Sharif Digital Repository

One effective way to reduce air pollution created by automobiles is to tax/toll the unfavorable characteristics of the automobiles. This study is an extension of the current literature on taxing visible and measurable aspects of automobile ownership and use, namely engine size, age, fuel used, and technology level. A three sided model, comprising the operator (government), consumers, and automobile producers, has been constructed to control emission by proper taxation. Engine size tax is one-time, age-tax is yearly, and fuel use is usage-based. The model has been built and experimented based on a sample population and the results have been shown to be in the direction of the management... 

Fuel cells convert the chemical energy of hydrogen and oxygen directly into the electricity. Their high efficiency and low emissions have made them a prime candidate for powering the next generation electric vehicles. Polymer electrolyte membrane is a key component of the PEM fuel cells. One of the critical problems to overcome in some PEM fuel cells is the water management because If there is not enough water, the membrane becomes dehydrated which leads to a rapid increase in ohmic resistance. On the other hand, if too much water is present, flooding may occur resulting in the pores of the gas diffusion filled by water and the available passage for reactant gases is decreased. In this work... 

In this project, 13 C nuclear magnetic shielding constants and also hindered internal rotation about C-N bond in compound 4 -(phenylacetyle) morpholine are investigated The Factorial Design method was used to obtain the best solution for chemical shift computations and comparison made out in two levels (HF and B 3 LYP). Consequently the (B 3 LYP) method own better data. 13 C NMR Spectra were taken at variable temperature ,and then with simulation of bandshape broadening pattern at coalescence region ,rate constants of exchange were obtained for all temperatures. For simulation of line-shape broadening Spinworks software was used, that with two interfaces made possible simulation with two... 

The present thesis deals with the effect of matrix shear deformation on energy released due to debonding at fiber/matrix interface during fiber pull out test, which is modeled using two concentric cylinders representing fiber and matrix. Tensile on fiber causes a shear stress at the interface. When this stress exceeds the tensile strength of the interface, debonding occurs at the interface and grows as a crack along the interface. This debonding causes a relative axial displacement between fiber and matrix along the debonded interface, which varies along the debond crack. How fiber/matrix relative displacement changes along the debond region is not known. Thus, the fiber/matrix interface is...