Digitala Vetenskapliga Arkivet

Endre søk
Begrens søket
1234567 151 - 200 of 58444
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 151.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    AoI-Optimal Joint Sampling and Updating for Wireless Powered Communication Systems2020Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 69, nr 11, s. 14110-14115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper characterizes the structure of the Age of Information (AoI)-optimal policy in wireless powered communication systems while accounting for the time and energy costs of generating status updates at the source nodes. In particular, for a single source-destination pair in which a radio frequency (RF)-powered source sends status updates about some physical process to a destination node, we minimize the long-term average AoI at the destination node. The problem is modeled as an average cost Markov Decision Process (MDP) in which, the generation times of status updates at the source, the transmissions of status updates from the source to the destination, and the wireless energy transfer (WET) are jointly optimized. After proving the monotonicity property of the value function associated with the MDP, we analytically demonstrate that the AoI-optimal policy has a threshold-based structure w.r.t. the state variables. Our numerical results verify the analytical findings and reveal the impact of state variables on the structure of the AoI-optimal policy. Our results also demonstrate the impact of system design parameters on the optimal achievable average AoI as well as the superiority of our proposed joint sampling and updating policy w.r.t. the generate-at-will policy.

    Fulltekst (pdf)
    fulltext
  • 152.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Online Age-minimal Sampling Policy for RF-powered IoT Networks2019Inngår i: 2019 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we study a real-time Internet of Things (IoT)-enabled monitoring system in which a source node (e.g., IoT device or an aggregator located near a group of IoT devices) is responsible for maintaining the freshness of information status at a destination node by sending update packets. Since it may not always be feasible to replace or recharge batteries in all IoT devices, we consider that the source node is powered by wireless energy transfer (WET) by the destination. For this system setup, we investigate the optimal online sampling policy that minimizes the long-term average Age-of-Information (AoI), referred to as the age-optimal policy. The age-optimal policy determines whether each slot should be allocated for WET or update packet transmission while considering the dynamics of battery level, AoI, and channel state information (CSI). To solve this optimization problem, we model this setup as an average cost Markov Decision Process (MDP). After analytically establishing the monotonicity property of the value function associated with the MDP, the age-optimal policy is proven to be a threshold based policy with respect to each of the system state variables. We extend our analysis to characterize the structural properties of the policy that maximizes average throughput for our system setup, referred to as the throughput-optimal policy. Afterwards, we analytically demonstrate that the structures of the age optimal and throughput-optimal policies are different. We also numerically demonstrate these structures as well as the impact of system design parameters on the optimal achievable average AoI.

  • 153.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Dhillon, Arpreet S.
    Virginia Tech, VA 24061 USA.
    On the Role of Age of Information in the Internet of Things2019Inngår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 57, nr 12, s. 72-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we provide an accessible introduction to the emerging idea of Age of Information (AoI) that quantifies freshness of information and explore its possible role in the efficient design of freshness-aware Internet of Things (IoT). We start by summarizing the concept of AoI and its variants with emphasis on the differences between AoI and other well-known performance metrics in the literature, such as throughput and delay. Building on this, we explore freshness-aware IoT design for a network in which IoT devices sense potentially different physical processes and are supposed to frequently update the status of these processes at a destination node (e.g., a cellular base station). Inspired by recent interest, we also assume that these IoT devices are powered by wireless energy transfer by the destination node. For this setting, we investigate the optimal sampling policy that jointly optimizes wireless energy transfer and scheduling of update packet transmissions from IoT devices with the goal of minimizing long-term weighted sum-AoI. Using this, we characterize the achievable AoI region. We also compare this AoI-optimal policy with the one that maximizes average throughput (throughput-optimal policy), and demonstrate the impact of system state on their structures. Several promising directions for future research are also presented.

    Fulltekst (pdf)
    fulltext
  • 154.
    Abdelmotteleb, Ibtihal
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Designing Electricity Distribution Network Charges for an Efficient Integration of Distributed Energy Resources and Customer Response2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    A significant transformation has been gradually taking place within the energy sector, mainly as a result of energy policies targeting environmental objectives. Consequently, the penetration of Distributed Energy Resources (DERs) has been escalating, including self-generation, demand side management, storage, and electrical vehicles. Although the integration of DERs may create technical challenges in the operation of distribution networks, it may also provide opportunities to more efficiently manage the network and defer network reinforcements. These opportunities and challenges impose the necessity of redesigning distribution network charges to incentivize efficient customer response.

    This PhD thesis focuses on the design of distribution network charges that send correct economic signals and trigger optimal responses within the context of active customers. First, a cost-reflective network charge is proposed that consists of a forward-looking locational component based on the network’s utilization level, which transmits the long-term incremental cost of network upgrades. Then, a residual cost component that recovers the remaining part of the regulated network revenues is proposed. The objective of the proposed network charge is to increase the system’s efficiency by incentivizing efficient short- and long-term customers’ reaction while ensuring network cost recovery. The Thesis presents an optimization model that simulates customers’ response to the proposed network charge in comparison to other traditional network charge designs. The model considers the operational and DER investment decisions that customers take rationally to minimize their total costs.

    Secondly, an evaluation methodology based on the Analytical Hierarchy Process technique is proposed in order to assess and compare different designs of network charges with respect to four attributes: network cost recovery, deferral of network costs, efficient customer response and recognition of side-effects on customers.

    Finally, a framework for Local Flexibility Mechanisms (LFM) is presented, complementing the proposed cost-reflective network charge. It aims to provide distribution-level coordination to mitigate unintended customer responses to network charges, by allowing customers to reveal their preferences and offer their flexibility services. It consists of a short-term LFM that utilizes customers’ flexibility in day-to-day network operation, and a long-term LFM that procures customers’ long-term flexibility to replace partially or fully network investments in network planning.

    Fulltekst (pdf)
    Designing electricity distribution network charges for an efficient integration of distributed energy resources and customer response
  • 155.
    Abd-Elrady, Emad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Harmonic signal modeling based on the Wiener model structure2002Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The estimation of frequencies and corresponding harmonic overtones is a problem of great importance in many situations. Applications can, for example, be found in supervision of electrical power transmission lines, in seismology and in acoustics. Generally, a periodic function with an unknown fundamental frequency in cascade with a parameterized and unknown nonlinear function can be used as a signal model for an arbitrary periodic signal. The main objective of the proposed modeling technique is to estimate the fundamental frequency of the periodic function in addition to the parameters of the nonlinear function.

    The thesis is divided into four parts. In the first part, a general introduction to the harmonic signal modeling problem and different approaches to solve the problem are given. Also, an outline of the thesis and future research topics are introduced.

    In the second part, a previously suggested recursive prediction error method (RPEM) for harmonic signal modeling is studied by numerical examples to explore the ability of the algorithm to converge to the true parameter vector. Also, the algorithm is modified to increase its ability to track the fundamental frequency variations.

    A modified algorithm is introduced in the third part to give the algorithm of the second part a more stable performance. The modifications in the RPEM are obtained by introducing an interval in the nonlinear block with fixed static gain. The modifications that result in the convergence analysis are, however, substantial and allows a complete treatment of the local convergence properties of the algorithm. Moreover, the Cramér–Rao bound (CRB) is derived for the modified algorithm and numerical simulations indicate that the method gives good results especially for moderate signal to noise ratios (SNR).

    In the fourth part, the idea is to give the algorithm of the third part the ability to estimate the driving frequency and the parameters of the nonlinear output function parameterized also in a number of adaptively estimated grid points. Allowing the algorithm to automatically adapt the grid points as well as the parameters of the nonlinear block, reduces the modeling errors and gives the algorithm more freedom to choose the suitable grid points. Numerical simulations indicate that the algorithm converges to the true parameter vector and gives better performance than the fixed grid point technique. Also, the CRB is derived for the adaptive grid point technique.

    Fulltekst (ps)
    fulltext
  • 156.
    Abd-Elrady, Emad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Nonlinear Approaches to Periodic Signal Modeling2005Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Periodic signal modeling plays an important role in different fields. The unifying theme of this thesis is using nonlinear techniques to model periodic signals. The suggested techniques utilize the user pre-knowledge about the signal waveform. This gives these techniques an advantage as compared to others that do not consider such priors.

    The technique of Part I relies on the fact that a sine wave that is passed through a static nonlinear function produces a harmonic spectrum of overtones. Consequently, the estimated signal model can be parameterized as a known periodic function (with unknown frequency) in cascade with an unknown static nonlinearity. The unknown frequency and the parameters of the static nonlinearity are estimated simultaneously using the recursive prediction error method (RPEM). A treatment of the local convergence properties of the RPEM is provided. Also, an adaptive grid point algorithm is introduced to estimate the unknown frequency and the parameters of the static nonlinearity in a number of adaptively estimated grid points. This gives the RPEM more freedom to select the grid points and hence reduces modeling errors.

    Limit cycle oscillations problem are encountered in many applications. Therefore, mathematical modeling of limit cycles becomes an essential topic that helps to better understand and/or to avoid limit cycle oscillations in different fields. In Part II, a second-order nonlinear ODE is used to model the periodic signal as a limit cycle oscillation. The right hand side of the ODE model is parameterized using a polynomial function in the states, and then discretized to allow for the implementation of different identification algorithms. Hence, it is possible to obtain highly accurate models by only estimating a few parameters.

    In Part III, different user aspects for the two nonlinear approaches of the thesis are discussed. Finally, topics for future research are presented.

    Fulltekst (pdf)
    FULLTEXT01
  • 157.
    Abd-Elrady, Emad
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Söderström, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Periodic signal analysis using orbits of nonlinear ODEs based on the Markov estimate2004Konferansepaper (Fagfellevurdert)
  • 158.
    Abd-Elrady, Emad
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Söderström, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Periodic signal modeling based on Liénard's equation2004Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 49, nr 10, s. 1773-1778Artikkel i tidsskrift (Fagfellevurdert)
  • 159.
    Abd-Elrady, Emad
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Söderström, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Periodic signal modeling based on Liénard's equation2003Rapport (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 160.
    Abdelraheem, Mohammed Ahmed
    et al.
    RISE., Swedish ICT, SICS, Security Lab.
    Gehrmann, Christian
    RISE., Swedish ICT, SICS, Security Lab.
    Lindström, Malin
    Blekinge Institute of Technology, Sweden.
    Nordahl, Christian
    Blekinge Institute of Technology, Sweden.
    Executing Boolean Queries on an Encrypted Bitmap Index2016Inngår i: CCSW 2016: Proceedings of the 2016 ACM on Cloud Computing Security Workshop, 2016, s. 11-22Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a simple and efficient searchable symmetric encryption scheme based on a Bitmap index that evaluates Boolean queries. Our scheme provides a practical solution in settings where communications and computations are very constrained as it offers a suitable trade-off between privacy and performance.

  • 161.
    Abdelrahman, Ahmed
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad.
    Detection and Extraction of Sky Regions in Digital Images based on Color Classification2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In many applications of image processing there is a need to extract the solid background which it is usually sky for outdoor images. In our application we present this solution. We developed an automatic algorithm for detection and extraction of sky regions in the color image based on color classification. In which the input image should be in the RGB color space and the blue color is detected and classified. Then the color image is transformed to the binary form and the connected regions are extracted separately. The connected regions are then sorted in a descending order according to the biggest area and the biggest region is identified. Then we merged all objects that have similar sky properties. Experimental results showed that our proposed algorithm can produce good results compared to other existing algorithms.

    Fulltekst (pdf)
    Sky_Regions_Extraction
  • 162.
    Abdelsamad, Deena
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Video Transmission Jerkiness Measure2013Independent thesis Basic level (degree of Bachelor)Oppgave
    Abstract [en]

    Digital video transmission is widely used nowadays in multimedia. Frame dropping, freeze and reduced number of frames in the transmitted video are common symptoms of bad transmission quality. In order to assess the quality of transmission, a criterion is introduced in a model for a no reference video jerkiness measure [3]. This model is dierent from the former models presented as it depends on viewing conditions and video resolutions, so it is applicable for any frame size from QCIF to HD. The model uses simple mathematical equations of jerkiness and can be used for any video sequence [3]. A model of reduced reference method (Qtransmission) which depends on a pre-measured Jerkiness is introduced as a suggestion of future work.

    Fulltekst (pdf)
    FULLTEXT01
  • 163.
    Abdi, Abdurazak
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Omar, Hassan
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Undersökning av två faktorer autentiseringsmöjligheter för inloggning till Linux-server samt Microsoft-Azure MFA2023Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Två-faktorautentisering är en tvåstegsverifieringsprocess som syftar till att ge ytterligare säkerhetsnivå genom att kräva att användaren verifierar sig med hjälp av en sekundär metod,för att säkerställa att personer som försöker få tillgång till ett online-konto är rätt person och utan 2fa kan hackare få tillgång till känslig information eller konto enbart genom att känna till offrets lösenord.I denna studie kommer mest använt 3 olika alternativa två faktor autentiseringsmöjligheter för inloggning till Linux servrar undersökas för att se vilken 2fa som är både användarvänlig och säker att använda. Faktorer som kommer att undersökas är kostnad, plattformskompatibilitet, tillförlitlighet, säkerhetsmässigt och tid samt backupalternativ.undersökningen kommer vara baserat på intervjuer om Högskolan Västs IT avdelnings nya två faktor autentiseringssystem för anställda. Det kommer ställas frågor till systemspecialist som har tagit fram två faktorer autentiseringslösningen och Högskolans anställda som kommer använda azure mfa lösningen. Frågorna kommer vara baserad anställdas behov av två faktor autentiseringssystem och hur de anställda upplever den nya två faktor autentiseringslösningen.Resultaten från de praktiska testerna påvisar att Yubikey var den mest säkra autentiseringsmetoden och duo var den mest användarvänliga metoden. Resultaten som samlats från intervjuerna visade att anledningen till att Högskolan Västs IT-avdelning vill implementera två faktorer autentiseringen var att skydda mot Phishing attacker som kan vara svåra att upptäcka

  • 164.
    Abdi Kelishami, Alireza
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Secure Privacy-Friendly Instant Messaging (IM) for Guidepal2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    It is fascinating, and yet often neglected, that a user’s privacy can be invaded notonly by the absence of security measures and mechanisms, but also by improperor inadequate usage of security services and mechanisms. When designingsecure systems, we must consider what services are needed and what is not.The work in this thesis revolves around privacy-friendly instant messaging (IM)systems. In such a system, an inadequate usage of security measures leads tohaving IM servers being able to intercept or gather users’ private conversations.An improper usage of security measures could bring about non-repudiationwhich is desirable when signing contracts, but unwelcome in IM and privateconversations.We will look into requirements of the desired IM system, study the currentstate-of-the-art solutions, deploy an IM server, and briefly extend an existingmodern privacy-friendly IM protocol and an open source mobile application tomeet our security and privacy requirements. This extended IM application iscalled Guidepal-IM and is available as open source1The thesis work is introduced and carried out at Guidepal, a startup companyin Stockholm. It is therefore supervised partly at Guidepal and partly at KTH.Since Guidepal is also looking into possibilities of integrating an IM featureto its current social media apps, our contribution would also briefly extend tostudying the limitations and recommendations for Guidepal’s social media appto help user privacy preservation.

    Fulltekst (pdf)
    fulltext
  • 165.
    Abdi, Somayeh
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ashjaei, Seyed Mohammad Hossein
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Cognitive and Time Predictable Task Scheduling in Edge-cloud Federation2022Inngår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, Institute of Electrical and Electronics Engineers Inc. , 2022, Vol. 2022-SeptemberKonferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we present a hierarchical model for time predictable task scheduling in edge-cloud computing architecture for industrial cyber-physical systems. Regarding the scheduling problem, we also investigate the common problem-solving approaches and discuss our preliminary plan to realize the proposed architecture. Furthermore, an Integer linear programming (ILP) model is proposed for task scheduling problem in the cloud layer. The model considers timing and security requirements of applications and the objective is to minimize the financial cost of their execution.

  • 166.
    Abdirahman Adami, Adnan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Actors Cooperation Analysis: A Techo-economic Study on Smart City Paradigm2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Modern cities must overcome complex challenges to achieve socio-economic development and to improve the quality of life as the urban population is rapidly increasing. The concept of smart citie s is a response to these challenges. Thus, emerging technologies that are key enablers for the development of a smart city are said to be IoT and 5G. To deploy such technologies , however, may be expensive and requires the involvement of multiple actors. Hence, lack of cooperation and coordination for planning, financing, deploying and managing the city’s operational networks makes it even more difficult to overcome such challenges. Further, waste management companies and parking services operators in a city have expensive operation costs and services inefficiency due to little utilization of IoT-based solutions. This paper identifies and analyzes smart city ecosyst e ms, value networks, actors, actor’s roles, and business models in order to illustrate business relationships and provide business opportunities in the development of smart and sustainable cities through cooperation and collaboration among involved actors . Target actors that this study focuse s are on Mobile Network Operators, Parking Services Operators, and Waste Management Companies, and uses smart parking and smart waste collection as use-cases. Results show several cooperative business scenarios that can lead to successful business relationships and opportunities.

    Fulltekst (pdf)
    fulltext
  • 167.
    Abdirahman, Khalid
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Förnberg, Sebastian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Styrsystem för solcellsladdade batterier2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Användandet av solceller ökar kontinuerligt i Sverige och effekten som genererasav solcellerna förvaras oftast i bly-syra batterier. Dessa batterier har en dåligpåverkan på miljön eftersom det krävs mycket energi och miljöfarliga material såsom bly och svavelsyra för att tillverka dessa batterier. Östersjökompaniet AB ochmånga av dess kunder inser vikten av ett hållbart tänkande och var intresseradeav att veta om det var möjligt att maximera livslängden av dessa batterier. Underarbetets gång analyserades olika metoder för upp- och urladdning av batterier somkan påverka ett batteris livslängd och hur man kan bära sig åt för att optimera det.En laddningskontroller användes för att optimera laddningen av batteriet. För attberäkna laddningsnivån i batteriet användes metoden ”Extended voltmeter”. Enprototyp som kunde ladda batterierna på ett optimalt sätt, varna då batterietsladdningsnivå blev för låg samt en användarvänlig applikation för övervakning avbatteriet konstruerades. Ett batteris beräknade livslängd är ingen exakt vetenskap.Enligt studier kan livslängden av ett batteri fördubblas om det laddas upp ochladdas ur på ett optimalt sätt i jämförelse med då det laddas ur helt.

    Fulltekst (pdf)
    Styrsystem för solcellsladdade batterier
  • 168.
    Abdo, Adel
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Tesfai, Henon
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Öka energieffektiviteten genom Industri 4.02021Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta examensarbete har utförts i samråd med PTC i Trollhättan, Sverige. Rapporten består av en omfattad litraturstudie om de olika aspekterna som berör, att öka energieffektiviteten genom Industri 4.0. De olika aspekterna som berör “Öka energieffektiviteten genom Industri 4.0” har undersökts och ett beslut togs av författarna, att genom att förstå sig på de olika aspekterna inom de berörda ämnet kommer en djupare förståelse existera när resultatet är presenterat. De olika aspekterna är grundläggande information om Industri 4.0, förebyggande underhåll, allmän kännedom om ventilation, minimera temperaturökningen och öka energieffektiviteten i en industrilokal med hjälp av ventilation och en informations del om litiumjonbatteriet.

    Slutligen har ett resultat framtagits till krossning och separationsrummet för att öka energieffektiviteten i rummet. Resultat består av två delar i en och samma lösning. De två stegen är genom att återanvända luften i rummet, öka energieffektiviteten i att behöva värma upp eller kyla ner en ny extern luft. Den andra steget är att med hjälp av AI och Big data teknologin skall datorsystemet som kontrollerar ventilationssystemet lära sig och känna igen mönster på vädret och temperaturen i den externa miljön utanför industrilokalen. När datorsystemet lärt sig det kan den implementera den lärdomen om när det är lägligt att ny extern luft ska ersätta den befintliga luften i rummet och när det är lägligt att försöka återanvända luften i rummet för att öka på energieffektiviteten i att värma upp och kyla ner luften. Genom personlig kommunikation med handledare Johan Dahlström har ett resultat framtagits av författarna. Resultat anses uppnå målet som är att öka energieffektivitetenmed hjälp av Industri 4.0.

  • 169.
    Abdollahi Sani, Negar
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Robertsson, Mats
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Cooper, Philip
    De La Rue Plc, Overton, Hampshire, UK .
    Wang, Xin
    Acreo AB, Norrköping, Sweden.
    Svensson, Magnus
    Acreo AB, Norrköping, Sweden.
    Andersson Ersman, Peter
    Acreo AB, Norrköping, Sweden.
    Norberg, Petronella
    Acreo AB, Norrköping, Sweden.
    Nilsson, Marie
    Acreo AB, Norrköping, Sweden.
    Nilsson, David
    Acreo AB, Norrköping, Sweden.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Hesselbom, Hjalmar
    Hesselbom Innovation and Development HB, Huddinge, Sweden .
    Akesso, Laurent
    De La Rue Plc, Overton, Hampshire, UK .
    Fahlman, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Engquist, Isak
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan. Acreo AB, Norrköping, Sweden.
    Gustafsson, Goran
    Acreo AB, Norrköping, Sweden.
    All-printed diode operating at 1.6 GHz2014Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, nr 33, s. 11943-11948Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.

    Fulltekst (pdf)
    fulltext
  • 170.
    Abdollahi Sani, Negar
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Wang, Xin
    Acreo Swedish ICT AB, Sweden.
    Granberg, Hjalmar
    INNVENTIA AB, Sweden.
    Andersson Ersman, Peter
    Acreo Swedish ICT AB, Sweden.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Dyreklev, Peter
    Acreo Swedish ICT AB, Sweden.
    Engquist, Isak
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Göran
    Acreo Swedish ICT AB, Sweden.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Flexible Lamination-Fabricated Ultra-High Frequency Diodes Based on Self-Supporting Semiconducting Composite Film of Silicon Micro-Particles and Nano-Fibrillated Cellulose2016Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 6, nr 28921Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low cost and flexible devices such as wearable electronics, e-labels and distributed sensors will make the future "internet of things" viable. To power and communicate with such systems, high frequency rectifiers are crucial components. We present a simple method to manufacture flexible diodes, operating at GHz frequencies, based on self-adhesive composite films of silicon micro-particles (Si-mu Ps) and glycerol dispersed in nanofibrillated cellulose (NFC). NFC, Si-mu Ps and glycerol are mixed in a water suspension, forming a self-supporting nanocellulose-silicon composite film after drying. This film is cut and laminated between a flexible pre-patterned Al bottom electrode and a conductive Ni-coated carbon tape top contact. A Schottky junction is established between the Al electrode and the Si-mu Ps. The resulting flexible diodes show current levels on the order of mA for an area of 2 mm(2), a current rectification ratio up to 4 x 10(3) between 1 and 2 V bias and a cut-off frequency of 1.8 GHz. Energy harvesting experiments have been demonstrated using resistors as the load at 900 MHz and 1.8 GHz. The diode stack can be delaminated away from the Al electrode and then later on be transferred and reconfigured to another substrate. This provides us with reconfigurable GHz-operating diode circuits.

    Fulltekst (pdf)
    fulltext
  • 171.
    Abdsharifi, Mohammad Hossein
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Dhar, Ripan Kumar
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Service Management for P2P Energy Sharing Using Blockchain – Functional Architecture2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Blockchain has become the most revolutionary technology in the 21st century. In recent years, one of the concerns of world energy isn't just sustainability yet, in addition, being secure and reliable also. Since information and energy security are the main concern for the present and future services, this thesis is focused on the challenge of how to trade energy securely on the background of using distributed marketplaces that can be applied. The core technology used in this thesis is distributed ledger, specifically blockchain. Since this technology has recently gained much attention because of its functionalities such as transparency, immutability, irreversibility, security, etc, we tried to convey a solution for the implementation of a secure peer-to-peer (P2P) energy trading network over a suitable blockchain platform. Furthermore, blockchain enables traceability of the origin of data which is called data provenience.

    In this work, we applied a secure blockchain technology in peer-to-peer energy sharing or trading system where the prosumer and consumer can trade their energies through a secure channel or network. Furthermore, the service management functionalities such as security, reliability, flexibility, and scalability are achieved through the implementation. \\

    This thesis is focused on the current proposals for p2p energy trading using blockchain and how to select a suitable blockchain technique to implement such a p2p energy trading network. In addition, we provide an implementation of such a secure network under blockchain and proper management functions. The choices of the system models, blockchain technology, and the consensus algorithm are based on literature review, and it carried to an experimental implementation where the feasibility of that system model has been validated through the output results. 

    Fulltekst (pdf)
    Service Management for P2P Energy Sharing Using Blockchain – Functional Architecture
  • 172. Abdu, Tedros Salih
    et al.
    Kisseleff, Steven
    Lagunas, Eva
    Chatzinotas, Symeon
    Ottersten, Björn
    Interdisciplinary Centre for Security, Reliability and Trust, University of Luxembourg, Luxembourg, Luxembourg.
    Demand and Interference Aware Adaptive Resource Management for High Throughput GEO Satellite Systems2022Inngår i: IEEE Open Journal of the Communications Society, E-ISSN 2644-125X, Vol. 3, s. 759-775Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The scarce spectrum and power resources, the inter-beam interference, together with the high traffic demand, pose new major challenges for the next generation of Very High Throughput Satellite (VHTS) systems. Accordingly, future satellites are expected to employ advanced resource/interference management techniques to achieve high system spectrum efficiency and low power consumption while ensuring user demand satisfaction. This paper proposes a novel demand and interference aware adaptive resource management for geostationary (GEO) VHTS systems. For this, we formulate a multi-objective optimization problem to minimize the total transmit power consumption and system bandwidth usage while matching the offered capacity with the demand per beam. In this context, we consider resource management for a system with full-precoding, i.e., all beams are precoded; without precoding, i.e., no precoding is applied to any beam; and with partial precoding, i.e., only some beams are precoded. The nature of the problem is non-convex and we solve it by jointly using the Dinkelbach and Successive Convex Approximation (SCA) methods. The simulation results show that the proposed method outperforms the benchmark schemes. Specifically, we show that the proposed method requires low resource consumption, low computational time, and simultaneously achieves a high demand satisfaction.

  • 173. Abdu, Tedros Salih
    et al.
    Kisseleff, Steven
    Lagunas, Eva
    Grotz, Joel
    Chatzinotas, Symeon
    Ottersten, Björn
    Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, Luxembourg, Luxembourg.
    Demand-Aware Onboard Payload Processor Management for High Throughput NGSO Satellite Systems2023Inngår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 00189251, s. 1-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-Throughput Satellite (HTS) systems with digital payload technology have been identified as a key enabler to support 5G/6G high-data connectivity with wider coverage area. The satellite community has extensively explored resource allocation methods to achieve this target. Typically, these methods do not consider the intrinsic architecture of the flexible satellite digital payload, which consists of multiple processors responsible for receiving, processing, and transmitting the signals. This paper presents a demand-aware onboard processor management scheme for broadband Non-Geostationary (NGSO) satellites. In this context, we formulate an optimization problem to minimize the number of active on-board processors while meeting the system constraints and user requirements. As the problem is non-convex, we solve it in two steps. First, we transform the problem into demand-driven bandwidth allocation while fixing the number of processors. Second, using the bandwidth allocation solution, we determine the required number of processors with two methods: 1) sequential optimization with the Branch & Bound method and 2) Bin Packing with Next Fit, First Fit, and Best Fit methods. Finally, we demonstrate the proposed methods with extensive numerical results. It is shown that the Branch & Bound, Best Fit, and First Fit methods manage the processors better than the Next Fit method. Furthermore, Branch & Bound requires fewer processors than the above methods.

  • 174.
    Abdul Aziz Hasan Ali, Aamir
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Shahzad, Muhammad Adil
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    A Joint Subcarrier/Power allocation Scheme for OFDMA-based Cellular Networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The assignment of this master thesis consists of initiating power, subcarrier allocation in a dynamic FFR based scheme designed for multi-cell OFDMA networks and to enhance the throughput of all center users in bandwidth hungry borrower cells (overloaded cells) which was previously degraded by original FFR3 scheme as a result of partitioning of system bandwidth into center and edge bands respectively. The method uses band borrowing to compensate center user’s throughput loss in a semi and fully overloaded system. The scheme uses dynamic programming method (0/1 knapsack problem) to bargain an edge band on various power levels and tends to check the best combination (power and sub-carrier) which the system can utilize while still maintaining acceptable throughput loss for the users at the edge of the neighboring cell (lender cell).

    The algorithm consists of generating a borrowing request to neighboring cells for utilizing their edge bands by the overloaded borrower cell if their average center user throughput reaches below a minimum threshold value set in the system. The borrowing method uses 0/1 knapsack problem to capture an edge band based on limiting factors of total cost in average throughput losses by neighbors (Ci) and Un (tolerable mean user edge user throughput loss by lending cell). While solving knapsack problem the lender (neighbors) will check Ci and Un before granting the right to use its edge band. The later stage requires reducing subcarrier power level in order to utilize the lenders edge band using "soft borrower" mode. The borrowed sub-carriers will be activated take power from the original center band sub-carriers of the overloaded cell by taking into account the interference between the lender and the borrower. In case of negative (0) reply from the lender cell after the first request, multiple requests are generated at reduce power level at every step to order to acquire more bands. If a neighbor has band borrowing requests from multiple overloaded base stations, the band will be granted to the one which gives minimal loss in terms of throughput to the lender cell.

    The simulation results are analyzed w.r.t reuse-1 and FFR3 scheme of a multi cell regular and irregular scenarios comprising of lightly to heavily overloaded cells with various subcarrier allocation patterns. An overhead and time assessment is also presented between borrower and lender cells. Simulation results show an increase of 60% in center user’s throughput w.r.t original FFR3 scheme with an acceptable loss of 18% at the edges in complex overloaded scenarios while the overall system throughout increases by 35%.

    Fulltekst (pdf)
    fulltext
  • 175.
    Abdul Khader, Shahbaz
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Data-Driven Methods for Contact-Rich Manipulation: Control Stability and Data-Efficiency2021Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Autonomous robots are expected to make a greater presence in the homes and workplaces of human beings. Unlike their industrial counterparts, autonomous robots have to deal with a great deal of uncertainty and lack of structure in their environment. A remarkable aspect of performing manipulation in such a scenario is the possibility of physical contact between the robot and the environment. Therefore, not unlike human manipulation, robotic manipulation has to manage contacts, both expected and unexpected, that are often characterized by complex interaction dynamics.

    Skill learning has emerged as a promising approach for robots to acquire rich motion generation capabilities. In skill learning, data driven methods are used to learn reactive control policies that map states to actions. Such an approach is appealing because a sufficiently expressive policy can almost instantaneously generate appropriate control actions without the need for computationally expensive search operations. Although reinforcement learning (RL) is a natural framework for skill learning, its practical application is limited for a number of reasons. Arguably, the two main reasons are the lack of guaranteed control stability and poor data-efficiency. While control stability is necessary for ensuring safety and predictability, data-efficiency is required for achieving realistic training times. In this thesis, solutions are sought for these two issues in the context of contact-rich manipulation.

    First, this thesis addresses the problem of control stability. Despite unknown interaction dynamics during contact, skill learning with stability guarantee is formulated as a model-free RL problem. The thesis proposes multiple solutions for parameterizing stability-aware policies. Some policy parameterizations are partly or almost wholly deep neural networks. This is followed by policy search solutions that preserve stability during random exploration, if required. In one case, a novel evolution strategies-based policy search method is introduced. It is shown, with the help of real robot experiments, that Lyapunov stability is both possible and beneficial for RL-based skill learning.

    Second, this thesis addresses the issue of data-efficiency. Although data-efficiency is targeted by formulating skill learning as a model-based RL problem, only the model learning part is addressed. In addition to benefiting from the data-efficiency and uncertainty representation of the Gaussian process, this thesis further investigates the benefits of adopting the structure of hybrid automata for learning forward dynamics models. The method also includes an algorithm for predicting long-term trajectory distributions that can represent discontinuities and multiple modes. The proposed method is shown to be more data-efficient than some state-of-the-art methods. 

    Fulltekst (pdf)
    fulltext
  • 176.
    Abdul Khader, Shahbaz
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Yin, Hang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Falco, Pietro
    ABB Corporate Research, Vasteras, 72178, Sweden.
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL. ABB Corporate Research, Vasteras, 72178, Sweden.
    Learning deep energy shaping policies for stability-guaranteed manipulation2021Inngår i: IEEE Robotics and Automation Letters, E-ISSN 2377-3766, Vol. 6, nr 4, s. 8583-8590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep reinforcement learning (DRL) has been successfully used to solve various robotic manipulation tasks. However, most of the existing works do not address the issue of control stability. This is in sharp contrast to the control theory community where the well-established norm is to prove stability whenever a control law is synthesized. What makes traditional stability analysis difficult for DRL are the uninterpretable nature of the neural network policies and unknown system dynamics. In this work, stability is obtained by deriving an interpretable deep policy structure based on the energy shaping control of Lagrangian systems. Then, stability during physical interaction with an unknown environment is established based on passivity. The result is a stability guaranteeing DRL in a model-free framework that is general enough for contact-rich manipulation tasks. With an experiment on a peg-in-hole task, we demonstrate, to the best of our knowledge, the first DRL with stability guarantee on a real robotic manipulator.

  • 177.
    Abdul Khader, Shahbaz
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Yin, Hang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Falco, Pietro
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS.
    Learning Deep Neural Policies with Stability GuaranteesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Deep reinforcement learning (DRL) has been successfully used to solve various robotic manipulation tasks. However, most of the existing works do not address the issue of control stability. This is in sharp contrast to the control theory community where the well-established norm is to prove stability whenever a control law is synthesized. What makes traditional stability analysis difficult for DRL are the uninterpretable nature of the neural network policies and unknown system dynamics. In this work, unconditional stability is obtained by deriving an interpretable deep policy structure based on the energy shaping control of Lagrangian systems. Then, stability during physical interaction with an unknown environment is established based on passivity. The result is a stability guaranteeing DRL in a model-free framework that is general enough for contact-rich manipulation tasks. With an experiment on a peg-in-hole task, we demonstrate, to the best of our knowledge, the first DRL with stability guarantee on a real robotic manipulator.

    Fulltekst (pdf)
    fulltext
  • 178.
    Abdul Khader, Shahbaz
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL. ABB Corp Res, Västerås, Sweden..
    Yin, Hang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Falco, Pietro
    ABB Corp Res, Västerås, Sweden..
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Learning Stable Normalizing-Flow Control for Robotic Manipulation2021Inngår i: 2021 IEEE International Conference On Robotics And Automation (ICRA 2021), Institute of Electrical and Electronics Engineers (IEEE) , 2021, s. 1644-1650Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Reinforcement Learning (RL) of robotic manipulation skills, despite its impressive successes, stands to benefit from incorporating domain knowledge from control theory. One of the most important properties that is of interest is control stability. Ideally, one would like to achieve stability guarantees while staying within the framework of state-of-the-art deep RL algorithms. Such a solution does not exist in general, especially one that scales to complex manipulation tasks. We contribute towards closing this gap by introducing normalizing-flow control structure, that can be deployed in any latest deep RL algorithms. While stable exploration is not guaranteed, our method is designed to ultimately produce deterministic controllers with provable stability. In addition to demonstrating our method on challenging contact-rich manipulation tasks, we also show that it is possible to achieve considerable exploration efficiency-reduced state space coverage and actuation efforts- without losing learning efficiency.

  • 179.
    Abdul Khader, Shahbaz
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Yin, Hang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL.
    Pietro, Falco
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Robotik, perception och lärande, RPL. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS.
    Learning Stable Normalizing-Flow Control for Robotic ManipulationManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Reinforcement Learning (RL) of robotic manipu-lation skills, despite its impressive successes, stands to benefitfrom incorporating domain knowledge from control theory. Oneof the most important properties that is of interest is controlstability. Ideally, one would like to achieve stability guaranteeswhile staying within the framework of state-of-the-art deepRL algorithms. Such a solution does not exist in general,especially one that scales to complex manipulation tasks. Wecontribute towards closing this gap by introducing normalizing-flow control structure, that can be deployed in any latest deepRL algorithms. While stable exploration is not guaranteed,our method is designed to ultimately produce deterministiccontrollers with provable stability. In addition to demonstratingour method on challenging contact-rich manipulation tasks, wealso show that it is possible to achieve considerable explorationefficiency–reduced state space coverage and actuation efforts–without losing learning efficiency.

    Fulltekst (pdf)
    fulltext
  • 180.
    Abdul Khaliq, Ali
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Pecora, Federico
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Saffiotti, Alessandro
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Point-to-point safe navigation of a mobile robot using stigmergy and RFID technology2016Inngår i: 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1497-1504, artikkel-id 7759243Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Reliable autonomous navigation is still a challenging problem for robots with simple and inexpensive hardware. A key difficulty is the need to maintain an internal map of the environment and an accurate estimate of the robot’s position in this map. Recently, a stigmergic approach has been proposed in which a navigation map is stored into the environment, on a grid of RFID tags, and robots use it to optimally reach predefined goal points without the need for internal maps. While effective,this approach is limited to a predefined set of goal points. In this paper, we extend this approach to enable robots to travel to any point on the RFID floor, even if it was not previously identified as a goal location, as well as to keep a safe distance from any given critical location. Our approach produces safe, repeatable and quasi-optimal trajectories without the use of internal maps, self localization, or path planning. We report experiments run in a real apartment equipped with an RFID floor, in which a service robot either reaches or avoids a user who wears slippers equipped with an RFID tag reader.

  • 181.
    Abdul Nazar, Mohamed
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Design of a Gysel Combiner at 100 MHz2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis relates to the design and implementation of a Gysel power combiner consisting of two input ports. The design is implemented using discrete (lumped) components over the conventional transmission line architecture and operates at 100 MHz. Because of the high power requirements for the power combiner, special attention is given to the power handling capabilities of the lumped elements and the other components involved. Simulations of an S-parameter of Gysel power combiner are performed using the Advanced Design System (ADS) from Keysight Technologies. The final design of two-way Gysel power combiner using PCB toroidal inductor was implemented, simulated and optimized at centre frequency of 100 MHz. Satisfactory results were obtained in terms of Insertion loss, Return loss and Port Isolation.

    Fulltekst (pdf)
    Design of a Gysel Combiner at 100 MHz
  • 182.
    Abdul Waheed, Malik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Thörnberg, Benny
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Cheng, Xin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Lawal, Najeem
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Imran, Muhammad
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Kjeldsberg, Per Gunnar
    NTNU.
    Generalized Architecture for a Real-time Computation of an Image Component Features on a FPGAManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This paper describes a generalized architecture for real-time component labeling and computation of image component features. Computing real-time image component features is one of the most important paradigms for modern machine vision systems. Embedded machine vision systems demand robust performance, power efficiency as well as minimum area utilization. The presented architecture can easily be extended with additional modules for parallel computation of arbitrary image component features. Hardware modules for component labeling and feature calculation run in parallel. This modularization makes the architecture suitable for design automation. Our architecture is capable of processing 390 video frames per second of size 640x480 pixels. Dynamic power consumption is 24.20mW at 86 frames per second on a Xilinx Spartran6 FPGA.

  • 183. Abdul-Ahad, Amir Stefan
    et al.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Larsson, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Mahmoud, Waleed A.
    Robust Distance-Based Watermarking for Digital Video2008Inngår i: Proceedings of The Annual SIGRAD Conference, Stockholm, 2008Konferansepaper (Fagfellevurdert)
  • 184.
    Abdulhadi, Sami
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    ARM i inbyggt system: med prototyp2009Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Inbyggda system blir allt vanligare i dagens samhälle. De inbyggda systemen finns i nästan allt nuförtiden, från diverse fordon till leksaker för barn.

    Dagens teknik innebär bland annat att gårdagens lösningar kan realiseras på en bråkdel av den tidigare ytan. Allt mer blir ytmonterat med mindre och mer komplexa kretsar. Detta är inte alltid till utvecklarnas fördel då montering av prototypkort blir en svår och/eller dyr process.

    Målet är att ta fram ett inbyggt system med en ARM-processor. Systemet ska innehålla USB-OTG, ethernet, minne av olika slag som FRAM och microSD samt en display med pekskärm för användargränssnitt. Projektet omfattar allt från komponentval till test och verifiering med programkod.

    Tiden räckte inte till för att få med alla delar som planerats. Resultatet av projektet blev ett prototypkort och två små programsekvenser, en som blinkar två lysdioder på kortet och en som skriver ut en bild på displayen.

    Detta inbyggda system är i första hand till för utvärdering av ARM-processorer för Mikrodidakt AB.

    Fulltekst (pdf)
    ARM i inbyggt system - med prototyp
  • 185.
    Abdulkareem, Haji  
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Javidan, Mustafa
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Nätutvecklingsplan för området Hälltorp i Trollhättan2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Efter att flertal långa avbrott inträffat på luftledningen som matar mottagningsstationen Torsred, och på grund av en utbredning av bostadsbebyggelsen i närliggande område har Trollhättan Energi Elnät AB insett att en ny mottagningsstation som ersätter det befintliga behöver byggas på en ny plats. Föreliggande examensarbete omfattar utredning och uträkning av ett nytt elnät samt förslag på hur det nya elnätet kan integreras med det befintliga. Även en ny selektivplan och nya reservmatningsvägar för det nya elnätet utreds.

    Den befintliga mottagningsstationen Torsred matas från Vattenfall Eldistribution AB:s 130/10 kV transformator OT00 via en drygt 1 km lång luftledning. Nollpunkten i Torsred är kopplad till högspänningsskenan och består av ett nollpunktsmotstånd och en nollpunktsreaktor. Den totala lastströmmen i Torsred är 925 A och vid kortslutning i samlingsskenan uppstår 154 MVA kortslutningseffekt. Fördelningsstationen Ängen med en kortslutningseffekt på 138 MVA är en underliggande station till Torsred som matar områdena Öresjö, Edsäter och Hjärtum. Samtliga utgående ledningar i Torsred och Ängen skyddas med reläskydd och med olika tids-och strömsinställningar på dessa reläer råder selektivitet i underliggande elnätet.

    Den nya mottagningsstationen är tänkt att byggas nära inmatningspunkten OT00. Enligt beräkningar kommer kortslutningseffekten i den nya mottagningsstationen uppgå till 227 MVA och i den nya nätstationen Ängen till 200 MVA. Generering av kapacitiva jordfelsströmmar ökar på grund av att drygt 1 km luftledning raseras och ytterligare 7,5 km jordkablar inkluderas i det nya elnätet. Nollpunktsreaktorn behöver nu uppgraderas till 20 A större än det befintliga på grund av den ökade kapacitiva genereringen i elnätet. Kostnaden för att bygga den nya mottagningsstationen uppgår till cirka 9 Mkr. Den befintliga mottagningsstationen Torsred kommer att raseras och ersättas med en ny 800 kVA nätstation som senare utgör matningen till en del av lågspänningsnätet i området Strömslund. Befintliga fördelningsstationen Ängen kommer att moderniseras och fungera som en vanlig nätstation. Den totala kostnaden för hela projektet beräknas bli 11,4 Mkr.

    Fulltekst (pdf)
    fulltext
  • 186.
    Abdulla, Mohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Modeling of Thermal Stresses and Analysis of Micro-Crack Formations in PCB Laminates2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master’s thesis has given me an opportunity to study how, where, when and why cracks appear in the Printed Circuit Board (PCB) laminate. Layout choices contribute to the likelihood of crack formation. Simulations were made on three different locations on one board, the results were then analyzed. Thermal simulation showed nearly no thermal gradient in the board, the temperature inside the board was almost the same as at the surface. This concluded that there was no need for linked thermal and structural simulation. Structural simulations showed that most of the stress and compressions in the laminate was around the vias.

  • 187.
    Abdulla, Parosh
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Aronis, Stavros
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Jonsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Sagonas, Konstantinos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Optimal dynamic partial order reduction2014Inngår i: Proc. 41st ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, New York: ACM Press, 2014, s. 373-384Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Stateless model checking is a powerful technique for program verification, which however suffers from an exponential growth in the number of explored executions. A successful technique for reducing this number, while still maintaining complete coverage, is Dynamic Partial Order Reduction (DPOR). We present a new DPOR algorithm, which is the first to be provably optimal in that it always explores the minimal number of executions. It is based on a novel class of sets, called source sets, which replace the role of persistent sets in previous algorithms. First, we show how to modify an existing DPOR algorithm to work with source sets, resulting in an efficient and simple to implement algorithm. Second, we extend this algorithm with a novel mechanism, called wakeup trees, that allows to achieve optimality. We have implemented both algorithms in a stateless model checking tool for Erlang programs. Experiments show that source sets significantly increase the performance and that wakeup trees incur only a small overhead in both time and space.

  • 188.
    Abdulla, Parosh
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Jonsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Ngo, Tuan-Phong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Optimal Stateless Model Checking under the Release-Acquire Semantics2018Inngår i: SPLASH OOPSLA 2018, Boston, Nov 4-9, 2018, ACM Digital Library, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a framework for efficient application of stateless model checking (SMC) to concurrent programs running under the Release-Acquire (RA) fragment of the C/C++11 memory model. Our approach is based on exploring the possible program orders, which define the order in which instructions of a thread are executed, and read-from relations, which define how reads obtain their values from writes. This is in contrast to previous approaches, which in addition explore the possible coherence orders, i.e., orderings between conflicting writes. Since unexpected test results such as program crashes or assertion violations depend only on the read-from relation, we avoid a potentially large source of redundancy. Our framework is based on a novel technique for determining whether a particular read-from relation is feasible under the RA semantics. We define an SMC algorithm which is provably optimal in the sense that it explores each program order and read-from relation exactly once. This optimality result is strictly stronger than previous analogous optimality results, which also take coherence order into account. We have implemented our framework in the tool Tracer. Experiments show that Tracer can be significantly faster than state-of-the-art tools that can handle the RA semantics.

  • 189.
    Abdulla, Parosh
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Jonsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Ngo, Tuan-Phong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Optimal Stateless Model Checking under the Release-Acquire Semantics2018Inngår i: Proceedings of the ACM on Programming Languages, E-ISSN 2475-1421, Vol. 2, nr OOPSLA, s. 1-29, artikkel-id 135Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a framework for the efficient application of stateless model checking (SMC) to concurrent programs running under the Release-Acquire (RA) fragment of the C/C++11 memory model. Our approach is based on exploring the possible program orders, which define the order in which instructions of a thread are executed, and read-from relations, which specify how reads obtain their values from writes. This is in contrast to previous approaches, which also explore the possible coherence orders, i.e., orderings between conflicting writes. Since unexpected test results such as program crashes or assertion violations depend only on the read-from relation, we avoid a potentially significant source of redundancy. Our framework is based on a novel technique for determining whether a particular read-from relation is feasible under the RA semantics. We define an SMC algorithm which is provably optimal in the sense that it explores each program order and read-from relation exactly once. This optimality result is strictly stronger than previous analogous optimality results, which also take coherence order into account. We have implemented our framework in the tool Tracer. Experiments show that Tracer can be significantly faster than state-of-the-art tools that can handle the RA semantics.

    Fulltekst (pdf)
    FULLTEXT01
  • 190.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Bouajjani, Ahmed
    IRIF Université Paris Diderot, Paris, France.
    Ngo, Tuan Phong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Context-bounded analysis for POWER2017Inngår i: Tools and Algorithms for the Construction and Analysis of Systems: Part II, Springer, 2017, s. 56-74Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose an under-approximate reachability analysis algorithm for programs running under the POWER memory model, in the spirit of the work on context-bounded analysis initiated by Qadeer et al. in 2005 for detecting bugs in concurrent programs (supposed to be running under the classical SC model). To that end, we first introduce a new notion of context-bounding that is suitable for reasoning about computations under POWER, which generalizes the one defined by Atig et al. in 2011 for the TSO memory model. Then, we provide a polynomial size reduction of the context-bounded state reachability problem under POWER to the same problem under SC: Given an input concurrent program P, our method produces a concurrent program P' such that, for a fixed number of context switches, running P' under SC yields the same set of reachable states as running P under POWER. The generated program P' contains the same number of processes as P and operates on the same data domain. By leveraging the standard model checker CBMC, we have implemented a prototype tool and applied it on a set of benchmarks, showing the feasibility of our approach.

  • 191.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Bouajjani, Ahmed
    Ngo, Tuan Phong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik.
    Replacing store buffers by load buffers in TSO2018Inngår i: Verification and Evaluation of Computer and Communication Systems, Springer, 2018, s. 22-28Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the weak memory model of Total Store Ordering (TSO). In the classical definition of TSO, an unbounded buffer is inserted between each process and the shared memory. The buffers contains pending store operations of the processes. We introduce a new model where we replace the store buffers by load buffers. In contrast to the classical model, the buffers now contain load operations. We show that the models have equivalent behaviors in the sense that the processes reach identical sets of states when the input program is run under the two models.

  • 192.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Bui, Phi Diep
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Counter-Example Guided Program Verification2016Inngår i: FM 2016: Formal Methods, Springer, 2016, s. 25-42Konferansepaper (Fagfellevurdert)
  • 193.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Chen, Yu-Fang
    Institute of Information Science, Academia Sinica .
    Holik, Lukas
    Brno University.
    Rezine, Ahmed
    Linköping University.
    Rümmer, Philipp
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    String Constraints for Verification2014Inngår i: Computer Aided Verification - 26th International Conference, {CAV} 2014, Held as Part of the Vienna Summer of Logic, {VSL} 2014, Vienna, Austria, July 18-22, 2014. Proceedings, Springer, 2014, s. 150-166Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many existing procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implementation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.

  • 194.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Hofman, Piotr
    Mayr, Richard
    Kumar, K. Narayan
    Chennai Mathematical Institute, Chennai, India.
    Totzke, Patrick
    Infinite-state energy games2014Inngår i: Joint Meeting of the Twenty-Third EACSL Annual Conference on Computer Science Logic (CSL) and the Twenty-Ninth Annual ACM/IEEE Symposium on Logic in Computer Science (LICS), CSL-LICS '14, Vienna, Austria, July 14 - 18, 2014, New York: ACM Press, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Energy games are a well-studied class of 2-player turn-based games on a finite graph where transitions are labeled with integer vectors which represent changes in a multidimensional resource (the energy). One player tries to keep the cumulative changes non-negative in every component while the other tries to frustrate this.

    We consider generalized energy games played on infinite game graphs induced by pushdown automata (modelling recursion) or their subclass of one-counter automata.

    Our main result is that energy games are decidable in the case where the game graph is induced by a one-counter automaton and the energy is one-dimensional. On the other hand, every further generalization is undecidable: Energy games on one-counter automata with a 2-dimensional energy are undecidable, and energy games on pushdown automata are undecidable even if the energy is one-dimensional. Furthermore, we show that energy games and simulation games are inter-reducible, and thus we additionally obtain several new (un)decidability results for the problem of checking simulation preorder between pushdown automata and vector addition systems.

  • 195.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Rezine, Othmane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Verification of Directed Acyclic Ad Hoc Networks2013Inngår i: Formal Techniques for Distributed Systems: FORTE 2013, Springer Berlin/Heidelberg, 2013, s. 193-208Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 196.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Stenman, Jari
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Computing optimal reachability costs in priced dense-timed pushdown automata2014Inngår i: Language and Automata Theory and Applications: LATA 2014, Springer Berlin/Heidelberg, 2014, s. 62-75Konferansepaper (Fagfellevurdert)
  • 197.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Atig, Mohamed Faouzi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Stenman, Jari
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Zenoness for Timed Pushdown Automata2014Inngår i: Proceedings 15th International Workshop on Verification of Infinite-State Systems, {INFINITY} 2013, Hanoi, Vietnam, 14th October 2013., 2014, s. -47Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Timed pushdown automata are pushdown automata extended with a finite set of real-valued clocks. Additionaly, each symbol in the stack is equipped with a value representing its age. The enabledness of a transition may depend on the values of the clocks and the age of the topmost symbol. Therefore, dense-timed pushdown automata subsume both pushdown automata and timed automata. We have previously shown that the reachability problem for this model is decidable. In this paper, we study the zenoness problem and show that it is EXPTIME-complete.

  • 198.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Clemente, Lorenzo
    Mayr, Richard
    Sandberg, Sven
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Stochastic Parity Games on Lossy Channel Systems2014Inngår i: Logical Methods in Computer Science, ISSN 1860-5974, E-ISSN 1860-5974, Vol. 10, nr 4, artikkel-id 21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We give an algorithm for solving stochastic parity games with almost-sure winning conditions on lossy channel systems, under the constraint that both players are restricted to finitememory strategies. First, we describe a general framework, where we consider the class of 21/2-player games with almost-sure parity winning conditions on possibly infinite game graphs, assuming that the game contains a finite attractor. An attractor is a set of states (not necessarily absorbing) that is almost surely re-visited regardless of the players' decisions. We present a scheme that characterizes the set of winning states for each player. Then, we instantiate this scheme to obtain an algorithm for stochastic game lossy channel systems.

    Fulltekst (pdf)
    fulltext
  • 199.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Dwarkadas, Sandhya
    University of Rochester, U.S.A..
    Rezine, Ahmed
    Linköping University.
    Shriraman, Arrvindh
    Simon Fraser University, Canada .
    Yunyun, Zhu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Verifying safety and liveness for the FlexTM hybrid transactional memory2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the verification of safety (strict serializability and abort consistency) and liveness obstruction and livelock freedom) for the hybrid transactional memory framework FlexTM. This framework allows for flexible implementations of transactional memories based on an adaptation of the MESI coherence protocol. FlexTM allows for both eager and lazy conflict resolution strategies. Like in the case of Software Transactional Memories, the verification problem is not trivial as the number of concurrent transactions, their size, and the number of accessed shared variables cannot be a priori bounded. This complexity is exacerbated by aspects that are specific to hardware and hybrid transactional memories. Our work takes into account intricate behaviours such as cache line based conflict detection, false sharing, invisible reads or non-transactional instructions. We carry out the first automatic verification of a hybrid transactional memory and establish, by adopting a small model approach, challenging properties such as strict serializability, abort consistency, and obstruction freedom for both an eager and a lazy conflict resolution strategies. We also detect an example that refutes livelock freedom. To achieve this, our prototype tool makes use of the latest antichain based techniques to handle systems with tens of thousands of states.

  • 200.
    Abdulla, Parosh Aziz
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Haziza, Frédéric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Holík, Lukás
    Block me if you can!: Context-sensitive parameterized verification2014Inngår i: Static Analysis: SAS 2014, Springer, 2014, s. 1-17Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a method for automatic verification of systems with a parameterized number of communicating processes, such as mutual exclusion protocols or agreement protocols. To that end, we present a powerful abstraction framework that uses an efficient and precise symbolic encoding of (infinite) sets of configurations. In particular, it generalizes downward-closed sets that have successfully been used in earlier approaches to parameterized verification. We show experimentally the efficiency of the method, on various examples, including a fine-grained model of Szymanski’s mutual exclusion protocol, whose correctness, to the best of our knowledge, has not been proven automatically by any other existing methods.

    Fulltekst (pdf)
    fulltext
1234567 151 - 200 of 58444
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf