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  • 201.
    Kaci, Iuliia
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Classifying receipts or invoices from images based on text extraction2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, most of the documents are stored in electronic form and there is a high demand to organize and categorize them efficiently. Therefore, the field of automated text classification has gained a significant attention both from science and industry. This technology has been applied to information retrieval, information filtering, news classification, etc. The goal of this project is the automated text classification of photos as invoices or receipts in Visma Mobile Scanner, based on the previously extracted text. Firstly, several OCR tools available on the market have been evaluated in order to find the most accurate to be used for the text extraction, which turned out to be ABBYY FineReader. The machine learning tool WEKA has been used for the text classification, with the focus on the Naïve Bayes classifier. Since the Naïve Bayes implementation provided by WEKA does not support some advances in the text classification field such as N-gram, Laplace smoothing, etc., an improved version of Naïve Bayes classifier which is more specialized for the text classification and the invoice/receipt classification has been implemented. Improving the Naive Bayes classifier, investigating how it can be improved for the problem domain and evaluating the obtained classification accuracy compared to the generic Naïve Bayes are the main parts of this research. Experimental results show that the specialized Naïve Bayes classifier has the highest accuracy. By applying the Fixed penalty feature, the best result of 95.6522% accuracy on cross-validation mode has been achieved. In case of more accurate text extraction, the accuracy is even higher. 

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    fulltext
  • 202.
    Kaidalov, Dmytro
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Algorithm and software development for security estimation of SPN-based block cipher against related-key attacks2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Symmetric block ciphers are among the most widely used cryptographic primitives. In addition to providing privacy via encryption, block ciphers are used as basic components in the construction of hash functions, message authentication codes, pseudorandom number generator, as part of various cryptographic protocols and etc. One of the most popular block ciphers nowadays is AES (Advanced Encryption Standard), which has been used as a standard of encryption in many countries of the world. In spite of popularity of this cipher a huge attack was found on its key-expansion algorithm some years ago. That is why it is important to analyze carefully this component and understand what weak points admit attacks. Since we know that we can improve existing algorithm to protect cipher from attacks or build up a new algorithm taking into account founded weaknesses so there will be no chance to break it with existing knowledge.

    The goal of this project is to create some method which can estimate security of encryption algorithm against related-key attacks. For this reason the perspective block cipher is introduced. This cipher is a candidate to the public standard of encryption in Ukraine so that is why this research is very important. Actually the introduced method of estimation is created especially for this cipher but also can be used for other ciphers based on the substitution-permutation network. The developed method was applied to the cipher and results are represented in the report. Also the complexity estimation of this algorithm is expressed. The software implementation is described in the last chapter of report.

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    Kaidalov_report
  • 203.
    Kalousek, Jiří
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Context-Aware P2P Network Construction2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With growing number of devices connected to the network, there is a greater need for use of Peer-to-Peer (P2P) networks and distributed P2P protocols.Devices participating in the P2P network do not usually need to use any central server that links up connections. It has many advantages but it needs to use so-called overlay network that consists of protocols used for traffic routing and decision making. Protocols used in today’s P2P networks are mostly not considerate of particular participating nodes and all the nodes in the network are usually equal. This can have negative impacts on network performance. In order to avoid or reduce some unwanted negative impacts, it would be advantageous if the overlay network could route traffic and make decisions according to context information like battery levels or connection speeds. This work reviews a few popular P2P overlay networks and based on that it introduces an improvement of one of them – Chord. The structure of the improved version of the Chord protocol called Context-Aware Chord is described. Then results of the evaluation are presented. With a use of the improved protocol, nodes can participate longer in the network and throughput of lookup messages is improved.

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    fulltext
  • 204.
    Karg, Philipp
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Evaluation and Implementation of Machine Learning Methods for an Optimized Web Service Selection in a Future Service Market2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In future service markets a selection of functionally equal services is omnipresent. The evolving challenge, finding the best-fit service, requires a distinction between the non-functional service characteristics (e.g., response time, price, availability). Service providers commonly capture those quality characteristics in so-called Service Level Agreements (SLAs). However, a service selection based on SLAs is inadequate, because the static SLAs generally do not consider the dynamic service behaviors and quality changes in a service-oriented environment. Furthermore, the profit-oriented service providers tend to embellish their SLAs by flexibly handling their correctness. Within the SOC (Service Oriented Computing) research project of the Karlsruhe University of Applied Sciences and the Linnaeus University of Sweden, a service broker framework for an optimized web service selection is introduced. Instead of relying on the providers’ quality assertions, a distributed knowledge is developed by automatically monitoring and measuring the service quality during each service consumption. The broker aims at optimizing the service selection based on the past real service performances and the defined quality preferences of a unique consumer.This thesis work concerns the design, implementation and evaluation of appropriate machine learning methods with focus on the broker’s best-fit web service selection. Within the time-critical service optimization the performance and scalability of the broker’s machine learning plays an important role. Therefore, high- performance algorithms for predicting the future non-functional service characteristics within a continuous machine learning process were implemented. The introduced so-called foreground-/background-model enables to separate the real-time request for a best-fit service selection from the time-consuming machine learning. The best-fit services for certain consumer call contexts (e.g., call location and time, quality preferences) are continuously pre-determined within the asynchronous background-model. Through this any performance issues within the critical path from the service request up to the best-fit service recommendation are eliminated. For evaluating the implemented best-fit service selection a sophisticated test data scenario with real-world characteristics was created showing services with different volatile performances, cyclic performance behaviors and performance changes in the course of time. Besides the significantly improved performance, the new implementation achieved an overall high selection accuracy. It was possible to determine in 70% of all service optimizations the actual best-fit service and in 94% of all service optimizations the actual two best-fit services.

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    Masters_Thesis_Philipp_Karg
  • 205.
    Karlsson, Emil
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Edberg, Mikael
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Skrapa försäljningssidor på nätet: Ett ramverk för webskrapningsrobotar2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    På internet finns det idag ett stort utbud av försäljningswebbsidor där det hela tiden inkommer nya annonser. Vi ser att det finns ett behov av ett verktyg som övervakar de här webbsidorna dygnet runt för att se hur mycket som säljs och vad som säljs. Att skapa ett program som övervakar webbsidor är tidskrävande, därför har vi skapat ett ramverk som underlättar skapandet av webbskrapare som är fokuserade på att listbaserade försäljningswebbsidor på nätet. Det finns flera olika ramverk för webbskrapning, men det finns väldigt få som endast är fokuserade på den här typen av webbsidor.

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    fulltext
  • 206.
    Kashfi, Hamid
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Evaluation of Current Practical Attacks Against RFID Technology2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Radio Frequency Identification (RFID) is a technology that has been around for three decades now. It is being used in various scenarios in technologically modern societies around the world and becoming a crucial part of our daily life. But we often forget how the inner technology is designed to work, or even if it is as trustable and secure as we think. While the RFID technology and protocols involved with it has been designed with an acceptable level of security in mind, not all implementations and use cases are as secure as consumers believe. A majority of implementations and products that are deployed suffer from known and critical security issues.

         This thesis work starts with an introduction to RFID standards and how the technology works. Followed by that a taxonomy of known attacks and threats affecting RFID is presented, which avoids going through too much of technical details but provides references for farther research and study for every part and attack. Then RFID security threats are reviewed from risk management point of view, linking introduced attacks to the security principle they affect. We also review (lack thereof) security standards and guidelines that can help mitigating introduced threats. Finally to demonstrate how practical and serious these threats are, three real-world case studies are presented, in which we break security of widely used RFID implementations. At the end we also review and highlight domains in RFID security that can be researched farther, and what materials we are currently missing, that can be used to raise awareness and increase security of RFID technology for consumers.

         The goal of this thesis report is to familiarize readers with all of the publicly documented and known security issues of RFID technology, so that they can get a sense about the security state of their systems. Without getting involved with too much technical details about every attack vector, or going throw tens of different books and papers, readers can use this report as a comprehensive reference to educate themselves about all known attacks against RFID, published to the date of writing this report. 

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    fulltext
  • 207.
    Kayahan, Hüseyin
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    INTRUSION EXECUTION SYSTEMS: Prototype: IMPETUS2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In nature, it is inspiring to observe such an extensive variety of defensive skills distributed among species. The speed of an antelope, and the sting of a scorpion, wasp or a bee are some examples of such defensive tools or mechanisms important to survive against predators. However sophisticated the skills or tools are, the correct accurate use and on-time triggering of those tools is a matter of life and death for animals. With those defensive measures, animals come with a complementary ability called "vigilance".

    Vigilance is costly and the human tries to minimize vigilant behaviour in every aspect of life. The absence of vigilance, or negligence in other words, allows humans to spend more time and cognition on matters that he or she wants rather than on problems that need time. The human has an inherent and intricate mechanism that determine the vigilance level required for a particular problem.

    The consequences of the lack of vigilance in a work environment, more especially in the Information Technologies Security field are catastrophic and even lethal as humanity becomes an increasingly associated habitant of cyberspace ecosystem.

    Intrusion Execution Systems (IES) which is one of my conceptual propositions in this research, is my approach to reduce negligent behaviour in IT Security personnel. Impetus is the name of the first prototype for IES concept with limitations, which is included in this research.

    Impetus can successfully achieve desired behaviour in test environment, however the conceptual propositions in this research among with Impetus, should further be experimented in real-world in order to be convinced of its effectiveness.

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    kayahanIES
  • 208.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Information Visualization Courses for Students with a Computer Science Background2013In: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 33, no 2, p. 12-15Article in journal (Refereed)
    Abstract [en]

    Linnaeus University offers two master's courses in information visualization for computer science students with programming experience. This article briefly describes the syllabi, exercises, and practices developed for these courses.

  • 209.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Interaction and Evaluation Techniques for Information Visualization: Future Directions2013In: Proceedings of the 6th International Symposium on Visual Information Communication and Interaction (VINCI '13), ACM Press, 2013, p. 118-118Conference paper (Other academic)
    Abstract [en]

    Intuitive and efficient interaction techniques are a fundamental component of most visualization tools. The integration of interaction techniques into visual representations (and automatic analysis methods in visual analytics) supports the human-information discourse and can be realized in various ways. But we also have to take care that our interaction and visual representation techniques are validated in order to get a clear understanding of their efficiency and usability. In this talk, I will explore current and identify future trends in the development of novel interaction and evaluation techniques for information visualization and related fields. Here, I especially want to highlight recent findings in the use of brain-computer interfaces to adapt and evaluate visualizations.

  • 210.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Cernea, DanielAGT International, Germany.Pohl, MargitTechnical University of Vienna, Austria.
    Proceedings of EmoVis 2016: ACM IUI 2016 Workshop on Emotion and Visualization2016Conference proceedings (editor) (Refereed)
  • 211.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Cernea, Daniel
    AGT International, Germany.
    Pohl, Margit
    Technical University of Vienna, Austria.
    Workshop on Emotion and Visualization: EmoVis 20162016In: Companion Publication of the 21st International Conference on Intelligent User Interfaces, New York, NY, USA: ACM Publications, 2016, p. 1-2Conference paper (Other academic)
  • 212.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Jusufi, Ilir
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Novel Radial Visualization Approach for Undirected Hypergraphs2013In: EuroVis: Short Papers, Eurographics - European Association for Computer Graphics, 2013, p. 25-29Conference paper (Refereed)
    Abstract [en]

    Hypergraphs are a more generalized concept of graphs where an edge typically connects multiple vertices. They are applicable to many different domains such as the representation of complex biochemical pathways or classification problems with non-empty intersections between different groups, for instance, in social network analysis. There is a need to visualize those relational data structures in such a way that a better understanding of the relationships between vertices as well as their interactive exploration is supported. This paper describes a new radial visualization technique to layout undirected hypergraphs without clutter and to provide methods of interaction and data analysis. 

  • 213.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Jusufi, Ilir
    University of California, USA.
    Liu, Jiayi
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Multi-Scale Trend Visualization of Long-Term Temperature Data Sets2014In: Proceedings of SIGRAD 2014, Visual Computing, June 12-13, 2014, Göteborg, Sweden / [ed] M. Obaid, D. Sjölie and M. Fjeld, Linköping University Electronic Press, 2014, p. 91-94Conference paper (Refereed)
    Abstract [en]

    The analysis and presentation of climate observations is a traditional application of various visualization approaches. The available data sets are usually huge and were typically collected over a long period of time. In this paper, we focus on the visualization of a specific aspect of climate data: our visualization tool was primarily developed for providing an overview of temperature measurements for one location over decades or even centuries. In order to support an efficient overview and visual representation of the data, it is based on a region-oriented metaphor that includes various granularity levels and aggregation features. 

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    sigrad14
  • 214.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kucher, Kostiantyn
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Li, Yuan-Fang
    Monash University, Australia.
    Schreiber, Falk
    University of Konstanz, Germany ; Monash University, Australia.
    BioVis Explorer: A visual guide for biological data visualization techniques2017In: PLOS ONE, E-ISSN 1932-6203, Vol. 12, no 11, article id e0187341Article in journal (Refereed)
    Abstract [en]

    Data visualization is of increasing importance in the Biosciences. During the past 15 years, a great number of novel methods and tools for the visualization of biological data have been developed and published in various journals and conference proceedings. As a consequence, keeping an overview of state-of-the-art visualization research has become increasingly challenging for both biology researchers and visualization researchers. To address this challenge, we have reviewed visualization research especially performed for the Biosciences and created an interactive web-based visualization tool, the BioVis Explorer. BioVis Explorer allows the exploration of published visualization methods in interactive and intuitive ways, including faceted browsing and associations with related methods. The tool is publicly available online and has been designed as community-based system which allows users to add their works easily.

  • 215.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Kucher, Kostiantyn
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Li, Yuan-Fang
    Monash University, Australia.
    Schreiber, Falk
    University of Konstanz, Germany ; Monash University, Australia.
    MDS-based Visual Survey of Biological Data Visualization Techniques2017In: EuroVis 2017 - Posters / [ed] Anna Puig Puig and Tobias Isenberg, Eurographics - European Association for Computer Graphics, 2017, p. 85-87Conference paper (Refereed)
    Abstract [en]

    Data visualization is of increasing importance in the Biosciences. During the past 15 years, a great number of novel methods and tools for biological data visualization have been developed and published in various journals and conference proceedings. As a consequence, keeping an overview of state-of-the-art visualization research has become increasingly challenging for both biology researchers as well as visualization researchers. To address this challenge, we have reviewed visualization research for the Biosciences and created an interactive web-based visualization tool, the BioVis Explorer. BioVis Explorer allows the exploration of published visualization methods in interactive and intuitive ways, including faceted browsing and associations with related methods. 

  • 216.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Kyusakova, Mimi
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Paradis, Carita
    Lund University, Centre for Languages and Literature.
    From Culture to Text to Interactive Visualization of Wine Reviews2013In: Knowledge Visualization Currents: From Text to Art to Culture, Part II / [ed] F.T. Marchese and E. Banissi, London: Springer, 2013, p. 85-110Chapter in book (Refereed)
    Abstract [en]

    On the basis of a large corpus of wine reviews, this chapter proposes a range of interactive visualization techniques that are useful for linguistic exploration and analysis of lexical, grammatical and discursive patterns in text. Our visualization tool allows linguists and others to make comparisons of visual, olfactory, gustatory and textual properties of different wines for example from different countries, from different grape varieties, or from different vintages. It also supports the visual exploration of sensory descriptions as well as confirmatory investigations of text and discourse. Besides a more technical discussion of our visualization approach, we also provide a more general overview of text and corpus visualizations and highlight linguistic challenges that we had to address during the development phase.

  • 217.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Purchase, Helen C.
    University of Glasgow.
    Ward, Matthew O.
    Worcester Polytechnic Institute.
    Information Visualization: Towards Multivariate Network Visualization2013Report (Other academic)
    Abstract [en]

    Information Visualization (InfoVis) focuses on the use of visualization techniques to help people understand and analyze large and complex data sets. The aim of this third Dagstuhl Seminar on Information Visualization was to bring together theoreticians and practitioners from Information Visualization, HCI, and Graph Drawing with a special focus on multivariate network visualization, i.e., on graphs where the nodes and/or edges have additional (multidimensional) attributes. To support discussions related to the visualization of real world data, researchers from selected application areas, especially bioinformatics, social sciences, and software engineering, were also invited. During the seminar, working groups on six different topics were formed and enabled a critical reflection on ongoing research efforts, the state of the field in multivariate network visualization, and key research challenges today. This report documents the program and the outcomes of Dagstuhl Seminar 13201 "Information Visualization - Towards Multivariate Network Visualization".

  • 218.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Purchase, Helen C.
    University of Glasgow.
    Ward, Matthew O.
    Worcester Polytechnic Institute.
    Introduction to Multivariate Network Visualization2014In: Multivariate Network Visualization / [ed] Kerren, Andreas, Purchase, Helen, Ward, Matthew O., Springer, 2014, p. 1-9Conference paper (Refereed)
  • 219.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Purchase, Helen C.University of Glasgow.Ward, Matthew O.Worcester Polytechnic Institute.
    Multivariate Network Visualization: Dagstuhl seminar #13201 Dagstuhl Castle, Germany, May 12-17, 2013, Revised Discussions2014Collection (editor) (Refereed)
    Abstract [en]

    This book is the outcome of the Dagstuhl Seminar 13201 on Information Visualization - Towards Multivariate Network Visualization, held in Dagstuhl Castle, Germany in May 2013.

    The goal of this Dagstuhl Seminar was to bring together theoreticians and practitioners from Information Visualization, HCI, and Graph Drawing with a special focus on multivariate network visualization, i.e., on graphs where the nodes and/or edges have additional (multidimensional) attributes. The integration of multivariate data into complex networks and their visual analysis is one of the big challenges not only in visualization, but also in many application areas. Thus, in order to support discussions related to the visualization of real world data, also invited researchers from selected application areas, especially bioinformatics, social sciences, and software engineering. The unique "Dagstuhl climate" ensured an open and undisturbed atmosphere to discuss the state-of-the-art, new directions, and open challenges of multivariate network visualization.

  • 220.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Schreiber, Falk
    Martin Luther University .
    Network Visualization for Integrative Bioinformatics2014In: Approaches in Integrative Bioinformatics: Towards the Virtual Cell / [ed] Ming Chen and Ralf Hofestädt, Berlin Heidelberg: Springer, 2014, p. 173-202Chapter in book (Refereed)
    Abstract [en]

    Approaches to investigate biological processes have been of strong interest in the past few years and are the focus of several research areas like systems biology. Biological networks as representations of such processes are crucial for an extensive understanding of living beings. Due to their size and complexity, their growth and continuous change, as well as their compilation from databases on demand, researchers very often request novel network visualization, interaction and exploration techniques. In this chapter, we first provide background information that is needed for the interactive visual analysis of various biological networks. Fields such as (information) visualization, visual analytics and automatic layout of networks are highlighted and illustrated by a number of examples. Then, the state of the art in network visualization for the life sciences is presented together with a discussion of standards for the graphical representation of cellular networks and biological processes.

  • 221.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Schreiber, Falk
    Monash Univ, Australia.
    Why Integrate InfoVis and SciVis?: An Example from Systems Biology2014In: IEEE Computer Graphics and Applications, ISSN 0272-1716, E-ISSN 1558-1756, Vol. 34, no 6, p. 69-73Article in journal (Other academic)
    Abstract [en]

    The more-or-less artificial barrier between information visualization and scientific visualization hinders knowledge discovery. Having an integrated view of many aspects of the target data, including a seamlessly interwoven visual display of structural abstract data and 3D spatial information, could lead to new discoveries, insights, and scientific questions. Such a view also could reduce the user’s cognitive load—that is, reduce the effort the user expends when comparing views.

  • 222.
    Kerren, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Zhang, KangThe University of Texas at Dallas, USA.
    Proceedings of the 9th International Symposium on Visual Information Communication and Interaction (VINCI '16): Dallas, TX, USA, September 24 - 26, 20162016Conference proceedings (editor) (Refereed)
    Abstract [en]

    Welcome to the 9th International Symposium on Visual Information Communication and Interaction (VINCI 2016) held in Dallas, TX, USA from September 24th to 26th, 2016. The objective of this symposium series is to provide a forum for researchers, artists, designers, and industrial practitioners to discuss the state of the art in visual communication theories, designs, and applications. As in past years, the papers in these proceedings represent the most interesting and exciting recent research in the area of visual communication.

  • 223.
    Khakpour, Narges
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Control of Self-adaptation Under Partial Observation: A Modular Approach2017In: Software Architecture: 11th European Conference, ECSA 2017, Canterbury, UK, September 11-15, 2017, Proceedings / [ed] Antónia Lopes & Rogério de Lemos, Springer, 2017, Vol. 10475, p. 112-119Conference paper (Refereed)
    Abstract [en]

    To realize correct adaptive and reconfigurable systems, we need techniques to assure that the behavior of an adaptive system during dynamic adaptation is correct. In this paper, we propose a modular approach to synthesize a symbolic reconfiguration controller that guides the behavior of a system during adaptation under partial observations. The reconfiguration controller observes the system behavior partially during an adaptation and controls it by allowing/disallowing actions in a way to ensure that a given property is satisfied and a deadlock is avoided.

  • 224.
    Khakpour, Narges
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science. Leiden University, The Netherlands.
    Arbab, Farhad
    Leiden University, The Netherlands.
    Rutten, Eric
    INRIA, France.
    Supervisory Controller Synthesis for Safe Software Adaptation2014In: 12th IFAC International Workshop on Discrete Event Systems (2014) / [ed] Jean-Jacques Lesage, Jean-Marc Faure, Jose E. R. Cury, Bengt Lennartson, International Federation of Automatic Control , 2014, Vol. 47, Iss 2, p. 39-45Conference paper (Refereed)
    Abstract [en]

    Today's software systems need to adapt their behavior due to the changes in their operational environments and user requirements. To this end, an adaptive software performs a sequence of adaptations at runtime. Correctness of the behavior of an adaptive software system during dynamic adaptation is an important challenge along the way to realize correct adaptive systems. In this research, we model adaptation as a supervisory control problem and synthesize a controller that guides the behavior of a software system during adaptation. The system during adaptation is modeled using a graph transition system and properties to be enforced are specified using an automaton. To ensure correctness, we then synthesize a controller that imposes constraints on the system during adaptation.

  • 225.
    Khakpour, Narges
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Leiden University, The Netherlands.
    Arbab, Farhad
    Leiden University, The Netherlands ; CWI, The Netherlands.
    Rutten, Eric
    INRIA, France.
    Synthesizing structural and behavioral control for reconfigurations in component-based systems2016In: Formal Aspects of Computing, ISSN 0934-5043, E-ISSN 1433-299X, Vol. 28, no 1, p. 21-43Article in journal (Refereed)
    Abstract [en]

    Correctness of the behavior of an adaptive system during dynamic adaptation is an important challenge to realize correct adaptive systems. Dynamic adaptation refers to changes to both the functionality of the computational entities that comprise a composite system, as well as the structure of their interconnections, in response to variations in the environment, e.g., the load of requests on a server system. In this research, we view the problem of correct structural adaptation as a supervisory control problem and synthesize a reconfiguration controller that guides the behavior of a system during adaptation. The reconfiguration controller observes the system behavior during an adaptation and controls the system behavior by allowing/disallowing actions in a way to ensure that a given property is satisfied and a deadlock is avoided. The system during adaptation is modeled using a graph transition system and properties to be enforced are specified using a graph automaton. We adapt a classical theory of supervisory control for synthesizing a controller for controlling the behavior of a system modeled using graph transition systems. This theory is used to synthesize a controller that can impose both behavioral and structural constraints on the system during an adaptation. We apply a tool that we have implemented to support our approach on a case study involving https servers.

  • 226.
    Khakpour, Narges
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Mousavi, Mohammad Reza
    Halmstad University.
    Notions of Conformance Testing for Cyber-Physical Systems: Overview and Roadmap2015In: 26th International Conference on Concurrency Theory (CONCUR 2015) / [ed] Luca Aceto, David de Frutos Escrig, Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik , 2015, p. 18-40Conference paper (Refereed)
    Abstract [en]

    We review and compare three notions of conformance testing for cyber-physical systems. We begin with a review of their underlying semantic models and present conformance-preserving translations between them. We identify the differences in the underlying semantic models and the various design decisions that lead to these substantially different notions of conformance testing. Learning from this exercise, we reflect upon the challenges in designing an "ideal" notion of conformance for cyber-physical systems and sketch a roadmap of future research in this domain.

  • 227.
    Khalili, Ali
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Security in Mobile Ad-Hoc Networks2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

                                           

    Abstract

    The number of wireless networks has been growing incessantly during the recent years. Ad hoc networks transmit digital data through radio frequency or wireless communications links, which is an open medium. According to this fact it is important to gain substantial knowledge about the advantages and the drawbacks associated with them for network security purposes. According to the vulnerability of these networks (wireless Ad hoc) to malicious attacks and hackers, there seems to be a necessity to address the potential risks of using these networks.

    An Ad-Hoc is a system of wireless mobile nodes that dynamically self-organize in temporary network topologies. People and vehicles can thus be internetworked in areas without a preexisting communication infrastructure or when the use of such infrastructure requires wireless extension.  

    Therefore, one should focus on a proper Security Standards as well as solid secure construction. There are a vast variety of malicious attacks against mobile Ad hoc networks. In order to distinguish these attacks some classifications (attack models) are presented. Different malicious techniques against communications of the network are discussed in order to introduce the best practice, to set-up and maintain a secure mobile Ad hoc network. In this paper a solid intrusion detection system for MANET presented along with the best solution for creates a trust relation among nodes. Information gathering (Passive attack) is discussed from an ethical point of view.

  • 228.
    Kirchner, Jens
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Context-Aware Optimized Service Selection with Focus on Consumer Preferences2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Cloud computing, mobile computing, Service-Oriented Computing (SOC), and Software as a Service (SaaS) indicate that the Internet emerges to an anonymous service market where service functionality can be dynamically and ubiquitously consumed. Among functionally similar services, service consumers are interested in the consumption of the services which perform best towards their optimization preferences. The experienced performance of a service at consumer side is expressed in its non-functional properties (NFPs). Selecting the best-fit service is an individual challenge as the preferences of consumers vary. Furthermore, service markets such as the Internet are characterized by perpetual change and complexity. The complex collaboration of system environments and networks as well as expected and unexpected incidents may result in various performance experiences of a specific service at consumer side. The consideration of certain call side aspects that may distinguish such differences in the experience of NFPs is reflected in various call contexts.

    Service optimization based on a collaborative knowledge base of previous experiences of other, similar consumers with similar preferences is a desirable foundation. The research work described in this dissertation aims at an individually optimized selection of services considering the individual call contexts that have an impact on the performance, or NFPs in general, of a service as well as the various consumer preferences. The presented approach exploits shared measurement information about the NFP behavior of a service gained from former service calls of previous consumptions. Gaining selection/recommendation knowledge from shared experience benefits existing as well as new consumers of a service before its (initial) consumption. Our approach solely focuses on the optimization and collaborative information exchange among service consumers. It does not require the contribution of service providers or other non-consuming entities. As a result, the contribution among the participating entities also contributes to their own overall optimization benefit. With the initial focus on a single-tier optimization, we additionally provide a conceptual solution to a multi-tier optimization approach for which our recommendation framework is prepared in general.

    For a consumer-sided optimization, we conducted a literature study of conference papers of the last decade in order to find out what NFPs are relevant for the selection and consumption of services. The ranked results of this study represent what a broad scientific community determined to be relevant NFPs for service selection.

    We analyzed two general approaches for the employment of machine learning methods within our recommendation framework as part of the preparation of the actual recommendation knowledge. Addressing a future service market that has not fully developed yet and due to the fact that it seems to be impossible to be aware of the actual NFP data of different Web services at identical call contexts, a real-world validation is a challenge. In order to conduct an evaluation and also validation that can be considered to be close approximations to reality with the flexibility to challenge the machine learning approaches and methods as well as the overall recommendation approach, we used generated NFP data whose characteristics are influenced by measurement data gained from real-world Web services.

    For the general approach with the better evaluation results and benefits ratio, we furthermore analyzed, implemented, and validated machine learning methods that can be employed for service recommendation. Within the validation, we could achieve up to 95% of the overall achievable performance (utility) gain with a machine learning method that is focused on drift detection, which in turn, tackles the change characteristic of the Internet being an anonymous service market.

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  • 229.
    Kirchner, Jens
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Karlsruhe University of Applied Sciences, Germany.
    Heberle, Andreas
    Karlsruhe University of Applied Sciences, Germany.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Classification vs. Regression: Machine learning approaches for service recommendation based on measured consumer experiences2015In: IEEE World Congress on Services (SERVICES), 2015 / [ed] Zhang, LJ; Bahsoon, R, IEEE Press, 2015, p. 278-285Conference paper (Refereed)
    Abstract [en]

    Service functionality can be provided by more than one service consumer. In order to choose the service which creates the most benefit before its consumption, a selection based on previous measurable experiences by other consumers is beneficial. In this paper, we present the results of our analysis of two machine learning approaches to predict the best service within this selection problem. The first approach focuses on classification, predicting the best performing service, while the second approach focuses on regression, predicting service performances which can then be used for the determination of the best candidate. We assessed and compared both approaches for service recommendation w.r.t. The performance gain when selecting the recommended instead of a random service. Our evaluation is based on data measured on real Web services as well as on simulated data. The latter is needed for a more profound analysis of the strengths and weaknesses of each approach. The simulated data has similar statistical properties as the data measured on real Web services. In the real-world case, regression achieved a response time gain of over 92% of the optimum and classification over 83%. In case of simulated data, we could achieve an overall gain of up to 95% using classification, while regression achieved 89%.

  • 230.
    Kirchner, Jens
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science. Karlsruhe Univ Appl Sci, Germany.
    Heberle, Andreas
    Karlsruhe Univ Appl Sci, Germany.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Evaluation of the Employment of Machine Learning Approaches and Strategies for Service Recommendation2015In: SERVICE ORIENTED AND CLOUD COMPUTING, ESOCC 2015, Springer, 2015, p. 95-109Conference paper (Refereed)
    Abstract [en]

    Service functionality can be provided by more than one service consumer. In order to choose the service with the highest benefit, a selection based on previously measured experiences by other consumers is beneficial. In this paper, we present the results of our evaluation of two machine learning approaches in combination with several learning strategies to predict the best service within this selection problem. The first approach focuses on the prediction of the best-performing service, while the second approach focuses on the prediction of service performances which can then be used for the determination of the best-performing service. We assessed both approaches w.r.t. the overall optimization achievement relative to the worst-and the best-performing service. Our evaluation is based on data measured on real Web services as well as on simulated data. The latter is needed for a more profound analysis of the strengths and weaknesses of each approach and learning strategy when it gets harder to distinguish the performance profile of the service candidates. The simulated data focuses on different aspects of a service performance profile. For the real-world measurement data, 97% overall optimization achievement and over 82% best service selection could be achieved within the evaluation.

  • 231.
    Kirchner, Jens
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Karlsruhe University of Applied Sciences, Germany.
    Heberle, Andreas
    Karlsruhe University of Applied Sciences, Germany.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Service recommendation using machine learning methods based on measured consumer experiences within a service market2015In: International Journal on Advances in Intelligent Systems, ISSN 1942-2679, E-ISSN 1942-2679, Vol. 8, no 3&4, p. 347-373Article in journal (Refereed)
    Abstract [en]

    Among functionally similar services, service consumersare interested in the consumption of the service that performsbest towards their optimization preferences. The experiencedperformance of a service at consumer side is expressed in its nonfunctionalproperties. Selecting the best-fit service is an individualaspect as the preferences of consumers vary. Furthermore, servicemarkets such as the Internet are characterized by perpetualchange and complexity. The complex collaboration of system environmentsand networks result in various performance experiencesat consumer side. Service optimization based on a collaborativeknowledge base of previous experiences of other, similar consumerswith similar preferences is a desirable foundation. In thisarticle, we present a service recommendation framework, whichaims at the optimization at consumer side focusing on the individualpreferences and call contexts. In order to identify relevantnon-functional properties for service selection, we conducted aliterature study of conference papers of the last decade. Theranked results of this study represent what a broad scientificcommunity determined to be relevant non-functional propertiesfor service selection. We furthermore analyzed, implemented, andvalidated machine learning methods that can be employed forservice recommendation. Within our validation, we could achieveup to 95% of the overall achievable performance (utility) gainwith a machine learning method that is focused on conceptdrift, which in turn, tackles the change characteristic of theInternet being a service market. Besides the comprehensive andscientific identification of relevant non-functional properties whenselecting a service, this article describes how machine learningcan be employed for service recommendation based on consumerexperiences in general, including an evaluation and overall proofof concept validation within our framework.

  • 232.
    Kirchner, Jens
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Karlsruhe University of Applied Sciences, Germany.
    Karg, Phillip
    University of Applied Science Karlsruhe, Germany.
    Heberle, Andreas
    University of Applied Science Karlsruhe, Germany.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Appropriate machine learning methods for service recommendation based on measured consumer experiences within a service market2015In: SERVICE COMPUTATION 2015 : The Seventh International Conferences on Advanced Service Computing, March 22, 2015 to March 27, 2015, Nice, France, International Academy, Research and Industry Association (IARIA), 2015, p. 41-48Conference paper (Refereed)
    Abstract [en]

    The actual experience of the performance of services at consumers’ side is a desirable foundation for service selection. Considering the knowledge of previous performance experiences from a consumer’s perspective, a service broker can automatically select the best-fitting service out of a set of functionally similar services. In this paper, we present the evaluation of machine learning methods and frameworks which can be employed for service recommendation based on shared experiences of previous consumers. Implemented in a prototype, our approach considers a consumer’s call context as well as its selection preferences (expressed in utility functions). The implementation of the framework aims at the time-critical optimisation of service consumption with focus on runtime aspects and scalability. Therefore, we evaluated and employed high-performance, online and large scale machine learning methods and frameworks. Considering the Internet as a service market with perpetual change, strategies for concept drift have to be found. The evaluation showed that with the current approach, the framework recommended the actual best-fit service instance in 70% of the validation cases, while in 90% of the cases, the best or second best-fit was recommended. Furthermore, within our approach employing the best method, we achieved 94.5% of the overall maximum achievable utility value.

  • 233.
    Kleveros, Daniel
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A scientific approach to the comparison between Java and Node.js: Factors to consider when choosing platform.2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When starting a new development project it can sometimes be hard to choose the best platform for the job. This study will through scientific research expose factors to consider when choosing platform for a project. The platforms included in this research are Java and Node.js, two popular server side programming languages

  • 234.
    Klimov, Illia
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Podoba, Oryna
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Improvement of the Architecture and Communication Protocol of a Sensor-based IT System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Communication protocols based on SMS and e-email are simple and straightforward to implement yet they possess a significant communication overhead and delay. In a large sensor network this would increasingly lead to performance issues and decrease scalability of the overall system, since SMS and e-mail include a significant transmission delay and overhead. Additionally, a communication architecture, where clients communicate directly to the central server requires these to be online all the time, thus decreasing battery time.

    We replaced the initial SMS and e-mail based communication protocol with a TCP based protocol. Furthermore, we selected a new architecture where sensor groups could communicate to a master node in that group, which in turn communicates to the central server.

    These changes were implemented in an emulator, since the real sensors could not be reconfigured. We evaluated the improvements and could show that we can reduce the communication overhead and transmission delay as well as that the average battery time for all sensors in a group is increased.

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  • 235.
    Kljajic, Haris
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Karlsson, Oskar
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Applying automated testing in an existing client-server game: A pursuit for fault localization in Quake 32015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper addresses the question formulation “Is it possible to implement automated testing in an existing client-server game in order to pinpoint faults and achieve credibility to tests?” The gaming industry’s goal, in most cases, is to release games that appeal to both their financial goals and the enjoyment factor of the players. In order to fulfill these goals, the game will need to function properly and the process to assure this is testing the game to find possible faults. This process is time and cost consuming in an exponential rate in accordance to game extensiveness, which makes this problem a very important decision in the process of development. The problem is most commonly tackled by using massive manual testing session, called alpha or beta sessions. In these session the game is at an early stage of development and gets released to a set player base to test and report issues encountered. We believe that the process of testing games could be more effective by utilizing automated testing. This thesis will investigate the possibilities to our claim. The result is a visual representation of the tests we managed to apply, while focusing on the client-server connectivity of Quake 3 and a graph of measurements for our improvised fault localization. This paper describes a solution in form of automated tests within a existing client-server game and a start to what could be early stages of a pattern obtained throughout this project.

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  • 236.
    Kourtesis, Marios
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Creating a Secure Server Architecture and Policy for Linux-based Systems2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Creating and maintaining servers for hosting services in a secure and reliable way is an important but complex and time-consuming task. Misconfiguration and lack of server maintenance can potentially make the system vulnerable. Hackers can exploit these vul­nerabilities in order to penetrate into the system internals and cause damage. Having a standard architecture/configuration supporting the needed services saves time and re­sources while it reduces security risks. A server architecture protected by a security policy can secure the integrity and quality of the overall services. This research demon­strates building a secure server architecture protected by a security policy. To achieve this a security policy and a checklist was designed and combined with a host based IDPS, a NMS and a WAF.

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  • 237.
    Kovbasiuk, Igor
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Design and Development of a Decision Making Application Using Analytic Hierarchy Process2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Every action a person takes is determined by the result of some decision. Making simple decisions is natural and does not require additional considerations. However, in case of multiple alternatives and criteria to be considered, decision-making technique is required. The most studied and developed technique is the Analytic Hierarchy Process(AHP).This thesis is focused on the practical implementation of AHP. Firstly, it defines a set of features that are necessary for the decision-making process involving several experts and additional non-functional requirements to be met. Feature comparison has shown that none of the existing applications implements all required features. Therefore, a new application is designed. Further on, the engineering process is described, including transforming functional requirements into features, features into use cases, use cases into activities diagrams. After the developed application is described screens corresponding to each use case are presented. Non-functional requirements are portability, free availability, and usability. Compliance of the developed application with these criteria is checked with tests and two user experiments.The main results of this thesis are: (i) the extension of AHP theory with external consistency check to improve the quality of final results and (ii) the developed application which meets all requirements.

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  • 238.
    Kovbasiuk, Igor
    et al.
    Softwerk.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Ericsson, Morgan
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Wingkvist, Anna
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Quick Decide: A Tool to Aid the Analytic Hierarchy Process for Group Decisions2015In: Perspectives in Business Informatics Research: 14th International Conference, BIR 2015, Tartu, Estonia, August 26-28, 2015, Proceedings / [ed] Raimundas Matulevičius, Marlon Dumas, Springer: Springer, 2015, Vol. 229, p. 179-193Conference paper (Refereed)
    Abstract [en]

    To take simple decisions comes naturally and does not re- quire additional considerations but when there are multiple alternatives and criteria to be considered, a decision-making technique is required. The most studied and developed technique is the Analytic Hierarchy Process (AHP). We focus on the practical implementation of AHP and study the set of features that are necessary when the process involves several experts together with a set of non-functional requirements, such as portability and usability. Since no existing tool satisfy all our require- ments, we design and implement a new AHP tool called Quick Decide. We perform a user experiment to evaluate our tool, and find that it fulfils all our requirements. To support our usability requirements, we extend AHP with an external consistency check, which measures the distance between expert opinions to avoid results that are mathematically correct but provide no semantic value (e.g., two opposite extreme opinions). 

  • 239.
    Krot, Andrii
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    New input methods for blind users on wide touch devices2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Blind people cannot enter text on touch devices using common input methods. They use special input methods that have lower performance (i.e. lower entry rate and higher error rate). Most blind people have muscle memory from using classic physical keyboards, but the potential of using this memory is not utilized by existing input methods. The goal of the project is to take advantage of this muscle memory to improve the typing performance of blind people on wide touch panels. To this end, four input methods are designed, and a prototype for each one is developed. These input methods are compared with each other and with a standard input method. The results of the comparison show that using input methods designed in this report improves typing performance. The most promising and the least promising approaches are specified.

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  • 240.
    Kruiger, Johannes F.
    et al.
    University of Groningen, Netherlands.
    Rauber, Paulo E.
    University of Groningen, Netherlands.
    Martins, Rafael Messias
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kobourov, Stephen
    The University of Arizona, USA.
    Telea, Alexandru C.
    University of Groningen, Netherlands.
    Graph Layouts by t-SNE2017In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 36, no 3, p. 283-294Article in journal (Refereed)
    Abstract [en]

    We propose a new graph layout method based on a modification of the t-distributed Stochastic Neighbor Embedding (t-SNE) dimensionality reduction technique. Although t-SNE is one of the best techniques for visualizing high-dimensional data as 2D scatterplots, t-SNE has not been used in the context of classical graph layout. We propose a new graph layout method, tsNET, based on representing a graph with a distance matrix, which together with a modified t-SNE cost function results in desirable layouts. We evaluate our method by a formal comparison with state-of-the-art methods, both visually and via established quality metrics on a comprehensive benchmark, containing real-world and synthetic graphs. As evidenced by the quality metrics and visual inspection, tsNET produces excellent layouts.

  • 241.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Cernea, Daniel
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Visualizing Excitement of Individuals and Groups2016In: Proceedings of the ACM IUI 2016 Workshop on Emotion and Visualization (EmoVis '16) / [ed] Andreas Kerren, Daniel Cernea, and Margit Pohl, Linköping, Sweden: Linköping University Electronic Press, 2016, p. 15-22Conference paper (Refereed)
    Abstract [en]

    Excitement or arousal is one of the main emotional dimensions that affects our lives on a daily basis. We win a tennis match, watch a great movie, get into an argument with a colleague—all of these are instances when most of us experience excitement, yet we do not pay much attention to it. Today, there are few systems that capture our excitement levels and even fewer that actually promote awareness of our most exciting moments. In this paper, we propose a visualization concept for representing individual and group-level excitement for emotional self-awareness and group-level awareness. The data used for the visualization is obtained from smart wristbands worn by each of the users. The visualization uses animated glyphs to generate a real-time representation for each individual’s excitement levels. We introduce two types of encodings for these glyphs: one focusing on capturing both the current excitement and the excitement history, as well as another focusing only on real-time values and previous peaks. The excitement levels are computed based on measurements of the user’s galvanic skin response and accelerometer data from the wristbands, allowing for a classification of the excitement levels into experienced (excitement without physical manifestation) and manifested excitement. A dynamic clustering of the individual glyphs supports the scalability of our visualization, while at the same time offering an overview of the group-level excitement and its distribution. The results of a preliminary evaluation suggest that the visualization allows users to intuitively and accurately perceive both individual and group-level excitement. 

  • 242.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Text Visualization Browser: A Visual Survey of Text Visualization Techniques2014In: Poster Abstracts of IEEE VIS 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Text visualization has become a growing and increasingly important subfield of information visualization. Thus, it is getting harder for researchers to look for related work with specific tasks or visual metaphors in mind. In this poster, we present an interactive visual survey of text visualization techniques that can be used for the purposes of search for related work, introduction to the subfield and gaining insight into research trends. 

  • 243.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Text Visualization Techniques: Taxonomy, Visual Survey, and Community Insights2015In: Proceedings of the 8th IEEE Pacific Visualization Symposium (PacificVis '15), / [ed] Shixia Liu, Gerik Scheuermann, and Shigeo Takahashi, IEEE, 2015, p. 117-121Conference paper (Refereed)
    Abstract [en]

    Text visualization has become a growing and increasingly important subfield of information visualization. Thus, it is getting harder for researchers to look for related work with specific tasks or visual metaphors in mind. In this paper, we present an interactive visual survey of text visualization techniques that can be used for the purposes of search for related work, introduction to the subfield and gaining insight into research trends. We describe the taxonomy used for categorization of text visualization techniques and compare it to approaches employed in several other surveys. Finally, we present results of analyses performed on the entries data. 

  • 244.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Paradis, Carita
    Lund University.
    Sahlgren, Magnus
    Gavagai AB, Sweden.
    Methodology and Applications of Visual Stance Analysis: An Interactive Demo2016In: International Symposium on Digital Humanities, Växjö 7-8 November 2016: Book of Abstracts, Linnaeus University , 2016, p. 56-57Conference paper (Refereed)
    Abstract [en]

    Analysis of stance in textual data can reveal the attitudes of speakers, ranging from general agreement/disagreement with other speakers to fine-grained indications of wishes and emotions. The implementation of an automatic stance classifier and corresponding visualization techniques facilitates the analysis of human communication and social media texts. Furthermore, scholars in Digital Humanities could also benefit from such an approach by applying it for literature studies. For example, a researcher could explore the usage of such stance categories as certainty or prediction in a novel. Analysis of such abstract categories in longer texts would be complicated or even impossible with simpler tools such as regular expression search.

    Our research on automatic and visual stance analysis is concerned with multiple theoretical and practical challenges in linguistics, computational linguistics, and information visualization. In this interactive demo, we demonstrate our web-based visual analytics system called ALVA, which is designed to support the text data annotation and stance classifier training stages. 

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    Abstract
  • 245.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Paradis, Carita
    Lund University.
    Sahlgren, Magnus
    Gavagai AB.
    Visual Analysis of Stance Markers in Online Social Media2014In: Poster Abstracts of IEEE VIS 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Stance in human communication is a linguistic concept relating to expressions of subjectivity such as the speakers’ attitudes and emotions. Taking stance is crucial for the social construction of meaning and can be useful for many application fields such as business intelligence, security analytics, or social media monitoring. In order to process large amounts of text data for stance analyses, linguists need interactive tools to explore the textual sources as well as the results of computational linguistics techniques. Both aspects are important for refining the analyses iteratively. In this work, we present a visual analytics tool for online social media text data and corresponding time-series that can be used to investigate stance phenomena and to refine the so-called stance markers collection. 

  • 246.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Paradis, Carita
    Lund University .
    Sahlgren, Magnus
    Gavagai AB.
    Visual Analysis of Text Annotations for Stance Classification with ALVA2016In: EuroVis Posters 2016 / [ed] Tobias Isenberg & Filip Sadlo, Eurographics - European Association for Computer Graphics, 2016, p. 49-51Conference paper (Refereed)
    Abstract [en]

    The automatic detection and classification of stance taking in text data using natural language processing and machine learning methods create an opportunity to gain insight about the writers’ feelings and attitudes towards their own and other people’s utterances. However, this task presents multiple challenges related to the training data collection as well as the actual classifier training. In order to facilitate the process of training a stance classifier, we propose a visual analytics approach called ALVA for text data annotation and visualization. Our approach supports the annotation process management and supplies annotators with a clean user interface for labeling utterances with several stance categories. The analysts are provided with a visualization of stance annotations which facilitates the analysis of categories used by the annotators. ALVA is already being used by our domain experts in linguistics and computational linguistics in order to improve the understanding of stance phenomena and to build a stance classifier for applications such as social media monitoring. 

  • 247.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Paradis, Carita
    Lund University, Sweden.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    DoSVis: Document Stance Visualization2018In: Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP '18) / [ed] Alexandru C. Telea, Andreas Kerren, and José Braz, SciTePress, 2018, Vol. 3, p. 168-175Conference paper (Refereed)
    Abstract [en]

    Text visualization techniques often make use of automatic text classification methods. One of such methods is stance analysis, which is concerned with detecting various aspects of the writer’s attitude towards utterances expressed in the text. Existing text visualization approaches for stance classification results are usually adapted to textual data consisting of individual utterances or short messages, and they are often designed for social media or debate monitoring tasks. In this paper, we propose a visualization approach called DoSVis (Document Stance Visualization) that focuses instead on individual text documents of a larger length. DoSVis provides an overview of multiple stance categories detected by our classifier at the utterance level as well as a detailed text view annotated with classification results, thus supporting both distant and close reading tasks. We describe our approach by discussing several application scenarios involving business reports and works of literature. 

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  • 248.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Paradis, Carita
    Lund University, Sweden.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    The State of the Art in Sentiment Visualization2018In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 37, no 1, p. 71-96, article id CGF13217Article in journal (Refereed)
    Abstract [en]

    Visualization of sentiments and opinions extracted from or annotated in texts has become a prominent topic of research over the last decade. From basic pie and bar charts used to illustrate customer reviews to extensive visual analytics systems involving novel representations, sentiment visualization techniques have evolved to deal with complex multidimensional data sets, including temporal, relational, and geospatial aspects. This contribution presents a survey of sentiment visualization techniques based on a detailed categorization. We describe the background of sentiment analysis, introduce a categorization for sentiment visualization techniques that includes 7 groups with 35 categories in total, and discuss 132 techniques from peer-reviewed publications together with an interactive web-based survey browser. Finally, we discuss insights and opportunities for further research in sentiment visualization. We expect this survey to be useful for visualization researchers whose interests include sentiment or other aspects of text data as well as researchers and practitioners from other disciplines in search of efficient visualization techniques applicable to their tasks and data. 

  • 249.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Paradis, Carita
    Lund University.
    Sahlgren, Magnus
    Swedish Research Institute (RISE SICS).
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Active Learning and Visual Analytics for Stance Classification with ALVA2017In: ACM Transactions on Interactive Intelligent Systems, ISSN 2160-6455, E-ISSN 2160-6463, Vol. 7, no 3, article id 14Article in journal (Refereed)
    Abstract [en]

    The automatic detection and classification of stance (e.g., certainty or agreement) in text data using natural language processing and machine learning methods create an opportunity to gain insight into the speakers' attitudes towards their own and other people's utterances. However, identifying stance in text presents many challenges related to training data collection and classifier training. In order to facilitate the entire process of training a stance classifier, we propose a visual analytics approach, called ALVA, for text data annotation and visualization. ALVA's interplay with the stance classifier follows an active learning strategy in order to select suitable candidate utterances for manual annotation. Our approach supports annotation process management and provides the annotators with a clean user interface for labeling utterances with multiple stance categories. ALVA also contains a visualization method to help analysts of the annotation and training process gain a better understanding of the categories used by the annotators. The visualization uses a novel visual representation, called CatCombos, which groups individual annotation items by the combination of stance categories. Additionally, our system makes a visualization of a vector space model available that is itself based on utterances. ALVA is already being used by our domain experts in linguistics and computational linguistics in order to improve the understanding of stance phenomena and to build a stance classifier for applications such as social media monitoring.

  • 250.
    Kucher, Kostiantyn
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Schamp-Bjerede, Teri
    Lund University.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Paradis, Carita
    Lund University.
    Sahlgren, Magnus
    Gavagai AB.
    Visual Analysis of Online Social Media to Open Up the Investigation of Stance Phenomena2016In: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 15, no 2, p. 93-116Article in journal (Refereed)
    Abstract [en]

    Online social media are a perfect text source for stance analysis. Stance in human communication is concerned with speaker attitudes, beliefs, feelings and opinions. Expressions of stance are associated with the speakers' view of what they are talking about and what is up for discussion and negotiation in the intersubjective exchange. Taking stance is thus crucial for the social construction of meaning. Increased knowledge of stance can be useful for many application fields such as business intelligence, security analytics, or social media monitoring. In order to process large amounts of text data for stance analyses, linguists need interactive tools to explore the textual sources as well as the processed data based on computational linguistics techniques. Both original texts and derived data are important for refining the analyses iteratively. In this work, we present a visual analytics tool for online social media text data that can be used to open up the investigation of stance phenomena. Our approach complements traditional linguistic analysis techniques and is based on the analysis of utterances associated with two stance categories: sentiment and certainty. Our contributions include (1) the description of a novel web-based solution for analyzing the use and patterns of stance meanings and expressions in human communication over time; and (2) specialized techniques used for visualizing analysis provenance and corpus overview/navigation. We demonstrate our approach by means of text media on a highly controversial scandal with regard to expressions of anger and provide an expert review from linguists who have been using our tool.

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