Sharif Digital Repository

Applying of seismic waves and analysing of its reflections is of effective ways in exploration of the internal structur of the Earth. In this method the Earth is considered as a elastic body that seismic waves are propagated in it. In this thesis the how of creation and propagation of seismic waves is modeld at first and then the inverse problem, exploration of the internal structure of the Earth from observed data, is considered  

Dealing with natural and handmade radioactive materials and sources is of major aspects of nuclear science and technology. Useful applications of these materials and sources in different fields, such as energy production and health physics, caused the necessity of developing the detection and radiation protection methods. Each of these methods uses different equipment and approaches which are based on different kinds of radiations and radioactive sources. Despite the given ability of radiation detection, in some cases, recognition, distinguish, and estimation of a source radiation level is impossible due to bad effects of these equipment on measured spectrum. Detection of neutron spectrum in... 

One of the important experiments on satellites and their components is testing of their resistance to shock wave known to pyroshock. Pyroshock is transient response of a structure to a high frequency and high acceleration shock wave that is created by the action of a member of pyrotechnics in the satellite structure. This research is for design, construction and calibration of a pyroshock simulator apparatus which is done with specific requirements and aims. For this purpose, in first step an experimental test is done and validation of computer simulation is obtained by using results of test. By use of computer simulation tool, new design is presented. After constructing the apparatus and... 

The success of oil recovery depends, among other factors, on the ability to provide reliable simulations of the reservoir performance. The reservoir dynamics are usually modeled by a distributed parameter dynamic system whose parameters represent the petrophysical properties of the reservoir. A proper characterization of those reservoir properties is fundamental for an accurate reservoir simulation. The petrophysical properties are highly heterogeneous and only a limited number of measurements are available at certain locations in the reservoir. Therefor, in ordet to obtain accurate prediction of the reservoir performance, it is essential to possess reliable estimates of the petrophysical... 

Motivated by the Karush-Kuhn-Tucker optimality conditions for a sort of quadratic programs, we first discuss a class of nonlinear complementarity problems (NCPs). Then, we explain a kind of inverse problems of the NCP for a given feasible decision , and we characterize the set of parameter values for which there exists a point such that ( , ) forms a solution of the NCP and require the parameter values to be adjusted as little as possible. This leads to an inverse optimization problem. In particular, under , and Frobenius norms as well as affine maps, we discuss three simple and efficient solution methods recently introduced in the literature, for the inverse NCPs. Finally, some... 

Today, the various medical imaging methods have had a wide development in achieving lower cost, lower volume, higher safety, higher quality and being more noninvasive. Compared with the other existing methods, Electrical Impedance Tomography (EIT) can solely meet the first three objectives. Although there have been some presented methods with significant progress, this method has still much lower quality than the other methods (like magnetic resonance imaging or X-ray imaging). In EIT, via the injection of an electrical current (in frequencies between 1-100 kHz and the amplitude between 1-5 mA) and the measurement of the voltage induced in the border areas of the body, a map of the internal... 

Rotating machinery are found in most industrial units, that are highly susceptible to transverse cross sectional cracks due to fatigue. The vibration pattern of a rotor system reflects the mechanical parameter changes in the system. These vibrations can be used for identifying the cracks and appropriate actions can be taken to prevent more damage to the system. The dynamic behavior of cracked rotor is a subject of considerable current interest. Several researchers have developed models of cracked rotor systems. Therefore, In this thesis, the influence of the presence of transverse cracks in a simple Jeffcott rotor is analyzed. In first, on the basis of fracture mechanics, the direct and...