Sharif Digital Repository

This thesis discusses design and, simulation procedure of a mono-injector combustion chamber, in order to study and, analyze the ignition and, stable combustion characteristics, for Kerosene and, liquid Oxygen cryogenic propellants. Accordingly, the design and, simulation for the combustion chamber, for Kerosene and, liquid Oxygen propellants is performed. Also, effective parameters on the flame taking place are studied, and finally an algorithm for design and, properties study of cryogenic propellant ignition is presented  

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... 

In this thesis, we consider design, modeling, and analysis of a single-phase Brushless Doubly-Fed Machine (BDFM). Generally, this type of machine is called the Brushless Doubly-Fed Induction Machine (BDFIM), that is a new class of induction machines. BDFM is a type of AC machines that requires two alternative power sources. One of the stators windings, called Power Winding, is connected to the network grid and the other one, which is called Control Winding, is connected via a converter, which is in the order of one-third of the nominal power of the machine, to the grid. Like the other types of induction machines, BDFM can also work as a generator or motor. The important criteria of this... 

Today, as an effective tool for marine applications, towed submarines play an im-portant role in various sectors of the marine industry, including defense, recreation, ocean exploration, etc. The high cost of existing thrust systems, as well as the signifi-cant vibrations in them, run counter to the goal of designing this small, low-cost sub-marine. Therefore, the decision was made to design this vessel with a tensile thrust system. In this project, an attempt is made to introduce and design the structure of the body and the carrying capacity of the passenger by a recreational submarine with the ability to move 10 people as passengers And while introducing the structure of the body shape and... 

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... 

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... 

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... 

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... 

Cascade impactors are the instruments which are used to assess the particle size distribution and the cut off diameter. Cascade impactors are wildly used for hygiene purposes, environmental, and toxicological studies. However, to find out the accurate size distribution, the cut off diameter of each stage which is different for different types of impactors with different geometry specifications should be determined. In this study first the basis of the cascade impactor operation is described. Next, different types of cascade impactors are introduced, and the Andersen Cascade Impactor (ACI) is chosen to design. The design criteria are explained and the dimension of each stage, entrance cone,... 

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.... 

Exoskeleton is a wearable active device used to augment human power in upper or lower extremities. The integration of robotic devices and conventional physiotherapy is becoming more and more acceptable worldwide. The main scope of this thesis is to design and develop a prototype of a light, low-cost and wearable robotic exoskeleton to rehabilitate the upper extremity in stroke patients at home. For this purpose mechanism of a wearable exoskeleton will be proposed compatible with upper extremity degrees of freedoms with minimum number of actuators which is constructed inexpensively to eliminate the demand of expensive and professional therapists. The conceptual design of such a system should... 

Biopotential sensors are used in a wide range of biomedical applications. For example, measuring electric potentials on the surface of living tissues in electroencephalography (EEG), electromyography (EMG), and electrocardiography (ECG) systems in which the brain, muscle, and heart activities respectively are measured over time. Moreover, these electrodes are used in measuring the pH of different materials and also in receiving and recording the electric field changes of the environment. The major purpose of biopotential electrodes is to act as a transducer between the ionic transport of the tissue and the electron flow in the electrode. Such a transduction takes place due to an oxidation or... 

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... 

One of the major concerns in the use of light flying objects is propulsion for cruise and take off from land. Creating propulsion force is important in such way that no excessive weight is introduced, especially in case of UAVs. A common trend for propulsion in light flying objects is using propellers. Propellers are commonly driven by an external motive force and due to this force and their geometry, they convert energy from this motive force into the momentum of fluid in which they are immersed as a result a lift force is generated.In the present work, trend of propeller design with optimum performance is introduced with use of vortex theory, optimum energy loss condition or Betz condition... 

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... 

Considering the advantages of optical communications and code division multiple access technique, Optical Code Division Multiple Access Networks (OCDMANs) was introduced. Thence, many researchers have suggested methods for creating Quality of Service (QoS) differentiated classes in OCDMANs. In this thesis, we have comprehensive review on the QoS assignment methods and enhance them by offering new techniques. In physical layer, we concentrate on variable chip rate OCDMANs and in MAC sub-layer, a new algorithm named Adaptive Level Control (ALC) is introduced. Then, we focus on the physical design of OCDMANs. Firstly, we solve the problem of one-class OCDMAN and introduce few simple and... 

Smoke must be exhausted, as the first action, in probable fire in subways, underground transportation systems and mines in order to survive people exposed to it. To achieving this purpose, the axial fan should be used to move the smoke to the exit lines. These fans should be had same performances in suction and discharge directions (main and reverse directions). This means flow rate should be the same at main and reverse directions. Therefore, fully reversible axial flow fans should be used in emergency ventilations. The fully reversible axial flow fans have same efficiencies in suction and discharge directions. The symmetric profiles should be used in manufacturing of the blades of these... 

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... 

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... 

Pyroshock Test is one of important environment tests in satellite design process.pyroshock or pyrotechnic shock is one of loads that exerted on spacecraft and it's subsystems during launch process. pyroshock can cause failure in some subsystems like sensitive electronic parts, solar cells and so on. For this reason it's necessary to make sure about strength of component under pyroshock which can be done by pyroshock simulator.The purpose of this research is to design a pyroshock simulator that can simulate a pyroshock with given SRS (Shock Response Spectrum) for satellite components.Requirements and constraints for design have been defined such as test item dimensions,weight range and also...