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electrical-networks
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Passively realisable impedance functions by using two fractional elements and some resistors
, Article IET Circuits, Devices and Systems ; Volume 12, Issue 3 , 2018 , Pages 280-285 ; 1751858X (ISSN) ; Sharif University of Technology
Institution of Engineering and Technology
2018
Abstract
Here, the necessary and sufficient conditions for realisability of a general class of impedance functions by passive electrical networks composed of two fractional element (fractional capacitor or fractional inductor) and some resistors are found. Also, a systematic procedure is proposed to obtain such passive electrical networks in the realisable cases. Moreover, by establishing a connection with the previously reported researches on the subject of inerter-based passive mechanical control, further results on the maximum number of the resistors required for passive realisation are obtained. Furthermore, a numerical example is presented to show the usefulness of the paper achievements in...
The promotion of innovation in regulated network industries
, Article International Review of Environmental and Resource Economics ; Volume 15, Issue 1-2 , 2021 , Pages 137-174 ; 19321465 (ISSN) ; Sharif University of Technology
Now Publishers Inc
2021
Abstract
The capital intensive network industries such as electricity and gas delivery infrastructures exhibit natural monopoly characteristics because of their high economy of scale relative to the size of the market. Due to the absence of direct competition in these regulated industries, infrastructure providers hardly undertake the appropriate level of innovation activities to optimise the operation and continuity of their services; a review is provided to show how different countries support innovation in the network industries. As innovation activities are costly and risky undertakings, a relevant query is how to incentivise innovation through economic regulations. This paper models three...
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...
Innovation in regulated electricity networks: Incentivising tasks with highly uncertain outcomes
, Article Competition and Regulation in Network Industries ; Volume 21, Issue 2 , 2020 , Pages 166-192 ; Peng, D ; Mirnezami, S. R ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
Traditional regulatory models of natural monopoly network utilities are designed to incentivise cost-efficiency, subject to the firm achieving a certain level of reliability. With the rise of decarbonisation as a key policy goal, facilitating innovation in electricity networks has become of vital importance. Innovation and cost-efficiency may overlap and exhibit the same risk profile. However, we show that when there is a difference in their risk profile, incentivising these two tasks using the same incentive scheme is ineffective. This means incentive regulations need to be enhanced with additional modules that take into account the level of risk to which companies are exposed to for their...
Different aspects of social network analysis
, Article 2006 IEEE/WIC/ACM International Conference on Web Intelligence, WI'06, Hong Kong, 18 December 2006 through 22 December 2006 ; 2006 , Pages 66-72 ; 0769527477 (ISBN); 9780769527475 (ISBN) ; Abolhassani, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2006
Abstract
A social network is a set of people (or organizations or other social entities) connected by a set of social relationships, such as friendship, co-working or information exchange. Social network analysis focuses on the analysis of patterns of relationships among people, organizations, states and such social entities. Social network analysis provides both a visual and a mathematical analysis of human relationships. Web can also be considered as a social network. Social networks are formed between Web pages by hyperlinking to other Web pages. In this paper a state of the art survey of the works done on social network analysis ranging from pure mathematical analyses in graphs to analyzing the...
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
Synthesis and analysis of sigma-delta modulators employing continuous-time filters
, Article Analog Integrated Circuits and Signal Processing, Dordrecht, Netherlands ; Volume 23, Issue 2 , 2000 , Pages 141-152 ; 09251030 (ISSN) ; Keramat, M ; Kielbasa, R ; Sharif University of Technology
Kluwer Academic Publishers
2000
Abstract
A methodology for analysis and synthesis of lowpass sigma-delta (∑Δ) converters is presented in this paper. This method permits the synthesis of ∑Δ modulators employing continuous-time filters from discrete-time topologies. The analysis method is based on the discretization of a continuous-time model and using a discrete simulator, which is more efficient than an analog simulator. In our analysis approach, the influence of the sample and hold block and non-idealities of the feedback DAC can be systematically modeled by discrete-time systems. Finally, a realistic design of a second-order ∑Δ modulator with a compensation of the non-ideal behavior of the DAC is given. Moreover, simulation...
Developing an Efficient Approach for Improving Operational Resilience of Power Distribution Network in Facing with Earthquake
, M.Sc. Thesis Sharif University of Technology ; Fotuhi Firuzabad, Mahmud (Supervisor)
Abstract
The design and operation of energy systems infrastructure is typically based on key reliability criteria such as system security and adequacy. Nowaday, with the rise of unexpected events and events such as floods, earthquakes, storms, and other natural phenomena can affect the performance of energy infrastructure. Given the low probability of these events, reliability studies and relevant criteria cannot guarantee that an energy infrastructure can respond well to these events. Investigating the ability of energy infrastructures to deal with these phenomena is divided into resilience studies. To overcome these challenges, this thesis has attempted to detail some of these natural events....
The design and operation of energy systems infrastructure is typically based on key reliability criteria such as system security and adequacy. Nowaday, with the rise of unexpected events and events such as floods, earthquakes, storms, and other natural phenomena can affect the performance of energy infrastructure. Given the low probability of these events, reliability studies and relevant criteria cannot guarantee that an energy infrastructure can respond well to these events. Investigating the ability of energy infrastructures to deal with these phenomena is divided into resilience studies. To overcome these challenges, this thesis has attempted to detail some of these natural events....
Technique for online tracking of a utility harmonic impedance using by synchronising the measured samples
, Article IET Generation, Transmission and Distribution ; Volume 10, Issue 5 , 2016 , Pages 1240-1247 ; 17518687 (ISSN) ; Mokhtari, H ; Sharif University of Technology
Institution of Engineering and Technology
Abstract
Utility harmonic impedance estimation is an important stage for the study and control of electrical networks power quality such as harmonic sharing determination between a utility and a customer at a point of common coupling (PCC). In this estimation, non-invasive methods, as compared with invasive methods, are more desirable since they do not need to apply intentional disturbances to the power network and can work based on natural load fluctuations. The only concern about such methods is the method accuracy. These methods require simultaneous and synchronous measurements of the voltage and current at the PCC. However, one of the causes of error in the utility harmonic impedance measurement...
Reducing power consumption in NoC design with no effect on performance and reliability
, Article 14th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2007, Marrakech, 11 December 2007 through 14 December 2007 ; 2007 , Pages 886-889 ; 1424413788 (ISBN); 9781424413782 (ISBN) ; Fazeli, M ; Miremadi, S. G ; Sharif University of Technology
2007
Abstract
High reliability, low power consumption and high performance are key objectives in the design of NoCs. These three design objectives should be considered simultaneously in order to have an optimal design. This paper proposes a method to reduce power consumption of an application specific NoC. This is done in two steps: 1) Extra virtual channels are used in the router architecture to increase the performance in an application specific NoC, and 2) The amount of the performance gain is then set to the initial point using frequency scaling technique, hence reducing the power consumption, without corruption of reliability. The simulation results show that the method can reduce the power...
Evaluation of traffic pattern effect on power consumption in mesh and torus network-on-chips
, Article 2007 International Symposium on Integrated Circuits, ISIC, Singapore, 26 September 2007 through 28 September 2007 ; 2007 , Pages 512-515 ; 1424407974 (ISBN); 9781424407972 (ISBN) ; Mirza Aghatabar, M ; Hessabi, S ; Sharif University of Technology
2007
Abstract
Technology scaling increases clock rates and die sizes; therefore, power dissipation is predicted to soon become the key limiting factor on the performance of single-chip designs. NoC as an efficient and scalable on-chip communication architecture for SoC architectures, enables integration of a large number of computational and storage blocks on a single chip. Since different applications impose different traffic models to the network, in this paper we will analyze the power and energy consumption of the most popular traffic models, i.e., Uniform, Local, HotSpot and First Matrix Transpose, in two famous and well designed topologies, mesh and torus. We will also compare these topologies with...
The effect of virtual channel organization on the performance of interconnection networks
, Article 19th IEEE International Parallel and Distributed Processing Symposium, IPDPS 2005, Denver, CO, 4 April 2005 through 8 April 2005 ; Volume 2005 , 2005 ; 0769523129 (ISBN); 0769523129 (ISBN); 9780769523125 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
2005
Abstract
Most of previous studies have assessed the performance issues for regular buffer and virtual channel organiza-tions and have not considered overall buffer size constraint. In this paper, the performance of mesh-based interconnection networks (mesh, torus and hypercube networks) under different traffic patterns (uniform, hotspot, and matrix-transpose) is studied. We investigate the effect of the number of virtual channels and their buffer lengths, on the performance of these topologies when the total buffer size associated to each physical channel (and thus router buffer size) is fixed.The results show that the optimal number of virtual channels and buffer length highly depends on the traffic...
Conditions Derivation of Implementability of Fractional-Order Functions by Passive Electrical Networks
, M.Sc. Thesis Sharif University of Technology ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
Today, the fractional-order systems are widely used in the system identification and design and implementation of control systems. By production of electrical elements with fractional-order relationship between voltage and current of their terminals, implementation of fractional-order functions with passive elements is possible. Fractional order capacitors are one of these elements. It was shown that necessary and sufficient condition for the implementation of an integer order function by passive elements is positive realness of such a function.
Like systems with integer-order, in this thesis the aim is to find corresponding conditions for implementation of fractional-order functions...
Like systems with integer-order, in this thesis the aim is to find corresponding conditions for implementation of fractional-order functions...
Application specific router architectures for NoCs: An efficiency and power consumption analysis
, Article Mechatronics ; Vol. 22, issue. 5 , August , 2012 , pp. 531-537 ; ISSN: 9574158 ; Sarbazi-Azad, H ; Sharif University of Technology
Abstract
Networks on chip (NoC) have been proposed as a solution to mitigate complex on-chip communication problems. NoCs are composed of intellectual properties (IP) which are interconnected by on-chip switching fabrics. A step in the design process of NoCs is hardware virtualization which is mapping the IP cores onto the tiles of a chip. The communication among the IP cores greatly affects the performance and power consumption of NoCs which itself is deeply related to the placement of IPs onto the tiles of the network. Different mapping algorithms have been proposed for NoCs which allocate a set of IPs to given network topologies. In these mapping algorithms, there is a restriction which limits IPs...
Connectedness of users-items networks and recommender systems
, Article Applied Mathematics and Computation ; Vol. 243 , 2014 , Pages 578-584 ; ISSN: 00963003 ; Jalili, M ; Sharif University of Technology
Abstract
Recommender systems have become an important issue in network science. Collaborative filtering and its variants are the most widely used approaches for building recommender systems, which have received great attention in both academia and industry. In this paper, we studied the relationship between recommender systems and connectivity of users-items bipartite network. This results in a novel recommendation algorithm. In our method recommended items are selected based on the eigenvector corresponding to the algebraic connectivity of the graph - the second smallest eigenvalue of the Laplacian matrix. Since recommending an item to a user equals to adding a new link to the users-items bipartite...
Prediction of the noise spectrum in optoelectronic oscillators: An analytical conversion matrix approach
, Article Journal of the Optical Society of America B: Optical Physics ; Vol. 31, issue. 8 , August , 2014 , p. 1915-1925 ; ISSN: 07403224 ; Hosseini, S. E ; Banai, A ; Sharif University of Technology
Abstract
In this paper an analytical formulation based on the conversion matrix approach for characterizing the oscillator noise spectra as well as the phase and amplitude noise spectra for a single-loop optoelectronic oscillator (OEO) is presented. The validity of this approach is verified by comparing our results regarding the noise spectra of the OEO against the results of two references in the literature. The first reference presents simulation results, and the second reference presents both simulation and measurement results, and good agreement is seen between the results of the new method and those of the references. The advantage of the new approach is the simplicity of the theory as well as...
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
Analysis of digital DSP blocks using GDI technology
, Article 2010 International Conference on Computer Information Systems and Industrial Management Applications, CISIM 2010, 8 October 2010 through 10 October 2010, Krackow ; 2010 , Pages 90-95 ; 9781424478170 (ISBN) ; Mortazavi, M ; Faed, A ; Sharif University of Technology
2010
Abstract
In parallel with enhancements in the technology of integrated circuits, transistors are implemented in silicon. Though the price is reduced; design is more complicated, which create the efficiency and power consumption. The reason why modern GDI-based circuit is the focus of attention is that in designing digital circuit, less power is required while more efficiency is obtained. Lowering the complexity of logic circuit can bring about reduction of power consumption, propagation delay and decrease circuit space. GDI-based integrated circuit resembles MOSFET transistors but have fewer transistors and higher performance capability. This study addresses two main areas which are Studying and...
A parallel clustering algorithm on the star graph and its performance
, Article Mathematical and Computer Modelling ; Volume 58, Issue 3-4 , 2013 , Pages 880-891 ; 08957177 (ISSN) ; Zarandi, H. R ; Fazeli, M ; Sharif University of Technology
Abstract
In this paper, a parallel algorithm is presented for data clustering on a multicomputer with star topology. This algorithm is fast and requires a small amount of memory per processing element, which makes it even suitable for SIMD implementation. The proposed parallel algorithm completes in O(K+S2-T2) steps for a clustering problem of N data patterns with M features per pattern and K clusters where S and T are the minimum numbers such that NM≤S! and KM≤T!, on the S-dimensional star graph