Sharif Digital Repository

The importance of rainfall pattern in assessing embankment stability and deformation is widely known. However, many studies have examined an embankment with simple rainfall patterns or used average and maximum ones. The importance of diverse rainfall patterns has also been overlooked in the study of divergent soil stability in the previous study. Therefore, the hydraulic properties of a natural soil with and without salinity potential and the stability analysis of the railway embankment located on this type of soil under various rainfall patterns are investigated. The study area is part of the Zahedan Chabahar National Railway Project, which is located on divergent soil and has high... 

Today, many evidences, including the distribution of galactic velocities, gravitational lensing observations, and the cosmic microwave background, show that there exist dark matter (non-baryon matter) in large-scale cosmological structures that are stable, free of charge and without color, which has gravitational interaction like normal matter. The hypothesis that weakly interacting massive particles (WIMPs) as a dark matter candidate with mass range of several tens of GeV to several teV and with the typical couplings of Electroweak order of magnitude, is an attractive and desirable model, Which naturally explains the density of cosmic dark matter in agreement with observations. Alongside... 

Quantum key distribution is one of the practical quantum information technologies in labo- ratories with existing equipments.In quantum key distribution protocols, the main challenge is the secrecy of key distribution. One of the new methods of quantum channel error esti- mation is the use of weak measurement. In this thesis, after introducing the main quantum key distribution protocols, we introduce weak measurement and sequential weak measure- ment concepts: the weak measurement methods are exployed to obtain the phase difference between two polarizations with high accuratly. It is also used for in line monitoring and error estimation parameters in some quantum key distribution protocols.... 

Nowadays, radiation therapy is one of the most common methods for the cancer treatment. Intensity Modulated Radiation Therapy(IMRT) is a novel technique of radiation therapy that aims to delivere sufficient dose to cancerous tissues while sparing healthy organs. There are various uncertainties in radiation therapy problems, including uncertainty about device setup, device errors, interfraction and intrafraction motions. One of the most important uncertainties is the movement of the tumor during the treatment process(intrafraction motion), as this displacement may cause the cancer tissue to not receive sufficient dose and also to damage the healthy tissue due to a violation of their dose... 

One important problem in all, particularly in developing countries, is shortage of funds to invest in infrastructure projects. One way to lessen this difficulty is to benefit from the private sector participation in this respect. Build-Operate-Own-Transfer (BOT) is a Public-Private-Partnership (PPP), in which the private sector invests and builds a (e.g. road) project, operates it for a specified period of time to collect the tolls to return the investment cost plus the specified attractive rate on it, and then transfer it to the public sector. This research, which is a continuation of previous endeavors in this area, formulates the problem, discusses the multiplicity of the solutions, and... 

With the extensive use and the growing popularity of file sharing in peer-to-peer (P2P) networks, the distribution of copyrighted files and the propagation of malwares have also increased. The increasing growth of these crimes multiplies the necessity of forensic investigation in order to detect the offenders. The yet proposed methods have sought to gather some proofs for forensic investigation by the application of some changes in clients’ programs and a constant monitoring of the network. These methods, however, have some limitations which have rendered useless the results of their application in real environments. Moreover, the important issues like the detection of the file source have... 

Power transformer is one of the most important equipment in the power system which plays a key role in the reliability and quality of power delivery. Among numerous failure modes of a typical power transformer, the turn-to-turn fault (TTF) is one of the most prominent reasons for its unplanned outage. A turn-to-turn fault quite often begins with the degradation of the winding insulation between two adjacent turns, then in a short time, this low-level fault can progress to a large number of turns and results in the transformer costly damages. Therefore, it is vital to detect TTF at an early stage and prevent its progression to a catastrophic disaster. The conventional percentage differential... 

In this article, research has been carried out on the control technique of autonomous mobile robots to navigate in unknown environments, avoiding static and moving obstacles using eight ultrasonic sensors for obstacle recognition.
In this article we used simple three wheeled robots. Each robot has a passive caster wheel and two active fixed wheels which can act independently. In addition robots have holonomic constraints like maximum acceleration, maximum speed and maximum angular velocity, so robot’s speed and orientation change independently and these changes are small in each time step. Each robot has eight ultrasonic sensors, each of them cover 22.5 degree of space from robot‘s... 

Tin sulfide with an energy gap of about 1.1 ev is a semiconductor suitable for applications such as solar cells, lithium-ion batteries, photocatalysts and other semiconductor-based devices. There are several methods for synthesizing this semiconductor at the nanometer scale, among which the solvothermal method is an efficient, controllable and inexpensive method. By precisely controlling the parameters of this process, two-dimensional tin sulfide nanosheets with high purity and desirable morphology can be produced. In this research, tin sulfide has been synthesized by solvothermal / hydrothermal chemical method and its metallurgical properties have been studied. Effect of solvothermal... 

Dye-sensitized solar cells (DSSCs) are Photoelectrochemical cells using wide band gap nanoporous oxide semiconductors sensitized by dye molecules. For achieving high efficiency DSSCs preparation of photoanode electrode with high surface aea which leads to adequate dye absorption is necessary. In order to achieve proper morphology, thickness, particles size and porosity, producing a TiO2 nano-structured paste is required. TiO2 powder was prepared using sol-gel method. following a calcination process at 300 degrees, XRD patterns showed presence of anatase and brookite structures with average crystallite size of 9 nm. Additives such as diethylene glycol, acetylacetone and Triton X-100 were used... 

The purpose of this thesis is the analysis, design and fabrication of polarization converters in the millimeter-wave and terahertz regions using metasurfaces in order to generate different polarizations in the transmitter of terahertz stand-off imaging systems. In this project, the design and fabrication of two linear cross-polarizers and a circular polarization converter have been done at the frequency of 100 GHz. These polarizers are easy to fabricate by printed circuit board (PCB) technology and are capable of converting the polarization of a linear incident wave to the cross-polarized transmission wave and circular polarization, respectively. Linear polarizers are double-layer and... 

Nowadays, due to the advancement of robotic technologies and development of industrial robots, the robot manipulators are widely used for automation of various manufacturing processes, such as finishing processes. In these applications, the contact has to be made between robot end-effector and environment. Therefore, control of interaction force in the constrained manipulators is an important demand. On the other hand, due to use of gear box and belts for energy transmission in robot joints, robot manipulators have flexible joints. The vibration, generated due to the interaction force and robot joint flexibility, can deteriorate surface roughness in automated finishing processes. In order to... 

The goal of this thesis is modeling and simulation of aircraft landing motion in order to evaluate the performance of an optimal anti-skid brake system (ABS) for the main landing gears with friction effects. In this process, the aircraft 6DOF perturbed equations of motion augmented with pertinent friction and brake forces and moments have been utilized. Subsequently, the problem is formulated within the framework of an optimal LQR that has allowed for generation of control brake commands as well as aircraft landing performance at different landing conditions with and without the proposed ABS. The results demonstrate the proposed ABS has been effective in providing admissible landing... 

Artificial immune systems (AIS) constitute a novel area of bio-inspired computing. Biological models of the natural immune system, in particular the theories of clonal selection, immune networks and negative selection, have provided the inspiration for AIS algorithms. Moreover, such algorithms have been successfully employed in a wide variety of different areas, but have not been applied for chemical processes yet. One important part of the immune systems is lymphatic system. Clonal selection is one of the few algorithms that belong to the family of AIS techniques. Clonal selection algorithm is the computational implementation of the clonal selection principle. In this project, we have... 

Non-uniform composite structures are widely being utilized in many modern industries including aerospace and automobile and wind turbine machines. Excessive vibration in these structures leads to dynamic instability and structural failure. In the present work, the vibration control of non-uniform composite structure particularly trapezoidal plates has been investigated using magnetorheological materials. The application of various smart materials including magnetorheological (MR) elastomer and magnetorheological fluids has been reviewed for vibration control. A trapezoidal composite plate with holes filled by MR elastomer has been considered for numerical simulations. The effect of location... 

The physics of the flow around the wing in the oscillatory motion of the wing has various patterns, including the leading edge vortex, the tip vortex and trailing edge vortex escape. The interaction of these vortices forms a complex flow structure around the wing, which will have a direct effect on the aerodynamic performance of the wing. Therefore, controlling these structures can be considered as a way to improve the performance of the flapping wing. One of the passive flow control techniques that has recently been taken into consideration is a leading-edge protuberance method. Another type of passive flow control is geometric correction, using corrugation method. According to studies, two... 

In this thesis, functionalized Fe3O4 nanoparticles have been utilized as a support for immobilization of homogeneous catalysts. The catalytic activity of the supported heterogeneous nanocatalysts was investigated in hydrocarbon and sulfide oxidation reactions. In the first part of this research, imidazole functionalized Fe3O4 nanoparticles (Fe3O4@SiO2-Im) were used as a support to anchor manganese porphyrin complex, [MnT(4-OMeP)P]OAc; via axial ligation. Catalytic application of the immobilized manganese porphyrin was studied in oxidation of alkenes and sulfides. To find suitable reaction conditions, the effect of different parameters such as solvent and temperature on immobilization process... 

The charge transfer interaction of two Schiff-bases 2,5-dichloro -bis(thiophen-2-ylmethylene)benzene-1,4-diamine and 2,5-dimethyl-bis(thiophen-2- ylmethylene) benzene-1,4-diamine as donors with I2 and TCNE ethylene as acceptors have been studied spectrophotometrically.
The formation constants and extinction coefficients of charge transfer complexes have been determined by graphical as well as iterative methods. From measurements at different temperatures the thermodynamic functions of the charge transfer complex formation have been studied. The temperature dependence of the K can be used for the determination of the thermodynamic reaction quantities (ΔG, ΔS, ΔH) for linear regression... 

In this dissertation, the thesis of Duhem-Quine holism will be intoduced and its similarity and dissimilarity in epistemolical webs of Duhem and Quine will be enumerated and criticisms that is taken to this thesis will be examined. In chapter 1 and 2, the fundamental characteristics of Duhem and Quine viewpoints will be introduced in sequence. This chapter is introduction to more accurate understanding of holism each of them and better Comparison together. In chapter 3, we will introduce their holism and we’ll see what the results of their holism in falsification and confirmation of different Hypotheses are. In chapter 4, we will discuss about discrepancy between their viewpoints and we... 

During recent decade huge number of new malware samples and their complexity have caused challenges to malware detection procedure. additionally the use of kernel level rootkit has been grew up. while rootkits usually defeat current security products which are cheifly relied on Operating system for gathering information and also running, existing nti-rootkit solutions can not cover all kinds of rootkits.In this work we have studied the problem of kernel-level rootkits in Windows operating system. we believe that focusing on kernel drivers features, will result in an overall view needs for monitoring kernel activity of the rootkits. Thus with regards to proves for lower volume of obfuscation...