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    Optimal Sizing and Operation of CHP Based on Stochastic Programming

    , M.Sc. Thesis Sharif University of Technology Bozorg, Mokhtar (Author) ; Ehsan, Mehdi (Supervisor)
    Abstract
    CHP (Combined Heat and Power) generates electricity and thermal energy simultaneously from input fuel. Since it has high energy efficiency and low installation time, it is an appropriate approach in energy management of residential complexes. In this project, stochastic programming based on Monte Carlo approach is used to handle uncertainties in the optimal sizing of CHP for residential complexes. Availability of CHP, boiler and AC bus as well as the electrical and thermal load forecast errors are considered as stochastic variables. Minimizing system total cost considering the probability of each scenario obtained from the scenario reduction algorithm is the objective function. The system... 

    Integration of Design and Manufacturing Systems Using Neutral Data Structure

    , Ph.D. Dissertation Sharif University of Technology Mokhtar, Alireza (Author) ; Hooshmand, Mahmoud (Supervisor)
    Abstract
    In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,... 

    Machining precedence of 21/2D interacting features in a feature-based data model

    , Article Journal of Intelligent Manufacturing ; Volume 22, Issue 2 , 2011 , Pages 145-161 ; 09565515 (ISSN) Mokhtar, A ; Xu, X ; Sharif University of Technology
    2011
    Abstract
    In process planning, determining feature's machining precedence is an essential step. The task becomes more difficult if features interact with each other, in which case the feature precedence information may suggest multiple machining sequences of the features. This paper considers interacting features in a feature-based model for process planning tasks. For each feature, precedence information is generated considering both roughing and finishing operations. A rule-based system is developed and implemented based on the information about machining precedence of the interacting features. The STEP-NC data model is used as the underlying data model. This model is object-oriented and compliant... 

    Introducing a roadmap to implement the universal manufacturing platform using axiomatic design theory

    , Article International Journal of Manufacturing Research ; Volume 5, Issue 2 , 2010 , Pages 252-269 ; 17500591 (ISSN) Mokhtar, A ; Houshmand, M ; Sharif University of Technology
    2010
    Abstract
    In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. To realise interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i utilising interfaces ii utilising neutral formats. Standard for the Exchange of Product data (STEP) plays a significant role as a neutral data model to integrate design, manufacturing and other activities in product life cycle. To implement a Universal Manufacturing Platform (UMP), a systematic roadmap is required. The current paper proposes such a roadmap using the methodology of Axiomatic Design (AD)  

    Interruptible load contracts implementation in stochastic security constrained unit commitment

    , Article 2010 IEEE 11th International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2010, 14 June 2010 through 17 June 2010, Singapore ; June , 2010 , Pages 796-801 ; 9781424457236 (ISBN) Bozorg, M ; Hajipour, E ; Hosseinia, S. H ; Sharif University of Technology
    2010
    Abstract
    Providing more choices to customers for determining the cost of their required reliability levels is one of the most important targets of restructured power system. Centralized management of reliability in Vertically Integrated Utility (VIU) applying the same policies to different customers is replaced with decentralized management allowing customers to participate in reliability management based on their required reliability levels. Hence, the importance of implementing interruptible load contracts that specifies each customer's reliability level has been increased in power system studies. In this paper, stochastic programming based on Monte Carlo approach has been used to implement... 

    Properties of the Cobalt Base Superalloys and the Effect of Remelting on Microstructure and Chemical and Physical Behavior

    , M.Sc. Thesis Sharif University of Technology Mokhtar, Fatemeh (Author) ; Yoozbashizadeh, Hossein (Supervisor)
    Abstract
    Because of the importance and value of Superalloy, In this research has been treid to remelting scrap of gas turbine blades cobalt based Superalloy X-45, In order to restore it to the cycle of consumption. For this purpose, scraps were remelted under different conditions, for example changing the atmosphere, changing slag composition, changing type of the furnace for remelting and changing time of remelting process. Then in order to investigate effect of the above factors, microstructure were studied by optical microscope and Scanning Electron Microscopy (SEM) And also in order to investigate changings of element composition, chemical analysis were examined by atomic absorption analysis and... 

    Dealing with feature interactions for prismatic parts in STEP-NC

    , Article Journal of Intelligent Manufacturing ; Volume 20, Issue 4 , 2009 , Pages 431-445 ; 09565515 (ISSN) Mokhtar, A ; Xu, X ; Lazcanotegui, I ; Sharif University of Technology
    2009
    Abstract
    Determining the precedence of machining features is a critical issue in feature-based process planning. It becomes more complex when geometric interaction occurs between machining features. STEP-NC, the extension of STEP (ISO 10303) standard developed for CNC controllers, is a feature-based data model. It represents all the geometric and topological product data minus feature interactions. In this paper, machining precedence of interactive and non-interactive STEP-NC features is discussed. Local and global precedence of machining features are defined on the basis of geometric constraints, such as geometric interaction of features and feature approach face and technological constraint such as... 

    Deep Learning Algorithms for Solving Graph Problems

    , M.Sc. Thesis Sharif University of Technology Bozorg, Mahdi (Author) ; Salehkaleybar, Saber (Supervisor) ; Hashemi, Matin (Co-Supervisor)
    Abstract
    Nowadays, thanks to improvement of processing hardware and plenty of data available, artificial intelligence and specifically Deep Learning are being one of the powerful tools for solving different problems. Also graph is one of the powerful tools for modeling different data structures. Graph matching is one of the problems in the field of graph problems.In this thesis we consider the problem of graph matching in Erdos-Renyi graphs. The graph matching problem refers to recovering the node-to-node correspondence between two correlated graphs. Previous works theoretically showed that recovering is feasible in sparse Erdos-R´enyi graphs if and only if the probability of having an edge between a... 

    , M.Sc. Thesis Sharif University of Technology Barzegari, Fatemeh (Author) ; Farhadi, Fathollah (Supervisor) ; Bozorg Mehri, Ramin (Supervisor)
    Abstract
    In the present work, a comprehensive economic, environmental and dynamic behavior analysis with multi-objective optimization for the unit 400 of BandarEmam aromatic plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potential of seven environmental features of the operational plant are qualified and normalized using life cycle assessement (LCA) for both process waste and utility environmental impacts. By choosing the number of trays and feed stage in three distillation columns as decision variables, optimization is performed to determine the best structural variables values based on the total annual cost and Environmental... 

    Applying the Principles of Design for Manufacturing in Commercial Refrigerator and Freezer Industry

    , M.Sc. Thesis Sharif University of Technology Ashkou, Mohammad Shahab (Author) ; Fatahi, Omid (Supervisor) ; Mokhtar, Alireza (Co-Advisor)
    Abstract
    Competitive world of industrial production need more speed and faster reaction for the customer needs. This should be carried out in low cost activities while satisfying what the consumers and customers require. Business of commercial refrigerators and freezers is a big industry targeting small to big customers. In this thesis a systematic method relying on reduction of cost, reworking and unexpected expenditures in product life is utilized. Stands for Design for Manufacturing, DFM is a series of principles and guideline simply to achieve a faultless design of a product so that the non-incurred costs of the product travel through its life cycle become minimized. Freezers and refrigerators... 

    , M.Sc. Thesis Sharif University of Technology (Author) ; Taghikhani, Vahid (Supervisor) ; Bozorg Mehri, Ramin (Supervisor) ; Ghotbi, Siroos (Supervisor)
    Abstract
    Gas hydrate is a nonstoichiometric structure that has been produced from water and gas in appropriate thermal and pressure conditions. There has been a long time that scientists work on predicting hydrate production condition. Predicting the hydrate behavior for pure substances is easier than mixtures; because there are some behaviors of mixtures that we do not know their reasons yet. In this thesis, there has been tried to give a model to describe hydrate reactions to temperature and pressure changes besides predicting the hydrate type and the cage occupancy. Since the hydrate behavior is nonstoichiometric, it is useful to know the cage occupancy to predict the amount of hydrate... 

    Simulation and Optimization of CVD based on CFD

    , M.Sc. Thesis Sharif University of Technology Raoofi Jahromi, Iman (Author) ; Farhadi, Fathollah (Supervisor) ; Bozorg Mehri, Ramin (Supervisor)
    Abstract
    In this project, the steady laminar flow coupled with heat transfer and chemical reactions corresponding to metal organic chemical vapor deposition (MOCVD) process in an axis-symmetrical rotating disk reactor has been simulated based on computational fluid dynamics (CFD) approach to optimize the parameters affecting the thickness of layer deposition. The simulation results have been validated with the benchmark solutions obtained from the literatures for the corresponding cases study. By genetic algorithms five geometrical structures have been optimized to achieve minimal radial changes in the rate of deposition. Using the optimum values, radial variations deposition rate of 22.7% decreased... 

    Exact Lyapunov exponent of the harmonic magnon modes of one-dimensional Heisenberg-Mattis spin glasses

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 77, Issue 10 , 2008 ; 10980121 (ISSN) Sepehrinia, R ; Niry, M. D ; Bozorg, B ; Rahimi Tabar, M. R ; Sahimi, M ; Sharif University of Technology
    2008
    Abstract
    A mapping is developed between the linearized equation of motion for the dynamics of the transverse modes at T=0 of the Heisenberg-Mattis model of one-dimensional (1D) spin glasses and the (discretized) random wave equation. The mapping is used to derive an exact expression for the Lyapunov exponent (LE) of the magnon modes of spin glasses and to show that it follows anomalous scaling at low magnon frequencies. In addition, through numerical simulations, the differences between the LE and the density of states of the wave equation in a discrete 1D model of randomly disordered media (those with a finite correlation length) and that of continuous media (with a zero correlation length) are... 

    Optimizing Structure of Catalysts and Development of Kinetic Parameters for Synthesis Gas to Olefin Reaction

    , Ph.D. Dissertation Sharif University of Technology Shayegh, Flora (Author) ; Ghotbi, Siroos (Supervisor) ; Bozorg Mehri, Ramin (Supervisor) ; Zarrinpashne, Saeid (Supervisor)
    Abstract
    Synthesis gas to light olefin reactions especially propylene production is one of the important path for clean fuel production in gas conversion processes. The object of this study is to define true kinetic model of process first step (e.g. Synthesis gas to light Olefins). For that, kinetic model for Co/Mn/TiO2 catalyst, which has the best conversion and selectivity for propylene, has been developed. Kinetic reaction parameters were measured by kinetic modeling in (220-300)0C temperature , (1-5)bar pressure , H2/CO=(1:3) and (450-600)hr-1 space velocity .After studying with significant models ,the best fitting can obtained with "KPCO P 1/2H2/(1+aPco+bPH2 1/2)2"equation. Later to... 

    Gas sweetening process optimization with economic, Exergy and Environmental criteria

    , M.Sc. Thesis Sharif University of Technology Ehsani, Hojjat Allah (Author) ; Farhadi, Fathollah (Supervisor) ; Bozorg Mehri, Ramin (Supervisor)
    Abstract
    In the present work, a comprehensive economic, environmental and exergy analysis and multi-objective optimization for gas sweetening plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potentials of three environmental features (global warming, acid rain, smog formation) of the operational plant are quantified and normalized using life cycle assessment (LCA) for both process waste and utility environmental impacts.Acid rain index is determined as the most important environmental impactindex in this unit. By choosing proper decision variables based on sensitivity analysis, LCA and EA results, optimization is performed to... 

    A Novel Road Map to Develop a Feasible Framework for Collaboration Management in Tele-working Paradigm Based on Cloud Computing Theory

    , M.Sc. Thesis Sharif University of Technology Edalat Javid, Negin (Author) ; Fattahi Valilai, Omid (Supervisor) ; Mokhtar, Alireza (Co-Advisor)
    Abstract
    Telework is an adaptable method for working which covers an extensive variety of work exercises in circulated associations comprised of people with robots and independent frameworks. From the levels of Nano and micro frameworks and gadgets the distance to the level of worldwide undertaking systems, beneficial work is reshaped by E-Work or Telework or Telecommute. The current work stresses on the part of learning administration as an empowering influence of E-Working standard. The four primary circles of information in e-Work related are: ‘‘e-Work”, ‘‘Integration , Coordination and Collaboration”, ‘‘Distributed Decision Support” and ‘‘Active Middleware”. Cloud computing can be distinguished... 

    Model reduction techniques for unstable second order-form systems

    , Article IEEJ Transactions on Electrical and Electronic Engineering ; Volume 16, Issue 3 , 2021 , Pages 445-454 ; 19314973 (ISSN) Ali, S ; Mohd Mokhtar, R ; Haider, S ; Bukhari, S. H. R ; Rasool, A ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Abstract
    In the present work, multiple non existing model order reduction (MOR) techniques for unstable second-order form systems (SOSs) are proposed. For unstable SOSs, continuous-time algebraic Lyapunov equations get unsolvable that halt the reduction process. To avoid this problem, unstable SOS is first decomposed into stable and unstable portions and balanced truncation is applied to the stable part. The obtained reduced order model (ROM) for the stable portion is augmented with the unstable portion to obtain the overall reduced system. It is observed that the second-order structure in ROM for the first technique gets lost as well as augmented unstable dynamics degrade the ROM performance. To... 

    Model reduction techniques for unstable second order-form systems

    , Article IEEJ Transactions on Electrical and Electronic Engineering ; Volume 16, Issue 3 , 2021 , Pages 445-454 ; 19314973 (ISSN) Ali, S ; Mohd-Mokhtar, R ; Haider, S ; Bukhari, S. H. R ; Rasool, A ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Abstract
    In the present work, multiple non existing model order reduction (MOR) techniques for unstable second-order form systems (SOSs) are proposed. For unstable SOSs, continuous-time algebraic Lyapunov equations get unsolvable that halt the reduction process. To avoid this problem, unstable SOS is first decomposed into stable and unstable portions and balanced truncation is applied to the stable part. The obtained reduced order model (ROM) for the stable portion is augmented with the unstable portion to obtain the overall reduced system. It is observed that the second-order structure in ROM for the first technique gets lost as well as augmented unstable dynamics degrade the ROM performance. To... 

    Developing an Applied Model for Energy Management in Dairy Production Industry

    , M.Sc. Thesis Sharif University of Technology Bahmanpour khalesi, Ahmad Reza (Author) ; Mokhtar, Ali Reza (Supervisor) ; Miremadi, Ali Reza (Supervisor)
    Abstract
    Reviewing trends of energy consumption in the world reveals that sooner or later energy resources will be depleted. This concerning rate of consumption has brought about more greenhouse gases (GHG) emission influencing deleteriously on environment and climate. Human has continued energy consumption to maintain and improve the quality of his life through industrial production. Industry as a significant energy user owns considerable contribution to this consumption. Several attempts have been carried out to develop energy management systems in order to improve the energy efficiency of industrial sectors. Whilst they are comprehensive and could be applied to any sector, there is lack of... 

    Duty-cycle division multiplexing (DCDM)

    , Article Optics and Laser Technology ; Volume 42, Issue 2 , 2010 , Pages 289-295 ; 00303992 (ISSN) Amouzad Mahdiraji, G ; Khazani Abdullah, M ; Malek Mohammadi, A ; Abas, A. F ; Mokhtar, M ; Zahedi, E ; Sharif University of Technology
    2010
    Abstract
    A multiplexing technique, which is based on duty-cycle division, is proposed. The channel multiplexing and demultiplexing are performed electrically at the single user bit rate, which is very economic. In a three-user system (3×10 Gb/s), the simulation results show that the best receiver sensitivity value achieved is -30.1 dBm with an optical signal-to-noise ratio (OSNR) of 22.3 dB, while the chromatic dispersion tolerance ranges from 192 to 280 ps/nm. Migration from 30 to 120 Gb/s is achieved with the penalty of 6.4 and 5.2 dB in the receiver sensitivity and OSNR, respectively, for the worst user