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    Comparing the stability regions for fractional-order PI controllers and their integer-order approximations

    , Article Proceedings of the IEEE Conference on Decision and Control, 15 December 2010 through 17 December 2010, Atlanta, GA ; 2010 , Pages 720-725 ; 01912216 (ISSN) ; 9781424477456 (ISBN) Rahimian, M. A ; Tavazoei, M. S ; Sharif University of Technology
    This paper proposes a scheme for computing the stable regions from which the parameters of a fractional-order PI controller can be selected. In particular, we extend a previously investigated method for plotting the stability regions of PIλ controllers to their integer-order approximations. Next we compare the two stability regions and derive their overlapping sections, which is referred to as the implementable stability region. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. The devised scheme we believe can facilitate the design procedure for fractional-order PI... 

    Development of an Integrated Solar Energy System for a Typical Educational Building

    , M.Sc. Thesis Sharif University of Technology Motavaselian, Ali Mohammad (Author) ; Saboohi, Yadollah (Supervisor)
    In the present thesis, A Computer software has been developed to evaluate technical and economic aspects of photovoltaic systems, off-grid and on-grid configuration, in urban areas where the electricity grid is accessible. As a case study the building of Energy Engineering faculty with annual demand of electricity in lighting section equals to 80048 kWh was considered. Regarding incident radiation and PV system characteristics with the aid of utilizability concept, a technical evaluation has been performed then life-cycle saving index was considered as a criterion for choosing an optimum nominal size of the system. Results show that for current electricity tariff of educational buildings ... 

    Design of dual- and quad-band E-CRLH-TLs with arbitrary phase characteristics

    , Article Progress In Electromagnetics Research M ; Vol. 35, issue , 2014 , p. 141-149 Fozi, M ; Nikmehr, S ; Ghurt-Tappeh, M.V ; Bemani, M ; Sharif University of Technology
    In this paper, extended composite right/left-handed (E-CRLH) transmission line (TL) metamaterial structures, with two left-handed (backward) and two right-handed (forward) pass bands, are investigated. Also, design procedures in order to design dual- and quad-band E-CRLH-TLs are presented in detail and the parameters of these structures are extracted by clean formulas, while satisfying arbitrary phase shifts at the operating frequencies. Finally, the dispersion and characteristic impedances of these transmission lines are derived and plotted. The results of this paper can be applied to any type of TL-based dual- and quad-band microwave component  

    A novel approach to design reversible counter rotating propeller fans

    , Article ASME 2012 Gas Turbine India Conference, GTINDIA 2012, 1 December 2012 through 1 December 2012 ; December , 2012 , Pages 265-270 ; 9780791845165 (ISBN) Abbaszadeh, M ; Parizi, P. N ; Taheri, R ; Sharif University of Technology
    Because of their high performance and unique abilities like producing none-rotating wake, Counter Rotating Propellers (C.R.P.) are being used in many advanced propulsion or ventilation systems. But due to complicated design procedure of C.R.P. fans up to now it was not possible to apply the concept in reversible systems. For the first time in this research, a new method presented to design a reversible counter rotating propeller system. This method is based on designing a basic C.R.P. by a reliable edition of blade element theory to achieve maximum performance in main rotating course and then to optimize it in order to have almost same performance in reverse rotating course. After expressing... 

    RASA: A low-cost upper-torso social robot acting as a sign language teaching assistant

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 1 November 2016 through 3 November 2016 ; Volume 9979 LNAI , 2016 , Pages 630-639 ; 03029743 (ISSN) ; 9783319474366 (ISBN) Zakipour, M ; Meghdari, A ; Alemi, M ; Sharif University of Technology
    Springer Verlag  2016
    This paper presents the design characteristics of a new robot Assistant for Social Aims (RASA), being an upper-torso humanoid robot platform currently under final stages of development. This project addresses the need for developing affordable humanoid platforms designed to be utilized in new areas of social robotics research, primarily teaching Persian Sign Language (PSL) to children with hearing disabilities. RASA is characterized by three features which are hard to find at the same time in today’s humanoid robots: its dexterous hand-arm systems enabling it to perform sign language, low development cost, and easy maintenance. In this paper, design procedures and considerations are briefly... 

    Axiomatic design of step down DC/DC converter

    , Article 2008 IEEE International Conference on Industrial Technology, IEEE ICIT 2008, Chengdu, 21 April 2008 through 24 April 2008 ; 2008 ; 9781424417063 (ISBN) Kaboli, S ; Haddadi, A ; Khaligh, A ; Sharif University of Technology
    In this paper, the axiomatic design is introduced for designing the power electronic converters. The main idea of axiomatic design is to introduce variables affecting the desired performances of the system most independently possible. The design process is presented for a Buck converter. ©2008 IEEE  

    Displacement-based seismic design using energy concept

    , Article 8th US National Conference on Earthquake Engineering 2006, San Francisco, CA, 18 April 2006 through 22 April 2006 ; Volume 4 , 2006 , Pages 1987-1996 ; 9781615670444 (ISBN) Tavallali, H ; Bakhshi, A ; Sharif University of Technology
    In this article, a new method for the seismic resistant design is introduced. At first some formulation necessary for the introduction of the proposed method is carried out. This new procedure directly deals with ductility and takes into account the amount of ultimate displacement and required strength interactively. This design procedure is verified by extensive numerical examples using some actual earthquake records. The procedure is shown to be completely safe and to reduce the amount of inherent conservatism. Moreover, it has been tried to introduce some applicable correction factors. Copyright © (2006) by Earthquake Engineering Research Institute  

    A novel dual-band transmission line with equal-phase responses

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 69, Issue 2 , 2021 , Pages 1265-1272 ; 00189480 (ISSN) Rezvani Pakdeh, M ; Tajik, A ; Fakharzadeh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    This article presents a novel dual-band transmission line (TL), consisting of a multibranch stub, which can provide equal unwrapped phases at two different frequencies. The frequency ratio can be close to one without any significant degradation in the device performance. Besides, the bandwidth of the proposed line can be manipulated at both frequencies by adjusting the design parameters. The behavior of the structure over the frequency bands is investigated theoretically, and the design procedure and relations are derived. The simulation and measurement results of a quarter-wavelength open-ended stub and a branch-line coupler (BLC) are presented and compared to verify the performance of the... 

    Robust output regulation: optimization-based synthesis and event-triggered implementation

    , Article IEEE Transactions on Automatic Control ; 2021 ; 00189286 (ISSN) Sarafraz, M. S ; Proskurnikov, A. V ; Tavazoei, M. S ; Mohajerinesfahani, P ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    We investigate the problem of practical output regulation: Design a controller that brings the system output in the vicinity of a desired target value while keeping the other variables bounded. We consider uncertain systems that are possibly nonlinear and the uncertainty of the linear part is modeled element-wise through a parametric family of matrix boxes. An optimization-based design procedures is proposed that delivers a continuous-time control and estimates the maximal regulation error. We also analyze an event-triggered emulation of this controller, which can be implemented on a digital platform, along with an explicit estimates of the regulation error. IEEE  

    Design and Modeling of a Solar Combined Cooling, Heating and Power System and it’s Validation with Empirical Results

    , M.Sc. Thesis Sharif University of Technology Yassaghi, Hamed (Author) ; Saboohi, Yadollah (Supervisor)
    Due to the growth of energy consumption the use of new technologies and efficient energy conversion is necessary. An example of efficient energy conversion technology is CCHP (Combined Cooling, Heating and Power). The aim of the present research work is to develop a model that could be applied for optimal design of a hybrid CCHP system which would be Solar Combined Cooling, Heating and Power (SCCHP). In order to do so,microturbine power system, cooling and heating equipment’s such as absorption system and heat exchanger and also solar collector have been considered as an integral part of the system. The objective of the application of the model has been to identify proper sizing of all... 

    Wide-band high-efficiency Ku-band power amplifier

    , Article IET Circuits, Devices and Systems ; Vol. 8, issue. 6 , December , 2014 , p. 583-592 ; 1751858X Yousefi, A ; Medi, A ; Sharif University of Technology
    A 37 dBm power amplifier (PA) is designed on a 0.25 μm optical T-gate pseudomorphic high electron mobility transistor (pHEMT) technology. The design of this two-stage PA along with a step-by-step design procedure is presented in this paper. This methodology can be used for design of PA in different technologies and frequencies. The PA delivers 5 W output power over the frequency band of 13-19 GHz. It shows average power-added efficiency of 37% and large signal gain of 15 dB in measurements which is consistent with simulation results. The output power and efficiency of the realised amplifier reach maximums of 37.6 dBm and 45%, respectively. Considering output power, bandwidth, chip area and... 

    Stability analysis of a single-phase phase-locked loop for power systems applications

    , Article 2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012, 2 July 2012 through 5 July 2012 ; 2012 , Pages 1383-1387 ; 9781467303828 (ISBN) Seifi, S ; Karimi, H ; Sharif University of Technology
    This paper presents the stability analysis for a single-phase phase-locked loop (PLL) for power systems applications. The dynamical equations of a previously presented single-phase PLL are systematically derived and linearized for design and stability analysis purposes. Based on the linearized model of the PLL, parameters of the loop filter and the PI controller are accurately determined. The main advantages of the PI controller are discussed as well as its design procedure. Moreover, it is shown that, unlike the conventional single-phase PLLs, the mentioned PLL does not suffer from double-frequency ripples. Simulations carried out in MATLAB and SIMULINK verify the performance of the PLL... 

    Calculating leakage inductances of pancake windings in dry-type traction transformers

    , Article ECTI-CON 2011 - 8th Electrical Engineering/ Electronics, Computer, Telecommunications and Information Technology (ECTI) Association of Thailand - Conference 2011, 17 May 2011 through 19 May 2011, Khon Kaen ; 2011 , Pages 808-811 ; 9781457704246 (ISBN) Azizian, D ; Vakilian, M ; Faiz, J ; Bigdeli, M ; Sharif University of Technology
    Calculating leakage inductances between windings of multi-winding Traction transformers is one of the most important schemes in design procedure. In this paper, analytical and finite element methods (FEM) have been introduced for electromagnetic modeling of traction transformers with four pancake split windings. Using these models, the leakage inductances between the split windings are calculated and the models have been validated with the help of experimental data gathered from a typical 4000kVA cast-resin dry-type transformer. Some reformations are employed to improve the FEM results and effects of these reformations on accuracy of the model are studied. Employing the validated models, the... 

    Robust synchronization of perturbed Chen's fractional-order chaotic systems

    , Article Communications in Nonlinear Science and Numerical Simulation ; Volume 16, Issue 2 , 2011 , Pages 1044-1051 ; 10075704 (ISSN) Asheghan, M. M ; Hamidi Beheshti, M. T ; Tavazoei, M. S ; Sharif University of Technology
    In this paper, based on a stability theorem proved for linear fractional-order systems, a scheme for robust synchronization of two perturbed fractional-order Chen systems is proposed. In the proposed scheme, both master and slave systems are considered to be involved with external disturbances having unknown values. It is analytically shown that any set of bounded external disturbances can be damped by the proposed method, where synchronization error will be forced and then kept inside a ball around the origin. Since during the design procedure the radius of this ball could be easily chosen by the designer, the synchronization can be done with any desired accuracy. The proposed method can be... 

    Development of structural shear fuse in moment resisting frames

    , Article Journal of Constructional Steel Research ; Volume 114 , November , 2015 , Pages 349-361 ; 0143974X (ISSN) Nikoukalam, M. T ; Dolatshahi, K. M ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract Codes require that the span-to-depth ratio of the beams in moment resisting frames (MRF) should be limited to guarantee the development of plastic hinges with a sufficient length at beam ends. This requirement limits the application of MRFs mostly in framed-tube structures. In the current design procedure of steel MRFs, the strength and stiffness design of the structure are coupled often leading to overdesigned structures and foundations. To overcome the abovementioned limits, in this paper a new replaceable shear structural fuse is introduced for MRFs. The fuse is a shear link designed as a sacrificial component by weakening the shear strength of a segment at the middle of the beam... 

    Stabilizing fractional-order PI and PD controllers: An integer-order implemented system approach

    , Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 224, Issue 8 , 2010 , Pages 893-903 ; 09596518 (ISSN) Rahimian, M. A ; Tavazoei, M. S ; Sharif University of Technology
    This paper proposes a scheme for computing the stable regions from which the parameters of fractional-order proportional-integral (PI) and proportional-derivative (PD) controllers can be selected. In particular, a previously investigated method for plotting the stability regions of PI λ and PDμ controllers is extended to their integer-order approximations. Next, the two stability regions are compared and their overlapping sections, referred to as the implementable stability region, are derived. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. Simulation results for two example... 

    Analysis of the power transfer to a nonlinear transmission line

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 11 , 2017 , Pages 4073-4083 ; 00189480 (ISSN) Samizadeh Nikoo, M ; Hashemi, S. M. A ; Sharif University of Technology
    The input current of a nonlinear transmission line (NLTL), driven by a step voltage pulse, was analyzed theoretically. As specific results of the analysis, two basic parameters of NLTLs were formulated for the first time: the energy injected to NLTLs and their characteristic impedance. The energy delivered to an NLTL by a square voltage source, with a series resistance of RS, is given by a closed-form formula, which depends on the NLTL parameters and the input pulse characteristics. Considering the importance of the problem of the determining the injected energy content in a wide variety of the different applications of NLTLs, the obtained result will be of great importance, facilitating the... 

    Design of dual active bridge isolated bidirectional DC converter based on current stress optimization

    , Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 247-252 ; 9781509057665 (ISBN) Yazdani, F ; Zolghadri, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Dual active bridge isolated bidirectional DC converter (DAB-IBDC) has a poor efficiency at light loads and non-unity voltage conversion ratio. In this paper the current stress of the converter is analyzed and the effect of maximum phase shift ratio and leakage inductance on the current stress of the converter is investigated. In order to increase the efficiency of the converter and reduce the current stress, the current stress optimization has been done and the design procedure is presented. Simulation results are used to validate the results of the theoretical analysis. © 2017 IEEE  

    Optimum design of coils in a dynamic wireless electric vehicle charger with misalignment compensation capability

    , Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 419-424 ; 9781509057665 (ISBN) Poorfakhraei, A ; Movaghar, G ; Tahami, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Electric vehicles have been proposed as a proper replacement for fossil fuel-powered vehicles; however, due to the limited power density of electric vehicles batteries, these cars have been facing formidable challenges, such as limited traversed distance. In recent years, dynamic wireless chargers are introduced as an adequate way of addressing this problem in the hope that dealing with this issue can lead to an increase in the popularity of electric vehicles. In this paper, a design procedure for transmitter coil of a dynamic wireless electric vehicles charger is proposed. The procedure includes selecting the best possible shape and calculating optimum size of coils for proper operation of... 

    Investigation of dynamics and vibration of a three unit pig in oil and gas pipelines

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 265-275 ; 9780791848722 (ISBN) Durali, M ; Fazeli, A ; Azimi, M ; Sharif University of Technology
    In this paper, the transient motion of a three unit intelligent Pipe Inspection Gauge (PIG) while moving across anomalies and bends inside gas/oil pipeline has been investigated. The pipeline fluid has been considered as isothermal and compressible. In addition, the pipeline itself has also been considered to be flexible. The fluid continuity and momentum equations along with the 3D multi body dynamic equations of motion of the pig comprise a system of coupled dynamic differential equations which have been solved numerically. Pig's position and velocity profiles as well as upstream and downstream fluid's pressure waves are presented as simulation results which provide a better understanding...