Sharif Digital Repository

In this thesis a substrate integrated waveguide (SIW) filter is designed and constructed using the contour integral method. A substrate integrated waveguide can overcome the drawbacks of regular waveguides, namely bulkiness, high costs and the difficulty to be integrated with other elements in high frequencies. In planar structures with arbitrary shapes where green’s functions aren’t available, we can use the contour integral method to construct the impedance matrix. Because the SIW structure supports TEn0¬ modes, we can consider SIW as a planar structure and thus use the contour integral method. Regular filter structures are usually analyzed using the FEM method (with HFSS) or the FIT... 

In this research, I intend to case study formal education textbook in Iran that responsible for educate science in elementary school or educate physics in high school that to study the situation of education in this field of knowledge in Iran. The method of this research is study the text of textbook and find instance that somehow build philosophy of science assumption in students’ minds. In the following, I categorize these founded phrase that find in all related books, following the current philosophy of science theories. In the end of this research, I present an explanation of these authors textbook’s assumption  

Magnetic elastomers are smart materials that consist of a combination of elastomeric matrix and magnetic particles. The mechanical and magnetic properties of this materials are changed by Applying an external magnetic field. The presence of an external magnetic field can cause these elastomers deform largely.Significant deformations of the magnetic elastomers, has made them suitable for a wide range of applications. The aim of this project is to solve the governing equations of magnetic elastomers with finite element method. Since there are no suitable models for the behavior of these elastomers in the commercial softwares, magnetic field module and solid mechanics module should be coupled... 

In this thesis, we have tried to study one of the most well known collective behavior phenomena known as the Wisdom of the crowd, from the perspective of statistical physics. In recent decades with the appearance of Social Networks and mass media, collective social phenomena have become a critical topic in the life of every human being. In the Wisdom of crowd phenomenon, the overall process is to ask the crowd’s opinion regarding a special topic and after aggregating the predicted values, the aggregated quantity is declared as the wisdom of the crowd. It has been observed that in some polls and elections, the result of the wisdom of crowd outperforms every individual of the group and in some... 

Electromagnetic metamaterials are designed artificial materials with sub-wavelength resonant inclusions. They can exhibit extraordinary properties such as negative permittivity, negative permeability, and anomalous reflection/refraction. Metasurfaces are 2D counterparts of metamaterials. Here, we proposed a framework for the multiscale multiphysics analysis of deformable metasurfaces. Nonlinear mechanical analysis (Geometry and material behavior), periodic boundary conditions, homogenization, multiscale analysis, and electromagnetic analysis are implemented in this framework. Benefiting from the framework, we proposed a multifunctional hyperelastic structured surface that can generate... 

There is a need from the natural gas and energy industries to seek for an economically attractive way of converting remote gas reserves into transportable products, such as high quality fuels or petrochemicals. A possible way for the conversion of natural gas to middle distillates is based on a three-step process. Firstly, production of syngas from natural gas. Secondly,catalytic conversion of syngas into hydrocarbons, mostly parafins from C5 to C100. (Fischer-Tropsch (F-T) synthesis). Thirdly, hydrocracking of the heavy paraffinic hydrocarbons to middle distillates. The F-T synthesis step is highly exothermic. In order to control the temperature within the reactor, when considering high...