prepared by Ling Hok Sun, Lawrence. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Abstract also in Chinese. / Chapter 1. --- Abstract --- p.2 / Chapter 2. --- Introduction --- p.3 / Chapter 3. --- Circuit Description --- p.8 / Chapter 4. --- Technology' --- p.10 / Chapter 5. --- Design --- p.13 / Chapter 5.1 --- TOP LEVEL --- p.13 / Chapter 5.2 --- Logic --- p.14 / Chapter 5.3 --- Tuner --- p.19 / Chapter 5.4 --- Gate Drive and Power Switch --- p.26 / Chapter 5.5 --- Full-Circuit Simulation --- p.43 / Chapter 6. --- Layout --- p.53 / Chapter 7. --- Characterization --- p.55 / Chapter 8. --- Conclusion --- p.65 / Chapter 9. --- Reference --- p.66 / Chapter 10. --- Appendix --- p.67

This thesis contains a study of improvement and application of strain measurement technique using neutron diffraction. A dedicated neutron strain scanner - ENGIN, funded by Ee. has been developed at ISIS. It has two radial collimators, allowing for the first time, measurements taken simultaneously at two orthogonal directions; uses Pawley refinement permitting both whole pattern and individual peak profile analysis and its positioner allow's specimens weighing 250 kg to be placed with an accuracy of 100 um. Strain measurement using neutron diffraction has been investigated under two extreme circumstances: very shallow (within 1 mm near surface) and very deep in materials (hundred of mm). Near-surface measurement requires both the accurate determination of the effective measurement position associated with precise location of specimen, calculation of centroid and correction for an anomalous near-surface effect. The strain measurements on a shot-peened surface in titanium alloy were carried out using the methodology mentioned above. The result is comparable to that obtained from X-ray diffraction. The latter was exploited by studying the effect of wavelength-dependent attenuation in materials. Experiments and theoretical analysis on aluminium and iron show that the effect is small for a strain scanner using radial collimator and time-of-flight technique. However, the reduction of the diffraction peak intensity, as a function of the amount of material in the beam path, reveals that great care should be taken when measuring texture as a function of depth in materials. The neutron diffraction technique was applied to several sets of engineering strain measurements. Firstly, 3-D residual stresses surrounding a cold expanded hole in a high strength aluminium alloy plate were measured. The result agrees well with that from modified Sachs' method after taking the effect of gauge volume averaging into account. Second, measurements of strain distributions in a Q-joint under zero and 30 kN load have been carried out, which provides a confirmation of the excellence of the joint design as the fastener system has completely shielded the fastener hole from deleterious tensile strains under operational loading. Finally, calibration strain measurement for an energy dispersive neutron transmission spectrometer was performed for the first time and it is found that the transmission spectrometer is feasible for strain and phase transformation measurement.

The aim of the work described in this thesis was to improve NCR's decision making process for progressing software products through the development cycle. The first chapter briefly describes the software development process at NCR, detailing documentation review and software testing techniques. The objectives and reasons for investigating software reliability models as a tool in the decision making process are outlined. There follows a short review of software reliability models, with the Littlewood and Verrall Bayesian model considered in detail. The difficulties in using this model to obtain estimates for model parameters and time to next failure are described. These estimation difficulties exist using the model on good datasets, in this case simulated failure data, and the difficulties are compounded when used with real failure data. The problems of collecting and recording failure data are outlined, highlighting the inadequacies of these collected data, and real failure data are analysed. Software reliability models are used in an attempt to quantify the reliability of real software products. The thesis concludes by summarising the problems encountered when using reliability models to measure software products and suggests future research into metrics that are required in this area of software engineering.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

The problems associated with single sideband (SSB) radio transmitters are primarily those of achieving both a spectrally clean output and a high DC to RF conversion efficiency. In the majority of applications the linearity of a transmitter is considered to be a more important requirement than efficiency, making the transmitter a poor convertor of DC into RF energy. An approach whereby both good linearity and efficiency may be obtained is known as the Polar-Loop Technique in which a large amount of negative feedback may be applied to a radio transmitter without compromising the stability of the RF amplifiers. This is achieved by resolving the SSB signal into polar coordinate form to produce two signals: one proportional to the instantaneous amplitude of the RF signal and the other to its instantaneous phase. These component are functions of the modulating signal and have bandwidths which are much lower than those of the RF circuits. By applying feedback in each component the excess phase shift introduced by the RF circuits into the feedback loops is small and consequently, a large amount of feedback may be employed without causing instability. This thesis is primarily concerned with the application of the Polar-Loop Technique to high frequency (HF) SSB radio transmitters. The early chapters of this thesis discuss the important aspects of HF transmitter design, practice and constraints together with methods of improving the linearity or efficiency of such transmitters. Subsequently, the Polar-Loop Technique is introduced and the properties and potential sources of spurious emissions from transmitters of this type are described. Several possible transmitter configurations suitable for broadband HF applications are presented and the problems associated with the implementation of HF Polar-Loop Transmitters are outlined. In order to demonstrate the properties and capabilities of transmitters based on the Polar-Loop Technique a 100 W broadband HF unit has been designed and evaluated and the results obtained using this transmitter are presented and described in detail.

by Lam Hiu-fung. / "Augustr 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 178-182). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Digitized by Kansas Correctional Industries

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

A project report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / Underground chilling installations have an important role in deep mining operations because the total cost of cooling a mine is minimized when underground machines deliver as high a proportion of the required cooling as practicable. Thus the refrigerating load of an underground installation should be maximized to the extent permitted both by the environment in which the installation operates, and by the physical characteristics of the machines in the installation. This study analyses how, and to what extent, the refrigerating load of older, already installed water chilling machines rejecting heat into a limited supply of return water may be maximized through configuration of their water circuits and capacity control of their compressors. Multiple-machine installations are simulated in a range of scenarios, using the thermodynamically efficient series-counterflow arrangement, to predict both the potential maximum refrigerating load and the expected refrigerating load of such installations. The simulation results indicate significant potential for installations to chill water more efficiently and thus deliver larger, maximized, refrigerating loads. For scenarios where a larger-than-design flowrate of return water is available, so permitting machines to be operated with little or no capacity control, the simulated chilling efficiency and thus the expected refrigerating loads tend toward, and in some cases almost match, the potential maximum values. For simulations in which compressor capacity control is used to prevent the return water temperature from exceeding its maximum permitted value, expected refrigerating loads fall short of their potential values, by varying amounts, due to the low machine cycle efficiency caused largely by reduced compressor isentropic efficiency at part load. For a limited supply of return water for heat rejection, the simulations indicate that load maximization efforts should focus on the machines in an installation being connected in a series-counterflow arrangement and operated, as far as practicable, at or near full capacity to create the best prospect for approaching potential maximum refrigerating load.