Sharif Digital Repository

The incidence of skeletal diseases such as osteoarthritis and its progression and the need to use knee replacement implants have significant effects on the quality of life. With the improvement of living conditions and the prolongation of the average life expectancy of the society and the aging of a large part of the society, the concern about the increase in the incidence of skeletal diseases and the need to use alternative implants increases. On the other hand, many conditions such as osteoporosis and accidents lead to fractures and cavities in the bones. Bone cements are one of the most widely used materials in orthopedic and spinal surgeries.The aim of this study was to construct a... 

Nowadays environmental issues are of great importance and one of the most paramount issues is the quality of water, because clean water is vital to our existence. Besides different methods for water purification, water quality testing is a useful and needful tool. Traditional methods for determination of water quality parameters are mainly expensive, time consuming and require highly trained staff. In this study, we have described a centrifugal microfluidic platform (Lab- on – a- CD) for simultaneous determination of different physical and chemical parameters including Nitrite, Free Chlorine and pH. All of the processes from sample injection to detection are integrated on this low-cost and... 

Nowadays, cancer, which has been mentioned as the disease of the century, is the second leading cause of death throughout the world, and its incidence is constantly increasing. Isolation of circulating tumor cells is one of the most critical steps in diagnosing and controlling cancer progression. Due to the rarity of cancer cells compared to other cells in the blood sample, the isolation process requires optimal and high-precision devices. With the advent of inertial microfluidics, the ability to control the particles movement, the processing of blood samples as quickly and accurately as possible, and the viability of cells with a high percentage, introduced microfluidic systems as a... 

The prediction of deposition efficiency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems, and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three dimensional honeycomb like configuration and a fluid-structure interaction analysis is performed to study the normal cyclic breathing hydrodynamics. A viscoelastic model is used for the mechanical behavior of alveolar wall tissue. In contrast to previous works in which the inlet flow rate is predefined, in this model a negative pressure is imposed on the outside surface of the alveolus which causes air... 

An acinus is defined as the complex of airways supplied by one first order respiratory or transitional bronchiole. In this part, the replenishment of oxygen at the alveolar surface occurs by a combination of convective air flow with diffusion of oxygen in the air. So for studying gas exchange in the lung, modeling gas species transport and exchange in an acinus is important. Due to lacking direct measurements of the distribution of oxygen (or carbon dioxide) concentration in the acinus, several mathematical models have been developed and studied by numerical simulations. But in none of them the influence of breathing pattern and the role of blood flow in restricting the gas exchange rate have... 

In this thesis, cavitating flow over 2D/3D geometries of cavitators and projectile bodies in stationary and moving conditions are simulated using the "Volume of Fluid" (VOF) technique. The main application of VOF model is for simulating free surface flows. In this work, another capability is added to the VOF algorithm to solve for gas phase and by applying analytical-numerical mass transfer models, cavitation phenomenon is simulated. The developed algorithm precisely simulates the geometrical parameters of supercavities such as dimension and shape in a wide range of cavitation numbers. In addition, the flow parameters of supercavity such as drag coefficient, pressure coefficient inside the... 

Planing crafts in waves are characterized by large and violent vertical motion and acceleration. The hull structure is subjected to high impact loads and the crew experiences high transient vertical acceleration and in most cases the crew needs to lower speed in order to avoid damage to the hull.In recent years, interest on increasingly faster marine vehicles has remarkably grown. Typical planing monohulls are: patrol vessels, pilot boats, rescue vessels, coast guard vessels and small navy vessels. So the behavior of planing monohulls in waves has been a widely researched topic since more and more planing monohulls appeared.The accurate prediction of large amplitude ship motions in severe... 

In this thesis, the potential flow including unsteady partial cavitation around axisymmetric bodies are studied using a boundary element method (BEM) based on potential theory. For this purpose the wetted surface of the body and cavity surface are divided (approximated) to panels. Then, by applying the Green’s third identity and expressing this theory in potential flow around every surface, cavitation can be modeled by distributing the source and the dipole rings on cavity/body surface. In order to approaching this goal we introduced dipole rings distribution on the cavity and body surfaces and source rings distribution on the cavity surface. In this work the cavitation number is assumed to... 

The present study examines both Direct Current (DC) and Alternating Current (AC) electroosmotic flows in a parallel plate microchannel. The method consists of a central finite difference scheme for spatial terms and a forward difference scheme for the temporal term. Asymmetric boundary conditions are assumed for Poison-Boltzmann equation used to determine the electric double layer (EDL) potential distribution. The potential distribution is then used to evaluate the velocity distribution for both DC and AC electroosmotic flows. The velocity distributions are obtained by applying slip boundary conditions on the walls to account for probable hydrophobicity of the surfaces. After determining the... 

In positioning and navigation, Sonar with utilization of sound waves in water environments is similar to the role of Radar in not watered (irrigated) environments. In the Sonar field, modeling and simulation of propagation of sound waves in the undersea environment is a fundamental and very important topic. Nowadays simulation is significant tool that allow to the researchers to predict the quality of Sonar function respect to the experimental conditions. For simulation and modeling of sound wave propagation are used two different methods; Wave theory and Ray theory. In the wave theory, because of the large volume of data, the interpretation of the results is hard. Also in this method cannot... 

Atherosclerosis is one of the most important and common causes of death in the world. Atherosclerosis typically affects medium and large arteries in the body and it leads to plaque formation in arterial wall. The first stage of plaque formation has been related to accumulation of low density lipoproteins in arterial wall.
The purpose of this research is presenting a four-layer model to describe the LDL transport in the arterial wall. The endothelium, intima, internal elastic lamina (IEL) and media are all treated as macroscopically homogeneous porous media and the volume-averaged porous media equations are employed to model various layers. The physiological parameters within the various... 

Nowadays counting small particles and gathering their morphological information is widely used in many fields as medicine, engineering, etc. One of the best examples of this technology is counting and distinguishing different cells which are considered bioparticles. In this thesis a brief review of different particle counting methods is presented. Among these methods flow cytometry technology is chosen, because of its speed and accuracy. In flow cytometry method cells are conducted to the center of a transparent capillary by sheath flow technique; then laser beam is radiated to the cells. The intensity of the light scattered from the cells is used to determine cell type and count. In... 

The stirred tank is one of the oldest device that widely used in different industrial. a special kind of stirred tank that clled bioreactor refer to any device which supplies required biological, biochemical and biomechanical engineered product. Since the aim of bioreactor is produce of desired biological product, it is essential to accurate monitoring internal and external transfer of nutrient, heat transfer, fluid velocity, Strain stress and medium PH. good design and application of bioreactor depend on product, organism, conditions for produce desired product and scale of produce. also cost of capital and function cost are important in bioreactor design. one of the most important... 

Nowadays providing services beyond the expected performance of users has become the most competition among telecommunication companies. Increase data rate at which a user is able to use a wireless system, you know that most of these companies are competing with each other. However, due to limited power to be sent to a transmitter, the first proposal to increase the data rate of wireless data transmission has a wider bandwidth. This results in increased bandwidth demand and thus sales by the government. During these years, many researchers have tried to increase efficiency in the use of broadband transceiver. These systems due to the wide band signal transmission and high-resolution mass... 

Nowadays, reaching higher speed in marine crafts and underwater vehicles mostly requires a modern propulsor with high efficiency and enhanced cavitation performance. Because of these requirements, numerous researches for developing the existing propulsion systems and invention of new systems have been conducted in recent years. One of the most sophisticated and developed propulsion systems that have high hydrodynamic efficiency and high cavitation performance and low acoustic signature is pumpjet. This propulsor contains a rotor, stator and a duct that surrounds two other parts. Stator reduces the swirl of flow coming from rotor and thereby reduces the loss of energy. High cavitation... 

In this research, we consider the problem of guarding orthogonal polygon with sliding cameras. This problem is originated from the well-known Art Gallery problem. In the Art Gallery problem the goal is to guard the polygon with minimum number of guards. Each guard is considered as a point and can guard all the points inside the polygon that are in its visibility area. In sliding camera version, each guard is modeld as a horizontal or vertical segment which is entirely in the polygon. The guarding area of each camera is defined by its segment and its power. In 0-transmitter model, the guarding area of each camera is limited by the edges of polygon, but in the k-transmitter model cameras can... 

High speed crafts due to their design, geometry, one of the parameters to improve the performance of hydrodynamic elements such as trim tabs, bow thruster, steps and Spray rails.Step is an element which change height of bottom and due to reduce wetted area and extra lift and finally cause to improve drag of vessel.In this thesis we have evaluated numerically and compared with experimental tests on planning crafts in calm water and waves, and the effects on the motions of floating and drag floating are compared.Numerical analysis is conducted to help Ansys.CFX software. First, to provide 2D modeling and analyzing real-bodies floating in calm water and waves with simple, step-paid. The... 

Morphology and alignment of endothelial cells (ECs) have great influence on plaque formation. These alignments are based on the cyclic strains and wall shear stress (WSS) on the arterial wall. In the present study, cyclic strains and WSS are investigated to predict the secondary plaque locations downstream of the primary stenosis. Therefore, left coronary artery (LCA) with its branches to left anterior descending (LAD) and left circumflex (LCX) are 3D located on a virtual sphere to consider the cardiac motion. Stenoses are placed at the beginning of the bifurcation with varying degrees from 40% to 70% based on diameter reduction. Healthy coronary is also constructed to compare with those of...