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  • 1. Afonso, M. M.
    et al.
    Mitra, Dhrubaditya
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Vincenzi, D.
    Kazantsev dynamo in turbulent compressible flows2019Inngår i: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 475, nr 2223, artikkel-id 20180591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the kinematic fluctuation dynamo problem in a flow that is random, white-in-time, with both solenoidal and potential components. This model is a generalization of the well-studied Kazantsev model. If both the solenoidal and potential parts have the same scaling exponent, then, as the compressibility of the flow increases, the growth rate decreases but remains positive. If the scaling exponents for the solenoidal and potential parts differ, in particular if they correspond to typical Kolmogorov and Burgers values, we again find that an increase in compressibility slows down the growth rate but does not turn it off. The slow down is, however, weaker and the critical magnetic Reynolds number is lower than when both the solenoidal and potential components display the Kolmogorov scaling. Intriguingly, we find that there exist cases, when the potential part is smoother than the solenoidal part, for which an increase in compressibility increases the growth rate. We also find that the critical value of the scaling exponent above which a dynamo is seen is unity irrespective of the compressibility. Finally, we realize that the dimension d = 3 is special, as for all other values of d the critical exponent is higher and depends on the compressibility.

  • 2.
    Ahmed, Olfet
    et al.
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Saman, Nawar
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Utvärdering av nätverkssäkerheten på J Bil AB2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta examensarbete är en utvärdering av nätverkssäkerheten hos J BiL AB, både på social och teknisk nivå. Företaget är beroende av säkra Internet-anslutningar för att nå externa tjänster och interna servrar lokaliserade på olika geografiska platser. Företaget har ingen IT-ansvarig som aktivt underhåller och övervakar nätverket, utan konsulterar ett externt dataföretag. Syftet med examensarbetet är att utvärdera säkerheten, upptäcka brister, ge förbättringsförslag och till viss del implementera lösningar. För att undersöka säkerheten har observationer och intervjuer med personalen gjorts och ett flertal attacker mot nätverket har utförts. Utifrån den data som samlats in kunde slutsatsen dras att företaget har brister vad gäller IT-säkerheten. Framförallt den sociala säkerheten visade sig ha stora luckor vilket till stor del beror på att de anställda varken har blivit utbildade eller fått någon information om hur de ska hantera lösenord, datorer och IT-frågor i allmänt. Förbättringsförslag har getts och viss implementation har genomförts för att eliminera bristerna. De anställda har även med hjälp av en IT-policy och föreläsning blivit utbildade i hur de ska agera och tänka kring IT-relaterade säkerhetsfrågor.

  • 3.
    Ahmed, Tanvir Saif
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Markovic, Bratislav
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Distribuerade datalagringssystem för tjänsteleverantörer: Undersökning av olika användningsfall för distribuerade datalagringssystem2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta examensarbete handlar om undersökning av tre olika användningsfall inom datalagring; Cold Storage, High Performance Storage och Virtual Machine Storage. Rapporten har som syfte att ge en översikt över kommersiella distribuerade filsystem samt en djupare undersökning av distribuerade filsystem som bygger på öppen källkod och därmed hitta en optimal lösning för dessa användnings-fall. I undersökningen ingick att analysera och jämföra tidigare arbeten där jämförelser mellan pre-standamätningar, dataskydd och kostnader utfördes samt lyfta upp diverse funktionaliteter (snapshotting, multi-tenancy, datadeduplicering, datareplikering) som moderna distribuerade filsy-stem kännetecknas av. Både kommersiella och öppna distribuerade filsystem undersöktes. Även en kostnadsuppskattning för kommersiella och öppna distribuerade filsystem gjordes för att ta reda på lönsamheten för dessa två typer av distribuerat filsystem.Efter att jämförelse och analys av olika tidigare arbeten utfördes, visade sig att det öppna distribue-rade filsystemet Ceph lämpade sig bra som en lösning utifrån kraven som sattes som mål för High Performance Storage och Virtual Machine Storage. Kostnadsuppskattningen visade att det var mer lönsamt att implementera ett öppet distribuerat filsystem. Denna undersökning kan användas som en vägledning vid val mellan olika distribuerade filsystem.

  • 4. Alesii, Roberto
    et al.
    Congiu, Roberto
    Santucci, Fortunato
    Di Marco, Piergiuseppe
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Architectures and protocols for fast identification in large-scale RFID systems2014Inngår i: ISCCSP 2014 - 2014 6th International Symposium on Communications, Control and Signal Processing, Proceedings, 2014, s. 243-246Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Passive tags based on backscattered signals yield low energy consumption for large-scale applications of RFIDs. In this paper, system architectures and protocol enhancements for fast identifications in ISO/IEC 18000-6C systems that integrate UWB technology are investigated. The anti-collision protocol is studied by considering various tag populations. A novel algorithm is proposed to adapt the UHF air interface parameters with the use of UWB ranging information. The results show that the proposed algorithm yields up to 25% potential performance improvement compared to the ISO/IEC 18000-6C standard.

  • 5.
    Altayr, Hydar
    et al.
    KTH, Tidigare Institutioner                               , Data- och systemvetenskap, DSV.
    Adis, Michael
    KTH, Tidigare Institutioner                               , Data- och systemvetenskap, DSV.
    Utveckling och design av WiGID2003Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Center for Genomics and Bioinformatics (CGB) is an academic department at Karolinska Institute. Generally stated, the CGB department is committed to the generation and management of genetic information by approaches aiming at elucidating the connection between genes, protein and function.

    WiGID is a genome information database that is available through WAP (Wireless Application Protocol).

    Our version of WiGID is based on WML, PHP and PostgreSQL as a database server.

    One of the changes on the old WiGID application was the creation of a relational database with seven tables and one view, instead of the file that represented the database on the old version. We also changed the script language from python to PHP.

    The search engine ability has been extended with three new search alternatives for a user to choose from. Each choice leads to other, sometimes multiple choices.

    A GUI has been created for the administrator, to be able to insert information into the database.

    The structure of the search engine is primarily for narrowing down the search result on the phone display, thereby making the search efficient.

  • 6.
    Andersson, Andreas
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Spirometri med en smarttelefon: Utveckling av en app för att mäta rotationshastigheten till en spirometerprototyp för smarttelefoner2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Målet med detta examensarbete har varit att utveckla en app med en algoritm för att mäta rotationshastigheten hos en prototyp för en spirometerlösning till en låg kostnad för smart- telefoner. En förstudie har gjorts av smarttelefoners användbarhet för att mäta hälsotillstånd och vilka alternativa lösningar och algoritmer som finns för att mäta rörelsedetektion. I detta arbete har en app med en algoritm utvecklats för att detektera rörelser och mäta rotations- hastigheten hos spirometerprototypens turbin filmad med en smarttelefonkamera. För att metoden ska fungera är det viktigt att rotationshastigheten understiger hälften av kamerans fps (bilder per sekund). Rotationshastigheten hos turbinen måste därför begränsas och det behövs en kamera som klarar minst 120 fps för att fånga rörelserna i prototypens turbin.Arbetet har resulterat i en fungerande algoritm för att bestämma turbinens rotationshastighet. Den utvecklade algoritmen detekterar topparna i en PPG (photoplethysmogram). För att minska beräkningstiden och för att öka noggrannheten analyserar algoritmen färgintensiteten i ett begränsat område, ett s.k. ROI (Region of Interest) i varje bild. Det finns stora möjligheter att använda denna algoritm för att fortsätta utvecklingen av detta alternativa sätt att utföra spirometritester.

  • 7.
    Araujo, Jose
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Sandberg, Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Experimental Validation of a Localization System Based on a Heterogeneous Sensor Network2009Inngår i: ASCC: 2009 7TH ASIAN CONTROL CONFERENCE, NEW YORK: IEEE , 2009, s. 465-470Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The experimental implementation and validation of a localization system based on a heterogeneous sensor network is described. The sensor network consists of ultrasound ranging sensors and web cameras. They are used to localize a mobile robot under sensor communication constraints. Applying a recently proposed sensor fusion algorithm that explicitly takes communication delay and cost into account, it is shown that one can accurately trade off the estimation performance by using low-quality ultrasound sensors with low processing time and low communication cost versus the use of the high-quality cameras with longer processing time and higher communication cost. It is shown that a periodic schedule of the sensors is suitable in many cases. The experimental setup is discussed in detail and experimental results are presented.

  • 8.
    Araya, Cristian
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Singh, Manjinder
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Web API protocol and security analysis2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    There is problem that every company has its own customer portal. This problem can be solved by creating a platform that gathers all customers’ portals in one place. For such platform, it is required a web API protocol that is fast, secure and has capacity for many users. Consequently, a survey of various web API protocols has been made by testing their performance and security.

    The task was to find out which web API protocol offered high security as well as high performance in terms of response time both at low and high load. This included an investigation of previous work to find out if certain protocols could be ruled out. During the work, the platform’s backend was also developed, which needed to implement chosen web API protocols that would later be tested. The performed tests measured the APIs’ connection time and their response time with and without load. The results were analyzed and showed that the protocols had both pros and cons. Finally, a protocol was chosen that was suitable for the platform because it offered high security and fast connection. In addition, the server was not affected negatively by the number of connections. Reactive REST was the web API protocol chosen for this platform.

  • 9.
    Arrospide Echegaray, Daniel
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Utvärdering av Självstyrandes-utvecklarramverket2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Inom mjukvaruteknik finns en mångfald processmetoder där var och en har ett specifikt syfte. En processmetod kan enklare beskrivas som en upprepningsbar uppsättning delsteg i syfte att utföra en uppgift och uppnå ett specifikt resultat. Majoriteten av processmetoder som har hittats i denna studie inriktar sig på den mjukvaruprodukt som är att utveckla. Det verkar finnas en brist på processmetoder som kan användas av mjukvaruutvecklare för att utveckla sin personliga utvecklingsprocess. Med personlig utvecklingsprocess menas, hur den enskilda utvecklaren väljer att strukturera det egna arbetet i syfte att uppnå ett visst re- sultat.

    Självstyrandes-utvecklarramverket (även kallad SGD-ramverket) är i skrivande stund ett nyligen utvecklat processramverk med syfte att bistå den individuella utvecklaren att ut- veckla sin personliga utvecklingsprocess. Kort beskrivet är ramverket tänkt att innehålla alla aktiviteter som kan komma att uppstå i ett utvecklingsprojekt. Problemet är att detta ramverk inte har utvärderats ännu och därför vet man inte om ramverket är relevant för att uppfylla sitt syfte. För att rama in och vägleda studien formulerades ett antal problemfråge- ställningar (1) Är ramverket fullständigt för ett mindre företag med avseende på aktivite- ter?, (2) Hur hög är kostnaden för SGD-ramverket i form av tid?

    Målet med studien är att bidra till framtida studier för ramverket genom att utföra en akt- ionsstudie där SGD-ramverket utvärderas utefter ett par specifika utvärderingskriterier.

    En induktiv kvalitativ forskningsmetod användes för att genomföra denna studie. Med in- duktiv metod menas att slutsatser dras utifrån empiriskt insamlad data och utifrån dessa ut- formas generella teorier. Mer specifikt användes metoden aktionsstudie. Data samlades in genom loggning och tidsloggning under aktionsstudiens gång. För att utvärdera ramverket användes utvärderingskriterierna (1) Fullständighet, (2) Semantisk korrekthet (3) Kostnad. En narrativ analys fördes över insamlad data för dessa kriterier med hänsyn till problemfrå- geställningarna.

    Resultat från utvärdering visade att ramverket inte ansågs fullständigt med hänsyn till dess aktiviteter. Dock näst intill fullständigt då enbart ett fåtal aktiviteter behövdes tilläggas i den utförda aktionsstudien. Totalt 3 extra aktiviteter lades till utöver de 40 som redan finns. Ca tio procent av den totala arbetstiden i aktionsstudien var i tillagda aktiviteter utanför Självstyrandes-Utvecklarramverkets ordinarie aktiviteter. Ramverkets aktiviteter ansågs även vara för granulärt formulerade i sammanhanget av ett mindre företag. Ramverket an- sågs vara högst relevant för att förbättra den individuella utvecklarens egna process. Kost- nad för införsel av Självstyrandes-Utvecklarramverket i denna studie speglar tiden det tog tills tidsanvändningen av Ramverket ansågs stabilt. Denna införelsekostnad uppskattades i form av tid och bestod av ca 3.54% av en åttatimmars arbetsdag, detta uppskattade ske un- der en införselsperiod på 24 dagar. Total tillämpningskostnad för användning av ramverket i den utförda aktionsstudien är i snitt 4,143 SEK/timme alternativt 662,88 SEK/månad. Schablonkostnaden som har använts ligger på 172,625 SEK/timme. 

  • 10.
    Aslamy, Benjamin
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Utveckling av ett multisensorsystem för falldetekteringsanordningar2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Fallolyckor bland äldre är ett stort folkhälsoproblem. Således har det utvecklats en rad olika system för fjärrövervakning av äldre för att möjliggöra en tidig detekte- ring av fallolyckor. Majoriteten av de forskningar som hittills har gjorts inom fallo- lyckor har fokuserat på att utveckla nya mer framgångsrika algoritmer just för att identifiera fall från icke-fall. Trots det visar statistiken att dödsfall och skador orsa- kade av fallolyckor ökar för varje år i samband med den ökande andel äldre perso- ner i befolkningen.

    Detta examensarbete handlar om att förbättra nuvarande falldetekteringsanord- ningar genom att täcka de brister och tillgodose de behov som finns i nuvarande tekniker. De förbättringar som har kartlagts är att kunna ge en säkrare bedömning av patientens hälsa och kunna påkalla snabbare hjälpinsats när en fallolycka har inträffat. En annan förbättring är rörelsefriheten för äldre. De ska kunna befinna sig utomhus och ha möjlighet att utföra sina dagliga aktiviteter utan att vara be- gränsade av platspositionen.

    Sammanfattningsvis kan det konstateras att ett multisensorsystem i form av en prototyp har konstruerats för att täcka de brister som har kartlagts. Utöver att pro- totypen detekterar fall och kroppsrörelser med hjälp av en accelerometersensor innehåller den även en sensor för detektering av livstecken i from av EKG. Den in- nehåller dessutom cellulära och trådlösa nätverksanslutningar i form av GPRS och Wi-Fi för att möjliggöra rörelsefriheten hos äldre. Vidare innehåller prototypen en sensor för GPS som ger information om platsposition. 

  • 11.
    Aurell, Erik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    El-Ansary, Sameh
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    A physics-style approach to scalability of distributed systems2005Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 3267, s. 266-272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Is it possible to treat large scale distributed systems as physical systems? The importance of that question stems from the fact that the behavior of many P2P systems is very complex to analyze analytically, and simulation of scales of interest can be prohibitive. In Physics, however, one is accustomed to reasoning about large systems. The limit of very large systems may actually simplify the analysis. As a first example, we here analyze the effect of the density of populated nodes in an identifier space in a P2P system. We show that while the average path length is approximately given by a function of the number of populated nodes, there is a systematic effect which depends on the density. In other words, the dependence is both on the number of address nodes and the number of populated nodes, but only through their ratio. Interestingly, this effect is negative for finite densities, showing that an amount of randomness somewhat shortens average path length.

  • 12.
    Axtelius, Mathias
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Alsawadi, Rami
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    An improved selection algorithm for access points in wireless local area networks: An improved selection algorithm for wireless iopsys devices2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Wireless devices search for access points when they want to connect to a network. A devicechooses an access point based on the received signal strength between the device and theaccess point. That method is good for staying connected in a local area network but it doesnot always offer the best performance, which can result in a slower connection. This is thestandard method of connection for wireless clients, which will be referred to as the standardprotocol. Larger networks commonly have a lot of access points in an area, which increasesthe coverage area and makes loss of signal a rare occurrence. Overlapping coverage zonesare also common, offering multiple choices for a client. The company Inteno wanted an alternativeconnection method for their gateways. The new method that was developed wouldforce the client to connect to an access point depending on the bitrate to the master, as wellas the received signal strength. These factors are affected by many different parameters.These parameters were noise, signal strength, link-rate, bandwidth usage and connectiontype. A new metric had to be introduced to make the decision process easier by unifying theavailable parameters. The new metric that was introduced is called score. A score system wascreated based on these metrics. The best suited access point would be the one with the highestscore. The developed protocol chose the gateway with the highest bitrate available, while thestandard protocol would invariably pick the closest gateway regardless. The developed protocolcould have been integrated to the standard protocol to gain the benefits of both. Thiscould not be accomplished since the information was not easily accessible on Inteno’s gatewaysand had to be neglected in this thesis.

  • 13. Ben Dhaou, I.
    et al.
    Tenhunen, Hannu
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Efficient library characterization for high-level power estimation2004Inngår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 12, nr 6, s. 657-661Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes LP-DSM, which is an algorithm used for efficient library characterization in high-level power estimation. LP-DSM characterizes the power consumption of building blocks using the entropy of primary inputs and primary outputs. The experimental results showed that over a wide range of benchmark circuits implemented using full custom design in 0.35-mum 3.3 V CMOS process the statistical performance (mean and maximum error) of LP-DSM is comparable or sometimes better than most of the published algorithms. Moreover, it was found that LP-DSM has the lowest prediction sum of squares, which makes it an efficient tool for power prediction. Furthermore, the complexity of the LP-DSM is linear in relation to the number of primary inputs (O(NI)), whereas state of the art published library characterization algorithms have a complexity of O(NI2).

  • 14.
    Bhuddi, Amita
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Somos, Oliver
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Återställningsverktyg för fordon baserat på applikationsintegration2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Mjukvarutestningsgruppen på Scania använder en manuell och tidskrävande process för att återställa testfordon efter sina utförda arbeten. I den återställningsprocessen ingår ett antal olika applikationer för att kunna säkerställa att fordonet är i samma skick som det var innan testerna. För att förbättra arbetsflödet med minskad arbetsbelastning och att försäkra en säkrare process var de intresserade av att utveckla ett återställningsverktyg som kan göra detta uppdrag. Önskemålet var att skapa detta genom att återanvända så mycket av de redan tillgängliga komponenterna som möjligt. Då det fanns flera komponenter som uppfyllde funktionskraven för de flesta funktionaliteten krävdes det en undersökning för att avgöra vilka ska användas. Denna gjordes med hjälp av integrationsmodellen Enterprise Application Integration, där målet är att utveckla en slutprodukt av applikationerna som används inom en organisation för att förenkla bland annat underhåll, datahantering och utbildning av medarbetarna. En prototyp har tagits fram som implementerar tre existerande moduler på olika nivåer och som enligt målet med EAI själv är en enkel mjukvara som möjliggör att komponenterna tillsammans utför arbetet.

  • 15.
    Bilardi, Gianfranco
    et al.
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Scquizzato, Michele
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teoretisk datalogi, TCS. Univ Padua, Padua, Italy.
    Silvestri, Francesco
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    A Lower Bound Technique for Communication in BSP2018Inngår i: ACM TRANSACTIONS ON PARALLEL COMPUTING, ISSN 2329-4949, Vol. 4, nr 3, artikkel-id UNSP 14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Communication is a major factor determining the performance of algorithms on current computing systems; it is therefore valuable to provide tight lower bounds on the communication complexity of computations. This article presents a lower bound technique for the communication complexity in the bulk-synchronous parallel (BSP) model of a given class of DAG computations. The derived bound is expressed in terms of the switching potential of a DAG, that is, the number of permutations that the DAG can realize when viewed as a switching network. The proposed technique yields tight lower bounds for the fast Fourier transform (FFT), and for any sorting and permutation network. A stronger bound is also derived for the periodic balanced sorting network, by applying this technique to suitable subnetworks. Finally, we demonstrate that the switching potential captures communication requirements even in computational models different from BSP, such as the I/O model and the LPRAM.

  • 16.
    Blanco Paananen, Adrian
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Storby, Johan
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Observing coevolution in simulated bacteria: Using asexual reproduction and simple direct mapped functions for decision-making2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this report we have presented the results of a program which performs simula- tions of artificial bacteria with the ability to evolve different characteristics and behaviours through genetic algorithms. Over time unfit bacteria will die out, and the more fit bacteria will produce offspring with slightly mutated variants of it’s genetic code resembling the evolutionary process. The simulation does not follow the traditional macro-scale hand-picked sexual reproduction often used in genetic algorithms to produce optimal results, but it instead uses individ- ual asexual reproduction which more closely resembles how bacteria reproduce in nature. Furthermore we do not use traditional neural networks for decision making, but simple functions which directly map the bacterias inputs to their decisions.

    The purpose of this study was to observe whether bacteria with different initial starting populations would coevolve, and specialize into heterogeneous populations. Furthermore we have tried to analyze how the populations inter- act with each other and how changing the different parameters of the simulation would affect the populations. We have performed three separate experiments that differ in their initial conditions, one with pre-created and heterogeneous herbivores and carnivores, one with homogeneous omnivores, and one with bac- teria whose genetic values have been decided at random. The result of our experiments was that we observed coevolution in the bacteria, and that they would despite very different initial starting conditions always grow towards sta- ble heterogeneous populations with very few exceptions. 

  • 17.
    Blom, Marcus
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Hammar, Kim
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Integrating Monitoring Systems - Pre-Study2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Failures in networks that reside in business environments cause harm to organizations depending on them. Every minute of inoperativety is hurtful and as a network adminstrator you want to minimize the rates of failures as well as the time of inoperation. Therefore, a fruitful network monitoring system is of great interest for such organizations. This bachelor’s thesis is the outcome of a pre-study performed on behalf of MIC Nordic and sought to advice them in the implementation of a new monitoring system.

    The aim of this study was to investigate how a Network Operation Center (NOC) can be implemented in an existing monitoring environment, to integrate current monitoring systems to a central point for monitoring. This study takes an holitstic approach to network management and the research can be divided into two main categories: Communication between network components and Presentation of information. Our process involves an analysis of the environment of MIC Nordic and an in depth inquiry on the current state of network monitoring and interface design. The study then culminates in the implementation of a prototype. The prototype serves in first hand as a research tool to collect experience and empirical evidence to increase the crediblity of our conclusions. It is also an attempt of demonstrating the complete process behind developing a NOC, that we believe can fill a gap among the previous research in the field.

    From our results you can expect a prototype with functionality for monitoring network components and a graphical user interface (GUI) for displaying information. The results are designed towards solving the specific network management problem that was given and the environment that it concerns. This pre-study suggests that the best solution for implementing a NOC in the given environment is to use SNMP for communication. From an investigation on how to present network management information in a effective way we propose to follow a user-centered approach and to utilize human perception theory in the design process. The authors recommend further research that maintain the holistic approach but applies more quantitative methods to broaden the scope.

  • 18. Bonnichsen, L.
    et al.
    Podobas, Artur
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Using transactional memory to avoid blocking in OpenMP synchronization directives: Don’t wait, speculate!2015Inngår i: 11th International Workshop on OpenMP, IWOMP 2015, Springer, 2015, s. 149-161Konferansepaper (Fagfellevurdert)
    Abstract [en]

    OpenMP applications with abundant parallelism are often characterized by their high-performance. Unfortunately, OpenMP applications with a lot of synchronization or serialization-points perform poorly because of blocking, i.e. the threads have to wait for each other. In this paper, we present methods based on hardware transactional memory (HTM) for executing OpenMP barrier, critical, and taskwait directives without blocking. Although HTM is still relatively new in the Intel and IBM architectures, we experimentally show a 73% performance improvement over traditional locking approaches, and 23% better than other HTM approaches on critical sections. Speculation over barriers can decrease execution time by up-to 41 %. We expect that future systems with HTM support and more cores will have a greater benefit from our approach as they are more likely to block.

  • 19.
    Braun, Stefan
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Wafer-level heterogeneous integration of MEMS actuators2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents methods for the wafer-level integration of shape memory alloy (SMA) and electrostatic actuators to functionalize MEMS devices. The integration methods are based on heterogeneous integration, which is the integration of different materials and technologies. Background information about the actuators and the integration method is provided.

    SMA microactuators offer the highest work density of all MEMS actuators, however, they are not yet a standard MEMS material, partially due to the lack of proper wafer-level integration methods. This thesis presents methods for the wafer-level heterogeneous integration of bulk SMA sheets and wires with silicon microstructures. First concepts and experiments are presented for integrating SMA actuators with knife gate microvalves, which are introduced in this thesis. These microvalves feature a gate moving out-of-plane to regulate a gas flow and first measurements indicate outstanding pneumatic performance in relation to the consumed silicon footprint area. This part of the work also includes a novel technique for the footprint and thickness independent selective release of Au-Si eutectically bonded microstructures based on localized electrochemical etching.

    Electrostatic actuators are presented to functionalize MEMS crossbar switches, which are intended for the automated reconfiguration of copper-wire telecommunication networks and must allow to interconnect a number of input lines to a number of output lines in any combination desired. Following the concepts of heterogeneous integration, the device is divided into two parts which are fabricated separately and then assembled. One part contains an array of double-pole single-throw S-shaped actuator MEMS switches. The other part contains a signal line routing network which is interconnected by the switches after assembly of the two parts. The assembly is based on patterned adhesive wafer bonding and results in wafer-level encapsulation of the switch array. During operation, the switches in these arrays must be individually addressable. Instead of controlling each element with individual control lines, this thesis investigates a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in the array with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators.

  • 20.
    Brejcha, Kevin
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Prestandaanalys av HTTP/22015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Swedbank är en av Sveriges största företag inom finanssektorn med drygt fyra miljoner privatkunder och försöker ständigt utveckla sina tjänster så att de är lättåtkomliga och lättanvända för kunderna. För att tillfredsställa sina kunders behov av en snabb och lättåtkomlig bank så vill Swedbank minska på laddningstiderna till sina finanstjänster, särskilt de mobila tjänsterna då det är där uppkopplingarna är som långsammast. Uppdraget var att göra en prestandaanalys av HTTP/2 som är den senaste versionen av HTTP-protokollet. Efter att ha genomfört arbetet ska Swedbank veta vad dem kan anpassa för att göra sina tjänster så optimala som möjligt för framtiden.Resultatet visade att med hjälp av HTTP/2’s nya funktioner, bland annat det binära ramlagret, uppnåddes en prestandaökning på 44% av totala laddningstiden på Swedbank’s hemsida. Testerna genomfördes i en lokal labbmiljö där de olika HTTP versionerna installerades och mätvärden dokumenterades. Detta ansågs som ett bra resultat utan att ha genomfört någon fördjupande konfiguration.

  • 21.
    Brink, Pontus
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Rinnarv, Jonathan
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Machine learning - neuroevolution for designing chip circuits/pathfinding2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Neural Networks have been applied in numeral broad categories of work. Such as classification, data processing, robotics, systemcontrol e.t.c. This thesis compares using traditional methods of the routing process in chip circuit design to using a Neural Network trained with evolution. Constructing and evaluating a chip design is a complicated thing, where a lot of variables have to be accounted for and therefore a simplified evaluation and design process is used in order to train the network and compare the results. This was done by constructing simple test cases and running the algorithms BFS, A*Star and the neural network and comparing the paths each algorithm found using a fitness function. The results were that BFS and A*Star both performed better on complex circuits, but the neural network was able to create better paths on very small and niche circuits. The conclusion of the study is that the neural network approach is not able to compete with the standard industry methods of the routing process, but we do not exclude the possibility that with a better designed Fitness function, this could be possible.

  • 22.
    Brorsson, Mats
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Collin, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Adaptive and flexible dictionary code compression for embedded applications2006Inngår i: Proceedings of the 2006 international conference on Compilers, architecture and synthesis for embedded systems, 2006, s. 113-124Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dictionary code compression is a technique where long instructions in the memory are replaced with shorter code words used as index in a table to look up the original instructions. We present a new view of dictionary code compression for moderately high-performance processors for embedded applications. Previous work with dictionary code compression has shown decent performance and energy savings results which we verify with our own measurement that are more thorough than previously published. We also augment previous work with a more thorough analysis on the effects of cache and line size changes. In addition, we introduce the concept of aggregated profiling to allow for two or more programs to share the same dictionary contents. Finally, we also introduce dynamic dictionaries where the dictionary contents is considered to be part of the context of a process and show that the performance overhead of reloading the dictionary contents on a context switch is negligible while on the same time we can save considerable energy with a more specialized dictionary contents.

  • 23.
    Bruse, Andreas
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Exploiting Cloud Resources For Semantic Scene Understanding On Mobile Robots2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Modern day mobile robots are constrained in the resources available to them. Only so much hardware can be fit onto the robotic frame and at the same time they are required to perform tasks that require lots of computational resources, access to massive amounts of data and the ability to share knowledge with other robots around it.

    This thesis explores the cloud robotics approach in which complex compu- tations can be offloaded to a cloud service which can have a huge amount of computational resources and access to massive data sets. The Robot Operat- ing System, ROS, is extended to allow the robot to communicate with a high powered cluster and this system is used to test our approach on such a complex task as semantic scene understanding. The benefits of the cloud approach is utilized to connect to a cloud based object detection system and to build a cat- egorization system relying on large scale datasets and a parallel computation model. Finally a method is proposed for building a consistent scene description by exploiting semantic relationships between objects.

  • 24.
    Burghout, Wilco
    KTH, Tidigare Institutioner                               , Infrastruktur.
    Hybrid microscopic-mesoscopic traffic simulation2004Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Traffic simulation is an important tool for modelling the operations of dynamic traffic systems and helps analyse the causes and potential solutions of traffic problems such as congestion and traffic safety. Microscopic simulation models provide a detailed representation of the traffic process, which makes them most suitable for evaluation of complicated traffic facilities and Intelligent Transportation Systems that often consist of complex traffic management, safety and information systems. Macroscopic and mesoscopic models on the other hand, capture traffic dynamics in lesser detail, but are faster and easier to apply and calibrate than microscopic models. Therefore they are most suitable for modelling large networks, while microscopic models are usually applied to smaller areas.

    The objective of this thesis is to combine the strengths of both modelling approaches and diminish their individual weaknesses by constructing a hybrid mesoscopic-microscopic model that applies microscopic simulation to areas of specific interest, while simulating a surrounding network in lesser detail with a mesoscopic model.

    Earlier attempts at hybrid modelling have concentrated on integrating macroscopic and microscopic models and have proved difficult due to the large difference between the continuous-flow representation of traffic in macroscopic models and the detailed vehicle-and driver-behaviour represented in microscopic models. These problems are solved in this thesis by developing a mesoscopic vehicle-based and event-based model that avoids the (dis)aggregation problems of traffic flows at the inter-model boundaries. In addition, this thesis focuses on the general problems of consistency across the entire hybrid model.

    The requirements are identified that are important for a hybrid model to be consistent across the models at different levels of detail. These requirements vary from network and route-choice consistency to consistency of traffic dynamics across the boundaries of the micro- and mesoscopic submodels. An integration framework is proposed that satisfies these requirements. This integration framework has been implemented in a prototype hybrid model, MiMe, which is used to demonstrate the correctness of the solutions to the various integration issues. The hybrid model integrates MITSIMLab, a microscopic traffic simulation model, and Mezzo, the newly developed mesoscopic model. Both the hybrid model and the new Mezzo model are applied in a number of case studies, including a network in the North of Stockholm, which show their validity and applicability. The results are promising and support both the proposed integration architecture and the importance of integrating microscopic and mesoscopic models.

  • 25. Calandriello, Giorgio
    et al.
    Papadimitratos, Panos
    Hubaux, Jean-Pierre
    Lioy, Antonio
    Efficient and Robust Pseudonymous Authentication in VANET2007Inngår i: VANET'07: PROCEEDINGS OF THE FOURTH ACM INTERNATIONAL WORKSHOP ON VEHICULAR AD HOC NETWORKS, 2007, s. 19-27Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Effective and robust operations, as well as security and privacy are critical for the deployment of vehicular ad hoc networks (VANETs). Efficient and easy-to-manage security and privacy-enhancing mechanisms axe essential for the wide-spread adoption of the VANET technology. In this paper, we are concerned with this problem; and in particular, how to achieve efficient and robust pseudonym-based authentication. We design mechanisms that reduce the security overhead for safety beaconing, and retain robustness for transportation safety, even in adverse network settings. Moreover, we show how to enhance the availability and usability of privacy-enhancing VANET mechanisms: Our proposal enables vehicle on-board units to generate their own pseudonyms, without affecting the system security.

  • 26.
    Carlzon, Malin
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    BGP oscillations when peering with loopback addresses2006Inngår i: 20th International Conference on Advanced Information Networking and Applications, Vol 2, Proceedings / [ed] Martin DC, LOS ALAMITOS, USA: IEEE COMPUTER SOC , 2006, s. 712-716Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An oscillating routing protocol will result in increased protocol activity and may lead to increased router CPU activity and memory consumption.  This case study shows that BGP peering using loopback addresses when peering EBGP between two dualhomed ASes will cause BGP to oscillate. It includes a detailed lab report in which several possible setups that will cause BGP to oscillate are presented. It also includes an oscillation event from one of the world's largest production networks that was caused by such a setup.

  • 27.
    Carlzon, Malin
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Improving BGP convergence properties and web content blocking using BGP2006Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 28.
    Carlzon, Malin
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Perceived problems with BGP: a survey2006Rapport (Annet vitenskapelig)
  • 29.
    Carlzon, Malin
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Resetting a damped out route in BGP2006Rapport (Annet vitenskapelig)
  • 30.
    Carlzon, Malin
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Hagsand, Olof
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Widell, Fredrik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Danielsson, Björn
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Blocking web contents using BGP: measurements and observations2006Rapport (Annet vitenskapelig)
  • 31. Casoni, E.
    et al.
    Jerusalem, A.
    Samaniego, C.
    Eguzkitza, B.
    Lafortune, P.
    Tjahjanto, Denny
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). IMDEA Materials Institute, Spain .
    Saez, X.
    Houzeaux, G.
    Vazquez, M.
    Alya: Computational Solid Mechanics for Supercomputers2015Inngår i: Archives of Computational Methods in Engineering, ISSN 1134-3060, E-ISSN 1886-1784, Vol. 22, nr 4, s. 557-576Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    While solid mechanics codes are now conventional tools both in industry and research, the increasingly more exigent requirements of both sectors are fuelling the need for more computational power and more advanced algorithms. For obvious reasons, commercial codes are lagging behind academic codes often dedicated either to the implementation of one new technique, or the upscaling of current conventional codes to tackle massively large scale computational problems. Only in a few cases, both approaches have been followed simultaneously. In this article, a solid mechanics simulation strategy for parallel supercomputers based on a hybrid approach is presented. Hybrid parallelization exploits the thread-level parallelism of multicore architectures, combining MPI tasks with OpenMP threads. This paper describes the proposed strategy, programmed in Alya, a parallel multi-physics code. Hybrid parallelization is specially well suited for the current trend of supercomputers, namely large clusters of multicores. The strategy is assessed through transient non-linear solid mechanics problems, both for explicit and implicit schemes, running on thousands of cores. In order to demonstrate the flexibility of the proposed strategy under advance algorithmic evolution of computational mechanics, a non-local parallel overset meshes method (Chimera-like) is implemented and the conservation of the scalability is demonstrated.

  • 32.
    Chabloz, Jean-Michel
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Hemani, Ahmed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Lowering the Latency of Interfaces for Rationally-Related Frequencies2010Inngår i: 2010 IEEE INTERNATIONAL CONFERENCE ON COMPUTER DESIGN, 2010, s. 23-30Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have introduced the Globally-Ratiochronous, Locally-Synchronous (GRLS) design paradigm, a design style based on rationally-related frequencies, with the objective to overcome the limitations of traditional multi-frequency systems by providing a flexibility close that of Globally-Asynchronous, Locally-Synchronous (GALS) systems but introducing performance penalties and overheads close to those of mesochronous systems. In this paper we focus on performances and improve the latency figures of our original GRLS interfaces by introducing two new interfaces, called GRLS-F and GRLS-noF, the first suitable for blocks with long computation time and the second for blocks with short computation time. The latency figures of the original GRLS interfaces are improved up to 50% without increasing complexity. The average latency figures of the resulting interfaces are lower than 1 Receiver clock cycle, the latency of a synchronous interface.

  • 33.
    Chahine, Sandy
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Chowdhury, Selma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    RTOS med 1.5K RAM?2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Internet of Things (IoT) blir allt vanligare i dagens samhälle. Allt fler vardagsenheter blir uppkopplade mot det trådlösa nätet. För det krävs kostnadseffektiv datorkraft vilket medför att det kan vara gynnsamt att undersöka mikrokontroller och hur de skulle klara av detta arbete. Dessa kan ses som mindre kompakta datorer vilka trots sin storlek erbjuder en hel del prestanda. Denna studie avser att underrätta om något befintligt operativsystem kan fungera ihop med mikrokontrollern PIC18F452 samt hur många processer som kan köras parallellt givet MCU:ns begränsade minne.

    Olika metodval undersöktes och diskuterades för att avgöra vilken metod som skulle generera bäst resultat. En undersökning och flera experiment genomfördes för att kunna besvara dessa frågor. Experimenten krävde att en speciell utvecklingsmiljö installerades och att den generiska FreeRTOS distributionen porterades till både rätt processor och experimentkort. Porteringen lyckades och experimenten visade att frågeställningen kunde besvaras med ett ja - det går att köra ett realtidsoperativsystem på en MCU med enbart 1,5 kB RAM-minne.

    Under arbetets gång konstaterade också projektet att Amazon byggt sin IoTsatsning på FreeRTOS. De hade dock satsat på en mer kraftfull MCU. Satsningen ville därmed framhålla det som en mer framtidssäker inriktning.

  • 34.
    Chavez Alcarraz, Erick
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Moraga, Manuel
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Linked data performance in different databases: Comparison between SQL and NoSQL databases2014Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Meepo AB was investigating the possibility of developing a social rating and recommendation service. In a recommendation service, the user ratings are collected in a database, this data is then used in recommendation algorithms to create individual user recommendations.

    The purpose of this study was to find out which  demands are put on a DBMS, database management system, powering a recommendation service, what impact the NoSQL databases have on the performance of recommendation services compared to traditional relational databases, and which DBMS is most suited for storing the data needed to host a recommendation service.

    Five distinct NoSQL and Relational DBMS were examined, from these three candidates were chosen for a closer comparison.

    Following a study of recommendation algorithms and services, a test suite was created to compare DBMS performance in different areas using a data set of 100 million ratings.

    The results show that MongoDB had the best performance in most use cases, while Neo4j and MySQL struggled with queries spanning the whole data set.

    This paper however never compared performance for real production code. To get a better comparison, more research is needed. We recommend new performance tests for MongoDB and Neo4j using implementations of recommendation algorithms, a larger data set, and more powerful hardware.

  • 35.
    Chen, Guang
    et al.
    Tongji Univ, Coll Automot Engn, Shanghai, Peoples R China.;Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Cao, Hu
    Hunan Univ, State Key Lab Adv Design & Mfg Vehicle Body, Changsha, Hunan, Peoples R China..
    Aafaque, Muhammad
    Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Chen, Jieneng
    Tongji Univ, Coll Elect & Informat Engn, Shanghai, Peoples R China..
    Ye, Canbo
    Tongji Univ, Coll Automot Engn, Shanghai, Peoples R China..
    Roehrbein, Florian
    Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Conradt, Jörg
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Chen, Kai
    Tongji Univ, Coll Automot Engn, Shanghai, Peoples R China..
    Bing, Zhenshan
    Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Liu, Xingbo
    Tongji Univ, Coll Automot Engn, Shanghai, Peoples R China..
    Hinz, Gereon
    Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Stechele, Walter
    Tech Univ Munich, Integrated Syst, Munich, Germany..
    Knoll, Alois
    Tech Univ Munich, Robot & Embedded Syst, Munich, Germany..
    Neuromorphic Vision Based Multivehicle Detection and Tracking for Intelligent Transportation System2018Inngår i: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, artikkel-id 4815383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neuromorphic vision sensor is a new passive sensing modality and a frameless sensor with a number of advantages over traditional cameras. Instead of wastefully sending entire images at fixed frame rate, neuromorphic vision sensor only transmits the local pixel-level changes caused by the movement in a scene at the time they occur. This results in advantageous characteristics, in terms of low energy consumption, high dynamic range, sparse event stream, and low response latency, which can be very useful in intelligent perception systems for modern intelligent transportation system (ITS) that requires efficient wireless data communication and low power embedded computing resources. In this paper, we propose the first neuromorphic vision based multivehicle detection and tracking system in ITS. The performance of the system is evaluated with a dataset recorded by a neuromorphic vision sensor mounted on a highway bridge. We performed a preliminary multivehicle tracking-by-clustering study using three classical clustering approaches and four tracking approaches. Our experiment results indicate that, by making full use of the low latency and sparse event stream, we could easily integrate an online tracking-by-clustering system running at a high frame rate, which far exceeds the real-time capabilities of traditional frame-based cameras. If the accuracy is prioritized, the tracking task can also be performed robustly at a relatively high rate with different combinations of algorithms. We also provide our dataset and evaluation approaches serving as the first neuromorphic benchmark in ITS and hopefully can motivate further research on neuromorphic vision sensors for ITS solutions.

  • 36.
    Chen, Xiaowen
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Lu, Zhonghai
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik.
    Liu, S.
    Chen, S.
    Round-trip DRAM access fairness in 3D NoC-based many-core systems2017Inngår i: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 16, nr 5s, artikkel-id 162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In 3D NoC-based many-core systems, DRAM accesses behave differently due to their different communication distances and the latency gap of different DRAM accesses becomes bigger as the network size increases, which leads to unfair DRAM access performance among different nodes. This phenomenon may lead to high latencies for some DRAM accesses that become the performance bottleneck of the system. The paper addresses the DRAM access fairness problem in 3D NoC-based many-core systems by narrowing the latency difference of DRAM accesses as well as reducing the maximum latency. Firstly, the latency of a round-trip DRAM access is modeled and the factors causing DRAM access latency difference are discussed in detail. Secondly, the DRAM access fairness is further quantitatively analyzed through experiments. Thirdly, we propose to predict the network latency of round-trip DRAM accesses and use the predicted round-trip DRAM access time as the basis to prioritize the DRAM accesses in DRAM interfaces so that the DRAM accesses with potential high latencies can be transferred as early and fast as possible, thus achieving fair DRAM access. Experiments with synthetic and application workloads validate that our approach can achieve fair DRAM access and outperform the traditional First-Come-First-Serve (FCFS) scheduling policy and the scheduling policies proposed by reference [7] and [24] in terms of maximum latency, Latency Standard Deviation (LSD)1 and speedup. In the experiments, the maximum improvement of the maximum latency, LSD, and speedup are 12.8%, 6.57%, and 8.3% respectively. Besides, our proposal brings very small extra hardware overhead (<0.6%) in comparison to the three counterparts.

  • 37.
    Chen, Yancang
    et al.
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Xie, Lunguo
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Li, Jinwen
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Shi, Zhu
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Zhang, Minxuan
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Chen, Xiaowen
    Natl Univ Def Technol, Dept Comp, Changsha, Hunan, Peoples R China..
    Lu, Zhonghai
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Elektronik och inbyggda system.
    A Trace-driven Hardware-level Simulator for Design and Verification of Network-on-Chips2010Inngår i: 2011 INTERNATIONAL CONFERENCE ON COMPUTERS, COMMUNICATIONS, CONTROL AND AUTOMATION (CCCA 2011), VOL II / [ed] Thaung, K S, IEEE , 2010, s. 32-35Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Traditional communications of general-purpose multi-core processor and application-specific System-on-Chip face challenges in terms of scalability and complexity. Network-on-Chip (NoC) has been the most promising solution for the communications of multi-core and many-core chips. In this paper, we present a trace-driven hardware-level simulator (noted HS) based on SystemVerilog for the design and verification of NoCs. Different from the state-of-the-art NoC simulators, the HS owns three important characteristics in addition to the capability of creating simulation and synthesizable NoC descriptions: 1) hardware-level simulation can be done, which means more implementation details of hardware than flit-level simulation; 2) router debugging and verification can be done at RTL by inserting assertions and coverage; 3) trace-based application simulations can be done besides synthetic workloads. A 4 X 4 2D mesh NoC with output virtual-channel routers verifies the capability of our HS.

  • 38. Chien, Steven W. D.
    et al.
    Markidis, Stefano
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Sishtla, Chaitanya Prasad
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Santos, Luis
    Herman, Pawel
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    Nrasimhamurthy, Sai
    Laure, Erwin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Parallelldatorcentrum, PDC.
    Characterizing Deep-Learning I/O Workloads in TensorFlow2018Inngår i: Proceedings of PDSW-DISCS 2018: 3rd Joint International Workshop on Parallel Data Storage and Data Intensive Scalable Computing Systems, Held in conjunction with SC 2018: The International Conference for High Performance Computing, Networking, Storage and Analysis, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 54-63Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of Deep-Learning (DL) computing frameworks rely on the rformance of data ingestion and checkpointing. In fact, during the aining, a considerable high number of relatively small files are first aded and pre-processed on CPUs and then moved to accelerator for mputation. In addition, checkpointing and restart operations are rried out to allow DL computing frameworks to restart quickly from a eckpoint. Because of this, I/O affects the performance of DL plications. this work, we characterize the I/O performance and scaling of nsorFlow, an open-source programming framework developed by Google and ecifically designed for solving DL problems. To measure TensorFlow I/O rformance, we first design a micro-benchmark to measure TensorFlow ads, and then use a TensorFlow mini-application based on AlexNet to asure the performance cost of I/O and checkpointing in TensorFlow. To prove the checkpointing performance, we design and implement a burst ffer. find that increasing the number of threads increases TensorFlow ndwidth by a maximum of 2.3 x and 7.8 x on our benchmark environments. e use of the tensorFlow prefetcher results in a complete overlap of mputation on accelerator and input pipeline on CPU eliminating the fective cost of I/O on the overall performance. The use of a burst ffer to checkpoint to a fast small capacity storage and copy ynchronously the checkpoints to a slower large capacity storage sulted in a performance improvement of 2.6x with respect to eckpointing directly to slower storage on our benchmark environment.

  • 39.
    Chivi, Daniel
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Östling Gran, Joakim
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Administration av API-drivna enheter och tjänster för slutanvändare: En fallstudie av API-tjänster2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I dagsläget tenderar många att använda tjänster som hanteras separat. Arbetet undersöker om det är möjligt att sammankoppla ett fåtal tjänster i en gemensam webbapplikation för att underlätta kommunicering mellan tjänsterna samt att förbättra användarvänligheten.

    Företaget A Great Thing har i åtanke att skapa en webbapplikation som tillåter användare att med hjälp av deras applikation skapa agenter som sköter händelser från användarens begäran, exempelvis “spela upp en låt vid en viss tid”.

    Metodiken som tillämpats har dels varit en fallstudie och dels användarbaserade metoder i form av enkätundersökning samt ett användartest. Ytterligare undersöktes hur kommunikationen går mellan tjänsters API, och de nödvändiga parametrar som utbyter data. Slutligen evalueras den framtagna prototypen enligt vissa riktlinjer inom användarvänlighet.

    Examensarbetets resultat är i form av en webbprototyp med fokus på användarvänlighet, implementering av API:er, användartest på faktiska användare samt statistik på efterfrågan av tjänster. Vidare har även en marknadsundersökning utförts för att belysa ekonomiska vinstmöjligheter genom API-distribution.

    Slutsatsen dras att det är möjligt att sammankoppla API:er och dess tjänster för att uppnå ett användarvänligt gränssnitt samt hur nödvändiga parametrar disponeras på ett effektivt vis. Vidare är förhoppningen att utomstående läsare skapar en förståelse om hur sammankopplingen går till på ett strukturerat och informativt tillvägagångssätt. Även hur olika tekniska metoder inom användarvänlighet kan tillämpas vid konstruktion av prototyper. 

  • 40.
    Ciobanu Morogan, Matei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    Security system for ad-hoc wireless networks based on generic secure objects2005Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    As computing devices and wireless connectivity become ubiquitous, new usage scenarios emerge, where wireless communication links between mobile devices are established in an ad-hoc manner. The resulting wireless ad-hoc networks differ from classical computer networks in a number of ways, lack of permanent access to the global network and heterogeneous structure being some of them. Therefore, security services and mechanisms that have been designed for classical computer networks are not always the optimal solution in an ad-hoc network environment.

    The research is focused on analyzing how standard security services that are available in classical networks can be provided in an ad-hoc wireless network environment. The goal is to design a security system optimized for operation in ad-hoc wireless networks that provides the same security services – authentication, access control, data confidentiality and integrity, non-repudiation – currently available in classic wired networks.

    The first part of the thesis is the design and implementation of a security platform based on generic secure objects. The flexible and modular nature of this platform makes it suitable for deployment on devices that form ad-hoc networks – ranging from Java-enabled phones to PDAs and laptops.

    We then investigate the problems that appear when implementing in ad-hoc networks some of the security technologies that are standard building blocks of secure systems in classical computer networks. Two such technologies have been found to present problems, namely the areas of certification and access control. In a series of articles, we have described the problems that appear and devised solutions to them by designing protocols, techniques and extensions to standards that are optimized for usage in the ad-hoc network environment.

    These techniques, together with the functionality provided by the underlying security platform, are used to implement all standard security services – confidentiality, authentication, access control, non repudiation and integrity, allowing to integrate ad-hoc networks into the existing security infrastructure.

  • 41.
    Clemmedsson, Elin
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Industriell Marknadsföring och Entreprenörskap.
    Identifying Pitfalls in Machine Learning Implementation Projects: A Case Study of Four Technology-Intensive Organizations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis undertook the investigation of finding often occurring mistakes and problems that organizations face when conducting machine learning implementation projects. Machine learning is a technology with the strength of providing insights from large amounts of data. This business value generating technology has been defined to be in a stage of inflated expectations which potentially will cause organizations problems when doing implementation projects without previous knowledge. By a literature review and hypothesis formation followed by interviews with a sample group of companies, three conclusions are drawn from the results. First, indications show there is a correlation between an overestimation of the opportunities of machine learning and how much experience an organization has within the area. Second, it is concluded that data related pitfalls, such as not having enough data, low quality of the data, or biased data, are the most severe. Last, it is shown that realizing the value of long-term solutions regarding machine learning projects is difficult, although the ability increases with experience.

  • 42.
    Collin, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Brorsson, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Öberg, Johnny
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    A performance and energy exploration of dictionary code compression architectures2011Inngår i: 2011 International  Green Computing Conference and Workshops (IGCC), IEEE conference proceedings, 2011, s. 1-8Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have made a performance and energy exploration of a previously proposed dictionary code compression mechanism where frequently executed individual instructions and/or sequences are replaced in memory with short code words. Our simulated design shows a dramatically reduced instruction memory access frequency leading to a performance improvement for small instruction cache sizes and to significantly reduced energy consumption in the instruction fetch path. We have evaluated the performance and energy implications of three architectural parameters: branch prediction accuracy, instruction cache size and organization. To asses the complexity of the design we have implemented the critical stages in VHDL.

  • 43. Cornwall, L. A.
    et al.
    Jensen, J.
    Kelsey, D. P.
    Frohner, Á.
    Kouřil, D.
    Bonnassieux, F.
    Nicoud, S.
    Lorentey, K.
    Hahkala, J.
    Silander, M.
    Cecchini, R.
    Ciaschini, V.
    dell'Agnello, L.
    Spataro, F.
    O'Callaghan, D.
    Mulmo, Olle
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Volpato, Gian Luca
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Groep, D.
    Steenbakkers, M.
    Mcnab, A.
    Authentication and authorization mechanisms for multi-domain grid environments2004Inngår i: Journal of Grid Computing, ISSN 1570-7873, E-ISSN 1572-9184, Vol. 2, nr 4, s. 301-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article discusses the authentication and the authorization aspects of security in grid environments spanning multiple administrative domains. Achievements in these areas are presented using the EU DataGrid project as an example implementation. It also gives an outlook on future directions of development.

  • 44. D'Angelo, M.
    et al.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    How to select the OOK detection threshold in wireless ad hoc and sensor networks2009Inngår i: IEEE Vehicular Technology Conference / [ed] 69th IEEE Vehicular Technology Conference Barcelona, SPAIN, APR 26-29, 2009, 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    On-off keying (OOK) is an attractive modulation technique to reduce energy consumption of power-constrained wireless networks. The OOK detection threshold, however, must be carefully selected to minimize the bit error probability (BER). This is a challenging task to accomplish on resource-limited nodes or on networks with high-mobility. In this paper, an efficient algorithm to compute the optimal threshold is proposed. The system scenario considers nodes simultaneously transmitting over same frequencies in Rayleigh-log-normal or Rice-log-normal fading conditions. It is shown that by using the Stirling expansion for the BER, and a log-normal approximation, a quick contraction-mapping can be built to achieve the threshold numerically. The mapping is simple to implement and converges quickly. Numerical simulations verify the validity of the theoretical analysis, and show that the new algorithm performs quite well in scenarios of practical interest.

  • 45. Darrell, T. J.
    et al.
    Yeh, T.
    Tollmar, Konrad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Photo-based mobile deixis system and related techniques2004Patent (Annet (populærvitenskap, debatt, mm))
  • 46. Di Gregorio, S.
    et al.
    Umeton, R.
    Bicocchi, A.
    Evangelisti, A.
    Gonzalez, Meliza Contreras
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Highway traffic model based on cellular automata: Preliminary simulation results with congestion pricing considerations2008Inngår i: Eur. Model. Simul. Symp., EMSS, 2008, s. 665-674Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cellular Automata are a reputable formal support for traffic modelling and simulation. STRATUNA is a Cellular Automata model for simulating the evolution of two/three lane highways. It encodes the wide specification of driver's response to the events in his sight range. Encouraging comparison between simulated events and their corresponding in the reality bring to the specification of a theoretical general model characterized by an increased expression power and a significantly deeper forecasting potential, whose application fields are numerous and varied. Fair results in flow forecasting lead to the implementation of an established cost system in which simulation directly provides cost forecasting in terms of congestion toll.

  • 47.
    Di Marco, Piergiuseppe
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Park, Pan Gun
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    A dynamic energy-efficient protocol for reliable and timely communications for wireless sensor networks in control and automation2009Inngår i: 2009 6th IEEE Annual Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks Workshops, 2009, Vol. SECON Workshops 2009, s. 146-148Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Designing quality of service (QoS) guaranteed communication protocol for wireless sensor networks (WSNs) is essential to exploit the advantages and flexibilities offered by this technology for real-time control and actuation applications. A novel cross-layer protocol that embraces altogether a semirandom routing, MAC, data aggregation, and radio power control for clustered WSNs is presented. The protocol leverages the combination of a randomized and a deterministic approach to ensure robustness over unreliable channels and packet losses. An optimization problem, whose objective function is the network energy consumption, and the constraints are reliability and latency of the packets is modelled and solved to adaptively select the protocol parameters by a simple algorithm. As a relevant contribution, the proposed protocol is completely implemented on a test-bed, and it is compared to existing protocols. Experimental results validate the analysis and show excellent performance in terms of reliability, latency, low node duty cycle, load balancing and dynamic adaptation to the application requirements.

  • 48.
    Di Marco, Piergiuseppe
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Park, Pan Gun
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    TREnD: A timely, reliable, energy-efficient and dynamic wsn protocol for control applications2010Inngår i: IEEE International Conference on Communications, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Control applications over wireless sensor networks (WSNs) require timely, reliable, and energy efficient communications. Cross-layer interaction is an essential design paradigm to exploit the complex interaction among the layers of the protocol stack and reach a maximum efficiency. Such a design approach is challenging because reliability and latency of delivered packets and energy are at odds, and resource constrained nodes support only simple algorithms. In this paper, the TREnD protocol is introduced for control applications over WSNs in industrial environments. It is a cross-layer protocol that embraces efficiently routing algorithm, MAC, data aggregation, duty cycling, and radio power control. The protocol parameters are adapted by an optimization problem, whose objective function is the network energy consumption, and the constraints are the reliability and latency of the packets. TREnD uses a simple algorithm that allows the network to meet the reliability and latency required by the control application while minimizing for energy consumption. TREnD is implemented on a test-bed and compared to some existing protocols. Experimental results show good performance in terms of reliability, latency, low duty cycle, and load balancing for both static and time-varying scenarios.

  • 49.
    Dilén, Erik
    et al.
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Lundmark, Emil
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    En utvärdering av Windows 8 Store applikationer som plattform för VOD-tjänster2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Som en effekt av att Video On Demand (VOD) är på stark tillväxt vill June, som en leverantör av mjukvara för TV-branschen, förvärva kunskaper och utvärdera Windows 8 applikationer som plattform för en VOD-tjänst. June har sedan tidigare en webblösning för VOD och vill nu även jämföra och utvärdera bland annat kunskapskrav, tidsåtgång samt fördelar och nackdelar med en Windows 8 applikation ställt mot denna webblösning.

    Målen med examensarbetet kan delas in i tre delar; en där komplexitet och arbetsinsats vid Windows 8 applikationsutveckling utvärderas, en där verktygen som krävs för att utveckla en VOD-applikation utvärderas och sist att implementera en Windows 8 applikation för VOD.

    En Windows 8 applikation utvecklades och valda lösningsmetoder dokumenterades. Dokumentation och kunskap som förvärvats under utvecklingsfasen stod sedan som grund för de analyserande och utvärderande målen. Resultatet är en Windows 8 applikation som uppfyller de mål som satts upp för programmeringsdelen samt en analys och utvärdering som svarar mot målen för analysdelen. 

    Ämnen som är centrala genom rapporten är Microsoft, WinRT, VOD, Smooth Streaming, PlayReady, Windows 8 applikationsutveckling samt data caching och utveckling av användargränsnitt i Windows 8.

  • 50.
    Ding, Christofer
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Evaluation of Recommender System2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Recommender System (RS) has become one of the most important component for many companies, such as YouTube and Amazon. A recommender system consists of a series of algorithms which predict and recommend products to users. This report covers the selection of many open source recommender system projects, and movie predictions are made using the selected recommender system. Based on the predictions, a comparison was made between precision and an improved precision algorithm.

    The selected RS uses singular value decomposition in the field of collaborative filtering. Based on the recommendation results produced by the RS, the comparison between precision and the improved precision algorithms showed that the result of improved precision is slightly higher than precision in different cutoff values and different dimensions of eigenvalues.

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