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  • 251. Berglund, Åsa
    et al.
    Bjurling, Björn
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Dantas, Ramide
    Engberg, Susanne
    Giambiagi, Pablo
    RISE., Swedish ICT, SICS.
    Ohlman, Börje
    Towards goal-based autonomic networking2009Ingår i: Proceedings of the Distributed Autonomous Network Magagement Systems Workshop (DANMS 2008), November 2008, 2009, 1, , s. 5Konferensbidrag (Refereegranskat)
    Abstract [en]

    The ability to quickly deploy and efficiently manage services is critical to the telecommunications industry. Currently, services are designed and managed by different teams with expertise over a wide range of concerns, from high-level business to low level network aspects. Not only is this approach expensive in terms of time and resources, but it also has problems to scale up to new outsourcing and/or multi-vendor models, where subsystems and teams belong to different organizations. We endorse the idea, upheld among others in the autonomic computing community, that the network and system components involved in the provision of a service must be crafted to facilitate their management. Furthermore, they should help bridge the gap between network and business concerns. In this paper, we sketch an approach based on early work on the hierarchical organization of autonomic entities that possibly belong to different organizations. An autonomic entity governs over other autonomic entities by defining their goals. Thus, it is up to each autonomic entity to decide its line of actions in order to fulfill its goals, and the governing entity needs not know about the internals of its subordinates. We illustrate the approach with a simple but still rich example of a telecom service.

  • 252. Bertels, Koen
    et al.
    Boman, Magnus
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Agent-based social simulation in markets2001Ingår i: Electronic Commerce Research, ISSN 1389-5753, E-ISSN 1572-9362, Vol. 1, nr 1-2, s. 149-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that certain desired behavioural properties of agent-based models can be deterministically induced by an appropriate mathematical structure. We also point out problems related to the handling of parameters, and of the modelling of time, in agent-based models. Our purpose is to illustrate some problems of agent-based social simulations in markets, as a first step towards the more ambitious goal of providing a methodology for such simulations.

  • 253. Bertels, Koen
    et al.
    Jacques, Jean-Marie
    Boman, Magnus
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Risk and crises management in complex systems2005Ingår i: MICRO MESO MACRO: Addressing Complex Systems Couplings, World Scientific Publishing Company , 2005, 4, , s. 12s. 305-316Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Many theories attempt to explain the nature of industrial and other kinds of hazards and some of the also stress the dynamical aspects of such events. We investigate to what extent the theory of self-organized criticality contributes to our understanding of industrial hazards.

  • 254. Berti, Valentino
    et al.
    Björkman, Mats
    Norden, Lars-Åke
    Lindgren, Anders
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Datakommunikation2012 (uppl. 7)Bok (Övrigt vetenskapligt)
    Abstract [sv]

    Denna bok ger en bred introduktion till datakommunikation i allmänhet och internetteknologi i synnerhet. Vad Internet är beror helt på vem du frågar, och detsamma gäller ämnet datakommunikation. Från att ha varit ett specialämne som studenter möjligtvis läste i årskurs 3 eller 4 på datatekniska universitetsutbildningar så kan man idag lära sig grunderna i datakommunikation på flera gymnasieprogram. Författarna till denna bok har alla personlig erfarenhet av att undervisa i ämnet datakommunikation på olika nivåer. Bokens struktur möjliggör olika sätt att tillgodogöra sig materialet beroende på vad som är mest tilltalande för respektive målgrupp.

  • 255.
    Bhatti, M. K.
    et al.
    Information Technology University, Pakistan.
    Oz, I.
    Marmara University, Turkey.
    Popov, Konstantin
    RISE., Swedish ICT, SICS.
    Brorsson, M.
    KTH Royal Institute of Technology, Sweden.
    Farooq, U.
    COMSATS Institute of Information Technology, Pakistan.
    Scheduling of Parallel Tasks with Proportionate Priorities2016Ingår i: Arabian Journal for Science and Engineering, ISSN 2193-567X, Vol. 41, nr 8, s. 3279-3295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Parallel computing systems promise higher performance for computationally intensive applications. Since programmes for parallel systems consist of tasks that can be executed simultaneously, task scheduling becomes crucial for the performance of these applications. Given dependence constraints between tasks, their arbitrary sizes, and bounded resources available for execution, optimal task scheduling is considered as an NP-hard problem. Therefore, proposed scheduling algorithms are based on heuristics. This paper presents a novel list scheduling heuristic, called the Noodle heuristic. Noodle is a simple yet effective scheduling heuristic that differs from the existing list scheduling techniques in the way it assigns task priorities. The priority mechanism of Noodle maintains a proportionate fairness among all ready tasks belonging to all paths within a task graph. We conduct an extensive experimental evaluation of Noodle heuristic with task graphs taken from Standard Task Graph. Our experimental study includes results for task graphs comprising of 50, 100, and 300 tasks per graph and execution scenarios with 2-, 4-, 8-, and 16-core systems. We report results for average Schedule Length Ratio (SLR) obtained by producing variations in Communication to Computation cost Ratio. We also analyse results for different degree of parallelism and number of edges in the task graphs. Our results demonstrate that Noodle produces schedules that are within a maximum of 12 % (in worst-case) of the optimal schedule for 2-, 4-, and 8-core systems. We also compare Noodle with existing scheduling heuristics and perform comparative analysis of its performance. Noodle outperforms existing heuristics for average SLR values. 

  • 256. Biagioni, Stefania
    et al.
    Borbinha, José Luis
    Ferber, Reginald
    Hansen, Preben
    RISE., Swedish ICT, SICS.
    The ERCIM technical reference digital library1998Konferensbidrag (Refereegranskat)
  • 257.
    Billger, D
    et al.
    RISE., Swedish ICT, SICS, Imego.
    Folkow, PD
    Wave propagators for the Timoshenko beam2003Ingår i: Wave motion, ISSN 0165-2125, E-ISSN 1878-433X, Vol. 37, s. 313-32Artikel i tidskrift (Refereegranskat)
  • 258.
    Birgersson, Marcus
    et al.
    Chalmers University of Technology, Sweden; ICore Solutions, Sweden.
    Hansson, Gustav
    Chalmers University of Technology, Sweden; ICore Solutions, Sweden.
    Franke, Ulrik
    RISE., Swedish ICT, SICS, Software and Systems Engineering Laboratory.
    Data Integration Using Machine Learning2016Ingår i: 2016 IEEE 20th International Enterprise Distributed Object Computing Workshop (EDOCW), 2016, s. 313-322, artikel-id 7584357Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today, enterprise integration and cross-enterprise collaboration is becoming evermore important. The Internet of things, digitization and globalization are pushing continuous growth in the integration market. However, setting up integration systems today is still largely a manual endeavor. Most probably, future integration will need to leverage more automation in order to keep up with demand. This paper presents a first version of a system that uses tools from artificial intelligence and machine learning to ease the integration of information systems, aiming to automate parts of it. Three models are presented and evaluated for precision and recall using data from real, past, integration projects. The results show that it is possible to obtain F0.5 scores in the order of 80% for models trained on a particular kind of data, and in the order of 60%-70% for less specific models trained on a several kinds of data. Such models would be valuable enablers for integration brokers to keep up with demand, and obtain a competitive advantage. Future work includes fusing the results from the different models, and enabling continuous learning from an operational production system.

  • 259.
    Bjarnason, Elizabeth
    et al.
    Lund University, Sweden.
    Borg, Markus
    RISE., Swedish ICT, SICS, Security Lab.
    Aligning Requirements and Testing - Working Together Toward the Same Goal2017Ingår i: IEEE Software, ISSN 0740-7459, E-ISSN 1937-4194, Vol. 34, nr 1, s. 20-23, artikel-id 7819382Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The proper alignment of requirements engineering and testing (RET) can be key to software's success. Three practices can provide effective RET alignment: using test cases as requirements, harvesting trace links, and reducing distances between requirements engineers and testers. The Web extra https://youtu.be/M65ZKxfxqME is an audio podcast of author Elizabeth Bjarnason reading the the Requirements column she cowrote with Markus Borg.

  • 260.
    Bjarnason, Elizabeth
    et al.
    Lund University, Sweden.
    Borg, Markus
    RISE., Swedish ICT, SICS, Security Lab. Lund University, Sweden.
    Lindvall, Bertil
    Lund University, Sweden.
    Supervising for Independence – A Case Study of Master Science Projects in Higher Education2015Ingår i: LU:s femte högskolepedagogiska utvecklingskonferens, 2015, 12Konferensbidrag (Refereegranskat)
    Abstract [en]

    Students completing a Swedish Master's degree in engineering should have knowledge and skills to independently solve engineering issues. This autonomy should be developed and demonstrated within the M.Sc. project course. But, how can supervisors encourage independence? We have explored this in a case study through semi-structured interviews with students, supervisors and examiners of two M.Sc. projects. We investigated their view of independence, and how supervision correlates to independence. The results identify areas relevant to independence, namely supervision roles and relationships, student characteristics, M.Sc. process, and view on independence. The results confirm previous findings that students' knowledge of and motivation for the topic support independence. The supervisor's role is to guide and support through frequent peer-level discussions and to act as a discussion partner, while the student should have the main responsibility for the project. We conclude that it is important for supervisors to encourage students to take ownership of their M.Sc. projects and to design their own solutions, while providing the overall process and timelines.

  • 261. Bjarnason, Elizabeth
    et al.
    Borg, Markus
    RISE., Swedish ICT, SICS, Security Lab.
    Lindvall, Bertil
    Supervising Towards Independence2016Övrigt (Övrigt vetenskapligt)
    Abstract [en]

    Supervising a student can be compared to teaching someone to drive a car. The student is in the driver's seat while the supervisor provides structure and guidance, and can intervene in risky and unsafe situations. It is a learning process in which the student gradually gains experience and sufficient skill to obtain a driving license, and to drive without an instructor. Similarly, a student attending the MSc project course at the technical faculty of Lund University is to "develop and demonstrate knowledge and ability required to autonomously work as an engineer" (from MSc course plan). But what factors affect a MSc project, and how can we as supervisors support students in their learning process towards independence? We performed a case study of two completed MSc projects where we interviewed the student, the supervisor and the examiner for each case. In this article we present the main conclusions drawn from the cross-case analysis of this study. Details on the studied cases and the results on which these conclusions are based can be found in our previous publication of this study.

  • 262.
    Bjarnason, Elizabeth
    et al.
    Lund University, Sweden.
    Unterkalmsteiner, Michael
    Blekinge Institute of Technology, Sweden.
    Borg, Markus
    RISE., Swedish ICT, SICS, Security Lab.
    Engström, Emelie
    Lund University, Sweden.
    A Multi-Case Study of Agile Requirements Engineering and the Use of Test Cases as Requirements2016Ingår i: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 77, s. 61-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [Context] It is an enigma that agile projects can succeed "without requirements" when weak requirements engineering is a known cause for project failures. While agile development projects often manage well without extensive requirements test cases are commonly viewed as requirements and detailed requirements are documented as test cases. [Objective] We have investigated this agile practice of using test cases as requirements to understand how test cases can support the main requirements activities, and how this practice varies. [Method] We performed an iterative case study at three companies and collected data through 14 interviews and 2 focus groups. [Results] The use of test cases as requirements poses both benefits and challenges when eliciting, validating, verifying, and managing requirements, and when used as a documented agreement. We have identified five variants of the test-cases-as-requirements practice, namely de facto, behaviour-driven, story-test driven, stand-alone strict and stand-alone manual for which the application of the practice varies concerning the time frame of requirements documentation, the requirements format, the extent to which the test cases are a machine executable specification and the use of tools which provide specific support for the practice of using test cases as requirements. [Conclusions] The findings provide empirical insight into how agile development projects manage and communicate requirements. The identified variants of the practice of using test cases as requirements can be used to perform in-depth investigations into agile requirements engineering. Practitioners can use the provided recommendations as a guide in designing and improving their agile requirements practices based on project characteristics such as number of stakeholders and rate of change.

  • 263.
    Bjurling, Björn
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    A Labelled Deductive System for Reasoning about Random Experiments2006Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 264.
    Bjurling, Björn
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Contracts for Resources in Crisis Management2010Konferensbidrag (Refereegranskat)
  • 265.
    Bjurling, Björn
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Giambiagi, Pablo
    RISE., Swedish ICT, SICS.
    Contracts for controlling business processes in dynamic environments2008Konferensbidrag (Refereegranskat)
  • 266.
    Bjurling, Björn
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Hansen, Preben
    RISE., Swedish ICT, SICS.
    Contracts for Information Sharing in Collaborative Networks2010Konferensbidrag (Refereegranskat)
  • 267.
    Bjurling, Björn
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    Data Readiness for BADA: BADA main study 1, FFI/Vinnova grant 2015-006772017Rapport (Övrigt vetenskapligt)
  • 268.
    Bjurling, Björn
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Rasmusson, Lars
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Johansson, Ulf M
    Qualitative policies for bandwidth priorities in ad-hoc networks2008Ingår i: Proc. IEEE 27th Conference on Computer Communications, 2008, 1Konferensbidrag (Refereegranskat)
  • 269.
    Bjurling, Björn
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Steinert, Rebecca
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Gillblad, Daniel
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Translation of Probabilistic QoS in a Decentralized Hierarchical Setting2011Konferensbidrag (Refereegranskat)
  • 270. Björk, Staffan
    et al.
    Holmquist, Lars Erik
    RISE, Swedish ICT, SICS.
    Redström, Johan
    Bretan, Ivan
    Danielsson, Rolf
    Karlgren, Jussi
    Franzén, Kristofer
    RISE, Swedish ICT, SICS.
    WEST: A Web Browser for Small Terminals1999Konferensbidrag (Refereegranskat)
    Abstract [en]

    We describe WEST, a WEb browser for Small Terminals, that aims to solve some of the problems associated with accessing web pages on hand-held devices. Through a novel combination of text reduction and focus+context visualization, users can access web pages from a very limited display environment, since the system will provide an overview of the contents of a web page even when it is too large to be displayed in its entirety. To make maximum use of the limited resources available on a typical hand-held terminal, much of the most demanding work is done by a proxy server, allowing the terminal to concentrate on the task of providing responsive user interaction. The system makes use of some interaction concepts reminiscent of those defined in the Wireless Application Protocol (WAP), making it possible to utilize the techniques described here for WAP-compliant devices and services that may become available in the near future.

  • 271.
    Björk, Staffan
    et al.
    RISE, Swedish ICT, SICS. ICE.
    Holopainen, Jussi
    Ljungstrand, Peter
    RISE, Swedish ICT, SICS. ICE.
    Åkesson, Karl-Petter
    RISE, Swedish ICT, SICS. ICE.
    Designing Ubiquitous Computing Games - A Report from a Workshop Exploring Ubiquitous Computing Entertainment2002Ingår i: Personal and Ubiquitous Computing, ISSN 1617-4909, E-ISSN 1617-4917, Vol. 6, s. 443-458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report from a Research Atelier that explored how ubiquitous computing could be applied to fun and entertainment. The Atelier lasted for five days, starting with two days of scenario development and brainstorming activities. This led to three fairly concrete – though very different – game ideas. The background and motivation for the Atelier is described, as well as the method used and the games developed.

  • 272.
    Blom, Rolf
    et al.
    RISE., Swedish ICT, SICS.
    Schwarz, Oliver
    RISE., Swedish ICT, SICS, Security Lab.
    High Assurance Security Products on COTS Platforms2015Ingår i: ERCIM News, ISSN 0926-4981, E-ISSN 1564-0094, nr 102, s. 39-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With commodity operating systems failing to establish unbreakable isolation of processes, there is a need for stronger separation mechanisms. A recently launched open source project aims at applying virtualization to achieve such isolation on the widespread embedded ARM architectures. Strong assurance is established by formal verification and common criteria certification. Coexisting guest systems are able to run unmodified on the multicore platform, in a resource and cost efficient manner. The solution is rounded anchored in a secure boot process.

  • 273. Boano, Carlo Alberto
    et al.
    Brown, James
    He, Zhitao
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Roedig, Utz
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Low-power radio communication in industrial outdoor deployments: the impact of weather conditions and ATEX-compliance2009Konferensbidrag (Refereegranskat)
  • 274. Boano, Carlo Alberto
    et al.
    He, Zhitao
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Li, Yafei
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Zuniga, Marco
    Willig, Andreas
    Controllable radio interference for experimental and testing purposes in wireless sensor networks2009Konferensbidrag (Refereegranskat)
  • 275. Boano, Carlo Alberto
    et al.
    Römer, Kay
    He, Zhitao
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Zuniga, Marco
    Willig, Andreas
    Demo Abstract: Generation of Controllable Radio Interference for Protocol Testing in Wireless Sensor Networks2009Konferensbidrag (Refereegranskat)
  • 276.
    Boano, Carlo Alberto
    et al.
    Graz University of Technology, Austria.
    Römer, Kay
    Graz University of Technology, Austria.
    Tsiftes, Nicolas
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Mitigating the Adverse Effects of Temperature on Low-Power Wireless Protocols2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Research and industrial installations have shown that the on-board temperature of wireless sensor nodes deployed outdoors can experience high fluctuations over time with a large variability across the network. These variations can have a strong impact on the efficiency of low-power radios and can significantly affect the operation of communication protocols, often compromising network connectivity. In this paper, we show the adverse effects of temperature on communication protocols and propose techniques to increase their resilience. First, we experimentally show that fluctuations of the on-board temperature of sensor nodes reduce the efficiency of data link layer protocols, leading to a substantial decrease in packet reception rate and to a considerable increase in energy consumption. Second, we investigate the reasons for such performance degradation, and show that high on-board temperatures reduce the effectiveness of clear channel assessment, compromising the ability of a node to avoid collisions and to successfully wake-up from low-power mode. After modelling the behaviour of radio transceivers as a function of temperature, we propose two mechanisms to dynamically adapt the clear channel assessment threshold to temperature changes, thus making data link layer protocols temperature-aware. An extensive experimental evaluation shows that our approaches considerably increase the performance of a network in the presence of temperature variations commonly found in real-world outdoor deployments, with up to 42% lower radio duty-cycle and 87% higher packet reception rate.

  • 277. Boano, Carlo Alberto
    et al.
    Römer, Kay
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Zuniga, Marco
    Poster Abstract: Agreement for Wireless Sensor Networks under External Interference2012Konferensbidrag (Refereegranskat)
  • 278. Boano, Carlo Alberto
    et al.
    Römer, Kay
    Österlind, Fredrik
    RISE., Swedish ICT, SICS.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Demo Abstract: Realistic Simulation of Radio Interference in COOJA2011Konferensbidrag (Refereegranskat)
  • 279.
    Boano, Carlo Alberto
    et al.
    RISE., Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Brown, James
    Roedig, Utz
    The Impact of Temperature on Outdoor Industrial Sensornet Applications2010Ingår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 6, s. 451-459Artikel i tidskrift (Refereegranskat)
  • 280. Boano, Carlo Alberto
    et al.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Dunkels, Adam
    RISE., Swedish ICT, SICS.
    Österlind, Fredrik
    RISE., Swedish ICT, SICS.
    Tsiftes, Nicolas
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Mottola, Luca
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Suarez, Pablo
    Poster Abstract: Exploiting the LQI Variance for Rapid Channel Quality Assessment2009Konferensbidrag (Refereegranskat)
  • 281. Boano, Carlo Alberto
    et al.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Noda, Claro
    Römer, Kay
    Zuniga, Marco
    JamLab: Augmenting Sensornet Testbeds with Realistic and Controlled Interference Generation2011Konferensbidrag (Refereegranskat)
  • 282. Boano, Carlo Alberto
    et al.
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Tsiftes, Nicolas
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Mottola, Luca
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Römer, Kay
    Zuniga, Marco
    Making Sensornet MAC Protocols Robust Against Interference2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Radio interference may lead to packet losses, thus negatively affecting the performance of sensornet applications. In this paper, we experimentally assess the impact of external interference on state-of-the-art sensornet MAC protocols. Our experiments illustrate that specific features of existing protocols, e.g., hand-shaking schemes preceding the actual data transmission, play a critical role in this setting. We leverage these results by identifying mechanisms to improve the robustness of existing MAC protocols under interference. These mechanisms include the use of multiple hand-shaking attempts coupled with packet trains and suitable congestion backoff schemes to better tolerate interference. We embed these mechanisms within an existing X-MAC implementation and show that they considerably improve the packet delivery rate while keeping the power consumption at a moderate level.

  • 283. Boano, Carlo Alberto
    et al.
    Wennerström, Hjalmar
    Zuniga, Marco
    Brown, James
    Keppitiyagama, Chamath
    RISE., Swedish ICT, SICS.
    Oppermann, Felix
    Roedig, Utz
    Norden, Lars-Åke
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Römer, Kay
    Hot Packets: A Systematic Evaluation of the Effect of Temperature on Low Power Wireless Transceivers2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Temperature is known to have a significant effect on the performance of radio transceivers: the higher the temper- ature, the lower the quality of links. Analysing this effect is particularly important in sensor networks because several applications are exposed to harsh environmental conditions. Daily or hourly changes in temperature can dramatically reduce the throughput, increase the delay, or even lead to network partitions. A few studies have quantified the impact of temperature on low-power wireless links, but only for a limited temperature range and on a single radio transceiver. Building on top of these preliminary observations, we de- sign a low-cost experimental infrastructure to vary the on- board temperature of sensor nodes in a repeatable fashion, and we study systematically the impact of temperature on various sensornet platforms. We show that temperature af- fects transmitting and receiving nodes differently, and that all platforms follow a similar trend that can be captured in a simple first-order model. This work represents an ini- tial stepping stone aimed at predicting the performance of a network considering the particular temperature profile of a given environment.

  • 284. Boano, Carlo Alberto
    et al.
    Zuniga, Marco
    Römer, Kay
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    JAG: Reliable and Predictable Wireless Agreement under External Radio Interference2012Konferensbidrag (Refereegranskat)
  • 285. Boano, Carlo Alberto
    et al.
    Zuniga, Marco
    Voigt, Thiemo
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Willig, Andreas
    Römer, Kay
    The Triangle Metric: Fast Link Quality Estimation for Mobile Wireless Sensor Networks (Invited Paper)2010Konferensbidrag (Refereegranskat)
  • 286.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Dahms, Florian
    Flier, Holger
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Optimal Freight Train Classification using Column Generation2012Konferensbidrag (Refereegranskat)
  • 287.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Doganay, Kivanc
    RISE., Swedish ICT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Scheduling Gas Turbine Maintenance Based on Condition Data2009Ingår i: Proceedings of the 21st Innovative Applications of Artificial Intelligence Conference, 2009, 6Konferensbidrag (Refereegranskat)
  • 288.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Doganay, Kivanc
    RISE., Swedish ICT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Steinert, Rebecca
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Wärja, Mathias
    A Tool for Gas Turbine Maintenance Scheduling2009Ingår i: Proceedings of the Twenty-First Conference on Innovative Applications of Artificial Intelligence (IAAI'09), IEEE Computer Society , 2009, 20Konferensbidrag (Refereegranskat)
    Abstract [en]

    We describe the implementation and deployment of a software decision support tool for the maintenance planning of gas turbines. The tool is used to plan the maintenance for turbines manufactured and maintained by Siemens Industrial Turbomachinery AB (SIT AB) with the goal to reduce the direct maintenance costs and the often very costly production losses during maintenance downtime. The optimization problem is formally defined, and we argue that feasibility in it is NP-complete. We outline a heuristic algorithm that can quickly solve the problem for practical purposes, and validate the approach on a real-world scenario based on an oil production facility. We also compare the performance of our algorithm with results from using mixed integer linear programming, and discuss the deployment of the application. The experimental results indicate that downtime reductions up to 65% can be achieved, compared to traditional preventive maintenance. In addition, using our tool is expected to improve availability with up to 1% and reduce the number of planned maintenance days with 12%. Compared to a mixed integer programming approach, our algorithm not optimal, but is orders of magnitude faster and produces results which are useful in practice. Our test results and SIT AB’s estimates based on operational use both indicate that significant savings can be achieved by using our software tool, compared to maintenance plans with fixed intervals.

  • 289.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Doganay, Kivanc
    RISE., Swedish ICT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Steinert, Rebecca
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Wärja, Mathias
    Searching for Gas Turbine Maintenance Schedules2010Ingår i: AI Magazine, Vol. 31, nr 1, s. 21-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Preventive maintenance schedules occurring in industry are often suboptimal with regard to maintenance coal-location, loss-of-production costs and availability. We describe the implementation and deployment of a software decision support tool for the maintenance planning of gas turbines, with the goal of reducing the direct maintenance costs and the often costly production losses during maintenance downtime. The optimization problem is formally defined, and we argue that the feasibility version is NP-complete. We outline a heuristic algorithm that can quickly solve the problem for practical purposes and validate the approach on a real-world scenario based on an oil production facility. We also compare the performance of our algorithm with results from using integer programming, and discuss the deployment of the application. The experimental results indicate that downtime reductions up to 65% can be achieved, compared to traditional preventive maintenance. In addition, the use of our tool is expected to improve availability with up to 1% and reduce the number of planned maintenance days by 12%. Compared to a integer programming approach, our algorithm is not optimal, but is much faster and produces results which are useful in practice. Our test results and SIT AB’s estimates based< on operational use both indicate that significant savings can be achieved by using our software tool, compared to maintenance plans with fixed intervals.

  • 290.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ekman, Jan
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Holst, Anders
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    The opportunistic replacement and inspection problem for components with a stochastic life time2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The problem of finding efficient maintenance and inspection schemes in the case of components with a stochastic life time is studied and a mixed integer programming solution is proposed. The problem is compared with the two simpler problems of which the studied problem is a generalisation: The opportunistic replacement problem, assuming components with a deterministic life time and The opportunistic replacement problem for components with a stochastic life time, for maintenance schemes without inspections.

  • 291.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Forsgren, Malin
    RISE - Research Institutes of Sweden, ICT, SICS.
    Holst, Anders
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Levin, Björn
    RISE - Research Institutes of Sweden, ICT, SICS.
    Aronsson, Martin
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Steinert, Rebecca
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Reducing vehicle maintenance using condition monitoring and dynamic planning2008Ingår i: Proceedings of the 4th IET International Conference on Railway Condition Monitoring (RCM'08), 2008, 1Konferensbidrag (Refereegranskat)
  • 292.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Optimerad rangering: slutsatser och resultat från projektet RANPLAN2013Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Sammanfattning Rapporten innehåller kortfattade slutsatser och resultat från en studie genomförd i projektet RANPLAN, som har utförts av SICS Swedish ICT AB på uppdrag av Trafikverket under åren 2010-2013. Fokus är på Hallsbergs rangerbangård, men resultaten är tillämpbara även på andra rangerbangårdar med vall. Datorkörningar visar att blanddragen kan öka kapaciteten på rangerbangårdar väsentligt, mätt i antalet samtidiga tåg som kan hanteras, till en kostnad av en ökad mängd vagnsrörelser. I en jämförande datorstudie av simulering och optimering framgick också att de optimala planerna var betydligt effektivare, mätt i antalet vagnsrörelser, än de simulerade planerna. Resultaten pekar tydligt på att datorstödd optimering av planeringsprocessen för rangerbangårdar både är praktiskt möjligt och kan ge stora effektivitetsvinster.

  • 293.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Dahms, Florian
    RWTH Aachen University, Germany.
    Mihalák, Matúš
    ETH Zurich, Switzerland.
    Flier, Holger
    ETH Zurich, Switzerland.
    Optimization Methods for Multistage Freight Train Formation2015Ingår i: Transportation Science, ISSN 0041-1655, E-ISSN 1526-5447, Vol. 50, nr 3, s. 823-840Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper considers mathematical optimization for the multistage train formation problem, which at the core is the allocation of classification yard formation tracks to outbound freight trains, subject to realistic constraints on train scheduling, arrival and departure timeliness, and track capacity. The problem formulation allows the temporary storage of freight cars on a dedicated mixed-usage track. This real-world practice increases the capacity of the yard, measured in the number of simultaneous trains that can be successfully handled. Two optimization models are proposed and evaluated for the multistage train formation problem. The first one is a column-based integer programming model, which is solved using branch and price. The second model is a simplified reformulation of the first model as an arc-indexed integer linear program, which has the same linear programming relaxation as the first model. Both models are adapted for rolling horizon planning and evaluated on a five-month historical data set from the largest freight yard in Scandinavia. From this data set, 784 instances of different types and lengths, spanning from two to five days, were created. In contrast to earlier approaches, all instances could be solved to optimality using the two models. In the experiments, the arc-indexed model proved optimality on average twice as fast as the column-based model for the independent instances, and three times faster for the rolling horizon instances. For the arc-indexed model, the average solution time for a reasonably sized planning horizon of three days was 16 seconds. Regardless of size, no instance took longer than eight minutes to be solved. The results indicate that optimization approaches are suitable alternatives for scheduling and track allocation at classification yards.

  • 294.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Dahms, Florian
    Mihalák, Matúš
    Flier, Holger
    Optimized shunting with mixed-usage tracks2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We consider the planning of railway freight classification at hump yards, where the problem involves the formation of departing freight train blocks from arriving trains subject to scheduling and capacity constraints. The hump yard layout considered consists of arrival tracks of sufficient length at an arrival yard, a hump, classification tracks of non-uniform and possibly non-sufficient length at a classification yard, and departure tracks of sufficient length. To increase yard capacity, freight cars arriving early can be stored temporarily on specific mixed-usage tracks. The entire hump yard planning process is covered in this paper, and heuristics for arrival and departure track assignment, as well as hump scheduling, have been included to provide the neccessary input data. However, the central problem considered is the classification track allocation problem. This problem has previously been modeled using direct mixed integer programming models, but this approach did not yield lower bounds of sufficient quality to prove optimality. Later attempts focused on a column generation approach based on branch-and-price that could solve problem instances of industrial size. Building upon the column generation approach we introduce a direct arc-based integer programming model, where the arcs are precedence relations between blocks on the same classification track. Further, the most promising models are adapted for rolling-horizon planning. We evaluate the methods on historical data from the Hallsberg shunting yard in Sweden. The results show that the new arc-based model performs as well as the column generation approach. It returns an optimal schedule within the execution time limit for all instances but from one, and executes as fast as the column generation approach. Further, the short execution times of the column generation approach and the arc-indexed model make them suitable for rolling-horizon planning, while the direct mixed integer program proved to be too slow for this. Extended analysis of the results shows that mixing was only required if the maximum number of concurrent trains on the classification yard exceeds 29 (there are 32 available tracks), and that after this point the number of extra car roll-ins increases heavily.

  • 295.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Khoshniyat, Fahimeh
    Evaluation of planning policies for marshalling track allocation using simulation2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Planning the operational procedures in a railway marshalling yard is a complex problem. When a train arrives at a marshalling yard, it is uncoupled on an arrival yard and then its cars are rolled to a classification yard. All cars should eventually be rolled to the classification track that has been assigned to the train they’re supposed to depart with. However, there is normally not enough capacity to compound all trains at once. In Sweden, cars arriving before a track has been assigned to their train can be stored on separate tracks called mixing tracks. All cars on mixing tracks will be pulled back to the arrival yard, and then rolled to the classification yard again to allow for reclassification. Today all procedures are planned by experienced dispatchers, but there are no documented strategies or guidelines for efficient manual planning. The aim of this paper is to examine operational planning strategies that could help dispatchers find a feasible marshalling schedule that minimizes unnecessary mixing. In order to achieve this goal, two different online planning strategies have been tested using deterministic and stochastic simulation. The Hallsberg marshalling yard was used as a case study, and was simulated for the time period between December 2010 and May 2011. The first tested strategy simply assigns tracks to trains on a first come-first served basis, while the second strategy uses time limits to determine when tracks should be assigned to departing trains. The online planning algorithms have been compared with an offline optimized track allocation. The results from both the deterministic and the stochastic simulation show that the optimized allocation is better than all online strategies and that the second strategy with a time limit of 32 hours is the best online method.

  • 296.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Gestrelius, Sara
    RISE., Swedish ICT, SICS.
    Khoshniyat, Fahimeh
    Simulation of planning strategies for track allocation at marshalling yards2013Konferensbidrag (Refereegranskat)
  • 297.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Holst, Anders
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ekman, Jan
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Sellin, Ola
    Lindström, Björn
    Larsen, Stefan
    Statistical Anomaly Detection for Train Fleets2012Konferensbidrag (Refereegranskat)
  • 298.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Kocjan, Waldemar
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Designing Global Scheduling Constraints for Local Search: A Generic Approach2002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this work we present a novel method to automate the computation of global constraints cost for local search. The method is based on the representation of a global constraints as graph properties on a binary constraint network. This formulation simplifies the implementation of global constraints in local search, and provides a cost that can be readily compared to one obtained for subproblems using binary constraints exclusively. The cost obtained can be efficiently updated during the search using incremental methods. The representation of a global constraint as outlined above can also be used for generation of suitable neighborhoods for the constraint. This is done using simple repair functions applied on the elementary constraints in the global constraint graph. We show the usability of our approach by presenting formulations of global constraints in non-overlapping and cumulative scheduling.

  • 299.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Aronsson, Martin
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Forsgren, Malin
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ansatser för flexibel planering och schemaläggning av tågtidtabeller2006Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Rapporten beskriver möjliga ansatser för att lösa det abstraherade tidtabellproblemet som bl.a. diskuteras i rapporten "Leveranstågplan: Specifikation och åtagande" (DDTP Arbetsdokument SICS-DDTP-002). Till grund för de olika ansatserna ligger en modell med avgångstider och hålltider (dvs. väntetider och i viss mån traverseringstider) som tillåts variera inom vissa tidsintervall. Huvudidén är att arbeta med förenklade kapacitetsvillkor på bana och bangård, för att på ett effektivt sätt kunna beräkna tidtabeller på en nivå som tillåter anpassning av tidtabellen till det gällande transportbehovet och den rådande trafiksituationen.

  • 300.
    Bohlin, Markus
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Lu, Yue
    Kraft, Johan
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Nolte, Thomas
    Best-Effort Simulation-Based Timing Analysis using Hill-Climbing with Random Restarts2009Ingår i: Proceedings of the 15th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, IEEE Computer Society , 2009, 6Konferensbidrag (Refereegranskat)
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