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Significant progress toward a functional 73 element, 730 watt, active microwave phased array has been made. This array, designed for medical hyperthermia applications, has significant size restrictions leading to a novel space conscious design. Unlike other hyperthermia devices, each array element is designed to have full 360° phase control with better than 1° resolution. Full amplitude control, with 10 bit amplitude resolution is implemented. The array is designed to operate in the 2.45 GHz ISM band. Measured operational data is presented and is compared to simulations performed with Compact Software's Microwave Harmonica®. A sophisticated control system for the array has been designed, built and tested. The system provides 160 computer controlled 10 bit analog control lines to drive the array. Sampling of various system parameters is made possible through the use of a 96 channel, 12 bit analog to digital converter system. This system provides 4 mV resolution and a 440 Hz sampling rate for each of the 96 measurement channels.

A near-infrared spectrometer incorporating solid-state design applicable for industrial quantitative/qualitative process monitoring analysis is presented. The solid-state near-infrared spectrometer provides inherent wavelength stability necessary for long term calibration accuracy. The spectrometer consists of a 24 volt, 10 watt quartz-halogen-tungsten regulated source with optical feedback. Wavelength dispersion was accomplished using a 50 μm entrance slit, f/4, 0.25 meter spectrograph equipped with astigmatism correcting toroidal mirrors and a 300 gr/mm plane reflectance ruled grating blazed for 2000 nm peak efficiency. A 1024 element backside- illuminated Schottky-barrier PtSi photodiode array detector with wavelength response from 900-5000 nm and peak quantum efficiency of 8% at 1100 nm was operated using cryogenic cooling to reduce dark response. A readout rate of 31.25 kHz produced 41 msec integration time per array read. The readout was digitized to 16 bit resolution for subsequent data storage. This system demonstrated 1.5 nm spectral bandpass, 3 orders linear dynamic range and typical baseline rms noise level of 10⁻⁴ a.u. Using this system, quantitative/qualitative chemical analyses were performed focusing on industrial analytical chemical applications. Simultaneous quantitative multcomponent xylene isomer mixtures analysis was achieved using the solid-state near-infrared spectrometer coupled with partial least squares regression multivariate data treatment. The results demonstrate an absolute accuracy of ± 0.05, ±0.12 and ±0.09% w/v for o-, m- and p-xylene isomers respectively. In a separate chemical study, qualitative classification analysis of specially denatured alcohol mixtures was successfully performed on 53 validation samples using 35 reference samples belonging to 12 classes. The validation set included mixture sample types used for model calibration as well as others composed of compounds not used for model calibration. The multivariate cluster classification method using principal components was employed to correctly classify 100% of the validations samples analyzed. The solid-state near-infrared spectrometer was also applied for direct reaction monitoring of the O-H overtone absorption band at 1411 nm for the reaction between triisopropyl-chlorosilane and methanol. The results illustrated the utility of near-infrared functional group monitoring of reactions at relatively high concentrations for information elucidation concerning reaction initiation and completion.

The alternative components in an electric/flywheel propulsion system are reviewed, including different continuously variable transmissions (CVT's), and a new arrangement is proposed for electric vehicles, called the "Sussex propulsion system". Computer simulations are developed which show the effects of using flywheel energy storage, as opposed to electrical regenerative braking, for a large urban delivery van, which originally incorporated an electronically-controlled motor. Vehicle performance and energy consumption are compared over different driving cycles, and the result of varying the flywheel energy capacity is shown. The design and operation of an experimental rig is described and the experimental results are compared with those obtained from a computer simulation,, in order to test the validity of the mathematical models. The results show that for urban use, an electric delivery van fitted with the Sussex propulsion system has a substantially reduced energy consumption and better performance than a comparable conventional electric vehicle. Therefore, an electric vehicle in the future would require a smaller, cheaper installed battery pack or would have a greater range between recharging.

A Turbo-Pascal program has been developed that will aid a circuit designer to determine which of a set of "real" circuits will best match the associated "ideal" circuit or in choosing components for a given circuit. Study one examined the Sallen and Key second-order active low-pass circuit. Wn (mean), Wn (standard deviation), Q (mean), and Q (standard deviation) were examined as a function of Q desired, distribution type and component tolerance. The sensitivity of the circuit was calculated both numerically and through program execution. In Study two a set of reference graphs were generated to compare several second order low pass, high pass, and band pass filter classes as a function of component distribution and tolerance. Study three compares the behavior of several orders of low pass MFM (Maximally Flat Magnitude) Leapfrog filters. Amax (maximum gain), Wmax (frequency of maximum gain), and the 3dB frequency were examined. (Abstract shortened with permission of author.)

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This thesis is concerned with two main lines of work which have followed parallel and complementary paths. The first one consists in using the technique of subharmonic sampling to investigate the frequency stabi lity of microwave oscillators using a convenient low frequency replica. The second line has been concerned with a detailed study of the Allan variance and the dependence of this variance on the operation of digital frequency counters, with special emphasis on the effects of 'dead-time'. This has led to the concept of an 'extended' variance over a time window NT obtained by averaging elementary estimates over a window T. After Chapter 1 which contains an overview of the basic concepts of frequency stability and summarises current measurement systems, Chapter 2 discusses in detail the operation of digital frequency counters and related mathematical modelling of the operation. As indicated above the chapter concludes with an original method of obtaining an extrapolated measurement of the two pair Allan variance. Chapter 3 extends the sampling theory to the down-conversion of a microwave signal using trapezoidal pulses with the objective of generating a low frequency replica. Recovery of the sampled signal, optimisation techniques and noise limitations are discussed in detail. Based on these considerations Chapter 4 explains the experimental equipment developed; it allows a microwave signal of up to 3 GHz to be translated down into the range 5 MHz to 7.5 MHz using a sampling gate driven by a variable width pulse generator coherent with a highly stable 5 MHz clock. Chapter 5 discusses the data acquisition and processing together with the calibration and checks of the experimental apparatus. Verification of the operation showed good agreement with the theoretical calculations and with an alternative mixing technique. The thesis concludes with Chapter 6 where after a detailed overview of the research work suggestions are given for further work.

<p> Power system is the backbone of modern society. Traditionally, over 90% of the electrical energy is produced by power generation systems driven by steam turbines. Recently, with the development of renewable energy resources, wind energy conversion systems are the proven solutions for the next generation sustainable energy resources. Stability and performance of these power systems are the primary concerns of power system engineers. To better characterize the dynamical behaviors of power systems in practical applications, time delays in the feedback state variables, systems modeling uncertainties, and external disturbances are included in the state space model of the power system in this work. Linear matrix inequality based robust and resilient controllers satisfying the H_infinty performance objective for time delayed power systems are proposed. Fixed time delays are assumed to exist within the system state and input signals. The system model is assumed to have unstructured bounded uncertainties and L_2 type of disturbances. Furthermore, controller gain perturbations are assumed to be of additive type. The proposed control techniques have been applied to variable speed permanent magnet synchronous generator based wind energy conversion systems, and electrical power generation systems driven by steam turbine. Computer simulations conducted in MATLAB show the eectiveness of the proposed control algorithms.</p>