Sharif Digital Repository

In this thesis, hemodynamic parameters of flow and deposition of low density lipoproteins (LDL) on wall of coronary arteries with taking into account their curvature on the heart are studied. At first, numerical solution of the blood flow by assumption of blood as incompressible and Newtonian fluid for steady and pulsatile inlet is done. Then by assuming LDL particles as dilute solute in the blood, LDL transport from artery lumen into arterial wall is studied. LDL accumulation and penetration into the vessel wall cause thickening of the walls and eventually eclipse it and its known as the first stage of atherosclerosis disease. The results show that low shear region occurs on inner wall... 

Different types of motion mechanisms can be found in any complicated or simple mechanical structure and linear motion is one of the most frequently used mechanisms for sure. In recent years, a wide variety of designs are developed to create linear motion, each one having many positive and negative points. Among already existing designs, those based on linear actuation are more considerable compared to those using a mechanical convertor to transform rotary motion to linear motion. This thesis presents two newly designed linear motors which utilize linear electromagnet actuators in their structures. In this study nonlinear models are developed for two linear motors. Although all conditions and... 

In general, Constrain Satisfaction Problems (CSP’s) are NP-complete, however, this is not the case, if we impose some restrictions on the constraints. Due to importance and applications of CSP’s in different areas of engineering and science including artificial intelligence, relational databases and logic, investigating the computational complexity of CSP’s is an important issue. Computational complexity of CSP’s has been investigated from a variety of aspects, including the Universal Algebraic approach that has given rise to a solution of dichotomy conjecture recently. In this thesis based on contributions of Bulatov, Krokhin and Jeavons, we try to explain this universal algebraic approach... 

One of the most practical deformation processes has been used to produce profiles with a diversity of shapes is forward extrusion. Minimizing the extrusion pressure along with reducing the curvature of the final product have always been the main concerns of the researchers in this area. To achieve the former, researchers have designed nonlinear dies and proposed various equations to determine proper die profile. To accomplish the latter, they have used bearing at the exit section of the extrusion die. The primary object of the current study is to design a proper bearing in order to eliminate the curvature of the final product in extrusion process. The effects of both bearing and die profile... 

Urmia Lake is a strong electrolyte containing various salts, with a thermodynamic identity. Changes in the temperature and volume of lake water cause a change in the concentration of ions in this brine as well as the composition and precipitation of salts in the lake. As a result of these changes, the thermodynamic properties of brine are also changed. The purpose of this study was to investigate the effect of mixing the rivers entering the lake and calculate and analyze the changes in the quality and hydrogeochemical characteristics of Urmia Lake and the amount of precipitation and dissolution of the main minerals in Urmia Lake during the period of 2007-2013 per month. For this purpose,... 

Undoubtedly, machine learning and its practical applications have become essential topics in research and industry. Among these, representation learning holds special importance. The goal in this field is to find low-dimensional and meaningful representations of high-dimensional data that encapsulate essential information. Most existing methods focus only on the statistical correlations in data, which do not necessarily indicate real relationships between variables and can affect learning performance. This becomes even more problematic when the distribution of test data differs from the training data, as it makes the learned representations less generalizable. To tackle this problem, causal...