Sharif Digital Repository

Due to pollution and destructive effects on the environment, while consuming a large amount of fossil fuels that can be converted into high value-added products, gasoline cars are gradually replaced by electric cars. Modern electric vehicles are generally designed and manufactured on the platform of gasoline vehicles. In the present study, it is tried to design three models of electric vehicles based on the SAINA vehicle. Initially, for the first model, an electric motor instead of the SAINA gasoline engine is employed to provide the power required for the vehicle. Then, for the second model, two electric motors are used namely one in the rear axle and one in the front. The third model uses... 

The current state of restructuring in the electric power industry has forced power companies to maintain and enhance service reliability and quality while controlling associated costs. Therefore these companies often seek to improve operational performance, increase productivity and promote management of their assets to restrain production costs while satisfying customers’ needs. Maintenance of system components has great impacts on both service quality and also system costs. However, it has been proved that traditional maintenance strategies which have been implemented in electrical companies are inefficient. Thus, Managing maintenance procedures would help companies to reduce their costs... 

The current restructuring trend in power industry emplaces the owners and managers under a great pressure to not only reduce the associated investment costs, but also reasonably cut the operation and maintenance expenses as much as possible, while keeping both the power quality and reliability requirements met. Reliability-Centered Maintenance (RCM) has been proved to be in response to this dilemma in power systems since it has been yet successfully applied in various engineering contexts worldwide. This process is more challenging when it comes to the power transmission systems because of its bulkiness and complex structure. On the other hand, market involvement and its intricate behavior... 

One of the main and challenging stages in the development of hybrid vehicles (HEVs) is the conceptual design of its powertrain, which includes two parts: architecture design and sizing. This research aims to introduce a novel framework for conceptual design of HEV powertrains. By using this framework, not only the sizing of components is optimized but also the optimal architecture of powertrain is selected. In the proposed framework, by finding the optimal values of the powertrain design variables, including type of architecture and sizing variables (such as nominal powers, nominal torques, conversion ratios, etc.), the performance and the cost of hybrid vehicle is optimized in three layers... 

Nowadays, industrial companies deal with a wide range of serious problems in the field of power transmission maintenance and also fault detection. A large amount of money and time is spent on these issues in order to solve them; consequently, there is an essential need for this subject. In this thesis, in order to tackle those major issues which were referred above, an artificial neural network is trained with only one hidden layer. Also, a suitable database for training an efficient neural network is needed. Thus, a one-stage gearbox system with appropriate degrees of freedom is used to set up referred database. In this system, a crack is imposed to a tooth of spur gear with different sizes... 

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... 

Renewable energy resources, e.g. wind, solar and geothermal, experience rapid progresses in electric power industry all over the world. So, it becomes essential that these free-emission electrical energy resources be integrated in the existing generating capacity planning procedures. On the other hand, the uncertain and intermittent nature of these energies has led to some problems in their integration in power systems. The reserve requirement in a renewable-based power system is a main challenge, which has to be addressed properly. In this way, this research presents an analytical approach, based on the modified PJM method, to quantify the risk of renewable energies commitment during the... 

The purpose of this study is to establish a lateral-torsional-axial dynamic model for spur and helical geared rotor systems subject to shaft bow manufacturing error. Timoshinko shaft element, elastic bearings and rigid disks used to simulate different element in the model. Tooth contacts is modeled with linear spring and damper along the pressure line.Results show that the vibration pattern of the unbalanced load and shaft bow effect is different. These obtained patterns might help with the fault diagnostics of rotating machinery. The vibration will be lowest if the unbalanced load and the shaft bow amplitude locates out of phase. The previous researches show that different pattern of the...