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Effect of Soil-Structure Interaction on Practical Design of Ordinary Buildings Based on Iranian Seismic Code
, M.Sc. Thesis Sharif University of Technology ; Ghannad, Mohammad Ali (Supervisor)
Abstract
In the last few decades Seismic Regulations attitude’s has been undergone significant changes from various aspects. One of these aspects is entering new topics based on the latest scientific achievements. Soil-Structure Interaction terms was from such issues which had found their ways into Seismic codes as an optional effective factor. In recent years, Based on this new attitude and Scientific achievements, Soil-Structure Interaction terms entrance into Iranian seismic code (2800 Standard), is also has been studied. Naturally, applying these criteria will impact on the design and performance of structures, because of reducing effect of soil structure interaction on decreasing base shear...
Preparation and Physico-chemical Characterization of Titanium Dioxide Nanotubes with Electrochemical Method for Oxidative Dehydrogenation of Propane (ODHP)
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, mohammad (Supervisor)
Abstract
Samples of the V2O5 catalysts supported on nanostructures of TiO2 and γ-Al2O3 were synthesized via hydrothermal method for the oxidative dehydrogenation of propane (ODHP) to propylene. The TiO2 support was utilized in both commercial microstructures and prepared nanostructures from their corresponding salts. Furthermore,the γ-Al2O3 was also prepared from two novel methods. Moreover, the vanadium catalysts supported on hybrid TiO2 and γ-Al2O3 were prepared. The performances of the prepared catalysts were subsequently examined in a fixed-bed reactor. The main products were propylene, ethylene and COx.The vanadium catalyst over TiO2 and γ-Al2O3 had the best performance under the reactor test...
Optimal Design of Tolerances in the Non-rigid Assemblies under the Thermal Impact
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor)
Abstract
Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental...
Theoretical study of CO adsorption on the illuminated TiO2 (0 0 1) surface
, Article Applied Surface Science ; Volume 256, Issue 12 , 2010 , Pages 3795-3798 ; 01694332 (ISSN) ; Sadighi Bonabi, R ; Sharif University of Technology
2010
Abstract
A quantum modeling of the CO adsorption on illuminated anatase TiO2 (0 0 1) is presented. The calculated adsorption energy and geometries of illuminated case are compared with the ground state case. The calculations were achieved by using DFT formalism and the BH and HLYP. Upon photoexcitation, an electron-hole pair is generated. Comparing of natural population in the ground state and the exited state, shows that an electron is trapped in a Ti4+ ion and a hole is localized in an oxygen ion. The photoelectron helps generation of a CO2 molecule on the TiO2 surface. As shown by optimization of these systems, the CO molecule adsorbed vertically on the TiO2 (0 0 1) surface in the ground state...
Coordinated Scheduling of Power and Natural Gas Systems Considering Demand Uncertainty
, M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid (Supervisor)
Abstract
The everyday increasing electricity consumption of household and industrial sectors across the world, and also the limited generation capacity and fuel supplies has led electricity companies, whether in private or government sectors, to focus deliberately on power generation planning, its costs, risks and constraints Because of many reasons including high efficiency, low cost of capital investment, expeditious permitting, and operation flexibility of gas-fired generating units, electricity companies prefer them to old ones like coal-fired or oil-fired generating units. Thus natural gas has gained a significant share in the portfolio of electricity generation fuel resources, and it is...
Numerical Investigation of the Effect of Influential Geometrical Parameters on the Plugholing Phenomenon in Smoke Extraction
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Correct and timely extraction of smoke is very important in fire incidents. Statistics show that more than seventy percent of fire casualties are caused by breathing toxic gases. One of the destructive factors in the operation of the smoke exhaust system is the plugholing phenomenon. In this phenomenon, due to the improper design of the ventilation system, the exhaust vent extracts air instead of smoke. The plugholing phenomenon causes the accumulation of smoke in the structure, therefore it is essential to know this phenomenon to prevent it. In this research, the plugholing phenomenon in the smoke extraction process has been investigated by the numerical simulation method. To investigate...
Semi Supervised Approaches for Image Depth Estimation
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
One of the important tasks in machine vision is 3D structure reconstruction or depth estimation. In recent decades, methods based on machine learning have been presented, which can be used to perform this costly task more optimally. For this purpose, two branches of supervised and unsupervised learning have been considered. In supervised learning, the available data is in the form of image-depth map pairs, such as the kitti dataset. The image is fed to the network and the output is made in the form of a depth map. The cost function of this network is obtained by comparing the generated depth map and the depth map in the data set calculated by laser. In unsupervised learning, there is no...
Decision Matrix for Time-Critical Optimal Trajectories for Air-Launch of Small Satellites
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
One of the satellite time-critical launch methods is air-launch, which is considered in this research thoroughly. The Large number of important parameters of this method makes the system highly complex. In such complex systems, usual methods of design and development will not be effective. Moreover, based on systemic approaches, interfaces between different elements of a complex system have significant effects on the performance of the whole system. One of the methods for analysis of such systems is “Design Structure Matrix” or DSM. This method is based on system engineering principles and has confirmed capabilities in analysis of highly coupled systems.
In this research, the air launch...
In this research, the air launch...
Ultrasonic-assisted grinding of Ti6Al4V alloy
, Article Procedia CIRP ; Volume 1, Issue 1 , 2012 , Pages 353-358 ; 22128271 (ISSN) ; Movahhedy, M. R ; Akbari, J ; Sharif University of Technology
2012
Abstract
In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to the grinding wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding is an efficient machining process which improves the machinability of hard-to-cut materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V alloy is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are compared between conventional...
Identification of Self-Leadership Strategies of Social Entrepreneurs in Face of Challenges of their Career
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor) ; Tasavori, Misagh (Supervisor)
Abstract
The present study seeks to focus on social entrepreneurs to address how these entrepreneurs continue to have sufficient motivation to overcome the challenges they face in the course of their careers and continue this path. This research has tried to use the concept of self-leadership - which keeps a person motivated to achieve his goals for which he has an inner motivation - to answer this question. So the main research question is how do social entrepreneurs use their leadership in the face of the challenges of their careers? To answer this question, this study used a qualitative research method with an exploratory approach and conducted semi-structured interviews with 14 social...
Study of UV Radiation Effects on Fischer–Tropsch Synthesis
, M.Sc. Thesis Sharif University of Technology ; Sadighi Bonabi, Rasoul (Supervisor)
Abstract
Recently, The interest of using the coherent and incoherent photons in chemical synthesis have been raised considerably. In this project, theoretical calculations due to investigation of irradiation’s effects on Fischer- Tropsch synthesis have done. Fischer – Tropsch synthesis is the process that converts synthesis gas, i.e. a mixture of carbon monoxide and hydrogen, in to a wide range of long chain hydrocarbons and oxygenates. We invest the first chapter of this project to introduce of Fischer- Tropsch synthesis and its importance. Following in the next chapter we have analyzed the photocatalyst in microscopic scale. In third chapter, we have claimed the necessary theories which are useful...
Protection of titanium metal by nanohydroxyapatite coating with zirconia and alumina second phases
, Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 48, Issue 6 , 2012 , Pages 688-691 ; 20702051 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif Universty of Technology
2012
Abstract
In this study hydroxyapatite (HA)/zirconia/alumina composite coatings on titanium metal was carried out using Sol-Gel dip coating and calcination process. Hydroxyapatite-Alumina-Zirconia sol, coated samples in three processes by changing final sol stirring time, aging time, calcination temperature of synthesized powder and prepared coating and rate of coating. Some parts of prepared sol were also synthesized and became powder in all three processes. Scanning electron microscopy was used to estimate the particle size of the surface and for morphological analysis. The functional group and crystallization characteristics of the powders were analyzed using (FTIR) and X-Ray diffraction (XRD)....
Surface modification for titanium implants by hydroxyapatite nanocomposite
, Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
2012
Abstract
Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO...
Influence of monoethanolamine on thermal stability of starch in water based drilling fluid system
, Article Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development ; Volume 45, Issue 1 , 2018 , Pages 157-160 ; 10000747 (ISSN) ; Sharif Nik, M. A ; Heidari, H ; Valizadeh, M ; Sharif University of Technology
Science Press
2018
Abstract
To improve the thermal stability of starch in water-based drilling fluid, monoethanolamine (MEA) was added, and the effect was investigated by laboratory experiment. The experimental results show that the addition of monoethanolamine (MEA) increases the apparent viscosity, plastic viscosity, dynamic shear force, and static shear force of the drilling fluid, and reduces the filtration rate of drilling fluid and thickness of mud cake apparently. By creating hydrogen bonds with starch polymer, the monoethanolamine can prevent hydrolysis of starch at high temperature. Starch, as a natural polymer, is able to improve the rheological properties and reduce filtration of drilling fluid, but it works...
Generalizing of numerically solving methods of eigenvalue problems to asymmetrical, damping included case
, Article Proceedings of the 2001 ASME Design Engineering Technical Conference and Computers and Information in Engineering Conference, Pittsburgh, PA, 9 September 2001 through 12 September 2001 ; Volume 1 , 2001 , Pages 401-404 ; Sharif University of Technology
2001
Abstract
In this paper, "Subspace" method is generalized to asymmetrical case. In the new algorithm described here, "Lanczos" method is used to find the first subspace and to solve the eigenvalue problem resulted in generalized subspace method. To solve the standard eigenvalue problem developed by "Lanczos" method "Jacoby" method is used. If eigenvalue problem includes damping matrix, that will be imported in new defined mass and stiffness matrices
A Multi-Objective Model of Economic and Environmental Simultaneous Programming in the Supply Chain Based on the Goal Programming of Algorithms Based on Aggregator Algorithms
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor) ; Mostafavi, Mostafa (Supervisor)
Abstract
One of the key challenges and issues in proper supply chain planning is that decision-making in one area affects other areas, and one-dimensional optimization of goals leads to inefficiency in other goals. One of the problems in this field is the realization of a multi-objective model of simultaneous economic and environmental planning in the supply chain. Accordingly, this study aimed to present a multi-objective model of simultaneous economic and environmental programming in the supply chain based on the goal programming of aggregator algorithms. This study is practical in terms of purpose and it is descriptive and developmental in terms of research method. In this way, using two models of...
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
In conventional grinding of hard to cut materials such as Ti6Al4V alloys, surface burning, redeposition and adhesion of chips to wheel and workpeice occur visibly unless it is carried out at low speeds and with high volume of cutting fluid. Ultrasonic assisted grinding (UAG) is an efficient machining process for hard-to-cut materials with poor machinability. UAG improves the machinability of such materials by changing the kinematics of the process. In this research, the effect of imposition of ultrasonic vibration on the grinding of Ti6Al4V is studied. Longitudinal vibration at ultrasonic frequency range (20 kHz) is applied on the workpiece and machining forces and surface roughness are...
Influence of monoethanolamine on thermal stability of starch in water based drilling fluid system
, Article Petroleum Exploration and Development ; Volume 45, Issue 1 , February , 2018 , Pages 167-171 ; 18763804 (ISSN) ; Ameri Shahrabi, M. J ; Heidari, H ; Valizadeh, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
To improve the thermal stability of starch in water-based drilling fluid, monoethanolamine (MEA) was added, and the effect was investigated by laboratory experiment. The experimental results show that the addition of monoethanolamine (MEA) increases the apparent viscosity, plastic viscosity, dynamic shear force, and static shear force of the drilling fluid, and reduces the filtration rate of drilling fluid and thickness of mud cake apparently. By creating hydrogen bonds with starch polymer, the monoethanolamine can prevent hydrolysis of starch at high temperature. Starch, as a natural polymer, is able to improve the rheological properties and reduce filtration of drilling fluid, but it works...
Optical Flow Based Flight of a Small Fixed-Wing Aircraft in Ideal Urban Environments
, Ph.D. Dissertation Sharif University of Technology ; Saghafi, Fariborz (Supervisor)
Abstract
This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach...
Reconfiguration and Capcitor Placement in Distribution Systems for Loss Reduction and Reliability Enhancement
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
Capacitor setting and reconfiguration are of main means of loss reduction and voltage profile improvement in distribution system operation. Cooperation between these two strategies can effectively minimize power losses in distribution system automation. Also, from the medium and long term viewpoint, capacitor placement and reconfiguration can be used for loss reduction and reliability enhancement. In this section, the sum of losses cost, capacitor investment cost and reliability cost should be minimized. Regarding the need to solve two non-linear combinatorial optimization problems simultaneously, metaheuristic algorithms are used in this thesis. Specifically, Elitist Genetic Algorithm,...