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aleebrahim-dehkordi--mohammad-ali
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Interaction of Surface and Interfacial Waves Over Fluid Mud Bed
, Ph.D. Dissertation Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
Motivated by the role of interfacial instabilities in sediment resuspension, this paper provides quantitative measurements of the long-time behavior of the interfacial waves and the changes in vertical density during motion of a surface wave over a muddy bed. After an initial fluidization process, a 3D quasi-standing interfacial wave was observed at the interface as a result of a resonant wave interaction with the surface wave. In the process, the quasi-standing wave started growing exponentially at a rate of 0.052-0.081 1/s and then reached a maximum amplitude (kexpb=0.77-0.83). The interfacial wave then took a downward trend in the transition stage and approached a steady state...
Gidelines of Executing the Petroleum Industry Vision in Iran (N.I.O.C)
, M.Sc. Thesis Sharif University of Technology ; Sharifian, Mohammad Ali (Supervisor) ; Mobini Dehkordi, Ali (Supervisor)
Abstract
Iran is a country with bright cultural and historical background, and rich natural resources. It is also one of the important oil and gas exporters with a special geographical situation. The world energy needs are increasing rapidly and that requires higher oil production. On the other hand, oil is Iran’s most important source of revenue and the country is highly dependent on oil export. Islamic republic of Iran’s (I.R.I) 1404 program is visioning the country to be the first producer of material in the region, the second producer of oil in OPEC, and the third producer of gas in the world. Although critical conditions can slow down the process to achieve the vision, implementing this vision...
Experimental investigation of instability of fluid mud layer under surface wave motion
, Article Physics of Fluids ; Volume 34, Issue 3 , 2022 ; 10706631 (ISSN) ; Jamali, M ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Motivated by environmental impacts of surface-wave induced mixing of fluid mud with clear water in nearshore areas, this paper presents quantitative measurements of excitation of interfacial waves over a bed mud layer by a surface wave in a wave flume. After an initial fluidization process, a quasi-standing interfacial wave comprised of four interfacial waves was observed at the interface as a result of a resonant wave interaction with the surface wave. The interfacial waves were subharmonic to the surface wave and traveled at the maximum possible angle from it. The growth rate and kinematic properties of the interfacial waves were measured, and good agreement with theoretical predictions of...
Laboratory study of instability-driven mixing of fluid mud under surface wave motion
, Article Physics of Fluids ; Volume 35, Issue 8 , 2023 ; 10706631 (ISSN) ; Jamali, M ; Sharif University of Technology
American Institute of Physics Inc
2023
Abstract
Motivated by the role of interfacial instabilities in sediment resuspension in coastal areas, this paper provides quantitative measurements of fluid mud density profile during motion of a surface wave over a muddy bed in a wave flume. Following a fluidization process, a quasi-standing interfacial wave grew owing to a resonant wave interaction with the surface wave. In the process, the quasi-standing wave reached a maximum amplitude and then approached a steady state. The long-time behavior of the resonantly generated interfacial wave and the changes in vertical density profile during wave motion were recorded. Increasing the surface wave frequency led to a higher initial growth rate of the...
Effect of variable Geometry on a Vertical Two Phase Flow
, M.Sc. Thesis Sharif University of Technology ; Nouri Borujerdi, Ali (Supervisor)
Abstract
The aim of this research is to consider the effect of geometric changes on pumping performance of two phase gas-fluid flow in a vertical pipe. The idea is to inject a light gas to the bottom of a tube full of fluid so we will obtain an upward flow due to density differences. Potential benefits of this device are numerous such as dredging of river estuaries and harbors, sludge extraction in sewage treatment plant, water treatment and many others. There are almost four distinct flow patterns which occurs in the rise pipe, bubbly flow, slug flow, churn flow and annular flow that each of them require special conditions. heat transfer between two phases, phase changes, mass and volume rate...
Oxidative Desulfurization of Light Fuel Oils
, Ph.D. Dissertation Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Shahrokhi, Mohammad (Supervisor)
Abstract
Oxidative desulfurization (ODS) is one of the desulfurization processes that posseses several important advantages such as mild operating conditions. In the present work, oxidative desulfurization of kerosene with a total sulfur content of 2335 ppm and gas oil with a total sulfur content of 7990 ppm were carefully investigated. By evaluation of different oxidation systems, the hydrogen peroxide-formic acid system was selected for the oxidation of sulfur-containing compounds of the light fuel oils. The effects of main operating parameters of the oxidation system including temperature, hydrogen peroxide to sulfur molar ratio (O/S), and formic acid to sulfur molar ratio (Acid/S) on the...
Dehydration of THF Using Different Zeolites
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
The aim of this work was to investigate the performance of different kinds of Linde type A zeolite (LTA) for the dehydration of Tetrahydrofuran (THF)-water solution. Batch experiments were carried out to evaluate the effect of various operating parameters such as contact time, initial concentration, mixing temperature (10, 15,and 25 C), amount of adsorbent, and zeolite type(3A, 4A, and 5A zeolites). In theoretical studies, we took the advantage of several types of equilibrium model isotherms such as Langmuir, Freundlich, Dubin-Kaganer-Radushkevich (DKR) to describe the experimental adsorption data. Besides, three adsorption kinetic models including pseudo-first-order, pseudo-second-order,...
Units in Witt Rings
, M.Sc. Thesis Sharif University of Technology ; Gholamzadeh Mahmoudi, Mohammad (Supervisor)
Abstract
This master’s thesis has three chapters. In the first and second chapters provided all the necessary preparations for the third chapter to describes the following article: Lewis, D. W, Units in Witt rings, Commun. Algebra 18, no. 10, 3295-3306 (1990).The first chapter includes an introduction of quadratic forms and Witt ring on fields with characteristic unequal 2, studing W b(F) in the category of commutative rings and introduction of formally real and nonreal fields. In this chapter there are important theorems such as Witt’s Decomposition and Cancellation Theorem, Cassels Representation, Springer and Pfister’s Local-Global Principle. The second chapter introduces the discretely valuated...
Characteristics of Liquid Crystal Near a Flat Surface Using EES Potential
, M.Sc. Thesis Sharif University of Technology ; Ejtehadi, Mohammad Reza (Supervisor)
Abstract
The study of the interaction between ellipsoid particles and the flat wall is the basis for understanding phenomena such as the passage of colloidal particles through the membrane and the order resulting from the presence of the wall in liquid crystals. Previous studies on liquid crystal systems confined between two walls have shown that topological constraints and the surface interaction of particles with the wall change the order behavior and create a surface layer near them. The thickness of this surface layer is about a few molecules, and this helps to achieve the result observed in the laboratory, in computer simulations. LAMMPS software is one of the most powerful codes available for...
Characterization of Micromixing and Determination of Mass-Transfer Coefficient in a new Double-Spinning-Disk Contactor
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
High mixing efficiency and high liquid-liquid mass transfer rate are two key features of spinning disk contactors. This work presents the experimental investigation of mixing and liquid-liquid mass transfer characteristics in a new double coaxial spinning disks contactor. The micromixing efficiency was investigated using a standard system of competitive parallel reaction known as iodide/iodate test reaction. The influences of various operating conditions such as the rotational speed of the disks, the direction of rotation, the feed radial location, the feed distribution pattern, the distance between the disks, and the feed flow rate on the mixing quality were examined carefully. The obtained...
A New Approach to Employ Fuzzy Logic for Airport Expansion
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
Airports are critical connectors in the air transportation operational system. In order to meet their operational, economic and social obligations in a very volatile environment, airports need to embrace change rather than resist it. Long-term airport planning has become a complex issue due to the constant growth in air traffic demand. In this context, the thesis puts forward an innovative approach to planning and decision making for various component of airport.in this has been used fuzzy logic decision making method to develop airport in all respect in order to plan balanced growth. Top airports are successful experience in airport expansion planning which can be pattern for other airports...
A Critical Study of the Civil Disobedience
, M.Sc. Thesis Sharif University of Technology ; Taheri Khoramabadi, Ali (Supervisor)
Abstract
Civil disobedience, as a protest mechanism, is one of the important topics discussed in political philosophy. The background of this idea dates back to Henry Thoreau, and later John Rawls played a very influential role in its theoretical development. The aim of this thesis is to conduct a critical study of this idea, focusing on the issue of its justification. The emphasis on the justification is placed firstly due to its central position in the discussions of normative political philosophy and secondly due to the controversial nature of civil disobedience in opposing official legal procedures. To this end, we have first discussed the definition of civil disobedience in two traditional and...
Modification of carbohydrate polymers via grafting in air. 1. Ceric-Induced synthesis of starch-g-polyacrylonitrile in presence and absence of oxygen [electronic resource]
, Article Starch - Starke ; Volume 54, Issue 3-4, pages 140–147, April 2002 ; Zohurian Mehr, Mohammad J
Abstract
Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N2) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the...
Modification of carbohydrate polymers via grafting in Air. 2. Ceric-Initiated graft copolymerization of acrylonitrile onto natural and modified polysaccharides [electronic resource]
, Article Starch - Stärke ; Volume 54, Issue 10, pages 482–488, October 2002 ; Zohuriaan-Mehr, Mohammad J
Abstract
Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous...
Modeling of in Plane Behavior of Retrofitted Adobe Walls with Finite Element Method under Cyclic Loading
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Ali (Supervisor) ; Ghannad, Mohammad Ali (Co-Advisor)
Abstract
Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by...
Silica chloride/wet SiO2 as a novel heterogeneous system for the deprotection of acetals under mild conditions [electronic resource]
, Article Phosphorus, Sulfur, and Silicon and the Related Elements ; Volume 178:2667-2670, Issue 12, 2003 ; Pourjavadi, Ali ; Zolfigol, Mohammad Ali ; Bamoniri, Abdolhamid
Abstract
A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition
Synthesis of Hybrid Nano-Adsorbent for CO2 Adsorption
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Rashidi, Ali Moradi (Supervisor)
Abstract
CO2 as a green house gas plays a significant role in the global warming and weather changes. Absorption by means of amine solutions is the main industrial technique for separating of CO2 from gas mixtures. Hazards associated with high temperature during solvent recovery, large size of equipment, corrosion, solvent degradation, and other reasons has made researchers to look for alternative processes such as adsorption. The aim of this study was to synthesis and modify the nano adsorbent for CO2 capture. To fulfill this purpose, various nano silica structures were synthesized and the amount of adsorption of each sample was determined. To investigate the performance capability nano_adsorbents,...
Modeling of Spray Granulation
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Fluidized bed spray granulation is an important powder production process with several key advantages compared to other powder production processes, such as spray drying. Moreover, in fluidized bed granulators, whole process takes place in just one apparatus and there is no need to side processing. Most important characteristics and essential part of fluidized bed granulation is the wetting of primary particles by atomized liquid binder to coating the primary particles and producing granules. To date, a lot of research has focused on modeling and understanding of the separate particle growth mechanisms which have been integrated into the population balance models. Although, these concepts...
Theoretical and Experimental Investigation of Preparation of Distillate Water by Combination of CSP and MED Methods
, M.Sc. Thesis Sharif University of Technology ; Molaee Dehkordi, Asghar (Supervisor)
Abstract
With the depletion of fossil resources, price of these energy careers increases. Therefore, researchers investigate for other alternative choices. One of the most interesting choice is the renewable energies. These sources of energies are attractive due to either they are permanent resources or they are environmentally friendly. The most important renewable energy resource is solar energy that in fact is the source of other renewable energies. The most important and economic method of solar energy absorption is the thermal method. Common technology in thermal method is the Parabolic-Trough. But, recently a new technology have been developed called Compact Linear Fresnel Reflector (CLFR) that...
Theoretical and Experimental Investigation of Nanoparticle Formation Via Microemulsion Method
, Ph.D. Dissertation Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor) ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
In this work, nanoparticle production via microemulsion method has been investigated from theoretical and experimental points of view. Population balance approach has been used to model nanoparticle formation in an inverse microemulsion system. The study of nanoparticle formation in the inverse microemulsion system of Marlipal O13/40-cyclohexane-water reveals that in low reactants concentrations, the coagulation phenomenon has an important effect on the formation of particles. In this regard, the population balance equations has been developed to consider the coagulation phenomenon in the inverse microemulsion system. The kernel of coagulation has been calculated based on attractive and...