Sharif Digital Repository

Since oil is the essential foundation of Irans economy and our country has access to deep water, the extraction of oil from the deep water is essential to our country. So far, due to the possibility of oil exploration in the shallow water of the Persian Gulf, need to invest in deepwater oil industry has not been one of the priorities. However, it seems that in the near future we will need to invest in deepwater. Among subsea structures which we need to use to extract the oil in deepwater, we can mention wellhead manifolds that are used to expand the oil field, optimisation of pipeline length, gathering and distribution of production and injection of water or gas into the wells. In some cases... 

In the present study, simultaneous adsorption of water, mercaptans, carbon dioxide and heavy hydrocarbons on three layers bed, namely Activated Alumina, 4A and 13X Molecular Sieve, on PTSA process is designed and simulated for LNG production. The level of water and mercaptan should be decreased to less than 0.1 ppmv at the bottom of zeolite 4A and 3 ppmv at the bottom of zeolite 13X layer respectively. The main purpose of this study is to investigate the dynamic simulation of multi-component adsorption on a multi-layer bed and to predict the effect of different operational variables on adsorption performance. Multi-layer bed decreases the investment cost and operational challenges in... 

One of the important experiments on satellites and their components is testing of their resistance to shock wave known to pyroshock. Pyroshock is transient response of a structure to a high frequency and high acceleration shock wave that is created by the action of a member of pyrotechnics in the satellite structure. This research is for design, construction and calibration of a pyroshock simulator apparatus which is done with specific requirements and aims. For this purpose, in first step an experimental test is done and validation of computer simulation is obtained by using results of test. By use of computer simulation tool, new design is presented. After constructing the apparatus and... 

Deployable structures have been used on small satellites since the beginning of such space programmes. Here, the design sequence for a special tensegrity structure, for use as supporting structure for deployable mesh-like antenna will be proposed. The design process is conducted to prevent structural elements from failure, and satisfy the minimum specified natural frequency. In this research, structural modeling is performed based on two external geometric parameters (overall height and diameter), and three internal geometric parameters (elements cross-section properties). The pre-stress in structural element is the last design parameter. Also, materials are pre-assigned. Internal forces of... 

Nowadays, microgyroscopes are among the most important products of MEMS. The production of small, precise and inexpensive gyroscopes has become possible as the result of recent developments in fabrication technology. In this thesis it is intended to introduce a new method for manufacturing more precise microgyroscopes regarding manufacture facilities. Using this new method, sensitivity and resistance of microgyroscopes are increased against noises which are primarily caused by vibration and rotation about undesirable axes. The rotational movement imposed on the gyro is detected through fluid flow within its torus channel. This transformation facilitates the measurement of the initial motion.... 

In this thesis, the value-ladenness or value-neutrality of technology, new social media and as a result Instagram is investigated. It is also discussed whether values can be taken into account during the design process of technical artefacts, including new social media and Instagram, and methods are developed for this purpose. Several methods have been developed for this purpose, some of them and their compatibility with modern social media are explained; including the Value-Sensitive-Design method and the disclosive computer ethics design method. The frameworks of ethical philosophy such as virtue ethics are reviewed and the appropriate ethical framework for the analysis of new social media... 

thermoacuostic heat pump (THP) is One of the most important thermoacuostic applications which is used for heat lost recovery in industrial applications and civil applications.In this project, we have a quick review on thermoacuostic theory and researches in this field. Also a thermoacuostic heat pump in a lab scale will be designed and analyzed.For achieving this goal, first, mathematical equations of thermoacuostic systems are reviewed; a thermoacuostic heat pump is designed on the base of Tijani method and final model is validated by DeltaEC software. In the next step, after investigating about laboratory equipments which is used in testing process, we generate test matrix and study about... 

In the present study, an attempt has been made to design and develop a nano drone using the dynamics of single-wing drones. To reduce the noise associated with nano-drone motors, a unique magnetic system has been developed for the drone's propulsion system, which has technology similar to magnetic trains and uses the theory of magnetic suspension, which is one of the main innovations of this dissertation. The drone designed in this research will have a blade with a radius of 15 cm and its total weight will be 170 grams, which according to the thrust of the blade will be able to carry a load of 50 grams for 14 minutes. In this research, after the initial design of the drone and related... 

Traditionally, orbital maneuvers are obtained according to mission cost, time and several constraints. This thesis considers the use of covariance as a measure of uncertainties in the design of orbit maneuvers. The ideal solution in the proposed method is the maneuver that obtains the minimum uncertainty at the desired times in presence of the mission constraints. In this thesis two impulsive orbit maneuver schemes, based on shaping method and sequential lambert solutions, are developed and has been analyzed under uncertainties. Moreover, a novel rendezvous design methodology is proposed in order to minimize the covariace trace at the impulse locations, considering several constraints... 

This paper investigates the behavior of the Y-shaped bracing system. Because of the special type of eccentricity in this system, the behavior of the frame is strongly dependent on the geometrical changes of the braces. So that even in the elastic region, it shows the geometrically nonlinear behavior. The amount of eccentricity is very effective on the nonlinear behavior of the frame. Also the ratio of cross sections of the bracing members has a very important impact on the expected performance of the frame. The results show that this system tolerates large displacements, and can act like a base isolation system. Firstly, using a two-dimensional accurate modeling related to the geometrical... 

The project aims to design and build a device that is capable of manipulation and control of micro-scale objects in dry and fluid medium. Among all the micro-manipulation methods, the use of magnetic fields has many applications. Because it has the ability to work without direct contact and also within a specified range for living tissue, is safe. To achieve this goal,manipulation systems ever made, were studied. Then, by presenting a conceptual design and the use of appropriate dynamic models for describing the behavior of micro-robot, the system performance was simulated. After this stage, The detailed design of the closed-loop system which must controls the position of the micro-robot... 

Thermo-acoustic sience is the conversion of heat to power through the sound wave. Thermoacoustic engines for different reasons like easy making, not having moving parts and so high reliablibility of system is in attention for researchers. Also looped-tube thermoacoustic engines are very new in the world and sience and thechnology of them belong to a few companies and for different reasons are replacing different kinds of thermoacoustic engines.They have higher efficiency than other types. They can be made in large scales. They have a larger thermal range. In this research, the numerical study of one, two and four stage looped-tube thermoacoustic engines has investigated with the help of... 

This research concerns a study of the interaction between tunneling and adjacent structures. Analysis is performed using a full two-dimensional finite element model, which takes into consideration the presence of adjacent structure with regard to distance to tunnel and diameter of tunnel during construction of the tunnel. The soil behavior is assumed to be governed by an elastic perfectly-plastic constitutive relation based on Mohr-Coulomb criterion with a non-associated flow rule. The research is composed of two parts. However, compatibility of each method with beam and solid continuum element models in two dimensional finite element (FE) analysis was investigated. The first part describes... 

Mini-Refinery is a small refinery that would need less time, effort and expenses to build in comparison with current refineries but it would have less capacity of operation. This type of refineries could create the opportunity to refine materials in place and reduce overload pressure on main refineries. In addition, private companies would be able to build them easier, due to their low cost and since the desired capacity of their equipment would be lower than current refineries, more companies would be able to fabricate and sell them. This research has two main chapters to assess the possibility of building a Mini-Refinery, to produce 30000 barrel a day of LPG, Gasoline, Kerosene, Diesel and... 

Turbojet engine combustors play a key role to convert energy with very high rates. To reach this goal, the combustor must satisfy many conflicting requirements. Complexity of the flow field inside the combustormakes the 2D or 3D analysis very difficult. In this thesis, a quasi one-dimensional software is developed applying empirical and analytical 1D relations. Using data for a mini-turbojet engine, the range of some important design parameters is extracted and then a new combustor is designed using both velocity and pressure loss methods. Different disigns are investigated and are compared by employing an extended version of the simulation software. Due to the unacceptable performance... 

Oil pump is a prominent part which has been described as a vehicle heart. Any malfunction or improper design may lead to engine failure. beside engine, proper design of oil route and lubrication system of vehicle, are main factor in engine design, which provide higher efficiency with lower pressure drop. lubrication system should be able to provide required pressure and flow of oil in vast range of engine rotation speed. also minimum energy waste in higher rpm is a key factor which happens due to reverse flow from output to input of pump in the relief valve. The aim of this thesis focus on design of oil pump and lubrication system of 4 cylinder 16 valve of 1600 cc inline engine. which is... 

In this thesis, implementing parametric resonance for the purpose of improvement in sensitivity of MEMS gyroscopes is studied. Based on a parametric study on effect of each factor on the sensor’s performance, the desired values for each parameter is determined. Stability of periodic orbits is studied using Floquet Theory. In addition, three expositions are defined and proved in order to make Floquet Theory applicable for stability analysis of origin. Based on this analysis, the relation between stabilities in the system and occurrence of parametric resonance is illustrated. Due to the complexity of dynamics of a parametrically excited MEMS gyroscope, bifurcations are observed in performance... 

Stress Absorbing Membrane Interlayer (SAMI) is a slightly thin layer made of bitumen and aggregate placed between a pavement with limited cracking and overlay in order to avoid reflective cracking in overlay. SAMI’s performance depends on many factors such as pavement layer’s materials and thickness and existing pavement’s condition. Numerical simulations are powerful tools to evaluate SAMI’s performance. Previous studies showed that construction of SAMI does not necessarily reduce reflective cracking. This research investigated the effect of different parameters on SAMI’s performance using numerical simulations. The focus of this study was on the performance of SAMIs used between asphalt... 

Design and modeling of a micromechanism for generating planar, nano-scaled locomotion is the subject of this thesis. First, we introduced the concepts and fundamental definitions used throughout the thesis. Then, based on the classification of the locomotion principles employed in microrobots, the related literature about design and fabrication of different microrobots is investigated. Inertial slip generation and contact force variation, as the preferred group, is utilized for further analysis. Since friction force is the main propelling source in the microrobot’s locomotion principle, different models proposed for this phenomenon are investigated and the Coulomb friction model is selected... 

The objective of this project is to design and control a single-stage three-phase unity power factor telecom rectifier. Following a comprehensive literature review on single-stage three-phase AC-DC converters, high-frequency isolated three-switch buck rectifier is selected. In this thesis, the analysis, design, and control of isolated buck converter is based on previously developed methods for classic three-switch buck rectifier. Three-phase isolated buck+boost rectifier is introduced by integrating a boost converter to the isolated three-phase three-switch buck rectifier and modified control structure. The proposed structure is simple and has good performance for heavily unbalanced mains...