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plasma Electrolytic Oxidation of AZ31 in Silicate and Phosphate Electrolyte and Study of Corrosion Behavior
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In recent years, magnesium and its alloys have been considered as biodegradable implants, but they corrode in the body before natural process of damaged organs recovery is completed. In this investigation PEO operation was used for corrosion control and effect of different parameter such as number of operation steps, electrolyte type, time and operation voltage on coating properties was studied. Scanning electron microscopy was used for investigating of morphology of coats and to determine chemical composition and phase of coats EDS analysis and X-ray diffraction were used. The corrosion resistance of samples were evaluated by potentiodynamic polarization and electrochemical impedance (EIS)...
Urban Transportation Network Design in Chaotic Conditions and Uncertainty in Travel Demand
, M.Sc. Thesis Sharif University of Technology ; Pourzahedi, Hossein (Supervisor)
Abstract
Transportation systems are dynamic and complex systems due to the interaction between human and non-human factors. In certain circumstances, the dynamics of traffic flow causes the transportation system fail to reach equilibrium and chaos will occur. In such cases, travel times vary daily and travel time reliability decreases. Moreover, these systems are continuously exposed to incidents that cause a high degree of uncertainty. So, it is necessary to enter such dynamics and uncertainty in the decision making models, such as network design. In this study a bilevel network design problem is defined with chaos and uncertainty taken into account. At the higher level problem, the optimization...
Modeling of Mixed Hinges and Their Use in the Inelastic Analysis of Frames
, Ph.D. Dissertation Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Considering the interaction of flexural moment and shear force in the steel frames with haunch or intermediate beam length and eccentrically braced frames with intermediate link length is a major concern of the structural analysis and design. This paper contains two stages. In the first stage, to investigate the moment-shear interaction for the highly ductile steel I-sections, a study is carried out using finite element analysis and a simple and practical relationship is developed. In the second stage, a simple approach based on virtual work method for assemblage of interconnected rigid bodies, is employed to consider collapse mechanisms with mixed hinges. Using this approach, the...
Binding Affinity Prediction Between Antibody and Antigen using Self-Supervised Learning
, M.Sc. Thesis Sharif University of Technology ; Sharifi Zarchi, Ali (Supervisor)
Abstract
In recent years, monoclonal antibodies have gained attention as highly effective drugs for treating diseases, especially cancer. The high binding affinity between an antibody and its corresponding antigen is one of the key factors in triggering an effective immune response. Modeling binding affinity using machine learning is considered a promising and cost-effective computational approach; however, due to the lack of training data, the performance of these models is often poor and limited. In contrast, recent advances in geometric learning have demonstrated that incorporating the three-dimensional geometry of protein structures in the learning process can significantly impact 3D...
Modeling, simulation, and optimal initiation planning for needle insertion into the liver
, Article Journal of Biomechanical Engineering ; Volume 132, Issue 4 , 2010 ; 01480731 (ISSN) ; Ahmadian, M. T ; Janabi Sharifi, F ; Sharif University of Technology
2010
Abstract
Needle insertion simulation and planning systems (SPSs) will play an important role in diminishing inappropriate insertions into soft tissues and resultant complications. Difficulties in SPS development are due in large part to the computational requirements of the extensive calculations in finite element (FE) models of tissue. For clinical feasibility, the computational speed of SPSs must be improved. At the same time, a realistic model of tissue properties that reflects large and velocity-dependent deformations must be employed. The purpose of this study is to address the aforementioned difficulties by presenting a cost-effective SPS platform for needle insertions into the liver. The study...
Estimation of Power Peaking Factor (PPF)Parameter in VVER Reactor Using Soft Computing, Case Study: Bushehr Nuclear Power Plant
, M.Sc. Thesis Sharif University of Technology ; Ghofrani, Mohammad Bagher (Supervisor) ; Moshkbar Bakhshayesh, Khalil (Supervisor)
Abstract
operation of a nuclear power plant. Therefore, constant monitoring of the reactor core with reliable methods is important. To monitor the reactor heart, it is necessary to estimate and calculate some parameters, with high speed and accuracy, such as power distribution inside the heart, reactivity feedback coefficients, PPF, DNBR, etc. Analytical methods are often used to calculate these parameters, which in case of failure of the sensors, the calculations will be practically disrupted, and the method used in this research can solve these problems by losing a small amount of accuracy.In this study using real data of Bushehr nuclear power plant (BNPP) and by soft computing methods and...
Quantification of in Vitro Drug Effects on COVID-19 through Analysis of Cellular Morphological Features
, M.Sc. Thesis Sharif University of Technology ; Rohban, Mohammad Hossein (Supervisor) ; Sharifi Zarchi, Ali (Supervisor)
Abstract
The epidemic of Covid 19 has killed millions of people worldwide. Despite the efforts of scientists around the world, there is still no cure for this disease. Approval of newly designed drugs due to clinical trial periods is time-consuming and costly. For this reason, in the current emergency situation, it is important to have a solution for screening available approved drugs in order to find effective substances for this disease.High-throughput assays are a good option for such problems. In this field of research, image-based high-throughput assays are amongst the most effective and cost-effective methods that help quantify the response of treated cells by measuring cell...
One-dimensional chemotaxis kinetic model
, Article Nonlinear Differential Equations and Applications ; Volume 18, Issue 2 , 2011 , Pages 139-172 ; 10219722 (ISSN) ; Sharif University of Technology
2011
Abstract
In this paper, we study a variation of the equations of a chemotaxis kinetic model and investigate it in one dimension. In fact, we use fractional diffusion for the chemoattractant in the Othmar-Dunbar-Alt system (Othmer in J Math Biol 26(3):263-298, 1988). This version was exhibited in Calvez in Amer Math Soc, pp 45-62, 2007 for the macroscopic well-known Keller-Segel model in all space dimensions. These two macroscopic and kinetic models are related as mentioned in Bournaveas, Ann Inst H Poincaré Anal Non Linéaire, 26(5):1871-1895, 2009, Chalub, Math Models Methods Appl Sci, 16(7 suppl):1173-1197, 2006, Chalub, Monatsh Math, 142(1-2):123-141, 2004, Chalub, Port Math (NS), 63(2):227-250,...
Effects of Dynamics and Structure on Population-level Oscillations in Homogeneous Neuronal Networks
, M.Sc. Thesis Sharif University of Technology ; Razvan, Mohammad Reza (Supervisor) ; Sharifi Tabar, Mohsen (Co-Advisor)
Abstract
Networks of neurons produce diverse patterns of oscillations, arising from the net-work’s global properties, the propensity of individual neurons to oscillate, or a mixture of the two. Here we describe noisy limit cycles and quasi-cycles, two related mech-anisms underlying emergent oscillations in neuronal networks whose individual com- ponents, stochastic spiking neurons, do not themselves oscillate. Both mechanisms are shown to produce gamma band oscillations atthepopulation level while individualneu-rons fire at a rate much lower than the population frequency. Spike trains in a network undergoing noisy limit cycles display a preferred period which is not found in the case...
Design, Fabrication and Evaluation of Polymeric Microcapsules Containing Cells to Use in Cell Therapy in Heart
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Sharifi, Ali Mohammad (Supervisor) ; Khanmohammadi, Mehdi (Co-Supervisor)
Abstract
Because of the inability of conventional methods to regenerate the infarcted part of the heart, regenerative medicine based on using scaffolds and hydrogels incorporation with cells and biological factors emerges as a promising approach. Micro-structures, especially hollow microcapsules created by the microfluidic system, has received a great deal of attention due to their inspired biomimetic structures, providing complete coverage cells, and preventing an immune response, consequently. This study aimed to use a microfluidic system to fabricate hollow microcapsules and investigate the behavior of rat cardiomyoblast cells (H9C2) along with exosomes within these structures. These structures'...
Cancer Detection and Classification in Histopathology Images Under Small Training Set
, M.Sc. Thesis Sharif University of Technology ; Rohban, Mohammad Hossein (Supervisor) ; Sharifi Zarchi, Ali (Supervisor)
Abstract
Histopathology images are a type of medical images that are used to diagnose a variety of diseases. One of these illnesses is the Leukemia cancer, which has four different subtypes and is diagnosed using a blood smear image. As a result of the advancement of deep learning tools, models for diagnosing various types of disease from images have been developed in recent years.In this project, one of the best models developed to diagnose four different types of disease was replicated, and it was demonstrated that, while this model achieves acceptable accuracy, its decision is not based on medically significant criteria. In the following, a general method for diagnosing the disease is proposed...
Investigating Effect of Nano Ceramic Coating of Combustion Chamber on the Performance of Internal Combustion Engines
,
M.Sc. Thesis
Sharif University of Technology
;
Naghdabadi, Reza
(Supervisor)
Abstract
Thermal barrier coatings (TBCs) are used for increasing the efficiency and reducing pollutants of internal combustion engines (ICEs). In this paper, an optimization framework is developed in order to obtain the optimal dimensions for conventional coat, and the optimal dimensions and material property for functionally graded (FG) coat of a partially coated piston. A thermo mechanical analysis is investigated for Nano coat by finite element method. The conventional and Nano coats are made of MgZrO_3 as the insulating ceramic overlay and NiCrAl as the metallic bond-coat. The properties of the FG coat is assumed to vary according to power law through the thickness. For all tree conventional, FG...
Thermally Driven Exchange Flow Between Open Water and Floating Vegetation
, M.Sc. Thesis Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
In this thesis, we present the results of a laboratory and numerical model study of the exchange flow generated by the temperature gradient between an open water heated by sunlight and a canopy area made of floating vegetation. Particle Image Velocimetry is employed to obtain the structures of the warm flow intruding the canopy at the surface and the bottom cold return flow for different roots length and vegetation density. Following an initial, transient stage of flow build-up governed by a balance between inertia and buoyancy forces, the flow reaches a steady state in the canopy area with a force balance between buoyancy and vegetation drag dominating the flow within roots. At the steady...
Corrosion behaviour of Ni-Co alloy coatings at Kish Island (marine) atmosphere
, Article Bulletin of Materials Science ; Vol. 37, issue. 3 , May , 2014 , p. 713-719 ; Ghorbani, M ; Sharif University of Technology
2014
Abstract
In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products
Multiple model filters applied to wind model estimation for a fixed wing UAV
, Article Proceedings of 2016 7th International Conference on Mechanical and Aerospace Engineering, ICMAE 2016, 18 July 2016 through 20 July 2016 ; 2016 , Pages 109-115 ; 9781467388290 (ISBN) ; Nobahari, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
The flight of unmanned aerial vehicles is often associated with model uncertainties, measurement noises, and environmental disturbances such as wind gust. To mitigate these challenges, the accurate estimation of states is vital. Moreover, the wind model and its parameters should also be estimated and compensated during the flight. In this paper, a multiple model filter is implemented for this purpose. To investigate the performance of the multiple model filter, three different models including constant wind, '1-cosine' model and wind shear model are considered. The multiple model filter utilizes three extended Kalman filter to simultaneously estimate the model of wind, the parameters of the...
Nonlinear robust adaptive Cartesian impedance control of UAVs equipped with a robot manipulator
, Article Advanced Robotics ; Volume 29, Issue 3 , Feb , 2015 , Pages 171-186 ; 01691864 (ISSN) ; Sayyaadi, H ; Sharif University of Technology
Robotics Society of Japan
2015
Abstract
In this paper, a new nonlinear robust adaptive impedance controller is addressed for Unmanned Aerial Vehicles (UAVs) equipped with a robot manipulator that physically interacts with environment. A UAV equipped with a robot manipulator is a novel system that can perform different tasks instead of human being in dangerous and/or inaccessible environments. The objective of the proposed robust adaptive controller is control of the UAV and its robotic manipulators end-effector impedance in Cartesian space in order to have a stable physical interaction with environment. The proposed controller is robust against parametric uncertainties in the nonlinear dynamics model of the UAV and the robot...
A Model for the Selection and Prioritization of Project Portfolio in the Project-Based Organizations
, M.Sc. Thesis Sharif University of Technology ; Hajji, Alireza (Supervisor)
Abstract
During recent years a variety of decision making models for project selecting and priorities have been developed. Most of these models used quantitative indicators for projects evaluating and focused on financial and economic indicators. In this project, a decision support system for project portfolio management in construction industry has been developed. The most important feature of this model that distinct it from others is its relationship with the organization's strategies. On one hand, this model focuses on the organization to ensuring that the projects selected for investment, meet the portfolio strategy and on the other hand, it focuses on project management to delivering projects...
Silver nano-islands on glass fibers using heat segregation method
, Article Materials Chemistry and Physics ; Volume 113, Issue 1 , 2009 , Pages 63-66 ; 02540584 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2009
Abstract
A new method for fabrication of silver nano-islands on glass fibers using a top-down process is introduced. A thin layer of silver chemically coated on the surface of the glass fibers evolves into silver islands by heat treatment. The effect of the concentration of the initial solution and the temperature were investigated. Segregation was more clearly observed for lower solution concentrations and higher temperatures. The temperature of 500 °C was found optimum where separated islands form. At higher temperatures, the coagulation and burial of silver islands occur. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and diffused reflectance spectroscopy (DRS) were...
Electrochemical and Microstructural Analysis of Aging Mechanism of 18650 LiFePO4/Graphite Li-ion Batteries under Different C-Rate and Temperature Conditions
, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous (Supervisor)
Abstract
In this study, the aging of the LiFePO4/graphite cell was investigated in two different types of 18650 Li-ion batteries during cycling at various C-rates (0.5, 1, 2, 3, 4C) and high temperature under long-term cycling. An amount of 20% Capacity loss was considered as the end of the cycling. Batteries with a capacity of 1500 mAh after this capacity drop, experience 60, 120, 1502, and 2155 cycles, at the rates of 4, 3, 2, and 1C , and batteries with capacity of 1400 mAh was also 60, 360, 1100, 1000, and 805 cycles at a rate of 0.5C. Capacity decrease of the cell is in linear relationship with cycle number and the slope of the capacity-fading line increases with elevating current rate. Aging...
Nonlinear robust adaptive sliding mode control of influenza epidemic in the presence of uncertainty
, Article Journal of Process Control ; Volume 56 , 2017 , Pages 48-57 ; 09591524 (ISSN) ; Moradi, H ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this paper, a nonlinear robust adaptive sliding mode control strategy is presented for the influenza epidemics in the presence of model uncertainties. The nonlinear epidemiological model of influenza with five state variables (the numbers of susceptible, exposed, infected, asymptomatic and recovered individuals) and two control inputs (vaccination and antiviral treatment) is considered. The objective of the proposed controller is decreasing the number of susceptible and infected humans to zero by tracking the desired scenarios. As a result of this decreasing, the number of exposed and asymptomatic individuals is also decreased and converged to the zero. Accordingly, it is shown that the...