Sharif Digital Repository

Concentrated photovoltaic systems (CPVs) allow simultaneous production of electrical energy and high-temperature thermal energy. These systems consist of a concentrator for collecting solar rays onto the surface of the recipient cells. Moreover, these systems are always facing the sun using a sun tracker. The heat generated by these systems can be used in industrial processes, heating, cooling, and water desalinating. Given the concurrent generation of power and high-temperature heat, it is possible to achieve higher efficiency than that of conventional solar systems. Furthermore, the electrical efficiency is also higher than conventional systems due to the use of multi-junction solar cells... 

In this thesis, we studied the oscillation of neutrino flavors and the measurement of mixing parameters through the detection of cosmic neutrinos at neutrino telescopes. Most of the astrophysical explosions predict the emission of neutrino flux and kilometer-scale detectors are under construction for the observation of these neutrinos. Detection of astrophysical neutrinos opens a new window to understand the neutrino properties and also the properties of astrophysical sources.In this thesis first we review the phenomenology of neutrino flavor oscillation and characteristics of neutrino mass matrix. By introducing a new class of invariants (under general transformation of lepton fields bases)... 

Excitability is one of the most important characteristics of a neuron. In 1948, Hodgkin identified three different types of excitability of neurons. Excitability an all of its types can be observed in Hodgkin-Huxley model of neuronal dynamics (H-H model) as a four-dimensional system of differential equations and in at least two dimensional reductions of H-H type models. By applying the theory of dynamical systems (e.g. bifurcation theory), one can give a mathematical definition of excitability.Excitability of the neuron is equivalent to that the neuronal model is near a bifurcation through which the state of the system approaches to a stable limit cycle. In this thesis, a two-dimensional... 

Neutrino flavor oscillations are clear evidence of massive neutrinos. It has been for more than a decade that neutrino physics became one of active topics in the field of particle physics and various experiments started studying the flavor oscillation of neutrinos. Unfortunately, experiments studying the flavor oscillations are only sensitive to the mass square difference, and they are incapable of providing more information about the absolute mass scale of neutrinos. Additionally, sterile neutrinos having non-standard interactions are under vast investigations and studies. Determination of neutrino masses and their effective number is among the most challenging problems by which... 

Nowadays, metal matrix composites due to their magnificent properties, has met diverse applications in automobile, aerospace and military industries. Decreasing the reinforcement size from micro-meter to nano-meter, properties of these structures will be improved significantly. Better properties will lead to better applications for them in the future. Thus, the main objective of the current project was investigation on the mechanical properties of metal matrix nanocomposites produced with shock wave sintering. In order to gain this aim, first the sintering of nanoparticles was modeled. A new model was proposed to consider the neighboring particles effects. Using the model, sintering of many... 

This thesis discusses a real-time vision-based framework for the purpose of hand region detection and hand gesture recognition. Our proposed methods include detecting hand regions in the cluttered background, based on Viola-Jones object detection algorithm and improving the classification of detected hand gestures regions in a novel contour-based framework. Our studies have demonstrated that deformability and high degree of freedom (DoF) of human hand as a non-rigid object besides diversity of skin color types, undeniable effect of cluttered background complexity, scalability and being robustness against rotation are the main reasons for considering some simplifications in visionbased...