Digitized by Kansas Correctional Industries

The objective of this research is to assess the performance of two popularReynolds-averaged Navier-Stokes (RANS) models, standard k-E and k-w, andto suggest modifications to improve model predictions for high-speed flows. Numerical simulations of turbulent ow past a at plate are performed at M1 = 2:25; 7:2.The results from these two Mach number cases are compared with Direct NumericalSimulation (DNS) results from Pirozzoli et al. (2004) and experimental results fromHorstman & Owen (1975). The effect of the Boussinesq coefficient (Cu) and turbulenttransport coefficients (sigmak; sigmaE; sigma; sigma*) on the boundary layer ow is examined. Further,the performance of a new model with realizability-based correction to Cu and corresponding modifications to sigma; sigma* is examined. The modification to Cu is based oncontrolling the ratio of production to dissipation of kinetic energy (P/E=1). The firstchoice of P/E = 1 ensures that there is no accumulation of kinetic energy in stagnation or free-stream regions of the ow. The second choice of P/E= 1:6 holds underthe assumption of a homogeneous shear ow. It is observed that the new model'sperformance is similar to that of the existing RANS models, which is expected for asimple ow over a at plate. Finally, the role of turbulent Prandtl number (Prt) intemperature and density predictions is established. The results indicate that the k-wmodel's performance is better compared to that of the standard k-E model for highMach number flows. A modification to Cu must be accompanied with correspondingchanges to sigmak; sigmaE; sigma; sigma* for an accurate log-layer prediction. The results also indicate that a Prt variation is required across the boundary layer for improved temperatureand density predictions in high-speed flows.

The objective of this work was to design high-speed circuits using silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) and complementary SiGe (C-SiGe) HBTs, as well as silicon (Si) complementary metal oxide semiconductor (CMOS) devices, for next-generation ultra-wideband (UWB) transceivers. The advantages of using UWB systems over conventional narrowband transceivers include their lower power requirements, higher data rate, more efficient spectrum usage, precise positioning capability, lower complexity, and lower cost. The two major components in a UWB transceiver IC are the radio frequency (RF) circuit and the analog-to-digital converter (ADC). In this work, circuit-level solutions to improve the speed and performance of critical building blocks in both the RF front-end and the ADC are presented. Device-related issues affecting SiGe HBTs for potential applications in UWB systems intended for use in extreme environments will also be investigated. This research envisions to realize various circuit blocks in a UWB transceiver including, a 3-10 GHz UWB low noise amplifiers (LNAs) in both the second (120 GHz) and third (200 GHz) SiGe technologies, an 8-bit 12 GSample/sec SiGe BiCMOS track-and-hold amplifier (THA), and a fifth order elliptic gm-c low-pass filter in C-SiGe HBT technology. This research will also focus on characterizing SiGe HBTs for UWB electronics for operation in extreme environments by investigating the proton radiation effects in the third generation SiGe HBTs.

Power systems on modern commercial transportation systems are moving to more electric based equipment, thus improving the reliability of the overall system. Electrical equipment on such systems will include some loads that require very high power for short periods of time, on the order of a few seconds, especially during acceleration and deceleration. The current approach to solving this problem is sizing the electrical grid for peak power, rather than the average. A method to efficiently store and discharge the pulsed power is necessary to eliminate the cost and weight of oversized generation equipment to support the pulsed power needs of these applications. Highspeed Flywheel Energy Storage Systems (FESS) are effectively capable of filling the niche of short duration, high cycle life applications where batteries and ultra capacitors are not usable. In order to have an efficient high-speed FESS, performing three important steps towards the design of the overall system are extremely vital. These steps are modeling, analysis and control of the FESS that are thoroughly investigated in this dissertation. This dissertation establishes a comprehensive analysis of a high-speed FESS in steady state and transient operations. To do so, an accurate model for the complete FESS is derived. State space averaging approach is used to develop DC and small-signal AC models of the system. These models effectively simplify analysis of the FESS and give a strong physical intuition to the complete system. In addition, they result in saving time and money by avoiding time consuming simulations performed by expensive packages, such as Simulink, PSIM, etc. In the next step, two important factors affecting operation of the Permanent Magnet Synchronous Machine (PMSM) implemented in the high-speed FESS are investigated in detail and outline a proper control strategy to achieve the required performance by the system. Next, a novel design algorithm developed by S.P. Bhattacharyya is used to design the control system. The algorithm has been implemented to a motor drive system, for the first time, in this work. Development of the complete set of the current- and speed-loop proportional-integral controller gains stabilizing the system is the result of this implementation. In the last part of the dissertation, based on the information and data achieved from the analysis and simulations, two parts of the FESS, inverter/rectifier and external inductor, are designed and the former one is manufactured. To verify the validity and feasibility of the proposed controller, several simulations and experimental results on a laboratory prototype are presented.

The objective of this research is to assess the performance of two popularReynolds-averaged Navier-Stokes (RANS) models, standard k-E and k-w, andto suggest modifications to improve model predictions for high-speed flows. Numerical simulations of turbulent ow past a at plate are performed at M1 = 2:25; 7:2.The results from these two Mach number cases are compared with Direct NumericalSimulation (DNS) results from Pirozzoli et al. (2004) and experimental results fromHorstman & Owen (1975). The effect of the Boussinesq coefficient (Cu) and turbulenttransport coefficients (sigmak; sigmaE; sigma; sigma*) on the boundary layer ow is examined. Further,the performance of a new model with realizability-based correction to Cu and corresponding modifications to sigma; sigma* is examined. The modification to Cu is based oncontrolling the ratio of production to dissipation of kinetic energy (P/E=1). The firstchoice of P/E = 1 ensures that there is no accumulation of kinetic energy in stagnation or free-stream regions of the ow. The second choice of P/E= 1:6 holds underthe assumption of a homogeneous shear ow. It is observed that the new model'sperformance is similar to that of the existing RANS models, which is expected for asimple ow over a at plate. Finally, the role of turbulent Prandtl number (Prt) intemperature and density predictions is established. The results indicate that the k-wmodel's performance is better compared to that of the standard k-E model for highMach number flows. A modification to Cu must be accompanied with correspondingchanges to sigmak; sigmaE; sigma; sigma* for an accurate log-layer prediction. The results also indicate that a Prt variation is required across the boundary layer for improved temperatureand density predictions in high-speed flows.

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The objective of this thesis is to provide the systematic design procedure for a high-speed PM motor with portable sizes, along with the detailed mathematical model developments and the thorough operational analysis. The entire scheme is realized by first following an available design reference to estimate the desired machine physical structures. Then, based on the related field theory, recoil line characteristics of permanent magnets, and the magnetic equivalent circuit method, the system mathematical model can be devised. Finally, the system operational behaviors can be investigated by the devised analytical models, and their accuracies will also be confirmed by the reference design tool. It is believed that the proposed design and verification scheme can provide a valuable and reasonable guidance for the related industry application.

The high speed machining is now recognized as one of the key manufacturing technologies. It possesses several better characteristics than those of a conventional machining way. For example, low chip load, and low cutting-heat generation can be obtained. It also contributes to high productivity and throughput. In this thesis, the technique about the high speed machining for cutting the aluminum thin-walled components will be discussed. An audio signal measuring system will be established to measure sound pressure for avoiding chatter. Meanwhile, the tool path will also be revealed in this thesis.

Abstract In this thesis, the variation of the natural frequencies of a drill during the high speed drilling processes has been investigated. The Pro-E and MARC finite element packages were used to formulate the twisted drills. Two numerical methods,i.e. Lanczos and Inverse Power Sweep, have been employed to solve the corresponding eigen value problems.The effects of following parameters,e.g. drilling speed,axial load and drilling conditions on the natural frequencies of a drill was simulated numerically and measured experimentally. Four springs with different spring stiffness attached on the drill tip is used to simulate the drill as it penetrated into the workpiece. The variation of the drilling responses under different drilling speeds have been measured. Results indicate the measured results agree very well with the measured data.Frequency spectrum distributions indicate the drilling frequency and the twice drilling frequency are the key response frequency of the axial thrust force, and the drill of frequencyisthe only key frequency which dominates the torque response.Experimental results also show the thrust forces estimated from the empirical equation have good correlation with these measured data.

Just like Eurotunnel link England & France, by the time Taiwan high speed rail arrive at Kaohsiung and Taipei , the passengers and people at platform welcoming the train, both feel exciting of this tremendous improvement of Taiwan. Taiwan have two highways and a railway for connecting Kaohsiung and Taipei despite many roads that have constructed long before. Even there also has plane to catch if you need time. Therefore, Taiwan high speed rail is a high-tech spine for new era of Taiwan. The distance between Taipei and Kaohsiung is merely 300 kilometer . Unfortunately Southern Taiwan and Kaohsiung didn¡¦t get sources from government fairly the old days. Now through this high ¡Vtech spine Kaohsiung and southern Taiwan can step forward proudly embracing future. Southern Taiwan had Kaohsiung Export Processing Zone and many industrial zones by local government , are not enough for use. Recently Southern Taiwan Science Park and Kaohsiung Software Park and Pingtung Agricultural Biotechnology Park all are built to meet future need. Enterprise can run business in these parks at lower cost than Northern Taiwan. Also , there are many solutions offer by government to help company and enterprise to improve and move in southern Taiwan. This study interview southern Taiwan companies and enterprises. From their point of view to see Taiwan high Speed Rail this modern technologic transportation create new opportunities for southern Taiwan. And bring lesson and suggestion for the future.