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    Adaptive control of structures by LMS algorithm: A comparative study

    , Article Proceedings of the Institution of Civil Engineers: Structures and Buildings ; Volume 152, Issue 2 , 2002 , Pages 175-191 ; 09650911 (ISSN) Golafshani, A. A ; Mirdamadi, H. R ; Sharif University of Technology
    ICE Publishing Ltd  2002
    By using the normalised least mean squared (NLMS) algorithm, a semi-active multi-variable adaptive controller is designed for a seismically excited structure. There is no need for a large power supply. A number of valves and battery size low-power supplies will suffice. The valves control the amount of flow of a fluid through bypass on-off orifice channels in installed energy dissipating mechanisms. Each mechanism is composed of a piston attached to a A-shaped chevron wind-bracing on each floor and to a cylinder attached to the upper floor. Adaptive controller parameters are estimated by the LMS optimiser, in order to search for optimal non-classical damping coefficients of the dissipating... 

    Erratum to: "Fast design of relatively wide band fractional delay all-pass filters" [Signal Process. 88 (3) (2008) 612-623] (DOI:10.1016/j.sigpro.2007.09.006)

    , Article Signal Processing ; Volume 88, Issue 4 , 2008 , Pages 1082- ; 01651684 (ISSN) Jahani Yekta, M. M ; Sharif University of Technology
    A fast and simple procedure for designing relatively wide band fractional delay (FD) all-pass filters is proposed and filters designed based on it are compared to those designed using Thiran’s method, which is one of the simplest, fastest and widely used approaches in designing FD all-pass filters. It is shown that filters designed using the introduced method have wider fractional group delay (fgpd) bandwidths compared to those obtained via Thiran’s technique, as well as some other desired properties. The designed filters are also demonstrated to be stable for several pairs of filter orders and fgpd values. r2007 Elsevier B.V. All rights reserved  

    Low-order adaptive half-sample interpolators

    , Article Electronics Letters ; Volume 46, Issue 13 , June , 2010 , Pages 897-898 ; 00135194 (ISSN) Jahani Yekta, M. M ; Sharif University of Technology
    Although the fractional delay filtering literature is full of design methods and implementation techniques for fractional sample interpolators, a fundamental need for the proposition of low-order efficient designs still strongly exists. Proposed is such a system for half-sample interpolation. In contrast to the typical systems studied in the literature for fractional delay filtering, the system proposed continuously adapts its interpolation kernel to the statistical variations of the input signal, and this is in fact the reason for it being needless of having a high order. Satisfactory performance of the proposed structure has been demonstrated via simulation  

    Development of Optimal Integrated and Intensive Model of Energy Processing and Conversion

    , Ph.D. Dissertation Sharif University of Technology Avami, Akram (Author) ; Saboohi, Yadollah (Supervisor)
    In a single chemical plant, the operation of each unit operation is not independent of each other. In the other hand, the main operations are performed in reactors following by several separation steps including distillation and purification units. The total energy requirements are sullied by the heat exchanger networks. The performance of these systems is improved by integration and intensification of the reactor and distillation column in a single unit. The main objective of the present work is to provide an effective design approach to intensify the reactor and distillation column. In a reactive distillation column, the reaction and separation is done in a single unit. Increasing... 

    Coevolution of input sensors and recognition system to design a very low computation isolated, word speech recognition system

    , Article Scientia Iranica ; Volume 14, Issue 6 , 2007 , Pages 625-630 ; 10263098 (ISSN) Halavati, R ; Shouraki, S. B ; Sharif University of Technology
    Sharif University of Technology  2007
    Appropriate sensors are a crucial necessity for the success of recognition systems. Nature has always coevolved sensors and recognition systems and this can also be done in artificially intelligent systems. To get a very fast isolated word speech recognition system for a small embedded speech recognizer, an evolutionary approach has been used to create together the required sensors and appropriate recognition structures. The input sensors are designed and evolved through inspiration by the human auditory system and the classification is done by artificial neural networks. The resulting system is compared with a widely used speech recognition system, and the results are quite satisfactory. ©... 

    Deformation-dependent peak floor acceleration for the performance-based design of nonstructural elements attached to R/C structures

    , Article Earthquake Spectra ; Volume 37, Issue 2 , 2021 , Pages 1035-1055 ; 87552930 (ISSN) Muho, E. V ; Pian, C ; Qian, J ; Shadabfar, M ; Beskos, D. E ; Sharif University of Technology
    SAGE Publications Inc  2021
    This study introduces a simple and efficient method to determine the peak floor acceleration (PFA) at different performance levels for three types of plane reinforced concrete (RC) structures: moment-resisting frames (MRFs), infilled–moment-resisting frames (I-MRFs), and wall-frame dual systems (WFDSs). By associating the structural maximum PFA response with the deformation response, the acceleration-sensitive nonstructural components, and the building contents, can be designed to adhere to the performance-based seismic design of the supporting structure. Thus, the proposed method can accompany displacement-based seismic design methods to design acceleration-sensitive nonstructural elements... 

    Analytical Design of Fixed-structure Fractional-order Controllers in Frequency Domain

    , Ph.D. Dissertation Sharif University of Technology Sayyaf, Negin (Author) ; Tavazoei, Mohammad Saleh (Supervisor)
    Due to the simplicity and generality, design of feedback control systems in the frequency domain is among the most prominent topics in the control systems engineering. The problem of compensation means properly adjusting the loop frequency response at critical frequencies. Considering the point that the traditional methods usually use trial and error procedures for compensation, analytical design of fixed-structure controllers for exactly adjusting such values has great importance. Benefitting from the capability of fractional-order dynamics, the compensation problem is studied from three aspects in this thesis. At first according to the importance of adjusting the system frequency response... 

    Subsonic and transonic airfoil inverse design via Ball-Spine Algorithm

    , Article Computers and Fluids ; Volume 84 , 2013 , Pages 87-96 ; 00457930 (ISSN) Nili Ahmadabadi, M ; Ghadak, F ; Mohammadi, M ; Sharif University of Technology
    Inverse design in external flow regimes usually involves finding the wall shape associated with a prescribed distribution of wall pressure or velocity. In this research, a novel iterative inverse design method is developed for inviscid subsonic and transonic external flow regimes. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA), and a 2D inviscid analysis code. The Euler equations are solved for a physical domain of which some unknown boundaries are iteratively modified via BSA until a prescribed pressure distribution is reached. In BSA, the unknown walls are composed of a set of virtual balls that move freely along the specified directions called... 

    New operational transconductance amplifiers using current boosting

    , Article Midwest Symposium on Circuits and Systems ; 2012 , Pages 109-112 ; 15483746 (ISSN) ; 9781467325264 (ISBN) Noormohammadi, M ; Lazarjan, V. K ; HajSadeghi, K ; Sharif University of Technology
    New techniques for Class-AB Operational Transconductance Amplifiers (OTAs) are presented. These new techniques are two topologies based on current boosting in class-AB stage which achieve considerable improvement of Slew Rate and Gain-Bandwidth while maintaining the same power consumption as the conventional design. Circuit level analysis and simulation results of proposed circuits in 0.18μm CMOS technology for gain, GBW, slew rate, and settling time are presented to prove the effectiveness of the proposed design method  

    A constrained multi-product pricing and inventory control problem

    , Article Applied Soft Computing Journal ; Volume 12, Issue 8 , 2012 , Pages 2454-2461 ; 15684946 (ISSN) Shavandi, H ; Mahlooji, H ; Nosratian, N. E ; Sharif University of Technology
    Elsevier  2012
    The aim of this article is presenting a new constrained multi-product pricing and inventory model in which perishable products are put into three categories: substitute, complementary and independent. The general demand is found by considering the relations of different products and the impact of their prices. The goal of the model is deciding on the prices as well as the inventory and production decisions in order to maximize the total profit. The derived model is a non-linear programming model and a genetic algorithm is developed for its solution. To enhance the performance of our genetic algorithm, we apply the Taguchi experimental design method to tune the parameters of the algorithm.... 

    Systematic design method for bonded repair based on axiomatic design methodology

    , Article Procedia CIRP, 16 September 2015 through 18 September 2015 ; Volume 34 , 2015 , Pages 236-243 ; 22128271 (ISSN) Fouladi, E ; Abedian, A ; Giorgetti, A ; Citti, P ; Suh, N. P ; Matt, D ; Kathryn, M ; Sharif University of Technology
    Elsevier  2015
    When cracks along rivet holes and other highly stressed regions of mostly aged aircrafts are found, usually repairs are being made to arrest these cracks. Patches provide an innovative repair technique, which can enhance the way aircrafts are maintained. Composite patch design along with axiomatic design technique deployment is a possibility. Axiomatic Design (AD) is expressed as a system design methodology that is applicable to creation of a new design, analysis and improvement of an existing design. While, here Patch Design system architecture is expressed as application of principles of axiomatic design on top level requirements with consideration of design parameters and constraints. A... 

    Optimum design of planar transformer for LLC resonant converter using metaheuristic method

    , Article 45th Annual Conference of the IEEE Industrial Electronics Society, IECON 2019, 14 October 2019 through 17 October 2019 ; Volume 2019-October , 2019 , Pages 6621-6626 ; 9781728148786 (ISBN) Nazerian, E ; Tahami, F ; Sharif University of Technology
    IEEE Computer Society  2019
    Isolated, high-density DC-DC converters play a crucial role in the power supply unit of information technology industries. By virtue of high efficiency and high power density, LLC resonant converters-among the rest of DC-DC converters-are suitable candidates for this application. The magnetic structure of this converter, however, is a bulky, dissipative part, which has a considerable portion of power loss. Improvement in the size and efficiency of the LLC transformer will lead to an overall enhancement of power density and efficiency of the converter. Nevertheless, the optimization of planar transformers for the LLC converter has not been studied enough. This paper proposes a... 

    Orthogonal-mode dual-band rectangular waveguide filters

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 1534-1537 ; 9781728115085 (ISBN) Golzar, M.H ; Memarian, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    In this paper, we present a design method of dual-band waveguide rectangular cavity filters, with a series in-line topology. The coupling matrix is based on asynchronously tuned designs, where two sets of resonances exist for the two bands. Thus the filter is inherently different than the typical dual-band designs in the literature, as existing designs utilize resonators at the same frequency. The design at Ku band validates the underlying idea and concept, and the theory of the detuned coupling matrix. This rectangular waveguide implementation can provide noticeable miniaturization in applications with high-power requirements  

    Performance improvement of mixed-flow centrifugal pumps with new impeller shrouds: Numerical and experimental investigations

    , Article Renewable Energy ; Volume 163 , 2021 , Pages 635-648 ; 09601481 (ISSN) Bozorgasareh, H ; Khalesi, J ; Jafari, M ; Gazori, H. O ; Sharif University of Technology
    Elsevier Ltd  2021
    A new impeller configuration with innovatively-designed shrouds is introduced, and its impact on the pressure head and efficiency of the semi-open centrifugal pump is explored using experimental and numerical approaches. The proposed design includes attaching specific plates called bladelets to a semi-open impeller to limit the secondary flows over the blades resulting in an increase in the pump head and efficiency. Hydraulic performance of a centrifugal pump with three different bladelets at angles of 30°, 60°, and 90° is investigated experimentally, and the results are compared to semi-open and closed impellers. The values of pressure head and efficiency of the proposed centrifugal pump... 

    Theoretical and experimental investigation of design parameter effects on the slip phenomenon and performance of a centrifugal compressor

    , Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 291-304 ; 10263098 (ISSN) Rajabpour, S ; Hajilouy Benisi, A ; Manzari, M. T ; Sharif University of Technology
    Sharif University of Technology  2021
    Numerous studies have investigated driving equations used to predict the slip factor in centrifugal compressors so far. Inevitably, through these studies, the ow field characteristics have been simplified and the effects of the related parameters have been neglected. The present study, experimentally and numerically, investigates the slip phenomenon in a specific centrifugal compressor with complex blade curves and splitter blades, considering the main effective parameters such as the number of blades, exit angle, etc. To this end, a three-dimensional simulation of the viscous flow field of the compressor via an appropriate turbulence method was performed. In addition, an experimental study... 

    A vacuum-refilled tensiometer for deep monitoring of in-situ pore water pressure

    , Article Scientia Iranica ; Volume 27, Issue 2A , 2021 , Pages 596-606 ; 10263098 (ISSN) Sadeghi, H ; Chiu, A. C. F ; Ng, C. W. W ; Jafarzadeh, F ; Sharif University of Technology
    Sharif University of Technology  2021
    Real-time measurement of soil water pressure has been recognized as an essential part of investigating water ow in unsaturated soils. Tensiometry, amongst different measuring techniques, is a common method for direct evaluation of water pressure. However, the lower limit of measurable water pressure by a conventional tensiometer becomes even more limited by increasing its length in the vertical installation. This paper describes the development of a Vacuum-Refilled Tensiometer (VRT) for monitoring soil water pressure independent of installation depth. This is achieved by fixing the distance between pressure sensor and ceramic cup together with incorporating an ancillary vacuumre filling... 

    Vanadium pentoxide catalyst over carbon-based nanomaterials for the oxidative dehydrogenation of propane

    , Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 46 , 2013 , Pages 16128-16141 ; 08885885 (ISSN) Fattahi, M ; Kazemeini, M ; Khorasheh, F ; Rashidi, A. M ; Sharif University of Technology
    A series of V2O5 catalysts supported on multiwall carbon nanotube (MWCNT), single wall carbon nanotube (SWCNT), and graphene were synthesized by hydrothermal and reflux methods for oxidative dehydrogenation of propane (ODHP) to propylene. The catalysts were characterized by techniques including the BET surface area measurements, XRD, FTIR, H2-TPR, NH3-TPD, FESEM, and UV-vis diffuse reflectance spectroscopy. The performance of the catalysts and the supports were subsequently examined in a fixed bed reactor. The main products were propylene, ethylene and CO x. The vanadium catalyst supported on graphene with C/V molar ratio of 1:1 synthesized through the hydrothermal method had the best... 

    Centrifugal compressor shape modification using a proposed inverse design method

    , Article Journal of Mechanical Science and Technology ; Volume 27, Issue 3 , 2013 , Pages 713-720 ; 1738494X (ISSN) Nili Ahmadabadi, M ; Poursadegh, F ; Sharif University of Technology
    This paper is concerned with a quasi-3D design method for the radial and axial diffusers of a centrifugal compressor on the meridional plane. The method integrates a novel inverse design algorithm, called ball-spine algorithm (BSA), and a quasi-3D analysis code. The Euler equation is solved on the meridional plane for a numerical domain, of which unknown boundaries (hub and shroud) are iteratively modified under the BSA until a prescribed pressure distribution is reached. In BSA, unknown walls are composed of a set of virtual balls that move freely along specified directions called spines. The difference between target and current pressure distributions causes the flexible boundary to deform... 

    Dextran-graft-poly(hydroxyethyl methacrylate) gels: A new biosorbent for fluoride removal of water

    , Article Designed Monomers and Polymers ; Volume 16, Issue 2 , 2013 , Pages 127-136 ; 1385772X (ISSN) Ahmari, A ; Mousavi, S. A ; Amini Fazl, A ; Amini Fazl, M. S ; Ahmari, R ; Sharif University of Technology
    Synthesis of dextran-graft-poly(hydroxyethyl methacrylate) gels as a new fluoride biosorbent was considered in this work. For this propose, the Taguchi experimental design method was used for optimizing the synthetic conditions of the gels to reach high level of fluoride absorbency. The effects of three main parameters including concentrations of monomer (hydroxyethyl methacrylate), crosslinking agent (ethylene glycol dimethacrylate), and initiator (ammonium persulfate) on the final properties of the prepared gels were investigated. The proposed mechanism for grafting and chemically crosslinking reactions was proved with equilibrium water absorption, Fourier-transformed infrared, scanning... 

    Comparison of the drift spectra generated using continuous and lumped-mass beam models

    , Article Scientia Iranica ; Volume 20, Issue 5 , 2013 , Pages 1337-1348 ; 10263098 (ISSN) Rofooei, F. R ; Shodja, A. H ; Sharif University of Technology
    The drift spectrum, as a new measure of earthquake-induced demands in structures, was developed using a uniform-stiffness continuous beam model. Practical limitations in the procedures based on such models have caused structural engineers to pay little attention to drift spectra. In this paper, a method is proposed to estimate the seismic-induced inter-story drift demands, using the modal analysis technique of lumped mass, non-uniform beam models. The proposed approach is simple and can overcome many deficiencies of the previous methods. It can take into account the very important effect of height-wise stiffness reduction on drift demands, without the numerical difficulties usually...