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bozorg-mehri--ramin
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, M.Sc. Thesis Sharif University of Technology ; 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...
, M.Sc. Thesis Sharif University of Technology ; 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 ; 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...
Optimizing Structure of Catalysts and Development of Kinetic Parameters for Synthesis Gas to Olefin Reaction
, Ph.D. Dissertation Sharif University of Technology ; 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 ; 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...
Optimal Sizing and Operation of CHP Based on Stochastic Programming
, M.Sc. Thesis Sharif University of Technology ; 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...
From Al-Khwarizmi to algorithm
, Article International Conference Joint with the 29th International Olympiad in Informatics, IOI 2017, 28 July 2017 through 4 August 2017 ; Volume 11, Issue Special Issue , 2017 , Pages 71-74 ; 18227732 (ISSN) ; Sharif University of Technology
Vilnius University
2017
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) ; 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...
Weak solutions to Vlasov-McKean equations under Lyapunov-type conditions
, Article Stochastics and Dynamics ; Volume 19, Issue 6 , 2019 ; 02194937 (ISSN) ; Stannat, W ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
We present a Lyapunov-type approach to the problem of existence and uniqueness of general law-dependent stochastic differential equations. In the existing literature, most results concerning existence and uniqueness are obtained under regularity assumptions of the coefficients with respect to the Wasserstein distance. Some existence and uniqueness results for irregular coefficients have been obtained by considering the total variation distance. Here, we extend this approach to the control of the solution in some weighted total variation distance, that allows us now to derive a rather general weak uniqueness result, merely assuming measurability and certain integrability on the drift...
Harmonic effects optimization at a system level using a harmonic power flow controller
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 28, Issue 5 , 2020 , Pages 2586-2601 ; Mokhtari, H ; Sharif University of Technology
Turkiye Klinikleri
2020
Abstract
Increase of nonlinear loads in industries has resulted in high levels of harmonic currents and consequently harmonic voltages in power networks. Harmonics have several negative effects such as higher energy losses and equipment life reduction. To reduce the levels of harmonics in power networks, different methods of harmonic suppression have been employed. The basic idea in all of these methods is to prevent harmonics from flowing into a power network at customer sides and the point of common coupling (PCC). Due to the costs, none of the existing mitigating methods result in a harmonic-free power system. The remaining harmonic currents, which rotate in a power network according to the system...
Lebesgue function for multivariate interpolation by radial basis functions
, Article Applied Mathematics and Computation ; Volume 187, Issue 1 SPEC. ISS , 2007 , Pages 306-314 ; 00963003 (ISSN) ; Jokar, S ; Sharif University of Technology
Elsevier Inc
2007
Abstract
Multivariate interpolation and approximation is a powerful tool for intuition of real world. In this paper we study Lebesgue function and Lebesgue constant for multivariate interpolation by conditionally positive definite RBFs. Also we give a conjecture about similar Bernstein and Erdös problem to multivariate case. © 2006 Elsevier Inc. All rights reserved
On the existence of periodic solutions for nonlinear ordinary differential equations
, Article Scientia Iranica ; Volume 15, Issue 2 , 2008 , Pages 182-185 ; 10263098 (ISSN) ; Shadman, D ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
In this paper, the existence of periodic solutions of autonomous ordinary differential equations of a 4th and 5th order is investigated. The method used is based on the Brower's degree theorem using the homotopy invariant a property of a topological degree. © Sharif University of Technology, April 2008
On the existence of periodic solutions for the quasi-linear third-order differential equation
, Article Journal of Mathematical Analysis and Applications ; Volume 261, Issue 1 , 2001 , Pages 159-167 ; 0022247X (ISSN) ; Niksirat, M ; Sharif University of Technology
2001
Abstract
In this paper we consider the nonlinear third-order quasi-linear differential equationx‴+k2x′=εfx,x′,x″and obtain some simple conditions for the existence of a periodic solution for it. In so doing we use the implicit function theorem to prove a theorem about the existence of periodic solutions and consider one example to show the realizability of the conditions. The validity of the conditions for the parameter-free problemx‴+k2x′=fx,x′,x″also is considered. © 2001 Academic Press
Periodic solution of a certain non-linear third order differential equation
, Article Scientia Iranica ; Volume 11, Issue 3 , 2004 , Pages 181-184 ; 10263098 (ISSN) ; Shadman, D ; Sharif University of Technology
Sharif University of Technology
2004
Abstract
In this paper, the third order differential equation x‴ + ψ (x′)x″ + (κ2 +ø (x))x′ + f(t, x = e(t) is considered. Under certain conditions on the functions appearing in the differential equation, the existence of periodic solutions is proved. Similar problems have been treated by authors in [4,6,7]. However, the method employed here is used by Reissig [1] and the results obtained are, in fact, a generalization of those in [1-3]. The conditions imposed on the nonlinear terms do not require the ultimate boundedness of all solutions. © Sharif University of Technology
A Data Replication Algorithm to Improve Performance of Cloud Data Centers
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
The daily growth of cloud computing usage for data based applications and Internet services has caused many challenges in the sense of storage cost, data access performance, QoS provision such as availability, scalability, pay-as-you-go model conformation and etc. Data replication is one of the most important mechanisms for data management in distributed systems. It creates some replicas of data and distributes them to the network. The number of replicas, the time for creating a new replica, the way of their distribution among the nodes and replica replacement strategy in the case of storage unavailability are some important challenges in data replication context. Replication is extensively...
Automated Negotiation in Electronic Commerce
, M.Sc. Thesis Sharif University of Technology ; Ramezanian, Rasoul (Supervisor)
Abstract
Extensive growth of the internet has had a profound effect on the business environment and rise to a phenomenon known as electronic commerce.electronic commerce has an important role in improvement of organization performance and likewise,has influence in everyday life.despite its name,e commerce is not fully automated.typically,online transactions require a significant level of human intervention.to achieve high degree of automation,we need a new model of software.this model is based upon the notion of agents.agents can act in different stages of e-commerce.one of the most important of these stages is negotiation.negotiation capabilities are essential for e-commerce systems.the agents...
Deep Learning Algorithms for Solving Graph Problems
, M.Sc. Thesis Sharif University of Technology ; 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...
Boundedness and regularity with nonlinear dependence of Hessian and gradient
, Article Scientia Iranica ; Volume 15, Issue 6 , 2008 , Pages 553-557 ; 10263098 (ISSN) ; Nojumi, M. H ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
Sufficient conditions for the boundedness and regularity of a function, whose partial derivatives satisfy a certain set of equations, are presented. Energy methods are used to establish these results. The asymptotic behavior of the gradient toward a constant function is also investigated. © Sharif University of Technology
On the existence of periodic solutions for certain differential equations
, Article Journal of Computational and Applied Mathematics ; Volume 174, Issue 2 , 2005 , Pages 239-249 ; 03770427 (ISSN) ; Niksirat, M. A ; Sharif University of Technology
2005
Abstract
Here we are concerned with the problem of the existence of periodic solution for certain second and third-order nonlinear differential equations. Our method here is to consider the problem as an eigenvalue problem and treat it by the topological degree theory. In particular we establish the conditions of the existence of periodic solution first for a simpler system which is homotopic to the original system and then generalize the obtained results for the focal system. The method employed here is applicable also for a system of nonlinear differential equations just with simple modifications. Finally, we present some specific examples numerically to show that the results are valid and...
Some computable results on the existence of periodic solutions for singular non-autonomous third order systems
, Article Applied Mathematics and Computation ; Volume 163, Issue 1 , 2005 , Pages 51-60 ; 00963003 (ISSN) ; Niksirat, M. A ; Sharif University of Technology
2005
Abstract
Here we are concerned with the existence of periodic solution for nonlinear non-autonomous third order system of ordinary differential equations with singular terms. Our method here is based on the topological method in the sense that we conclude some computable results for the focal system from a homotopic nonsingular system. The aim is to obtain sufficient conditions for which the system has periodic solution whenever the value of deformation with respect to the first variation of the nonsingular subsystem is sufficiently small. The method presented here is constructive in the sense that the existence of periodic orbits can be verified numerically as well as computed if any. For this, we...