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movahhedy--mohammad-reza
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Kinetic Study of Heterogeneous and Homogeneous Catalytic Reactions in Molecular and Ionic Solvents and Their Mixtures
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Habibi Yangjeh, Aziz (Supervisor)
Abstract
Solvatochromic parameters (ETN: normalized polarity parameter, π*: dipolarity/polarizability, β: hydrogen-bond acceptor basicity, α: hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (2-hydroxyethylammonium formate) at 25 ◦C. The applicability of nearly ideal combined binary solvent/Redlich-Kister equation was proved for the correlation of various solvatochromic parameters with solvent composition. Solute-solvent and solvent-solvent interactions were applied to interpret the results. Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/Al2O3, was carried out in...
Improvement of Security Features of Communication Networks with Network Coding
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Supervisor)
Abstract
In this thesis, we study security features of the networks which use linear network coding to multicast information to some nodes of the network in presence of a wiretapper and also an active intruder. We consider information theoretic security in which we assume no computation limits for enemy. Thus, we take advantage of the essence of network coding instead of cryptographic tools to improve security features of the network. First, we show how providing shannon security for such networks in presence of wiretapper, leads to different cost in multicast rate, depending on initial network code designed. Based on this, we present a modified secure network code design which can provide perfect...
Mechanical Properties of Al2O3-ZrO2 Nanocomposites Fabricated by Gelcasting
, M.Sc. Thesis Sharif University of Technology ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
Gelcasting is a new ceramic forming technique getting worldwide attention. The process is based on casting of slurry; containing powder, water and water-soluble organic monomers. The premix solution was prepared using Acrylamide as a monomer and Methylene bisacrylamide as a crosslinker with AM:MBAM ratio of 25:1, and Poly Acrylic Acid Sodium as a dispersant (1 wt% based on ceramic powders weight). A series of Al2O3/ZrO2 ceramic nanocomposites with 15, 17.5 and 20 wt% content of ZrO2 and 40, 43, 45, 47, 50, 53 and 55 vol.% of solid loading were fabricated by gelcasting. After casting the mixture, the monomer was polymerized to form gel parts. Drying, burning out and sintering completed the...
Numerical Solution of Stochastic Differential Equations with Different Methods
, M.Sc. Thesis Sharif University of Technology ; Zohuri Zangeneh, Bijan (Supervisor) ; Razvan, Mohammad Reza (Supervisor)Flow-Field Modeling and Performance Prediction of Axial-Flow Compressors using Streamline Curvature Method
, M.Sc. Thesis Sharif University of Technology ; Ghofrani, Mohammad Bagher (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
Abstract
Compressors are one of the most important components of gas turbines and turbomachinery processes. Thus some precise and quick tools are needed for design and analysis purposes. Despite of vast development of Computational Fluid Dynamics (CFD) tools, Through-Flow Streamline Curvature Methods (SCM) has retained their position. 2D and quasi-3D forms of SCM in combination with CFD results nowadays make more than 80% of turbomachinery design process of axial and radial compressors and turbines. In this thesis, the basics of developing a tool for axial-flow compressor analysis are introduced. As will be seen, this analysis tool can be used for design purposes too. The method that is chosen for...
Direct Synthesis of Dimethyl Ether from Carbon Dioxide
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Aghaziarati, Mahmoud (Co-Advisor) ; Kazemian, Masoud (Co-Advisor)
Abstract
In this research, direct synthesis of dimethyl ether (DME) from CO2 hydrogenation in three phase slurry reactor was investigated. Bifunctional catalysts composed of Cu- ZnO-Al2O3-ZrO2 as hydrogenation component and zeolite Na-Mordenite as dehydration component, with different Al2O3 and ZrO2 contents were synthesized by coprecipitating sedimentation and influences of Al2O3 and ZrO2 on CO2 conversion and DME selectivity were evaluated. Results show, both Al2O3 and ZrO2 enhanced conversion, but Al2O3 markedly increase selectivity of DME. However, when the total contents of Al2O3 and ZrO2 was increased up to 16 wt% , CO2 conversion and DME selectivity remarkably decreased. BET and XRD analyzes...
Efficient Visibility Computation and Simplification in Different Environments
, Ph.D. Dissertation Sharif University of Technology ; Ghodsi, Mohammad (Supervisor)
Abstract
In this thesis, we considered several types of the visibility problem. These problems include computing the visibility polygon of a point observer inside a polygonal domain, maintaining visibility polygon of a moving point observer, visibility coherence in space, maintaining visibility polygon of a moving segment observer and visibility dependent simplification. Furthermore, we considered these problems in both offline and streaming settings. These problems arise in different practical areas, such as computer graphics, machine vision, robotics, motion planning, geographic information systems (GIS) and computational geometry. We obtained effective theoretical results as well as superior...
Development of Model for Evaluation of Energy Technologies and R&D Planning
, Ph.D. Dissertation Sharif University of Technology ; Ghofrani, Mohammad Bagher (Supervisor) ; Saboohi, Yadollah (Supervisor)
Abstract
In this research work an analytical instrument has been developed for assessment of energy technologies, R&D resource allocation and technology development. Development of new technologies has been considered according to the specific conditions of developing countries. The analytical instrument includes two models interlinked with each other: energy technology assessment and optimal control of innovation activities. Energy technology assessment and prioritization of new energy technologies are provided by the model of the energy supply system that contains a detailed representation of current and emerging technologies characterized in terms of their technical indices. The results of this...
Computer Simulation of Arthrometric Diagnosis of Partial ACL-Injured Knee
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Knee pain and injuries are very common in athletes. Anterior cruciate ligament (ACL) injury is one of the most important reason of knee acute and chronic pains. As ACL plays a significant role in knee stability and due to amount of reported ACL related injuries, much effort has been placed on finding proper and on time diagnosis and treatment of these injuries. Arthrometric methods are the most non-invasive reliable diagnosis option; however they are not fully capable of separating partial injuries from intact joint. This weakness can be investigated by quantifying the tests using computer simulations; so far few studies have been conducted toward this goal. In this study a two dimensional...
Studying the Effect of Dynamic Vulcanization of EPDM on Scratch Resistance of Rubber-Modified Polypropylene
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
Polypropylene is a commodity thermoplastic with good physical and mechanical properties along with fair recyclability and cost. However, the application of polypropylene is limited in some cases, especially in automotive industry, as a result of inappropriate toughness of this material. Although rubber toughening of polypropylene is a method used to increase the toughness, it reduces scratch resistance. Studies performed in the polymer group of this department reveal that the cavitation resistance of elastomeric phase and its bonding to the matrix are two effective parameters in scratch resistance of this material. In this study, it is tried to alter the cavitation resistance of elastomeric...
Theoretical and Experimental İnvestigation of C-n İnternal Rotation in Ethyl Tetrahydro-1(2H)-Pyridine Carbdithioate and Ethyl 1-pyrrolidine Carbodithioate by Dynamic Nuclear Magnetic Resonance Spectroscopy
, M.Sc. Thesis Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor)
Abstract
In this project, investigation of C-N internal rotation in ethyl tetrahydro-1(2H)-pyridine carbdithioate and ethyl 1-pyrrolidine carbodithioate were investigated by dynamic nuclear magnetic resonance spectroscopy. The 1HNMR and 13CNMR spectra were taken at the variable tempratures around the coalescence temprature. Thermodynamic parameters were calculated by analysing the spectra and the outcomes were compared by the theoretical results. For ethyl tetrahydro-1(2H)-pyridine carbdithioate ∆G‡ was 14.3 (kcal/mol) and for ethyl 1-pyrrolidine carbodithioate ∆G‡ was 17.0 (kcal/mol) which were in accordance with the theoretical results. The analysis were done by the Spinworks program which...
Study of Mechanical Properties of PP/r-PET Composite Reinforced with Flax Fiber
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Bagheri, Reza (Supervisor)
Abstract
Recycling of polymers, with the aim of environmental protection and economical benefits, is important procedure, which is constantly developing. In this study the effect of the incorporation of recycled PET(r-PET) and recycled polypropylene/Flax(r-PP/Flax) to PP at low (20wt %) and medium content (40wt %) of r-PET was investigated. Polymer compounds were prepared by twin screw extruder followed by injection moulding. The effect of r-PP/Flax and r-PET on PP was evaluated using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetery (DSC), rheological behavior, and mechanical properties (tensile modulus, yield strength, and charpy notched impact...
A Practical Examination of the Antibacterial and Absorption Effect of Bioceramic Apatite-Coated TiO2 as a Modified Nanophotocatalyst
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Haghighi, Saeed (Co-Advisor)
Abstract
Ag / AgCl /TiO2 , 2 Ap / Ag / AgCl /TiO , 2 AgI /TiO and 2 Ap / AgI /TiO were prepared by the deposition-precipitation method on 2TiO (P25) nanoparticles and their photocatalyctic activities have been investigated under visible light and dark environments. Cationic surfactant plus 2 PVPI (topical solution and dry powder) as an iodine ion source and nonionic surfactant plus KI as an iodide ion source were used to prepar 2 AgI /TiO . In less than 30 minutes, 2 AgI /TiO which has been resulted from combination of cationic surfactant and 2 PVPI showed high efficiency on Escherichia coli under visible light when small quantities of it is used . However, AgCl sample prepared with cationic...
Synthesis of β-Amino Ketones Using Titania Based on Solid Acid as A Catalyst
, M.Sc. Thesis Sharif University of Technology ; Mahmoudi Hashemi, Mohammad (Supervisor)
Abstract
Enanthioselective synthesis of biological molecules are so important in synthetic chemistry, and because of their biological activities, β-amino carbonyl compounds have earned so much attention in this area of chemistry. Mannich reaction is a classical method for synthesis of these molecules. The Mannich reaction is a three-component reaction between an enolizable CH-acidic carbonyl compound, an amine, and an aldehyde producing β-amino carbonyl compounds. But acidic or basic difficult circumstances, long reaction time, low yield and enantioselectivity, are the drawbacks of classical methods. In this project, we used titania-based solid acid as an enantioselective catalyst to overcome these...
Supply Chain Network with Normal Demand
, M.Sc. Thesis Sharif University of Technology ; Modarres Yazdi, Mohammad (Supervisor)
Abstract
In this thesis, we focus on some internal organization issues of the supply chain; in particular, we analyze some network design problems which are typical of producer companies. The aim is to optimize the flow of goods through the literature distribution network, from the plants where the goods are produced (supply points) to the demand points, which are essentially distributors such as wholesalers or retailers. The system addresses a class of distribution network design problems, which is characterized by multiple product families, a central manufacturing plant site, multiple central warehouses and distribution center, and retail outlets (customer zones) which demand multiple units of...
Investigation of Palladium Growth on Nanostructured Tungsten Oxide Films
, M.Sc. Thesis Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Iraji Zad, Azam (Supervisor)
Abstract
We have studied making and characterization of gasochromic thin films that are used as gas sensors. Gasochromic films consist of an electronchromic layer and a catalyst layer. Addition of palladium to the surface , increased the sensitivity and decreased the working temperature. The used electrochromic layer was tungsten oxide. WO3 films were fabricated by (PLD) method. The substrates were slide glasses. Structure, morphology and composite of tungsten oxide and optical property of films depend on condition of deposition. The pressure of oxygen gas in chamber and temperature of substrate are two factors that can affect in deposition. We can make layers with different morphology by variation...
Numerical Simulation of Cavitation in Rigid Body Motion in Unsteady State
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor)
Abstract
In this thesis, cavitating flow over 2D/3D geometries of cavitators and projectile bodies in stationary and moving conditions are simulated using the "Volume of Fluid" (VOF) technique. The main application of VOF model is for simulating free surface flows. In this work, another capability is added to the VOF algorithm to solve for gas phase and by applying analytical-numerical mass transfer models, cavitation phenomenon is simulated. The developed algorithm precisely simulates the geometrical parameters of supercavities such as dimension and shape in a wide range of cavitation numbers. In addition, the flow parameters of supercavity such as drag coefficient, pressure coefficient inside the...
Synthesis & Characterization of Nano Zeolite SAPO-34 Membranes on Alumina Supports and Evaluation of Their Performance for Gas and Vapor Separation
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor) ; Kazemian, Hossein (Supervisor)
Abstract
A Novel synthesis method to assemble of nano crystalline SAPO-34 molecular sieves crystalline is successfully developed at a supercritical condition. The environmental and operating conditions are investigated through a Taguchi L-9 orthogonal array and optimum synthesis conditions in order to reach highest crystallinity and smallest crystalline. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), thermal method of analysis (e.g. TG-DTA), and infra red spectroscopy (FT-IR) techniques. In comparison to conventional hydrothermal methods, using a supercritical hydrothermal approach leads to the higher purity, reduced particle size, and change of...
Iteration Control in Design Process
, Ph.D. Dissertation Sharif University of Technology ; 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....
Analogy Indices in the Engineering of Large Socio-Economic Systems (With Emphasis on Aerospace Education Systems)
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
Throughout the history of science, mankind has always invented tools and methods to help him deal with complex problems, means that constitute the science. Systems theory and all the tools and methods introduced by it to analyze and judge simple to complex systems, although relatively recent, has left an enormous impact on current life style by being one those very important sciences that make dealing with complex systems easier. On the other hand, the importance of educational systems and their impact over the success of societies and large systems is close to obvious. In today’s world, having an effective educational system which can deliver required information to people and prepare them...