Sharif Digital Repository

Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX) is a wireless access technology based on IEEE 802.16e. Mobile WiMAX supports mobility and a wide range of Quality of Service (QoS) requirements for several applications. This wireless technology introduces handover mechanisms to avoid disruption of services running on Mobile Stations (MS) through moving. In this thesis, we have focused on balancing the load of the system, using handover mechanisms suggested by mobile WiMAX. The proposed algorithm, WQLB, concentrates on controlling the system load and keeping it in a balanced state by using a handover process. Also, the algorithm is designed to utilize resources... 

In this thesis, a novel method for the design of adaptive wavelet transforms based on the lifting scheme structure is presented. We have compared the proposed adaptive wavelet design method with the exisiting algorithms by providing a brief survey of the recent adaptive lifting scheme techniques. In addition, object detection is selected as the target application and two novel template matching algorithms based on the proposed adaptive lifting scheme transform, called LAPT and RASIM, are presented. As the main building block of the proposed algorithms, given an object as a template, we first select a set of coefficients as object features in the wavelet transform domain and then build an... 

In multi-agent systems (MAS), collective behavior of autonomous agents and complexities arisen by their interactions are studied, while they are exploited to solve real-world complex problems. Machine learning methods are frequently used for problem solving in MAS, because complexities in these systems prevent a programmer to thoroughly describe the agents’ behaviors and the rules governing them.Reinforcement learning (RL) is one of the most commonly used learning methods for intelligent agents,because it does not need a model of the environment and learns agents’ policies through trial and error.Conventional RL algorithms store and update utilities for every possible state in a table. One... 

Enzyme-powered motors self-propel through the catalysis of biofuels, which makes them excellent candidates for biomedical applications. However, fundamental issues such as their movement in biological fluids and understanding the mechanism of propulsion are important aspects that must be considered before application in biomedicine. Building active systems based on biocompatible materials that use non-toxic fuels to power their vehicles have always been challenging. In this study, self-propelled micromotors consist of titanium dioxide black spheres asymmetrically coated with a thin layer of gold. Cysteine was used to bind urease enzyme due to thiol binding. By biocatalytically converting... 

Developing algorithms in engineering and decision making systems based on psychological and biological mechanisms is a promising area of research. The challenging part of any psychological or biological system development is its learning necessity to adapt itself to random incidents, inherent in the environment. Goals, as defined in engineering problems, are the performance functions that continuously evaluate the responses of environment. They have a duty of directing the learning system to the desirable state. If the environment is corrupted by a variety of disturbances that cannot be predicted from the outset, adapting the parameter of learning agent is inevitable. In this work, we... 

In this thesis, we want to present methods that are able to solve the assignment tasks problem in a heterogeneous computing system. These methods are two hybrid methods that are constructed by composing Hopefield Neural Networks with Genetic Algorithms and the Simulated Annealing. First, we solve the relaxed problem by applying Genetic Algorithms and the Simulated Annealing and we compare the results of these ways with other traditional methods. Then, we solve the constrained problem with mentioned hybrid methods. The definition of the problem is as following: Consider a distributed computing system which is comprised of set of processors with different speeds but the same structure. We want... 

Wind power is site dependent and is by nature partially dispatchable. Furthermore, good wind sites are far from grid. Due to these problems, and along with the existing limitations in the transmission networks, a comprehensive analysis over an extended time is needed to properly explore all potential wind sites for wind capacity allocation. This problem is computationally expensive and decomposition methods are required to break down this problem. Here Benders decomposition approach is used, which is a popular technique for solving large-scale problems, to decompose the original problem into a master and a subproblem. The master problem is a linear problem, which allocates wind capacity to... 

In the past few years, many research works on the controllable integration of metal nanoparticles and metal-organic frameworks were done, since the obtained composite material shows a synergism effect in catalysis and photocatalysis, drug delivery applications, gas, and energy storage, as well as sensing. For the first time, in this study, we employed template-assisted growth to synthesize Au-HKUST-1 Nanocomposite. XRD analysis entirely confirms that employing this strategy in synthesizing Au-HKUST-1 was wholly successful, and the plasmonic properties of this nanostructure were studied via UV-visible spectroscopy. In the course of synthesis, gold nanoparticles with 70nm diameter were... 

Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of... 

Image Registration is a fundamental task in numerous applications in medical image processing and is defined as the process of determining the correspondence of between images collected at different times or using different imaging modalities. This correspondence can be used for aligning images so that the pair can be directly compared, combined or analyzed. Image-guided surgery systems use registration for establishing an accurate relation between preoperative and intraoperative image space. There have been several methods for rigid registration which are not easily applicable for soft tissues. Indeed, nonrigid deformation of soft tissues will endanger the accuracy of rigid methods, so it... 

Fire in enclosures is one of the most important disasters due to the presence of human and physical risks, so, investigation of the firefighting scenarios in this case has much importance. In the present study, novel enclosures fire suppression scenarios are simulated using computational fluid dynamics (CFD). The simulations have two major categories. In the first part, performance of different natural ventilation, positive pressure ventilation (PPV) and negative pressure ventilation (NPV) scenarios, which are new methods in firefighting, are evaluated and compared. In this part, the influence of different parameters like geometry, position of inlet and outlets and fire heat release rate... 

In this thesis, we have implemented the quantum renormalization group method to study quantum spin systems. We reviewed the recent progress to calculate the quantum information properties of these models. The recent investigations show that concurrence and entanglement are two quantities which can show quantum critical properties of the quantum systems. More specifically, the derivative of entanglement and the second derivative of ground state energy show divergent behavior at the quantum critical point. Moreover, the ground state fidelity for two different parameters close to quantum critical point shows a drop which leads to a divergent behavior in its corresponding susceptibility. We have... 

Recently magnesium alloys have shown great potential as biodegradable metallic implants. However, due to high corrosion rate in the body environment, these alloys would be degraded before the tissue healing time period. Therefore corrosion resistance of these alloys has to be improved in order to be used in biological environments. In the present work, supposing improvement of corrosion properties of magnesium AZ91D alloy, the alloy has been coated with biocompatible nano-Zirconia particles using Electrophoretic deposition method and the effects of deposition parameters such as bath agitation, Zirconia concentration, current density and duration of deposition process on the properties of the... 

Price and warranty are two powerful marketing tool that can stimulate consumers’ purchase willingness. Therefore, producers must choose the appropriate price and warranty that can stimulate customers to purchase the quantity that will achieve the maximum profit. This study investigates optimal strategies for price and warranty length of a new product to maximize profit of a producer during lifecycle of the product. We consider both durable products and non-durable ones. Customers buy non-durable products many times but if we consider the planning horizon relatively short, each customer buys one product during the period. So, the market for non-durable products is static and for durable ones...