Sharif Digital Repository

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... 

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  

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... 

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... 

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  

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  

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... 

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  

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... 

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 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... 

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... 

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... 

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... 

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... 

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  

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... 

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...