Loading...
Search for: distributed-computer-systems
0.009 seconds
Total 133 records

    Fault injection into verilog models for dependability evaluation of digital systems

    , Article 2nd International Symposium on Parallel and Distributed Computing, ISPDC 2003, 13 October 2003 through 14 October 2003 ; 2003 , Pages 281-287 ; 0769520693 (ISBN); 9780769520698 (ISBN) Zarandi, H. R ; Miremadi, S. G ; Ejlali, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2003
    Abstract
    This paper presents transient and permanent fault injection into Verilog models of digital systems during the design phase by a developed simulation-based fault injection tool called INJECT. With this fault injection tool, it is possible to inject crucial fault models in all abstraction levels (such as swith-level) supported by Verilog HDL. Several fault models for injecting into Verilog models are specified and described. Analyzing the results obtained from the fault injections, using INJECT enables system designers to inform from dependable parameters, such as fault latency, propagation and coverage. As a case study, a 32-bit processor, namely DP32, has been evaluated and effects of faults... 

    An enhanced random-walk method for content locating in P2P networks

    , Article 27th International Conference on Distributed Computing Systems Workshops, ICDCSW'07, Toronto, ON, 22 June 2007 through 29 June 2007 ; 2007 ; 0769528384 (ISBN); 9780769528380 (ISBN) Ronasi, K ; Firooz, M. H ; Pakravan, M. R ; Nasiri Avanaki, A ; Sharif University of Technology
    2007
    Abstract
    The important problem of content location in an unstructured distributed network (such as P2P, with no central searching system, graph construction control or file placement regulation) is addressed. The existing methods that are based on either flooding or random walk impose a large traffic load on the network or require a long time to search. In this work, we propose a method that outperforms the existing methods in both of these measures. These advantages are achieved by publishing traces of the contents of each node in its nearby nodes, so that the closer nodes to the target have a stronger trace of it. Such traces are used to rapidly locate the desired content. The superb performance of... 

    Assessment of message missing failures in CAN-based systems

    , Article IASTED International Conference on Parallel and Distributed Computing and Networks, as part of the 23rd IASTED International Multi-Conference on Applied Informatics, Innsbruck, 15 February 2005 through 17 February 2005 ; 2005 , Pages 387-392 ; 10272666 (ISSN) Salmani, H ; Miremadi, S. G ; Fahringer T ; Hamza M. H ; Sharif University of Technology
    2005
    Abstract
    This paper presents a simulation-based environment to study fault effects in message missing failures in CAN-based systems. A CAN controller is modeled by VHDL at behavioral level and is exploited to set up a network composed of several nodes. A total of 27,000 transient faults of seven types are injected into five critical portions of the system including the bus and four portions of the CAN controller. The experimental results show that the faults affect the message sending in which more than 20% of faults cause the failure. Besides, with a heavy workload, faults that are occurred into the CAN controller and on the bus cause about 90% and 10% of all failures, respectively  

    A scalable framework for wireless distributed computing

    , Article IEEE/ACM Transactions on Networking ; Volume 25, Issue 5 , 2017 , Pages 2643-2654 ; 10636692 (ISSN) Li, S ; Yu, Q ; Maddah Ali, M. A ; Avestimehr, A. S ; Sharif University of Technology
    Abstract
    We consider a wireless distributed computing system, in which multiple mobile users, connected wirelessly through an access point, collaborate to perform a computation task. In particular, users communicate with each other via the access point to exchange their locally computed intermediate computation results, which is known as data shuffling. We propose a scalable framework for this system, in which the required communication bandwidth for data shuffling does not increase with the number of users in the network. The key idea is to utilize a particular repetitive pattern of placing the data set (thus a particular repetitive pattern of intermediate computations), in order to provide the... 

    Packet loss in peer-to-peer video streaming over the Internet

    , Article Multimedia Systems ; Volume 13, Issue 5-6 , 2008 , Pages 345-361 ; 09424962 (ISSN) Akbari, B ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
    2008
    Abstract
    Peer-to-peer streaming has recently gained attention as an effective solution to support large scale media streaming applications over the Internet. One of the main challenges of peer-to-peer video streaming is the cumulative impact of the Internet packet loss due to the decoding dependency of the compressed video frames. In this paper we study the impact of the Internet packet loss on the performance of peer-to-peer video streaming systems, and analyze the efficiency of various packet loss recovery policies in such systems. Our analytical and simulation results show how the Internet packet loss can affect the performance of peer- to-peer video streaming systems and how different packet loss... 

    Capturing an intruder in product networks

    , Article Journal of Parallel and Distributed Computing ; Volume 67, Issue 9 , 2007 , Pages 1018-1028 ; 07437315 (ISSN) Imani, N ; Sarbazi Azad, H ; Zomaya, A. Y ; Sharif University of Technology
    2007
    Abstract
    In this paper, we propose a solution to the problem of capturing an intruder in a product network. This solution is derived based on the assumption of existing algorithms for basic member graphs of a graph product. In this problem, a team of cleaner agents are responsible for capturing a hostile intruder in the network. While the agents can move in the network one hop at a time, the intruder is assumed to be arbitrarily fast in a way that it can traverse any number of nodes contiguously as far as no agents reside in those nodes. Here, we consider a version of the problem where each agent can replicate new agents. Thus, the algorithm starts with a single agent and new agents are created on... 

    Extended Rebeca: A component-based actor language with synchronous message passing

    , Article 5th International Conference on Application of Concurrency to System Design, ACSD 2005, St. Malo, 7 June 2005 through 9 June 2005 ; Volume 2005 , 2005 , Pages 212-220 ; 15504808 (ISSN); 0769523633 (ISBN); 9780769523637 (ISBN) Sirjani, M ; De Boer, F ; Movaghar, A ; Shali, A ; Sharif University of Technology
    2005
    Abstract
    In this paper, we propose extended Rebeca as a tool-supported actor-based language for modeling and verifying concurrent and distributed systems. We enrich Rebeca with a formal concept of components which integrates the message-driven computational model of actor-based languages with synchronous message passing. Components are used to encapsulate a set of internal active objects which react asynchronously to messages by means of methods and which additionally interact via a synchronous message passing mechanism. Components themselves interact only via asynchronous and anonymous messages. We present our compositional verification approach and abstraction techniques, and the theory... 

    Computation time analysis of centralized and distributed optimization algorithms applied to automated irrigation networks

    , Article 2013 3rd Australian Control Conference, AUCC 2013, Fremantle, WA ; Nov , 2013 , Pages 263-269 ; 9781479924981 (ISBN) Farhadi, A ; Dower, P. M ; Cantoni, M ; Sharif University of Technology
    2013
    Abstract
    This paper compares the computation time of two algorithms for solving a structured constrained linear optimal control problem with finite horizon quadratic cost within the context of automated irrigation networks. The first is a standard centralized algorithm based on the active set method that does not exploit problem structure. The second is distributed and is based on a consensus algorithm, not specifically tailored to account for system structure. It is shown that there is a significant advantage in terms of computation overhead (the time spent computing the optimal solution) in using the second algorithm in large-scale networks. Specifically, for a fixed horizon length the computation... 

    Extension of particle filters for time-varying target presence through split and raw measurements

    , Article IET Radar, Sonar and Navigation ; Volume 7, Issue 5 , 2013 , Pages 517-526 ; 17518784 (ISSN) Danaee, M. R ; Behnia, F ; Sharif University of Technology
    2013
    Abstract
    Target tracking through particle filter (PF) for time-varying presence of a target is compared for thresholded and nonthresholded measurements, where in both cases a track produces more than one measurement. To that end, thresholded split measurements PF along with non-thresholded measurements, sequential importance resampling PF (SIR PF) and auxiliary variable PF (AV PF) are extended to cope with time-varying target presence. Simulations show superiorities in working through non-thresholded measurements. Furthermore, they surprisingly demonstrate that non-thresholded measurements SIR PF leads to less root-mean-square position estimation error than non-thresholded measurements AV PF in case... 

    A measurement framework for directed networks

    , Article IEEE Journal on Selected Areas in Communications ; Volume 31, Issue 6 , June , 2013 , Pages 1007-1016 ; 07338716 (ISSN) Salehi, M ; Rabiee, H. R ; Sharif University of Technology
    2013
    Abstract
    Partially-observed network data collected by link-tracing based sampling methods is often being studied to obtain the characteristics of a large complex network. However, little attention has been paid to sampling from directed networks such as WWW and Peer-to-Peer networks. In this paper, we propose a novel two-step (sampling/estimation) framework to measure nodal characteristics which can be defined by an average target function in an arbitrary directed network. To this end, we propose a personalized PageRank-based algorithm to visit and sample nodes. This algorithm only uses already visited nodes as local information without any prior knowledge about the latent structure of the network.... 

    A new metric for comparison of P2P search algorithms

    , Article Proceedings - 2012 7th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing, 3PGCIC 2012, 12 November 2012 through 14 November 2012 ; November , 2012 , Pages 191-195 Sharifkhani, F ; Pakravan, M. R ; Sharif University of Technology
    2012
    Abstract
    Success rate, query hit rate and speed of search are some common metrics for evaluating p2p search algorithms. Yet, these metrics do not consider properties of discovered sources and their impact on download performance. A requesting peer is interested in stable serving peers with high upload bandwidth to minimize its download time and therefore, this is the superiority of a search algorithm to find sources with higher upload bandwidth in the p2p heterogeneous environment. In this paper, a new bio-inspired metric for comparing p2p search algorithms is introduced which takes the upload bandwidth of supplying nodes into account as a factor influencing quality of a search algorithm and user... 

    Visual tracking using D2-clustering and particle filter

    , Article 2012 IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2012 ; 2012 , Pages 230-235 ; 9781467356060 (ISBN) Raziperchikolaei, R ; Jamzad, M ; Sharif University of Technology
    2012
    Abstract
    Since tracking algorithms should be robust with respect to appearance changes, online algorithms has been investigated recently instead of offline ones which has shown an acceptable performance in controlled environments. The most challenging issue in online algorithms is updating of the model causing tracking failure because of introducing small errors in each update and disturbing the appearance model (drift). in this paper, we propose an online generative tracking algorithm in order to overcome the challenges such as occlusion, object shape changes, and illumination variations. In each frame, color distribution of target candidates is obtained and the candidate having the lowest distance... 

    A usage control based architecture for cloud environments

    , Article Proceedings of the 2012 IEEE 26th International Parallel and Distributed Processing Symposium Workshops, IPDPSW 2012, 21 May 2012 through 25 May 2012 ; 2012 , Pages 1534-1539 ; 9780769546766 (ISBN) Tavizi, T ; Shajari, M ; Dodangeh, P ; Sharif University of Technology
    2012
    Abstract
    Today modern computing systems leverage distributed models such as cloud, grid, etc. One of the obstacles of wide spreading these distributed computing models is security challenges which includes access control problem. These computing models because of providing features like on-demand self-service, ubiquitous network access, rapid elasticity and scalability, having dynamic infrastructure and offering measured service, need a powerful and continuous control over access and usage session. Usage control (UCON) model is emerged to cover some drawbacks of traditional access control models with features like attribute mutability and continuity of control. Several recent works have been done to... 

    Realizability of choreographies using Process algebra encodings

    , Article IEEE Transactions on Services Computing ; Volume 5, Issue 3 , 2012 , Pages 290-304 ; 19391374 (ISSN) Salaün, G ; Bultan, T ; Roohi, N ; Sharif University of Technology
    IEEE  2012
    Abstract
    Service-oriented computing has emerged as a new software development paradigm that enables implementation of Web accessible software systems that are composed of distributed services which interact with each other via exchanging messages. Modeling and analysis of interactions among services is a crucial problem in this domain. Interactions among a set of services that participate in a service composition can be described from a global point of view as a choreography. Choreographies can be specified using specification languages such as Web Services Choreography Description Language (WS-CDL) and visualized using graphical formalisms such as collaboration diagrams. In this paper, we present an... 

    Modeling topological characteristics of BitTorrent-like peer-to-peer networks

    , Article IEEE Communications Letters ; Volume 15, Issue 8 , August , 2011 , Pages 896-898 ; 10897798 (ISSN) Farzad, A ; Rabiee, H. R ; Sharif University of Technology
    2011
    Abstract
    This letter presents a complex network model for the BitTorrent; the most popular peer-to-peer network. Three important topological characteristics; (i) degree distribution, (ii) clustering coefficient and (iii) average path length of this network are analytically modeled. The analytical computations are confirmed by simulations. Moreover, the accuracy of the proposed model was confirmed by exploiting a BitTorrent simulator  

    Fault injection into verilog models for dependability evaluation of digital systems

    , Article Proceedings - 2nd International Symposium on Parallel and Distributed Computing, ISPDC 2003, 13 October 2003 through 14 October 2003 ; October , 2015 , Pages 281-287 ; 0769520693 (ISBN) ; 9780769520698 (ISBN) Zarandi, H. R ; Miremadi, S. G ; Ejlali, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    This paper presents transient and permanent fault injection into Verilog models of digital systems during the design phase by a developed simulation-based fault injection tool called INJECT. With this fault injection tool, it is possible to inject crucial fault models in all abstraction levels (such as swith-level) supported by Verilog HDL. Several fault models for injecting into Verilog models are specified and described. Analyzing the results obtained from the fault injections, using INJECT enables system designers to inform from dependable parameters, such as fault latency, propagation and coverage. As a case study, a 32-bit processor, namely DP32, has been evaluated and effects of faults... 

    A hybrid mesh-tree peer-to-peer overlay structure for layered video streaming

    , Article 2010 5th International Symposium on Telecommunications, IST 2010, 4 December 2010 through 6 December 2010, Tehran ; 2010 , Pages 706-709 ; 9781424481835 (ISBN) Tahghigh Jahromi, N ; Akbari, B ; Movaghar, A ; Sharif University of Technology
    2010
    Abstract
    Due to complicated implementation of IP multicast, application layer multicast has attracted the attention of researchers. Tree overlay has some challenges such as resiliency problems caused by peer churns and also network resources may not be efficiently used. Mesh overlay doesn't have such problems, but has a high delivery latency and overhead caused by pull mechanism. Using a hybrid mesh/tree overlay offers push pull approach and leads to use the advantages of both overlays simultaneously. Also in p2p networks a significant problem is heterogeneity of peers. In this paper we propose a hybrid mesh/tree overlay that by means of streaming layered coded video, addresses these challenges. This... 

    The effect of using cube connected cycle for improving locality awareness in peer-to-peer networks

    , Article UKSim2010 - UKSim 12th International Conference on Computer Modelling and Simulation, 24 March 2010 through 26 March 2010 ; March , 2010 , Pages 491-496 ; 9780769540160 (ISBN) Gharib, M ; Barzegar, Z ; Habibi, J ; UK Simulation Society; Asia Modelling and Simulation Society (AMSS); European Federation of Simulation Societies (EUROSIM); IEEE UK and RI; European Council for Modelling and Simulation (ECMS) ; Sharif University of Technology
    2010
    Abstract
    Today, peer-to-peer networks are become more popular among internet users and more than millions peers share high volume of data from anywhere. Sending and receiving these data increase the network traffics terribly. By improving the performance of these networks not only the efficiency of these networks increase but also the overall performance of the internet augments. To achieve high performance and resilience to failures, a peer can make connections with those other peers that are geographically closer to it. There are many solutions that are suggested for locality problem. In this paper, we suggest a Cube Connected Cycle as an overlay network to improve locality with higher performance  

    A large-scale active measurement study on the effectiveness of piece-attack on bit torrent networks

    , Article IEEE Transactions on Dependable and Secure Computing ; Volume 13, Issue 5 , 2016 , Pages 509-518 ; 15455971 (ISSN) Fattaholmanan, A ; Rabiee, H. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Abstract
    The peer to peer (P2P) file sharing applications have allocated a significant amount of today's Internet traffic. Among various P2P file sharing protocols, BitTorrent is the most common and popular one that attracts monthly a quarter of a billion users from all over the world. Similar to other P2P file sharing protocols, BitTorrent is mostly used for illegal sharing of copiright protected files such as movies, music and TV series. To impede this huge amount of illegal file distributions, anti-P2P companies have arisen to stand against these applications (specially the BitTorrent). To this end, they have begun to fire large-scale Internet attacks against BitTorrent networks. In this paper, we... 

    A secure attribute based keyword search scheme against keyword guessing attack

    , Article 2016 8th International Symposium on Telecommunications, IST 2016,17 March 2017 ; 2017 , Pages 124-128 ; 9781509034345 (ISBN) Yousefipoor, V ; Ameri, M. H ; Mohajeri, J ; Eghlidos, T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    To provide the privacy of the users who receive some computing services from the cloud, the users must encrypt their documents before outsourcing them to the cloud. Computation on outsourced encrypted data in the cloud rises some complexity to the system specially in the case when an entity would like to find some documents related to a special keyword. Searchable encryption is a tool for data owners to encrypt their data in a searchable manner. Generally, there exist two kinds of searchable encryption, namely symmetric (secret key) and asymmetric (public key) ones. Most of the public key searchable encryption schemes are vulnerable to the keyword guessing attack (KGA). In this paper we...