1D Convolutional Neural Networks (CNNs) have recently become the state-of-the-art technique for crucial signal processing applications such as patient-specific ECG classification, structural health monitoring, anomaly detection in power electronics circuitry and motor-fault detection. This is an expected outcome as there are numerous advantages of using an adaptive and compact 1D CNN instead of a conventional (2D) deep counterparts. First of all, compact 1D CNNs can be efficiently trained with a limited dataset of 1D signals while the 2D deep CNNs, besides requiring 1D to 2D data transformation, usually need datasets with massive size, e.g., in the »Big Data» scale in order to prevent the well-known »overfitting» problem. 1D CNNs can directly be applied to the raw signal (e.g., current, voltage, vibration, etc.) without requiring any pre- or post-processing such as feature extraction, selection, dimension reduction, denoising, etc. Furthermore, due to the simple and compact configuration of such adaptive 1D CNNs that perform only linear 1D convolutions (scalar multiplications and additions), a real-time and low-cost hardware implementation is feasible. This paper reviews the major signal processing applications of compact 1D CNNs with a brief theoretical background. We will present their state-of-the-art performances and conclude with focusing on some major properties. Keywords - 1-D CNNs, Biomedical Signal Processing, SHM.
EXT="Kiranyaz, Serkan"
EXT="Ince, Turker"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Agile methods increase the speed and reduce the cost of software projects; however, they have been criticized for lack of documentation, traditional quality control, and, most importantly, lack of security assurance - mostly due to their informal and self-organizing approach to software development. This paper clarifies the requirements for security assurance by using an evaluation framework to analyze the compatibility of established agile security development methods: XP, Scrum and Kanban, combined with Microsoft SDL security framework, against Finland's established national security regulation (Vahti). We also analyze the selected methods based on their role definitions, and provide some avenues for future research.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we present a computational approach for finding complete graph invariants. Specifically, we generate exhaustive sets of connected, non-isomorphic graphs with 9 and 10 vertices and demonstrate that a 97-dimensional multivariate graph invariant is capable to distinguish each of the non-isomorphic graphs. Furthermore, in order to tame the computational complexity of the problem caused by the vast number of graphs, e.g., involving over 10 million networks with 10 vertices, we suggest a low-dimensional, iterative procedure that is based on highly discriminative individual graph invariants. We show that also this computational approach leads to a perfect discrimination. Overall, our numerical results prove the existence of such graph invariants for networks with 9 and 10 vertices. Furthermore, we show that our iterative approach has a polynomial time complexity.
Research output: Contribution to journal › Article › Scientific › peer-review
This paper presents a novel application of convolutional neural networks (CNNs) for the task of acoustic scene classification (ASC). We here propose the use of a CNN trained to classify short sequences of audio, represented by their log-mel spectrogram. We also introduce a training method that can be used under particular circumstances in order to make full use of small datasets. The proposed system is tested and evaluated on three different ASC datasets and compared to other state-of-the-art systems which competed in the 'Detection and Classification of Acoustic Scenes and Events' (DCASE) challenges held in 20161 and 2013. The best accuracy scores obtained by our system on the DCASE 2016 datasets are 79.0% (development) and 86.2% (evaluation), which constitute a 6.4% and 9% improvements with respect to the baseline system. Finally, when tested on the DCASE 2013 evaluation dataset, the proposed system manages to reach a 77.0% accuracy, improving by 1% the challenge winner's score.
jufoid=58177
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Today's dominant design for the Internet of Things (IoT) is a Cloud-based system, where devices transfer their data to a back-end and in return receive instructions on how to act. This view is challenged when delays caused by communication with the back-end become an obstacle for IoT applications with, for example, stringent timing constraints. In contrast, Fog Computing approaches, where devices communicate and orchestrate their operations collectively and closer to the origin of data, lack adequate tools for programming secure interactions between humans and their proximate devices at the network edge. This paper fills the gap by applying Action-Oriented Programming (AcOP) model for this task. While originally the AcOP model was proposed for Cloud-based infrastructures, presently it is re-designed around the notion of coalescence and disintegration, which enable the devices to collectively and autonomously execute their operations in the Fog by serving humans in a peer-to-peer fashion. The Cloud's role has been minimized—it is being leveraged as a development and deployment platform.
EXT="Mäkitalo, Niko"
EXT="Mikkonen, Tommi"
Research output: Contribution to journal › Article › Scientific › peer-review
Networking devices such as switches and routers have traditionally had fixed functionality. They have the logic for the union of network protocols matching the application and market segment for which they have been designed. Possibility of adding new functionality is limited. One of the aims of Software Defined Networking is to make packet processing devices programmable. This provides for innovation and rapid deployment of novel networking protocols. The first step in processing of packets is packet parsing. In this paper, we present a custom processor for packet parsing. The parser is protocol-independent and can be programmed to parse any sequence of headers. It does so without the use of a Ternary Content Addressable Memory. As a result, the area and power consumption are noticeably smaller than in the state of the art. Moreover, its output is the same as that of the parser used in the Reconfigurable Match Tables (RMT). With an area no more than that of parsers in the RMT architecture, it sustains aggregate throughput of 3.4 Tbps in the worst case which is an improvement by a factor of 5.
Research output: Contribution to journal › Article › Scientific › peer-review
Deep learning models are capable of achieving state-of-the-art performance on a wide range of time series analysis tasks. However, their performance crucially depends on the employed normalization scheme, while they are usually unable to efficiently handle non-stationary features without first appropriately pre-processing them. These limitations impact the performance of deep learning models, especially when used for forecasting financial time series, due to their non-stationary and multimodal nature. In this paper we propose a data-driven adaptive normalization layer which is capable of learning the most appropriate normalization scheme that should be applied on the data. To this end, the proposed method first identifies the distribution from which the data were generated and then it dynamically shifts and scales them in order to facilitate the task at hand. The proposed nor-malization scheme is fully differentiable and it is trained in an end-to-end fashion along with the rest of the parameters of the model. The proposed method leads to significant performance improvements over several competitive normalization approaches, as demonstrated using a large-scale limit order book dataset.
EXT="Tefas, Anastasios"
EXT="Iosifidis, Alexandros"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
One approach for stereoscopic video compression is to down sample the content prior to encoding and up sample it to the original spatial resolution after decoding. In this study it is shown that the ratio by which the content should be rescaled is sequence dependent. Hence, a frequency based method is introduced enabling fast and accurate estimation of the best down sampling ratio for different stereoscopic video clips. It is shown that exploiting this approach can bring 3.38% delta bitrate reduction over five camera-captured sequences.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we provide a novel dataset designed for camera independent color constancy research. Camera independence corresponds to the robustness of an algorithm’s performance when run on images of the same scene taken by different cameras. Accordingly, the images in our database correspond to several lab and field scenes each of which is captured by three different cameras with minimal registration errors. The lab scenes are also captured under five different illuminations. The spectral responses of cameras and the spectral power distributions of the lab light sources are also provided, as they may prove beneficial for training future algorithms to achieve color constancy. For a fair evaluation of future methods, we provide guidelines for supervised methods with indicated training, validation and testing partitions. Accordingly, we evaluate two recently proposed convolutional neural network based color constancy algorithms as baselines for future research. As a side contribution, this dataset also includes images taken by a mobile camera with color shading corrected and uncorrected results. This allows research on the effect of color shading as well.
Research output: Contribution to journal › Article › Scientific › peer-review
The task of additional lossless compression of JPEG images is considered. We propose to decode JPEG image and recompress it using lossy BPG (Better Portable Graphics) codec based on a subset of the HEVC open video compression standard. Then the decompressed and smoothed BPG image is used for calculation and quantization of DCT coefficients in 8x8 image blocks using quantization tables of the source JPEG image. A difference between obtained quantized DCT coefficients and quantized DCT coefficients of the source JPEG image (prediction error) is calculated. The difference is lossless compressed by a proposed context modeling and arithmetical coding. In this way the source JPEG image is replaced by two files: compressed BPG image and the compressed difference which needed for lossless restoration of the source JPEG image. It is shown that the proposed approach provides compression ratios comparable with state of the art PAQ8, WinZip and STUFFIT file archivers. At the same time BPG images may be used for fast preview of compressed JPEG images.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Heterogeneous computing platforms with multicore central processing units (CPUs) and graphics processing units (GPUs) are of increasing interest to designers of embedded signal processing systems since they offer the potential for significant performance boost while maintaining the flexibility of software-based design flows. Developing optimized implementations for CPU-GPU platforms is challenging due to complex, inter-related design issues, including task scheduling, interprocessor communication, memory management, and modeling and exploitation of different forms of parallelism. In this paper, we present an automated, dataflow based, design framework called DIF-GPU for application mapping and software synthesis on heterogeneous CPU-GPU platforms. DIF-GPU is based on novel extensions to the dataflow interchange format (DIF) package, which is a software environment for developing and experimenting with dataflow-based design methods and synthesis techniques for embedded signal processing systems. DIF-GPU exploits multiple forms of parallelism by deeply incorporating efficient vectorization and scheduling techniques for synchronous dataflow specifications, and incorporating techniques for streamlining interprocessor communication. DIF-GPU also provides software synthesis capabilities to help accelerate the process of moving from high-level application models to optimized implementations.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Design and implementation of smart vision systems often involve the mapping of complex image processing algorithms into efficient, real-time implementations on multicore platforms. In this paper, we describe a novel design tool that is developed to address this important challenge. A key component of the tool is a new approach to hierarchical dataflow scheduling that integrates a global scheduler and multiple local schedulers. The local schedulers are lightweight modules that work independently. The global scheduler interacts with the local schedulers to optimize overall memory usage and execution time. The proposed design tool is demonstrated through a case study involving an image stitching application for large scale microscopy images.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper introduces the AIE-Studio (Audio Interfaces for Exploration), a modular dataflow patching library implemented with Pure Data. The AIE-Studio introduces new tools for procedural sound design through generative sonic and musical structures. Particular focus is on aesthetic experience. The designed modules allow versatile dataflow mapping through matrix routing system while also enabling the sound designer to influence generative processes of music creation. In particular, The AIE-Studio was used to create generative sonic and musical material in an embodied game-like application. In this paper we present key questions driving the research, theoretical background, research approach and the main development activities .
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we propose a joint framework for target localization and classification using a single generalized model for non-imaging based multi-modal sensor data. For target localization, we exploit both sensor data and estimated dynamics within a local neighborhood. We validate the capabilities of our framework by using a multi-modal dataset, which includes ground truth GPS information (e.g., time and position) and data from co-located seismic and acoustic sensors. Experimental results show that our framework achieves better classification accuracy compared to recent fusion algorithms using temporal accumulation and achieves more accurate target localizations than multilateration.
JUFOID=57409
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Multilabel ranking is an important machine learning task with many applications, such as content-based image retrieval (CBIR). However, when the number of labels is large, traditional algorithms are either infeasible or show poor performance. In this paper, we propose a simple yet effective multilabel ranking algorithm that is based on k-nearest neighbor paradigm. The proposed algorithm ranks labels according to the probabilities of the label association using the neighboring samples around a query sample. Different from traditional approaches, we take only positive samples into consideration and determine the model parameters by directly optimizing ranking loss measures. We evaluated the proposed algorithm using four popular multilabel datasets. The proposed algorithm achieves equivalent or better performance than other instance-based learning algorithms. When applied to a CBIR system with a dataset of 1 million samples and over 190 thousand labels, which is much larger than any other multilabel datasets used earlier, the proposed algorithm clearly outperforms the competing algorithms.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper the lightweight many-to-many authentication protocol, that uses Near Field Communications as a carrier technology is proposed. The solution works without any user interaction and can be applied for almost any data storage device: NFC or RFID tag, USB-flash drive, etc. The major novelty of the system is real-time encryption key generation algorithm. This approach doesn't require any computation power on the tag, trusted third parties or secure link between tag and information system. So far, the mentioned features transforms to significant advantages of the proposed solution, while compared to existing analogues: OAuth, Opacity and LMAP. At the same time, the integrity of key sequences is not guarantied, that brings motivation for future research in the field.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
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.
Research output: Contribution to journal › Article › Scientific › peer-review
Dataflow-based application specifications are widely used in model-based design methodologies for signal processing systems. In this paper, we develop a new model called the dataflow schedule graph (DSG) for representing a broad class of dataflow graph schedules. The DSG provides a graphical representation of schedules based on dataflow semantics. In conventional approaches, applications are represented using dataflow graphs, whereas schedules for the graphs are represented using specialized notations, such as various kinds of sequences or looping constructs. In contrast, the DSG approach employs dataflow graphs for representing both application models and schedules that are derived from them. Our DSG approach provides a precise, formal framework for unambiguously representing, analyzing, manipulating, and interchanging schedules. We develop detailed formulations of the DSG representation, and present examples and experimental results that demonstrate the utility of DSGs in the context of heterogeneous signal processing system design.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We have created a movable, limitedly volumetric "immaterial" display. Our prototype is the first mobile, hand-held fogscreen. It can show e.g., slices of volumetric objects when swept across mid-air. It is based on the patented FogScreen [Fogio 2013] technology. The previous FogScreen installations have been fixed set-ups, where the screen device and a projector are typically rigged up, leaving space for the viewers to walk through the mid-air display. Also mid-air virtual reality and mid-air user interfaces have been implemented [DiVerdi et al. 2006, Rakkolainen et al. 2009]. 2013 Copyright held by the Owner/Author.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The C2NET project aims to provide cloud-based platform for the supply chain interactions. The architecture of such platform includes a Data Collection Framework (DCF) for managing the collection of the company's data. The DCF collects, transforms and stores data from both Internet of Things (IoT) devices in the factory shopfloor and company enterprises data via two types of hub; Legacy system hub (LSH) and IoT hub. Since the C2NET, targets the Small and Medium-sized Enterprises (SMEs), the enterprise data, or legacy data as called in the C2NET project, can be provided via excel files. Thus, this research work highlights a technique for processing the excel files in the LSHs. This technique adopts the concept of Multi-Agent Systems for processing the data as table in the excel files in the LSH. The multi-agent approach allows the LSH to process any excel file regardless the complexity in the data structure or in the file table. Furthermore, the presented approach enhances the processing of the excel files in different aspects, such as the size of the excel file or the required processing power.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we develop new multiclass classification algorithms for detecting people and vehicles by fusing data from a multimodal, unattended ground sensor node. The specific types of sensors that we apply in this work are acoustic and seismic sensors. We investigate two alternative approaches to multiclass classification in this context - the first is based on applying Dempster-Shafer Theory to perform score-level fusion, and the second involves the accumulation of local similarity evidences derived from a feature-level fusion model that combines both modalities. We experiment with the proposed algorithms using different datasets obtained from acoustic and seismic sensors in various outdoor environments, and evaluate the performance of the two algorithms in terms of receiver operating characteristic and classification accuracy. Our results demonstrate overall superiority of the proposed new feature-level fusion approach for multiclass discrimination among people, vehicles and noise.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we consider incompletely defined discrete functions, i.e., Boolean and multiple-valued functions, f : S → {0, 1, . . . , q - 1} where S ⊆ {0, 1, . . . , q - 1}n i.e., the function value is specified only on a certain subset S of the domain of the corresponding completely defined function. We assume the function to be sparse i.e. |S| is 'small' relative to the cardinality of the domain. We show that by embedding the domain {0, 1, . . . , q - 1}n , where n is the number of variables and q is a prime power, in a suitable ring structure, the multiplicative structure of the ring can be used to construct a linear function {0, 1, . . . , q - 1}n → {0, 1, . . . , q - 1}m that is injective on S provided that m > 2 logq |S| + logq (n - 1). In this way we find a linear transform that reduces the number of variables from n to m, and can be used e.g. in implementation of an incompletely defined discrete function by using linear decomposition.
EXT="Stanković, Radomir"
Research output: Contribution to journal › Article › Scientific › peer-review
This paper presents an analysis of an efficient parallel implementation of the active-set Newton algorithm (ASNA), which is used to estimate the nonnegative weights of linear combinations of the atoms in a large-scale dictionary to approximate an observation vector by minimizing the Kullback–Leibler divergence between the observation vector and the approximation. The performance of ASNA has been proved in previous works against other state-of-the-art methods. The implementations analysed in this paper have been developed in C, using parallel programming techniques to obtain a better performance in multicore architectures than the original MATLAB implementation. Also a hardware analysis is performed to check the influence of CPU frequency and number of CPU cores in the different implementations proposed. The new implementations allow ASNA algorithm to tackle real-time problems due to the execution time reduction obtained.
Research output: Contribution to journal › Article › Scientific › peer-review
The Intelligent Transportation Systems concept provides the ground to enable a wide range of applications to improve traffic safety and efficiency. Innovative communication systems must be proposed taking into account, on the one hand, unstable characteristics of vehicular communications and, on the other hand, different requirements of applications. In this paper a reliable (geo-)broadcasting scheme for vehicular ad-hoc networks is proposed and analyzed. This receiver-based technique aims at fulfilling the received message integrity yet keeping the overhead at a reasonably low level. The results are compared to simulation studies carried out in the Network Simulator-3 (NS-3) simulation environment demonstrating good agreement with each other. The analysis shows that in a single-hop scenario, receiver-based reliable broadcasting can provide good reliability, while giving very little overhead for high number of receivers.
Research output: Contribution to journal › Article › Scientific › peer-review
Since video traffic is resource intensive, it is a challenging issue to stream video over low bandwidth networks, whereas video communication over LTE becomes an open research topic nowadays due to LTE’s high throughput capabilities. Indeed, video transmission requires low delay, and wireless channel is time-varying, which result in a scenario when a layer-separated design is replaced by a Cross-Layer Adaptation (CLA) principle. In this paper an efficient analytical model that evaluates the behavior of the downlink LTE channel with CLA is presented. To the best of our knowledge, this is the first time an analytical model using CLA principle has been devised that covers both the transmission process from the eNB to the User Equipment (UE) at the first phase and video decoding process at the UE at the second phase. In order to ensure the cross-layer adaptation in the model, the arrival rate varies based on the received video request, whereas the service probability changes according to the channel quality indicator sent from the UE. In the experimental part the analysis of the main performance measures found from the stationary distribution is conducted.
Research output: Contribution to journal › Article › Scientific › peer-review
Software maintenance has dramatically evolved in the last four decades, to cope with the continuously changing software development models, and programming languages and adopting increasingly advanced prediction models. In this work, we present the initial results of a Systematic Literature Review (SLR), highlighting the evolution of the metrics and models adopted in the last forty years.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Cloud-enabled tools developed in the Cloud Collaborative Manufacturing Networks (C2NET) project address the needs of small and medium enterprises with respect to information exchange and visibility across the collaboration partners in the supply network, coupled with automated and collaborative production planning and supply management. This paper analyses a case of an oil lubrication and hydraulic systems manufacturer and describes a pilot application of C2NET where the production schedule is optimized according to the priorities of the pilot company. In this case the goal is a highly adaptive just-in-time manufacturing schedule with guaranteed on time delivery.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The need for accurate documentation for the preservation of cultural heritage has prompted the use of terrestrial laser scanner (TLS) in this discipline. Its study in the heritage context has been focused on opaque surfaces with lambertian reflectance, while translucent and anisotropic materials remain a major challenge. The use of TLS for the mentioned materials is subject to significant distortion in measure due to the optical properties under the laser stimulation. The distortion makes the measurement by range not suitable for digital modelling in a wide range of cases. The purpose of this paper is to illustrate and discuss the deficiencies and their resulting errors in marmorean surfaces documentation using TLS based on time-of-flight and phase-shift. Also proposed in this paper is the reduction of error in depth measurement by adjustment of the incidence laser beam. The analysis is conducted by controlled experiments.
Research output: Contribution to journal › Article › Scientific › peer-review
Background: Open Source Software (OSS) is used by a continuously growing number of people, both end-users and developers. The quality of OSS is thus an issue of increasing interest. Specifically, OSS stakeholders need to trust OSS with respect to a number of qualities. Objective: This paper focuses on the level of trust that OSS stakeholders have in OSS reliability, one of the most important software qualities. The goal of the work reported here is to investigate to what extent the perception of reliability by users depends on objectively measurable characteristics of software. Method: We collected subjective user evaluations of the reliability of 22 Java OSS products, and then we measured their code characteristics that are generally believed to affect the quality of software. Finally, we carried out a correlational study to predict the perceived level of reliability of OSS based on the measured characteristics of the software code. Result: We obtained a set of statistically significant quantitative models, collectively called MOSST\REL, which account for the dependence of the perceived reliability of OSS on objectively observable qualities of Java code. Conclusions: The models we obtained can be used by: 1) endusers and developers that would like to reuse existing OSS products and components, to evaluate the perceived level of reliability of these OSS products that can be expected based on the characteristics of code; 2) the developers of OSS products, who can set code quality targets based on the level of perceived reliability they want to achieve.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The 'App economy' is a highly lucrative and competitive market for independent software vendors as it potentially offers an easy highway to reach millions of users. However, the mobile application landscape is scattered and an application developer has to publish the software for several different platforms to be able to serve a majority of smartphone users. Therefore, a bunch of cross-development tools have been offered to simplify this workload. In this paper, we present an evaluation framework for comparing different cross-development tools. We use this framework to evaluate Adobe PhoneGap tool against native development in Android and Windows Phone platforms. The results of a case study reveal that while the cross-platform technique was easy to use, the appearance and usability of the app was mediocre at its best. The business impacts of these are also discussed.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Dynamic simulation of distance to the physical surface could promote the development of new inexpensive tools for blind and visually impaired users. The StickGrip is a haptic device comprised of the Wacom pen input device added with a motorized penholder. The goal of the research presented in this paper was to assess the accuracy and usefulness of the new pen-based interaction technique when the position and displacement of the penholder in relation to the pen tip provided haptic feedback to the user about the distance to the physical or virtual surface of interaction. The aim was to examine how accurately people are able (1) to align the randomly deformed virtual surfaces to the flat surface and (2) to adjust the number of surface samples having a randomly assigned curvature to the template having the given curvature and kept fixed. These questions were approached by measuring both the values of the adjusted parameters and the parameters of the human performance, such as a ratio between inspection time and control time spent by the participants to complete the matching task with the use of the StickGrip device. The test of the pen-based interaction technique was conducted in the absence of visual feedback when the subject could rely on the proprioception and kinesthetic sense. The results are expected to be useful for alternative visualization and interaction with complex topographic and mathematical surfaces, artwork, and modeling.
Research output: Contribution to journal › Article › Scientific › peer-review
Although eye typing (typing on an on-screen keyboard via one's eyes as they are tracked by an eye tracker) has been studied for more than three decades now, we still know relatively little about it from the users' point of view. Standard metrics such as words per minute and keystrokes per character yield information only about the effectiveness of the technology and the interaction techniques developed for eye typing. We conducted an extensive study with almost five hours of eye typing per participant and report on extended qualitative and quantitative analysis of the relationship of dwell time, text entry rate, errors made, and workload experienced by the participants. The analysis method is comprehensive and stresses the need to consider different metrics in unison. The results highlight the importance of catering for individual differences and lead to suggestions for improvements in the interface.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Mobile app markets have been touted as fastest growing marketplaces in the world. Every day thousands of apps are published to join millions of others on app stores. The competition for top grossing apps and market visibility is fierce. The way an app is visually represented can greatly contribute to the amount of attention an icon receives and to its consequent commercial performance. Therefore, the icon of the app is of crucial importance as it is the first point of contact with the potential user/customer amidst the flood of information. Those apps that fail to arouse attention through their icons danger their commercial performance in the market where consumers browse past hundreds of icons daily. Using semantic differential scale (22 adjective pairs), we investigate the relationship between consumer perceptions of app icons and icon successfulness, measured by 1)overall evaluation of the icon, 2)willingness to click the icon, 3)willingness to download the imagined app and, 4)willingness to purchase the app. The study design was a vignette study with random participant (n = 569)assignment to evaluate 4 icons (n = 2276)from a total of pre-selected 68 game app icons across 4 categories (concrete, abstract, character and text). Results show that consumers are more likely to interact with app icons that are aesthetically pleasing and convey good quality. Particularly, app icons that are perceived unique, realistic and stimulating lead to more clicks, downloads and purchases.
Research output: Contribution to journal › Article › Scientific › peer-review
We propose a full processing pipeline to acquire anthropometric measurements from 3D measurements. The first stage of our pipeline is a commercial point cloud scanner. In the second stage, a pre-defined body model is fitted to the captured point cloud. We have generated one male and one female model from the SMPL library. The fitting process is based on non-rigid iterative closest point algorithm that minimizes overall energy of point distance and local stiffness energy terms. In the third stage, we measure multiple circumference paths on the fitted model surface and use a nonlinear regressor to provide the final estimates of anthropometric measurements. We scanned 194 male and 181 female subjects, and the proposed pipeline provides mean absolute errors from 2.5 to 16.0 mm depending on the anthropometric measurement.
Research output: Contribution to journal › Article › Scientific › peer-review
In this paper, we describe Antroposeeni, a mixed reality game designed and developed for mobile devices. Antroposeeni utilizes location-based services, GPS for tracking users and augmented reality techniques for displaying captivating audiovisual content and creating rich experiences. Our demonstration will introduce a pilot version of the game, which encompasses narrative elements of the game mediated through developed media technologies. The goal for the demonstration is to give the conference visitors a chance to test the game in a specifically tailored route close to the conference site. After conducting the pilot we plan to organize a short review regarding the user experience.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Video game genre classification has long been a focusing perspective in game studies domain. Despite the commonly acknowledged usefulness of genre classification, scholars in the game studies domain are yet to reach consensus on the game genre classification. On the other hand, Steam, a popular video game distribution platform, adopts the user-generated tag feature enabling players to describe and annotate video games based on their own understanding of genres. Despite the concern of the quality, the user-generated tags (game tags) provide an opportunity towards an alternative way of understanding video game genres based on the players' collective intelligence. Hence, in this study, we construct a network of game tags based on the co-occurrence of tags in games on Steam platform and analyze the structure of the network via centrality analysis and community detection. Such analysis shall provide an intuitive presentation on the distribution and connections of the game tags, which furthermore suggests a potential way of understanding the important tags that are commonly adopted and the main genres of video games.
INT=coms,"Li, Xiaozhou"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The quality control and optimization of Simulated Moving Bed processes are still a challenge. Among the main reasons for that, the real time measurement of its main properties can be highlighted. Further developments in this field are necessary in order to allow the development of better control and optimization systems of these units. In the present work, a system composed by two Artificial Neural Networks working concomitantly with an offline measurement system is proposed, named Quasi-Virtual Analyser (Q-VOA) system. The development of the Q-VOA is presented and the system is simulated in order to evaluate its efficiency. The methodology used to select the input variables for the Q-VOA is another contribution of this work. The results show that the Q-VOA is capable of reducing the system errors and keep the prediction closer to the process true responses, when compared with the simple VOA system, which is based solely on model predictions. Furthermore, the results show the efficiency of the measurement system even under the presence of non-measured perturbations.
Research output: Contribution to journal › Article › Scientific › peer-review
The Liquid Software metaphor refers to software that can operate seamlessly across multiple devices owned by one or multiple users. Liquid Software applications can take advantage of the computing, storage and communication resources available on all the devices owned by the user. Liquid Software applications can also dynamically migrate from one device to another, following the user’s attention and usage context. The key design goal in Liquid Software development is to minimize the additional efforts arising from multiple device ownership (e.g., installation, synchronization and general maintenance of personal computers, smartphones, tablets, home and car displays, and wearable devices), while keeping the users in full control of their devices, applications and data. In this paper we present the design space for Liquid Software, categorizing and discussing the most important architectural dimensions and technical choices. We also provide an introduction and comparison of two frameworks implementing Liquid Software capabilities in the context of the World Wide Web.
EXT="Mikkonen, Tommi"
EXT="Taivalsaari, Antero"
Research output: Contribution to journal › Article › Scientific › peer-review
Microservices is an architectural style increasing in popularity. However, there is still a lack of understanding how to adopt a microservice-based architectural style. We aim at characterizing different microservice architectural style patterns and the principles that guide their definition. We conducted a systematic mapping study in order to identify reported usage of microservices and based on these use cases extract common patterns and principles. We present two key contributions. Firstly, we identified several agreed microservice architecture patterns that seem widely adopted and reported in the case studies identified. Secondly, we presented these as a catalogue in a common template format including a summary of the advantages, disadvantages, and lessons learned for each pattern from the case studies. We can conclude that different architecture patterns emerge for different migration, orchestration, storage and deployment settings for a set of agreed principles.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Background. Architectural smells and code smells are symptoms of bad code or design that can cause different quality problems, such as faults, technical debt, or difficulties with maintenance and evolution. Some studies show that code smells and architectural smells often appear together in the same file. The correlation between code smells and architectural smells, however, is not clear yet; some studies on a limited set of projects have claimed that architectural smells can be derived from code smells, while other studies claim the opposite. Objective. The goal of this work is to understand whether architectural smells are independent from code smells or can be derived from a code smell or from one category of them. Method. We conducted a case study analyzing the correlations among 19 code smells, six categories of code smells, and four architectural smells. Results. The results show that architectural smells are correlated with code smells only in a very low number of occurrences and therefore cannot be derived from code smells. Conclusion. Architectural smells are independent from code smells, and therefore deserve special attention by researchers, who should investigate their actual harmfulness, and practitioners, who should consider whether and when to remove them.
Research output: Contribution to journal › Article › Scientific › peer-review
The popularity of tools for analyzing Technical Debt, and particularly the popularity of SonarQube, is increasing rapidly. SonarQube proposes a set of coding rules, which represent something wrong in the code that will soon be reflected in a fault or will increase maintenance effort. However, our local companies were not confident in the usefulness of the rules proposed by SonarQube and contracted us to investigate the fault-proneness of these rules. In this work we aim at understanding which SonarQube rules are actually fault-prone and to understand which machine learning models can be adopted to accurately identify fault-prone rules. We designed and conducted an empirical study on 21 well-known mature open-source projects. We applied the SZZ algorithm to label the fault-inducing commits. We analyzed the fault-proneness by comparing the classification power of seven machine learning models. Among the 202 rules defined for Java by SonarQube, only 25 can be considered to have relatively low fault-proneness. Moreover, violations considered as 'bugs' by SonarQube were generally not fault-prone and, consequently, the fault-prediction power of the model proposed by SonarQube is extremely low. The rules applied by SonarQube for calculating technical debt should be thoroughly investigated and their harmfulness needs to be further confirmed. Therefore, companies should carefully consider which rules they really need to apply, especially if their goal is to reduce fault-proneness.
EXT="Lenarduzzi, Valentina"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Production planning and control in printed wiring board (PWB) manufacturing is becoming more difficult as PWB's technology is developing and the production routings become more complex. Simultaneously, the strategic importance of delivery accuracy, short delivery times, and production flexibility is increasing with the highly fluctuating demand and short product life cycles of end products. New principles, that minimize throughput time while guaranteering excellent customer service and adequate capacity utilization, are needed for production planning and control. Simulation is needed in order to develop the new principles and test their superiority. This paper presents an ongoing simulation product that aims at developing the production planning and control of a PWB manufacturer. In the project, a discrete event simulation model is built of a pilot case factory. The model is used for comparing the effect of scheduling, queuing rules, buffer policies, and lot sizes on customer service and cost efficiency.
Research output: Contribution to journal › Conference article › Scientific › peer-review
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Diversification and obfuscation methods are promising approaches used tosecuresoftware and prevent malware from functioning. Diversification makes each software instance unique so that malware attacks cannot rely on the knowledge of the program's execution environment and/or internal structure anymore. We present a systematic literature review on the state of-the-art of diversification and obfuscation research aiming to improve software security between 1993 and 2014. As the result of systematic search, in the final phase, 209 related papers were included in this study. In this study we focus on two specific research questions: what are the aims of diversification and obfuscation techniques and what are the environments they are applied to. The former question includes the languages and the execution environments that can benefit from these two techniques, while the second question presents the goals of the techniques and also the type of attacks they mitigate. is held by the owner/author(s). Publication rights licensed to ACM.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Trustworthiness is a crucial characteristic when it comes to evaluating any product, even more so for open source software, which is now becoming widely used. The authors conducted a survey to identify the reasons and motivations that lead software companies to adopt or reject open source software; they then ranked, according to importance, the specific trust factors used when selecting an open source software component or product. The motivations and importance ranking of factors might be useful for both developers of open source software (to make their products and components more useful for other stakeholders) and to future prospective open source software users.
Research output: Contribution to journal › Article › Scientific › peer-review
This paper, as a generalization of our previous works, presents a unified time-optimal path-following controller for Wheeled Mobile Robots (WMRs). Unlike other path-following controllers, we solve the path-following problem for all common categories of WMRs such as car-like, differential, omnidirectional, all wheels steerable and others. We show that the insertion of our path-following controller into the kinematic and non-holonomic constraints of the wheels, simplifies the otherwise impenetrable constraints, resulting in explicit monotonic functions between the velocity of the base and that of the wheels. Based on this foundation, we present a closed-form solution that keeps all the wheels' steering and driving velocities within their corresponding pre-specified bounds. Simulation data and experimental results from executing the controller in a real-time environment demonstrate the efficacy of the method.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Modern embedded systems show a clear trend towards the use of Multiprocessor System-on-Chip (MPSoC) architectures in order to handle the performance and power consumption constraints. However, the design and validation of dedicated MPSoCs is an extremely hard and expensive task due to their complexity. Thus, the development of automated design processes is of highest importance to satisfy the time-to-market pressure of embedded systems. This paper proposes an automated co-design flow based on the high-level language-based approach of the Reconfigurable Video Coding framework. The designer provides the application description in the RVC-CAL dataflow language, after which the presented co-design flow automatically generates a network of heterogeneous processors that can be synthesized on FPGA chips. The synthesized processors are Very Long Instruction Word-style processors. Such a methodology permits the rapid design of a many-core signal processing system which can take advantage of all levels of parallelism. The toolchain functionality has been demonstrated by synthesizing an MPEG-4 Simple Profile video decoder to two different FPGA boards. The decoder is realized into 18 processors that decode QCIF resolution video at 45 frames per second on a 50 MHz FPGA clock frequency. The results show that the given application can take advantage of every level of parallelism.
Research output: Contribution to journal › Article › Scientific › peer-review
An automatic computer vision algorithm that detects individual paper fibres from an image, assesses the possibility of grasping the detected fibres with microgrippers and detects the suitable grasping points is presented. The goal of the algorithm is to enable automatic fibre manipulation for mechanical characterisation, which has traditionally been slow manual work. The algorithm classifies the objects in images based on their morphology, and detects the proper grasp points from the individual fibres by applying given geometrical constraints. The authors test the ability of the algorithm to detect the individual fibres with 35 images containing more than 500 fibres in total, and also compare the graspability analysis and the calculated grasp points with the results of an experienced human operator with 15 images that contain a total of almost 200 fibres. The detection results are outstanding, with fewer than 1% of fibres missed. The graspability analysis gives sensitivity of 0.83 and specificity of 0.92, and the average distance between the grasp points of the human and the algorithm is 220 μm. Also, the choices made by the algorithm are much more consistent than the human choices.
Research output: Contribution to journal › Article › Scientific › peer-review
Automatic word count estimation (WCE) from audio recordings can be used to quantify the amount of verbal communication in a recording environment. One key application of WCE is to measure language input heard by infants and toddlers in their natural environments, as captured by daylong recordings from microphones worn by the infants. Although WCE is nearly trivial for high-quality signals in high-resource languages, daylong recordings are substantially more challenging due to the unconstrained acoustic environments and the presence of near- and far-field speech. Moreover, many use cases of interest involve languages for which reliable ASR systems or even well-defined lexicons are not available. A good WCE system should also perform similarly for low- and high-resource languages in order to enable unbiased comparisons across different cultures and environments. Unfortunately, the current state-of-the-art solution, the LENA system, is based on proprietary software and has only been optimized for American English, limiting its applicability. In this paper, we build on existing work on WCE and present the steps we have taken towards a freely available system for WCE that can be adapted to different languages or dialects with a limited amount of orthographically transcribed speech data. Our system is based on language-independent syllabification of speech, followed by a language-dependent mapping from syllable counts (and a number of other acoustic features) to the corresponding word count estimates. We evaluate our system on samples from daylong infant recordings from six different corpora consisting of several languages and socioeconomic environments, all manually annotated with the same protocol to allow direct comparison. We compare a number of alternative techniques for the two key components in our system: speech activity detection and automatic syllabification of speech. As a result, we show that our system can reach relatively consistent WCE accuracy across multiple corpora and languages (with some limitations). In addition, the system outperforms LENA on three of the four corpora consisting of different varieties of English. We also demonstrate how an automatic neural network-based syllabifier, when trained on multiple languages, generalizes well to novel languages beyond the training data, outperforming two previously proposed unsupervised syllabifiers as a feature extractor for WCE.
Research output: Contribution to journal › Article › Scientific › peer-review
Purpose – The purpose of this paper is to investigate the extent, drivers, and conditions underlying backshoring in the Finnish manufacturing industry, comparing the results to the wider ongoing relocation of production in the international context. Design/methodology/approach – The survey of 229 Finnish manufacturing firms reveals the background, drivers, and patterns of offshoring and backshoring. Findings – Companies that had transferred their production back to Finland were more commonly in industries with relatively higher technology intensity and they were typically larger than the no-movement companies, and with a higher number of plants. They also reported more commonly having a corporate-wide strategy for guiding production location decisions. Research limitations/implications – Backshoring activity in the small and open economy of Finland seems to be higher compared to earlier studies in larger countries. The findings suggest that there is a transformation in the manufacturing industries with some gradual replacement of labor-intensive and lower technology-intensive industries toward higher technology-intensive industries. Practical implications – Moving production across national borders is one option in the strategies of firms to stay competitive. Companies must carefully consider the relevance of various decision-making drivers when determining strategies for their production networks. Social implications – Manufacturing industries have traditionally been important for employment in the relatively small and open economies of the Nordic countries. From the social perspective, it is important to understand the ongoing transformation and its implications. Originality/value – There are few empirical studies available of the ongoing backshoring movement, utilizing data from company decision makers instead of macroeconomic factors.
Research output: Contribution to journal › Article › Scientific › peer-review
Positive face-to-face social encounters between strangers can strengthen the sense of community in modern urban environments. However, it is not always easy to initiate friendly encounters due to various inhibiting social norms. We present three inspirational design patterns for reducing inhibitions to interact with unfamiliar others. These abstractions are based on a broad design space review of concepts, encompassing examples across a range of scales, fields, media and forms. Each inspirational pattern is formulated as a response to a different challenge to initiating social interaction but all share an underlying similarity in offering varieties of barriers and filters that paradoxically also separate people. The patterns are "Closer Through Not Seeing"; "Closer Through Not Touching"; and "Minimize Encounter Duration". We believe these patterns can support designers, in understanding, articulating, and generating approaches to creating embodied interventions and systems that enable unacquainted people to interact.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We analyze barriers to task-based information access in molecular medicine, focusing on research tasks, which provide task performance sessions of varying complexity. Molecular medicine is a relevant domain because it offers thousands of digital resources as the information environment. Data were collected through shadowing of real work tasks. Thirty work task sessions were analyzed and barriers in these identified. The barriers were classified by their character (conceptual, syntactic, and technological) and by their context of appearance (work task, system integration, or system). Also, work task sessions were grouped into three complexity classes and the frequency of barriers of varying types across task complexity levels were analyzed. Our findings indicate that although most of the barriers are on system level, there is a quantum of barriers in integration and work task contexts. These barriers might be overcome through attention to the integrated use of multiple systems at least for the most frequent uses. This can be done by means of standardization and harmonization of the data and by taking the requirements of the work tasks into account in system design and development, because information access is seldom an end itself, but rather serves to reach the goals of work tasks.
Research output: Contribution to journal › Article › Scientific › peer-review
We propose a novel classifier accuracy metric: the Bayesian Area Under the Receiver Operating Characteristic Curve (CBAUC). The method estimates the area under the ROC curve and is related to the recently proposed Bayesian Error Estimator. The metric can assess the quality of a classifier using only the training dataset without the need for computationally expensive cross-validation. We derive a closed-form solution of the proposed accuracy metric for any linear binary classifier under the Gaussianity assumption, and study the accuracy of the proposed estimator using simulated and real-world data. These experiments confirm that the closed-form CBAUC is both faster and more accurate than conventional AUC estimators.
EXT="Tohka, Jussi"
Research output: Contribution to journal › Article › Scientific › peer-review
In this editorial a short introduction to the special issue on Big Media Data Analysis is given. The scope of this Editorial is to briefly present methodologies, tasks and applications of big media data analysis and to introduce the papers of the special issue. The special issue includes six papers that span various media analysis application areas like generic image description, medical image and video analysis, distance calculation acceleration and data collection.
EXT="Tefas, Anastasios"
Research output: Contribution to journal › Editorial › Scientific › peer-review
The performance of many cryptographic primitives is reliant on efficient algorithms and implementation techniques for arithmetic in binary fields. While dedicated hardware support for said arithmetic is an emerging trend, the study of software-only implementation techniques remains important for legacy or non-equipped processors. One such technique is that of software-based bit-slicing. In the context of binary fields, this is an interesting option since there is extensive previous work on bit-oriented designs for arithmetic in hardware, such designs are intuitively well suited to bit-slicing in software. In this paper we harness previous work, using it to investigate bit-sliced, software-only implementation arithmetic for binary fields, over a range of practical field sizes and using a normal basis representation. We apply our results to demonstrate significant performance improvements for a stream cipher, and over the frequently employed Ning-Yin approach to normal basis implementation in software.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In the paper, a new method of blind estimation of noise variance in a single highly textured image is proposed. An input image is divided into 8x8 blocks and discrete cosine transform (DCT) is performed for each block. A part of 64 DCT coefficients with lowest energy calculated through all blocks is selected for further analysis. For the DCT coefficients, a robust estimate of noise variance is calculated. Corresponding to the obtained estimate, a part of blocks having very large values of local variance calculated only for the selected DCT coefficients are excluded from the further analysis. These two steps (estimation of noise variance and exclusion of blocks) are iteratively repeated three times. For the verification of the proposed method, a new noise-free test image database TAMPERE17 consisting of many highly textured images is designed. It is shown for this database and different values of noise variance from the set {25, 49, 100, 225}, that the proposed method provides approximately two times lower estimation root mean square error than other methods.
jufoid=84313
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
A satellite navigation receiver traditionally searches for positioning signals using an acquisition procedure. In situations, in which the required information is only a binary decision whether at least one positioning signal is present or absent, the procedure represents an unnecessarily complex solution. This paper presents a different approach for the binary detection problem with significantly reduced computational complexity. The approach is based on a novel decision metric which is utilized to design two binary detectors. The first detector operates under the theoretical assumption of additive white Gaussian noise and is evaluated by means of Receiver Operating Characteristics. The second one considers also additional interferences and is suitable to operate in a real environment. Its performance is verified using a signal captured by a receiver front-end.
EXT="Raasakka, Jussi"
EXT="Peltola, Pekka"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We introduce a content-Adaptive approach to image denoising where the filter design is based on mean opinion scores (MOSs) from preliminary experiments with volunteers who evaluated the quality of denoised image fragments. This allows to tune the filter parameters so to improve the perceptual quality of the output image, implicitly accounting for the peculiarities of the human visual system (HVS). A modification of the BM3D image denoising filter (Dabov et al., IEEE TIP, 2007), namely BM3DHVS, is proposed based on this framework. We show that it yields a higher visual quality than the conventional BM3D. Further, we have also analyzed the MOSs against popular full-reference visual quality metrics such as SSIM (Wang et al., IEEE TIP, 2004), its extension FSIM (Zhang et al., IEEE TIP, 2011), and the noreference IL-NIQE (Zhang et al., IEEE TIP, 2015) over each image fragment. Both the Spearman and the Kendall rank order correlation show that these metrics do not correspond well to the human perception. This calls for new visual quality metrics tailored for the benchmarking and optimization of image denoising methods.
EXT="Danielyan, Aram"
EXT="Lukin, Vladimir"
jufoid=84313
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We present a study of using embodied health information system for developing regions focusing on users not familiar with technology. We designed and developed a health information system with two gesture-based selection techniques: pointing to a screen and touching one's own body part. We evaluated the prototype in user study with 37 semi-literate and literate participants. Our results indicate a clear preference (76%) for touching in the healthcare domain. Based on our observations and user feedback, we present four design guidelines for developing embodied systems for the developing world: designing bodycentric interaction to overcome literacy and technological proficiency barriers, addressing the misconceptions of system behaviors with users not familiar with technology, understanding effects of cultural constraints on interaction, and utilizing interactive virtual avatars to connect with the users.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Mobile handheld devices are an increasing part of everyday fieldwork of news professionals. Mobile assignments delivered to mobile journalists' smartphones are one potential future development step. We present findings on using mobile assignments from two exploratory user studies in which smartphones were used as news reporting tools. Mobile assignments were perceived as handy for fast reporting situations and simple stories but challenging in case of more complex tasks. Structured information content of assignments, process phase based information and supporting situation and activity awareness would support the work of both editorial staff and mobile journalists. The locationing of reporters for sending location-based assignments was found acceptable for coordinating the work although some privacy concerns were expressed. The findings provide new information on using mobile assignments in work where carrying out tasks involves creativity and the tasks may be complex, not strictly limited or they may not have clear completion criteria. © 2012 ACM.
ei ut-numeroa 21.9.2013<br/>Contribution: organisation=ohj,FACT1=1<br/>Publisher name: ACM
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Today many organizations have come to value knowledge as a production factor. Thus, there is a constant need for getting the information in and sorted. Business intelligence (BI) is a process for systematic acquiring, analyzing, and disseminating data and information from various sources to gain understanding about the business's environment. This is required for supporting decisions for achieving organization's business objectives. Literature has introduced models for planning and executing BI. However, as business environments and technologies evolve in a rapid pace, are the models still applicable? Not all recent issues are taken into consideration in the previous models. BI is considered to be integrated into business processes, so the similar evolution is expected to take place. There are two studies investigating BI instigating this study, but there are still questions to be answered. Literature on different models and findings of these studies were combined to form a vision to better match reality. Various issues like users' active involvement, real-time analysis and presentation, and social media resources were brought up. Practitioners can use the approach to assess their current state of BI activities or planning the organization of BI program.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we explore how to better integrate virtual reality viewing to a smartphone. We present novel designs for casual (short-term) immersive viewing of spatial and 3D content, such as augmented and virtual reality, with smartphones. Our goal is to create a simple and low-cost casual-viewing design which could be retrofitted and eventually be embedded into smartphones, instead of using larger spatial viewing accessories. We explore different designs and implemented several prototypes. One prototype uses thin and light near-to-eye optics with a smartphone display, thus providing the user with the functionality of a large, high-resolution virtual display. Our designs also enable 3D user interfaces. Easy interaction through various gestures and other modalities is possible by using the inertial and other sensors and camera of the smartphone. Our preliminary concepts are a starting point for exploring useful constructions and designs for such usage.
EXT="Rakkolainen, Ismo"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The present contribution proposes a spectrally efficient censor-based cooperative spectrum sensing (C-CSS) approach in a sustainable cognitive radio network that consists of multiple antenna nodes and experiences imperfect sensing and reporting channels. In this context, exact analytic expressions are first derived for the corresponding probability of detection, probability of false alarm, and secondary throughput, assuming that each secondary user (SU) sends its detection outcome to a fusion center only when it has detected a primary signal. Capitalizing on the findings of the analysis, the effects of critical measures, such as the detection threshold, the number of SUs, and the number of employed antennas, on the overall system performance are also quantified. In addition, the optimal detection threshold for each antenna based on the Neyman-Pearson criterion is derived and useful insights are developed on how to maximize the system throughput with a reduced number of SUs. It is shown that the C-CSS approach provides two distinct benefits compared with the conventional sensing approach, i.e., without censoring: i) the sensing tail problem, which exists in imperfect sensing environments, can be mitigated; and ii) less SUs are ultimately required to obtain higher secondary throughput, rendering the system more sustainable.
Research output: Contribution to journal › Article › Scientific › peer-review
Context: Global software development (GSD), although now a norm in the software industry, carries with it enormous challenges mostly regarding communication and coordination. Aforementioned challenges are highlighted when there is a need to transfer knowledge between sites, particularly when software artifacts assigned to different sites depend on each other. The design of the software architecture and associated task dependencies play a major role in reducing some of these challenges. Objective: The current literature does not provide a cohesive picture of how the distributed nature of software development is taken into account during the design phase: what to avoid, and what works in practice. The objective of this paper is to gain an understanding of software architecting in the context of GSD, in order to develop a framework of challenges and solutions that can be applied in both research and practice. Method: We conducted a systematic literature review (SLR) that synthesises (i) challenges which GSD imposes on software architecture design, and (ii) recommended practices to alleviate these challenges. Results: We produced a comprehensive set of guidelines for performing software architecture design in GSD based on 55 selected studies. Our framework comprises nine key challenges with 28 related concerns, and nine recommended practices, with 22 related concerns for software architecture design in GSD. These challenges and practices were mapped to a thematic conceptual model with the following concepts: Organization (Structure and Resources), Ways of Working (Architecture Knowledge Management, Change Management and Quality Management), Design Practices, Modularity and Task Allocation. Conclusion: The synthesis of findings resulted in a thematic conceptual model of the problem area, a mapping of the key challenges to practices, and a concern framework providing concrete questions to aid the design process in a distributed setting. This is a first step in creating more concrete architecture design practices and guidelines.
Research output: Contribution to journal › Article › Scientific › peer-review
Understanding data-based value creation helps organizations to enhance its decision-making and to renew their business operations. However, organizations aiming to use modern data analytics face several severe challenges that are not usually so evident or visible beforehand. In this paper we study a Finnish manufacturing company's data empowerment and information and knowledge management practices in order to identify the potential challenges related to modern data-based value creation within industrial context. The empirical data is consisted of group discussions, relevant data sets acquired from the case company's information systems, and lastly, 12 thematic interviews of the key actors in the company in relation to service development. The study provides valuable insights for managing service development and decision-making and creates understanding on data-based value creation. Achieved understanding provides meaningful knowledge for organizations utilizing or having plans to utilize, for example, data analytic methods in their businesses.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The unprecedented proliferation of smart devices together with novel communication, computing, and control technologies have paved the way for A-IoT. This development involves new categories of capable devices, such as high-end wearables, smart vehicles, and consumer drones aiming to enable efficient and collaborative utilization within the smart city paradigm. While massive deployments of these objects may enrich people's lives, unauthorized access to said equipment is potentially dangerous. Hence, highly secure human authentication mechanisms have to be designed. At the same time, human beings desire comfortable interaction with the devices they own on a daily basis, thus demanding authentication procedures to be seamless and user-friendly, mindful of contemporary urban dynamics. In response to these unique challenges, this work advocates for the adoption of multi-factor authentication for A-IoT, such that multiple heterogeneous methods - both well established and emerging - are combined intelligently to grant or deny access reliably. We thus discuss the pros and cons of various solutions as well as introduce tools to combine the authentication factors, with an emphasis on challenging smart city environments. We finally outline the open questions to shape future research efforts in this emerging field.
Research output: Contribution to journal › Article › Scientific › peer-review
A visual data flow language (VDFL) allows graphical presentation of a computer program in the form of a directed graph, where data tokens travel through the arcs of the graph, and the vertices present e.g. the input token streams, calculations, comparisons, and conditionals. Amongst their benefits, VDFLs allow parallel computing and they are presumed to improve the quality of programming due to their intuitive readability. Thus, they are also suitable for computing education. However, the token-based computational model allowing parallel processing may make the programs more complicated than what they look. We propose a method for checking properties of VDFL programs using finite state processes (FSPs) using a commonly available labelled transition system analyser (LTSA) tool. The method can also be used to study different VDFL programming constructs for development or re-design of VDFLs. For our method, we have implemented a compiler that compiles a textual representation of a VDFL into FSPs.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Although video sharing is common among youth, schools are only beginning to apply digital videos and digital storytelling to formal learning. This paper presents pedagogical models, examples, best practices, and outcomes that illustrate how teachers and students design and use digital stories in knowledge creation in cross-cultural settings. The results are based on the empirical data and findings from several international pilot studies. On the one hand, working with digital video stories drove engagement. However, on the other hand, technical issues significantly lowered engagement. In addition, the video inquiry pedagogy supported inquiry learning. Students began to pose scientifically oriented questions and seek answers together.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this preliminary research we examine the suitability of hierarchical strategies of multi-class support vector machines for classification of induced pluripotent stem cell (iPSC) colony images. The iPSC technology gives incredible possibilities for safe and patient specific drug therapy without any ethical problems. However, growing of iPSCs is a sensitive process and abnormalities may occur during the growing process. These abnormalities need to be recognized and the problem returns to image classification. We have a collection of 80 iPSC colony images where each one of the images is prelabeled by an expert to class bad, good or semigood. We use intensity histograms as features for classification and we evaluate histograms from the whole image and the colony area only having two datasets. We perform two feature reduction procedures for both datasets. In classification we examine how different hierarchical constructions effect the classification. We perform thorough evaluation and the best accuracy was around 54% obtained with the linear kernel function. Between different hierarchical structures, in many cases there are no significant changes in results. As a result, intensity histograms are a good baseline for the classification of iPSC colony images but more sophisticated feature extraction and reduction methods together with other classification methods need to be researched in future.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We present a binary graph classifier (BGC) which allows to classify large, unweighted, undirected graphs. This classifier is based on a local decomposition of the graph for each node in generalized trees. The obtained trees, forming the tree set of the graph, are then pairwise compared by a generalized tree-similarity-algorithm (GTSA) and the resulting similarity scores determine a characteristic similarity distribution of the graph. Classification in this context is defined as mutual consistency for all pure and mixed tree sets and their resulting similarity distributions in a graph class. We demonstrate the application of this method to an artificially generated data set and for data from microarray experiments of cervical cancer.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper we describe a method for nonlinear class-specific discriminant learning that is based on Cholesky Decomposition. We show that the optimization problem solved in Class-Specific Kernel Discriminant Analysis is equivalent to that of Low-Rank Kernel Regression using training data independent target vectors. This connection allows us to devise a new Class-Specific Kernel Discriminant Analysis method that can be trained by exploiting fast linear system approaches, like the Cholesky decomposition. We verify our analysis in publicly available verification problems designed for human action recognition.
jufoid=58177
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Smart city development relies heavily on creation of digital services that are available for the citizens and for the city authorities. At best, these services are co-created by the authorities, citizens and the digital solution supplier companies. Digital service co-creation is, however, a complex process and includes several contradictions due to presence of several stakeholders. In this paper, we present a case study of smart city initiated digital service co-creation process through the analytical lenses of activity theory.
EXT="Jussila, Jari"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Programming has become an essential subject for today's education curriculum and as a result, the importance of creating the right environments to teach is increasing. For such environments, featuring tangible tools enhances creativity and collaboration. However, due to their high prices, current tangible tools are not reachable by most of the students. We developed Code Notes as a low-cost, attainable and tangible tool aimed to motivate children to support programming education. Code Notes is comprised of an Android app and code-cardboards to teach the basic concepts in programming. We continue to develop the platform with insights gained from children. This paper shares the design phases of Code Notes and observations from our two-month programming project. We also presented some future concepts of Code Notes that offer an active and embodied interaction with the teaching material.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Enterprise software development is a complex effort that may last years. Enterprise software is often developed by a systems integrator that makes modifications to a pre-made package or builds tailored software for the specific purpose. The development may include many developer organizations, the user organization, and their different departments and sub-units. Their collaboration evolves through project incidents, phases and even crises. The practices of project management, communication, contracts, and ultimately personal relationships change intentionally or unintentionally. These changes may cause uncertainties and discontinuities for the development. This study observes changes during enterprise software development and their influence on collaboration practices in different situations. During twenty years of development both internal and external crises and changes in the business environment triggered changes in collaboration. The collaboration practices are classified with four modes of collaboration (contract, cooperation, personified, and process) that illustrate emphasis in collaboration in different circumstances.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Future home networks are expected to become extremely sophisticated, yet only the most technically adept persons are equipped with skills to manage them. In this paper, we provide a novel solution as to how complex smart home networks can be collaboratively managed with the assistance of operators and third party experts. Our solution rests in separating the management and control functionalities of the home access points and routers, away from the actual connectivity, traffic forwarding and routing operations within the home network. By so doing, we present a novel REST-based architecture in which the management of the home network can be hosted in an entirely separate, external cloud-based infrastructure, which models the network within the home as a resource graph.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Groups of mutually similar image blocks are the key element in nonlocal image processing. In this work, the spatial coordinates of grouped blocks are leveraged in two distinct parts of the transform-domain collaborative filtering within the BM3D algorithm. First, we introduce an adaptive 1-D transform for 3-D collaborative filtering based on sampling 2-D smooth functions at the positions of grouped blocks. This adaptive transform is applied for improved decorrelation of the 2-D spectra of the grouped blocks. Second, we propose a directional sharpening procedure whose strength varies adaptively according to the relative orientation of the transform basis functions with respect to the group coordinates. Experiments confirm the efficacy of the proposed adaptations, for denoising as well as for sharpening of noisy images.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
There exists a large base of evidence for gender differences in human navigation. However, there is not much research on gender differences in collaborative aspects of navigation, including the interaction of individuals during collaborative wayfinding tasks in virtual environments. In light of this, we present a study of a collaborative virtual environment, Berlin Kompass. The goal of this study was to find out the main differences between genders in collaborative wayfinding. The application was evaluated in the context of foreign language learning in schools with over 200 students, where the users navigated through cityscapes while interacting verbally with each other. We collected and analyzed interaction logs, questionnaire data and audio and video recordings to gain insights into gender-related differences in wayfinding in virtual worlds. Our findings suggest that several differences that are evident in single user systems are not present when the collaborative aspect is added. Male users were more immersed during the task than females. One of the explaining factors for this might be video game experience. Genders also communicated differently - males spoke in longer utterances whereas females had more, shorter utterances. Males referred more to relative directions and dynamic landmarks such as cars and pedestrians while navigating. Males with more video game experience also provided more positive subjective user experience feedback on the application.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Software development methods are shifting towards faster deployments and closer to the end users. Their ever tighter engagement of end-users also requires new technologies for gathering feedback from those users. At the same time, widespread Internet connectivity of different application environments is enabling the collection of this post-deployment data also from sources other than traditional web and mobile software. However, the sheer number of different alternatives of collecting technologies makes the selection a complicated process in itself. In this paper, we describe the process of data-driven software development and study the challenges organizations face when they want to start guiding their development towards it. From these challenges, we extract evaluation criteria for technological approaches to usage data collecting. We list such approaches and evaluate them using the extracted criteria. Using a design science approach, we refine the evaluation criteria to a selection framework that can help practitioners in finding a suitable technological approach for automated collecting of usage data.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Social robots are entering our workplaces, homes, medical and educational systems in assistive and collaborative roles. In our research, we have investigated the use of a social robot Pepper as an interactive icebreaker host to create a positive atmosphere at events. This paper presents two user studies (total n=43) in which we evaluated two interactive prototypes of playful applications on Pepper, with the overall aim of providing a personal and entertaining service for event attendees. Data about users' experiences and attitudes were collected with semi-structured interviews, surveys, and observations. The results of the studies suggest that the majority of the participants had pleasurable and positive experiences with the robot and its applications. Moreover, their positive encounters led them to accept social robots as icebreaker hosts to connect with strangers. Based on our findings, we present a list of design implications to help the future design of social robots used to facilitate social connectedness, and to aid in the development of social robots as intelligent agents performing tasks as integrated parts of smart spaces.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We present a new image enhancement algorithm based on combined local and global image processing. The basic idea is to apply α-rooting image enhancement approach for different image blocks. For this purpose, we split image in moving windows on disjoint blocks with different size (8 by 8, 16 by 16, 32 by 32 and, i.e.). The parameter alfa for every block driven through optimization of measure of enhancement (EME). The resulting image is a weighted mean of all processing blocks. This strategy for image enhancement allows getting more contrast image with the following properties: irregular lighting and brightness gradient. Some experimental results are presented to illustrate the performance of the proposed algorithm.
jufoid=84313
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The problem of increasing efficiency of blind image quality assessment is considered. No-reference image quality metrics both independently and as components of complex image processing systems are employed in various application areas where images are the main carriers of information. Meanwhile, existing no-reference metrics have a significant drawback characterized by a low adequacy to image perception by human visual system (HVS). Many well-known no-reference metrics are analyzed in our paper for several image databases. A method of combining several no-reference metrics based on artificial neural networks is proposed based on multi-database verification approach. The effectiveness of the proposed approach is confirmed by extensive experiments.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
[Context]: Communication plays an important role in any development process. However, communication overhead has been rarely compared among development processes. [Objective]: The goal of this work is to compare the communication overhead and the different channels applied in three agile processes (XP, Scrum, Scrum with Kanban) and in an unstructured process. [Method]: We designed an empirical study asking four teams to develop the same application with the four development processes, and we compare the communication overhead among them. [Results]: As expected, face-to-face communication is most frequently employed in the teams. Scrum with Kanban turned out to be the process that requires the least communication. Unexpectedly, despite requiring much more time to develop the same application, the unstructured process required comparable communication overhead (25% of the total development time) as the agile processes.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Depending on one's viewpoint, a generic standards-compatible web browser supports three, four or five built-in application rendering and programming models. In this paper, we provide an overview of the built-in client-side web application architectures. While the dominance of the base HTML/CSS/JS technologies cannot be ignored, we foresee Web Components and WebGL gaining popularity as the world moves towards more complex and even richer web applications, including systems supporting virtual and augmented reality.
EXT="Taivalsaari, Antero"
EXT="Mikkonen, Tommi"
jufoid=69204
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We present a comparative split-half resampling analysis of various data driven feature selection and classification methods for the whole brain voxel-based classification analysis of anatomical magnetic resonance images. We compared support vector machines (SVMs), with or without filter based feature selection, several embedded feature selection methods and stability selection. While comparisons of the accuracy of various classification methods have been reported previously, the variability of the out-of-training sample classification accuracy and the set of selected features due to independent training and test sets have not been previously addressed in a brain imaging context. We studied two classification problems: 1) Alzheimer’s disease (AD) vs. normal control (NC) and 2) mild cognitive impairment (MCI) vs. NC classification. In AD vs. NC classification, the variability in the test accuracy due to the subject sample did not vary between different methods and exceeded the variability due to different classifiers. In MCI vs. NC classification, particularly with a large training set, embedded feature selection methods outperformed SVM-based ones with the difference in the test accuracy exceeding the test accuracy variability due to the subject sample. The filter and embedded methods produced divergent feature patterns for MCI vs. NC classification that suggests the utility of the embedded feature selection for this problem when linked with the good generalization performance. The stability of the feature sets was strongly correlated with the number of features selected, weakly correlated with the stability of classification accuracy, and uncorrelated with the average classification accuracy.
EXT="Tohka, Jussi"
Research output: Contribution to journal › Article › Scientific › peer-review
Gaze data processing is an important and necessary step in gaze-based applications. This study focuses on the comparison of several gaze-to-object mapping algorithms using various dwell times for selection and presenting targets of several types and sizes. Seven algorithms found in literature were compared against two newly designed algorithms. The study revealed that a fractional mapping algorithm (known) has produced the highest rate of correct selections and fastest selection times, but also the highest rate of incorrect selections. The dynamic competing algorithm (designed) has shown the next best result, but also high rate of incorrect selections. A small impact on the type of target to the calculated statistics has been observed. A strictly centered gazing has helped to increase the rate of correct selections for all algorithms and types of targets. The directions for further mapping algorithms improvement and future investigation have been explained.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Research on the indicators of student performance in introductory programming courses has traditionally focused on individual metrics and specific behaviors. These metrics include the amount of time and the quantity of steps such as code compilations, the number of completed assignments, and metrics that one cannot acquire from a programming environment. However, the differences in the predictive powers of different metrics and the cross-metric correlations are unclear, and thus there is no generally preferred metric of choice for examining time on task or effort in programming. In this work, we contribute to the stream of research on student time on task indicators through the analysis of a multi-source dataset that contains information about students' use of a programming environment, their use of the learning material as well as self-reported data on the amount of time that the students invested in the course and per-Assignment perceptions on workload, educational value and difficulty. We compare and contrast metrics from the dataset with course performance. Our results indicate that traditionally used metrics from the same data source tend to form clusters that are highly correlated with each other, but correlate poorly with metrics from other data sources. Thus, researchers should utilize multiple data sources to gain a more accurate picture of students' learning.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Video-based human-computer interaction has received increasing interest over the years. However, earlier research has been mainly focusing on technical characteristics of different methods rather than on user performance and experiences in using computer vision technology. This study aims to investigate performance characteristics of novice users and their subjective experiences in typing text with several video-based pointing and selection techniques. In Experiment 1, eye tracking and head tracking were applied for the task of pointing at the keys of a virtual keyboard. The results showed that gaze pointing was significantly faster but also more erroneous technique as compared with head pointing. Self-reported subjective ratings revealed that it was generally better, faster, more pleasant and efficient to type using gaze pointing than head pointing. In Experiment 2, mouth open and brows up facial gestures were utilized for confirming the selection of a given character. The results showed that text entry speed was approximately the same for both selection techniques, while mouth interaction caused significantly fewer errors than brow interaction. Subjective ratings did not reveal any significant differences between the techniques. Possibilities for design improvements are discussed.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Trust-region methods have yielded state-of-the-art results in policy search. A common approach is to use KL-divergence to bound the region of trust resulting in a natural gradient policy update. We show that the natural gradient and trust region optimization are equivalent if we use the natural parameterization of a standard exponential policy distribution in combination with compatible value function approximation. Moreover, we show that standard natural gradient updates may reduce the entropy of the policy according to a wrong schedule leading to premature convergence. To control entropy reduction we introduce a new policy search method called compatible policy search (COPOS) which bounds entropy loss. The experimental results show that COPOS yields state-of-the-art results in challenging continuous control tasks and in discrete partially observable tasks.
Research output: Contribution to journal › Article › Scientific › peer-review
One of the main approaches to additional lossless compression of JPEG images is decoding of quantized values of discrete cosine transform (DCT) coefficients and further more effective recompression of the coefficients. Values of amplitudes of DCT coefficients are highly correlated and it is possible to effectively compress them. At the same time, signs of DCT coefficients, which occupy up to 20% of compressed image, are often considered unpredictable. In the paper, a new and effective method for compression of signs of quantized DCT coefficients is proposed. The proposed method takes into account both correlation between DCT coefficients of the same block and correlation between DCT coefficients of neighbor blocks. For each of 64 DCT coefficients, positions of 3 reference coefficients inside the block are determined and stored in the compressed file. Four reference coefficients with fixed positions are used from the neighbor blocks. For all reference coefficients, 15 frequency models to predict signs of a given coefficient are used. All 7 probabilities (that the sign is negative) are mixed by logistic mixing. For test set of JPEG images, we show that the proposed method allows compressing signs of DCT coefficients by 1.1 ⋯ 1.3 times, significantly outperforming nearest analogues.
jufoid=84313
EXT="Lukin, Vladimir"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The authors consider the problem of compressive sensed video recovery via iterative thresholding algorithm. Traditionally, it is assumed that some fixed sparsifying transform is applied at each iteration of the algorithm. In order to improve the recovery performance, at each iteration the thresholding could be applied for different transforms in order to obtain several estimates for each pixel. Then the resulting pixel value is computed based on obtained estimates using simple averaging. However, calculation of the estimates leads to significant increase in reconstruction complexity. Therefore, the authors propose a heuristic approach, where at each iteration only one transform is randomly selected from some set of transforms. First, they present simple examples, when block-based 2D discrete cosine transform is used as the sparsifying transform, and show that the random selection of the block size at each iteration significantly outperforms the case when fixed block size is used. Second, building on these simple examples, they apply the proposed approach when video block-matching and 3D filtering (VBM3D) is used for the thresholding and show that the random transform selection within VBM3D allows to improve the recovery performance as compared with the recovery based on VBM3D with fixed transform.
EXT="Belyaev, Evgeny"
Research output: Contribution to journal › Article › Scientific › peer-review
Compressive sensing (CS) is a recently emerging technique and an extensively studied problem in signal and image processing, which suggests a new framework for the simultaneous sampling and compression of sparse or compressible signals at a rate significantly below the Nyquist rate. Maybe, designing an effective regularization term reflecting the image sparse prior information plays a critical role in CS image restoration. Recently, both local smoothness and nonlocal self-similarity have led to superior sparsity prior for CS image restoration. In this paper, first, an adaptive curvelet thresholding criterion is developed, trying to adaptively remove the perturbations appeared in recovered images during CS recovery process, imposing sparsity. Furthermore, a new sparsity measure called joint adaptive sparsity regularization (JASR) is established, which enforces both local sparsity and nonlocal 3-D sparsity in transform domain, simultaneously. Then, a novel technique for high-fidelity CS image recovery via JASR is proposed - CS-JASR. To efficiently solve the proposed corresponding optimization problem, we employ the split Bregman iterations. Extensive experimental results are reported to attest the adequacy and effectiveness of the proposed method comparing with the current state-of-the-art methods in CS image restoration.
Research output: Contribution to journal › Article › Scientific › peer-review
In this paper, we present a designer-configurable, resource efficient FPGA architecture for OFDM system implementation. Our design achieves a significant improvement in resource efficiency for a given data rate. This efficiency improvement is achieved through careful analysis of how FFT computation is performed within the context of OFDM systems, and streamlining memory management and control logic based on this analysis. In particular, our OFDM-targeted FFT design eliminates redundant buffer memory, and simplifies control logic to save FPGA resources. We have synthesized and tested our design using the Xilinx ISE 13.4 synthesis tool, and compared the results with the Xilinx FFT v7.1, which is a widely used commercial FPGA IP core. We have demonstrated that our design provides at least 8.8% enhancement in terms of resource efficiency compared to Xilinx FFT v7.1 when it is embedded within the same OFDM configuration.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The Manufacturing Enterprise Solutions Association (MESA) provided the abstract and general definition of the Manufacturing Execution Systems (MES). A dedicated function has been reserved for the data collection activities. In this matter, the Cloud Collaborative Manufacturing Networks (C2NET) project tends to provide a cloud based platform for hosting the interactions of the supply chain in a collaborative network. Within the architecture of the C2NET project, a Data Collection Framework (DCF) is designed to fulfill the function of data collection. This allows the companies to provide their data, which can be both enterprise and Internet of Things (IoT) devices type of data to the platform for further use. The collection of the data is achieved by a specific third party application, i.e., the Legacy System Hub (LSH). This research work presents the approach of configuring and visualizing the data resources in the C2NET platform. This approach employs the web-based applications and the help of the LSH. This permits the C2NET platform to adapt to any kind of third party application, which manipulates enterprise data, following the generic and flexible solution of this approach.
INT=aut,"Jose, L."
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Edgewrite is a text entry method where the user follows the edges of a physical guiding rectangle to enter corner sequences that are interpreted as characters. The original Edgewrite character set resembles the Latin alphabet and includes explicit character segmentation by lifting the stylus (or centering the joystick, etc). We present a variant of Edgewrite that we call the continuous Edgewrite. It relies on a dictionary instead of user's character segmentation to disambiguate words. New users can use the continuous Edgewrite with the help of an interactive visualization of possible continuations while writing. In a 6-session user study we measured initial text transcription performance (increased from 1 to 5.4 wpm) and the ratio of observed explicit segmentations to optimal continuous writing (decreased from 2.5 to 1.5). These results show that it is possible to learn to use the continuous writing mode, but also that the learning takes some time.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we consider continuum approach for high-cycle fatigue in the case where life-time is finite. The method is based on differential equations and all basic concepts are explained. A stress history is assumed to be a stochastic process and this leads us to the theory of stochastic differential equations. The life-time is a quantity, which tells us when the breakdown of the material happens. In this method, it is naturally a random variable. The basic assumption is, that the distribution of the life-time is log-normal or Weibull. We give a numerical basic example to demonstrate the method.
Research output: Contribution to journal › Article › Scientific › peer-review
The capability to model dynamic aspects of safety-critical systems, such as sequence or stochastic dependence of events, is one important requirement for safety analysis techniques. State Event Fault Tree Analysis, Dynamic Fault Tree Analyis, and Fault Tree Analysis combined with Markov Chains Analysis have been developed to fulfill these requirements, but they are still not widely accepted and used in practice. In order to investigate the reasons behind this low usage, we conducted two controlled experiments. The goal of the experiments was to analyze and compare applicability and efficiency in State Event Fault Tree analysis versus Dynamic Fault Tree Analyis and Fault Tree Analysis combined with Markov Chains Analysis. The results of both experiments show that, notwithstanding the power of State Event Fault Tree Analysis, Dynamic Fault Tree Analyis is rated by participants as more applicable and is more efficient compared to State Event Fault Tree Analysis, which, in turn, is rated as more applicable but is less efficient than Fault Tree Analysis combined with Markov Chains Analysis. Two of the reasons investigated are the complexity of the notations used and the lack of tool support. Based on these results, we suggest strategies for enhancing State Event Fault Tree Analysis to overcome its weaknesses and increase its applicability and efficiency in modeling dynamic aspects of safety-critical systems.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we discuss conversions between integers and \tau-adic expansions and we provide efficient algorithms and hardware architectures for these conversions. The results have significance in elliptic curve cryptography using Koblitz curves, a family of elliptic curves offering faster computation than general elliptic curves. However, in order to enable these faster computations, scalars need to be reduced and represented using a special base-τ expansion. Hence, efficient conversion algorithms and implementations are necessary. Existing conversion algorithms require several complicated operations, such as multiprecision multiplications and computations with large rationals, resulting in slow and large implementations in hardware and microcontrollers with limited instruction sets. Our algorithms are designed to utilize only simple operations, such as additions and shifts, which are easily implementable on practically all platforms. We demonstrate the practicability of the new algorithms by implementing them on Altera Stratix ∥ FPGAs. The implementations considerably improve both computation speed and required area compared to the existing solutions.
Research output: Contribution to journal › Article › Scientific › peer-review
We propose shearlet decomposition based light field (LF) reconstruction and filtering techniques for mitigating artifacts in the visualized contents of 3D multiview displays. Using the LF reconstruction capability, we first obtain the densely sampled light field (DSLF) of the scene from a sparse set of view images. We design the filter via tiling the Fourier domain of epipolar image by shearlet atoms that are directionally and spatially localized versions of the desired display passband. In this way, it becomes possible to process the DSLF in a depth-dependent manner. That is, the problematic areas in the 3D scene that are outside of the display depth of field (DoF) can be selectively filtered without sacrificing high details in the areas near the display, i.e. inside the DoF. The proposed approach is tested on a synthetic scene and the improvements achieved by means of the quality of the visualized content are verified, where the visualization process is simulated using a geometrical optics model of the human eye.
jufoid=84313
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The energy efficiency of modern MPSoCs is enhanced by complex hardware features such as Dynamic Voltage and Frequency Scaling (DVFS) and Dynamic Power Management (DPM). This paper introduces a new method, based on convex problem solving, that determines the most energy efficient operating point in terms of frequency and number of active cores in an MPSoC. The solution can challenge the popular approaches based on never-idle (or As-Slow-As-Possible (ASAP)) and race-to-idle (or As-Fast-As-Possible (AFAP)) principles. Experimental data are reported using a Samsung Exynos 5410 MPSoC and show a reduction in energy of up to 27 % when compared to ASAP and AFAP.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Successful fine-grained image classification methods learn subtle details between visually similar (sub-)classes, but the problem becomes significantly more challenging if the details are missing due to low resolution. Encouraged by the recent success of Convolutional Neural Network (CNN) architectures in image classification, we propose a novel resolution-aware deep model which combines convolutional image super-resolution and convolutional fine-grained classification into a single model in an end-to-end manner. Extensive experiments on multiple benchmarks demonstrate that the proposed model consistently performs better than conventional convolutional networks on classifying fine-grained object classes in low-resolution images.
Research output: Contribution to journal › Article › Scientific › peer-review
Recent device shipment trends strongly indicate that the number of Web-enabled devices other than PCs and smart phones are growing rapidly. Marking the end of the dominant era of these two traditional device categories, people will soon commonly use various types of Internet-connected devices in their daily lives, where no single device will dominate. Since today's devices are mostly standalone and only stay in sync in limited ways, new approaches are needed for mastering the complexity arising from the world of many types of devices, created by different manufacturers and implementing competing standards. Today, the most common denominator for dealing with the differences is using clouds. Unfortunately, however, while the cloud is well suited for numerous activities, there are also serious limitations, especially when considering systems that consist of numerous, battery-powered computing devices that have limited connectivity. In this paper, we provide an insight to our research where totally cloud-based orchestration of cooperating devices is partitioned into more local actions, where constant communication with the cloud backend can be at least partially omitted.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This study investigates the influence of culture on the use of a website intended for tracking exercise activities. The data was collected using an online survey with 258 respondents from three national backgrounds: Germany, the USA and Spain. In the analysis, the focus was on determining whether users' cultural background impacts their use and perception of the site, especially as concerns social networking and the sharing of content. The Spanish were most interested in social networking, collaboration and sharing content with others, whereas the German participants were the least interested in these activities. The applicability of Hofstede's cultural theory in the explanation of differences between national cultures in online community use is discussed.
EXT="Malinen, Sanna"
Research output: Contribution to journal › Article › Scientific › peer-review
In spite of the advances in theory of formal specifications, they have not gained a wide popularity in the software development industry. This could be due to difficulties in understanding them or positioning them into the current work practices, however, we believe that one major problem is that the tool support still does not make the use of the formal specifications easy enough for the software developer. We discuss the required functionality for comprehensive tool support for executable DisCo specifications, and propose a tool architecture based on database technology, and finally, discuss our implementation of the core part of the tool set.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this chapter, we discuss the state of the art and future challenges in adaptive stream mining systems for computer vision. Adaptive stream mining in this context involves the extraction of knowledge from image and video streams in real-time, and from sources that are possibly distributed and heterogeneous. With advances in sensor and digital processing technologies, we are able to deploy networks involving large numbers of cameras that acquire increasing volumes of image data for diverse applications in monitoring and surveillance. However, to exploit the potential of such extensive networks for image acquisition, important challenges must be addressed in efficient communication and analysis of such data under constraints on power consumption, communication bandwidth, and end-to-end latency. We discuss these challenges in this chapter, and we also discuss important directions for research in addressing such challenges using dynamic, data-driven methodologies.
Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review
In this paper, modern CPU architecture with several different cache levels is described and current CPU performance limitations such as frequency increase bounds are discussed. As changes to the currently existing architecture are usually proposed as a way of increasing CPU performance, data rates of the internal and external CPU interfaces must be known. This information would help to assess the applicability of proposed solutions and to optimize them. This paper is aimed at obtaining real values of traffic on an L2–L3 cache interface inside a CPU and a CPU–RAM bus load, as well as showing the dependences of the total traffic on the studied interfaces on the number of active cores, CPU frequency, and test type. A measurement methodology using an Intel Performance Counter Monitor is provided and the equations used to obtain data rates from the internal CPU counters are explained. Both real-life and synthetic tests are described. The dependence of total traffic on the number of active cores and the dependence of total traffic on CPU frequency are provided as plots. The dependence of total traffic on test type is provided as a bar plot for multiple CPU frequencies.
INT=elt,"Komar, M. S."
Research output: Contribution to journal › Article › Scientific › peer-review
In this paper, a computational color constancy method is proposed via estimating the illuminant chromaticity in a scene by pooling from many local estimates. To this end, first, for each image in a dataset, we form an image pyramid consisting of several scales of the original image. Next, local patches of certain size are extracted from each scale in this image pyramid. Then, a convolutional neural network is trained to estimate the illuminant chromaticity per-patch. Finally, two more consecutive trainings are conducted, where the estimation is made per-image via taking the mean (1st training) and median (2nd training) of local estimates. The proposed method is shown to outperform the state-of-the-art in a widely used color constancy dataset.
jufoid=57423
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Recently, the use of neural networks for image classification has become widely spread. Thanks to the availability of increased computational power, better performing architectures have been designed, such as the Deep Neural networks. In this work, we propose a novel image representation framework exploiting the Deep p- Fibonacci scattering network. The architecture is based on the structured p-Fibonacci scattering over graph data. This approach allows to provide good accuracy in classification while reducing the computational complexity. Experimental results demonstrate that the performance of the proposed method is comparable to state-of-the-art unsupervised methods while being computationally more efficient.
jufoid=84313
EXT="Battisti, F."
EXT="Carli, M."
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Developing accurate financial analysis tools can be useful both for speculative trading, as well as for analyzing the behavior of markets and promptly responding to unstable conditions ensuring the smooth operation of the financial markets. This led to the development of various methods for analyzing and forecasting the behaviour of financial assets, ranging from traditional quantitative finance to more modern machine learning approaches. However, the volatile and unstable behavior of financial markets forbids the accurate prediction of future prices, reducing the performance of these approaches. In contrast, in this paper we propose a novel price trailing method that goes beyond traditional price forecasting by reformulating trading as a control problem, effectively overcoming the aforementioned limitations. The proposed method leads to developing robust agents that can withstand large amounts of noise, while still capturing the price trends and allowing for taking profitable decisions.
EXT="Tefas, Anastasios"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Forecasting time series has several applications in various domains. The vast amount of data that are available nowadays provide the opportunity to use powerful deep learning approaches, but at the same time pose significant challenges of high-dimensionality, velocity and variety. In this paper, a novel logistic formulation of the well-known Bag-of-Features model is proposed to tackle these challenges. The proposed method is combined with deep convolutional feature extractors and is capable of accurately modeling the temporal behavior of time series, forming powerful forecasting models that can be trained in an end-to-end fashion. The proposed method was extensively evaluated using a large-scale financial time series dataset, that consists of more than 4 million limit orders, outperforming other competitive methods.
EXT="Tefas, Anastasios"
EXT="Iosifidis, Alexandros"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper examines how the demographic attributes and extra-game habits of players of a Massively Multiplayer Online Role-Playing Game (MMORPG) predict the accumulated capital of their avatars. An online survey (N=905) was conducted amidst the players of Final Fantasy XIV (FFXIV). Four types of capital were measured to map out the concrete and intangible resources of the avatars; social, economic, cultural and symbolic. The results show that weekly time spent playing the game is the strongest predictor of avatar capital and was associated with all types of capital. Time subscribed to the game was associated with cultural, economic, symbolic and bonding social capital. Social capital was found to be highest amongst both young and female players. Forum activity was associated with symbolic capital.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Our workshop has three primary goals. The first goal is community building: we want to get text entry researchers that are active in different communities into one place. Our second goal is to promote CHI as a natural and compelling focal point for all kinds of text entry research. The third goal is to discuss some difficult issues that are hard or near impossible to handle within the traditional format of research papers.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Socially interactive technologies are emerging as one of the predominant technologies of the future. In this workshop, we aim to discuss the emerging field of Social Robotic technologies with a particular focus on interaction design methodologies used in the design process. The workshop will investigate how researchers have approached designing social robots and what we can learn from the interaction design field for future designs. The main activities of the workshop will encompass two interactive sessions and a discussion panel on approaches to inspire the design of socially interactive robots. In particular, we focus on experience-driven design methods involving rituals and memorable experiences with social robots.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The present aim was to study the preference of tactile feedback stimulations given by non-physical (i.e., solid) piezo-actuated buttons. Participants (n=16) ranked 16 different tactile feedback stimuli varied by 4 output delays and 4 vibration durations. The results showed that the mean ranks of the stimuli differed significantly from each other. The timing parameters of delay and duration interacted with each other, for example, so that preference of certain vibration duration fluctuated in response to different output delays. Using a very short time window (i.e., 10-453 ms) combining both delay and duration parameters of the feedback could result either in favorable or significantly less favorable subjective experience. The results suggest that a preferred perception of tactile feedback from non-physical buttons requires careful design and controlling of the timing parameters.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The paper proposes a method for the detection of bubble-like transparent objects in a liquid. The detection problem is non-trivial since bubble appearance varies considerably due to different lighting conditions causing contrast reversal and multiple interreflections. We formulate the problem as the detection of concentric circular arrangements (CCA). The CCAs are recovered in a hypothesize-optimize-verify framework. The hypothesis generation is based on sampling from the partially linked components of the non-maximum suppressed responses of oriented ridge filters, and is followed by the CCA parameter estimation. Parameter optimization is carried out by minimizing a novel cost-function. The performance was tested on gas dispersion images of pulp suspension and oil dispersion images. The mean error of gas/oil volume estimation was used as a performance criterion due to the fact that the main goal of the applications driving the research was the bubble volume estimation. The method achieved 28 and 13 % of gas and oil volume estimation errors correspondingly outperforming the OpenCV Circular Hough Transform in both cases and the WaldBoost detector in gas volume estimation.
Research output: Contribution to journal › Article › Scientific › peer-review
A machine learning method for the automatic detection of pronunciation errors made by non-native speakers of English is proposed. It consists of training word-specific binary classifiers on a collected dataset of isolated words with possible pronunciation errors, typical for Finnish native speakers. The classifiers predict whether the typical error is present in the given word utterance. They operate on sequences of acoustic features, extracted from consecutive frames of an audio recording of a word utterance. The proposed architecture includes a convolutional neural network, a recurrent neural network, or a combination of the two. The optimal topology and hyperpa-rameters are obtained in a Bayesian optimisation setting using a tree-structured Parzen estimator. A dataset of 80 words uttered naturally by 120 speakers is collected. The performance of the proposed system, evaluated on a well-represented subset of the dataset, shows that it is capable of detecting pronunciation errors in most of the words (46/49) with high accuracy (mean accuracy gain over the zero rule 12.21 percent points).
jufoid=58177
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Haptics has been an integral part of multimodal systems in Human Computer Interaction (HCI). The ability to touch and sense virtual components of any system has long been the holy grail of HCI, which is particularly useful in mission critical environments where other modalities are weakened by environmental noise. Haptics also compliments most modalities of interaction by reinforcing the intimate and personal aspect of interaction. Haptics becomes much more important in environments that prove to be far too noisy for audio feedback.The driving environment is one such area, which the addition of haptics is not just additive, but critical in HCI. However, most of the research on haptic feedback in the car has been conducted using vibro-tactile feedback. In this paper, we present a system in which we have developed a novel haptic feedback environment using pneumatic and vibrotactile technologies, to facilitate in carcommunication, using the In-vehicle Infotainment System. Our aim was to build on the user haptic perception and experience the advance multimodal interaction system by utilizing available feedback techniques in, in-car interaction. The qualitative results of our study show that haptic feedback has great potential for safety and communication use, but the difficulty in interpreting haptic signals requires additional translation means ('semantic linkages'), to support the right interpretation of the haptic information.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Context: DevOps is considered important in the ability to frequently and reliably update a system in operational state. DevOps presumes cross-functional collaboration and automation between software development and operations. DevOps adoption and implementation in companies is non-trivial due to required changes in technical, organisational and cultural aspects. Objectives: This exploratory study presents detailed descriptions of how DevOps is implemented in practice. The context of our empirical investigation is web application and service development in small and medium sized companies. Method: A multiple-case study was conducted in five different development contexts with successful DevOps implementations since its benefits, such as quick releases and minimum deployment errors, were achieved. Data was mainly collected through interviews with 26 practitioners and observations made at the companies. Data was analysed by first coding each case individually using a set of predefined themes and thereafter perform a cross-case synthesis. Results: Our analysis yielded some of the following results: (i) software development team attaining ownership and responsibility to deploy software changes in production is crucial in DevOps. (ii) toolchain usage and support in deployment pipeline activities accelerates the delivery of software changes, bug fixes and handling of production incidents. (ii) the delivery speed to production is affected by context factors, such as manual approvals by the product owner (iii) steep learning curve for new skills is experienced by both software developers and operations staff, who also have to cope with working under pressure. Conclusion: Our findings contributes to the overall understanding of DevOps concept, practices and its perceived impacts, particularly in small and medium sized companies. We discuss two practical implications of the results.
EXT="Mikkonen, Tommi"
Research output: Contribution to journal › Article › Scientific › peer-review
DevOps and continuous development are getting popular in the software industry. Adopting these modern approaches in regulatory environments, such as medical device software, is not straightforward because of the demand for regulatory compliance. While DevOps relies on continuous deployment and integration, regulated environments require strict audits and approvals before releases. Therefore, the use of modern development approaches in regulatory environments is rare, as is the research on the topic. However, as software is more and more predominant in medical devices, modern software development approaches become attractive. This paper discusses the fit of DevOps for regulated medical device software development. We examine two related standards, IEC 62304 and IEC 82304-1, for obstacles and benefits of using DevOps for medical device software development. We found these standards to set obstacles for continuous delivery and integration. Respectively, development tools can help fulfilling the requirements of traceability and documentation of these standards.
EXT="Kuusinen, Kati"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper we propose a novel framework for human action recognition based on Bag of Words (BoWs) action representation, that unifies discriminative codebook generation and discriminant subspace learning. The proposed framework is able to, naturally, incorporate several (linear or non-linear) discrimination criteria for discriminant BoWs-based action representation. An iterative optimization scheme is proposed for sequential discriminant BoWs-based action representation and codebook adaptation based on action discrimination in a reduced dimensionality feature space where action classes are better discriminated. Experiments on five publicly available data sets aiming at different application scenarios demonstrate that the proposed unified approach increases the codebook discriminative ability providing enhanced action classification performance.
Research output: Contribution to journal › Article › Scientific › peer-review
Speech separation algorithms are faced with a difficult task of producing high degree of separation without containing unwanted artifacts. The time-frequency (T-F) masking technique applies a real-valued (or binary) mask on top of the signal's spectrum to filter out unwanted components. The practical difficulty lies in the mask estimation. Often, using efficient masks engineered for separation performance leads to presence of unwanted musical noise artifacts in the separated signal. This lowers the perceptual quality and intelligibility of the output. Microphone arrays have been long studied for processing of distant speech. This work uses a feed-forward neural network for mapping microphone array's spatial features into a T-F mask. Wiener filter is used as a desired mask for training the neural network using speech examples in simulated setting. The T-F masks predicted by the neural network are combined to obtain an enhanced separation mask that exploits the information regarding interference between all sources. The final mask is applied to the delay-and-sum beamformer (DSB) output. The algorithm's objective separation capability in conjunction with the separated speech intelligibility is tested with recorded speech from distant talkers in two rooms from two distances. The results show improvement in instrumental measure for intelligibility and frequency-weighted SNR over complex-valued non-negative matrix factorization (CNMF) source separation approach, spatial sound source separation, and conventional beamforming methods such as the DSB and minimum variance distortionless response (MVDR).
Research output: Contribution to journal › Article › Scientific › peer-review
Background: Pull requests are a common practice for making contributions and reviewing them in both open-source and industrial contexts.
Objective: Our goal is to understand whether quality flaws such as code smells, anti-patterns, security vulnerabilities, and coding style violations in a pull request's code affect the chance of its acceptance when reviewed by a maintainer of the project.
Method: We conducted a case study among 28 Java open-source projects, analyzing the presence of 4.7 M code quality flaws in 36 K pull requests. We analyzed further correlations by applying logistic regression and six machine learning techniques. Moreover, we manually validated 10% of the pull requests to get further qualitative insights on the importance of quality issues in cases of acceptance and rejection.
Results: Unexpectedly, quality flaws measured by PMD turned out not to affect the acceptance of a pull request at all. As suggested by other works, other factors such as the reputation of the maintainer and the importance of the delivered feature might be more important than other qualities in terms of pull request acceptance.
Conclusions:. Researchers have already investigated the influence of the developers’ reputation and the pull request acceptance. This is the first work investigating code style violations and specifically PMD rules. We recommend that researchers further investigate this topic to understand if different measures or different tools could provide some useful measures.
EXT="Lenarduzzi, Valentina"
INT=comp,"Nikkola, Vili"
Research output: Contribution to journal › Article › Scientific › peer-review
Background: The migration from a monolithic system to microservices requires a deep refactoring of the system. Therefore, such a migration usually has a big economic impact and companies tend to postpone several activities during this process, mainly to speed up the migration itself, but also because of the demand for releasing new features.
Objective: We monitored the technical debt of an SME while it migrated from a legacy monolithic system to an ecosystem of microservices. Our goal was to analyze changes in the code technical debt before and after the migration to microservices.
Method: We conducted a case study analyzing more than four years of the history of a twelve-year-old project (280K Lines of Code) where two teams extracted five business processes from the monolithic system as microservices. For the study, we first analyzed the technical debt with SonarQube and then performed a qualitative study with company members to understand the perceived quality of the system and the motivation for possibly postponed activities.
Results: The migration to microservices helped to reduce the technical debt in the long run. Despite an initial spike in the technical debt due to the development of the new microservice, after a relatively short period of time the technical debt tended to grow slower than in the monolithic system.
EXT="Lenarduzzi, Valentina"
Research output: Contribution to journal › Review Article › Scientific › peer-review
Cloud computing has evolved from a promising concept to one of the fastest growing segments of the IT industry. However, many businesses and individuals continue to view cloud computing as a technology that risks exposing their data to unauthorized users. We introduce a data confidentiality and integrity protection mechanism for Infrastructure-as-a-Service (IaaS) clouds, which relies on trusted computing principles to provide transparent storage isolation between IaaS clients. We also address the absence of reliable data sharing mechanisms, by providing an XML-based language framework which enables clients of IaaS clouds to securely share data and clearly define access rights granted to peers. The proposed improvements have been prototyped as a code extension for a popular cloud platform.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we present a novel rotation-invariant and computationally efficient texture descriptor called Dominant Rotated Local Binary Pattern (DRLBP). A rotation invariance is achieved by computing the descriptor with respect to a reference in a local neighborhood. A reference is fast to compute maintaining the computational simplicity of the Local Binary Patterns (LBP). The proposed approach not only retains the complete structural information extracted by LBP, but it also captures the complimentary information by utilizing the magnitude information, thereby achieving more discriminative power. For feature selection, we learn a dictionary of the most frequently occurring patterns from the training images, and discard redundant and non-informative features. To evaluate the performance we conduct experiments on three standard texture datasets: Outex12, Outex 10 and KTH-TIPS. The performance is compared with the state-of-the-art rotation invariant texture descriptors and results show that the proposed method is superior to other approaches.
Research output: Contribution to journal › Article › Scientific › peer-review
In this paper, we propose a novel method that performs dynamic action classification by exploiting the effectiveness of the Extreme Learning Machine (ELM) algorithm for single hidden layer feedforward neural networks training. It involves data grouping and ELM based data projection in multiple levels. Given a test action instance, a neural network is trained by using labeled action instances forming the groups that reside to the test sample's neighborhood. The action instances involved in this procedure are, subsequently, mapped to a new feature space, determined by the trained network outputs. This procedure is performed multiple times, which are determined by the test action instance at hand, until only a single class is retained. Experimental results denote the effectiveness of the dynamic classification approach, compared to the static one, as well as the effectiveness of the ELM in the proposed dynamic classification setting.
Research output: Contribution to journal › Article › Scientific › peer-review
Patching a program during its execution without restarting is called dynamic software updating (DSU). DSU is well acknowledged in research, but rarely applied in practice as witnessed by constant need for reboots and restarts of both applications as well as operating systems. This raises the question of how well DSU related techniques are supported in education. In this paper, we review how the major software engineering and education guides acknowledge dynamic software updating techniques. Our analysis indicates that although DSU is not explicitly mentioned in the guides, the need is already well motivated and many DSU concepts are implicitly supported. Based on this, we argue that DSU could be introduced as an optional topic in software engineering studies.
JUFOID=67349
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Print interpreting supports people with a hearing disability by giving them access to spoken language. In print interpreting, the interpreter types the spoken text in real time for the hard-of-hearing client to read. This results in dynamic text presentation. An eye movement study was conducted to compare two types of dynamic text presentation formats in print interpreting: letter-by-letter and word-by-word. Gaze path analysis with 20 hearing participants showed different types of reading behaviour during reading of two pieces of text in these two presentation formats. Our analysis revealed that the text presentation format has a significant effect on reading behaviour. Rereading and regressions occurred significantly more often with the word-by-word format than with the letter-by-letter format. We also found a significant difference between the number of regressions starting at the words that end a sentence and that of regressions starting at all other words. The frequency of rereading was significantly higher for incorrectly typed or abbreviated words than for the other words. Analysis of the post-test questionnaire found almost equal acceptance of the word-by-word and letter-by-letter formats by the participants. A follow-up study with 18 hard-of-hearing participants showed a similar trend in results. The findings of this study highlight the importance of developing print interpreting tools that allow the interpreter and the client to choose the options that best facilitate the communication. They also bring up the need to develop new eye movement metrics for analysing the reading of dynamic text, and provide first results on a new dynamic presentation context.
Research output: Contribution to journal › Article › Scientific › peer-review
This paper outlines the design and development process of the Dynamic Audio Motion (Dynamo) concept. The Dynamo audio engine was developed for driving dynamic sound interaction states via custom made finite state machine. Further, a generative sound design approach was employed for creating sonic and musical structures. Designed dynamic sound interactions were tested in an embodied information wall application with endusers. During the testing situation, end-users engaged in a reflective creation process providing valuable insight of their experiences of using the system. In this paper we present key questions driving the research, theoretical background, research approach, an audio engine development process, and end-user research activities. The results indicate that dynamic sound interactions supported people's personal, emotional, and creative needs in the design context.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Existing car navigation systems require visual or auditory attention. Providing the driver with directional cues could potentially increase safety. We conducted an experiment comparing directional haptic and non-speech audio cues to visual cueing in a navigation task. Participants (N=16) drove the Lane Change Test simulator with different navigational cues. The participants were to recognize the directional cue (left or right) by responding as fast as possible using a tablet. Reaction times and errors were measured. The participants were also interviewed about the different cues and filled up the NASA-TLX questionnaire. The results showed that in comparison to visual cues all the other cues were reacted to significantly faster. Haptic only cueing resulted in the most errors, but it was evaluated as the most pleasant and the least physically demanding. The results suggest that non-visual cueing could improve safety. Copyright is held by the owner/author(s).
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Studies in Escherichia coli using in vivo single-RNA detection and time-lapse confocal microscopy showed that transcription is a multiple rate-limiting steps process, in agreement with previous in vitro measurements. Here, from simulations of a stochastic model of transcription validated empirically that accounts for cell-to-cell variability in RNA polymerase (RNAP) numbers, we investigate the hypothesis that the cell-to-cell variability in RNA numbers due to RNAP variability differs with the promoter rate-limiting steps dynamics. We find that increasing the cell-to-cell variability in RNAP numbers increases the cell-to-cell diversity in RNA numbers, but the degree with which it increases is promoter kinetics dependent. Namely, promoters whose open complex formation is relatively longer lasting dampen more efficiently this noise propagation phenomenon. We conclude that cell-to-cell variability in RNA numbers due to variability in RNAP numbers is promoter-sequence dependent and, thus, evolvable.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Eye tracking enables automatic scrolling based on natural viewing behavior. We were interested in the effects of haptic feedback on gaze behavior and user experience. We conducted an experiment where haptic feedback was used to forewarn the reader that their gaze had entered an active scrolling area. Results show no statistical differences between conditions with or without haptic feedback on task time or gaze behavior. However, user experience varied a lot. Some participants were not able to associate the haptics and the scrolling. Those who understood the connection found the haptic feedback useful. Further research is required to find out a delay between the forewarning and the start of scrolling that is short enough to make the association but yet long enough to support the feeling of control and enjoyable user experience. Copyright is held by the owner/author(s).
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Purpose: To guide ultrasound-driven prostate photodynamic therapy using information from MRI-based treatment planning. Methods: Robust points matching (RPM) and thin plate splines (TPS) are used to solve correspondences and to map optimally positioned landmarks from MR images to transrectal ultrasound (TRUS) images. The algorithm uses a reduced number of anatomical markers that are initialized on the images. Results: Both phantom and patient data were used to evaluate precision and robustness of the method. Mean registration error (±standard deviation) was of 2.18. ±. 0.25. mm and 1.55. ±. 0.31. mm for patient prostate and urethra, respectively. Repeated tests with different markers initialization conditions showed that the quality of registration was neither influenced by the number of markers nor to the human observer. Conclusion: This method allows for satisfyingly accurate and robust non rigid registration of MRI and TRUS and provides practitioners with substantial help in mapping treatment planning from pre-operative MRI to interventional TRUS.
Research output: Contribution to journal › Article › Scientific › peer-review
This paper introduces a novel micro-force sensing approach utilizing an electroplated nickel microspring and a precision linear slider (PLS) for micro-tensile testing applications. After investigating the effects of friction forces in a PLS, an electroplated nickel microspring is designed, fabricated and integrated into the PLS, and the proposed micro-force sensor concept is validated through experimental results. The microspring fabricated in this paper is limited to forces up to 6 mN with the average sensitivity of 36.63 μN/μm. It is shown that the friction forces introduce uncertainties only to the forces less than 500 μN. The proposed approach allows the fabrication of micro-force sensors for the force ranges of up to tens of Millinewtons for different applications.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Experiencing stress, disturbing interruptions, loss of ability to concentrate, hurry and challenges to meet tight deadlines at work are very common in working life. At the same time, while variety of digital communication channels like instant messaging, video calls and social networking sites are getting more popular in working life, email is still intensively utilized work communication media. The goal of the empirical field study analyzing daily desktop computing of knowledge workers was to analyze association between email intensity in work time spending and subjectively experienced quality of work performance. It was found that while intensive email use does not impair subjectively experienced productivity, it may harm ability to concentrate, may increase forgetfulness and inability to solve problems at work effectively. Copyright is held by the owner/author(s). Publication rights licensed to ACM.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Emotional reactions to basic, artificial, yet carefully controllable point-light displays (PLDs) were investigated with ratings of valence, arousal, approachability and dominance. PLDs were varied by movement location (upper and lower) and intensity (10°, 20° and 30° angular change) for angular upward and downward movements. Half of participants (N =28) were told that PLDs were related to face while to other half nothing was hinted. Results showed that 20° and 30° angle lower location upward movements were rated as significantly more pleasant, relaxing and approachable than corresponding upper location downward movements. Informed participants rated 20° and 30° angle lower movements as significantly more controllable than corresponding upper movements. Results are important from many perspectives, like for understanding human perceptual mechanisms. When using PLDs only a small amount of information needs to be transmitted. This enables low bandwidth requirements. As PLD visualizations are simple, there is no need for high-definition displays.
Research output: Contribution to journal › Article › Scientific › peer-review
The maritime industry is experiencing a new era of digital transformation. At the same time as the number of cyberattacks and cybersecurity incidents are increasing, cybersecurity awareness and incident reporting in this sector remains low. In this paper, we describe a cybersecurity incident reporting system for the maritime industry that aims to address this issue. The work focuses on autonomous and unmanned vessels, but can be equally applied to other areas of the maritime industry. The proposed approach has been evaluated experimentally and the results demonstrate its applicability and feasibility.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Sound event detection systems typically consist of two stages: Extracting hand-crafted features from the raw audio waveform, and learning a mapping between these features and the target sound events using a classifier. Recently, the focus of sound event detection research has been mostly shifted to the latter stage using standard features such as mel spectrogram as the input for classifiers such as deep neural networks. In this work, we utilize end-to-end approach and propose to combine these two stages in a single deep neural network classifier. The feature extraction over the raw waveform is conducted by a feedforward layer block, whose parameters are initialized to extract the time-frequency representations. The feature extraction parameters are updated during training, resulting with a representation that is optimized for the specific task. This feature extraction block is followed by (and jointly trained with) a convolutional recurrent network, which has recently given state-of-the-art results in many sound recognition tasks. The proposed system does not outperform a convolutional recurrent network with fixed hand-crafted features. The final magnitude spectrum characteristics of the feature extraction block parameters indicate that the most relevant information for the given task is contained in 0 - 3 kHz frequency range, and this is also supported by the empirical results on the SED performance.
jufoid=58177
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We propose a combination of gaze pointing and head gestures for enhanced hands-free interaction. Instead of the traditional dwell-time selection method, we experimented with five simple head gestures: nodding, turning left/right, and tilting left/right. The gestures were detected from the eye-tracking data by a range-based algorithm, which was found accurate enough in recognizing nodding and leftdirected gestures. The gaze estimation accuracy did not noticeably suffer from the quick head motions. Participants pointed to nodding as the best gesture for occasional selections tasks and rated the other gestures as promising methods for navigation (turning) and functional mode switching (tilting). In general, dwell time works well for repeated tasks such as eye typing. However, considering multimodal games or transient interactions in pervasive and mobile environments, we believe a combination of gaze and head interaction could potentially provide a natural and more accurate interaction method.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we propose an optimization scheme aiming at optimal nonlinear data projection, in terms of Fisher ratio maximization. To this end, we formulate an iterative optimization scheme consisting of two processing steps: optimal data projection calculation and optimal class representation determination. Compared to the standard approach employing the class mean vectors for class representation, the proposed optimization scheme increases class discrimination in the reduced-dimensionality feature space. We evaluate the proposed method in standard classification problems, as well as on the classification of human actions and face, and show that it is able to achieve better generalization performance, when compared to the standard approach.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The classification of Human Epithelial (HEp-2) cells images, acquired through Indirect Immunofluorescence (IIF) microscopy, is an effective method to identify staining patterns in patient sera. Indeed it can be used for diagnostic purposes, in order to reveal autoimmune diseases. However, the automated classification of IIF HEp-2 cell patterns represents a challenging task, due to the large intra-class and the small inter-class variability. Consequently, recent HEp-2 cell classification contests have greatly spurred the development of new IIF image classification systems.Here we propose an approach for the automatic classification of IIF HEp-2 cell images by fusion of several texture descriptors by ensemble of support vector machines combined by sum rule. Its effectiveness is evaluated using the HEp-2 cells dataset used for the "Performance Evaluation of Indirect Immunofluorescence Image Analysis Systems" contest, hosted by the International Conference on Pattern Recognition in 2014: the accuracy on the testing set is 79.85%.The same dataset was used to test an ensemble of ternary-encoded local phase quantization descriptors, built by perturbation approaches: the accuracy on the training set is 84.16%. Finally, this ensemble was validated on 14 additional datasets, obtaining the best performance on 11 datasets.Our MATLAB code is available at https://www.dei.unipd.it/node/2357.
Research output: Contribution to journal › Article › Scientific › peer-review
Software development effort estimation is a very important issue in software engineering and several models have been defined to this end. In this paper, we carry out an empirical study on the estimation of software development effort broken down by phase, so that estimation can be used along the software development lifecycle. More specifically, our goal is twofold. At any given point in the software development lifecycle, we estimate the effort needed for the next phase. Also, we estimate the effort for the remaining part of the software development process. Our empirical study is based on historical data from the ISBSG database. The results show a set of statistically significant correlations between: (1) the effort spent in one phase and the effort spent in the following one, (2) the effort spent in a phase and the remaining effort, (3) the cumulative effort up to the current phase and the remaining effort. However, the results also show that these estimation models come with different degrees of goodness of fit. Finally, including further information, such as the functional size, does not significantly improve estimation quality.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper proposes a method for online estimation of time-varying room impulse responses (RIR) between multiple isolated sound sources and a far-field mixture. The algorithm is formulated as adaptive convolutive filtering in short-time Fourier transform (STFT) domain. We use the recursive least squares (RLS) algorithm for estimating the filter parameters due to its fast convergence rate, which is required for modeling rapidly changing RIRs of moving sound sources. The proposed method allows separation of reverberated sources from the far-field mixture given that their close-field signals are available. The evaluation is based on measuring unmixing performance (removal of reverberated source) using objective separation criteria calculated between the ground truth recording of the preserved sources and the unmixing result obtained with the proposed algorithm. We compare online and offline formulations for the RIR estimation and also provide evaluation with blind source separation algorithm only operating on the mixture signal.
jufoid=57409
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Programming models which specify an application as a network of independent computational elements have emerged as a promising paradigm for programming streaming applications. The antagonism between expressivity and analysability has led to a number of different such programming models, which provide different degrees of freedom to the programmer. One example are Kahn process networks (KPNs), which, due to certain restrictions in communication, can guarantee determinacy (their results are independent of timing by construction). On the other hand, certain dataflow models, such as the CAL Actor Language, allow non-determinacy and thus higher expressivity, however at the price of static analysability and thus a potentially less efficient implementation. In many cases, however, non-determinacy is not required (or even not desired), and relying on KPN for the implementation seems advantageous. In this paper, we propose an algorithm for classifying dataflow actors (i.e. computational elements) as KPN compatible or potentially not. For KPN compatible dataflow actors, we propose an automatic KPN translation method based on this algorithm. In experiments, we show that more than 75% of all mature actors of a standard multimedia benchmark suite can be classified as KPN compatible and that their execution time can be reduced by up to 1.97x using our proposed translation technique. Finally, in a manual classification effort, we validate these results and list different classes of KPN incompatibility.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Deep neural network (DNN) based acoustic modelling has been successfully used for a variety of automatic speech recognition (ASR) tasks, thanks to its ability to learn higher-level information using multiple hidden layers. This paper investigates the recently proposed exemplar-based speech enhancement technique using coupled dictionaries as a pre-processing stage for DNN-based systems. In this setting, the noisy speech is decomposed as a weighted sum of atoms in an input dictionary containing exemplars sampled from a domain of choice, and the resulting weights are applied to a coupled output dictionary containing exemplars sampled in the short-time Fourier transform (STFT) domain to directly obtain the speech and noise estimates for speech enhancement. In this work, settings using input dictionary of exemplars sampled from the STFT, Mel-integrated magnitude STFT and modulation envelope spectra are evaluated. Experiments performed on the AURORA-4 database revealed that these pre-processing stages can improve the performance of the DNN-HMM-based ASR systems with both clean and multi-condition training.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we propose a method for video summarization based on human activity description. We formulate this problem as the one of automatic video segment selection based on a learning process that employs salient video segment paradigms. For this one-class classification problem, we introduce a novel variant of the One-Class Support Vector Machine (OC-SVM) classifier that exploits subclass information in the OC-SVM optimization problem, in order to jointly minimize the data dispersion within each subclass and determine the optimal decision function. We evaluate the proposed approach in three Hollywood movies, where the performance of the proposed SOC-SVM algorithm is compared with that of the OC-SVM. Experimental results denote that the proposed approach is able to outperform OC-SVM-based video segment selection.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
There is a need to understand ways to enhance innovations in the construction industry. It is argued that suppliers have potential to develop new innovations, but they are largely neglected in earlier construction-related research. This research focuses on suppliers' role in construction innovations, and the aim of the research is to increase understanding of practices for exploiting suppliers' potential in that context. A qualitative, explanatory research strategy is employed in the context of construction industry in Finland. Eighteen interviews are conducted with contractors to discover experiences and practices related to suppliers' potential in construction innovations. The results reveal practices for exploiting supplier's potential in construction innovations. As a key contribution, the research shows that suppliers have an important role in construction innovation but exploitation of suppliers' potential is still rather underdeveloped.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The modelling of cognition is playing a major role in robotics. Indeed, robots need to learn, adapt and plan their actions in order to interact with their environment. To do so, approaches like embodiment and enactivism propose to ground sensorimotor experience in the robot's body to shape the development of cognition. In this work, we focus on the role of memory during learning in a closed loop. As sensorimotor contingencies, we consider a robot arm that moves a baby mobile toy to get visual reward. First, the robot explores the continuous sensorimotor space by associating visual stimuli to motor actions through motor babbling. After exploration, the robot uses the experience from its memory and exploits it, thus optimizing its motion to perceive more visual stimuli. The proposed approach uses Dynamic Field Theory and is integrated in the GummiArm, a 3D printed humanoid robot arm. The results indicate a higher visual neural activation after motion learning and show the benefits of an embodied babbling strategy.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The aim of this research was to explore the role of Schwartz's ten universal human values in the context of using products and services. Seventy-five participants were asked to qualitatively describe a product or service especially well in line with their values and a product or service in conflict with their values, and to evaluate them on a number of rating scales. The scales included 30 statements (three statements per universal value) probing the presence of each value in user experiences related to products and services and 10 statements studying the perceived importance of each value. The results showed that all the ten universal values were relevant in the evaluations of products and services both in line with the users' values and in conflict with the users' values. In the current sample, hedonism and self-direction were rated as the values most frequently present and most important in the evaluations of products and services in line with values. Power was rated as a moderately important value for products in conflict with values, but significantly less important for products in line with values. Achievement values were frequently reported in the qualitative descriptions, but they were less prominent in the quantitative data. The results suggest that the model of ten universal values is promising in understanding the role of users' value preferences in using products and services, and it seems to have potential for complementing the psychological needs approach in understanding user experience.
Research output: Contribution to journal › Article › Scientific › peer-review
The stability of software is a classical topic in software engineering. This research investigates stability of software architectures in terms of an object-oriented design principle presented by Robert C. Martin. The research approach is statistical: the design principle is evaluated with a time-series cross-sectional (TSCS) regression model. The empirical sample covers a release history from the Java library Vaadin. The empirical results establish that the design principle cannot be used to characterize the library. Besides delivering this negative empirical result, the research provides the necessary methodological background that is required to understand TSCS modeling.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Many web sites utilize deprecated software products that are no longer maintained by the associated software producers. This paper explores the question of whether an existing big data collection can be used to predict the likelihood of deprecated PHP releases based on different abstract components in modern web deployment stacks. Building on web intelligence, software security, and data-based industry rationales, the question is examined by focusing on the most popular domains in the contemporary web-facing Internet. Logistic regression is used for classification. Although statistical classification performance is modest, the results indicate that deprecated PHP releases are associated with Linux and other open source software components. Geographical variation is small. Besides these results, the paper contributes to the web intelligence research by evaluating the feasibility of existing big data collections for mass-scale fingerprinting.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Facial expressions are emotionally, socially and otherwise meaningful reflective signals in the face. Facial expressions play a critical role in human life, providing an important channel of nonverbal communication. Automation of the entire process of expression analysis can potentially facilitate human-computer interaction, making it to resemble mechanisms of human-human communication. In this paper, we present an ongoing research that aims at development of a novel spatiotemporal approach to expression classification in video. The novelty comes from a new facial representation that is based on local spatiotemporal feature descriptors. In particular, a combined dynamic edge and texture information is used for reliable description of both appearance and motion of the expression. Support vector machines are utilized to perform a final expression classification. The planned experiments will further systematically evaluate the performance of the developed method with several databases of complex facial expressions.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Actualizing positive social encounters remains both a key ends and means in many activities to foster a sense of community. Initiating encounters between strangers typically requires facilitative activities or artefacts, such as icebreakers or tickets-to-talk. However, there is little understanding of which designs are effective and why, and the broad design space remains largely underexplored. We address this challenge by presenting five candidates for inspirational design patterns on signaling social intentions and identifying impediments that deter commencement of encounters. The principles result from an extensive review of design cases and public art installations. Through focus groups and expert interviews, we assessed the perceived applicability and social acceptance of the proposed patterns. Three new design principles relating to the risks of initiating an encounter emerged through analyzing participant responses. These articulations of possible approaches and pitfalls for increasing conviviality may broaden the repertoire of, and support discussion between designers and others concerned with collocated social interaction.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
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.
Research output: Contribution to journal › Article › Scientific › peer-review
Farm detection using low resolution satellite images is an important topic in digital agriculture. However, it has not received enough attention compared to high-resolution images. Although high resolution images are more efficient for detection of land cover components, the analysis of low-resolution images are yet important due to the low-resolution repositories of the past satellite images used for timeseries analysis, free availability and economic concerns. The current paper addresses the problem of farm detection using low resolution satellite images. In digital agriculture, farm detection has significant role for key applications such as crop yield monitoring. Two main categories of object detection strategies are studied and compared in this paper; First, a two-step semi-supervised methodology is developed using traditional manual feature extraction and modelling techniques; the developed methodology uses the Normalized Difference Moisture Index (NDMI), Grey Level Co-occurrence Matrix (GLCM), 2-D Discrete Cosine Transform (DCT) and morphological features and Support Vector Machine (SVM) for classifier modelling. In the second strategy, high-level features learnt from the massive filter banks of deep Convolutional Neural Networks (CNNs) are utilised. Transfer learning strategies are employed for pretrained Visual Geometry Group Network (VGG-16) networks. Results show the superiority of the high-level features for classification of farm regions.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The service broker provides service providers with virtualized services that can be initialized rapidly and scaled up or down on demand. This demonstration paper describes how a service provider can set up a new video distribution service to end users with a diminutive effort. Our proposal makes use of Docker lightweight virtualization technologies that pack services in containers. This makes it possible to implement video coding and content delivery networks that are scalable and consume resources only when needed. The demonstration showcases a scenario where a video service provider sets up a new live video distribution service to end users. After the setup, live 720p30 video camera feed is encoded in real-time, streamed in HEVC MPEG-DASH format over CDN network, and accessed with a HbbTV compatible set-top-box. This end-to-end system illustrates that virtualization causes no significant resource or performance overhead but is a perfect match for online video services.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper describes one of the challenging issues implied by scientific infrastructures on a mobile robot cognition architecture. For a generally applicable cognition architecture, we study the dependencies and logical relations between several tasks and subsystems. The overall view of the software modules is described, including their relationship with a fault management module that monitors the consistency of the data flow among the modules. The fault management module is the solution of the deliberative architecture for the single point failures, and the safety anchor is the reactive solution for the faults by redundant equipment. In addition, a hardware architecture is proposed to ensure safe robot movement as a redundancy for the cognition of the robot. The method is designed for a four-wheel steerable (4WS) mobile manipulator (iMoro) as a case study.
Research output: Contribution to journal › Article › Scientific › peer-review
Hardware acceleration for famous VPN solution, IPsec, has been widely researched already. Still it is not fully covered and the increasing latency, throughput, and feature requirements need further evaluation. We propose an IPsec accelerator architecture in an FPGA and explain the details that need to be considered for a production ready design. This research considers the IPsec packet processing without IKE to be offloaded on an FPGA in an SDN network. Related work performance rates in 64 byte packet size for throughput is 1–2 Gbps with 0.2 ms latency in software, and 1–4 Gbps with unknown latencies for hardware solutions. Our proposed architecture is capable to host 1000 concurrent tunnels and have 10 Gbps throughput with only 10 µs latency in our test network. Therefore the proposed design is efficient even with voice or video encryption. The architecture is especially designed for data centers and locations with vast number of concurrent IPsec tunnels. The research confirms that FPGA based hardware acceleration increases performance and is feasible to integrate with the other server infrastructure.
EXT="Viitamäki, Vili"
EXT="Kulmala, Ari"
Research output: Contribution to journal › Article › Scientific › peer-review
Most existing content-based image retrieval and classification systems rely on low-level features which are automatically extracted from images. However, often these features lack the discrimination power needed for accurate description of the image content, and hence, they may lead to a poor retrieval or classification performance. We propose a novel technique to improve low-level features which uses parallel one-against-all perceptrons to synthesize new features with a higher discrimination power which in turn leads to improved classification and retrieval results. The proposed method can be applied on any database and low-level features as long as some ground-truth information is available. The main merits of the proposed technique are its simplicity and faster computation compared to existing feature synthesis methods. Extensive simulation results show a significant improvement in the features’ discrimination power.
EXT="Kiranyaz, Serkan"
Research output: Contribution to journal › Article › Scientific › peer-review
The Internet of Things (IoT) ecosystem is evolving towards the deployment of integrated environments, wherein heterogeneous devices pool their capacities together to match wide-ranging user and service requirements. As a consequence, solutions for efficient and synergistic cooperation among objects acquire great relevance. Along this line, this paper focuses on the adoption of the promising MIFaaS (Mobile-IoT-Federation-as-a-Service) paradigm to support delay-sensitive applications for high-end IoT devices in next-to-come fifth generation (5G) environments. MIFaaS fosters the provisioning of IoT services and applications with low-latency requirements by leveraging cooperation among private/public clouds of IoT objects at the edge of the network. A performance assessment of the MIFaaS paradigm in a cellular 5G environment based on both Long Term Evolution (LTE) and the recent Narrowband IoT (NB-IoT) is presented. Obtained results demonstrate that the proposed solution outperforms classic approaches, highlighting significant benefits derived from the joint use of LTE and NB-IoT bandwidths in terms of increased number of successfully delivered IoT services.
INT=ELT, "Orsino, A."
Research output: Contribution to journal › Article › Scientific › peer-review
In this paper we survey methods for performing a comparative graph analysis and explain the history, foundations and differences of such techniques of the last 50 years. While surveying these methods, we introduce a novel classification scheme by distinguishing between methods for deterministic and random graphs. We believe that this scheme is useful for a better understanding of the methods, their challenges and, finally, for applying the methods efficiently in an interdisciplinary setting of data science to solve a particular problem involving comparative network analysis.
Research output: Contribution to journal › Article › Scientific › peer-review
This paper presents a novel challenging dataset that offers a new landscape of testing material for mobile robotics, autonomous driving research, and forestry operation. In contrast to common urban structures, we explore an unregulated natural environment to exemplify sub-urban and forest environment. The sequences provide two-natured data where each place is visited in summer and winter conditions. The vehicle used for recording is equipped with a sensor rig that constitutes four RGB cameras, an Inertial Measurement Unit, and a Global Navigation Satellite System receiver. The sensors are synchronized based on non-drifting timestamps. The dataset provides trajectories of varying complexity both for the state of the art visual odometry approaches and visual simultaneous localization and mapping algorithms. The full dataset and toolkits are available for download at: http://urn.fi/urn:nbn:fi:att:9b8157a7-1e0f-47c2-bd4e-a19a7e952c0d. As an alternative, you can browse for the dataset using the article title at: http://etsin.fairdata.fi.
Research output: Contribution to journal › Article › Scientific › peer-review
On-line methods for trajectory scaling have focused on torque or acceleration bounded minimum time trajectories, while other system constraints have received little attention. For hydraulic systems, volumetric flow rate of the supply unit establishes a critical constraint, that has been neglected in control design. Consequently, commercial solutions for robotic control of hydraulic manipulators are typically limited to a compromise of a slower constant endpoint velocity, that can be achieved in any operating point without violating the constrained flow rate. However, with real-time analysis of the required volumetric flow rate, the desired trajectories can be executed much faster without violating the flow rate constraint or losing control accuracy. This study proposes an on-line method for trajectory scaling to perform predetermined trajectories in minimum time. Essentially, the method scales velocity along the trajectory to maintain achievable velocity at all times. The proposed method is capable of enforcing a global volumetric flow limit, whether it is constant or time-varying. The method is validated with simulations and experiments with a real hydraulic robotic manipulator. Experimental results show a very significant improvement in the trajectory tracking control, where the tracking error is reduced from 461 mm to 73 mm on a square trajectory.
jufoid=73592
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Multi-task learning, learning of a set of tasks together, can improve performance in the individual learning tasks. Gaussian process models have been applied to learning a set of tasks on different data sets, by constructing joint priors for functions underlying the tasks. In these previous Gaussian process models, the setting has been symmetric in the sense that all the tasks have been assumed to be equally important, whereas in settings such as transfer learning the goal is asymmetric, to enhance performance in a target task given the other tasks. We propose a focused Gaussian process model which introduces an "explaining away" model for each of the additional tasks to model their non-related variation, in order to focus the transfer to the task-of-interest. This focusing helps reduce the key problem of negative transfer, which may cause performance to even decrease if the tasks are not related closely enough. In experiments, our model improves performance compared to single-task learning, symmetric multi-task learning using hierarchical Dirichlet processes, transfer learning based on predictive structure learning, and symmetric multi-task learning with Gaussian processes.
Research output: Contribution to journal › Article › Scientific › peer-review
While good user experience (UX) can be seen to provide competitive advantage for the company and added value to users, resources for achieving UX may often be lacking in software startups. Furthermore, in different phases of business and product development process, concentrating on the focal things can be challenging. In this study, we investigated the factors affecting UX work in startups as well as UX goals startups set for their products. Furthermore, we reviewed the goals in terms of the Minimum Viable UX framework as well as value creation aspects. We present qualitative results of a survey study with 20 software startups as well as findings of a literature review. Our study suggests that while startups aim to provide products with good usability, the lack of a more comprehensive approach to UX can hinder their value creation; affecting both user satisfaction and business success. As a result, this may affect the successful implementation of startup's business model.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we describe patterns that are meant for founding internal startups in a larger company. The patterns are part of a larger pattern language for software startup companies. The patterns presented here cover four main parts of an internal startup's life cycle starting from idea creation by enabling innovation with 20 Rule. The second pattern introduces an incubator phase, where the idea is validated to have a sensible problem and solution. This optimally leads to the creation of an internal startup, where resources are allocated to concretize the idea. With restricted resources such as a limited time, the internal startup may find a new Product-Market fit and offer a validated business opportunity for the parent company. This is concluded by the Exit decision by the parent company and ends the internal startup's life cycle.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
When we gaze a scene, our visual acuity is maximal at the fixation point (imaged by the fovea, the central part of the retina) and decreases rapidly towards the periphery of the visual field. This phenomenon is known as foveation. We investigate the role of foveation in nonlocal image filtering, installing a different form of self-similarity: the foveated self-similarity. We consider the image denoising problem as a simple means of assessing the effectiveness of descriptive models for natural images and we show that, in nonlocal image filtering, the foveated self-similarity is far more effective than the conventional windowed self-similarity. To facilitate the use of foveation in nonlocal imaging algorithms, we develop a general framework for designing foveation operators for patches by means of spatially variant blur. Within this framework, we construct several parametrized families of operators, including anisotropic ones. Strikingly, the foveation operators enabling the best denoising performance are the radial ones, in complete agreement with the orientation preference of the human visual system.
EXT="Boracchi, Giacomo"
Research output: Contribution to journal › Article › Scientific › peer-review
This paper presents a framework for evaluating and designing game design patterns commonly called as "achievements". The results are based on empirical studies of a variety of popular achievement systems. The results, along with the framework for analyzing and designing achievements, present two definitions of game achievements. From the perspective of the achievement system, an achievement appears as a challenge consisting of a signifying element, rewards and completion logics whose fulfilment conditions are defined through events in other systems (usually games). From the perspective of a single game, an achievement appears as an optional challenge provided by a meta-game that is independent of a single game session and yields possible reward(s).
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The paper reports the results from an ongoing project that aims to develop an engaging and effective digital game for training conceptual rational number knowledge. The overall research approach is design science. In the paper we report the results of an iteration in which we studied how students used a Semideus School game prototype and how they experienced the core mechanics of the game. 20 fourth graders and 32 sixth graders played Semideus School game for approximately 2.5 hours. Students were allowed to freely play the game with their iPads. Playing experience was studied with a digital questionnaire that included items about flow experience (Flow Short Scale), perceived playability, and acceptance of game-based math training. Additionally, a researcher observed the playing sessions and discussed with the students about the implementation of the game. Students experienced reasonable high flow experience while playing the game. The results revealed that 4th graders would be more willing to study rational numbers with a game and they also appreciated the playability of the game more than sixth graders. Moreover, sixth graders demanded more complex game mechanics, but 4th graders were happy with the core mechanics. We redesigned the game mechanics based on the findings. The paper describes the new mechanics and the theoretical basis of the new design.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
People use social-photography services to tell stories about themselves and to solicit responses from viewers. State-of-the-art services concentrate on textual comments, "Like" buttons, or similar means for viewers to give explicit feedback, but they overlook other, non-textual means. This paper investigates how emotion responses-as video clips captured by the front camera of a cell phone and used as tags for the individual photo viewed-can enhance photo-sharing experiences for close-knit groups. Our exploration was carried out with a mobile social-photography service called Social Camera. Four user groups (N=19) used the application for two to four weeks. The study's results support the value of using front-camera video recordings to glean emotion response. It supports lightweight phatic social interactions not possible with comments and "Like" buttons. Most users kept sharing emotion responses throughout the study. They typically shared the responses right after they saw a just-taken photo received from a remote partner. They used the responses to share their current contexts with others just as much as to convey nuanced feelings about a photo. We discuss the implications for future design and research.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper proposes an improved version of a .fully tributed routing protocol, that is applicable for cloud computing infrastructure. Simulation results showstheprotocol is ideal for discovering cloud services ... a scalable manner with minimum latency.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
This paper is devoted to analysis and further improvement of full-reference metrics of image visual quality. The effectiveness of a metric is characterized by the rank correlation factors between the obtained array of mean opinion scores (MOS) and the corresponding array of given metric values. This allows to determine the correspondence of a considered metric to a human visual system (HVS). Results obtained on the database TID2013 show that Spearman correlation for the best existing metrics (PSNRHMA, FSIM, SFF, etc.) does not exceed 0.85. In this paper, extended verification tools that allow to detect the shortcomings of the metrics taking into account combined distortions is proposed. An example for further improvement of the PSNRHMA metric is presented.
jufoid=84313
EXT="Ponomarenko, Nikolay"
EXT="Lukin, Vladimir"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Postmortems and Reddit Ask Me Anything (AMA) threads represent communications of game developers through two different channels about their game development experiences, culture, processes, and practices. We carry out a quantitative text mining based comprehensive analysis of online available postmortems and AMA threads from game developers over multiple years. We find and analyze underlying topics from the postmortems and AMAs as well as their variation among the data sources and over time. The analysis is done based on structural topic modeling, a probabilistic modeling technique for text mining. The extracted topics reveal differing and common interests as well as their evolution of prevalence over time in the two text sources. We have found that postmortems put more emphasis on detail-oriented development aspects as well as technically-oriented game design problems whereas AMAs feature a wider variety of discussion topics that are related to a more general game development process, game-play and game-play experience related game design. The prevalences of the topics also evolve differently over time in postmortems versus AMAs.
INT=comp,"Peltonen, Jaakko"
INT=comp,"Lu, Chien"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Computer gaming is a globally growing industry, with hundreds of millions of gaming-capable computers consuming an ever increasing amount of energy. Several of the world's most popular computer games tend to make a heavy use of computers' central processing units and/or graphics processing units. When such games execute on typical computers, for much of the time those components are kept in high energy-consuming states, regardless of what is happening in the game. We analyze this pattern of energy usage and we assess the scope for economizing on energy. The results presented also give insight into the energy implications of the hardware platform and operating systems used for hosting such games. We use the results to provide practical suggestions to both the industry and the gamers. Copyright is held by the owner/author(s). Publication rights licensed to ACM.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Two parallel phenomena are gaining attention in human–computer interaction research: gamification and crowdsourcing. Because crowdsourcing's success depends on a mass of motivated crowdsourcees, crowdsourcing platforms have increasingly been imbued with motivational design features borrowed from games; a practice often called gamification. While the body of literature and knowledge of the phenomenon have begun to accumulate, we still lack a comprehensive and systematic understanding of conceptual foundations, knowledge of how gamification is used in crowdsourcing, and whether it is effective. We first provide a conceptual framework for gamified crowdsourcing systems in order to understand and conceptualize the key aspects of the phenomenon. The paper's main contributions are derived through a systematic literature review that investigates how gamification has been examined in different types of crowdsourcing in a variety of domains. This meticulous mapping, which focuses on all aspects in our framework, enables us to infer what kinds of gamification efforts are effective in different crowdsourcing approaches as well as to point to a number of research gaps and lay out future research directions for gamified crowdsourcing systems. Overall, the results indicate that gamification has been an effective approach for increasing crowdsourcing participation and the quality of the crowdsourced work; however, differences exist between different types of crowdsourcing: the research conducted in the context of crowdsourcing of homogenous tasks has most commonly used simple gamification implementations, such as points and leaderboards, whereas crowdsourcing implementations that seek diverse and creative contributions employ gamification with a richer set of mechanics.
Research output: Contribution to journal › Article › Scientific › peer-review
Maps of RSS from a wireless transmitter can be used for positioning or for planning wireless infrastructure. The RSS values measured at a single point are not always the same, but follow some distribution, which vary from point to point. In existing approaches in the literature this variation is neglected or its mapping requires making many measurements at every point, which makes the measurement collection very laborious. We propose to use GMs for modeling joint distributions of the position and the RSS value. The proposed model is more versatile than methods found in the literature as it models the joint distribution of RSS measurements and the location space. This allows us to model the distributions of RSS values in every point of space without making many measurement in every point. In addition, GMs allow us to compute conditional probabilities and posteriors of position in closed form. The proposed models can model any RSS attenuation pattern, which is useful for positioning in multifloor buildings. Our tests with WLAN signals show that positioning with the proposed algorithm provides accurate position estimates. We conclude that the proposed algorithm can provide useful information about distributions of RSS values for different applications.
Research output: Contribution to journal › Article › Scientific › peer-review
An automatic technique that scrolls the window content while the user is reading the text in the window has been implemented. Scrolling is triggered by gaze moving outside the reader's preferred reading zone. The reading patterns instigated by automatic scrolling are analyzed both quantitatively and using gaze path visualizations. Automatic scrolling is shown to result in smooth reading activity.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Anticipating the emergence of gaze tracking capable mobile devices, we are investigating the use of gaze as an input modality in handheld mobile devices. We conducted a study of combining gaze gestures with vibrotactile feedback. Gaze gestures were used as an input method in a mobile device and vibrotactile feedback as a new alternative way to give confirmation of interaction events. Our results show that vibrotactile feedback significantly improved the use of gaze gestures. The tasks were completed faster and rated easier and more comfortable when vibrotactile feedback was provided.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Traditional Artificial Neural Networks (ANNs) such as Multi-Layer Perceptrons (MLPs) and Radial Basis Functions (RBFs) were designed to simulate biological neural networks; however, they are based only loosely on biology and only provide a crude model. This in turn yields well-known limitations and drawbacks on the performance and robustness. In this paper we shall address them by introducing a novel feed-forward ANN model, Generalized Operational Perceptrons (GOPs) that consist of neurons with distinct (non-)linear operators to achieve a generalized model of the biological neurons and ultimately a superior diversity. We modified the conventional back-propagation (BP) to train GOPs and furthermore, proposed Progressive Operational Perceptrons (POPs) to achieve self-organized and depth-adaptive GOPs according to the learning problem. The most crucial property of the POPs is their ability to simultaneously search for the optimal operator set and train each layer individually. The final POP is, therefore, formed layer by layer and this ability enables POPs with minimal network depth to attack the most challenging learning problems that cannot be learned by conventional ANNs even with a deeper and significantly complex configuration.
jufoid=58177
EXT="Kiranyaz, Serkan"
EXT="Ince, Turker"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Information visualization has recently been formulated as an information retrieval problem, where the goal is to find similar data points based on the visualized nonlinear projection, and the visualization is optimized to maximize a compromise between (smoothed) precision and recall. We turn the visualization into a generative modeling task where a simple user model parameterized by the data coordinates is optimized, neighborhood relations are the observed data, and straightforward maximum likelihood estimation corresponds to Stochastic Neighbor Embedding (SNE). While SNE maximizes pure recall, adding a mixture component that "explains away" misses allows our generative model to focus on maximizing precision as well. The resulting model is a generative solution to maximizing tradeoffs between precision and recall. The model outperforms earlier models in terms of precision and recall and in external validation by unsupervised classification.
Research output: Contribution to journal › Article › Scientific › peer-review
Discriminative part-based models have become the approach for visual object detection. The models learn from a large number of positive and negative examples with annotated class labels and location (bounding box). In contrast, we propose a part-based generative model that learns from a small number of positive examples. This is achieved by utilizing "privileged information", sparse class-specific landmarks with semantic meaning. Our method uses bio-inspired complex-valued Gabor features to describe local parts. Gabor features are transformed to part probabilities by unsupervised Gaussian Mixture Model (GMM). GMM estimation is robustified for a small amount of data by a randomization procedure inspired by random forests. The GMM framework is also used to construct a probabilistic spatial model of part configurations. Our detector is invariant to translation, rotation and scaling. On part level invariance is achieved by pose quantization which is more efficient than previously proposed feature transformations. In the spatial model, invariance is achieved by mapping parts to an "aligned object space". Using a small number of positive examples our generative method performs comparably to the state-of-the-art discriminative method.
EXT="Riabchenko, Ekaterina"
Research output: Contribution to journal › Article › Scientific › peer-review
We describe the design and evaluation of a gestural text editing technique for touchscreen devices. The gestures are drawn on top of the soft keyboard and interpreted as commands for moving the caret, performing selections, and controlling the clipboard. Our implementation is an Android service that can be used in any text editing task on Android-based devices. We conducted an experiment to compare the gestural editing technique against the widget-based technique available on a smartphone (Samsung Galaxy II with Android 2.3.5). The results show a performance benefit of 13-24% for the gestural technique depending on the font size. Subjective feedback from the participants was also positive. Because the two editing techniques use different input areas, they can coexist on a device. This means that the gestural editing can be added on any soft keyboard without interfering with user experience for those users that choose not to use it.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Smartwatches are widely available and increasingly adopted by consumers. The most common way of interacting with smartwatches is either touching a screen or pressing buttons on the sides. However, such techniques require using both hands. We propose glance awareness and active gaze interaction as alternative techniques to interact with smartwatches. We will describe an experiment conducted to understand the user preferences for visual and haptic feedback on a "glance" at the wristwatch. Following the glance, the users interacted with the watch using gaze gestures. Our results showed that user preferences differed depending on the complexity of the interaction. No clear preference emerged for complex interaction. For simple interaction, haptics was the preferred glance feedback modality. Copyright is held by the author/owner(s).
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
We introduce eyeglasses that present haptic feedback when using gaze gestures for input. The glasses utilize vibrotactile actuators to provide gentle stimulation to three locations on the user's head. We describe two initial user studies that were conducted to evaluate the easiness of recognizing feedback locations and participants' preferences for combining the feedback with gaze gestures. The results showed that feedback from a single actuator was the easiest to recognize and also preferred when used with gaze gestures. We conclude by presenting future use scenarios that could benefit from gaze gestures and haptic feedback.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
The article discusses the concept of MurMur Moderators, talking playful seats designed to facilitate playful atmosphere and creativity at office environments. The concept of MurMur Moderators consists of five different personalities, grumpy Mur, goofy Mus, mellow Muh, sensitive Mut and shy Mum. The article describes the experiences and reactions to two personalities, Mus and Mur. Further, a sixth personality, Muf, consisting of rejected, provocative features is detailed. Consequently, the paper discusses play preferences, affordances and thresholds in connection to adult play. These will be the focus of future research by the authors.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
In this paper, we propose a novel extension of the extreme learning machine (ELM) algorithm for single-hidden layer feedforward neural network training that is able to incorporate subspace learning (SL) criteria on the optimization process followed for the calculation of the network's output weights. The proposed graph embedded ELM (GEELM) algorithm is able to naturally exploit both intrinsic and penalty SL criteria that have been (or will be) designed under the graph embedding framework. In addition, we extend the proposed GEELM algorithm in order to be able to exploit SL criteria in arbitrary (even infinite) dimensional ELM spaces. We evaluate the proposed approach on eight standard classification problems and nine publicly available datasets designed for three problems related to human behavior analysis, i.e., the recognition of human face, facial expression, and activity. Experimental results denote the effectiveness of the proposed approach, since it outperforms other ELM-based classification schemes in all the cases.
Research output: Contribution to journal › Article › Scientific › peer-review
Finding graph measures with high discrimination power has been triggered by searching for so-called complete graph invariants. In a series of papers, we have already investigated highly discriminating measures to distinguish graphs (networks) based on their topology. In this paper, we propose an approach where the graph measures are based on the roots of random graph polynomials. The polynomial coefficients have been defined by utilizing information functionals which capture structural information of the underlying networks. Our numerical results obtained by employing exhaustively generated graphs reveal that the new approach outperforms earlier results in the literature.
EXT="Tripathi, Shailesh"
Research output: Contribution to journal › Article › Scientific › peer-review
Fog Computing is a new paradigm that has been proposed by CISCO to take full advantage of the ever growing computational capacity of the near-user or edge devices (e.g., wireless gateways and sensors). The paradigm proposes an architecture that enables the devices to host functionality of various user-centric services. While the prospects of Fog Computing promise numerous advantages, development of Fog Services remains under-investigated. This article considers an opportunity of Fog implementation for Alert Services on top of Wireless Sensor Network (WSN) technology. In particular, we focus on targeted WSN-alert delivery based on spontaneous interaction between a WSN and hand-held devices of its users. For the alert delivery, we propose a Gravity Routing concept that prioritizes the areas of high user-presence within the network. Based on the concept, we develop a routing protocol, namely the Gradient Gravity Routing (GGR) that combines targeted delivery and resilience to potential sensor-load heterogeneity within the network. The protocol has been compared against a set of state-of-the-art solutions via a series of simulations. The evaluation has shown the ability of GGR to match the performance of the compared solutions in terms of alert delivery ratio, while minimizing the overall energy consumption of the network.
Research output: Contribution to journal › Article › Scientific › peer-review
Research output: Contribution to journal › Article › Scientific › peer-review
We present the lessons learned during the development and evaluation process for UX-sensors, a visual data analytics tool for inspecting logged usage data from flexible manufacturing systems (FMS). Based on the experiences during a collaborative development process with practitioners from one FMS supplier company, we propose guidelines to support other developers of visual data analytics tools for usage data logging in context of complex industrial systems. For instance, involving stakeholders with different roles can help to identify user requirements and generate valuable development ideas. Tool developers should confirm early access to real usage data from customers' systems and familiarize themselves with the log data structure. We argue that combining expert evaluations with field study methods can provide a more diverse set of usability issues to address. For future research, we encourage studies on insights emerging from usage data analytics and their impact on the viewpoints of the supplier and customer.
EXT="Nieminen, Harri"
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Open Source Software (OSS) products do not usually follow traditional software engineering development paradigms. Specifically, testing activities in OSS development may be quite different from those carried out in Closed Source Software (CSS) development. As testing and verification require a good deal of resources in OSS, it is necessary to have ways to assess and improve OSS testing processes. This paper provides a set of testing guidelines and issues that OSS developers can use to decide which testing techniques make most sense for their OSS products. This paper 1) provides a checklist that helps OSS developers identify the most useful testing techniques according to the main characteristics of their products, and 2) outlines a proposal for a method that helps assess the maturity of OSS testing processes. The method is a proposal of a Maturity Model for testing processes (called OSS-TMM). To show its usefulness, the authors apply the method to seven real-life projects. Specifically, the authors apply the method to BusyBox, Apache Httpd, and Eclipse Test & Performance Tools Platform to show how the checklist supports and guides the testing process of these OSS products.
Research output: Contribution to journal › Article › Scientific › peer-review
Wearable devices including smart eyewear require new interaction methods between the device and the user. In this paper, we describe our work on the combined use of eye tracking for input and haptic (touch) stimulation for output with eyewear. Input with eyes can be achieved by utilizing gaze gestures which are predefined patterns of gaze movements identified as commands. The frame of the eyeglasses offers three natural contact points with the wearer's skin for haptic stimulation. The results of two user studies reported in this paper showed that stimulation moving between the contact points was easy for users to localize, and that the stimulation has potential to make the use of gaze gestures more efficient.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Touchscreens are becoming a more attractive interaction technology in our daily lives and they are quickly replacing most of the conventional user interface controls. The ability to continuously modify and reconfigure screen contacts is a valuable feature in any device, especially in mobile devices like smartphones and tablets, where every inch matters. Perhaps the most inviting aspect of touchscreens is their ability to detect gestures and recognize human activities. Unlike externally static interfaces with a dedicated input device, such as a keypad with discrete well-defined keys; most touch sensitive displays are embodied as a flat, stiff and ridged screen surface. As a result, touch sensitive displays are breaking down and do not follow either ergonomic rules and standards nor physiological and psychological models/concepts of the afferent flow information processing. This, in turn, means that these systems diminish perceptual and intuitive haptic feedback which hinders and sometime limits user interaction.This paper defines a Haptic User Interface Enhancement System (UIES) that transforms the conventionally flat and stiff touchscreen surfaces intoa haptically adaptive interaction hub which is not only able to provide generic vibrotactile stimulation for conformational haptic feedback but is able to guide the user though onscreen User Interface controls via kinetic feedback cues which includes components of forces and torques applied dynamically in the place of contact to the fingertips.
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review
Dataflow models of computation are capable of providing high-level descriptions for hardware and software components and systems, facilitating efficien