Sharif Digital Repository

A Cylinder Liner is one of the most important functional parts that gives a wear protective surface of cylinder block for piston and piston rings. Liners are used in automotive, ships, power aircrafts, and power generation units and the most load carrying part in internal combustion engine. Liners are subjected to various stresses during the engine working status. The stresses which act on cylinder liner are stress due to action of gas pressure and heat. Result of that stresses, wear developed inside of liner and internal or external cracking of cylinder liner takes place. In this paper, complete thermo-mechanical analysis of cylinder liner and failure mechanisms detected in alloyed cast... 

Around 20 to 50 percent of the operation costs occurs in manufacturing is related to facility layout. Efficient design would reduce these costs by 10 to 30 percent. Facility layout consists of design of material handling system and plant layout. Design of material handling system includes determining, the flow network and locations of Pick-up and Delivery stations which are defined regarding to the kind of material handling equipment. Today, Automated Guided Vehicles are considered as the basic material handling equipment due to their potentials in production planning and controls, high safety and flexibility and low expenses.
In this thesis, we first discuss the design of the shortest... 

In this thesis, bayesian network has been used in analyzing the failure of a structural component. The design life of a structural component of a system can be limited or unlimited depending on the working conditions considered by the designers. However, usually during the operation of an industrial system or device, a structural component of it fails prematurely, in other words, its actual life is less than the design life. In this case, the failure must be analyzed to find the causes and factors. The method of work is such that first, according to the problem and the type of failure, the required analyzes and studies are considered. Then, a number of samples of the components, whose... 

The material handling cost is a significant portion of the operational costs in a production system. Designing an efficient material transport network helps reduce these costs. In most unequal-area facility layout models, the total loaded trip distances are minimized, and the empty flows are overlooked. In these models, it is assumed that the transportation of load is possible through bidirectional rectilinear paths connecting pairs of departments, and the optimal location of departments is determined based on the rectilinear centroid-to-centroid distances. These assumptions lead to a complex network with a large number of edges, which is impractical to implement in reality. In this study, a... 

In this Thesis ,the two-dimensional thermoelastic tractive rolling contact problem for an FGM coated half-plane under the plane strain deformation is investigated. A rigid cylinder rolls on the surface of an FGM coated half-plane with constant translational velocity, generating frictional heat in the slip zones of the contact area. Thermo-mechanical properties of the FGM vary exponentially along the thickness. It is assumed that the contact area consists of a central stick zone and two slip zones of the same sign. The transfer matrix method and Fourier integral transform technique are used to achieve a system of two Cauchy singular integral equations. The associated governing equations are... 

The potential of phase change process in liquids at microscale has been a favorite for the scientists to fabricate this type of micropumps. To hold unidirectional flow in microchannels usually nozzle-diffuser arrangement is used. Due to the existence of difference in pressure drop in the nozzle and diffuser sections, one can see unidirectional flow through diffuser direction. The objective of this article is to analyze analytically the thermo-hydrodynamic behavior of the Isopropyl Alcohol (IPA) bubble of a phase change micropump. Considering the simultaneous effects of hydrodynamic and thermal characteristics of the bubble in the bubble generation chamber, and temperature-saturation... 

Porous burner technology has many advantages in comparison with conventional burners such as higher burner thermal performance, lower pollutants emission, high power ranges, fuel flexibility, compact geometry and higher turn down ratios. These kinds of burners are made of preheated porous combustion zone and combustion porous zone that have different thermophysical and geometrical properties. In this work, the transient one-dimensional multi-step premixed laminar reacting flows in a two-stage porous media burner have been investigated. The combustible mixture is considered H2-Air (9 species and 19 reactions) and CH4-Air (22 species and 49 reactions). In porous media, without lateral wall... 

In this research we investigate the effect of demand disruption on coordinating a supply chain with one manufacturer and one retailer competing with a manufacturer. For this purpose we consider two kinds of demand function: 1) a demand function which determines the demand deterministically and 2) a demand function with a random factor which determines the demand stochastically. Also we assume that in competition between retailer and competing manufacturer, retailer possesses more power than his rival in the market. In order to study the effect of demand disruption on coordinating the supply chain, first we consider coordination without demand disruption by using linear quantity discount and... 

Hydrocyclones are used for separating different materials from liquids in a variety of applications. Compactness, efficiency, reliability and low maintenance costs are their noteworthy characteristics. Dewatering and deoiling hydrocyclones used for refining crude oil or oily waste water in offshore platforms are examples of liquid-liquid hydrocyclones. Separation process in hydrocyclones is based on the fact that swirl flow induces a centrifugal force and leads to separation due to density difference. The density difference in liquid-liquid mixtures is smaller than solid-liquid types and trying to separate one liquid from another takes much more effort than the other type. Increase of... 

Integration of radio transceivers results in developing low power low cost wireless systems and allows delivery of multimedia contents to battery-powered mobile terminals. Portable reception of digital video for hand-held devices is one of the applications, for which, some telecommunications standards have been developed in the recent years. This research deals with the integrated implementation of the radio frequency parts of the digital video receiver, especially the frequency synthesizer. The key aspects of the digital video reception system are the required signal to noise ratio, which is relatively high, wide band input signals and strong interferers in the receiving band.
In... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

Influence tactics are methods which people use to influence others. These tactics may have different effect due to their sources of power, context, etc. On the other hand, if others perceive somebody authentic while he/she is using a tactic, it can be more effective. Through in-depth interviews with the members of the government and private sector dialogue council in Yazd’s Chamber of Commerce, this research examines the tactics of rational persuasion, appraisal and ingratiation. It seems that knowing the person who is arguing, the validity of his argument, emotionalizing the meeting atmosphere and some side factors like body language are effective in the perception of authenticity from that... 

Since the seminal work of Modigliani and Miller, the basic question of whether a unique combination of debt and equity capital maximizes the firm value, and if so, what factors could influence a firm’s optimal capital structure have been the subject of frequent debate in the capital structure literature. Empirical work in this area has lagged behind the theoretical research, perhaps because the relevant firm attributes are expressed in terms of fairly abstract concepts that are not directly observable and furthermore capital structure decision-making is even more complicated when it is examined in an international context, particularly in developing countries where markets are characterized... 

This project is about crest triangular weirs. The discharge is a function of triangular angle and head of the water. There are so many projects that is about the effect of various parameters on the discharge of weir. In some places we can not use just one symmetric weir so we have to use multi weirs. Because of the lack of information in multiasymmetrical weirs, the goal of this project in studing multi triangular weirs in laboratory. We used the civil engeneering department of sharif university chanel that is 148 cm in width and 40 cm in height. In this project we used three 60, two 90 and two 45 triangular weirs that instaleed singular,double and triapple in various position in width. In... 

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...