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Thesis (M.S.)--Ohio University, August, 1981. / Title from PDF t.p.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 23, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Scott D. Kovaleski. Vita. Includes bibliographical references.

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Power consumption and soft-error tolerance have become major constraints in the design of DSM CMOS circuits. With continued technology scaling, the impact of these parameters is expected to gain in significance. Furthermore, the design complexity continues to increase rapidly due to the tremendous increase in number of components (gates/transistors) on an IC every technology generation. This research describes an efficient and general CAD framework for the optimization of critical circuit characteristics such as power consumption and soft-error tolerance under delay constraints with supply/threshold voltages and/or gate sizes as variables. A general technique called Delay-Assignment-Variation (DAV) based optimization was formulated for the delay-constrained optimization of directed acyclic graphs. Exact mathematical conditions on the supply and threshold voltages of circuit modules were developed that lead to minimum overall dynamic and static power consumption of the circuit under delay constraints. A DAV search based method was used to obtain the optimal supply and threshold voltages that minimized power consumption. To handle the complexity of design of reliable, low-power circuits at the gate level, a hierarchical application of DAV based optimization was explored. The effectiveness of the hierarchical approach in reducing circuit power and unreliability, while being highly efficient is demonstrated. The usage of the technique for improving upon already optimized designs is described. An accurate and efficient model for analyzing the soft-error tolerance of CMOS circuits is also developed.

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M.Ing.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The validity of the atmospheric correction method presented in the IEC 60060-1 (2010) standard is analysed and evaluated by means of theoretical and laboratory work. In order to understand the problem, the evolution of the atmospheric correction methods, from as early as 1914, has been presented. A procedure (Calva prediction method) for predicting the direct current (DC) breakdown voltage for an air gap at any altitude was discovered and was also analysed along with the IEC 60060-1 (2010). A critique of some of the atmospheric correction methods commonly used standards was also done. Experiments were carried out at altitudes of 1 740 m (Wits University), 130 m (UKZN HVDC centre) and at less than 2 m above sea level (Scottburgh beach, Clansthal). More tests were conducted using a pressure vessel where high altitude relative air density was simulated. All tests were conducted on rod-plane air gaps using a 15 mm diameter at tip rod. Test results from Scottburgh beach were used as the standard breakdown voltages of the air gaps tested since the environmental conditions were the closest to the conventional standard conditions (stp). The test results obtained were compared with predictions using the Calva method in order to validate the method. The test results were also corrected according to IEC 60060-1 (2010) and compared to the standard breakdown voltages obtained at Scottburgh beach. It was shown that the IEC 60060-1 (2010) is quite suitable for atmospheric correction for data obtained at low altitudes (about 130 m). When applied to high altitude (1 740 m) data, the correction method is accurate and suitable for very small air gaps less than 0.1 m. As the air gap length increased, the corrected results began to deviate from the expected standard voltage. The same trend was shown with the corrected results from the pressure chamber tests. The prediction method by Calva was accurate when compared to the experimental data from the high altitude and low altitude test results. When compared to the data from the pressure chamber, the prediction method had a linear error factor which was di erent for each gap length. It was concluded that the IEC 60060-1 (2010) is not only unsuitable for atmospheric correction for data at relative air densities below 0.8, but also that the correction method is prone to an increase in error as the air gap length increases when the relative air density is higher than 0.8. The Calva prediction method was found to be suitable to use after additional factors are added when applied to high altitude conditions. / GR2016

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