Sharif Digital Repository

A novel semi active control system for eleven Degrees of Freedom passenger car's suspension system using Magneto rheological damper is presented. The considered suspension system is modeled using mass spring damper model. The semi active vibration control is designed to reduce the amplitude of vehicle's vibration due to by road profile. The applied control strategies are based on a Linear Quadratic Gaussian optimal control algorithm to obtain desired damping forces of MR dampers. In considered system, the damping coefficient of the shock absorber changes actively through inducing magnetic field. The necessary input voltage to MR dampers to generate desired damping forces are derived using... 

In this paper the effect of simultaneous operation of the automotive radiator, fan, engine, and cooler system on radiator coolant inlet temperature is studied. For this purpose, an analytical model is developed to simulate the automotive cooling system. First, the heat transfer rate and air pressure drop in radiators with louvered corrugated fins and flat tubes are modeled and compared with wind tunnel test results over six radiator cores. Also, the air flow path is simulated. Two preexisting codes are used to simulate the automotive engine and cooler system. Then a code is developed in order to investigate the effect of different parameters related to each component of the cooling system on... 

The compound axle is a space saving suspension component that is relatively inexpensive and easy to install. Therefore it is used in rear suspension system of most front wheel drive passenger cars. This article present an optimum design algorithm for this component. A typical cross section for this the torsion beam of the axle is selected as a basis design. Using finite element methods, kinematics and elasto-kinematics behaviors of the section in vehicle normal maneuvers have been calculated. The acquired dynamic characteristics of the member was entered into a dynamic simulation program and the effect of geometrical parameters of torsion beam on the vehicle handling was studied. Using DOE... 

There are many reported researches considering movement behavior of vehicles. In these studies the two basic types of movement of a vehicle are longitudinal movement, car following, and lateral movement, lane changing. Dependency between car following and lane changing models and the fact that many of drivers does not consider driving lanes, necessitate developing of models that combine the car following and lane changing without considering the driving lanes. Utilizing computer simulation, the work can also be applied to conditions where lane disciplines are strictly observed. Microscopic simulation models considering the movement of individual vehicles in a traffic stream can be... 

This paper presents a biomechanical model with seven degrees of freedom as a seated human exposed to vertical vibration. Experimental data is used to find the stiffness and damping parameters of the model. The data includes values of seat to head transmissibility, driving point mechanical impedance and apparent mass. The multi-objective function is used to obtain theoretical results similar to three different experimental cases. The unknown coefficients are calculated by a genetic algorithm. Improved results, in comparison with previous models, are achieved from the presented model. Next, this modified model is assembled on a quarter car and parameters of the cushion and the suspension... 

In spite of the recent steady increase of the volume of the second-hand markets, often customers remain in doubt regarding the quality and durability of the secondhand products. Aiming to reduce and share this uncertainty, dealers offer warranty on their products. Offering warranty for second-hand products is a relatively new marketing strategy employed by dealers of used electronic equipment, furniture, automobiles, etc. Usually, for used products, the dealer's expected warranty cost is a function of product reliability, past age and usage, servicing strategy and conditions and terms of the warranty policy/contract. Sometimes the offered policy is limited by two parameters, typically the... 

The need for service passenger cars, like taxies and governmental vehicles, to work in central Tehran that can produce less emission has been the main drive behind this research. A series hybrid pneumatic vehicle based on Iran manufactured Samand Passenger car was developed using commercially available components. The idea is to use as much standard parts as possible to reduce the development and manufacturing costs of the developed hybrid car. The vehicle space and weight limitations and the fixed geometry have been the main constraint in adoption of the components. The calculations show that the designed vehicle succeeds to satisfy the requirements set by driving cycle, but requires... 

Development of hybrid cars is the most popular subject among automotive engineers both in production and research. The need for service passenger cars, like taxies and governmental vehicles, to work in central Tehran that produce less emission has been the main drive behind this paper. A parallel hybrid pneumatic vehicle based on Iran manufactured Samand passenger car was developed using commercially available components. The idea is to use as many standard components as possible to reduce development and manufacturing costs. The vehicle space and weight limitations and fixed geometry have been the main constraint in adoption of the components. In this design the 75 kW engine of the Samand... 

Today condition monitoring using vibration analysis is not only used for simple proposes like bearings and gears fault detection but also it is used in hybrid motors and cars in automobile industry for detecting or anticipating faults. The main aim of this paper is using vibration analysis in automobile industry to detect and categorize faults appeared due to poppet valve clearance and incomplete combustion sometimes called misfiring phenomenon in internal combustion engine. So we used four accelerometers on OHV engine body for registering vibration signals. Then using PCA technique acquiring data were investigated. At the end we succeeded to classify and detect faults with a high ratio of... 

A novel semi-active control system for suspension systems of passenger car using Magnetorheological (MR) damper is introduced. The suspension system is considered as a mass-spring model with an eight-degrees-of-freedom, a passive damper and an active damper. The semi-active vibration control is designed to reduce the amplitude of automotive vibration caused by the alteration of road profile. The control mechanism is designed based on the optimal control algorithm, Linear Quadratic Regulator (LQR). In this system, the damping coefficient of the shock absorber changes actively trough inducing magnetic field. It is observed that utilizing the present control algorithm may significantly reduce... 

In this paper a three-dimensional steady state incompressible turbulent air flow is considered in a large single room. The buoyancy affected turbulent air flow is simulated by solving governing equations numerically. The turbulence modeling includes both k - ε and zero-equation models and their results are compared to the experimental data. The paper reviews several aspects such as displacement of radiator system performance, temperature and flow field distribution and comfort. The results show that the best temperature distribution and comfort obtain when radiator is installed under the window and its height be equal to or greater than that of the window. Copyright © 2006 by ASME  

This article presents the research results on production and performance of palladium-only catalytic converters. Monolith is used as catalyst carrier and gamma alumina as substrate. Dipping method is used for monolith washcoating. Palladium as the active metal is impregnated on gamma alumina using wet impregnation to produce catalyst samples. The effects of factors such as percent solid in slurry, milling time, calcination time and temperature, pH and existence of Al(NO3)3 on wash-coat characteristics were studied experimentally. SEM, XRD, and BET tests were carried out on the samples. Catalyst performance was tested in an experimental reactor that was designed for this research. The results... 

This paper presents a feature-based license plate localization algorithm that copes with multi-object problem in different image capturing conditions. The proposed algorithm is robust against illumination, shadow, scale, rotation, and weather condition. It extracts license plate candidates using edge statistics and morphological operations and removes the incorrect candidates according to the determined features of license plates. We have formed a rather complete database of 269 images in different conditions. The proposed algorithm successfully detecteds the accurate location of the license plates in 96.5% cases, which outperforms the other available approaches in the literature. © 2006... 

Real-time, fuzzy rule-based guidance systems for autonomous vehicles on limited-access highways are investigated. The goal of these systems is to plan trajectories that are safe, while satisfying the driver's requests based on stochastic information about the vehicle's state and the surrounding traffic. This paper presented a new method to implement an automated highway driving behaviour. The main advantage of the suggested system is its well-defined structure. To test the designed system, a simulation tool is implemented. By using the described tool, we can analyse the operation of the implemented decision making system in a simulated highway. Results show an acceptable performance of the... 

Magneto-rheological (MR) fluids consist of magnetic particles in carrying fluid. One of the drawbacks in using MR dampers in laboratory work is their price. At present, there is a compelling need for the production of the laboratory scale of MR fluids to lower their production cost. In this study, to show that the MR fluid is an applicable prototyped laboratory scale of single ended and mono-tube, MR dampers with a prototyped MR fluid are presented. The main features of produced MR fluid and dampers are simplifying in constructing and their low cost. These dampers are useful for laboratory research work. To illustrate the validity of the MR fluids, using this fluid, four MR dampers are made...