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  • 201.
    Li, Wenxiang
    et al.
    Wuhan Univ Sci & Technol, Sch Informat Sci & Engn, Wuhan 430081, Peoples R China.;Wuhan Univ Sci & Technol, Minist Educ, Engn Res Ctr Met Automat & Detecting Technol, Wuhan, Peoples R China..
    Zhu, Chunsheng
    Univ British Columbia, Dept Elect & Comp Engn, Vancouver, BC V6T 1Z4, Canada..
    Ngai, Edith C. -H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yang, Laurence T.
    St Francis Xavier Univ, Dept Comp Sci, Antigonish, NS B2G 2W5, Canada..
    Shu, Lei
    Guangdong Univ Petrochem Technol, Guangdong Prov Key Lab Petrochem Equipment Fault, Maoming 525000, Guangdong, Peoples R China..
    Sheng, Yuxia
    Wuhan Univ Sci & Technol, Sch Informat Sci & Engn, Wuhan 430081, Peoples R China.;Wuhan Univ Sci & Technol, Minist Educ, Engn Res Ctr Met Automat & Detecting Technol, Wuhan, Peoples R China..
    Facilities Collaboration in Cloud Manufacturing based on Generalized Collaboration Network2015In: Proceedings of the 11th EAI International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, 2015, p. 298-303Conference paper (Refereed)
    Abstract [en]

    In cloud manufacturing for regional industrial cluster, there is increasing necessity of collaboration among enterprises or facilities. It is valuable to explore the characteristics of these collaboration behaviors for effectively scheduling dispersed manufacturing facilities and organizing their collaboration. The collaborative relation of manufacturing in regional industrial cluster can be described as a generalized social collaboration network. In this paper, we introduce the relevant entities and relations of facilities collaboration, and propose the method for building Facility Collaboration Network (FCN). We further design the dynamically growing process of FCN for different facility selection strategies, including random selection, balanced selection, random selection with preference and balanced selection with preference. Based on the metrics such as network scale, node degree distribution, act degree distribution, average shortest distance and number of cliques, we present the statistical characteristics of FCN, and analyze relevant characteristics and laws for efficient facilities selection in cloud manufacturing.

  • 202. Li, Wenxiang
    et al.
    Zhu, Chunsheng
    Yang, Laurence T.
    Shu, Lei
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ma, Yajie
    Subtask scheduling for distributed robots in cloud manufacturing2017In: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 11, no 2, p. 941-950Article in journal (Refereed)
  • 203.
    Li, Yonghui
    et al.
    Eindhoven Univ Technol, NL-5600 MB Eindhoven, Netherlands.
    Åkesson, Benny
    CISTER INESC TEC, ISEP, Oporto, Portugal.
    Lampka, Kai
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Goossens, Kees
    Eindhoven Univ Technol, NL-5600 MB Eindhoven, Netherlands.
    Modeling and verification of dynamic command scheduling for real-time memory controllers2016In: 2016 IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS), IEEE Computer Society, 2016Conference paper (Refereed)
    Abstract [en]

    In modern multi-core systems with multiple real-time (RT) applications, memory traffic accessing the shared SDRAM is increasingly diverse, e.g., transactions have variable sizes. RT memory controllers with dynamic command scheduling can efficiently address the diversity by issuing appropriate commands subject to the SDRAM timing constraints. However, the scheduling dependencies between commands make it challenging to derive tight bounds for the worst-case response time (WCRT) and the worst-case bandwidth (WCBW) of a memory controller. Existing modeling and analysis techniques either do not provide tight WCRT and WCBW bounds for diverse memory traffic with variable transaction sizes or are difficult to adapt to different RT memory controllers. This paper models a memory controller using Timed Automata (TA), where model checking is applied for analysis. Our TA model is modular and accurately captures the behavior of a RT memory controller with dynamic command scheduling. We obtain WCRT and WCBW bounds, which are validated by simulating the worst-case transaction traces obtained by model checking with a cycle-accurate model of the memory controller. Our method outperforms three state-of-the-art analysis techniques. We reduce WCRT bound by up to 20%, while the average improvement is 7.7%, and increase the WCBW bound by up to 25% with an average improvement of 13.6%. In addition, our modeling is generic enough to extend to memory controllers with different mechanisms.

  • 204. Lin, Anthony W.
    et al.
    Nguyen, Truong Khanh
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Sun, Jun
    Regular Symmetry Patterns2016In: Verification, Model Checking, and Abstract Interpretation, Springer Berlin/Heidelberg, 2016, p. 455-475Conference paper (Refereed)
    Abstract [en]

    Symmetry reduction is a well-known approach for alleviating the state explosion problem in model checking. Automatically identifying symmetries in concurrent systems, however, is computationally expensive. We propose a symbolic framework for capturing symmetry patterns in parameterised systems (i.e. an infinite family of finite-state systems): two regular word transducers to represent, respectively, parameterised systems and symmetry patterns. The framework subsumes various types of "symmetry relations" ranging from weaker notions (e.g. simulation preorders) to the strongest notion (i.e. isomorphisms). Our framework enjoys two algorithmic properties: (1) symmetry verification: given a transducer, we can automatically check whether it is a symmetry pattern of a given system, and (2) symmetry synthesis: we can automatically generate a symmetry pattern for a given system in the form of a transducer. Furthermore, our symbolic language allows additional constraints that the symmetry patterns need to satisfy to be easily incorporated in the verification/synthesis. We show how these properties can help identify symmetry patterns in examples like dining philosopher protocols, self-stabilising protocols, and prioritised resource-allocator protocol. In some cases (e.g. Gries's coffee can problem), our technique automatically synthesises a safety-preserving finite approximant, which can then be verified for safety solely using a finite-state model checker.

  • 205.
    Lin, Anthony W.
    et al.
    Yale NUS Coll, Singapore, Singapore.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Liveness of randomised parameterised systems under arbitrary schedulers2016In: Computer Aided Verification: Part II, Springer, 2016, p. 112-133Conference paper (Refereed)
  • 206. Lin, Chuang
    et al.
    Ramakrishnan, Kadangode K.
    Liu, Jiangchuan
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Special Issue on Cloud Computing for IoT2016In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, no 3, p. 254-256Article in journal (Other academic)
  • 207. Lin, Hao
    et al.
    Xu, Wenyao
    Guan, Nan
    Ji, Dong
    Wei, Yangjie
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Noninvasive and continuous blood pressure monitoring using wearable body sensor networks2015In: IEEE Intelligent Systems, ISSN 1541-1672, E-ISSN 1941-1294, Vol. 30, no 6, p. 38-48Article in journal (Refereed)
  • 208.
    Lind, Thomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    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.
    Sandblad, Bengt
    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.
    Lárusdóttir, Marta
    McDermott, Roger
    Clear, Tony
    Students envisioning the future2016In: Proc. 46th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2016Conference paper (Refereed)
    Abstract [en]

    How can students be included as critical stakeholders in the systems and services provided by a university? To address the whole student experience, we engaged students and employees at a large Swedish university in a vision seminar process to elicit how these groups envisioned an ideal future university, and the necessary changes to technology and organisational structures required to achieve this ideal version. The process entailed six four-hour workshops with four groups consisting of six participants each. A survey instrument was used to follow up on the participants' experiences of participating in the vision seminar process and their thoughts on the future of the university. The results show that the participating students were more positive compared to the university employees. The students envisioned harmonized interdepartmental systems, seamlessly integrating a variety of services into one university provided solution. The employees envisioned their future work as flexible, enabled by technology providing excellent support without hindering pedagogical and organisational development. Using technological frames, these visions of the future are identified, analysed and discussed in relation to the quality of university education and a holistic view on students' university experience. Finally we discuss the broader implications of the visions on the future of university education.

  • 209.
    Lindén, Jonatan
    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.
    Synchronization Techniques in Parallel Discrete Event Simulation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Discrete event simulation is an important tool for evaluating system models in many fields of science and engineering. To improve the performance of large-scale discrete event simulations, several techniques to parallelize discrete event simulation have been developed.

    In parallel discrete event simulation, the work of a single discrete event simulation is distributed over multiple processing elements. A key challenge in parallel discrete event simulation is to ensure that causally dependent events are processed in the correct order, so that the same simulation trajectory is produced as in a sequential simulation. To preserve chronology between events processed in parallel, different synchronization protocols have been devised, each carrying a cost in performance.

    This thesis presents techniques for reducing synchronization costs in two approaches to parallel discrete event simulation, viz., optimistic space-parallel and share-everything parallel discrete event simulation.

    Firstly, we develop a concurrent priority queue, to be used as, e.g., a central event queue in the share-everything approach to parallel discrete event simulation. The priority queue is based on skiplists. It improves over previous queues by incurring fewer global synchronization operations, thereby inducing less contention and improving scalability.

    Secondly, we study how to improve the performance of optimistic parallel discrete event simulation by disseminating accurate estimates of timestamps of future events. We present techniques for obtaining the estimates in two different methods for simulation of spatial stochastic models. The estimates allow processing elements to determine when to pause simulation with high precision, thereby reducing the amount of performed useless work.

    Finally, we observe that in the applications that we have studied, the phenomena of interest are often non-homogeneous and migrate over time. Due to this, the work distribution tends to become unbalanced among the processing elements. A solution is to rebalance the work dynamically. We propose a fine-grained local dynamic load balancing algorithm for parallel discrete event simulation. The load balancing algorithm reduces the number of events arriving out-of-order, thereby reducing the amount of time spent on corrective actions.

    List of papers
    1. A Skiplist-Based Concurrent Priority Queue with Minimal Memory Contention
    Open this publication in new window or tab >>A Skiplist-Based Concurrent Priority Queue with Minimal Memory Contention
    2018 (English)Report (Other academic)
    Series
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2018-003
    Keywords
    Concurrent Data Structures, Priority Queue, Lock-free, Non-blocking, Skiplist
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-342233 (URN)
    Projects
    CoDeR-MPUPMARC
    Available from: 2018-02-19 Created: 2018-02-19 Last updated: 2018-04-06Bibliographically approved
    2. Efficient inter-process synchronization for parallel discrete event simulation on multicores
    Open this publication in new window or tab >>Efficient inter-process synchronization for parallel discrete event simulation on multicores
    2015 (English)In: Proc. 3rd ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2015, p. 183-194Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    New York: ACM Press, 2015
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-260199 (URN)10.1145/2769458.2769476 (DOI)978-1-4503-3583-6 (ISBN)
    Conference
    SIGSIM-PADS 2015
    Projects
    UPMARC
    Available from: 2015-06-10 Created: 2015-08-17 Last updated: 2018-11-12Bibliographically approved
    3. Exposing inter-process information for efficient PDES of spatial stochastic systems on multicores
    Open this publication in new window or tab >>Exposing inter-process information for efficient PDES of spatial stochastic systems on multicores
    2019 (English)In: ACM Transactions on Modeling and Computer Simulation, ISSN 1049-3301, E-ISSN 1558-1195, Vol. 29, no 2, p. 11:1-25, article id 11Article in journal (Refereed) Published
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-342180 (URN)10.1145/3301500 (DOI)000468031300004 ()
    Projects
    UPMARC
    Available from: 2019-04-02 Created: 2018-02-19 Last updated: 2019-06-18Bibliographically approved
    4. Fine-grained local dynamic load balancing in PDES
    Open this publication in new window or tab >>Fine-grained local dynamic load balancing in PDES
    2018 (English)In: Proc. 6th ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2018, p. 201-212Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    New York: ACM Press, 2018
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-342174 (URN)10.1145/3200921.3200928 (DOI)978-1-4503-5092-1 (ISBN)
    Conference
    SIGSIM-PADS 2018
    Projects
    UPMARC
    Available from: 2018-05-14 Created: 2018-02-19 Last updated: 2018-11-12Bibliographically approved
  • 210.
    Lindén, Jonatan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bauer, Pavol
    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.
    Engblom, Stefan
    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.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Exposing inter-process information for efficient parallel discrete event simulation of spatial stochastic systems2017In: Proc. 5th ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2017, p. 53-64Conference paper (Refereed)
  • 211.
    Lindén, Jonatan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bauer, Pavol
    Engblom, Stefan
    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.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Exposing inter-process information for efficient PDES of spatial stochastic systems on multicores2019In: ACM Transactions on Modeling and Computer Simulation, ISSN 1049-3301, E-ISSN 1558-1195, Vol. 29, no 2, p. 11:1-25, article id 11Article in journal (Refereed)
  • 212.
    Lindén, Jonatan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bauer, Pavol
    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.
    Engblom, Stefan
    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.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Fine-grained local dynamic load balancing in PDES2018In: Proc. 6th ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2018, p. 201-212Conference paper (Refereed)
  • 213.
    Lindén, Jonatan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Skiplist-Based Concurrent Priority Queue with Minimal Memory Contention2018Report (Other academic)
  • 214.
    Liu, Di
    et al.
    Leiden Univ, Leiden, Netherlands..
    Spasic, Jelena
    Leiden Univ, Leiden, Netherlands..
    Guan, Nan
    Hong Kong Polytech Univ, Hong Kong, Hong Kong, Peoples R China..
    Chen, Gang
    Northeastern Univ, Shenyang, Peoples R China..
    Liu, Songran
    Northeastern Univ, Shenyang, Peoples R China..
    Stefanov, Todor
    Leiden Univ, Leiden, Netherlands..
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Northeastern Univ, Shenyang, Peoples R China..
    EDF-VD scheduling of mixed-criticality systems with degraded quality guarantees2016In: Proc. 37th Real-Time Systems Symposium, IEEE Computer Society, 2016, p. 35-46Conference paper (Refereed)
    Abstract [en]

    This paper studies real-time scheduling of mixed-criticality systems where low-criticality tasks are still guaranteed some service in the high-criticality mode, with reduced execution budgets. First, we present a utilization-based schedulability test for such systems under EDF-VD scheduling. Second, we quantify the suboptimality of EDF-VD (with our test condition) in terms of speedup factors. In general, the speedup factor is a function with respect to the ratio between the amount of resource required by different types of tasks in different criticality modes, and reaches 4/3 in the worst case. Furthermore, we show that the proposed utilization-based schedulability test and speedup factor results apply to the elastic mixed-criticality model as well. Experiments show effectiveness of our proposed method and confirm the theoretical suboptimality results.

  • 215. Liu, Qiang
    et al.
    Hu, Xiping
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Liang, Min
    Leung, Victor C. M.
    Cai, Zhiping
    Yin, Jianping
    A security patch addressing bandwidth request vulnerabilities in the IEEE 802.16 standard2016In: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 30, no 5, p. 26-34Article in journal (Refereed)
  • 216.
    Liu, Xiaoyang
    et al.
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, Beijing 100876, Peoples R China.
    Song, Zheng
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, Beijing 100876, Peoples R China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ma, Jian
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, Beijing 100876, Peoples R China.
    Wang, Wendong
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, Beijing 100876, Peoples R China.
    PM2.5 Monitoring using Images from Smartphones in Participatory Sensing2015Conference paper (Refereed)
    Abstract [en]

    Air pollution has become one of the most pressing environmental issues in many countries, including China. Fine-grained PM2.5 particulate data can prevent people from long time exposure and advance scientific research. However, existing monitoring systems with PM2.5 stationary sensors are expensive, which can only provide pollution data at sparse locations. In this paper we demonstrate for the first time that camera on smartphones can be used for low-cost and fine-grained PM2.5 monitoring in participatory sensing. We propose a LearningBased method to extract air quality related features from images taken by smartphones. These image features will be used to build the haze model that can estimate PM2.5 concentration depending on the reference sensors. We conducted extensive experiments over six months with two datasets to demonstrate the performance of the proposed solution using different models of smartphones. We believe that our findings will give profound impact in many research fields, including mobile sensing, activity scheduling, haze data collection and analysis.

  • 217.
    Liu, Xiuming
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Khankan, Abdul Rahman
    Alsioufi, Mohamad
    He, Zhitao
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cloud-Based Data Fusion in Green IoT for Smart Cities2017In: Proc. 14th International Conference on Embedded Wireless Systems and Networks, ACM Digital Library, 2017, p. 216-217Conference paper (Refereed)
  • 218.
    Liu, Xiuming
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Xi, Teng
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Data modelling with Gaussian process in sensor networks for urban environmental monitoring2016In: Proc. 24th International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, IEEE Computer Society, 2016, p. 457-462Conference paper (Refereed)
  • 219.
    Liu, Xiuming
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Xi, Teng
    State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing, China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wang, Wendong
    State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing, China.
    Path planning for aerial sensor networks with connectivity constraints2017In: 2017 IEEE International Conference on Communications (ICC), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Wireless sensor networks (WSN) based on unmanned aerial vehicles (UAV) are ideal platforms for monitoring dynamics over larger service area. On the other hand, aerial sensor networks (ASNs) are often required to be connected with a command center for sending data and receiving control messages in real time. In this paper, we study the problem of path planning for ASNs with connectivity constraints. The primary goal of path planning is driving UAVs to locations where the most informative measurements can be collected. Meanwhile, the worst link's capacity is assured to be greater than a pre-defined requirement. We proposed a solution for the path planning problem and it consists of two modules: network coordinator (NC) and motion controller (MC). The NC manages the topology of relay-assisted wireless communication networks. For the design of MC, we compare two motion strategies: maximum entropy and maximum mutual information. The simulation results show that our proposed solution achieves accurate signal reconstruction while maintaining the connectivity. We conclude that it's important to enable UAV-to-UAV communications for future ASN-based applications.

  • 220.
    Luca, Mottola
    et al.
    RISE Swedish Institute of Computer Science, Kista SE164 29, Sweden;Politecnico di Milano, Milano 20133, Italy.
    Picco, Gian Pietro
    University of Trento, Trento 38122, Italy.
    Oppermann, Felix
    Graz University of Technology, Ultimo, NSW 2007, Australia.
    Eriksson, Joakim
    RISE Swedish Institute of Computer Science, Kista SE164 29, Sweden SICS.
    Finne, Niclas
    RISE Swedish Institute of Computer Science, Kista SE164 29, Sweden SICS.
    Fuchs, Harald
    SAP, Walldorf, 69190, Germany.
    Gaglione, Andrea
    University of Trento, Trento 38122, Italy.
    Karnouskos, Stamatis
    SAP, Walldorf, 69190, Germany.
    Montero, Patricio
    Acciona Infraestructuras S.A. Alcobendas, Madrid 28108, Spain.
    Oertel, Nina
    SAP, Walldorf, 69190, Germany.
    Römer, Kay
    Graz University of Technology, Ultimo, NSW 2007, Australia.
    Spiess, Patrik
    SAP, Walldorf, 69190, Germany.
    Tranquillini, Stefano
    University of Trento, Trento 38122, Italy.
    Voigt, Thiemo
    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. RISE Swedish Institute of Computer Science, Kista, SE-164 29, Sweden.
    makeSense: Simplifying the Integration of Wireless Sensor Networks into Business Processes2019In: IEEE Transactions on Software Engineering, ISSN 0098-5589, E-ISSN 1939-3520, Vol. 45, no 6, p. 576-596Article in journal (Refereed)
    Abstract [en]

    A wide gap exists between the state of the art in developing Wireless Sensor Network (WSN) software and current practices concerning the design, execution, and maintenance of business processes. WSN software is most often developed based on low-level OS abstractions, whereas business process development leverages high-level languages and tools. This state of affairs places WSNs at the fringe of industry. The makeSense system addresses this problem by simplifying the integration of WSNs into business processes. Developers use BPMN models extended with WSN-specific constructs to specify the application behavior across both traditional business process execution environments and the WSN itself, which is to be equipped with application-specific software. We compile these models into a high-level intermediate language—also directly usable by WSN developers—and then into OS-specific deployment-ready binaries. Key to this process is the notion of meta-abstraction, which we define to capture fundamental patterns of interaction with and within the WSN. The concrete realization of meta-abstractions is application-specific; developers tailor the system configuration by selecting concrete abstractions out of the existing codebase or by providing their own. Our evaluation of makeSense shows that i) users perceive our approach as a significant advance over the state of the art, providing evidence of the increased developer productivity when using makeSense; ii) in large-scale simulations, our prototype exhibits an acceptable system overhead and good scaling properties, demonstrating the general applicability of makeSense; and, iii) our prototype—including the complete tool-chain and underlying system support—sustains a real-world deployment where estimates by domain specialists indicate the potential for drastic reductions in the total cost of ownership compared to wired and conventional WSN-based solutions.

  • 221. Lv, Mingsong
    et al.
    Guan, Nan
    Ma, Ye
    Ji, Dong
    Knippel, Erwin
    Liu, Xue
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Speed planning for solar-powered electric vehicles2016In: Proc. 17th International Conference on Future Energy Systems, New York: ACM Press, 2016, article id 6Conference paper (Refereed)
  • 222. Lv, Mingsong
    et al.
    Guan, Nan
    Reineke, Jan
    Wilhelm, Reinhard
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A survey on static cache analysis for real-time systems2016In: Leibniz Transactions on Embedded Systems, ISSN 2199-2002, Vol. 3, no 1, p. 05:1-48, article id 5Article, review/survey (Refereed)
  • 223. Lárusdóttir, Marta
    et al.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    McDermott, Roger
    Quality assurance using international curricula and employer feedback2015In: Conferences in Research and Practice in Information Technology, ISSN 1445-1336, Vol. 160, p. 19-27Article in journal (Refereed)
  • 224.
    Löscher, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    Targeted Property-Based Testing with Applications in Sensor Networks2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Testing is a fundamental part of modern software development, as it unveils bugs in the system under test and gives confidence in their correctness. Testing is often a laborious task as it typically requires to write by hand a plethora of test cases to test a system thoroughly. This task can be aided by high-level testing techniques such as random property-based testing (PBT) where the testing task is reduced to specifying properties that the system under test is expected to satisfy, and generators that produce well-distributed random inputs to these properties. However, as with all random testing techniques, the confidence in the system and the chances of finding a bug is proportional to the number of tests. If the set of possible inputs is large, even a high number of tests does not yield a satisfactory result. One example is testing sensor networks, where one not only needs to produce the inputs for the software system but also needs to consider the network topology and the systems environment.

    This dissertation presents targeted property-based testing, an enhanced form of PBT where the input generation is guided by a search strategy instead of being random, thereby combining the strengths of QuickCheck-like and search-based testing techniques. It furthermore presents an automation for the simulated annealing search strategy that reduces the manual task of using targeted PBT. We present concrete implementations for all presented techniques and a framework for PBT of sensor networks.

    Applying PBT to testing sensor networks has allowed us to test relatively complex software and uncover subtle and hard-to-find bugs. We evaluate targeted PBT by comparing it to its random counterpart on a series of case studies. We show that its testing performance is significantly higher than that of random PBT. Furthermore, we demonstrate that the extra effort required to use targeted PBT is limited to specifying a test goal. With these results, we argue that targeted PBT improves the state-of-the-art of software testing and ultimately leads to higher confidence in complex software systems.

  • 225.
    Malik, Adeel Mohammad
    et al.
    Ericsson, Stockholm, Sweden..
    Ahlgren, Bengt
    SICS Swedish ICT, Kista, Sweden..
    Ohlman, Börje
    Ericsson, Stockholm, Sweden..
    Lindgren, Anders
    SICS Swedish ICT, Kista, Sweden..
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Klingsbo, Lukas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Lång, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Experiences From A Field Test Using Icn For Live Video Streaming2015In: 2015 IEEE International Conference on Multimedia & Expo Workshops (ICMEW), 2015Conference paper (Refereed)
    Abstract [en]

    Information Centric Networking (ICN) aims to evolve the Internet from a host-centric to a data-centric paradigm. In particular, it improves performance and resource efficiency in events with large crowds where many users in a local area want to generate and watch media content related to the event. In this paper, we present the design of a live video streaming system built on the NetInf ICN architecture and how the architecture was adapted to support live streaming of media content. To evaluate the feasibility and performance of the system, extensive field tests were carried out over several days during a major sports event. We show that our system streams videos successfully with low delay and communication overhead compared with existing Internet streaming services, by scalability tests using emulated clients we also show that it could support several thousands of simultaneous users.

  • 226.
    McCarthy, Tim
    et al.
    SRI Int, 333 Ravenswood Ave, Menlo Pk, CA 94025 USA.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Schäf, Martin
    SRI Int, 333 Ravenswood Ave, Menlo Pk, CA 94025 USA.
    Bixie: Finding and understanding inconsistent code2015In: Proc. 37th IEEE/ACM International Conference on Software Engineering, Piscataway, NJ: IEEE , 2015, Vol. 2, p. 645-648Conference paper (Refereed)
    Abstract [en]

    We present Bixie, a tool to detect inconsistencies in Java code. Bixie detects inconsistent code at a higher precision than previous tools and provides novel fault localization techniques to explain why code is inconsistent. We demonstrate the usefulness of Bixie on over one million lines of code, show that it can detect inconsistencies at a low false alarm rate, and fix a number of inconsistencies in popular open-source projects. Watch our Demo at http://youtu.be/QpsoUBJMxhk.

  • 227. McDermott, Roger
    et al.
    Daniels, Mats
    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.
    Perseverance measures and attainment in first year computing science students2015In: Proc. 20th Conference on Innovation and Technology in Computer Science Education, New York: ACM Press, 2015, p. 302-307Conference paper (Refereed)
  • 228. McDermott, Roger
    et al.
    Daniels, Mats
    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.
    Bass, Julian
    Lalchandani, JayPrakash
    A comparative analysis of two globally distributed group projects: A perspective from CSCW/CSCL research2015In: Proc. 45th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2015, p. 1964-1972Conference paper (Refereed)
  • 229.
    McDermott, Roger
    et al.
    Robert Gordon Univ, Sch Comp Sci & Digital Media, Aberdeen, Scotland.
    Zarb, Mark
    Robert Gordon Univ, Sch Comp Sci & Digital Media, Aberdeen, Scotland.
    Ballew, William
    Robert Gordon Univ, Sch Comp Sci & Digital Media, Aberdeen, Scotland.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Isomöttönen, Ville
    Univ Jyvaskyla, Dept Math Informat Technol, FIN-40014 Jyvaskyla, Finland.
    Phronesis, Authentic Learning and the Solution of Open-Ended Problems in Computing and Engineering Education2018In: 2018 IEEE Frontiers in Education Conference (FIE), Piscataway, NJ: IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    One of the most significant changes in Higher Education pedagogy that has occurred over the past fifty years is the idea that university students should not just be taught theoretical subject knowledge but should engage with practical aspects of their course so developing the skills and professional competences that will allow them to gain successful employment after graduation. In this paper, we relate this development to the Aristotelian notion of intellectual virtue and specifically the concept of phronesis. We discuss the way in which this idea has developed from classical beginnings to the modern educational setting, and argue that the notion of phronesis, that is, practical wisdom or prudential judgement, is crucial to a range of activities which are fundamental to science, engineering and computing education. These include an understanding of what it means to engage in authentic learning and the solution of open-ended or ill-structured problems. We also discuss the role the concept plays in describing key features of work-based learning. Finally, we make some comments concerning the relative value the education system places on different types of knowledge, and why an appropriate understanding of phronesis allows for a proper appreciation of contingent knowledge within the curriculum.

  • 230. McDermott, Roger
    et al.
    Zarb, Mark
    Daniels, Mats
    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
    Motivation, optimal experience and flow in first year computing science2016In: Proc. 21st Conference on Innovation and Technology in Computer Science Education, New York: ACM Press, 2016, p. 206-211Conference paper (Refereed)
  • 231. McDermott, Roger
    et al.
    Zarb, Mark
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Isomöttönen, Ville
    First year computing students' perceptions of authenticity in assessment2017In: Proc. 22nd Conference on Innovation and Technology in Computer Science Education, New York: ACM Press, 2017, p. 10-15Conference paper (Refereed)
  • 232. McDermott, Roger
    et al.
    Zarb, Mark
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nylén, Aletta
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Pears, Arnold
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Isomöttönen, Ville
    Caspersen, Michael
    The authenticity of 'authentic' assessment: Some faculty perceptions2017In: Proc. 47th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2017Conference paper (Refereed)
  • 233.
    McNamara, Liam
    et al.
    Swedish Inst Comp Sci, SE-16451 Stockholm, Sweden.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    SADHealth: A personal mobile sensing system for seasonal health monitoring2018In: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 12, no 1, p. 30-40Article in journal (Refereed)
    Abstract [en]

    People's health, mood, and activities are closely related to their environment and the seasons. Countries at extreme latitudes (e.g., Sweden, U.K., and Norway) experience huge variations in their light levels, impacting the population's mental state, well-being and energy levels. Advanced sensing technologies on smartphones enable nonintrusive and longitudinal monitoring of user states. The collected data make it possible for healthcare professionals and individuals to diagnose and rectify problems caused by seasonality. In this paper, we present a personal mobile sensing system that exploits technologies on smartphones to efficiently and accurately detect the light exposure, mood, and activity levels of individuals. We conducted a 2-year experiment with many users to test the functionality and performance of our system. The results show that we can obtain accurate light exposure estimation by opportunistically measuring light data on smartphones, tracking both personal light exposure and the general seasonal trends. An optional questionnaire also provides insight into the correlation between a user's mood and energy level. Our system is able to inform users how little light they are experiencing in the winter time. It can also correlate light exposure data with reduced mood and energy, and provide quantitative measurements for lifestyle changes.

  • 234.
    Melot, Nicolas
    et al.
    Linkoping Univ, Linkoping, Sweden..
    Janzén, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kessler, Christoph
    Linkoping Univ, Linkoping, Sweden..
    Mimer and Schedeval: Tools for Comparing Static Schedulers for Streaming Applications on Manycore Architectures2015In: 2015 44Th International Conference On Parallel Processing Workshops, 2015, p. 146-155Conference paper (Refereed)
    Abstract [en]

    Scheduling algorithms published in the scientific literature are often difficult to evaluate or compare due to differences between the experimental evaluations in any two papers on the topic. Very few researchers share the details about the scheduling problem instances they use in their evaluation section, the code that allows them to transform the numbers they collect into the results and graphs they show, nor the raw data produced in their experiments. Also, many scheduling algorithms published are not tested against a real processor architecture to evaluate their efficiency in a realistic setting. In this paper, we describe Mimer, a modular evaluation tool-chain for static schedulers that enables the sharing of evaluation and analysis tools employed to elaborate scheduling papers. We propose Schedeval that integrates into Mimer to evaluate static schedules of streaming applications under throughput constraints on actual target execution platforms. We evaluate the performance of Schedeval at running streaming applications on the Intel Single-Chip Cloud computer (SCC), and we demonstrate the usefulness of our tool-chain to compare existing scheduling algorithms. We conclude that Mimer and Schedeval are useful tools to study static scheduling and to observe the behavior of streaming applications when running on manycore architectures.

  • 235.
    Mobyen, Uddin Ahmed
    et al.
    MdH.
    Fotouhi, Hossein
    MdH.
    Köckemann, Uwe
    Örebro University.
    Linden, Maria
    MdH.
    Tomasic, Ivan
    MdH.
    Tsiftes, Nicolas
    RISE SICS.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Run-Time Assurance for the E-care@ home System2018Conference paper (Refereed)
  • 236.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Abdullah, Jakaria
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ekberg, Pontus
    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.
    Refinement of workload models for engine controllers by state space partitioning2017In: 29th Euromicro Conference on Real-Time Systems: ECRTS 2017, Dagstuhl, Germany: Leibniz-Zentrum für Informatik , 2017, p. 11:1-22Conference paper (Refereed)
  • 237.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Abdullah, Jakaria
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Guan, Nan
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Schedulability analysis of synchronous digraph real-time tasks2016In: Proc. 28th Euromicro Conference on Real-Time Systems, IEEE Computer Society, 2016, p. 176-186Conference paper (Refereed)
  • 238.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Abdullah, Jakaria
    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 executable semantics for synchronous task graphs: From SDRT to Ada2017In: Reliable Software Technologies — Ada-Europe 2017, Springer, 2017, Vol. 10300, p. 137-152Conference paper (Refereed)
    Abstract [en]

    We study a graph-based real-time task model in which inter-task synchronization can be specified through a rendezvous mechanism. Previously, efficient methods have been proposed for timing analysis of the corresponding task sets. In this paper, we first formally specify an operational semantics for the model. Next, we describe a method for Ada code generation for a set of such task graphs. We also specify extensions of the approach to cover a notion of broadcasting, as well as global inter-release separation time of real-time jobs. We have implemented the proposed method in a graphical tool which facilitates a model-based design and implementation of real-time software.

  • 239.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Abdullah, Jakaria
    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.
    Modeling and analysis of data flow graphs using the digraph real-time task model2016In: Reliable Software Technologies — Ada-Europe 2016, Springer, 2016, p. 15-29Conference paper (Refereed)
  • 240.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ekberg, Pontus
    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.
    On fixed-priority schedulability analysis of sporadic tasks with self-suspension2016In: Proc. 24th International Conference on Real-Time Networks and Systems, New York: ACM Press, 2016, p. 109-118Conference paper (Refereed)
  • 241.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Mousavi, Mohammad Reza
    Sound test-suites for cyber-physical systems2016In: Proc. 10th International Symposium on Theoretical Aspects of Software Engineering, IEEE Computer Society, 2016, p. 42-48Conference paper (Refereed)
  • 242.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Mousavi, Mohammad Reza
    Towards an approximate conformance relation for hybrid I/O automata2016In: Proc. 1st Workshop on Verification and Validation of Cyber-Physical Systems, Open Publishing Association , 2016, p. 53-64Conference paper (Refereed)
  • 243.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nasri, Mitra
    Xu, Yang
    Cervin, Anton
    Årzén, Karl-Erik
    On the problem of finding optimal harmonic periods2016In: Proc. 24th International Conference on Real-Time Networks and Systems, New York: ACM Press, 2016, p. 171-180Conference paper (Refereed)
  • 244.
    Mohaqeqi, Morteza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nasri, Mitra
    Max Planck Institute for Software Systems (MPI-SWS), Germany.
    Xu, Yang
    Department of Automatic Control, Lund University, Sweden.
    Cervin, Anton
    Department of Automatic Control, Lund University, Sweden.
    Årzén, Karl-Erik
    Department of Automatic Control, Lund University, Sweden.
    Optimal harmonic period assignment: complexity results and approximation algorithms2018In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 54, no 4, p. 830-860Article in journal (Refereed)
    Abstract [en]

    Harmonic periods have wide applicability in industrial real-time systems. Rate monotonic (RM) is able to schedule task sets with harmonic periods up to 100% utilization. Also, if there is no release jitter and execution time variation, RM and EDF generate the same schedule for each instance of a task. As a result, all instances of a task are interfered by the same amount of workload. This property decreases the jitters that happen during sampling and actuation of the tasks, and hence, it increases the quality of service in control systems. In this paper, we consider the problem of optimal period assignment where the periods are constrained to be harmonic and the task set is required to be feasible. We study two variants of this problem. In the first one, the objective is to maximize the system utilization, while in the second one, the goal is to minimize the total weighted sum of the periods. First, we assume that an interval is determined a priori for each task from which its period can be selected. We show that both variants of the problem are (at least) weakly NP-hard. This is shown by reducing the NP-complete number partitioning problem to the mentioned harmonic period assignment problems. Afterwards, we consider a variant of the second problem in which the periods are not restricted to a special interval. We present two approximation algorithms with polynomial-time complexity for this problem and show that the maximum relative error of these algorithms is bounded by a factor of 1.125. Our evaluations show that, on the average, results of the approximation algorithms are very close to an optimal solution.

  • 245. Nasri, Mitra
    et al.
    Mohaqeqi, Morteza
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Fohler, Gerhard
    Quantifying the effect of period ratios on schedulability of rate monotonic2016In: Proc. 24th International Conference on Real-Time Networks and Systems, New York: ACM Press, 2016, p. 161-170Conference paper (Refereed)
  • 246.
    Nemitz, Catherine E.
    et al.
    Department of Computer Science, University of North Carolina at Chapel Hill.
    Yang, Kecheng
    Department of Computer Science, University of North Carolina at Chapel Hill.
    Yang, Ming
    Department of Computer Science, University of North Carolina at Chapel Hill.
    Ekberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Anderson, James H.
    Department of Computer Science, University of North Carolina at Chapel Hill.
    Multiprocessor Real-Time Locking Protocols for Replicated Resources2016In: Proc. 28th Euromicro Conference on Real-Time Systems (ECRTS), 2016, p. 50-60Conference paper (Refereed)
    Abstract [en]

    A real-time multiprocessor synchronization problem is studied herein that has not be extensively studied before, namely, the management of replicated resources where tasks may require multiple replicas to execute. In prior work on replicated resources, k-exclusion locks have been used, but this restricts tasks to lock only one replica at a time. To motivate the need for unrestricted replica sharing, two use cases are discussed that reveal an interesting tradeoff: in one of the use cases, blocking is the dominant lock-related factor impacting schedulability, while in the other, lock/unlock overheads are. Motivated by these use cases, three replica-allocation protocols are presented. In the first two, the lock/unlock logic is very simple, yielding low overheads, but blocking is not optimal. In the third, blocking is optimal (ignoring constant factors), but additional lock/unlock overhead is incurred to properly order lock requests. Experiments are presented that examine the overhead/blocking tradeoff motivated by these protocols in some detail.

  • 247.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    On providing sink anonymity for wireless sensor networks2016In: Security and Communication Networks, ISSN 1939-0114, E-ISSN 1939-0122, Vol. 9, no 2, p. 77-86Article in journal (Refereed)
  • 248.
    Ngai, Edith C.-H.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Brandauer, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Shrestha, Amendra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Vandikas, Konstantinos
    Ericsson Res, Kista, Sweden..
    Personalized Mobile-Assisted Smart Transportation2016In: 2016 Digital Media Industry And Academic Forum (DMIAF), 2016, p. 158-160Conference paper (Refereed)
    Abstract [en]

    Digital media covers larger parts of our daily lives nowadays. Mobile services enable a better connected society where citizens can easily access public services, discover events, and obtain important information in the city. We observe the popularity of mobile car sharing applications, such as Uber and Didi Dache. Mobile social applications provide new ways of developing and optimizing public transportation. In this paper, we present a mobile platform for timetable-free traveling. It can capture the traffic demand of citizens in real-time, and support efficient planning and scheduling for vehicles on-demand. At the moment, the platform is targeted for public bus services, but it has great potential to be extended for self-driving vehicles in the future.

  • 249.
    Ngai, Edith
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Dressler, Falko
    Univ Paderborn, Dept Comp Sci, D-33102 Paderborn, Germany.
    Leung, Victor
    Univ British Columbia, Vancouver, BC V6T 1Z4, Canada.
    Li, Mo
    Nanyang Technol Univ, Sch Comp Sci & Engn, Singapore 639798, Singapore.
    Guest Editorial Special Section on Internet-of-Things for Smart Cities and Urban Informatics2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 2, p. 748-750Article in journal (Other academic)
  • 250.
    Ngai, Edith
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ohlman, Börje
    Tsudik, Gene
    Uzun, Ersin
    Wählisch, Matthias
    Wood, Christopher A.
    Can we make a cake and eat it too?: A discussion of ICN security and privacy2017In: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 47, no 1, p. 49-54Article in journal (Other academic)
2345678 201 - 250 of 351
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