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A general framework for voltage sag performance analysis of distribution networks
, Article Energies ; Volume 12, Issue 14 , 2019 ; 19961073 (ISSN) ; Fotuhi Firuzabad, M ; Lehtonen, M ; Sharif University of Technology
MDPI AG
2019
Abstract
The proliferation of more sensitive loads has obliged distribution companies to pay greater attention to the voltage sag mitigation potential of different design alternatives in network planning studies. In doing so, a company has to have effective tools for estimating the voltage sag performance of its network. In this regard, this paper establishes a three-step framework for evaluating voltage sag performance of a distribution network. The first step, designated as state selection, is to select a network state in which voltage sag is likely. Although voltage sags have various causes, those that originated from faults in distribution networks are considered in this paper. The stochastic...
Truthful and secure routing in Ad Hoc networks
, Article 2008 International Symposium on Computer Science and its Applications, CSA 2008, Hobart, TAS, 13 October 2008 through 15 October 2008 ; October , 2008 , Pages 369-376 ; 9780769534282 (ISBN) ; Ghodsi, M
2008
Abstract
Cooperation among nodes is vital in wireless networks since in such networks nodes depend on each other for routing packets. However, cooperation in such operations consumes nodes recourses such as battery and bandwidth. Therefore, it is necessary to design incentive mechanisms to enforce nodes to forward packets when the source and destination of the packet are other nodes. We study routing in wireless networks from a game theoretic view point. Based on this view, the network consists of greedy and selfish nodes who accept payments for forwarding data for other nodes if the payments cover their individual costs incurred by forwarding data. Also, route falsification attacks are easy to...
Linear temporal logic of constraint automata
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 972-975 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Izadi, M ; Sharif University of Technology
2008
Abstract
Constraint automata are formalisms to describe the behavior and possible data flow in coordination models. In this paper we introduce a linear time temporal logic, called temporal logic of steps (TLS), for specifying the executions of constraint automata. TLS is the first attempt in presenting a linear temporal logic for constraint automata. Having TLS in hand, we are able to design model checking algorithms for verification of concurrent systems modeled by constraint automata. © 2008 Springer-Verlag
An approach for semantic web query approximation based on domain knowledge and user preferences
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 443-452 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Piri, R ; Abolhassani, H ; Sharif University of Technology
2008
Abstract
One of the most important services in the Semantic Web is the Reasoning Service. According to the Semantic Web requirements, reasoning under time pressure or other restrictions is needed; and, reasoning which is not 'perfect' but instead 'good enough' for given tasks is acceptable. One of the approaches for the improvement of reasoning performance is approximation; of course, there is an effort for raising more precise approximations. One of the fields in which approximation seems to be useful is query. So far, all of the approximation strategies introduced for conjunctive queries just consider the query's structure. In this paper, a semantic approach for conjunctive query approximation...
Polymorphism-aware common bus in an object-oriented ASIP
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 115-122 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Hessabi, S ; Sharif University of Technology
2008
Abstract
Polymorphism and dynamic binding of processing units to methods are key features in object-oriented (OO) processors. Since Network-on-Chip is not available for most platform implementation, common bus can be a good approach to interconnect processing units of an OO processor. In this paper, we present a network protocol with little overhead for common bus that does not violate the polymorphism method calls in an OO processor. Moreover, we show the appropriateness of our solution by presenting a real-world application. © 2008 Springer-Verlag
CEBAC: A decentralized cooperation enforcement based access control framework in MANETs
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 427-434 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Mashayekhi, H ; Movaghar, A ; Jalili, R ; Sharif University of Technology
2008
Abstract
Prevention of unauthorized access to services in mobile ad hoc networks is a more sophisticated problem than access control in other networks, due to interconnection facilities and lack of any fixed network infrastructure in such networks. Therefore regarding the nature of these networks, controlling access to services should be in a decentralized manner providing good performance and preserving network security. In this paper, we propose a decentralized Cooperation Enforcement Based Access Control (CEBAC) framework for mobile ad hoc networks. CEBAC comprises several groups of Service Authorizers, each issuing Credentials for access to a specific kind of services. The User Authorization for...
Using social annotations for search results clustering
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 976-980 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Khayyamian, M ; Abolhassani, H ; Sharif University of Technology
2008
Abstract
Clustering search results helps the user to overview returned results and to focus on the desired clusters. Most of search result clustering methods use title, URL and snippets returned by a search engine as the source of information for creating the clusters. In this paper we propose a new method for search results clustering (SRC) which uses social annotations as the main source of information about web pages. Social annotations are high-level descriptions for web pages and as the experiments show, clustering based on social annotations yields good clusters with informative labels. © 2008 Springer-Verlag
A novel semi-supervised clustering algorithm for finding clusters of arbitrary shapes
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 876-879 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Bagheri Shouraki, S ; Sharif University of Technology
2008
Abstract
Recently, several algorithms have been introduced for enhancing clustering quality by using supervision in the form of constraints. These algorithms typically utilize the pair wise constraints to either modify the clustering objective function or to learn the clustering distance measure. Very few of these algorithms show the ability of discovering clusters of different shapes along with satisfying the provided constraints. In this paper, a novel semi-supervised clustering algorithm is introduced that uses the side information and finds clusters of arbitrary shapes. This algorithm uses a two-stage clustering approach satisfying the pair wise constraints. In the first stage, the data points...
Object-based video coding for distance learning using stereo cameras
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 176-185 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Bagheri, M ; Kasaei, S ; Sharif University of Technology
2008
Abstract
This paper presents a novel video encoding method for cooperative educational dissemination systems. Taking into consideration the inherent characteristics of stereo cameras framework in our educational videos and the ability of determining objects in different depths in a scene, we have proposed a novel object-based video encoding based on "sprite coding" that supports the MPEG-4 Version 1 Main profile in order to transfer distance learning videos across narrow-band transmission links such as the Internet. This paper proposes a multi-layer video object layer generation scheme with foreground moving object extraction and background sprite generation using stereo camera property. The...
Modeling routing protocols in ad hoc networks
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 419-426 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Movaghar, A ; Sharif University of Technology
2008
Abstract
Regarding increasing popularity of Ad hoc networks, the routing protocols employed in these networks should be validated before deployment. Formal methods are used nowadays to find defects in protocols specification. In this paper, we explain different methods of formal modeling and verification of routing protocols of ad hoc networks. We derive the key concepts that are vital in modeling ad hoc network protocols and then modify process algebra, appropriate for verifying protocols at network layer. This process algebra implements mobility behaviors of underlying infrastructure implicitly in the semantics of broadcasting. The semantics of broadcast communication also abstracts away the...
Challenges in using peer-to-peer structures in order to design a large-scale web search engine
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 461-468 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Movaghar, A ; Sharif University of Technology
2008
Abstract
One of the distributed solutions for scaling Web Search Engines (WSEs) may be peer-to-peer (P2P) structures. P2P structures are successfully being used in many systems with lower cost than ordinary distributed solutions. However, the fact that they can also be beneficial for large-scale WSEs is still a controversial subject. In this paper, we introduce challenges in using P2P structures to design a large-scale WSE. Considering different types of P2P systems, we introduce possible P2P models for this purpose. Using some quantitative evaluation, we compare these models from different aspects to find out which one is the best in order to construct a large-scale WSE. Our studies indicate that...
Directing the search in the fast forward planning
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 857-861 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Ghassem Sani, G. R ; Sharif University of Technology
2008
Abstract
In this paper, we introduce DiFF, a novel extension of the Fast Forward (FF) planning system. FF is a domain independent planner that employs a forward heuristic search. Its search strategy is an enforced form of hill climbing. In order to move to a more promising state, FF evaluates successor states without any particular order. In this paper, we introduce a new form of the enforced hill climbing, which we call directed enforced hill climbing, to enhance the efficiency of Fast Forward planning. This strategy evaluates successor states in the order recommended by an adaptive heuristic function. Our experimental results in several planning domains show a significant improvement in the...
Inferring trust using relation extraction in heterogeneous social networks
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 867-870 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Akhoondi, M ; Abolhassani, H ; Sharif University of Technology
2008
Abstract
People use trust to cope with uncertainty which is a result of the free will of others. Previous approaches for inferring trust have focused on homogeneous relationships and attempted to infer missing information based on existing information in a single relationship. In this paper we propose using methods of social network analysis to infer trust in a heterogeneous social network. We have extended the problem of relation extraction and allowed using any type of binary operator on matrixes, whereas previous work have focused on linear combination of base matrixes (the only allowed operator was summation of two matrixes). We present two genetic algorithms which use ordinary numerical and...
Energy adaptive cluster-head selection for wireless sensor networks using center of energy mass
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 130-137 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Manzuri Shalmani, M. T ; Sharif University of Technology
2008
Abstract
A set of small battery-operated sensors with low-power transceivers that can automatically form a network and collect some desired physical characteristics of the environment is called a wireless sensor network. The communications must be designed to conserve the limited energy resources of the sensors [14].By clustering sensors we can save energy. In this paper, we introduce a new concept called "Center of Energy Mass" which is a combination of both energy level and location of the nodes which is used to form the new factor of "distance of the nodes to the CEM ".Distance of the nodes to the CEM is used together with Probability Density Function of the normal distribution in optimizing...
Efficient VLSI layout of WK-recursive and WK-pyramid interconnection networks
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 123-129 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
2008
Abstract
The WK-recursive mesh and WK-pyramid networks are recursively-defined hierarchical interconnection networks with excellent properties which well idealize them as alternatives for mesh and traditional pyramid interconnection topologies. They have received much attention due to their favorable attributes such as small diameter, large connectivity, and high degree of scalability and expandability. In this paper, we deal with packagibility and layout area of these networks. These properties are of great importance in the implementation of interconnection networks on chips. We show that WK-recursive, mesh-pyramid and WK-pyramid networks can be laid out in an area of O(N2) which is the optimal...
An approximation algorithm for the k-level uncapacitated facility location problem with penalties
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 41-49 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Niknafs, A ; Ghodsi, M ; Sharif University of Technology
2008
Abstract
The k-level Uncapacitated Facility Location (UFL) problem is a generalization of the UFL and the k-median problems. A significant shortcoming of the classical UFL problem is that often a few very distant customers, known as outliers, can leave an undesirable effect on the final solution. This deficiency is considered in a new variant called UFL with outliers, in which, in contrast to the other problems that need all of the customers to be serviced, there is no need to service the entire set of customers. UFL with Penalties (UFLWP) is a variant of the UFL with outliers problem in which we will decide on whether to provide service for each customer and pay the connection cost, or to reject it...
A robust and efficient SIP authentication scheme
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 551-558 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Darmani, Y ; Jalili, R ; Nourani, M ; Sharif University of Technology
2008
Abstract
Apart from its security, an SIP (Session Initiation Protocol) authentication protocol shall be efficient; because in order to replace traditional telephony, VoIP services have to offer enough security and QoS compared to PSTN services. Recently, Srinivasan et al. proposed an efficient SIP authentication scheme. The low delay overhead introduced by their scheme, causes the total call setup time to be well within the acceptable limit recommended by ITU-T. Based on their work, this paper proposes an SIP authentication scheme. In both schemes, the end users are authenticated with the proxy server in their domain using the registrar server. Comparing with the Srinivasan et al.'s scheme, our...
Involving computer science students in real-world problems
, Article ITI 2008 30th International Conference on Information Technology Interfaces, Cavtat/Dubrovnik, 23 June 2008 through 26 June 2008 ; 2008 , Pages 569-573 ; 13301012 (ISSN) ; 9789537138127 (ISBN) ; Shirali ShahrezaMohammad, M ; Sharif University of Technology
2008
Abstract
Today, many students are study computer science. Although they study different courses, they rarely do homework or projects related to real world problems. In this paper, we design a project to show some of the problems which are occured during implementing a real word project to the students. In this project, the students are asked to implement the FFT (Fast Fourier Transform) algorithm on a personal computer and then port the program to a smartphone using J2ME (Java 2 Micro Edition) programming language. By doing this project, the undergraduate computer science students will become familiar with the limitations of small devices such as smartphones. They also learn the process of porting a...
Symmetric bursting behaviors in the generalized FitzHugh-Nagumo model
, Article Biological Cybernetics ; Volume 107, Issue 4 , 2013 , Pages 465-476 ; 03401200 (ISSN) ; Fallah, H ; Razvan, M. R ; Sharif University of Technology
2013
Abstract
In the current paper, we have investigated the generalized FitzHugh-Nagumo model. We have shown that symmetric bursting behaviors of different types could be observed in this model with an appropriate recovery term. A modified version of this system is used to construct bursting activities. Furthermore, we have shown some numerical examples of delayed Hopf bifurcation and canard phenomenon in the symmetric bursting of super-Hopf/homoclinic type near its super-Hopf and homoclinic bifurcations, respectively
A constant factor approximation for minimum λ-edge-connected k-subgraph with metric costs
, Article SIAM Journal on Discrete Mathematics ; Volume 25, Issue 3 , 2011 , Pages 1089-1102 ; 08954801 (ISSN) ; Salavatipour, M. R ; Sharif University of Technology
Abstract
In the (k, λ)-subgraph problem, we are given an undirected graph G = (V,E) with edge costs and two positive integers k and λ, and the goal is to find a minimum cost simple λ-edge-connected subgraph of G with at least k nodes. This generalizes several classical problems, such as the minimum cost k-spanning tree problem, or k-MST (which is a (k, 1)-subgraph), and the minimum cost λ-edge-connected spanning subgraph (which is a (|V(G)|, λ)-subgraph). The only previously known results on this problem [L. C. Lau, J. S. Naor, M. R. Salavatipour, and M. Singh, SIAM J. Comput., 39 (2009), pp. 1062-1087], [C. Chekuri and N. Korula, in Proceedings of the IARCS Annual Conference on Foundations of...