratings: 
  • Scopus rating (2014): CiteScore 4.81 SJR 2.367 SNIP 1.831
Original language: English

Bibliographical note

Article first published online: 26 MAY 2013<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2013-07-29<br/>Publisher name: Wiley-Blackwell

Source: researchoutputwizard
Source ID: 957

Research output: Contribution to journalArticleScientificpeer-review

Information Diversity in Structure and Dynamics of Simulated Neuronal Networks

Neuronal networks exhibit a wide diversity of structures, which contributes to the diversity of the dynamics therein. The presented work applies an information theoretic framework to simultaneously analyze structure and dynamics in neuronal networks. Information diversity within the structure and dynamics of a neuronal network is studied using the normalized compression distance. To describe the structure, a scheme for generating distance-dependent networks with identical in-degree distribution but variable strength of dependence on distance is presented. The resulting network structure classes possess differing path length and clustering coefficient distributions. In parallel, comparable realistic neuronal networks are generated with NETMORPH simulator and similar analysis is done on them. To describe the dynamics, network spike trains are simulated using different network structures and their bursting behaviors are analyzed. For the simulation of the network activity the Izhikevich model of spiking neurons is used together with the Tsodyks model of dynamical synapses. We show that the structure of the simulated neuronal networks affects the spontaneous bursting activity when measured with bursting frequency and a set of intraburst measures: the more locally connected produce more and longer bursts than the more random networks. The information diversity of the structure of a network is greatest in the most locally connected, smallest in random networks, and somewhere in between in the networks between order and disorder. As for the dynamics, the most locally connected and some of the in-between networks produce the most complex intraburst spike trains. The same result also holds for sparser of the two considered network densities in the case of full spike trains.

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: Algebraic and Algorithmic Methods in Signal Processing AAMSP, Research group: Computational Systems Biology, Multi-scaled biodata analysis and modelling (MultiBAM), Prostate cancer research center (PCRC)
Contributors: Mäki-Marttunen, T., Acimovic, J., Nykter, M., Kesseli, J., Ruohonen, K., Yli-Harja, O., Linne, M.
Number of pages: 17
Pages: 1-17
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Frontiers in Computational Neuroscience
Volume: 5
Article number: 26
ISSN (Print): 1662-5188
Ratings: 
  • Scopus rating (2011): CiteScore 3 SJR 1.514 SNIP 0.732
Original language: English

Bibliographical note

Ei UT-numeroa 5.4.2014<br/>Contribution: organisation=sgn,FACT1=0.7<br/>Contribution: organisation=mat,FACT2=0.3

Source: researchoutputwizard
Source ID: 6702

Research output: Contribution to journalArticleScientificpeer-review

Integral kernels for k-hypermonogenic functions

We consider the modified Cauchy–Riemann operator (Formula presented.) in the universal Clifford algebra (Formula presented.) with the basis (Formula presented.). The null-solutions of this operator are called k-hypermonogenic functions. We calculate the k-hyperbolic harmonic fundamental solutions, i.e. solutions to (Formula presented.), and use these solutions to find k-hypermonogenic kernels for a Cauchy-type integral formula in the upper half-space.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Helsinki
Contributors: Vuojamo, V., Eriksson, S.
Number of pages: 12
Pages: 1-12
Publication date: 2017
Peer-reviewed: Yes
Early online date: 21 Feb 2017

Publication information

Journal: Complex Variables and Elliptic Equations
Volume: 62
Issue number: 9
ISSN (Print): 1747-6933
Ratings: 
  • Scopus rating (2017): CiteScore 0.73 SJR 0.616 SNIP 0.989
Original language: English
ASJC Scopus subject areas: Analysis, Numerical Analysis, Computational Mathematics, Applied Mathematics
Keywords: Cauchy integral formula, Clifford algebra, hyperbolic Laplace–Beltrami, k-hyperbolic harmonic, k-hypermonogenic

Bibliographical note

EXT="Eriksson, Sirkka-Liisa"

Source: Scopus
Source ID: 85013192611

Research output: Contribution to journalArticleScientificpeer-review

Internal model theory for distributed parameter systems

In this paper we consider robust output regulation of distributed parameter systems and the internal model principle. The main purpose is to generalize the internal model principle by Francis and Wonham for infinite-dimensional systems and clarify the relationships between different generalizations of the internal model. We also construct a signal generator capable of generating infinite-dimensional polynomially increasing signals.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Paunonen, L., Pohjolainen, S.
Pages: 4753-4775
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: SIAM Journal on Control and Optimization
Volume: 48
Issue number: 7
ISSN (Print): 0363-0129
Ratings: 
  • Scopus rating (2010): SJR 1.648 SNIP 1.95
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8952

Research output: Contribution to journalArticleScientificpeer-review

Interval decomposition lattices are balanced

Intervals in binary or n-ary relations or other discrete structures generalize the concept of an interval in a linearly ordered set. They are defined abstractly as closed sets of a closure system on a set, satisfying certain axioms. Join-irreducible partitions into intervals are characterized in the lattice of all interval decompositions. This result is used to show that the lattice of interval decompositions is balanced, and the case when this lattice is distributive is also characterised.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, University of Miskolc
Contributors: Foldes, S., Radeleczki, S.
Number of pages: 11
Pages: 271-281
Publication date: 1 Sep 2016
Peer-reviewed: Yes

Publication information

Journal: DEMONSTRATIO MATHEMATICA
Volume: 49
Issue number: 3
ISSN (Print): 0420-1213
Ratings: 
  • Scopus rating (2016): CiteScore 0.3 SJR 0.355 SNIP 0.657
Original language: English
ASJC Scopus subject areas: Mathematics(all)
Keywords: Balanced lattice, Closure system, Interval decomposition, Join-irreducible element, Semimodular lattice, Strong set
Electronic versions: 
Source: Scopus
Source ID: 84991000276

Research output: Contribution to journalArticleScientificpeer-review

Interventions for second-order change in higher education: challenges and barriers

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Fiedler, S., Väljataga, T.
Pages: 85-92
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Electronic Journal of e-Learning
Volume: 8
Issue number: 2
ISSN (Print): 1479-4403
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 7908

Research output: Contribution to journalArticleScientificpeer-review

Inverse problems of generalized projection operators

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Kaasalainen, M., Lamberg, L.
Pages: 749-769
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Inverse Problems
Volume: 22
Issue number: 3
ISSN (Print): 0266-5611
Ratings: 
  • Scopus rating (2006): SJR 0.924 SNIP 1.842
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 16573

Research output: Contribution to journalArticleScientificpeer-review

Invertibility and Dedekind finiteness in structural matrix rings

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Foldes, S., Szigeti, J., van Wyk, L.
Pages: 221-227
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Linear and Multilinear Algebra
Volume: 59
Issue number: 2
ISSN (Print): 0308-1087
Ratings: 
  • Scopus rating (2011): CiteScore 0.85 SJR 0.819 SNIP 1.147
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 5946

Research output: Contribution to journalArticleScientificpeer-review

Iterative alternating sequential (IAS) method for radio tomography of asteroids in 3D

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: 15
Pages: 84-98
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Planetary and Space Science
Volume: 82-83
ISSN (Print): 0032-0633
Ratings: 
  • Scopus rating (2013): CiteScore 1.59 SJR 0.865 SNIP 0.798
Original language: English

Bibliographical note

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

Source: researchoutputwizard
Source ID: 3194

Research output: Contribution to journalArticleScientificpeer-review

Kalman filter with a linear state model for PDR+WLAN positioning and its application to assisting a particle filter

Indoor positioning based on wireless local area network (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, the positioning accuracy with this linear model is better than with the traditional models when the initial heading is not known, which is a common situation. The proposed method is computationally light and is also suitable for smoothing. Furthermore, we present modifications to WLAN positioning based on Gaussian coverage areas and show how a Kalman filter using the proposed model can be used for integrity monitoring and (re)initialization of a particle filter.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research area: Dynamic Systems, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Nurminen, H., Piché, R.
Publication date: 1 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2015
Issue number: 1
Article number: 33
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: Computational modeling, Indoor positioning, Pedestrian dead reckoning, Wireless LAN
Electronic versions: 
Source: Scopus
Source ID: 84928397748

Research output: Contribution to journalArticleScientificpeer-review

Kehittämistutkimus: vuorovaikutteisten Matlab-opetusohjelmien vaikutus minäpystyvyyteen ja oppimistuloksiin yliopistomatematiikassa

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics, Research group: Positioning
Contributors: Kaarakka, T. E., Ali-Löytty, S., Huhtanen, M.
Number of pages: 11
Pages: 67-77
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: FMSERA Journal
Volume: 2
Issue number: 1
ISSN (Print): 2489-4583
Original language: Finnish

Research output: Contribution to journalArticleScientificpeer-review

Kriging prediction of stand-level forest information using mobile laser scanning data adjusted for nondetection

This study presents an approach for predicting stand-level forest attributes utilizing mobile laser scanning data collected as a nonprobability sample. Firstly, recordings of stem density were made at point locations every 10th metre along a subjectively chosen mobile laser scanning track in a forest stand. Secondly, kriging was applied to predict stem density values for the centre point of all grid cells in a 5 m x 5 m lattice across the stand. Thirdly, due to nondetectability issues, a correction term was computed based on distance sampling theory. Lastly, the mean stem density at stand level was predicted as the mean of the point-level predictions multiplied with the correction factor, and the corresponding variance was estimated. Many factors contribute to the uncertainty of the stand-level prediction; in the variance estimator, we accounted for the uncertainties due to kriging prediction and due to estimating a detectability model from the laser scanning data. The results from our new approach were found to correspond fairly well to estimates obtained using field measurements from an independent set of 54 circular sample plots. The predicted number of stems in the stand based on the proposed methodology was 1366 with a 12.9% relative standard error. The corresponding estimate based on the field plots was 1677 with a 7.5% relative standard error.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems, Norwegian Inst Bioecon Res, Swedish University of Agricultural Sciences, University System Of New Hampshire
Contributors: Saarela, S., Breidenbach, J., Raumonen, P., Grafström, A., Ståhl, G., Ducey, M. J., Astrup, R.
Number of pages: 9
Pages: 1257-1265
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
Volume: 47
Issue number: 9
ISSN (Print): 0045-5067
Ratings: 
  • Scopus rating (2017): CiteScore 2.06 SJR 0.969 SNIP 0.956
Original language: English
Keywords: covariogram, detectability function, forest management, model-based inference, TREE STEM, ABOVEGROUND BIOMASS, ASSISTED ESTIMATION, SPACEBORNE LIDAR, BOUNDARY OVERLAP, AIRBORNE, INVENTORY, MODELS, SYSTEM, VOLUME
Source: WOS
Source ID: 000408223000012

Research output: Contribution to journalArticleScientificpeer-review

Kullback-Leibler Divergence Approach to Partitioned Update Kalman Filter

Kalman filtering is a widely used framework for Bayesian estimation. The partitioned update Kalman filter applies a Kalman filter update in parts so that the most linear parts of measurements are applied first. In this paper, we generalize partitioned update Kalman filter, which requires the use of the second order extended Kalman filter, so that it can be used with any Kalman filter extension such as the unscented Kalman filter. To do so, we use a Kullback-Leibler divergence approach to measure the nonlinearity of the measurement, which is theoretically more sound than the nonlinearity measure used in the original partitioned update Kalman filter. Results show that the use of the proposed partitioned update filter improves the estimation accuracy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research area: Dynamic Systems, Research group: Positioning
Contributors: Raitoharju, M., García-Fernádez, Á., Piche, R.
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Signal Processing
Volume: 130
ISSN (Print): 0165-1684
Ratings: 
  • Scopus rating (2017): CiteScore 3.94 SJR 0.94 SNIP 1.947
Original language: English
Electronic versions: 
  • KLPUKF. Embargo ended: 15/07/18

Research output: Contribution to journalArticleScientificpeer-review

LEADER: fast estimates of asteroid shape elongation and spin latitude distributions from scarce photometry

Context. Many asteroid databases with lightcurve brightness measurements (e.g. WISE, Pan-STARRS1) contain enormous amounts of data for asteroid shape and spin modelling. While lightcurve inversion is not plausible for individual targets with scarce data, it is possible for large populations with thousands of asteroids, where the distributions of the shape and spin characteristics of the populations are obtainable.

Aims. We aim to introduce a software implementation of a method that computes the joint shape elongation p and spin latitude β distributions for a population, with the brightness observations given in an asteroid database. Other main goals are to include a method for performing validity checks of the algorithm, and a tool for a statistical comparison of populations.

Methods. The LEADER software package read the brightness measurement data for a user-defined subpopulation from a given database. The observations were used to compute estimates of the brightness variations of the population members. A cumulative distribution function (CDF) was constructed of these estimates. A superposition of known analytical basis functions yielded this CDF as a function of the (shape, spin) distribution. The joint distribution can be reconstructed by solving a linear constrained inverse problem. To test the validity of the method, the algorithm can be run with synthetic asteroid models, where the shape and spin characteristics are known, and by using the geometries taken from the examined database.

Results. LEADER is a fast and robust software package for solving shape and spin distributions for large populations. There are major differences in the quality and coverage of measurements depending on the database used, so synthetic simulations are always necessary before a database can be reliably used. We show examples of differences in the results when switching to another database.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Inverse Problems
Contributors: Nortunen, H., Kaasalainen, M.
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 608
Article number: A91
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2017): CiteScore 3.8 SJR 2.265 SNIP 1.257
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Learner control and personal learning environment: a challenge for instructional design

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Väljataga, T., Laanpere, M.
Pages: 277-291
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Interactive Learning Environments
Volume: 18
Issue number: 3
ISSN (Print): 1049-4820
Ratings: 
  • Scopus rating (2010): SJR 0.597 SNIP 1.215
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9504

Research output: Contribution to journalArticleScientificpeer-review

Main-belt binary asteroidal systems with circular orbits

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Marchis, F., Descamps, P., Baek, M., Harris, A., Kaasalainen, M., Berthier, J., Hestroffer, D., Vachier, F.
Pages: 97-118
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Icarus
Volume: 196
ISSN (Print): 0019-1035
Ratings: 
  • Scopus rating (2008): SJR 2.584 SNIP 1.21
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 12977

Research output: Contribution to journalArticleScientificpeer-review

Manifolds in electromagnetism and superconductor modelling: Using their properties to model critical current of twisted conductors in self-field with 2-D model

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electrical Engineering, Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact)
Contributors: Stenvall, A., Tarhasaari, T., Grilli, F., Raumonen, P., Vojenciak, M., Pellikka, M.
Number of pages: 7
Pages: 135-141
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Cryogenics
Volume: 53
ISSN (Print): 0011-2275
Ratings: 
  • Scopus rating (2013): CiteScore 1.04 SJR 0.457 SNIP 1.127
Original language: English

Bibliographical note

Contribution: organisation=dee,FACT1=0.5<br/>Contribution: organisation=mat,FACT2=0.5<br/>Portfolio EDEND: 2013-04-29<br/>Publisher name: Pergamon

Source: researchoutputwizard
Source ID: 3464

Research output: Contribution to journalArticleScientificpeer-review

Maximal perpendicularity in certain Abelian groups

We define perpendicularity in an Abelian group G as a binary relation satisfying certain five axioms. Such a relation is maximal if it is not a subrelation of any other perpendicularity in G. A motivation for the study is that the poset (P, ⊆) of all perpendicularities in G is a lattice if G has a unique maximal perpendicularity, and only a meet-semilattice if not. We study the cardinality of the set of maximal perpendicularities and, on the other hand, conditions on the existence of a unique maximal perpendicularity in the following cases: G ≅ ℤn, G is finite, G is finitely generated, and G = ℤ ⊕ ℤ ⊕⋯. A few such conditions are found and a few conjectured. In studying ℝn, we encounter perpendicularity in a vector space.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Lulea University of Technology
Contributors: Mattila, M., Merikoski, J. K., Haukkanen, P., Tossavainen, T.
Number of pages: 13
Pages: 235-247
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: ACTA UNIVERSITATIS SAPIENTIAE: MATHEMATICA
Volume: 9
Issue number: 1
ISSN (Print): 1844-6094
Ratings: 
  • Scopus rating (2017): CiteScore 0.31 SJR 0.38 SNIP 0.607
Original language: English
ASJC Scopus subject areas: Mathematics(all)
Keywords: Abelian group, Perpendicularity
Source: Scopus
Source ID: 85026624639

Research output: Contribution to journalArticleScientificpeer-review

Mean Value Properties for the Weinstein Equation Using the Hyperbolic Metric

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Pages: 1609-1621
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Complex Analysis and Operator Theory
Volume: 7
Issue number: 5
ISSN (Print): 1661-8254
Ratings: 
  • Scopus rating (2013): CiteScore 0.56 SJR 0.694 SNIP 0.98
Original language: English

Bibliographical note

Tallennettu Online first<br/>Contribution: organisation=mat,FACT1=1<br/>Publisher name: Birkhäuser

Source: researchoutputwizard
Source ID: 2116

Research output: Contribution to journalArticleScientificpeer-review

Meeting a deadline: shortest paths on stochastic directed acyclic graphs with information gathering

We consider the problem of an agent traversing a directed graph with the objective of maximizing the probability of reaching a goal node before a given deadline. Only the probability of the travel times of edges is known to the agent. The agent must balance between traversal actions towards the goal, and delays due to actions improving information about graph edge travel times. We describe the relationship of the problem to the more general partially observable Markov decision process. Further, we show that if edge travel times are independent and the underlying directed graph is acyclic, a closed loop solution can be computed. The solution specifies whether to execute a traversal or information-gathering action as a function of the current node, the time remaining until the deadline, and the information about edge travel times. We present results from two case studies, quantifying the usefulness of information-gathering as opposed to applying only traversal actions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering
Contributors: Lauri, M., Ropponen, A., Ritala, R.
Number of pages: 34
Pages: 337–370
Publication date: Apr 2017
Peer-reviewed: Yes
Early online date: 28 Sep 2016

Publication information

Journal: Annals of Mathematics and Artificial Intelligence
Volume: 79
Issue number: 4
ISSN (Print): 1012-2443
Ratings: 
  • Scopus rating (2017): CiteScore 1.21 SJR 0.413 SNIP 1.036
Original language: English
ASJC Scopus subject areas: Artificial Intelligence, Applied Mathematics
Keywords: Applied probability, Decision processes, Dynamic programming, Markov processes, Transportation
Source: Scopus
Source ID: 84988712384

Research output: Contribution to journalArticleScientificpeer-review

Minimal Characterization of O-notation in Algorithm Analysis

Previously, we showed that linear dominance is the only definition of O-notation suitable for algorithm analysis [1,2]. Linear dominance was characterized by 8 primitive properties as a down-set of a non-trivial scale-invariant preorder which is preserved under certain modifications to algorithms and is consistent with pointwise partial order. In this paper, we provide a minimal characterization of O-notation, where there are no redundant properties. Such is given by excluding locality from primitive properties.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics
Contributors: Rutanen, K.
Pages: 31-41
Publication date: Feb 2018
Peer-reviewed: Yes
Early online date: 27 Dec 2017

Publication information

Journal: Theoretical Computer Science
Volume: 713
ISSN (Print): 0304-3975
Ratings: 
  • Scopus rating (2018): CiteScore 1.23 SJR 0.494 SNIP 1.072
Original language: English
Keywords: O-notation, characterization, minimal
Source: RIS
Source ID: urn:31587026E9CB9CBC88F2461C9E8F550F

Research output: Contribution to journalArticleScientificpeer-review

Minimal solutions of general fuzzy relation equations on linear carriers. An algebraic characterization

This paper considers a general fuzzy relation equation, which has minimal solutions, if it is solvable. In this case, an algebraic characterization is introduced which provides an interesting method to compute minimal solutions in this general setting. Moreover, a comparison with other frameworks is also given.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Mathematics, Research group: Computer Science and Applied Logics
Contributors: Diaz-Moreno, J. C., Medina, J., Turunen, E.
Pages: 112–123
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
Volume: 311
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2017): CiteScore 2.86 SJR 1.138 SNIP 1.733
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Minors of Boolean functions with respect to clique functions and hypergraph homomorphisms

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Lehtonen, E., Nesetril, J.
Pages: 1981-1995
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: European Journal of Combinatorics
Volume: 31
Issue number: 8
ISSN (Print): 0195-6698
Ratings: 
  • Scopus rating (2010): SJR 1.235 SNIP 1.094
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 8598

Research output: Contribution to journalArticleScientificpeer-review

Mixture surrogate models based on Dempster-Shafer theory for global optimization problems

Recent research in algorithms for solving global optimization problems using response surface methodology has shown that it is in general not possible to use one surrogate model for solving different kinds of problems. In this paper the approach of applying Dempster-Shafer theory to surrogate model selection and their combination is described. Various conflict redistribution rules have been examined with respect to their influence on the results. Furthermore, the implications of the surrogate model type, i.e. using combined, single or a hybrid of both, have been studied. The suggested algorithms were applied to several well-known global optimization test problems. The results indicate that the used approach leads for all problems to a thorough exploration of the variable domain, i.e. the vicinities of global optima could be detected, and that the global minima could in most cases be approximated with high accuracy.

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: Muller, J., Piche, R.
Number of pages: 26
Pages: 79-104
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Global Optimization
Volume: 51
Issue number: 1
ISSN (Print): 0925-5001
Ratings: 
  • Scopus rating (2011): CiteScore 1.28 SJR 1.07 SNIP 1.388
Original language: English

Bibliographical note

Online first<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6831

Research output: Contribution to journalArticleScientificpeer-review

Mobile Context-Aware Systems: Technologies, Resources and Applications

Mobile applications often adapt their behavior according to user context, however, they are often limited to consider few sources of contextual information, such as user position or language. This article reviews existing work in context-aware systems (CAS), e.g., how to model context, and discusses further development of CAS and its potential applications by looking at available information, methods and technologies. Social Media seems to be an interesting source of personal information when appropriately exploited. In addition, there are many types of general information, ranging from weather and public transport to information of books and museums. These information sources can be combined in previously unexplored ways, enabling the development of smarter mobile services in different domains. Users are, however, reluctant to provide their personal information to applications; therefore, there is a crave for new regulations and systems that allow applications to use such contextual data without compromising the user privacy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Rivero-Rodriguez, A., Pileggi, P., Nykänen, O. A.
Number of pages: 8
Pages: 25-32
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of Interactive Mobile Technologies
Volume: 10
Issue number: 2
ISSN (Print): 1865-7923
Ratings: 
  • Scopus rating (2016): CiteScore 0.27 SJR 0.169 SNIP 0.186
Original language: English
Keywords: Context-aware Services , Context Awareness, Context Management, Mobile Computing
Electronic versions: 
Source: Bibtex
Source ID: urn:416cbddcc24982dbb51c9c6e1123e281

Research output: Contribution to journalArticleScientificpeer-review

Mobile Tracking in Mixed Line-of-Sight/Non-Line-of-Sight Conditions: Algorithm and Theoretical Lower Bound

The paper investigates the problem of mobile tracking in mixed line-of-sight (LOS)/non-line-of-sight (NLOS) conditions. The motion of mobile station is modeled by a dynamic white noise acceleration model, while the measurements are time of arrival (TOA). A first-order Markov model is employed to describe the dynamic transition of LOS/NLOS conditions. An improved Rao-Blackwellized particle filter (RBPF) is proposed, in which the LOS/NLOS sight conditions are estimated by particle filtering using the optimal trial distribution, and the mobile state is computed by applying approximated analytical methods. The theoretical error lower bound is further studied in the described problem. A new method is presented to compute the posterior Cramer-Rao lower bound (CRLB): the mobile state is first estimated by decentralized extended Kalman filter (EKF) method, then sigma point set and unscented transformation are applied to calculate Fisher information matrix (FIM). Simulation results show that the improved RBPF is more accurate than current methods, and its performance approaches to the theoretical bound.

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: Chen, L., Ali-Löytty, S., Piche, R., Wu, L.
Pages: 753-771
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: WIRELESS PERSONAL COMMUNICATIONS
Volume: 65
Issue number: 4
ISSN (Print): 0929-6212
Ratings: 
  • Scopus rating (2012): CiteScore 0.73 SJR 0.247 SNIP 0.755
Original language: English

Bibliographical note

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

Source: researchoutputwizard
Source ID: 3969

Research output: Contribution to journalArticleScientificpeer-review

Modeling of Neuronal Growth In Vitro: Comparison of Simulation Tools NETMORPH and CX3D

We simulate the growth of neuronal networks using the two recently published tools, NETMORPH and CX3D. The goals of the work are (1) to examine and compare the simulation tools, (2) to construct a model of growth of neocortical cultures, and (3) to characterize the changes in network connectivity during growth, using standard graph theoretic methods. Parameters for the neocortical culture are chosen after consulting both the experimental and the computational work presented in the literature. The first (three) weeks in culture are known to be a time of development of extensive dendritic and axonal arbors and establishment of synaptic connections between the neurons. We simulate the growth of networks from day 1 to day 21. It is shown that for the properly selected parameters, the simulators can reproduce the experimentally obtained connectivity. The selected graph theoretic methods can capture the structural changes during growth.

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: Algebraic and Algorithmic Methods in Signal Processing AAMSP, Research group: Computational Systems Biology
Contributors: Acimovic, J., Mäki-Marttunen, T., Havela, R., Teppola, H., Linne, M.
Number of pages: 13
Pages: 1-13
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Bioinformatics and Systems Biology
Volume: 2011
Article number: 616382
ISSN (Print): 1687-4145
Ratings: 
  • Scopus rating (2011): CiteScore 0.81 SJR 0.508 SNIP 0.728
Original language: English

Bibliographical note

ei ut-numeroa 12.10.2013<br/>Contribution: organisation=sgn,FACT1=0.9<br/>Contribution: organisation=mat,FACT2=0.1

Source: researchoutputwizard
Source ID: 5647

Research output: Contribution to journalArticleScientificpeer-review

Modelling anisotropy in non-oriented electrical steel sheet using vector Jiles-Atherton model

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Energy Engineering, Research area: Power engineering, Aalto University, Graz University of Technology, Tallinn University of Technology
Contributors: Upadhaya, B., Martin, F., Rasilo, P., Handgruber, P., Belahcen, A., Arkkio, A.
Pages: 764-773
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering
Volume: 36
Issue number: 3
ISSN (Print): 0332-1649
Ratings: 
  • Scopus rating (2017): CiteScore 0.75 SJR 0.22 SNIP 0.523
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Modifications of the 85/85 test and the temperature cycling test for tantalum capacitors

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics, Department of Mathematics, Mathematical modelling with wide societal impact (MathImpact), Sensing Systems for Wireless Medicine (MediSense)
Contributors: Virkki, J., Sydänheimo, L., Raumonen, P.
Pages: 168-176
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Soldering and Surface Mount Technology
Volume: 23
Issue number: 3
ISSN (Print): 0954-0911
Ratings: 
  • Scopus rating (2011): CiteScore 0.67 SJR 0.157 SNIP 0.57
Original language: English

Bibliographical note

Tulospisteet 90 % ELE / 10 % MAT<br/>Contribution: organisation=ele,FACT1=0.9<br/>Contribution: organisation=mat,FACT2=0.1

Source: researchoutputwizard
Source ID: 7523

Research output: Contribution to journalArticleScientificpeer-review

Multicolor, rotationally resolved photometry of asteroid 21 Lutetia from Osiris/Rosetta observations

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Lamy, P., Faury, G., Jorda, L., Kaasalainen, M., Hviid, S.
Number of pages: 10
Pages: 1-10
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 521
Issue number: A19
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: 8568

Research output: Contribution to journalArticleScientificpeer-review

Multigrid-Based Inversion for Volumetric Radar Imaging With Asteroid Interior Reconstruction as a Potential Application

This study concentrates on advancing mathematical and computational methodology for radar tomography imaging in which the unknown volumetric velocity distribution of a wave within a bounded domain is to be reconstructed. Our goal is to enable effective simulation and inversion of a large amount of full-wave data within a realistic 2-D or 3-D geometry. For propagating and inverting the wave, we present a rigorous multigrid-based forward approach that utilizes the finite-difference time-domain method and a nested finite element grid structure. We also introduce and validate a multigrid-based inversion algorithm that allows regularization of the unknown distribution through a coarse-to-fine inversion scheme. Using this approach, sparse signals can be effectively inverted, as the coarse fluctuations are reconstructed before the finer ones. Furthermore, the number of nonzero entries in the system matrix can be compressed and, thus, the inversion procedure can be speeded up. As the test scenario, we investigate satellite-based asteroid interior reconstruction. We use both full-wave and projected wave data and estimate the accuracy of the inversion under different error sources: noise and positioning inaccuracies. The results suggest that the present inversion technique allows recovering the interior with a single satellite recording backscattering data. Robust results can be achieved, when the peak-to-peak signal-to-noise ratio is above 10 dB. Furthermore, the robustness for the deep interior part can be enhanced if two satellites can be utilized in the measurements.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics
Contributors: Takala, M., Us, D., Pursiainen, S.
Number of pages: 13
Pages: 228-240
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Computational Imaging
Volume: 4
Issue number: 2
ISSN (Print): 2333-9403
Ratings: 
  • Scopus rating (2018): CiteScore 5.4 SJR 0.837 SNIP 3.18
Original language: English
Keywords: finite difference time-domain analysis, geometry, inverse problems, radar imaging, tomography, unknown volumetric velocity distribution, bounded domain, full-wave data, 3-D geometry, rigorous multigrid-based forward approach, finite-difference time-domain method, nested finite element grid structure, multigrid-based inversion algorithm, coarse-to-fine inversion scheme, asteroid interior reconstruction, inversion technique, single satellite recording backscattering data, peak-to-peak signal-to-noise ratio, deep interior part, volumetric radar imaging, mathematical methodology, computational methodology, radar tomography imaging, Image reconstruction, Solar system, Radar imaging, Permittivity, Tomography, Computational modeling, Multigrid methods, radio tomography, microw-ave tomography, asteroids, biomedical imaging
Source: Bibtex
Source ID: urn:e8d6524261193d516a9b65740487b26d

Research output: Contribution to journalArticleScientificpeer-review

Multimodal inverse problems: maximum compatibility estimate and shape reconstruction

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.
Pages: 37-57
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Inverse Problems and Imaging
Volume: 5
Issue number: 1
ISSN (Print): 1930-8337
Ratings: 
  • Scopus rating (2011): CiteScore 0.96 SJR 0.647 SNIP 1.16
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6255

Research output: Contribution to journalArticleScientificpeer-review

Multiplierless filtered-OFDM transmitter for narrow-band IoT devices

In cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) based radio access, the coexistence of different technologies without precise time-frequency synchronization is limited due to high out-of-band emissions. Therefore, spectrum enhancement techniques play a key role to relax the synchronization and power control requirements. This allows higher degree of opportunistic spectrum use with minimized interference. In addition, all transmitting devices have to fulfill specific transmitted signal quality requirements, including the maximum out-of-band radiated signal power. With OFDM based radio access, some additional signal processing for improved spectrum containment is commonly needed to achieve these requirements. Filtering and time-domain windowing are two fundamentally different approaches for spectrum enhancement. Filtered OFDM (F-OFDM) provides better spectrum localization than the timewindowing schemes (such as windowed overlap-add, WOLA), with the cost of higher complexity. This paper introduces lowcomplexity solutions for spectrally enhanced narrow-band OFDM transmitters based on the use of a look-up tables (LUTs). The proposed LUT approach, requiring only memory units and a low number of additions, allows to avoid all computationally expensive operations in on-line transmitter processing, as it builds the transmitted signal by summing the stored partial waveforms optimized off-line. In certain cases, completely multiplication and summation free designs are possible. The transmitters of narrowband Internet of things (NB-IoT) devices are natural applications for the proposed LUT approach, as they require additional digital baseband signal processing to reach the emission requirements. It is shown that the proposed LUT schemes can provide signicant savings in real-time computations of NB-IoT devices, while fulfilling the 3GPP requirements.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Nokia Bell Labs
Contributors: Loulou, A. E., Yli-Kaakinen, J., Levanen, T., Lehtinen, V., Schaich, F., Wild, T., Renfors, M., Valkama, M.
Pages: 846-862
Publication date: 13 Feb 2020
Peer-reviewed: Yes
Early online date: 2 Oct 2019

Publication information

Journal: IEEE Internet of Things Journal
Volume: 7
Issue number: 2
ISSN (Print): 2327-4662
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Multi-stable dynamics of the non-adiabatic repressilator

The assumption of the fast binding of transcription factors (TFs) to promoters is a typical point in studies of synthetic genetic circuits functioning in bacteria. Although the assumption is effective for simplifying the models, it becomes questionable in the light of in vivo measurements of the times TF spends searching for its cognate DNA sites. We investigated the dynamics of the full idealized model of the paradigmatic genetic oscillator, the repressilator, using deterministic mathematical modelling and stochastic simulations. We found (using experimentally approved parameter values) that decreases in the TF binding rate changes the type of transition between steady state and oscillation. As a result, this gives rise to the hysteresis region in the parameter space, where both the steady state and the oscillation coexist. We further show that the hysteresis is persistent over a considerable range of the parameter values, but the presence of the oscillations is limited by the low rate of TF dimer degradation. Finally, the stochastic simulation of the model confirms the hysteresis with switching between the two attractors, resulting in highly skewed period distributions. Moreover, intrinsic noise stipulates trains of large-amplitude modulations around the stable steady state outside the hysteresis region, which makes the period distributions bimodal.

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), Department of Theoretical Physics, Lebedev Physical Institution
Contributors: Potapov, I., Zhurov, B., Volkov, E.
Publication date: 6 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of the Royal Society. Interface
Volume: 12
Issue number: 104
Article number: 20141315
ISSN (Print): 1742-5689
Ratings: 
  • Scopus rating (2015): CiteScore 3.5 SJR 1.823 SNIP 1.537
Original language: English
ASJC Scopus subject areas: Biophysics, Biotechnology, Bioengineering, Biomedical Engineering, Biomaterials, Biochemistry
Keywords: Adiabatic, Bimodality, Genetic oscillator, Hysteresis, Multi-stability
Source: Scopus
Source ID: 84923240824

Research output: Contribution to journalArticleScientificpeer-review

Nanosatellite attitude estimation using Kalman-type filters with non-Gaussian noise

In order to control the orientation of a satellite, it is important to estimate the attitude accurately. Time series estimation is especially important in micro and nanosatellites, whose sensors are usually low-cost and have higher noise levels than high end sensors. Also, the algorithms should be able to run on systems with very restricted computer power. In this work, we evaluate five Kalman-type filtering algorithms for attitude estimation with 3-axis magnetometer and sun sensor measurements. The Kalman-type filters are selected so that each of them is designed to mitigate one error source for the unscented Kalman filter that is used as baseline. We investigate the distribution of the magnetometer noises and show that the Student's t-distribution is a better model for them than the Gaussian distribution. We consider filter responses in four operation modes: steady state, recovery from incorrect initial state, short-term sensor noise increment, and long-term increment. We find that a Kalman-type filter designed for Student's t sensor noises has the best combination of accuracy and computational speed for these problems, which leads to a conclusion that one can achieve more improvements in estimation accuracy by using a filter that can work with heavy tailed noise than by using a nonlinearity minimizing filter that assumes Gaussian noise.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Automation and Systems Theory, Istanbul Technical University
Contributors: Cilden-Guler, D., Raitoharju, M., Piche, R., Hajiyev, C.
Pages: 66-76
Publication date: Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Aerospace Science and Technology
Volume: 92
ISSN (Print): 1270-9638
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

New determination of the size and bulk density of binary asteroid 22 Kalliope from observations of mutual eclipses

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Descamps, P., Marchis, F., Pollock, J., Berthier, J., Vachier, F., Birlan, M., Kaasalainen, M., Harris, A., Wong, M., Romanishin, W., Cooper, E., Kettner, K., Wiggins, P., Kryszczynska, A., Polinska, M., Coliac, J., Devyatkin, A., Verestchagina, I., Gorshanov, D.
Pages: 578-600
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Icarus
Volume: 196
ISSN (Print): 0019-1035
Ratings: 
  • Scopus rating (2008): SJR 2.584 SNIP 1.21
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 12000

Research output: Contribution to journalArticleScientificpeer-review

New Insights for Relational Capital

In this paper, we concentrate on relational capital, manifestation of the old adage ”it is not what you know but who you know”. We propose that in this networked world, the importance of relationships between multiple stakeholders created by key personnel and financing becomes fundamental, and hence understanding and measuring those becomes fundamental, too. Accordingly, we highlight a need to go beyond social, individual or personal relationships and organizational context, as well as beyond the limitations of the dyadic (one actor to one actor) view on relationships. Hence, we are introducing the ecosystem as the context for measuring relational capital. This paper builds on a construct of ecosystemic relational capital, created for understanding and measuring the importance of relationships in the context of ecosystems. It looks at the totality of relationships both at organizational level and at individual level, measuring the structures and characteristics related to individuals, organizations as well as the ecosystem as a whole (Still et al. 2014a). We acknowledge that the initial framework emphasizes the “networking capabilities” element of relational capital, with less attention to the element of “customer loyalty and reputation”, which is the motivation for building on the construct. The processes of ecosystemic relational capital are built on the possibilities afforded by the volumes of digital data, mostly from social media, providing details on the relationships between various actors related to various regions, sectors, technologies and products. However, we propose enhancing the holistic integration for better understanding and measuring of relational capital with the application of methods of social network analysis (SNA), network visualizations and social media analytics. In this paper, we present concrete examples of the enhanced framework. At the same time, we acknowledge that there are many other avenues for obtaining novel insights for relational capital with these analytics, and we strongly encourage researchers and practitioners to do so.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Intelligent Information Systems Laboratory
Contributors: Still, K., Huhtamäki, J., Russell, M. G.
Number of pages: 16
Pages: 167-182
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Electronic Journal of Knowledge Management
Volume: 13
Issue number: 1
ISSN (Print): 1479-4411
Original language: English
Source: RIS
Source ID: urn:F9D7182C2BD28413A479A84749F380C0

Research output: Contribution to journalArticleScientificpeer-review

New insights on the binary asteroid 121 Hermione

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Descamps, P., Marchis, F., Durech, J., Emery, J., Harris, A., Kaasalainen, M., Berthier, J., Teng-Chuen-Yu, J., Peyrot, A., Hutton, L., Greene, J., Pollock, J., Assafin, M., Vieira-Martins, R., Camargo, J., Braga-Ribas, F., Vachier, F., Reichart, D., Ivarsen, K., Crain, J., Nysewander, M., Lacluyze, A., Haislip, J., Behrend, R., Colas, F., Lecaheux, J., Bernasconi, L., Roy, R., Baudouin, P., Brunetto, L., Sposetti, S., Manzini, F.
Pages: 88-101
Publication date: 2009
Peer-reviewed: Yes

Publication information

Journal: Icarus
Volume: 203
ISSN (Print): 0019-1035
Ratings: 
  • Scopus rating (2009): SJR 2.668 SNIP 1.348
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9900

Research output: Contribution to journalArticleScientificpeer-review

New photometric observations of asteroids (1862) Apollo and (25143) Itokawa - analysis of YORP effect

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., Weissman, P., Lowry, S., Beshore, E., Higgins, D., Krugly, Y., Shevchenko, V., Gaftonyuk, N., Choi, Y., Kowalski, R., Larson, S., Warner, B., Marshalkina, A., Ibrahimov, M., Molotov, I., Michalowski, T., Kitazato, K.
Pages: 345-350
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 488
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: 12022

Research output: Contribution to journalArticleScientificpeer-review

n-Fold implicative basic logic is Gödel 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: Turunen, E., Tchikapa, N., Lele, C.
Pages: 177-181
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Soft Computing
Volume: 16
Issue number: 1
ISSN (Print): 1432-7643
Ratings: 
  • Scopus rating (2012): CiteScore 1.94 SJR 0.747 SNIP 1.225
Original language: English

Bibliographical note

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

Source: researchoutputwizard
Source ID: 5464

Research output: Contribution to journalArticleScientificpeer-review

Nondestructive estimates of above-ground biomass using terrestrial laser scanning

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)
Contributors: Calders, K., Newnhamn, G., Burt, A., Murphy, S., Raumonen, P., Herold, M., Culvenor, D., Avitable, V., Disney, M., Armston, J., Kaasalainen, M.
Number of pages: 11
Pages: 198-208
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Methods in Ecology and Evolution
Volume: 6
Issue number: 2
ISSN (Print): 2041-210X
Ratings: 
  • Scopus rating (2015): CiteScore 7.61 SJR 5.436 SNIP 2.845
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-12-16<br/>Publisher name: Wiley-Blackwell Publishing

Source: researchoutputwizard
Source ID: 199

Research output: Contribution to journalArticleScientificpeer-review

Non-destructive tree volume estimation through quantitative structure modelling: Comparing UAV laser scanning with terrestrial LIDAR

Above-Ground Biomass (AGB) product calibration and validation require ground reference plots at hectometric scales to match space-borne missions' resolution. Traditional forest inventory methods that use allometric equations for single tree AGB estimation suffer from biases and low accuracy, especially when dealing with large trees. Terrestrial Laser Scanning (TLS) and explicit tree modelling show high potential for direct estimates of tree volume, but at the cost of time demanding fieldwork. This study aimed to assess if novel Unmanned Aerial Vehicle Laser Scanning (UAV-LS) could overcome this limitation, while delivering comparable results. For this purpose, the performance of UAV-LS in comparison with TLS for explicit tree modelling was tested in a Dutch temperate forest. In total, 200 trees with Diameter at Breast Height (DBH) ranging from 6 to 91 cm from 5 stands, including coniferous and deciduous species, have been scanned, segmented and subsequently modelled with TreeQSM. TreeQSM is a method that builds explicit tree models from laser scanner point clouds. Direct comparison with TLS derived models showed that UAV-LS reliably modelled the volume of trunks and branches with diameter ≥30 cm in the mature beech and oak stand with Concordance Correlation Coefficient (CCC) of 0.85 and RMSE of1.12 m3. Including smaller branch volume led to a considerable overestimation and decrease in correspondence to CCC of 0.51 and increase in RMSE to 6.59 m3. Denser stands prevented sensing of trunks and further decreased CCC to 0.36 in the Norway spruce stand. Also small, young trees posed problems by preventing a proper depiction of the trunk circumference and decreased CCC to 0.01. This dependence on stand indicated a strong impact of canopy structure on the UAV-LS volume modelling capacity. Improved flight paths, repeated acquisition flights or alternative modelling strategies could improve UAV-LS modelling performance under these conditions. This study contributes to the use of UAV-LS for fast tree volume and AGB estimation on scales relevant for satellite AGB product calibration and validation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Wageningen University and Research Centre, Universiteit Gent
Contributors: Brede, B., Calders, K., Lau, A., Raumonen, P., Bartholomeus, H. M., Herold, M., Kooistra, L.
Publication date: 1 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Remote Sensing of Environment
Volume: 233
Article number: 111355
ISSN (Print): 0034-4257
Original language: English
ASJC Scopus subject areas: Soil Science, Geology, Computers in Earth Sciences
Keywords: Above-Ground Biomass (AGB), Forest, Laser scanning, Quantitative Structure Model (QSM), UAV
Source: Scopus
Source ID: 85071628636

Research output: Contribution to journalArticleScientificpeer-review

Nonlinear iteration semigroups of fuzzy Cauchy problems

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Kaleva, O.
Number of pages: 7
Pages: 104-110
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

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

Source: researchoutputwizard
Source ID: 4388

Research output: Contribution to journalArticleScientificpeer-review

NP-completeness results for partitioning a graph into total dominating sets

A total domatic k-partition of a graph is a partition of its vertex set into k subsets such that each intersects the open neighborhood of each vertex. The maximum k for which a total domatic k-partition exists is known as the total domatic number of a graph G, denoted by dt(G). We extend considerably the known hardness results by showing it is[Formula presented]-complete to decide whether dt(G)≥3 where G is a bipartite planar graph of bounded maximum degree. Similarly, for every k≥3, it is[Formula presented]-complete to decide whether dt(G)≥k, where G is split or k-regular. In particular, these results complement recent combinatorial results regarding dt(G) on some of these graph classes by showing that the known results are, in a sense, best possible. Finally, for general n-vertex graphs, we show the problem is solvable in 2nnO(1) time, and derive even faster algorithms for special graph classes.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Helsinki
Contributors: Koivisto, M., Laakkonen, P., Lauri, J.
Publication date: 1 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: Theoretical Computer Science
ISSN (Print): 0304-3975
Ratings: 
  • Scopus rating (2018): CiteScore 1.23 SJR 0.494 SNIP 1.072
Original language: English
ASJC Scopus subject areas: Theoretical Computer Science, Computer Science(all)
Keywords: Combinatorics, Computational complexity, Graph theory, Total domatic number
Source: Scopus
Source ID: 85045701638

Research output: Contribution to journalArticleScientificpeer-review

Old and New Algorithms for Minimal Coverability Sets

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., Hansen, H.
Number of pages: 25
Pages: 1-25
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Fundamenta Informaticae
Volume: 131
Issue number: 1
ISSN (Print): 0169-2968
Ratings: 
  • Scopus rating (2014): CiteScore 1 SJR 0.48 SNIP 0.954
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2014-11-17<br/>Publisher name: IOS Press

Source: researchoutputwizard
Source ID: 1694

Research output: Contribution to journalArticleScientificpeer-review

On Computational Complexity Reduction Methods for Kalman Filter Extensions

The Kalman filter and its extensions are used in a vast number of aerospace and navigation applications for nonlinear state estimation of time series. In the literature, different approaches have been proposed to exploit the structure of the state and measurement models to reduce the computational demand of the algorithms. In this tutorial, we survey existing code optimization methods and present them using unified notation that allows them to be used with various Kalman filter extensions. We develop the optimization methods to cover a wider range of models, show how different structural optimizations can be combined, and present new applications for the existing optimizations. Furthermore, we present an example that shows that the exploitation of the structure of the problem can lead to improved estimation accuracy while reducing the computational load. This tutorial is intended for persons who are familiar with Kalman filtering and want to get insights for reducing the computational demand of different Kalman filter extensions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Automation and Systems Theory
Contributors: Raitoharju, M., Piche, R.
Number of pages: 18
Pages: 2-19
Publication date: 7 Oct 2019
Peer-reviewed: Yes

Publication information

Journal: IEEE Aerospace and Electronic Systems Magazine
Volume: 34
Issue number: 10
ISSN (Print): 0885-8985
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

On constructibility and unconstructibility of LTS operators from other LTS operators

An LTS operator can be constructed from a set of LTS operators up to an equivalence if and only if there is an LTS expression that only contains operators from the set and whose result is equivalent to the result of the operator. In this publication this idea is made precise in the context where each LTS has an alphabet of its own and the operators may depend on the alphabets. Then the extent to which LTS operators are constructible is studied. Most, if not all, established LTS operators have the property that each trace of the result arises from the execution of no more than one trace of each of its argument LTSs, and similarly for infinite traces. All LTS operators that have this property and satisfy some other rather weak regularity properties can be constructed from parallel composition and hiding up to the equivalence that compares the alphabets, traces, and infinite traces of the LTSs. Furthermore, a collection of other miscellaneous constructibility and unconstructibility results is presented.

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: 28
Pages: 207-234
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Acta Informatica
Volume: 52
Issue number: 2-3
ISSN (Print): 0001-5903
Ratings: 
  • Scopus rating (2015): CiteScore 0.76 SJR 0.421 SNIP 0.736
Original language: English
ASJC Scopus subject areas: Computer Networks and Communications, Information Systems, Software
Electronic versions: 
Source: Scopus
Source ID: 84925463574

Research output: Contribution to journalArticleScientificpeer-review

On finding rainbow and colorful paths

In the Colorful Path problem we are given a graph G=(V,E) and an arbitrary vertex coloring function c:V→[k]. The goal is to find a colorful path, i.e., a path on k vertices, that visits each color. This problem has been introduced in the classical work of Alon et al. (1995) [1], and the authors proposed a dynamic programming algorithm that runs in time 2knO(1) and uses O(2k) space. Since then the only progress obtained is reducing the space size to a polynomial at the cost of using randomization. In this work we show that a progress in time complexity is unlikely: if Colorful Path can be solved in time (2-ε)knO(1), then Set Cover admits a (2-ε')n(nm)O(1)-time algorithm. The same applies to other versions of the problem: when edges are colored instead of vertices, or we ask for a walk instead of a path, or when the requested path/walk has specified endpoints.We study also a second, very related problem. In Rainbow s t -Connectivity, we are given a k-edge-colored graph and two vertices s and t. The goal is to decide whether there is a rainbow path between s and t, that is, a path on which no color repeats. In its vertex variant (Rainbow Vertex s t -Connectivity) the input graph is k-vertex-colored, and a rainbow path is defined analogously. Uchizawa et al. (2011) [14] show that both variants can be solved in 2knO(1) time and exponential space. We show that the space size can be reduced to a polynomial, while keeping the same running time. In contrast to the polynomial space algorithm for Colorful Path, our algorithm for finding rainbow paths is deterministic.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, University of Warsaw
Contributors: Kowalik, Ł., Lauri, J.
Number of pages: 5
Pages: 110-114
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Theoretical Computer Science
Volume: 628
ISSN (Print): 0304-3975
Ratings: 
  • Scopus rating (2016): CiteScore 0.97 SJR 0.547 SNIP 0.968
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

On Fractional Ornstein-Uhlenbeck Process

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Kaarakka, T., Salminen, P.
Pages: 121-133
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Communications on Stochastic Analysis
Volume: 5
Issue number: 1
ISSN (Print): 0973-9599
Original language: English

Bibliographical note

ei ut-numeroa 22.3.2014<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6253

Research output: Contribution to journalArticleScientificpeer-review

On homomorphisms between products of median algebras

Homomorphisms of products of median algebras are studied with particular attention to the case when the codomain is a tree. In particular, we show that all mappings from a product (Formula presented.) of median algebras to a median algebra (Formula presented.) are essentially unary whenever the codomain (Formula presented.) is a tree. In view of this result, we also characterize trees as median algebras and semilattices by relaxing the defining conditions of conservative median algebras.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Université de Lorraine, TEI of Epirus
Contributors: Couceiro, M., Foldes, S., Meletiou, G. C.
Number of pages: 9
Pages: 545–553
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Algebra Universalis
Volume: 78
Issue number: 4
ISSN (Print): 0002-5240
Ratings: 
  • Scopus rating (2017): CiteScore 0.63 SJR 0.583 SNIP 1.038
Original language: English
ASJC Scopus subject areas: Algebra and Number Theory
Source: Scopus
Source ID: 85031922238

Research output: Contribution to journalArticleScientificpeer-review

On hypermonogenic functions

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Number of pages: 16
Pages: 975-990
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Complex Variables and Elliptic Equations
Volume: 58
Issue number: 7
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 14.9.2011.Poistettu Portfolio13:sta tuplat r=1850 ja r=1851.<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 2118

Research output: Contribution to journalArticleScientificpeer-review

On k-Hypermonogenic Functions and Their Mean Value Properties

We study a hyperbolic version of holomorphic functions to higher dimensions. In this frame work, a generalization of holomorphic functions are called (Formula presented.)-hypermonogenic functions. These functions are depending on several real variables and their values are in a Clifford algebra. They are defined in terms of hyperbolic Dirac operators. They are connected to harmonic functions with respect to the Riemannian metric (Formula presented.) in the same way as the usual harmonic function to holomorphic functions. We present the mean value property for (Formula presented.)-hypermonogenic functions and related results. Earlier the mean value properties has been proved for hypermonogenic functions. The key tools are the invariance properties of the hyperbolic metric.

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: 15
Pages: 311-325
Publication date: 2016
Peer-reviewed: Yes
Early online date: 8 Mar 2015

Publication information

Journal: Complex Analysis and Operator Theory
Volume: 10
Issue number: 2
ISSN (Print): 1661-8254
Ratings: 
  • Scopus rating (2016): CiteScore 0.57 SJR 0.554 SNIP 0.776
Original language: English
ASJC Scopus subject areas: Applied Mathematics, Computational Mathematics, Computational Theory and Mathematics
Keywords: Dirac operator, Hyperbolic metric, Hypermonogenic, Monogenic
Source: Scopus
Source ID: 84955725749

Research output: Contribution to journalArticleScientificpeer-review

Online tests of Kalman filter consistency

The normalised innovation squared (NIS) test, which is used to assess whether a Kalman filter's noise assumptions are consistent with realised measurements, can be applied online with real data, and does not require future data, repeated experiments or knowledge of the true state. In this work, it is shown that the NIS test is equivalent to three other model criticism procedures, which are as follows: (i) it can be derived as a Bayesian p-test for the prior predictive distribution; (ii) as a nested-model parameter significance test; and (iii) from a recently-proposed filter residual test. A new NIS-like test corresponding to a posterior predictive Bayesian p-test is presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research group: Positioning
Contributors: Piché, R.
Pages: 115–124
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of Adaptive Control and Signal Processing
Volume: 30
Issue number: 1
ISSN (Print): 0890-6327
Ratings: 
  • Scopus rating (2016): CiteScore 2.04 SJR 0.749 SNIP 1.026
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Electrical and Electronic Engineering, Signal Processing
Keywords: Kalman filter, Model consistency, Normalised innovations squared, Predictive distribution
Electronic versions: 
Source: Scopus
Source ID: 84954027695

Research output: Contribution to journalArticleScientificpeer-review

On the complexity of rainbow coloring problems

An edge-colored graph G is said to be rainbow connected if between each pair of vertices there exists a path which uses each color at most once. The rainbow connection number , denoted by rc(G), is the minimum number of colors needed to make G rainbow connected. Along with its variants, which consider vertex colorings and/or so-called strong colorings, the rainbow connection number has been studied from both the algorithmic and graph-theoretic points of view.

In this paper we present a range of new results on the computational complexity of computing the four major variants of the rainbow connection number. In particular, we prove that the Strong Rainbow Vertex Coloring problem is View the MathML source-complete even on graphs of diameter 3, and also when the number of colors is restricted to 2. On the other hand, we show that if the number of colors is fixed then all of the considered problems can be solved in linear time on graphs of bounded treewidth. Moreover, we provide a linear-time algorithm which decides whether it is possible to obtain a rainbow coloring by saving a fixed number of colors from a trivial upper bound. Finally, we give a linear-time algorithm for computing the exact rainbow connection numbers for three variants of the problem on graphs of bounded vertex cover number.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, TU Vienna
Contributors: Eiben, E., Ganian, R., Lauri, J.
Pages: 38-48
Publication date: Sep 2018
Peer-reviewed: Yes
Early online date: 2016

Publication information

Journal: Discrete Applied Mathematics
Volume: 246
ISSN (Print): 0166-218X
Ratings: 
  • Scopus rating (2018): CiteScore 1.2 SJR 0.815 SNIP 1.263
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

On the complexity of restoring corrupted colorings

In the r-Fix problem, we are given a graph G, a (non-proper) vertex-coloring c: V(G) → [r] , and a positive integer k. The goal is to decide whether a proper r-coloring c is obtainable from c by recoloring at most k vertices of G. Recently, Junosza-Szaniawski et al. (in: SOFSEM 2015: theory and practice of computer science, Springer, Berlin, 2015) asked whether the problem has a polynomial kernel parameterized by the number of recolorings k. In a full version of the manuscript, the authors together with Garnero and Montealegre, answered the question in the negative: for every r≥ 3 , the problem r-Fix does not admit a polynomial kernel unless [InlineEquation not available: see fulltext.]. Independently of their work, we give an alternative proof of the theorem. Furthermore, we study the complexity of r-Swap, where the only difference from r-Fix is that instead of k recolorings we have a budget of k color swaps. We show that for every r≥ 3 , the problem r-Swap is [InlineEquation not available: see fulltext.]-hard whereas r-Fix is known to be FPT. Moreover, when r is part of the input, we observe both Fix and Swap are [InlineEquation not available: see fulltext.]-hard parameterized by the treewidth of the input graph. We also study promise variants of the problems, where we are guaranteed that a proper r-coloring c is indeed obtainable from c by some finite number of swaps. For instance, we prove that for r= 3 , the problems r-Fix-Promise and r-Swap-Promise are [InlineEquation not available: see fulltext.]-hard for planar graphs. As a consequence of our reduction, the problems cannot be solved in 2o(n) time unless the Exponential Time Hypothesis fails.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Bell Labs
Contributors: De Biasi, M., Lauri, J.
Number of pages: 20
Pages: 1150-1169
Publication date: May 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Combinatorial Optimization
Volume: 37
Issue number: 4
ISSN (Print): 1382-6905
Original language: English
ASJC Scopus subject areas: Computer Science Applications, Discrete Mathematics and Combinatorics, Control and Optimization, Computational Theory and Mathematics, Applied Mathematics
Keywords: Combinatorial reconfiguration, Computational complexity, Graph coloring, Local search, Parameterized complexity
Source: Scopus
Source ID: 85053264976

Research output: Contribution to journalArticleScientificpeer-review

On the Discrete-Time Regulator Problem in Infinite-Dimensional Spaces

The linear, discrete-time regulator problem is considered in infinite-dimensional spaces without posing in advance any positivity conditions on quadratic criterion. The convergence of the finite-time optimum solution is studied, when time increases to infinity with a stable, stabilizable, and detectable system.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electrical Engineering
Contributors: Pohjolainen, S. A.
Number of pages: 9
Pages: 319-327
Publication date: 1980
Peer-reviewed: Yes

Publication information

Journal: Journal of Optimization Theory and Applications
Volume: 30
Issue number: 2
ISSN (Print): 0022-3239
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

On the distribution of coefficients of powers of positive polynomials

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Major, L.
Pages: 239-243
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Australasian Journal of Combinatorics
Volume: 49
ISSN (Print): 1034-4942
Ratings: 
  • Scopus rating (2011): CiteScore 0.28 SJR 0.414 SNIP 0.685
Original language: English

Bibliographical note

ei ut-numeroa 5.4.2014<br/>Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6694

Research output: Contribution to journalArticleScientificpeer-review

On the fine-grained complexity of rainbow coloring

The Rainbow k-Coloring problem asks whether the edges of a given graph can be colored in k colors so that every pair of vertices is connected by a rainbow path, i.e., a path with all edges of different colors. Our main result states that for any k ≥ 2, there is no algorithm for Rainbow k-Coloring running in time 2o(n 3/2), unless the exponential time hypothesis fails. Motivated by this negative result we consider two parameterized variants of the problem. In the Subset Rainbow k-Coloring problem, introduced by Chakraborty et al. [J. Comb. Optim., 21 (2009), pp. 330-347], we are additionally given a set S of pairs of vertices and we ask if there is a coloring in which all the pairs in S are connected by rainbow paths. We show that Subset Rainbow k-Coloring is fixed parameter tractable (FPT) when parameterized by |S|. We also study the Maximum Rainbow k-Coloring problem, where we are additionally given an integer q, and we ask if there is a coloring in which at least q anti-edges are connected by rainbow paths. We show that the problem is FPT when parameterized by q and has a kernel of size O(q) for every k ≥ 2, extending the result of Ananth, Nasre, and Sarpatwar, in FSTTCS, LIPIcs, Schloss Dagstuhl-Leibniz-Zentum für Informatik, Dagstuhl, Germany, 2011, pp. 241-251. We believe that our techniques used for the lower bounds may shed some light on the complexity of the classical Edge Coloring problem, where it is a major open question if a 2O(n)-time algorithm exists.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, University of Warsaw, Institute of Informatics, Bell Labs
Contributors: Kowalik, L., Lauri, J., La, A. S.
Number of pages: 34
Pages: 1672-1705
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: SIAM Journal on Discrete Mathematics
Volume: 32
Issue number: 3
ISSN (Print): 0895-4801
Ratings: 
  • Scopus rating (2018): CiteScore 1.07 SJR 0.958 SNIP 1.221
Original language: English
ASJC Scopus subject areas: Mathematics(all)
Keywords: Computational complexity, FPT algorithms, Graph coloring, Lower bounds
Source: Scopus
Source ID: 85053925686

Research output: Contribution to journalArticleScientificpeer-review

On the spectral and Frobenius norm of a generalized Fibonacci r-circulant matrix

Consider the recursion g0 = a, g1 = b, gn = gn-1 + gn-2, n = 2, 3, . . . . We compute the Frobenius norm of the r-circulant matrix corresponding to g0, . . . , gn-1. We also give three lower bounds (with equality conditions) for the spectral norm of this matrix. For this purpose, we present three ways to estimate the spectral norm from below in general.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Lulea University of Technology
Contributors: Merikoski, J. K., Haukkanen, P., Mattila, M., Tossavainen, T.
Number of pages: 14
Pages: 23-36
Publication date: 1 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: Special Matrices
Volume: 6
Issue number: 1
ISSN (Print): 2300-7451
Ratings: 
  • Scopus rating (2018): CiteScore 0.64 SJR 0.408 SNIP 1.005
Original language: English
ASJC Scopus subject areas: Algebra and Number Theory, Geometry and Topology
Keywords: Euclidean norm, Frobenius norm, generalized Fibonacci numbers, r-circulant matrix, spectral norm
Electronic versions: 
Source: Scopus
Source ID: 85042290997

Research output: Contribution to journalArticleScientificpeer-review

On the Structure of Octonion Regular Functions

In this paper, we study octonion regular functions and the structural differences between regular functions in octonion, quaternion, and Clifford analyses.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Civil Engineering
Contributors: Kauhanen, J., Orelma, H.
Number of pages: 17
Publication date: Sep 2019
Peer-reviewed: Yes
Early online date: 2 Aug 2019

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 29
Issue number: 4
Article number: 77
ISSN (Print): 0188-7009
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

On the Succinctness of Atoms of Dependency

Propositional team logic is the propositional analog to first-order team logic. Non-classical atoms of dependence, independence, inclusion, exclusion and anonymity can be expressed in it, but for all atoms except dependence only exponential translations are known. In this paper, we systematically compare their succinctness in the existential fragment, where the splitting disjunction only occurs positively, and in full propositional team logic with unrestricted negation. By introducing a variant of the Ehrenfeucht-Fra\"{i}ssé game called formula size game into team logic, we obtain exponential lower bounds in the existential fragment for all atoms. In the full fragment, we present polynomial upper bounds also for all atoms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Leibniz-Universität Hannover
Contributors: Vilander, M., Lück, M.
Number of pages: 28
Pages: 17:1-17:28
Publication date: 20 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Logical Methods in Computer Science
Volume: 15
Issue number: 3
ISSN (Print): 1860-5974
Original language: English
ASJC Scopus subject areas: Logic, Computational Theory and Mathematics
Keywords: team semantics, succinctness, dependence atom

Research output: Contribution to journalArticleScientificpeer-review

On the Underlying Mathematical and Quantum Structure of Quantum Cryptography

Quantum cryptography is a novel approach to provide secure communication, based on the laws of physics. It offers perfect security for the communication between two authorized parties, while assuming very high computational capacity for the eavesdropper, who may be attempting to intrude into this communication. It provides a very high rate of intrusion detection as against the classical systems. Classical cryptography is built on a fundamental assumption that it is difficult to invert some of mathematical functions, in a limited time, with the use of efficient computing resources. While, quantum cryptography is based on formidable laws of nature, making it less prone to attack. With the advent of quantum computing, boundaries between various subjects like quantum physics, computer science and mathematics are getting reduced. In the early seventies, Steven Wiesner made pioneering efforts in the field Quantum Cryptography. In its present form, Quantum Cryptography depends on two essential principles of Quantum Mechanics. One is that no information is available without causing disturbance in the system and other is Principle of No-Cloning. In this paper we present some of fundamental aspects of Quantum Cryptography and the underlying structures that makes it a credible option for providing perfect security of information.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Gotkhindikar, A. D.
Pages: 15685-15699
Publication date: Feb 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of Engineering and Computer Science
Volume: 5
Issue number: 2
ISSN (Print): 2319-7242
Original language: English
Source: Bibtex
Source ID: urn:7250acb0df8a579e30de45499bead3c2

Research output: Contribution to journalArticleScientificpeer-review

On Vekua Systems and Their Connections to Hyperbolic Function Theory in the Plane

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Eriksson, S., Orelma, H.
Number of pages: 12
Pages: 1027-1038
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Advances in Applied Clifford Algebras
Volume: 24
Issue number: 4
ISSN (Print): 0188-7009
Ratings: 
  • Scopus rating (2014): CiteScore 0.56 SJR 0.304 SNIP 0.687
Original language: English

Bibliographical note

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

Source: researchoutputwizard
Source ID: 286

Research output: Contribution to journalArticleScientificpeer-review

Optical properties of snow in backscatter

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Kaasalainen, S., Kaasalainen, M., Mielonen, T., Suomalainen, J., Peltoniemi, J., Näränen, J.
Pages: 574-584
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Journal of Glaciology
Volume: 52
Issue number: 179
ISSN (Print): 0022-1430
Ratings: 
  • Scopus rating (2006): SJR 1.237 SNIP 0.967
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 16574

Research output: Contribution to journalArticleScientificpeer-review

Optimal computation of brightness integrals parametrized on the unit sphere

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., Lu, X., Vänttinen, A.
Pages: 7
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 539
Article number: A96
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: 4377

Research output: Contribution to journalArticleScientificpeer-review

Optimal energy decay for the wave-heat system on a rectangular domain

We study the rate of energy decay for solutions of a coupled wave-heat system on a rectangular domain. Using techniques from the theory of C 0 -semigroups, and in particular a well-known result due to Borichev and Tomilov, we prove that the energy of classical solutions decays like t - 2/ 3 as t \rightarrow \infty . This rate is moreover shown to be sharp. Our result implies in particular that a general estimate in the literature, which predicts at least logarithmic decay and is known to be best possible in general, is suboptimal in the special case under consideration here. Our strategy of proof involves direct estimates based on separation of variables and a refined version of the technique developed in our earlier paper for a one-dimensional wave-heat system.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, St Giles
Contributors: Batty, C., Paunonen, L., Seifert, D.
Number of pages: 12
Pages: 808-819
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: SIAM JOURNAL ON MATHEMATICAL ANALYSIS
Volume: 51
Issue number: 2
ISSN (Print): 0036-1410
Original language: English
ASJC Scopus subject areas: Analysis, Computational Mathematics, Applied Mathematics
Keywords: C -semigroups, Coupled, Energy, Heat equation, Rates of decay, Rectangular domain, Resolvent estimates, Wave equation
Source: Scopus
Source ID: 85065492247

Research output: Contribution to journalArticleScientificpeer-review

Optimal energy decay in a one-dimensional coupled wave–heat system

We study a simple one-dimensional coupled wave–heat system and obtain a sharp estimate for the rate of energy decay of classical solutions. Our approach is based on the asymptotic theory of C0-semigroups and in particular on a result due to Borichev and Tomilov (Math Ann 347:455–478, 2010), which reduces the problem of estimating the rate of energy decay to finding a growth bound for the resolvent of the semigroup generator. This technique not only leads to an optimal result, it is also simpler than the methods used by other authors in similar situations.

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: Batty, C., Paunonen, L., Seifert, D.
Number of pages: 16
Pages: 649–664
Publication date: Sep 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Evolution Equations
Volume: 16
Issue number: 3
ISSN (Print): 1424-3199
Ratings: 
  • Scopus rating (2016): CiteScore 0.9 SJR 1.356 SNIP 1.051
Original language: English
ASJC Scopus subject areas: Mathematics (miscellaneous)
Keywords: C-semigroups, Coupled, Energy, Heat equation, Rates of decay, Resolvent estimates, Wave equation
Electronic versions: 
Source: Scopus
Source ID: 84954191330

Research output: Contribution to journalArticleScientificpeer-review

Optimization of large-area OLED current distribution grids with self-aligned passivation

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Department of Physics, Department of Mathematics, Augmented Human Activities (AHA), Mathematical modelling with wide societal impact (MathImpact)
Contributors: Janka, M., Saukko, E., Raumonen, P., Lupo, D.
Number of pages: 8
Pages: 3431-3438
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Organic Electronics
Volume: 15
Issue number: 12
ISSN (Print): 1566-1199
Ratings: 
  • Scopus rating (2014): CiteScore 3.85 SJR 1.346 SNIP 1.2
Original language: English

Bibliographical note

Contribution: organisation=elt,FACT1=0.8<br/>Contribution: organisation=fys,FACT2=0.1<br/>Contribution: organisation=mat,FACT3=0.1<br/>Portfolio EDEND: 2014-11-11<br/>Publisher name: Elsevier BV

Source: researchoutputwizard
Source ID: 571

Research output: Contribution to journalArticleScientificpeer-review

Orbiter-to-orbiter tomography: a potential approach for small solar system bodies

The goal of this paper is to advance mathematical and computational methodology for orbiter-to-orbiter radio tomography of small solar system bodies. In this study, an advanced full waveform forward model is coupled with a total variation-based inversion technique. We use a satellite formation model in which a single unit receives a signal that is transmitted by one or more transponder satellites. Numerical results for a two-dimensional domain are presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics, Research group: MAT Inverse Problems
Contributors: Pursiainen, S., Kaasalainen, M.
Pages: 2747-2759
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Aerospace and Electronic Systems
Volume: 52
Issue number: 6
ISSN (Print): 0018-9251
Ratings: 
  • Scopus rating (2016): CiteScore 2.89 SJR 0.742 SNIP 1.918
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Paraconsistent Many-Valued Logic in GUHA Framework

The primary aim of this paper is to establish a formal connection between a particular many-valued paraconsistent logic and the logic of a KDD method, namely the GUHA data mining method by introducing a new quantifier called Paraconsistent Separation quantifier. This quantifier is implemented to LISp-Miner Software. The secondary aim is to demonstrate a possible usefulness of this quantifier in social and other applied sciences by examples taking from family planning context.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Research group: Computer Science and Applied Logics
Contributors: Turunen, E.
Number of pages: 8
Pages: 104-111
Publication date: 3 May 2018
Peer-reviewed: Yes

Publication information

Journal:  Acta Informatica Pragensia, University of Economics, Prague
Volume: 7
Issue number: 1
ISSN (Print): 1805-4951
Original language: English

Research output: Contribution to journalArticleScientificpeer-review

Paraconsistent semantics for Pavelka style fuzzy sentential logic

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Turunen, E., Özturkb, M., Tsoukisc, A.
Pages: 1926-1940
Publication date: 2010
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
Volume: 161
Issue number: 14
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2010): SJR 1.274 SNIP 2.111
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 9451

Research output: Contribution to journalArticleScientificpeer-review

Partitioned Update Kalman Filter

In this paper we present a new Kalman filter extension for state update called Partitioned Update Kalman Filter (PUKF). PUKF updates state using multidimensional measurements in parts. PUKF evaluates the nonlinearity of the measurement function within Gaussian prior by comparing the innovation covariance caused by the second order linearization to the Gaussian measurement noise. A linear transformation is applied to measurements to minimize the nonlinearity of a part of the measurement. The measurement update is applied then using only the part of the measurement that has low nonlinearity and the process is then repeated for the updated state using the remaining part of the transformed measurement until the whole measurement has been used. PUKF does the linearizations numerically and no analytical differentiation is required. Results show that when measurement geometry allows effective partitioning, the proposed algorithm improves estimation accuracy and produces accurate covariance estimates.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research area: Dynamic Systems, Department of Mathematics, Research group: MAT Positioning, Research group: Positioning
Contributors: Raitoharju, M., Piché, R., Ala-Luhtala, J., Ali-Löytty, S.
Number of pages: 12
Pages: 3-14
Publication date: Jun 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Advances in Information Fusion
Volume: 11
Issue number: 1
ISSN (Print): 1557-6418
Ratings: 
  • Scopus rating (2016): CiteScore 1.42 SJR 0.213 SNIP 1.171
Original language: English

Bibliographical note

ORG=ase,0.75 ORG=mat,0.25

Source: ArXiv
Source ID: http://arxiv.org/abs/1503.02857v1

Research output: Contribution to journalArticleScientificpeer-review

Pedagogical experiments with MathCheck in university teaching

MathCheck is a relatively new online tool that gives students feedback on their solutions to elementary university mathematics and theoretical computer science exercises. MathCheck was designed with constructivism learning theory in mind and it differs from other online tools as it checks the solutions step by step and shows a counter-example if the step is incorrect. It has been in student use since the autumn of 2015 and under design-based research from the first online day. The main research questions of this study are the following. 1) How can the usage of MathCheck support the aspects of conceptual understanding and procedural fluency of constructivism learning? 2) How can MathCheck empower both students and teachers in the education of mathematics? This paper presents the results of five pedagogical experiments considering both students’ and teachers’ point of views. In each experiment, the students have suggested improvements, which have affected the further development of MathCheck. In general, both students and teachers have given positive feedback on MathCheck. MathCheck seems to support learning better than tools that only provide the “incorrect”/“correct” verdict after checking the answer. MathCheck is suitable for independent studying as well as an addition to traditional lectures. In the best case, it can reduce teachers’ workload during courses.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Norwegian Defence University College, Jyväskylän yliopisto
Contributors: Kaarakka, T., Helkala, K., Valmari, A., Joutsenlahti, M.
Number of pages: 29
Pages: 84-112
Publication date: 16 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Lumat
Volume: 7
Issue number: 3
ISSN (Print): 2323-7112
Original language: English
ASJC Scopus subject areas: Education
Keywords: Education, MathCheck, Mathematics, Pedagogy
Source: Scopus
Source ID: 85077989152

Research output: Contribution to journalArticleScientificpeer-review

Perfect Pavelka Logic

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: Turunen, E., Navara, M.
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Fuzzy Sets and Systems
ISSN (Print): 0165-0114
Ratings: 
  • Scopus rating (2015): CiteScore 2.34 SJR 1.354 SNIP 1.797
Original language: English

Bibliographical note

In Press.Siirretään Portfolio15<br/>Contribution: organisation=mat,FACT1=1<br/>Portfolio EDEND: 2015-01-08<br/>Publisher name: Elsevier BV

Source: researchoutputwizard
Source ID: 35

Research output: Contribution to journalArticleScientificpeer-review

Periodic Output Regulation for Distributed Parameter Systems

In this paper the output regulation of a linear distributed parameter system with a nonautonomous periodic exosystem is considered. It is shown that the solvability of the output regulation problem can be characterized by the solvability of a certain constrained infinite-dimensional Sylvester differential equation. Conditions are given for the existence of feedforward and feedback controllers solving the regulation problem along with a method for their construction. The theoretical results are applied to output regulation of a controlled delay equation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Paunonen, L., Pohjolainen, S.
Pages: 403-441
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Mathematics of Control Signals and Systems
Volume: 24
Issue number: 4
ISSN (Print): 0932-4194
Ratings: 
  • Scopus rating (2012): CiteScore 0.69 SJR 0.626 SNIP 0.849
Original language: Finnish

Bibliographical note

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

Source: researchoutputwizard
Source ID: 5029

Research output: Contribution to journalArticleScientificpeer-review

Perturbation of strongly and polynomially stable Riesz-spectral operators

In this paper we consider bounded and relatively bounded finite rank perturbations of a Riesz-spectral operator generating a polynomially stable semigroup of linear operators on a Hilbert space. We concentrate on a commonly encountered situation where the spectrum of the unperturbed operator is contained in the open left half-plane of the complex plane and approaches the imaginary axis asymptotically. We present conditions on the perturbing operator such that the spectrum of the perturbed operator is contained in the open left half-plane of the complex plane and additional conditions for the strong and polynomial stabilities of the perturbed semigroup. We consider two applications of the perturbation results. In the first example we apply the results to the perturbation of a polynomially stabilized one-dimensional wave equation. In the second example we consider perturbation of a closed-loop system consisting of a distributed parameter system and an observer-based feedback controller solving the robust output regulation problem related to an infinite-dimensional signal generator.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mathematics
Contributors: Paunonen, L.
Pages: 234-248
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Systems and Control Letters
Volume: 60
Issue number: 4
ISSN (Print): 0167-6911
Ratings: 
  • Scopus rating (2011): CiteScore 2.58 SJR 2.148 SNIP 1.943
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 6975

Research output: Contribution to journalArticleScientificpeer-review

Photometry and models of selected main-belt asteroids (II)

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Michalowski, T., Kaasalainen, M., Marciniak, A., Denchev, P., Kwiatkowski, T., Kryszczynska, A., Hirsch, R., Velichko, F., Erikson, A., Szabo, G., Kowalski, R.
Pages: 329-335
Publication date: 2005
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 443
Issue number: 1
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2005): SJR 3.265 SNIP 1.329
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 19117

Research output: Contribution to journalArticleScientificpeer-review

Photometry and models of selected main-belt asteroids. III

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Michalowski, T., Kaasalainen, M., Polinska, M., Marciniak, A., Kwiatkowski, A., Kryszczynska, A., Velichko, F.
Pages: 663-668
Publication date: 2006
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 459
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: 17117

Research output: Contribution to journalArticleScientificpeer-review

Photometry and models of selected main-belt asteroids. IV

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Marciniak, A., Michalowski, T., Kaasalainen, M., Durech, J., Polinska, M., Kwiatkowski, T., Kryszczynska, A., Hirsch, R., Kaminski, K., Fagas, M., Colas, F., Fauvaud, S., Santacana, G., Behrend, R., Ro, R.
Pages: 633-639
Publication date: 2007
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 473
ISSN (Print): 0004-6361
Ratings: 
  • Scopus rating (2007): SJR 2.861 SNIP 1.342
Original language: English

Bibliographical note

Contribution: organisation=mat,FACT1=1

Source: researchoutputwizard
Source ID: 15045

Research output: Contribution to journalArticleScientificpeer-review

Photometry and models of selected main-belt asteroids. V.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Former organisation of the author
Contributors: Marciniak, A., Michalowski, T., Kaasalainen, M., Kryszczynska, A., Kwiatkowski, T., Hirsch, R., Kaminski, K., Fagas, M., Polinska, M., Velichko, F., Michalowski, M., Snodgrass, C., Behrend, R., Bernasconi, L.
Pages: 559-565
Publication date: 2008
Peer-reviewed: Yes

Publication information

Journal: Astronomy and Astrophysics
Volume: 478
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: 12978

Research output: Contribution to journalArti