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Design of the Coronary Stent Device to Improve Fluid Flow in Coagulated Vascular Regions
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor)
Abstract
The application of computational fluid dynamics (CFD) has been growing rapidly in biomedical engineering. The altered hemodynamics inside the blood vessels plays a key role in the development of the arterial disease called atherosclerosis, which is the major cause of human death worldwide. Atherosclerosis is often treated with the stenting procedure to restore the normal blood flow. A stent is a tubular, flexible structure, usually made of metals, which is driven and expanded in the blocked arteries. The presence of non-biological device in the artery causes inflammation or re-growth of atherosclerotic lesions in the treated vessels. Several factors including the design of stents and type of...
Computational study on design parameters of a solar chimney
, Article International Conference on Sustainable Mobility Applications, Renewables and Technology, 23 November 2015 through 25 November 2015 ; 2015 ; 9781467395298 (ISBN) ; Raveshi, S ; Shahsavari, M ; Sedaghat, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
Today, the production of energy and electricity is one of the major concerns of mankind. Electricity generation by solar energy is considered as one of the alternatives to fossil fuels. Solar chimneys mechanism is based on a natural phenomenon. In this process the solar energy heat up the earth's surface and the surrounding air. Due to the density difference between cold air and warm air, heated air ascends and causes air circulation. In this study, mathematical modelling of solar chimney and governing equations of this system will be discussed. In order to validate the numerical results, upwind velocity in chimney has been compared with a reliable reference results. As well as, the...
Three-dimensional numerical simulation of a novel electroosmotic micromixer
, Article Chemical Engineering and Processing: Process Intensification ; Volume 119 , 2017 , Pages 25-33 ; 02552701 (ISSN) ; Madadelahi, M ; Abdorahimzadeh, S ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Lab-on-a-chip (LOC) systems have been widely used in chemical and medical analyses. In this study, a novel T-shaped electroosmotic micromixer was simulated and the effects of different parameters on the mixing process were examined. These parameters include; inlet angle, number of conducting hurdles, arrangements of the hurdles, geometry of hurdles and chambers, aspect ratios of the channel cross-sectional profile, hurdle radius, and depth. It was found that the inlet angle has a direct influence on mixing index (σ). The effect of various number of hurdles (one, two, three and four hurdles) and their orientations was investigated. Simulations revealed that using two conducting hurdles is the...
Intra-And intermolecular interactions in a series of chlorido-tricarbonyl-diazabutadienerhenium(I) complexes: Structural and theoretical studies
, Article Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials ; Volume 76 , May , 2020 , Pages 417-426 ; Kalaghchi, A ; Sharif University of Technology
International Union of Crystallography
2020
Abstract
A series of new chlorido-tricarbonylrhenium(I) complexes bearing alkyl-substituted diazabutadiene (DAB) ligands, namely N,N′-bis(2,4-dimethylbenzene)-1,4-diazabutadiene (L1), N,N′-bis(2,4-dimethylbenzene)-2,3-dimethyl-1,4-diazabutadiene (L2), N,N′-bis(2,4,6-trimethylbenzene)-2,3-dimethyl-1,4-diazabutadiene (L3) and N,N′-bis(2,6-diisopropylbenzene)-1,4-diazabutadiene (L4), were synthesized and investigated. The crystal structures have been fully characterized by X-ray diffraction and spectroscopic methods. Density functional theory, natural bond orbital and non-covalent interaction index methods have been used to study the optimized geometry in the gas phase and intra-...
The effect of variable temperature and location on relative thermal conductivity (RTC) on the heat pipe in the presence of AL2O3 nanoparticles: Numerical and optimization approaches
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 124 , 2021 , Pages 132-149 ; 18761070 (ISSN) ; Mohammadiun, H ; Alizadeh, R ; Mesgarpour, M ; Younesian, A ; Jowkar, S ; Sharif University of Technology
Taiwan Institute of Chemical Engineers
2021
Abstract
Background: The cooling system is one of the important parts of new devices such as smartphones, servers, and other electrical devices. By employing the almost all heat transfer methods such as conduction, evaporation and condensation, heat pipes are the best choice to increase the heat transfer. The thermal conductivity of heat pipe is much higher than fins because they benefit from condensation and evaporation simultaneously. Methods: This study tries to present relative thermal conductivity base on temperature and length of a heat pipe in optimized geometry. To achieve this aim, unsteady, multiphase fluid was considered inside the heat pipe. Evaporation, condensation, and conduction were...
Optimal geometry analysis for tdoa-based localization under communication constraints
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 57, Issue 5 , 2021 , Pages 3096-3106 ; 00189251 (ISSN) ; Behnia, F ; Amiri, R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
The sensor-source geometry has a significant effect on accuracy of source localization problems. In a sensor placement problem, one attempts to optimally place the sensors in the surveillance area so as to optimize a performance criterion. Sensor placement methods mainly solve the associated problems without taking any specific constraint on permissible location of sensors into account. In practical applications, however, possible location for deployment of the sensors are subject to such limitations as environmental, industrial, and communication constraints, which affects the optimal sensor-source geometry. In this article, we consider the problem of optimal sensor placement, based on time...
Aerosol nano-particle charger simulations and optimizations
, Article Scientia Iranica ; Volume 23, Issue 5 , 2016 , Pages 2220-2229 ; 10263098 (ISSN) ; Saidi, M. S ; Sani, M ; Sharif University of Technology
Sharif University of Technology
Abstract
Size distribution of aerosol particles is prevalently obtained through electrical characterization techniques and study of charged particles' dynamics in the presence of electric field. In this work, a wire-cylinder corona charger is presented, redesigned, and aero dynamically optimized. An initial 2D axisymmetric geometry of the charger was employed for the simulations using the Computational Fluid Dynamics (CFD) commercial code FLUENT 6.3.26. Through successive attempts, a new geometry was obtained by streamlining the walls to eliminate the undesired vortices produced in the flow field of the previous ones. The process optimized the charger by minimizing losses and dilutions of the...
Mamsim: A computational software platform for measuring and optimizing imaging and dosimetry parameters in screen-film and digital mammography systems
, Article 15th IEEE International Symposium on Medical Measurements and Applications, MeMeA 2020, 1 June 2020 through 3 June 2020 ; July , 2020 ; Vahdat, B. V ; Ebrahimi Khankook, A ; Noorvand, M ; IEEE; IEEE Instrumentation and Measurement Society; IEEE Sensors Council Italy Chapter; Politecnica di Bari; Politecnico di Torino; Societa Italiana di Analisi del Movimento in Clinica ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
The aim of this work is to develop a mammography Monte Carlo MCNP-FBSM based simulation platform called 'MamSim' that is able to model the detailed geometry and physics of commercial screen-film and digital mammography units. This simulation platform is designed to enable the virtual assessment and optimization of mammography protocols and parameters for obtaining the desired image quality while diminishing radiation dose to the patient in both contact and magnification modes. A graphical user interface generates MCNP-FBSM input files for simulating mammography units under various geometries and imaging protocols. We considered the full simulation of all components of mammography procedure...
Geometrical optimization of half toroidal continuously variable transmission using particle swarm optimization
, Article Scientia Iranica ; Volume 18, Issue 5 , 2011 , Pages 1126-1132 ; 10263098 (ISSN) ; Saadat Foumani, M ; Boroushaki, M ; Ekhtiari, M ; Dehghani, M ; Sharif University of Technology
Abstract
The objective of this research is geometrical optimization of half toroidal Continuously Variable Transmission (CVT) in order to achieve high power transmission efficiency. The dynamic analysis of CVT is implemented and contact between the disk and the roller is modeled viaelastohydrodynamic (EHL) lubrication principles. Computer model is created using geometrical, thermal and kinetic parameters to determine the efficiency of CVT. Results are compared by other models to confirm the model validity. Geometrical parameters are obtained by means of Particle Swarm Optimization (PSO) algorithm, while the optimization objective is to maximize the power transmission efficiency. Optimization was...
Coanda surface geometry optimization for multi-directional co-flow fluidic thrust vectoring
, Article Proceedings of the ASME Turbo Expo: Power for Land, Sea, and Air ; Volume 5 , 2009 , Pages 183-189 ; 9780791848869 (ISBN) ; Banazadeh, A ; Sharif University of Technology
Abstract
The performance of Co-flow fluidic thrust vectoring is a function of secondary flow characteristics and the fluidic nozzle geometry. In terms of nozzle geometry, wall shape and the secondary slot aspect ratio are the main parameters that control the vector angle. The present study aims to find a high quality wall shape to achieve the best thrust vectoring performance, which is characterized by the maximum thrust deflection angle with respect to the injected secondary air. A 3D computational fluid dynamics (CFD) model is employed to investigate the flow characteristics in thrust vectoring system. This model is validated using experimental data collected from the deflection of exhaust gases of...