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    Global nonlinear dynamic analysis of concrete chimneys in frequency domain

    , Article ACI Structural Journal ; Volume 101, Issue 3 , 2004 , Pages 341-350 ; 08893241 (ISSN) Horr, A. M ; Safi, M ; Asadpour, N ; Sharif University of Technology
    2004
    Abstract
    The conventional finite element method has been used successfully in linear and nonlinear analyses in concrete chimney structures. The method can be performed by subdividing the large structure into small uniform elements having approximate shape functions. Although this replaces a single complicated structural system into a number of simple uniform elements, in cases of tall concrete chimney structures with cracking and crushing behavior in concrete material and yielding in the reinforcement, the computer time and memory can be large. Hence, it is desirable to search for a procedure requiring a fewer number of elements and also less computer time and effort to model a structure. In this... 

    Optimal design and fabrication of "CEDRA" rescue robot using genetic algorithm

    , Article 2004 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Salt Lake City, UT, 28 September 2004 through 2 October 2004 ; Volume 2 A , 2004 , Pages 541-548 Meghdari, A ; Pishkenari, H. N ; Gaskarimahalle, A. L ; Mahboobi, S. H ; Karimi, R ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Abstract
    This article presents an overview of the mechanical design features, fabrication and control of a Rescue Robot (CEDRA) for operation in unstructured environments. As a preliminary step, the essential characteristics of a robot in damaged and unstable situations have been established. According to these features and kinematical equations of the robot, design parameters are optimized by means of Genetic Algorithm. Optimum parameters are then utilized in construction. Upon fabrication, this unit has been tested in clean laboratory environment, as well as, ill-conditioned arenas similar to earthquake zones. The obtained results have been satisfactory in all aspects, and improvements are... 

    Work-in-Progress: heterogeneous redundancy to address performance and cost in multi-core SIMT

    , Article Proceedings of the 12th IEEE/ACM/IFIP International Conference on Hardware/Software Codesign and System Synthesis Companion, CODES 2017, 15 October 2017 through 20 October 2017 ; 2017 ; 9781450351850 (ISBN) Naghashi, M ; Mozafari, S. H ; Hessabi, S ; Sharif University of Technology
    Abstract
    As manufacturing processes scale to smaller feature sizes and processors become more complex, it is becoming challenging to have fabricated devices that operate according to their speciication in the irst place: yield losses are mounting [3]. In this work, we investigate adding heterogeneous hot redundancy (i.e., the architecture of redundant hot cores is diferent from the baseline cores) to improve the cost and performance of multicore single-instruction, multiple-thread (SIMT) architectures. We propose to utilize x86 out of order (OoO) cores as redundancy in SIMT processors. In this case, dice with unused functional redundancies can beneit from two types of processing cores (OoO and SM)  

    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
    Abstract
    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... 

    Automatic optimal feeder design in steel casting process

    , Article Computer Methods in Applied Mechanics and Engineering ; Volume 197, Issue 9-12 , 2008 , Pages 921-932 ; 00457825 (ISSN) Tavakoli, R ; Davami, P ; Sharif University of Technology
    2008
    Abstract
    A method for automatic optimal feeder design in steel casting processes is presented. The initial design is the casting part (without feeders) which is placed in a suitable mold box. Design of each feeder contains the following steps: determination of the feeder-neck connection point on the casting surface, initial feeder design, feeder shape optimization and feeder topology optimization. Completing designing the first feeder, the method attends to designing the next one, if it is required, and the same procedure will be repeated. In the presented method, feeders are designed in a descending order of their sizes. The feasibility of the presented method is supported with an illustrative... 

    Optimal feeder design in sand casting process by growth method

    , Article International Journal of Cast Metals Research ; Volume 20, Issue 5 , 2007 , Pages 288-296 ; 13640461 (ISSN) Tavakoli, R ; Davami, P ; Sharif University of Technology
    2007
    Abstract
    The computer aided optimal feeder design in the sand casting process is considered. The design problem is formulated as an additive evolutionary topology optimisation problem. The initial design of the presented method is a casting part which is placed in a suitable environmental mould box. The method is composed of three stages: determination of the feeder neck connection point, construction of the feeder neck and the feeder growth. During the growth stage, the feeder topology is improved gradually until satisfying some predefined criteria. The technological constraints and user contribution can be easily incorporated in the presented method. The success of the proposed method is supported... 

    Wind turbine transformer improved design method entailing resonance blocking

    , Article IET Electric Power Applications ; Volume 12, Issue 9 , 2018 , Pages 1337-1343 ; 17518660 (ISSN) Elhaminia, P ; Vakilian, M ; Lehtonen, M ; Sharif University of Technology
    Institution of Engineering and Technology  2018
    Abstract
    A wind turbine transformer resonance can occur due to high frequency transients at its terminal i.e.; under its energization through a length of cable. Occurrence of resonance can be addressed by a sophisticated transformer design procedure. The goal is to obtain an optimum design capable of controlling the frequency response of the winding in such a way to avoid occurrence of any resonance under transient conditions. Three insulation clearances parameters which are employed for the wind turbine transformer winding design have been investigated in design of a (800 kVA, 690/20,000 V) wind turbine transformer to determine effect of their variation on its frequency response. It is shown that... 

    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
    2008
    Abstract
    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  

    A new method for design cycle period management in aircraft design process

    , Article Aircraft Engineering and Aerospace Technology ; Volume 80, Issue 5 , 5 September , 2008 , Pages 497-509 ; 00022667 (ISSN) Soltanmohammad, S ; Malaek, S. M ; Sharif University of Technology
    2008
    Abstract
    Purpose - The purpose of this paper is to present research into reducing the aircraft design cycle period, by reducing the necessary number of design cycle iterations. The design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. Design/methodology/approach - Toachieve the above-mentioned goal, the paper presents a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps... 

    “Does cinema form the future of robotics?”: a survey on fictional robots in sci-fi movies

    , Article SN Applied Sciences ; Volume 3, Issue 6 , 2021 ; 25233971 (ISSN) Saffari, E ; Hosseini, S. R ; Taheri, A ; Meghdari, A ; Sharif University of Technology
    Springer Nature  2021
    Abstract
    Abstract: Robotics and Artificial Intelligence (AI) have always been among the most popular topics in science fiction (sci-fi) movies. This paper endeavors to review popular movies containing Fictional Robots (FR) to extract the most common characteristics and interesting design ideas of robots portrayed in science fiction. To this end, 134 sci-fi films, including 108 unique FRs, were investigated regarding the robots’ different design aspects (e.g., appearance design, interactive design and artificial intelligence, and ethical and social design). Also, in each section of this paper, some characteristics of FRs are compared with real social robots. Since some researches point to the... 

    Applications of axiomatic design theory in design for human safety in manufacturing systems: a literature review

    , Article MATEC Web of Conferences, 13 September 2017 through 15 September 2017 ; Volume 127 , 2017 ; 2261236X (ISSN) Sadeghi, L ; Houshmand, M ; Fatahi Valilai, O ; Slatineanu L ; Sharif University of Technology
    Abstract
    Design for Human Safety (DfHS) is an approach to integrate knowledge of human safety in the design process. DfHS is multi-disciplinary in its nature, requiring many kinds of information and knowledge. Number of DfHS studies tried to apply Axiomatic Design (AD) to achieve their aims. The purpose of this paper is to review the literature on application of AD in DfHS in manufacturing systems and to propose a roadmap for future DfHS works. This paper examines the number and type of publications dealing with this context. The review covers papers published between 1990 (when AD was introduced first) and 2017. It is based on a range of combinations of the following keywords: "Axiomatic design" and... 

    Iteration Control in Design Process

    , Ph.D. Dissertation Sharif University of Technology Soltan Mohammad, Bahram (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    The main goal of this research is to reduce aircraft design cycle period, by reducing the necessary number of design cycle iterations. The Design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. To achieve the above mentioned goal, we present a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps break information cycles that create iterations among important tasks.... 

    Axiomatic Design Science: Application in reducing Design Complexities of Special Structures

    , Ph.D. Dissertation Sharif University of Technology Fazli, Noroddin (Author) ; Abedian, Ali (Supervisor) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    This research aims to study fundamentals of design as a science for possible use in special structures. Special structures are referred to those structures that designers’ knowledge for which are insufficient. Designs of such structures are complex in the sense that we lack all necessary elements of design matrix; as well as proper steps to reach the unknowns. Introducing appropriate design strategy for such structures; we show how a design could be developed without specific needs for trial and errors. In this work, various design methodologies and especially “Axiomatic Design” have been examined. In addition, functional requirement and associated design parameters for structural design are... 

    Expand the shares together: envy-free mechanisms with a small number of cuts

    , Article Algorithmica ; 2018 ; 01784617 (ISSN) Seddighin, M ; Farhadi, M ; Ghodsi, M ; Alijani, R ; Tajik, A. S ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    We study the problem of fair division of a heterogeneous resource among strategic players. Given a divisible heterogeneous cake, we wish to divide the cake among n players to meet these conditions: (I) every player (weakly) prefers his allocated cake to any other player’s share (such notion is known as envy-freeness), (II) the allocation is dominant strategy-proof (truthful) (III) the number of cuts made on the cake is small. We provide methods for dividing the cake under different assumptions on the valuation functions of the players. First, we suppose that the valuation function of every player is a single interval with a special property, namely ordering property. For this case, we... 

    Covariance-based multiple-impulse rendezvous design

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 55, Issue 5 , 2019 , Pages 2128-2137 ; 00189251 (ISSN) Shakouri, A ; Kiani, M ; Pourtakdoust, S. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    A novel trajectory design methodology is proposed in the current work to minimize the state uncertainty in the crucial mission of spacecraft rendezvous. The trajectory is shaped under constraints utilizing a multiple-impulse approach. State uncertainty is characterized in terms of covariance, and the impulse time as the only effective parameter in uncertainty propagation is selected to minimize the trace of the covariance matrix. Furthermore, the impulse location is also adopted as the other design parameter to satisfy various translational constraints of the space mission. Efficiency and viability of the proposed idea have been investigated through some scenarios that include constraints on... 

    Rationality of the inner products of spherical s-distance t-designs for t ≥ 2s − 2, s ≥ 3

    , Article Linear Algebra and Its Applications ; Volume 646 , 2022 , Pages 107-118 ; 00243795 (ISSN) Boyvalenkov, P ; Nozaki, H ; Safaei, N ; Sharif University of Technology
    Elsevier Inc  2022
    Abstract
    We prove that the inner products of spherical s-distance t-designs with t≥2s−2 (Delsarte codes) and s≥3 are rational with the only exception being the icosahedron. In other formulations, we prove that all sharp configurations have rational inner products and all spherical codes which attain the Levenshtein bound, have rational inner products, except for the icosahedron. © 2022 Elsevier Inc  

    Novel probabilistic bounds on power level profile of spectrally-encoded spread-time CDMA signals [electronic resource]

    , Article IEEE Transactions on Wireless Communications ; Vol. 8, No. 5, PP. 2296-2301, May 2009 Mashhadi, S. (Saeed) ; Sharif University Of Technology
    Abstract
    In this letter we introduce an effective tool to demonstrate signal power behavior of a typical spectrally encoded spread-time (SE/ST) CDMA system using probabilistic approach. By defining power level profile (PLP), as the probability of stretching instantaneous power from a pre-specified threshold, we can find novel upper bounds on the signal power profile. We discuss various properties owing to PLP and elaborate on the main parameters affecting the PLP value. We present three theorems, propose some simple upper bounds on the PLP, and give an insight on the main contributions of the results. We introduce a fundamental parameter, namely ß, as a key design parameter which relates the most... 

    The Minimum vulnerability problem

    , Article Algorithmica ; Volume 70, Issue 4 , 2014 , pp 718-731 ; ISSN: 14320541 Assadi, S ; Emamjomeh-Zadeh, E ; Norouzi-Fard, A ; Yazdanbod, S ; Zarrabi-Zadeh, H ; Sharif University of Technology
    Abstract
    We revisit the problem of finding (Formula presented.) paths with a minimum number of shared edges between two vertices of a graph. An edge is called shared if it is used in more than one of the (Formula presented.) paths. We provide a (Formula presented.)-approximation algorithm for this problem, improving the best previous approximation factor of (Formula presented.). We also provide the first approximation algorithm for the problem with a sublinear approximation factor of (Formula presented.), where (Formula presented.) is the number of vertices in the input graph. For sparse graphs, such as bounded-degree and planar graphs, we show that the approximation factor of our algorithm can be... 

    Toward equitable investment in transport infrastructures: Providing a comparative framework based on theories of justice

    , Article Middle - East Journal of Scientific Research ; Vol. 19, issue. 9 , 2014 , pp. 1215-1225 ; ISSN: 19909233 Behbahani, H ; Nazari, S ; Jahromi, H. N ; Sharif University of Technology
    Abstract
    Equity in distribution is one of the most controversial and essential concepts which for a long time has been the central concern of political philosophers when considering planning concerns of the societies. Transport is a key field by which politicians and decision-makers impose their intention on societies. Although there have been studies discussing equity in transport, yet there is no clear mathematical framework to utilize the equity concept in transportation planning. This study has reviewed equity in transportation, as well as in human science studies to investigate and determine how transportation advantages should be equitably distributed among society members. This review has led... 

    Robust tolerance design of mechanical assemblies using a multi-objective optimization formulation

    , Article SAE Technical Papers ; Vol. 1 , 2014 Khodaygan, S ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    The design process always has some known or unknown uncertainties in the design variables and parameters. The aim of robust design is minimization of performance sensitivity to uncertainties. Tolerance allocation process can significantly affect quality and robustness of the product. In this paper, a methodology to minimize a product's sensitivity to uncertainties by allocating manufacturing tolerances is presented. The robust tolerance design problem is formulated as a multi-objective optimization based on the combined function-uncertainty-cost model. Genetic algorithm is utilized to solve the multi-objective optimization and a case study is presented to illustrate the methodology