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This thesis describes a new method of measuring dielectric constants and loss tangents using an open resonator. The dielectric constant measurement method consists basically of perturbing the resonant frequency of an open resonator by placing a dielectric sample at the centre of the resonator normal to its axis. By measuring the resonant frequency of a symmetrical mode and of the adjacent lower-frequency asymmetrical mode, the dielectric constant can be determined. Based on the Gaussian beam theory, a pair of transcendental equations, one for each mode, are derived by assuming first the surfaces of the dielectric sample are spherical and coincident with the phase fronts of the resonator modes. These equations can easily be solved for the refractive index n, by using a computer. When sample in sheet form is measured, the results can be corrected to account for the error so introduced. The formula giving this correction is derived by using the perturbational technique. From these two equations, two sets of approximate formulas are also derived for the determination of the dielectric constant. An important feature of these formulas is that they are algebraic expressions, but reduction in their accuracy occurs if the sample is nearly a multiple of half wavelengths thick. The loss tangent is determined by the measurements of Q of the perturbed and the unperturbed resonator. Based on the usual definition of Q, an algebraic-expression is derived relating the loss tangent to the experimentally measurable quantities. Measurements of dielectric constants and loss tangents of polystyrene and perspex have been made at X-band frequencies and the results are presented. It is on these results that the accuracy of ±0.25% for measuring dielectric constant is claimed. The accuracy of the loss tangent measurement is estimated to be about ±10%. The method is applicable to the measurements of both low-loss and high-loss materials, and becomes more accurate at shorter wavelengths.

The anodic behaviour of lead in sulphuric acid was examined using the potentiodynamic method. Simultaneous diffusion-in- solution and solid-state reactions were suggested to account for the observed behaviour. The contribution of each process being determined by the sweep rate. The effects of different anions added to the sulphuric acid solutions on the anodic behaviour of lead were studied.

Testing low power very large scale integrated (VLSI) circuits has recently become an area of concern due to yield and reliability problems. This dissertation focuses on minimising power dissipation during test application at logic level and register-transfer level (RTL) of abstraction of the VLSI design flow. The first part of this dissertation addresses power minimisation techniques in scan sequential circuits at the logic level of abstraction. A new best primary input change (BPIC) technique based on a novel test application strategy has been proposed. The technique increases the correlation between successive states during shifting in test vectors and shifting out test responses by changing the primary inputs such that the smallest number of transitions is achieved. The new technique is test set dependent and it is applicable to small to medium sized full and partial scan sequential circuits. Since the proposed test application strategy depends only on controlling primary input change time, power is minimised with no penalty in test area, performance, test efficiency, test application time or volume of test data. Furthermore, it is shown that partial scan does not provide only the commonly known benefits such as less test area overhead and test application time, but also less power dissipation during test application when compared to full scan. To achieve power savings in large scan sequential circuits a new test set independent multiple scan chain-based technique which employs a new design for test (DFT) architecture and a novel test application strategy, is presented. The technique has been validated using benchmark examples, and it has been shown that power is minimised with low computational time, low overhead in test area and volume of test data, and with no penalty in test application time, test efficiency, or performance. The second part of this dissertation addresses power minimisation techniques for testing low power VLSI circuits using built-in self-test (BIST) at RTL. First, it is important to overcome the shortcomings associated with traditional BIST methodologies. It is shown how a new BIST methodology for RTL data paths using a novel concept called test compatibility classes (TCC) overcomes high test application time, BIST area overhead, performance degradation, volume of test data, fault-escape probability, and complexity of the testable design space exploration. Second, power minimisation in BIST RTL data paths is achieved by analysing the effect of test synthesis and test scheduling on power dissipation during test application and by employing new power conscious test synthesis and test scheduling algorithms. Third, the new BIST methodology has been validated using benchmark examples. Further, it is shown that when the proposed power conscious test synthesis and test scheduling is combined with novel test compatibility classes simultaneous reduction in test application time and power dissipation is achieved with low overhead in computational time.

This thesis describes a research investigation into novel probes for the measurement of ultra-fast voltage pulses with a peak value up to 500 kV, and during the course of the work five probes were constructed for voltages of between 60 kV and 500 kV. Essential requirements of the probes are that they should be immune to high-levels of electromagnetic noise and also isolate the measuring equipment from the high voltage of the test circuit. Their designs were therefore based on an electro-optic (Pockels) Cell rather than on an electromagnetic device. The first item in the probe is a capacitive divider that attenuates the high-voltage under investigation to the level that can be fed to a Pockels Cell. Light from a laser is circularly polarized and passes through the Cell, with the attenuated voltage pulse causing the Cell crystal to change its molecular shape. This produces a change in the refractive index of the crystal and the emerging light signal becomes elliptically polarized. After conversion into electrical form, a waveform is displayed on an oscilloscope that is an accurate representation of the input voltage to the capacitor. To test the performance of a probe requires a generator capable of producing the required high voltage with a very short rise time, and a number of these were developed for use with the different probes. Careful comparisons of the performance with that of several commercially available probes showed unequivocally that the new probes were far superior. The thesis concludes by presenting ideas for future probe designs and suggests what form the ultimate probe might take. Much of the work reported in the thesis has already been presented at major international conferences or in prestigious academic journals.

The popularity of the variable-speed induction machine as a drive mechanism has increased rapidly. This has led to the voltage source inverter induction machine being used to drive numerous applications such as electric vehicles and trains. Unfortunately, the condition monitoring and fault detection of these types of drives is an area, which has been left largely untouched by the research community. This is due to the high harmonic contents of the machine supply making the rigorous mathematical analysis of the drive complex. Fortunately, the interesting development in signal processing theory, especially wavelet transform, has sparked a new interest in condition monitoring of voltage source inverter induction machine. The wavelet transform have two important features, which, are important for the condition monitoring and fault detection purpose; time localization ability and multi-resolution analysis. Furthermore, the wavelet can be combined with an artificial intelligent system to provide an acceptable system with high accuracy and reliability. The work herein presented is a contribution to voltage source inverter induction machine condition monitoring and fault detection using the combination of wavelet transform and fuzzy logic. The research was concentrated on some typical fault events of voltage source inverter that allow reduced operating conditions of the drive system without triggering the short circuit protection.

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