Sharif Digital Repository

Finite dielctric structures are commonly used in optical devices, Microwave Integrated Circuitc (MICs) and printed antennas. To analyze these structures, full-wave analysis methods cannot be employed easily. They need huge computer resources and are time-consuming especially for electrically large structures. On the other hand, asymptotic techniques may not be exact enough for these structures. In this thesis, MPIE technique is chosen as an accurate and efficient technique for analyzing these structres. To use this technique, the magnetic vector potential and electric scalar potential are required. Uniform and closed-form spatial Green's function for finite dielectric structures is... 

It is a common method to use some proper materials such as honey, herbal fibers, and minerals for covering the wounds as an effective treatment. Nowadays biopolymers and new methods of nanofiber production to build a structure similar to the natural extracellular matrix (ECM) like electrospinning are used to reduce the time of restoration and prevent from the effects of wounds such as bedsores, diabetic ulcers, and severe burns. For effective design of a wound dressing, wound feature, recovery time, physical, mechanical, and biological properties should be considered in order to best as possible heal the bound. In this research, cellulose nanocrystals with average aspect ratio of 11.8 and... 

This paper studies a multi-product, multi-period location- routing- inventory problem in a three-level supply chain including suppliers, cross-docks and customers. Each cross-dock could be supplied by more than one supplier and each customer could be supplied by more than one cross-dock. In the first phase we find the best locations for the cross-dock and allocate them to customers and suppliers by considering inventory costs. . Then, in the second phase Products are distributed from cross-docks towards customers using Heterogeneous vehicles. In this article the option for split delivery is enabled and furthermore, backlogging is allowable for each customer. The model presented in this... 

Accurate and fast position controlling is an important issue in today’s industrial needs. Drives used for position control require fast dynamics on speed control. Cascade linear controllers have sluggish response due to bandwidth limitations on speed and current loop. These structures limit the dynamics above all in high power applications where the switching frequency is low. In this thesis, deadbeat direct speed control is proposed, which overcomes limitations by cascade loops resulting in high-speed control dynamics. This approach uses a model of the plant to generate the control signals. According to measured speed and currents, the controller specifies the best voltage vector in order... 

The aim of this paper is to perform macro stress test for one of Iran’s private banks using bank’s quarterly data from Q-4 1383 to Q-4 1389. To do this, the relation of bank’s default rate with macroeconomic indicators like house prices and the growth rate of value added of services; as macroeconomic risk factors; was investigated by a linear model. Results show that the bank’s default rate has a negative relation with both risk factors.Stress testing, using monte carlo simulation; shows that reverse shocks to both house prices and the growth rate of value added of services leads to severe increase in bank’s default rate; so that with decrease of both house prices to 4 million rials at... 

Linear structure of polypropylene, which is a direct result of Ziegler-Natta catalysts, led to the melt strength of the polymer is low and it does not show hardness strain. This defect is cause to the use of polypropylene in some processes, such as thermoforming, making foam etc. are limited. A main methods to solve this defect are branching structure of the polymer. There are three general methods for this purpose, which are modified by chemical, electron beam irradiation and polymerization in the presence of metallocene catalyst. The first two methods that past processing, polypropylene branching using linear type is produced, while the third method branching occurs during polymerization.... 

In this thesis, the improving effects of TiO2 nanotubes (TiO2NTs) fabricated by anodizing of titanium as suitable substrate for deposition active materiales in supercapacitors were considered. PANI/Pd/TiO2NTs electrodes with highly porous structures and good capacitive characteristics were prepared by electrodeposition of polyaniline on palladium nanoparticles loaded TiO2 nanotubes. The results illustrated that the specific capacitance of these electrodes was around 1060 Fg−1 in 1.0 M H2SO4 electrolyte as measured at a constant current of 2.0 Ag−1, whereas it was 210 Fg−1 for the PANI/TiO2NTs electrode. NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of... 

Due to the relatively high freedom of selection of materials associated with a simple manufacturing method, a nonpneumatic tire (NPT) can be manufactured with low viscoelastic energy loss material. NPTs consisting of flexible spokes and the shear band are still at an early stage of research and development. An optimization study of NPTs’ geometry needs to be conducted, which is the objective of this thesis. Parametric studies and design of experiments (DOE) of an NPT are conducted with a hyper-viscoelastic finite element (FE) model to determine the effects of four design variables on rolling resistance, contact pressure and vertical deflection. Considering vehicle load carrying capacity and... 

Bonding gravity with Quantum mechanics has always been a challenging issue. So that, accomplishing a theory of quantum gravity is one of the most important research topics in High-Energy Physics.Information paradox in black holes is among such issues which connect quantum mechanics with gravity. Black holes as a natural solution of Einstein equations have a distinction, with other solutions, since there exists an event horizon that imparts space-time into two causally disconnected regions.According to Hawking’s calculations, black holes would evaporate over time by the thermal radiation. This resulting thermal radiation has less information than the initial collapsed matter in a pure state....