Sharif Digital Repository

In the past years a lot of research has been done on effects of different parameters on dynamic behavior of soils. According to these studies, principal stress direction rotation and intermediate principal stress coefficient have a major effect on monotonic behavior of soils, but more studies needed for observingtheir effect on dynamic behavior of soils.
In recent study undrained isotropic consolidated specimens of dense Babolsar sand subjected to α changes using dynamic hollow cylinder apparatus and the inner and outer cell pressure kept constant so that b was relative to α changes.
Fisrt series of testswere done to find an appropriate value for induced cyclic deviator stress. The... 

First, we peruse the intraction between a quantized light and a two level atom which has been described by Janes-Cummings-Paul Hamiltonian. By solving Heisenberg equations in Fourier space and describing electric field by a generalized-transverse Green function, we obtain spectral density for a quantum dot which is in the strong coupling to a slab photonic crystal cavity. Afterward, by solving Shrouding equations precisely we demonstrate when quantum dot is in a very strong coupling to cavity, rotate wave approximation is not reliable anymore. It means that if coupling constant gets comparable to cavity mode frequency then the prevalent approach to solve this Hamiltonian will not be correct.... 

In this project, we were intended to study the ultra-strong coupling in optical waveguides. Hence, we analyze the interaction of an electromagnetic wave with a quantum well embedded in a dielectric slab waveguide. First, we designed a QW with and alloys, which the energy of its electron-heavy holes transition is . By exploiting the envelope function approximation, we derived the wavefunction of electrons and holes, their eigen-energies, and the dipole moment of electon-holes. For finding the wavefunction of holes and their eigen-energies, we used the Luttinger Hamiltonian. Next, we calculated the electrical susceptibility of a three level quantum system (as a model for QW), by using... 

Cavity Quantum Electro-Dynamics (CQED) in Weak, Strong and Ultra-Strong coupling Regimes are studied. A MATLAB m-file is written which is able to solve any arbitrary CQED configuration. This program demands input data such as number of Quantum Dots, number of energy levels of each Quantum Dot, energies of each energy level of Quantum Dots, Number of cavity modes, eign-frequency of each cavity mode, coupling constant, dipole strength of each allowed transition of Quantum Dots and initial state of system from user and begins to solve the Schrodinger equation for annihilation and atomic ladder operators. In addition, coefficients of each possible ket will be calculated. Since, any approximation... 

Thin Walled Beams are widely used in engineering applications with the minimum weight design criteria, ranging from civil to aerospace and many other industrial fields. The weight reduction of the beam leads to importance of the dynamic behavior of the structure. Frequently used thin walled beams have low torsional stiffness and their torsional deformations may be of such magnitudes that it is not adequate to treat the angles of cross section rotation as small. When the vibration amplitudes are moderate or large, the geometric nonlinearity must be included and some new phenomena which do not exist in linear torsional dynamic come into play. Unfortunately, the equations of motion of nonlinear... 

In the recent years, photonic crystal (PhC) devices vastly have been paid attention due to their ignorable loss, very low group velocity, flexibility in shape and dimension.In this thesis a PhC coupled cavity ring known as superresonator is introduced and its properties and applications is studied. Also modes of the structure are extracted through both coupled-resonator model and FDTD method, and two of its application is described and studied. Add-drop filter is one of the essential devices in WDM systems. First, an application of superresonator in designing add-drop filters is explained and a novel filter based on the superresonator is introduced and analyzed by FDTD and coupled mode... 

Wound is a defect or failure in the skin texture which occurs as a result of physical or heat injuries or physiological conditions. The wound dress as a temporary cover can improve wound healing process and due to the unique properties, hydrogels have become appropriate choice for this application. Hydrogel’s structure allows drug to be loaded in the wound dress. Hydrogel wound dress should have adequate fluidity to cover wound’s bed and make full contact with the skin. Sufficient cohesion and strength is also necessary to allow the wound dress to remove from wound completely. Therefore, the study on the viscoelastic properties of hydrogel is important. In this study, polyvinyl alcohol... 

In industry it is usual to develop a family of similar software instead of a single one. Software product-line (SPL) engineering or family-based software engineering is an approach that tries to minimize needed effort and time-to-market and maximize quality of manufactured products through strategic planning for maximizing reuse among members of the family. On the other hand it is known that testing software is an indivisible part of software development process which requires considerable time and effort. With large number of products created from an SPL, it is obvious that testing should be conducted in such a way that needed effort does not maintain a linear relationship with number of... 

The gradual depletion of the resources of fossil fuels, as well as the instability of their price in addition to the necessity of mitigation of hazardous air pollutants, are the chief reasons to increase the use of renewable sources. Biodiesel, as one of the best alternatives, can mitigate the emission of air pollutants resulting from fuel combustion. However, using raw biodiesel is not economically viable due to its lower quality in comparison with diesel. In this study, the role of nanoparticles in the improvement of biodiesel characteristics has been investigated. Firstly, biodiesel was produced from waste cooking oil (WCO) using the transesterification reaction, and then ceria and... 

Ultrasonic metal welding is a solid state welding process and is widely used in welding the connections of lithium-ion battery batteries in hybrid and plug-in hybrid vehicles. This welding process has advantages over fusion welding processes such as; Shorter time, no heat affected area, optimal energy consumption, cheaper equipment and no harm to the environment. The aim of this study was to investigate the effect and optimization of time, normal pressure and oscillation amplitude parameters in order to achieve the maximum tensile-shear test force and T-peel test in the dissimilar welding of 1050 aluminum and copper (purity above 99.9%). In order to achieve the optimal state of welding...