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  • 251. Abrahamsson, Emil
    et al.
    Forni, Timothy
    Skeppstedt, Maria
    Kvist, Maria
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Medical text simplification using synonym replacement: adapting assessment of word difficulty to a compounding language2014Ingår i: Proceedings of the 3rdWorkshop on Predicting andImproving Text Readability for Target Reader Populations(PITR) / [ed] Sandra Williams, Stroudsburg: Association for Computational Linguistics , 2014, 57-65 s.Konferensbidrag (Refereegranskat)
  • 252. Abrahamsson, H
    et al.
    Hagsand, Olof
    KTH, Skolan för datavetenskap och kommunikation (CSC), Teoretisk datalogi, TCS.
    Marsh, Ian
    TCP over high speed variable capacity links: A simulation study for bandwidth allocation2002Konferensbidrag (Refereegranskat)
    Abstract [en]

     New optical network technologies provide opportunities for fast, controllable bandwidth management. These technologies can now explicitly provide resources to data paths, creating demand driven bandwidth reservation across networks where an applications bandwidth needs can be meet almost exactly. Dynamic synchronous Transfer Mode (DTM) is a gigabit network technology that provides channels with dynamically adjustable capacity. TCP is a reliable end-to-end transport protocol that adapts its rate to the available capacity. Both TCP and the DTM bandwidth can react to changes in the network load, creating a complex system with inter-dependent feedback mechanisms. The contribution of this work is an assessment of a bandwidth allocation scheme for TCP flows on variable capacity technologies. We have created a simulation environment using ns-2 and our results indicate that the allocation of bandwidth maximises TCP throughput for most flows, thus saving valuable capacity when compared to a scheme such as link over-provisioning. We highlight one situation where the allocation scheme might have some deficiencies against the static reservation of resources, and describe its causes. This type of situation warrants further investigation to understand how the algorithm can be modified to achieve performance similar to that of the fixed bandwidth case.

  • 253.
    Abrahamsson, Henrik
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Internet Traffic Management2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 254.
    Abrahamsson, Henrik
    RISE., Swedish ICT, SICS. School of Innovation, Design and Engineering.
    Network overload avoidance by traffic engineering and content caching2012Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The Internet traffic volume continues to grow at a great rate, now driven by video and TV distribution. For network operators it is important to avoid congestion in the network, and to meet service level agreements with their customers. This thesis presents work on two methods operators can use to reduce links loads in their networks: traffic engineering and content caching. This thesis studies access patterns for TV and video and the potential for caching. The investigation is done both using simulation and by analysis of logs from a large TV-on-Demand system over four months. The results show that there is a small set of programs that account for a large fraction of the requests and that a comparatively small local cache can be used to significantly reduce the peak link loads during prime time. The investigation also demonstrates how the popularity of programs changes over time and shows that the access pattern in a TV-on-Demand system very much depends on the content type. For traffic engineering the objective is to avoid congestion in the network and to make better use of available resources by adapting the routing to the current traffic situation. The main challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands. This thesis proposes L-balanced routings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level L. L-balanced routing gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic. We present an L-balanced routing algorithm and a heuristic search method for finding L-balanced weight settings for the legacy routing protocols OSPF and IS-IS. We show that the search and the resulting weight settings work well in real network scenarios.

  • 255.
    Abrahamsson, Henrik
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Network overload avoidance by traffic engineering and content caching2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The Internet traffic volume continues to grow at a great rate, now driven by video and TV distribution. For network operators it is important to avoid congestion in the network, and to meet service level agreements with their customers.  This thesis presents work on two methods operators can use to reduce links loads in their networks: traffic engineering and content caching.

    This thesis studies access patterns for TV and video and the potential for caching.  The investigation is done both using simulation and by analysis of logs from a large TV-on-Demand system over four months.

    The results show that there is a small set of programs that account for a large fraction of the requests and that a comparatively small local cache can be used to significantly reduce the peak link loads during prime time. The investigation also demonstrates how the popularity of programs changes over time and shows that the access pattern in a TV-on-Demand system very much depends on the content type.

    For traffic engineering the objective is to avoid congestion in the network and to make better use of available resources by adapting the routing to the current traffic situation. The main challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands.

    This thesis proposes L-balanced routings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level L. L-balanced routing gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic.  We present an L-balanced routing algorithm and a heuristic search method for finding L-balanced weight settings for the legacy routing protocols OSPF and IS-IS. We show that the search and the resulting weight settings work well in real network scenarios.

  • 256.
    Abrahamsson, Henrik
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Traffic measurement and analysis1999Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Measurement and analysis of real traffic is important to gain knowledge about the characteristics of the traffic. Without measurement, it is impossible to build realistic traffic models. It is recent that data traffic was found to have self-similar properties. In this thesis work traffic captured on the network at SICS and on the Supernet, is shown to have this fractal-like behaviour. The traffic is also examined with respect to which protocols and packet sizes are present and in what proportions. In the SICS trace most packets are small, TCP is shown to be the predominant transport protocol and NNTP the most common application. In contrast to this, large UDP packets sent between not well-known ports dominates the Supernet traffic. Finally, characteristics of the client side of the WWW traffic are examined more closely. In order to extract useful information from the packet trace, web browsers use of TCP and HTTP is investigated including new features in HTTP/1.1 such as persistent connections and pipelining. Empirical probability distributions are derived describing session lengths, time between user clicks and the amount of data transferred due to a single user click. These probability distributions make up a simple model of WWW-sessions.

  • 257.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ahlgren, Bengt
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Temporal Characteristics of Large IP Traffic Flows2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Several studies of Internet traffic have shown that it is a small percentage of the flows that dominate the traffic. This is often referred to as the mice and elephants phenomenon. It has been proposed that this might be one of very few invariants of Internet traffic and that this property could somehow be used for traffic engineering purposes. The idea being that one in a scalable way could control a major part of the traffic by only keeping track of a small number of flows. But for this the large flows must also be stable in the meaning that they should be among the largest flows during long periods of time. In this work we analyse packet traces of Internet traffic and study the temporal characteristics of large aggregated traffic flows defined by destination address prefixes.

  • 258.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ahlgren, Bengt
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Using empirical distributions to characterize web client traffic and to generate synthetic traffic2000Konferensbidrag (Refereegranskat)
  • 259.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ahlgren, Bengt
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Alonso, Juan
    RISE - Research Institutes of Sweden, IKT, SICS.
    Andersson, Anders
    RISE - Research Institutes of Sweden, IKT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    A Multi Path Routing Algorithm for IP Networks Based on Flow Optimisation.2002Konferensbidrag (Refereegranskat)
  • 260.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ahlgren, Bengt
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Alonso, Juan
    RISE - Research Institutes of Sweden, IKT, SICS.
    Andersson, Anders
    RISE - Research Institutes of Sweden, IKT, SICS.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    From QoS provisioning to QoS charging2002Ingår i: Proceedings of the Second International Workshop on Internet Charging and QoS Technologies, ICQT 2002, 2002, 1, Vol. Lectures Notes in Computer Science (LNCS) no. 2511, 135-144 s.Konferensbidrag (Refereegranskat)
  • 261.
    Abrahamsson, Henrik
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ahlgren, Bengt
    RISE - Research Institutes of Sweden, ICT, SICS.
    Lindvall, Patrik
    TeliaSonera, Sweden.
    Nieminen, Johanna
    TeliaSonera, Sweden.
    Tholin, Per
    TeliaSonera, Sweden.
    Traffic Characteristics on 1Gbit/s Access Aggregation Links2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Large network operators have thousands or tens of thousands of access aggregation links that they need to manage and dimension properly. Measuring and understanding the traffic characteristics on these type of links are therefore essential. What do the traffic intensity characteristics look like on different timescales from days down to milliseconds? How do the characteristics differ if we compare links with the same capacity but with different type of clients and access technologies? How do the traffic characteristics differ from that on core network links? These are the type of questions we set out to investigate in this paper. We present the results of packet level measurements on three different 1Gbit/s aggregation links in an operational IP network. We see large differences in traffic characteristics between the three links. We observe highly skewed link load probability densities on timescales relevant for buffering (i.e. 10-milliseconds). We demonstrate the existence of large traffic spikes on short timescales (10-100ms) and show their impact on link delay. We also found that these traffic bursts often are caused by only one or a few IP flows.

  • 262.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ahlgren, Bengt
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Tholin, Per
    Delay and Traffic Intensity Monitoring in an Operational IP Network2015Konferensbidrag (Refereegranskat)
  • 263.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Caching for IPTV distribution with time-shift2013Konferensbidrag (Refereegranskat)
  • 264.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Caching for IPTV distribution with time-shift2013Ingår i: 2013 International Conference on Computing, Networking and Communications, ICNC 2013, IEEE , 2013, 916-921 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today video and TV distribution dominate Internet traffic and the increasing demand for high-bandwidth multimedia services puts pressure on Internet service providers. In this paper we simulate TV distribution with time-shift and investigate the effect of introducing a local cache close to the viewers. We study what impact TV program popularity, program set size, cache replacement policy and other factors have on the caching efficiency. The simulation results show that introducing a local cache close to the viewers significantly reduces the network load from TV-on-Demand services. By caching 4% of the program volume we can decrease the peak load during prime time by almost 50%. We also show that the TV program type and how program popularity changes over time can have a big influence on cache hit ratios and the resulting link loads

  • 265.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Robust Traffic Engineering using L-balanced Weight-Settings in OSPF/IS-IS2009Konferensbidrag (Refereegranskat)
  • 266.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Simulation of IPTV caching strategies2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    IPTV, where television is distributed over the Internet Protocol in a single operator network, has become popular and widespread. Many telecom and broadband companies have become TV providers and distribute TV channels using multicast over their backbone networks. IPTV also means an evolution to time-shifted television where viewers now often can choose to watch the programs at any time. However, distributing individual TV streams to each viewer requires a lot of bandwidth and is a big challenge for TV operators. In this paper we present an empirical IPTV workload model, simulate IPTV distribution with time-shift, and show that local caching can limit the bandwidth requirements significantly.

  • 267.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Simulation of IPTV caching strategies2010Ingår i: Proceedings of the 2010 International Symposium on Performance Evaluation of Computer and Telecommunication Systems, 2010, 187-193 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    IPTV, where television is distributed over the Internet Protocol in a single operator network, has become popular and widespread. Many telecom and broadband companies have become TV providers and distribute TV channels using multicast over their backbone networks. IPTV also means an evolution to time-shifted television where viewers now often can choose to watch the programs at any time. However, distributing individual TV streams to each viewer requires a lot of bandwidth and is a big challenge for TV operators. In this paper we present an empirical IPTV workload model, simulate IPTV distribution with time-shift, and show that local caching can limit the bandwidth requirements significantly.

  • 268.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Gunnar, Anders
    RISE., Swedish ICT, SICS.
    Traffic engineering in ambient networks: challenges and approaches2004Ingår i: Swedish National Computer Networking Workshop, 2004, 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    The focus of this paper is on traffic engineering in ambient networks. We describe and categorize different alternatives for making the routing more adaptive to the current traffic situation and discuss the challenges that ambient networks pose on traffic engineering methods. One of the main objectives of traffic engineering is to avoid congestion by controlling and optimising the routing function, or in short, to put the traffic where the capacity is. The main challenge for traffic engineering in ambient networks is to cope with the dynamics of both topology and traffic demands. Mechanisms are needed that can handle traffic load dynamics in scenarios with sudden changes in traffic demand and dynamically distribute traffic to benefit from available resources. Trade-offs between optimality, stability and signaling overhead that are important for traffic engineering methods in the fixed Internet becomes even more critical in a dynamic ambient environment.

  • 269.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Hagsand, Olof
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    TCP over High Speed Variable Capacity Links: A Simulation Study for Bandwidth Allocation2002Konferensbidrag (Refereegranskat)
  • 270.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    A case for resource management in IPTV distribution2008Konferensbidrag (Refereegranskat)
  • 271.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Kreuger, Per
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Resource Management for IPTV distribution2009Ingår i: ERCIM News, Vol. 77Artikel i tidskrift (Övrigt vetenskapligt)
  • 272.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    DTMsim - DTM channel simulation in ns2001Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Dynamic Transfer Mode (DTM) is a ring based MAN technology that provides a channel abstraction with a dynamically adjustable capacity. TCP is a reliable end to end transport protocol capable of adjusting its rate. The primary goal of this work is investigate the coupling of dynamically allocating bandwidth to TCP flows with the affect this has on the congestion control mechanism of TCP. In particular we wanted to find scenerios where this scheme does not work, where either all the link capacity is allocated to TCP or congestion collapse occurs and no capacity is allocated to TCP. We have created a simulation environment using ns-2 to investigate TCP over networks which have a variable capacity link. We begin with a single TCP Tahoe flow over a fixed bandwidth link and progressively add more complexity to understand the behaviour of dynamically adjusting link capacity to TCP and vice versa.

  • 273.
    Abrahamsson, Henrik
    et al.
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Nordmark, Mattias
    Program Popularity and Viewer Behaviour in a Large TV-on-Demand System2012Konferensbidrag (Refereegranskat)
  • 274.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Nordmark, Mattias
    TeliaSonera AB, Stockholm, Sweden .
    Program popularity and viewer behaviour in a large TV-on-Demand system2012Ingår i: IMC '12 Proceedings of the 2012 ACM conference on Internet measurement conference, New York: ACM , 2012, 199-210 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today increasingly large volumes of TV and video are distributed over IP-networks and over the Internet. It is therefore essential for traffic and cache management to understand TV program popularity and access patterns in real networks.

    In this paper we study access patterns in a large TV-on-Demand system over four months. We study user behaviour and program popularity and its impact on caching. The demand varies a lot in daily and weekly cycles. There are large peaks in demand, especially on Friday and Saturday evenings, that need to be handled.

    We see that the cacheability, the share of requests that are not first-time requests, is very high. Furthermore, there is a small set of programs that account for a large fraction of the requests. We also find that the share of requests for the top most popular programs grows during prime time, and the change rate among them decreases. This is important for caching. The cache hit ratio increases during prime time when the demand is the highest, and aching makes the biggest difference when it matters most.

    We also study the popularity (in terms of number of requests and rank) of individual programs and how that changes over time. Also, we see that the type of programs offered determines what the access pattern will look like.

  • 275.
    Abrahamsson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Nätverksoptimering: Bästa möjliga tillgänglighet till lägsta möjliga länkkostnad2012Självständigt arbete på grundnivå (högskoleexamen), 5 poäng / 7,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna uppsats behandlar nätverksoptimering, med fokus på att få fram den bästa möjliga tillgängligheten till lägsta möjliga kostnad, i form av länkar. I studien tas en teoretiskt grundad hypotes om en metod fram för att lösa detta problemet. Samt genomförs ett test där metoden appliceras på ett studieobjekt för att bekräfta huruvida metoden verkar fungerar eller inte.

    Resultatet blir slutligen en metod som genom att analysera tillgängligheten, länk redundansen samt beräkna antal oberoende vägar mellan noder i ett nätverk. Kan genom att jämföra resultat från före en förändring med resultat från efter en förändring lyfta fram de förändringar som medför förbättringar. Varpå ett nätverk kan optimeras till bästa möjliga tillgänglighet till lägsta möjliga kostnad, i form av länkar.

  • 276.
    Abrahamsson, Johan
    et al.
    Umeå universitet, Samhällsvetenskaplig fakultet, Informatik.
    Sjöberg, Robin
    Umeå universitet, Samhällsvetenskaplig fakultet, Informatik.
    E-tjänstutveckling ur ett medborgarperspektiv: Att skapa beslutsunderlag baserat på medborgarärendens lämplighet för olika kommunikationskanaler2009Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Citizens’ interaction with governments is an area with unique implications for channel management. Governments need to take the citizens perspective into further consideration in order to be successful in delivering high-quality e-services. This paper aims to determine if a categorization of citizen-initiated contacts from a citizen-centric perspective can be a valuable basis for decisions regarding e-service development. The study consisted of three steps. The first step was an examination of the existing related literature, which resulted in the uncovering of the most important aspects of citizens channel choice. The second step consisted of an elaboration of a classification based on perceived task characteristics and a subsequent matching of the categories to desirable channel characteristics. The third and final step consisted of an application of the proposed categorization on a content management system containing all citizen-initiated contacts in a Swedish municipality. The application indicated that the proposed categorization could possibly be used to guide investments in e-services towards a channel-appropriate direction.

  • 277.
    Abrahamsson, Jonas
    Högskolan i Skövde, Institutionen för datavetenskap.
    Metoder vid implementation av affärssystem: en studie om anpassning2001Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats
    Abstract [sv]

    Dagens företag är i stort behov av information. Företag som har många avdelningar behöver möjligheter för att enkelt och smidigt kunna samordna information för hela företaget. Affärssystem erbjuder denna möjlighet genom en modulbaserad konstruktion som integrerar ett företags samtliga avdelningar i ett enda system. Problem kan dock uppstå då ett valt affärssystem inte passar företagets verksamhet. En kompromiss mellan system och verksamhet måste då försöka uppnås.

    Ett affärssystem implementeras ofta i samband med en metod, vilken ger detaljerade beskrivningar för hur implementeringen ska gå till. På vilka grunder väljer företagen att arbeta efter en specifik metod då system och verksamhet behöver anpassas till varandra?

    Detta arbete bygger på en undersökning som har utförts genom en survey där fem företag har medverkat. Resultatet av undersökningen visar ett antal metoder samt presenterar orsaker till varför dessa metoder används.

  • 278.
    Abrahamsson, Lars
    Linköpings universitet, Institutionen för systemteknik.
    A portal based system for indoor environs2006Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    The purpose of this thesis is to document the development of the graphics part of an extremely pluggable game engine/lab environment for a course in advanced game programming. This thesis is one out of five, and concerns indoor, realtime computer 3D graphics. It covers state-of-the-art techniques such as GLSL - the OpenGL Shading Language - and more well known techniques such as portal based rendering.

  • 279.
    Abrahamsson, Lisa
    et al.
    Blekinge Tekniska Högskola.
    Lagerqvist, Amelie
    Blekinge Tekniska Högskola.
    Att formas och att formge: Normkritisk mönsterformgivning2015Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Vårt samhälle är uppbyggt av normer som säger hur vi bör se ut, bete oss och leva. Många av dessa normer fokuserar på hur en person som man eller kvinna bör vara i förhållande till sitt kön. Könsnormer återspeglas i design och det vi formger, i produkter, möbler och byggnader. Genom ett genusspecificerat normkritiskt förhållningssätt undersöker vi hur könsnormer uppkommer i design och hur vi som formgivare kan designa normkritiskt. Med mönsterdesign som undersökande metod vill vi belysa och undersöka hur könsnormer upprepas i det vi formger, precis som ett mönster definieras av linjer och former som upprepas eller upplevs att göra det.

    Under vår undersökning framkommer det att mönster kan bidra till diskussion och ställningstagande som fungerar i flera forum. Vi undersöker hur unisex och manligt och kvinnligt kan gestaltas i mönster och hur normkritik fungerar som förhållningssätt i en designprocess.

  • 280. Abrahamsson, M.
    et al.
    Sundberg, Johan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Subglottal pressure variation in actors’ stage speech2007Ingår i: Voice and Gender Journal for the Voice and Speech Trainers Association / [ed] Rees, M., VASTA Publishing , 2007, 343-347 s.Kapitel i bok, del av antologi (Refereegranskat)
  • 281.
    Abrahamsson, Marcus
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A platform for third-party applications on the web2013Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A trend seen on the web today is to create a platform where externally developed applications can run inside some kind of main application. This is often done by providing an API to access data and business logic of your service and a sandbox environment in which third-party applications can run. By providing this, it is made possible for external developers to come up with new ideas based on your service. Some good examples on this are Spotify Apps, Apps on Facebook and SalesForce.com.

    Ipendo Systems AB is a company that develops a web platform for intellectual properties. Currently most things on this platform are developed by developers at Ipendo Systems AB. Some interest has though risen to enable external developers to create applications that will in some way run inside the main platform.

    In this thesis an analysis of already existing solutions has been done. These solutions were Spotify Apps and Apps on Facebook. The two have different approaches on how to enable third-party applications to run inside their own service. Facebook’s solution builds mainly on iframe embedded web pages where data access is provided through a web API. Spotify on the other hand hosts the third-party applications themselves but the applications may only consist of HTML5, CSS3 and JavaScript.

    In addition to the analysis a prototype was developed. The purpose of the prototype was to show possible ways to enable third-party applications to run inside your own service. Two solutions showing this were developed. The first one was based on Facebook’s approach with iframing of external web pages. The second was a slightly modified version of Spotify’s solution with only client-side code hosted by the main application. To safely embed the client side code in the main application a sandboxing tool for JavaScript called Caja was used.

    Of the two versions implemented in the prototype was the Iframe solution considered more ready to be utilized in a production environment than Caja. Caja could be seen as an interesting technique for the future but might not be ready to use today. The reason behind this conclusion was that Caja decreased the performance of the written JavaScript as well as adding complexity while developing the third-party applications.

  • 282.
    Abrahamsson, Peder
    Linköpings universitet, Institutionen för datavetenskap.
    Mer lättläst: Påbyggnad av ett automatiskt omskrivningsverktyg till lätt svenska2011Självständigt arbete på grundnivå (kandidatexamen), 12 poäng / 18 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det svenska språket ska finnas tillgängligt för alla som bor och verkar i Sverige. Därförär det viktigt att det finns lättlästa alternativ för dem som har svårighet att läsa svensktext. Detta arbete bygger vidare på att visa att det är möjligt att skapa ett automatisktomskrivningsprogram som gör texter mer lättlästa. Till grund för arbetet liggerCogFLUX som är ett verktyg för automatisk omskrivning till lätt svenska. CogFLUXinnehåller funktioner för att syntaktiskt skriva om texter till mer lättläst svenska.Omskrivningarna görs med hjälp av omskrivningsregler framtagna i ett tidigare projekt.I detta arbete implementeras ytterligare omskrivningsregler och även en ny modul förhantering av synonymer. Med dessa nya regler och modulen ska arbetet undersöka omdet är det är möjligt att skapa system som ger en mer lättläst text enligt etableradeläsbarhetsmått som LIX, OVIX och Nominalkvot. Omskrivningsreglerna ochsynonymhanteraren testas på tre olika texter med en total lägnd på ungefär hundra tusenord. Arbetet visar att det går att sänka både LIX-värdet och Nominalkvoten signifikantmed hjälp av omskrivningsregler och synonymhanterare. Arbetet visar även att det finnsfler saker kvar att göra för att framställa ett riktigt bra program för automatiskomskrivning till lätt svenska.

  • 283.
    Abrahamsson, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Kay, Steven M.
    Stoica, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Estimation of the parameters of a bilinear model with applications to submarine detection and system identification2007Ingår i: Digital signal processing (Print), ISSN 1051-2004, E-ISSN 1095-4333, Vol. 17, nr 4, 756-773 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work we study the problem of estimating the parameters of a bilinear model describing, e.g., the amplitude modulation of extremely low frequency electromagnetic (ELFE) signatures of submarines. A similar problem arises in estimation of a nonlinear dynamic system using a Hammerstein–Wiener model, where two nonlinear static blocks surround a linear dynamic block. For these purposes a new method is derived. It is also shown in the same context that a two-stage method for parameter estimation of Hammerstein–Wiener models can be interpreted as an approximate least squares method. We also show the similarities with the problem of weighted low-rank approximation and the fact that these problems can be solved exactly in finite time using solvers for global optimization of systems of polynomials based on self dual optimization.

  • 284.
    Abrahamsson, Robin
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Berntsen, David
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Comparing modifiability of React Native and two native codebases2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Creating native mobile application on multiple platforms generate a lot of duplicate code. This thesis has evaluated if the code quality attribute modifiability improves when migrating to React Native. One Android and one iOS codebase existed for an application and a third codebase was developed with React Native. The measurements of the codebases were based on the SQMMA-model. The metrics for the model were collected with static analyzers created specifically for this project. The results created consists of graphs that show the modifiability for some specific components over time and graphs that show the stability of the platforms. These graphs show that when measuring code metrics on applications over time it is better to do this on a large codebase that has been developed for some time. When calculating a modifiability value the sum of the metrics and the average value of the metrics between files should be used and it is shown that the React Native platform seems to be more stable than native.

  • 285.
    Abrahamsson, Sofie
    et al.
    Södertörns högskola, Institutionen för kommunikation, medier och it.
    Eriksson, Emelie
    Södertörns högskola, Institutionen för kommunikation, medier och it.
    En utvärdering av synthesizern OP-1 utifrån ett användbarhetsperspektiv2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport handlar om en användbarhetsutvärdering av synthesizern OP-1, utvecklad av företaget Teenage Engineering. Studien är kvalitativ och undersöker bara den omedelbara användarupplevelsen av produkten. Rapporten baseras på resultat från ett antal användbarhetstester, utförda på företaget i fråga. Användbarhetstesterna avser att undersöka hur en användare kan förstå hur OP-1:s kan användas och hur de kan förstår dess olika lägen och vidare på vilket sätt detta påverkar den initiala användarupplevelsen.

    Totalt nio av fjorton tillfrågade personer har ingått i användbarhetstesterna. Urvalsgruppen bestod av personer med tidigare, dock varierande mängd, erfarenhet av synthesizers. I den teoretiska referensramen förenas Jonas Löwgren och Erik Stoltermans brukskvalitetsteorier tillsammans med valda delar av Donald Normans ” Seven Stages of Actions as Design Aids”.

    Resultatet visar att användarna snabbt kommer igång med synthesizerns grundläggande funktioner. Samtliga användare tycker att OP-1 är estetiskt tilltalande, underhållande och uppskattar dess portabla format, med vilket de ser användningsområden i både resor och livesammanhang. Användarna anser också att de inte alltid måste förstå synthesizerns grafiska element, på display eller knappar, då detta tydliggörs efter användning av produkten. Användarna visar svårigheter med funktioner som pattern sequencer och viss redigering i tape. Vidare har de även ibland svårt att förstå i vilket mode som synthesizern befinner sig i.

    Samtliga användbarhetstester utfördes på en pre-betaversion av OP-1. Den slutgiltiga versionen av synthesizern har uppdaterats utefter resultaten från den här undersökningen.

     

  • 286.
    Abrahamyan, Lilit
    et al.
    University of Amsterdam.
    Schaap, Jorrit A.
    Hoekstra, Alfons G.
    Shamonin, Denis
    M.A.Box, Frieke
    Van der Geest, Rob J.
    H.C. Reiber, Johan
    M.A. Sloot, Peter
    A Problem Solving Environment for Image-Based Computational Hemodynamics2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce a complete problem solving environment designed for pulsatile flows in 3D complex geometries, especially arteries. Three-dimensional images from arteries, obtained from e.g. Magnetic Resonance Imaging, are segmented to obtain a geometrical description of the arteries of interest. This segmented artery is prepared for blood flow simulations in a 3D editing tool, allowing to define in- and outlets, to filter and crop part of the artery, to add certain structures ( e.g. a by-pass, or stents ), and to generate computational meshes as input to the blood flow simulators. Using dedicated fluid flow solvers the time dependent blood flow in the artery during one systole is computed. The resulting flow, pressure and shear stress fields are then analyzed using a number of visualization techniques. The whole environment can be operated from a desktop virtual reality system, and is embedded in a Grid computing environment.

  • 287.
    Abrate, Matteo
    et al.
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Bacciu, Clara
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Hast, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion. CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Marchetti, Andrea
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Minutoli, Salvatore
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Tesconi, Maurizio
    CNR Natl Res Council, Inst Informat & Telemat, I-56124 Pisa, Italy.
    Geomemories - A Platform for Visualizing Historical, Environmental and Geospatial Changes of the Italian Landscape2013Ingår i: ISPRS International Journal of Geo-Information. Special issue: Geospatial Monitoring and Modelling of Environmental Change, ISSN 2220-9964, Vol. 2, nr 2, 432-455 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The GeoMemories project aims at publishing on the Web and digitally preserving historical aerial photographs that are currently stored in physical form within the archives of the Aerofototeca Nazionale in Rome. We describe a system, available at http://www.geomemories.org, that lets users visualize the evolution of the Italian landscape throughout the last century. The Web portal allows comparison of recent satellite imagery with several layers of historical maps, obtained from the aerial photos through a complex workflow that merges them together. We present several case studies carried out in collaboration with geologists, historians and archaeologists, that illustrate the great potential of our system in different research fields. Experiments and advances in image processing technologies are envisaged as a key factor in solving the inherent issue of vast amounts of manual work, from georeferencing to mosaicking to analysis.

  • 288.
    Abreu, Rodrigo
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA (stängd 2012-06-30).
    Jansson, Niclas
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA (stängd 2012-06-30).
    Hoffman, Johan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA (stängd 2012-06-30).
    Adaptive computation of aeroacoustic sources for a rudimentary landing gear using lighthill's analogy2011Ingår i: 17th AIAA/CEAS AeroacousticsConference 2011: 32nd AIAA Aeroacoustics Conference, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present our simulation results for the benchmark problem of the ow past a Rudimentary Landing Gear (RLG) using a General Galerkin (G2) nite element method, also referred to as Adaptive DNS/LES. In G2 no explicit subgrid model is used, instead the compuational mesh is adaptively re ned with respect to an a posteriori error es-timate of a quantity of interest in the computation, in this case the drag force on the RLG. Turbulent boundary layers are modeled using a simple wall layer model with the shear stress at walls proportional to the skin friction, which here is assumed to be small and, therefore, can be approximated by zero skin friction. We compare our results with experimental data and other state of the art computations, where we nd good agreement in sound pressure levels, surface velocities and ow separation. We also compare with detailed surface pressure experimental data where we nd largely good agreement, apart from some local dierences for which we discuss possible explanations.

  • 289.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology Miami University Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology Miami University Hamilton, OH.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Distributed Home Automation System Based on IEC 61499 Function Blocks and Wireless Sensor Networks2017Ingår i: 2017 IEEE International Conference on Industrial Technology (ICIT), Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, 1354-1359 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution.

  • 290.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Distributed home automation system based on IEC61499 function blocks and wireless sensor networks2017Ingår i: Proceedings of the IEEE International Conference on Industrial Technology, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, 1354-1359 s., 7915561Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution

  • 291. Abu Bakar, Sakhinah
    et al.
    Taheri, Javid
    The University of Sydney, Australia.
    Zomaya, Albert
    The University of Sydney, Sydney, Australia.
    Characterization of essential proteins in proteins interaction networks2013Ingår i: Journal of Quality Measurement and Analysis, ISSN 1823-5670, Vol. 9, nr 2, 11-26 s.Artikel i tidskrift (Refereegranskat)
  • 292.
    Abu Baker, Mohamed
    Linköpings universitet, Institutionen för datavetenskap, PELAB - Laboratoriet för programmeringsomgivningar.
    Agile Prototyping: A combination of different approaches into one main process2009Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Software prototyping is considered to be one of the most important tools that are used by software engineersnowadays to be able to understand the customer’s requirements, and develop software products that are efficient,reliable, and acceptable economically. Software engineers can choose any of the available prototyping approaches tobe used, based on the software that they intend to develop and how fast they would like to go during the softwaredevelopment. But generally speaking all prototyping approaches are aimed to help the engineers to understand thecustomer’s true needs, examine different software solutions and quality aspect, verification activities…etc, that mightaffect the quality of the software underdevelopment, as well as avoiding any potential development risks.A combination of several prototyping approaches, and brainstorming techniques which have fulfilled the aim of theknowledge extraction approach, have resulted in developing a prototyping approach that the engineers will use todevelop one and only one throwaway prototype to extract more knowledge than expected, in order to improve thequality of the software underdevelopment by spending more time studying it from different points of view.The knowledge extraction approach, then, was applied to the developed prototyping approach in which thedeveloped model was treated as software prototype, in order to gain more knowledge out of it. This activity hasresulted in several points of view, and improvements that were implemented to the developed model and as a resultAgile Prototyping AP, was developed. AP integrated more development approaches to the first developedprototyping model, such as: agile, documentation, software configuration management, and fractional factorialdesign, in which the main aim of developing one, and only one prototype, to help the engineers gaining moreknowledge, and reducing effort, time, and cost of development was accomplished but still developing softwareproducts with satisfying quality is done by developing an evolutionary prototyping and building throwawayprototypes on top of it.

  • 293.
    Abu Khousa, Eman
    et al.
    UAE University, Al Ain, United Arab Emirates.
    Atif, Yacine
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Social network analysis to influence career development2017Ingår i: Journal of Ambient Intelligence and Humanized Computing, ISSN 1868-5137, E-ISSN 1868-5145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Social network analysis techniques have shown a potential for influencing gradu-ates to meet industry needs. In this paper, we propose a social-web driven solutions to bridge formal education and industry needs. The proposed career development frame-work utilizes social network analytics, influence diffusion algorithms and persuasive technology models along three phases: (1) career readiness to measure and visualize the general cognitive dispositions required for a successful career in the 21st Century, (2) career prediction to persuade future graduates into a desired career path by clustering learners whose career prospects are deemed similar, into a community of practice; and (3) career development to drive growth within a social network structure where social network analytics and persuasive techniques are applied to incite the adoption of desired career behaviors. The process starts by discovering behavioral features to create a cognitive profile and diagnose individual deficiencies. Then, we develop a fuzzy clustering algorithm that predicts similar patterns with controlled constraint-violations to construct a social structure for collaborative cognitive attainment. This social framework facilitates the deployment of novel influence diffusion approaches, whereby we propose a reciprocal-weighted similarity function and a triadic clo-sure approach. In doing so, we investigate contemporary social network analytics to maximize influence diffusion across a synthesized social network. The outcome of this social computing approach leads to a persuasive model that supports behavioral changes and developments. The performance results obtained from both analytical and experi-mental evaluations validate our data-driven strategy for persuasive behavioral change.

  • 294.
    Abu Khousa, Eman
    et al.
    UAE University, United Arab Emirates.
    Atif, Yacine
    UAE University, United Arab Emirates.
    Mohammad M., Masud
    UAE University, United Arab Emirates.
    A social learning analytics approach to cognitive apprenticeship2015Ingår i: Smart Learning Environments, ISSN 2196-7091, Vol. 2, nr 14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The need for graduates who are immediately prepared for employment has been widely advocated over the last decade to narrow the notorious gap between industry and higher education. Current instructional methods in formal higher education claim to deliver career-ready graduates, yet industry managers argue their imminent workforce needs are not completely met. From the candidates view, formal academic path is well defined through standard curricula, but their career path and supporting professional competencies are not confidently asserted. In this paper, we adopt a data analytics approach combined with contemporary social computing techniques to measure, instil, and track the development of professional competences of learners in higher education. We propose to augment higher-education systems with a virtual learning environment made-up of three major successive layers: (1) career readiness, to assert general professional dispositions, (2) career prediction to identify and nurture confidence in a targeted domain of employment, and (3) a career development process to raise the skills that are relevant to the predicted profession. We analyze self-declared career readiness data as well as standard individual learner profiles which include career interests and domain-related qualifications. Using these combinations of data sources, we categorize learners into Communities of Practice (CoPs), within which learners thrive collaboratively to build further their career readiness and assert their professional confidence. Towards these perspectives, we use a judicious clustering algorithm that utilizes a fuzzy-logic objective function which addresses issues pertaining to overlapping domains of career interests. Our proposed Fuzzy Pairwise-constraints K-Means (FCKM) algorithm is validated empirically using a two-dimensional synthetic dataset. The experimental results show improved performance of our clustering approach compared to baseline methods.

  • 295.
    Abu Nijmeh, Jonas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Catalan Canales, Diego
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Prokrastinering i form av medieanvändning: En jämförelsestudie kring kön och sysselsättning2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Prokrastinering har sedan länge varit ett problem som många möter. Vare sig det handlar om skolarbete, träning eller något annat har de flesta individer upplevt att de medvetet skjutit upp en uppgift till ett senare tillfälle. Detta fenomen har under senare tid integrerats i vårt samhälle på ett oftast negativt vis. I vårt mediecentrerade samhälle blir vi allt mer uppkopplade och nuförtiden har nästan hela Sveriges befolkning tillgång till internet. Tekniken har medfört många möjligheter men har även öppnat upp för nya sätt att prokrastinera.

    Denna studie ämnade undersöka prokrastinering i form av medieanvändning hos en stor målgrupp bestående av folk i alla åldrar. Vi ämnade att ta reda på eventuella skillnader i prokrastineringsvanor mellan könen men också bland yrkesarbetande och studerande. Tidigare forskning har redan visat att prokrastinering skiljer sig med ålder och sysselsättning. Mot bakgrund av detta söker vi att besvara frågan: Vilka medier använder personer när de prokrastinerar samt på vilka tekniska plattformar sker detta? För att besvara denna forskningsfråga utförde vi en förstudie på en mindre grupp för att få ett bättre förstånd för vilka frågor som var relevanta i sammanhanget. Denna förstudie låg sedan till grund för en enkätstudie med 91 deltagare.

    Resultatet visade tydliga skillnader mellan både män och kvinnor och mellan studerande och yrkesarbetande. Skillnader gällande både medieanvändning och prokrastineringsvanor kunde ses där vissa skillnader var mer märkbara än andra. Resultatet bekräftar tidigare studier i flera aspekter och ger oss en viss insikt om hur olika prokrastineringsvanor kan se ut.

  • 296.
    Abualhana, Munther
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Tariq, Ubaid
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Improving QoE over IPTV using FEC and Retransmission2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    IPTV (Internet Protocol Television), a new and modern concept of emerging technologies with focus on providing cutting edge high-resolution television, broadcast, and other fascinating services, is now easily available with only requirement of high-speed internet. Everytime a new technology is made local, it faces tremendous problems whether from technological point of view to enhance the performance or when it comes down to satisfy the customers. This cutting edge technology has provided researchers to embark and play with different tools to provide better quality while focusing on existing tools. Our target in dissertation is to provide a few interesting facets of IPTV and come up with a concept of introducing an imaginary cache that can re-collect the packets travelling from streaming server to the end user. In the access node this cache would be fixed and then on the basis of certain pre-assumed research work we can conclude how quick retransmission can take place when the end user responds back using RTCP protocol and asks for the retransmission of corrupted/lost packets. In the last section, we plot our scenario of streaming server on one side and client, end user on the other end and make assumption on the basis of throughput, response time and traffic.

  • 297.
    Abugessaisa, Imad
    Linköpings universitet, Institutionen för datavetenskap, GIS - Geografiska informationssystem. Linköpings universitet, Tekniska högskolan.
    Analytical tools and information-sharing methods supporting road safety organizations2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A prerequisite for improving road safety are reliable and consistent sources of information about traffic and accidents, which will help assess the prevailing situation and give a good indication of their severity. In many countries there is under-reporting of road accidents, deaths and injuries, no collection of data at all, or low quality of information. Potential knowledge is hidden, due to the large accumulation of traffic and accident data. This limits the investigative tasks of road safety experts and thus decreases the utilization of databases. All these factors can have serious effects on the analysis of the road safety situation, as well as on the results of the analyses.

    This dissertation presents a three-tiered conceptual model to support the sharing of road safety–related information and a set of applications and analysis tools. The overall aim of the research is to build and maintain an information-sharing platform, and to construct mechanisms that can support road safety professionals and researchers in their efforts to prevent road accidents. GLOBESAFE is a platform for information sharing among road safety organizations in different countries developed during this research.

    Several approaches were used, First, requirement elicitation methods were used to identify the exact requirements of the platform. This helped in developing a conceptual model, a common vocabulary, a set of applications, and various access modes to the system. The implementation of the requirements was based on iterative prototyping. Usability methods were introduced to evaluate the users’ interaction satisfaction with the system and the various tools. Second, a system-thinking approach and a technology acceptance model were used in the study of the Swedish traffic data acquisition system. Finally, visual data mining methods were introduced as a novel approach to discovering hidden knowledge and relationships in road traffic and accident databases. The results from these studies have been reported in several scientific articles.

  • 298.
    Abu-Sheikh, Khalil
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Reviewing and Evaluating Techniques for Modeling and Analyzing Security Requirements2007Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    The software engineering community recognized the importance of addressing security requirements with other functional requirements from the beginning of the software development life cycle. Therefore, there are some techniques that have been developed to achieve this goal. Thus, we conducted a theoretical study that focuses on reviewing and evaluating some of the techniques that are used to model and analyze security requirements. Thus, the Abuse Cases, Misuse Cases, Data Sensitivity and Threat Analyses, Strategic Modeling, and Attack Trees techniques are investigated in detail to understand and highlight the similarities and differences between them. We found that using these techniques, in general, help requirements engineer to specify more detailed security requirements. Also, all of these techniques cover the concepts of security but in different levels. In addition, the existence of different techniques provides a variety of levels for modeling and analyzing security requirements. This helps requirements engineer to decide which technique to use in order to address security issues for the system under investigation. Finally, we found that using only one of these techniques will not be suitable enough to satisfy the security requirements of the system under investigation. Consequently, we consider that it would be beneficial to combine the Abuse Cases or Misuse Cases techniques with the Attack Trees technique or to combine the Strategic Modeling and Attack Trees techniques together in order to model and analyze security requirements of the system under investigation. The concentration on using the Attack Trees technique is due to the reusability of the produced attack trees, also this technique helps in covering a wide range of attacks, thus covering security concepts as well as security requirements in a proper way.

  • 299.
    Aceto, L.
    et al.
    School of Computer Science, Reykjavik University, Iceland.
    Birgisson, A.
    Department of Computer Science and Engineering, Chalmers University of Technology, Sweden.
    Ingolfsdottir, A.
    School of Computer Science, Reykjavik University, Iceland.
    Mousavi, Mohammad Reza
    Department of Computer Science, TU/Eindhoven, Eindhoven, Netherlands.
    Decompositional Reasoning about the History of Parallel Processes2011Ingår i: Fundamentals of software engineering: revised selected papers, Heidelberg: Springer Berlin/Heidelberg, 2011, Vol. 4171, 32-47 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a decomposition technique for Hennessy-Milner logic with past and its extension with recursively defined formulae. In order to highlight the main ideas and technical tools, processes are described using a subset of CCS with parallel composition, nondeterministic choice, action prefixing and the inaction constant. The study focuses on developing decompositional reasoning techniques for parallel contexts in that language. © 2012 Springer-Verlag.

  • 300.
    Aceto, L.
    et al.
    School of Computer Science, Reykjavík University, Kringlan 1, 103 Reykjavík, Iceland.
    Fokkink, W. J.
    Department of Computer Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, Netherlands.
    Ingólfsdóttir, A.
    School of Computer Science, Reykjavík University, Kringlan 1, 103 Reykjavík, Iceland.
    Mousavi, Mohammad Reza
    Department of Computer Science, Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands.
    Lifting non-finite axiomatizability results to extensions of process algebras2010Ingår i: Acta Informatica, ISSN 0001-5903, E-ISSN 1432-0525, Vol. 47, nr 3, 147-177 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a general technique for obtaining new results pertaining to the non-finite axiomatizability of behavioural (pre)congruences over process algebras from old ones. The proposed technique is based on a variation on the classic idea of reduction mappings. In this setting, such reductions are translations between languages that preserve sound (in)equations and (in)equational provability over the source language, and reflect families of (in)equations responsible for the non-finite axiomatizability of the target language. The proposed technique is applied to obtain a number of new non-finite axiomatizability theorems in process algebra via reduction to Moller's celebrated non-finite axiomatizability result for CCS. The limitations of the reduction technique are also studied. In particular, it is shown that prebisimilarity is not finitely based over CCS with the divergent process Ω, but that this result cannot be proved by a reduction to the non-finite axiomatizability of CCS modulo bisimilarity. This negative result is the inspiration for the development of a sharpened reduction method that is powerful enough to show that prebisimilarity is not finitely based over CCS with the divergent process Ω. © 2010 Springer-Verlag.

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