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  • 101.
    Bhat, Anand
    et al.
    Electr. & Comput. Eng., Carnegie Mellon Univ., Pittsburgh, PA, USA.
    Samii, Soheil
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. General Motors, USA.
    Rajkumar, Ragunathan
    Electr. & Comput. Eng., Carnegie Mellon Univ., Pittsburgh, PA, USA.
    Recovery Time Considerations in Real-Time Systems Employing Software Fault Tolerance2018In: 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)}, 2018Conference paper (Refereed)
    Abstract [en]

    Safety-critical real-time systems like modern automobiles with advanced driving-assist features must employ redundancy for crucial software tasks to tolerate permanent crash faults. This redundancy can be achieved by using techniques like active replication or the primary-backup approach. In such systems, the recovery time which is the amount of time it takes for a redundant task to take over execution on the failure of a primary task becomes a very important design parameter. The recovery time for a given task depends on various factors like task allocation, primary and redundant task priorities, system load and the scheduling policy. Each task can also have a different recovery time requirement (RTR). For example, in automobiles with automated driving features, safety-critical tasks like perception and steering control have strict RTRs, whereas such requirements are more relaxed in the case of tasks like heating control and mission planning. In this paper, we analyze the recovery time for software tasks in a real-time system employing Rate-Monotonic Scheduling (RMS). We derive bounds on the recovery times for different redundant task options and propose techniques to determine the redundant-task type for a task to satisfy its RTR. We also address the fault-tolerant task allocation problem, with the additional constraint of satisfying the RTR of each task in the system. Given that the problem of assigning tasks to processors is a well-known NP-hard bin-packing problem we propose computationally-efficient heuristics to find a feasible allocation of tasks and their redundant copies. We also apply the simulated annealing method to the fault-tolerant task allocation problem with RTR constraints and compare against our heuristics.

  • 102.
    Bianzino, Aruna Prem
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Cooperative proxies: Optimally trading energy and quality of service in mobile devices2014In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 75, no Part A, p. 297-312Article in journal (Refereed)
    Abstract [en]

    This work studies the energy and quality of service (QoS) trade-off in the context of mobile devices with two communication interfaces (a high energy and a low energy interface). We propose an optimisation scheme during underload scenarios where proxy groups are dynamically formed exploiting both interfaces. The scheme integrates a reward mechanism that compensates a proxy while carrying other group members’ traffic, and deals with churn (joining and leaving of nodes) in a cell area. For traffic flows that approximate knowledge about current services we show that the scheme can achieve energy savings of 60% for all mobile nodes as whole. We also demonstrate the impact on disruption-sensitive flows as a function of the traffic mix, and that the use of rewards for selection of proxies is a fair mechanism in the long term.

  • 103.
    Bianzino, Aruna Prem
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Rougier, Jean-Louis
    Telecom ParisTech.
    Chaudet, Claude
    Telecom ParisTech.
    Rossi, Dario
    Telecom ParisTech.
    The Green-Game: Accounting for Device Criticality in Resource Consolidation for Backbone IP Networks2014In: Strategic Behavior and the Environment, ISSN 1944-012X, E-ISSN 1944-0138, Vol. 4, no 2, p. 131-153Article in journal (Refereed)
    Abstract [en]

    The reduction of the energy expenditure of communication networks rep- resents a key issue for the research community. A promising technique acting in this direction is known as “resource consolidation”. It consists in concen- trating the workload of an infrastructure on a reduced set of devices, while switching off the others. Deciding on the set of devices that can be safely switched off requires an accurate evaluation of their criticality in the net- work. We define here a measure of criticality that takes into account the network topology, but also the traffic, and different possible network config- urations. We model the scenario as a coalitional game. Shapley value ranking is efficiently used to drive the resource consolidation procedure. Numerical results, on real network scenarios, confirm the robustness and relevance of the proposed index in measuring criticality, yielding a good tradeoff between energy efficiency and network robustness, and outperforming other classical indexes. 

  • 104.
    Biciusca, Tonino
    et al.
    Academic Romana, Romania; West University of Timisoara, Romania.
    Horga, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Academic Romana, Romania.
    Sofonea, Victor
    Academic Romana, Romania.
    Simulation of liquid-vapour phase separation on GPUs using Lattice Boltzmann models with off-lattice velocity sets2015In: Comptes rendus. Mecanique, ISSN 1631-0721, E-ISSN 1873-7234, Vol. 343, no 10-11, p. 580-588Article in journal (Refereed)
    Abstract [en]

    We use a two-dimensional Lattice Boltzmann model to investigate the liquid-vapour phase separation in an isothermal van der Waals fluid. The model is based on the expansion of the distribution function up to the third order in terms of Hermite polynomials. In two dimensions, this model is an off-lattice one and has 16 velocities. The Corner Transport Upwind Scheme is used to evolve the corresponding distribution functions on a square lattice. The resulting code allows one to follow the liquid-vapour phase separation on lattices up to 4096 x 4096 nodes using a Tesla M2090 Graphics Processing Unit. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

  • 105.
    Billman, Johan
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Hellström, Victor
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Abusing Keep-Alive Forwarding to flood a VANET: When safety messages become a safety risk2016Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Cooperative Intelligent Transport Systems (C-ITS) enable vehicles to cooperate with each other and can be used to increase traffic safety and traffic flow. There are several standard initiatives for C-ITS, such as WAVE in the US, ARIB in Japan and ETSI ITS G5 in Europe.

    Decentralized Environment Notification Message (DENM) is a kind of message within ETSI TC ITS. DENMs are event-triggered, multi-hop notification messages that can be for- warded using Keep-Alive Forwarding (KAF).

    In this thesis, KAF is used to flood the network with DENMs sent from a single attack- ing vehicle. Using the simulation tools SUMO, OmNet++ and Veins, a highway scenario is studied. In the scenario, a vehicle sends out a DENM into a network that is being attacked by one other vehicle. Due to how KAF allows messages to be forwarded the other vehicles help flood the network. The results clearly indicate that KAF can be abused to create a Denial of Service (DoS) attack. After just a few seconds, the attack has introduced large de- lays and very high packet loss. The delay to receive a DENM is increased by several orders of magnitude and the packet loss reach unacceptable levels. By getting DENMs several seconds after they are needed, or by not getting them at all, could lead to traffic hazards. 

  • 106.
    Birksjö, Marcus
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Event-based diagnostics in heavy-duty vehicles2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The integration of small computer units in vehicles has made new and more complex functionalitypossible within the vehicle industry. To verify that the functionality is working and to troubleshoot it when a fault is detected requires a set of diagnostic services. Due to the increasing complexity of the functionality the diagnostic services need to extract more data to be able to diagnose the functionality. This causes an increased network load which soon threatens to become too high for some of the current networks. New ways to diagnose functionality in vehicles are therefore needed.

    The aim of this thesis was to investigate the need for an event-based service within the domain of vehicle diagnostics as well as presenting a recommendation of how sucha service should be designed. The thesis also aimed at eliciting obstacles and pitfalls connected with the implementation of the service in the current software architecture in heavy duty vehicles.

    An industrial case study was performed at the Swedish company Scania to elicit the potential need, problems and limitations with an event-based service for vehicle diagnostics. First a set of experts representing different domains within vehicle diagnostics were interviewed to investigate the need and potential of the service for different use cases. Requirements were elicited and compared with the service ResponseOnEvent defined inthe ISO standard 14229-1:2013. A decision was then made to diverge from the standard inorder to increase the number of fulfilled requirements and flexibility of the service. A new proprietary service was therefore created and evaluated through a proof of concept wherea prototype of the service was implemented in one client and one server control unit. A final recommendation was then given suggesting how to implement an event-based service and how to solve the found problems.

    The elicitation of the need for an event-based service resulted a confirmed need in three different domains and 23 different requirements which the service ResponseOnEvent was compared against. The service failed to meet all the requirements and therefore a proprietary service was designed. The prototype implementation of the proprietary service showed on multiple difficulties connected to the realization of an event-based service in the current architecture. One of the biggest was the fact that diagnostic services was assumed to always have a one-to-one relation between request and response, which an event-based service would not have. Different workarounds were discovered and assessed. Another problem was the linking between an event triggered response message and the triggercondition. It was concluded that some restrictions would have to be made to facilitatethe process of linking a response to its trigger condition. Non-determinism was another problem, since there were no guarantees that an event would not trigger too often causinga bus overload. In the final recommendation there are suggestions of how to solve these problems and some suggested areas for further research.

    The thesis confirms the need for a new way to diagnose vehicle functionality due to their increased complexity and the limited bandwidth of some of today’s in-vehicle networks. The event-based service ResponseOnEvent offers a good alternative but might lacksome key functionality. Therefore it might be valuable to consider a proprietary service instead. Due to its nature, an event-based service might require a restructuring of thesystem architecture and limitations in the hardware might limit the usability and flexibilityof the service.

    Keywords: event-based service, Response on Event, ECU, Vehicle Diagnostics, UDS,KWP.

  • 107.
    Bjelkenstedt, Alf
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Web-Based Drawing Tool in GWT with Usability Testing and Usability Evaluation2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    On behalf of Inspectera HK AB in Norrköping a web-based drawing tool has been developed in Java, mainlywith the library Google Web Toolkit (GWT). The purpose of this tool is to facilitate both the staff's at Inspecteraand their client's work with different types of drawings such as blueprints for pest control, fire protection andespecially drawings of the company's e-service of self-checks. Besides developing the drawing tool usabilitytesting and a usability evaluation has been performed.

  • 108.
    Blom, Lillemor
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Impact of light on augmented reality: Evaluating how different light conditions affect the performance of Microsoft HoloLens 3D applications2018Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Microsoft HoloLens is a headmounted augmented reality system providing users the ability to experience three-dimensional virtual content. This could be used in applications aimed at industry where users could use augmented reality to easily access information and receive instructions. For this to be suitable for industry, the system must be robust. One property of robustness was chosen for this thesis: system performance in conditions of different levels of light. A prototype implementing a use case for future industry was developed, as well as two additional smaller applications to facilitate experiments. Experiments were performed to investigate how different light levels affects the functionality in a 3D holographic application running on HoloLens and how the visibility of virtual content was affected in conditions with bright and heterogeneous backgrounds. The results showed that the functionality of the holographic application was not significantly affected except in very dark conditions, and that bright and messy backgrounds pose a problem to hologram visibility.

  • 109.
    Blomquist, Linus
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Engström, Hampus
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    GPU based IP forwarding2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was about investigating if it is feasible to implement an IP-forwarding data plane on a GPU. A GPU is energy efficient compared to other more powerful processors on the market today and should in theory be efficient to use for routing purposes. An IP-forwarding data plane consist of several things where we focused on some of the concepts. We have implemented IP-forwarding lookup operations, packet header changes, prioritization between different packets and a traffic shaper to restrict the packet throughput. To test these concepts we implemented a prototype, on a Tegra platform, in CUDA and evaluated its performance. We are able to forward 28 Mpackets/second with a best case latency of 27 µS given local simulated packets. The conclusions we can draw of this thesis work is that using a GPU for IP-forwarding purposes seems like an energy efficient solution compared to other routers on the market today. In the thesis we also tried the concept of only launching the GPU kernel once and let it be infinite which shows promising results for future work.

  • 110.
    Boberg, Hannes
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Designing and comparing access control systems2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Access control systems are an important concept in the area of computer security. In this master thesis different solutions are analyzed. The focus is on a tool called DW Access. DW Access is developed by Pdb Datasystem AB. A comparison was done that showed that DW Access is lacking some important functionality. After the comparison a base model for an access control system was designed. The new design includes concepts like relation- ships, replacements and time limited access. It also works for generic subjects and objects in the system. This design was later partly implemented in DW Access.

    The conclusions from this thesis work is that DW Access is a unique tool and there is a market for the application or similar applications. The new functionality was one step forward and the evaluation showed that the potential users liked the new concepts. But it is a very open area because of very unique requirements on the market.

  • 111.
    Bodirsky, Manuel
    et al.
    Technical University of Dresden, Germany.
    Chen, Hubie
    University of Basque Country, Spain; Basque Fdn Science, Spain.
    Wrona, Michal
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Tractability of quantified temporal constraints to the max2014In: International journal of algebra and computation, ISSN 0218-1967, Vol. 24, no 8, p. 1141-1156Article in journal (Refereed)
    Abstract [en]

    A temporal constraint language is a set of relations that are first-order definable over (Q; less than). We show that several temporal constraint languages whose constraint satisfaction problem is maximally tractable are also maximally tractable for the more expressive quantified constraint satisfaction problem. These constraint languages are defined in terms of preservation under certain binary polymorphisms. We also present syntactic characterizations of the relations in these languages.

  • 112.
    Bodirsky, Manuel
    et al.
    Technical University of Dresden, Germany.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    A Model-Theoretic View on Qualitative Constraint Reasoning2017In: The journal of artificial intelligence research, ISSN 1076-9757, E-ISSN 1943-5037, Vol. 58, p. 339-385Article in journal (Refereed)
    Abstract [en]

    Qualitative reasoning formalisms are an active research topic in artificial intelligence. In this survey we present a model-theoretic perspective on qualitative constraint reasoning and explain some of the basic concepts and results in an accessible way. In particular, we discuss the significance of omega-categoricity for qualitative reasoning, of primitive positive interpretations for complexity analysis, and of Datalog as a unifying language for describing local consistency algorithms.

  • 113.
    Bodirsky, Manuel
    et al.
    Technical University of Dresden, Germany.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pham Trung, Van
    Vienna University of Technology, Austria.
    THE REDUCTS OF THE HOMOGENEOUS BINARY BRANCHING C-RELATION2016In: Journal of Symbolic Logic (JSL), ISSN 0022-4812, E-ISSN 1943-5886, Vol. 81, no 4, p. 1255-1297Article in journal (Refereed)
    Abstract [en]

    Let (L; C) be the (up to isomorphism unique) countable homogeneous structure carrying a binary branching C-relation. We study the reducts of (L; C), i.e., the structures with domain L that are first-order definable in (L; C). We show that up to existential interdefinability, there are finitely many such reducts. This implies that there are finitely many reducts up to first-order interdefinability, thus confirming a conjecture of Simon Thomas for the special case of (L; C). We also study the endomorphism monoids of such reducts and show that they fall into four categories.

  • 114. Bodirsky, Manuel
    et al.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Van Pham, Trung
    The Complexity of Phylogeny Constraint Satisfaction2016Conference paper (Refereed)
  • 115.
    Bodirsky, Manuel
    et al.
    Technical University of Dresden, Germany.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Van Pham, Trung
    Vietnam Academy of Science and Technology, Hanoi, Vietnam.
    The Complexity of Phylogeny Constraint Satisfaction Problems2017In: ACM Transactions on Computational Logic, ISSN 1529-3785, E-ISSN 1557-945X, Vol. 18, no 3, article id 23Article in journal (Refereed)
    Abstract [en]

    We systematically study the computational complexity of a broad class of computational problems in phylogenetic reconstruction. The class contains, for example, the rooted triple consistency problem, forbidden subtree problems, the quartet consistency problem, and many other problems studied in the bioinformatics literature. The studied problems can be described as constraint satisfaction problems, where the constraints have a first-order definition over the rooted triple relation. We show that every such phylogeny problem can be solved in polynomial time or is NP-complete. On the algorithmic side, we generalize a well-known polynomial-time algorithm of Aho, Sagiv, Szymanski, and Ullman for the rooted triple consistency problem. Our algorithm repeatedly solves linear equation systems to construct a solution in polynomial time. We then show that every phylogeny problem that cannot be solved by our algorithm is NP-complete. Our classification establishes a dichotomy for a large class of infinite structures that we believe is of independent interest in universal algebra, model theory, and topology. The proof of our main result combines results and techniques from various research areas: a recent classification of the model-complete cores of the reducts of the homogeneous binary branching C-relation, Leebs Ramsey theorem for rooted trees, and universal algebra.

  • 116.
    Bodirsky, Manuel
    et al.
    Ecole Polytechnique, Palaiseau, France.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    von Oertzen, Timo
    Max-Planck-Institute for Human Development, Berlin, Germany and University of Virginia, Charlottesville, USA..
    Essential Convexity and Complexity of Semi-algebraic Constraints2012In: Logical Methods in Computer Science, ISSN 1860-5974, E-ISSN 1860-5974, Vol. 8, no 4Article in journal (Refereed)
    Abstract [en]

    Let \Gamma be a structure with a finite relational signature and a first-order definition in (R;*,+) with parameters from R, that is, a relational structure over the real numbers where all relations are semi-algebraic sets. In this article, we study the computational complexity of constraint satisfaction problem (CSP) for \Gamma: the problem to decide whether a given primitive positive sentence is true in \Gamma. We focus on those structures \Gamma that contain the relations \leq, {(x,y,z) | x+y=z} and {1}. Hence, all CSPs studied in this article are at least as expressive as the feasibility problem for linear programs. The central concept in our investigation is essential convexity: a relation S is essentially convex if for all a,b\inS, there are only finitely many points on the line segment between a and b that are not in S. If \Gamma contains a relation S that is not essentially convex and this is witnessed by rational points a,b, then we show that the CSP for \Gamma is NP-hard. Furthermore, we characterize essentially convex relations in logical terms. This different view may open up new ways for identifying tractable classes of semi-algebraic CSPs. For instance, we show that if \Gamma is a first-order expansion of (R;*,+), then the CSP for \Gamma can be solved in polynomial time if and only if all relations in \Gamma are essentially convex (unless P=NP).

  • 117.
    Bodirsky, Manuel
    et al.
    Ecole Polytechnique, Palaiseau, France.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    von Oertzen, Timo
    University of Virginia, USA.
    Horn versus Full First-order: Complexity Dichotomies in Algebraic Constraint Satisfaction2012In: Journal of logic and computation (Print), ISSN 0955-792X, E-ISSN 1465-363X, Vol. 22, no 3, p. 643-660Article in journal (Refereed)
    Abstract [en]

    We study techniques for deciding the computational complexity of infinite-domain constraint satisfaction problems. For certain fundamental algebraic structures Delta, we prove definability dichotomy theorems of the following form: for every first-order expansion Gamma of Delta, either Gamma has a quantifier-free Horn definition in Delta, or there is an element d of Gamma such that all non-empty relations in Gamma contain a tuple of the form (d,...,d), or all relations with a first-order definition in Delta have a primitive positive definition in Gamma. The results imply that several families of constraint satisfaction problems exhibit a complexity dichotomy: the problems are in P or NP-hard, depending on the choice of the allowed relations. As concrete examples, we investigate fundamental algebraic constraint satisfaction problems. The first class consists of all first-order expansions of (Q;+). The second class is the affine variant of the first class. In both cases, we obtain full dichotomies by utilising our general methods.

  • 118.
    Bodirsky, Manuel
    et al.
    Ecole Polytechnique, Palaiseau, France.
    Wrona, Michal
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Equivalence Constraints2012Conference paper (Other academic)
    Abstract [en]

    The following result for finite structures Gamma has been conjectured to hold for all countably infinite omega-categorical structures Gamma: either the model-complete core Delta of Gamma has an expansion by finitely many constants such that the pseudovariety generated by its polymorphism algebra contains a two-element algebra all of whose operations are projections, or there is a homomorphism f from Delta^k to Delta, for some finite k, and an automorphism alpha of Delta satisfying f(x1,...,xk) = alpha(f(x2,...,xk,x1)). This conjecture has been confirmed for all infinite structures Gamma that have a first-order definition over (Q;<), and for all structures that are definable over the random graph. In this paper, we verify the conjecture for all structures that are definable over an equivalence relation with a countably infinite number of countably infinite classes. Our result implies a complexity dichotomy (into NP-complete and P) for a family of constraint satisfaction problems (CSPs) which we call equivalence constraint satisfaction problems. The classification for equivalence CSPs can also be seen as a first step towards a classification of the CSPs for all relational structures that are first-order definable over Allen's interval algebra, a well-known constraint calculus in temporal reasoning.

  • 119.
    Boeira, Felipe
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    Mitigating Position Falsification Attacks in Vehicular Platooning2018In: 2018 IEEE VEHICULAR NETWORKING CONFERENCE (VNC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    As connected vehicles are envisioned to provide novel intelligent transportation systems, cyberattacks and security schemes are becoming an increasing concern. Several studies have shown that algorithms that make use of location information from other vehicles, such as vehicular platoon controllers, are vulnerable to message falsification attacks. Moreover, the ability for an attacking vehicle to appear as several vehicles through a so-called Sybil attack can significantly increase the severity of the attack. In this paper, we investigate how these attacks can be detected using Vouch location proof scheme (by identifying false location messages) and propose several reaction strategies to mitigate them. We also show through simulation that it is possible to prevent collisions by reacting appropriately to the false beacons in time while not reacting to false positives coming from the detector.

  • 120.
    Boeira, Felipe
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Univ Fed Rio Grande do Sul, Brazil; Halmstad Univ, Sweden.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    de Freitas, Edison P.
    Univ Fed Rio Grande do Sul, Brazil.
    Vinel, Alexey
    Halmstad Univ, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Effects of Colluding Sybil Nodes in Message Falsification Attacks for Vehicular Platooning2017In: 2017 IEEE VEHICULAR NETWORKING CONFERENCE (VNC), IEEE , 2017, p. 53-60Conference paper (Refereed)
    Abstract [en]

    This paper studies the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Platooning employs Inter-Vehicular Communication (IVC) to control a group of vehicles. It uses broadcast information such as acceleration, position, and velocity to operate a longitudinal control law. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of network communication to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. To carry out this study, we evaluate five scenarios to quantify the potential impact of such attacks, identifying how platoons behave under varying Sybil attack conditions and what are the associated safety risks. This research also presents the use of location hijacking attack. In this attack, innocent vehicles that are not part of a platoon are used as a way to create trust bond between the false identities and the physical vehicles. We demonstrate that the ability to create false identities increases the effectiveness of message falsification attacks by making them easier to deploy and harder to detect in time.

  • 121.
    Boeira, Felipe
    et al.
    Univ Fed Rio Grande do Sul, Brazil.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    de Freitas, Edison P.
    Univ Fed Rio Grande do Sul, Brazil.
    Vinel, Alexey
    Halmstad Univ, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    On the Impact of Sybil Attacks in Cooperative Driving Scenarios2017In: 2017 IFIP NETWORKING CONFERENCE (IFIP NETWORKING) AND WORKSHOPS, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Platooning employs a set of technologies to manage how a group of vehicles operates, including radar, GPS and Inter-Vehicular Communication (IVC). It uses broadcasted information such as acceleration, position and velocity to operate vehicle members of the platoon. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of IVC to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. In this paper we study the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Simulation results show that this attack may impact the longitudinal control and compromise the entire platoon control.

  • 122.
    Boije, Niklas
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Borg, Kristoffer
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Semi-automatic code-to-code transformer for Java: Transformation of library calls2016Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    Having the ability to perform large automatic software changes in a code base gives new possibilities for software restructuring and cost savings. The possibility of replacing software libraries in a semi-automatic way has been studied. String metrics are used to find equivalents between two libraries by looking at class- and method names. Rules based on the equivalents are then used to describe how to apply the transformation to the code base. Using the abstract syntax tree, locations for replacements are found and transformations are performed. After the transformations have been performed, an evaluation of the saved effort of doing the replacement automatically versus manually is made. It shows that a large part of the cost can be saved. An additional evaluation calculating the maintenance cost saved annually by changing libraries is also performed in order to prove the claim that an exchange can reduce the annual cost for the project.

  • 123.
    Bolinder, Richard
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Atmospheric Radiation Effects Study on Avionics: An Analysis of NFF Errors2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    No fault found (NFF) errors, i.e. errors which origin has not been established, irregularly occur in electronic devices. The actual cause of such errors varies but one, possibly more prominent, source for these soft errors is atmospheric radiation.

    The overarching aim of this thesis is to demonstrate: 1) the importance of keeping the atmospheric radiation environment in mind when designing robust airborne systems, 2) how to take this environment into consideration when applying mitigation techniques which may drastically reduce the risk of SEEs (Single Event Effects) which can cause NFF errors. To achieve these goals, Part 1 of this thesis describes how cosmic rays affect electronics (i.e. what kind of errors may be induced), which types of devices are susceptible to radiation, and why this subject is of extra importance for airborne systems. In addition, soft error mitigation techniques, which may be applied at different design levels to reduce the soft error rate (SER) or the impact of soft errors, are also presented.

    The aim is further corroborated by Part 2. Five subsystems of a modern aircraft are studied and real examples of failures potentially induced by atmospheric radiation are presented. For each of the five systems, all errors that have been reported for these (in the past few years) have been studied, and the number of errors found to be potentially induced by cosmic radiation has been listed and compared to number of expected soft errors based on calculations and previous experimental tests.

  • 124.
    Boman, Erik
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Converting an existing .NET Framework ground control software into a cross-platform application2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Unmanned aerial vehicles can be used in many different situations such as, for example, monitoring the growth of crops or for surveillance of a private property. Operating the unmanned aerial vehicle is usually done using some kind of ground control station. This thesis examines the possibilities of creating ground control stations working on several different platforms using the cross platform development frameworks Xamarin, Universal Windows Platform and Mono. This is done by creating and comparing three prototype applications regarding functional requirements, code reuse and resource usage. It is shown that none of the cross platform frameworks can fulfill all of the initial requirements on a ground control station. However, for the case studied in this thesis, Xamarin is demonstrated to be the most suitable cross platform framework of the three since it provides the same functionality as UWP for Windows devices while also enabling development for both Android and iOS devices.

  • 125.
    Bordoloi, Unmesh D.
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Aminifar, Amir
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Schedulability Analysis of Ethernet AVB Switches2014In: 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2014), Chongqing, China, Aug. 20-22, 2014., IEEE Computer Society, 2014Conference paper (Refereed)
    Abstract [en]

    Ethernet AVB is being actively considered by the automotive industry as a candidate for in-vehicle communication backbone. However, several questions pertaining to schedulability of hard real-time messages transmitted via such a switch remain unanswered. In this paper, we attempt to fill this void. We derive equations to perform worst-case response time analysis on Ethernet AVB switches by considering its credit-based shaping algorithm. Also, we propose several approaches to reduce the pessimism in the analysis to provide tighter bounds.

  • 126.
    Bordoloi, Unmesh D.
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Tanasa, Bogdan
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    On the Timing Analysis of the Dynamic Segment of FlexRay2012In: International Symposium on Industrial Embedded Systems (SIES 2012), Karlsruhe, Germany, June 20-22, 2012., 2012Conference paper (Other academic)
    Abstract [en]

    FlexRay, developed by a consortium of over hundred automotive companies, is a real-time communication protocol for automotive networks. A communication cycle in FlexRay consists of an event-triggered component known as the dynamic (DYN) segment, apart from a time-triggered segment. Predicting the worst-case response time of messages transmitted on the DYN segment is a difficult problem. This is because a set of complex rules, apart from the priorities of the messages, govern the DYN segment protocol. In this paper, we survey techniques for the timing analysis of the DYN segment. We discuss the challenges associated with the timing analysis of the FlexRay protocol, the proposed techniques and their limitations.

  • 127.
    Bordoloi, Unmesh D.
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Tanasa, Bogdan
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Tahoori, Mehdi B.
    Institute of Computer Science & Engineering (ITEC), Karlsruhe Institute of Technology (KIT), Germany.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Shazli, Syed Z.
    Northeastern University, USA.
    Chakraborty, Samarjit
    Technical University of Munich, Germany.
    Reliability-Aware Instruction Set Customization for ASIPs with Hardened Logic2012In: International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2012), Seoul, Korea, August 19-22, 2012., 2012Conference paper (Refereed)
    Abstract [en]

    Application-specific instruction-set processors (ASIPs) allow the designer to extend the instruction set of the base processor with selected custom instructions to tailor-fit the application.In this paper, with the help of a motivational example, we first demonstrate that different custom instructions are vulnerable to faults with varying probabilities. This shows that by ignoring the vulnerability to faults, traditional methods of instruction set customization can provide no guarantees on the reliability of the system. Apart from such inherent disparity in error vulnerability across custom instructions, each custom instruction can have multiple implementation choices corresponding to varying hardened levels. Hardening reduces the vulnerability to errors but this comes at the overhead of area costs and reduced performance gain. In this paper, we propose a framework to select custom instructions and their respective hardening levels such that reliability is optimized while the performance gain is satisfied and area costs are met as well. Our framework is based on a novel analytical method to compute the overall system reliability based on the probability of failure of individual instructions. Wide range of experiments that were conducted illustrate how our tool navigates the design space to reveal interesting tradeoffs.

  • 128.
    Bordoloi, Unmesh
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Samii, Soheil
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    The Frame Packing Problem for CAN-FD2014In: Real-Time Systems Symposium (RTSS 2014), Rome, Italy, Dec. 2-5, 2014., IEEE Press, 2014, p. 284-293Conference paper (Refereed)
    Abstract [en]

    CAN with flexible data rate (CAN-FD) allows transmission of larger payloads compared to standard CAN. However, efficient utilization of CAN-FD bandwidth space calls for a systematic strategy. The challenge arises from the nature of the frame sizes stipulated by CAN-FD as well as the heterogeneity of the periods of the messages and the signals. In this paper, we formulate a frame packing problem for CAN-FD with the optimization objective of bandwidth utilization while meeting temporal constraints. As part of the solution, first, we propose a formula to compute the best-case and the worst-case transmission times of the CAN-FD frames. Thereafter, we propose a framework that solves the optimization problem in pseudo-polynomial time. Experiments show the gains achieved by our framework. The results also show that, when applied to standard CAN, our heuristic provides improved results over existing techniques.

  • 129.
    Borek, Paul
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    SMT Aided Test Case Generation For Constrained Feature Models2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the development of highly configurable and large software, a new challenge has to be addressed, when it comes to software testing. While traditional testing approaches might still apply and succeed in achieving a better quality of service, the high degree of customizable parts of such a system implies the mentioned testing activities on different configurations. If a formal notion is used to express the allowed configurations of a system, one might think of generating such configurations in an automated fashion. However, if there are constraints involved, traditional model-based test-case generation might cause problems to achieve a desired coherency. An idea is, to use those constraints to generate test-cases and to achieve coherency at the same time. Satisfiability modulo theories (SMT) has been an emerging field in current theoretical computer science and developed decision procedures to treat various theoretical fragments in a specific manner. The goal of this thesis is, to look at a translation mechanism from an expression language for constraints into SAT modulo theories and involve this technique into a test-case generation process. Furthermore, the balance between the generation of coherent test-cases as well as the problem-specific purposes of such test-cases is investigated.

  • 130.
    Borg, Therese
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Usability of a Business Software Solution for Financial Follow-up Information of Service Contracts2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Enterprise Resource Planning systems have been available since the 1990s and come with several business benefits for the users. One of the major advantages is improved decision making through current and accessible information about strategical, tactical and operational levels of the organization. Although several Enterprise Resource Planning system vendors provide several features for contract management, more decision support regarding the total profitability of service contracts is desired by the customers. Estimating the total profitability of service contracts is a challenging task for all service providers and implies a lot of manual data processing by the contract manager. This master’s thesis is conducted in collaboration with IFS World Operations AB and aims to investigate how functionality for budget and forecasting of the profitability of service contracts can be designed to be usable in terms of effectiveness. The implementation was performed iteratively and the resulting prototypes were evaluated and refined throughout the project. The final high-fidelity prototype for budgeting of service contracts was evaluated using the task success rate in conjunction with the System Usability Scale to assess how well the system conformed to the needs of the users. The study revealed that two of the key characteristics of financial follow-up information of service contracts is the support of creating a budget and graphical visualizations of both budgeted and actual values. The final usability evaluation indicated that the developed functionality was usable in terms of effectiveness and has an overall usability clearly above the average.

  • 131.
    Boudjadar, Abdeldjalil
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    David, Alexandre
    Aalborg University, Denmark.
    Hyun Kim, Jin
    INRIA IRISA, France.
    Larsen, Kim G.
    Aalborg University, Denmark.
    Mikucionis, Marius
    Aalborg University, Denmark.
    Nyman, Ulrik
    Aalborg University, Denmark.
    Skou, Arne
    Aalborg University, Denmark.
    A reconfigurable framework for compositional schedulability and power analysis of hierarchical scheduling systems with frequency scaling2015In: Science of Computer Programming, ISSN 0167-6423, E-ISSN 1872-7964, Vol. 113, p. 236-260Article in journal (Refereed)
    Abstract [en]

    This paper presents a compositional framework for the modeling and analysis of hierarchical scheduling systems. We consider both schedulability and energy consumption of individual components, while analyzing a single core setting with a voltage frequency scaling CPU. According to the CPU frequency scaling, each task has a set of different execution times. Thus, the energy consumption of the whole system varies from one execution to another. We analyze each component individually by checking the feasibility of its workload against both the CPU availability and energy consumption constraints of such a component. Our periodic task model considers both static and dynamic priorities together with preemptive and non-preemptive behaviors. The models are realized using different forms of Hybrid Automata, all of which are analyzed using variants of UPPAAL. The CPU frequencies, task behavior and scheduling policies used in each component are some of the reconfigurable parameters of the system. Finally, we demonstrate the applicability and scalability of our framework by analyzing the schedulability and power consumption of an avionics system. (C) 2015 Elsevier B.V. All rights reserved.

  • 132.
    Boudjadar, Abdeldjalil
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Dingel, Juergen
    Queen's University, Canada.
    Madzar, Boris
    Queen's University, Canada.
    Hyun Kim, Jin
    INRIA Rennes, France.
    Compositional Predictability Analysis of Mixed Critical Real Time Systems2016In: FORMAL TECHNIQUES FOR SAFETY-CRITICAL SYSTEMS, (FTSCS 2015) / [ed] Artho and P.C. Olveczky, Springer, 2016, Vol. 596, p. 69-84Conference paper (Refereed)
    Abstract [en]

    This paper introduces a compositional framework for analyzing the predictability of component-based embedded real-time systems. The framework utilizes automated analysis of tasks and communication architdepicts the structureectures to provide insight on the schedulability and data flow. The communicating tasks are gathered within components, making the system architecture hierarchical. The system model is given by a set of Parameterized Stopwatch Automata modeling the behavior and dependency of tasks, while we use Uppaal to analyze the predictability. Thanks to the Uppaal language, our model-based framework allows expressive modeling of the behavior. Moreover, our reconfigurable framework is customizable and scalable due to the compositional analysis. The analysis time and cost benefits of our framework are discussed through an avionic case study.

  • 133.
    Boudjadar, Jalil
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Hyun Kin, Jin
    University of Pennsylvania, USA.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Performance-aware Scheduling of Multicore Time-critical Systems2016In: / [ed] IEEE, IEEE, 2016, p. 105-114Conference paper (Refereed)
    Abstract [en]

    Despite attractiveness of multicore processors for embedded systems, the potential performance gains need to be studied in the context of real-time task scheduling and memory interference. This paper explores performance-aware schedula-bility of multicore systems by evaluating the performance when changing scheduling policies (as design parameters). The modelbased framework we build enables analyzing the performance of multicore time-critical systems using processor-centric and memory-centric scheduling policies. The system architecture we consider consists of a set of cores with a local cache and sharing the cache level L2 and main memory (DRAM). The metrics we use to compare the performance achieved by different configurations of a system are: 1) utilization of the cores; and 2) the maximum delay per access request to shared cache and DRAM. Our framework, realized using UPPAAL, can be viewed as an engineering tool to be used during design stages to identify the scheduling policies that provide better performance for a given system while maintaining system schedulability. As a proof of concept, we analyze and compare 2 different cases studies.

  • 134.
    Boudjadar, Jalil
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Schedulability and Memory Interference Analysis of Multicore Preemptive Real-time Systems2017In: ICPE '17 Proceedings of the 8th ACM/SPEC on International Conference on Performance Engineering, ACM Press, 2017, p. 263-274Conference paper (Refereed)
    Abstract [en]

    Today's embedded systems demand increasing computingpower to accommodate the ever-growing software functionality.Automotive and avionic systems aim to leverage thehigh performance capabilities of multicore platforms, but arefaced with challenges with respect to temporal predictability.Multicore designers have achieved much progress onimprovement of memory-dependent performance in cachingsystems and shared memories in general. However, havingapplications running simultaneously and requesting the accessto the shared memories concurrently leads to interference.The performance unpredictability resulting from interferenceat any shared memory level may lead to violationof the timing properties in safety-critical real-time systems.In this paper, we introduce a formal analysis framework forthe schedulability and memory interference of multicore systemswith shared caches and DRAM. We build a multicoresystem model with a ne grained application behavior givenin terms of periodic preemptible tasks, described with explicitread and write access numbers for shared caches andDRAM. We also provide a method to analyze and recommendcandidates for task-to-core reallocation with the goalto nd schedulable congurations if a given system is notschedulable. Our model-based framework is realized usingUppaal and has been used to analyze a case study

  • 135.
    Braaf, Joakim
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Introducing Mock framework for Unit Test ina modeling environment2014Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Testing is an important part in the software development process. Unit testsaim to test individual units in isolation. These units may have dependenciesto their surroundings that make the units hard to test in isolation withoutalso testing the surrounding units. A technique to help isolate these units isto replace the surrounding units with mock objects. This work investigateshow a C++ mock framework can be integrated into a modeling environ-ment’s unit test framework. Several mock frameworks are evaluated, and aproof of concept is created to show that integration is possible. Additionally,ideas for how to use mocks in a model environment are presented.

  • 136.
    Bragazzi Ihrén, Maximilian
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Ingbrant Björs, Henrik
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Visualizing atmospheric data on a mobile platform2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Weather data is important for almost everyone today. Thedaily weather report, home thermometers, and a lot of otherthings affect our every day life. In order to develop betterand more efficient equipment, tools and algorithms, thepeople working with this data need to be able to access it inan easily accessible and easy to read format. In thisresearch, methods of visualizing data on mobile platformsare evaluated based on what researchers in the field wants,since their respective fields might want to use very specificvisualizations. The implementability of these visualizationsare then evaluated, based on the implementations madethroughout this paper. The results show that the researchersknow what they want, and that what they want isimplementable on mobile platforms given some limitationscaused by performance.

  • 137.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Asghar, Adeel
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fritzson, Dag
    SKF Group Technology, AB SKF.
    An Open-Source Framework for Efficient Co-simulation of Fluid Power Systems2017In: Proceedings of 15th Scandinavian International Conference on Fluid Power, SICFP’17, Linköping: Linköping University Electronic Press, 2017, Vol. 144, p. 393-400Conference paper (Refereed)
    Abstract [en]

    Simulation of fluid power systems typically requires models from multiple disciplines.Achieving accurate load dynamics for a system with complex geometry, for example, mayrequire both a 1D model of the hydraulic circuit and a 3D multi-body model. However, mostsimulation tools are limited to a single discipline. A solution to these kinds of problems isco-simulation, where different tools are coupled and simulated together. Co-simulation canprovide increased accuracy, improved modularity and facilitated collaboration between dif-ferent organizations. Unfortunately, tool coupling typically requires tedious and error-pronemanual work. It may also introduce numerical problems. For these reasons, co-simulation isoften avoided as long as possible. These problems have been addressed by the developmentof an open-source framework for asynchronous co-simulation. Simulation tools can be inter-connected through a stand-alone master simulation tool. An extensive range of tools is alsosupported via the Functional Mockup Interface standard. A graphical user interface has beenimplemented in the OpenModelica Connection Editor. System models can be created andedited from both a schematic view and a 3D view. Numerical robustness is enforced by theuse of transmission line modelling. A minimalistic programming interface consisting of onlytwo functions is used. An example model consisting of a hydraulic crane with two arms, twoactuators and a hanging load is used to verify the framework. The composite model consistsof nine multi-body models, one hydraulic system model and a controller. It is shown thatmodels from various simulation tools can be replaced with a minimal amount of user input.

  • 138.
    Brehmer, Dan
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Evaluering och optimering av automatisk beståndsindelning2016Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Beståndsindelning av skog är till stor den en manuell process som kräver mycket tid. De senaste 20 åren har tekniker som Airborne Laser Scanning (ALS) bidragit till en effektivisering av processen genom att generera laserdata som möjliggör skapandet av lättolkade bilder av skogsområden. Ur laser- och bilddata kan skogliga attribut så som trädhöjd, trädtäthet och markhöjd extraheras. Studiens syfte var att utvärdera vilka attribut som var mest relevanta för att särskilja skogsbestånd i ett system som delade in skog i bestånd automatiskt. Vid analys av attributens relevans användes klassificeringsmodeller. Fackmän intervjuades och litteratur studerades. Under studien modifierades systemets algoritmer med ambitionen att höja dess resultat till en tillfredsställande nivå. Studien visade att attribut som är kopplade till skogssköstel har störst relevans vid automatisk beståndsindelning. Trots modifieringar och använding av relevanta attribut lyckades studien inte påvisa att systemet kunde fungera som en egen lösning för beståndsindelning av skog. Däremot var den resulterande beståndsindelningen lämplig att använda som ett komplement vid manuell beståndsindelning.

  • 139.
    Brenner, Jürgen
    et al.
    FernUniversität in Hagen, Germany.
    Keller, Jörg
    FernUniversität in Hagen, Germany.
    Kessler, Christoph
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Executing PRAM Programs on GPUs2012In: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 9, p. 1799-1806Article in journal (Refereed)
    Abstract [en]

    We present a framework to transform PRAM programs from the PRAM programming language Fork to CUDA C, so that they can be compiled and executed on a Graphics Processor (GPU). This allows to explore parallel algorithmics on a scale beyond toy problems, to which the previous, sequential PRAM simulator restricted practical use. We explain the design decisions and evaluate a prototype implementation consisting of a runtime library and a set of rules to transform simple Fork programs which we for now apply by hand. The resulting CUDA code is almost 100 times faster than the previous simulator for compiled Fork programs and allows to handle larger data sizes. Compared to a sequential program for the same problem, the GPU code might be faster or slower, depending on the Fork program structure, i.e. on the overhead incurred. We also give an outlook how future GPUs might notably reduce the overhead.

  • 140.
    Brinkrolf, Christoph
    et al.
    Bielefeld University, Faculty of Technology, Bioinformatics Department, Bielefeld, Germany.
    Henke, Nadja A
    Bielefeld University, Faculty of Biology and CeBiTec, Genetics of Prokaryotes, Bielefeld, Germany.
    Ochel, Lennart
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Bielefeld University, Faculty of Technology, Bioinformatics Department, Bielefeld, Germany.
    Pucker, Boas
    Bielefeld University, Faculty of Biology and CeBiTec, Genome Research, Bielefeld, Germany; University of Cambridge, Department of PlantSciences, Evolution and Diversity, Cambridge, UK.
    Kruse, Olaf
    Bielefeld University, Faculty of Biology and CeBiTec, Algae Biotechnology and Bioenergy, Bielefeld, Germany.
    Lutter, Petra
    Bielefeld University, Faculty of Biology and CeBiTec, Proteome and Metabolome Research, Bielefeld, Germany.
    Modeling and Simulating the Aerobic Carbon Metabolism of a Green Microalga Using Petri Nets and New Concepts of VANESA2018In: Journal of integrative bioinformatics, ISSN 1613-4516, Vol. 15, no 3Article in journal (Refereed)
    Abstract [en]

    In this work we present new concepts of VANESA, a tool for modeling and simulation in systems biology. We provide a convenient way to handle mathematical expressions and take physical units into account. Simulation and result management has been improved, and syntax and consistency checks, based on physical units, reduce modeling errors. As a proof of concept, essential components of the aerobic carbon metabolism of the green microalga Chlamydomonas reinhardtii are modeled and simulated. The modeling process is based on xHPN Petri net formalism and simulation is performed with OpenModelica, a powerful environment and compiler for Modelica. VANESA, as well as OpenModelica, is open source, free-of-charge for non-commercial use, and is available at: http://agbi.techfak.uni-bielefeld.de/vanesa.

  • 141.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology. University of Calif Berkeley, CA 94720 USA .
    Derler, Patricia
    University of Calif Berkeley, CA 94720 USA .
    Eidson, John C
    University of Calif Berkeley, CA 94720 USA .
    Temporal Issues in Cyber-Physical Systems2013In: JOURNAL OF THE INDIAN INSTITUTE OF SCIENCE, ISSN 0970-4140, Vol. 93, no 3, p. 389-402Article, review/survey (Refereed)
    Abstract [en]

    This paper reviews the use of time, clocks, and clock synchronization protocols in cyber-physical systems (CPS). Recent advances in the area of timing suggest avenues of research and potential new application areas. We discuss how introducing timestamps and clocks can help overcome issues such as latency, jitter, and determining correct execution order. Furthermore, we show how system complexity can be reduced and distribution as well as parallelism can be done deterministically. We also point to recent work in raising time to first class citizen status in modeling and implementation. In particular, we describe design and execution environments of CPS and specialized hardware such as predictable timing architectures where time plays a key role.

  • 142.
    Broman, David
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Hedin, Görel
    Lund University, Sweden.
    Åkesson, Johan
    Lund University, Sweden.
    A comparison of two metacompilation approaches to implementing a complex domain-specific language2012In: Proceedings of the 27th Annual ACM Symposium on Applied Computing, Association for Computing Machinery (ACM), 2012, p. 1919-1921Conference paper (Refereed)
    Abstract [en]

    Operational semantics and attribute grammars are examples of formalisms that can be used for generating compilers. We are interested in finding similarities and differences in how these approaches are applied to complex languages, and for generating compilers of such maturity that they have users in industry.

    As a specific case, we present a comparative analysis of two compilers for Modelica, a language for physical modeling, and which contains numerous compilation challenges. The two compilers are OpenModelica, which is based on big-step operational semantics, and JModelica.org, which is based on reference attribute grammars.

  • 143.
    Brunnerby, Erik
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Android Machine Interface: Integrating anAndroid Mobile Device into an Industrial Control System2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The interaction between humans and industrial machinery have long been dominated by purpose-built hardware made to withstand the tough environment of the factory floor. Advances in hardware and software in the recent decade has made mobile and powerful devices common place, which has prompted this study to evaluate an Android tablet as an interface to control and monitor industrial machinery. This has been done through the implementation of an application used to control a braiding machine. Using this application as a proof of concept and a practical assessment, the study has concluded that an Android device is feasible to use to control and monitor industrial machinery. The study has also evaluated the network performance and security through testing, where it has compared the transport layer protocols TCP and UDP as well as the use of encryption for this implementation.

  • 144.
    Buffoni, Lena
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, AdrianLinköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.Thiele, BernhardLinköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Proceedings of the 56th Conference on Simulation and Modelling (SIMS 56): October, 7-9, 2015, Linköping University, Sweden2015Conference proceedings (editor) (Refereed)
    Abstract [en]

    Welcome

    The 56th Conference on Simulation and Modelling will be held in Linköping, Sweden. Linköping is one of Sweden’s fastest growing cities. The population is constantly increasing and will soon surpass 150 000 inhabitants. It is currently Sweden’s fifth largest city and a part of the expansive region Twin Cities of Sweden. Linköping has long been characterized by world-class high technology in the fields of aviation, IT and the environment. There is a strong force of innovation especially in Mjärdevi Science Park—one of Europe’s leading technology parks, and at the highly ranked university, which stands for excellence and entrepreneurship.

    SIMS is the Scandinavian Simulation Society with members from the five Nordic countries Denmark, Finland, Norway, Sweden and Iceland. The SIMS history goes back to 1959. The goal of SIMS is to further the science and practice of modeling and simulation in all application areas and be a Scandinavian forum for information interchange among modeling and simulation professionals and non-professionals in Denmark, Finland, Norway and Sweden as well as a channel for information exchange between the Scandinavian modeling and simulation community and the international modeling and simulation communities.

    The ambition of the SIMS is to bring the field of modeling and simulation technology to a variety of application fields from energy extraction to building and automotive industries, resulting in more sustainable and ecological systems and reducing energy consumption and waste production. The scientific program includes technical sessions with submitted and invited papers and will cover broad aspects of simulation, modeling and optimization.

    The focus of the conference is split evenly between papers on simulation and optimization in a variety of applied contexts spanning domains such as oil extraction, automotive and building industries and more methodological papers on tools and technologies for simulation and modeling.

    This year we wanted to emphasize the importance of reducing the gap between state of the art methodologies and tools and industrial applications. To this end a number of invited talks, papers and tutorials were centered on tools and methodologies for successful modeling in an industrial context.

    The format of the conference is somewhat changed compared to previous years. This year we have dedicated a half-day before the traditional two-day conference to tutorials, with 3 tutorials presenting stateof- the-art simulation tools.

    Conference highlights:

    • 4 Keynote speeches
    • 40 papers in 2 parallel tracks
    • 3 tutorials
    • Electronic proceedings including all papers and some associated Modelica libraries and models

    Finally, we want to acknowledge the support we received from the conference board and program committee as well as from the SIMS board. Special thanks to our colleagues at this year’s organizers at Linköping University, especially to Åsa Kärrman, and Tina Malmström from Grand Travel Group. The support from the conference sponsors is gratefully acknowledged. Last but not least, thanks to all authors, keynote speakers, and presenters for their contributions to this conference. We wish all participants an enjoyable and inspiring conference.

    Linköping, September 1, 2015

    Lena Buffoni, Adrian Pop and Bernhard Thiele

  • 145.
    Buhaiu, Andrei
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Radio Frequency Remote Control Unit with Gyro and Accelerometer2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today digital TV receivers (Set-Top-Boxes) are mainly controlled by IR-based remote control units (RCUs). With new services emerging in thereceivers where better browsing and pointing abilities are desirable (VODservices, Web services, games etc), one solution is a new type of RF remotecontrol. An RF RCU has a number of advantages, e.g. when in range, ithas 100% reliable transmission, it is not sensitive to direction, and it doesnot require a free way to the receiver (i.e. it allows the receiver to be hiddenbehind the TV-set or in a cabinet).

  • 146.
    Bäckström, Christer
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Parameterising the Complexity of Planning by the Number of Paths in the Domain-transition Graphs2014In: Proceedings of the 21st European Conference on Artificial Intelligence (ECAI-14), IOS Press, 2014, p. 33-38Conference paper (Refereed)
    Abstract [en]

    We apply the theory of parameterised complexity to planning, using the concept of fixed-parameter tractability (fpt) which is more relaxed than the usual tractability concept. The parameter we focus on is the maximal number of paths in the domain-transition graphs, and we show that for this parameter, optimal planning is fpt for planning instances with polytree causal graphs and acyclic domain-transition graphs. If this parameter is combined with the additional parameters of domain size for the variables and the treewidth of the causal graph, then planning is fpt also for instances with arbitrary causal graphs. Furthermore, all these parameters are fpt to test in advance. These results also imply that delete-relaxed planning is fpt, even in its recent generalisation to non-binary variables.

  • 147.
    Bäckström, Christer
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Some Fixed Parameter Tractability Results for Planning with Non-Acyclic Domain-Transition Graphs2015In: Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI-2015), AAAI Press, 2015Conference paper (Refereed)
    Abstract [en]

    Bäckström studied the parameterised complexity of planning when the domain-transition graphs (DTGs) are acyclic. He used the parameters d (domain size), k (number of paths in the DTGs) and w (treewidth of the causal graph), and showed that planning is fixed-parameter tractable (fpt) in these parameters, and fpt in only parameter k if the causal graph is a polytree. We continue this work by considering some additional cases of non-acyclic DTGs. In particular, we consider the case where each strongly connected component (SCC) in a DTG must be a simple cycle, and we show that planning is fpt for this case if the causal graph is a polytree. This is done by first preprocessing the instance to construct an equivalent abstraction and then apply B¨ackstr¨oms technique to this abstraction. We use the parameters d and k, reinterpreting this as the number of paths in the condensation of a DTG, and the two new parameters c (the number of contracted cycles along a path) and pmax (an upper bound for walking around cycles, when not unbounded).

  • 148.
    Bäckström, Christer
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Chen, Yue
    Vienna University of Technology, Austria.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Ordyniak, Sebastian
    Vienna University of Technology, Austria.
    Szeider, Stefan
    Vienna University of Technology, Austria.
    The Complexity of Planning Revisited - A Parameterized Analysis2012In: Proceedings of the Twenty-Sixth AAAI Conference on Artificial Intelligence, AAAI Press, 2012, p. 1735-1741Conference paper (Refereed)
    Abstract [en]

    The early classifications of the computational complexity of planning under various restrictions in STRIPS (Bylander) and SAS+ (B¨ackstr¨om and Nebel) have influenced following research in planning in many ways. We go back and reanalyse their subclasses, but this time using the more modern tool of parameterized complexity analysis. This provides new results that together with the old results give a more detailed picture of the complexity landscape. We demonstrate separation results not possible with standard complexity theory, which contributes to explaining why certain cases of planning haveseemed simpler in practice than theory has predicted. In particular, we show that certain restrictions of practical interest are tractable in the parameterized sense of the term, and that a simple heuristic is sufficient to make a well-known partialorder planner exploit this fact.

  • 149.
    Bäckström, Christer
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Jonsson, Anders
    University of Pompeu Fabra, Spain.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Automaton Plans2014In: The journal of artificial intelligence research, ISSN 1076-9757, E-ISSN 1943-5037, Vol. 51, p. 255-291Article in journal (Refereed)
    Abstract [en]

    Macros have long been used in planning to represent subsequences of operators. Macros can be used in place of individual operators during search, sometimes reducing the effort required to find a plan to the goal. Another use of macros is to compactly represent long plans. In this paper we introduce a novel solution concept called automaton plans in which plans are represented using hierarchies of automata. Automaton plans can be viewed as an extension of macros that enables parameterization and branching. We provide several examples that illustrate how automaton plans can be useful, both as a compact representation of exponentially long plans and as an alternative to sequential solutions in benchmark domains such as LOGISTICS and GRID. We also compare automaton plans to other compact plan representations from the literature, and find that automaton plans are strictly more expressive than macros, but strictly less expressive than HTNs and certain representations allowing efficient sequential access to the operators of the plan.

  • 150.
    Bäckström, Christer
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Jonsson, Anders
    Universitat Pompeu Fabra, Barcelona, Spain.
    Jonsson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    From Macro Plans to Automata Plans2012In: ECAI 2012. 20th European Conference on Artificial Intelligence, 27-31 2012,  August, Montpellier, France, 2012, p. 91-96Conference paper (Refereed)
    Abstract [en]

    Macros have a long-standing role in planning as a tool for representing repeating subsequences of operators. Macros are useful both for guiding search towards a solution and for representing plans compactly. In this paper we introduce automata plans which consist of hierarchies of finite state automata. Automata plans can be viewed as an extension of macros that enables parametrization and branching. We provide several examples of the utility of automata plans, and prove that automata plans are strictly more expressive than macro plans. We also prove that automata plans admit polynomialtime sequential access of the operators in the underlying “flat” plan, and identify a subset of automata plans that admit polynomial-time random access. Finally, we compare automata plans with other representations allowing polynomial-time sequential access.

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