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  • 101.
    Ceballos, Germán
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Understanding Task Parallelism: Providing insight into scheduling, memory, and performance for CPUs and Graphics2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Maximizing the performance of computer systems while making them more energy efficient is vital for future developments in engineering, medicine, entertainment, etc. However, the increasing complexity of software, hardware, and their interactions makes this task difficult. Software developers have to deal with complex memory architectures such as multilevel caches on modern CPUs and keeping thousands of cores busy in GPUs, which makes the programming process harder.

    Task-based programming provides high-level abstractions to simplify the development process. In this model, independent tasks (functions) are submitted to a runtime system, which orchestrates their execution across hardware resources. This approach has become popular and successful because the runtime can distribute the workload across hardware resources automatically, and has the potential to optimize the execution to minimize data movement (e.g., being aware of the cache hierarchy).

    However, to build better runtime systems, we now need to understand bottlenecks in the performance of current and future multicore architectures. Unfortunately, since most current work was designed for sequential or thread-based workloads, there is an overall lack of tools and methods to gain insight about the execution of these applications, allowing both the runtime and the programmers to detect potential optimizations.

    In this thesis, we address this lack of tools by providing fast, accurate and mathematically-sound models to understand the execution of task-based applications. In particular, we center these models around three key aspects of the execution: memory behavior (data locality), scheduling, and performance. Our contributions provide insight into the interplay between the schedule's behavior, data reuse through the cache hierarchy, and the resulting performance. These contributions lay the groundwork for improving runtime systems. We first apply these methods to analyze a diverse set of CPU applications, and then leverage them to one of the most common workloads in current systems: graphics rendering on GPUs.

    List of papers
    1. Shared Resource Sensitivity in Task-Based Runtime Systems
    Open this publication in new window or tab >>Shared Resource Sensitivity in Task-Based Runtime Systems
    2013 (English)In: Proc. 6th Swedish Workshop on Multi-Core Computing, Halmstad University Press, 2013Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Halmstad University Press, 2013
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-212780 (URN)
    Conference
    MCC13, November 25–26, Halmstad, Sweden
    Projects
    Resource Sharing ModelingUPMARC
    Funder
    Swedish Research Council
    Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2018-11-16Bibliographically approved
    2. Formalizing data locality in task parallel applications
    Open this publication in new window or tab >>Formalizing data locality in task parallel applications
    2016 (English)In: Algorithms and Architectures for Parallel Processing, Springer, 2016, p. 43-61Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Springer, 2016
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 10049
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-310341 (URN)10.1007/978-3-319-49956-7_4 (DOI)000389797000004 ()978-3-319-49955-0 (ISBN)
    Conference
    ICA3PP 2016, December 14–16, Granada, Spain
    Projects
    UPMARCResource Sharing Modeling
    Funder
    Swedish Foundation for Strategic Research , FFL12-0051
    Available from: 2016-11-19 Created: 2016-12-14 Last updated: 2018-11-16Bibliographically approved
    3. Analyzing performance variation of task schedulers with TaskInsight
    Open this publication in new window or tab >>Analyzing performance variation of task schedulers with TaskInsight
    2018 (English)In: Parallel Computing, ISSN 0167-8191, E-ISSN 1872-7336, Vol. 75, p. 11-27Article in journal (Refereed) Published
    National Category
    Computer Engineering
    Identifiers
    urn:nbn:se:uu:diva-340202 (URN)10.1016/j.parco.2018.02.003 (DOI)000433655700002 ()
    Projects
    UPMARCResource Sharing Modeling
    Funder
    Swedish Research Council, FFL12-0051Swedish Foundation for Strategic Research , FFL12-0051
    Available from: 2018-02-22 Created: 2018-01-26 Last updated: 2018-11-16Bibliographically approved
    4. Behind the Scenes: Memory Analysis of Graphical Workloads on Tile-based GPUs
    Open this publication in new window or tab >>Behind the Scenes: Memory Analysis of Graphical Workloads on Tile-based GPUs
    2018 (English)In: Proc. International Symposium on Performance Analysis of Systems and Software: ISPASS 2018, IEEE Computer Society, 2018, p. 1-11Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    IEEE Computer Society, 2018
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-361214 (URN)10.1109/ISPASS.2018.00009 (DOI)978-1-5386-5010-3 (ISBN)
    Conference
    ISPASS 2018, April 2–4, Belfast, UK
    Projects
    UPMARC
    Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-11-16Bibliographically approved
    5. Tail-PASS: Resource-based Cache Management for Tiled Graphics Rendering Hardware
    Open this publication in new window or tab >>Tail-PASS: Resource-based Cache Management for Tiled Graphics Rendering Hardware
    2018 (English)In: Proc. 16th International Conference on Parallel and Distributed Processing with Applications, IEEE, 2018, p. 55-63Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern graphics rendering is a very expensive process and can account for 60% of the battery consumption on current games. Much of the cost comes from the high memory bandwidth of rendering complex graphics. To render a frame, multiple smaller rendering passes called scenes are executed, with each one tiled for parallel execution. The data for each scene comes from hundreds of software resources (textures). We observe that each frame can consume up to 1000s of MB of data, but that over 75% of the graphics memory accesses are to the top-10 resources, and that bypassing the remaining infrequently accessed (tail) resources reduces cache pollution. Bypassing the tail can save up to 35% of the main memory traffic over resource-oblivious replacement policies and cache management techniques. In this paper, we propose Tail-PASS, a cache management technique that detects the most accessed resources at runtime, learns if it is worth bypassing the least accessed ones, and then dynamically enables/disables bypassing to reduce cache pollution on a per-scene basis. Overall, we see an average reduction in bandwidth-per-frame of 22% (up to 46%) by bypassing all but the top-10 resources and an 11% (up to 44%) reduction if only the top-2 resources are cached.

    Place, publisher, year, edition, pages
    IEEE, 2018
    National Category
    Computer Systems Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-363920 (URN)10.1109/BDCloud.2018.00022 (DOI)000467843200008 ()978-1-7281-1141-4 (ISBN)
    Conference
    ISPA 2018, December 11–13, Melbourne, Australia
    Funder
    EU, European Research Council, 715283
    Available from: 2018-10-21 Created: 2018-10-21 Last updated: 2019-06-17Bibliographically approved
  • 102.
    Chen, Gang
    et al.
    Northeastern Univ, Smart Syst Lab, Sch Comp Sci & Engn, Shenyang 110819, Liaoning, Peoples R China;Hong Kong Polytech Univ, Dept Comp, Hong Kong, Hong Kong, Peoples R China.
    Guan, Nan
    Hong Kong Polytech Univ, Dept Comp, Hong Kong, Hong Kong, Peoples R China.
    Hu, Biao
    Beijing Univ Chem Technol, Coll Informat Sci & Technol, Beijing 100029, Peoples R China.
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. School of Computer Science and Engineering, Northeastern University, Shenyang, China.
    EDF-VD Scheduling of Flexible Mixed-Criticality System With Multiple-Shot Transitions2018In: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, ISSN 0278-0070, E-ISSN 1937-4151, Vol. 37, no 11, p. 2393-2403Article in journal (Refereed)
    Abstract [en]

    The existing mixed-criticality (MC) real-time task models assume that once any high-criticality task overruns, all high-criticality jobs execute up to their most pessimistic WCET estimations simultaneously in a one-shot manner. This is very pessimistic in the sense of unnecessary resource overbooking. In this paper, we propose a more generalized mixed-critical real-time task model, called flexible MC model with multiple-shot transitions (FMC-MST), to address this problem. In FMC-MST, high-criticality tasks can transit multiple intermediate levels to handle less pessimistic overruns independently and to nonuni-formly scale the deadline on each level. We develop a run-time schedulability analysis for FMC-MST under EDF-VD scheduling, in which a better tradeoff between the penalties of low-criticality tasks and the overruns of high-criticality tasks is achieved to improve the service quality of low-criticality tasks. We also develop a resource optimization technique to find resource-efficient level-insertion configurations for FMC-MST task systems under MC timing constraints. Experiments demonstrate the effectiveness of FMC-MST compared with the state-of-the-art techniques.

  • 103.
    Chen, Gang
    et al.
    Northeastern Univ, Sch Comp Sci & Engn, Shenyang 110004, Liaoning, Peoples R China.;Hong Kong Polytech Univ, Dept Comp, Hong Kong, Hong Kong, Peoples R China..
    Guan, Nan
    Hong Kong Polytech Univ, Dept Comp, Hong Kong, Hong Kong, Peoples R China..
    Liu, Di
    Yunnan Univ, Natl Pilot Sch Software, Kunming 650221, Yunnan, Peoples R China..
    He, Qingqiang
    Hong Kong Polytech Univ, Dept Comp, Hong Kong, Hong Kong, Peoples R China..
    Huang, Kai
    Sun Yet Sen Univ, Minist Educ, Key Lab Machine Intelligence & Adv Comp, Guangzhou 510275, Guangdong, Peoples R China..
    Stefanov, Todor
    Leiden Univ, Leiden Inst Adv Comp Sci, NL-2311 EZ Leiden, Netherlands..
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Northeastern Univ, Sch Comp Sci & Engn, Shenyang 110004, Liaoning, Peoples R China.
    Utilization-Based Scheduling of Flexible Mixed-Criticality Real-Time Tasks2018In: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 67, no 4, p. 543-558Article in journal (Refereed)
    Abstract [en]

    Mixed-criticality models are an emerging paradigm for the design of real-time systems because of their significantly improved resource efficiency. However, formal mixed-criticality models have traditionally been characterized by two impractical assumptions: once any high-criticality task overruns, all low-criticality tasks are suspended and all other high-criticality tasks are assumed to exhibit high-criticality behaviors at the same time. In this paper, we propose a more realistic mixed-criticality model, called the flexible mixed-criticality (FMC) model, in which these two issues are addressed in a combined manner. In this new model, only the overrun task itself is assumed to exhibit high-criticality behavior, while other high-criticality tasks remain in the same mode as before. The guaranteed service levels of low-criticality tasks are gracefully degraded with the overruns of high-criticality tasks. We derive a utilization-based technique to analyze the schedulability of this new mixed-criticality model under EDF-VD scheduling. During run time, the proposed test condition serves an important criterion for dynamic service level tuning, by means of which the maximum available execution budget for low-criticality tasks can be directly determined with minimal overhead while guaranteeing mixed-criticality schedulability. Experiments demonstrate the effectiveness of the FMC scheme compared with state-of-the-art techniques.

  • 104.
    Chen, Weili
    et al.
    Sun Yat-sen University, Guangzhou, China.
    Zheng, Zibin
    Sun Yat-sen University, Guangzhou, China.
    Jiahui, Cui
    Sun Yat-sen University, Guangzhou, China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zheng, Peilin
    Sun Yat-sen University, Guangzhou, China.
    Zhou, Yuren
    Sun Yat-sen University, Guangzhou, China.
    Detecting Ponzi Schemes on Ethereum: Towards Healthier Blockchain Technology2018In: WWW '18: Proceedings of the 2018 World Wide Web Conference, ACM Digital Library, 2018, p. 1409-1418Conference paper (Refereed)
    Abstract [en]

    Blockchain technology becomes increasingly popular. It also attracts scams, for example, Ponzi scheme, a classic fraud, has been found making a notable amount of money on Blockchain, which has a very negative impact. To help dealing with this issue, this paper proposes an approach to detect Ponzi schemes on blockchain by using data mining and machine learning methods. By verifying smart contracts on Ethereum, we first extract features from user accounts and operation codes of the smart contracts and then build a classification model to detect latent Ponzi schemes implemented as smart contracts. The experimental results show that the proposed approach can achieve high accuracy for practical use. More importantly, the approach can be used to detect Ponzi schemes even at the moment of its creation. By using the proposed approach, we estimate that there are more than 400 Ponzi schemes running on Ethereum. Based on these results, we propose to build a uniform platform to evaluate and monitor every created smart contract for early warning of scams.

  • 105.
    Chen, Weili
    et al.
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Zheng, Zibin
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zheng, Peilin
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Zhou, Yuren
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Exploiting Blockchain Data to Detect Smart Ponzi Schemes on Ethereum2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 37575-37586Article in journal (Refereed)
    Abstract [en]

    Blockchain technology becomes increasingly popular. It also attracts scams, for example, a Ponzi scheme, a classic fraud, has been found making a notable amount of money on Blockchain, which has a very negative impact. To help to deal with this issue and to provide reusable research data sets for future research, this paper collects real-world samples and proposes an approach to detect Ponzi schemes implemented as smart contracts (i.e., smart Ponzi schemes) on the blockchain. First, 200 smart Ponzi schemes are obtained by manually checking more than 3,000 open source smart contracts on the Ethereum platform. Then, two kinds of features are extracted from the transaction history and operation codes of the smart contracts. Finally, a classification model is presented to detect smart Ponzi schemes. The extensive experiments show that the proposed model performs better than many traditional classification models and can achieve high accuracy for practical use. By using the proposed approach, we estimate that there are more than 500 smart Ponzi schemes running on Ethereum. Based on these results, we propose to build a uniform platform to evaluate and monitor every created smart contract for early warning of scams.

  • 106. Chen, Yu-Fang
    et al.
    Hong, Chih-Duo
    Lin, Anthony W.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Learning to prove safety over parameterised concurrent systems2017In: Proceedings of the 17th International Conference on Formal Methods in Computer-Aided Design, IEEE, 2017, p. 76-83Conference paper (Refereed)
  • 107. Clear, Tony
    et al.
    Beecham, Sarah
    Barr, John
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    McDermott, Roger
    Oudshoorn, Michael
    Savickaite, Airina
    Noll, John
    Challenges and recommendations for the design and conduct of global software engineering courses: A systematic review2015In: Proc. 20th ITiCSE Working Group Reports, New York: ACM Press, 2015, p. 1-39Conference paper (Refereed)
  • 108.
    Clear, Tony
    et al.
    Auckland Univ Technol, Sch Engn Comp & Math Sci, Auckland, New Zealand..
    Beecham, Sarah
    Univ Limerick, Lero, Limerick, Ireland..
    Barr, John
    Ithaca Coll, Ithaca, NY 14850 USA..
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Oudshoorn, Michael
    Wentworth Inst Technol, Dept Comp Sci & Comp Networking, Boston, MA USA..
    Noll, John
    Univ Limerick, Lero, Limerick, Ireland..
    Developments in Global Software Engineering Education2016In: 2016 IEEE FRONTIERS IN EDUCATION CONFERENCE (FIE), 2016Conference paper (Refereed)
    Abstract [en]

    An ITiCSE 2015 conference working group report has recently delivered a comprehensive systematic review of the literature addressing the challenges and solutions in teaching global software engineering courses. In this panel session, a group of authors of that report will review the findings, and present their own views on teaching such courses, the pros and cons and their own motivations and experiences, together with strategies that have proven effective. We argue that these courses are critical for preparing students for practice as software engineers in today's global settings, but they are certainly not for the faint-hearted. After the review and presentation of position statements by panelists there will be a question and answer session with the audience and a discussion elaborating on the next frontiers in research and practice for global software engineering education.

  • 109. Clear, Tony
    et al.
    McDermott, Roger
    Parsjö, Elin
    Cajander, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Lagerqvist, Nanna
    A framework for writing learning agreements2016In: Proc. 46th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2016Conference paper (Refereed)
    Abstract [en]

    Active learning is a popular concept for motivating learning. Learning agreements are one strategy towards this goal. They can be used to aid the students to take ownership of their learning and in becoming more active in a course. Learning Agreements are especially useful tools for scaffolding learning in courses with a focus on developing the professional competencies of students, such as in Open Ended Group Projects, Work Integrated Learning or other authentic learning contexts. Such educational contexts are complex and we have found it necessary to scaffold student learning using agreements based on professional competencies. This has led to a pedagogical framework, which has found successful application in a number of contexts. This framework has been built based on discussions with students, and has involved the development of a supporting wiki which contains descriptions of the different professional competencies involved in the learning agreement. The IT based framework has been iteratively developed together with the students taking the course in the fall of 2015. The development and assessment of this framework is contrasted in the context of two courses using learning agreements, one (in Sweden) with a focus on development of professional competencies and the other (in New Zealand) addressing a mix of professional competencies and subject knowledge in a work integrated learning setting.

  • 110. Cohen, Katie
    et al.
    Isbister, Tim
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Shrestha, Amendra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Linguistic markers of a radicalized mind-set among extreme adopters2017In: Proc. 10th ACM International Conference on Web Search and Data Mining, New York: ACM Press, 2017, p. 823-824Conference paper (Refereed)
    Abstract [en]

    The words that we use when communicating in social media can reveal how we relate to ourselves and to others. For instance, within many online communities, the degree of adaptation to a community-specific jargon can serve as a marker of identification with the community. In this paper we single out a group of so called extreme adopters of community-specific jargon from the whole group of users of a Swedish discussion forum devoted to the topics immigration and integration. The forum is characterized by a certain xenophobic jargon, and we hypothesize that extreme adopters of this jargon also exhibit certain linguistic features that we view as markers of a radicalized mind-set. We use a Swedish translation of LIWC (linguistic inquiry word count) and find that the group of extreme adopters differs significantly from the whole group of forum users regarding six out of seven linguistic markers of a radicalized mind-set.

  • 111.
    Corneo, Lorenzo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Scheduling at the Edge for Assisting Cloud Real-Time Systems2018In: Proceedings of the 2018 Workshop on Theory and Practice for Integrated Cloud, Fog and Edge Computing Paradigms, New York, NY, USA: ACM , 2018, p. 9-14Conference paper (Refereed)
    Abstract [en]

    We study edge server support for multiple periodic real-time applications located in different clouds. The edge communicates both with sensor devices over wireless sensor networks and with applications over Internet type networks. The edge caches sensor data and can respond to multiple applications with different timing requirements to the data. The purpose of caching is to reduce the number of multiple direct accesses to the sensor since sensor communication is very energy expensive. However, the data will then age in the cache and eventually become stale for some application. A push update method and the concept of age of information is used to schedule data updates to the applications. An aging model for periodic updates is derived. We propose that the scheduling should take into account periodic sensor updates, the differences in the periodic application updates, the aging in the cache and communication variance. By numerical analysis we study the number of deadline misses for two different scheduling policies with respect to different periods.

  • 112.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    My SIGCSE -> ITiCSE2018In: ACM inroads, ISSN 2153-2184, E-ISSN 2153-2192, Vol. 9, no 4, p. 101-101Article in journal (Refereed)
    Abstract [en]

    My SIGCSE is rather my ITiCSE, since this conference has become part of my identity. This is not just professional, it is also very personal. Education has always been special to me and attending conferences, such as SIGCSE and ITiCSE, has been essential to get a better foundation for my strong drive to improve education, both at Uppsala University and elsewhere. Thinking back to my first conferences the main impression is "coming home," to be where I belong among positive and supporting people discussing matters that I deeply care about. This is also evident in my line of research. I started my academic career as a researcher in formal methods in computer science, specifically in timing aspects in computer architecture and computer networks and subsequently changed to the area of discipline-based education research. Attending SIGCSE and ITiCSE has been instrumental in this shift as well as the creation of the Uppsala Computing Education research Group (UpCERG).

  • 113.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Professional Competencies for Real?: A Question about Identity!2016In: ITiCSE '16 Proceedings of the 2016 ACM Conference in Innovation and Technology in Computer Science Education, ACM Digital Library, 2016Conference paper (Other academic)
    Abstract [en]

    How students develop professional competencies has been an interest for me for decades. There are several aspects to this issue that I have addressed, e.g. what are professional competencies, how can their development of them be supported in educational settings, what motivates a student to put in an effort towards developing a competency, how can they be assessed, how can progression of professional competencies be handled in education curricula, and how can development of professional competencies be specified in a course description. These are among the more prominent issues that have been on my mind. In this work I have noticed a huge "gap" between how professional competencies are expressed as important learning outcomes of degree programs and the almost zero link to how this development should be done at the course instance level. This "gap" is frustrating for me and a source for thoughts regarding how to bridge that "gap". Work in our research group UpCERG (Uppsala Computing Education Research Group, www.it.uu.se/research/group/upcerg) has lately included studying issues related to identity, initially mostly the identity of different student cohorts, but now also that of teachers and education leaders. This research provides valuable insights towards causes for the "gap". That is, the slow closing of the "gap" can be understood by placing this in the context of the identity of the teachers (especially) and the students. It is how professional competencies are valued in relation to "pure" subject knowledge among these identities that provides severe obstacles to inclusion of development of professional competencies in a meaningful way at the course instance level. This is despite much of the previous work regarding issues related to developing professional competencies in educational settings, as those mentioned above.

  • 114.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    The Educator Identity and its Impact2017In: SIGCSE '17 Proceedings of the 2017 ACM SIGCSE Technical Symposium on Computer Science Education, ACM Digital Library, 2017Conference paper (Other academic)
    Abstract [en]

    I'm going to address the educator identity from two perspectives. The first is my own perspective, where I will present what my educator identity means to me and what this has led me to devote time and energy on. My vision is that I want to be part of creating learning environments that benefit both the learner as an individual and society in general from many dimensions and purposes. As an educator I want to support our students on a route to become able and conscious graduates who will have a positive impact and be seen as truly professionally competent wherever their career takes them. This sounds hunky-dory, but how can it be achieved? I don't think there are any silver bullets that will lead to such a setting, but I do believe that knowing more is a way forward. Having no clear way forward was frustrating and this is where involvement in educator communities, like the SIGCSE community, became essential. Giving time and effort to such communities is, in my opinion, rewarding itself manyfold, not least, in my case, for aiding to understand the issues and opportunities involved in pursuing my vision. Developing my identity as educator through being part of the SIGCSE community, with its abundance of role models, has been invaluable for me. I hope my work will be an inspiration for others. Computing and engineering education research is the other big part in my strive for fulfilling my educator dreams. Or should I say pipe dreams as in the title of my thesis "Developing and Assessing Professional Competencies: a Pipe Dream? Experiences from an Open-Ended Group Project Learning Environment", which I defended on the day thirty years after I enrolled as a PhD student? No, I don't see it as a pipe dream even though there are much more to look into and understand regarding education in our field. This research area is the second perspective I want to bring up regarding educator identity, and I will use the research lens to look at the impact we as educators have on our students. My focus will be on the influence educators have on students learning with regard to aspects beyond pure computing skills. I will in the presentation build on work in our research group (UpCERG), which lately has included studying issues related to identity, both students and educators. I especially want to draw attention to the potential impact we as educators have on the "gap" between graduating truly professionally competent persons and merely technically competent persons

  • 115.
    Daniels, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cajander, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Clear, Tony
    McDermott, Roger
    Collaborative technologies in global engineering: New competencies and challenges2015In: International journal of engineering education, ISSN 0949-149X, Vol. 31, no 1, p. 267-281Article in journal (Refereed)
    Abstract [en]

    Educational institutions face many challenges in closing the gap between what is currently offered through academic engineering curricula and what is expected by society in general and industry in particular. There are many aspects to these challenges and here we address needs that are specific to global professionals by investigating the knowledge, skills and abilities needed for mediating and using Collaborative Technologies (CT) in an Open Ended Group Project (OEGP) within a global setting. We discuss these needs as framed by relevant theoretical frameworks for collaboration and learning (including Collaborative knowledge building and Collaborative Technology Fit), mapped using empirical data from a course setting involving global collaboration between two universities (one in the United States and one in Sweden). The paper concludes with a commentary on competencies beyond discipline specific technical skills and presents recommendations, based upon this research, for developing students’ proficiency in both mediating and using CTs in OEGP courses. These recommendations are followed by an outline of key areas for future research.

  • 116.
    Daniels, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cajander, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Eckerdal, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Lind, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Nylén, Aletta
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Clear, Tony
    McDermott, Roger
    Competencies for paradigm shift "survival"2015In: Proc. 45th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2015, p. 1424-1429Conference paper (Refereed)
  • 117.
    Demyanova, Yulia
    et al.
    Vienna University of Technology.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zuleger, Florian
    Vienna University of Technology.
    Systematic predicate abstraction using variable roles2017In: NASA Formal Methods, Springer, 2017, p. 265-281Conference paper (Refereed)
  • 118.
    Ekberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Models and Complexity Results in Real-Time Scheduling Theory2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    When designing real-time systems, we want to prove that they will satisfy given timing constraints at run time. The main objective of real-time scheduling theory is to analyze properties of mathematical models that capture the temporal behaviors of such systems. These models typically consist of a collection of computational tasks, each of which generates an infinite sequence of task activations. In this thesis we study different classes of models and their corresponding analysis problems.

    First, we consider models of mixed-criticality systems. The timing constraints of these systems state that all tasks must meet their deadlines for the run-time scenarios fulfilling certain assumptions, for example on execution times. For the other scenarios, only the most important tasks must meet their deadlines. We study both tasks with sporadic activation patterns and tasks with complicated activation patterns described by arbitrary directed graphs. We present sufficient schedulability tests, i.e., methods used to prove that a given collection of tasks will meet their timing constraints under a particular scheduling algorithm.

    Second, we consider models where tasks can lock mutually exclusive resources and have activation patterns described by directed cycle graphs. We present an optimal scheduling algorithm and an exact schedulability test.

    Third, we address a pair of longstanding open problems in real-time scheduling theory. These concern the computational complexity of deciding whether a collection of sporadic tasks are schedulable on a uniprocessor. We show that this decision problem is strongly coNP-complete in the general case. In the case where the asymptotic resource utilization of the tasks is bounded by a constant smaller than 1, we show that it is weakly coNP-complete.

    List of papers
    1. Bounding and shaping the demand of generalized mixed-criticality sporadic task systems
    Open this publication in new window or tab >>Bounding and shaping the demand of generalized mixed-criticality sporadic task systems
    2014 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 50, no 1, p. 48-86Article in journal (Refereed) Published
    Abstract [en]

    We generalize the commonly used mixed-criticality sporadic task model to let all task parameters (execution-time, deadline and period) change between criticality modes. In addition, new tasks may be added in higher criticality modes and the modes may be arranged using any directed acyclic graph, where the nodes represent the different criticality modes and the edges the possible mode switches. We formulate demand bound functions for mixed-criticality sporadic tasks and use these to determine EDF-schedulability. Tasks have different demand bound functions for each criticality mode. We show how to shift execution demand between different criticality modes by tuning the relative deadlines. This allows us to shape the demand characteristics of each task. We propose efficient algorithms for tuning all relative deadlines of a task set in order to shape the total demand to the available supply of thecomputing platform. Experiments indicate that this approach is successful in practice. This new approach has the added benefit of supporting hierarchical scheduling frameworks.

    National Category
    Computer Sciences
    Research subject
    Computer Science with specialization in Real Time Systems
    Identifiers
    urn:nbn:se:uu:diva-212779 (URN)10.1007/s11241-013-9187-z (DOI)000328351200003 ()
    Projects
    UPMARC
    Available from: 2013-06-15 Created: 2013-12-13 Last updated: 2018-01-11Bibliographically approved
    2. Schedulability analysis of a graph-based task model for mixed-criticality systems
    Open this publication in new window or tab >>Schedulability analysis of a graph-based task model for mixed-criticality systems
    2016 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 52, no 1, p. 1-37Article in journal (Refereed) Published
    National Category
    Computer Sciences
    Research subject
    Computer Science with specialization in Real Time Systems
    Identifiers
    urn:nbn:se:uu:diva-265781 (URN)10.1007/s11241-015-9225-0 (DOI)000370819700001 ()
    Available from: 2015-05-01 Created: 2015-11-03 Last updated: 2018-01-10Bibliographically approved
    3. An optimal resource sharing protocol for generalized multiframe tasks
    Open this publication in new window or tab >>An optimal resource sharing protocol for generalized multiframe tasks
    2015 (English)In: The Journal of logical and algebraic methods in programming, ISSN 2352-2208, E-ISSN 2352-2216, Vol. 84, no 1, p. 92-105Article in journal (Refereed) Published
    National Category
    Computer Engineering
    Research subject
    Computer Science with specialization in Real Time Systems
    Identifiers
    urn:nbn:se:uu:diva-235474 (URN)10.1016/j.jlamp.2014.10.001 (DOI)000347601600007 ()
    Projects
    UPMARC
    Available from: 2014-10-16 Created: 2014-11-04 Last updated: 2018-01-11Bibliographically approved
    4. Uniprocessor feasibility of sporadic tasks with constrained deadlines is strongly coNP-complete
    Open this publication in new window or tab >>Uniprocessor feasibility of sporadic tasks with constrained deadlines is strongly coNP-complete
    2015 (English)In: Proc. 27th Euromicro Conference on Real-Time Systems, Piscataway, NJ: IEEE, 2015, p. 281-286Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Piscataway, NJ: IEEE, 2015
    National Category
    Computer Sciences
    Research subject
    Computer Science with specialization in Real Time Systems
    Identifiers
    urn:nbn:se:uu:diva-265783 (URN)10.1109/ECRTS.2015.32 (DOI)000375052900025 ()978-1-4673-7570-2 (ISBN)
    Conference
    ECRTS 2015, July 7–10, Lund, Sweden
    Projects
    UPMARC
    Available from: 2015-08-06 Created: 2015-11-03 Last updated: 2018-01-10Bibliographically approved
    5. Uniprocessor feasibility of sporadic tasks remains coNP-complete under bounded utilization
    Open this publication in new window or tab >>Uniprocessor feasibility of sporadic tasks remains coNP-complete under bounded utilization
    2015 (English)In: Proc. 36th Real-Time Systems Symposium, IEEE Computer Society, 2015, p. 87-95Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    IEEE Computer Society, 2015
    National Category
    Computer Sciences
    Research subject
    Computer Science with specialization in Real Time Systems
    Identifiers
    urn:nbn:se:uu:diva-265784 (URN)10.1109/RTSS.2015.16 (DOI)000380424600009 ()978-1-4673-9507-6 (ISBN)
    Conference
    RTSS 2015, December 1–4, San Antonio, TX
    Projects
    UPMARC
    Available from: 2016-01-18 Created: 2015-11-03 Last updated: 2018-01-10Bibliographically approved
  • 119.
    Ekberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Guan, Nan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Stigge, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    An optimal resource sharing protocol for generalized multiframe tasks2015In: The Journal of logical and algebraic methods in programming, ISSN 2352-2208, E-ISSN 2352-2216, Vol. 84, no 1, p. 92-105Article in journal (Refereed)
  • 120.
    Ekberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Fixed-Priority Schedulability of Sporadic Tasks on Uniprocessors is NP-hard2017In: 2017 IEEE Real-Time Systems Symposium (RTSS), IEEE, 2017, p. 139-146Conference paper (Refereed)
    Abstract [en]

    We study the computational complexity of the FP-schedulability problem for sporadic or synchronous periodic tasks on a preemptive uniprocessor. We show that this problem is (weakly) NP-hard, even when restricted to either (i) task sets with implicit deadlines and rate-monotonic priority ordering, or (ii) task sets with constrained deadlines, deadline-monotonic priority ordering and utilization bounded by any constant c, such that 0 < c < 1.

  • 121.
    Ekberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Schedulability analysis of a graph-based task model for mixed-criticality systems2016In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 52, no 1, p. 1-37Article in journal (Refereed)
  • 122.
    Ekberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Uniprocessor feasibility of sporadic tasks remains coNP-complete under bounded utilization2015In: Proc. 36th Real-Time Systems Symposium, IEEE Computer Society, 2015, p. 87-95Conference paper (Refereed)
  • 123.
    Ekberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Uniprocessor feasibility of sporadic tasks with constrained deadlines is strongly coNP-complete2015In: Proc. 27th Euromicro Conference on Real-Time Systems, Piscataway, NJ: IEEE, 2015, p. 281-286Conference paper (Refereed)
  • 124.
    Ekemark, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Application of Daedal in Huawei’s Base Station Scheduler and Enlargement of Extended Data-Race-Free Regions through Conflict Isolation2018Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 125. Eriksson, Anders E.
    et al.
    Ohlman, Börje
    Persson, Karl-Åke
    Malik, Adeel Mohammad
    Ihlar, Marcus
    Sunde, Linus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Scalable point-to-multipoint communication for cloud networking using information-centric networking2015In: Proc. 12th IEEE Consumer Communications and Networking Conference, Piscataway, NJ: IEEE , 2015, p. 654-662Conference paper (Refereed)
  • 126. Felsing, Dennis
    et al.
    Grebing, Sarah
    Klebanov, Vladimir
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ulbrich, Mattias
    Automating regression verification2015In: Software Engineering & Management 2015, Germany: Gesellschaft für Informatik , 2015, p. 75-76Conference paper (Refereed)
  • 127.
    Feng, Zhiwei
    et al.
    Northeastern Univ, Sch Comp Sci & Engn, Shenyang, Liaoning, Peoples R China; Univ Illinois, Urbana, IL USA.
    Guan, Nan
    Hong Kong Polytech Univ, Dept Computat, Hung Hom, Kowloon, Hong Kong, Peoples R China.
    Lv, Mingsong
    Northeastern Univ, Sch Comp Sci & Engn, Shenyang, Liaoning, Peoples R China.
    Liu, Weichen
    Nanyang Technol Univ, Sch Comp Sci & Engn, Singapore, Singapore.
    Deng, Qingxu
    Northeastern Univ, Sch Comp Sci & Engn, Shenyang, Liaoning, Peoples R China.
    Liu, Xue
    McGill Univ, Dept Math & Stat, Montreal, Canada; McGill Univ, Dept Elect & Comp Engn, Montreal, Canada.
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    An Efficient UAV Hijacking Detection Method Using Onboard Inertial Measurement Unit2019In: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 17, no 6, article id 96Article in journal (Refereed)
    Abstract [en]

    With the fast growth of civil drones, their security problems meet significant challenges. A commercial drone may be hijacked by a GPS-spoofing attack for illegal activities, such as terrorist attacks. The target of this article is to develop a technique that only uses onboard gyroscopes to determine whether a drone has been hijacked. Ideally, GPS data and the angular velocities measured by gyroscopes can be used to estimate the acceleration of a drone, which can be further compared with the measurement of the accelerometer to detect whether a drone has been hijacked. However, the detection results may not always be accurate due to some calculation and measurement errors, especially when no hijacking occurs in curve trajectory situations. To overcome this, in this article, we propose a novel and simple method to detect hijacking only based on gyroscopes' measurements and GPS data, without using any accelerometer in the detection procedure. The computational complexity of our method is very low, which is suitable to be implemented in the drones with micro-controllers. On the other hand, the proposed method does not rely on any accelerometer to detect attacks, which means it receives less information in the detection procedure and may reduce the results accuracy in some special situations. While the previous method can compensate for this flaw, the high detection results also can be guaranteed by using the above two methods. Experiments with a quad-rotor drone are conducted to show the effectiveness of the proposed method and the combination method.

  • 128.
    Feng, Zhiwei
    et al.
    Northeastern Univ, Shenyang, Peoples R China..
    Guan, Nan
    Hong Kong Polytech Univ, Hong Kong, Hong Kong, Peoples R China..
    Lv, Mingsong
    Northeastern Univ, Shenyang, Peoples R China..
    Liu, Weichen
    Chongqing Univ, Chongqing, Peoples R China..
    Deng, Qingxu
    Northeastern Univ, Shenyang, Peoples R China..
    Liu, Xue
    McGill Univ, Montreal, PQ, Canada..
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Northeastern Univ, Shenyang, Peoples R China.
    Efficient Drone Hijacking Detection using Onboard Motion Sensors2017In: Proceedings Of The 2017 Design, Automation & Test In Europe Conference & Exhibition (DATE), IEEE , 2017, p. 1414-1419Conference paper (Refereed)
    Abstract [en]

    The fast growth of civil drones raises significant security challenges. A legitimate drone may be hijacked by GPS spoofing for illegal activities, such as terrorist attacks. The target of this paper is to develop techniques to let drones detect whether they have been hijacked using onboard motion sensors (accelerometers and gyroscopes). Ideally, the linear acceleration and angular velocity measured by motion sensors can be used to estimate the position of a drone, which can be compared with the position reported by GPS to detect whether the drone has been hijacked. However, the position estimation by motion sensors is very inaccurate due to the significant error accumulation over time. In this paper, we propose a novel method to detect hijacking based on motion sensors measurements and GPS, which overcomes the accumulative error problem. The computational complexity of our method is very low, and thus is suitable to be implemented in the micro-controllers of drones. Experiments with a quad-rotor drone are conducted to show the effectiveness of the proposed method.

  • 129.
    Fernquist, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Fängström, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Swedish Def Res Agcy, Stockholm, Sweden..
    IoT Data Profiles: The Routines of Your Life Reveals Who You Are2017In: 2017 European Intelligence and Security Informatics Conference (EISIC) / [ed] Brynielsson, J, IEEE, 2017, p. 61-67Conference paper (Refereed)
    Abstract [en]

    Preserving privacy is getting more and more important. The new EU general data protection regulation (GDPR) which will apply from May 2018 will introduce developments to some areas of EU data protection law and increase the privacy and personal integrity by strengthen and unify data protection for all individuals in EU. GDPR will most likely have an impact on many organizations and put pressure on many organizations that handle data. In this work, we investigate to what extent data profiles consisting of data from connected things can be used to identify a user. We use time and event profiles that can be created based on when, where and how a user communicates and uses digital devices. Our results show that such data profiles can be used to identify individuals and that collecting and creating data profiles of users can be seen as a serious threat towards privacy and personal integrity.

  • 130.
    Figea, Léo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Scrivens, Ryan
    Measuring online affects in a white supremacy forum2016In: Proc. 14th International Conference on Intelligence and Security Informatics, IEEE, 2016, p. 85-90Conference paper (Refereed)
  • 131.
    Forsberg, Bjoern
    et al.
    Swiss Fed Inst Technol Zurich, D ITET, Zurich, Switzerland..
    Lampka, Kai
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Spiliopoulos, Vasileios
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    An Online Overclocking Scheme for Bursty Real-time Tasks and an Evaluation of its Thermal Impact2016In: 14Th ACM/IEEE Symposium On Embedded Systems For Real-Time Multimedia (ESTIMEDIA 2016), 2016, p. 104-113Conference paper (Refereed)
    Abstract [en]

    This paper proposes a scheme which drives a processor beyond its rated operation frequency, e.g., by exploiting Intel's boost technology, to digest the peak workload of the system in time. In the setting of deadline constrained workloads, this is far from trivial: the boost mode can only be used during short time spans, therefore it can only help to digest the peak workload, rather than serving the normal case. A lowered processor frequency, used outside the peak workload time, yields a backlog of not completed jobs. This backlog may result in deadline violations or buffer overflows, if the next burst of job arrivals appears too early. To overcome the above problem, we propose a peak workload aware speed assignment strategy, which only allows the system to build up computation backlog if the absence of high computation demands is assured. Contrasting the existing body of work, we take advantage of bursty arrival patterns of compute jobs, thereby progressing over the standard (non-bursty sporadic) job release model. Together with our scheme, we also present a tool chain and simulations of synthetic workloads for investigating the thermal effects of different speed assignment strategies.

  • 132.
    Frezza, S.
    et al.
    Gannon Univ, 109 Univ Sq, Erie, PA 16541 USA.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wilkin, A.
    Rose Hulman Inst Technol, 5500 Wabash Ave, Terre Haute, IN 47803 USA.
    Assessing Students' IT Professional Values in a Global Project Setting2019In: ACM Transactions on Computing Education, ISSN 1946-6226, E-ISSN 1946-6226, Vol. 19, no 2, article id 9Article in journal (Refereed)
    Abstract [en]

    This research aimed at evaluating the development and use of low-cost affective domain assessment instruments, culminating with personal and group characterization of representative global information technology (IT) professional values. Values and valuing are a compelling component of Bloom's affective domain of learning for engineering education. In helping students develop professional engineering competencies, it is essential that they develop not just cognitive knowledge of something but also values related to that knowledge and the ability to express these values in professional action. However, even if some professional values are identified, understood, and expressed, assessing student's values and valuing are difficult, and assessment instruments are often difficult to develop, particularly for assessing student learning in the context of a particular course. This exploratory study aimed at examining assessment of dispositional knowledge in the context of global software engineering (GSE). It focused on the development and use of a set of instruments for assessing affective domain student learning of global IT/software engineering (SE) professional values. The project included making explicit the IT professional values of interest among the participating faculty in the form of actionable value statements. Following a process derived from Thurstone scale development, the project included validation of these statements with an expert panel as question roots, followed by the use of these questions to investigate student and alumni receiving, responding, and valuing of these professional values. The effort needed to generate questionnaires suitable for course use was relatively low; these questionnaires were deployed to students and alumni from an open-ended global software engineering project course. Students responding reported significant agreement when receiving these global values, but sent more mixed responses in responding to and valuing them. The effort helped identify several actionable IT professional values worth reinforcing in future course offerings.

  • 133. Frezza, Stephen
    et al.
    Pears, Arnold
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kann, Viggo
    Kapoor, Amanpreet
    McDermott, Roger
    Peters, Anne-Kathrin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wallace, Charles
    Sabin, Mihaela
    Cajander, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Modeling global competencies for computing education2018In: Proc. 23rd Conference on Innovation and Technology in Computer Science Education, New York: ACM Press, 2018, p. 348-349Conference paper (Refereed)
  • 134.
    Fängström, Torbjörn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Internet of Things and Future Threats Towards our Society2015In: Proc. National Symposium on Technology and Methodology for Security and Crisis Management: TAMSEC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    Internet of Things (IoT) is all things around us that are connected to the Internet. New technologies such as small and cheap sensors with wireless communication makes it possible to connect most of the electronic devices we use in our everyday life and according to analyst firm Gartner, close to 26 billion things to be connected to the Internet of Things in 2020. However, with new technology new threats arises. The Internet of Things in combination with the increasing number of internet users globally creates new possibilities for attacks for criminals to exploit. In this work we will investigate Internet of things and possible threats towards the security of the society.

  • 135.
    Gallagher, John
    et al.
    Roskilde Univ, Roskilde, Denmark.;IMDEA Software Inst, Madrid, Spain..
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Preface, Electronic Proceedings in Theoretical Computer Science. Vol 2192016In: Electronic Proceedings in Theoretical Computer Science, ISSN 2075-2180, E-ISSN 2075-2180, no 219Article in journal (Other academic)
  • 136.
    Giustiniano, Domenico
    et al.
    IMDEA Networks.
    Varshney, Ambuj
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Connecting Battery-free IoT Tags Using LED Bulbs2018Conference paper (Refereed)
  • 137.
    Grande, Virginia
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Lost for Words! Defining the Language Around Role Models in Engineering2018In: Proc. 48th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2018Conference paper (Refereed)
    Abstract [en]

    This full paper in the research category contains a vocabulary to describe role modeling in engineering education. The term role model is loosely defined but widely used in the literature, particularly in broadening participation. During our interviews with teachers in the discipline, there was no consensus on what a role model nor on the meaning of adjectives to evaluate them. Here a vocabulary around the phenomenon of role modeling is developed, favoring the point of view of the role models themselves. It aims to support educators who reflect on how to be effective role models for their students. We define what a role model in engineering education is, and what this person may model: an aspect (a competency, a character attribute or an attitude) or and achievement. Main actors and types of models according to awareness and intention of the modeling are covered, as well as how the modeling may be perceived by others. We indicate differences and overlaps with other terms, such as mentor, that are sometimes used interchangeably. Finally, we discuss the challenges of defining this vocabulary due to the subjectiveness of the topic: who defines the norm for what is an ideal professional in engineering?

  • 138.
    Grande, Virginia
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Uppsala Univ, Uppsala, Sweden.
    Lost for Words! Defining the Language Around Role Models in Engineering Education2018In: 2018 IEEE Frontiers in Education Conference (FIE), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    This full research paper contains a vocabulary to describe role modeling in engineering education. The term role model is widely used in the literature, particularly in broadening participation. However, it is loosely defined. Both its everyday and academic use varies. This was also observed during our interviews with teachers in the discipline: there was no consensus on what a role model is nor on the meaning of adjectives used to describe a role model. Considering the benefits of role models and the need for terminology that supports a common understanding of role modeling, we have developed a vocabulary around this phenomenon. We aim to support educators by providing them with a means to reflect on different dimensions of role modeling. We define what a role model in engineering is, and what they may model: an aspect (a competency, a character attribute or an attitude) or an achievement. Main actors and types of awareness and intention of the modeling are covered, as well as how the modeling may be perceived by others. We indicate differences and overlaps with terms such as mentor. Finally, we discuss challenges due to subjectiveness: who defines the norm for what an ideal professional in engineering is?

  • 139.
    Grande, Virginia
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Perspectives on Volunteering for Initiatives for Women in Computing: a Case Study2015Conference paper (Refereed)
    Abstract [en]

    Initiatives for women in computing exist since the 70's. However, little research has been done to study the effect they have on the women involved. Hence, this case study presents observations of the perceived value of the initiatives from the perspective of these women. This is a case study of one of the organizations contributing to this kind of initiative, the ACM (and its branch ACM-W), and how its volunteers see this work. The study is based on semi-structured interviews that were thematically coded and analysed. Results show that, depending on their generation, volunteers have different motivations and target their efforts at different audiences. Interviewees also reflected on how to further support women in computing. Finally, implications for future studies and lines of action are presented in the paper.

  • 140.
    Grande, Virginia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Experiences of teachers in computing as role models: a phenomenographic study2017In: Proc. 17th International Conference on Computing Education Research: Koli Calling, New York: ACM Press, 2017, p. 133-137Conference paper (Refereed)
    Abstract [en]

    The literature on role models lacks a focus on understanding teachers' role modelling from the teachers' own perspective. Our tentative research question is "How do teachers in computing experience being role models for their students?". We use a phenomenographic approach to describe the teachers' experiences of role modelling and their own understanding of the term. Different understandings of role model are shown in a structure of categories, focusing on subject domain, perception of the model by others, and influence from and impact on the context.

  • 141.
    Grande, Virginia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A diversity lens on the last decade of the FIE conference: Role models for the engineering community2017In: Proc. 47th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2017Conference paper (Refereed)
  • 142.
    Grande, Virginia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Motivation and Grade Gap Related to Gender in a Programming Course2015Conference paper (Refereed)
  • 143.
    Grande, Virginia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Peters, Anne-Kathrin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Tedre, Matti
    "Participating under the influence": How role models affect the computing discipline, profession, and student population2018In: Proc. 48th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2018Conference paper (Refereed)
  • 144.
    Grass, Thomas
    et al.
    Barcelona Supercomp Ctr, Barcelona 08034, Spain;Rhein Westfal TH Aachen, D-52062 Aachen, Germany.
    Carlson, Trevor E.
    NUS, Singapore 119077, Singapore.
    Rico, Alejandro
    Arm Ltd, Austin, TX 78735 USA.
    Ceballos, Germán
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ayguade, Eduard
    Barcelona Supercomp Ctr, Barcelona 08034, Spain;Univ Politecn Cataluna, ES-08034 Barcelona, Spain.
    Casas, Marc
    Barcelona Supercomp Ctr, Barcelona 08034, Spain.
    Moreto, Miquel
    Barcelona Supercomp Ctr, Barcelona 08034, Spain;Univ Politecn Cataluna, ES-08034 Barcelona, Spain.
    Sampled Simulation of Task-Based Programs2019In: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 68, no 2, p. 255-269Article in journal (Refereed)
    Abstract [en]

    Sampled simulation is a mature technique for reducing simulation time of single-threaded programs. Nevertheless, current sampling techniques do not take advantage of other execution models, like task-based execution, to provide both more accurate and faster simulation. Recent multi-threaded sampling techniques assume that the workload assigned to each thread does not change across multiple executions of a program. This assumption does not hold for dynamically scheduled task-based programming models. Task-based programming models allow the programmer to specify program segments as tasks which are instantiated many times and scheduled dynamically to available threads. Due to variation in scheduling decisions, two consecutive executions on the same machine typically result in different instruction streams processed by each thread. In this paper, we propose TaskPoint, a sampled simulation technique for dynamically scheduled task-based programs. We leverage task instances as sampling units and simulate only a fraction of all task instances in detail. Between detailed simulation intervals, we employ a novel fast-forwarding mechanism for dynamically scheduled programs. We evaluate different automatic techniques for clustering task instances and show that DBSCAN clustering combined with analytical performance modeling provides the best trade-off of simulation speed and accuracy. TaskPoint is the first technique combining sampled simulation and analytical modeling and provides a new way to trade off simulation speed and accuracy. Compared to detailed simulation, TaskPoint accelerates architectural simulation with 8 simulated threads by an average factor of 220x at an average error of 0.5 percent and a maximum error of 7.9 percent.

  • 145.
    Griggio, Alberto
    et al.
    Fdn Bruno Kessler, Trento, Italy..
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Preface to special issue on satisfiability modulo theories2017In: Formal methods in system design, ISSN 0925-9856, E-ISSN 1572-8102, Vol. 51, no 3, p. 431-432Article in journal (Other academic)
  • 146. Gu, Chuancai
    et al.
    Guan, Nan
    Feng, Zhiwei
    Deng, Qingxu
    Sharon Hu, Xiaobo
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Transforming real-time task graphs to improve schedulability2016In: Proc. 22nd International Conference on Embedded and Real-Time Computing Systems and Applications, IEEE Computer Society, 2016, p. 29-38Conference paper (Refereed)
  • 147. Guan, Nan
    et al.
    Han, Meiling
    Gu, Chuancai
    Deng, Qingxu
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bounding carry-in interference to improve fixed-priority global multiprocessor scheduling analysis2015In: Proc. 21st International Conference on Embedded and Real-Time Computing Systems and Applications, IEEE Computer Society, 2015, p. 11-20Conference paper (Refereed)
  • 148. Guan, Nan
    et al.
    Tang, Yue
    Abdullah, Jakaria
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Stigge, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Scalable timing analysis with refinement2015In: Tools and Algorithms for the Construction and Analysis of Systems, Springer, 2015, p. 3-18Conference paper (Refereed)
  • 149.
    Guan, Nan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Tang, Yue
    Wang, Yang
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delay analysis of structural real-time workload2015In: Proc. 18th Conference on Design, Automation and Test in Europe, Piscataway, NJ: IEEE, 2015, p. 223-228Conference paper (Refereed)
  • 150. Guan, Nan
    et al.
    Zhao, Mengying
    Xue, Chun Jason
    Liu, Yongpan
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Modular performance analysis of energy-harvesting real-time networked systems2015In: Proc. 36th Real-Time Systems Symposium, IEEE Computer Society, 2015, p. 65-74Conference paper (Refereed)
1234567 101 - 150 of 353
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