Sharif Digital Repository

Direct Torque Control (DTC) is one of the vector methods to control Permanent Magnet Synchronous Machines (PMSM). In order to achieve an appropriate control in vector control methods, an accurate estimation of flux is indispensable. Flux estimation should be fulfilled in a wide speed range without considerable dependence on motor parameters. Prevalent flux estimation methods are based on integration of stator voltage which is not feasible in low speed, or performed based on assumption of decoupled equations on d and q axis which is not precise for applications with fast dynamic. Different flux estimation methods are investigated in this thesis with the aim of improving the flux estimation in... 

Hydrocephalus is a desease which causes by unnatural accumulation of cerebrospinal fluid in the brain ventricles. One of the most convenient ways to treat hydrocephalus disease is to use a brain shunt which consists of ventricular catheter, valve and distal catheter. Ventricular catheter obstruction is the main reason for shunt replacement in the human brain. This project attempts to remove obstruction of the ventricular catheter by mechanical forces. For this purpose, a magnet and a variable magnetic field suggested to apply mechanical force on a brush sliding on the shunt. On the inner surface of the ring-shaped magnet, brushes have been embedded and the magnet is placed on the outer... 

In this research dynamic modeling of a 3-DOF (degree of freedom) compliant parallel mechanism with flexible intermediate links has been investigated. Unlike conventional rigid mechanisms that gain their mobility from movable joints, the compliant mechanisms transmit or transform through elastic deformation of flexible members (flexible connector and joint), displacement, force, or energy from input into output. Eliminating clearance, friction, wear and demand of lubrication in compliant mechanisms, and having monolithic structure provides high-precision motion with micro/nanometer level resolution for them. Therefore compliant mechanisms play a significant role in modern technologies such as... 

Drug targeting to specific organs and tissues has become one of the critical endeavors of the new century. Magnetic nanoparticles have gained a lot of attention in biomedical and industrial application. Doxorubicin is an effective anti-cancer drug in the treatment of many types of cancers. The aim of this study is to load doxorubicin on stimuli-responsive nanocarriers. These nanocarriers are prepared from magnetic nanoparticles. Then these magnetic nanparticles are coated by copolymer of poly(glycidyl methacrylate) then reacted with hydrazine and hydrazide functional group is formed that can chemically be bonded with the anticancer drug doxorubicin via a hydrazone bond formation. This... 

A bolometer is a device for measuring electromagnetic waves, which uses the heating of a material with variable resistance to temperature. Due to the existing limitations and quality improvement, superconducting materials are used in the manufacture of these devices. In this dissertation, the construction and improvement of the components of a high temperature transient edge superconducting radiometer with terahertz detection capability is discussed. In the construction of these detectors, the superconducting material YBa2Cu3O7-x is used as a thermal sensor with a transition temperature of 93.5K. In order to characterize these detectors, an automatic system for measuring the voltage response... 

Software modeling is one of the most important activities in the Software Engineering domain. Models provide an abstract view of the system, thereby facilitating their understandability and resolving the complexities and problems involved. Indeed, models can be considered as a roadmap for achieving the goal of producing software-intensive systems. The aim of real-world modeling is to identify real-world entities, their interactions, and the constituent activities. Real-World Models are tangible to all stakeholders and provide them with an overall view of the Problem Domain. Therefore, many software development methodologies are based on modeling the real world. In some of these... 

General-purpose Chip Multiprocessors (CMPs) are used to run a wide range of applications. Task-to-network mapping is one of the best NoC optimization methods which highly affects the NoC power and performance metrics. However, this kind of optimization can be applied
only when the input application and its traffic pattern is known in advance and is described by a communication task-graph. However, for some applications, such as multimedia and network applications, the communication task graph is not known in advance. Hence, we cannot achieve an optimum task mapping by using the existing mapping algorithms. In this thesis, we aim to address this problem by proposing a distributed run-time... 

Descriptive complexity refers to the difficulty of expressing a problem in a formal language, allowing for a complete and precise description of the problem, including output specifications for function problems. Despite the success of the descriptive approach in computational complexity, this approach has been predominantly used for decision problems. In contrast to decision problems, a counting problem can be considered as a function with the range of natural numbers. This thesis focuses on the examination of counting problems from a descriptive perspective, exploring the connection between their descriptive and computational versions. Toward this goal, weighted logic is utilized to... 

Gamma ray spectroscopy has a special place in the industrial applications of nuclear radiation. Currently, the most common device for gamma ray detection and spectroscopy is the sodium iodide scintillation detector. Long life and high efficiency and reasonable price of these detectors are the reasons for the development of the use of these detectors in industries and laboratories. But these detectors in the classification of energy sensitive detectors are considered as detectors with low resolution. The presence of broad peaks in the gamma ray spectrum of this detector increases the possibility of interference of peaks related to different energies and makes it difficult to identify the...