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Simulation And Modelling Of Thin Film Phi(Rho-Z) Curves For Electron Probe Microanalysis, Ka Shing Chan
Simulation And Modelling Of Thin Film Phi(Rho-Z) Curves For Electron Probe Microanalysis, Ka Shing Chan
Digitized Theses
Quantitative analysis of homogeneous bulk unknowns using an electron probe microanalyzer requires the accurate knowledge of the depth distributions of x-ray production ({dollar}\phi{dollar}({dollar}\rho{dollar}z) curves). Straight line behaviour is observed in the plot of ln{dollar}\phi{dollar}({dollar}\rho{dollar}z) versus ({dollar}\rho{dollar}z){dollar}\sp2{dollar} for most experimentally measured data. Monte Carlo calculations can be used to simulate {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves. However, ln {dollar}\phi{dollar}({dollar}\rho{dollar}z) versus ({dollar}\rho{dollar}z){dollar}\sp2{dollar} plots of these {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves, in general, are nonlinear and concave downward. By introducing the concept of electron straggling into a multiple scattering Monte Carlo model, agreement with the behaviour of experimental curves is achieved.;Electron probe microanalysis can also be used for the characterization …
Adaptive Non-Linear Predictive Control, Edward Katende
Adaptive Non-Linear Predictive Control, Edward Katende
Digitized Theses
Most predictive control algorithms, including the Generalized Predictive Control (GPC) (Clarke et al. 1987) are based on linear dynamics. Many processes are severely non-linear and would require high order linear approximations. Another approach, which is presented here, is to extend the basic adaptive GPC algorithm to a non-linear form. This provides a non-linear predictive controller which is shown to be very effective in the control of processes with non-linearities that can be suitably modelled using general Volterra, Hammerstein and bilinear models. In developing this algorithm, the process dynamics are not restricted to a particular order as is the case with …
Chemistry Of Antiwear Films By X-Ray Absorption Spectroscopy, Zhanfeng Yin
Chemistry Of Antiwear Films By X-Ray Absorption Spectroscopy, Zhanfeng Yin
Digitized Theses
The antiwear and antioxidant additives, zinc dialkyldithiophosphates (ZDDPs), are an essential ingredient in engine oil formulations, and have been in use for many years. These additives function by forming antiwear films on surfaces in sliding contact, and thus reduce friction and wear. Among the surface techniques employed, X-ray absorption spectroscopy (including EXAFS and XANES) has been mainly used because of its high resolution, low detection limit and non-destructive characteristics.;This is the first time that P and S L-edge XANES spectroscopy has been used to analyze antiwear films and thermal films. About two hundred antiwear films and thermally prepared films have …
High Temperature X-Ray Diffraction Investigation Of The Beta-(Bismuth(2) Oxygen(3))(1-X)(Strontium Oxide)(X) Solid Solution, Edward Andrew Payzant
High Temperature X-Ray Diffraction Investigation Of The Beta-(Bismuth(2) Oxygen(3))(1-X)(Strontium Oxide)(X) Solid Solution, Edward Andrew Payzant
Digitized Theses
To investigate the controversial {dollar}\beta\sb1\leftrightarrow\beta\sb2{dollar} phase transformation in the {dollar}\beta{dollar}-{dollar}\rm (Bi\sb2O\sb3)\sb{lcub}1-x{rcub}(SrO)\sb{lcub}x{rcub}{dollar} phase, a series of compositions across the phase were prepared by conventional grinding, pressing and firing ceramic techniques. Electrical conductivity measurements demonstrated that the samples were comparable to those used in other laboratories. X-ray diffraction analysis confirmed that the cations are located on a hexagonal sublattice, but details of the anion sublattice could not be resolved, because of the low X-ray scattering factor of {dollar}\rm O\sp{lcub}2-{rcub}.{dollar};The compositional dependence of the lattice parameters of the hexagonal crystal structure of the {dollar}\beta{dollar}-{dollar}\rm (Bi\sb2O\sb3)\sb{lcub}1-x{rcub}(SrO)\sb{lcub}x{rcub}{dollar} phase, which was determined at {dollar}27\sp\circ\rm C{dollar} using …
The Initial Interaction Of Water Vapour With Magnesium And Magnesium Alloy Surfaces, Steven Joseph Splinter
The Initial Interaction Of Water Vapour With Magnesium And Magnesium Alloy Surfaces, Steven Joseph Splinter
Digitized Theses
The initial interaction of water vapour with polycrystalline magnesium and magnesium alloy surfaces has been quantitatively followed from the earliest stage using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The fitting of AES data to theoretical models suggested that a three-stage oxidation behaviour was operative on pure Mg surfaces: (1) dissociative chemisorption during doses up to {dollar}{lcub}\approx{rcub}0.7{dollar} langmuir (L) (1L = {dollar}1.3\times10\sp{lcub}-4{rcub}{dollar} Pa{dollar}\cdot{dollar}s); (2) oxide nucleation and growth which is complete by {dollar}{lcub}\approx{rcub}5{dollar}L at an average island height of four monolayers; and (3) bulk thickening after coalescence of the oxide islands. The bulk thickening stage was adequately described …
A Boolean Algebra Approach To High-Level Process Planning, Hugh Jack
A Boolean Algebra Approach To High-Level Process Planning, Hugh Jack
Digitized Theses
One of the most daunting challenges in Computer Integrated Manufacturing (CIM) is bridging the gap between Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM). Many specific approaches have been developed for limited manufacturing domains. For example, a solid model may be directly converted into Numerical Control (NC) code for a computerized milling machine. But, when we try to extend the planning to cover a number of domains, there are no satisfactory techniques. This still leaves many unresolved problems when converting a product from design features to manufacturing features.;Computer Aided Process Planning (CAPP) is the umbrella term for automated approaches …
Surface Modifications Of Silicon Induced By Low Energy Reactive Ion Bombardment, Wayne Harold Chang
Surface Modifications Of Silicon Induced By Low Energy Reactive Ion Bombardment, Wayne Harold Chang
Digitized Theses
The effects of low energy reactive ion bombardment of semiconducting silicon material have been investigated by X-ray photoelectron spectroscopy. The residual surface damage induced by a conventional fluorocarbon plasma reactive ion etching of silicon consisted of a uniform fluorocarbon deposited film approximately 4nm in thickness which covered a silicon compound reaction layer. This reaction layer was comprised of silicon oxides, carbide and fluorosilyl species distributed in depth to approximately 2nm. The removal of the residuel surface damage was accomplished by an ozone oxidation plus a wet oxide chemical etching step processing and monitored by surface charge spectroscopy. This residual surface …
Fabrication Of Indium Phosphide Misfet, Raymund Wai-Man Kwok
Fabrication Of Indium Phosphide Misfet, Raymund Wai-Man Kwok
Digitized Theses
The presence of excessive energy states in the bandgap of III-V semiconductor surfaces is commonly found and has considerably hindered the development of III-V semiconductor technology. Although InP metal-insulator-semiconductor field effect transistors (MISFETs) are attractive switching and driving elements for the InP-based optoelectronic devices which have been widely used for communication applications, interface states of the dielectric/InP structure are known to cause surface Fermi level pinning and drain current drifting, a fact which causes the MISFETs to be unacceptable for any practical usage. In this study, we used a wide range of surface and interface analytical techniques to investigate a …
A Characterization Of The Fast Pyrolysis Of Cellulose And Wood Biomass, Robert George Graham
A Characterization Of The Fast Pyrolysis Of Cellulose And Wood Biomass, Robert George Graham
Digitized Theses
The science of biomass fast pyrolysis is relatively young and incomplete. To date, there has been no systematic attempt to define fast pyrolysis in terms of chemistry, product distribution, kinetics, heat transfer requirements, and requisite process conditions. Neither has there been any experimental work which tracks the reaction progress as a function of both temperature and residence time. Furthermore, the literature provides a fragmented and often contradictory view of the nature of fast pyrolysis.;This thesis provides a coherent picture of the fast pyrolysis of cellulose and wood via an extensive literature review and systematic research. The literature review is an …
A Reconfigurable Multicomputer System: Implementation And Performance, Paul Anthony Smeulders
A Reconfigurable Multicomputer System: Implementation And Performance, Paul Anthony Smeulders
Digitized Theses
Architecture of the computer has always been dictated by the attribute considered the most important during its design. The classical von Neumann computer system was the consequence of a quest for reliability; the modern multiple-processor architectures have resulted from a search for performance. While the modern system's existence is based on its relative reliability, its efficiency depends upon the match between the problem's inherent structure and the system's architecture. The architecture of a typical multiple-processor machine is fixed: essentially it either supports simultaneous, or sequential task solutions with efficiency. Since most computer-tractable problems are neither purely parallel nor serial, the …
Electrochemical Properties Of Passive Films On 440c Stainless Steel, Timothy Lawrence Walzak
Electrochemical Properties Of Passive Films On 440c Stainless Steel, Timothy Lawrence Walzak
Digitized Theses
The properties of passive films formed on 440C stainless steel were investigated using advanced electrochemical techniques for the purpose of establishing a method to measure film stability directly in passivation baths. Electrochemical measurements were sensitive to the passive film properties and were able to quantify the effect of cooling rate on passive film stability. The various techniques used--linear polarization, AC impedance, small amplitude cyclic voltammetry (SACV), and coulostatic transient measurements--provided results that exhibited excellent agreement with the AC impedance technique providing the most information about the interfacial reactions. Full electrochemical characterization of the passive film stability required an evaluation of …
A Study Of Thermally Stratified Plumes In A Channel, Hani A. Farghaly
A Study Of Thermally Stratified Plumes In A Channel, Hani A. Farghaly
Digitized Theses
The problem of waste heat discharge into natural bodies of water is one of the environmental problems that has received considerable attention in recent years. The scope of most of the previous investigations has been limited to summer flow conditions and did not address the problem of waste heat discharge in cold climate regions. This thesis is concerned with the problem of a thermal discharge in a channel in the range of temperatures encountered in practice, including temperatures anticipated in cold climate regions.;More specifically, this study was conducted to: (i) develop numerical models of surface and bottom discharges in a …
A Study Of Oseen Flow Using Integral Conditions, Serpil Kocabiyik
A Study Of Oseen Flow Using Integral Conditions, Serpil Kocabiyik
Digitized Theses
The primary objective of this work is to analyze the steady two-dimensional flow of a viscous incompressible fluid past a conformally-mappable cylinder in an unbounded field. The main concern is the correct satisfaction of the boundary conditions at large distances from the cylinder. It is shown that the steady-state asymmetrical flow problem needs careful examination, particularly with regard to the satisfaction of these conditions. A general method is developed to solve this class of problem, under the assumption that flow is governed by the Oseen linearized equations of motion. The method is based on satisfaction of the proper conditioning for …
Computer Aided Synthesis Of Steam And Power Plants For Chemical Complexes, Masatoshi Nishio
Computer Aided Synthesis Of Steam And Power Plants For Chemical Complexes, Masatoshi Nishio
Digitized Theses
No abstract provided.
Identification And Control Applied To Fermentation, Vuong Thanh Xuyen
Identification And Control Applied To Fermentation, Vuong Thanh Xuyen
Digitized Theses
No abstract provided.
Determination Of Absorption And Atomic Number Corrections In Electron Probe Microanalysis For Electron Energies Below 15 Kev, Lubomir Parobek
Determination Of Absorption And Atomic Number Corrections In Electron Probe Microanalysis For Electron Energies Below 15 Kev, Lubomir Parobek
Digitized Theses
No abstract provided.
Evaluation And Characterization Of Surface Roughness By Ellipsometry, Edmond Che-Hung Chan
Evaluation And Characterization Of Surface Roughness By Ellipsometry, Edmond Che-Hung Chan
Digitized Theses
No abstract provided.