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  • 46351.
    van Leeuwen, Manon
    et al.
    FUNDECYT.
    Velkova, Julia
    Södertörns högskola, Institutionen för kultur och kommunikation, Medie- och kommunikationsvetenskap.
    Özel, Bulent
    Istanbul Bilgi University.
    How to Avoid the Transformation of Barriers to OSS Adoption in Public Administration into Barriers for Regional Development2007Ingår i: Exploiting the Knowledge Economy:: Issues, Applications and Case Studies / [ed] Paul Cunningham & Miriam Cunningham, Amsterdam: IOS Press, 2007, s. 571-578Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 46352.
    van Loon, Patricia
    et al.
    RISE - Research Institutes of Sweden, ICT, Viktoria. INSEAD, France.
    Delagarde, Charles
    INSEAD, France.
    Van Wassenhove, Luk N.
    INSEAD, France.
    The role of second-hand markets in circular business: a simple model for leasing versus selling consumer products2018Ingår i: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 56, nr 1-2, s. 960-973Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper explores the role of the second-hand market when transitioning to a closed-loop system where products are leased multiple times. The total cost of ownership for consumers and profitability for manufacturers are compared in circular and linear business cases. We find that while second-hand markets were beneficial for manufacturers of durable goods in a linear system, since they increased the consumers’ willingness-to-pay for new products, the same second-hand markets might restrict the profitability of a closed-loop business model. A high resale value results in a relatively low cost of ownership in the sales system and additional activities in the closed-loop model (such as managing the lease contracts and refurbishment) add significant costs to the supply chain. Consequently, the economic (and environmental) benefits of leasing products already traded on second-hand markets in the linear system are often limited. Our simple analytical model allows a quick and dirty analysis of multiple scenarios with a minimum of inputs. We argue that manufacturers lack these kinds of models to guide them in navigating circular economy business models.

  • 46353.
    van Loon, Patricia
    et al.
    RISE - Research Institutes of Sweden, ICT, Viktoria. INSEAD, France.
    Delagarde, Charles
    INSEAD, France.
    Van Wassenhove, Luk N.
    INSEAD, France.
    Mihelic, Ales
    R&D Competence Centre Laundry Care, Slovenia.
    Comparing leasing and buying white goods for themanufacturer and consumer2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Remanufacturing, or other forms of recirculating products, can create opportunities forcompanies to become more sustainable while remaining profitable. However, not allcompanies will profit from a move towards a closed-loop business model and a thoroughassessment of the envisioned business models is therefore needed. This paper investigatesthe profitability of leasing and remanufacturing washing machines for a large white goodsproducer.An analytical model is built to simultaneously estimate the total cost of ownership(TCO) of consumers and costs and profit for the manufacturer. The results are comparedagainst the TCO and profitability of the linear system where high, medium and low endwashing machines are sold to the consumers. A sensitivity analysis is conducted onimportant factors such as repair, administration and transport costs.Using the replacement chain method, it was found that the TCO of low-end washingmachines in the sales system are significantly higher than for high-end washing machinesand consequently those consumers would benefit the most from a circular system in whichhigh-end washing machines are leased against acceptable prices. However, due toadditional costs for the manufacturer it remains challenging to make the same level of profitas in the linear system. The research shows important cost components which companieswill have to address when considering a move towards a circular business model that entailsleasing and remanufacturing.

  • 46354.
    van Miltenburg, Jelle
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Conformal survival predictions at a user-controlled time point: The introduction of time point specialized Conformal Random Survival Forests2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med denna avhandling är att utöka området för konformitetsprediktion med hjälp av Random Survival Forests. Standardutförandet av Conformal Random Survival Forest kan förutsäga med en viss säkerhet om någonting kommer att överleva fram till en viss tidpunkt. Denna avhandling är den första som visar att det finns liten praktisk användning i standardutförandet av Conformal Random Survival Forest-algoritmen. Det visar sig att konfidensgarantierna för konformitetsprediktionsramverket bryts om standardalgoritmen gör förutsägelser för en användarstyrd fast tidpunkt. För att lösa denna utmaning, föreslår denna avhandling två algoritmer som specialiserar sig i konformitetsprediktion för en bestämd tidpunkt: en fast-tids algoritm och en hybridalgoritm. Båda algoritmerna omvandlar den överlevnadsdata som används av den delade utvärderingsmetoden i Random Survival Forest-algoritmen. Uppskattningsförmågan för hybridalgoritmen överträffar den för fast-tids algoritmen i de flesta fall. Dessutom är hybrid algoritmen stabilare än fast-tids algoritmen när det förutsägelsejobbet sträcker sig till olika tidpunkter. Hybridalgoritmen för Conformal Random Survival Forest bör därför föredras av den som vill göra konformitetsprediktion av överlevnad vid användarstyrda tidpunkter.

  • 46355.
    Van, Nguyen Hong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    Popov, O.
    Popova, I.
    Combined model for congestion control2006Ingår i: Proceedings of the International Conference on Information Technology Interfaces, ITI, 2006, s. 657-662Konferensbidrag (Refereegranskat)
    Abstract [en]

    The growth of multimedia applications on the Internet made at least one fifth of the total network traffic to run over UDP. Unlike TCP, UDP is unresponsive to network congestion. This may cause, inter alia, bandwidth starvation of responsive flows, severe and prolonged congestions or in the worst-case scenario a congestion collapse. Hence, the coexistence of both protocols on fair-share premises converges towards impossibility. The paper deals with a new approach to solving the problem of taming down the unresponsive flows. By using some of the desirable properties of mobile agents, the system is able to control the influx of non-TCP or unresponsive flows into the network. Various functions performed by mobile agents monitor non-TCP flows, calculate sending rates and modify their intensity according to the needs of the network to attain as good performance as it is possible.

  • 46356. Van, Nguyen Hong
    et al.
    Popov, Oliver
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Popova, Iskra
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Combined Model for Congestion Control - CM4CC2006Ingår i: C I T. Journal of Computing and Information Technology, ISSN 1330-1136, Vol. 14, nr 4, s. 337-342Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growth of multimedia applications on the Internet made at least one fifth of the total network traffic to run over UDP. Unlike TCP, UDP is unresponsive to network congestion. This may cause, inter alia, bandwidth starvation of responsive flows, severe and prolonged congestions or in the worst-case scenario a congestion collapse. Hence, the coexistence of both protocols on fair-share premises converges towards impossibility. The paper deals with a new approach to solving the problem of taming down the unresponsive flows. By using some of the desirable properties of mobile agents, the system is able to control the influx of non-TCP or unresponsive flows into the network. Various functions performed by mobile agents monitor non-TCP flows, calculate sending rates and modify their intensity according to the needs of the network to attain as good performance as it is possible.

  • 46357.
    Van Os, Rob
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    SOC-CMM: Designing and Evaluating a Tool for Measurement of Capability Maturity in Security Operations Centers2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis addresses the research gap that exists in the area of capability maturity measurement for Security Operations Centers (SOCs). This gap is due to the fact that there is very little formal research done in this area. To address this gap in a scientific manner, a multitude of research methods is used.

    Primarily, a design research approach is adopted that combines guiding principles for the design of maturity models with basic design science theory and a step by step approach for executing a design science research project. This design research approach is extended with interviewing techniques, asurvey and multiple rounds of evaluation.

    The result of any design process is an artefact. In this case, the artefact is a self-assessment tool that can be used to establish the capability maturity level of the SOC. This tool was named the SOC-CMM (Security Operations Center Capability Maturity Model). In this tool, maturity is measured across 5 domains: business, people, process, technology and services. Capability is measured across 2 domains: technology and services. The tool provides visual output of results using web diagrams and bar charts. Additionally, an alignment with the National Institute of Standards and Technology Cyber Security Framework (NIST CSF) was also implemented by mapping services and technologies to NIST CSF phases.

    The tool was tested in several rounds of evaluation. The first round of evaluation was aimed at determining whether or not the setup of the tool would be viable to resolve the research problem. The second round of evaluation was a so-called laboratory experiment performed with several participants in the research. The goal of this second round was to determine whether or not the acreated artefact sufficiently addressed the research question. In this experiment it was determined that the artefact was indeed appropriate and mostly accurate, but that some optimisations were required. These optimisations were implemented and subsequently tested in a third evaluation round. The artefact was then finalised.

    Lastly, the SOC-CMM self-assessment tool was compared to the initial requirements and research guidelines set in this research. It was found that the SOC-CMM tool meets the quality requirements set in this research and also meets the requirements regarding design research. Thus, it can be stated that a solution was created that accurately addresses the research gap identified in this thesis.

    The SOC-CMM tool is available from http://www.soc-cmm.com/

  • 46358. Van Roy, P.
    et al.
    Haridi, Seif
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster (Stängd 20120101), Programvaru- och datorsystem, SCS (Stängd 20120101).
    Reinefeld, A.
    Stefani, J. -B
    Yap, R.
    Coupaye, T.
    Self management for large-scale distributed systems: An overview of the SELFMAN project2008Ingår i: 6th International Symposium on Formal Methods for Components and Objects, FMCO 2007, 2008, s. 153-178Konferensbidrag (Refereegranskat)
    Abstract [en]

    As Internet applications become larger and more complex, the task of managing them becomes overwhelming. "Abnormal" events such as software updates, failures, attacks, and hotspots become frequent. The SELFMAN project is tackling this problem by combining two technologies, namely structured overlay networks and advanced component models, to make the system self managing. Structured overlay networks (SONs) developed out of peer-to-peer systems and provide robustness, scalability, communication guarantees, and efficiency. Component models provide the framework to extend the self-managing properties of SONs over the whole system. SELFMAN is building a self-managing transactional storage and using it for two application demonstrators: a distributed Wiki and an on-demand media streaming service. This paper provides an introduction and motivation for the ideas underlying SELFMAN and a snapshot of its contributions midway through the project. We explain our methodology for building self-managing systems as networks of interacting feedback loops. We then summarize the work we have done to make SONs a practical basis for our architecture: using an advanced component model, handling network partitions, handling failure suspicions, and doing range queries with load balancing. Finally, we show the design of a self-managing transactional storage on a SON.

  • 46359. van Roy, Peter
    et al.
    Brand, Per
    RISE - Research Institutes of Sweden, ICT, SICS.
    Haridi, Seif
    RISE - Research Institutes of Sweden, ICT, SICS.
    Collet, Raphael
    A lightweight reliable object migration protocol1999Konferensbidrag (Refereegranskat)
  • 46360. van Roy, Peter
    et al.
    Ghodsi, Ali
    RISE., Swedish ICT, SICS. DSL.
    Stefani, Jean-Bernard
    Haridi, Seif
    RISE., Swedish ICT, SICS. DSL.
    Coupaye, Thierry
    Reinefeld, Alexander
    Winter, Ehrhard
    Yap, Roland H.C.
    Self Management of Large-Scale Distributed Systems by Combining Structured Overlay Networks and Components2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This position paper envisions making large-scale distributed applications self managing by combining component models and structured overlay networks. A key obstacle to deploying large-scale applications running on Internet is the amount of management they require. Often these applications demand specialized personnel for their maintenance. Making applications self-managing will help removing this obstacle. Basing the system on a structured overlay network will allow extending the abilities of existing component models to large-scale distributed systems. Structured overlay networks provide guarantees for efficient communication, e±cient load-balancing, and self-manage in case of joins, leaves, and failures. Component models, on the other hand, support dynamic configuration, the ability of part of the system to reconfigure other parts at run-time. By combining overlay networks with component models we achieve both low-level as well as high-level self-management. We will target multi-tier applications, and specifically we will consider three-tier applications using a self-managing storage service.

  • 46361. van Roy, Peter
    et al.
    Haridi, Seif
    RISE., Swedish ICT, SICS, Computer Systems Laboratory.
    Concepts, Techniques, and Models of Computer Programming2004 (uppl. 1)Bok (Refereegranskat)
  • 46362. van Roy, Peter
    et al.
    Haridi, Seif
    RISE - Research Institutes of Sweden, ICT, SICS.
    Mozart: a programming system for agent applications1999Konferensbidrag (Refereegranskat)
  • 46363. van Roy, Peter
    et al.
    Haridi, Seif
    RISE - Research Institutes of Sweden, ICT, SICS.
    Brand, Per
    RISE - Research Institutes of Sweden, ICT, SICS.
    Smolka, Gert
    Three moves are not as bad as a fire1998Konferensbidrag (Refereegranskat)
  • 46364.
    Van Roy, Peter
    et al.
    Dept. of Comp. Sci. and Engineering, Univ. Catholique de Louvain.
    Haridi, Seif
    Swedish Institute of Computer Science.
    Brand, Per
    Swedish Institute of Computer Science.
    Smolka, Gert
    Ger. Res. Ctr. for Artif. Intell..
    Mehl, Michael
    Ger. Res. Ctr. for Artif. Intell..
    Scheidhauer, Ralf
    Ger. Res. Ctr. for Artif. Intell..
    Mobile objects in distributed Oz1997Ingår i: ACM Transactions on Programming Languages and Systems, ISSN 0164-0925, E-ISSN 1558-4593, Vol. 19, nr 5, s. 804-851Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Some of the most difficult questions to answer when designing a distributed application are related to mobility: what information to transfer between sites and when and how to transfer it. Network-transparent distribution, the property that a program's behavior is independent of how it is partitioned among sites, does not directly address these questions. Therefore we propose to extend all language entities with a network behavior that enables efficient distributed programming by giving the programmer a simple and predictable control over network communication patterns. In particular, we show how to give objects an arbitrary mobility behavior that is independent of the object's definition. In this way, the syntax and semantics of objects are the same regardless of whether they are used as stationary servers, mobile agents, or simply as caches, These ideas have been implemented in Distributed Oz, a concurrent object-oriented language that is state aware and has dataflow synchronization. We prove that the implementation of objects in Distributed Oz, is network transparent. To satisfy the predictability condition, the implementation avoids forwarding chains through intermediate sites. The implementation is an extension to the publicly available DFKI Oz 2.0 system.

  • 46365.
    Van, Sophie
    Högskolan i Skövde, Institutionen för informationsteknologi.
    Encouraging moral reflection in digital games: Feedback systems and their effects2016Självständigt arbete på avancerad nivå (magisterexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of this study is to investigate whether some feedback systems are better at encouraging moral reflection than other in digital games. A small game was developed, which was then made into three versions, each with different feedback systems. A total of 35 people participated in the study. The results indicate that color coding the game’s options decrease the moral reflection, while some feedback in form more ambiguous text is still positively perceived.

  • 46366.
    Van, Sophie
    Högskolan i Skövde, Institutionen för informationsteknologi.
    Spelarmotivationer och karaktärsskapande: Skillnader i karaktärsskapande2014Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    För att kunna anpassa ett spel så bra som möjligt för den tilltänkta målgruppen är det viktigt för speldesigners att förstå vad som motiverar spelare till att spela. Huvudsyftet med detta arbete är att undersöka hur olika spelare utformar sina rollspelskaraktärer och hur dessa spelare skiljer sig åt trots att de spelar samma spel. För att undersöka detta har testdeltagare fått skapa rollspelskaraktärer och sedan motiverat sina val. Ur studien framkom det att spelare prioriterar olika aspekter av sitt karaktärskapande samt att de inte bemödar sig med delar som de finner ointressanta. Fortsatt forskning skulle kunna titta närmare på huruvida kosmetik och immersion hör ihop med tanke på att vissa testdeltagare uppgav att immersion var en stark motivation för dem samtidigt som de inte lade något värde i de kosmetiska aspekterna.

  • 46367.
    van 't Hof, David M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Service Provisioning in SDN using a Legacy Network Management System2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Software Defined Networking (SDN) har blivit mer och mer populärt i kombination med Network Function Virtualization (NFV). SDN är en sätt för att göra ett nätverk mer programmerbart och dynamiskt. För att skapa ett homogent nätverk med detta koncept, behöver man dock ersätta traditionell utrustning med SDN utrustning som är dyr. För att stänga gapet mellan traditionella nätverk och SDN-världen, introducerar vi ett koncept med ett traditionell Network Management System (NMS) som är anslutet till en SDN-styrenhet för att utföra tjänsteprovisionering. På detta sätt kan NMS:et konfigurera både traditionella och SDN-nätverk, samt provisionera tjänster för kunderna medan nya SDN-funktioner möjliggörs i SDN-delen av nätverket.

    Den huvudsakliga tjänsten som vi vill lansera genom SDN är Service Function Chaining (SFC). Tjänsteprovisionering består av att konstruera en väg genom beställda tjänster, i detta fall Virtual Network Functions (VNFs). Detta examensarbete fokuserar huvusakligen på SDN-styrenheten och dess interaktion med NMS:et. Projektet syftar till att konfigurera OpenFlow regler i SDN-styrenheten för att utföra SFC. Dessutom fokuserar arbetet på hur man kan representera SDN-element och SFCs i ett traditionellt NMS. Vidare diskuteras vilken information som ska utbytas mellan NMS:et och SDNstyrenheten. NMS:et som ska vara användas är BECS, ett system utvecklat av Packetfront Software.

    Uppgiften löses genom att skapa ett proof of concept, som innehåller ett komplett system med alla komponenter från nätverkselement till NMS:et. Genom att använda en bottom-up-strategi för detta proof of concept kan informationen som BECS måste skicka till SDN styrenheten indentifieras, innan design och implementation av förbindelsen mellan enheterna kan utföras. När informationen är skickad ska NMS:et kunna hämta information om huruvida styrenheten fick informationen utan fel.

    Dock uppstår ett problem gällande hur man testar och felsöker detta proof of concept. Av denna anledning skapades ett web Graphical User Interface (GUI). Användargränssnittet visar antalet paket som går genom varje VNF, samt var i nätverket fel uppstår. Analysen undersöker hur stor effekten är för en nätverkadministrator och visar att området där fel kan uppstå begränsas avsevärt.

  • 46368.
    van Tol, Amanda
    et al.
    Högskolan Dalarna, Akademin Humaniora och medier, Bildproduktion.
    Laugren, Lina
    Högskolan Dalarna, Akademin Humaniora och medier, Bildproduktion.
    Publiken kommer och går men tv-tablån består: En intervjustudie av fem tablåplanerares syn på tv-tablåns utformning, genusmedvetenhet och framtid.2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med denna uppsats är att undersöka hur tablåplanerare ser på den svenska tv-tablån,

    dess utformning och dess framtid samt hur kanalerna förhåller sig till jämställdhet vid

    tablåplanering. För att göra detta möjligt har vi utfört fem kvalitativa intervjuer med

    tablåplanerare från stora kanaler i Sverige. Valet av kvalitativ intervju grundar sig i att få

    djupare förståelse och inblick i informanternas kunskaper om tablåplanering samt dess

    innehåll och mening.

    Metoden som användes vid analys av transkriberad text från intervjuerna var tematiserad

    analysmetod. Genom att sortera texterna efter teman kunde vi finna mönster från

    informanternas svar som sedan kunde jämföras mot varandra.

    Denna uppsats har resulterat i en insyn i hur tablåplanerarna arbetar; de följer tittarsiffror,

    granskar nya program, konkurrensbevakar och följer publikens efterfrågan. Denna studie visar

    även på att det finns bristande genusmedvetenhet hos de undersökta svenska tv-kanalerna.

    Framtiden för tv-tablån är oviss med tablåplanerarna menar att tv-tablån kommer överleva,

    dock måste en omställning ske på grund av att tittarmönstret förändras

  • 46369. Vanbiervliet, J.
    et al.
    Michiels, W.
    Jarlebring, Elias
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA.
    Using spectral discretization for the optimal H2 design of time-delay systems2011Ingår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 84, nr 2, s. 228-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stabilization and robustification of a time-delay system is the topic of this paper. More precisely, we want to minimize the H2 norm of the transfer function corresponding to this class of linear time-invariant input-output systems with fixed time delays in the states. Due to the presence of the delays, the transfer function is a nonrational, nonlinear function, and the classical procedure which involves solving Lyapunov equations is no longer applicable. We therefore propose an approach based on a spectral discretization applied to a reformulation of the time-delay system as an infinite-dimensional standard linear system. In this way, we obtain a large delay-free system, which serves as an approximation to the original time-delay system, and which allows the application of standard H2 norm optimization techniques. We give an interpretation of this approach in the frequency domain and relate it to the approximation of the nonlinear terms in the time-delay transfer function by means of a rational function. Using this property, we can provide some insight in the convergence be- haviour of the approximation, justifying its use for the purpose of H2 norm computation. Along with this, the easy availibility of derivatives with respect to the original matrices allows for an efficient integration into any standard optimization framework. A numerical example finally illustrates how the presented method can be employed to perform optimal H2 norm design using smooth optimization techniques.

  • 46370. Vandeghinste, Vincent
    et al.
    Martens, Scott
    Kotzé, Gideon
    Tiedemann, Jörg
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Språkvetenskapliga fakulteten, Institutionen för lingvistik och filologi.
    Van den Bogaert, Joachim
    De Smet, Koen
    Van Eynde, Frank
    van Noord, Gertjan
    Parse and Corpus-based Machine Translation2012Ingår i: Essential Speech and Language Technology for Dutch: resources, tools and applications / [ed] Spyns, Peter; Odijk, Jan, Springer , 2012Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 46371.
    Vandeginste, Ruben
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Datalogi. DATALOGI.
    Demoen, Bart
    Sagonas, Konstantinos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Datalogi.
    Segment Order Preserving and Generational Garbage Collection for Prolog2002Ingår i: In Practical Aspects of Declarative Languages: Proceedings of the PADL 2002 Symposium: 2257, 2002, s. 299-317Konferensbidrag (Refereegranskat)
  • 46372.
    Vangal, Sriram R.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Performance and Energy Efficient Building Blocks for Network-on-Chip Architectures2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The ever shrinking size of the MOS transistors brings the promise of scalable Network-on-Chip (NoC) architectures containing hundreds of processing elements with on-chip communication, all integrated into a single die. Such a computational fabric will provide high levels of performance in an energy efficient manner. To mitigate emerging wire-delay problem and to address the need for substantial interconnect bandwidth, packet switched routers are fast replacing shared buses and dedicated wires as the interconnect fabric of choice. With on-chip communication consuming a significant portion of the chip power and area budgets, there is a compelling need for compact, low power routers. While applications dictate the choice of the compute core, the advent of multimedia applications, such as 3D graphics and signal processing, places stronger demands for self-contained, low-latency floating-point processors with increased throughput. Therefore, this work focuses on two key building blocks critical to the success of NoC design: high performance, area and energy efficient router and floating-point processor architectures.

    This thesis first presents a six-port four-lane 57 GB/s non-blocking router core based on wormhole switching. The router features double-pumped crossbar channels and destinationaware channel drivers that dynamically configure based on the current packet destination. This enables 45% reduction in crossbar channel area, 23% overall router area, up to 3.8X reduction in peak channel power, and 7.2% improvement in average channel power, with no performance penalty over a published design. In a 150nm six-metal CMOS process, the 12.2mm2 router contains 1.9 million transistors and operates at 1GHz at 1.2V. We next present a new pipelined single-precision floating-point multiply accumulator core (FPMAC) featuring a single-cycle accumulate loop using base 32 and internal carry-save arithmetic, with delayed addition techniques. Combined algorithmic, logic and circuit techniques enable multiply-accumulates at speeds exceeding 3GHz, with single-cycle throughput. Unlike existing FPMAC architectures, the design eliminates scheduling restrictions between consecutive FPMAC instructions. The optimizations allow removal of the costly normalization step from the critical accumulate loop and conditionally powered down using dynamic sleep transistors on long accumulate operations, saving active and leakage power. In addition, an improved leading zero anticipator (LZA) and overflow detection logic applicable to carry-save format is presented. In a 90nm seven-metal dual-VT CMOS process, the 2mm2 custom design contains 230K transistors. The fully functional first silicon achieves 6.2 GFLOPS of performance while dissipating 1.2W at 3.1GHz, 1.3V supply.

    It is clear that realization of successful NoC designs require well balanced decisions at all levels: architecture, logic, circuit and physical design. Our results from key building blocks demonstrate the feasibility of pushing the performance limits of compute cores and communication routers, while keeping active and leakage power, and area under control.

  • 46373.
    VANGALA, SHIVAKANTHREDDY
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Pattern Recognition applied to Continuous integration system.2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Context: Thisthesis focuses on regression testing in the continuous integration environment which is integration testing that ensures that changes made in the new development code to thesoftware product do not introduce new faults to the software product. Continuous integration is software development practice which integrates all development, testing, and deployment activities. In continuous integration,regression testing is done by manually selecting and prioritizingtestcases from a larger set of testcases. The main challenge faced using manual testcases selection and prioritization is insome caseswhereneeded testcases are ignored in subset of selected testcasesbecause testers didn’t includethem manually while designing hourly cycle regression test suite for particular feature development in product. So, Ericsson, the company in which environment this thesis is conducted,aims at improvingtheirtestcase selection and prioritization in regression testing using pattern recognition.

    Objectives:This thesis study suggests prediction models using pattern recognition algorithms for predicting future testcases failures using historical data. This helpsto improve the present quality of continuous integration environment by selecting appropriate subset of testcases from larger set of testcases for regression testing. There exist several candidate pattern recognition algorithms that are promising for predicting testcase failures. Based on the characteristics of the data collected at Ericsson, suitable pattern recognition algorithms are selected and predictive models are built. Finally, two predictive models are evaluated and the best performing model is integrated into the continuous integration system.

    Methods:Experiment research method is chosen for this research because discovery of cause and effect relationships between dependent and independent variables can be used for the evaluation of the predictive model.The experiment is conducted in RStudio, which facilitates to train the predictive models using continuous integration historical data. The predictive ability of the algorithms is evaluated using prediction accuracy evaluation metrics.

    Results: After implementing two predictive models (neural networks & k-nearest means) using continuous integration data, neural networks achieved aprediction accuracy of 75.3%, k-nearest neighbor gave result 67.75%.

    Conclusions: This research investigated the feasibility of an adaptive and self-learning test machinery by pattern recognition in continuous integration environment to improve testcase selection and prioritization in regression testing. Neural networks have proved effective capability of predicting failure testcase by 75.3% over the k-nearest neighbors.Predictive model can only make continuous integration efficient only if it has 100% prediction capability, the prediction capability of the 75.3% will not make continuous integration system more efficient than present static testcase selection and prioritization as it has deficiency of lacking prediction 25%. So, this research can only conclude that neural networks at present has 75.3% prediction capability but in future when data availability is more,this may reach to 100% predictive capability. The present Ericsson continuous integration system needs to improve its data storage for historical data at present it can only store 30 days of historical data. The predictive models require large data to give good prediction. To support continuous integration at present Ericsson is using jenkins automation server, there are other automation servers like Team city, Travis CI, Go CD, Circle CI which can store data more than 30 days using them will mitigate the problem of data storage.

  • 46374.
    Vanhainen, Niklas
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Discovering Words from Continuous Speech – A study of two factor analysis methods.2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Moderna taligenkännare är beroende av förprogrammerad kunskap om språk och omfattande annoterade exempel. Barn är dock påfallande välanpassade för att lära sig språket utan sådana hjälpmedel. De lär sig istället från exempel av tal och från den miljö de växer upp i. Att modellera denna inlärningsprocess är ett mycket intressant men också ett väldigt komplext problem, som inte bara innefattar tal utan alla de sinnen barnet har tillgängligt.

    I det här exjobbet studeras en del av detta problem, att upptäcka ord från kontinuerligt tal utan tidigare kunskap om språket i fråga. Två olika metoder används för detta syfte. Det grundläggande antagandet för båda metoder är detsamma och så är även tillvägagångssättet. Båda metoder försöker hitta ofta förekommande sekvenser i yttranden och båda metoder går ut på att hitta en linjär kombination av vektorer som bäst representerar en matris som innehåller representationer av ett antal yttranden.

    Den första metoden är en nyligen utvecklad metod som använder ickeparametrisk Bayesisk statistik för att utföra faktoranalys. Metoden kallas Beta Process Factor Analysis (BPFA) och anpassas i det här exjobbet för att kunna användas för ordupptäckt. Den andra metoden kallas Non-negative Matrix Factorization (NMF) och har tidigare använts för ordupptäckt, denna metod används i det här exjobbet som en referens. Fördelen med den nya metoden jämfört med NMF är att den kan hitta antalet vektorer som bäst representerar yttranden och därmed även antalet ordkandidater. Resultaten som erhålls med BPFA jämförs med NMF på TIDigits-databasen, och i exjobbet visas att den nya metoden inte bara kan hitta orden utan även det korrekta antalet ord. Vidare visas att BPFA kan antyda det ungefärliga antalet ord som finns i slumpvis genererade meningar med olika storlekar på vokabulären.

  • 46375.
    Vanhainen, Niklas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Salvi, Giampiero
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Free Acoustic and Language Models for Large Vocabulary Continuous Speech Recognition in Swedish2014Ingår i: Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14), 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents results for large vocabulary continuous speech recognition (LVCSR) in Swedish. We trained acoustic models on the public domain NST Swedish corpus and made them freely available to the community. The training procedure corresponds to the reference recogniser (RefRec) developed for the SpeechDat databases during the COST249 action. We describe the modifications we made to the procedure in order to train on the NST database, and the language models we created based on the N-gram data available at the Norwegian Language Council. Our tests include medium vocabulary isolated word recognition and LVCSR. Because no previous results are available for LVCSR in Swedish, we use as baseline the performance of the SpeechDat models on the same tasks. We also compare our best results to the ones obtained in similar conditions on resource rich languages such as American English. We tested the acoustic models with HTK and Julius and plan to make them available in CMU Sphinx format as well in the near future. We believe that the free availability of these resources will boost research in speech and language technology in Swedish, even in research groups that do not have resources to develop ASR systems.

  • 46376.
    Vanhainen, Niklas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Salvi, Giampiero
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Pattern Discovery in Continuous Speech Using Block Diagonal Infinite HMM2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose the application of a recently introduced inference method, the Block Diagonal Infinite Hidden Markov Model (BDiHMM), to the problem of learning the topology of a Hidden Markov Model (HMM) from continuous speech in an unsupervised way. We test the method on the TiDigits continuous digit database and analyse the emerging patterns corresponding to the blocks of states inferred by the model. We show how the complexity of these patterns increases with the amount of observations and number of speakers. We also show that the patterns correspond to sub-word units that constitute stable and discriminative representations of the words contained in the speech material.

  • 46377.
    Vanhainen, Niklas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Salvi, Giampiero
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Word Discovery with Beta Process Factor Analysis2012Ingår i: 13th Annual Conference of the International Speech Communication Association 2012, INTERSPEECH 2012, Vol 1, 2012, s. 798-801Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose the application of a recently developed non-parametric Bayesian method for factor analysis to the problem of word discovery from continuous speech. The method, based on Beta Process priors, has a number of advantages compared to previously proposed methods, such as Non-negative Matrix Factorisation (NMF). Beta Process Factor Analysis (BPFA) is able to estimate the size of the basis, and therefore the number of recurring patterns, or word candidates, found in the data. We compare the results obtained with BPFA and NMF on the TIDigits database, showing that our method is capable of not only finding the correct words, but also the correct number of words. We also show that the method can infer the approximate number of words for different vocabulary sizes by testing on randomly generated sequences of words.

  • 46378.
    Vanhauer, Marleen
    Umeå universitet, Samhällsvetenskaplig fakultet, Informatik.
    Global Family Networking for the Elderly: Evaluation and Redesign of ModernFamilies.net2009Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This paper, the corresponding wireframe documentation including the functional prototype and flowchart document the evaluation and redesign of the beta version of the social networking platform ModernFamilies.net. In order to reveal possible usability flaws for people of different generations, in particular the elderly, a user-centered design approach including an expert review, diary studies and interviews were conducted. The findings reflected the need for consistency and feedback in general. For young children, the concept of the site appeared to behard to grasp. Experienced users found the access and management of relatives cumbersome. Most importantly, the elderly, novice computer users had a hard time getting started with the site on their own because they did not have access to a PC nor internet at their home. The latter and the fact, that some issues might never be solved by traditional usability testing because the user just feels overwhelmed by the vast amount of communication features he is faced with today calls for alternative, more intelligent, ambient interfaces. However, we came to the conclusion that although evaluation of such new technologies with elderly people is not alwayseasy, it is best to be conducted in the participants home or a similar environment.

  • 46379.
    Vanin, E
    RISE., Swedish ICT, Acreo.
    Performance evaluation of intensity modulated optical OFDM system with digital basebdistortion2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 5, s. 4280-93Artikel i tidskrift (Refereegranskat)
  • 46380.
    Vanin, E
    RISE., Swedish ICT, Acreo.
    Signal restoration in intensity-modulated optical OFDM access systems2011Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 36, nr 22, s. 4338-40Artikel i tidskrift (Refereegranskat)
  • 46381. Vanin, E
    et al.
    Jacobsen, G
    RISE., Swedish ICT, Acreo.
    Analytical estimation of laser phase noise induced BER floor in coherent receiver with digital signal processing2010Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, nr 5, s. 4246-59Artikel i tidskrift (Refereegranskat)
  • 46382.
    Vanin, E
    et al.
    RISE., Swedish ICT, Acreo.
    Jacobsen, G
    RISE., Swedish ICT, Acreo.
    Signal Patterning Nonlinear Phase Noise in 111 Gb/s PolMux- RZ-DQPSK Systems with 50 GHz Channel Spacing2009Ingår i: J. Opt. Commun, Vol. 31Artikel i tidskrift (Refereegranskat)
  • 46383.
    Vanin, E
    et al.
    RISE., Swedish ICT, Acreo.
    Jacobsen, G
    RISE., Swedish ICT, Acreo.
    Berntson, A
    RISE., Swedish ICT, Acreo.
    Effective simulation method for parametric signal-noise interaction in transmission fibers2006Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, nr 15, s. 2272-74Artikel i tidskrift (Refereegranskat)
  • 46384.
    Vanin, E
    et al.
    RISE., Swedish ICT, Acreo.
     Jacobsen, G
    RISE., Swedish ICT, Acreo.
    Berntson, A
    RISE., Swedish ICT, Acreo.
    Nonlinear phase noise separation method for on-off keying transmission system modeling with non-Gaussian noise generation in optical fibers2007Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 32, s. 1740-Artikel i tidskrift (Refereegranskat)
  • 46385.
    Vanin, E V
    et al.
    RISE., Swedish ICT, Acreo.
    Persson, U
    Jacobsen, G
    RISE., Swedish ICT, Acreo.
    Spectral functional forms for gain noise characterization of erbium doped fiber amplifiers2002Ingår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 20, s. 243-49Artikel i tidskrift (Refereegranskat)
  • 46386.
    Vanin, EV
    et al.
    RISE., Swedish ICT, Acreo.
    Grishin, AM
    Khartsev, SI
    Tarasenko, O
    RISE., Swedish ICT, Acreo.
    Johansson, P
    RISE., Swedish ICT, Acreo.
    Broadbphotoluminescence from pulsed laser deposited Er2O3 films2006Ingår i: Journal of Luminescence, Vol. 121, s. 256-58Artikel i tidskrift (Refereegranskat)
  • 46387.
    Vapen, Anna
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Contributions to Web Authentication for Untrusted Computers2011Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Authentication methods offer varying levels of security. Methods with one-time credentials generated by dedicated hardware tokens can reach a high level of security, whereas password-based authentication methods have a low level of security since passwords can be eavesdropped and stolen by an attacker. Password-based methods are dominant in web authentication since they are both easy to implement and easy to use. Dedicated hardware, on the other hand, is not always available to the user, usually requires additional equipment and may be more complex to use than password-based authentication.

    Different services and applications on the web have different requirements for the security of authentication.  Therefore, it is necessary for designers of authentication solutions to address this need for a range of security levels. Another concern is mobile users authenticating from unknown, and therefore untrusted, computers. This in turn raises issues of availability, since users need secure authentication to be available, regardless of where they authenticate or which computer they use.

    We propose a method for evaluation and design of web authentication solutions that takes into account a number of often overlooked design factors, i.e. availability, usability and economic aspects. Our proposed method uses the concept of security levels from the Electronic Authentication Guideline, provided by NIST.

    We focus on the use of handheld devices, especially mobile phones, as a flexible, multi-purpose (i.e. non-dedicated) hardware device for web authentication. Mobile phones offer unique advantages for secure authentication, as they are small, flexible and portable, and provide multiple data transfer channels. Phone designs, however, vary and the choice of channels and authentication methods will influence the security level of authentication. It is not trivial to maintain a consistent overview of the strengths and weaknesses of the available alternatives. Our evaluation and design method provides this overview and can help developers and users to compare and choose authentication solutions.

  • 46388.
    Vapen, Anna
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Mahanti, A.
    NICTA, Sydney NSW, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Third-party identity management usage on the web2014Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Berlin/Heidelberg, 2014, Vol. 8362 LNCS, s. 151-162Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many websites utilize third-party identity management services to simplify access to their services. Given the privacy and security implications for end users, an important question is how websites select their third-party identity providers and how this impacts the characteristics of the emerging identity management landscape seen by the users. In this paper we first present a novel Selenium-based data collection methodology that identifies and captures the identity management relationships between sites and the intrinsic characteristics of the websites that form these relationships. Second, we present the first large-scale characterization of the third-party identity management landscape and the relationships that makes up this emerging landscape. As a reference point, we compare and contrast our observations with the somewhat more understood third-party content provider landscape. Interesting findings include a much higher skew towards websites selecting popular identity provider sites than is observed among content providers, with sites being more likely to form identity management relationships that have similar cultural, geographic, and general site focus. These findings are both positive and negative. For example, the high skew in usage places greater responsibility on fewer organizations that are responsible for the increased information leakage cost associated with highly aggregated personal information, but also reduces the users control of the access to this information. © 2014 Springer International Publishing Switzerland.

  • 46389.
    Vapen, Anna
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    A Look at the Third-Party Identity Management Landscape2016Ingår i: IEEE Internet Computing, ISSN 1089-7801, E-ISSN 1941-0131, Vol. 20, nr 2, s. 18-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many websites act as relying parties (RPs) by allowing access to their services via third-party identity providers (IDPs), such as Facebook and Google. Using IDPs simplifies account creation, login activity, and information sharing across websites. However, different websites use of IDPs can have significant security and privacy implications for users. Here, the authors provide an overview of third-party identity managements current landscape. Using datasets collected through manual identification and large-scale crawling, they answer questions related to which sites act as RPs, which sites are the most successful IDPs, and how different classes of RPs select their IDPs.

  • 46390.
    Vapen, Anna
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    2-clickAuth - Optical Challenge-Response Authentication using Mobile Handsets2011Ingår i: International Journal on Mobile Computing and Multimedia Communications, ISSN 1937-9412, E-ISSN 1937-9404, Vol. 3, nr 2, s. 1-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Internet users often have usernames and passwords at multiple web sites. To simplify things, many sites support federated identity management, which enables users to have a single account allowing them to log on to different sites by authenticating to a single identity provider. Most identity providers perform authentication using a username and password. Should these credentials be compromised, all of the user’s accounts become compromised. Therefore a more secure authentication method is desirable. This paper implements 2-clickAuth, a multimedia-based challenge-response solution which uses a web camera and a camera phone for authentication. Two-dimensional barcodes are used for the communication between phone and computer, which allows 2-clickAuth to transfer relatively large amounts of data in a short period of time. 2-clickAuth is more secure than passwords while easy to use and distribute. 2-clickAuth is a viable alternative to passwords in systems where enhanced security is desired, but availability, ease-of-use, and cost cannot be compromised. This paper implements an identity provider in the OpenID federated identity management system that uses 2-clickAuth for authentication, making 2-clickAuth available to all users of sites that support OpenID, including Facebook, Sourceforge, and MySpace.

  • 46391.
    Vapen, Anna
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Shahmehri, Nahid
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Security Levels for Web Authentication using Mobile Phones2011Ingår i: Privacy and Identity Management for Life / [ed] Simone Fischer-Hübner, Penny Duquenoy, Marit Hansen, Ronald Leenes and Ge Zhang, Boston: Springer , 2011, s. 130-143Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile phones offer unique advantages for secure authentication: they are small and portable, provide multiple data transfer channels, and are nearly ubiquitous. While phones provide a flexible and capable platform, phone designs vary, and the security level of an authentication solution is influenced by the choice of channels and authentication methods. It can be a challenge to get a consistent overview of the strengths and weaknesses of the available alternatives. Existing guidelines for authentication usually do not consider the specific problems in mobile phone authentication. We provide a method for evaluating and designing authentication solutions using mobile phones, using an augmented version of the Electronic Authentication Guideline.

  • 46392.
    Vapen, Anna
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Security Levels for Web Authentication using Mobile Phones2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Mobile phones offer unique advantages for secure authentication: they are small and portable, provide multiple data transfer channels, and are nearly ubiquitous. While phones provide a flexible and capable platform, phone designs vary, and the security level of an authentication solution is influenced by the choice of channels and authentication methods. It can be a challenge to get a consistent overview of the strengths and weaknesses of the available alternatives. In this paper we provide a method for evaluating and designing authentication solutions using mobile phones. The method also considers availability and usability, which are often overlooked factors. The goal is to help developers to create secure authentication, considering the user's priorities on security, availability and usability.

  • 46393. Vapirev, A.
    et al.
    Deca, J.
    Lapenta, G.
    Markidis, Stefano
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Hur, I.
    Cambier, J. -L
    Initial results on computational performance of Intel many integrated core, sandy bridge, and graphical processing unit architectures: implementation of a 1D c++/OpenMP electrostatic particle-in-cell code2015Ingår i: Concurrency and Computation, ISSN 1532-0626, E-ISSN 1532-0634, Vol. 27, nr 3, s. 581-593Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present initial comparison performance results for Intel many integrated core (MIC), Sandy Bridge (SB), and graphical processing unit (GPU). A 1D explicit electrostatic particle-in-cell code is used to simulate a two-stream instability in plasma. We compare the computation times for various number of cores/threads and compiler options. The parallelization is implemented via OpenMP with a maximum thread number of 128. Parallelization and vectorization on the GPU is achieved with modifying the code syntax for compatibility with CUDA. We assess the speedup due to various auto-vectorization and optimization level compiler options. Our results show that the MIC is several times slower than SB for a single thread, and it becomes faster than SB when the number of cores increases with vectorization switched on. The compute times for the GPU are consistently about six to seven times faster than the ones for MIC. Compared with SB, the GPU is about two times faster for a single thread and about an order of magnitude faster for 128 threads. The net speedup, however, for MIC and GPU are almost the same. An initial attempt to offload parts of the code to the MIC coprocessor shows that there is an optimal number of threads where the speedup reaches a maximum.

  • 46394.
    Varada, Shanmukha Shri Sri
    Högskolan i Skövde, Institutionen för kommunikation och information.
    Neural Networks and Smart Antennae: A Case Study2005Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats
    Abstract [en]

    This dissertation evaluates the artificial neural technique for evolving a smart antenna system. The AI techniques pose a challenging research in the field of communication. As such the antennas help to communicate with the digital processor to choose the desired signals and reject the others. It makes its own decision even to find the level of interferences and noises to be discarded by amplitude elimination process through the use of perceptron optimization algorithms like LMS (Least Mean Squares). This method helps to enhance the performance of signal processing efficiently. The design of hardware and software are quite complex. This is due to the fact, that the behaviour of the system is not fully understood being a real-time dependent system. This research work is carried only on software with certain simulated activity on beam-formation algorithm and as well, the system responses before and after using the adaptive algorithm. In this report, we try to concentrate to work on the method of adaptivity to make antenna adaptable to a virtual form of real-time environment. For, this reason a two-element antenna is used for simulation testing, as it is the most commonly used antenna for all purposes in communication. It is also tested on various scanning levels of rotation to determine the learning rate (a parameter that has no effect on the radiation output after using LMS) mean-square error rates and convergence analysis. For the purpose of above mentioned tests, three hypotheses are framed in relation to side-lobe reduction level above 5 decibels, the narrowing of the beam after adaptivity and finally the response of the main beam output for varying values of learning rate, respectivelty. The given research work, may comprehend good practical use of this LMS algorithm and also to indicate antenna patterns and the responses to adaptivity conditions through clarity in graphical format.

    The method is influenced to reduce computational complexity and bring simplicity to the functionality of the antenna with more efficient and effective adaptivness. An effort to test theoretical concepts in practice is also been made in this thesis work. The results show that the antenna system can be made to evolve itself through the process of adaptation with simple behaviour by relying on artificial intelligence technique which ensures little supervision and human intereference. Eventually, it is understood that the reader should have possessed prior concepts, related to antennas, digital signal processing and its practical usage in artificially intelligent systems and as well the exceptions in it, since the work is explained in the direct level assuming so.

  • 46395.
    Varagnolo, Damiano
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Del Favero, Simone
    Dinuzzo, Francesco
    Schenato, Luca
    Pillonetto, Gianluigi
    Finding Potential Support Vectors in Separable Classification Problems2013Ingår i: IEEE Transactions on Neural Networks and Learning Systems, ISSN 2162-237X, Vol. 24, nr 11, s. 1799-1813Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper considers the classification problem using support vector (SV) machines and investigates how to maximally reduce the size of the training set without losing information. Under separable data set assumptions, we derive the exact conditions stating which observations can be discarded without diminishing the overall information content. For this purpose, we introduce the concept of potential SVs, i.e., those data that can become SVs when future data become available. To complement this, we also characterize the set of discardable vectors (DVs), i.e., those data that, given the current data set, can never become SVs. Thus, these vectors are useless for future training purposes and can eventually be removed without loss of information. Then, we provide an efficient algorithm based on linear programming that returns the potential and DVs by constructing a simplex tableau. Finally, we compare it with alternative algorithms available in the literature on some synthetic data as well as on data sets from standard repositories.

  • 46396.
    Varatharajah, Thujeepan
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Victor, Eriksson
    A comparative study on artificial neural networks and random forests for stock market prediction2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna studie undersöker hur väl två olika modeller inom maskininlärning (ML) kan förutspå aktiemarknaden och jämför sedan resultaten av dessa. De valda modellerna baseras på artificiella neurala nätverk (ANN) samt random forests (RF). Modellerna tränas upp med två separata datamängder och prognoserna sker på nästföljande dags stängningskurs. Indatan för modellerna består av 6 olika finansiella nyckeltal som är baserade på stängningskursen för de senaste 5, 10 och 20 dagarna. Prestandan utvärderas genom att analysera och jämföra värden som root mean squared error (RMSE) samt mean average percentage error (MAPE) för testperioden. Även specifika trender i delmängder av testperioden undersöks för att utvärdera följdriktigheten av modellerna. Resultaten visade att ANN-modellen presterade bättre än RF-modellen då den sett över hela testperioden visade mindre fel jämfört med de faktiska värdena och gjorde därmed mer träffsäkra prognoser.

  • 46397.
    Varava, Anastasiia
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Pokorny, Florian T.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Caging Grasps of Rigid and Partially Deformable 3-D Objects With Double Fork and Neck Features2016Ingår i: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 32, nr 6, s. 1479-1497Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Caging provides an alternative to point-contact-based rigid grasping, relying on reasoning about the global free configuration space of an object under consideration. While substantial progress has been made toward the analysis, verification, and synthesis of cages of polygonal objects in the plane, the use of caging as a tool for manipulating general complex objects in 3-D remains challenging. In this work, we introduce the problem of caging rigid and partially deformable 3-D objects, which exhibit geometric features we call double forks and necks. Our approach is based on the linking number-a classical topological invariant, allowing us to determine sufficient conditions for caging objects with these features even in the case when the object under consideration is partially deformable under a set of neck or double fork preserving deformations. We present synthesis and verification algorithms and demonstrations of applying these algorithms to cage 3-D meshes.

  • 46398.
    Vardanyan, Konstantin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    A Low Cost Time Domain Reflectometry Circuit for printed Electronic Applications2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 46399.
    Varea, Mauricio
    et al.
    Dept. Electronics and Computer Science University of Southampton.
    Al Hashimi, Bashir M.
    Dept. of Electronics and Computer Science University of Southampton.
    Cortes, Luis-Alejandro
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Eles, Petru Ion
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Peng, Zebo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Symbolic Model Checking of Dual Transition Petri Nets2002Ingår i: 10th International Symposium on HardwareSoftware Codesign CODES 2002,2002, Estes Park, Colorado, USA: IEEE Computer Society Press , 2002, s. 43-Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the formal verification of the recently introduced Dual Transition Petri Net (DTPN) models, using model checking techniques. The methodology presented addresses the symbolic model checking of embedded systems behavioural properties, expressed in either computation tree logics (CTL) or linear temporal logics (LTL). The embedded system specification is given in terms of DTPN models, where elements of the model are captured in a four-module library which implements the behaviour of the model. Key issues in the development of the methodology are the heterogeneity and the nondeterministic nature of the model. This is handled by introducing some modifications in both structure and behaviour of the model, thus reducing the points of nondeterminism. Several features of the methodology are discussed and two examples are given in order to show the validity of the model.

  • 46400.
    Varea, Mauricio
    et al.
    Dept. of Electronics and Computer Science University of Southampton.
    Al-Hashimi, Bashir
    Dept. of Electronics and Computer Science University of Southampton.
    Cortes, Luis-Alejandro
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Eles, Petru Ion
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Peng, Zebo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Dual Flow Nets: Modelling the Control/Data-Flow Relation in Embedded Systems2006Ingår i: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 5, nr 1, s. 54-81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper addresses the interrelation between control and data flow in embedded system models through a new design representation, called Dual Flow Net (DFN). A modeling formalism with a very close-fitting control and data flow is achieved by this representation, as a consequence of enhancing its underlying Petri net structure. The work presented in this paper does not only tackle the modeling side in embedded systems design, but also the validation of embedded system models through formal methods. Various introductory examples illustrate the applicability of the DFN principles, whereas the capability of the model to with complex designs is demonstrated through the design and verification of a real-life Ethernet coprocessor.

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