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  • 151.
    Alt, Helmut
    et al.
    Institut für Informatik, Freie Universität, Berlin, Germany .
    Arkin, Esther M
    Applied Mathematics and Statistics, Stony Brook University, Stony Brook, USA .
    Efrat, Alon
    Computer Science, The University of Arizona, Tucson, USA .
    Hart, George
    Hurtado, Ferran
    Departament de Matemàtica Aplicada II, Universitat Politècnica de Catalunya, Barcelona, Spain .
    Kostitsyna, Irina
    Computer Science, Stony Brook University, Stony Brook, USA .
    Kröller, Alexander
    Computer Science, Technische Universität Braunschweig, Braunschweig, Germany .
    Mitchell, Joseph SB
    Applied Mathematics and Statistics, Stony Brook University, Stony Brook, USA.
    Polishchuk, Valentin
    Helsinki Institute for IT, Computer Science, University of Helsinki, Helsinki, Finland .
    Scandinavian Thins on Top of Cake: New and Improved Algorithms for Stacking and Packing2014Inngår i: Theory of Computing Systems, ISSN 1432-4350, Vol. 54, nr 4, s. 689-714Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show how to compute the smallest rectangle that can enclose any polygon, from a given set of polygons, in nearly linear time; we also present a PTAS for the problem, as well as a linear-time algorithm for the case when the polygons are rectangles themselves. We prove that finding a smallest convex polygon that encloses any of the given polygons is NP-hard, and give a PTAS for minimizing the perimeter of the convex enclosure. We also give efficient algorithms to find the smallest rectangle simultaneously enclosing a given pair of convex polygons.

  • 152.
    Alvarsson, Andreas
    Linköpings universitet, Institutionen för datavetenskap.
    The development of a sports statistics web application: Sports Analytics and Data Models for a sports data web application2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Sports and technology have always co-operated to bring better and more specific sports statistics. The collection of sports game data as well as the ability to generate valuable sports statistics of it is growing. This thesis investigates the development of a sports statistics application that should be able to collect sports game data, structure the data according to suitable data models and show statistics in a proper way.

    The application was set to be a web application that was developed using modern web technologies. This purpose led to a comparison of different software stack solutions and web frameworks. A theoretical study of sports analytics was also conducted, which gave a foundation for how sports data could be stored and how valuable sports statistics could be generated.

    The resulting design of the prototype for the sports statistics application was evaluated. Interviews with persons working in sports contexts evaluated the prototype to be both user-friendly, functional and fulfilling the purpose to generate valuable statistics during sport games.

  • 153.
    Alvestig, Carl
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Informatik.
    Jägerud, Filip
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Informatik.
    Man måste brinna för att bli utbränd: En kvalitativ studie om orsaker till stress samt dess påverkan på IT-projektledare och IT-projekt2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Stress är ett växande problem i dagens samhälle. Anställda drabbas av utmattningssyndromoch tvingas sjukskriva sig under längre perioder vilket medför kostnader både för samhälletoch arbetsgivaren. Vissa yrkesgrupper är mer utsatta för stress än andra. Inom IT-branschensker utvecklingen väldigt snabbt vilket innebär att de anställda ständigt måste hålla siguppdaterade för att inte hamna efter. En projektledare har ett stort ansvar på sina axlar att ledaprojekt med i vårt fall uppemot 50 projektmedlemmar, detta kan vara ännu fler i störreorganisationer. Projekt av denna typ kan även omfatta stora budgetar och när ett sådantprojekt misslyckas får det stora konsekvenser. Där dessa två områden överlappar kan detonekligen uppstå stressande situationer.Vi har i denna uppsats undersökt vilka specifika situationer som stressar projektledare inomIT-projekt, hur de påverkas av denna stress samt vad det har för påverkan på projekten somde driver. Syftet med detta är att kunna förebygga stress i fortsättningen samt att visa på attdetta är ett utbrett problem inom den här branschen. Då kan det underlätta för projektledareatt söka hjälp ifall de vet att de inte är ensamma om problemet.För att undersöka detta så har vi utfört totalt fem stycken kvalitativa intervjuer uppdelade påtvå olika organisationer. En kommunal och en privat, vi gör dock inte någon djuparejämförelse angående just den aspekten då vårt urvalsområde är för smalt. Intervjuerna varsemistrukturerade för att tillåta följdfrågor och utfördes i enlighet med den dramaturgiskamodellen. Samtliga respondenter har stor erfarenhet av projektledning inom IT-branschenoch majoriteten jobbar idag som projektledare. Denna empiri analyseras sedan tillsammansmed tidigare forskning både inom stress samt projektområdet.Vårt resultat visar att samtliga projektledare känner av stress och att stressen går i vågor. Detfinns perioder då exempelvis ett oförutsett problem uppstår där stressnivån kan bliproblematisk. En respondent berättar om en projektledarkollega som blivit utbränd och därvår respondent fick ta över projektet. Men ingen av våra respondenter såg stressen som enanledning till ett karriärbyte. De uttryckte alla att de trivs bra och har tänkt fortsätta inombranschen. En av de viktigaste metoderna för att motverka stress som vi uppmärksammade äratt prioritera sina arbetsuppgifter och utföra dem i en logisk ordning istället för att ta sig anallting på en gång. Vi upptäckte även att smartphones bidrar med stress bland projektledarnadå de alltid har jobbet i fickan och på så sätt har svårt att slappna av och släppa jobbet påfritiden.

  • 154.
    Amadori, Kristian
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska högskolan.
    On Aircraft Conceptual Design: A Framework for Knowledge Based Engineering and Design Optimization2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents a design framework where analytical tools are linked together and operated from an efficient system level interface. The application field is aircraft conceptual design. Particular attention has been paid to CAD system integration and design optimization.

    Aircraft design is an inherently multidisciplinary process. The goal is to search for the design that, in the best of possible ways, fulfills the requirements. It is therefore desirable to be able to effectively investigate and analyze solutions from a variety of points of view, weighting together the results and gathering a general figure of merit. At the same time, increasing competition on a global market forces to shorten the design process and to reduce costs. Thus a system that allows a tight and efficient integration of different disciplines and improving data flow and storage plays a key role.

    Integrating a CAD system to the framework is of central relevance. The geometrical model includes most of the information; specific data, required to carry out particular analysis, can be extracted from it. This is possible adopting parametric associative models that are controlled from a spreadsheet user interface. Strategies for building CAD models with a very high degree of flexibility are presented. Not only the external shape can be changed, but also the internal structure can be completely modified. Structural elements can be added or removed, and their position and shaping changed.

    In this work the design of an Unmanned Aerial Vehicle is used as test case for comparing three different optimization algorithms. The presented framework is also used for automatically design Micro Aerial Vehicles, starting from a short list of requirements and ending with a physical prototype produced by a rapid prototyping machine.

    Delarbeid
    1. Use of Panel Code Modeling in a Framework for Aircraft Concept Optimization
    Åpne denne publikasjonen i ny fane eller vindu >>Use of Panel Code Modeling in a Framework for Aircraft Concept Optimization
    2006 (engelsk)Inngår i: 11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, 6-8 September, Portsmouth, Virginia, USA, 2006, s. 7084-Konferansepaper, Publicerat paper (Annet vitenskapelig)
    Abstract [en]

     

     

    In this study the use of a high-order panel code within a framework for aircraft concept design is discussed. The framework is intended to be a multidisciplinary optimization tool to be adopted from the very beginning of the conceptual design phase in order to define and refine the aircraft design, with respect to its aerodynamic, stability and control, structure and basic aircraft systems. The presented work is aimed at developing a module for aerodynamic analysis of concepts as a basis for a direct search optimization of the concept layout. The design criterion, used in the example presented here, is to minimize the maximum take-off weight required to fulfil the mission. Classic and simple equations are used together with the data generated by the panel code solver to calculate the aircraft’s performances. Weights are calculated by means of statistical group weight equations, but the weight could also be calculated from a CAD-model. The design of an Unmanned Combat Air Vehicle is used as test case for three different optimization algorithms: one gradient method based (Fmincon), one non-gradient based (Complex) and one Genetic Algorithm (GA). Comparison of results and performances shows that the Genetic Algorithm is best fitted for the specific problem, having the by far best hit rate, even if it is at a cost of longer computing time. The Complex algorithm requires less iterations and is also able to find the optimum solution, but with a worse hit rate, while Fmincon can not reach to a global optimum. The suggested optimized configuration for the aircraft is very similar to the Boeing X-45C and Northrop Grumman X-47B.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13306 (URN)
    Tilgjengelig fra: 2011-11-10 Laget: 2008-05-21 Sist oppdatert: 2011-12-16bibliografisk kontrollert
    2. A Framework for Aerodynamic and Structural Optimization in Conceptual Design
    Åpne denne publikasjonen i ny fane eller vindu >>A Framework for Aerodynamic and Structural Optimization in Conceptual Design
    2007 (engelsk)Inngår i: 25th AIAA Applied Aerodynamics Conference, 25-28 June, Miami, FL, USA, AIAA , 2007, s. 4061-Konferansepaper, Publicerat paper (Annet vitenskapelig)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of a new aircraft. In this work main attention has been paid to wing design, with respect to aerodynamic efficiency and loads, and to structural analysis. By linking together various modules via a user-friendly interface based on a spreadsheet, the framework allows multidisciplinary analysis and optimizations to be carried out. This paper will present the framework, give an overview of its development status and give an indication on the future work.

    sted, utgiver, år, opplag, sider
    AIAA, 2007
    Emneord
    Aircraft design, multi domain optimization
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13307 (URN)
    Tilgjengelig fra: 2008-05-21 Laget: 2008-05-21 Sist oppdatert: 2009-04-22
    3. Distributed Framework for Micro Aerial Vehicle Design Automation
    Åpne denne publikasjonen i ny fane eller vindu >>Distributed Framework for Micro Aerial Vehicle Design Automation
    2008 (engelsk)Inngår i: Proceedings from the 46th AIAA Aerospace Sciences Meeting and Exhibit, 7 - 10 January, Reno, NV, USA, AIAA , 2008, s. 140-Konferansepaper, Publicerat paper (Annet vitenskapelig)
    Abstract [en]

    Micro or mini aerial vehicles are characterized by being simple and inexpensive to build, and due to their small size very important to optimize. They are also likely to be built in relatively small series and be tailored for the sensors and equipment available at the time of deployment. Therefore "design and build on demand" is very attractive, where a modular concept with a more or less automated design process is desirable. In this paper design automation of a Micro or Mini Aerial Vehicle (MAV) is demonstrated using a distributed design optimization framework that involves selections of components from a database of propulsion system equipment and geometrical shape optimization. The framework links together a CAD system, responsible for the aircraft shape generation, with a panel code for aerodynamic evaluations.

     

    sted, utgiver, år, opplag, sider
    AIAA, 2008
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13308 (URN)978-1-62410-128-1 (ISBN)
    Konferanse
    46th AIAA Aerospace Sciences Meeting and Exhibit, 7 - 10 January, Reno, NV, USA
    Tilgjengelig fra: 2008-05-21 Laget: 2008-05-21 Sist oppdatert: 2012-10-17bibliografisk kontrollert
  • 155.
    Amanda, Jaber
    Linköpings universitet, Institutionen för datavetenskap.
    Evaluating the Team Resilience Assessment Method for Simulation (TRAMS)2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Team Resilience Assessment Method for Simulation (TRAMS) is an instrument that consist of several measurements, such as team-member exchange, workload, the TRAMS observation protocol etc. This thesis researches the observation protocol. The TRAMS protocol is an assessment method for resilience in simulation games. The aim of this protocol is to support the identification of resilience strategies used and developed by the participants in a simulation game. It is a challenge to assess resilience in teams and that is why the TRAMS protocol has been developed. The scenario of the simulation games is a disruption for 10 days in the card payment system. During the simulation games, the participants work in teams and have to try to cope with the disruption in the card payment system. During the course of this study, 14 simulation games have been conducted with seven different teams. Each of the simulation games has been executed during one whole day, and the participating teams have in total played two games each. During every simulation game there were three observers equipped with the TRAMS protocol. To interpret the data collected with the TRAMS protocol, two methods have been used: transcription and thematic analysis. As a result, guidelines and design changes was formed. In addition, results showed that the distribution and frequency of observations of resilience strategies made were similar, that the observations noted by the observers were similar, and lastly eight themes from the data collection could be extracted: Coordinate and collaborate, Payment options, Cash circulation, Safety, Fuel and transportation, Inform, communicate and the media, Hoarding and rationing, Vulnerable groups. In conclusion, the TRAMS protocol is still under development and 15 more simulation games are planned to be conducted within the ongoing CCRAAAFFTING project. However, the protocol has been applied in this study´s 14 simulation games so far, and the similarities in how the observers filled in the protocol and how similar the observations were, indicate that it hopefully can develop into a recognized research tool in the future. 

  • 156.
    Amdahl, Per
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Chaikiat, Per
    Linköpings universitet, Institutionen för datavetenskap.
    Personas as Drivers: - an alternative approach for creating scenarios for ADAS evaluation2007Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    Research and development on vehicle safety has lately started to direct its focus towards how to actively support the driver and make it easier for her to drive safely through letting Advanced Driver Assistance Systems (ADAS) have effect on how the driver interacts with the vehicle and the surrounding traffic. This requires research on both how the driver and vehicle perform in different situations, in terms of psychology, cognition and individual differences. In addition, physical limitations and requirements of the driver and the vehicle must be taken into account. Therefore scenarios for evaluation of these systems are required. In the area of user-centered design a rather new method, Personas, is being adopted. This thesis tries to explore if the Persona method is a viable tool for creating scenarios for such evaluations. Experiences after completing this work imply that personas indeed is a viable way to include aspects and raise issues concerning individual variability and situational context in ADAS scenarios.

  • 157.
    Aminifar, Amir
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Analysis, Design, and Optimization of Embedded Control Systems2016Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Today, many embedded or cyber-physical systems, e.g., in the automotive domain, comprise several control applications, sharing the same platform. It is well known that such resource sharing leads to complex temporal behaviors that degrades the quality of control, and more importantly, may even jeopardize stability in the worst case, if not properly taken into account.

    In this thesis, we consider embedded control or cyber-physical systems, where several control applications share the same processing unit. The focus is on the control-scheduling co-design problem, where the controller and scheduling parameters are jointly optimized. The fundamental difference between control applications and traditional embedded applications motivates the need for novel methodologies for the design and optimization of embedded control systems. This thesis is one more step towards correct design and optimization of embedded control systems.

    Offline and online methodologies for embedded control systems are covered in this thesis. The importance of considering both the expected control performance and stability is discussed and a control-scheduling co-design methodology is proposed to optimize control performance while guaranteeing stability. Orthogonal to this, bandwidth-efficient stabilizing control servers are proposed, which support compositionality, isolation, and resource-efficiency in design and co-design. Finally, we extend the scope of the proposed approach to non-periodic control schemes and address the challenges in sharing the platform with self-triggered controllers. In addition to offline methodologies, a novel online scheduling policy to stabilize control applications is proposed.

  • 158.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Bini, Enrico
    Scuola Super Sant Anna, Italy.
    Eles, Petru lon
    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.
    Analysis and Design of Real-Time Servers for Control Applications2016Inngår i: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 65, nr 3, s. 834-846Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, a considerable portion of embedded systems, e.g., automotive and avionic, comprise several control applications. Guaranteeing the stability of these control applications in embedded systems, or cyber-physical systems, is perhaps the most fundamental requirement while implementing such applications. This is different from the classical hard real-time systems where often the acceptance criterion is meeting the deadline. In other words, in the case of control applications, guaranteeing stability is considered to be a main design goal, which is linked to the amount of delay and jitter a control application can tolerate before instability. This advocates the need for new design and analysis techniques for embedded real-time systems running control applications. In this paper, the analysis and design of such systems considering a server-based resource reservation mechanism are addressed. The benefits of employing servers are manifold: providing a compositional and scalable framework, protection against other tasks misbehaviors, and systematic bandwidth assignment and co-design. We propose a methodology for designing bandwidth-optimal servers to stabilize control tasks. The pessimism involved in the proposed methodology is both discussed theoretically and evaluated experimentally.

  • 159.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Bini, Enrico
    Lund University, Sweden.
    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.
    Bandwidth-Efficient Controller-Server Co-Design with Stability Guarantees2014Inngår i: Design, Automation & Test in Europe, DATE 2014, IEEE Computer Society, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many cyber-physical systems comprise several control applications implemented on a shared platform, for which stability is a fundamental requirement. This is as opposed to the classical hard real-time systems where often the criterion is meeting the deadline. However, the stability of control applications depends on not only the delay experienced, but also the jitter. Therefore, the notion of deadline is considered to be artificial for control applications that promotes the need for new techniques for designing cyber-physical systems. The approach in this paper is built on a server-based resource reservation mechanism, which provides compositionality, isolation, and the opportunity of systematic controller--server co-design. We address the controller--server co-design of such systems to obtain design solutions with the minimal bandwidth to guarantee stability.

  • 160.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Bini, Enrico
    Lund University, Sweden.
    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.
    Designing Bandwidth-Efficient Stabilizing Control Servers2013Inngår i: IEEE Real-Time Systems Symposium, RTSS 2013, IEEE , 2013, s. 298-307Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Guaranteeing stability of control applications in embedded systems, or cyber-physical systems, is perhaps the alpha and omega of implementing such applications. However, as opposed to the classical real-time systems where often the acceptance criterion is meeting the deadline, control applications do not primarily enforce hard deadlines. In the case of control applications, stability is considered to be the main design criterion and can be expressed in terms of the amount of delay and jitter a control application can tolerate before instability. Therefore, new design and analysis techniques are required for embedded control systems. In this paper, the analysis and design of such systems considering server-based resource reservation mechanism are addressed. The benefits of employing servers are manifold: (1) providing a compositional framework, (2) protection against other tasks misbehaviors, and (3) systematic bandwidth assignment. We propose a methodology for designing bandwidth-efficient servers to stabilize control tasks.

  • 161.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. 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 högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Jfair: A Scheduling Algorithm to Stabilize Control Applications2015Inngår i: 21st IEEE Real-Time and Embedded Technology and Applications Symposium, Cyber-Physical Systems Week, Seattle, WA, April 2015, IEEE Computer Society, 2015, s. 63-72Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Control applications are considered to be among the core applications in cyber-physical and embedded realtime systems, for which jitter is typically an important factor. This paper investigates whether it is possible to guarantee certain amount of jitter for a given set of applications on a shared platform. The effect of jitter on the stability of control applications and its relation with the latency will be discussed. The importance arises from the fact that it is considerably easier to manage the constant part of the delay (known as latency), while the process of coping with the varying part of the delay (known as jitter) is more involved. The proposed solution guarantees certain jitter limits, and at the same time does not lead to overly pessimistic latency values. The results are later used in a design optimization problem to minimize the resource utilized.

  • 162.
    Aminifar, Amir
    et al.
    Embedded Systems Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland.
    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.
    Optimization of Message Encryption for Real-Time Applications in Embedded Systems2018Inngår i: IEEE Transactions on Computers, ISSN 0018-9340, Vol. 67, nr 5, s. 748-754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, security can no longer be treated as a secondary issue in embedded and cyber-physical systems. Therefore, one of the main challenges in these domains is the design of secure embedded systems under stringent resource constraints and real-time requirements. However, there exists an inherent trade-off between the security protection provided and the amount of resources allocated for this purpose. That is, the more the amount of resources used for security, the higher the security, but the fewer the number of applications which can be run on the platform and meet their timing requirements. This trade-off is of high importance since embedded systems are often highly resource constrained. In this paper, we propose an efficient solution to maximize confidentiality, while also guaranteeing the timing requirements of real-time applications on shared platforms.

  • 163.
    Aminifar, Amir
    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.
    Cervin, Anton
    Dept. of Automatic Control, Lund University, Sweden.
    Control-Quality Driven Design of Cyber-Physical Systems with Robustness Guarantees2013Inngår i: Design, Automation & Test in Europe (DATE 2013), IEEE , 2013, s. 1093-1098Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many cyber-physical systems comprise several control applications sharing communication and computation resources. The design of such systems requires special attention due to the complex timing behavior that can lead to poor control quality or even instability. The two main requirements of control applications are: (1) robustness and, in particular, stability and (2) high control quality. Although it is essential to guarantee stability and provide a certain degree of robustness even in the worst-case scenario, a design procedure which merely takes the worst-case scenario into consideration can lead to a poor expected (average-case) control quality, since the design is solely tuned to a scenario that occurs very rarely. On the other hand, considering only the expected quality of control does not necessarily provide robustness and stability in the worst-case. Therefore, both the robustness and the expected control quality should be taken into account in the design process. This paper presents an efficient and integrated approach for designing high-quality cyber-physical systems with robustness guarantees.

  • 164.
    Aminifar, Amir
    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.
    Cervin, Anton
    Lund University, Sweden.
    Stability-Aware Analysis and Design of Embedded Control Systems2013Inngår i: Proceedings of the International Conference on Embedded Software (EMSOFT), 2013, IEEE conference proceedings, 2013, s. 1-10Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many embedded systems comprise several controllers sharing available resources. It is well known that such resource sharing leads to complex timing behavior that can jeopardize stability of control applications, if it is not properly taken into account in the design process, e.g., mapping and scheduling. As opposed to hard real-time systems where meeting the deadline is a critical requirement, control applications do not enforce hard deadlines. Therefore, the traditional real-time analysis approaches are not readily applicable to control applications. Rather, in the context of control applications, stability is often the main requirement to be guaranteed, and can be expressed as the amount of delay and jitter a control application can tolerate. The nominal delay and response-time jitter can be regarded as the two main factors which relate the real-time aspects of a system to control performance and stability. Therefore, it is important to analyze the impact of variations in scheduling parameters, i.e., period and priority, on the nominal delay and response-time jitter and, ultimately, on stability. Based on such an analysis, we address, in this paper, priority assignment and sensitivity analysis problems for control applications considering stability as the main requirement.

  • 165.
    Aminifar, Amir
    et al.
    Embedded Systems Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland..
    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.
    Cervin, Anton
    Department of Automatic Control, Lund University, Sweden.
    Årzén, Karl-Erik
    Department of Automatic Control, Lund University, Sweden.
    Control-Quality Driven Design of Embedded Control Systems with Stability Guarantees2017Inngår i: IEEE design & test, ISSN 2168-2356, E-ISSN 2168-2364Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, the majority of control applications in embedded systems, e.g., in the automotive domain, are implemented as software tasks on shared platforms. Ignoring implementation impacts during the design of embedded control systems results in complex timing behaviors that may lead to poor performance and, in the worst case, instability of control applications. This article presents a methodology for implementation-aware design of high-quality and stable embedded control systems on shared platforms with complex timing behaviors.

  • 166.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Samii, Soheil
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    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.
    Cervin, Anton
    Dept. of Automatic Control, Lund University, Sweden.
    Designing High-Quality Embedded Control Systems with Guaranteed Stability2012Inngår i: 33rd IEEE Real-Time Systems Symposium (RTSS 2012, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many embedded systems comprise several controllers sharing available resources. It is well known that such resource sharing leads to complex timing behavior that degrades the quality of control, and more importantly, can jeopardize stability in the worst-case, if not properly taken into account during design. Although stability of the control applications is absolutely essential, a design flow driven by the worst-case scenario often leads to poor control quality due to the significant amount of pessimism involved and the fact that the worst-case scenario occurs very rarely. On the other hand, designing the system merely based on control quality, determined by the expected (average-case) behavior, does not guarantee the stability of control applications in the worst-case. Therefore, both control quality and worst-case stability have to be considered during the design process, i.e., period assignment, task scheduling, and control-synthesis. In this paper, we present an integrated approach for designing high-quality embedded control systems, while guaranteeing their stability.

  • 167.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Tabuada, Paulo
    University of California at Los Angeles, USA.
    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.
    Self-Triggered Controllers and Hard Real-Time Guarantees2016Inngår i: PROCEEDINGS OF THE 2016 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION (DATE), Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 636-641Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is well known that event-triggered and self-triggered controllers implemented on dedicated platforms can provide the same performance as the traditional periodic controllers, while consuming considerably less bandwidth. However, since the majority of controllers are implemented by software tasks on shared platforms, on one hand, it might no longer be possible to grant access to the event-triggered controller upon request. On the other hand, due to the seemingly irregular requests from self-triggered controllers, other applications, while in reality schedulable, may be declared unschedulable, if not carefully analyzed. The schedulability and response-time analysis in the presence of self-triggered controllers is still an open problem and the topic of this paper.

  • 168.
    Aminoff, Hedvig
    Linköpings universitet, Institutionen för datavetenskap.
    Coordination in Emergency Management from a Joint Cognitive Systems Perspective2007Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Emergency management (EM) can benefit from new information and communication technology (ICT). However, the complexity of the field poses high demands upon prospective system developers. The design of technological support in a field where roles and actions are entwined and never completely predetermined, requires an understanding of interactions in the socio-technical system as a whole.

    In this thesis, an attempt is made to work from a Cognitive Systems Engineering stance to identify important characteristics of coordination in intermunicipal EM. Applying perspectives from distributed cognition, joint activity and common ground, Hollnagel’s COCOM and ECOM models have been applied to identify points of entry into work practices. Working with data from a simulated forest-fire in a role-playing exercise, an analysis of dialogues uncovered ambiguity in how functions are handled in a large event, indicating vulnerabilities in face of larger crises. In addition, it became evident that functions moved across roles during the evolving event, and it was possible to uncover recognizable phases of a response. The results underline characteristics that should be supported by future ICT, and occurrences that can be explored in future studies.

  • 169.
    Aminoff, Hedviq
    et al.
    Infocentret Ankaret.
    Johansson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, CSELAB - Cognitive Systems Engineering Laboratory.
    Trnka, Jiri
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, GIS - Geografiska informationssystem.
    Understanding Coordination in Emergency Response2007Inngår i: European Annual Conference on Human Decision-Making and Manual Control,2007, Lyngby, Denmark: Technical University of Denmark , 2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper describes and discusses analysis of an emergency management exercise. In the exercise scenario, different emergency management organizations jointly try to cope with a forest fire and related incidents. The Extended Control Model is utilized for examination of the establishment of en emergent emergency response organization. Ambiguity in how functions are to be handled in a large event, indicating vulnerabilities in face of larger crises; functions moving across roles during the evolving event; and recognizable phases of a response are uncovered. This is assessed by utilizing episodic analysis of the communication between different functions and roles in the participating emergency management organizations. The results indicate requirements for future information and communication technologies, and occurrences that can be explored in future studies.

  • 170.
    Amirijoo, Mehdi
    Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem. Linköpings universitet, Tekniska högskolan.
    QoS Control of Real-Time Data Services under Uncertain Workload2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Real-time systems comprise computers that must generate correct results in a timely manner. This involves a wide spectrum of computing systems found in our everyday life ranging from computers in rockets to our mobile phones. The criticality of producing timely results defines the different types of realtime systems. On one hand, we have the so-called hard real-time systems, where failing to meet deadlines may result in a catastrophe. In this thesis we are, however, concerned with firm and soft real-time systems, where missing deadlines is acceptable at the expense of degraded system performance. The usage of firm and soft real-time systems has increased rapidly during the last years, mainly due to the advent of applications in multimedia, telecommunication, and e-commerce. These systems are typically data-intensive, with the data normally spanning from low-level control data, typically acquired from sensors, to high-level management and business data. In contrast to hard real-time systems, the environments in which firm and soft real-time systems operate in are typically open and highly unpredictable. For example, the workload applied on a web server or base station in telecommunication systems varies according to the needs of the users, which is hard to foresee. In this thesis we are concerned with quality of service (QoS) management of data services for firm and soft real-time systems. The approaches and solutions presented aim at providing a general understanding of how the QoS can be guaranteed according to a given specification, even if the workload varies unpredictably. The QoS specification determines the desired QoS during normal system operation, and the worst-case system performance and convergence rate toward the desired setting in the face of transient overloads. Feedback control theory is used to control QoS since little is known about the workload applied on the system. Using feedback control the difference between the measured QoS and the desired QoS is formed and fed into a controller, which computes a change to the operation of the real-time system. Experimental evaluation shows that using feedback control is highly effective in managing QoS such that a given QoS specification is satisfied. This is a key step toward automatic management of intricate systems providing real-time data services.

    Delarbeid
    1. Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations
    Åpne denne publikasjonen i ny fane eller vindu >>Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations
    2006 (engelsk)Inngår i: IEEE Transactions on Computers, ISSN 0018-9340, Vol. 55, nr 3, s. 304 - 319Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services that are provided by real-time databases. Since the workload of real-time databases cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework for QoS specification and management consisting of a model for expressing QoS requirements, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of real-time databases, even for transient overloads and with inaccurate runtime estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms that uses feedback control.

    Emneord
    Real-time and embedded systems, real-time data services, imprecise computation, feedback control, modeling techniques
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-12635 (URN)10.1109/TC.2006.45 (DOI)
    Tilgjengelig fra: 2007-10-17 Laget: 2007-10-17 Sist oppdatert: 2009-02-10
    2. Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems
    Åpne denne publikasjonen i ny fane eller vindu >>Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems
    2007 (engelsk)Inngår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, nr 3, s. 209-238Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In recent years a new class of soft real-time applications operating in unpredictable environments has emerged. Typical for these applications is that neither the resource requirements nor the arrival rates of service requests are known or available a priori. It has been shown that feedback control is very effective to support the specified performance of dynamic systems that are both resource insufficient and exhibit unpredictable workloads. To efficiently use feedback control scheduling it is necessary to have a model that adequately describes the behavior of the system. In this paper we experimentally evaluate the accuracy of four linear time-invariant models used in the design of feedback controllers. We introduce a model (DYN) that captures additional system dynamics, which a previously published model (STA) fails to include. The accuracy of the models are evaluated by validating the models with regard to measured data from the controlled system and through a set of experiments where we evaluate the performance of a set of feedback control schedulers tuned using these models. From our evaluations we conclude that second order models (e.g., DYN) are more accurate than first order models (e.g. STA). Further we show that controllers tuned using second order models perform better than controllers tuned using first order models.

    sted, utgiver, år, opplag, sider
    Springer Science+Business Media B.V., 2007
    Emneord
    Feedback control scheduling, Modeling, Model validation, System identification
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-12636 (URN)10.1007/s11241-006-9008-8 (DOI)
    Tilgjengelig fra: 2007-10-17 Laget: 2007-10-17 Sist oppdatert: 2017-12-14
    3. Robust Quality Management for Differentiated Imprecise Data Services
    Åpne denne publikasjonen i ny fane eller vindu >>Robust Quality Management for Differentiated Imprecise Data Services
    2004 (engelsk)Inngår i: Proceedings of the 25th IEEE International Real-Time Systems Symposium, 2004, s. 265-275Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Several applications, such as Web services and e-commerce, are operating in open environments where the workload characteristics, such as the load applied on the system and the worst-case execution times, are inaccurate or even not known in advance. This implies that transactions submitted to a real-time database cannot be subject to exact schedulability analysis given the lack of a priori knowledge of the workload. In this paper we propose an approach, based on feedback control, for managing the quality of service of real-time databases that provide imprecise and differentiated services, given inaccurate workload characteristics. For each service class, the database operator specifies the quality of service requirements by explicitly declaring the precision requirements of the data and the results of the transactions. The performance evaluation shows that our approach provides reliable quality of service even in the face of varying load and inaccurate execution time estimates.

    Emneord
    Real-time systems, Real-time databases, Control theory, Realtidssystem, Realtidsdatabaser, Reglerteknik, CUGS
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-12637 (URN)10.1109/REAL.2004.49 (DOI)0-7695-2247-5 (ISBN)
    Konferanse
    25th IEEE International Real-Time Systems Symposium, Lisbon, Portugal, December 5-8, 2004
    Tilgjengelig fra: 2007-10-17 Laget: 2007-10-17 Sist oppdatert: 2018-08-30
    4. Generalized performance management of multi-class real-time imprecise data services
    Åpne denne publikasjonen i ny fane eller vindu >>Generalized performance management of multi-class real-time imprecise data services
    Vise andre…
    2005 (engelsk)Inngår i: Real-Time Systems Symposium, 2005. RTSS 2005. 26th IEEE International, 2005, s. 12-49Konferansepaper, Publicerat paper (Annet vitenskapelig)
    Abstract [en]

    The intricacy of real-time data service management increases mainly due to the emergence of applications operating in open and unpredictable environments, increases in software complexity, and need for performance guarantees. In this paper we propose an approach for managing the quality of service of real-time databases that provide imprecise and differentiated services, and that operate in unpredictable environments. Transactions are classified into service classes according to their level of importance. Transactions within each service class are further classified into subclasses based on their quality of service requirements. In this way transactions are explicitly differentiated according to their importance and quality of service requests. The performance evaluation shows that during overloads the most important transactions are guaranteed to meet their deadlines and that reliable quality of service is provided even in the face of varying load and execution time estimation errors.

    Emneord
    real-time system, database, QoS, feedback control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-12638 (URN)10.1109/RTSS.2005.23 (DOI)
    Tilgjengelig fra: 2007-10-17 Laget: 2007-10-17 Sist oppdatert: 2009-04-22
    5. Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems
    Åpne denne publikasjonen i ny fane eller vindu >>Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems
    2008 (engelsk)Inngår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 40, nr 1, s. 44-76Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the dynamics of the system. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantify the disturbance present in the measured variable as a function of the data set size and the sampling period, and we propose a feedback control structure that suppresses the measurement disturbance. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability.

    sted, utgiver, år, opplag, sider
    Springer, 2008
    Emneord
    Adaptive scheduling, Feedback control, Measurement disturbance, System disturbance
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-12639 (URN)10.1007/s11241-008-9048-3 (DOI)
    Tilgjengelig fra: 2007-10-17 Laget: 2007-10-17 Sist oppdatert: 2017-12-14
  • 171.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Brännström, Per
    Institutionen för datavetenskap Linköpings universitet.
    Hansson, Jörgen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Gunnarsson, Svante
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Son, Sang
    Department of Computer Science University of Virginia.
    Toward Adaptive Control of QoS-Importance Decoupled Real-Time Systems2007Inngår i: IEEE International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks,2007, 2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper deals with differentiated services in real-time systems. Tasks submitted to a real-time system are differentiated with respect to importance and QoS requirements. We use feedback control to enforce the requirements in QoS and ensure a hierarchical admission policy based on the importance of the tasks. The results show that the requirements are met during steady state when the workload is constant. The feedback control approach does not satisfactorily manage QoS when there is a sudden and significant workload change (transient state) due to the time-variant nature of the system. To address this, we present preliminary and promising results using adaptive control, and report on some challenges we are facing when applying the theory.

  • 172.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem. Linköpings universitet, Tekniska högskolan.
    Hansson, Jörgen
    Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem. Linköpings universitet, Tekniska högskolan.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Son, Sang H.
    University of Virginia, VA, USA.
    Enhancing Feedback Control Scheduling Performance by On-line Quantification and Suppression of Measurement Disturbance2005Inngår i: Proceedings of the 11th IEEE Real-Time and Embedded Technology and Applications Symposium, 2005, s. 2-11Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the system dynamics. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantize the disturbance present in the measured variable as a function of the sampling period and we propose a measurement disturbance suppressive control structure. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability and adaptation.

  • 173.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Hansson, Jörgen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Son, Sang H
    Dept. of Computer Science University of Virginia.
    Error-Driven QoS Management in Imprecise Real-Time Databases2003Inngår i: Euromicro Conference on Real-Time Systems,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, s. 63-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In applications such as web-applications, e-commerce, and engine control, the demand for real-time data services has increased. In these applications, requests have to be processed within their deadlines using fresh data. Since the workload of these systems cannot be precisely predicted, they can become overloaded and as a result, deadline and freshness violations may occur. To address this problem we propose a QoS-sensitive approach based on imprecise computation, applied on transactions and data objects. We propose two algorithms FCS-HEF and FCS-HEDF that give a robust and controlled behavior of RTDBs in terms of transaction and data preciseness, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms including FCS-EDF, which schedules the transactions using EDF.

  • 174.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Hansson, Jörgen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Son, Sang H
    Dept. of Computer Science University of Virginia.
    Specification and Management of QoS in Imprecise Real-Time Databases2003Inngår i: International Database Engineering and Applications Symposium,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, s. 192-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services. Since the workload of real-time databases RTDBs, providing real-time data services, cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in a damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework consisting of a model for expressing QoS requirements in terms of data and transaction preciseness, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of RTDBs, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms, including FCS-EDF that schedules the transactions using EDF and feedback control.

  • 175.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Son, Sang H.
    Department of Computer Science University of Virgina.
    Hansson, Jörgen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    QoD Adaptation for Achieving Lifetime Predictability of WSN Nodes Communicating over Satellite Links2007Inngår i: International Conference on Networked Sensing Systems INSS,2007, IEEE , 2007, s. 19-26Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we propose an architecture consisting of a particular type of node, namely a communication server that collects and aggregates data, and establishes a link between the users and the sensor nodes through satellite communication. A key challenge with satisfying a lifetime requirement of the communication server is the unpredictability of the sensor data volume arriving at the communication server and the transmission power of the satellite terminal. To provide lifetime predictability we propose an approach that automatically adjusts the quality of the data such that the specified lifetime if achieved. We have shown through an extensive evaluation that the approach manages to provide an actual lifetime within 2% of the specified lifetime despite variations in workload and communication link quality.

  • 176.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Tesanovic, Aleksandra
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Andersson, Torgny
    Enea Epact.
    Hansson, Jörgen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Son, Sang H.
    Department of Computer Science University of Virginia, USA.
    Finite Horizon QoS Prediction of Reconfigurable Firm Real-Time Systems2006Inngår i: IEEE International Conference on Embedded and Real-Time Computing Systems and Applications,2006, Los Alamitos, California, USA: IEEE Computer Society , 2006, s. 233-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Updating real-time system software is often needed in response to errors and added requirements to the software. Stopping a running application, updating the software, and then restarting the application is not suitable for systems with high availability requirements. On the other hand, dynamically updating a system may increase the execution time of the tasks, thus, degrading the performance of the system. Degradation is not acceptable for performance-critical real-time systems as there are strict requirements on the performance. In this paper we present an approach that enables dynamic reconfiguration of a real-time system, where the performance of the system during a reconfiguration satisfies a given worst-case performance specification. Evaluation shows that the presented method is efficient in guaranteeing the worst-case performance of dynamically reconfigurable firm real-time systems. 

  • 177.
    Amirijoo, Mehdi
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Tesanovic, Aleksandra
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, RTSLAB - Laboratoriet för realtidssystem.
    Raising Motivation in Real-time Laboratories: The Soccer Scenario2004Inngår i: Technical Symposium on Computer Science Education, SIGCSE,2004, USA: Association for Computing Machinery (ACM) , 2004, s. 265-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Real-time systems is a topic that one cannot overlook in an engineer's education. However, teaching real-time systems in an undergraduate syllabus is a challenging experience due to conflicting constraints placed on such a course. In this paper we present a new setup for laboratories in the real-time systems course that successfully meets the constraints of mass education, stable environment management, short time span for the labs, and still enables deep involvement of students in the central topic of resource allocation with high motivation.

  • 178.
    Amundin, Mats
    et al.
    Kolmården Wildlife Park.
    Hållsten, Henrik
    Filosofiska institutionen, Stockholms universitet.
    Eklund, Robert
    Linköpings universitet, Institutionen för kultur och kommunikation, Avdelningen för språk och kultur. Linköpings universitet, Filosofiska fakulteten.
    Karlgren, Jussi
    Kungliga Tekniska Högskolan.
    Molinder, Lars
    Carnegie Investment Bank, Swedden.
    A proposal to use distributional models to analyse dolphin vocalisation2017Inngår i: Proceedings of the 1st International Workshop on Vocal Interactivity in-and-between Humans, Animals and Robots, VIHAR 2017 / [ed] Angela Dassow, Ricard Marxer & Roger K. Moore, 2017, s. 31-32Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper gives a brief introduction to the starting points of an experimental project to study dolphin communicative behaviour using distributional semantics, with methods implemented for the large scale study of human language.

  • 179.
    An, Ping
    Linköpings universitet, Institutionen för datavetenskap.
    An investigation of the use of software development environments in the industry2004Independent thesis Basic level (professional degree)Oppgave
    Abstract [en]

    Software engineering tools are being used in the industry in order to improve the productivity and the quality of the software development process. The properties of those tools are being perceived to be unsatisfactory. For example, researchers have found that some problems are due to deficient integration among the tools. Furthermore, a continuing problem is that there is a gap between the IT education and real demand of tool-skills form IT industry. Consequently, knowledge is needed of the properties of software development tools as well an understanding of demanded tool-skill from the industry.

    The purpose of this study is to survey commercial software development environment (SDEs) that are used today in professional software engineering and discuss their advantages adn disadvantages. A secondary goal of the study is to identify the actual requirements from the industry on the IT-education.

    A questionnaire was sent out to 90 software developers and IT managers of 30 IT companies in Sweden. The results of the survey show that IT companies, for most part, use SDEs from commercial software vendors. Respondents report that common problems of the SDEs are the following: bad integration among the tools, problems to trace software artifacts in the different phases of the programming cycle, and deficient support for version control and system configuration. Furthermore, some tools are difficult to use which results in a time-consuming development process.

    We conclude that future software development environments need to provide better support for integration, automation, and configuration management. Regarding the required tool-skills, we believe that the IT education would gain from including commercial tools that cover the whole software product lifecycle in the curriculum.

  • 180.
    Andell, Anton
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Cole, Nigel
    Linköpings universitet, Institutionen för datavetenskap.
    Karlsson, Wiktor
    Linköpings universitet, Institutionen för datavetenskap.
    Lilja, Eric
    Linköpings universitet, Institutionen för datavetenskap.
    Rezaie, Diba
    Linköpings universitet, Institutionen för datavetenskap.
    Thimren, David
    Linköpings universitet, Institutionen för datavetenskap.
    Zeijlon, Andreas
    Linköpings universitet, Institutionen för datavetenskap.
    CI/CD i molnapplikationer som Google Cloud, Azure och AWS2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Under VT 2019 ägde projektet rum varav denna rapport är ett av resultaten. Projektets mål var att skapa en CI/CD pipeline vars syfte var tänkt att frekvent kunna leverera färdigtestad kod till olika molntjänster som Google Cloud Platform, Amazon Web Services och Azure. Projektspecifikationerna gavs av företaget Skira för att skapa en snabbare integrationsprocess för nya utvecklare. Detta så en ny utvecklare skulle kunna lägga mer tid på att koda istället för att gräva ner sig i leverans-/testningsprocessen. Slutprodukten ger företag möjligheten att koda direkt på sitt utvecklingskluster.

  • 181.
    Andell, Oscar
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Andersson, Albin
    Linköpings universitet, Institutionen för datavetenskap.
    Slow rate denial of service attacks on dedicated- versus cloud based server solutions2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Denial of Service (DoS) attacks remain a serious threat to internet stability. A specific kind of low bandwidth DoS attack, called a slow rate attack can with very limited resources potentially cause major interruptions to the availability of the attacked web servers. This thesis examines the impact of slow rate application layer DoS attacks against three different server solutions. The server solutions are a static cloud solution and a load-balancing cloud solution running on AmazonWeb Services (AWS) as well as a dedicated server. To identify the impact in terms of responsiveness and service availability a number of experiments were conducted on the web servers using publicly available DoS tools. The response times of the requests were measured. The results show that the dedicated and static cloud based server solutions are severely impacted by the attacks while the AWS load-balancing cloud solution is not impacted nearly as much. We concluded that all solutions were impacted by the attacks and that the readily available DoS tools are sufficient for creating a denial of service state on certain web servers.

  • 182.
    Anderberg, Pierre
    Linköpings universitet, Institutionen för datavetenskap.
    Analyzing and Re-designing Legacy Systems for Enhanced Usability: A Case Study on the CATS TCT2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The CATS TCT is a military wargaming simulator used by the Swedish Armed Forces for education of position holders within battalion or company staffs. The CATS TCT was developed during the nineties and one of the challenges today is how the system can be modernized in order to meet the increased demands on usability. This master thesis is part of the work with modernizing the CATS TCT and a usability study has been conducted in order to identify issues and problems of the current system related to usability.

    This thesis is conducted at BAE Systems C-ITS in Linköping and the main focus of this study has been how to analyze and re-design the CATS TCT in order to enhance the usability of the system. Empirical data in this study has been collected through six semi-structured interviews, one observation and two focus group interviews and the result of this study has elicit several problem areas related to any of following usability aspects: effectiveness, efficiency or satisfaction.

    The conclusions from this investigation is that the CATS TCT simulator is an valuable and appreciated educational tool – especially from an effectiveness point of view. When it comes to efficiency, however, several problems areas has been identified and these areas are: information architecture, interface interaction, how orders are issued to units and how the simulation rules are implemented. When it comes to the users satisfaction of the system no unequivocal conclusion has been possible to present.

    As a complement to the identified issues and problems of the simulator this study has also presented examples on how prototypes could be used to solve some of the identified problems. More specifically, in this report re-design solutions related to how the users interact with the map, how orders are issued and how status overview is displayed has been presented.

  • 183.
    Anderljung, Andreas
    Linköpings universitet, Institutionen för datavetenskap.
    An approach for using personas and scenarios to procure user-requirements within a procuring organization2009Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this master thesis is to investigate how a procuring organization can use personas and scenarios to gather user-requirements in the procurement of software. To reach this understanding a case study is carried out to answer the questions of research; which is a definition that suits IKEA Components, which tools and how to use them; and what are the obstacles and enablers for working with personas and scenarios in procurement of software. The thesis consists of a theoretical study in the usability area followed by an empirical investigation with semi-structured interviews and observations. The study resulted in 4 personas and 8 connected scenarios that are based on user requirements. The first finding due to the question of research includes a usability definition applied to a real context. The second reveals examples of how personas and scenarios can make the development team understand the user requirements and thus contribute to procurement. The last finding is that the main obstacles and enablers for IKEA Components is the complexity of the main system, lack of resources and the management support.

  • 184.
    Anderson, Camilla
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Andersson, Frida
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Subscribers loyalty for newspapers - a study of Östgöta Correspondentens weekend supplement2015Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [en]

    Upplagesiffrorna för den tryckta dagstidningen har minskat under flera år. I Sverige är det ett stort problem då prenumerationen av den tryckta dagstidningen fortfarande är tidningsföretagens största inkomstkälla. Detta gör att det är av stor vikt för tidningsföretagen att hitta ett sätt att behålla dessa kunder. I denna studie har det undersökts om utformningen av en bilaga kan bidra till att prenumeranterna blir mer lojala. Studien har utförts i sammanbete med Östgöta Correspondenten och dess helgbilaga Paus Weekend. För att svara på syftet delades studien upp i två delproblem: vad har Östgöta Correspondentens nuvarande prenumeranter för attityder till Paus Weekend och huvudtidningen samt om det finns andra liknande bliagor som uppnått ökad kundlojalitet.

  • 185.
    Anderson, Jonathan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Visualisation of data from IoT systems: A case study of a prototyping tool for data visualisations2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The client in this study, Attentec, has seen an increase in the demand for services connected to Internet of things systems. This study is therefore examining if there is a tool that can be a used to build fast prototype visualisations of data from IoT systems to use as a tool in their daily work.

    The study started with an initial phase with two parts. The first part was to get better knowledge of Attentec and derive requirements for the tool and the second part was a comparison of prototyping tools for aiding in development of data visualisations. Apache Zeppelin was chosen as the most versatile and suitable tool matching the criteria defined together with Attentec. Following the initial phase a pre-study containing interviews to collect empirical data on how visualisations and IoT projects had been implemented previously at Attentec were performed. This lead to the conclusion that geospatial data and NoSQL databases were common for IoT projects. A technical investigation was conducted on Apache Zeppelin to answer if there were any limits in using the tool for characteristics common in IoT system. This investigation lead to the conclusion that there was no support for plotting data on a map.

    The first implementation phase implemented support for geospatial data by adding a visualisation plug-in that plotted data on a map. The implementation phase was followed by an evaluation phase in which 5 participants performed tasks with Apache Zeppelin to evaluate the perceived usability of the tool. The evaluation was performed using a System Usability Scale and a Summed Usability Metric as well as interviews with the participants to find where improvements could be made. From the evaluation three main problems were discovered, the import and mapping of data, more feature on the map visualisation plug-in and the creation of database queries. The first two were chosen for the second iteration where a script for generating the code to import data was developed as well as improvements to the geospatial visualisation plug-in. A second evaluation was performed after the changes were made using similar tasks as in the first to see if the usability was improved between the two evaluations. The results of the Summed Usability Metric improved on all tasks and the System Usability Scale showed no significant change. In the interviews with the participants they all responded that the perceived usability had improved between the two evaluations suggesting some improvement.

  • 186.
    Anderson, Jonathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Björch, Tobias
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Boman, Jakob
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    van Dijk, Christopher
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Harrius, Sofie
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Nilsson, Daniel
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Ottosson, Albin
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Östman, Johan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    BookShark – En praktisk studie i webbutveckling2014Independent thesis Basic level (degree of Bachelor), 12 poäng / 18 hpOppgave
    Abstract [sv]

    Rapportens syfte är att beskriva det tekniska och teoretiska framtagandet av e-boktjänsten BookShark. Den innehåller bland annat styrkanden rörande tjänstens hållbarhet på marknaden samt hur teamet har förhållit sig till arbetsmetoden Scrum. Målgruppen för BookShark är kunder som vill ha möjligheten att handla böcker online på ett smidigt sätt till ett förmånligt pris. Utifrån detta har teamet arbetat enligt visionen Vår vision är att revolutionera sättet människor konsumerar böcker på genom att göra böcker billigare och mer lättillgängliga för alla.

    Den tekniska utvecklingen har delats upp i fyra lager: Databas, Databasinterface, Serverskript och Front-end. Teammedlemmarna har delat upp ansvarområden inom dessa fyra lager, men samtidigt haft en kontinuerlig uppdatering om varandras arbete för att på så sätt ha koll på respektive teammedlems arbete.

    BookShark har uppnått den kravspecifikation som sattes av teamet i projektets början, och även om viss utveckling fortfarande skulle krävas för en kommersiell lansering har önskad funktionalitet uppnåtts.

  • 187.
    Anderson, Kristin
    Linköpings universitet, Institutionen för systemteknik, Informationsteori. Linköpings universitet, Tekniska högskolan.
    Tree Structures in Broadcast Encryption2005Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The need for broadcast encryption arises when a sender wishes to securely distribute messages to varying subsets of receivers, using a broadcast channel, for instance in a pay-TV scenario. This is done by selecting subsets of users and giving all users in the same subset a common decryption key. The subsets will in general be overlapping so that each user belongs to many subsets and has several different decryption keys. When the sender wants to send a message to some users, the message is encrypted using keys that those users have. In this thesis we describe some broadcast encryption schemes that have been proposed in the literature. We focus on stateless schemes which do not require receivers to update their decryption keys after the initial keys have been received; particularly we concentrate on the Subset Difference (SD) scheme.

    We consider the effects that the logical placement of the receivers in the tree structure used by the SD scheme has on the number of required transmissions for each message. Bounds for the number of required transmissions are derived based on the adjacency of receivers in the tree structure. The tree structure itself is also studied, also resulting in bounds on the number of required transmissions based on the placement of the users in the tree structure.

    By allowing a slight discrepancy between the set of receivers that the sender intends to send to and the set of receivers that actually can decrypt the message, we can reduce the cost in number of transmissions per message. We use the concept of distortion to quantify the discrepancy and develop three simple algorithms to illustrate how the cost and distortion are related.

  • 188.
    Andersson, Adam
    Linköpings universitet, Institutionen för systemteknik, Bildbehandling. Linköpings universitet, Tekniska högskolan.
    Range Gated Viewing with Underwater Camera2005Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The purpose of this master thesis, performed at FOI, was to evaluate a range gated underwater camera, for the application identification of bottom objects. The master thesis was supported by FMV within the framework of “arbetsorder Systemstöd minjakt (Jan Andersson, KC Vapen)”. The central part has been field trials, which have been performed in both turbid and clear water. Conclusions about the performance of the camera system have been done, based on resolution and contrast measurements during the field trials. Laboratory testing has also been done to measure system specific parameters, such as the effective gate profile and camera gate distances.

    The field trials shows that images can be acquired at significantly longer distances with the tested gated camera, compared to a conventional video camera. The distance where the target can be detected is increased by a factor of 2. For images suitable for mine identification, the increase is about 1.3. However, studies of the performance of other range gated systems shows that the increase in range for mine identification can be about 1.6. Gated viewing has also been compared to other technical solutions for underwater imaging.

  • 189.
    Andersson, Adam
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Byrsten, Niclas
    Linköpings universitet, Institutionen för datavetenskap.
    Hvass, Björn
    Linköpings universitet, Institutionen för datavetenskap.
    Lindström, Henrik
    Linköpings universitet, Institutionen för datavetenskap.
    Persson, Martin
    Linköpings universitet, Institutionen för datavetenskap.
    Sjöbergsson, Christoffer
    Linköpings universitet, Institutionen för datavetenskap.
    Utterborn, Tor
    Linköpings universitet, Institutionen för datavetenskap.
    Schemaläggningsstöd för kirurgi2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna rapport är resultatet av kandidatprojektkursen TDDD96 som ges vid Linköpings Universitet. Rapporten omfattas av sju studenter som har utvecklat ett schemaläggnings-stöd för kirurgin till Region Östergötland. I rapporten behandlas de tekniska val som har gjorts, hur utvecklingsarbetet har fortgått och hur resultat blev. Varje student har också bidragit med en individuell studie, dessa finns i slutet av dokumentet.

  • 190.
    Andersson, Anders
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Gråbalans: i praktik och teori2003Independent thesis Basic level (professional degree)Oppgave
    Abstract [sv]

    Syfte

    Detta examensarbete gjordes för att försöka underlätta och förbättra arbetet med gråbalansstyrning vid dagstidningstryck. Punkter som ingår:

    - Hur väl går det att mäta med densitometer på gråbalansfälten, och vad kan påverka dess mätvärden?

    - Går det att hitta några riktlinjer för hur mätvärden, som erhålls från densitometern, skall förhålla sig till varandra?

    - Hur små kan gråbalansfälten vara och ändå vara tillförlitliga att arbeta med visuellt?

    - Hur förhåller sig konventionellt raster till stokastiskt raster?

    Resultat

    Vad gäller val av gråbalanston kan rekommenderas att använda någon av de fyra mellantoner, som ingick i undersökningen. Den allra ljusaste tonen i testerna är väldigt svår att läsa av visuellt, och vid mätning med densitometer är den inte tillräckligt känslig för variationer i fulltonsdensiteterna och punktareorna.Den allra mörkaste tonen är den som är enklast att läsa av visuellt i små fält, men vid mätning ger den väldigt spridda och oregelbundna mätvärden.

    Vid mätning med densitometer är konventionellt raster stabilare än stokastiskt raster. Stokastiskt raster ger lite högre mätvärden, än vad det konventionella rastret gör, då båda metoderna har samma rastertonvärden för de ingående tryckfärgerna. Vid visuell bedömning har rastermetoderna olika fördelar. För konventionellt raster är det lättare att identifiera små densitetsavvikelser, medan stokastiskt raster är lättare att avläsa på väldigt små fält, då avvikelsen på fulltonsdensiteten ligger på +/- 0,1 D.

    Placeringen på sidan spelar en stor roll när det gäller mätning med densitometer. Det allra viktigaste är att inte placera gråbalkarna så att de trycks bakom varandra på varsin sida av pappret. Detta påverkar mätningsresultatet relativt mycket. Även val av placering i tryckriktningen påverkar mätningar. Det gick att se klara tendenser på förändring i punktarean, genom att den ökade längs tryckriktningen. Denna förändring i punktarean påverkade mätvärdet.

    Vid mätning med densitometer på ett CMY-fält, tryckt med konventionellt raster, ska C och M ge samma värde, medan Y skall ligga ungefär 0,01 mätenhet högre. För att K-fältet ska vara så likt CMY-fältet som möjligt, bör dess K-värde ligga 0,02 mätenheter över värdet för C i CMY-fältet. Det inbördes förhållandet mellan C-, M- och Y-värdena i CMY-fälten är vid stokastiskt raster svårare att bestämma. De ligger dock nära varandra i de flesta toner. Som referensmätvärde för C kan sägas att det bör ligga något under tonvärdet för cyan, vid konventionellt raster. När stokastiskt raster används bör detta värde ligga något över tonvärdet för cyan.

  • 191.
    Andersson, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Hallgren, Daniel
    Linköpings universitet, Institutionen för systemteknik.
    Passive Aircraft Altimetry using GPS as a Bistatic Radar: A simulation model2003Independent thesis Basic level (professional degree)Oppgave
    Abstract [en]

    A common way to measure height in aerial vehicles is to use a radar height altimeter (RHM). Since the RHM transmits radar pulses that can be detected, a passive alternative would be desirable in military applications. The idea to use reflected signals from the Global Positioning System (GPS) as a bistatic radar, has been established over the last years. The GPS signals are already present and would not reveal aeroplanes in covert operations.

    In this thesis, the use of reflected GPS signals as a bistatic, passive altimeter is examined. A simulation model has been developed and implemented, and simulations using the model have been done. Different types of ground cover have been investigated, both water and land types, with varying reflectivity and scattering behaviour. For larger terrain variations, e.g. mountains and valleys, a ground elevation database has been used. Furthermore, several parameters, like the antenna coverage and the satellite elevation angle, have been varied and the result of this examined.

    The results of these simulations show that measuring height is possible for bothsea and land surfaces. The accuracy depends on several error factors, like a bias originating from surface roughness and measurement errors due to noise in the receiver. The simulations also show that the most important design parameter is the antenna, which must be designed to give a sufficiently large SNR, capture the specular reflection and avoid unwanted reflections.

  • 192.
    Andersson, André
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    Selenium-Testing as a Service2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Selenium has been a method to test web applications for over a decade, it is interacting directly with the browser and has gained support from both browsers and the community. With the growing amount of browsers, mobile devices and operating systems which a web application is expected to work with, services providing these systems for testing web applications against has gained interest. These services provide testing as a service (TaaS), and runs Selenium-tests in the cloud. This research tried to compare the different services with each other in regard to flexibility, cost, simplicity and reliability. I have also tried to see differences between running the tests locally and using these services. The results showed that there are some differences between the services, and the one best suited might depend on the web application.

  • 193.
    Andersson, Anna
    Linköpings universitet, Institutionen för datavetenskap.
    Management information systems in process-oriented healthcare organisations2003Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis work was to develop a management information system model for process-oriented healthcare organisations. The study explores two questions: “What kinds of requirements do healthcare managers place on information systems?” and “How can the work and information systems of healthcare managers and care providers be incorporated into process-oriented healthcare organisations?”

    The background to the study was the process orientation of Swedish healthcare organisations. The study was conducted at the paediatric clinic of a county hospital in southern Sweden. Organisational process was defined as “a sequence of work procedures that jointly constitute complete healthcare services”, while a functional unit was the organisational venue responsible for a certain set of work activities.

    A qualitative research method, based on a developmental circle, was used. The data was collected from archives, interviews, observations, diaries and focus groups. The material was subsequently analysed in order to categorise, model and develop small-scale theories about information systems.

    The study suggested that computer-based management information systems in processoriented healthcare organisations should: (1) support medical work; (2) integrate clinical and administrative tools; (3) facilitate the ability of the organisation to measure inputs and outcomes.

    The research effort concluded that various healthcare managers need the same type of primary data, though presented in different ways. Professional developers and researchers have paid little attention to the manner in which integrated administrative, financial and clinical systems should be configured in order to ensure optimal support for process-oriented healthcare organisations. Thus, it is important to identify the multiple roles that information plays in such an organisation.

    Delarbeid
    1. Management demands on information and communication technology in process- oriented health-care organizations: The importance of understanding managers expectations during early phases of systems design
    Åpne denne publikasjonen i ny fane eller vindu >>Management demands on information and communication technology in process- oriented health-care organizations: The importance of understanding managers expectations during early phases of systems design
    2002 (engelsk)Inngår i: Journal of Management in Medicine, ISSN 0268-9235, Vol. 16, nr 2-3, s. 159-169Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There are numerous challenges to overcome before information and communication technology (ICT) can achieve its full potential in process-oriented health-care organizations. One of these challenges is designing systems that meet users’ needs, while reflecting a continuously changing organizational environment. Another challenge is to develop ICT that supports both the internal and the external stakeholders’ demands. In this study a qualitative research strategy was used to explore the demands on ICT expressed by managers from functional and process units at a community hospital. The results reveal a multitude of partially competing goals that can make the ICT development process confusing, poor in quality, inefficient and unnecessarily costly. Therefore, from the perspective of ICT development, the main task appears to be to coordinate the different visions and in particular clarify them, as well as to establish the impact that these visions would have on the forthcoming ICT application.

    Emneord
    Communications technology, Health care, Information technology, Management, Organizational development, Systems design
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13778 (URN)10.1108/02689230210434907 (DOI)
    Tilgjengelig fra: 2003-10-06 Laget: 2003-10-06 Sist oppdatert: 2013-09-05
    2. A Model for Interpreting Work and Information Management in Process-Oriented Healthcare Organisations
    Åpne denne publikasjonen i ny fane eller vindu >>A Model for Interpreting Work and Information Management in Process-Oriented Healthcare Organisations
    2003 (engelsk)Inngår i: International Journal of Medical Informatics, ISSN 1386-5056, Vol. 72, nr 1-3, s. 47-56Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Background: To increase productivity, management in healthcare organisations have introduced different types of process-oriented organisational configurations. Few studies have addressed clinical practice and information management in these settings. Methods: A case study was performed at a paediatric clinic. Data was collected from archives, through interviews, by participatory observation, and by performing a focus group session. The collected data was analysed using a qualitative and interpretative research strategy. Results: A model was developed of care practitioners’ daily work in process-oriented organisations. The model shows that clinical work was deeply integrated; the care activities were dependent on supply activities and tightly connected to management routines. Conclusion: The resulting model can be used to support development of health information system (HIS) embedded in process-oriented healthcare work.

    Emneord
    Process-oriented healthcare organisation; Health information system (HIS); Healthcare management; Care process; Case study methods
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13779 (URN)10.1016/j.ijmedinf.2003.09.001 (DOI)
    Tilgjengelig fra: 2003-10-06 Laget: 2003-10-06 Sist oppdatert: 2013-09-05
    3. A Management Information System Model for Process-Oriented Health Care
    Åpne denne publikasjonen i ny fane eller vindu >>A Management Information System Model for Process-Oriented Health Care
    2003 (engelsk)Inngår i: Proceedings of Medinfo 2004, 2003Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13780 (URN)
    Tilgjengelig fra: 2003-10-06 Laget: 2003-10-06 Sist oppdatert: 2013-09-05
  • 194.
    Andersson, Anna
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Eklund, Klara
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    A Study of Oriented Mottle in Halftone Print2007Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    Coated solid bleached board belongs to the top-segment of paperboards. One important property of paperboard is the printability. In this diploma work a specific print defect, oriented mottle, has been studied in association with Iggesund Paperboard. The objectives of the work were to develop a method for analysis of the dark and light areas of oriented mottle, to analyse these areas, and to clarify the effect from the print, coating and paperboard surface related factors. This would clarify the origin of oriented mottle and predict oriented mottle on unprinted paperboard. The objectives were fulfilled by analysing the areas between the dark halftone dots, the amount of coating and the ink penetration, the micro roughness and the topography. The analysis of the areas between the dark halftone dots was performed on several samples and the results were compared regarding different properties. The other methods were only applied on a limited selection of samples. The results from the study showed that the intensity differences between the dark halftone dots were enhanced in the dark areas, the coating amount was lower in the dark areas and the ink did not penetrate into the paperboard. The other results showed that areas with high transmission corresponded to dark areas, smoother micro roughness, lower coating amount and high topography. A combination of the information from these properties might be used to predict oriented mottle. The oriented mottle is probably an optical phenomenon in half tone prints, and originates from variations in the coating and other paperboard properties.

  • 195.
    Andersson, Annika
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Björndahl, Caroline
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska högskolan.
    Säsongssmart - Att kommunicera mat i säsong2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
  • 196.
    Andersson, Björn
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Valfridsson, Martin
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Digital 3D Facial Reconstruction Based on Computed Tomography2005Independent thesis Basic level (professional degree)Oppgave
    Abstract [en]

    Despite the introduction of DNA-analysis for identification of human remains (1997-2000) several cases exist where the deceased remain unidentified. Approximately ten percent of unknown deceased persons can not be identified by dental status or other present methods. During the year 2003 alone, seven individuals, in Sweden, remain unidentified.

    Increase in travel in Europe will lead to more discoveries of foreign human remains in Sweden. In these cases, dental and medical records are often unavailable for the identification process. When reconstructing a face from a skull, a technique with so called landmarks is used. These landmarks define the distance between the skull and the skin.

    Today the reconstruction is performed by a forensic artist applying modelling clay to a cast of the skull according to the placement of the landmarks. This method is considered unethical since it involves manipulation of the skull. Another drawback with this method is that it is very time consuming and changes and modifications of the model are hard to do.

    This thesis presents the possibilities of digitally, in 3D, reconstructing deceased persons'faces based on computed tomography of skulls. This is done by presenting our PC based 3D modelling tool that we have implemented in Discreet 3ds max. By developing and testing our software we have shown that digital 3D facial reconstruction can be performed by acquiring data from CT and performing the reconstruction process in 3ds max withhelp from our software.

  • 197.
    Andersson, Christian
    Linköpings universitet, Institutionen för systemteknik.
    Simulering av filtrerade skärmfärger2005Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This report present a working model for simulation of what happens to colors displayed on screens when they are observed through optical filters. The results of the model can be used to visually, on one screen, simulate another screen with an applied optical filter. The model can also produce CIE color difference values for the simulated screen colors. The model is data driven and requires spectral measurements for at least the screen to be simulated and the physical filters that will be used. The model is divided into three separate modules or steps where each of the modules can be easily replaced by alternative implementations or solutions. Results from tests performed show that the model can be used for prototyping of optical filters even though the tests of the specific algorithms chosen show there is room for improvements in quality. There is nothing that indicates that future work with this model would not produce better quality in its results.

  • 198.
    Andersson, Daniel
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Automatic vertebrae detection and labeling in sagittal magnetic resonance images2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Radiologists are often plagued by limited time for completing their work, with an ever increasing workload. A picture archiving and communication system (PACS) is a platform for daily image reviewing that improves their work environment, and on that platform for example spinal MR images can be reviewed. When reviewing spinal images a radiologist wants vertebrae labels, and in Sectra's PACS platform there is a good opportunity for implementing an automatic method for spinal labeling. In this thesis a method for performing automatic spinal labeling, called a vertebrae classifier, is presented. This method should remove the need for radiologists to perform manual spine labeling, and could be implemented in Sectra's PACS software to improve radiologists overall work experience.Spine labeling is the process of marking vertebrae centres with a name on a spinal image. The method proposed in this thesis for performing that process was developed using a machine learning approach for vertebrae detection in sagittal MR images. The developed classifier works for both the lumbar and the cervical spine, but it is optimized for the lumbar spine. During the development three different methods for the purpose of vertebrae detection were evaluated. Detection is done on multiple sagittal slices. The output from the detection is then labeled using a pictorial structure based algorithm which uses a trained model of the spine to correctly assess correct labeling.

    The suggested method achieves 99.6% recall and 99.9% precision for the lumbar spine. The cervical spine achieves slightly worse performance, with 98.1% for both recall and precision. This result was achieved by training the proposed method on 43 images and validated with 89 images for the lumbar spine. The cervical spine was validated using 26 images. These results are promising, especially for the lumbar spine. However, further evaluation is needed to test the method in a clinical setting.

  • 199.
    Andersson, Daniel
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Sköld, Patrik
    Linköpings universitet, Institutionen för systemteknik.
    Evaluation of a diagnostic tool for use during system development and operations2007Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Rodon is a diagnostic tool developed by Sörman. SAAB’s interest in Rodon regards the possibility to use the tool for development and operations of aircraft systems. The main goal of this thesis was to evaluate the capacity of Rodon and determine how SAAB can use the diagnostic tool during development and operations.

    The tool uses model based diagnosis with artificial intelligence for fault isolation which is a powerful approach. If Rodon is introduced at SAAB, then detailed models of systems will be necessary to create, including the nominal behavior of the system and different faulty behaviors. In order to achieve high quality fault isolation, it is necessary to have complete and consistent models. To be able to use all applications that Rodon feature for a modeled system, preferable characteristics are that the model should be static, have discrete control signals, and have well defined system behavioral modes.

    During development of a system Rodon can be used to improve and easy the work for failure analysis, guidance of sensor placements, evaluation of tests, generation of decision structures, and fault isolation. Since design of tests during development is a desirable application that Rodon does not have, two different methods are presented that utilizes Rodon to generate all possible limit checking tests.

    In conclusion, Rodon can be very useful in several different aspects if introduced, but benefits gained by using Rodon will have to be compared to the labor cost of creating good models.

  • 200.
    Andersson, Ellen
    Linköpings universitet, Institutionen för datavetenskap.
    Cognitive Workload, Game Experience, and Intrinsic Motivation2017Independent thesis Basic level (degree of Bachelor), 12 poäng / 18 hpOppgave
    Abstract [en]

    When it comes to game design, two features that have been linked to the success of a game are playability and the subjective game experience. This is perhaps not surprising, as the main purpose of a game is to entertain. What cognitive factors that may underlie these features has, however, not been explored. This study examines the relationship between both workload and cognitive workload and player experience. The results suggest that an increase in workload, including cognitive workload, positively affect the player experience of the game as well as the player’s intrinsic motivation.

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