Search for: electrical-engineering
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    Educational robot for principles of electrical engineering

    , Article Scientia Iranica ; Volume 25, Issue 3D , 2018 , Pages 1582-1592 ; 10263098 (ISSN) Rahnavard, M ; Alavi, M. H ; Khorasani, S ; Vakilian, M ; Fardmanesh, M ; Sharif University of Technology
    Sharif University of Technology  2018
    An educational robot is described, which is designed and constructed for use in the laboratory of Principles of Electrical Engineering. The discrete nature of design, conforming to a simple block strategy, allows for fairly easy introduction of basic and fundamental concepts of Electrical Engineering to the freshman students, including control, actuation, wireless signal transmission, and analogue/digital conversions. Each block or module represents one or few engineering ideas and helps the students to understand the interplay and connection between system divisions, and enhance their creative thinking. Circuits are designed and implemented such that both structure and functionality of each... 

    On the coding advantages of the quasi-orthogonal space-frequency block codes

    , Article IET Communications ; Vol. 8, Issue. 4 , 2014 , Pages 525-529 ; ISSN: 17518628 Shahabinejad, M ; Morsali, A ; Talebi, S ; Shahabinejad, M ; Sharif University of Technology
    In this study, the authors show that the coding advantage (CA) of quasi-orthogonal space-frequency block codes (QOSFBCs) could be decomposed into two parts, namely intrinsic CA (ICA) and extrinsic CA (ECA). Then, by using the ICA, the authors demonstrate that the optimum precoder of the QOSFBCs could be analytically derived without any requirement of the exhaustive search. Then, by improving the ECA, the authors enhance performances of the QOSFBCs efficiently - up to 4dB. Finally, the authors show that a very fast optimisation process for the QOSFBCs is viable over any arbitrary frequency-selective channel  

    Compensation by fractional-order phase-lead/lag compensators

    , Article IET Control Theory and Applications ; Volume 8, Issue 5 , 2014 , Pages 319-329 ; ISSN: 17518644 Tavazoei, M. S ; Tavakoli Kakhki, M ; Sharif University of Technology
    This study deals with a generalised version of lead/lag compensators known as fractional-order lead/lag compensators. Exact and simple formulas are found for designing this introduced type of fractional-order compensators in order to provide the required magnitude and phase at a given frequency. Also, the region in the phase-magnitude plane, which is accessible by these compensators, is analytically found. Moreover, numerical examples and experimental results are presented to show the applicability of the achievements of this study in control system design  

    On type number concept in fractional-order systems

    , Article Automatica ; Volume 49, Issue 1 , January , 2013 , Pages 301-304 ; 00051098 (ISSN) Tavazoei, M. S ; Sharif University of Technology
    In this note, the type number concept is defined for fractional-order systems. Based on this definition, it is shown that fractional-order systems having type numbers more than 1 can not track some classes of reference inputs without any overshoot  

    Conditions on polynomials involved in admittance functions passively realizable by using rlc and two fractional elements

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 67, Issue 6 , 2020 , Pages 999-1003 Tavazoei, M. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    This brief deals with finding the necessary conditions which should be met by the polynomials appeared in the admittance functions passively realizable by using RLC components and two fractional elements. These conditions include structurally necessary equalities/specifications and positive-realness-based inequalities which should be satisfied by the involved polynomials. In the realizable cases, the acceptable region for choosing the pseudo inductances/capacitances of fractional elements is found from the obtained conditions. © 2004-2012 IEEE  

    Advances in heuristic signal processing and applications

    , Book ; Chatterjee, Amitava ; Nobahari, Hadi ; Siarry, Patrick
    Springer  2013
    There have been significant developments in the design and application of algorithms for both one-dimensional signal processing and multidimensional signal processing, namely image and video processing, with the recent focus changing from a step-by-step procedure of designing the algorithm first and following up with in-depth analysis and performance improvement to instead applying heuristic-based methods to solve signal-processing problems. In this book the contributing authors demonstrate both general-purpose algorithms and those aimed at solving specialized application problems, with a special emphasis on heuristic iterative optimization methods employing modern evolutionary and swarm... 

    Static and dynamic source separation using nonnegative factorizations: A unified view

    , Article IEEE Signal Processing Magazine ; Vol. 31, issue. 3 , 2014 , pp. 66-75 ; ISSN: 1053-5888 Smaragdis, P ; Fevotte, C ; Mysore, G. J ; Mohammadiha, N ; Hoffman, M ; Sharif University of Technology
    Source separation models that make use of nonnegativity in their parameters have been gaining increasing popularity in the last few years, spawning a significant number of publications on the topic. Although these techniques are conceptually similar to other matrix decompositions, they are surprisingly more effective in extracting perceptually meaningful sources from complex mixtures. In this article, we will examine the various methodologies and extensions that make up this family of approaches and present them under a unified framework. We will begin with a short description of the basic concepts and in the subsequent sections we will delve in more details and explore some of the latest... 

    Multiple-access channel with correlated states and cooperating encoders

    , Article IET Communications ; Volume 6, Issue 13 , 2012 , Pages 1857-1867 ; 17518628 (ISSN) Emadi, M. J ; Zamanighomi, M ; Aref, M. R ; Sharif University of Technology
    IET  2012
    In this study, a two-user discrete memoryless multiple-access channel with two correlated states known non-causally at the corresponding encoder is considered. Each encoder transmits a message independent of the other encoder's and tries to cooperate with it. To consider cooperative encoders, it is assumed that each encoder strictly-causally receives and finds out the other encoder's transmitted signals and tries to cooperate with the other encoder by transmitting its message. A special case is also studied in which the common part of the states is known at the both encoders, resulting in a larger rate region. For these two scenarios, achievable rate regions are derived using a combination... 

    A Minimization-Projection (MP) approach for blind separating convolutive mixtures

    , Article Proceedings - IEEE International Conference on Acoustics, Speech, and Signal Processing, Montreal, Que, 17 May 2004 through 21 May 2004 ; Volume 5 , 2004 , Pages V-533-V-536 ; 15206149 (ISSN) Babaie-Zadeh, M ; Jutten, C ; Nayebi, K ; Sharif University of Technology
    In this paper, a new algorithm for blind source separation in convolutive mixtures, based on minimizing the mutual information of the outputs, is proposed. This minimization is done using a recently proposed Minimization-Projection (MP) approach for minimizing mutual information in a parametric model. Since the minimization step of the MP approach is proved to have no local minimum, it is expected that this new algorithm has good convergence behaviours  

    Interpolation of steganographic schemes

    , Article Signal Processing ; Vol. 98 , May , 2014 , pp. 23-36 ; ISSN: 01651684 Gholampour, I ; Khosravi, K ; Sharif University of Technology
    Many high performance steganographic schemes work at a limited or sparsely distributed set of embedding rates. We have shown that some steganographic changes will be wasted as these schemes are utilized individually for messages of various lengths. To measure the wasted changes and compare different schemes in this respect, we have built a framework based on two new criteria: the Relative Change Waste (RCW) and the Expected Changes per Pixel (ECP). To decrease the wasted changes a systematic combination of schemes is introduced and proved to be equivalent to nonlinear interpolation of points in a two-dimensional space. We have proved that a special case which leads to a linear interpolation... 

    Coding advantage decomposition inequality for the space-frequency block codes

    , Article IET Communications ; Vol. 8, Issue. 4 , 2014 , Pages 500-507 ; ISSN: 17518628 Morsali, A ; Tofigh, S ; Mohammadian, Z ; Talebi, S ; Sharif University of Technology
    In this study, the authors present a new criterion which can be used to decompose the coding advantage (CA) of space-frequency block codes (SFBCs). The proposed decomposition separates the CA into two parts, called precoder-CA and channel-CA. The precoder-CA represents the effects of the precoder and the signal constellation, and can be used in the design of the precoder of SFBCs. The channel-CA, on the other hand, gives an indication of the effects of the channel characteristics, and can be utilised for optimising the permutation parameter. The authors have shown that the proposed decomposition method leads to a lower computational complexity for the optimisation procedure compared with the... 

    Distribution loss allocation for radial systems including dgs

    , Article IEEE Transactions on Power Delivery ; Vol. 29, issue. 1 , 2014 , pp. 72-80 ; ISSN: 08858977 Ghofrani-Jahromi, Z ; Mahmoodzadeh, Z ; Ehsan, M ; Sharif University of Technology
    Due to the liberalization of the electricity market and the introduction of distributed generation (DG), the importance of distribution loss allocation (LA) has increased. This paper presents a new method for distribution power LA in radial systems. The proposed method, which is based on the results of power flow and considers active and reactive power flows of lines for LA, is composed of three steps. In the first step, starting from the source nodes (i.e., the nodes whose generation is more than their load), the power loss allocated to all nodes is calculated and then the power loss allocated to the loads connected to each node is obtained. In the next step, the total power loss is... 

    A novel simultaneous reconfiguration and capacitor switching method to improve distribution networks operation

    , Article 2014 14th International Conference on Environment and Electrical Engineering, EEEIC 2014 - Conference Proceedings ; May , 2014 , pp. 295-300 ; ISBN: 9781479946617 Ameli, A ; Davari-Nejad, E ; Kamyab, F ; Vakilian, M ; Haghifam, M. R ; Sharif University of Technology
    Due to the important role that distribution systems play in quality of power delivered to the customers, there has always been a great deal of interest in investigating different methods of efficiency enhancement for these networks. Two of these methods are Feeder Reconfiguration (FR) and Capacitor Allocation (CA); both have been widely employed to reduce losses and improve several other operational characteristics in electrical power distribution systems. As in FR process the topology of the network changes, it is necessary to change some previous settings; for instance: the capacity of capacitor banks in service in each bus, after each reconfiguration process. This is due to the fact that... 

    Steady-state analysis and performance of a brushless doubly fed machine accounting for core loss

    , Article IET Electric Power Applications ; Volume 7, Issue 3 , 2013 , Pages 170-178 ; 17518660 (ISSN) Hashemnia, M. N ; Tahami, F ; Tavner, P ; Tohidi, S ; Sharif University of Technology
    In this study a steady-state equivalent circuit for a brushless doubly fed machine (BDFM), based upon earlier work, is introduced which takes account of core losses. Based upon some loss approximations, simple relationships have been derived, which show that the synchronous mode operation, in terms of core loss, of the BDFM is similar to the cascaded doubly fed machine. The slip-dependence of core loss resistances in the equivalent circuit has been investigated by applying energy conservation to derive machine steady-state torque-speed relations in the presence of core loss. Experimental speed measurements of the BDFM in the simple induction mode were used to identify the core loss... 

    Multi-attribute queries: To merge or not to merge?

    , Article Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition ; 2013 , Pages 3310-3317 ; 10636919 (ISSN) Rastegari, M ; Diba, A ; Parikh, D ; Farhadi, A ; Sharif University of Technology
    Users often have very specific visual content in mind that they are searching for. The most natural way to communicate this content to an image search engine is to use key-words that specify various properties or attributes of the content. A naive way of dealing with such multi-attribute queries is the following: train a classifier for each attribute independently, and then combine their scores on images to judge their fit to the query. We argue that this may not be the most effective or efficient approach. Conjunctions of attribute often correspond to very characteristic appearances. It would thus be beneficial to train classifiers that detect these conjunctions as a whole. But not all... 

    Improved bounds for the spectrum of interval matrices

    , Article IET Control Theory and Applications ; Volume 7, Issue 7 , 2013 , Pages 1022-1028 ; 17518644 (ISSN) Firouzbahrami, M ; Babazadeh, M ; Nobakhti, A ; Karimi, H ; Sharif University of Technology
    This study presents new sufficient conditions for Hurwitz and Schur stability of interval matrices. Tight bounds for the spectrum of interval matrices are estimated using computationally simple optimisation problems. The conservativeness is reduced further by application of ordinary similarity transformation. A necessary and sufficient vertex based criterion for the stability of a subclass of interval systems in continuous and discrete-time cases is also proposed. This enables the spectra for this class of interval systems to be determined exactly. A selection of various examples adopted from existing literature is used to demonstrate the utility of the proposed criteria  

    IGDT based risk-constrained strategic bidding of GenCos considering bilateral contracts

    , Article 2013 21st Iranian Conference on Electrical Engineering, ICEE 2013 ; 2013 ; 9781467356343 (ISBN) Kazemi, M ; Mohammadi Ivatloo, B ; Ehsan, M ; Sharif University of Technology
    A new risk-constrained bidding curve construction method is presented in this paper. A Day-ahead energy market has been chosen for competition of GenCos and the Information Gap Decision Theory (IGDT) is used for modelling the Day-ahead market price uncertainty and its corresponding risk. The bilateral contracts of the GenCo are also considered in the proposed framework. A Bi-level optimization problem is incorporated in the proposed method to guarantee a pre-specified level of revenue. The proposed IGDT based method constructs the non-decreasing bidding curve while dispatching units based on the uncertain forecasted prices of the next-day market. The verification of the proposed method is... 

    A computationally efficient direction-of-arrival estimation algorithm, robust against coherent sources and small sample size

    , Article 2013 21st Iranian Conference on Electrical Engineering, ICEE ; 2013 , 14-16 May ; 9781467356343 (ISBN) Rahmani, M ; Bastani, M. H ; Shahraeeni, S ; Sharif University of Technology
    Direction-of-arrival (DOA) estimation algorithms usually impose high computation burden and most of them are incapable of facing the coherent sources. In this paper, a new computationally efficient algorithm that is robust against the coherent sources is proposed. This method is based on a combination of the Maximum Likelihood (ML) and Orthogonal-Matching-Pursuit (OMP) algorithms. Simulation results show that the proposed algorithm has good performance in the small sample size cases and the coherency does not affect its performance  

    New SNDR enhancement techniques in pipelined ADC

    , Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 5 ; 9781467356343 (ISBN) Ghadi, M. H ; Safavi, S. M ; Sharifkhani, M ; Sharif University of Technology
    Signal to Noise and Distortion Ratio (SNDR) is widely chosen for dynamic characterization of ADC. For pipelined ADC in which the inner circuits' errors accumulate at the output, analysis of the origins of SNDR and its characterization can be very hard. However, due to a relationship between maximum INL of ADC and the distortion in its output codes, SNDR can be derived as a function of maximum INL value and its position in output codes. Utilizing this relationship, this paper develops two methods for SNDR enhancement that do not cost much power. The 50k sampled Monte-Carlo simulation in the behavioral level indicates 75% increase in the possibility of having SNDR > 60db just by utilizing... 

    Incommensurate order fractional optimal control: Application to treatment of psychiatric disorders

    , Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 5 ; 9781467356343 (ISBN) Tabatabaei, S. S ; Yazdanpanah, M. J ; Tavazoei, M. S ; Sharif University of Technology
    The main point of this paper is to present a time domain strategy for drug dosage to treat psychiatric disorders. A time domain model of emotion is obtained from an extension of a recently developed fractional nonlinear dynamic model of happiness. First, the Fractional Optimal Control law for incommensurate multi state systems is obtained. It will be then applied as an optimal drug administration procedure in the line of psychiatric disorders treatment. Results of this paper show that optimal control scheme is a proper approach to face the difficulties of analysis and control the incommensurate systems. It can be also clearly seen from the simulation results that this approach is very...