Sharif Digital Repository

In this work, we establish the constancy of expansion ratio (density factor) and adiabatic flame temperature for predicting lower explosive limits and further establish the constancy of expansion ratio for measuring upper explosion limits. Flammability limits are important characteristics of combustion processes. The flame can only propagate in a specific range of ratios of concentration of fuel to oxidant. The maximum of this concentration ratio that make possible propagation of flame in a mixture, is called upper flammability limit. The minimum of this ratio that make flame propagation possible is called lower flammability limit. Limits of flammability change with initial conditions such... 

Airports are critical connectors in the air transportation operational system. In order to meet their operational, economic and social obligations in a very volatile environment, airports need to embrace change rather than resist it. Long-term airport planning has become a complex issue due to the constant growth in air traffic demand. In this context, the thesis puts forward an innovative approach to planning and decision making for various component of airport.in this has been used fuzzy logic decision making method to develop airport in all respect in order to plan balanced growth. Top airports are successful experience in airport expansion planning which can be pattern for other airports... 

With the huge natural gas reservoir in Iran, LNG production processes have a great attraction for the gas industry. The main goal of this project is the design of a skid mounted of a small scale LNG unit. A pretreatment unit was designed which includes two adsorption towers. In these towers, the type 13X adsorbent, eliminate traces of CO, N2 and H2S. For the cryogenic side a N2 expansion cycle was considered, after studying different cycles. It is found that N2 expansion cycle is one of the best methods for mini LNG production unit. In this process N2 gas was compressed to 35 bar in two stages and after precooling, enters to an expander to produce the -165 C cold in a cold box. The natural... 

Air enterance in to flowing water is something that is commonly seen in the water conveyance systems. The mixture of Air and water that flow together create a kind of flow that is called two phase flow. This kind of flow is often seen in culverts and water conveyance systems. There are different flow patterns in two phase flow. Considering pressure fluctuation, pressure drop and pressure recovery, slug flow pattern is the most complicated pattern among all.
Sometimes a singularity is used in a tunnel; one of the singularities that are frequently used in water conveyance system is expansion transition. In this study an experimental setup is used to model two phase slug flow, which passes... 

Cosmology is a knowledge that deals with the matter of creation of the world, its current structure and its end. This scientific field that was a subject discussed by the scientific, philosophical and religious groups has nowadays taken the attention of many scientists and researchers. The philosophers of science, also, are not exemptions from theses groups and cosmology, as a topic common between philosophy and science, is one of the points that are under discussion in the field of philosophy of science. On the other hand, the religions, also, have noticed this issue. Koran that is the most complete divine book sent from God, has taken account of the creation and the Creator as the axis of... 

Emphasis on the expansion of education in Iran's development strategy and increasing demand for higher education in the 2000s required the country to develop higher educational institutes. Unprecedented growth of these institutes in the second half of 2000s was so vast that in 2008 all the counties in Iran had at least one institute. These institutes were established even in the smallest counties in order to solve the problem of transportation for its settlers, and on the other hand, developing higher education institutes in larger cities resulted in an increase in the acceptance rate of these institutes and their accessibility for the people. Moreover, lower accessibility to higher... 

The increasing variability of renewables and volatile chronological net-load in modern smart grids engenders significant operational risks of an uncertain sufficiency of flexible capacity. Assessing the operational flexibility of the grid with high penetration of renewable resources remains an issue of critical importance. Operational flexibility insufficiency may bring about two major problems: 1) there may exist no feasible solution for operation under uncertain conditions due to insufficient available flexibility capacity;2) even if the solution feasibility criterion is ensured, dispatch limitations of the flexible resources may force the system operating point to deviate from the optimal... 

In this thesis, we study optomechanics of subwavelength nanoparticles based on the Green's function formulation. First, we investigate the optical force exerted upon Rayleigh particles in the free space using the dipole approximation method. Then, we present a new method based on the Taylor expansion of the polarization field to calculate the optical forces beyond the Rayleigh regime. Subsequently, we study the optical force exerted upon Rayleigh particles in non-free spaces, and model the backaction effect using the scattering Green's function. We show that the backaction effect can modify the polarizability of the particle and thereby can affect the gradient force, radiation pressure, and...