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Total 142 records

#### A class of ball-and-bin problems and its application to mesh networks

, Article 2003 10th IEEE International Conference on Electronics, Circuits and Systems, ICECS2003, Sharjah, 14 December 2003 through 17 December 2003 ; Volume 3 , 2003 , Pages 1038-1041 ; 0780381637 (ISBN); 9780780381636 (ISBN) ; Khonsari, A ; Sharif University of Technology
2003

Abstract

Non-recursive and explicit expressions for calculating the number of ways to distribute n indistinguishable balls into m distinguishable bins with different capacities have been derived. Similar expression for the special case where bins have the same capacity was previously reported in the literature. Theses expressions can be used to study network graphs with grid structures. In this line, we have derived some topological properties of meshes, furnishing some expressions to calculate the surface area and volume of radial spheres in the mesh network. © 2003 IEEE

#### Finite-time consensus in undirected/directed network topologies

, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 5 , 2010 , Pages 1-6 ; 9780791849194 (ISBN) ; Sayyaadi, H ; Sharif University of Technology
2010

Abstract

The main contribution of this paper is to introduce a novel non-Lipschitz protocol that guarantees consensus in finite-time domain. Its convergence in networks with both unidirectional and bidirectional links is investigated via Lyapunov Theorem approach. It is also proved that final agreement value is equal to average of agents' states for the bidirectional communication case. In addition effects of communication time-delay on stability are assessed and two other continuous Lipschitz protocols are also analyzed

#### Some topological properties of star graphs: The surface area and volume

, Article Discrete Mathematics ; Volume 309, Issue 3 , 2009 , Pages 560-569 ; 0012365X (ISSN) ; Sarbazi Azad, H ; Akl, S. G ; Sharif University of Technology
2009

Abstract

The star graph, as an interesting network topology, has been extensively studied in the past. In this paper, we address some of the combinatorial properties of the star graph. In particular, we consider the problem of calculating the surface area and volume of the star graph, and thus answering an open problem previously posed in the literature. The surface area of a sphere with radius i in a graph is the number of nodes in the graph whose distance from a given node is exactly i. The volume of a sphere with radius i in a graph is the number of nodes within distance i from the given node. In this paper, we derive explicit expressions to calculate the surface area and volume in the star graph....

#### On the topological properties of grid-based interconnection networks: Surface area and volume of radial spheres

, Article Computer Journal ; Vol. 54, issue. 5 , 2011 , p. 726-737 ; ISSN: 00104620 ; Khonsari, A ; Ould-Khaoua, M ; Sharif University of Technology
Abstract

Grid-based networks (or grids for short), such as meshes and tori, have been the underlying topology for many multicomputers, and have been extensively studied in the past as a graph topology. In this paper, we investigate some topological properties of grids without boundary wrap-around (meshes) and with boundary wrap-around (tori). In particular, we study the problem of finding the number of nodes located at/within a given distance from a given node (surface area/volume) in the network and derive some expressions for computing such a number. Furthermore, we provide similar expressions that improve on previous results already reported in the literature for some special cases of grids,...

#### Bandwidth adapted hierarchical multicast overlay

, Article Proceedings - 5th International Multi-Conference on Computing in the Global Information Technology, ICCGI 2010, 20 September 2010 through 25 September 2010 ; 2010 , Pages 262-267 ; 9780769541815 (ISBN) ; Movaghar, A ; Khodaparast, A. A ; Sharif University of Technology
Abstract

As the infrastructure-centric model of peer-to-peer streaming, recent overlay construction schemes compose a hierarchical topology of peers by grouping them into clusters. There is a server in each cluster that receives data from the source and relays it to its cluster members. In this paper, we propose an alternative infrastructure-centric peer-to-peer framework called BAHMO that constructs a hierarchical multicast tree. BAHMO does not utilize server bandwidth and rely only on peer bandwidth for data transfers. It achieves both the stability of the infrastructure-centric model and the bandwidth efficiency of the fully-distributed model. Bandwidth assignment for inter-cluster data transfers...

#### A new scheme on recovery from failure in NICE overlay protocol

, Article 1st International Conference on Scalable Information Systems, InfoScale '06, Hong Kong, 30 May 2006 through 1 June 2006 ; Volume 152 , 2006 ; 1595934286 (ISBN); 9781595934284 (ISBN) ; Barghi, S ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
2006

Abstract

Overlay networks have been an active area of research for the past few years. The control overhead and the recovery from failure are the two important issues in the topology aware embedded overlay networks. In this research, we have introduced an enhanced version of the NICE protocol, called resilient NICE (R-NICE) that reduces the control overhead significantly. Furthermore, by saving the join path for an end host, the time and overhead of rejoining for isolated nodes have also been reduced. This will cause the clusters and consequently the overall network to become more stable and the effect of a node failure become localized. Our experimental results have confirmed the superior...

#### The stretched-hypercube: A VLSI efficient network topology

, Article 8th International Symposium on Parallel Architectures, Algorithms and Networks, I-SPAN 2005, Las Vegas, NV, 7 December 2005 through 9 December 2005 ; Volume 2005 , 2005 , Pages 462-467 ; 0769525091 (ISBN); 9780769525099 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
2005

Abstract

In this paper, we introduce a new class of interconnection networks for multiprocessor systems which we refer to as Stretched-Hypercubes, or shortly the Stretched-Cube networks. These networks are obtained by replacing an edge of the well-known hypercube network with an array of processors. Two interesting features of the proposed topology are its area-efficient VLSI layout and superior scalability over the traditional hypercube network. Some topological properties of the proposed network are studied. In addition, an area-efficient VLSI layout for the stretched-cube is suggested and some comparisons between the proposed network and previously studied networks such as the star and hypercube...

#### On some combinatorial properties of the star graph

, Article 8th International Symposium on Parallel Architectures, Algorithms and Networks, I-SPAN 2005, Las Vegas, NV, 7 December 2005 through 9 December 2005 ; Volume 2005 , 2005 , Pages 6-11 ; 0769525091 (ISBN); 9780769525099 (ISBN) ; Sarbazi Azad, H ; Akl, S. G ; Sharif University of Technology
IEEE Computer Society
2005

Abstract

The star graph, as an interesting network topology, has been extensively studied in the past. In this paper, we address some of the combinatorial properties of the star graph. In particular, we consider the problem of calculating the surface area of the star graph, answering an open problem previously posed in [12]. © 2005 IEEE

#### Transmission Expansion Planning Considering Network Topology Optimization

, M.Sc. Thesis Sharif University of Technology ; Fotuhi-Firuzabad, Mahmud (Supervisor)
Abstract

With increasing demand levels in recent years, transmission congestion is considered as one of the most important power system constraints. This limitation can result in higher operational costs and load curtailment. Furthermore, in power systems with high penetration of wind power, a significant amount of wind curtailment may occur due to congestion of transmission lines. Thus, in order to guarantee a reliable and economic operation of the power system, new transmission lines should be constructed with a rational plan. Very high investment costs are required for building new transmission lines to meet the growing demand. This fact as well as the other associated difficulties emphasize the...

#### Modeling the effects of hot-spot traffic load on the performance of wormhole-switched hypermeshes

, Article Computers and Electrical Engineering ; Vol. 37, issue. 1 , 2011 , p. 1-23 ; ISSN: 00457906 ; Sarbazi-Azad, H ; Nayebi, A ; Navi, K ; Sharif University of Technology
Abstract

Hypermesh is a promising network topology and is suitable for a range of network-based computing systems. Although there are few models reported for hypermeshes with uniform traffic pattern, no analytical model has been reported to deal with hot-spot traffic. Since many parallel applications exhibit non-uniform traffic patterns such as hot-spots, uniform traffic assumption is not always justifiable in practice. In this study, we propose a new analytical model to predict the mean message latency in wormhole-switched hypermeshes in the presence of hot-spot traffic. The proposed model can also calculate the mean latency under uniform traffic load when the hot-spot ratio is set to zero....

#### Adaptive flocking control of nonlinear multi-agent systems with directed switching topologies and saturation constraints

, Article Journal of the Franklin Institute ; Volume 350, Issue 6 , August , 2013 , Pages 1545-1561 ; 00160032 (ISSN) ; Haeri, M ; Sharif University of Technology
2013

Abstract

In this paper, we propose and analyze flocking algorithms in a network of second-order agents with bounded control inputs and nonlinear intrinsic dynamics. We consider a general switching network topology, for velocity information exchange, rather than undirected or fixed directed network topology with a directed spanning tree. The proposed adaptive controller architecture applies a leader-following strategy in which the pinning scheme is defined based on the interaction topology. Finally, some examples are presented to illustrate the theoretical results

#### A novel utilization of wireless sensor networks as data acquisition system in smart grids

, Article Advanced Materials Research, 16 September 2011 through 18 September 2011 ; Volume 433-440 , September , 2012 , Pages 6725-6730 ; 10226680 (ISSN) ; 9783037853191 (ISBN) ; Daraei, M. H ; Rezaei, J ; Siahkoohi, A ; Sharif University of Technology
2012

Abstract

In this paper, after studying the demands and requirements of a perfect smart grid and specifications of network topology and sensor nodes utilized in a Wireless Sensor Network [WSN], a manipulated version of them is proposed to be combined with smart grid in order to improve the data acquisition step, increase the security and facilitate the process of information and desired commands from users. We will take the advantage of computer simulations to illustrate improved capacity and speed of this method. Finally, we will analyze the advantages of employing this proposed structure in a smart grid

#### Modeling of osmotic pressure of aqueous poly(ethylene glycol) solutions using the artificial neural network and free volume flory huggins model

, Article Journal of Dispersion Science and Technology ; Volume 32, Issue 7 , 2011 , Pages 1054-1059 ; 01932691 (ISSN) ; Pazuki, G. R ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
2011

Abstract

In this work, the modified Flory-Huggins coupled with the free-volume concept and the artificial neural network models were used to obtain the osmotic pressure of aqueous poly(ethylene glycol) solutions. In the artificial neural network, the osmotic pressure of aqueous poly(ethylene glycol) solutions depends on temperature, molecular weight and the mole fractions of poly(ethylene glycol) in aqueous solution. The network topology is optimized and the (3-1-1) architecture is found using optimization of an objective function with batch back propagation (BBP) method for 134 experimental data points. The results obtained from the neural network in obtaining of the osmotic pressure of aqueous...

#### Modeling the effects of hot-spot traffic load on the performance of wormhole-switched hypermeshes

, Article Computers and Electrical Engineering ; Volume 37, Issue 1 , 2011 , Pages 1-23 ; 00457906 (ISSN) ; Sarbazi Azad, H ; Nayebi, A ; Navi, K ; Sharif University of Technology
Abstract

Hypermesh is a promising network topology and is suitable for a range of network-based computing systems. Although there are few models reported for hypermeshes with uniform traffic pattern, no analytical model has been reported to deal with hot-spot traffic. Since many parallel applications exhibit non-uniform traffic patterns such as hot-spots, uniform traffic assumption is not always justifiable in practice. In this study, we propose a new analytical model to predict the mean message latency in wormhole-switched hypermeshes in the presence of hot-spot traffic. The proposed model can also calculate the mean latency under uniform traffic load when the hot-spot ratio is set to zero....

#### Layeredcast - A hybrid peer-to-peer live layered video streaming protocol

, Article 2010 5th International Symposium on Telecommunications, IST 2010, 4 December 2010 through 6 December 2010 ; 2010 , Pages 663-668 ; 9781424481835 (ISBN) ; Motamedi, R ; Rabiee, H. R ; Khansari, M ; Sharif University of Technology
Abstract

Peer-to-Peer overlay networks are an attractive foundation for video streaming. However, live Peer-to-Peer media streaming systems face many challenges such as bandwidth heterogeneity, node churn, and selfish nodes. Although many tree based and mesh based streaming protocols have been proposed, each has its own drawbacks such as unreliability and unfairness in tree based and long startup delay and complex scheduling in mesh based protocols. In this paper, we propose a new video streaming protocol called LayeredCast main features of which are: 1) Hybrid: Drawbacks of the simple approaches are compensated using a hybrid of mesh and tree overlays. 2) Layered Video: Provides an adaptive scheme...

#### Multi-server coded caching

, Article IEEE Transactions on Information Theory ; Volume 62, Issue 12 , 2016 , Pages 7253-7271 ; 00189448 (ISSN) ; Motahari, S. A ; Khalaj, B. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016

Abstract

In this paper, we consider multiple cache-enabled clients connected to multiple servers through an intermediate network. We design several topology-aware coding strategies for such networks. Based on the topology richness of the intermediate network, and types of coding operations at internal nodes, we define three classes of networks, namely, dedicated, flexible, and linear networks. For each class, we propose an achievable coding scheme, analyze its coding delay, and also compare it with an information theoretic lower bound. For flexible networks, we show that our scheme is order-optimal in terms of coding delay and, interestingly, the optimal memory-delay curve is achieved in certain...

#### Impact of reliability considerations on network topology optimization

, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 1215-1220 ; 9781538649169 (ISBN) ; Fotuhi Firuzabad, M ; Farzin, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018

Abstract

Optimal transmission switching (OTS) along with optimal bus-bar switching, also known as network topology optimization (NTO), has been previously proposed and utilized as a powerful tool to reduce operational costs. However, operational constraints and reliability considerations of NTO problem have not been addressed properly. In this paper, operational constraints are integrated in NTO problem and the effect of transmission network switching on expected interruption cost (EIC) is investigated. Moreover, a novel approach based on pool of solutions approach is presented, which can generate various switching scenarios. In doing so, the decision maker would be able to analyze and choose the...

#### Transmission loss allocation using normalized loss weight factors

, Article 3rd International Conference on Deregulation and Restructuring and Power Technologies, DRPT 2008, Nanjing, 6 April 2008 through 9 April 2008 ; 2008 , Pages 431-435 ; 9787900714138 (ISBN) ; Ehsan, M ; Sharif University of Technology
2008

Abstract

One of the major problems in liberalized power markets is loss allocation. In this paper, a new method for allocating transmission losses to pool market participants is proposed. The proposed method is fundamentally based on Bialek's "Tracing the flow of electricity" method. The losses is allocated to market participants using the loss weight factors (LWFs) which are obtained from the square current magnitude and Z-bus matrix. The LWF method is based on a solved load flow and strongly emphasizes on current magnitude while considers network topology. The method has been implemented and tested on several networks and one sample summarized in the paper. The results show that the method has an...

#### Empirical performance evaluation of stretched hypercubes

, Article 22nd International Conference on Advanced Information Networking and Applications Workshops/Symposia, AINA 2008, Gino-wan, Okinawa, 25 March 2008 through 28 March 2008 ; 2008 , Pages 75-79 ; 1550445X (ISSN) ; 0769530966 (ISBN); 9780769530963 (ISBN) ; Sarbazi Azad, H ; IEEE Computer Society ; Sharif University of Technology
2008

Abstract

Stretched hypercube has recently been introduced as an attractive alternative to the well-known hypercube. Previous research on this network topology has mainly focused on topological properties and VLSI aspects of this network In this paper, we propose some deterministic and adaptive routing algorithms for the stretched hypercubes. The performance of stretched hypercubes using the proposed routing algorithms is then evaluated by means of simulation experiments. Experiments are reahzed under different working loads and for different network actors. © 2008 IEEE

#### ADIAN: A distributed intelligent ad-hoc network

, Article 8th International Conference on Distributed Computing and Networking, ICDCN 2006, Guwahati, 27 December 2006 through 30 December 2006 ; Volume 4308 LNCS , 2006 , Pages 27-39 ; 03029743 (ISSN); 9783540681397 (ISBN) ; Ghassem Sani, G ; Rabiee, H ; Ghanbari, M ; Dehghan, M ; Sharif University of Technology
2006

Abstract

Mobile Ad-hoc Networks are networks that have a dynamic topology without any fixed infrastructure. To transmit information in ad-hoc networks, we need robust protocols that can cope with constant changes in the network topology. The known routing protocols for mobile ad-hoc networks can be classified in two major categories: proactive routing protocols and reactive routing protocols. Proactive routing protocols keep the routes up-to-date to reduce delay in real-time applications but they have high control overhead. The control overhead in reactive routing protocols is much less than proactive routing protocols; however, the routes are discovered on demand, which is not suitable for real-time...