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Simulation of Flow Drag Reduction through Air Injection from the Porous Wall
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor) ; Sadrhosseini, Hani (Supervisor)
Abstract
The effect of using backpressure of air injection in a microchannel on internal flow pressure drop were investigated in this study. Multiphase flows are commonly encountered in gas and oil industries. Flow fields in production operations are often complex and include multiphase flows of gas and liquid. Previously, because of their complex nature, these flow patterns have been mostly investigated only experimentally and empirical correlations based on the experimental data. From another point of view, it is almost impossible to experimentally realize all the flow conditions for each of the flow patterns. Nowadays computer facilities provide the tool to construct and use large-scale...
Simulation of Droplet Sorting in Microfluidic Systems
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor) ; Asghari, Mohsen (Supervisor)
Abstract
A new microfluidic device is introduced for sorting the particles based on the hydrodynamic resistance induced in a microchannel which is not needed for additional detection or sorting modules. Hydrodynamic resistance affects physical properties, such as size and deformability of the particle. This device could apply application in cell sorting for remedies, diagnostics, and industrial applications. The device design is performed using an equivalent resistance model, and also numerical simulations are performed. For validation of the results, they are compared with experimental results. Moreover, we will discuss threshold particle size and will introduce a way to approximate it to ...
Design an Artificial Neural Structure by Using Mirror Neurons for Implementing the Ink Drop Spread (I.D.S) Operator in Active Learning Method Algorithm
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
In this research, a study on Mirror Neuron and Active learning method was done based on the human capability of using their past knowledge in order to understand new systems faster and with more accuracy. Mirror ALM, A new modeling technique based on ALM was proposed that is capable of merging the IDS planes of an old system in order to improve the output of the modeling for a new system. This new technique was tested on a 3D function, state estimation of an inverted pendulum and finally in control procedure of an inverted pendulum. The results of the tests were compared with the classic ALM method to recognize the advantages and disadvantages of the introduced method. The results showed...
Realization Law of Pragnanz and Closure of Gestalt Theory Using Neural Network Modeling and Active Learning Method
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor) ; Mirian Hossinabadi, Maryam (Supervisor)
Abstract
Human brain is one the most efficient biological neural network that is capable of performing most complicated tasks in very short time. Visual system as a part of the brain can process the visual records from the environment and perform very useful processes on them. The information provided from visual system processes play important roles in human intelligence. In this thesis we introduce and investigate one of the well-known theories about visual system called gestalt theories. These theories tried to define how a biological neural network can perform such results. Gestalt theorists developed rules of perception to explain their ideas including Law of Pragnanz, Similarity, Closure,...
Comparision of Single Service Call Admission Control Schemes in Cellular Mobile Networks
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
In single service wireless cellular networks, two types of call are defined; new call and handoff call. New call blocking probability and handoff call dropping probability are two major parameters of QoS. Some call admission control schemes are proposed for handling new and handoff calls in the cell for keeping these QoS parameters under suitable values. In this work, we will introduce some call admission control schemes and will show performance analysis, advantages and disadvantages of them (under different channel holding times and same channel holding times for new calls and handoff calls). Then we will focus on two schemes and based on their ideas, we will propose a new call admission...
Synthesis and Characterization of 2D-WS2 Nanostructures for Gas Sensing Applications
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Nowadays, beside of two-dimensional tungsten disulfide nanosheets, its hybrid nanostructures also provide active sites for physisorption of gas molecules due to their high surface-to-volume ratio, surface active site (such as sulfur vacancies, surface defects, and p-n junctions) and active edges, and are very attractive for gas sensing applications. In this research, tungsten disulfide layered crystallines were grown by chemical vapor phase transport and its two-dimensional nanoflakes were prepared by liquid exfoliation method. So, a thin film of the nanoflakes was deposited on a silicon oxide substrate by drop casting method, and its gas sensing properties were investigated for water and...
Development of an Optimization Model Based on Superstructure for the Integration of Water and Energy Networks in Process Industries
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
Lack of resources, environmental limitations, the incresed price of the water used by industrial processes, and the growth of the industry have caused the necessity of minimizing the heat and water consumption in industries become more vital. Therefore, in addition to the methods of energy integration for reducing the energy consumption, some other methods are being utilized to minimize the required fresh water or the production of the waste water in the industries. Studies show that regarding the direct impact that these two objects have on each other, a separate minimization of them cannot lead to the total optimization of the system. Thus, their minimization should be achieved while...
Investigation of Equilibrium and Kinetics of Uranium Solvent Extaction by Cyanex 301 Using a Single Drop Column
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Torab-Mostaedi, Meisam (Supervisor)
Abstract
Uranium separation from other metals in ore and nuclear waste is one of the most important stagesin nuclear fuel cycling. Solvent extraction is the common method for uranium extraction that reagent plays important rule in this technique. In this investigation, uranium solvent extraction is carried out by Cyanex 301 as reagent from nitric acid. At beginning, equilibrium batch extraction was carried and the effect of parameters such as pH, reagent concentration, temperature, shaking time of two phases, volumetric ratio of two phases, diluent and nitric acid concentration on extraction was investigated and optimum value of parameters was calculated. Uranium concentration effect was also...
Evaluation of Energy Recovery by Development of Natural Gas Transmission Network Model
, M.Sc. Thesis Sharif University of Technology ; Saboohi, Yadollah (Supervisor)
Abstract
The development of natural gas supply systems and its transmission networks are vitally important to achieve a natural gas economy. Development and planning of natural gas transmission networks as multidisciplinary projects have crucial impact on the economy of gas-rich countries like Iran. The nvestment costs and operation expenses of pipeline networks are so large that even small improvements in system utilization and planning can involve substantial amounts of money. A large number of technological options exist for development in conversion, distribution levels and …, which cause various pathways for supplying natural gas. In addition there are many energy recovery technologies along...
Numerical Simulation of the Impact of a Drop with a Flat Surface in a Cross Flow, Using LBM
, M.Sc. Thesis Sharif University of Technology ; Taebi Rahni, Mohammad (Supervisor)
Abstract
In this research, numerical simulation of the impact of a drop on a flat surface with oblique velocity has been performed, using two-phase model of Lattice Boltzmann Method (conservative phase-field). During impact, it is important to investigate two-dimensional drop dynamics and to evaluate the effectiveness of the numerical method used. The model used here restores conservative phase field and preserves mass both locally and globally. In addition, to calculate the slope of the phase field, it calls the center points without engaging finite difference calculations. This makes it efficient for running parallel computations. A fixed dry and hard surface is considered and the drop impacts it...
Developing Advanced Models to Simply Simulate the HRSG of Class F Turbine in Full Scale
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Todays, heat recovery steam generator (HRSG) systems are used extensively in combined power plant cycles (consisting of Rankine cycles and Brighton gas cycle) to maximize their efficiencies. The role of HRSG is essential in providing additional energy needed in the steam cycle part. The HRSG has many pipes or harps. They recover the heat from the incoming gas from the gas turbine outlet, which may be boosted up by the duct burner unit. The main challenge in simulating heat recovery units such as tube bundles is to provide ultra-large and cost-efficient grids. In such situations, alternative models are used to simplify the simulation of the steam generator in full scale, including the...
Computational Two-dimensional Study of Oscillating Electrical Field on Break-up of a Drop, Using Hybrid Lattice Boltzmann-Finite Volume Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Salimi, Mohammad Reza (Supervisor)
Abstract
Drop formation is an interesting field of research due to its wide-range of applications, such as drug delivery, biomedical studies, pharmaceutical industry, Lab-On-Chip (LOC) devices, etc. In recent years, researchers have used numerical studies to better understand how the process of forming and carefully examining the factors that affect quality improvement. One of the most effective methods in controlling the size and the process of drop formation is use of external force in microfluidic devices. Among the external force in this study, an electric field with oscillating current was used. Rapid methods for creating, deforming, and breaking up of drops in microfluidic applications are...
LBM Computational Simulation of Oscillations Caused by Formation and Detachment of Drops
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Ebrahimi, Abbas (Supervisor)
Abstract
Formation and detachment of drops are of fundamental importance in studying two-phase flows, such as ink jet printing, emulsion, and spray. Drops are formed under the effects of surface tension forces. After formation, forces like gravity detach the drop from the rest of the fluid. The flow rate is varied from dripping to jetting regime. In this project, formation and detachment of drops were simulated, using LBM with phase field model, which can simulate flows with high-density ratios and is a robust method for applying wetting condition on the walls. Results were validated using single-phase and two-phase flows. After code validation, the oscillations caused by formation and detachment of...
Design snd Analysis Compact Heat Exchangers and Choose and Design Heat Exchanger for Gas Turbines
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)Prediction of Droplet size and Velocity Distribution by using Maximum Entropy Method
, M.Sc. Thesis Sharif University of Technology ; Kebriaee, Azadeh (Supervisor)Computational Simulation of High Density Ratio Drop Deformation and Breakup, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Karbaschi, Mohsen (Supervisor)
Abstract
Deformation and breakup of drops are the basisof many interfacial flow studies and appear in a number of industrial applications, e.g., spray painting, spray combustion, emulsion, foam, sedimentation, and rain. Following their formation, drops may enter a region where hydrodynamicforces are large enough to cause their significant deformation and breakup. When a drop breaks apart into a multitude of small fragments due to disruptive hydrodynamicforces, the process is termed secondary atomization or breakup. Due to many engineering and scientific applications of multiphase and multi-component flows, they have been the main topic of many researchers for many years. Particularly, interfacial...
Simulation of Droplet Formation and Detachment, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor)
Abstract
The phenomena of formation and detachment of droplets are of fundamental importance in studying two-phase flows, such as spraying processes, ink jet printing, emulosin, etc. Droplets are formed under the effects of surface tension forces. After formation, forces like gravity detach the droplet from the rest of the fluid. Recent advancements in computational fluid dynamics and computers have made it feasible to have advancement in simulation of complex flows, including two-phase phenomenon. On the other hand, the lattice Boltzmann method (LBM) has been developed into an alternative and promising numerical scheme for simulating multi-component fluid flows.
In this project, formation and...
In this project, formation and...
Performance Ehancement of Congestion Control Algorithm Through Traffic Flow Istinction
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Congestion is an important issue in the network environment. To keep stable the perfor-mance of the network, congestion control algorithms have been extensively studied. Queue management method employed by the routers is one of the important issues in the congestion control study. Active Queue Management (AQM) has been proposed for early detection of congestion inside the network. AQM mechanisms control the queue length in a router by dropping arriving packets. The Random Early Detection (RED) is the most popular AQM mechanism used in routers on the Intenet to allow network users to simultaneously achieve high throughput and low average delay. The RED algorithm may cause heavy oscillation of...
New S-norm and T-norm Operators for ALM
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
Active Learning Method (ALM) is a soft computing methodology which has been used for modeling and control. Unlike the good results of ALM’s ability, there is not any analytic expression to prove its power, because ALM’s main operators don’t satisfy fuzzy S-norm & T-norm properties. This problem considered from three viewpoints: Mathematics, Geometry and fuzzy sets. In this paper, we try to introduce two new operators based on morphology to satisfy three conditions: at first, they must be fuzzy S-norm and T-norm to confirm the committal of fuzzy set theory. Secondly, they must satisfy Demorgans law, because they are complement of each other. And finally, they resemble the main operators of...
Hydraulic Evaluation and Pressure Estimation in Two-Phase Air-Water Slug Flow Using Soft Computing
, M.Sc. Thesis Sharif University of Technology ; Borghei, Shamsai (Supervisor) ; Shamsaee, Abolfazl (Co-Advisor)
Abstract
Study of hydraulic characteristics of two-phase flow is one of the important issues in hydraulic engineering. Two-phase flows usually accur in hydraulic structures such as pressurized flow tunnels, culverts, sewer pipes, junctions, and similar conduits. Under certain conditions, air may also be introduced into pressurized intake systems, which may form large bubbles in portions of the pipe. The bubbles may, in turn, cause an unstable slug flow, or other flow patterns. Slug flow is one of the most probable patterns in these flows. Prediction of pressure in this situation is a complex subject which despite its great importance is rarely discussed. In this study, the results of a laboratory...