Loading...
Search for: shamsi--h
0.115 seconds

    Performance evaluation and optimization of encapsulated cascade PCM thermal storage

    , Article Journal of Energy Storage ; Volume 11 , 2017 , Pages 64-75 ; 2352152X (ISSN) Shamsi, H ; Boroushaki, M ; Geraei, H ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    One of the main components of any solar power plant is its thermal heat storage system. Heat storage reduces the cost of power generation by increasing the capacity factor of the system. This paper aims to model and optimize the operation of a consecutive multi-layer Phase Change Material (PCM) thermal heat storage system, named Cascade Latent Heat Storage (CLHS), using the method of characteristics and genetic algorithm. The model is validated through comparison with experimental data available in the literature. The model can predict fluid and PCM temperature, PCM phase and the energy absorbed by PCM. A sensitivity analysis is employed for both the PCM and the fluid parameters. The PCM... 

    Linear decoupled and quasi-decoupled space-time codes

    , Article IEEE Transactions on Communications ; Volume 55, Issue 1 , 2007 , Pages 54-59 ; 00906778 (ISSN) Razaghi, P ; Khalaj, B. H ; Shamsi, M ; Sharif University of Technology
    2007
    Abstract
    Space-time transmit diversity results in coupling of transmitted symbols across different antennas, which increases the complexity of maximum-likelihood decoding. Symbol coupling can be completely or partially avoided if the space-time code (STC) satisfies specific decoupling conditions; examples of such codes are orthogonal space-time block codes and quasi-orthogonal codes. In this letter, we study decoupling conditions for a linear full-diversity STC. Quasi-decoupled codes are proposed as a partially decoupled full-diversity STC of any rate for any number of transmit antennas with minimum decoding delay. By optimizing the coding gain of quasi-decoupled codes, it is shown that... 

    Control of a Bioreactor Using Artificial Intelligent Methods

    , M.Sc. Thesis Sharif University of Technology Shamsi, Zahra (Author) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    The goal of this project is finding an appropriate method for controlling four different bioreactors with unknown dynamics. At first, an introduction to bioreactor dynamic hase been presented, then their nonlinear behavior has been discussed. In the following, four output control systems using adaptive neural network have been designed separately for four different dynamics. The applied control method has been adapted from a method of references with some changes. Performances of designed controllers in set point tracking, load rejection and model mismatch have been evaluated using simulation. In these studies, input saturation has been considered in simulations but it is not existed in... 

    A Comparison of Three Vocabulary Teaching Methods: A Case for Task/Test Compatibility

    , M.Sc. Thesis Sharif University of Technology Shamsi, Yaser (Author) ; Jahangard, Ali (Supervisor)
    Abstract
    The importance of vocabulary, the building blocks of every language, in having a good command of a second language is evident. However, the best way to improve the lexical knowledge of the students is an issue that is open to discussions. This study aimed at investigating three different methods for teaching new vocabularies to Iranian students who were striving to take command of English as a second language in order to determine the advantages of one method over the other in terms of immediate and delayed retention. In this endeavor, we set 105 intermediate adult learners of English into three groups and instructed each group with a specific method, teaching them a number of new words... 

    Controller design for processes with unknown dynamics and input nonlinearity with applications to bioreactors

    , Article Industrial and Engineering Chemistry Research ; Volume 55, Issue 9 , 2016 , Pages 2584-2593 ; 08885885 (ISSN) Shamsi, Z ; Shahrokhi, M ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    An efficient approach for controlling processes with completely unknown dynamics subject to input nonlinearity and in the absence of state measurements is presented. To handle the system input nonlinearity, this constrain has been included in the system unknown dynamics and a new input has been defined. An unknown Lyapunov function has been considered, and the terms appearing in its time derivative are estimated by neural networks and the stability of the closed-loop system has been established. The effectiveness of the proposed control scheme has been demonstrated by applying the scheme to different bioreactors with unknown dynamics under input saturation. The performances of designed... 

    Study on Non-Linear Approaches for Accelerating Iterative Methods

    , M.Sc. Thesis Sharif University of Technology Shamsi, Mahdi (Author) ; Marvasti, Farokh (Supervisor)
    Abstract
    In this correspondence, a non-linear method of convergence accelerating and improving for iteration based algorithms is introduced. After convergence analysis, some enough conditions are proposed to guarantee convergence of the algorithm.For the sake of low complexity implementation of the proposed algorithm, some simple stabilizing methods are suggested. Simulation results show desirable performance of the proposed method and its capability to stabilize the iteration based algorithms. In the literature of missing samples recovery, the proposed method is applied to an Iterative Method (IM) as a general signal reconstruction method,then it is extended to the image recovery problem where... 

    A Comperehensive Model of Disasters Classification

    , M.Sc. Thesis Sharif University of Technology Shamsi, Somayeh (Author) ; Eshghi, Kourosh (Supervisor)
    Abstract
    The occurrence of natural disasters and damages caused by them has greatly impacted humans' lives, which reveals need for us to prepare for confrontation with various disasters. For this purpose, in this research, we are seeking to develop a programming model to reduce damages caused by various disasters. This thesis includes 3 main sections. In first section, some major impacts of disasters are reviewed and studied during the past 118 years and some major lessons are summarized based on statistical data analysis. In second section, a 3-demontional probability density function has been developed to categorize different types of disasters. Furthermore, a scaling system is presented to... 

    Overloaded Time-Frequency Modulation Schema for 5-6 G Mobile Systems

    , Ph.D. Dissertation Sharif University of Technology Shamsi, Mahdi (Author) ; Marvasti, Farokh (Supervisor)
    Abstract
    Increasing dynamics of mobile users intensifies the Doppler effect and degrades the performance of the communication system. Considering Fourier kernel-based modulation, in this research, we focus on dealing with the Doppler effect and compensating non-ideal communication channel response suffered from the Doppler-delay spread. In the first step, we study Zak transform and present a new transform for 2-D representation of time signals. This mapping is a well-known transformation that can be considered as a generalized discrete-time Fourier transform in the field of signal processing and can be used to represent a signal in the delay-Doppler domain. After providing a new 2-D transform, we... 

    High throughput blood plasma separation using a passive PMMA microfluidic device

    , Article Microsystem Technologies ; Volume 22, Issue 10 , 2016 , Pages 2447-2454 ; 09467076 (ISSN) Shamsi, A ; Shamloo, A ; Mohammadaliha, N ; Hajghassem, H ; Fallah Mehrabadi, J ; Bazzaz, M ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    Since plasma is rich in many biomarkers used in clinical diagnostic experiments, microscale blood plasma separation is a primitive step in most of microfluidic analytical chips. In this paper, a passive microfluidic device for on-chip blood plasma separation based on Zweifach–Fung effect and plasma skimming was designed and fabricated by hot embossing of microchannels on a PMMA substrate and thermal bonding process. Human blood was diluted in various times and injected into the device. The main novelty of the proposed microfluidic device is the design of diffuser-shaped daughter channels. Our results demonstrated that this design exerted a considerable positive influence on the separation... 

    High throughput blood plasma separation using a passive PMMA microfluidic device

    , Article Microsystem Technologies ; 2015 ; 09467076 (ISSN) Shamsi, A ; Shamloo, A ; Mohammadaliha, N ; Hajghassem, H ; Mehrabadi, J. F ; Bazzaz, M ; Sharif University of Technology
    Springer Verlag  2015
    Abstract
    Since plasma is rich in many biomarkers used in clinical diagnostic experiments, microscale blood plasma separation is a primitive step in most of microfluidic analytical chips. In this paper, a passive microfluidic device for on-chip blood plasma separation based on Zweifach–Fung effect and plasma skimming was designed and fabricated by hot embossing of microchannels on a PMMA substrate and thermal bonding process. Human blood was diluted in various times and injected into the device. The main novelty of the proposed microfluidic device is the design of diffuser-shaped daughter channels. Our results demonstrated that this design exerted a considerable positive influence on the separation... 

    Detail Design of a Pyroshock Simulator with Ability of Generating Specified SRS

    , M.Sc. Thesis Sharif University of Technology Shamsi, Mohammad (Author) ; Saadat Foumani, Mahmoud (Supervisor)
    Abstract
    Pyrotechnic devices are widely used by the aerospace and defense industries and consist of a broad family ofsophisticated devices using self-contained energy sourcessuch as explosives and/or pyrotechnic compositions.Pyrotechnic shock, or pyroshock, is the transient oscillatoryresponse of a structure to loading (high frequency, highmagnitude stress waves) induced by the detonation ofpyrotechnic devices incorporated into or attached to thestructure.Pyroshock Test is one of importantenvironmental tests in satellite design process. Pyroshock is one of loads that exerted on spacecraft and it's subsystems during launch process. Pyroshock can cause failure in some subsystems like sensitive... 

    Stochastic Model for Optimal Participation of Wind Power Producers in Electricity Market Considering Risk Factors

    , M.Sc. Thesis Sharif University of Technology Shamsi Gushki, Amin (Author) ; Ehsan, Mehdi (Supervisor)
    Abstract
    This thesis presents a new method for scheduling wind generation companies to participate in day-ahead market. The assumed market structure of this thesis, considers day-ahead energy market and balancing market, simultaneously. The stochastic model of this, implements a robust function to face the uncertainties of these markets. The risk of participation in these market are controlled with Information Gap Decision Theory (IGDT). Finally the allowable percent of each uncertain parameters are introduced to met an specific level of profit for the company  

    A hybrid PSO-SA algorithm for the travelling tournament problem

    , Article European Journal of Industrial Engineering ; Volume 6, Issue 1 , 2012 , Pages 2-25 ; 17515254 (ISSN) Tajbakhsh, A ; Eshghi, K ; Shamsi, A ; Sharif University of Technology
    2012
    Abstract
    Sports scheduling has become an important area of applied operations research in recent years, since satisfying fans and teams' requests and revenues of a sports league and TV networks may be affected by quality of the league schedule. While this type of scheduling problem can be solved by mathematical methods and exact solutions are accessible, it computationally leads to hard problems. The travelling tournament problem (TTP) is defined as minimising total travelling distance for all teams in a league. In this study, a new mathematical model for the TTP with the no-repeater constraint is presented. In addition, a very fast hybrid metaheuristic algorithm is proposed, which combines particle... 

    Modeling and Optimization of a Solar Thermal Storage for Concentrating Solar Power Plants

    , M.Sc. Thesis Sharif University of Technology Shamsi, Hamid Reza (Author) ; Boroushaki, Mehrdad (Supervisor)
    Abstract
    One of the main components of any solar power plant is the heat storage. Implementing heat storage reduc-es the cost of power generation by increasing the capacity factor of the system. This Thesis aims to analyze the operation of heat storages by modeling latent heat
    storage. In this regard, an efficient method named "Method of Characteristics" is utilized. Models developed based on this method are possible to be used for comparison, sensitivity analysis, and optimization due to their low computation time. Sensitivity analysis was carried out based on various parameters such as void fraction, fiUer material size. Results show that using latent heat storage, storage c-apacity is... 

    A Hybrid PSO-SA algorithm for the traveling tournament problem

    , Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009, 6 July 2009 through 9 July 2009, Troyes ; 2009 , Pages 512-518 ; 9781424441365 (ISBN) Tajbakhsh, A ; Eshghi, K ; Shamsi, A ; Sharif University of Technology
    2009
    Abstract
    Sports scheduling has become an important area of applied operationsresearch in recent years, since satisfying the fans and teams' requests andrevenues of a sports league and TV networks may be affected by the quality ofthe league schedule. While this type of scheduling problem can be solvedtheoretically by mathematical methods, it computationally leads to hardproblems. The Traveling Tournament Problem (TTP) is defined as minimizing totaltraveling distance for all teams in the league. In this study, a newmathematical model for the TTP with no-repeater constraint is presented. Inaddition, a very fast hybrid metaheuristic algorithm is proposed, which combinesParticle Swarm Optimization (PSO)... 

    Effect of Household Economic Condition on Mps Reelection

    , M.Sc. Thesis Sharif University of Technology Mollanoori Shamsi, Mohammad (Author) ; Vesal, Mohammad (Supervisor)
    Abstract
    Does the household attribute changes to its economic conditions during the term of the MPs, and chooses to vote with regard to these conditions, including income and employment status, or who decides, regardless of economic characteristics, in this regard Takes? In this study, using micro data of the household income and expenditure survey and building a sample household for each district, we compute economic characteristics for each election district including total income, total cost, employment rate, employment in the government sector, and unemployment rate. . Election data includes the name, vote and status of the candidates for the ninth and tenth Islamic Consultative Assembly... 

    A nonlinear acceleration method for iterative algorithms

    , Article Signal Processing ; Volume 168 , 2020 Shamsi, M ; Ghandi, M ; Marvasti, F ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Iterative methods have led to better understanding and solving problems such as missing sampling, deconvolution, inverse systems, and impulsive and Salt and Pepper noise removal problems. However, the challenges regarding the speed of convergence and or the accuracy of the answer still remain. In order to improve the existing iterative algorithms, a non-linear method is discussed in this paper. The mentioned method is analyzed from different aspects, including its convergence and its ability to accelerate recursive algorithms. We show that this method is capable of improving Iterative Method (IM) as a non-uniform sampling reconstruction algorithm and some other iterative sparse recovery... 

    Optimal lot size with rework, inspection errors and scrap items

    , Article 36th International Conference on Computers and Industrial Engineering, ICC and IE 2006, Taipei, 20 June 2006 through 23 June 2006 ; 2006 , Pages 764-771 Haji, A ; Javadian, N ; Shamsi, R ; Sharif University of Technology
    2006
    Abstract
    The classical economic production quantity (EPQ) model is a well-known and commonly used inventory control technique. A common assumption in the EPQ model is that all units produced are of perfect quality, since in practice non-conforming product or scrap items are possible, this assumption will underestimate the actual required quantity. The objective of this paper is to provide a framework to integrate product of imperfect quality items, inspection errors, rework and scrap items into a single EPQ model. To achieve this objective a suitable mathematical model is defined and the optimal production lot size which minimizes the total cost is obtained  

    The effect of inspection errors on the optimal batch size in reworkable production systems with scraps

    , Article International Journal of Product Development ; Volume 10, Issue 1-3 , 2010 , Pages 201-216 ; 14779056 (ISSN) Haji, A ; Shadrokh Sikari, S ; Shamsi, R ; Sharif University of Technology
    2010
    Abstract
    The objective of this paper is to provide a framework to integrate the existence of products with imperfect-quality items, inspection errors, rework and scrap items into a single Economic Production Quantity (EPQ) model. To achieve this objective, a suitable mathematical model is defined and the optimal production lot size that minimises the total cost is obtained. Sensitivity analysis is carried out for this model. The sensitivity analysis results indicate that the model is very sensitive to defective proportions and type 1 errors of inspection. Nowadays, given the progress made, inspection errors are often ignored. But the findings of this study show that the values of EPQ and total cost... 

    Capital Misallocation and Bank Interest Rate

    , M.Sc. Thesis Sharif University of Technology Shamsi, Mohammad Javad (Author) ; Madanizadeh, Ali (Supervisor)
    Abstract
    To understand the link between the capital misallocation and financial repression in less-developed economies, we put forward a dynamic theoretical macro-finance model with information asymmetry between firms and the bank. While there is no exogenous instrument for the bank to asses firms’ productivity, we let him update his belief about firms’ productivity, based on their records. We show in the presence of asymmetric information and weak formal contract enforcement systems, in the short-run, increasing the interest rate may increase capital misallocation since the moral hazard problem of strategically defaulting of firms can cancel out the screening mechanism of increasing the interest...