Sharif Digital Repository

Railroads should be well maintained for safe and efficient operation. The most important reason for the failure of railways is overload and asymmetric load on them. Also, the proper interval for repairs should be adjusted to fit the load crossed over. In order to carry out all these tasks, a constant observation of the weight on the rails must take place. Current dynamic weighing systems are costly. In addition, the installation of these systems is time-consuming and causes permanent damage to the rails. On the other hand, some of the cheaper models of weighing systems require full stop and static weighing, which practically does not work at all, especially on busy rails due to delays. The... 

For over a hundred years, vehicles have entered the human environment and influenced it. One of the most important effects that vehicles have on their surroundings and humans is their acoustic noise. The gearbox is one of the important components of the vehicle's transmission chain, in which the gears interact with each other and cause to create noise and vibration. These vibrations are transmitted through the bearings to the gearbox casing and then transferred to other parts of the vehicle via gearbox supports. Many researchers have studied the factors of NVH production in gearboxes and used methods such as gear profile modification and optimization of shaft and casing to reduce NVH. This... 

Gearbox is one of the important components of power transmission chain in the car which the engagement of the gears inside it causes noise. The following thesis, is in line with the project that was defined as "NVH reduction of the Tiba X200 gearbox" and to increase the correlation between university and industry, the aim of which was to improve all the noise sources in the mentioned vehicle. The purpose of this project is to reduce the noise of the gearbox shell by using reinforcing blades called ribs. For this purpose, first the desired changes were made in Solidworks software on the 3D model of the gearbox shell, and then the finite element model of the gearbox shell was prepared in... 

Diabete is disability in the body to produce insulin or use it. Body insulin hormone needed to convert starch, sugar and other foods to energy and thus the body is functioning properly. Considering this incurable disease and its complications, many doctors and researchers trying to control the disease, reduce complications and to create favorable conditions and appropriate solutions for preventing its expanding and also strengthening patients mentally. Be destroyed in digestive system, insulin can not through tablets or similar cases received. The best way known to enter insulin to the body, is injection. This project is about a device to reduce the level of blood glucose in patients with... 

Fatigue life and crack growth retardation due to periodic tensile overload that superposed on constant amplitude cycles has been investigated. The tests were performed using C(T) specimens made of 7075 aluminium. All periodic overload tests were carried out at the same spacing between overloads and the effect of overload ratio on fatigue life has been investigated. Results of experiments revealed that the at low and high overload ratios, crack growth rate is relatively high and there is an optimum OLR that maximize interaction and thus minimize FCGR. Whit OCR-1=50, overload ratio of 1.85 led to maximum interaction and resulted in 219% increase in specimen's life relative to CA loading. Also... 

In recent decades, emission from automobiles is considered one of the main reasons for global warming. One of the ways to decrease the fuel consumption of the vehicle, increase the power train efficiency and vehicle acceleration is to use Continuously Variable Transmission (CVT) and infinitely variable transmission (IVT). Previous inquiries include investigate miscellaneous types of continuously variable transmissions and their efficiency and different ways of combination of CVT and other power trains in order to create an IVT. The aim of this research is to optimize one kind of IVT transmission. At first, different state of combination of IVT portions will be investigated. Then, a model is... 

In this research, the effect of variable stiffness and damping, in suspension system, on car performance was studied. The optimization of car performance was obtained by minimization of an objective function including the body acceleration, suspension travel and tire deflection. Firstly, considering the stochastic input for a quarter car model, minimization of the objective function was done by changing the stiffness and damping coefficients in the frequency domain. The Linear Quadratic Regulator (LQR) method was implemented to minimize the objective function. In order to supply the active force obtained by optimization, different semi-active designs, in which stiffness and damping were... 

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... 

In recent years passenger cars have been known as the main source of air pollution in urban areas. Despite all the research and efforts in minimizing the fuel consumption and emissions of internal combustion engines (ICE), this is merely a temporary solution. The permanent solution to overcome these disavantages is the use of electric vehicles (EV). The main downside of using electric vehicles is their short driving range. Multi-speed transmissions can be adopted to overcome this problem. Continuously variable transmissions (CVT) and infinitely variable transmissions (IVT) have been proven to enhance fuel economy in ICE vehicles and a great deal of research is being conducted to maximize... 

In this research the vibration of rotating and non-rotating shells was investigated. In the non-rotating shells field, the vibration of joined cylindrical shells and joined conical shells that each sections of them has independent material, thickness, length and angle were investigated. By analyzing the free vibration of joined conical shells, we can perform the free vibration analysis on every complex thin-walled geometry.In the rotating shells field, first the governing equations of the rotating conical shells are derived and then, the vibration of rotating cylindrical-conical shells and joined conical shells were investigated. The governing equations of rotating conical shells and... 

Modern science and technology’s desire is increasing for Control Algorithms Testing Instruments which allow testing autonomics due to advancement in robotic science and increased application for autonomics. In this Thesis, a manufactured tester is equipped with sensors to allow data acquisition and Control algorithms tests for RC helicopters, which are a variety of autonomics. For this purpose; a manufactured 3-DOF tester was used and for control application purposes one degree of freedom was added and it was made to 4-DOF. Also, Mechanical defections which cause vibration resonance failing was solved. In the end, a data acquisition system with an appropriate rate for signal gathering and... 

Recently lots of studies have been done on driving cycles and parameters affecting pollutants emission and fuel consumption. Due to changes of driving behavior and traffic situations, it’s necessary to update driving cycle of a city to obtain more accurate simulation and analysis results. In this project, first of all driving cycle of Tehran city is developed using three different methods. These methods include choosing representative microtrips from specified traffic situations, clustering and choosing representative microtrips from all available data. Results show that using clustering method is more accuarate and parameters of the cycle developed using this method is closer to measured... 

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... 

Pyrotechnic devices are widely used by the aerospace and defense industries and consist of a broad family ofsophisticated devices using self-contained energy sourcessuch as explosives and/or pyrotechnic compositions.Pyrotechnic shock, or pyroshock, is the transient oscillatoryresponse of a structure to loading (high frequency, highmagnitude stress waves) induced by the detonation ofpyrotechnic devices incorporated into or attached to thestructure.Pyroshock Test is one of importantenvironmental tests in satellite design process. Pyroshock is one of loads that exerted on spacecraft and it's subsystems during launch process. Pyroshock can cause failure in some subsystems like sensitive... 

One of the robots that has become more important recently is radio control helicopters. According to the intrinsic unstability of these helicopters and possibility of crash with the surroundings, it is needed to have a device which the helicopter can be fixed to so the ability of motion is reduced and a safer flight is achieved. In the recent applications of these helicopters, the autonomous flight ability of these devices is more noticed; and a lot of controllers are proposed to achieve this goal. It is obvious that these controllers are needed to be tested; and benchmarking a controller in the software simulation environment is not reliable; so a test stand is needed.
In this project a... 

The goal of using speed humps is to reduce the velocity of cars to allowable value. Reducing the speed more than necessary before arriving at the hump, causes losing kinetic energy whose compensation needs consuming more fuel. In fact, the total fuel consumption of vehicles is noticeable and it expresses the need for allowable speed definition to prevent wasting fuel. In this project, using different methods in engineering design and by defining allowable speed, an intelligent speed hump is designed and selected from different patterns which may remain protuberant or become like the road surface in level. The parts considered for this hump are selected simple to lower the cost of... 

Millions of people are exposed to noise every day in their work and life, and their physical and mental health is at risk due to this issue. Hence, the issue of noise and vibration has become an important factor in car quality. One of the sources of noise and vibration in the vehicle is the engine. The engine is the heart of the car and its most important part. Therefore, reducing Engine noise can have a significant effect on the noise emitted by the vehicle. Engine noise can be divided into three categories: 1 - combustion noise 2 - mechanical noise 3 - aerodynamic noise. This project is in line with a project defined between the university and industry aimed at improving all sources of... 

In this research, the mechanical section of a reduced-scale hybrid vehicle simulator was designed and fabricated. In order to scale down the vehicle dynamics, a method based on dimensional analysis was proposed. An internal combustion engine and an electric motor were selected as power sources and then, scaling was performed, according to the specifications of the combustion engine. Afterwards, the power transmission system was designed first in concept and then in more detail. Finally, the design was manufactured and assembled. The study was made in conjunction with another study responsible for the controlling section of the work, conducted by Safabakhsh The sponsor of these two researches...