Sharif Digital Repository

This paper presents a surface generation model for sculptured surface productions using the ball end milling process. Dimensional measurement using a coordinate measuring machine (CMM) has been commonly adapted in advanced manufacturing environment to ensure that manufacturing products have high quality and reliability. To conduct dimensional inspection efficiency in a computer integrated manufacturing (CIM) environment, there is an urgent need to derive a sampling strategy which can be used to specify a set of measuring points that lead to accurate sampling while minimizing the sampling time and cost. Owing to the variations in characteristics of geometric feature and manufacturing process,... 

In this dissertation، with regard of the importance of innovation and being innovative in the competitive conditions of the markets in the world، and the need of companies for some permanent competitive advantages، we are looking for some models and finding or creating some instruments to know and create knowledge for basics of innovation and innovation capacity before measuring the outputs of innovative projects، as innovation capability، and have the needed knowledge for managing resources and having the intransitive tendency to important factors that crystallize the structure of innovation capacity. For this purpose، we had a vast literature review with reading so many books about... 

The need for integration of electron guns together with thermal considerations of thermionic cathodes has led to design new cold cathode guns based on field emission phenomenon. In first part of this thesis, basic field emission theories, fabrication methods of field emitter arrays, effect of different parameters on the field emission properties of field emitter arrays and applications of these arrays are investigated. After setting up fabrication methods of nano-tip field emitters, in the second part of thesis, Si nano-tips and Si field emitter arrays are fabricated using of thermal oxidation of silicon substrate, lithography, and chemical etching of silicon oxide and silicon substrate. Si... 

A Reaction Wheel (RW) is a torque actuator which is used for attitude control of a satellite. Reaction Wheels usually consist of a brushless DC motor which rotates a flywheel. When the flywheel is accelerated by the motor, the reaction torque of the motor applies to the base of the RW and therefore the satellite can rotate along the RW spin axis. Due to frictionless surrounding of a satellite in space, a very small disturbance in a reaction wheel structure during its function may lead to instability of satellite and decrease the satellite precision and performance. There are some important sources of disturbance in an RW. Some of them are: 1- Unbalances in wheel (offset of center of gravity... 

Quantum Mechanics, as the most famous physical theory was founded about 85 years ago; but still there are a lot of debates about its interpretation. In this work, we review some basic concepts of Quantum Mechanics in form of questions about uncertainty principle, measurement problem and complementarily. We also review Bell inequality which has great philosophical and recently technological results. Bell derived his inequality regardless of modeling the measuring apparatus; we show, by take a realistic model for measuring apparatus, Bell inequality would be deduced. Finally we review a mathematical language which was used to show the duality of wave and particle. Quantum... 

In the early time of the discovery of the quantum mechanics and some decades after that, various interpretations of quantum mechanics were proposed. However, many years after that, the “indetermenistic” perspective well-known for Copenhagen perspective which was proposed mostly by Bohr and his colleagues became the dominant attitude among physicists. But nearly two decades after the fixation point of the Copenhagen perspective, a new interpretation of quantum mechanics was proposed by Bohm which was nonlocal but deterministic and it could reproduce all the predictions of quantum mechanics.Bohm’s theory responded to the many theoretical and philosophical objections assumed to the Copenhagen... 

Any physical system is characterized with some set of quantities or parameters, knowing which, is equivalent to estimation of the system. Evaluating such parameters is usually done using tomography methods. An important question to ask, is how to increase the precision of measurement, being able to do some specific set of physical operations, say, measurement?
this question is more important in parameter estimation in quantum meanical systems. It has been shown that, quantum meanics causes a fundamental limit, on precision of estimating su parameters, escribed by the so called “antum Cramér-Rao bound”.We must note that almost all quantum meanical systems are interacting with the... 

Mostly, the high voltage DC power supplies have output voltage ripple. In such an applications like power supply of microwave lamps in radar systems, low output voltage ripple is an important point of operational characteristics. On the other hand, measuring the low voltage ripple will be a challenge that can lead to recognize of its reasons and reduce its amplitude. In this thesis, different ways of ripple measurement constraints is described, then a method based on high pass filters for output voltage ripple measurement is implemented. The impact of components tolerance and their parasitic components like shunt parasitic resistance of a capacitor in filter operational characteristics is... 

The TWT is highly sensitive to the ripple amplitude of its power supply output voltage. If the amplitude of the output voltage's ripple exceeds a certain limit, the amplitude of the undesired harmonics in the power spectrum of the TWT is greatly increased. Increasing the amplitude of undesired harmonics in the TWT output power spectrum reduces the accuracy and performance of the TWT. Therefore, for optimum TWT performance, a low-ripple power supply is essential. Typically, a low-frequency rectifier or high-frequency switching structure is used to build a high-voltage DC power supply. In this thesis, the different structures of high voltage DC power supplies are studied. Next, by focusing on... 

Microfluidics is a novel technology that brought a revolution in the field of chemistry and biology. This technology allows precise control and manipulation of fluids and particles in sub-millimeter bio-compatible channels. This makes microfluidics a powerful tool to study and examine bio-particles and bio-processes. One of the most prominent areas in microfluidics is the integration of developed measurement tools and devices of the electrical engineering field, with microfluidic chips. The purpose of this thesis is to measure the electrical impedance spectrum of bio-particles with high precision and in a wide bandwidth. These valuable spectrums are useful in many applications such as... 

Electromagnetic field modes have several degrees of freedom, including polarization, orbital angular momentum, and radial order, which can be described by orthogonal modes. By using all the degrees of freedom in communication, the channel capacity can be increased dramatically. With the aim of increasing the capacity and correcting the errors created along the optical fiber, two important issues have been addressed in this thesis. First, the states propagated in the fiber may be disrupted by many unwanted factors and may not be transmitted correctly. Therefore, measures should be taken to minimize the impact of these factors as much as possible or to compensate for their effects. In the...