Engineering

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  • A basis for optimal irrigation systems design, operation and evaluation
    (1984) Chalomba, Christopher Mukundanji
    Thesis
  • Studies in electron phenomena in MOS structures the pulsed C-V method
    (1983) Kaplan, G.
    Thesis
    C-V methods for the investigation of electron phenomena in MOS structures have shown great advances as the theory of the semiconductor-oxide interface developed. From 1962 to about 1975 attention was concentrated on quasiequilibrium C-V methods, i.e. the H-F C-V method and the LF C-V method. The pulse C-V method was used mainly for the investigation of the transients in MOS capacitance caused by minority charge carriers. The most noticable attempt to use the pulse technique for the surface state measurements was made by Muller and Shick in 1970. Recently, owing to the development of the theory of MOS structures and experimental techniques, the C-V method has been further developed. For example, deep level pulse spectroscopy and also the pulse hysteresis C-V method originated by the author of this work. The latter is presented and developed in this thesis. The pulse hysteresis C-V method provides a straight-forward technique for measuring the change of various charges in MOS structures and a tool for investigating the kinetics of various electron phenomena. For example, the pulse hysteresis C-V method can be used for measuring the energy distribution and kinetics of surface states with the resolution of about 5x10-9cm eV-1. A theoretical investigation is also presented of some transients in an MOS structure, particularly, the thermal generation of minority charge carriers via surface states and the relaxation of minority charge carriers supplied from the inversion layer outside the MOS structure. This investigation resulted in derivation of the analytical expressions which clearly present the physics of those electron phenomena.
  • A review of bank protection methods in N.S.W.
    (1983) Dooley, B. T.
    Thesis
  • Sand ripples under natural waves
    (1984) Nielsen, A. F.
    Thesis
    This report presents data on forty three bedforms generated on medium to coarse sandy beds under natural wave motions. The data comprise measurements of ripple lengths, heights and crest orientations, assessments of sediment activity, and associated hydraulic conditions measured by waverider bouys and electromagnetic current meters. The data are limited in that they were obtained at a single water depth (approximately 24 m) under low wave conditions (Hs < 1.5 m and 7 s < T < 14 s). Interpretation of the data, however, could be generalised to a limited extent through the application of dimensional analysis techniques. The field data are assessed in the light of other limited field data and the extensive laboratory data set with a view to determining the appropriate statistical parameters describing natural wave spectra to be used for predicting bedform size and sediment activity under natural wave motion. The results indicate that the size of wave-generated bedforms can be predicted approximately from natural, wave-induced, near-bed, velocity spectral data if periods corresponding to the frequencies at which the spectral energy densities peak are used with values of near-bed orbital displacements (or velocities) approximately twice those of the "significant" displacement parameters, and D50 for the sediment grain size, in conjunction with the laboratory-determined bedform curves presented by Mogridge and Kamphuis (1972). A rippled bed incipient motion criterion is developed empirically from the field data using dimensional analysis techniques. This criterion incorporates the contribution to boundary shear stress made by the presence of bedforms as well as particle size. The report also presents some limited results on the comparison of simple numerical refraction methods with field waverider and electromagnetic current meter data, and comparisons between surface wave spectra and simultaneous, near-bed velocity spectra in 24 m water depth.