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    A hybrid Nelder-Mead simplex and PSO approach on economic and economic-statistical designs of MEWMA control charts

    , Article International Journal of Advanced Manufacturing Technology ; Volume 65, Issue 9-12 , 2013 , Pages 1339-1348 ; 02683768 (ISSN) Barzinpour, F ; Noorossana, R ; Niaki, S. T. A ; Ershadi, M. J ; Sharif University of Technology
    Economic design of a control chart involves determining its basic parameters such that a cost function is minimized. This design when statistical performance measures are also considered is referred to as the economic-statistical design. In this paper, a simplex-based Nelder-Mead algorithm is used in combination with a particle swarm meta-heuristic procedure to solve both the economic and economic-statistical designs of a MEWMA control chart. The application results on extensive simulation experiments show that the particle swarm can lead the Nelder-Mead algorithm to better results. Furthermore, a comparative study is performed on the performances of three different algorithms of the... 

    Improved methodology for endurance time analysis: From time to seismic hazard return period

    , Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1180-1187 ; 10263098 (ISSN) Mirzaee, A ; Estekanchi, H. E ; Vafai, A ; Sharif University of Technology
    In the Endurance Time (ET) method, structures are subjected to a calibrated intensifying accelerogram and their performance is assessed based on their response at various equivalent intensity levels. Application of the ET method in performance-based design of structures has been studied by introducing a continuous performance target curve, which expresses the limit of the proper seismic performance of a structure along various times of the ET accelerogram. The correlation between time in the ET method and the return period for different structural periods is investigated. The procedure is based on the coincidence of response spectra obtained from the ET accelerogram at different times and... 

    A particle swarm optimization approach on economic and economic-statistical designs of MEWMA control charts

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1529-1536 ; 10263098 (ISSN) Niaki, S. T. A ; Malaki, M ; Ershadi, M. J ; Sharif University of Technology
    Control charts are the best tools to monitor main process parameters, and the Multivariate Exponentially Weighted Moving Average, MEWMA, type of this tool is used when there are several correlated quality characteristics to be monitored simultaneously where detecting small deviations of the characteristics is desired. In this paper, the models of both the economic and the economic-statistical design problems of MEWMA control charts are solved by a Particle Swarm Optimization (PSO) approach. The comparison study between the economic and the economic-statistical designs shows better statistical performances of the economic-statistical design with negligible increase in cost. Furthermore, in... 

    Application of particle swarm optimization to transportation network design problem

    , Article Journal of King Saud University - Science ; Volume 23, Issue 3 , 2011 , Pages 293-300 ; 10183647 (ISSN) Babazadeh, A ; Poorzahedy, H ; Nikoosokhan, S ; Sharif University of Technology
    Transportation network design problem (TNDP) aims to choose from among a set of alternatives (e.g., set of new arcs) which minimizes an objective (e.g., total travel time), while keeping consumption of resources (e.g., budget) within their limits. TNDP is formulated as a bilevel programming problem, which is difficult to solve on account of its combinatorial nature. Following a recent, heuristic by ant colony optimization (ACO), a hybridized ACO (HACO) has been devised and tested on the network of Sioux Falls, showing that the hybrid is more effective to solve the problem. In this paper, employing the heuristic of particle swarm optimization (PSO), an algorithm is designed to solve the TNDP.... 

    Experimental design for optimizing the corrosion resistance of pulse reverse electrodeposited graphene oxide thin film

    , Article Journal of Solid State Electrochemistry ; Volume 19, Issue 5 , May , 2015 , pp 1367–1380 ; 14328488 (ISSN) Yaghoubinezhad, Y ; Afshar, A ; Sharif University of Technology
    Springer New York LLC  2015
    In this study, linear polarization resistance (LPR) of pulse reverse electrodeposited graphene oxide (PREGO) coating is optimized by design of experiments approach (central composite design). Pulse current density (i), cathodic (Tc) and anodic (Ta) pulse durations, and total electrodeposition time (Tt) are selected as the substantial factors. The best prediction model proposes a definitive linear relation without any significant interaction of the LPR by analysis of variance. The desirable value of LPR was predicted equal to 5358 Ω cm2, obtaining at the pulse current density of 235.62 mA cm−2, Ta of 7.75 ms, Tc equal to 3.25 ms (f = 100 Hz), and Tt of approximately 225 s. Appearance of the... 

    Optimization of operating conditions in ultrafiltration process for produced water treatment via Taguchi methodology

    , Article Desalination and Water Treatment ; Volume 54, Issue 10 , May , 2015 , Pages 2669-2680 ; 19443994 (ISSN) Reyhani, A ; Sepehrinia, K ; Seyed Shahabadi, S. M ; Rekabdar, F ; Gheshlaghi, A ; Sharif University of Technology
    Taylor and Francis Inc  2015
    This paper describes how to find optimal operating conditions of three controlling parameters, i.e. temperature, transmembrane pressure (TMP), and cross-flow velocity (CFV) for maximizing the permeate flux and total organic carbons (TOC) rejection, and minimizing the fouling resistance using Taguchi method in ultrafiltration (UF) treatment of the real produced water. At first, the optimal operating conditions were found at a temperature of 45°C, TMP = 4 bar, and CFV of 2.25 m/s. To determine the most significant parameters affecting the response parameters, an analysis of variance was employed. In the second stage, performance of applied polymeric membrane in the UF system was studied under... 

    Heuristic algorithm for periodic clock optimisation in scheduling-based latency-insensitive design

    , Article IET Computers and Digital Techniques ; Volume 9, Issue 3 , May , 2015 , Pages 165-174 ; 17518601 (ISSN) Zare, M ; Hessabi, S ; Goudarzi, M ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    Delay in communication wires causes design iterations in system-on-chip. Latency-insensitive design copes with this issue by encapsulating each core in a shell wrapper and inserting buffers in the wires to separate the design of core from that of communication wires. Scheduling-based latency-insensitive protocol is a methodology which employs shift registers for periodic clock gating of blocks instead of the shell wrappers. In many cases, the bit sequences inside the shift registers are too long and therefore consume a large area. This study presents a heuristic algorithm that optimises the bit sequences and produces them with shorter lengths compared with the existing method. The algorithm... 

    Transmit code design for extended target detection in the presence of clutter

    , Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, 19 April 2014 through 24 April 2014 ; Volume 2015-August , April , 2015 , Pages 3921-3925 ; 15206149 (ISSN) ; 9781467369978 (ISBN) Karbasi, S. M ; Naghsh, M. M ; Bastani, M. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    In this paper, we consider the problem of transmit code design to optimize the detection probability of an extended target embedded in Gaussian signal-dependent interference. We model the target with a priori known target impulse response (TIR) structure along with an unknown reflection factor. As is known, the performance of the generalized likelihood ratio test (GLRT) detector, for the case at hand, monotonically increases with the signal-to-interference-plus-noise ratio (SINR). Hence, we deal with the code design problem via maximizing the SINR. We also enforce a peak-to-average power ratio (PAR) constraint on the sought code. We devise a cyclic method to tackle the highly non-convex... 

    Investigating optimum procedures needed to maintain a model satellite's CG stable about design point, under subsystem configuration changes

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 585-588 ; 9780791849187 (ISBN) Dastoom Laatleyli, H ; Abedian, A ; Teimouri, H ; Sharif University of Technology
    During design, microsatellites are subject to different changes like the changes in weight, location and dimension of parts and elements of subsystems and the payload. These changes should be accumulated by the structure subsystem in a way that some key structural parameters like the center of gravity (CG) and inertia moments remain unchanged. This subject is also important regarding the design of a modular structure of a satellite. In the present study it is tried to accommodate any changes in weight and location of any part(s) and element(s) of a microsatellite by optimum (minimum) rearrangement of other parts on their plane of rest in order to keep the CG and inertia moments unchanged.... 

    Design optimization of gimbal robotic joints based on task space manipulability

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 3 , July , 2010 , Pages 567-572 ; 9780791849170 (ISBN) Mohammadi, F ; Hemmatian, I ; Ghaemi Osgouie, K ; Sharif University of Technology
    Featuring a nonlinear novel design, Gimbal transmission, is a replacement for traditional robotic joints like gearboxes and revolute joints. This mechanism is one of the most recent types of nonlinear direct transmission (DT) methods in robots. As an alternative for traditional drive methodologies - herein called direct drive transmission (DD) methods, DT provides dynamic coupling and joint interaction attenuation while its capability to be adjusted for a desired task space point, smooth input-output characteristic, and varying reduction ratio lead to a desired force and motion behavior for the whole manipulator. In this paper, design optimization of a gimbal mechanism used as a replacement... 

    A survey of wave function effects on theoretical calculation of gas phase 19F NMR chemical shifts using factorial design

    , Article Journal of Fluorine Chemistry ; Volume 131, Issue 1 , 2010 , Pages 47-52 ; 00221139 (ISSN) Shaghaghi, H ; Ebrahimi, H ; Tafazzoli, M ; Jalali-Heravi, M ; Sharif University of Technology
    The wave functions for calculating gas phase 19F chemical shifts were optimally selected using the factorial design as a multivariate technique. The effects of electron correlation, triple-ξ valance shell, diffuse function, and polarization function on calculated 19F chemical shifts were discussed. It is shown that of the four factors, electron correlation and the polarization functions affect the results significantly. B3LYP/6-31 + G(df,p) wave functions have been proposed as the best and the most efficient level of theory for calculating 19F chemical shifts. An additional series of fluoro compounds were used as a test set and their predicted 19F chemical shifts values confirmed the... 

    Economic design of phase 2 simple linear profiles with variable sample size

    , Article International Journal of Productivity and Quality Management ; Volume 18, Issue 4 , 2016 , Pages 518-536 ; 17466474 (ISSN) Ershadi, M. J ; Noorossana, R ; Akhavan Niaki, S. T ; Sharif University of Technology
    Inderscience Enterprises Ltd  2016
    Employing profiles using variable sample size (VSS) may improve its effectiveness and hence is investigated in this paper. Besides, the implementation cost of a profile is an important factor in determining the main parameters. In this paper, the Lorenzen-Vance function is first extended to model implementation cost of VSS linear profiles. Then, the resulted economic model is solved using a genetic algorithm (GA). The average run length criterion when process is in control, ARL0 and the average run length measure when process goes out of control, ARL1 , is used to evaluate statistical properties of the designed profile. Moreover, a sensitivity analysis on the main parameters of the... 

    A three-step method for the deposition of large cuboids of organic–inorganic perovskite and application in solar cells

    , Article ChemPhysChem ; 2016 , Pages 2389-2394 ; 14394235 (ISSN) Shahbazi, S ; Malekshahi Byranvand, M ; Tajabadi, F ; Afshar, Sh ; Taghavinia, N ; Sharif University of Technology
    Wiley-VCH Verlag 
    A three-step method for the deposition of CH3NH3PbI3 perovskite films with a high crystalline structure and large cuboid overlayer morphology is reported. The method includes PbI2 deposition, which is followed by dipping into a solution of C4H9NH3I (BAI) and (BA)2PbI4 perovskite formation. In the final step, the poorly thermodynamically stable (BA)2PbI4 phase converts into the more stable CH3NH3PbI3 perovskite by dipping into a solution of CH3NH3I. The final product is characterized by XRD, SEM, UV/Vis, and photoluminescence analysis methods. The experimental results indicate that the prepared perovskite has cuboids with high crystallinity and large sizes (up to 1 μm), as confirmed by XRD... 

    A road map for knowledge management systems design using axiomatic design approach

    , Article MATEC Web of Conferences, 13 September 2017 through 15 September 2017 ; Volume 127 , 2017 ; 2261236X (ISSN) Houshmand, M ; Amani, M ; Slatineanu, L ; Sharif University of Technology
    Successful design and implementation of knowledge management systems have been the main concern of many researchers. It has been reported that more than 50% of knowledge management systems have failed, therefore, it is required to seek for a new and comprehensive scientific approach to design and implement it. In the design and implementation of a knowledge management system, it is required to know 'what we want to achieve' and 'how and by what processes we will achieve it'. A literature review conducted and axiomatic design theory selected for this purpose. For the first time, this paper develops a conceptual design of knowledge management systems by means of a hierarchical structure,... 

    Use of response surface methodology analysis for xanthan biopolymer production by xanthomonas campestris: focus on agitation rate, carbon source, and temperature

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 36, Issue 1 , 2017 , Pages 173-183 ; 10219986 (ISSN) Zakeri, A ; Pazouki, M ; Vossoughi, M ; Sharif University of Technology
    Jihad Danishgahi  2017
    The current study is an attempt to contribute for efficient and cost-effective substrates for xanthan gum production. In this context, the sugar cane molasses wastes can be used as a cheap substrate for xanthan gum production. Xanthan biopolymer production by a novel Xanthomonas campestris strain IBRC-M 10644 was optimized with statistical approaches. Based on the results of Response Surface Methodology (RSM) with Central Composite Design (CCD) technique, a second-order polynomial model was developed and evaluated the effects of variables on the maximum xanthan production. Agitation rate (X1: 200-500 rpm), sugar cane molasses concentration (X2: 30-90 g/L) and operation temperature (X3: 25-35... 

    Impacts of SiO2 and MgO nanoparticles on mass transfer performance of batch liquid-liquid extraction

    , Article Inorganic and Nano-Metal Chemistry ; Volume 47, Issue 5 , 2017 , Pages 677-680 ; 24701556 (ISSN) Sepehri Sadeghian, S. S ; Abooali, D ; Rahbar Kelishami, A ; Sharif University of Technology
    Due to substantial impacts of nanoparticles on mass and heat transfer, having knowledge about different types of nanoparticles can contribute to access high efficiencies. As an investigation, in the present study, a number of liquid-liquid extraction experiments were designed by the use of Taguchi design model in order to study the impacts of SiO2 and MgO nanoparticles on mass transfer, in the batch systems. Acetic acid was considered as solute in some organic phases (i.e., n-butanol, n-butyl acetate, toluene, and chloroform), and pure water was applied as solvent. Taguchi experiment design method made more precision and convenience in the work. Final results showed reduction of mass... 

    The effect of microthread design on magnitude and distribution of stresses in bone: a three-dimensional finite element analysis

    , Article Dental Research Journal ; Volume 15, Issue 5 , 2018 , Pages 347-353 ; 17353327 (ISSN) Golmohammadi, S ; Eskandari, A ; Movahhedy, M. R ; Shirmohammadi, A ; Amid, R ; Sharif University of Technology
    Background: The researches regarding the influence of microthread design variables on the stress distribution in bone and a biomechanically optimal design for implant neck are limited. The aim of the present study is to compare the effect of different microthread designs on crestal bone stress. Materials and Methods: Six implant models were constructed for three-dimensional finite element analysis including two thread profile (coarse and fine) with three different lengths of microthreaded neck (1 mm, 2 mm, and 3 mm). A load of 200 N was applied in two angulations (0° and 30°) relative to the long axis of the implant and the resultant maximum von Mises equivalent (EQV), compressive, tensile,... 

    Inherently safer design of a reactor network system: a case study

    , Article Journal of Loss Prevention in the Process Industries ; Volume 51 , 2018 , Pages 112-124 ; 09504230 (ISSN) Eini, S ; Javidi, M ; Shahhosseini, H. R ; Rashtchian, D ; Sharif University of Technology
    Elsevier Ltd  2018
    The strategies of Inherently Safer Design (ISD) provide a conceptual approach in order to design equipment and processes with substantially improved safety level. However, this may lead to a less economically attractive design. This study aimed to obtain optimal decision parameters of a reactor network system to produce allyl chloride. The objective functions were the risk level, including the severity and the frequency of the accidents, which were associated with the hazards in the network and the economic profit of the process. Based on this optimization approach, an array of optimal solutions (called Pareto front) was obtained as a trade-off between the objectives under investigation. A... 

    Optimal riser design in sand casting process with evolutionary topology optimization

    , Article Structural and Multidisciplinary Optimization ; Volume 38, Issue 2 , 2009 , Pages 205-214 ; 1615147X (ISSN) Tavakoli, R ; Davami, P ; Sharif University of Technology
    The optimal design of a casting feeding system is considered. The riser topology is systematically modified to minimize the riser volume, while simultaneously ensuring that no defect appears in the product. In this approach, we combine finite-difference analysis of the solidification process with evolutionary topology optimization to systematically improve the feeding system design. The outstanding features of the presented method are: its efficiency, ease of implementation and simplifying definition of the initial design. The efficiency and capability of the presented method are supported by illustrative examples. © 2008 Springer-Verlag  

    Novel probabilistic bounds on power level profile of spectrally-encoded spread-time CDMA signals

    , Article IEEE Transactions on Wireless Communications ; Volume 8, Issue 5 , 2009 , Pages 2296-2301 ; 15361276 (ISSN) Mashhadi, S ; Salehi, J ; Sharif University of Technology
    In this letter we introduce an effective tool to demonstrate signal power behavior of a typical spectrallyencoded spread-time (SE/ST) CDMA system using probabilistic approach. By denning 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 β, as a key design parameter which relates the most...