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  • 101.
    Carlsson, Daniel
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Einarsson, Peder
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Inledning till spelutveckling för AndroidSpelutveckling för Android med Java och OpenGL ES2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis deals with the problems you face as a new game developer for the mobile platform Android when developing a 3D game and presents solutions to these problems. It also explores which optimizations should be made to increase performance and how well suited for game development the Android platform is. A simple 3D game for version 2.2 of Android was developed to examine this. The conclusion was that a good game structure for Android separates logic and rendering by running these separately in different threads. Solutions to rendering and updating of game logic were presented and optimizations were implemented for performance, although fewer optimizations were needed than was anticipated. In conclusion, Android is well suited for game development and a powerful platform for developers.

  • 102.
    Carlsson, Emil
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Matching in MySQL: A comparison between REGEXP and LIKE2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When needing to search for data in multiple datasets there is a risk that not all da-tasets are of the same type. Some might be in XML-format; others might use a re-lational database. This could frighten developers from using two separate datasets to search for the data in, because of the fact that crafting different search methods for different datasets can be time consuming.

    One option that is greatly overlooked is the usage of regular expressions. If a search expression is created it can be used in a majority of database engines as a “WHERE” statement and also in other form of data sources such as XML.

    This option is however, at best, poorly documented and few tests have been made in how it performs against traditional search methods in databases such as “LIKE”.

    Multiple experiments comparing “LIKE” and “REGEXP” in MySQL have been performed for this paper. The results of these experiments show that the possible overhead by using regular expressions can be motivated when considering the gain of only using one search phrase over several data sources.

  • 103.
    Carlsson, Emil
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Mining Git Repositories: An introduction to repository mining2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When performing an analysis of the evolution of software quality and software metrics,there is a need to get access to as many versions of the source code as possible. There isa lack of research on how data or source code can be extracted from the source controlmanagement system Git. This thesis explores different possibilities to resolve thisproblem.

    Lately, there has been a boom in usage of the version control system Git. Githubalone hosts about 6,100,000 projects. Some well known projects and organizations thatuse Git are Linux, WordPress, and Facebook. Even with these figures and clients, thereare very few tools able to perform data extraction from Git repositories. A pre-studyshowed that there is a lack of standardization on how to share mining results, and themethods used to obtain them.

    There are several tools available for older version control systems, such as concurrentversions system (CVS), but few for Git. The examined repository mining applicationsfor Git are either poorly documented; or were built to be very purpose-specific to theproject for which they were designed.

    This thesis compiles a list of general issues encountered when using repositorymining as a tool for data gathering. A selection of existing repository mining tools wereevaluated towards a set of prerequisite criteria. The end result of this evaluation is thecreation of a new repository mining tool called Doris. This tool also includes a smallcode metrics analysis library to show how it can be extended.

  • 104.
    Carlsson, Jacob
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gashi, Edison
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    SSDs påverkan på MySQL: En prestandajämförelse2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Solid State Drives (SSD) are now becoming  more common as storage and is about to  become  an  alternative  to  magnetic  disks.  This  report  studied  how  to  best  utilize SSDs in a MySQL database. This study was carried out using experiments in which performance benchmarks were made to get an accurate view on which configuration of  SSDs  that  gives  the  best  performance  in  MySQL.  The  benchmarks  where  made with sql-bench and mysqlslap.   The  results  indicate  that  a  database  using  only  SSD  storage  performs  equal  to  a database of solid-state cache under the majority of the tests and shows better results than the remaining configurations that include a database on a single hard drive and a configuration with the transaction log on a SSD. 

  • 105.
    Carlsson, Jacob
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Lindell, Johnas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Prestandaskillnader mellan olika ZFS-implementationer2011Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
  • 106.
    Carlsson, Johan
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Optimisation of a Graph Visualization Tool: Vizz3D2006Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vizz3D is a graph visualization tool developed at Växjö University. It is used to visualize different aspects of software systems in 3D, based on the static analysis of source code. It can optionally use Java3D or OpenGL as a graphics library.

    In order to visualize huge 3D structures performance is very important. This comes from the fact that the structures must be redrawn with no delay when a user interacts with the system. If there were a delay the user would loose the cognitive orientation because his interaction and the feedback would not fit. Vizz3D was not capable to run huge visualizations fast enough, and therefore careful optimisation was essential. Additionally, the Vizz3D tool is just at the beginning of its software life cycle.

    For optimisation, JOGL (Java Bindings for OpenGL) was chosen. The extension with a JOGL version was necessary since the GL4Java (OpenGL for Java) wrapper used for the implementation of Vizz3D is no longer supported. JOGL was therefore needed for assuring future maintainability.

    The JOGL version of Vizz3D was optimised to be able to visualize huge graphs with acceptable performance. To determine what areas of Vizz3D that consumed most of its resources, the process of profiling were used. The system performance was improved according to several aspects: Computational performance, Scalability, Perceived performance, RAM footprint and Start-up time. The results were then evaluated by using benchmarking techniques. After optimisation, the performance of Vizz3D was improved a lot which led to that huge graphs now could be visualized with acceptable performance.

  • 107.
    Carlsson, Marcus
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Karlsson, Oscar
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Prestandaundersökning och återställning av degraderade RAID-system2010Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [sv]

    Denna B-uppsats tar upp prestanda och återställning mellan två vanligt förekommande mjukvarubaserade RAID-system. Mjukvarubaserad RAID har blivit mer och mer intressant eftersom det är ett billigt och bra sätt att skydda sig mot hårdvarufel på hårddiskar. Tidigare har det inneburit prestandaförluster om man inte har använt en hårdvarubaserad RAID kontroller men med dagens snabba processorer är det inte längre så. Hårddiskar går för eller senare sönder och för ett RAID-system som ska vara igång tjugofyra timmar om dygnet är det viktigt att det även då fungerar med bra prestanda. Denna undersökning visar hur mycket sämre prestandan blir under sådana omständigheter samt hur lång återställningstid man kan förvänta sig på ett datorssystem uppbyggt av delar för hemmabruk. Undersökningen utfördes på två olika typer mjukvarubaserad RAID, ett med mdadm på Ubuntu/Linux och ett med RAID-Z på OpenSolaris. På de systemen mättes läs- och skrivprestanda med programmet bonnie++ som skriver och läser en fil som var dubbelt så stor som primärminnet i datorn. Resultatet visar att prestandan försämras med 36 % när en hårddisk går sönder på ett system med mdadm men med RAID-Z ökar istället prestandan. På ett system med mdadm är återställningstiden för ett degraderat system är ungefär lika lång oavsett hur mycket information som finns lagrad på hårddiskarna. Däremot går det fortare med RAID-Z eftersom den på ett intelligent sätt bara återställer den del av hårddisken som används för lagring av filer.

     

  • 108.
    Caroline, Millgårdh
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Comparing Software Libraries2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When building an application, native or web-based, you can be faced with the dilemma of finding an external library that will fit your needs. This thesis investigates the problem from a commercial viability standpoint. A new Compliance Reporting System needed a chart library to create appealing dashboards and reports.

    The aim of the thesis was to develop a generic method for finding, comparing and testing software libraries. The method was developed making use of multiple phases which were then applied to different chart libraries for the Compliance Reporting System.

    The devised method did not result in the desired outcome of finding a library for the Compliance Reporting System. It did, however, contain a number of successful steps. The first set of prerequisites was used to define relevant search terms. The second set of prerequisites reduced the selection of libraries. The adaptability tests examined the APIs. It was also found that the quality of documentation and public interface of the library can influence the possibility of successful utilization. Testing the extendibility would also have been beneficial. As for chart libraries in general, a lexicon of standardized terminology would be of great benefit.

  • 109.
    Catherine, Catherine
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Simulation and Measurement of Non-Functional Properties of Web Services in a Service Market to Improve User Value2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 110.
    Caubet, Marc
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Cifuentes, Mònica
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Extracting metadata from textual documents and utilizing metadata for adding textual documents to an ontology2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The term Ontology is borrowed from philosophy, where an ontology is a systematic account of Existence. In Computer Science, ontology is a tool allowing the effective use of information, making it understandable and accessible to the computer. For these reasons, the study of ontologies gained growing interest recently.

    Our motivation is to create a tool able to build ontologies from a set of textual documents. We present a prototype implementation which extracts metadata from textual documents and uses the metadata for adding textual documents to an ontology. In this paper we will investigate which techniques we have available and which ones

    have been used to accomplish our problem. Finally, we will show a program written in Java which allows us to build ontologies from textual documents using our approach.

  • 111.
    Cernea, Daniel
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    User-Centered Collaborative Visualization2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The last couple of years have marked the entire field of information technology with the introduction of a new global resource, called data. Certainly, one can argue that large amounts of information and highly interconnected and complex datasets were available since the dawn of the computer and even centuries before. However, it has been only a few years since digital data has exponentially expended, diversified and interconnected into an overwhelming range of domains, generating an entire universe of zeros and ones. This universe represents a source of information with the potential of advancing a multitude of fields and sparking valuable insights. In order to obtain this information, this data needs to be explored, analyzed and interpreted.

    While a large set of problems can be addressed through automatic techniques from fields like artificial intelligence, machine learning or computer vision, there are various datasets and domains that still rely on the human intuition and experience in order to parse and discover hidden information. In such instances, the data is usually structured and represented in the form of an interactive visual representation that allows users to efficiently explore the data space and reach valuable insights. However, the experience, knowledge and intuition of a single person also has its limits. To address this, collaborative visualizations allow multiple users to communicate, interact and explore a visual representation by building on the different views and knowledge blocks contributed by each person.

    In this dissertation, we explore the potential of subjective measurements and user emotional awareness in collaborative scenarios as well as support flexible and user-centered collaboration in information visualization systems running on tabletop displays. We commence by introducing the concept of user-centered collaborative visualization (UCCV) and highlighting the context in which it applies. We continue with a thorough overview of the state-of-the-art in the areas of collaborative information visualization, subjectivity measurement and emotion visualization, combinable tabletop tangibles, as well as browsing history visualizations. Based on a new web browser history visualization for exploring user parallel browsing behavior, we introduce two novel user-centered techniques for supporting collaboration in co-located visualization systems. To begin with, we inspect the particularities of detecting user subjectivity through brain-computer interfaces, and present two emotion visualization techniques for touch and desktop interfaces. These visualizations offer real-time or post-task feedback about the users’ affective states, both in single-user and collaborative settings, thus increasing the emotional self-awareness and the awareness of other users’ emotions. For supporting collaborative interaction, a novel design for tabletop tangibles is described together with a set of specifically developed interactions for supporting tabletop collaboration. These ring-shaped tangibles minimize occlusion, support touch interaction, can act as interaction lenses, and describe logical operations through nesting operations. The visualization and the two UCCV techniques are each evaluated individually capturing a set of advantages and limitations of each approach. Additionally, the collaborative visualization supported by the two UCCV techniques is also collectively evaluated in three user studies that offer insight into the specifics of interpersonal interaction and task transition in collaborative visualization. The results show that the proposed collaboration support techniques do not only improve the efficiency of the visualization, but also help maintain the collaboration process and aid a balanced social interaction. 

  • 112.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. University of Kaiserslautern.
    Ebert, Achim
    University of Kaiserslautern.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Study of Emotion-triggered Adaptation Methods for Interactive Visualization2013In: UMAP 2013 Extended Proceedings: Late-Breaking Results, Project Papers and Workshop Proceedings of the 21st Conference on User Modeling, Adaptation, and Personalization. Rome, Italy, June 10-14, 2013 / [ed] Shlomo Berkovsky, Eelco Herder, Pasquale Lops & Olga C. Santos, CEUR-WS.org , 2013, Vol. 997, p. 9-16Conference paper (Refereed)
    Abstract [en]

    As the size and complexity of datasets increases, both visual-ization systems and their users are put under more pressure to oer quickand thorough insights about patterns hidden in this ocean of data. Whilenovel visualization techniques are being developed to better cope withthe various data contexts, users nd themselves increasingly often undermental bottlenecks that can induce a variety of emotions. In this paper,we execute a study to investigate the eectiveness of various emotion-triggered  adaptation  methods  for  visualization  systems.  The  emotionsconsidered are boredom and frustration, and are measured by means ofbrain-computer interface technology. Our ndings suggest that less intru-sive adaptive methods perform better at supporting users in overcomingemotional states with low valence or arousal, while more intrusive onestend to be misinterpreted or perceived as irritating.

  • 113.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Ebert, Achim
    Kerren, Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Morar, Valentina
    R3 - Un dispozitiv de intrare configurabil pentru interacţiunea liberă în spaţiu2010In: Romanian Journal of Human-Computer Interaction, ISSN 1843-4460, Vol. 3, p. 45-50Article in journal (Refereed)
    Abstract [un]

    În ultima perioadă s-a abordat tot mai des problema implementării unor dispozitive de intrare care să sprijine interacţiunea 3D prin oferirea a 6 sau a mai multor grade de libertate (degrees of freedom sau DoF). Cu toate acestea, astfel de dispozitive care să fie disponibile pentru interacţiune liberă în spaţiu - adică fără a fi necesară o suprafaţă ca sistem de referinţă, cum este cazul unui mouse - sunt proiectate doar pentru un tip restrâns de aplicaţii. De asemenea, aparatele de intrare de acest tip sunt rareori intuitive în utilizare şi limitate ca număr. Pentru a combate aceste probleme, în acest articol propunem un dispozitiv de complexitate şi costuri de implementare reduse, care poate fi utilizat în spaţiul liber şi este extrem de configurabil, susţinând nativ o interacţiune intuitivă cu variate medii virtuale. R3 (roll - rostogolire, rotate - rotire, rattle - agitare) oferă acurateţea necesară pentru navigare şi indicare - atât în 2D, cât şi în 3D – în aplicaţii de modelare şi jocuri, dar şi feedback tactil prin prezenţa unui trackball, toate acestea într-o manieră orientată spre utilizator. În plus, dispozitivul poate fi trecut uşor în modul de mouse, oferind astfel oricând suport pentru interacţiunea cu sistemele de operare convenţionale.

  • 114.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. University of Kaiserslautern, Germany.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Survey of Technologies on the Rise for Emotion-Enhanced Interaction2015In: Journal of Visual Languages and Computing, ISSN 1045-926X, E-ISSN 1095-8533, Vol. 31, no A, p. 70-86Article in journal (Refereed)
    Abstract [en]

    Emotions are a major part of the human existence and social interactions. Some might say that emotions are one of the aspects that make us truly human. However, while we express emotions in various life settings, the world of computing seems to struggle with supporting and incorporating the emotional dimension. In the last decades, the concept of affect has gotten a new upswing in research, moving beyond topics like market research and product development, and further exploring the area of emotion-enhanced interaction.

    In this article, we highlight techniques that have been employed more intensely for emotion measurement in the context of affective interaction. Besides capturing the functional principles behind these approaches and the inherent volatility of human emotions, we present relevant applications and establish a categorization of the roles of emotion detection in interaction. Based on these findings, we also capture the main challenges that emotion measuring technologies will have to overcome in order to enable a truly seamless emotion-driven interaction.

  • 115.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Kerren, Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Ebert, Achim
    Detecting Insight and Emotion in Visualization Applications with a Commercial EEG Headset2011In: Proceedings of the SIGRAD 2011 Conference on Evaluations of Graphics and Visualization - Efficiency, Usefulness, Accessibility, Usability, KTH, Stockholm, Sweden., Linköping: Linköping University Electronic Press , 2011, p. 53-60Conference paper (Refereed)
    Abstract [en]

    Insight represents a special element of knowledge building. From the beginning of their lives, humans experience moments of insight in which a certain idea or solution becomes as clear to them as never before. Especially in the field of visual representations, insight has the potential to be at the core of comprehension and pattern recognition. Still, one problem is that this moment of clarity is highly unpredictable and complex in nature, and many scientists have investigated different aspects of its generation process in the hope of capturing the essence of this eureka (Greek, for "I have found") moment.

    In this paper, we look at insight from the spectrum of information visualization. In particular, we inspect the possible correlation between epiphanies and emotional responses subjects experience when having an insight. In order to check the existence of such a connection, we employ a set of initial tests involving the EPOC mobile electroencephalographic (EEG) headset for detecting emotional responses generated by insights. The insights are generated by open-ended tasks that take the form of visual riddles and visualization applications. Our results suggest that there is a strong connection between insight and emotions like frustration and excitement. Moreover, measuring emotional responses via EEG during an insight-related problem solving results in non-intrusive, nearly automatic detection of the major Aha! moments the user experiences. We argue that this indirect detection of insights opens the door for the objective evaluation and comparison of various visualizations techniques.

  • 116.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics. University of Kaiserslauten, Germany.
    Olech, Peter-Scott
    University of Kaiserslauten, Germany.
    Ebert, Achim
    University of Kaiserslauten, Germany.
    Kerren, Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    EEG-based Measurement of Subjective Parameters in Evaluations2011In: HCI International 2011 Posters' Extended Abstracts: International Conference, HCI International 2011, Orlando, FL, USA, July 9-14, 2011, Proceedings, Part II / [ed] Stephanidis, Constantine, Berlin Heidelberg: Springer, 2011, p. 279-283Conference paper (Refereed)
    Abstract [en]

    Evaluating new approaches, be it new interaction techniques, new applications or even new hardware, is an important task, which has to be done to ensure both usability and user satisfaction. The drawback of evaluating subjective parameters is that this can be relatively time consuming, and the outcome is possibly quite imprecise. Considering the recent release of cost-efficient commercial EEG headsets, we propose the utilization of electro-encephalographic (EEG) devices for evaluation purposes. The goal of our research is to evaluate if a commercial EEG headset can provide cutting-edge support during user studies and evaluations. Our results are encouraging and suggest that wireless EEG technology is a viable alternative for measuring subjectivity in evaluation scenarios.

  • 117.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. University of Kaiserslautern, Germany.
    Truderung, Igor
    University of Kaiserslautern, Germany.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Ebert, Achim
    An Interactive Visualization for Tabbed Browsing Behavior Analysis2014In: Computer Vision, Imaging and Computer Graphics: Theory and Applications / [ed] Sebastiano Battiato, Sabine Coquillart, Robert S. Laramee, Andreas Kerren, and José Braz, Springer, 2014, p. 69-84Chapter in book (Refereed)
    Abstract [en]

    Web browsers are at the core of online user experience, enablinga wide range of Web applications, like communication, games, entertainment, development, etc. Additionally, given the variety and complexity of online-supported tasks, users have started parallelizing and organizing their online browser sessions by employing multiple browser windows and tabs. However, there are few solutions that support analysts and casual users in detecting and extracting patterns from these parallel browsing histories. In this paper we introduce WebComets, an interactive visualization for exploring multi-session multi-user parallel browsing logs. After highlighting visual and functional aspects of the system, we introduce a motif-based contextual search for enabling the filtering and comparison of user navigation patterns. We further highlight the functionality of WebComets with a use case. Our investigations suggest that parallel browser history visualization can offer better insight into user tabbed browsing behavior and support the recognition of online navigation patterns.

  • 118.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Truderung, Igor
    University of Kaiserslautern, Germany .
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Ebert, Achim
    University of Kaiserslautern, Germany .
    WebComets: A Tab-Oriented Approach for Browser History Visualization2013In: / [ed] S. Coquillart, C. Andujar, R. S. Laramee, A. Kerren, and J. Braz, SciTePress , 2013, p. 439-450Conference paper (Refereed)
    Abstract [en]

    Web browsers are our main gateways to the Internet. With their help we read articles, we learn, we listen to music, we share our thoughts and feelings, we write e-mails, or we chat. Current Web browser histories have mostly no visualization capabilities as well as limited options to filter patterns and information. Furthermore, such histories disregard the existence of parallel navigation in multiple browser windows andtabs. But a good understanding of parallel browsing behavior is of critical importance for the casual user and the behavioural analyst, while at the same time having implications in the design of search engines, Web sites and Web browsers. In this paper we present WebComets, an interactive visualization for extended browser histories. Our visualization employs browser histories that capture—among others—the taboriented, parallel nature of Web page navigation. Results presented in this paper suggest that WebComets better supports the analysis and comparison of parallel browsing and corresponding behavior patterns than common browser histories.

  • 119.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Univ Kaiserslautern, Germany.
    Weber, Christopher
    Univ Kaiserslautern, Germany.
    Ebert, Achim
    Univ Kaiserslautern, Germany.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Emotion-Prints: Interaction-Driven Emotion Visualization on Multi-Touch Interfaces2015In: Proceedings of SPIE 9397: Visualization and Data Analysis 2015, San Francisco, CA, USA, February 8-12, 2015 / [ed] David L. Kao, Ming C. Hao, Mark A. Livingston, and Thomas Wischgoll, SPIE - International Society for Optical Engineering, 2015, p. 9397-0A-Conference paper (Refereed)
    Abstract [en]

    Emotions are one of the unique aspects of human nature, and sadly at the same time one of the elements that our technological world is failing to capture and consider due to their subtlety and inherent complexity. But with the current dawn of new technologies that enable the interpretation of emotional states based on techniques involving facial expressions, speech and intonation, electrodermal response (EDS) and brain-computer interfaces (BCIs), we are finally able to access real-time user emotions in various system interfaces. In this paper we introduce emotion-prints, an approach for visualizing user emotional valence and arousal in the context of multi-touch systems. Our goal is to offer a standardized technique for representing user affective states in the moment when and at the location where the interaction occurs in order to increase affective self-awareness, support awareness in collaborative and competitive scenarios, and offer a framework for aiding the evaluation of touch applications through emotion visualization. We show that emotion-prints are not only independent of the shape of the graphical objects on the touch display, but also that they can be applied regardless of the acquisition technique used for detecting and interpreting user emotions. Moreover, our representation can encode any affective information that can be decomposed or reduced to Russell’s two-dimensional space of valence and arousal. Our approach is enforced by a BCI-based user study and a follow-up discussion of advantages and limitations. 

  • 120.
    Cernea, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. University of Kaiserslautern.
    Weber, Christopher
    UC Davis, Department of Computer Science.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Ebert, Achim
    University of Kaiserslautern.
    Group Affective Tone Awareness and Regulation through Virtual Agents2014In: Proceedings of the Workshop on Affective Agents: Fourteenth International Conference on Intelligent Virtual Agents (IVA 2014), 2014, p. 9-16Conference paper (Refereed)
    Abstract [en]

    It happens increasingly often that experts need to collaboratein order to exchange ideas, views and opinions on their path towardsunderstanding. However, every collaboration process is inherently fragileand involves a large set of human subjective aspects, including socialinteraction, personality, and emotions. In this paper we present Pogat,an affective virtual agent designed to support the collaboration processaround displays by increasing user awareness of the group affective tone.A positive group affective tone, where all the participants of a groupexperience emotions of a positive valence, has been linked to fosteringcreativity in groups and supporting the entire collaboration process. Atthe same time, a negative or inexistent group affective tone can suggestnegative emotions in some of the group members, emotions that canlead to an inefficient or even obstructed collaboration. A study of ourapproach suggests that Pogat can increase the awareness of the overallaffective state of the group as well as positively affect the efficiency ofgroups in collaborative scenarios.

  • 121.
    Cerrato, Loredana
    et al.
    KTH Computer Science and Communication.
    Ekeklint, Susanne
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering. Datalogi.
    Different ways of ending human-machine dialogues2002In: Proceeding of AAMAS'02, the first international joint conference in autonomous agents & multi-agent systems: Embodied conversational agents-let's specify and evaluate them!, Bologna , 2002, p. 5-Conference paper (Refereed)
    Abstract [en]

    More and more dialogue systems are developed to provide public services to inexperienced users. This makes the competition harder among developers and increases the interest in finding methods to evaluate and improve the overall performance of dialogue systems. The aim of this study is to propose a method to evaluate users’ satisfaction in dialogue interactions. The hypothesis being tested is that it is possible to derive information about the users’ satisfaction with the interaction, by simply analysing the way in which users ends the dialogues. The users' final utterances were analysed in order to classify the type of utterance and to find out some prosodic correlates that could signal the users' attitude towards the system. To test this hypothesis we carried out a preliminary analysis of the way in which users' of two Swedish multi-modal dialogue systems (namely August and Adapt) ended their interactions.

  • 122.
    Cerrato, Loredana
    et al.
    KTH Computer Science and Communication.
    Ekeklint, Susanne
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering. Datalogi.
    Evaluating users reactions to human-like interfaces: Prosodic and paralinguistic features as new evaluation measures for users’ satisfaction2004In: From Brows to Trust: Evaluating Embodied Conversational Agents, Kluwer Academic Publishers , 2004, p. 101-124Chapter in book (Refereed)
    Abstract [en]

    An increasing number of dialogue systems are deployed to provide public services in our everyday lives. They are becoming more service-minded and several of them provide different channels for interaction. The rationale is to make automatic services available in new environments and more attractive to use. From a developer perspective, this affects the complexity of the requirements elicitation activity, as new combinations and variations in end-user interaction need to considered. The aim of our investigation is to propose new parameters and metrics to evaluate multimodal dialogue systems endowed with embodied conversational agents (ECAs). These new metrics focus on the users, rather than on the system. Our assumption is that the intentional use of prosodic variation and the production of communicative non-verbal behaviour by users can give an indication of their attitude towards the system and might also help to evaluate the users' overall experience of the interaction. To test our hypothesis we carried out analyses on different Swedish corpora of interactions between users and multimodal dialogue systems. We analysed the prosodic variation in the way the users ended their interactions with the system and we observed the production of non-verbal communicative expressions by users. Our study supports the idea that the observation of users' prosodic variation and production of communicative non-verbal behaviour during the interaction with dialogue systems could be used as an indication of whether or not the users are satisfied with the system performance.

  • 123.
    Chatzimparmpas, Angelos
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Martins, Rafael Messias
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    t-viSNE: A Visual Inspector for the Exploration of t-SNE2018Conference paper (Refereed)
    Abstract [en]

    The use of t-Distributed Stochastic Neighborhood Embedding (t-SNE) for the visualization of multidimensional data has proven to be a popular approach, with applications published in a wide range of domains. Despite their usefulness, t-SNE plots can sometimes be hard to interpret or even misleading, which hurts the trustworthiness of the results. By opening the black box of the algorithm and showing insights into its behavior through visualization, we may learn how to use it in a more effective way. In this work, we present t-viSNE, a visual inspection tool that enables users to explore anomalies and assess the quality of t-SNE results by bringing forward aspects of the algorithm that would normally be lost after the dimensionality reduction process is finished.

  • 124.
    Cherkasov, Stanislav
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Framework integration in practice2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Development of modern software is a challenging task that requires software developers to leverageexisting functionality by means of reusable code structures, libraries, frameworks and middleware. This allows shortening development time and lowering costs, while keeping resulting software competitive, reliable and maintainable.However, developing software based on reuse of existing libraries and frameworks has its own challenges and requires programmers to be aware of the issuesthey might face.This paper discusses common difficultiesfaced by software developers while developing complex software systems based on reusable libraries and frameworks.The issuesare described along with possible solutions and exemplified by a custom UI framework named AxeZ. AxeZ is designed for customized UI development for Android phones and is built on top of OpenGL and Bullet Physics engine.As a result, AxeZ can be consideredan instanceof successfully designed framework, which implements solutions forthe challenges discussed in this paper. It provides an example of reusable framework targeted for wide area of application in UI programming

  • 125.
    Chernenko, Andrii
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Facilitating comprehension of Swift programs2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Program comprehension is the process of gaining knowledge about software system by extracting it from its source code or observing its behavior at runtime. Often, when documentation is unavailable or missing, this is the only reliable source of knowledge about the system, and the fact that up to 50% of total maintenance effort is spent understanding the system makes it even more important. The source code of large software systems contains thousands, sometimes millions of lines of code, motivating the need for automation, which can be achieved with the help of program comprehension tools. This makes comprehension tools an essential factor in the adoption of new programming languages. This work proposes a way to fill this gap in the ecosystem of Swift, a new, innovative programming language aiming to cover a wide range of applications while being safe, expressive, and performant. The proposed solution is to bridge the gap between Swift and VizzAnalyzer, a program analysis framework featuring a range of analyses and visualizations, as well as modular architecture which makes adding new analyses and visualizations easier. The idea is to define a formal model for representing Swift programs and mapping it to the common program model used by VizzAnalyzer as the basis for analyses and visualizations. In addition to that, this paper discusses the differences between Swift and programming languages which are already supported by VizzAnalyzer, as well as practical aspects of extracting the models of Swift programs from their source code.

  • 126.
    Cohen, Shavit
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    Creating Innovative Pedagogical Opportunities via “Treasure-HIT”: Mobile Treasure Hunt Games Generator2015Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In this thesis we are presenting a design-based research aimed to extend an existing mobile-based environment named “Treasure-HIT”. “Treasure-HIT” is an environment which uses the available mobile technology to enable teachers to conduct pedagogical “Treasure Hunt” games for their students. At baseline (January 2013), “Treasure-HIT” was at its early stages and has not yet been officially released; only a few teachers were granted access to it. The goal of this thesis was to test the system with teachres in order to understand the actual needs to detect difficulties and usabily limitations and to improve the system accordingy.The sudy was conducted as a design-based research that included three iterations. Within each iteration we have identified needs expressed by teachers and improved the relevant system features. The outcome of this thesis was the design, development and implementation of 7 different features that increased the usability of the “Treasure-HIT” environment and its potential to effectievy support the creation and enactment of pedagogical location based activities.

  • 127.
    Coimbra, Danilo B.
    et al.
    University of São Paulo, Brazil.
    Martins, Rafael Messias
    University of São Paulo, Brazil.
    Neves, Tácito T. A. T.
    University of São Paulo, Brazil.
    Telea, Alexandru C.
    University of Groningen, The Netherlands.
    Paulovich, Fernando V.
    University of São Paulo, Brazil.
    Explaining three-dimensional dimensionality reduction plots2016In: Information Visualization, ISSN 1473-8716, E-ISSN 1473-8724, Vol. 15, no 2, p. 154-172Article in journal (Refereed)
    Abstract [en]

    Understanding three-dimensional projections created by dimensionality reduction from high-variate datasets is very challenging. In particular, classical three-dimensional scatterplots used to display such projections do not explicitly show the relations between the projected points, the viewpoint used to visualize the projection, and the original data variables. To explore and explain such relations, we propose a set of interactive visualization techniques. First, we adapt and enhance biplots to show the data variables in the projected threedimensional space. Next, we use a set of interactive bar chart legends to show variables that are visible from a given viewpoint and also assist users to select an optimal viewpoint to examine a desired set of variables. Finally, we propose an interactive viewpoint legend that provides an overview of the information visible in a given three-dimensional projection from all possible viewpoints. Our techniques are simple to implement and can be applied to any dimensionality reduction technique. We demonstrate our techniques on the exploration of several real-world high-dimensional datasets.

  • 128.
    Collin, Imad
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Quality Assessment of Web Pages: is it worth the trouble?2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 129.
    Conrad, Jan
    Växjö University, Faculty of Mathematics/Science/Technology.
    Flexible User Interface - FLUSI2006Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cellular phone network has been increasing rapidly during the last years. For many people the mobile phone has become an every day gadget with a wide performance and functional range. The usage of technologies like GPRS, HSCSD, EDGE and UMTS as well as the bandwidth of networks and consequently the connectivity of the phones has also increased persistently. Coming along with that, three technologies, which are ubiquitous or pervasive computing, mobile and wireless networks and location-based technologies, are making rapid progress.

    The aim of this thesis is to offer an architecture for a location-based user interface in the intersection of the three technologies mentioned above. The system should work with a minimum of special hardware requirement. Not to overload the user with information, the user interface should be adaptable, context-aware and location-based. The context-data should remain extendible and adaptable.

  • 130. Coquillart, Sabine
    et al.
    Andujar, CarlosLaramee, Robert S.Kerren, AndreasLinnaeus University, Faculty of Technology, Department of Computer Science.Braz, José
    GRAPP 2013 and IVAPP 2013: Proceedings of the International Conference on Computer Graphics Theory and Applications and International Conference on Information Visualization Theory and Applications2013Conference proceedings (editor) (Refereed)
  • 131.
    Cosic, Admir
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Antonio, Michel
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Processförbättring med hjälp av TMMi-Modellen: Utvärdering av en testprocess på ett medelstort företag2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Storleken och komplexiteten på dagens system och applikationer ökar. Detta leder till att kraven på system och applikationer ökar också eftersom kunderna kräver av dagens system full funktionalitet inom olika typer av distribuerade miljöer. Kunder är inte bara intresserade av funktionerna i systemen och applikationerna, de förväntar sig också att systemet skall vara av god kvalitet. Av dessa skäl är det mycket viktigt att testa system och applikationer för att säkerställa att de uppfyller kundernas förväntningar. Däremot är det inte bara själva mjukvarans kvalitets frågor som organisationer behöver ha i åtanke, en lika viktig del är själva testprocessens kvalitet. För att öka testprocessens kvalitet  krävs det en utvärdering av processen. Utvärderingen identifierar processens styrkor, svagheter och möjligheter.

    I detta examensarbete har vi utvärderat tesprocessen på ett utvecklingsföretag. Utvärderingen har baserats på anvisningar och rekommendationer från TMMi-modellen, Test Maturity Model Integrated. Vi hade som mål att lyfta fram förbättringsförslag till företagets testprocess. Efter utvärderingen kom vi fram till vilken mognadsnivå verksamheten utifrån TMMi-modellen samt en mängd förbättringsförslag för att höja mognadsnivån på testprocessen.

  • 132.
    Covic, Mirjana
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Kohler, Thomas
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    IT security for small and medium-sized enterprises: A didactical concept of a dynamical questionnaire2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis has been written at the School of Mathematics and System Engineering (MSI) at Växjö University in the field of computer science. IT security has become one of the main topics of every enterprise since they all use information technology in their business. Investments have to be done in order to achieve a high protection status of the IT environments. Specially small and medium-sized enterprises need more knowledge and advisory how to handle their IT security. This thesis analyses management tools that have the goal to improve the IT security. The second and main part of the thesis is the design of a tool that should helps to solve the described problems.

  • 133.
    Dadzie, Aba-Sah
    et al.
    KMi, The Open University, UK.
    Müller, Maximilian
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    Alissandrakis, Aris
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    Milrad, Marcelo
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    Collaborative Learning through Creative Video Composition on Distributed User Interfaces2016In: State-of-the-Art and Future Directions of Smart Learning / [ed] Li, Y., Chang, M., Kravcik, M., Popescu, E., Huang, R., Kinshuk, Chen, N.-S., Springer, 2016, 1, p. 199-210Chapter in book (Refereed)
    Abstract [en]

    We report two studies that fed into user-centred design for pedagogical and technological scaffolds for social, constructive learning through creative, collaborative, reflective video composition. The studies validated this learning approach and verified the utility and usability of an initial prototype (scaffold) built to support it. However, challenges in interaction with the target technology, multi-touch tabletops, impacted ability to carry out prescribed learning activities. Our findings point to the need to investigate an alternative approach and informed redesign of our scaffolds. We propose coupling of distributed user interfaces, using mobile devices to access large, shared displays, to augment capability to follow our constructive learning process. We discuss also the need to manage recognised challenges to collaboration with a distributed approach.

  • 134.
    Dahal, Abhinav
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Saheb, Azal
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Architectural Agents2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a complex and ever changing software environment, controlling and coordinating asoftware system's architecture and its components have become an almost an impossibletask. It takes a lot of effort from a developer and even then it is not a foolproof plan. In thisMasters thesis, we introduce Architectural Agents. Architectural agents are specializedconfigurable components. They are the key elements that make a software environmentself-adaptive. Should there be any problem in the software, the architectural agents havingmonitored the software architecture can know which component is having the problem andfix it.This thesis aims towards making software self-adaptive by using Architectural Agents.This can be achieved by combining two frameworks namely, Prism-MW and JADE. Eachof these frameworks have their own property that contribute towards achieving the goal ofthe thesis. Prism-MW decomposes a software into separate and easily manageablecomponents. JADE on the other hand, creates agents. Combining these two frameworksmeans using the agents to control the software components. This will make the softwareenvironment self-adaptive.We support our claims and theories by practically proving them.

  • 135.
    Dahl, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Nylander, Kristofer
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Differences in security between native applications and web based applications in the field of health care2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Developing native applications for different platforms with different resolutions and screen sizes is both time consuming and costly. If developers were able to develop one web based application which can be used on multiple platforms, yet retain the same level of security as a native application, they would be able to reduce both development time and costs.

    In this thesis we will investigate the possibilities of achieving a level of security in a web-based application that can equal that of a native application, as well as how to develop an application that uses the Mina Vårdkontakter (My Healthcare Contacts) framework.

  • 136.
    Dahlstein, Marcus
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Nilsson, Mats
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Datasäkerhet: Hur man skyddar sig mot interna hot2005Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As the companies of today are good at protecting themselves against external threats, but are having problems with internal threats, we focused on how information can be protected from ending up in the wrong hands. First and foremost to protect information from employees who might steal it and sell it to another company. Since the security investments needed are connected to the financial costs of implementing them we have tried to create a balance between the investments needed and the cost of implementing them. The different kinds of protection needed are first and foremost protection to make data less accessable, passwords and traceability. While it is hard for us to estimate the amount of money a company lose by the hour when the production stands still, we have not been able to use any of the excising models to calculate the profit of installing countermeasures. We have, however, been able to find a model that works excellent for the average company who is beginning to install computer security.

  • 137.
    Dalipi, Fisnik
    et al.
    State University of Tetova, Makedonia.
    Idrizi, Florim
    State University of Tetova, Makedonia.
    Kamberi, Lazim
    State University of Tetova, Makedonia.
    Determinants of e-business and ICT adoption among SMEs in Macedonia: An application of TOE Framework2011In: International Symposium on Computing in Informatics and Mathematics; 1st International Symposium on Computing in Informatics and Mathematics, International Symposium on Computing in Informatics and Mathematics , 2011, p. 111-124Conference paper (Refereed)
    Abstract [en]

    Research has demonstrated that firms using e-business culminate with considerable returns through efficiency improvement, inventory reduction, sales increase,customer relationship enhancement, new market penetration, and ultimatelyfinancial returns. However, there is little systematic research in terms of e-businessadoption patterns in firms using TOE (Technology-Organization-Environment)framework. This paper illustrates the potential of adoption and use of ICT and ebusinessapplications in small and medium sized enterprises (SMEs) in Macedonia.In the paper we present preliminary results of a survey of around 60 SMEs. In thisstudy we explore several factors enabling or impeding the successful adoption anduse of e-business and ICT by Macedonian SMEs. Based on technologyenvironment-organization (TOE) theory, three aspects influence e-business adoption: technological context (we explore technology integration among firms,more specifically the type of ICT adoption and applications), organizational context(we try to discover the motivations to invest in ICT, the benefits and barriers of ICTand e-business in particular) and environmental context (here we investigate trusted sources of IT advice, challenges of implementations and competitive pressure). Wefind that SMEs are generally satisfied with their investment in ICT but they are concerned about the cost of such investments and are uncertain about the business benefits, failing to recognize ICT's strategic potential to increase business flexibility, to increase productivity and to support globalization. Besides the concern about the ICT related cost, other major obstacles in adopting ICT were lackof internal ICT capabilities and lack of information about selecting, implementing and evaluating suitable ICT solutions. Our findings have important implications for policy aimed at ICT adoption and use by SMEs and will provide a foundation forfuture research by helping policy makers to understand, assist and support the SME sector.

  • 138.
    Dalipi, Fisnik
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science. RISE Interactive Institute.
    Zdravkova, Katerina
    Ss. Cyril and Methodius University, Macedonia.
    Ahmedi, Lule
    University of Prishtina, Serbia.
    Rethinking the conventional learning paradigm towards MOOC based flipped classroom learning2017In: 16th International Conference on Information Technology Based Higher Education and Training (ITHET), 10-12 June, 2017, Ohrid, Macedonia, IEEE, 2017, article id 8067791Conference paper (Refereed)
    Abstract [en]

    The recent proliferation of Massive Open Online Courses (MOOCs) has initiated a plethora of research endeavors revolving around new pedagogical methods in higher education. Integrating MOOCs in blended learning can be beneficial in different ways for both learners and instructors. In this position paper, we aim to provide a brief and comprehensive review about the challenges that higher education institutions in Macedonia and Kosovo face while coping with the new trends of flexible or blended learning. Moreover, after describing some real cases of MOOC based flipped classroom learning, we also provide some recommendations in order to enhance and enrich learning experience by employing innovative pedagogies.

  • 139.
    Dalipi, Fisnik
    et al.
    Tetovo State University, Makedonien.
    Ninka, Ilia
    Tirana University, Albanien.
    Shej, Ajri
    Tetovo State University, Makedonien.
    Applying semantically adapted vector space model to enhance information retrieval2012In: ICT Innovations 2012 Web Proceedings: Poster Session / [ed] S. Markovski, M. Gusev, Ohrid: ICT ACT , 2012, p. 573-575Conference paper (Refereed)
    Abstract [en]

    Abstract. While most enterprise data is unstructured and file based, the need for access to structured data is increasing. In order to reduce the cost for finding information and achieve relevant results there is a need to build a very complex query which indeed is a serious challenge. Data volumes are growing at 60% annually and up to 80% of this data in any organization can be unstructured. In this paper we focus on describing the evolution of some modern ontology-based information retrieval systems. Further, we will provide a brief overview of the key advances in the field of semantic information retrieval from heterogeneous information sources, and a description of where the state-of-the-art is at in the field. Finally, we present and propose a novel use of semantic retrieval model based on the vector space model for the exploitation of KB (Knowledge Base) to enhance and support searching over robust and heterogeneous environments.

  • 140.
    Dalipi, Fisnik
    et al.
    Gjøvik University College, Norway.
    Yayilgan, Sule Yildirim
    Gjøvik University College, Norway.
    Gebremedhin, Alemayehu
    Faculty of Technology and Management, Norway.
    A machine learning approach to increase energy efficiency in district heating systems2015In: Environmental Engineering and Computer Application: Proceedings of the International Conference on Environmental Engineering and Computer Application, ICEECA 2014, Hong kong: CRC Press, 2015, p. 223-226Conference paper (Refereed)
    Abstract [en]

    Heat demand prediction is an important part of increasing system efficiency within district heating. To achieve this efficiency, the energy provider companies need to estimate how much energy is re quired to satisfy the market demand. In this paper, we propose a method to investigate the application of online ma chine learning algorithm to achieve energy efficiency and optimization in District Heating (DH) systems by predicting the heat demand on the consumer side. To accomplish this, we are planning to use operational data from a Norwegian company (EffektivEnergi AS, Hamar) for a group of buildings that are connected to DH in other places.

  • 141.
    Dalipi, Fisnik
    et al.
    Norwegian University of Science and Technology, Norway.
    Yayilgan, Sule Yildirim
    Norwegian University of Science and Technology, Norway.
    Gebremedhin, Alemayehu
    Norwegian University of Science and Technology, Norway.
    Data-Driven Machine Learning Model in District Heating System for Heat Load Prediction: A Comparison Study2016In: Applied Computational Intelligence and Soft Computing, ISSN 1687-9724, E-ISSN 1687-9732, article id 3403150Article in journal (Refereed)
    Abstract [en]

    We present our data-driven supervised machine-learning (ML) model to predict heat load for buildings in a district heating system (DHS). Even though ML has been used as an approach to heat load prediction in literature, it is hard to select an approach that will qualify as a solution for our case as existing solutions are quite problem specific. For that reason, we compared and evaluated three ML algorithms within a framework on operational data from a DH system in order to generate the required prediction model. The algorithms examined are Support Vector Regression (SVR), Partial Least Square (PLS), and random forest (RF). We use the data collected from buildings at several locations for a period of 29 weeks. Concerning the accuracy of predicting the heat load, we evaluate the performance of the proposed algorithms using mean absolute error (MAE), mean absolute percentage error (MAPE), and correlation coefficient. In order to determine which algorithm had the best accuracy, we conducted performance comparison among these ML algorithms. The comparison of the algorithms indicates that, for DH heat load prediction, SVR method presented in this paper is the most efficient one out of the three also compared to other methods found in the literature.

  • 142.
    Dallner, Björn
    et al.
    University of Kalmar, Kalmar Maritime Academy.
    Holmen, Martin
    University of Kalmar, Kalmar Maritime Academy.
    Spanier, Lars
    University of Kalmar, Kalmar Maritime Academy.
    Svenskt Skeppshistoriskt Register: Datorapplikation2008Independent thesis Basic level (professional degree), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    Our objective with this diploma thesis was to build a computer application to a maritime society on the island Donsö. They want to use the application to compile a Swedish Shiphistorical Register with the help of the information they have collected bye the maritime society during modern time. The idea emerged when one member from the projekt group where out as a cadet and the captain told him about his card index with ship history. During the spring contact with said captain was re-established and a request to get premission to create an application and adjecent database working in project form using project as the type of work within the limits of degree project was sent, and approved. We concentrated our efforts to create an easy to manage database ther several user simultanously could both register and search for data. The time needed in the end turned out to be greater than within the time-frame and the limits of the size of the course, for this reason the application is not finished during the writing of this diploma thesis. We took a decision to prolong the time-frame outside the limits of a degree project and complete the application for delivery before the end of the semester.

  • 143.
    Dam, Mads
    et al.
    KTH Royal Institute of Technology.
    Guanciale, Roberto
    KTH Royal Institute of Technology.
    Khakpour, Narges
    KTH Royal Institute of Technology.
    Nemati, Hamed
    KTH Royal Institute of Technology.
    Schwartz, Oliver
    SICS Swedish ICT.
    Formal verification of information flow security for a simple arm-based separation kernel2013In: Proceedings of the 2013 ACM SIGSAC conference on Computer & communications security, ACM Press, 2013, p. 223-234Conference paper (Refereed)
    Abstract [en]

    A separation kernel simulates a distributed environment using a single physical machine by executing partitions in isolation and appropriately controlling communication among them. We present a formal verification of information flow security for a simple separation kernel for ARMv7. Previous work on information flow kernel security leaves communication to be handled by model-external means, and cannot be used to draw conclusions when there is explicit interaction between partitions. We propose a different approach where communication between partitions is made explicit and the information flow is analyzed in the presence of such a channel. Limiting the kernel functionality as much as meaningfully possible, we accomplish a detailed analysis and verification of the system, proving its correctness at the level of the ARMv7 assembly. As a sanity check we show how the security condition is reduced to noninterference in the special case where no communication takes place. The verification is done in HOL4 taking the Cambridge model of ARM as basis, transferring verification tasks on the actual assembly code to an adaptation of the BAP binary analysis tool developed at CMU.

  • 144.
    Danylenko, Antonina
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Decision Algebra: A General Approach to Learning and Using Classifiers2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Processing decision information is a vital part of Computer Science fields in which pattern recognition problems arise. Decision information can be generalized as alternative decisions (or classes), attributes and attribute values, which are the basis for classification. Different classification approaches exist, such as decision trees, decision tables and Naïve Bayesian classifiers, which capture and manipulate decision information in order to construct a specific decision model (or classifier). These approaches are often tightly coupled to learning strategies, special data structures and the special characteristics of the decision information captured, etc. The approaches are also connected to the way of how certain problems are addressed, e.g., memory consumption, low accuracy, etc. This situation causes problems for a simple choice, comparison, combination and manipulation of different decision models learned over the same or different samples of decision information. The choice and comparison of decision models are not merely the choice of a model with a higher prediction accuracy and a comparison of prediction accuracies, respectively. We also need to take into account that a decision model, when used in a certain application, often has an impact on the application's performance. Often, the combination and manipulation of different decision models are implementation- or application-specific, thus, lacking the generality that leads to the construction of decision models with combined or modified decision information. They also become difficult to transfer from one application domain to another. In order to unify different approaches, we define Decision Algebra, a theoretical framework that presents decision models as higher order decision functions that abstract from their implementation details. Decision Algebra defines the operations necessary to decide, combine, approximate, and manipulate decision functions along with operation signatures and general algebraic laws. Due to its algebraic completeness (i.e., a complete algebraic semantics of operations and its implementation efficiency), defining and developing decision models is simple as such instances require implementing just one core operation based on which other operations can be derived. Another advantage of Decision Algebra is composability: it allows for combination of decision models constructed using different approaches. The accuracy and learning convergence properties of the combined model can be proven regardless of the actual approach. In addition, the applications that process decision information can be defined using Decision Algebra regardless of the different classification approaches. For example, we use Decision Algebra in a context-aware composition domain, where we showed that context-aware applications improve performance when using Decision Algebra. In addition, we suggest an approach to integrate this context-aware component into legacy applications.

  • 145.
    Danylenko, Antonina
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Decisions: Algebra and Implementation2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Processing decision information is a constitutive part in a number of applicationsin Computer Science fields. In general, decision information can be used to deduce the relationship between a certain context and a certain decision. Decision information is represented by a decision model that captures this information. Frequently used examples of decision models are decision tables and decision trees. The choice of an appropriate decision model has an impact on application performance in terms of memory consumption and execution time. High memory expenses can possibly occur due to redundancy in a decision model; and high execution time is often a consequence of an unsuitable decision model.

    Applications in different domains try to overcome these problems by introducing new data structures or algorithms for implementing decision models. These solutions are usually domain-specificand hard to transfer from one domain to another. Different application domains of Computer Science often process decision information in a similar way and, hence, have similar problems. We should thus be able to present a unifying approach that can be applicable in all application domains for capturing and manipulating decision information. Therefore, the goal of this thesis is (i) to suggest a general structure(Decision Algebra) which provides a common theoretical framework that captures decision information and defines operations (signatures) for storing, accessing, merging, approximating, and manipulating such information along with some general algebraic laws regardless of the used implementation. Our Decision Algebra allows defining different construction strategiesfor decision models and data structures that capture decision information as implementation variants, and it simplifies experimental comparisons between them.

    Additionally, this thesis presents (ii) an implementation of Decision Algebra capturing the information in a non-redundant way and performing the operations efficiently. In fact, we show that existing decision models that originated in the field of Data Mining and Machine Learning and variants thereof as exploited in special algorithms can be understood as alternative implementation variants of the Decision Algebra by varying the implementations of the Decision Algebra operations. Hence, this work (iii) will contribute to a classification of existing technology for processing decision information in different application domains of Computer Science.

  • 146.
    Danylenko, Antonina
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Lundberg, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Löwe, Welf
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Decisions: Algebra and Implementation2011In: Machine Learning and Data Mining in Pattern Recognition: 7th International Conference on Machine Learning and Data Mining in Pattern Recognition, MLDM 2011, New York, NY, USA, August/September 2011, Proceedings / [ed] Perner, Petra, Berlin, Heidelberg: Springer, 2011, Vol. 6871, p. 31-45Chapter in book (Refereed)
    Abstract [en]

    This paper presents a generalized theory for capturing and manipulating classification information. We define decision algebra which models decision-based classifiers as higher order decision functions abstracting from implementations using decision trees (or similar), decision rules, and decision tables. As a proof of the decision algebra concept we compare decision trees with decision graphs, yet another instantiation of the proposed theoretical framework, which implement the decision algebra operations efficiently and capture classification information in a non-redundant way. Compared to classical decision tree implementations, decision graphs gain learning and classification speed up to 20% without accuracy loss and reduce memory consumption by 44%. This is confirmed by experiments.

  • 147.
    Danylenko, Antonina
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Lundberg, Jonas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Decisions: Algebra, Implementation, and First Experiments2014In: Journal of universal computer science (Online), ISSN 0948-695X, E-ISSN 0948-6968, Vol. 20, no 9, p. 1174-1231Article in journal (Refereed)
    Abstract [en]

    Classification is a constitutive part in many different fields of Computer Science. There exist several approaches that capture and manipulate classification information in order to construct a specific classification model. These approaches are often tightly coupled to certain learning strategies, special data structures for capturing the models, and to how common problems, e.g. fragmentation, replication and model overfitting, are addressed. In order to unify these different classification approaches, we define a Decision Algebra which defines models for classification as higher order decision functions abstracting from their implementations using decision trees (or similar), decision rules, decision tables, etc. Decision Algebra defines operations for learning, applying, storing, merging, approximating, and manipulating models for classification, along with some general algebraic laws regardless of the implementation used. The Decision Algebra abstraction has several advantages. First, several useful Decision Algebra operations (e.g., learning and deciding) can be derived based on the implementation of a few core operations (including merging and approximating). Second, applications using classification can be defined regardless of the different approaches. Third, certain properties of Decision Algebra operations can be proved regardless of the actual implementation. For instance, we show that the merger of a series of probably accurate decision functions is even more accurate, which can be exploited for efficient and general online learning. As a proof of the Decision Algebra concept, we compare decision trees with decision graphs, an efficient implementation of the Decision Algebra core operations, which capture classification models in a non-redundant way. Compared to classical decision tree implementations, decision graphs are 20% faster in learning and classification without accuracy loss and reduce memory consumption by 44%. This is the result of experiments on a number of standard benchmark data sets comparing accuracy, access time, and size of decision graphs and trees as constructed by the standard C4.5 algorithm. Finally, in order to test our hypothesis about increased accuracy when merging decision functions, we merged a series of decision graphs constructed over the data sets. The result shows that on each step the accuracy of the merged decision graph increases with the final accuracy growth of up to 16%.

  • 148.
    Danylenko, Antonina
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Löwe, Welf
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Adaptation of Legacy Codes to Context-Aware Composition Using Aspect-Oriented Programming2012In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 7306, p. 68-85Article in journal (Refereed)
    Abstract [en]

    The context-aware composition approach (CAC) has shown to improve the performance of object-oriented applications on modern multi-core hardware by selecting between different (sequential and parallel) component variants in different (call and hardware) contexts. However, introducing CAC in legacy applications can be time-consuming and requires quite some effort for changing and adapting the existing code.We observe that CAC-concerns, like offline component variant profiling and runtime selection of the champion variant, can be separated from the legacy application code. We suggest separating and reusing these CAC concerns when introducing CAC to different legacy applications.

    For automating this process, we propose an approach based on Aspect-Oriented Programming (AOP) and Reflective Programming. It shows that manual adaptation to CAC requires more programming than the AOP-based approach; almost three times in our experiments. Moreover, the AOP-based approach speeds up the execution time of the legacy code, in our experiments by factors of up to 2.3 and 3.4 on multi-core machines with two and eight cores, respectively. The AOP based approach only introduces a small runtime overhead compared to the manually optimized CAC approach. For different problems, this overhead is about 2-9% of the manual adaptation approach. These results suggest that AOP-based adaptation can effectively adapt legacy applications to CAC which makes them running efficiently even on multi-core machines.

  • 149.
    Danylenko, Antonina
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Löwe, Welf
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Context-Aware Recommender Systems for Non-functional Requirements2012In: Third International Workshop on Recommendation Systems for Software Engineering (RSSE 2012), 2012, p. 80-84Conference paper (Refereed)
    Abstract [en]

    For large software projects, system designers have to adhere to a significant number of functional and non-functional requirements, which makes software development a complex engineering task. If these requirements change during the development process, complexity even increases. In this paper, we suggest recommendation systems based on context-aware composition to enable a system designer to postpone and automate decisions regarding efficiency non-functional requirements, such as performance, and focus on the design of the core functionality of the system instead.

    Context-aware composition suggests the optimal component variants of a system for different static contexts (e.g., software and hardware environment) or even different dynamic contexts (e.g., actual parameters and resource utilization). Thus, an efficiency non-functional requirement can be automatically optimized statically or dynamically by providing possible component variants. Such a recommender system reduces time and effort spent on manually developing optimal applications that adapts to different (static or dynamic) contexts and even changes thereof.

  • 150.
    Danylenko, Antonina
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Merging Classifiers of Different Classification Approaches2014In: 2014 IEEE International Conference on Data Mining Workshop (ICDMW), IEEE Press, 2014, p. 706-715Conference paper (Refereed)
    Abstract [en]

    Classification approaches, e.g. Decision trees or Naive Bayesian classifiers, are often tightly coupled to learning strategies, special data structures, the type of information captured, and to how common problems, e.g. Over fitting, are addressed. This prevents a simple combination of classifiers of differentclassification approaches learned over different data sets. Many different methods of combiningclassification models have been proposed. However, most of them are based on a combination of the actual result of classification rather then producing a new, possibly more accurate, classifier capturing the combined classification information. In this paper we propose a new general approach to combiningdifferent classification models based on a concept of Decision Algebra which provides a unified formalization of classification approaches as higher order decision functions. It defines a general combining operation, referred to as merge operation, abstracting from implementation details of differentclassifiers. We show that the combination of a series of probably accurate decision functions (regardless of the actual implementation) is even more accurate. This can be exploited, e.g., For distributed learning and for efficient general online learning. We support our results by combining a series of decision graphs and Naive Bayesian classifiers learned from random samples of the data sets. The result shows that on each step the accuracy of the combined classifier increases, with a total accuracy growth of up to 17%.

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