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ahmadi-mousavi--mohammad
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The Behavior of Supporting Structures with Pretension Anchors by Geotechnical Softwares
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
In recent years, due to urban expansion and population growth, number of floors and excavations depth has increased. Stabilization of excavations is one of the most important issues in geotechnical engineering. Today, one of the most widely used methods that is used in deep excavations is brace soil by steels and pretension them. In this thesis tries to evaluate static behavior of flexible supporting structures with pretension anchors by using PLAXIS2D, FLAC3D and GEOSTUDIO softwares. The objective of this modeling is better understanding the static behavior of walls, comparing the two and three dimensional modeling and the effect of corners of excavation on deformation. The results shows...
Controllability of Networked Systems based on Structural Features of Proximity Graphs
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
Recently, there has been a surge of research activities in the area of networks in the systems and control community. One foundational class of questions on networked systems pertains to their controllability. While there are classical tests to check the controllability of linear time-invariant (LTI) systems, their applications to large-scale networks is numerically infeasible. Indeed, finding a minimum cardinality set of input nodes that ensure the controllability of a network is NP-hard. Moreover, when the interaction strengths along the edges of a network are unknown, the classical controllability test cannot be applied. To overcome these issues, an alternative set of approaches involves...
Non-Scratch, Antibacterial And Self-cleaning SiO2/TiO2 Nano Composite Coating on Surgical Tools By Sol-Gel
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In this study TiO2/SiO2 thin films were prepared by sol-gel method from Tetra isopropylortho Titanate(TIPT) as the principle of TiO2 material with Tera ethoxysilane(TEOS) as the principle of SiO2 material to achieve high scratch-resistant , antibacterial and self-cleaning surface area under the effect of various percentage of SiO2 . Film deposition was carried out using a dip-coating technique and heat-treatment was used at 700ºC to achieve crystalline of films with excellent adherence the of substrate.
The surface morphology of the films has been observed by Scanning Electron Microscope (SEM) and the tribological properties of the surface were investigated by Atomic Force Microscope...
The surface morphology of the films has been observed by Scanning Electron Microscope (SEM) and the tribological properties of the surface were investigated by Atomic Force Microscope...
Design, Prototyping and Testing an Indirect Load Monitoring System for Ball Mills
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Ball mills are a category of industrial mills used for crushing and grinding non-metallic materials into powder. In these mills, as the mill rotates, steel balls move and by falling on materials, the process of crushing and grinding takes place. The mismatch between the rotation speed of the mill and the volume of balls inside it can result in ineffective collisions between the balls or between the balls and the inner protective layers of the mill, causing damage to the balls and liners and leading to repair costs and loss of production. The aim of this project is to design and prototype an intelligent system for monitoring the ball mass inside the mill to increase production efficiency and...
Migrating From 3D Modelling of the Laser Assisted Machining Process into a Valid 2D Model
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Due to recent advances in laser technology and instruments, laser assisted machining processes has gained extra attention by scientists and industries. Naturally, effective modeling of the process is of great interest for researchers. Machining processes are generally modeled via FE tools and based on the requirements of model, it can be performed either mechanically or thermos-mechanically. About the LAM problems, it is basically meaningless to have a model without considering thermal effects. Hence, modeling is performed in two steps where through the first one, a thermal problem is solved to bring the temperature distribution of the work piece as the initial conditions of the next step....
Effect of reactive diluent on gas separation behavior of photocurable acrylated polyurethane composite membranes
, Article Journal of Applied Polymer Science ; Volume 137, Issue 3 , 15 January , 2020 ; Shojaei, A ; Mousavi, S. A ; Ahmadi, S. A ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
In this study, the effects of the type and content of reactive diluents on the permeation/separation of carbon dioxide/nitrogen (CO2/N2) through acrylate-terminated polyurethane (APU)-acrylate/acrylic diluent (APUA) composite membranes was investigated. A series of APUs based on poly(ethylene glycol) (PEG)-1000 g mol−1, toluene diisocyanate, and 2-hydroxyethyl methacrylate was synthesized and then diluted with several reactive diluents. The results obtained from differential scanning calorimetry (DSC) and Fourier transform infrared analyses showed that the microphase interference of hard and soft segments increased with increasing reactive diluent content. Furthermore, with increasing alkene...
Evaluating the Effect of CPAP Pressure in Patient with Obstructive Sleep Apnea Using Heart Rate Variability
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Gholamreza (Supervisor) ; Arjmand, Navid (Supervisor)
Abstract
Continuous positive airway pressure (CPAP) is a standard treatment for patients with obstructive sleep apnea (OSA), a sleep-related breathing disorder characterized by full or partial occlusion of the upper airway during sleep. CPAP pressure adjust by a sleep technologist during attended laboratory polysomnography (PSG) to eliminate obstructive respiratory-related events (apneas, hypopneas). Because of changes in environment and lifestyle patients needed new adjustments for the device that brings discomfort and extra money for treatment. In recent, lots of methods have been proposed to replace PSG and minimized the number of biological signals to detect apnea, best results came from deep...
Electrodeposition and Characterization of Zn-Ni-P/Zn-Ni Multilayer from Citrate Bath
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
The aim of this study was electrodeposition of Zn-Ni-P/Zn-Ni multilayer coatings by single-bath method from a citrate bath to produce a sacrificial coating with high barrier properties compared to Zn-Ni monolayer coating. The coatings that were prepared at 10 mA/cm2 was Zn-Ni-P (Ni-rich and percentage of zinc, nickel and phosphorus, respectively: 40, 50 and 10 %), and the alloy deposited in 60 mA/cm2 were practically Zn-Ni (Zn-rich, 85% zinc) and almost phosphorus free. Galvanostatic pulse deposition method through switching of the current density between the two values mentioned in monolayers (10 and 60 mA/cm2) in different time periods to create bilayers corresponding to the monolayers,...
Optimal Selection of Local Models in Multi-Model Method
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
Many processes and real world systems indicate nonlinear behavior and operate either naturally in multiple regions or in a wide range of operation space. Modelling and control of these systems by nonlinear methods needs to have a deep insight. Furthermore, the nonlinear methods leads to complexity issues. To overcome these problems, multi-model methods are introduced which consist of two steps, decomposition and combination. In decomposition step, the complex system is divided into a set of simple models; in the combination step, the behavior of local models are combined. How to decompose to local models and how to combine them are two main questions in this area which not answered...
Designing and Constructing a Heavy Water Electrolysis System for Deuterium Gas Production & Encapsulation at Mini Pilot Scale
, M.Sc. Thesis Sharif University of Technology ; Oteuokesh, Mohammad (Supervisor)
Abstract
By studying and evaluating methods for producing deuterium gas from heavy water, the electrolysis method with polymer membranes (PEM) was defined as the proposed method.The (PEMWEs) is a new method in electrolysis, which utilizes solid polymer electrolyte (SPE) membranes as electrolytes to play a significant role in reducing the resistivity in the electrolysis and also in comparison with alkaline electrolysis in terms of energy consumption and optimal being in condition is also a better condition for the purity of the produced gas.In this regard, a polymer electrolyte membrane water electrolysers (PEMWEs) was designed and developed on a laboratory scale. After analysis of the sample gas, and...
Production of Magnesium Nanoparticles by Electromagnetinc Levitation Melting
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
Electromagnetic levitation(EML) provides a process producing nanoparticles using gas condensation method. In gas condensation processes, vapor is produced by heating the sample then inert gas is applied to provide the inert atmosphere and also cool and condense the sample vapor into a nano powder to obtain a sample nanoparticle. In the EML method, rapidly alternating electromagnetic field induces eddy current in the conducting sample which will heat the sample. The current in the sample result in an induced magnetic field. Consequently, the sample droplet is heated and levitated simultaneously by an induction furnace as a generator. The sample temperature is dependent on parameters such as...
Numerical Modeling of Hydrothermal Behavior of Geothermal Tunnels in Sandy Soils
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
Shallow geothermal energy is a renewable and sustainable form of energy that has the potential to help alleviate the growing climate and energy crisis. The most common system used to extract shallow geothermal energy is the ground source heat pump (GSHP) system. The concept of using underground structures in exploiting shallow geothermal energy for space heating and cooling has received increasing attention. This study focuses on the use of geothermal tunnels as a means of extracting shallow geothermal energy.This research examines the effects of different heat transfer mechanisms, and highlights the effects of this phenomenon by focusing on the effects of natural convection around the...
Correlation of In-Situ Horizontal Stress and Cone Tip Resistance in Sandy Soils Using Calibration Chamber Test Measurements
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
This study aims to propose a new correlation between in-situ horizontal stress and cone tip resistance in soils. Knowing the field in-situ stress state condition has an important role in stability assessment and stress-deformation analysis in a common geotechnical system. Although vertical stress could be measured easily, horizontal stress is still known as challenging work. Due to the difficulty in sampling undisturbed sand specimens, in-situ tests have been proposed in the previous literature to investigate the different characteristics of this soil. Cone Penetration Test (CPT) is one of the most used and accepted soil methods for soil investigation, identifying different soil parameters...
Numerical Analysis of Mechanized Tunneling Effects in Different Conditions on Internal Forces and Settlement of Superstructures
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mahdi (Supervisor)
Abstract
In this research with Finite Element Methods in ABAQUS, numerical modeling has done in three-dimensions, which can be used to determine the effect of different factors on the surface settlement. Also, various factors such as geotechnical conditions, tunnel diameter,tunnel depth, the impact of the thickness of the segments and the amount of eccentricity of the structure relative to the longitudinal axis of the tunnel considered in this study. Face Pressure Supports, and Grout Injection Pressures are taken into account, too.Tunnel drilling causes a change in the displacement area and creates a changing zone around the tunnel. In this regard, not only adjacent buildings will be affected by...
Numerical Modeling of Effective Parameters on the Performance and Efficiency of Energy Piles
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
In recent years, with the growth of industrial societies, the amount of energy consumption in the world has been increasing. On the other hand, the most consumed energy sources in the world are non-renewable energy sources. For this reason, governments and industries have invested to facilitate and make renewable energy sources cheaper. One of these renewable energies is geothermal energy, which is one of the most economical ways to use this energy, using heat exchange systems in piles and foundations. Using a heat exchange fluid, energy piles transfer the heat of the earth's surface to the ground with a lower temperature in the hot seasons of the year and use the thermal energy of the...
Fabrication of Superhydrophobic Coating to Reduce Drag force with Anti-Corrosion and Anti-biofouling Properties
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor)
Abstract
Growth of the fuel consumption in the world and the greenhouse effect of its pollution get industrial managers and environmental activities attention. Skin drag force has a significant role in energy uses. The drag reduction property of superhydrophobic surfaces shows a new approach for investigators to reduce energy uses. Surface with 150° contact angle called superhydrophobic surface.In this project, a superhydrophobic coating is developed based on acrylic hydroxyl resin by silica nanoparticles. This coating can be sprayed on any surface. Using the Iron oxid particles and silica nanoparticles together produces hierarchical micro-nano structures. This coating has a 160.1° contact angle on...
Experimental Study of the Effect of Liquid Fluid Injection Conditions Inside the Evaporation Tube on its Performance
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
This reaserch is study on the performance of evaporation tubes used in mini jet engines which has been done experimentally using laboratory equipment. In this study, researchers have tried to simulate the laboratory conditions as much as possible to the real conditions inside the mini-jet engine, increase the accuracy of the results and increase the results and bring them closer to the results inside the mini-jet engine. The experiments are divided into two categories, cold and hot In cold tests, an attempt is made to study and investigate the types of two-phase flow regimes created by applying different fluid and air flow rates, and to select annular flow regimes from among them....
Optimal Operation of a Price-Maker Virtual Power Plant in Frequency Constrained Electricity Market
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
In this thesis, optimal offering strategy problem of a virtual power plant (VPP) as a price-maker player in day-ahead frequency constrained electricity market is presented. The optimal offering strategy problem is modeled as a bi-level optimization problem. In the upper level, the total profit of VPP is maximized. In the lower level, the clearing conditions of frequency constrained electricity market is modeled. The proposed bi-level optimization problem is reformulated as a mathematical programming with equilibrium constraints (MPEC) problem by using Karush-Kuhn-Tucker (KKT) conditions. Then, the proposed MPEC problem, which is nonlinear and hard to solve by commercial solvers, is...
Flood Risk-Based Design for Roads and Pipelines Crossing from Wetlands; Case Study: Horulazim Wetland
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
One of the natural functions of wetlands is to neutralize the dangers caused by floods. Therefore, if a facility is built in the area of wetlands, it should not disturb their natural functioning. During the Iran-Iraq war, several antenna roads were built across the wetland, and the construction of these roads divided the wetland into 5 separate reservoirs. After the end of the war and with the development of the oil fields west of Karun (Hor al-Azim region), the extraction of oil from this region was put on the agenda. With the flood of April 2018, these facilities and roads were exposed to damage and flooding, and oil production from these reservoirs was stopped. In this research, after...
Simulation and Analysis of of NEM Relays for Low Power VLSI Applications
, M.Sc. Thesis Sharif University of Technology ; Sarvari, Reza (Supervisor)
Abstract
Over the past five decades, the proliferation of electronic devices and the advent of Internet of Things (IoT) technology have ushered in a profound revolution in integrated circuit technology. In contemporary electronics, digital integrated circuits rely predominantly on CMOS transistors. Among the notable limitations associated with CMOS transistors are their non-zero off-state current and limited sub-threshold slope. In response to these limitations, researchers have ventured into a burgeoning field known as "Beyond CMOS," exploring technologies like Tunnel Junctions, Carbon Nanotube FETs, and more. Additionally, alternative approaches that blend electronic and mechanical principles in...