Sharif Digital Repository

This study proposes a novel type of metallic yielding damper called block slit damper or BSD. This damper is a slit damper with very low height to thickness ratios. This device is buckle resistant, possesses high shear capacities, and is more economical than SSD devices with high height to thickness ratios. Based on theoretical analysis the formulation for the BSD device’s main parameters is derived. Then to investigate the hysteretic behavior of the proposed devices, 5 specimens with different aspect ratios (height-width ratios) were manufactured and tested in a quasi-static manner. The tests revealed that by reducing the aspect ratios, the shear and energy dissipation capacity increases... 

Intrusion detection systems’ test and evaluation is an active research area on which many researchers have been working for years. A complete and comprehensive test methodology that can be applied in reasonable time and cost is important and useful both to evaluate a newly designed system and to compare two or more existing systems to select an appropriate system for a particular network. In this research, we first determine the critical features of an IDS and then inspect methods and effective parameters that may influence the test process and propose a method for testing intrusion detection systems. In the proposed test methodology we only examine critical features which lake of them cause... 

Being harmless to living tissues makes magnetic robots very promising for medical applications. Furthermore, since these robots are driven by external magnetic fields, no actuators are needed to be placed on the robots, enabling them to come in very small dimensions if necessary. Motion control of small magnetic particles paves the way for future applications, such as deliberate drug-delivery, sampling, and lowinvasive surgeries.The goal of this research is to design and construct a platform for generating desired magnetic fields in order to control the motion of magnetic robots in threedimensional space. In order to do so, a system of eight electromagnetic coils with iron cores was built.... 

In this thesis, which is based on an article of Claus Scheiderer (Reference [21]), the relation between positive semi-definite elements of a semilocal ring, called psd, and elements of the ring which can be written as a sum of square elements of the ring and are called sos will be evaluated. In Chapter One, the concepts of prime cones, real spectrum of a ring and real ideals will be defined and then the relation between psd and sos elements in the total rings of quotients will be assessed. The Krull Valuation of an element which is a sum of squares will also be determined. In Chapter Two, the concept of totally positive elements in a ring will be defined and their properties will be... 

Friction stir welding (FSW) is an appropriate method for joining Aluminum structures. In this method lots of defects involved in other methods are not formed and good properties are achieved for Aluminum joints. The metal sheets joined by this method are used to manufacture metal structures bodies. One of the important issues in the structure bodies used in transportation is the amount of energy absorbed in collision with other objects. One of the methods to investigate the energy absorption is wedge tearing test and one other is tensile test. In the preset study two sheets of Al 1050 were joined using FSW method in different tool rotational and welding speeds. Firstly, the microstructure of... 

The development of deep neural networks is making tremendous progress in various fields, including processing Image, speech processing and other areas. Despite this tremendous achivement, neural networks have a lot of computational overhead and memory access that prevent them from being used in resource-constrained devices. We also know that many neural network applications are of great importance in mobile devices, and it is desirable for us to use their power in this regard. Many efforts have been done at different levels to solve the problem of executing deep neural networks on these devices. In this research, an approach based on offloading is used in which two different small (on the... 

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... 

In the present research the methods and challenges to ocular drug delivery have been investigated with more emphasis on ocular diseases that do not have any approved treatment. Periocular route is a promising alternative to the common routes of ocular drug delivery especially for treatment of posterior eye diseases. Based on barriers for efficient drug delivery to the eye, magnetic drug targeting revealed to be influential to eliminate some obstacles of this route which has not been worked before. It is hypothesized that the particles can pulled into the eye or will be trapped inside the sclera tissue or even if it is not happened, they can stay behind the sclera and magnetic force can... 

Since the classical continuum theory fails to deal with the problems associated with defects, stress concentrators, and relevant deformation phenomena in solids, alternative approaches that can detect the atomistic nature of materials' fracture are required. The deficiency of the capture the size effect which yields delusively high values for some components of the stress field right on the edge of the stress concentrators, and its weakness in describing the complex interaction between small inhomogeneities, cracks and the like when they are only a few nanometers apart, are among some of the disadvantages of the classical approach. In recent years, however, atomistic methods are emerging to... 

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...