<p>InP and related materials have become important materials for applications in many electronic and photonic devices because of their high electron mobilities and high saturation electron drift velocities. InGaAs and InGaAsP, grown lattice matched to InP, are the materials of choice for making light sources and detectors in the wavelength range of 1.3-1.6 μm for the present day high data rate, long haul, fibre-optic communication systems. InGaAs metal-semiconductor-metal (MSM) photodetectors, InGaAs high-electron mobility transistors (HEMTs) and their monolithic integration as photoreceivers are promising devices for opto-electronic integrated circuits (OEICs). In the fabrication of the InGaAs MSM-PDs and HEMTs, good Schottky contacts are critical to achieve high performance, such as low dark current and high breakdown voltage, of the devices. However, the Schottky barrier height of metal/InGaAs contacts is only about 0.2-0.3 eV, which is not high enough for device applications. InP was chosen as the contact material in our fabrications of InGaAs MSM-PDs and HEMTs because of its compatibility in growth and lattice matched to In₀₅₃Ga₀₄₇As. In this research, the following investigations were carried out to understand the physics of the InP Schottky barrier, to obtain good Schottky contacts to InP, and to improve the performance of the InP/InGaAs MSM-PDs. (1) It was found that the current-voltage characteristics of metal(s)-InP Schottky contacts depart from the behavior predicted for the thermionic emission model. To explain these barrier anomalies. a modified current-voltage relationship was developed based on the inhomogeneous Schottky barrier. (2) A systematic investigation on metallization schemes shows that the Schottky barrier height of metal(s)-InP ranges from 0.38 to 0.5 eV, depending on the metal(s) and deposition techniques and the surface conditions of the InP. Among them, Au/Ti/Pt produces the highest barrier height while Au/Ni/Pt has the best uniformity in metal(s)-InP Schottky contacts. To further increase the Schottky barrier height, a thin In1-xGxP (x ranges from 0.1 to 0.3) layer of 100-200 Å grown on top of InP was employed. The barrier height obtained is found between 0.56 to 0.65 eV. The dark current is significantly reduced while the reverse breakdown voltage is increased from about 15 V to 20 V. (3) High-performance InGaAs MSM-PDs with InP as the barrier layer was fabricated. The MSM-PDs with a finger width of 2μm, finger spacing of 2μm, and an active area of 50 x 50 μm², have a dark current of about 200 nA at a bias of 10 V, a low capacitance of 0.2 pF, and breakdown voltages of about 15 V. A fairly high responsivity of 0.75±0.05 A/W at λ=1.3 μm was obtained. The temporal response is characterized by a rise time of about 4.0±0.2 ps, fall time of 8.0±0.2 ps, and FWHM of 8.5±0.2 ps which corresponds to a 3-dB frequency (unit current gain cut-off frequency), f3dB, of 20 GHz. The performance is comparable to the best of those InGaAs MSM-PDs with InAlAs as the contact layer. (4) Because of the lateral conduction in MSM-PDs and the Fermi-level pinning in InP due to surface states, the surface conditions play an important role in device performance. Surface passivation using (NH₄)₂Sx solution was successfully implemented to improve the performance of InGaAs/InP MSM-PDs.</p> / Doctor of Philosophy (PhD)

<p>For decades, microwaves have been used to create gas discharges for many applications. This thesis deals with the use of microwaves to excite gas discharges for incoherent optical sources, with particular emphasis on excimer systems. In addition, microwave excitation of a gas laser is considered. A novel apparatus was designed and built to couple 2.45-GHz microwave radiation into a gas discharge. The microwave resonator is the essential part of this equipment, and a detailed discussion of its design and performance is given. The resonator is characterized both theoretically and experimentally in order to determine the coupling efficiency and peak electric-field strength. Specialized theory is developed in order to evaluate many parameters of a microwave-excited discharge. The phenomenon of skin effect is investigated quantitatively and expressions for the plasma frequency and electron density are developed in terms of collision frequency and observable parameters (e.g., skin depth). Expressions for peak electric-field strength, ionization coefficient and collisionless electron energy are also developed. The results of an extensive investigation of continuous-wave microwave-excited excimer fluorescence are reported. Rare-gas halide, homonuclear halogen and heteronuclear halogen systems are examined and the corresponding ultraviolet spectra are presented. Truly continuous excimer emission has been achieved (for the first time) on several transitions. For systems of particular interest (e.g. XeCl and KrCl), the effects of total pressures and gas composition on fluorescence output are investigated, and the appropriate spectra are presented. Finally, the potential operation of microwave-excited carbon dioxide and argon-ion gas lasers is investigated, and upper limits are deduced for the small-signal gain under various conditions.</p> / Doctor of Philosophy (PhD)

<p>A technique for obtaining maps of the spatially-resolved and polarization-resolved electroluminescence of 1.3 μm semiconductor diode lasers has been developed. It reveals information about the strain, scattering and absorption which exist in the active region of lasers. These data have been correlated with the spectral output of the lasers, and models have been developed which explain the correlation.</p> / Doctor of Philosophy (PhD)

Simulated, 3D gaming environments have been used for a wide-range of applications including training, entertainment, and experimentation in an assortment of domains for some time. This can be attributed to their unique ability to emulate multifaceted situations that may be difficult to control, while affording participants the opportunity to operate in a relatively safe environment. In cybersecurity research, investigation of insider threat behavior is an endeavor that has received little attention in terms of available environments and resources for experimental manipulation. This research effort aimed to close this gap. A simulated, 3D gaming environment and accompanying scenarios were developed for utilization as a research application for a verification study. These constitute crucial components for proper development of insider threat detection tools and training applications. The aim was to use knowledge of performance, user stress state, and user perceptions of the simulation's graphic and usability qualities to verify the simulation for use in insider threat detection work. The objective of this simulated, 3D gaming environment and scenarios was to serve as a realistic and valid context for the development of insider threat identification methods. The scenario narrative involved a reenactment of computer system exploitation by an employee who is trying to acquire private financial information without authorization. In each scenario, the participant assumed the role of a financial investigator employed at a large financial institution. There were two conditions associated with this verification study (control and insider threat). Participants in the control condition performed all of their tasking as regular bank employees while participants assigned to the insider threat condition had to carry out a portion of their tasking as an insider threat. Findings indicated that participants found the simulated, 3D gaming environment engaging, and the simulations graphics usable and immersive. Additionally, the role manipulation resulted in a significant difference in the time it took to perform critical tasking (tasking that was illicit in the insider threat condition). Role manipulation did not produce significant differences in stress between conditions, but it was influential regarding the perceptions of the stress sources. The results suggest that this simulated, 3D gaming environment meets the needs of insider threat investigation and can be used to advance understanding of the nature of insider threat behavior.

Polycyclic Aromatic Hydrocarbons (PAHs) that are generated by diverse anthropogenic sources, are classified by the U.S. Environmental Protection Agency (EPA) as Semivolatile Hazardous Compounds. PAHs are pollutants of great concern due to their toxicity and mobility in the environment; they can be found in air, water, and soil media. Supercritical Fluid Extraction (SFE) is currently an alternative technology for the removal of PAHs from solid matrices. Carbon dioxide, water and organic compounds, above their critical temperature and pressure conditions, have been used as supercritical fluids. This bench-scale study evaluates the influence of temperature and use of modifiers on the extraction efficiency of PAHs in a diesel-contaminated soil sample from the Miami International Airport (MIA). Carbon dioxide at supercritical conditions was used as extraction fluid in most of this research. Subcritical water, in vapor and liquid states, was also used in a preliminary testing as extraction fluids. A conceptual design of a supercritical carbon dioxide extraction plant is suggested.

ssuring production forms a crucial part of mining business profitability. Factors related to various mine operations, activities and business processes can threaten required/planned mine production.   To address problems and ensure production level in mining, it is necessary to implement a mine production assurance program (MPA). In order to propose a guideline and its component, this study started by reviewing four such techniques used in process industries. Comparing the tools, techniques   and focus with mining productivity and production factors, it was observed that applicability of these methods for mining is limited due to lack of focus on equipment focus, cost focus and other parameters. Similarity of objectives and requirements of equipment focus lead to conclusion that PAP from oil and gas industry seems to be method which can guide MPA.\parAs a basis of MPA, an index is required to create a clear relationship between different situations which can occur in mining operation and production loss. A literature review on mining productivity improvement methods shows availability, utilisation and production performance of equipment are the key factors in determining overall production. A single index applicable for chain operation in mining is needed. A Mine Production index (MPi) is thus proposed. This index involves all three parameters for equipment productivity mentioned above.  Weights associated with MPi calculation for bottleneck equipment can point out critical factors in equipment operation. Once bottleneck equipment and relevant critical factors are known, further analysis can be carried out to determine the possible causes of production loss. By using MPi for machine operations, it is possible to rank machines in terms of production effectiveness. When the study applied MPi to chain operations in a mining case study, a crusher was determined as bottleneck equipment.\parMining operation is heavily influenced by internal and external uncertainties. Operational uncertainties related to equipment includes its key factors leading to production i.e. availability, utilisation and performance. These factors are in turn dependent upon downtime, idle time, rated capacities. External parameters related to weather are based upon location of mining operation. Influence of these factors on production volume, could be used for better decision making during mining operations optimization. To effectively propose a method for correlating internal and external parameters with production volume, case studies in an open pit mine were conducted. During these case studies a multi-regression modelling methodology is used. It was found that at system level availability is important criteria for increasing production. At level of shovel and truck fleet, availability and utilisation are most important characteristics to be focused for reduction in production uncertainty. Environmental factors are although correlate to less variation in production volume compared to operational factors.  Amongst considered environmental factors snowfall is highly influencing followed by rainfall.  At system level  use of maximum capacities of equipment and availability are key point for increasing production. Based on analysis of internal operational factors, it was concluded that capacity of shovel and trucks is underutilised. For shovels availability and idle time are influential factors. For trucks utilisation is highly correlated to production volume generated.  Analysis of environmental factors concluded that, period of zero snowfall and rainfall are perfect condition for equipment production increase. Period when either snowfall or rainfall stabilisation are also equivalent to achieve higher production. Although these production levels are significantly less than period without snow and rain

Photovoltaic (PV) system and the battery energy storage system are promising to supply power for residential buildings. Solar panels along with the battery energy storage (BESS) presents an opportunity for the households to use a much greater proportion of the solar photovoltaic (PV) to generate the electricity and minimize the need of purchasing expensive electricity from the electricity grid. This project presents a framework for conducting the economic and technical analysis of residential house along with the integration of solar panel units and the BESSs. In this study, the electricity consumption of a multi flats building (Magnolia) in Helsingborg and the PV production profile under local weather conditions are compared and analyzed. The proposed framework is developed by considering different prices of electricity of the existing electricity market in Sweden as well as the investment costs for the solar PV units and BESSs. The economic analysis is carried out based on different economic measures such as electricity price, simple payback analysis, net present value, payback analysis based on funding and without funding, and reduction in carbon-di-oxide (CO2) emissions. Technical evaluations of the BESS are carried out based on peak shaving purpose and overproduction from the solar panels. and The results show that ten 28 kWh of the BESSs in Magnolia building is required in order to meet the customer electricity demand and reduce the stress on the electricity grid as well as power cost and size of the fuse. Furthermore, the customer saves 154256 kr yearly, with the payback period of 14 to 20 years, which is almost similar to the expected lifetime of such a BESS.

As a result of trends identified in the report and marketing plan, the importance of a search engine optimized platform for e-commerce is established. In order to further examine the implementation of such, a website was constructed with this purpose in mind. The of said website was designed based on user stories which in their turn partly came from competitor's websites and partly from preference. In order to optimize the website for search engines, four established factors were optimized to the best of the group's ability. These factors were responsivity, custom 404-page, sitemap and keywords. Testing these factors against Google, the tests were ran partly through the search engine itself and partly through the third-party programmes WebSite Auditor and SERPROBOT. In accordance with expectations, the keywords had a considerable effect on the acquired results, but the remaining factors had nothing more than a marginal contribution; this was not expected. The experiment had many sources of error and and low reliability, cheifly on account of the chosen instruments for measure and a statistical uncertainty as a result of few observations. The conclusion made is that keywords have a greater effect than the other evaluated factors.

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