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  • 501.
    Stenberg, David
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Recompiling DSP applications to x86 using LLVM IR2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis describes the design and implementation of a prototype LLVM compiler backend, x86-64p, that compiles code written for a DSP architecture, FADER, into executables for the x86-64 architecture. The prototype takes LLVM IR generated for the FADER architecture and compiles x86-64 executables that emulate the properties of the DSP architecture, e.g. the multiple address spaces, the big-endianness and the support for fixed-point arithmetics. The backend is compared to a previous solution, C-Emu, that converts the DSP code to normal C code that is compiled using a normal x86-64 compiler. The two solutions are compared in terms of their correctness, debuggability and performance. The created prototype handles code containing low-level architectural assumptions better than C-Emu. However, the added emulation reduces the debuggability and performance of the generated executables. We have measured a runtime overhead of up to a factor of two compared to C-Emu. We also present some possible solutions for these issues.

  • 502.
    Stenlund, Sebastian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Testing Safety Critical Avionics Software Using LBTest2016Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A case study for the tool LBTest illustrating benets and limitations of the tool along the terms of usability, results and costs. The study shows the use of learning based testing on a safety critical application in the avionics industry. While requiring the user to have the oretical knowledge of the tools inner workings, the process of using the tool has benefits in terms of requirement analysis and the possibility of finding design and implementation errors in both the early and late stages of development

  • 503.
    Ström, Joakim
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Sjölund, Jakob
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Unit Test of Capsules using Google Test Framework2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Software testing is an important part of modern system development. It is a collection of methods used to detect and correct bugs and faults found in software code. Unit testing is a widely used technique in software testing where individual units of source code are isolated, often divided up into classes and functions, and tested separately.

    When developing in a modeling environment, the system components and their respective behavior are expressed by models written in the Unified Modeling Language (UML). These model descriptions are then used to automatically generate programming code for compilation into real-time systems. The generated code can in turn be subjected to unit testing in order to aid in the verification of the systems behavior and functionality.

    The modeling tool Rational Software Architect RealTime Edition (RSARTE), developed by IBM, is one example of such an environment. The generated code from the UML models in RSARTE is designed to execute in a real-time computing C++ runtime environment. An essential building block for real-time functionality is the Capsule model. A capsule is an element with an internal state-machine and ports defining its behavior and communication with other capsules. This construction is of great help when programming concurrent real-time applications.

    Due to the complexity provided by the real-time runtime environment, it is difficult to isolate and unit test the behavior of designed capsules. In this thesis we will show that a capsule in this environment can be isolated and then subjected to unit testing with the help of an integrated third party unit test framework. Also, before integrating a suitable framework, we will select one by doing a review, discussion and a comparison of different mature and available unit test frameworks for use in the C++ language.

  • 504.
    Strömbäck, Filip
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    A Syntax Highlighting and Code Formatting Tool for Extensible Languages2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Domain specific languages are sometimes useful to make it easier to express solutions to problems in a specific domain compared to general purpose programming languages. There are a number of tools available to create such languages, either as separate languages or by extending an existing language. One large problem with creating languages or language extensions is that existing tools are unaware of the new language, and therefore unable to properly assist the programmer unless all such tools are extended to support the new language. Extending all tools to support the new language is often a large enough task to be infeasible, especially for small languages.

    In this thesis, we propose using the compiler of the extensible language Storm to provide the information required for a text editor to provide syntax highlighting and code formatting. By using the Storm compiler to provide the required information, it is possible to use the Storm language definitions for syntax highlighting and code formatting in addition to compiling the language. This means that syntax highlighting and code formatting can be provided without requiring the language author to maintain multiple implementations of the language. The solution is evaluated by comparing the correctness and the responsiveness of the syntax highlighting to Emacs.

  • 505.
    Strömgren, Oliver
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Usage of Constraint Programming for Nurse Rostering Problems: A literature study2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Constraint Programming can be used to solve many problems and this thesis is about getting an overview on the usage of Constraint Programming for Constraint Satisfaction Problems, both interactive and explorative. Many problems can be mathematically modeled as a Constraint Satisfaction Problem but this thesis will focus on the Nurse Rostering Problem since it is a well-studied area. The problem when creating a schedule for nurses is that it can easily be over-constrained and a solution could be hard to find. This thesis will investigate whether if Constraint Programming is a good technique for solving the Nurse Rostering Problem but also if user interaction is considered when solving the problem. The method for this is a literature study where a number of research articles has been reviewed and categorized, and resulted in 27 different kinds of sources that were used. The conclusion is that there exists better ways to solve these problems than the use of pure Constraint Programming. To answer the second part of the thesis, it seems like the solution for the problem is the main focus and therefore is user interaction something that is given less attention.

  • 506.
    Ståhlberg, Povel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Persson, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Practical Approach to Developing an Automation Testing Tool2018Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Manually verifying a software under development can be time consuming because ofits complexity, but also because of frequent updates to different parts of the system. As thesoftware grows larger, a way of verifying the software automatically withoutuser-interaction is a good approach. Verifying a software systematically and automaticallywill both save time for the developers; and assure that the updated version functions asbefore. This report will present a starting point for automatic testing. This is done incooperation with XperDi, a company developing a plug-in for CAD-software thatcurrently verifies their functionality manually. This was achieved by developing a testingtool that support communication between Windows applications used by the plug-in; thiswas needed to automate the testing process. The reached conclusions during this thesisare promising as a starting point for XperDi; to move from manually to automaticverification. There are however several improvements that this report presents for furtherdevelopment of testing tool.

  • 507.
    Ståhlberg, Simon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Methods for Detecting Unsolvable Planning Instances using Variable Projection2017Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis we study automated planning, a branch of artificialintelligence, which deals with construction of plans. A plan is typically an action sequence that achieves some specific goal. In particular, we study unsolvable planning instances, i.e. there is no plan. Historically, this topic has been neglected by the planning community, and up to recently the International Planning Competition has only evaluated planners on solvable planning instances. For many applications we can know, e.g. by design, that there is a solution, but this cannot be a general assumption. One example is penetration testing in computer security, where a system inconsidered safe if there is no plan for intrusion. Other examples are resource bound planning instances that have insufficient resources to achieve the goal.

    The main theme of this thesis is to use variable projection to prove unsolvability of planning instances. We implement and evaluate two planners: the first checks variable projections with the goal of finding an unsolvable projection, and the second builds a pattern collection to provide dead-end detection. In addition to comparing the planners to existing planners, we also utilise a large computer cluser to statistically assess whether they can be optimised further. On the benchmarks of planning instances that we used, it turns out that further improvement is likely to come from supplementary techniques rather than optimisation. We pursued this and enhanced variable projections with mutexes, which yielded a very competitive planner. We also inspect whether unsolvable variable projections tend to be composed of variables that play different roles, i.e. they are not 'similar'. We devise a variable similarity measure to rate how similar two variables are on a scale, and statistically analyse it. The measure can differentiate between unsolvable and solvable planning instances quite well, and is integrated into our planners. We also define a binary version of the measure, namely, that two variables are isomorphic if they behave exactly the same in some optimal solution (extremely similar). With the help of isomorphic variables we identified a computationally tractable class of planning instances that meet certain restrictions. There are several special cases of this class that are of practical interest, and this result encompass them.

  • 508.
    Sävenhed, Jonatan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Resman, Elias
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Xcontrol: Kontroll av kommunikation i API:er2017Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Fler standardiserade API:er (Application Programming Interface) växer fram, detta underlättar införande av informationsbyten mellan system, eftersom det är samma API som visas utåt oavsett vilket system som finns bakom. En nackdel med detta är att det kan växa fram många och komplexa kopplingar mellan API:er och olika system då de kommunicerar via internet, det är då viktigt att inte förlorar kontroll. Med kontroll menas att hålla reda på all kommunikation mellan API:erna och systemen. Fördelar med detta är att bättre prestanda kan uppnås, undersöka belastning och göra felsökning lättare samt att det medför att företaget sparar både tid och pengar.

    Detta arbete handlar om att ta fram ett produktförslag som vi har valt att kalla Xcontrol. Xcontrol:s uppgift är att vara en mellanhand mellan fastighetssystem och olika tjänster till dessa fastighetssystem, systemen kommunicerar med hjälp av ett API kallat fastAPI. Produktförslaget innehåller en översikt på hur arkitekturen kan se ut och förslag på vilka funktioner som kan finnas i Xcontrol.

    I rapporten beskrivs också hur en av dessa funktioner implementeras, vilket är loggning av internettrafiken mellan systemen. Där beskrivs designen av databasen, hur man tar emot och skickar vidare information mellan systemen samt hur man visar upp statistik av informationen med hjälp av grafer. Avslutningsvis diskuteras arbetets utförande, slutsatser och framtida arbete.

  • 509.
    Söderbäck, Karl
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Design, Implementation, and Performance Evaluation of HLA in Unity2017Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report investigates if an HLA-plugin for the game engine Unity can be made and whether or not it would lead to any drawbacks in regard to data exchange and performance. An implementation of a plugin and performance tests on it proceeds to show that the possibilities of running HLA as a plugin in Unity shows a lot of promise for 3D-applications designed in Unity communicating over HLA.

  • 510.
    Söderén, Martin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Online Transverse Beam Instability Detection in the LHC: High-Throughput Real-Time Parallel Data Analysis2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis presents the ADT transverse instability detection system, the next generation of instability detection in the LHC at CERN, Geneva. The system is presented after a thorough study of underlying causes for instabilities in high energy particle accelerators, current parallel programming paradigms, the available hardware and software at CERN and possible instability detection techniques. The requirements for the system involve handling vast amounts of data which need to be analyzed in real-time and in this data detect rapid amplitude growth while limiting the computational resources required to a minimum. The result of this thesis was a system that could generate a trigger when an instability was detected, which was used to save data from observation instruments around the LHC. A fixed display in the CERN control centre was also created which allows scientists and operators at CERN to monitor the oscillation amplitude of all particle bunches. The conclusion is that the complete system will be a valuable asset at CERN to help further develop the LHC.

  • 511.
    Tahirovic, Mensur
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Övervakning av automatiserade processer2014Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Användning av datorsystem vare sig privat person eller företagare har blivit allt mer vanligare. Det förekommer olika typer av datorsystem och användningsområden kan variera. Efterfrågan av att kunna övervaka dessa datorsystem blir allt större och större. För att ta det ett steg längre, övervakning av datorsystem via mobila enheter blir allt mer efterfrågat.

    Företaget MMSOFT Design skapade ett program som heter Mobile PC Monitor. Med programmet ska man kunna övervaka en dator eller server oberoende vilken plattform som används. Övervakning ska även kunna ske mobilt genom att använda någon typ av mobil enhet.

    Det är detta område examensarbetet handlar om och det syftar till att ta fram en studie rörande möjligheten att utnyttja tekniken för att övervaka olika processer och att kunna utgöra en referenstillämpning av modulen när funktionen säljs in till andra kunder. Rapporten är även tänkt att kunna använda som handledning/underlag för användning av Mobile PC Monitor.

    För att få en uppfattning om hur Mobile PC Monitor fungerar och vilka funktioner programmet erbjuder så ägnades tid åt att läsa om Mobile PC Monitor på hemsidan, se ref 1. Vidare installerades datoragenten för att utforska och se vilka möjligheter och inställningar som var tillgängliga. Utöver detta så skrevs även en modul som länkades in i datoragenten för att övervaka publiceringar i ett Video On Demand-system.

    Den programmerade modulens funktion är att läsa och hämta data ur databasen för att övervaka systembelastning, genomflöde och systemstatus i ett Video On Demand-system, där man ser statistiken över olika publiceringstillstånd i systemet. Programmeringen gjordes i Microsoft Visual Studio 2012 och programspråket C# (C-Sharp) användes. Modulen förutsatte även en del databasprogrammering (SQL) för att få tillgång till nödvändiga data.

    Resultatet av examensarbetet är en studie av Mobile PC Monitor och dess funktioner samt en skriven modul. Resultatet av den skrivna modulen kan presenteras i mobila enheter, där man ser statistik för systembelastning, genomflöde och systemstatus.

  • 512.
    Tanasa, Bogdan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Bordoloi, Unmesh D.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Correlation-Aware Probabilistic Timing Analysis for the Dynamic Segment of FlexRay2016Ingår i: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 15, nr 3, s. 54:1-54:31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose an analytical framework for probabilistic timing analysis of the event-triggered Dynamic segment of the FlexRay communication protocol. Specifically, our framework computes the Deadline Miss Ratio of each message. The core problem is formulated as a Mixed Integer Linear Program (MILP). Given the intractability of the problem, we also propose several techniques that help to mitigate the running times of our tool. This includes the re-engineering of the problem to run it on GPUs as well as reformulating the MILP itself.

    Most importantly, we also show how our framework can handle correlations between the queuing events of messages. This is challenging because one cannot apply the convolution operator in the same way as in the case of independent queuing events.

  • 513.
    Tanasa, Bogdan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Bordoloi, Unmesh D
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Probabilistic Response Time and Joint Analysis of Periodic Tasks2015Ingår i: PROCEEDINGS OF THE 2015 27TH EUROMICRO CONFERENCE ON REAL-TIME SYSTEMS (ECRTS 2015), IEEE Communications Society, 2015, s. 235-246Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we address the problem of computing the probability response time distribution of periodic tasks scheduled on a uniprocessor systems. Our framework assumes an arbitrary non-idling preemptive scheduling policy that may be either a fixed-priority scheduler (such as Rate Monotonic - RM) or a dynamic-priority scheduler (such as Earliest Deadline First - EDF). At the same time, our framework can handle arbitrary execution time distributions arbitrary deadlines providing numerically accurate results. We also show how the framework can be extended to compute the correlation coefficients between the response times of different jobs by performing the joint analysis.

  • 514.
    Tanasa, Bogdan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Bordoloi, Unmesh
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Probabilistic Timing Analysis for the Dynamic Segment of FlexRay2013Ingår i: 25th Euromicro Conference on Real-Time Systems (ECRTS), IEEE , 2013, s. 135-144Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose an analytical framework for probabilistic timing analysis of the event-triggered Dynamic segment of the FlexRay communication protocol. Specifically, our framework computes the Deadline Miss Ratios of each message. The core problem is formulated as a Mixed Integer Linear Program (MILP). Given the intractability of the problem, we also propose several techniques that help to mitigate the running times of our tool. This includes the re-engineering of the problem to run it on GPUs as well as re-formulating the MILP itself.

  • 515.
    Tanasa, Bogdan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Bordoloi, Unmesh
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Kosuch, Stefanie
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Schedulability Analysis for the Dynamic Segment of FlexRay: A Generalization to Slot Multiplexing2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    FlexRay, developed by a consortium of over hundred automotive companies, is a real-time communication protocol for automotive networks. In this paper, we propose a new approach for timing analysis of the event-triggered component of FlexRay, known as the dynamic segment. Our technique accounts for the fact that the FlexRay standard allows slot multiplexing, i.e., the same priority can be assigned to more than one message. Existing techniques have either ignored slot multiplexing in their analysis or made simplifying assumptions that severely limit achieving high bandwidth utilization. Moreover, we show that our technique returns less pessimistic results compared to previously known techniques even in the case where slot multiplexing is ignored.

  • 516.
    Thiele, Bernhard Amadeus
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Knoll, A.
    Technical University of Munich, Germany.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Towards Qualifiable Code Generation from a Clocked Synchronous Subset of Modelica2015Ingår i: Modeling, Identification and Control, ISSN 0332-7353, E-ISSN 1890-1328, Vol. 36, nr 1, s. 23-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    So far no qualifiable automatic code generators (ACGs) are available for Modelica. Hence, digital control applications can be modeled and simulated in Modelica, but require tedious additional efforts (e.g., manual reprogramming) to produce qualifiable target system production code. In order to more fully leverage the potential of a model-based development (MBD) process in Modelica, a qualifiable automatic code generator is needed. Typical Modelica code generation is a fairly complex process which imposes a huge development burden to any efforts of tool qualification. This work aims at mapping a Modelica subset for digital control function development to a well-understood synchronous data-flow kernel language. This kernel language allows to resort to established compilation techniques for data-flow languages which are understood enough to be accepted by certification authorities. The mapping is established by providing a translational semantics from the Modelica subset to the synchronous data-flow kernel language. However, this translation turned out to be more intricate than initially expected and has given rise to several interesting issues that require suitable design decisions regarding the mapping and the language subset.

  • 517.
    Thiele, Bernhard
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pop, Adrian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Flattening of Modelica State Machines: a practical symbolic representation2015Ingår i: Proceedings of the 11th International Modelica Conference: Versailles, France, September 21-23, 2015 / [ed] Peter Fritzson, Hilding Elmqvist, Linköping: Linköping University Electronic Press, 2015, s. 255-263Konferensbidrag (Refereegranskat)
    Abstract [en]

    Modelica 3.3 introduced dedicated built-in language support for state machines that was inspired by semantics known from Statechart and mode automata formalisms. The specification describes the semantics of these constructs in terms of data-flow equations that allows to relate it to the Modelica DAE representation which is the conceptual intermediate format of Modelica code after instance creation (flattening). However, a complete transformation of state machine constructs into data-flow equations at the stage of flattening requires an early commitment to implementation details that potentially hinders model optimizations at subsequent translation phases. Also, due to the required substantial model transformation the semantic distance between the original source model and the flattened representation is rather large. Hence, this paper proposes a more versatile symbolic representation for flattened state machine constructs that preserves the state machine’s composition structure and allows postponing optimizations to subsequent compiler phases.

  • 518.
    Tholander, Oscar
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    System design for integration of faultisolation and recording tool for airplanes.2013Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis investigates the possibilities to design enterprise software after the REST architectural style and also look into how these kinds of systems can be developed using the .NET 4.0 Framework, Windows Communication Foundation (WCF) and EntityFramework 4.0. The thesis will in detail go through how to design the database abstraction to transferring the database content over a network, encoded with JSON to a client. The proposed solution is a viable way of designing network based software and is quite simple to implement when you get you head around the concepts of REST. The future in developing REST based applications is getting better and easier in the .NET Framework with added and improved support for in newer releases of the framework.

  • 519.
    Thomke, Sven
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Implementation av Microsoft Exchange ActiveSync mot en molntjänst2013Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report describes a bachelor thesis work performed at the cloud storage company CloudMe in Linköping, Sweden. The storage service provided by CloudMe allows users to access their files seamlessly from multiple units at the same time. In the cloud there is storage provided for contacts, calendar and e-mail, which is data nowadays normally used by smart phones.Exchange ActiveSync is a protocol developed by Microsoft which, among much more, provides functionality to synchronize the previously described data. This protocol is supported by the smart phone developers and the ability to synchronize over the exchange protocol is implemented in products by default. Due to this fact it would be preferable to implement support for synchronization from CloudMe to phones over this protocol. Therefore a decision was made to create a proxy server which handles communication with clients (smart phones) over Exchange ActiveSync and talks with CloudMes SOAP-based open API to extract the needed data. With the help of this server a user would be able to synchronize the described data between different phones and tablets, independently of label and model and would never have to worry about loss of data.The purpose of this bachelor thesis work was therefore to design and implement such a proxy server, so that clients would be able to connect, through the standard support for exchange in smart phones,and synchronize data between phones and the cloud. The report describes the methods used when designing the project and also the problems that occurred during the process.

  • 520.
    Thorarensen, Sebastian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    A Back-End for the SkePU Skeleton Programming Library targeting the Low-Power Multicore Vision Processor Myriad 22016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The SkePU skeleton programming library utilises algorithmic skeletons to offer a high-level approach for creating parallel applications. By using different back-ends, SkePU applications can run on multicore systems, GPGPU systems, and computer clusters.

    Myriad 2 is a low-power multicore vision processor for embedded systems, capable of running parallel applications energy-efficiently. Myriad 2 is heterogeneous, containing two different processor architectures and memories with different characteristics.

    In this thesis, we implement a back-end for SkePU, that allows SkePU applications to run on Myriad 2. We describe how the back-end is designed and evaluate the performance of SkePU applications running on Myriad 2. By conducting a series of benchmarks, we show that our back-end achieves enough performance to make SkePU a useful tool for creating applications for Myriad 2. We also show that SkePU applications can run more energy-efficiently on Myriad 2, compared to a GPGPU system.

  • 521.
    Thorarensen, Sebastian
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Cuello, Rosandra
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Kessler, Christoph
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Li, Lu
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Barry, Brendan
    Movidius Ltd, Ireland.
    Efficient Execution of SkePU Skeleton Programs on the Low-power Multicore Processor Myriad22016Ingår i: 2016 24TH EUROMICRO INTERNATIONAL CONFERENCE ON PARALLEL, DISTRIBUTED, AND NETWORK-BASED PROCESSING (PDP), IEEE , 2016, s. 398-402Konferensbidrag (Refereegranskat)
    Abstract [en]

    SkePU is a state-of-the-art skeleton programming library for high-level portable programming and efficient execution on heterogeneous parallel computer systems, with a publically available implementation for general-purpose multicore CPU and multi-GPU systems. This paper presents the design, implementation and evaluation of a new back-end of the SkePU skeleton programming library for the new low-power multicore processor Myriad2 by Movidius Ltd. This enables seamless code portability of SkePU applications across both HPC and embedded (Myriad2) parallel computing systems, with decent performance, on these architecturally very diverse types of execution platforms.

  • 522.
    Thorslund, Gustaf
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Simulating Partial Differential Equations using the Explicit Parallelism of ParModelica2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Modelica language is a modelling and programming  language for modelling cyber-physical systems using equations and  algorithms. In this thesis two suggested extensions of the Modelica  language are covered. Those are Partial Differential Equations (PDE)  and explicit parallelism in algorithmic code.  While PDEs are not  yet supported by the Modelica language, this thesis presents a  framework for solving PDEs using the algorithmic part of the  Modelica language, including parallel extensions. Different  numerical solvers have been implemented using the explicit parallel  constructs suggested for Modelica by the ParModelica language  extensions, and implemented as part of OpenModelica. The solvers  have been evaluated using different models, and it can be seen how  bigger models are suitable for a parallel solver. The intention has  been to write a framework suitable for modelling and parallel  simulation of PDEs. This work can, however, also be seen as a case  study of how to write a custom solver using parallel algorithmic  Modelica and how to evaluate the performance of a parallel solver.

  • 523.
    Timliden, Erik
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Domain-Specific Language data- validation and manipulation in a case handlingsystem2014Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I denna rapport utvecklas ett Domän-Specifikt Språk (DSL) och integreras i ärehanterings systemet iipax. Implementationen undersökte fördelar med Domän-Specifika Språk. Rapporten ägnade sig åt agil mjukvaruutveckling och resulterade i ett fungerande Domän-Specifikt Språk som efterliknandar engelska.

  • 524.
    Toczé, Klervie
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Functional Reactive Programming as programming model for telecom server software2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis studies the use of the functional reactive programming (FRP) framework reactive-banana in a prototype which simulates a part of a Long-Term Evolution (LTE) base station: the Radio Resource Control connection setup procedure. The investigated problem is to determine whether using this FRP framework leads to an implementation with suitable performance and improved maintainability compared to the current implementation. Enhancing the maintainability of the base station software enables quicker and more efficient maintenance activities, which lead to an improved customer satisfaction. Moreover, it means that less programmers need to work on maintenance, so they can work on developing new products instead.

    In order to compare the use of the FRP paradigm to the one currently used in the base station implementation, the object-oriented programming (OOP) paradigm, a second prototype using this paradigm was also implemented. Having two prototypes implementing the same designed reference model (which is a simplified version of the Radio Resource Control connection setup procedure) enables a relevant comparison of the two paradigms. The two prototypes were then compared in terms of performance and maintainability. The maintainability evaluation consisted in using both software metrics and experts’ assessment, as this has been proven to be the most efficient way to evaluate software maintainability. Four experts were asked to fill in a questionnaire after reviewing the code of the two implementations.

    The comparison of the two prototypes indicates that the FRP prototype is more maintainable than the OOP one, but the OOP prototype has better performances than the FRP one. Moreover, the performance of the FRP prototype during the conducted tests indicates that such an implementation of the FRP paradigm is not suitable for a real base station.

  • 525.
    Toczé, Klervie
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    A Taxonomy for Management and Optimization of Multiple Resources in Edge Computing2018Ingår i: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, artikel-id 7476201Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Edge computing is promoted to meet increasing performance needs of data-driven services using computational and storage resources close to the end devices at the edge of the current network. To achieve higher performance in this new paradigm, one has to consider how to combine the efficiency of resource usage at all three layers of architecture: end devices, edge devices, and the cloud. While cloud capacity is elastically extendable, end devices and edge devices are to various degrees resource-constrained. Hence, an efficient resource management is essential to make edge computing a reality. In this work, we first present terminology and architectures to characterize current works within the field of edge computing. Then, we review a wide range of recent articles and categorize relevant aspects in terms of 4 perspectives: resource type, resource management objective, resource location, and resource use. This taxonomy and the ensuing analysis are used to identify some gaps in the existing research. Among several research gaps, we found that research is less prevalent on data, storage, and energy as a resource and less extensive towards the estimation, discovery, and sharing objectives. As for resource types, the most well-studied resources are computation and communication resources. Our analysis shows that resource management at the edge requires a deeper understanding of how methods applied at different levels and geared towards different resource types interact. Specifically, the impact of mobility and collaboration schemes requiring incentives are expected to be different in edge architectures compared to the classic cloud solutions. Finally, we find that fewer works are dedicated to the study of nonfunctional properties or to quantifying the footprint of resource management techniques, including edge-specific means of migrating data and services.

  • 526.
    Toczé, Klervie
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Where Resources meet at the Edge2017Ingår i: 2017 IEEE INTERNATIONAL CONFERENCE ON COMPUTER AND INFORMATION TECHNOLOGY (CIT), IEEE , 2017, s. 302-307Konferensbidrag (Refereegranskat)
    Abstract [en]

    Edge computing is a recent paradigm where network nodes are placed close to the end users, at the edge of the network. Efficient management of resources within this configuration is crucial due to scarcity and geographical spreading of edge resources. We begin by a brief description of the edge paradigm, the most generic edge architecture, and the terminology associated to it. Then, we propose and elaborate on a preliminary taxonomy for edge resource management, together with a substantial review of works in the area. Finally, we identify some research challenges.

  • 527.
    Toczé, Klervie
    et al.
    Ericsson AB, Linköping, Sweden.
    Vasilevskaya, Maria
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sandahl, Patrik
    Ericsson AB, Linköping, Sweden.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Maintainability of Functional Reactive Programs in a Telecom Server Software2016Ingår i: SAC '16 Proceedings of the 31st Annual ACM Symposium on Applied Computing, Association for Computing Machinery (ACM), 2016, s. 2001-2003Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Functional Reactive Programming (FRP) is claimed to be a good choice for event handling applications. Current object- oriented telecom applications are known to suffer from additional complexity due to event handling code. In this paper we study the maintainability of FRP programs in the tele- com domain compared to traditional object-oriented programming (OOP), with the motivation that higher maintainability increases the service quality and decreases the costs. Two implementations of the same procedure are created: one using Haskell and the reactive-banana FRP frame- work and one using C++ and the OOP paradigm. Four software experts each with over 20 years of experience and three development engineers working on a product subject to study were engaged in evaluations, based on a questionnaire involving five different aspects of maintainability. The evaluations indicate a higher maintainability profile for FRP compared with OOP. This is confirmed by a more detailed analysis of the code size. While performance was not a main criteria, a preliminary evaluation shows that the OOP prototype is 8-10 times faster than the FRP prototype in the current (non-optimised) implementations.

  • 528.
    Torggler, Manfred
    et al.
    Fernuniv, Germany.
    Keller, Joerg
    Fernuniv, Germany.
    Kessler, Christoph
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Asymmetric Crown Scheduling2017Ingår i: 2017 25TH EUROMICRO INTERNATIONAL CONFERENCE ON PARALLEL, DISTRIBUTED AND NETWORK-BASED PROCESSING (PDP 2017), IEEE , 2017, s. 421-425Konferensbidrag (Refereegranskat)
    Abstract [en]

    Streaming applications are often used for embedded and high-performance multi and manycore processors. Achieving high throughput without wasting energy can be achieved by static scheduling of parallelizable tasks with frequency scaling. We present asymmetric crown scheduling, which improves on the static crown scheduling approach by allowing flexible split ratios when subdividing processor groups. We formulate the scheduler as an integer linear program and evaluate it with synthetic task sets. The results demonstrate that a small number of split ratios improves energy efficiency of crown schedules by up to 12% with slightly higher scheduling time.

  • 529.
    Tufvesson, Hampus
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Impact of automated validation on software model quality2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Model driven development is gaining momentum, and thus, larger and more complex systems are being represented and developed with the help of modeling. Complex systems often suffer from a number of problems such as difficulties in keeping the model understandable, long compilation times and high coupling. With modeling comes the possibility to validate the models against constraints, which makes it possible to handle problems that traditional static analysis tools can't solve. This thesis is a study on to what degree the usage of automatic model validation can be a useful tool in addressing some of the problems that appear in the development of complex systems. This is done by compiling a list of validation constraints based on existing problems, implementing and applying fixes for these and measuring how a number of different aspects of the model is affected. After applying the fixes and measuring the impact on the models ,it could be seen that validation of dependencies can have a signicant impact on the models by reducing build times of the generated code. Other types of validation constraints require further study to decide what impact they might have on model quality.

  • 530.
    Udd, Robert
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Anomaly Detection in SCADA Network Traffic2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Critical infrastructure provides us with the most important parts of modern society, electricity, water and transport. To increase efficiency and to meet new demands from the customer remote monitoring and control of the systems is necessary. This opens new ways for an attacker to reach the Supervisory Control And Data Acquisition (SCADA) systems that control and monitors the physical processes involved. This also increases the need for security features specially designed for these settings. Anomaly-based detection is a technique suitable for the more deterministic SCADA systems. This thesis uses a combination of two techniques to detect anomalies. The first technique is an automatic whitelist that learns the behavior of the network flows. The second technique utilizes the differences in arrival times of the network packets. A prototype anomaly detector has been developed in Bro. To analyze the IEC 60870-5-104 protocol a new parser for Bro was also developed. The resulting anomaly detector was able to achieve a high detection rate for three of the four different types of attacks evaluated. The studied methods of detection are promising when used in a highly deterministic setting, such as a SCADA system.

  • 531.
    Udd, Robert
    et al.
    Sectra AB, Linköping, Sweden.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Kazemtabrizi, Mehrdad
    The Royal Institute of Technology, Stockholm, Sweden.
    Ekstedt, Mathias
    The Royal Institute of Technology, Stockholm, Sweden.
    Exploiting Bro for Intrusion Detection in a SCADA System2016Ingår i: Proceedings of the 2nd ACM International Workshop on Cyber-Physical System Security, ACM Digital Library, 2016, s. 44-51Konferensbidrag (Refereegranskat)
    Abstract [en]

    Supervisory control and data acquisition (SCADA) systemsthat run our critical infrastructure are increasingly run withInternet-based protocols and devices for remote monitoring.The embedded nature of the components involved, and thelegacy aspects makes adding new security mechanisms in anefficient manner far from trivial. In this paper we studyan anomaly detection based approach that enables detect-ing zero-day malicious threats and benign malconfigurationsand mishaps. The approach builds on an existing platform(Bro) that lends itself to modular addition of new proto-col parsers and event handling mechanisms. As an examplewe have shown an application of the technique to the IEC-60870-5-104 protocol and tested the anomaly detector withmixed results. The detection accuracy and false positiverate, as well as real-time response was adequate for 3 ofour 4 created attacks. We also discovered some additionalwork that needs to be done to an existing protocol parser toextend its reach.

  • 532.
    Ukhov, Ivan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    System-Level Analysis and Design under Uncertainty2017Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    One major problem for the designer of electronic systems is the presence of uncertainty, which is due to phenomena such as process and workload variation. Very often, uncertainty is inherent and inevitable. If ignored, it can lead to degradation of the quality of service in the best case and to severe faults or burnt silicon in the worst case. Thus, it is crucial to analyze uncertainty and to mitigate its damaging consequences by designing electronic systems in such a way that uncertainty is effectively and efficiently taken into account.

    We begin by considering techniques for deterministic system-level analysis and design of certain aspects of electronic systems. These techniques do not take uncertainty into account, but they serve as a solid foundation for those that do. Our attention revolves primarily around power and temperature, as they are of central importance for attaining robustness and energy efficiency. We develop a novel approach to dynamic steady-state temperature analysis of electronic systems and apply it in the context of reliability optimization.

    We then proceed to develop techniques that address uncertainty. The first technique is designed to quantify the variability in process parameters, which is induced by process variation, across silicon wafers based on indirect and potentially incomplete and noisy measurements. The second technique is designed to study diverse system-level characteristics with respect to the variability originating from process variation. In particular, it allows for analyzing transient temperature profiles as well as dynamic steady-state temperature profiles of electronic systems. This is illustrated by considering a problem of design-space exploration with probabilistic constraints related to reliability. The third technique that we develop is designed to efficiently tackle the case of sources of uncertainty that are less regular than process variation, such as workload variation. This technique is exemplified by analyzing the effect that workload units with uncertain processing times have on the timing-, power-, and temperature-related characteristics of the system under consideration.

    We also address the issue of runtime management of electronic systems that are subject to uncertainty. In this context, we perform an early investigation into the utility of advanced prediction techniques for the purpose of fine-grained long-range forecasting of resource usage in large computer systems.

    All the proposed techniques are assessed by extensive experimental evaluations, which demonstrate the superior performance of our approaches to analysis and design of electronic systems compared to existing techniques.

  • 533.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Bao, Min
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Steady-State Dynamic Temperature Analysis and Reliability Optimization for Embedded Multiprocessor Systems2012Ingår i: 49th ACM/EDAC/IEEE Design Automation Conference (DAC), 3-7 June 2012, San Francisco, ACM/ IEEE , 2012, s. 197-204Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we propose an analytical technique for the steady-state dynamic temperature analysis (SSDTA) of multiprocessor systems with periodic applications. The approach is accurate and, moreover, fast, such that it can be included inside an optimization loop for embedded system design. Using the proposed solution, a temperature-aware reliability optimization, based on the thermal cycling failure mechanism, is presented. The experimental results con firm the quality and speed of our SSDTA technique, compared to the state of the art. They also show that the lifetime of an embedded system can significantly be improved, without sacrificing its energy efficiency, by taking into consideration, during the design stage, the steady-state dynamic temperature profile of the system.

  • 534.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Probabilistic Analysis of Electronic Systems via Adaptive Hierarchical Interpolation2017Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, ISSN 0278-0070, E-ISSN 1937-4151, Vol. 36, nr 11, s. 1883-1896Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a framework for system-level analysis of electronic systems whose runtime behaviors depend on uncertain parameters. The proposed approach thrives on hierarchical interpolation guided by an advanced adaptation strategy, which makes the framework general and suitable for studying various metrics that are of interest to the designer. Examples of such metrics include the end-to-end delay, total energy consumption, and maximum temperature of the system under consideration. The framework delivers a light generative representation that allows for a straightforward, computationally efficient calculation of the probability distribution and accompanying statistics of the metric at hand. Our technique is illustrated by considering a number of uncertainty-quantification problems and comparing the corresponding results with exhaustive simulations.

  • 535.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Probabilistic Analysis of Power and Temperature Under Process Variation for Electronic System Design2014Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, ISSN 0278-0070, E-ISSN 1937-4151, Vol. 33, nr 6, s. 931-944Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electronic system design based on deterministic techniques for power-temperature analysis is, in the context of current and future technologies, both unreliable and inefficient since the presence of uncertainty, in particular, due to process variation, is disregarded. In this paper, we propose a flexible probabilistic framework targeted at the quantification of the transient power and temperature variations of an electronic system. The framework is capable of modeling diverse probability laws of the underlying uncertain parameters and arbitrary dependencies of the system on such parameters. For the considered system, under a given workload, our technique delivers analytical representations of the corresponding stochastic power and temperature profiles. These representations allow for a computationally efficient estimation of the probability distributions and accompanying quantities of the power and temperature characteristics of the system. The approximation accuracy and computational time of our approach are assessed by a range of comparisons with Monte Carlo simulations, which confirm the efficiency of the proposed technique.

  • 536.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Temperature-Centric Reliability Analysis and Optimization of Electronic Systems under Process Variation2015Ingår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 23, nr 11, s. 2417-2430Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electronic system designs that ignore process variationare unreliable and inefficient. In this paper, we propose asystem-level framework for the analysis of temperature-inducedfailures that considers the uncertainty due to process variation.As an intermediate step, we also develop a probabilistic techniquefor dynamic steady-state temperature analysis. Given an electronicsystem under a certain workload, our framework deliversthe corresponding survival function, founded on the basis ofwell-established reliability models, with a closed-form stochasticparameterization in terms of the quantities that are uncertain atthe design stage. The proposed solution is exemplified consideringsystems with periodic workloads that suffer from the thermalcyclingfatigue. The analysis of this fatigue is a challengingproblem as it requires the availability of detailed temperatureprofiles, which are uncertain due to the variability of processparameters. To demonstrate the computational efficiency of ourframework, we undertake a design-space exploration procedureto minimize the expected energy consumption under a set oftiming, thermal, and reliability constraints.

  • 537.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Marculescu, Diana
    Department of Electrical and Computer Engineering, Carnegie Mellon University, USA.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fast Synthesis of Power and Temperature Profiles for the Development of Data-Driven Resource Managers2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The goal of this work is to facilitate the development of proactive power- and temperature-aware resource managers that leverage machine learning in order to attain their objectives. In this context, the availability of sufficiently large amounts of relevant data, which are essential for learning and, therefore, exploration of research ideas, is elusive. In order to fulfill the need, we present a toolchain for fast generation of realistic power and temperature profiles of computer systems. The toolchain provides profuse representative data to learn from during development stages. The overreaching objective is to help research by making it tractable to experiment with the highly promising but data-demanding state-of-the-art techniques for prediction.

  • 538.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Marculescu, Diana
    Department of Electrical and Computer Engineering, Carnegie Mellon University, USA.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fine-Grained Long-Range Prediction of Resource Usage in Computer Clusters2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In order to facilitate the development of intelligent resource managers of computer clusters, we investigate the utility of the state-of-the-art neural networks for the purpose of fine-grained long-range prediction of the resource usage in one such cluster. We consider a large data set of real-life traces and describe in detail our workflow, starting from making the data accessible for learning and finishing by predicting the resource usage of individual tasks multiple steps ahead. The experimental results indicate that such fine-grained traces as the ones considered possess a certain structure, and that this structure can be extracted by advanced machine-learning techniques and subsequently utilized for making informed predictions.

  • 539.
    Ukhov, Ivan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Villani, Mattias
    Linköpings universitet, Institutionen för datavetenskap, Statistik. Linköpings universitet, Filosofiska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Statistical Analysis of Process Variation Based on Indirect Measurements for Electronic System Design2014Ingår i: 2014 19TH ASIA AND SOUTH PACIFIC DESIGN AUTOMATION CONFERENCE (ASP-DAC), New York: IEEE conference proceedings, 2014, s. 436-442Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a framework for the analysis of process variation across semiconductor wafers. The framework is capable of quantifying the primary parameters affected by process variation, e.g., the effective channel length, which is in contrast with the former techniques wherein only secondary parameters were considered, e.g., the leakage current. Instead of taking direct measurements of the quantity of interest, we employ Bayesian inference to draw conclusions based on indirect observations, e.g., on temperature. The proposed approach has low costs since no deployment of expensive test structures might be needed or only a small subset of the test equipments already deployed for other purposes might need to be activated. The experimental results present an assessment of our framework for a wide range of configurations.

  • 540.
    Uppman, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Computational Complexity of the Minimum Cost Homomorphism Problem on Three-element Domains2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we study the computational complexity of the extended minimum cost homomorphism problem (Min-Cost-Hom) as a function of a constraint language, i.e. a set of constraint relations and cost functions that are allowed to appear in instances. A wide range of natural combinatorial optimisation problems can be expressed as extended Min-Cost-Homs and a classification of their complexity would be highly desirable, both from a direct, applied point of view as well as from a theoretical perspective.

    The extended Min-Cost-Hom can be understood either as a flexible optimisation version of the constraint satisfaction problem (CSP) or a restriction of the (general-valued) valued constraint satisfaction problem (VCSP). Other optimisation versions of CSPs such as the minimum solution problem (Min-Sol) and the minimum ones problem (Min-Ones) are special cases of the extended Min-Cost-Hom.

    The study of VCSPs has recently seen remarkable progress. A complete classification for the complexity of finite-valued languages on arbitrary finite domains has been obtained Thapper and Živný [STOC’13]. However, understanding the complexity of languages that are not finitevalued appears to be more difficult. The extended Min-Cost-Hom allows us to study problematic languages of this type without having to deal with with the full generality of the VCSP. A recent classification for the complexity of three-element Min-Sol, Uppman [ICALP’13], takes a step in this direction. In this paper we generalise this result considerably by determining the complexity of three-element extended Min-Cost-Hom.

  • 541.
    Uppman, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Max-Sur-CSP on Two Elements2012Ingår i: Principles and Practice of Constraint Programming: 18th International Conference, CP 2012, Québec City, QC, Canada, October 8-12, 2012. Proceedings / [ed] Michela Milano, Springer Berlin Heidelberg , 2012, s. 38-54Konferensbidrag (Refereegranskat)
    Abstract [en]

    Max-Sur-CSP is the following optimisation problem: given a set of constraints, find a surjective mapping of the variables to domain values that satisfies as many of the constraints as possible. Many natural problems, e.g. Minimum k-Cut (which has many different applications in a variety of fields) and Minimum Distance (which is an important problem in coding theory), can be expressed as Max-Sur-CSPs. We study Max-Sur-CSP on the two-element domain and determine the computational complexity for all constraint languages (families of allowed constraints). Our results show that the problem is solvable in polynomial time if the constraint language belongs to one of three classes, and NP-hard otherwise. An important part of our proof is a polynomial-time algorithm for enumerating all near-optimal solutions to a generalised minimum cut problem. This algorithm may be of independent interest.

  • 542.
    Uppman, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    On Some Combinatorial Optimization Problems: Algorithms and Complexity2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is about the computational complexity of several classes of combinatorial optimization problems, all related to the constraint satisfaction problems.

    A constraint language consists of a domain and a set of relations on the domain. For each such language there is a constraint satisfaction problem (CSP). In this problem we are given a set of variables and a collection of constraints, each of which is constraining some variables with a relation in the language. The goal is to determine if domain values can be assigned to the variables in a way that satisfies all constraints. An important question is for which constraint languages the corresponding CSP can be solved in polynomial time. We study this kind of question for optimization problems related to the CSPs.

    The main focus is on extended minimum cost homomorphism problems. These are optimization versions of CSPs where instances come with an objective function given by a weighted sum of unary cost functions, and where the goal is not only to determine if a solution exists, but to find one of minimum cost. We prove a complete classification of the complexity for these problems on three-element domains. We also obtain a classification for the so-called conservative case.

    Another class of combinatorial optimization problems are the surjective maximum CSPs. These problems are variants of CSPs where a non-negative weight is attached to each constraint, and the objective is to find a surjective mapping of the variables to values that maximizes the weighted sum of satisfied constraints. The surjectivity requirement causes these problems to behave quite different from for example the minimum cost homomorphism problems, and many powerful techniques are not applicable. We prove a dichotomy for the complexity of the problems in this class on two-element domains. An essential ingredient in the proof is an algorithm that solves a generalized version of the minimum cut problem. This algorithm might be of independent interest.

    In a final part we study properties of NP-hard optimization problems. This is done with the aid of restricted forms of polynomial-time reductions that for example preserves solvability in sub-exponential time. Two classes of optimization problems similar to those discussed above are considered, and for both we obtain what may be called an easiest NP-hard problem. We also establish some connections to the exponential time hypothesis.

  • 543.
    Uppman, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    The Complexity of Three-Element Min-Sol and Conservative Min-Cost-Hom2013Ingår i: Automata, Languages, and Programming: 40th International Colloquium, ICALP 2013, Riga, Latvia, July 8-12, 2013, Proceedings, Part I / [ed] Fedor V. Fomin, Rūsiņš Freivalds, Marta Kwiatkowska, David Peleg, Springer Berlin/Heidelberg, 2013, s. 804-815Konferensbidrag (Refereegranskat)
    Abstract [en]

    Thapper and Živný [STOC’13] recently classified the complexity of VCSP for all finite-valued constraint languages. However, the complexity of VCSPs for constraint languages that are not finite-valued remains poorly understood. In this paper we study the complexity of two such VCSPs, namely Min-Cost-Hom and Min-Sol. We obtain a full classification for the complexity of Min-Sol on domains that contain at most three elements and for the complexity of conservative Min-Cost-Hom on arbitrary finite domains. Our results answer a question raised by Takhanov [STACS’10, COCOON’10].

  • 544.
    Usman, Muhammad
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Framework for Within Day Rescheduling due to UnexpectedIncidents in Transportation Networks2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In activity based modelling the concept of rescheduling is very important in order to gain dynamic scheduling of activities and to adjust the effect of unexpected incidents in individual agendas to keep them realistic and valid. This report describes a new framework to investigate algorithms for rescheduling on a large scale. This framework models the information of traffic demand and results of micro simulation of traffic on a loaded network; it enables agents to adapt their schedules by providing them with information about the traffic flow. A perception filter for each agent is included in this framework. It models the concept that some agents can notice the broadcast traffic information about the incident and get their own prediction of the expected delay, while other agents who do not notice the information can become aware only by experiencing traffic jam. Initial agendas are created by means of the FEATHERS activity based schedule generator for mutually independent agents. FEATHERS has no knowledge about the actual transportation network but makes use of an impedance matrix that specifies the minimal travel time between traffic analysis zones. The matrix specifies a free-flow value for the uncongested case and correction values for the loaded network. In this new framework the network state can be changed by agent behaviour and external incidents; the effect of this change in network state is perceived differently by each agent through a perception filter, and according to the perceived value individual adaption is calculated by a ReScheduler. The modified behaviour again creates new traffic demand hence creating a new traffic state; this phenomenon continues for the complete day. Each activity in the agenda is assumed to generate some utility. Each individual is assumed to maximize the total utility over the day. The ReScheduler is implemented using a marginal utility function that monotonically decreases with activity duration. This results in a monotonically converging relaxation algorithm to efficiently determine the new activity timing when less time is available for activities due to increased travel time caused by the incident.

  • 545.
    Vasconcelos Jansson, Erik Sven
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Analysis of Test Coverage Data on a Large-Scale Industrial System2016Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Software testing verifies the program's functional behavior, one important process when engineering critical software. Measuring the degree of testing is done with code coverage, describing the amount of production code affected by tests. Both concepts are extensively used for industrial systems. Previous research has shown that gathering and analyzing test coverages becomes problematic on large-scale systems. Here, development experience, implementation feasibility, coverage measurements and analysis method are explored; providing potential solutions and insights into these issues.

    Outlined are methods for constructing and integrating such gathering and analysis system in a large-scale project, along with the problems encountered and given remedies. Instrumentations for gathering coverage information affect performance negatively, these measurements are provided. Since large-scale test suite measurements are quite lacking, the line, branch, and function criteria are presented here. Finally, an analysis method is proposed, by using coverage set operations and Jaccard indices, to find test similarities.

    Results gathered imply execution time was significantly affected when gathering coverage, [2.656, 2.911] hours for instrumented software, originally between [2.075, 2.260] on the system under test, given under the alpha = 5% and n = 4, while both processor & memory usages were inconclusive. Measured criteria were (59.3, 70.7, 24.6)% for these suites. Analysis method shows potential areas of test redundancy.

  • 546.
    Vasilevskaya, Maria
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Ariani Gunawan, Linda
    Norwegian University of Science and Technology, NTNU.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Herrmann, Peter
    Norwegian University of Science and Technology, NTNU.
    Integrating security mechanisms into embedded systems by domain-specific modelling2014Ingår i: Security and Communication Networks, ISSN 1939-0114, E-ISSN 1939-0122, Vol. 7, nr 12, s. 2815-2832Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Embedded devices are crucial enablers of the Internet of Things and become increasingly common in our daily life. They store, manipulate and transmit sensitive information and, therefore, must be protected against security threats. Due to the security and also resource constraint concerns, designing secure networked embedded systems is a difficult task. Model-based development (MBD) is promoted to address complexity and ease the design of software intensive systems. We leverage MBD and domain-specific modelling to characterise common issues related to security and embedded systems that are specific to a given application domain. Security-specific knowledge relevant for a certain application domain is represented in the form of an adapted information security ontology. Further, the elements of the ontology are associated with security building blocks modelled with the MBD method SPACE. The selection of relevant security building blocks is based on (i) assets automatically elicited from the functional models, (ii) domain security knowledge captured by the security expert and (iii) the platform adopted by the embedded system engineer. A tool is developed to support the steps supporting this methodology and help to bridge between the security and embedded systems domains. We illustrate our approach with a case study from the smart metering domain.

  • 547.
    Vasilevskaya, Maria
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Broman, David
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Sandahl, Kristian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    An Assessment Model for Large Project Courses2014Ingår i: Proceedings of the 45th ACM Technical Symposium on Computer Science Education (SIGCSE), Association for Computing Machinery (ACM), 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Larger project courses, such as capstone projects, are essential in a modern computing curriculum. Assessing such projects is, how- ever, extremely challenging. There are various aspects and trade-offs of assessments that can affect the quality of a project course. Individual assessments can give fair grading of individuals, but may loose focus of the project as a group activity. Extensive teacher involvement is necessary for objective assessment, but may affect the way students are working. Continuous feedback to students can enhance learning, but may be hard to combine with fair assessment. Most previous work is focusing on some specific assessment aspect, whereas we in this paper present an assessment model that consists of a collection of assessment activities, each covering different aspects. We have applied, developed, and improved these activities during a six-year period and evaluated their usefulness by performing a questionnaire-based survey.

  • 548.
    Vasilevskaya, Maria
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Broman, David
    KTH Royal Institute of Technology, Stockholm, Sweden; University of California, Berkeley, USA.
    Sandahl, Kristian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Assessing Large Project Courses: Model, Activities, and Lessons Learned2015Ingår i: ACM Transactions on Computing Education, ISSN 1946-6226, E-ISSN 1946-6226, Vol. 15, nr 4, s. 20:1-20:30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a modern computing curriculum, large project courses are essential to give students hands-on experience of working in a realistic software engineering project. Assessing such projects is, however, extremely challenging. There are various aspects and tradeoffs of assessments that can affect the course quality. Individual assessments can give fair grading of individuals, but may loose focus of the project as a group activity. Extensive teacher involvement is necessary for objective assessment, but may affect the way students are working. Continuous feedback to students can enhance learning, but may be hard to combine with fair assessment. Most previous work is focusing on some specific assessment aspect, whereas we in this paper present an assessment model that consists of a collection of assessment activities, each covering different aspects. We have applied, developed, and improved these activities during a seven-year period. To evaluate the usefulness of the model, we perform questionnaire-based surveys over a two-years period. Furthermore, we design and execute an experiment that studies to what extent students can perform fair peer assessment and to what degree the assessments of students and teachers agree. We analyze the results, discuss findings, and summarize lessons learned.

  • 549.
    Vasilevskaya, Maria
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Linda, Ariani Gunawan
    Norwegian University of Science and Technology, Trondheim, Norway.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peter, Herrmann
    Norwegian University of Science and Technology, Trondheim, Norway.
    Security Asset Elicitation for Collaborative Models2012Ingår i: MDsec '12 Proceedings of the Workshop on Model-Driven Security, ACM Digital Library , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Building secure systems is a difficult job for most engineers since it requires in-depth understanding of security aspects. This task, however, can be assisted by capturing security knowledge in a particular domain and reusing the knowl- edge when designing applications. We use this strategy and employ an information security ontology to represent the se- curity knowledge. The ontology is associated with system designs which are modelled in collaborative building blocks specifying the behaviour of several entities. In this paper, we identify rules to be applied to the elements of collaborations in order to identify security assets present in the design. Further, required protection mechanisms are determined by applying a reasoner to the ontology and the obtained assets. We exemplify our approach with a case study from the smart metering domain. 

  • 550.
    Vasilevskaya, Maria
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Quantifying Risks to Data Assets Using Formal Metrics in Embedded System Design2015Ingår i: Computer Safety, Reliability, and Security: 34th International Conference, SAFECOMP 2015, Delft, The Netherlands, September 23-25, 2015, Proceedings / [ed] Floor Koornneef; Coen van Gulijk, Springer, 2015, Vol. 9337, s. 347-361Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses quantifying security risks associated with data assets within design models of embedded systems. Attack and system behaviours are modelled as time-dependent stochastic processes. The presence of the time dimension allows accounting for dynamic aspects of potential attacks and a system: the probability of a success- ful attack changes as time progresses; and a system possesses different data assets as its execution unfolds. These models are used to quan- tify two important attributes of security: confidentiality and integrity. In particular, likelihood/consequence-based measures of confidentiality and integrity losses are proposed to characterise security risks to data assets. In our method, we consider attack and system behaviours as two sepa- rate models that are later elegantly combined for security analysis. This promotes knowledge reuse and avoids adding extra complexity in the system design process. We demonstrate the effectiveness of the proposed method and metrics on smart metering devices. 

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