Sharif Digital Repository

Nowadays a lot of people from all around the world travel by inter-city trains and this phenomenon is the direct result of the fact that this travel mode is more affordable and relatively comfortable in comparison to other modes. Furthermore, recent developments such as the emergence of high-speed rail lines have made rail transportation able to compete with other means of transportation such as airplanes. Therefore, the practice of maximizing train networks’ resilience against probable disruptions has drawn significant attention to itself. This study introduces a novel methodology in which train network resilience can be maximized through three stages. In the first stage, the critical nodes... 

The purpose of this research is the aerodynamic design of a 100 kW transonic ducted fan. Today, the aviation industry is moving towards the design of electric driven aircraft propulsion. Transonic ducted fans are one of the viable options that have been used in medium and heavy aircrafts due to their high specific power. In this research, the meanline model has been used for the initial design. By applying the design constraints, design limitations, design and functional parameters, the initial design point is found and then a sensitivity analysis is performed with respect to the effective design parameters to obtain the optimal design point. For the initial design of the transonic ducted... 

Inlet air cooling is a simple and economical method to increase the power output of gas turbines. High-pressure fogging systems and mechanical chillers are two common methods. High water consumption, damage to compressor blades by water droplets, and inefficiency in humid climates are disadvantages of high-pressure fogging systems. Mechanical chillers have high electricity consumption and initial costs. In this research, an earth-to-air heat exchanger (EAHE) is introduced as a new method for inlet air cooling of gas turbines and is technically and economically compared with the two common methods in the long term in the climate of Tehran city. Temperature distribution in the ground is... 

Carbon dioxide is one of the main geenhouse gases emitted from factories as well as transportation vehicles that adversely affect the atmosphere and cause global warming. Among the proposed solutions to reduce carbon dioxide in the atmosphere, carbon dioxide separation would be the most viable medium-term approach. However, the high cost of carbon dioxide separation prevents the development of carbon dioxide absorption technologies. Therefore, it seems that integrating separation and production processes is the most efficient way to save energy and reduce carbon emissions. This method decrease a high proportion of the energy consumption in upstream operations (carbon dioxide removal,... 

One way to increase the efficiency and improve the performance of a gas turbine is to increase the inlet gas temperature. On the other hand, the inlet temperature has an allowable operating range, and increasing it beyond the tolerance of the alloys used in turbine blades causes structural defects and significantly reduces the blade life. Therefore, to increase the blade life, various cooling methods such as internal and layer cooling are used. Considering the blade geometry and cooling paths, accuracy in the manufacturing process is doubly important in the production of these blades. The importance of this issue is that if the cooling channels produced are inconsistent with the design...