Sharif Digital Repository

This thesis extends a probabilistic framework for evaluating the seismic resilience of communities by modeling the transportation system. The framework that is being extended is under continuous development at the Center for Infrastructure Sustainability and Resilience Research (INSURER) at Sharif University of Technology quantifies community resilience by integrating hazard models, risk models, and recovery models within an agent-based simulation. In this framework, the transportation system is modeled by developing a library of probabilistic models to predict the occurrence and intensity of earthquake hazard, damage and capacity of network components, network travel demand, and economic,... 

In various industries, particularly in the process industries, computational fluid dynamics (CFD) stands as the predominant method for simulating distributed systems. In these methods, discretization of system geometry and partial differential equations is necessary, resulting in a system of algebraic or ordinary differential equations, or a combination thereof. The significant computational demands arising from the extensive number of equations derived from dynamic system simulations highlight the necessity for substantial processing and computing power. The objective of this project is to reduce the computational load associated with solving these equations. It focuses on utilizing machine... 

The solution to the hyperbolic conservation laws may involve discontinuities or shocks even if initial condition is smooth. Devising low cost methods which can identify shocks accurately, has always been a challenge. This project focuses on applying high resolution schemes to the solution of two and three phase Buckley-Leverett equation and hyperbolic conservation laws in general.Buckley-Leverett equation is a transport equation which is used to describe two and three phase flows in porous media. Weighted Essentially Non-Oscillatory (WENO) schemes with reconstruction on fluxes in finite difference formulation are used to solve one dimensional systems of equations including Euler equation as... 

In this thesis, two types of two-phase flow are studied in one dimension. The first type is oil-gas two-phase flow which is miscible and compressible. The second one is oil-water two-phase flow which is immiscible and incompressible. Oil wet and water wet conditions are studied in the second type of flow. Two approaches, i.e. double porosity and double porosity-double permeability, are used to study naturally fractured reservoirs. In these approaches, the matrix and fracture are modeled as two separate media that exchange mass via a transfer function. Black oil model is applied to simulate the fluid system. The governing equations consist of the conservation of mass equations for each... 

At today’s crowded world, the importance of automobile transportation is obvious for all. Due to energy crisis and air pollution problems, designing and manufacturing high-performance and low emission engines is very important. Because of high efficiency and low fuel consumption, diesel engines have attracted more attention. In addition to the mentioned advantages, diesel engine’s nitrogen oxide and particulate matter emissions are very high. So to limit these pollutants, strict standards was legislated by different countries and nations. Recently in the field of diesel engines emission reduction, low temperature combustion concept is proposed that can reduce nitrogen oxide and particulate... 

Parkinson's disease is a progressive neurodegenerative disease in which balance disorders are a common symptom. Clinical and non-clinical methods have been developed to evaluate the quality of maintaining balance. Clinical methods include questionnaires and tests that are scored by the therapist and therefore depend on the examiner's skill. On the other hand, there are biomechanical methods that do not depend on the therapist's skill. Posturography -based methods are among the biomechanical tests used today to assess balance. In these methods, some indicators are extracted from the patient's foot center of pressure that can measure the quality of balance. These studies usually examine the... 

One of the methods of measuring the flow rate in a pipe (channel) is by using the acoustic waves with long wavelenghs in Sonar flowmeters. This flowmeter consists of an array of sensors, mounted on the outer wall of the pipe. These sensors by listening and interpreting the sound waves passing through the fluid, would give a “non-intrusive” measurement of the volumetric flow rate. This means that the flowmeter is not in direct contact with the flow and therefore its repair, relocation or replacement will not disturb the flow. In this project, we will provide a clear understanding of the principles and physics involved in sonar-based acoustic flowmeters, by means of numerical simulation of the... 

In this research, a simple yet efficient two-dimensional model of proton exchange membrane fuel cell (PEMFC) is developed using stream function-vorticity formulation. The model accounts for the fluid flow and masstransport processes in cathode gas channel and gas diffuser layer. The governing equations are decoupled and solved usingtwo efficient approaches, Alternating Direction Implicit (ADI) and False Transient Method (FTM) in a modified geometry to simulate the fully-developed condition consistently. An in-house code was developed to perform a parametric study of fuel cell performance. The results show the variations of important parameters along the cathode channel such as velocity...