liu.seSök publikationer i DiVA
Ändra sökning
Avgränsa sökresultatet
1234567 151 - 200 av 429
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 151.
    Hakam, Imran
    Linköpings universitet, Institutionen för datavetenskap, PELAB - Laboratoriet för programmeringsomgivningar.
    ModelicaML Graphical Modeling Environment Based on Eclipse MDT Papyrus2011Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The ModelicaML graphicalModeling Language and Modelica/UML profile is a language for the description of continuous-time and discrete-time/event-based system dynamics. Modelica ML uses Papyrus as modelling tool implementation platform which is used for editing models. These models may be expressed in UML withoptional textual statements in Modelica as action language code. For the new version ModelicaML 2.0, the need for support in the new Papyrus M1 version was essential. In this master thesis project, new plug-in functionality was developed that has enhanced the existing functionality of the ModelicaML modelling environment within the Papyrus Eclipse plug-in. This includes handling Modelica modifiers as well as new views and component tree views which provides complete list of components for a selected class.

  • 152.
    Hallgren, Ellen
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    A Problem Analysis at Tieto Leading to the Development of a Test-Data-Handler Application2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med examensarbetet är att ge Maftaki teamet vid Tieto ett förslag på ett verktyg eller förbättra ett av de nuvarande verktygen för att ge support till deras processer. För att hitta ett lämpligt verktyg gjordes först en problemanalys, den problemanalysmodell som beskrivs i Goldkuhl och Röstlinger, (1988), bok användes. För att ta reda på vilka problem som kunde finnas genomförde ett antal intervjuer med medlemmar i Maftaki. Ur de problem som hade kommit fram under intervjuerna valdes svårigheten att hitta telefonnummer som kan användas i testmiljön vid testning ut.

    För att lösa problemet beslutades att ett verktyg som hanterar testdata skulle utvecklas. Först genomfördes en kravfångst genom att intervjua potentiella användare och på så sätt togs användningsfall och funktionella krav fram. För att bygga applikationen användes ett ramverk som heter Struts2, ett Object/Relational Mapping ramverk, Hibernate, och en Inversion of Control container, Spring. För att bygga applikationen användes Maven.

    Under utvecklingens gång genomfördes demos för att få fler krav ifrån användare och för att få en klarare bild av betydelsen av vissa krav. Också omstrukturering av kod genomfördes kontinuerligt under utvecklingens gång. Sist av allt genomfördes ett antal test på applikationen.

  • 153.
    Hallin, Magnus
    Linköpings universitet, Institutionen för datavetenskap.
    SMT-Based Reasoning and Planning in TAL2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Automated planning as a satisfiability problem is a method developed in theearly nineties. It has some known disadvantages, such as its inefficient encod-ing of numbers. The field of Satisfiability Modulo Teories tries to connectalready established solvers for e.g. linear constraints into SAT-solvers in orderto make reasoning about numerical values more efficient. This thesis combines planning as satisfiability and SMT to perform efficientreasoning about actions that occupy realistic time in Temporal Action Logic,a formalism developed at Linköping University for reasoning about action andchange.

  • 154.
    Han, Dapeng
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    FPGA Implementation of an AC3 Decoder2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of this thesis is to explore the possibility of integrating an AC3 audio de- coding module into the company’s current product. Due to limited left resources on the FPGA chip in the company’s current product, the focus of this thesis is to be resource efficient. In this thesis, a system for AC3 audio decoding is designed and implemented. In order to use less logic on FPGA, PicoBlaze soft processor is used to control the whole processing flow. The system is designed and synthe- sized for a Spartan-6 FPGA which can be easily ported to the company’s current platform. 

  • 155.
    He, Qing
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    A Comprehensive Analysis of Optimal Link Scheduling for Emptying a Wireless Network2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wireless communications have become an important part of modern life. The ubiquitous wireless networks and connectivities generate exponentially increasing data traffic. In view of this, wireless network optimization, which aims at utilizing the limited resource, especially spectrum and energy, as efficiently as possible from a network perspective, is essential for performance improvement and sustainable development of wireless communications.

    In the dissertation, we focus on a fundamental problem of wireless network optimization, link scheduling, as well as its subproblem, link activation. The problem type arises because of the nature of wireless media and hence it is of relevance to a wide range of networks with multiple access. We freshen these classic problems up by novel extensions incorporating new technologies of interference management or with new performance metrics. We also revisit the problems in their classic setup to gain new theoretical results and insights for problem-solving. Throughout the study, we consider the problems with a general setup, such that the insights presented in this dissertation are not constrained to a specific technology or network type. Since link activation and scheduling are key elements of access coordination in wireless communications, the study opens up new approaches that significantly improve network performance, and eventually benefit practical applications.

    The dissertation consists of five research papers. The first paper addresses maximum link activation with cooperative transmission and interference cancellation. Papers II and III investigate the minimum-time link scheduling problem in general and a particular class of networks, respectively. In Paper IV, we consider the scheduling problem of emptying a network in its broad form and provide a general optimality condition. In Paper V, we study the scheduling problem with respect to age of information.

    Delarbeten
    1. Maximum Link Activation with Cooperative Transmission and Interference Cancellation in Wireless Networks
    Öppna denna publikation i ny flik eller fönster >>Maximum Link Activation with Cooperative Transmission and Interference Cancellation in Wireless Networks
    2017 (Engelska)Ingår i: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 16, nr 2, s. 408-421Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We address the maximum link activation problem in wireless networks with new features, namely when the transmitters can perform cooperative transmission, and the receivers are able to perform successive interference cancellation. In this new problem setting, which transmitters should transmit and to whom, as well as the optimal cancellation patterns at the receivers, are strongly intertwined. We present contributions along three lines. First, we provide a thorough tractability analysis, proving the NP-hardness as well as identifying tractable cases. Second, for benchmarking purposes, we deploy integer linear programming for achieving global optimum using off-theshelf optimization methods. Third, to overcome the scalability issue of integer programming, we design a sub-optimal but efficient optimization algorithm for the problem in its general form, by embedding maximum-weighted bipartite matching into local search. Numerical results are presented for performance evaluation, to validate the benefit of cooperative transmission and interference cancellation for maximum link activation and to demonstrate the effectiveness of the proposed algorithm.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2017
    Nationell ämneskategori
    Kommunikationssystem Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-112447 (URN)10.1109/TMC.2016.2546906 (DOI)000393808500009 ()
    Konferens
    2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), September 2-5, Washington DC, DC, USA
    Anmärkning

    Funding agencies: Swedish Research Council; EU FP7 Marie Curie [324515, 329313]; National Science Foundation [CCF-0728966, CCF-1420651]; ONR [N000141410107]

    Tillgänglig från: 2014-11-27 Skapad: 2014-11-27 Senast uppdaterad: 2018-08-14Bibliografiskt granskad
    2. Minimum-Time Link Scheduling for Emptying Wireless Systems: Solution Characterization and Algorithmic Framework
    Öppna denna publikation i ny flik eller fönster >>Minimum-Time Link Scheduling for Emptying Wireless Systems: Solution Characterization and Algorithmic Framework
    2014 (Engelska)Ingår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 60, nr 2, s. 1083-1100Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We consider a set of transmitter-receiver pairs, or links, that share a wireless medium and address the problem of emptying backlogged queues with given initial size at the transmitters in minimum time. The problem amounts to determining activation subsets of links, and their time durations, to form a minimum-time schedule. Scheduling in wireless networks has been studied under various formulations before. In this paper, we present fundamental insights and solution characterizations that include: 1) showing that the complexity of the problem remains high for any continuous and increasing rate function; 2) formulating and proving sufficient and necessary optimality conditions of two baseline scheduling strategies that correspond to emptying the queues using one-at-a-time or all-at-once strategies; and 3) presenting and proving the tractability of the special case in which the transmission rates are functions only of the cardinality of the link activation sets. These results are independent of physical-layer system specifications and are valid for any form of rate function. We then develop an algorithmic framework for the solution to this problem. The framework encompasses exact as well as sub-optimal, but fast, scheduling algorithms, all under a unified principle design. Through computational experiments, we finally investigate the performance of several specific algorithms from this framework.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2014
    Nyckelord
    Algorithm; optimality; scheduling; wireless networks
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-104836 (URN)10.1109/TIT.2013.2292065 (DOI)000330286100022 ()
    Tillgänglig från: 2014-02-28 Skapad: 2014-02-28 Senast uppdaterad: 2018-08-14
    3. Polynomial Complexity Minimum-Time Scheduling in a Class of Wireless Networks
    Öppna denna publikation i ny flik eller fönster >>Polynomial Complexity Minimum-Time Scheduling in a Class of Wireless Networks
    2016 (Engelska)Ingår i: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 3, nr 3, s. 322-331Artikel i tidskrift (Övrigt vetenskapligt) Published
    Abstract [en]

    We consider a wireless network with a set of transmitter-receiver pairs, or links, that share a common channel, and address the problem of emptying finite traffic volume from the transmitters in minimum time. This, so called, minimum-time scheduling problem has been proved to be NP-hard in general. In this paper, we study a class of minimum-time scheduling problems in which the link rates have a particular structure. We show that global optimality can be reached in polynomial time and derive optimality conditions. Then we consider a more general case in which we apply the same approach and obtain an approximation as well as lower and upper bounds to the optimal solution. Simulation results confirm and validate our approach.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Nyckelord
    algorithm, interference, optimality, scheduling, wireless networks
    Nationell ämneskategori
    Kommunikationssystem Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-112446 (URN)10.1109/TCNS.2015.2512678 (DOI)000384701100010 ()
    Anmärkning

    At the time for thesis presentation publication was in status: Manuscript

    Tillgänglig från: 2014-11-27 Skapad: 2014-11-27 Senast uppdaterad: 2019-07-15Bibliografiskt granskad
    4. A general optimality condition of link scheduling for emptying a wireless network
    Öppna denna publikation i ny flik eller fönster >>A general optimality condition of link scheduling for emptying a wireless network
    2016 (Engelska)Ingår i: 2016 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, IEEE , 2016, s. 1446-1450Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    We consider link scheduling in wireless networks for emptying the queues of the source nodes, and provide a unified mathematical formulation that accommodates all meaningful settings of link transmission rates and network configurations. We prove that, any scheduling problem is equivalent to solving a convex problem defined over the convex hull of the rate region. Based on the fundamental insight, a general optimality condition is derived, that yields a unified treatment of optimal scheduling. Furthermore, we demonstrate the implications and usefulness of the result. Specifically, by applying the theoretical insight to optimality characterization and complexity analysis of scheduling problems, we can both unify and extend previously obtained results.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2016
    Serie
    IEEE International Symposium on Information Theory. Proceedings, ISSN 2157-8095, E-ISSN 2157-8117
    Nyckelord
    convex programming;radio links;radio networks;telecommunication scheduling;convex hull;convex problem;general optimality condition;link scheduling;link transmission rates;network configurations;optimal scheduling;source nodes;wireless network;Complexity theory;Information theory;Interference;Optimal scheduling;Processor scheduling;Scheduling;Wireless networks;complexity;optimality;scheduling;wireless networks
    Nationell ämneskategori
    Datorteknik Systemvetenskap, informationssystem och informatik Programvaruteknik
    Identifikatorer
    urn:nbn:se:liu:diva-131357 (URN)10.1109/ISIT.2016.7541538 (DOI)000390098701102 ()
    Konferens
    IEEE International Symposium on Information Theory (ISIT), 2016, Universitat Pompeu Fabra, Barcelona, Spain, July l0-l5, 2016
    Tillgänglig från: 2016-09-15 Skapad: 2016-09-15 Senast uppdaterad: 2018-08-14Bibliografiskt granskad
  • 156.
    Hedin, Adam
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska högskolan.
    Konstruktion av styrelektronik till testfixtur2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete är utfört inom elektronikkonstruktion och beskriver koncept- och prototyputveckling av styrelektronik i form av ett kretskort med mikrokontroller. Uppdragsgivaren utvecklar testutrustningar som används för automatiserad produkttestning inom elektronikproduktion och behöver ett nytt styrsystem till utrustningen som kan hantera styrning och generella testfall. I arbetet utreds vad som krävs av ett sådant styrsystem och en prototyp designas och tillverkas.

    Prototypen har utvecklats med fokus på skydd mot elektrostatiska urladdningar och överspänningar. Funktioner som ingår i prototypen är spänningsmätningar, kommunikationsgränssnitt och styrning av in- och utspänningar. Mjukvara till prototypen har utvecklats och har konfigurerats för anslutning till PC genom USB för styrning samt inläsning av mätdata. 

  • 157.
    Hedin, Alexander
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Testing and evaluation of the integratability of the Senior processor2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Den första versionen av Senior processorn skapades som en del i ett examensarbe-te under 2007, denna processor färdigställdes och användes i utbildningssyfte påLinköping Universitet. 2008 optimerades flera delar av processorn och utökadesmed extra funktionalitet som del av ytterligare ett examensarbete. 2009 startadeett EU finansierat projekt vid namn MULTI-BASE, som ISYs Datortekniks avdel-ning deltar i. Till deras del av MULTI-BASE projektet valdes Senior processorn attanvändas, efter ytterligare utveckling skickades denna processor för tillverkning.

    Detta examensarbete hade i uppgift att testa och verifiera de olika funktionernasom Senior processorn har implementerats med. För att göra detta tillverkades ettkretskort som ska användas för att testa Senior processorn tillsammans med enVirtex-4 FPGA. Utförliga tester gjordes på de viktigaste funktionerna hos Seniorprocessorn, dessa tester visade att den tillverkade Senior processorn fungerar somplanerat. Den kan på egen hand utföra större beräkningar och använda sig avexterna hårdvare acceleratorer med hjälp av sina olika gränssnitt.

  • 158.
    Henriksson, Jonas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Implementation of a real-time Fast Fourier Transform on a Graphics Processing Unit with data streamed from a high-performance digitizer2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis we evaluate the prospects of performing real-time digital signal processing on a graphics processing unit (GPU) when linked together with a high-performance digitizer. A graphics card is acquired and an implementation developed that address issues such as transportation of data and capability of coping with the throughput of the data stream. Furthermore, it consists of an algorithm for executing consecutive fast Fourier transforms on the digitized signal together with averaging and visualization of the output spectrum.

    An empirical approach has been used when researching different available options for streaming data. For better performance, an analysis of the introduced noise of using single-precision over double-precision has been performed to decide on the required precision in the context of this thesis. The choice of graphics card is based on an empirical investigation coupled with a measurement-based approach.

    An implementation in single-precision with streaming from the digitizer, by means of double buffering in CPU RAM, capable of speeds up to 3.0 GB/s is presented. Measurements indicate that even higher bandwidths are possible without overflowing the GPU. Tests show that the implementation is capable of computing the spectrum for transform sizes of , however measurements indicate that higher and lower transform sizes are possible. The results of the computations are visualized in real-time.

  • 159.
    Hinrichsen, Oscar
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    An Evaluation of Network Protocols for Bluetooth Low Energy Mesh Networks2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sakernas Internet (IoT) är ett scenario som skisserar objekt och människor som potentiella noder i ett ständigt växande trådlöst nätverk. Denna vision driver utvecklingen av trådlösa lågkostnadsteknologier som kan köras på portabla strömkällor i flera månader. En kandiderande teknik som har visat goda resultat inom detta område är Bluetooth Low Energy (BLE). Detta uppsatsarbete studerar flera tekniker för att möjliggöra och upprätthålla storskaliga meshnätverk över BLE-kommunikation. Den inledande studien granskar ett existerande översvämningsbaserat meshprotokoll för BLE. Uppsatsarbetet presenterar därefter ett förbättrat protokoll som reducerar strömförbrukningen med avseende på kvoten mellan antalet mottagna paket genom antalet skickade paket. Ytterliggare upprustningar som tillkommer i det förbättrade protokollet är en procedur för självanpassning, samt en algorithm för dirigering av paket. Simuleringar visar att det förbättrade protokollet kan spara upp till 50 % av strömkonsumptionen för en enhet, jämfört med originalprotokollet.

  • 160.
    Hjelmberg, Eric
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Rowell, Henrik
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Persondetektering i inomhusmiljö med enkla sensorer2015Självständigt arbete på grundnivå (högskoleexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport syftar till att beskriva arbetet kring att kunna detektera närvaro i ett rum medhjälp av så enkla sensorer som möjligt, kopplade till en Arduino. Samtidigt som detta skerså används också systemet till att med samma sensorer visa klimatet i rummet. Läsaren fåren inblick i problematiken med att detektera människor samt inom funktionen av de valdasensorerna. Utöver detta studeras energiförbrukningen i systemet. Rapportenmynnar ut i enslutsats där en procentuell chans för närvaro presenteras via en internetuppkoppling medhjälp av en omfattande testning av sensorernas beteende.

  • 161.
    Hochwallner, Martin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell Produktion. Linköpings universitet, Tekniska fakulteten.
    On Motion Control of Linear Incremental Hydraulic Actuators2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Linear Incremental Hydraulic Actuators combine one or more short-stroke cylinders, and two or more engaging/disengaging mechanisms into one actuator with long, medium, or even unlimited stroke length. The motion of each single short-stroke actuator concatenated by the engaging/disengaging mechanisms forms the motion of the linear incremental hydraulic actuator.

    The patterns of how these motions are concatenated form the gaits of a specific linear incremental hydraulic actuator. Linear incremental hydraulic actuators may have more than one gait. In an application, the gaits may be combined to achieve optimal performance at various operating points.

    The distinguishing characteristic of linear incremental hydraulic actuators is the incremental motion. The term incremental actuator is seen as analogous to the incremental versus absolute position sensor. Incremental actuators realize naturally relative positioning. Incremental motion means also that the behavior does not depend on an absolute position but only on the relative position within a cycle or step.

    Incremental actuators may realize discrete incremental or continuous incremental motion. Discrete incremental actuators can only approach discrete positions, whereby stepper drives are one prominent example. In contrast, continuous incremental actuators may approach any position. Linear electric motors are one example of continuous incremental actuators. The actuator has no inherent limitation in stroke length, as every step or cycle adds only to the state at the beginning of the step or cycle and does not depend on the absolute position. This led to the alternative working title Hydraulic Infinite Linear Actuator.

    Linear incremental hydraulic actuator provides long stroke, high force, and linear motion and has the potential to

    • decrease the necessary resource usage,
    • minimize environmental impact, e.g. from potential oil spillage,
    • extend the range of feasible products: longer, stiffer, better, etc.

    This thesis presents an analysis of the characteristics and properties of linear incremental hydraulic actuators as well as the gaits and possible realizations of some gaits. The gait for continuous, smooth motion with two cylinders is comprehensively studied and a control concept for the tracking problem is proposed. The control concept encapsulates the complexity of the linear incremental hydraulic actuator so that an application does not have to deal with it. One other gait, the ballistic gait, which realizes fast, energy-efficient motion, enabling energy recuperation is studied.

  • 162.
    Holgersson, Stefan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Informatik. Linköpings universitet, Filosofiska fakulteten.
    Melin, Ulf
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Informatik. Linköpings universitet, Filosofiska fakulteten.
    Pragmatic Dilemmas in Action Research: Doing Action Research With or Without the Approval of Top Management?2015Ingår i: Systemic Practice and Action Research, ISSN 1094-429X, E-ISSN 1573-9295, Vol. 28, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article problematizes a basic assumption that action research should be conducted in terms of acceptance by management. The importance of approval from the responsible stakeholders at the work practice, which is the subject of action research, has traditionally been emphasized in academic literature. External pressure can constrain an organisation to initiate and fulfil different types of needs for change. In this article we address the question of whether it is appropriate to accomplish action research in a way that creates pressure on an organisation to act. If the public risks suffering as a result of an organisation´s inability or unwillingness to identify and rectify serious problems, there are strong arguments to answer “yes” to this question. This answer is particularly relevant when it comes to governmental organisations. The public has a legitimate requirement that tax-financed organisations should be well-functioning. This article illustrates how action research can put pressure on a work practice, and discusses the problems and challenges of this type of research design. An important contribution to action research literature based on this paper is that it shows that the dilemma in action research of balancing practice interests and those of science is not just about dealing with a dual agenda. The interest of the practice interests is multi-faceted. This paper points at the relationship between action research and principles for conducting critical research in information systems. Practical implications that can be drawn based on this paper are for example that it clarifies the challenge of different considerations that may be eligible in action research.

  • 163.
    Holmlid, Stefan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Björndal, Petra
    ABB Corporate Research; Kungliga tekniska högskolan, Stockholm, Sweden.
    Mapping What Actors Know When Integrating Resources: Towards a Service Information Canvas2016Ingår i: Service design geographies: Proceedings of the ServDes.2016 Conference / [ed] Nicola Morelli, Amalia de Götzen and Francesco Grani, Linköping: Linköping University Electronic Press, 2016, Vol. 125, s. 544-550Konferensbidrag (Refereegranskat)
    Abstract [en]

    Even though service is described as actors integrating resources to achieve values, research on perspectives on knowledge that these actors have when integrating resources has not been part of service design research. In this paper we experiment with a technique, based in a service scenario, to map what actors know as a consequence of the events in the service process. We suggest that the technique called Service Information Canvas is valuable in a service design toolbox, and give access to understanding of service processes that is not currently available through other design tools.

  • 164.
    Hotz, Ingrid
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten. German Aerospace Center.
    Flatken, Markus
    German Aerospace Center - DLR.
    Berres, Anne
    University of Kaiserslautern.
    Merkel, Jonas
    University of Kaiserslautern.
    Gerndt, Andreas
    German Aeorspace Center (DLR).
    Hagen, Hans
    University Kaiserslautern.
    Dynamic Schedulig for Progressive Large-Scale Visualization2015Konferensbidrag (Refereegranskat)
  • 165.
    Huang, Qing
    Linköpings universitet, Institutionen för datavetenskap.
    An extension to the Android access control framework2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Several nice hardware functionalities located at the low level of operating system onmobile phones could be utilized in a better way if they are available to applicationdevelopers. With their help, developers are able to bring overall user experienceto a new level in terms of developing novel applications. For instance, one of thosehardware functionalities, SIM-card authentication is able to offer stronger andmore convenient way of authentication when compared to the traditional approach.Replacing the username-password combination with the SIM-card authentication,users are freed from memorizing passwords. However, since normally those kindsof functionalities are locked up at the low level, they are only accessible by a fewusers who have been given privileged access rights. To let the normal applicationsbe benefiting as well, they need to be made accessible at the application level. Onthe one hand, as we see the benefit it will bring to us, there is a clear intentionto open it up, however, on the other hand, there is also a limitation resultingfrom their security-critical nature that needs to be placed when accessing whichis restricting the access to trusted third parties.

    Our investigation is based on the Android platform. The problem that we havediscovered is the existing security mechanism in Android is not able to satisfy everyregards of requirements we mentioned above when exposing SIM-card authenticationfunctionality. Hence, our requirement on enhancing the access control modelof Android comes naturally. In order to better suit the needs, we proposed a solutionWhite lists & Domains (WITDOM) to improve its current situation in thethesis. The proposed solution is an extension to the existing access control modelin Android that allows alternative ways to specify access controls therefore complementingthe existing Android security mechanisms. We have both designedand implemented the solution and the result shows that with the service that weprovided, critical functionalities, such as APIs for the low-level hardware functionalitycan retain the same level of protection however in the meanwhile, with moreflexible protection mechanism.

  • 166.
    Hultman, Johan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    A software system for defining and controlling actions in a mechanical system1988Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with the subject of technical systems where machinery, usually of mechanical character, are controlled by a computer system. Sensors in the system provide information about a machine’s current state, and are crucial for the controlling computer. The thesis presents an architecture for such a software system and then describes the actual implementation along with some examples.

  • 167.
    Hultman, Tim
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Signal-Aware Route Planning2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Modern vehicles have an increasing number of advanced features requiring network coverage in order to function properly. In order to facilitate the requirements of such features and allow more advanced applications, we consider the possibility of planning routes that take signal strength into consideration. Previous work have shown the relationship between TCP throughput/goodput and signal strength. In this thesis signal-aware route planning is presented, implemented, and validated. Crowd-sourced map and signal data (3G) from two sources is used for building a signal coverage map. The signal and map data is validated in a field experiment, where routes were travelled while measuring the signal strength. The field experiment showed gains in signal characteristics when deviating from the shortest possible path. The average signal strength increased by 11 dBm between algorithms and the shortest possible path. Lastly, routes were planned for all possible sources and destinations in a given urban area. The results of this calculation confirms the patterns found in the field experiment.

  • 168.
    Hussain, Shahbaz
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Finding Correlation and Predicting System Behavior in Large IT Infrastructure2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Modern IT development infrastructure has a large number of components that must be monitored, for instance servers and network components. Various system-metrics (build time, CPU utilization, queries time etc.) are gathered to monitor system performance. In practice, it is extremely difficult for a system administrator to observe a correlation between several systemmetrics and predict a target system-metric based on highly correlated system-metrics without machine learning support.

    The experiments were performed on development logs at Ericsson. There were many system-metrics available in the system. Our goal is use machine learning techniques to find correlation between buildtime and other system-metrics and predict its trends in the future.

  • 169.
    Ingemarsson, Carl
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    SFF—The Single-Stream FPGA-Optimized Feedforward FFT Hardware Architecture2018Ingår i: Journal of Signal Processing Systems, ISSN 1939-8018, E-ISSN 1939-8115, Vol. 90, nr 11, s. 1583-1592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a fast Fourier transform (FFT) hardware architecture optimized for field-programmable gate-arrays (FPGAs) is proposed. We refer to this as the single-stream FPGA-optimized feedforward (SFF) architecture. By using a stage that trades adders for shift registers as compared with the single-path delay feedback (SDF) architecture the efficient implementation of short shift registers in Xilinx FPGAs can be exploited. Moreover, this stage can be combined with ordinary or optimized SDF stages such that adders are only traded for shift registers when beneficial. The resulting structures are well-suited for FPGA implementation, especially when efficient implementation of short shift registers is available. This holds for at least contemporary Xilinx FPGAs. The results show that the proposed architectures improve on the current state of the art.

  • 170.
    Ingemarsson, Ingemar
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Fåk, Viiveke
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Forchheimer, Robert
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Blom, Rolf
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Computer Security 19811976Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The goal of COMPUTER SECURITY 1981 is to prediet the demand for protection of eleetronic data processing (EDP) and for the information processed. To predict the future demands on computer security we have discussed the issue with several people involved in one way or another with EDP. These discussions, our own knowledge other background material have been the material for discussions amongst the authors. The results are divided into two parts. In the first part (section 4) we have been as objective as possible. In the latter part (section 5) we have discussed the differences between the results in section 4 and our own opinion as proffessional researchers.

    In addition the report covers a summary of how EDP is used 1981 and a section describing the structure of the security field (which we have used in the interviews) and an outline of the investigation.

  • 171.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Integration of Ontology Alignment and Ontology Debugging for Taxonomy Networks2014Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Semantically-enabled applications, such as ontology-based search and data integration, take into account the semantics of the input data in their algorithms. Such applications often use ontologies, which model the application domains in question, as well as alignments, which provide information about the relationships between the terms in the different ontologies.

    The quality and reliability of the results of such applications depend directly on the correctness and completeness of the ontologies and alignments they utilize. Traditionally, ontology debugging discovers defects in ontologies and alignments and provides means for improving their correctness and completeness, while ontology alignment establishes the relationships between the terms in the different ontologies, thus addressing completeness of alignments.

    This thesis focuses on the integration of ontology alignment and debugging for taxonomy networks which are formed by taxonomies, the most widely used kind of ontologies, connected through alignments.

    The contributions of this thesis include the following. To the best of our knowledge, we have developed the first approach and framework that integrate ontology alignment and debugging, and allow debugging of modelling defects both in the structure of the taxonomies as well as in their alignments. As debugging modelling defects requires domain knowledge, we have developed algorithms that employ the domain knowledge intrinsic to the network to detect and repair modelling defects.

    Further, a system has been implemented and several experiments with real-world ontologies have been performed in order to demonstrate the advantages of our integrated ontology alignment and debugging approach. For instance, in one of the experiments with the well-known ontologies and alignment from the Anatomy track in Ontology Alignment Evaluation Initiative 2010, 203 modelling defects (concerning incomplete and incorrect information) were discovered and repaired.

  • 172.
    Jackson, Marcus
    Linköpings universitet, Institutionen för datavetenskap.
    Program för digitala prov: Och hur programmet möter kraven som ställs när det används i gymnasieskolan2018Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Under de senaste två årtionden har det blivit en drastisk ökning av privat ägda laptops. Detta har öppnat för nya möjligheter som bring your own device (BYOD) digitala prov i skolan. Men med detta blir nedlåsning av datorn inför digitalt prov ännu viktigare. Undersökningar har gjorts gällande elevernas uppfattning kring digitala provsystem samt deras åsikter om digitala prov i allmänhet. Andra arbeten har gjorts gällande hur digitala provsystem fungerar tekniskt men samtidigt finns det artiklar som visar hur viktig lärarnas åsikter är. Därför kommer detta arbete definiera kraven som de krav som lärare har för att undersöka deras perspektiv, inte på det digitala prov eller provsystem som andra arbeten utan på nedlåsningsprogrammet för datorn vilket bidrar med information i ett nytt perspektiv. Detta görs genom insamling av enkäter från lärarna på en gymnasieskola för att definiera krav. Dessa krav ställs sedan mot vanligt använda nedlåsningsprogram för att svara på hur de klarar av de krav som lärare har. Resultatet av detta visar att nedlåsningsprogrammen inte uppfyller alla krav som lärarna ställer. Dock vid undersökning av de krav som underkändes bedöms nedlåsningsprogrammen leva upp till en majoritet av lärarnas krav då anpassade lösningar och vikten av olika krav disskuteras. Detta ger ett positivt betyg för nedlåsningsprogrammen och ger uppmaning till lärare att gå över till digitala prov utan att oroa sig för nedlåsningen av datorerna.

  • 173.
    Jang, Jeong Keun
    et al.
    Dongbu Hitek, South Korea.
    Kim, Ho Keun
    Ajou University, South Korea.
    Sunwoo, Myung Hoon
    Ajou University, South Korea.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Area-efficient scheduling scheme based FFT processor for various OFDM systems2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents an area-efficient fast Fouriertransform (FFT) processor for orthogonal frequency-division multiplexing systems based on multi-path delay commutator architecture. This paper proposes a data scheduling scheme to reduce the number of complex constant multipliers. The proposed mixed-radix multi-path delay commutator FFT processor can support 128-, 256-, and 512-point FFT sizes. The proposed processor was synthesized using the Samsung 65-nm CMOS standard cell library. The proposed processor with eight parallel data paths can achieve a high throughput rate of up to 2.64 GSample/s at 330 MHz.

  • 174.
    Janzén, Johan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Evaluation of Energy-Optimizing Scheduling Algorithms for Streaming Computations on Massively Parallel Multicore Architectures2014Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis describes an environment to evaluate and compare static schedulers for real pipelined streaming applications on massively parallel architectures, such as Intel Single chip Cloud Computer (SCC), Adapteva Epiphany, and Tilera TILE-Gx series. The framework allows performance comparison of schedulers in their execution time, or the energy usage of static schedules with energy models and measurements on real platform.

    This thesis focuses on the implementation of a framework evaluating the energy consumption of such streaming applications on the SCC. The framework can run streaming applications, built as task collections, with static schedules including dynamic frequency scaling. Streams are handled by the framework with FIFO buffers, connected between tasks.

    We evaluate the framework by considering a pipelined mergesort implementation with different static schedules. The runtime is compared with the runtime of a previously published task based optimized mergesort implementation. The results show how much overhead the framework adds on to the streaming application. As a demonstration of the energy measuring capabilities, we schedule and analyze a Fast Fourier Transform application, and discuss the results.

    Future work may include quantitative comparative studies of a range of different static schedulers. This has, to our knowledge, not been done previously.

  • 175.
    Jernlås, Johan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Evaluation of virtual servers for use incomputer science education: Utvardering av virtuella servrar f ör användning inom undervisning i datateknik2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Virtual servers are being increasingly utilized in higher education forclient computers, this thesis investigates if virtualization could also bebeneficial for servers. By providing three general models (the first beingthe current situation and the two latter leveraging virtualization) andevaluating each, a broad sense of the applicability, possibilities andremaining problems of introducing server virtualization is provided.For one specific course, TDDD27 - Advanced web programming, amore concrete analysis is done and specific recommendations are pro-vided.The conclusion is that there are still more work to be done, butboth of the proposed models are possible and suitable for some courses.Their introduction should have several positive effects, for instancefairer courses and more focus on the subject at hand.

  • 176.
    Jiang, Ke
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Security-Driven Design of Real-Time Embedded Systems2015Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Real-time embedded systems (RTESs) have been widely used in modern society. And it is also very common to find them in safety and security critical applications, such as transportation and medical equipment. There are, usually, several constraints imposed on a RTES, for example, timing, resource, energy, and performance, which must be satisfied simultaneously. This makes the design of such systems a difficult problem.

    More recently, the security of RTESs emerges as a major design concern, as more and more attacks have been reported. However, RTES security, as a parameter to be considered during the design process, has been overlooked in the past. This thesis approaches the design of secure RTESs focusing on aspects that are particularly important in the context of RTES, such as communication confidentiality and side-channel attack resistance.

    Several techniques are presented in this thesis for designing secure RTESs, including hardware/software co-design techniques for communication confidentiality on distributed platforms, a global framework for secure multi-mode real-time systems, and a scheduling policy for thwarting differential power analysis attacks. 

    All the proposed solutions have been extensively evaluated in a large amount of experiments, including two real-life case studies, which demonstrate the efficiency of the presented techniques.

  • 177.
    Johansson, Anthon
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    How can Atlassian products be modified to reduce the average time usage for common tasks2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Software tools such as Build systems and project management tools are sometimes notwell designed when it comes to usability. This paper investigates the possibility of creatingcustom solutions for the three Atlassian products Jira, Confluence, and BitBucket, in orderto increase the efficiency when performing common tasks at the Atlassian administration atSaab AB. It was discovered that the main issue was performing reoccurring project-accesspermission audits, which was a very repetitive task with many manual steps involved.The solution to the issue was a Python script that, through the use of the Atlassian RESTAPI, could collect all the necessary information automatically and present it in a readablesummarized view. The amount of manual steps was significantly decreased to just a fewsteps which made a huge difference for the Atlassian administrators at Saab AB.

  • 178.
    Johansson, Cristina
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Multiobjective Optimization for Safety and Reliability Trade-off: Applications on Early Phases of Aircraft Systems Design2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A strategic issue for any industrial company is to conceive safe and reliable systems while performing all systems’ intended functions at a minimum cost. System safety and reliability are fundamental to system design and involve a quantitative assessment prior to system development. Aircraft design is a multifaceted process that involves several different disciplines, system safety and reliability among them, to obtain o holistic approach of a complex product. During the last decades, the idea of trade-off between safety or reliability goals against other characteristics has become more prominent. Furthermore, while predictions of system performance can be made in early design phases with credible precision, within reasonable tolerances, reliability and system safety are seldom predicted with high accuracy and confidence. Making the right design decisions in the early design phase is vital to the success of a project. Nowadays, it is essential within the design of new products, to increase awareness (knowledge) early in the design phases and keep the design decisions (freedom) open as long as possible, and with that also keep down the allocated costs.

    This thesis presents MOSART (Multiobjective Optimization for Safety and Reliability Trade-off), a method promoting a systematic approach regarding trade-offs between system safety and reliability goals against other contradictory targets, such as weight and cost, in early design phases.

    A theoretical framework and context are presented in the first part of the thesis, including system safety and reliability methods and optimization techniques. The second and third parts are dedicated to contributions and papers, where seven papers are included. These papers approach different aspects of MOSART, from the basic idea to the implementation and usage of the method in the conceptual phase of aircraft systems design. Several aspects regarding the choice of system safety and reliability methods in early design phases are also included in the papers, e.g. evaluation of applicability of reliability methods in early design phases, considerations around the usage of these methods within the MOSART framework and a proposal of a guideline for how to choose the right reliability method. All the examples used in the papers are chosen from basic aircraft sub-systems.

    Delarbeten
    1. On the Usage of Reliability Methods in Early Design Phases
    Öppna denna publikation i ny flik eller fönster >>On the Usage of Reliability Methods in Early Design Phases
    2012 (Engelska)Ingår i: Proceedings of the 11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012 (PSAM11 ESREL 2012), Curran Associates, Inc., 2012, s. 769-778Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    One important challenge in the early phases of product development is to apply reliability methods for estimating the safety and reliability of the system when information about the chosen equipment and components is limited. For systems consisting of units with several degraded states, and not only “up” and “down”, the results from reliability and system safety analysis are often difficult to interpret and use. The main contribution of this paper is to evaluate the applicability of different reliability methods for analyzing an overall system concept in early development stages. Furthermore, the paper constitutes the first step of a methodology intended to address the issues outlined above from a practical point of view. In the paper, two static methods, Reliability Block Diagram and Fault Tree Analysis, and one dynamic method, Markov Analysis, have been applied to conceptual design of an aircraft electrical system. These three methods have been evaluated regarding usefulness, modeling possibilities and applicability in the conceptual design. Each method is, from a practical point of view, dependent on the limitations of the software that is used. In order to overcome this issue the calculations and partly the modeling have been performed in three different software tools.

    Two iterations have been performed for Markov Analysis, and the results are used to evaluate the method regarding applicability and possibilities of modeling the system and to find out what results can be gained by extending the model.

    Ort, förlag, år, upplaga, sidor
    Curran Associates, Inc., 2012
    Nyckelord
    System Reliability, Markov Analysis, Reliability Block Diagram, Fault Tree
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-94350 (URN)978-1-62276-436-5 (ISBN)
    Konferens
    11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012 (PSAM11 ESREL 2012), 25-29 June, Helsinki, Finland
    Tillgänglig från: 2013-06-25 Skapad: 2013-06-25 Senast uppdaterad: 2017-02-20Bibliografiskt granskad
    2. Choosing the reliability approach: A guideline for selecting the appropriate reliability method in the design process
    Öppna denna publikation i ny flik eller fönster >>Choosing the reliability approach: A guideline for selecting the appropriate reliability method in the design process
    2013 (Engelska)Ingår i: Proceedings of the 20th Advances in Risk and Reliability Technology Symposium 21–23 May 2013 / [ed] Lisa Jackson and John Andrews, Loughborough: Loughborough University, UK , 2013, s. 366-378Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
    Abstract [en]

    The main objective of a reliability study should always be to provide information as a basis for decisions, e.g. concept choice, design requirements, investment, choice of suppliers, design changes or guaranty claims. The choice of reliability method depends on the time allocated for the reliability study, the design stage, the problem at hand and the competence and resources available.

    During a reliability study the engineer focuses on providing a graphical means of evaluating the relationships between different parts of the system, gathering or assessing the reliability data for the components and interpreting the results of the analyses. Even though the commercial software tools available claim to provide answers to most reliability questions, choosing which method is best suited is not an easy task. Often several methods can be applied and none of them will fit the purpose perfectly.

    This paper presents a guideline for choosing the best suited reliability method in early design phases from two aspects: objective and system characteristics. The methods studied are the most common methods available in commercial software tools: Reliability Block Diagram (RBD), Fault Tree (FT), Event Tree (ET), Markov Analysis (MA) and Stochastic Petri Network (SPN). The guideline considers two aspects: the characteristics of the system studied and the scope of the analysis. The applicability of each of the five chosen methods is assessed for all possible combinations of system characteristics and objective. A study has been made at Saab Aeronautics to evaluate the practical use of the analysed methods and how this guideline can improve the selection of appropriate reliability methods in early design phases.

    Ort, förlag, år, upplaga, sidor
    Loughborough: Loughborough University, UK, 2013
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-94352 (URN)9781907382611 (ISBN)
    Konferens
    The 20th Advances in Risk and Reliability Technology Symposium, 21st – 23rd May 2013, Burleigh Court Conference Centre, Loughborough, Leicestershire, UK
    Tillgänglig från: 2013-06-25 Skapad: 2013-06-25 Senast uppdaterad: 2017-02-20Bibliografiskt granskad
    3. Cost optimization with focus on reliability and system safety
    Öppna denna publikation i ny flik eller fönster >>Cost optimization with focus on reliability and system safety
    2013 (Engelska)Ingår i: Safety, Reliability and Risk AnalysisBeyond the Horizon / [ed] R. D. J. M. Steenbergen , P. H. A. J. M. van Gelder , S. Miraglia and A. C. W. M. Ton. Vrouwenvelder, CRC Press, 2013, s. 2723-2730Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    When developing a safety critical system, there are many aspects that need to be balanced against each other in order to reach an optimal design such as safety requirements, reliability goal, performance specifications and budget constraints. In an early design stage, it is vital to be able to screen the design space for a set of promising design alternatives for further studies. This paper proposes an approach capable of investigating the trade-offs described above, combining the techniques for system safety and reliability analysis with optimization methods. Markov analysis is employed for modeling the system safety and reliability characteristics and a Genetic Algorithm is used for optimization. The proposed method is applied to the design of an electric supply system for an aircraft, involving selection of components from different suppliers. First a model is built for each objective, i.e. cost, safety, and reliability. The models are validated and optimization is performed. The obtained result is the selection of suppliers for each component in the system in order to achieve a balance between system safety, reliability, and other design objectives.

    Ort, förlag, år, upplaga, sidor
    CRC Press, 2013
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-94353 (URN)10.1201/b15938-413 (DOI)9781138001237 (ISBN)9781315815596 (ISBN)
    Konferens
    ESREL2013, 29 Sep-02 October, Amsterdam, Holland
    Tillgänglig från: 2013-06-25 Skapad: 2013-06-25 Senast uppdaterad: 2017-02-20Bibliografiskt granskad
    4. An Industrial Implementation of an Optimization Based Method for Balancing Safety, Reliability and Weight of Aircraft Systems
    Öppna denna publikation i ny flik eller fönster >>An Industrial Implementation of an Optimization Based Method for Balancing Safety, Reliability and Weight of Aircraft Systems
    Visa övriga...
    2017 (Engelska)Ingår i: Risk, Reliability and Safety: Innovating Theory and Practice: Proceedings of ESREL 2016 (Glasgow, Scotland, 25-29 September 2016) / [ed] Lesley Walls, Matthew Revie and Tim Bedford, CRC Press, 2017, s. 1707-1713Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The aim of this paper is to show how a method able of trade-offs such as system safety, reliability, weight and cost can be practically implemented in industry (SAAB Aeronautics). The scope is to facilitate the decision-making on the optimal design in early design phases. The method consists of several steps guiding the user to model each objective, verify and validate the models, perform optimization and finally visualize and select the results. Within the practical implementation of this method, several challenges are addressed and solved. For example, one challenge is to implement the trade-off method using the existing programs. Another challenge is the user friendliness of the implementation. In order to solve these challenges, the analysis is started and performed in Matlab. A Graphical User Interface guides the user to select the analysis to perform, budgets/requirements for each objective and parameters with influence on end-result. Data regarding the safety and reliability objectives, exported from Reliability Workbench program to Excel, is imported to Matlab, where the analysis is performed. The results are extracted into an Excel file, where the user can work further on visualization and selection. Two small examples are used to demonstrate this practical implementation of the trade-off method. Lessons learned are presented, strengths, limitations and development potential.

    Ort, förlag, år, upplaga, sidor
    CRC Press, 2017
    Nationell ämneskategori
    Datorsystem Inbäddad systemteknik Programvaruteknik
    Identifikatorer
    urn:nbn:se:liu:diva-134590 (URN)000414164700242 ()9781138029972 (ISBN)9781315374987 (ISBN)
    Konferens
    ESREL 2016, Glasgow, Scotland, 25-29 September 2016
    Anmärkning

    Funding agencies:The implementation presented in this paper is part of a research funded by Saab Aeronautics and the National Aviation Engineering Research Program (NFFP), jointly driven by the Swedish Armed Forces, the Swedish Defense Materiel Administration (FMV), and the Swedish Governmental Agency for Innovation Systems (VINNOVA).

    Tillgänglig från: 2017-02-20 Skapad: 2017-02-20 Senast uppdaterad: 2018-01-13Bibliografiskt granskad
    5. How to use an Optimization-based Method Capable of Balancing Safety, Reliability, and Weight in an Aircraft Design Process
    Öppna denna publikation i ny flik eller fönster >>How to use an Optimization-based Method Capable of Balancing Safety, Reliability, and Weight in an Aircraft Design Process
    2017 (Engelska)Ingår i: Nuclear engineering and technology : an international journal of the Korean Nuclear Society, ISSN 1738-5733, E-ISSN 2234-358X, Vol. 49, s. 404-410Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In order to help decision-makers in the early design phase to improve and make more cost-efficient system safety and reliability baselines of aircraft design concepts, a method (Multi-objective Optimization for Safety and Reliability Trade-off) that is able to handle trade-offs such as system safety, system reliability, and other characteristics, for instance weight and cost, is used. Multi-objective Optimization for Safety and Reliability Trade-off has been developed and implemented at SAAB Aeronautics. The aim of this paper is to demonstrate how the implemented method might work to aid the selection of optimal design alternatives. The method is a three-step method: step 1 involves the modelling of each considered target, step 2 is optimization, and step 3 is the visualization and selection of results (results processing). The analysis is performed within Architecture Design and Preliminary Design steps, according to the company’s Product Development Process. The lessons learned regarding the use of the implemented trade-off method in the three cases are presented. The results are a handful of solutions, a basis to aid in the selection of a design alternative. While the implementation of the trade-off method is performed for companies, there is nothing to prevent adapting this method, with minimal modifications, for use in other industrial applications.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2017
    Nyckelord
    Aircraft Design, Early Design Phases, MOSART, Safety, Reliability, Trade-off
    Nationell ämneskategori
    Produktionsteknik, arbetsvetenskap och ergonomi Inbäddad systemteknik Datavetenskap (datalogi) Datorsystem Tillförlitlighets- och kvalitetsteknik
    Identifikatorer
    urn:nbn:se:liu:diva-134591 (URN)10.1016/j.net.2017.01.006 (DOI)000401102000015 ()
    Anmärkning

    Funding agencies: MOSART - Saab Aeronautics and the National Aviation Engineering Research Program [NFFP6 2013-01223]; Swedish Armed Forces; Swedish Defense Materiel Administration; Swedish Governmental Agency for Innovation Systems

    Tillgänglig från: 2017-02-20 Skapad: 2017-02-20 Senast uppdaterad: 2018-01-13Bibliografiskt granskad
  • 179.
    Johansson, Cristina
    et al.
    Mendeley, Br€oderna Ugglasgatan, SE-582 54 Linköping, Sweden.
    Derelöv, Micael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Ölvander, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    How to use an Optimization-based Method Capable of Balancing Safety, Reliability, and Weight in an Aircraft Design Process2017Ingår i: Nuclear engineering and technology : an international journal of the Korean Nuclear Society, ISSN 1738-5733, E-ISSN 2234-358X, Vol. 49, s. 404-410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to help decision-makers in the early design phase to improve and make more cost-efficient system safety and reliability baselines of aircraft design concepts, a method (Multi-objective Optimization for Safety and Reliability Trade-off) that is able to handle trade-offs such as system safety, system reliability, and other characteristics, for instance weight and cost, is used. Multi-objective Optimization for Safety and Reliability Trade-off has been developed and implemented at SAAB Aeronautics. The aim of this paper is to demonstrate how the implemented method might work to aid the selection of optimal design alternatives. The method is a three-step method: step 1 involves the modelling of each considered target, step 2 is optimization, and step 3 is the visualization and selection of results (results processing). The analysis is performed within Architecture Design and Preliminary Design steps, according to the company’s Product Development Process. The lessons learned regarding the use of the implemented trade-off method in the three cases are presented. The results are a handful of solutions, a basis to aid in the selection of a design alternative. While the implementation of the trade-off method is performed for companies, there is nothing to prevent adapting this method, with minimal modifications, for use in other industrial applications.

  • 180.
    Johansson, Cristina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Tekniska fakulteten.
    Derelöv, Micael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Ölvander, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Bergstrom, B.
    SAAB Aeronaut, Linkoping, Sweden.
    Nilsson-Sunden, H.
    SAAB Aeronaut, Linkoping, Sweden.
    An industrial implementation of an optimization based method for balancing safety, reliability and weight of aircraft systems2017Ingår i: RISK, RELIABILITY AND SAFETY: INNOVATING THEORY AND PRACTICE, CRC PRESS-TAYLOR & FRANCIS GROUP , 2017, s. 1707-1713Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this paper is to show how a method able of trade-offs such as system safety, reliability, weight and cost can be practically implemented in industry (SAAB Aeronautics). The scope is to facilitate the decision-making on the optimal design in early design phases. The method consists of several steps guiding the user to model each objective, verify and validate the models, perform optimization and finally visualize and select the results. Within the practical implementation of this method, several challenges are addressed and solved. For example, one challenge is to implement the trade-off method using the existing programs. Another challenge is the user friendliness of the implementation. In order to solve these challenges, the analysis is started and performed in Matlab. A Graphical User Interface guides the user to select the analysis to perform, budgets/requirements for each objective and parameters with influence on end-result. Data regarding the safety and reliability objectives, exported from Reliability Workbench program to Excel, is imported to Matlab, where the analysis is performed. The results are extracted into an Excel file, where the user can work further on visualization and selection. Two small examples are used to demonstrate this practical implementation of the trade-off method. Lessons learned are presented, strengths, limitations and development potential.

  • 181.
    Johansson, Cristina
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Derelöv, Micael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Ölvander, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Bergström, B.
    SAAB Aeronautics, Linköping, Sweden.
    Nilsson-Sundén, H.
    SAAB Aeronautics, Linköping, Sweden.
    An Industrial Implementation of an Optimization Based Method for Balancing Safety, Reliability and Weight of Aircraft Systems2017Ingår i: Risk, Reliability and Safety: Innovating Theory and Practice: Proceedings of ESREL 2016 (Glasgow, Scotland, 25-29 September 2016) / [ed] Lesley Walls, Matthew Revie and Tim Bedford, CRC Press, 2017, s. 1707-1713Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this paper is to show how a method able of trade-offs such as system safety, reliability, weight and cost can be practically implemented in industry (SAAB Aeronautics). The scope is to facilitate the decision-making on the optimal design in early design phases. The method consists of several steps guiding the user to model each objective, verify and validate the models, perform optimization and finally visualize and select the results. Within the practical implementation of this method, several challenges are addressed and solved. For example, one challenge is to implement the trade-off method using the existing programs. Another challenge is the user friendliness of the implementation. In order to solve these challenges, the analysis is started and performed in Matlab. A Graphical User Interface guides the user to select the analysis to perform, budgets/requirements for each objective and parameters with influence on end-result. Data regarding the safety and reliability objectives, exported from Reliability Workbench program to Excel, is imported to Matlab, where the analysis is performed. The results are extracted into an Excel file, where the user can work further on visualization and selection. Two small examples are used to demonstrate this practical implementation of the trade-off method. Lessons learned are presented, strengths, limitations and development potential.

  • 182.
    Johansson, Fredrik
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Microscopic Simulation of Pedestrian Traffic2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    There has recently been a renewed interest in planning for pedestrian traffic, primarily in connection to public transport interchange stations, since these are important for public transport to constitute an attractive alternative to car usage. This thesis concerns microscopic simulation of pedestrian traffic, which is a promising tool for analyzing and predicting the traffic situation in a given pedestrian facility; particularly powerful when the traffic is congested. Important applications of microscopic simulation include comparison of possible infrastructure designs such as proposed interchange stations, and evaluations of various traffic management solutions, for example information systems.

    The purpose of this thesis is to advance the capabilities of pedestrian microsimulation toward a level at which it can be reliably applied for quantitative analysis by practitioners in the field. The work is based on an established microscopic model of pedestrian dynamics, the Social Force Model (sfm), and the advances are made in a number of different areas.

    To be able to evaluate and compare simulated traffic situations suitable performance measures are needed. A set of local performance measures are proposed that quantifies the local delay rate density and estimates the discomfort perceived by the pedestrians.

    The sfm is extended to include waiting pedestrians through the introduction of a waiting model, demonstrated to be stable and free from oscillations. The inclusion of waiting pedestrians in the model is critical for accurate modelling of public transport interchange stations, where large groups of waiting pedestrians may hinder passing pedestrians if the design of the station is poor.

    The relaxation time of the adaptation to the preferred velocity is an important parameter in force based models of pedestrian traffic since it affects several behaviors of the simulated pedestrians, two of which are linear acceleration and turning movements. A comparison of observations of accelerating pedestrians reported in the literature and new observations of turning pedestrians indicates that no value of the relaxation time can give model behavior consistent with both sets of observations. This indicates that modifications of the model is needed to accurately reproduce the observed behavior.

    An important input to simulations is the preferred speed of the simulated pedestrians. The common assumption that the preferred speed distribution at a location does not vary during the day is tested through observations of pedestrian traffic at Stockholm Central Station. The results demonstrate that the preferred speeds are lower in the afternoon than in the morning, implying that the preferred speed should be treated as a source of uncertainty when applying pedestrian microsimulation.

    Finally, a sensitivity analysis of a simulation of the lower hall of Stockholm Central Station is performed to find the most important sources of uncertainty in the model predictions, given the available data. The results indicate that the uncertainty related to calibration is the largest of the considered potential error sources.

    Delarbeten
    1. Local performance measures of pedestrian traffic
    Öppna denna publikation i ny flik eller fönster >>Local performance measures of pedestrian traffic
    2014 (Engelska)Ingår i: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 6, nr 1-2, s. 159-183Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Efficient interchange stations, where travelers are changing lines and/or travel modes, are essential for the functionality of the whole public transport system. By studying pedestrian movements, the level of service and effectiveness imposed by the design of the interchange station can be evaluated. We address the problem by microsimulation, where a social force model is used for the phenomenological description of pedestrian interactions. The contribution of this paper is the proposal of measures describing the density, delay, acceleration and discomfort for pedestrian flows. Simulation experiments are performed for the movements in two canonical pedestrian areas, a corridor and a corridor intersection. Clearly, each of the four measures gives a description for how pedestrians impede each other, and hence for the efficiency at the facility. There is, however, different information provided by each measure, and we conclude that they all are well-motivated for quantifying the level of service in a pedestrian flow. We also illustrate the outcome for a railway platform, with two trains arriving in parallel.

    Ort, förlag, år, upplaga, sidor
    Springer Berlin/Heidelberg, 2014
    Nyckelord
    Interchange stations, Microsimulation, Pedestrians, Social force model
    Nationell ämneskategori
    Transportteknik och logistik
    Identifikatorer
    urn:nbn:se:liu:diva-109045 (URN)10.1007/s12469-013-0081-9 (DOI)
    Tillgänglig från: 2014-08-04 Skapad: 2014-08-04 Senast uppdaterad: 2018-08-23Bibliografiskt granskad
    2. Waiting pedestrians in the social force model
    Öppna denna publikation i ny flik eller fönster >>Waiting pedestrians in the social force model
    2015 (Engelska)Ingår i: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 419, s. 95-107Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Microscopic simulation of pedestrian traffic is an important and increasingly popular method to evaluate the performance of existing or proposed infrastructure. The social force model is a common model in simulations, describing the dynamics of pedestrian crowds given the goals of the simulated pedestrians encoded as their preferred velocities. The main focus of the literature has so far been how to choose the preferred velocities to produce realistic dynamic route choices for pedestrians moving through congested infrastructure. However, limited attention has been given the problem of choosing the preferred velocity to produce other behaviors, such as waiting, commonly occurring at, e.g., public transport interchange stations. We hypothesize that: (1) the inclusion of waiting pedestrians in a simulated scenario will significantly affect the level of service for passing pedestrians, and (2) the details of the waiting model affect the predicted level of service, that is, it is important to choose an appropriate model of waiting. We show that the treatment of waiting pedestrians have a significant impact on simulations of pedestrian traffic. We do this by introducing a series of extensions to the social force model to produce waiting behavior, and provide predictions of the model extensions that highlight their differences. We also present a sensitivity analysis and provide sufficient criteria for stability. (C) 2014 Elsevier B.V. All rights reserved.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2015
    Nyckelord
    Social force model; Waiting pedestrians; Microscopic simulation
    Nationell ämneskategori
    Samhällsbyggnadsteknik
    Identifikatorer
    urn:nbn:se:liu:diva-113715 (URN)10.1016/j.physa.2014.10.003 (DOI)000347017300012 ()
    Anmärkning

    Funding Agencies|Swedish Transport Administration [TRV 2013/13329]

    Tillgänglig från: 2015-01-30 Skapad: 2015-01-29 Senast uppdaterad: 2018-08-23
    3. The Many Roles of the Relaxation time Parameter in Force based Models of Pedestrian Dynamics
    Öppna denna publikation i ny flik eller fönster >>The Many Roles of the Relaxation time Parameter in Force based Models of Pedestrian Dynamics
    2014 (Engelska)Ingår i: Transportation Research Procedia, Elsevier, 2014, Vol. 2, s. 300-308Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
    Abstract [en]

    In force based models of pedestrian traffic, the relaxation time, τ, is related to the time it takes a pedestrian to adapt its motion to its preferences. An example of this is linear acceleration, but τ is also connected to how the agent adjusts to spatial variations in its preferred velocity, and affects evasive maneuvers. These many roles of τ may be a problem when calibrating force based models.

    We compare linear acceleration, to new data on, and simulations of, turning movements. The results indicate that the models predict drifting of a magnitude that is not supported by the data.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2014
    Nyckelord
    pedestrian simulation; force based models; calibration; relaxation time; social force model
    Nationell ämneskategori
    Transportteknik och logistik
    Identifikatorer
    urn:nbn:se:liu:diva-119121 (URN)10.1016/j.trpro.2014.09.057 (DOI)
    Konferens
    The Conference on Pedestrian and Evacuation Dynamics 2014 (PED 2014)
    Tillgänglig från: 2015-06-09 Skapad: 2015-06-09 Senast uppdaterad: 2016-12-20
  • 183.
    Johansson, Jacob
    Linköpings universitet, Institutionen för datavetenskap.
    Implementation and evaluationof the ACE DTLS framework: Reducing the authentication workload of a constrained device2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    IoT-devices are becoming more advanced and powerful than ever, and the applicationpotential is increasing rapidly. It is starting to become normal to have IoT-devices takingover mundane jobs such as controlling the climate at home, or monitoring e.g the water us-age of a household. These devices are usually constrained to be as cheap and primitive asthe task allows. Most of the time, they are only used to send collected data which only re-quires a one way secure channel. However, in order to apply updates or manage the deviceremotely, the communication has to be secured both ways. There are multiple suggestionson how a two way secure channel can be established while still operating on a constraineddevice. Each security specializes in its own area e.g privacy, scalability, or simplicity. Thispaper will describe how to implement the ACE-DTLS framework and analyze the perfor-mance with respect to energy consumption and security. While ACE-DTLS is quite simpleto implement without having to understand the complex math of a key exchange, it comeswith the cost of a high overhead in order to establish a secure two way connection. It mightnot be the best suited framework for small amount of data transfers available.

  • 184.
    Johansson, Oscar
    Linköpings universitet, Institutionen för datavetenskap.
    Weight Estimation and Evaluation of User Suggestions in Mobile Browsing2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study investigates the suggestion system of a mobile browser. The goal of a suggestion system is to assist the user by presenting relevant suggestions in an ordered list. By weighting the different types of suggestions presented to the user, such as history, bookmarks etc., it is investigated how this affects the performance of the suggestion sys- tem. The performance is measured using the position, error and Mean Reciprocal Rank of the chosen suggestion as well as the number of written characters. It is also measured if the user chose to not use the suggestion system, by searching or entering the entire URL. The weights were estimated using a Genetic Algorithm. The evaluation was done by performing an A/B test, were the control group used an unweighted system and the test group used the weights estimated by the genetic algorithm. The results from the A/B test were statistically analyzed using BEST and Bootstrap. The results showed an improvement of position, number of written characters, MMR and the error. There was no change in how much the user used the suggestion system. The thesis concluded that there is a correlation between the position of the desired suggestion and when the user stops typing, and that weighting types is a way to improve said position. The thesis also concludes that there is a need for future work in regards to evaluation of the optimization algorithm and error measurement.

  • 185.
    Johnsson, Arvid
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Extending a framework for a play and learn game with drag and drop, a subgame and visual feedback2015Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report documents and describes the process of the extension of a JavaScript frameworkfor the math game Magical Island and implementation of one of its subgames. Moreover itdetails the implementation of visual feedback within this subgame based on literature aboutfeedback within games. The method details the implementation process one system at a time,starting with a study of the code and ending with the implementation of the visual feedback.The results show that a systematic approach where an understanding of the existing code isthe most important thing when extending and implementing new features in a framework.They also show that to properly design a system for visual feedback knowledge of theresearch within this field is needed.

  • 186.
    Jonsson Lindahl, Nils
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    Utveckling av system förkommunikation med chattbottar2017Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Chattbottar har den senaste tiden, genom snabbmeddelandetjänsternas stora tillväxt, blivitallt populärare. Chattbottar används idag till allt från automatisk kundtjänst tillnöjesinriktade ändamål. Numera finns flera olika ramverk för att skapa chattbottar med olikaegenskaper.Syftet med detta arbete var att undersöka hur chattbottar kan integreras i existerandesnabbmeddelandetjänster på ett underhållbart och flexibelt sätt.

    En prototyplösning förmeddelandetjänsten Briteback skapades med opensource-ramverken React, Node.js och Deepstream. Rapporten beskriver för- och nackdelar med den valda lösningen specielltavseende flexibilitet och underhåll.

  • 187.
    Jonsson, Simon
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Designing a Scheduler for Cloud-Based FPGAs2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The primary focus of this thesis has been to design a network packet scheduler for the 5G (fifth generation) network at Ericsson in Linköping, Sweden. Network packet scheduler manages in which sequences the packages in a network will be transmitted, and will put them in a queue accordingly. Depending on the requirement for the system different packet schedulers will work in different ways. The scheduler that is designed in this thesis has a timing wheel as its core. The packages will be placed in the timing wheel depending on its final transmission time and will be outputted accordingly. The algorithm will be implemented on an FPGA (Field Programmable gate arrays). The FPGA itself is located in a cloud environment. The platform in which the FPGA is located on is called "Amazon EC2 F1", this platform can be rented with a Linux instance which comes with everything that is necessary to develop a synthesized file for the FPGA. Part of the thesis will discuss the design of the algorithm and how it was customized for a hardware implementation and part of the thesis will describe using the instance environment for development.

  • 188.
    Jönsson, Oscar
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska högskolan.
    An explorative study of the technology transfer coach as a preliminary for the design of a computer aid2014Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The university technology transfer coach has an important role in supporting the commercialization of research results. This thesis has studied the technology transfer coach and their needs in the coaching process. The goal has been to investigate information needs of the technology transfer coach as a preliminary for the design of computer aids.Using a grounded theory approach, we interviewed 17 coaches working in the Swedish technology transfer environment. Extracted quotes from interviews were openly coded and categorized. The analysis show three main problem areas related to the information needs of the technology transfer coach; awareness, communication, and resources. Moreover, 20 features for future computer aids were extracted from the interview data and scenarios and personas where developed to exemplify the future use of computer aids.We conclude that there is a need for computer support in the coaching process. Such systems should aid the coach in; awareness, aiding the coach to focus on meetings; communication, aid the coach to transfer commercialisation knowledge; and resources, aid the coach in accessing and delivering of resources to the coachee. However, it is imperative that the computer aids do not interfere with the coach current process; and that the computer aid is not seen as the sole solution.

  • 189. Kalogiannidou, Evmorfia
    et al.
    Peters, Christopher E.
    Kungliga tekniska högskolan.
    Facial hair and trustworthiness in virtual faces: towards an evaluation study2015Ingår i: Proceedings of SIGRAD 2015: June 1st and 2nd, Stockholm, Sweden / [ed] Christopher E. Peters, Lars Kjelldahl, Stockholm: Svenska föreningen för grafisk databehandling , 2015, s. 59-60Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present a work-in-progress towards a perceptual study concerning male and female first impressions of male virtual faces as variations are made in terms of their facial hair (beard) length, colour and the camera viewing angle. Previous studies involving real human faces suggest that these types of variations may impact impressions of trustworthiness and related qualities, such as credibility. This research investigates similar issues, but in the domain of virtual characters, with a view to exploring issues of trustworthiness based on the appearance of virtual faces. This is of great significance to the design of interactive computational social systems.

  • 190.
    Kangas, Fredrik
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Wihlborg, Sebastian
    Linköpings universitet, Institutionen för datavetenskap.
    Design and implementation of a collaborative secure storage solution2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the modern enterprises it is common that support and maintenance of IT environments are outsourced to third parties. In this setting, unencrypted confidential data may pose a problem since administrators maintaining the outsourced system can access confidential information if stored unencrypted. This thesis work, performed at ELITS, presents a solution to this problem; a design of a collaborative storage system where all files at rest (i.e. stored on disk) and in transit remain encrypted is proposed.

    The design uses a hybrid encryption scheme to protect the encryption keys used. The keys can safely be stored in a centralized database as well as sent to the clients without risk of unauthorized parties gaining access to the stored data. The design was also implemented as a proof of concept in order to establish that it was possible to realize.

  • 191.
    Kanza, Grace
    et al.
    University of Bergen, Norway.
    Babic, Ankica
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan. Univeristy of Bergen, Norway.
    Agile Development for Smart User Interfaces to Cancer Registries2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper studies different user interfaces developed for visualizing data mined from cancer registries. The motivation behind this research is a need to create more flexible and smart, easy to use interfaces that will assist users in utilizing and exploring clinical information. The design process combined Parallel and Iterative design process models together with Personal Kanban for managing the development process. The developed prototype provides users with a choice of several data visualization possibilities, depending on the user’s tasks and goals. A preliminary user interface was evaluated resulting in recommendations for further development. Heuristic evaluation with potential experts had scores on all the high scores on all the design dimensions: H1=visibility of system status; H2=match between the system and the real world; H3=user control and freedom; H4=consistency and standards; H5=error prevention; H6=recognition rather than recall; H7=flexibility and efficiency of use; H8=aesthetic and minimalist design; H9=help users recognize, diagnose, and recover from errors; and H10=help and documentation.

  • 192.
    Karlsson, Andréas
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Design of Energy-Efficient High-Performance ASIP-DSP Platforms2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    In the last ten years, limited clock frequency scaling and increasing power density has shifted IC design focus towards parallelism, heterogeneity and energy efficiency. Improving energy efficiency is by no means simple and it calls for a reevaluation of old design choices in processor architecture, and perhaps more importantly, development of new programming methodologies that exploit the features of modern architectures.

    This thesis discusses the design of energy-efficient digital signal processors with application-specific instructions sets, so-called ASIP-DSPs, and their programming tools. Target applications for such processors include, but are not limited to, communications, multimedia, image processing, intelligent vision and radar. These applications are often implemented by a limited set of kernel algorithms, whose performance and efficiency are critical to the application's success. At the same time, the extreme non-recurring engineering cost of system-on-chip designs means that product life-time must be kept as long as possible. Neither general-purpose processors nor non-programmable ASICs can meet both the flexibility and efficiency requirements, and ASIPs may instead be the best trade-off between all the conflicting goals.

    Traditional superscalar- and VLIW processor design focus has been to improve the throughput of fine-grained instructions, which results in high flexibility, but also high energy consumption. SIMD architectures, on the other hand, are often restricted by inefficient data access. The result is architectures which spend more energy and/or time on supporting operations rather than actual computing.

    This thesis defines the performance limit of an architecture with an N-way parallel datapath as consuming 2N elements of compute data per clock cycle. To approach this performance, this work proposes coarse-grained higher-order functional (HOF) instructions, which encode the most  frequently executed compute-, data access- and control sequences into single many-cycle instructions, to reduce the overheads of instruction delivery, while at the same time maintaining orthogonality. The work further investigates opportunities for operation fusion to improve computing performance, and proposes a flexible memory subsystem for conflict-free parallel memory access with permutation and lookup-table-based addressing, to ensure that high computing throughput can be sustained even in the presence of irregular data access patterns. These concepts are extensively studied by implementing a large kernel algorithm library with typical DSP kernels, to prove their effectiveness and adequacy. Compared to contemporary VLIW DSP solutions, our solution can practically eliminate instruction fetching energy in many scenarios, significantly reduce control path switching, simplify the implementation of kernels and reduce code size, sometimes by as much as 30 times.

    The techniques proposed in this thesis have been implemented in the DSP platform ePUMA (embedded Parallel DSP processor with Unique Memory Access), a configurable control-compute heterogeneous platform with distributed memory, optimized for low-power predictable DSP computing. Hardware evaluation has been done with FPGA prototypes. In addition, several VLSI layouts have been created for energy and area estimations. This includes smaller designs, as well as a large design with 73 cores, capable of 1280 integer GOPS or 256 GFLOPS at 500MHz and which measures 45mm2 in 28nm FD-SOI technology.

    In addition to the hardware design, this thesis also discusses parallel programming flow for distributed memory architectures and ePUMA application implementation. A DSP kernel programming language and its compiler is presented. This effectively demonstrates how kernels written in a high-level language can be translated into HOF instructions for very high processing efficiency.

  • 193.
    Karlsson, Anna
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Device Sensor Fingerprinting: Mobile Device Sensor Fingerprinting With A Biometric Approach2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The number of connected devices connected to the Internet is growing rapidly. When talking about devices it also covers the ones not having any contact with humans. This type of devices are the ones that are expected to increase the most. That is why the field of device fingerprinting is an area that requires further investigation. This thesis measures and evaluates the accelerometer, camera and gyroscope sensor of a mobile device to the use as device fingerprinting. The method used is based on previous research in sensor identification together with methods used for designing a biometric system. The combination with long-proven methods in the biometric area with new research of sensor identification is a new approach of looking at device fingerprinting.

  • 194.
    Karlsson, Daniel
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten.
    Nyström, Mikael
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten.
    Kron, Bengt
    Region Västra Götaland.
    An integrated Expression Repository EHR system2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Introduction: The aim of this work is to develop and test a system for storing and querying pre- and post-coordinated SNOMED CT expressions in an Electronic Health Record (EHR) system. SNOMED CT is here used as a reference terminology and to allow abstraction of EHR data for transfer to quality databases.

    Background: Enumerating all combinations of SNOMED CT concepts is not possible due to combinatorial explosion. E.g. pain may be qualified by severity (7 severities), pain character (152), body site (25888 sites), course (31) etc. giving a total of some 800 million possible, although not always sensible, different ways to express pain.

    For SNOMED CT to be useful, terminology services need to be integrated with the other parts of the information infrastructure, e.g. EHRs. As the boundary between terminology and information model representation may vary among use cases, care should be taken in implementing such integrations.

    Results: A system is developed to support the management of post-coordinated SNOMED CT expressions. This expression repository allows subsumption testing of pre- and post-coordinated expressions using a full view, i.e. historical views are possible. A transitive closure of the Is a-relation is updated continuously with new post-coordinated expressions stored in the repository. The repository is also integrated with an openEHR-based EHR system including archetype querying possibilities. The integrated system allows querying of terminology-bound archetype instances using pre- and post-coordinated SNOMED CT expressions.

  • 195.
    Karlsson, Eric
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    The evolution and erosion of a service-oriented architecture in enterprise software: A study of a service-oriented architecture and its transition to a microservice architecture2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis project, a company’s continuously evolved service-oriented software architecture was studied for signs of architectural erosion. The architecture has been continuously developed over some time and the company have experienced a reduction in architectural quality and felt that it no longer fulfilled its design goals and therefore decided to start working on a replacement architecture based on the microservice archi-tectural style. This thesis project therefore aimed to study how the current architectures quality have changed during its evolution, find the causes of these changes in quality, andestimate how the planned microservice migration will effect these changes in quality. This study was performed in three steps. First, a suite of suitable quality metrics where gathered based on the stated architectural design goals and what information can be ex-tracted from the history of the implemented architecture. A tool was developed to model the architecture and to gather the quality metrics from the current architecture and how ithas changed over one year’s worth of development and evolution. Secondly, the causes ofthese changes in architectural quality was investigated through developer interviews with a wide range of developers that had worked on the architecture and the web application that it provides the structure for. The interviews focused on the topics of architectural knowledge, what consideration is taken to its design during component development, maintenance of existing components and architecture, as well as questions regardingspecific components and anomalies. Thirdly and finally, the migration to a microserviceand its effects on the quality of the current architecture is estimated through performing microservice reengineering on the model used to evaluate the current architecture. The tools developed during this thesis allowed for an analysis of the architecture didshow an increase in consistency violations, structural problems and level the of coupling have substantially increased over the version history that the model tracked. It was discov-ered by the developer interviews that some of the causes of this erosion was due to among other reasons an abandonment of some architectural deign decisions, lack of architectural knowledge on certain topics, and none-optimal development conditions and priorities. The microservice reengineering showed how the migration could be used to improve themeasured quality metrics and that a migration alongside some other architectural erosionprevention and repair methods could create an architecture that are more modular and erosion tolerant.

  • 196.
    Karlsson, Linus
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska högskolan.
    RESTful Cloud Server2013Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report is about the development of a cloud service server that will be used to store user information. The clouds purpose is to store information about the user and the devices he or she uses. The cloud has web services that enable users to retrieve and store the data on the server. It isalso responsible for user administration and security of the data. A web client is also developed in parallel with the cloud. The web client uses the cloud’s  web services to show and modify data for the user.

  • 197.
    Karlsson, Marcus
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Aspects of Massive MIMO2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Det ställs hårda krav på nästa generations cellulära trådlösa system: att simultant öka datatakten på kommunikationen och dess tillförlitlighet utan att konsumera mer resurser, oavsett om det spektrum eller energi. Massiv mimo (eng: Multiple-Input Multiple-Output) har visat, både i teori och praktik, att tekniken är redo att tackla utmaningen. Massiv mimo kan betjäna många användare samtidigt, med god service, utan att öka den utstrålade effekten jämfört med nuvarande system. Massiv mimo, där basstationerna är utrustade med hundratals antenner, skiljer sig från dagens system vilket gör att många nya problem dyker upp och nya infallsvinklar på befintliga problem krävs. Denna avhandling analyserar två problem, och hur dessa förändras i ett massiv mimo sammanhang: säkerhet för fysiska lagret och överföring av systeminformation. Särskiljt visas att en störsändare med ett stort antal antenner kan överträffa en traditionell störsändare med en enda antenn. Antalet antenner ger störsändaren möjlighet att hitta strukturer i signaler och utnyttja detta för att förbättra störningens effekt. Det stora antalet antenner visar sig vara användbart även för överföring av systeminformation, där basstationen inte har någon kanalkännedom. Antennerna ger möjligheten att tillämpa spatial kodning (eng: space-time block coding). Vi visar hur överföringen utan kanalkännedom kan göras i massiv mimo genom att använda en fix förkodningsmatris för att reducera antalet pilotsymboler. Samtidigt kodar vi spatiellt över antennerna för att tillhandahålla spatiell diversitet.

  • 198.
    Karlsson, Rikard
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    Utvärdering av kvalitetsregistret och processtödssystemet Carath2017Självständigt arbete på grundnivå (kandidatexamen), 12 poäng / 18 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Studien genomförs i syfte att utvärdera hur arbetsflödet i sjukvårdssystemet Carath är anpassat efter rutiner hos användarna på de thoraxkliniker som äger systemet och där det används. Tre arbetsplatsundersökningar och elva stycken intervjuer genomfördes med sjukhuspersonal på olika kliniker i Sverige med metoden kontextuell design.

    Resultaten från studien visar att Carath är anpassat efter patientflödet på klinikerna men i mindre grad anpassat efter användares arbetsrutiner och roller. Studien visar även på att systemet saknar inbyggd hantering för återkoppling och kontroller av registrerad data. Dessa funktioner utförs istället manuellt utanför systemet. Samtliga av de saknade funktionerna bekräftas även genom SEIPS-modellen som funktioner som är rekommenderbara inom ett sjukvårdssystem. Sammantaget visar resultatet från kontextuella intervjuer med kommentarer från personal, genererade sekvensmodeller över arbetsflöden och utvärderingar mot SEIPS-modellen att Carath skulle behöva balanseras mellan patientflöde och personalens arbetsflöde. Funktioner för återkoppling och kontroll skulle integreras i systemet. Framtida arbete innefattar en undersökning kring integration mot andra system inom sjukvården.

  • 199.
    Karlsson Schmidt, Carl
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Rhino and Human Detection in Overlapping RGB and LWIR Images2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Tjuvjakten av noshörningar har ökat drastiskt de senaste åren och parkvakternastår ofta handfallna mot militariserade tjuvjägare. Linköpings Universitet arbetarpå flera projekt som på olika sätt ska vara ett stöd för parkvakterna i deras arbete.Examensarbetet genomfördes på CybAero AB som jobbar med att bygga fjärrstyrdahelikoptrar, så kallade RPAS (Remotely Piloted Aircraft System). Med derassystem kan man bära högkvalitativa kameror och ha stor räckvidd så hela parkenkan övervakas.Det här examensarbetet syftar på att undersöka olika metoder för att från luftburnakameror kunna ge information om vad som pågår i parken. System bygger påatt man har två kameror, en vanlig färgkamera och en värmekamera. Värmekamerananvänds för att hitta intressanta objekt som sedan plockas ut ur färgbilden.Objektet klassificeras sedan som antingen noshörningar, människor eller annat.Flertalet metoder har utvärderas utefter deras förmåga att klassificera objektenkorrekt.Det visade sig att man kan få väldigt bra resultat när man klassificerar endastpå värmebilden vilket ger systemet möjlighet att operera även när det är skymningeller mörkt ute. Det är en väldigt viktig del då de flesta djuren skjuts vidantingen gryning eller skymning. Som slutsats i rapporten presenteras ett förslagpå system som kan köras på lågpresterande hårdvara för att kunna köras direkt iluften.

  • 200.
    Kastegård, Sandra
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Automated testing of a web-based user interface2015Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Testing is a vital part of software development and test automation is an increasingly common practise. Performing automated testing on web-based applications is more complicated than desktop applications, which is particularly clear when it comes to testing a web based user interface as they are becoming more complex and dynamic. Depending on the goals and needed complexity of the testing, a variety of different frameworks/tools are available to help implementing it.

    This thesis investigates how automated testing of a web-based user interface can be implemented. Testing methods and a selection of relevant testing frameworks/tools are presented and evaluated based on given requirements. Out of the selected frameworks/tools, the Selenium WebDriver framework is chosen and used for implementation. The implementation results in automated test cases for regression testing of the functionality of a user interface created by Infor AB.

1234567 151 - 200 av 429
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf