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  • 401.
    Sun, Ang
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Comparison of Java Persistence Layer Technologies2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As data and data structures grown more complex in computing, the task of storing and accessing such data efficiently also becomes more complex. Object-oriented programming languages such as Java have popularized the practice of using class-based objects and created the challenge of persisting these complex objects to storage systems such as databases which only store simple scalar values. This paper seeks to explore and compare a selected num-ber of popular persistence solutions for the Java language in their use and per-formance. This is done through researching, implementing and performance testing the chosen candidates. Through these steps we have found that while more abstracted solutions provided easier implementation and usage, these positives come with the disadvantages of generally slower performance. We also discovered that while many persistence frameworks provide features that minimize the amount of code required for implementation, they suffer from performance issues such as the N+1 query issue if not configured or utilized correctly.

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  • 402.
    Sun, Xuebo
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Wang, Yudan
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    An Application of Dimension Reduction for Intention Groups in Reddit2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Reddit (www.reddit.com) is a social news platform for information sharing and exchanging. The amount of data, in terms of both observations and dimensions is enormous because a large number of users express all aspects of knowledge in their own lives by publishing the comments. While it’s easy for a human being to understand the Reddit comments on an individual basis, it is a tremendous challenge to use a computer and extract insights from it. In this thesis, we seek one algorithmic driven approach to analyze both the unique Reddit data structure and the relations inside owners of comments by their similar features. We explore the various types of communications between two people with common characteristics and build a special communication model that characterizes the potential relationship between two users via their communication messages. We then seek a dimensionality reduction methodology that can merge users with similar behavior into same groups. Along the process, we develop computer program to collect data, define attributes based on the communication model and apply a rule-based group merging algorithm. We then evaluate the results to show the effectiveness of this methodology. Our results show reasonable success in producing user groups that have recognizable group characteristics and share similar intentions.

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    Master Thesis Report - Xuebo Sun and Yudan Wang
  • 403.
    Svensson, Jesper
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Berisha, Ideal
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Generisk Felkodsfunktionalitet2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    BSR Svenska AB have developed a diagnostic device for cars and the task at hand is to develop this device called PPC diagnostic to make it compatible with generic OBDII codes. This will make it easier for the ordinary person to control their cars and check if there is anything wrong, that is contained in the generic protocol. This includes mostly a lot of probes weather they are ok or not and also a lot of values for temperature and similar stuff, but the most important part of the generic fault codes is the environmental fault codes.

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  • 404.
    Svensson, Kristoffer
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Sentiment Analysis With Convolutional Neural Networks: Classifying sentiment in Swedish reviews2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today many companies exist and market their products and services on social medias, and therefore may receive reviews and thoughts from their end-users directly in these social medias. Reading every text by hand can be time-consuming, so by analysing the sentiment for all texts give the companies an overview how positive or negative the users are on a specific subject. Sentiment analysis is a feature that Beanloop AB is interested in implementing in their future projects and this thesis research problem was to investigate how deep learning could be used for this task. It was done by conducting an experiment with deep learning and neural networks. Several convolutional neural network models were implemented with different settings to find a combination of settings that gave the highest accuracy on the given test dataset. There were two different kind of models, one kind classifying positive and negative, and the second classified the previous two categories but also neutral. The training dataset and the test dataset contained data from two recommendation sites, www.reco.se and se.trustpilot.com. The final result shows that when classifying three categories (positive, negative and neutral) the models had problems to reach an accuracy at 85%, were only one model reached 80% accuracy as best on the test dataset. However, when only classifying two categories (positive and negative) the models showed very good results and reached almost 95% accuracy for every model.

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    Deep learning thesis
  • 405.
    Svensson, Marcus
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Dynamic Strategy in Real-Time Strategy Games: with the use of finite-state machines2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Developing real-time strategy game AI is a challenging task due to that an AI-player has to deal with many different decisions and actions in an ever changing complex game world. Humans have little problem when it comes to dealing with the complexity of the game genre while it is a difficult obstacle to overcome for the computer. Adapting to the opponents strategy is one of many things that players typically have to do during the course of a game in the real-time strategy genre. This report presents a finite-state machine based solution to the mentioned problem and implements it with the help of the existing Starcraft: Broodwar AI Opprimobot. The extension is experimentally compared to the original implementation of Opprimobot. The comparison shows that both manages to achieve approximately the same win ratio against the built-in AI of Starcraft: Broodwar, but the modified version provides away to model more complex strategies.

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  • 406.
    Svensson, Martin
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Jämförelse mellan tekniker för att lagra data i webbläsare: Kan webbapplikationer anpassas för att användas offline? 2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport undersöker olika tekniker för att spara data lokalt i webbläsare, föratt möjliggöra att webbapplikationer kan användas i webbläsare närinternetanslutning saknas, och för att minska mängden data som behöver överförasmellan webbserver och webbläsare.

    Undersökningen genomförs genom att en befintlig webbapplikation först undersöksför att avgöra vilka datamängder som behöver sparas i webbläsare.Sedan jämförs olika teknikers egenskaper och tidsåtgång för att spara data av olikastorlekar.

    Resultaten från undersökningarna visar att stödet i webbläsare för FileSystem APIoch IndexedDB inte är tillräckligt för att teknikerna ska användas i publikawebbapplikationer, varför HTML5 Application Cache i kombination med WebStorage är det bästa alternativet att använda för att möjliggöra attwebbapplikationer kan användas utan internetanslutning.

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  • 407.
    Svensson, Rickard
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Cued Click-Point Memorability2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Safety of passwords has been in question for over 40 years, long before the Internet. While improvements have been made to ensure security nothing has changed with passwords since the emergence of the Internet. Passwords need to be long and complex to be secure and users should not reuse their passwords. In a world where there are thousands of services on the internet requiring authentication to keep passwords safe users will have to remember a lot of passwords. Studies show however that users are prone to both create bad passwords but to also reuse their passwords on different sites. A lot of different alternatives to passwords has been proposed but none has become dominant. Is there a good alternative to text-based passwords? Can a graphical password be that alternative? The purpose of this thesis is to create a prototype of a CCP-like system and to conduct a memorability and usability test with it. The test results suggest that CCP is easy to use for users new to the concept of graphical passwords. A CCP-password also seems memorable with most participants recalling their passwords after a week with ease. PCCP can be a good substitute for passwords since it is easy to use, easy to remember and potentially more secure than text-based passwords.

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  • 408.
    Sy, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Lindström, Artur
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Färdplanshantering: Extrahera komponenter i färdplanen2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Färdplan är ett dokument som beskriver hur flygningen ska genomföras av piloten och är därför viktigt för att förhindra problem i luftutrymmet. Men nuvarande färdplan system hos Saab AB är känslig för felaktig information och man är istället tvungen att korrigera felet manuellt. För att förhindra det har projektets huvudsakliga mål varit att skapa ett program som kan minska det manuella arbetet.

    Programmet skapades med hjälp av reguljärt uttryck och ett poängsystem baserat på hur viktig informationen är. Reguljärt uttryck används både för att söka och manipulera texter och används i programmet för att kontrollera information. Vi har med hjälp av reguljärt uttryck kunnat skilja mellan felaktig och korrekt information. Utifrån reguljärt uttryck kan man hämta ut den felaktiga informationen för att sedan prioritera om det är av intresse eller inte. På det sättet kan man undvika manuell korrigering om informationen inte behövs.

    Poängen rangordnas mellan 0 till 10 och lagras i en fil som använder formatet extensible markup language (XML). Filen innehåller olika poäng för olika delar av färdplanen. För varje information som har korrekt format erhåller färdplanen ett antal poäng. Poängen kan sedan användas för att bestämma om färdplanen ska godkännas eller inte.

    Rapporten går även igenom olika problem som har uppstått under projektets gång och tester som har genomgåtts. Vidare beskriver det vilka brister det finns i programmet och möjliga lösningar till dem.

  • 409.
    Syromiatnikov, Artem
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Journey Through the Land of Model-View-* Design Patterns2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Every software program that interacts with a user requires a user interface. Model-View-Controller (MVC) is a common design pattern to integrate a user interface with the application domain logic. MVC separates the representation of the application domain (Model) from the display of the application's state (View) and user interaction control (Controller). However, studying the literature reveals that a variety of other related patterns exists, which we denote with Model-View-* (MV*) design patterns. This thesis discusses existing MV* patterns classified in three main families: Model-View-Controller (MVC), Model-View-View Model (MVVM), and Model-View-Presenter (MVP). We take a practitioners' point of view and emphasize the essentials of each family as well as the differences. The study shows that the selection of patterns should take into account the use cases and quality requirements at hand, and chosen technology. We illustrate the selection of a pattern with an example of our practice. The study results aim to bring more clarity in the variety of MV* design patterns and help practitioners to make better grounded decisions when selecting patterns.

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    Master Thesis - A.Syromiatnikov
  • 410.
    Syromiatnikov, Artem
    et al.
    Tele2, ProposalsFactory.
    Weyns, Danny
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A Journey Through the Land of Model-View-* Design Patterns2014In: 2014 IEEE/IFIP Conference on Software Architecture (WICSA), IEEE, 2014, p. 21-30Conference paper (Refereed)
    Abstract [en]

    Every software program that interacts with a user requires a user interface. Model-View-Controller (MVC) is a common design pattern to integrate a user interface with the application domain logic. MVC separates the representation of the application domain (Model) from the display of the application's state (View) and user interaction control (Controller). However, studying the literature reveals that a variety of other related patterns exists, which we denote with Model-View- (MV) design patterns. This paper discusses existing MV patterns classified in three main families: Model-View-Controller (MVC), Model-View-View Model (MVVM), and Model-View-Presenter (MVP). We take a practitioners' point of viewand emphasize the essentials of each family as well as the differences. The study shows that the selection of patterns should take into account the use cases and quality requirements at hand, and chosen technology. We illustrate the selection of a pattern with an example of our practice. The study results aim to bring more clarity in the variety of MV design patterns and help practitioners to make better grounded decisions when selecting patterns.

  • 411.
    Sánchez Bermúdez, Yoel
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    How to select the right machine learning approach?2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the last years, the use of machine learning methods has increased remarkably and therefore the research in this field is becoming more and more important. Despite this fact, a high uncertainity when using machine learning models is still present. We have a wide variety of machine learning approaches such as decision trees or support vector machines and many applications where machine learning has been proved useful like medical diagnosis or computer vision, but all this possibilities make finding the best machine learning approach for a given application a time consuming and not welldefined process since there is not a rule that tells us what method to use for a given type of data.We attempt to build a system that, using machine learning, is capable to learn the best machine learning approach for a given application. For that, we are working on the hypothesis that similar types of data will have also the same machine learning approachas best learner. Classification algorithms will be the main focus of this research and different statistical measures will be used in order to find these similarities among the data.

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  • 412.
    Söderlund, Joakim
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Universal Tagging2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this master degree project was to find out whether or not a highly integrated system for universal tagging of content improves the usability of a desktop environment. A prototype of such a system was implemented and integrated into the GNOME desktop environment. A usability study was then performed which showed that the tagging system did improve the usability of the desktop environment.

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    tagpaca-daemon
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    tagpaca-shell
  • 413.
    Söderlund, Sverker
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Performance of REST applications: Performance of REST applications in four different frameworks2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    More and more companies use a REST architecture to implement applications for an easy to use API. One important quality attribute of an application is the performance. To be able to understand how the application will perform it is important to know how the selected framework perform. By testing the performance of different frameworks it will become easier for software developers to choose the right framework to achieve their requirements and goals. At the time when this paper was written the research in this area was limited. This paper answered the question of which framework between Express, .NET Core, Spring and Flask that had the best performance. To be able to know how frameworks performed the author needed to measure them. One way of measuring performance is with response time from the server. The author used a controlled experiment to collect raw data from which the results was drawn. The author found out that Spring had the best overall performance between the different categories. By analysing the results the author also found out that performance differed a lot between the frameworks in some categories.

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    Report-REST
  • 414.
    Sönnerfors, Peter
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Nilsson, Elliot
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Gustafsson, Michael
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    DDoS-skydd för hemanvändare: En studie kring DDoS2014Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    To make a living as streaming personality on the Internet is something that has grownexponentially in recent times. This also leads to one becoming a clear target for attacks.This work has highlighted the problems that DDoS-attacks create when they are aimedat home users. Various solutions to this problem are reviewed and analyzed. Tests havebeen conducted to illustrate the simplicity of the attack and how it affects home usershardware. The result of the tests has shown that VPN is a competent solution but also hasits disadvantages.

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  • 415.
    Tasim, Taner
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A general framework for scraping newspaper websites2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Data streaming nowadays is one of the most used approaches used by websites and applications to supply the end user with the latest articles and news. As a lot of news websites and companies are founded every day, such data centers must be flexible and it must be easy to introduce a new website to keep track of. The main goal of this project is to investigate two frameworks where implementing a robot for given website should take some acceptable amount of time. It is really challenging task, first of all it aims optimizing of a framework which means to put less efforts on something and have the same result and one another thing is that it will be used by professors and students at the end so quality and robustness play big role here. In order to overcome this challenge two different types of news websites were investigated and through this process the approximately time to implement a single robot was extracted. Having in mind the time spent to implement a single robot, the new frameworks were implemented with the goal to spend less time to implement a new web robot. The results are two general frameworks for two different types of websites, where implementing a robot does not take so much efforts and time. The implementation time of a new robot was reduced from 18 hours to approximately 4 hours.

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  • 416. Telea, Alexandru
    et al.
    Kerren, AndreasLinnaeus University, Faculty of Technology, Department of Computer Science.Marcus, Andrian
    Proceedings of the 1st IEEE Working Conference on Software Visualization (VISSOFT '13)2013Conference proceedings (editor) (Refereed)
  • 417.
    Toll, Daniel
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Measuring Programming Assignment Effort2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Students often voice that the programming assignments are hard and that they spend a lot of time on solving them. Is this true; are we giving them too hard assignments and how much and what do they spend the time on? This is what we want to gain insight to. We constructed a tool that records programming sessions with finer granularity than the existing solutions. The tool has recorded 2643 programming sessions from students. Using that data we found that students spend only 15% of their time writing code, and that on average 40% of their programming effort is spent reading and navigating. We also estimate the time spent outside of the tool to be almost 20%. The increased detail in the recordings can be used to measure the effect of programming source code comments, and we found that the effect of both helpful and redundant comments increases the reading time but did not help to reduce the students writing effort. Finally, we used the tool to examine the effects of an improved programming assignment and found that the total effort was not reduced.

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    Licentiate Thesis (Full Text)
  • 418.
    Toll, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Olsson, Tobias
    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.
    Detailed recordings of student programming sessions2015In: ITiCSE '15: Proceedings of the 2015 ACM Conference on Innovation and Technology in Computer Science Education, ACM Press, 2015, p. 328-328Conference paper (Refereed)
    Abstract [en]

    Observation is important when we teach programming. It can help identify students that struggle, concepts that are not clearly presented during lectures, poor assignments, etc. However, as development tools become more widely available or courses move off-campus and online, we lose our ability to naturally observe students. Online programming environments provide an opportunity to record how students solve assignments and the data recorded allows for in-depth analysis. For example, file activities, mouse movements, text-selections, and text caret movements provide a lot of information on when a programmer collects information and what task is currently worked on. We developed CSQUIZ to allow us to observe students on our online courses through data analysis. Based on our experience with the tool in a course, we find recorded sessions a sufficient replacement for natural observations.

  • 419.
    Toll, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Olsson, Tobias
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Ericsson, Morgan
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Wingkvist, Anna
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Fine-Grained Recording of Student Programming Sessions to Improve Teaching and Time Estimations2015In: IFIP TC3 Working Conference “A New Culture of Learning: Computing and next Generations” / [ed] Andrej Brodnik, Cathy Lewin, 2015, p. 264-274Conference paper (Refereed)
    Abstract [en]

    To have direct observation of students during an online programming course is impossible. This makes it harder for teachers to help struggling students. By using an online programming environment we have the opportunity to record what the students actually do to solve an assignment. We can analyse the recordings and provide teachers with valuable information. We developed and used an online programming toolwith fine-grained event logging to observe how our students solve problems. Our tool provides descriptive statistics and accurate replays of a student’s programming sessions, including mouse movements. We used the tool in a course and collected 1028 detailed recordings. We compare fine-grained logging with existing coarsegrained logging solutions to estimate assignment-solving time. We find that time aggregations are improved by including time for active reading and navigation enabled by the increased granularity. We also divide the time users spent into editing (on average 14.8%), active use (on average 37.8%), passive use (on average 29.0%), and also estimate time used for breaks (on average 18.2%).Finally wesee a correlation between early student submission results and students that hand in later, but also see an example where the results differ significantly.

  • 420.
    Toll, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Olsson, Tobias
    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.
    Fine-Grained Recording of Student Programming Sessions to Improve Teaching and Time Estimations2016In: International journal of engineering education, ISSN 0949-149X, Vol. 32, no 3, p. 1069-1077Article in journal (Refereed)
    Abstract [en]

    It is not possible to directly observe how students work in an online programming course. This makes it harder for teachers to help struggling students. By using an online programming environment, we have the opportunity to record what the students actually do to solve an assignment. These recordings can be analyzed to provide teachers with valuable information. We developed such an online programming tool with fine-grained event logging and used it to observe how our students solve problems. Our tool provides descriptive statistics and accurate replays of a student's programming sessions, including mouse movements. We used the tool in a course and collected 1028 detailed recordings. In this article, we compare fine-grained logging to existing coarse-grained logging solutions to estimate assignment-solving time. We find that time aggregations are improved by including time for active reading and navigation, both enabled by the increased granularity. We also divide the time users spent into editing (on average 14.8%), active use (on average 37.8%), passive use (on average 29.0%), and estimate time used for breaks (on average 18.2%). There is a correlation between assignment solving time for students who pass assignments early and students that pass later but also a case where the times differ significantly. Our tool can help improve computer engineering education by providing insights into how students solve programming assignments and thus enable teachers to target their teaching and/or improve instructions and assignments.

  • 421.
    Toll, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Olsson, Tobias
    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.
    Ericsson, Morgan
    University of Gothenburg.
    The challenge of teaching students the value of programming best practices2014In: Innovation and Technology in Computer Science Education Conference 2014 / [ed] Åsa Cajander and Mats Daniels and Tony Clear and Arnold Pears, ACM Publications, 2014, p. 347-347Conference paper (Refereed)
    Abstract [en]

    We investigate the benefits of our programming assignments in correlation to what the students learn and show in their programming solutions. The assignments are supposed to teach the students to use best practices related to program comprehension, but do the programming assignments clearly show the benefits of best practices? We performed an ex- periment that showed no significant result which suggests that the assignments did not emphasise the value of best practices. As lecturers, we understand that constructing as- signments that match the sought after outcome in students learning is a complex task. The experiment provided valu- able insights that we will use to improve the assignments to better mirror best practices. 

  • 422.
    Toll, Daniel
    et al.
    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.
    How Tool Support and Peer Scoring Improved Our Students' Attitudes Toward Peer Reviews2017In: Proceedings of the 2017 ACM Conference on Innovation and Technology in Computer Science Education, New York, NY, USA: ACM Publications, 2017, p. 311-316Conference paper (Refereed)
    Abstract [en]

    We wanted to introduce peer reviews for the final report in a course on Software Testing. The students had however experienced issues with peer reviews in a previous course which made this a challenge. To get a better understanding of the situation, we distributed a pre-questionnaire to the students. 48 of the 83 students provided their expectations on peer reviews. To deal with some of the perceived issues, we developed a peer review tool where we introduce anonymity, grading of reviews, teacher interventions, as well as let students score and comment on the reviews they receive. In total, 67 reports were submitted by 83 students and 325 reviews were completed. The post-questionnaire was answered by 48 students (not necessarily the same respondents as for the pre-questionnaire as both were collected anonymously). While 27 of the students expected incorrect feedback only 13 students agreed to have got incorrect feedback in the post-questionnaire. The students reported that they found the feedback from their peers more valuable (+15%) than expected, and 88% of the students reported that they learned from doing peer reviews. Overall, we find that the students' attitudes towards peer reviews have improved.

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    fulltext
  • 423.
    Trapp, Martin
    et al.
    Senacor Technologies AG, Germany.
    Hedenborg, Mathias
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Lundberg, Jonas
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Capturing and Manipulating Context-sensitive Program Information2015In: Software Engineering Workshops 2015: Gemeinsamer Tagungsband der Workshops der Tagung Software Engineering 2015, Dresden, 17.-18. März 2015 / [ed] Wolf Zimmermann, Martin-Luther-Universität Halle-Wittenberg, CEUR-WS.org , 2015, Vol. 1337, p. 154-163Conference paper (Refereed)
    Abstract [en]

    Designers of context-sensitive program analyses need to take special care of the memory consumption of the analysis results. In general, they need to sacrifice accuracy to cope with restricted memory resources. We introduce χ-terms as a general data structure to capture and manipulate context-sensitivity analysis results. A χ-term is a compact representation of arbitrary forward program analysis distinguishing the effects of different control-flow paths. While χ-terms can be represented by trees, we propose a memory efficient representation generalizing ordered binary decision diagrams (OBDDs).

  • 424.
    Tullberg, Jesper
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Jonsson, Simon
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Klient-server och Peer-to-Peer applikationer: En prestandajämförelse2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    An increasing number of applications are becoming more or less network based today.

    The traditional architecture for network based applications is client-server, but as usage

    of download services are going up, so is the Peer-to-Peer architecture. This report is a

    comparison between the Peer-to-Peer and client-server model, and can serve as a basis

    when a decision between them needs to be taken. In the report, the performance

    between the different architectures is compared in different contexts. Our basis is a

    general implementation of both architectures in a test that is derived from a previous

    report. On top of this, the performance of the different architectures are measured,

    implemented in a gaming-context. This way, we are trying to give the reader as an

    objective and informative picture of the different architectures as possible. The tests that

    have been done shows a different situation than that of the general view, which is that

    client-server is the preferred model.

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  • 425.
    Tägt, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Hansson, Jonny
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Synkroniserad insamling av videoström från flera analoga källor2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Arbetet bygger på att modernisera Saab AB:s kamerasystem med videoservrar. Systemet ska kunna samla in ett antal analoga videoströmmar och omvandla de till digitala. Kamerorna är utav bildformaten NTSC och PAL vilket innebär att de har olika bilduppdateringshastigheter. Det medför att en fördröjning kommer ske i PAL-strömmen. En programvara ska utvecklas för att ta in dessa strömmar, spara och synkronisera de.

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  • 426.
    Valipour, Saeideh
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Language IndependentDetector for Auto GeneratedTweets2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cross-disciplinary Nordic Tweet Stream (NTS) is a project aiming at creating a multilingual text corpus consisting of tweets published in the five Nordic countries. The NTS linguists are explicitly interested in tweets having a text formulated by a human where each tweet is a personal statement, not in Tweets generated by bots and other programs or apps since they might skew the results. NTS consists of multiple parts and the part we are responsible for is a language-independent approach, using supervised machine learning, to classify every single tweet as auto-generated (AGT) or human-generated (HGT). The objective of this study is to increase data accuracy in sociolinguistic studies that utilize Twitter by reducing skewed sampling and inaccuracies in linguistic data. We define an AGT as a tweet where all or parts of the natural language content are generated automatically by a bot or other type of program. In other words, while AGT/HGT refers to an individual message, the term bot refers to nonpersonal and automated accounts that post content to online social networks. Our approach classifies a tweet using only metadata that comes with every tweet, and we utilize those metadata parameters that are both language and country independent. The empirical part shows that our results show poor success rates when it comes to unseen data. Using a bilingual training set of two languages tweets, we correctly classified only about 60-70% of all tweets in a test set using a third new language, which is still better than nothing, but probably not good enough to be used (as is) in a real-world scenario to identify AGTs in a given set of multilingual tweets.

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  • 427.
    Valldeperas, Roger
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Production Cell Simulation Visualization in 3D2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis explains the development process of a production cell simulation in 3D implemented using Unity3D. The developed simulation communicates with existing control software and aims to test this control software in a 3D environment with physics simulation. The final result includes 3D models and also works as a visualization since it allows us to present the control system, and this visualization can be viewed using most web browsers. The thesis also includes a brief study and comparison between currently popular game engines to choose an appropriate option for this project.This is a project in collaboration with a local company (ARiSA) and has a high practical relevance.

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    ProdCellSim3D
  • 428.
    Viebke, Andre
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Pllana, Sabri
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    The Potential of the Intel (R) Xeon Phi (TM) for Supervised Deep Learning2015In: Proceedings: 2015 IEEE 17th International Conference on High Performance Computing and Communications, 2015 IEEE 7th International Symposium on Cyberspace Safety and Security & 2015 IEEE 12th International Conference on Embedded Software and Systems, IEEE Press, 2015, p. 758-765Conference paper (Refereed)
    Abstract [en]

    Supervised learning of Convolutional Neural Networks (CNNs), also known as supervised Deep Learning, is a computationally demanding process. To find the most suitable parameters of a network for a given application, numerous training sessions are required. Therefore, reducing the training time per session is essential to fully utilize CNNs in practice. While numerous research groups have addressed the training of CNNs using GPUs, so far not much attention has been paid to the Intel Xeon Phi coprocessor. In this paper we investigate empirically and theoretically the potential of the Intel Xeon Phi for supervised learning of CNNs. We design and implement a parallelization scheme named CHAOS that exploits both the thread-and SIMD-parallelism of the coprocessor. Our approach is evaluated on the Intel Xeon Phi 7120P using the MNIST dataset of handwritten digits for various thread counts and CNN architectures. Results show a 103.5x speed up when training our large network for 15 epochs using 244 threads, compared to one thread on the coprocessor. Moreover, we develop a performance model and use it to assess our implementation and answer what-if questions.

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  • 429.
    Viebke, André
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Accelerated Deep Learning using Intel Xeon Phi2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Deep learning, a sub-topic of machine learning inspired by biology, have achieved wide attention in the industry and research community recently. State-of-the-art applications in the area of computer vision and speech recognition (among others) are built using deep learning algorithms. In contrast to traditional algorithms, where the developer fully instructs the application what to do, deep learning algorithms instead learn from experience when performing a task. However, for the algorithm to learn require training, which is a high computational challenge. High Performance Computing can help ease the burden through parallelization, thereby reducing the training time; this is essential to fully utilize the algorithms in practice. Numerous work targeting GPUs have investigated ways to speed up the training, less attention have been paid to the Intel Xeon Phi coprocessor. In this thesis we present a parallelized implementation of a Convolutional Neural Network (CNN), a deep learning architecture, and our proposed parallelization scheme, CHAOS. Additionally a theoretical analysis and a performance model discuss the algorithm in detail and allow for predictions if even more threads are available in the future. The algorithm is evaluated on an Intel Xeon Phi 7120p, Xeon E5-2695v2 2.4 GHz and Core i5 661 3.33 GHz using various architectures and thread counts on the MNIST dataset. Findings show a 103.5x, 99.9x, 100.4x speed up for the large, medium, and small architecture respectively for 244 threads compared to 1 thread on the coprocessor. Moreover, a 10.9x - 14.1x (large to small) speed up compared to the sequential version running on Xeon E5. We managed to decrease training time from 7 days on the Core i5 and 31 hours on the Xeon E5, to 3 hours on the Intel Xeon Phi when training our large network for 15 epochs

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  • 430.
    Viebke, André
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Tan, Wenwei
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Calendar 2.0: The mitigation of calendar friction2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Calendar applications have been a primary tool for time management, although they have been slowly developed and improved. The slow development of calendar applications has created friction of usage.

    In this report, we propose a friction mitigation strategy for calendar applications. A set of characteristics are identified: active, intelligent, personal, extensible, information-centred and dynamic view, which describes the notion of friction.

    The goal is to develop a framework, supporting the prototype and providing reusable components for future development. The prototype is evaluated by participants and the result is used to conclude that friction can be mitigated to some extent.

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    Calendar2.0
  • 431.
    Vitt, Artur
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Machine Learning in DigitalTelerehabilitation: Telerehabilitation system based on kinect2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The healthcare as a service is always under pressure and is in great demand. Despiteliving in a developed world with access to cars, trains, busses and other transportationmeans, sometimes accessing healthcare can be troublesome and costly. Thecontinuous technological progress provides new means to provide different kind ofservices, healthcare included. One way of putting technology into good use in fieldof healthcare is remote rehabilitation.Remote rehabilitation is a matter of delivering physiotherapy on a distance. Theuse of remote rehabilitation potentially reduces waiting time for treatment and gives apossibility for people with long traveling distance, to be treated at their locations. Thethesis addresses a solution to physiotherapy on distance that utilizes Kinect and machinelearning technologies to provide physiotherapy offline. Thesis presents KinectDigital Rehabilitation Assistant (KiDiRA), which provides simple functions to sufficethe needs of a physiotherapist to plan therapeutical treatment and the ability of apatient to get access physiotherapy offline in real-time at home.More precisely KiDiRA is the system that combines Kinect motion capture device,an interactive graphical interface and a platform to assist with the design ofphysiotherapeutical exercises and an aid for the patient to execute therapeutic plan onhis/her own. The system displays the exercise directives and monitors performanceof patient. KiDiRA aims to incorporate science of machine-learning in process ofperformance evaluation during exercises.

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  • 432.
    Vogel, Bahtijar
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology. Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    An Open Architecture Approach for the Design and Development of Web and Mobile Software2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The rapid evolution of web and mobile technologies as well as open standards are important ingredients for developing open software applications. HTML5, affordable electronics, and connectivity costs are some of the trends that drive the web towards an open platform and lead to an increased use of distributed applications. Proprietary software technologies have been extensively deployed throughout multiple platforms, including desktop, web, and mobile systems. Such systems are closed in many cases. Thus, it is rather difficult to expand existing and create additional features for them. Web and mobile software development is fragmented with the existence of multiple browsers and mobile operating systems, that comply differently with web standards. The evolution of web and mobile technologies, coupled with the changes in the deployment environments in which they operate, has resulted in complex requirements that are challenging to satisfy. Additionally, the largest part of the development lifecycle is related to the need to constantly change/modify these software systems within a short-time period. The fact that these systems evolve over time makes it difficult to meet the changing requirements.

    In this thesis, we offer a novel open architecture approach in the area of web and mobile software design and development when dealing with heterogeneous device environments, together with constantly evolving and dynamic requirements. This approach is grounded on our experiences gained during the last four years of project work regarding the development of a web and mobile software system to support mobile inquiry learning. This case served as a testbed for experimentation with heterogeneous device environments. After five development iterations, our software solution is considered robust, flexible, and expandable as a platform. Among others, this was validated with being tested with more than 500 users. The open architecture approach is also grounded on a literature survey of state of the art projects and definitions related to this concept. The outcomes of this thesis show that an open architecture approach is characterized by flexibility, customizability, and extensibility, which are instantiated into a set of properties. The importance of stressing these three characteristics and their properties in the open architecture approach is based on the identified needs of using open source components, using open data standards, and reducing development time. The research efforts in this thesis resulted in a refined definition of an open architecture approach as well as the initial and refined models that are contextualized within the field of web and mobile software. 

    For validation of the research, the Goal Question Metric (GQM) approach is adapted and extended with a layer of Tasks/Activities. The data is collected from the project work mentioned above and three follow-up cases. The results show that the benefits of an open architecture approach can be reflected in terms of: achievement of the software system’s long-term goals; reduced development time; and increased satisfaction of the users. These benefits refer to the possibility to easily adapt emerging technologies and address dynamic changes and requirements. The contributions of this thesis are threefold: (1) for researchers, our open architecture approach could be used to analyze a system from a top down perspective; (2) for developers, it could be used as an approach to identify and address the needs for building an open evolvable system from a bottom up perspective; (3) for domain experts in the technology enhanced learning field, it could be used as a sustainability approach through which to integrate new tools and address complex requirements when designing new educational activities.

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  • 433.
    Vogel, Bahtijar
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Kilamo, Terhi
    Tampere University of Technology, Finland.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Teaching Distributed Agile Development to Software Professionals: A Flexible Approach2015In: Proceedings of the 2015 European Conference on Software Architecture Workshops (ECSA 2015) / [ed] Matthias Galster, ACM Press, 2015, p. 1-8, article id 31Conference paper (Refereed)
    Abstract [en]

    Software development today is based on a set of Agile approaches in the mindset of Lean. These emphasize the need for team collaboration and communication, rapid feedback and continuous learning. This creates the need for software intensive companies to educate their developers to these ways of working in a manner that allows fast adoption of the acquired skills also in professional capacity. As Agile emphasizes learning, teaching agile development can rely on modern, learner-centric approaches such as situated learning and the idea of a flipped classroom. In this paper we present and reflect upon a case study of two courses of teaching distributed agile development for software professionals based on modern learning theories engaging the learners directly in practice.

  • 434.
    Vogel, Bahtijar
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Mikkonen, Tommi
    Tampere University of Technology, Finland.
    Milrad, Marcelo
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    From Architectural Requirements towards an Open Architecture for Web and Mobile Societal Applications2014In: Proceedings of the 1st International Workshop on Inclusive Web Programming - Programming on the Web with Open Data for Societal Applications, ACM Publications, 2014, p. 20-23Conference paper (Refereed)
    Abstract [en]

    This paper reflects on our experiences during the last four years regarding the development of a web & mobile application for sustainable environment. After five development cycles our software application has become robust, flexible, and expandable platform. Inspired from this and the needs identified during this process we report our research towards identifying novel architectural approaches that nourish open data and emerging web standards for developing open societal applications. The efforts resulted in an open architecture approach that relies on a set of key characteristics - flexibility, evolvability, customizability, and extensibility. Stressing these characteristics refers to the identified needs of using open standards and reducing development time. The results show that an open architecture approach provides the key ingredients in terms of system integration and data interoperability as well as the ability of the software to grow in terms of new services, devices, and subsystems attached to it, primarily due to the use of open source components and open data standards.

  • 435.
    Vogel, Bahtijar
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Linnaeus University, Faculty of Technology, Department of Media Technology.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Mikkonen, Tommi
    Tampere University of Technology.
    Milrad, Marcelo
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    Towards an Open Architecture Model for Web and Mobile Software: Characteristics and Validity Properties2014In: 2014 IEEE 38th Annual Computer Software and Applications Conference (COMPSAC) / [ed] Chang, CK; Gao, Y; Hurson, A; Matskin, M; McMillin, B; Okabe, Y; Seceleanu, C; Yoshida, K, IEEE Press, 2014, p. 476-485Conference paper (Refereed)
    Abstract [en]

    Proprietary software solutions are extensively deployed through multiple platforms including desktop, web and mobile devices. Such systems are in many cases closed, thus making it difficult for software developers to expand and create additional features to these systems. Recent research in the field of web and mobile technologies indicates that open systems are more successful than those based on proprietary technologies. In this paper, we investigate and analyze existing research related to the notion of open architectures. We conducted a literature survey of the state of the art projects and definitions related to this concept. Our efforts have resulted in a refined definition of the term followed by a conceptual model of an open architecture contextualized within the field of web and mobile software. The model primarily relies on four key characteristics, namely flexibility, evolvability, customizability and extensibility. Furthermore, we present a validation plan based on the GQM approach that further instantiates these characteristics into a set of properties that can serve as metrics.

  • 436.
    Vogel, Bahtijar
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Milrad, Marcelo
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Johansson, Emil
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Müller, Maximilian
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Mobile Inquiry Learning in Sweden: Development Insights on Interoperability, Extensibility and Sustainability of the LETS GO Software System2014In: Educational Technology & Society, ISSN 1176-3647, E-ISSN 1436-4522, Vol. 17, no 2, p. 43-57Article in journal (Refereed)
    Abstract [en]

    This paper presents the overall lifecycle and evolution of a software system we have developed in relation to the Learning Ecology through Science with Global Outcomes (LETS GO) research project. One of the aims of the project is to support “open inquiry learning” using mobile science collaboratories that provide open software tools and resources, and participation frameworks for learner project collaboration, mobile data and media capture, publishing, analysis, and reflection. The primary focus of this paper is to report on our technical development, insights and knowledge gained during the past four years. Technical implementations and the prototypes developed in this project have been tested across several educational trials conduced in Sweden and abroad with more than 400 learners. Insights and knowledge gained from these activities verify that learners´ requirements were adequately addressed while satisfying their needs. The outcomes and results of our efforts provided us with a better understanding with regard to which software engineering processes and approaches can be used to address and support the complex requirements that emerge in novel mobile learning scenarios. Thus, the results discussed in this paper provide deeper insights into the importance of properly addressing issues related to interoperability and extensibility in order to develop software solutions to support mobile learning that are sustainable and endurable over time.

  • 437.
    von Landesberger, Tatiana
    et al.
    Technical University of Darmstadt, Germany.
    Brodkorb, Felix
    Technical University of Darmstadt, Germany.
    Roskosch, Philipp
    Technical University of Darmstadt, Germany.
    Andrienko, Natalia
    Fraunhofer IAIS, Germany ; City University, UK.
    Andrienko, Gennady
    Fraunhofer IAIS, Germany ; City University, UK.
    Kerren, Andreas
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    MobilityGraphs: Visual Analysis of Mass Mobility Dynamics via Spatio-Temporal Graphs and Clustering2016In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 22, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Learning more about people mobility is an important task for official decision makers and urban planners. Mobility data sets characterize the variation of the presence of people in different places over time as well as movements (or flows) of people between the places. The analysis of mobility data is challenging due to the need to analyze and compare spatial situations (i.e., presence and flows of people in certain time intervals) and to gain an understanding of the spatio-temporal changes (variations of situations over time). Traditional flow visualizations usually fail due to massive clutter. Modern approaches offer limited support for investigating the complex variation of the movements over longer time periods.

    We propose a visual analytics methodology that solves these issues by combined spatial and temporal simplifications. We have developed a graph-based method, called MobilityGraphs, which reveals movement patterns that were occluded in flow maps. Our method enables the visual representation of the spatio-temporal variation of movements for long time series of spatial situations originally containing a large number of intersecting flows. The interactive system supports data exploration from various perspectives and at various levels of detail by interactive setting of clustering parameters. The feasibility our approach was tested on aggregated mobility data derived from a set of geolocated Twitter posts within the Greater London city area and mobile phone call data records in Abidjan, Ivory Coast. We could show that MobilityGraphs support the identification of regular daily and weekly movement patterns of resident population.

  • 438.
    Wahlstrand, Albin
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    A/B-testning av Mikrotransaktioner2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Micro transactions are a big part of today's internet commerce. They are used diligently in both web applications and in computer games. This report will explore how a company or private developer, through A/B-testing, can test which transaction type is the best for their specific application. The problem is that there's a large amount of transaction types to choose from and there is not any good way to find out which one is the best for your application. To do this there needs to be some way to test the different types to receive the optimal one. By measuring a transaction type's efficiency, we can get a point of measure which can be compared to other transaction types. The results show that A/B-testing is applicable on micro transactions by following the architectures provided by this report.

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    A/B-testingMicrotransactions
  • 439.
    Weiss, Jan
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Speed-invariant video comparison for robust human action recognition2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As cameras and especially 3D cameras got affordable within recent years they can be used by a wider range of people. Human action recognition based on 3D coordinates recorded with such devices including a depth camera made it possible to compute video data easier. Many already published papers ignore the difference of speed within the execution of the same action. This paper suggests and evaluates multiple algorithms handling that problem based on Dynamic Time Warping and compares them with regard to runtime and accuracy. An additional algorithm from Softwerk AB is analyzed, adjusted and compared. An approach for a fast and robust algorithm able to compute a massive amount of stored sequences is proposed within this paper. The new algorithm depends on further research as not all prerequisites are met yet.

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  • 440.
    Weißbach, Mandy
    et al.
    University of Halle, Germany.
    Zimmermann, Wolf
    University of Halle, Germany.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Context-aware Data-flow in the Cloud2013In: Cloud Computing 2013 : The Fourth International Conference on Cloud Computing, GRIDs, and Virtualization, 2013, p. 81-86Conference paper (Refereed)
    Abstract [en]

    In the last few months, clients of services running in a cloud are getting more and more aware of storing and processing their data in the cloud. In this paper, we present a context-aware data-flow analysis approach to allow clients to negotiate services that store or process (directly or indirectly) their data in undesired locations. The approach is context- aware to satisfy the stateless character of services in a multi- tenant cloud. We show that the use of a dynamic context-aware data-flow analysis ensures that the clients’ data does not reach undesired locations in the cloud.

  • 441.
    Weyns, Danny
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Variability: From Software Product Lines to Self-Adaptive Systems2014Conference paper (Refereed)
    Abstract [en]

    Variability is commonly understood as the ability of a software system or software artifact (e.g., component) to be changed so that it fits a specific context. Variability allows adapting the structure of a software system, its behavior, or underlying processes. These adaptations are enabled through variation points and variants as options that can be selected at these variation points. So far, variability has mainly been studied in the classic software product line domain. However, variability is not limited to product lines or families, but imposes challenges on software development in general. Many other types of today's software systems are built with variability in mind; one prominent type is self-adaptive systems that are capable to adapt autonomously at runtime, another is dynamic software product lines that combines principles from product lines with self-adaptation. In this talk, I summarize the results of an extensive survey we recently performed on the use of variability in software systems in general [1]. Based on our findings, I present dimensions of variability in software engineering. This empirically grounded set of core dimensions provides a step towards an integrated perspective of variability in software systems, spanning across loosely coupled research areas in the software engineering community. To conclude, I outline some interesting opportunities for future research.

  • 442.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Ahmad, Tanvir
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Claims and Evidence for Architecture-Based Self-Adaptation: A Systematic Literature Review2013In: Software Architecture: 7th European Conference, ECSA 2013, Montpellier, France, July 1-5, 2013. Proceedings, Springer, 2013, p. 249-265Conference paper (Refereed)
    Abstract [en]

    Engineering the upcoming generation of software systems and guaranteeing the required qualities is complex due to the inherent uncertainties at design time, such as new user needs and changing availability of resources. Architecture-based self-adaptation is a promising approach to tackle these challenges. In this approach, a system maintains a model of itself and adapts itself to realize particular quality objectives using a feedback loop. Despite a vast body of work, no systematic study has been performed on the claims associated with architecture-based self-adaptation and the evidence that exists for these claims. As such insight is important for researchers and engineers, we performed a systematic literature review covering 20 leading software engineering conferences and journals in the field, resulting in 121 studies used for data collection. The review shows that self-adaptation is primarily used to improve performance, reliability, and flexibility. The tradeoffs implied by self-adaptation have not received much attention, and evidence is mainly obtained from simple examples. From the study, we derive a number of recommendations for future research in architecturebased self-adaptive systems.

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  • 443.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Andersson, Jesper
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    On the Challenges of Self-adaptation in Systems of Systems2013In: Proceedings of the First International Workshop on Software Engineering for Systems-of-Systems, ACM Press, 2013, p. 47-51Conference paper (Refereed)
    Abstract [en]

    A system of systems (SoS) integrates independently useful systems into a larger system. Examples are integrated surveillance systems and networked smart homes. A SoS offers functions to users that cannot be provided by its individual parts, but emerge as a combination of these. However, providing these functions with a required level of quality is difficult due to inherent uncertainties, such as systems that attach and detach at will and faults that are difficult to predict. Self-adaptation is a well-studied approach that enables a system to reason about itself and adapt to achieve particular quality objectives in the face of uncertainties and change. However, the inherently decentralized nature of SoS raises fundamental challenges to self-adaptation. This paper presents three architectural styles to realize self-adaptation in SoS, discusses key challenges for each style, and outlines starting points that could help to tackle these challenges.

  • 444.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Calinescu, Radu
    University of York, UK.
    Tele Assistance: A Self-Adaptive Service-Based System Examplar2015In: Proceedings: 2015 IEEE/ACM 10th International Symposium on Software Engineering for Adaptive and Self-Managing Systems (SEAMS), IEEE conference proceedings, 2015, p. 88-92Conference paper (Refereed)
    Abstract [en]

    Research on adaptive and self-managing systems is hindered by a lack of prototypical applications that researchers could use to evaluate and compare new methods, techniques and tools. To address this limitation, we introduce a reference implementation of a Tele Assistance System (TAS) for research onself-adaptation in the domain of service-based systems. Our TAS exemplar of service-based systemscomes with pre-defined scenarios for comparing the effectiveness of different self-adaptation solutions. Other researchers can easily exploit the underlying service platform, reusable components and development method we devised for TAS to speed up the engineering of additional research exemplars for service-based systems.

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  • 445.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Caporuscio, Mauro
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Andersson, Jesper
    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.
    Pllana, Sabri
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Löwe, Welf
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Software Technology for Self-Adaptive Systems2017In: Swedsoft's Software Technology Exchange Workshop, 18-19 oktober, 2017, Stockholm, 2017Conference paper (Refereed)
  • 446.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science. Katholieke Univ Leuven, Belgium.
    Caporuscio, Mauro
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Axelsson, Clara
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    Petersson, Göran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry.
    BoConnect – Reliable Assistive Technologies to Empower Elderly People to Live Independently Longer2017Report (Other academic)
    Abstract [en]

    BoConnect was a multi-disciplinary collaborative research project between Linnaeus University and Växjö and Kalmarmunicipalities in Sweden. The project had a budget of 3 MSEK; it stated Jan. 2015 and ended Dec. 2016.The project studied reliable assistive technologies to support elderly people. In contrast to existing work in this areathatis often limited to small-scale technology-driven pilots that are poorly embedded in the social living context, the BoConnect project took a holistic perspective on assistive technologies and put user needs and reliability of the solutions in focus, both from a technological and organizational perspective. This report summarizes the main results of the project.

    Download full text (pdf)
    fulltext
  • 447.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Caporuscio, Mauro
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Vogel, Bahtijar
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Kurti, Arianit
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Design for Sustainability = Runtime Adaptation U Evolution2015In: Proceedings of the 2015 European Conference on Software Architecture Workshops, ACM Press, 2015, p. 1-7, article id 62Conference paper (Refereed)
    Abstract [en]

    Continuous change changes everything; it introduces various uncertainties, which may harm the sustainability of software systems. We argue that integrating runtime adaptation and evolution is crucial for the sustainability of software systems. Realising this integration calls for a radical change in the way software is developed and operated. Our position is that we need to Design for Sustainability. To that end, we present: (i) the AdEpS model (Adaptation and Evolution processes for Sustainability) to handle and mitigate uncertainties by means of integrating runtime adaptation and evolution, and (ii) a set of engineering principles to design software systems that facilitate the application of the AdEpS model to build sustainable software.

  • 448.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science. Katholieke Univ Leuven, Belgium.
    Iftikhar, Muhammad Usman
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Model-based Simulation at Runtime for Self-adaptive Systems2016In: 2016 IEEE International Conference on Autonomic Computing (ICAC), IEEE, 2016, p. 364-373Conference paper (Refereed)
    Abstract [en]

    Modern software systems are subject to uncertainties, such as dynamics in the availability of resources or changes of system goals. Self-adaptation enables a system to reason about runtime models to adapt itself and realises its goals under uncertainties. Our focus is on providing guarantees for adaption goals. A prominent approach to provide such guarantees is automated verification of a stochastic model that encodes up-to-date knowledge of the system and relevant qualities. The verification results allow selecting an adaption option that satisfies the goals. There are two issues with this state of the art approach: i) changing goals at runtime (a challenging type of uncertainty) is difficult, and ii) exhaustive verification suffers from the state space explosion problem. In this paper, we propose a novel modular approach for decision making in self-adaptive systems that combines distinct models for each relevant quality with runtime simulation of the models. Distinct models support on the fly changes of goals. Simulation enables efficient decision making to select an adaptation option that satisfies the system goals. The tradeoff is that simulation results can only provide guarantees with a certain level of accuracy. We demonstrate the benefits and tradeoffs of the approach for a service-based telecare system.

  • 449.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Iftikhar, Muhammad Usman
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Söderlund, Joakim
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science.
    Do External Feedback Loops Improve the Design of Self-Adaptive Systems?: A Controlled Experiment2013In: Proceedings of the 8th International Symposium on Software Engineering for Adaptive and Self-Managing Systems, New York: IEEE Press, 2013, p. 3-12Conference paper (Refereed)
    Abstract [en]

    Providing high-quality software in the face of uncertainties, such as dealing with new user needs, changing availability of resources, and faults that are difficult to predict, raises fundamental challenges to software engineers. These challenges have motivated the need for self-adaptive systems. One of the primary claimed benefits of self-adaptation is that a design with external feedback loops provide a more effective engineering solution for self-adaptation compared to a design with internal mechanisms. While many efforts indicate the validity of this claim, to the best of our knowledge, no controlled experiments have been performed that provide scientifically founded evidence for it. Such experiments are crucial for researchers and engineers to underpin their claims and improve research. In this paper, we report the results of a controlled experiment performed with 24 final-year students of a Master in Software Engineering program in which designs based on external feedback loops are compared with designs based on internal mechanisms. The results show that applying external feedback loops can reduce control flow complexity and fault density, and improve productivity. We found no evidence for a reduction of activity complexity.

    Download full text (pdf)
    2013SEAMSb.pdf
  • 450.
    Weyns, Danny
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Michel, FabienLIRMM, France.
    Agent Environments for Multi-Agent Systems IV: 4th International Workshop, E4MAS 2014 - 10 Years Later, Paris, France, May 6, 2014, Revised Selected and Invited Papers2015Conference proceedings (editor) (Refereed)
    Abstract [en]

    This book constitutes the thoroughly refereed post-workshop proceedings of the 4th International Workshop on Environments for Multiagent Systems, E4MAS 2014 - 10 years later, held in Paris, France, in May 2014 as an associated event of AAMAS 2014, the 13th International Conference on Autonomous Agents and Multiagent Systems.

    The 6 revised full papers presented together with 1 roadmap paper and 7 invited papers were carefully reviewed and selected from 14 initial submissions. The papers are organized in topical sections on connecting agents, environments, and humans; environments for complex and stigmergic systems; virtual and simulated environments; and open agent environments and interoperability.

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