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Thesis (Ph.D.)--Tennessee Technological University, 2007. / Bibliography: leaves 99-102.

"An iron wire, 12000 feet in length, was suspended about five feet from the ground by silk cords; one end of it was connected to the globe of an electrical machine, and at the other a lead ball was hung in order to perceive when the matter reached it. After five or six turns of the wheel, the matter had passed along the whole wire and communicated its virtue to the ball, which instantly attracted and repelled light bodies. 2. As this ball was equally electrified with every part of the wire, it is probable that the electric matter would instantly pervade a wire of a still greater length, provided we had a proper apparatus for the purpose. 3. Several metals and other conductors were substituted in place of the ball, and all received the electricity in the same manner. The ball and touched with other non-conductors, :when' the finger, gave a luminous spark and as smart a shock as when the end of the wire next to 'the 'gTobe·vas touched. All these effects instantly ceased whenever .. any person not electrified touched any part of the wire and commenced again a few seconds after his hand was withdrawn. The same effects are produced, though with more difficultly, when hair or woollen ropes were substituted in place of the silk ones: But they were entirely stopped by hemp ropes or when the silk ones were wetted."

Epoxy res~ a major component of solid electrical insulation systems, degrades when subjected to electrical discharges. Identification of the epoxy resin degradation mechanism might indicate improvements which can be made in the chemical formulation of the resin to enhance the insulation systems. Samples of a commonly used epoxy res~ bisphenol-A epoxy crosslinked with phthalic anhydride, were manufactured and then aged by applying lOkV AC to an electrode 2mm above the resin surface. The following experimental conditions were altered: manufacturing system: (i) moulded slab and (ii) slice cut from moulded cylinder; atmosphere: (i) nitrogen, (ii) dry, (iii) normal and (iv) moist air; high voltage electrode:(i) brass and (ii) copper. In addition, ageing due to chemical, thermal and radiative stressing was also examined. The changes in the stressed resin samples were determined using the following techniques: diffuse reflectance Fourier Transform infrared spectroscopy (DRIFT), attenuated total reflectance FTIR (ATR-FTIR), thermogravimetric analysis (TGA), thermogravimetric FTIR (TG-FTIR) and atomic force microscopy (AFM). The changes in the electrode materials were determined using X-ray diffratometry (XRD) and Fourier Transform infrared (FTIR) techniques. The method of production of the specimens was shown to affect the degradation. Silicone release agent, used in the moulding of the resin slabs, was found on the surface of degraded moulded resin slabs: the contamination of the moulded samples was not detectable prior to partial discharge stressing. Crazing and flaking of the stressed resin surface were found on the moulded slabs but not on the slices of resin. Anhydride, acid and amine species were identified on the surface of the electrically stresses resin slices. Chemical reactions accounting for the changes found on the surface of the stressed resin slices are given. The radical species formed by methyl group dissociation, reacting with hydroxyl and activated oxygen species, lead to the formation of linear anhydrides, acids and peracids on the resin surface. Reactive nitrous oxide species in the discharge atmosphere react with the resin to form amines. Zinc formate dihydrate was identified on brass electrodes after the resin ageing process, whilst basic copper nitrate was identified on copper electrodes. The difference in deposit found on the electrode indicates that zinc reacts with carbon species from the discharge environment; copper reacts, not with carbon species, but with nitrogen species. The variation in chemical interaction at the high voltage electrode, dependant upon electrode material, has been found to correlate with changes on the resin surface. Correlations are made between the effects of partial discharge and other stresses applied. None of the applied stresses generated the anhydride structure found in partial discharge stressed resin samples. However, in common with p.d. stress, UV radiation increases the level of crosslinking in the epoxy resin and produces carbonyl structures, nitric acid fumes produce acid, peracid and nitroso structures.

This research thesis involves the measurement of the airborne sound insulation of road traffic noise barriers, with the goal of gaining a more in depth understanding of the factors that influence noise barrier performance. A measurement system is developed, based on EN 1793-6:2012, to quantify the airborne sound insulation of a noise barrier in situ. Validation testing is performed to ensure that the system meets the requirements of EN 1793-6:2012. MATLAB code is developed, incorporating all of the signal processing tasks into a single graphical user interface. The measurement system is then used to measure the airborne sound insulation of eight existing traffic noise barriers located around Auckland, New Zealand. The results from the Auckland field tests show that consistent single number ratings of airborne sound insulation can be achieved on different samples of the same noise barrier. The presence of air gaps and hidden defects will degrade the acoustic performance of a noise barrier, most significantly at the high frequencies. The comparison of single number ratings calculated with differing measurement frequency ranges is discussed, and some comments are made on the measurement standard itself.

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