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ebadi--ali
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Using a combination of vibration absorber and a classical active controller to suppress the chatter vibration and increase the stability in turning process
, Article 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021, 5 July 2021 through 7 July 2021 ; 2021 ; 9781665418478 (ISBN) ; Moradi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Free, forced, and self-excited vibrations are the three main types of machine tool vibrations. Self-excited vibration is the most important type of destructive vibration in machining. The most important factor in increasing the chipping rate, stability, and tool life is decreasing this type of destructive vibration. In this paper, we aim to introduce a method to control the self-excited vibrations by the means of the combining a vibration absorber as a passive controlling method and a classical active controller such as PID or compensator or the other classical methods. Utilizing the SIMULINK toolbox of MATLAB software, first, we designed and added the vibration absorber to the model...
Design of Customized Cemented Stems for Hip Joint Arthroplasty Surgery in Patients with Severe Femoral Deformity
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor)
Abstract
Hip replacement surgery is performed with the aim of relieving pain and restoring the normal function of the joint for patients who are in the final stages of arthritis. Standard prostheses offered by implant manufacturers come in a wide variety of models and sizes to meet the needs of patients. However, these commercial prostheses may not be suitable for patients with significant bony abnormalities, leading to implant instability and loosening. In such cases, a suitable solution is to use customized implants that are specifically designed to match the patient's unique anatomy. The purpose of this research was to design a customized cement stem for hip joint replacement surgery in patients...
A Novel Approach in DNA Sequencing Based on Physical Differences of Nucleotides
, M.Sc. Thesis Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor) ; Meghdari, Ali (Supervisor) ; Vossoughi, Gholamreza (Supervisor)
Abstract
With the continued improvement of sequencing technologies, the prospect of genome-based medicine is now at the forefront of scientific research. To realize this potential, however, a revolutionary sequencing method is needed for the cost-effective and rapid interrogation of individual genomes. Generally there are key factors in the definition and evalution of sequencing methods: 1-read length, 2-throughput, 3-read accuracy, 4-read depth, and 5-cost per base. The purpose of developing new sequencing methods is making better at least one of these factors. In order to reach the goal of rapid and low-cost sequencing method, one cannot rely only on current techniques. Improvements of current...
Designing and Manufactureing a Concentration Gradient Generator
, M.Sc. Thesis Sharif University of Technology ; kashaninezhad, navid (Supervisor)
Abstract
Nowadays, due to the growing need of the human to further improve the health of the community, research in the field of pharmacology as well as simulation of the cell culture environment is increasing. One of the most important requirements for simulating cell culture is the use of concentration gradient in culture media. The reason for this is the dependence of cellular activity on the presence of a gradient of concentration in the environment. Also, in drug investigations, in order to speed up the examination of different drugs and reduce the amount of drug that will used, different concentrations of the drug should be considered simultaneously in the microchips. Therefore, to make the...
Study and Preparation of Gas-adsorbent Polymers
,
M.Sc. Thesis
Sharif University of Technology
;
Mousavi, Abbas
(Supervisor)
Abstract
In the current situation of energy, gas storage is one of the basic needs. Different methods have been used in order to storage gases. One of these methods is the adsorption of gases on solid materials, which are called as adsorbents. In recent decades, different gas adsorbents, such as silica gel, zeolite and activated carbon, have been studied. Most of these adsorbents are nonorganic materials. Recently, many researchers have tried to apply polymeric materials as gas adsorbents. In this regard, the obtained results on the different polymers showed that it is possible to achieve the proper gas adsorption. In this study, different samples were prepared from polysulfone by phase inversion...
Synthesis of highly dispersed nanosized NiO/MgO-Al2O3 catalyst for the production of synthetic natural gas with enhanced activity and resistance to coke formation
, Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 38 , 2018 , Pages 12700-12714 ; 08885885 (ISSN) ; Tourani, S ; Khorasheh, F ; Sharif University of Technology
2018
Abstract
Nickel nanoparticles supported on MgO-Al2O3 and Al2O3 were synthesized by an impregnation method using dinitrobisethylenediamine nickel and nickel nitrate hexahydrate as precursors and were used as catalysts for CO methanation. Different MgO contents (1.5-11.25 wt %) were employed for the preparation of supports, and NiO loadings were in the range of 10-40 wt %. The optimum catalyst prepared from proper amounts of MgO (∼2 wt %) and NiO loading (20 wt %) with [Ni(en)2(H2O)2](NO3)2 as precursor and a mesoporous support with a wide range of mesopores resulted in highly dispersed nickel nanoparticles that exhibited moderate metal-support interactions, lower acidic surface sites, and enhanced...
Anodizing behavior and electrochemical evaluation of accumulative roll bonded Al and Al-SiC composite
, Article Surface and Coatings Technology ; Volume 408 , 2021 ; 02578972 (ISSN) ; Alishavandi, M ; Paydar, M. H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Accumulative roll bonded (ARBed) AA1050 and Al-2 vol% SiCp (AMC) samples were anodized in an H2SO4 electrolyte to improve corrosion resistance. The SEM images revealed that the anodic oxide's morphology is significantly dependent on the microstructure of the ARBed bare samples, owing to high internal energy that accelerates Al consumption during anodizing process. Potentiodynamic polarization measurements and EIS evaluation showed that anodic oxide improves the corrosion resistance of both ARBed AA and AMC samples; however, the electrochemical behavior of the processed samples changed due to the formation of a complex oxide structure comprising of twisted pore channels and attack routes. ©...
Coupled ionic-electronic equivalent circuit to describe asymmetric rise and decay of photovoltage profile in perovskite solar cells
, Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) ; Aryanpour, M ; Mohammadpour, R ; Taghavinia, N ; Sharif University of Technology
Nature Publishing Group
2019
Abstract
In this research, we employed transient photo-voltage rise and decay measurements to investigate the origin of slow unsymmetrical rise and decay profiles in single and triple cation perovskite solar cells. Drastic changes in photo-voltage decay profile were observed upon insertion of Br−, Cs+ and FA+ ions into perovskite structures. In order to explain our observations, the activation energy for ionic defects was measured and an equivalent circuit model was proposed containing both electrical and ionic components. The electrical branch consists of a diode, the bulk capacitance and resistances for charge transport and recombination. In parallel we introduced an ionic branch describing the...
Microstructural and mechanical evaluation of submerged arc welded HSLA 4135 steel by modeled and manufactured granular Cr-Mo bonded active basic flux
, Article Journal of Materials Processing Technology ; Volume 290 , 2021 ; 09240136 (ISSN) ; Mohammadmirzaei, M ; Ebadi, M ; Kokabi, A. H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Bead-on-plate submerged arc welding was performed on the AISI 4135 heat-treatable low-alloy (HTLA) steel using S2 welding wire and granular Cr-Mo basic flux. The Cr-Mo active flux was produced by the bonded -unfused method. The alloying elements were introduced into the weld metal by active flux. Two methods were introduced for calculating the recovery rate (η) of the alloying elements. Moreover, by defining the slag factor (α) of the process and η of the alloying elements, the amount of a specific element transferred from flux into WM was calculated by the proposed equation. Likewise, microstructure evolutions, inclusions characteristics, longitudinal tensile, indentation, and CVN impact...
Microstructural and mechanical evaluation of submerged arc welded HSLA 4135 steel by modeled and manufactured granular Cr-Mo bonded active basic flux
, Article Journal of Materials Processing Technology ; Volume 290 , 2021 ; 09240136 (ISSN) ; Mohammadmirzaei, M ; Ebadi, M ; Kokabi, A. H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Bead-on-plate submerged arc welding was performed on the AISI 4135 heat-treatable low-alloy (HTLA) steel using S2 welding wire and granular Cr-Mo basic flux. The Cr-Mo active flux was produced by the bonded -unfused method. The alloying elements were introduced into the weld metal by active flux. Two methods were introduced for calculating the recovery rate (η) of the alloying elements. Moreover, by defining the slag factor (α) of the process and η of the alloying elements, the amount of a specific element transferred from flux into WM was calculated by the proposed equation. Likewise, microstructure evolutions, inclusions characteristics, longitudinal tensile, indentation, and CVN impact...
Microstructural and mechanical evaluations of SAW by manufactured granular basic bonded Cr, Mo, and Cr–Mo active fluxes on ST37 low carbon steel
, Article International Journal of Advanced Manufacturing Technology ; Volume 119, Issue 9-10 , 2022 , Pages 6335-6347 ; 02683768 (ISSN) ; Mohammadmirzaei, M ; Ebadi, M ; Kokabi, A. H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Abstract: Bead-on-plate submerged arc welding was conducted on St37 steel by manufactured Cr, Mo, and Cr–Mo active basic fluxes produced via the unfused bonded method. The base metal heat-affected zone and weld metal (WM) microstructures were identified and characterized by optical microscopy and scanning electron microscopy. Furthermore, each element’s recovery rate (η) and slag factor (α) determine the amount of element transferred from flux into WM. Then, the ferrite morphologies volume fraction of WMs was measured. Moreover, the chemical analysis of slag and inclusions was evaluated by point scan energy-dispersive X-ray spectroscopy and extensively discussed. The number density and...
Estimating The Demand of Freeways in Iran, Using Discreet Choice Model
, M.Sc. Thesis Sharif University of Technology ; Rahmati, Mohammad Hossein (Supervisor) ; Vesal, Mohammad (Supervisor)
Abstract
According to the principle No. 44 of the Constitution of the Islamic Republic of Iran, Roads are in the public domain and are at the discretion of the Government. The result of this rule is that there is always a free route on the side of the freeway and motorists have the right to choose between a freeway and its successor road. This is a perfect laboratory condition which gives the opportunity that can be used with discrete choice models to estimate the demand of freeway versus its successor. In this paper we estimate the determinant parameters of the freeway demand versus the successor road and price elasticity of demand that can be calculated separately for each path. The results show...
Origin of apparent light-enhanced and negative capacitance in perovskite solar cells
, Article Nature Communications ; Volume 10, Issue 1 , 2019 ; 20411723 (ISSN) ; Taghavinia, N ; Mohammadpour, R ; Hagfeldt, A ; Tress, W ; Sharif University of Technology
Nature Publishing Group
2019
Abstract
So-called negative capacitance seems to remain an obscure feature in the analysis of the frequency-dependent impedance of perovskite solar cells. It belongs to one of the puzzling peculiarities arising from the mixed ionic-electronic conductivity of this class of semiconductor. Here we show that apparently high capacitances in general (positive and negative) are not related to any capacitive feature in the sense of a corresponding charge accumulation. Instead, they are a natural consequence of slow transients mainly in forward current of the diode upon ion displacement when changing voltage. The transient current leads to a positive or negative ‘capacitance’ dependent on the sign of its...
A First-Order Interior-Point Method For Linearly Constrained Smooth Optimization
, M.Sc. Thesis Sharif University of Technology ; Peyghami, Mohammad Reza (Supervisor) ; Fotouhi, Morteza (Supervisor)
Abstract
In this thesis, we propose a first-order interior-point method for linearly constrained smooth optimization which was recently proposed in the literatuare that unifies and extends first-order affine-scaling method and replicator dynamics method for standard quadratic programming. Global convergence and, in the case of quadratic program, the (sub)linear convergence rate and iterate convergence results are derived.The method is implemented and numerical experiments on simplex onstrained problems with 1000 variables is reported
Radiating Cosmological Black Hole Horizons
, M.Sc. Thesis Sharif University of Technology ; Mansouri, Reza (Supervisor) ; Taghizadeh Firouzjaee, Javad (Co-Advisor)
Abstract
One of the main subjects that has been vastly studied recently, is the final fate of Black holes with Hawking radiation. Radiation of a black hole changes the black hole, thus horizons of the black hole will also have dynamics. For a radiating black hole the inward flux of matter and the flux of radiation are two important factors for determining black hole energymomentum tensor that determine dynamics of different kinds of horizons. Quantum flux calculation needs choosing a proper quantum state as vacuum for calculating the expectation value of energy-momentum tensor. In this thesis we have attempted to write a useful reference and we hope it could help the reader to prepare for studying...
Investigation of the Ion Migration Mechanism and its Effect on the Slow Response of Perovskite Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
In recent years, organo-metal perovskite solar cells have attracted remarkable attention due to their low cost manufacturing method as well as the rapid growth of efficiency. Despite the fast growing efficiency of organo-metal perovskite solar cells, there are big challenges around their low stability under real operational condition. In addition to extrinsic parameters like oxygen and humidity, intrinsic instability of perovskite rises mainly from ion migration in perovskite film. In order to understand the ion migration and its effect on photovoltaic parameters of the devices, appropriate characterizations and analysis are needed. Since ions are much slower compare to electrons, their...
A tool for designing tree-like concentration gradient generators for lab-on-a-chip applications
, Article Chemical Engineering Science ; Volume 212 , 2020 ; Moshksayan, K ; Kashaninejad, N ; Saidi, M. S ; Nguyen, N. T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Concentration gradient generators (CGGs) help biologists to perform large scale, fast and high-throughput experiments. This paper introduces a design tool called Tree-like Concentration gradient generator Design Tool (TCDT). The performance of this tool is validated both numerically and experimentally. Three CGGs were fabricated using three different fabrication methods and design parameters. The performance of these devices was examined using the measurement of fluorescent and dye intensity. The performance of the design tool for non-linear and multi-drug concentration gradient generations was investigated as well. In addition, a method was developed to investigate the multi-drug...
The Relationship Between Satisfaction and Repurchase Behavior in Business in IRAN
, M.Sc. Thesis Sharif University of Technology ; Moayedi, Vafa (Supervisor) ; Askariazad, Mohammad Hossein (Co-Advisor)
Abstract
This research enlarges the content of the literature related to the business switching behavior by examining why dissatisfied customers remain in relationship with their existing service provider and do not exit, in the business to business context in Iran. The study develops and tests a model investigating the factors which potentially affect on dissatisfied customers to stay in relationship and also perform upon their repurchase intention. The proposed model specifies a set of propositions among dimensions of switching barriers, switching cost, interpersonal relationship, lack of attractive of alternative, dependence, calculative commitment, service recovery, inertia, lower price, method...
Development of Transient Model of Fuel Consumption to Optimize IVT
, M.Sc. Thesis Sharif University of Technology ; Saadat Foumani, Mahmoud (Supervisor) ; Kazemzade Hannani, Siamak (Co-Advisor)
Abstract
Changes in the internal structure of engines for reducing fuel consumption has almost stopped. While changes in powertrain is a better way to reduce vehicle fuel consumption. Recently, infinitely variable transmissions or IVTs have attracted large attention of car manufacturers . In these systems, due to the continuous transmission ratio, engine speed is kept in a range which is the optimum fuel consumption speed range. Designing of these systems for each vehicle must be done according to the requirements of the vehicle and engine abilities. So, an exact model of engine fuel consumption for the design of these systems is required. One way of improving the accuracy of conventional models, is...
Corrosion-wear behavior of AA1050/mischmetal oxides surface nanocomposite fabricated by friction stir processing
, Article Journal of Alloys and Compounds ; Volume 832 , 2020 ; Razmjoo Khollari, M. A ; Ebadi, M ; Alishavandi, S ; Kokabi, A. H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, the wear and corrosion characteristics of six-pass friction stir processed (FSPed) AA1050/mischmetal oxide nanocomposite (6PPA) was compared to six-pass FSPed sample without powder (6 PA) and annealed base metal (BM). Different wear characteristics, such as weight loss, wear rate and coefficient of friction (COF) were studied. In order to evaluate the corrosion resistance of samples, immersion and cyclic polarization tests were performed. In addition, worn and corroded surfaces were investigated by field emission scanning electron microscopy (FESEM). The result of pin on disk dry sliding wear test revealed that wear resistance improved by employing FSP through finer grain...