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distributed-computer-systems
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Total 133 records
Feature-based content dissemination process in opportunistic networks
, Article 26th IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2015, 30 August 2015 through 2 September 2015 ; Volume 2015-December , 2015 , Pages 1464-1469 ; 9781467367820 (ISBN) ; Elhami, G ; Pakravan, M. R ; Sharif University of Technology
Abstract
In order to respond to drastically increased traffic demands in mobile networks such as cellulars, opportunistic communication has been introduced as a data offloading strategy. Delivering the contents using peer-to-peer data dissemination is more preferable compared to epidemic diffusion schemes. To implement peer-to-peer dissemination, one needs to define the peer selection and content dissemination policies. Efficient content dissemination relies on the selection of suitable peers. Besides that, the peers require to choose what contents to be transmitted between them. In this paper, we propose multi-level master/slave peer selection algorithm (MMSA) and variance-based multi-metric chunk...
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) ; 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...
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) ; 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...
Using description logics for network vulnerability analysis
, Article International Conference on Networking, International Conference on Systems and International Conference on Mobile Communications and Learning Technologies, ICN/ICONS/MCL'06, Morne, 23 April 2006 through 29 April 2006 ; Volume 2006 , 2006 ; 0769525520 (ISBN); 9780769525525 (ISBN) ; Jalili, R ; Abolhassani, H ; Shahriari, H. R ; Sharif University of Technology
2006
Abstract
The distributed nature and complexity of computer networks and various services provided via them, makes the networks vulnerable to numerous attacks. The TCP/IP presumptions which are based on using this protocol to provide a simple, open communication infrastructure in an academic and collaborative environment, causes this protocol lack of built-in mechanisms for authentication, integrity and privacy. Even though in the last few years a more systematic approach to TCP/IP network security problem has been followed, a formal approach to this problem is lacking. In this paper, we propose using Description Logics as a formal model which could be used to analyze TCP/IP networks against attacks....
Collaborative privacy management in P2P online social networks
, Article 12th International ISC Conference on Information Security and Cryptology, 8 September 2015 through 10 September 2015 ; 2015 , Pages 64-72 ; 9781467376099 (ISBN) ; Alizadeh, M ; Abbas Pour, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
Online Social Networks (OSNs) have become widely popular in recent years. In spite of users' interest to join OSNs, sharing vast amounts of personal information and resources in these networks might result in privacy issues for them. In the centralized OSNs, access control policies defined by users are enforced by OSN providers. Moreover, as these shared resources are stored by providers, they can access them. To avoid such problems, various architectures for decentralized OSNs are proposed. But the proposed architectures for P2P OSNs yet do not support any mechanism for collaborative privacy management on the shared content. By increasing the amount of resources such as photos which is...
Straggler mitigation in distributed matrix multiplication: fundamental limits and optimal coding
, Article IEEE Transactions on Information Theory ; Volume 66, Issue 3 , 2020 , Pages 1920-1933 ; Maddah Ali, M. A ; Avestimehr, A. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
We consider the problem of massive matrix multiplication, which underlies many data analytic applications, in a large-scale distributed system comprising a group of worker nodes. We target the stragglers' delay performance bottleneck, which is due to the unpredictable latency in waiting for slowest nodes (or stragglers) to finish their tasks. We propose a novel coding strategy, named entangled polynomial code, for designing the intermediate computations at the worker nodes in order to minimize the recovery threshold (i.e., the number of workers that we need to wait for in order to compute the final output). We demonstrate the optimality of entangled polynomial code in several cases, and show...
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) ; 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...
Game-theoretic approach to mitigate packet dropping in wireless Ad-hoc networks
, Article 2011 IEEE Consumer Communications and Networking Conference, CCNC'2011, 8 January 2011 through 11 January 2011, Las Vegas, NV ; 2011 , Pages 163-165 ; 9781424487905 (ISBN) ; Farhat, F ; Pakravan, M. R ; Aref, M. R ; Sharif University of Technology
2011
Abstract
Performance of routing is severely degraded when misbehaving nodes drop packets instead of properly forwarding them. In this paper, we propose a Game-Theoretic Adaptive Multipath Routing (GTAMR) protocol to detect and punish selfish or malicious nodes which try to drop information packets in routing phase and defend against collaborative attacks in which nodes try to disrupt communication or save their power. Our proposed algorithm outranks previous schemes because it is resilient against attacks in which more than one node coordinate their misbehavior and can be used in networks which wireless nodes use directional antennas. We then propose a game theoretic strategy, ERTFT, for nodes to...
Decentralized active power management in multi-agent distribution systems considering congestion issue
, Article IEEE Transactions on Smart Grid ; Volume 13, Issue 5 , 2022 , Pages 3582-3593 ; 19493053 (ISSN) ; Fattaheian Dehkordi, S ; Fotuhi Firuzabad, M ; Lehtonen, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Recently, due to the restructuring of power systems and the high penetration level of local renewables, distribution systems have encountered with the complexity of power management. Therefore, the modern systems would be operated in a multi-agent structure which facilitates the power management as well as privacy protections of independent entities. In this structure, the distribution system is assumed to compose of several agents who independently schedule their local resources in order to maximize their own profits. Consequently, this paper provides an efficient peer-to-peer (P2P) active power management framework in a multi-agent distribution system while considering network constraints...
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) ; 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...
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) ; 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...
Polynomial-time fence insertion for structured programs
, Article 33rd International Symposium on Distributed Computing, DISC 2019, 14 October 2019 through 18 October 2019 ; Volume 146 , 2019 ; 18688969 (ISSN); 9783959771269 (ISBN) ; Pourdamghani, A ; Lesani, M ; Suomela J ; Sharif University of Technology
Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
2019
Abstract
To enhance performance, common processors feature relaxed memory models that reorder instructions. However, the correctness of concurrent programs is often dependent on the preservation of the program order of certain instructions. Thus, the instruction set architectures offer memory fences. Using fences is a subtle task with performance and correctness implications: using too few can compromise correctness and using too many can hinder performance. Thus, fence insertion algorithms that given the required program orders can automatically find the optimum fencing can enhance the ease of programming, reliability, and performance of concurrent programs. In this paper, we consider the class of...
OPAIC: An optimization technique to improve energy consumption and performance in application specific network on chips
, Article Measurement: Journal of the International Measurement Confederation ; Volume 74 , 2015 , Pages 208-220 ; 02632241 (ISSN) ; Taassori, M ; Niroomand, S ; Vizvári, B ; Uysal, S ; Hadi Vencheh, A ; Sharif University of Technology
Elsevier
2015
Abstract
Abstract Network on Chip (NoC) is an appropriate and scalable solution for today's System on Chips (SoCs) with the high communication demands. Application specific NoCs is preferable since they can be customized to optimize all requirements of the specific applications. This paper presents an OPtimization technique for Application specifIC NoCs (OPAIC), which aims not only to decrease the energy consumption but also to improve the area of NoCs. OPAIC is composed of three stages to find the optimum NoC; in the first stage, it uses a linearized form of a Quadratic Assignment Problem (QAP) to map tasks on cores to minimize the energy. In the second stage, a Mixed Integer Linear Problem (MILP)...
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) ; 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...
Crosstalk avoidance coding for reliable data transmission of network on chips
, Article 2013 International Symposium on System-on-Chip, SoC 2013 - Proceedings ; 2013 ; Miremadi, S. G ; Sharif University of Technology
2013
Abstract
Inter-wire coupling capacitance may lead to crosstalk faults that significantly limits the reliability of NoCs. In this paper, we propose a numerical-based crosstalk avoidance code that can omit the Triplet Opposite Direction (TOD) transitions produced by crosstalk faults. The proposed coding does not have ambiguity and uses all of the codeword space. Simulations using VHDL for different channel widths show that the proposed method can reduce crosstalk fault in the NoC links with negligible power and area overheads
PAM: A packet manipulation mechanism for mitigating crosstalk faults in NoCs
, Article Proceedings - 15th IEEE International Conference on Computer and Information Technology, CIT 2015, 14th IEEE International Conference on Ubiquitous Computing and Communications, IUCC 2015, 13th IEEE International Conference on Dependable, Autonomic and Secure Computing, DASC 2015 and 13th IEEE International Conference on Pervasive Intelligence and Computing, PICom 2015, 26 October 2015 through 28 October 2015 ; October , 2015 , Pages 1895-1902 ; 9781509001545 (ISBN) ; Ansari, M ; Abharian, S. K ; Safari, S ; Miremadi, S. G ; Atzori L ; Jin X ; Jarvis S ; Liu L ; Calvo R. A ; Hu J ; Min G ; Georgalas N ; Wu Y ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
This paper proposes an efficient mechanism that mitigates crosstalk faults in Network-on-Chips (NoCs). This is done by using a Packet Manipulating mechanism called PAM for reliable data transfer of NoCs. PAM investigates the transitions of a packet to minimize the forbidden transition patterns appearing during the flit traversal in NoCs. To do this, the content of a packet is manipulated using three different manipulating mechanisms. In other words, PAM manipulates the content of packet in three manipulating modes including: vertical, horizontal and diagonal modes. Then, comparing the transitions of these manipulating mechanisms, a packet with minimum numbers of transitions is selected to be...
S2AP: An efficient numerical-based crosstalk avoidance code for reliable data transfer of NoCs
, Article 10th International Symposium on Reconfigurable and Communication-centric Systems-on-Chip,, 29 June 2015 through 1 July 2015 ; June , 2015 , Page(s): 1 - 6 ; 9781467379427 (ISBN) ; Miremadi, S. G ; Janssen K ; DFG ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Data traversal in Network-on-Chips (NoCs) is threated by crosstalk fault seriously. Crosstalk fault leads to mutual influence between adjacent wires of NoCs and as a result endangers the reliability of data in NoCs. Crosstalk fault is strongly dependent on the transition patterns appearing on the wires of NoCs. Among these transitions, Triplet Opposite Directions (TODs) impose the worse crosstalk effects to the wires of NoCs. This paper proposes an efficient numerical-based coding mechanism called Summation-based-Subtracted-Added-Penultimate (S2AP) which alleviates crosstalk faults. This is done by completely removing TODs which are the main source of crosstalk faults in the channels of...
An efficient and low power one-lambda crosstalk avoidance code design for network on chips
, Article Microprocessors and Microsystems ; Volume 63 , 2018 , Pages 36-45 ; 01419331 (ISSN) ; Mahdavi, Z ; Sharif University of Technology
Abstract
Crosstalk faults occurring in wires of Networks on Chip (NoCs) can seriously threaten the reliability of data transfer. One efficient way to tackle crosstalk faults is numeral-based Crosstalk Avoidance Codes (CACs). Numeral-based CACs reduce crosstalk faults by preventing specific transition patterns to occur. One-Lambda Codes (OLCs) are the most efficient types of CACs. However, the codec of OLCs imposes overheads including power consumption, critical path and area occupation to the routers of NoCs. To find overhead-efficient OLCs, this paper proposes an Algorithm for Generating OLC Numeral systems (AGON). AGON provides a tradeoff for designers in selecting overhead-efficient OLCs. Using...
Bacterial foraging search in unstructured P2P networks
, Article Canadian Conference on Electrical and Computer Engineering ; 2014 ; Pakravan, M. R ; Sharif University of Technology
Abstract
In this paper, a new search algorithm in heterogeneous hierarchical unstructured p2p networks is presented which takes into account heterogeneity of peers such as upload bandwidth, life time in the network and process capacity in its peer discovery policy as factors that influence download performance and user satisfaction. One advantage of this algorithm is that it can be performed in a completely unstructured network without imposing any change on network topology and file replication. However, it obviously decreases file download time as it is designed to discover broad-bandwidth nodes with a higher probability. This property results in a fair distribution of load over heterogeneous p2p...
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 ; 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...