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ebrahimi--mohsen
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Introducing a Set of Material Strain Measures in Non-Linear Kinematics of Micropolar Continuum Mechanics and Determining their Time Rates
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
The concept of generalized strains is a well-established subject in the classical continuum mechanics. The characteristics and various applications of the generalized strains have been the point of interest of many researchers in the classical continuum mechanics. The aim of this thesis is the introduction of generalized strains in the micropolar theory, as a non-classical continuum theory. A set of generalized strains is suggested for the deformation of macro-elements. Moreover, a set of generalized strains is proposed for the micro-structures. Since the rate of strains possesses a significant importance in the constitutive equations of nonlinear analysis of solids, expressions for the rate...
Single Channel Control of a Rotating Flying Vehicle Using an Inertial Navigation System
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor) ; Fathi, Mohsen (Supervisor)
Abstract
In this thesis, single channel control of a rotating flying vehicle by using an INS is designed based on a nonlinear model simulation. Despite the widespread use of single channel guidance and control systems in some homing missiles, they have not been utilized in rotating rockets due to absence of stabilized seeker in this kind of rockets. The idea proposed in this thesis is to make it possible to use single channel control system by means of a stable platform in the flying vehicle which is completely isolated from body rolling motion. The INS is located on the stable platform and an appropriate guidance algorithm is presented in the stable platform coordinate system.
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Modelling and Prediction of Water Quality of Dam Reservoir Using CE-QUAL-W2 Model and Machine Learning Methods (Case Study: Shahr Bijar Dam)
,
M.Sc. Thesis
Sharif University of Technology
;
Shamsai, Abolfazl
(Supervisor)
;
Ghaemian, Mohsen
(Supervisor)
Abstract
Dams are constructed for various purposes, including flood control, drinking water supply, agriculture irrigation, electricity generation, etc. The dam converts the river's natural and dynamic flow into a stagnant artificial lake where humans control the outflow of water, reducing the velocity of water movement and increasing residence time, followed by the entry and accumulation of nutrients in the reservoir, resulting in phenomena such as thermal stratification and eutrophication. Due to the changing climatic conditions of Iran and sudden droughts and wet periods, the need to monitor the water level of dam reservoirs and their water quality to keep them in the best operational condition...
Developing a Decision Support System for Generation Expansion Policy Making in Iranian Deregulated Electricity Market
, M.Sc. Thesis Sharif University of Technology ; Kermanshah, Ali (Supervisor) ; Bahramgiri, Mohsen (Supervisor)
Abstract
Iranian Power industry has undergone fundamental changes since deregulation started in 2003. Currently, bulk trade of electricity in the industry is mainly conducted through a day ahead wholesale market, representing over 98 percent of the exchange of electricity within the grid. Although the current market regime is under operation for over 4 years, several political, cultural and operational obstacles have hindered effective evolution of the restructuring process. Low political support from privatization of the industry assets backed by lack of confidence and trust in market economies in general, and low economic incentive of the market players has slowed down formation of an effective...
A study of Chemical Shielding Constants of Biomolecules by Theoretical And Experimental NMR
, Ph.D. Dissertation Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor) ; Parsafar, Gholam Abbas (Co-Advisor)
Abstract
Prediction and calculation of shielding tensors of H, C, F and P nuclei of different molecules has been the subject of much research, because these nuclei have the greatest importance in NMR experiments. The optimum wave functions and calculation method were obtained using empirical models and factorial design. Based on preliminary experiences, the following four factors at two levels were selected: electron correlation, triple-ξ valence shell, diffuse function and polarization function. The wave functions for calculating gas phase 1H and 13C chemical shifts of various types of alcohols, amines and simple hydrocarbons were optimized using empirical model. The B3LYP/6-311+G wave function is...
Investigation of The Effect Of Microgravity On Bone Marrow Stromal Cell Growth And Infiltration On An Optimized 3d Structured Scaffold
,
M.Sc. Thesis
Sharif University of Technology
;
Yaghmaei, Soheila
(Supervisor)
;
Vossoughi, Manouchehr
(Supervisor)
;
Haji Ebrahimi, Zahra
(Supervisor)
;
Janmaleki, Mohsen
(Co-Supervisor)
Abstract
To develop a novel cell culture method for enhancement of bone marrow stromal cell growth and infiltration into the 3d electrospun PCL-based scaffold, we utilized the RPM system to simulate microgravity. In current study, six different scaffolds are produced using the electrospinningelectrospraying technique. These scaffolds are compared based on their structural (average diameter and SEM micrographs), mechanical (Tensile strength, elongation and wettability) and biological (Biodegradability, bioactivity, biocompatibility, cell adhesion, cell infiltration and antibacterial quality) characteristics. It is noted that the porous nano-hydroxyapatite/titanium hydroxide/polycaprolactone...
A ZVS-resonant bifilar drive circuit for SRM with a reduction in stress voltage of switches
, Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference, Istanbul ; 2013 , Pages 125-128 ; 9781467350037 (ISBN) ; Najmi, V ; Ebrahimi, S ; Oraee, H ; Sharif University of Technology
2013
Abstract
Switched Reluctance Motors (SRMs) are widely used in high-speed and low voltage applications because of their attractive features such as robustness and simplicity. No winding on the rotor of this type of motors allows reaching high speed which is desired for many applications. Drive circuits of SRMs also play an important role in their performance and operation. In this paper, a new bifilar drive circuit for this type of motors has been proposed. This novel configuration has been tested and investigated by PSIM software. Results show that the new bifilar drive circuit highly reduces the voltage stresses on semiconductor switches, and also considerably reduces the switching losses which are...
Energy management of smart home considering residences' satisfaction and PHEV
, Article 2018 International Conference on Smart Energy Systems and Technologies, SEST 2018, 10 September 2018 through 12 September 2018 ; 2018 ; 9781538653265 (ISBN) ; Shokri Gazafroudi, A ; Corchado, J. M ; Ebrahimi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Regarding the increasing number of electrical devices in the smart homes that leads to increase in total electricity consumption and cost, it is essential to use energy management methods to reduce the electricity cost. However, this can cause resident's dissatisfaction. Hence, it is important to define a method in which cost and dissatisfaction be optimized simultaneously. Among different services, an electric vehicle is the one that can be used as an energy storage system, so it can reduce the daily cost despite of increasing the total energy consumption. In this paper, we study the effect of the EV on the cost and dissatisfaction in our proposed method. © 2018 IEEE
Measured impact of different back-off points and cooling methods on pulse-to-pulse stability and sidelobe level of a high-power solid-state amplifier
, Article IET Radar, Sonar and Navigation ; Volume 14, Issue 2 , 2020 , Pages 335-340 ; Khodarahmi, E ; Ebrahimi, E ; Ahmadi, B ; Jalali, M ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Using solid-state power amplifiers for next generation of weather radars becomes feasible by pulse compression techniques. In this study a 1.5 kW solid-state power amplifier (transmitter) for C-band weather radars is designed and fabricated by GaN high electron mobility transistor (HEMT) technology. An experimental setup based on heterodyne receiver with 16-bit digitiser is developed to investigate the behavior of the power amplifier under different cooling methods and back-off points. Several measurements with shaped LFM pulse show an approximately identical pulse to pulse (P2P) stability for 3 dB compression, P1dB and 2 dB back-off points while the best sidelobe level (SLL) is achieved for...
Probabilistic safety assessment of a UF 6 production process
, Article Advances in Safety, Reliability and Risk Management - Proceedings of the European Safety and Reliability Conference, ESREL 2011 ; 2012 , Pages 1384-1389 ; 9780415683791 (ISBN) ; Sharif University of Technology
2012
Abstract
Application of Probabilistic Safety Assessment (PSA) to a Uranium hexafluoride (UF 6) production process is presented in this paper. The process is constituted from three main units: UF 4 conversion to UF 6, condensation of produced UF 6 gas and tail gas treatment. Radioactive gas is present in all parts of the process and occurrence of high pressure or high temperature in the process equipments may lead to radioactive release to workplace and environment. The work is mainly based on PSA experience in nuclear power plants. Accordingly for the process, eight group of Initiating Events (IE) that lead to UF 6 gas release have been identified using HAZOP study. For each IE, based on related...
On the temperature control in self-controlling hyperthermia therapy
, Article Journal of Magnetism and Magnetic Materials ; Volume 416 , 2016 , Pages 134-140 ; 03048853 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature...
Atmospheric icing effects of S816 airfoil on a 600 kW wind turbine's performance
, Article Scientia Iranica ; Volume 25, Issue 5B , 2018 , Pages 2693-2705 ; 10263098 (ISSN) ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
This study investigates the aerodynamic loads and energy losses of a typical 600 kW wind turbine with S816 airfoil blade under two different icing conditions. Three sections at different radial positions were considered to estimate the icing effect along the blade. Ice accretion simulations in wet and dry regimes were carried out using the NASA LEWICE 3.2 computer program. The airflow simulations were performed with CFD method and SST k -ω turbulence model. The results of these simulations, including streamlines, surface pressure, skin friction, lift, and drag coefficients, were inspected for both clean and iced airfoils. In the case of wet iced airfoil, a separation bubble was created in...
Investigation on the Effects of the Polyacrylamide Copolymers and Their Blends with Sulfonated Lignin on the Soil Stabilization
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Ebrahimi, Hossein (Co-Supervisor)
Abstract
In recent years, dust pollution has become a worldwide issue due to the creation of serious environmental problems and the effects it has on human health. In this research, an environmentally friendly soil stabilizer has been synthesized, and its performance has been investigated. Acrylamide monomers were grafted onto sodium lignosulfonate chains, utilizing solution polymerization. The soil of the Ahvaz deserts was used in the analyses. Using EDX and DLS analyses, the components of this soil and the particle size distribution of the used soil were obtained. Characterization of the functional groups and the structure of the graft copolymer were done by FTIR and H-NMR analysis, respectively,...
Sole versus dual-sourcing under order dependent lead-times and prices [electronic resource]
, Article Computers And Operations Research, Published in: Elsevier Journals ; Volume 36, Issue 12, December 2009, Pages 3272–3280 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this paper, we consider a dual-sourcing model with constant demand and stochastic lead times. Two suppliers may be different in terms of purchasing prices and lead-time parameters. The ordering takes place when the inventory level depletes to a reorder level, and the order is split among two suppliers. Unlike previous works in the order splitting literature, the supply lead time between vendor and buyer as well as unit purchasing prices is considered to be order quantity dependent. The proposed model finds out the optimal reorder point, order quantity and splitting proportion, using a solution procedure. Numerical results show that neglecting the relationship between ordering batch size...
Human serum protein adsorption onto synthesis nano-hydroxyapatite
, Article Protein Journal ; Volume 31, Issue 2 , February , 2012 , Pages 150-157 ; 15723887 (ISSN) ; Massah Bidgoli, M ; Behrashi, M ; Mohsen Nia, A ; Sharif University of Technology
2012
Abstract
Adsorption of human serum proteins (Albumin and total protein) onto high purity synthesis nano-hydroxyapatite (HA), Ca 10(PO 4) 6(OH) 2, has been studied in a wide temperature range by UV-visible spectrophotometer. Adsorption isotherm is basically important to describe how solutes interact with adsorbent, andiscriticalinoptimizing the use of adsorbent. Inthe present study, the experimental results werefitted tothe Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (DR) models to obtain the characteristic parameters of each model and square of the correlation coefficients (R 2). According to the results, the DR isotherm model had the best agreement with the experimental data. The effect of...
Dunford-Taylor integral and the isotropic tensor valued functions having the commutative property with their tensor argument
, Article Advanced Materials Research, 16 September 2011 through 18 September 2011 ; Volume 433-440 , September , 2012 , Pages 3308-3314 ; 10226680 (ISSN) ; 9783037853191 (ISBN) ; Asghari, M ; Sharif University of Technology
2012
Abstract
Isotropic tensor valued functions of tensor arguments play an important role in the formulation of the equations governing the behavior of solid materials in the field of continuum mechanics. When the tensor argument is non-symmetric, the complexity and the difficulty in dealing with the tensor functions are high. In this work, the issue of expressing an isotropic tensor valued tensor function of a non-symmetric tensor argument is attention by utilizing the Dunford-Taylor integral. An important subclass of the isotropic tensor functions is considered with the commutative property
Formaldehyde biodegradation using an immobilized bed aerobic bioreactor with pumice stone as a support
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1372-1376 ; 10263098 (ISSN) ; Borghei, M ; Sharif University of Technology
2011
Abstract
The objective of this study is the investigation of formaldehyde degradation in a bioreactor with pumice stone as a support. The reactor was tested at different synthetic wastewater concentrations with total COD of 500, 1000 and 1500 mgL, respectively, at 24 h hydraulic retention time. The effect of feed composition was tested by changing the COD TCOD FA ratio in order to analyze the impact of formaldehyde concentration. The average formaldehyde and COD removal efficiencies obtained in the reactor were 97.1% and 88%, respectively. The maximum COD and formaldehyde removal efficiencies occurred at the COD TCOD F of 41 at COD T=1000mgL. The effect of toxic shock on reactor performance was...
Port-Hamiltonian control of a brachiating robot via generalized canonical transformations
, Article 2016 American Control Conference, ACC 2016, 6 July 2016 through 8 July 2016 ; Volume 2016-July , 2016 , Pages 3026-3031 ; 07431619 (ISSN); 9781467386821 (ISBN) ; Namvar, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
This paper is devoted to the design of a port Hamiltonian controller for different scenarios of brachiation movement by a two-link bio-inspired robot called brachiating robot. A unified technique for trajectory tracking control problem of nonholonomic (drift-less) port Hamiltonian systems was introduced in the past, which exploits a generalized canonical transformation to form an error system in order to convert the trajectory tracking problem into a stabilization one. Although the method is novel and promising, only fully actuated systems are considered and success of the approach relies on the possibility of solving a set of partial differential equations (PDEs). Considering the fact that...
Numerical investigation of the forward and backward travelling waves through an undulating propulsor: performance and wake pattern
, Article Ships and Offshore Structures ; Volume 11, Issue 5 , 2016 , Pages 517-539 ; 17445302 (ISSN) ; Abbaspour, M ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Recently, the mechanisms of natural undulatory locomotion of aquatic animal swimming have become one of the most significant issues for the researchers, swimmers and engineers. This study aims to elucidate and compare the propulsive vortical signature and performance of backward (negative undulation) and forward (positive undulation) travelling waves through a typical fishlike propulsor by a systematic numerical study. The numerical approach uses a pressure-based finite volume method solver to solve Navier–Stokes equations in an arbitrary Lagrangian–Eulerian framework domain containing a two-dimensional NACA 0012 foil moving with prescribed kinematics. Some of the important findings are: (1)...