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In this thesis, we will investigate the degradation of the low temperature polycrystalline silicon TFTs (LTPS TFTS) under the electrical stress. The electrical stress is divided into two parts of ac stress and dc stress. We used ac stress and dc stress conditions to stress different TFTs respectively and investigate the influence of grain boundary in n-type TFT and p-type TFT by use of electrical analysis. On the other hand, degradation mechanism was confirmed by measured capacitance. In n-type TFT, the SLS poly-Si TFT which contains GB perpendicular to the channel direction owns the higher ability against dc stress and poorer ability against ac stress than the poly-Si TFT which does not contain GB. The physical mechanism for these results has been reasonably deduced by use of TFT device simulation tool (ISE_TCAD). In p-type TFT, the enhancement phenomenon is always observed after dc or ac stress. There are both existed a power-law between the variation of the drain current with stress time. The slope of power-law is related to the shortening speed of effective channel length. In either dc stress or ac stress, there are two effective factors. The one factors of them is the degradation of poly-Si film, and another one is the effective channel length shortening. In the competition of these two effective factors, the GB-TFT has more obvious enhancement than GB-TFT during dc stress. Nevertheless, during the ac stress the GB-TFT is without larger enhancement than NGB-TFT because of serious poly-Si film damage.

Master of Agribusiness / Department of Agricultural Economics / Vincent R. Amanor-Boadu / While understanding consumer decisions about food choices is complex, the nature of wines makes it even more difficult to decipher how consumers arrive at their choices. Given the perceived importance of "local", how willing are consumers to pay for locally-produced wine? And, what characteristics of the wine influence the premium that consumers pay for it? These are the two related questions that this research seeks to address. The research uses a case study approach to explore how five wine characteristics of local Kansas wine influence the premium consumers are willing to pay. The five characteristics are appearance, aroma, body, taste and finish. The study uses four pairs of wine in the following groups: sweet white, dry white, semi-sweet red and dry red. Each pair is made up of a Kansas wine and a non-Kansas wine. A very well-defined set of focus group participants were invited to taste these wine without knowing the identity of the wines and score them according to their characteristics and then provide an indication of how much they are willing to pay. The case results indicate that the focus group participants were willing to discount Kansas wines in all cases of the four pairs. The factors affecting the discount were finish for sweet white wines, appearance for sweet red wines, taste and aroma for dry white and dry red wines. The implication of this exploratory case study is that while most local residents proclaim their willingness to pay a premium for local wines, when tested against national or international competitors, consumers are unwilling to pay a premium for these local wines because the local wines lack the desired quality the international wines have. The information is important because it provides direction for an entrepreneur seeking to develop local wines to focus on understanding and addressing the characteristics which influence consumers' willingness to pay a premium even as she determines which particular wines current players in the local Kansas industry has the potential to be competitive if they address the characteristics upon which they are penalized by consumers. This, despite this being an exploratory case study, it provides important direction for entrepreneurial action.

Thermal barrier coatings have been widely used to provide thermal protection to components in the hot section of gas turbines. This research focuses on two influencing factors on coating behavior: thermal gradient and cyclic oxidation. The delamination mechanics under thermal gradient is analyzed, taking thermally grown oxide into consideration. Coatings experience thermal gradients at different stages during actual service flight. One is due to engine power shut down when landing and the other due to internal cooling of the substrate. Thermally grown oxide (TGO) also acts as a critical factor in delamination mechanics. The induced stress gradient and corresponding energy release rate for interface delamination and shallower delamination are presented. Mechanism maps that explain the criteria for preventing delamination from developing and propagating are established. Three cooling trajectories are envisaged to analyze the variation in the possibility of delamination. Multilayer coatings used in components of the hot section of aero turbine engines also experience cyclic temperature variation during flight cycles. As experiment conditions vary and coating performance is improved, the time required to run through the test of coating failure can be both time-consuming and prohibitive. Therefore, protocols providing prediction of quantified coating behavior are in demand to shorten life-time tests. Curves of mass change are obtained from quantifying scale growth and loss by different models such as Cyclic Oxidation Spall Program (COSP). A modification is made by combining COSP and a mechanic based model to obtain critical parameters for lifetime prediction from short time experiment. The time for coatings to reach peak temperature during cycling is discovered to influence prominently on modeling results. Predictions for several coating compositions and cycling conditions are consistent with the data from the existing experiments of the coating system.

The research question asks: “Is the policy for financial inclusion in Rwanda explicit, appropriate and effective?” The Government of Rwanda targets ‘financial inclusion’ for 80% of the population of Rwanda by 2017. The study considers what financial inclusion means, how policy has captured it, and whether policy implementation reaches the grassroots – and with what effect. Chapter 1 introduces the research study. Chapter 2 gives background to Rwanda’s development, the strategic policy cycle and planning processes, the accessibility of policy detail, and the aspiration for economic transformation to be a ‘middle income’ country by 2020. Professionalising public service, and the role of Rwanda’s leadership are considered, as are Rwanda’s demographic challenges. Chapter 3 reviews literature relevant to Rwanda’s development and to financial inclusion in development. It explores the ‘livelihoods’ analytic framework. Chapter 4 outlines methods and methodological approaches to this study. A ‘grounded theory’ approach is used and a mixed methods approach is applied to the data. The four data chapters (Chapters 5, 6 7, and 8) draw on voices of people involved in financial inclusion policy. In Chapter 5, villagers speak, via a household survey, about good things in their lives, challenges they face, and their actual livelihood activities. They explain their engagement with financial services, and discuss the role of asset ownership. In Chapter 6 senior policy makers speak of vision and pragmatism in financial inclusion policy, and their own rationale for supporting the policy. Chapter 7 focuses on voices at the mid-level of implementation: District level civil servants, cooperative managers, branch bank-managers. All describe challenges and achievements, explaining their personal route to this career position. Chapter 8 returns to grassroots, hearing voices of farmers (in groups and individually), using real lives to show impacts and limitations of the policy. Chapter 9 draws conclusions from the study: the impact of the policy for financial inclusion; the role of central and local leadership; the wider insights allowed into the nature of inclusive development; and the significance of Rwanda’s ‘Home Grown Solutions’. The study proposes a wider use of the livelihoods analytical framework as an aid to understanding transformation at diverse levels in development.

This thesis is concerned with the characterisation, fabrication and testing of devices capable of generating and detecting terahertz (THz) radiation. Such devices are based on semiconductor photoconductors grown under low temperature (LT) conditions using the technique of Molecular Beam Epitaxy (MBE). The absorption of a pulsed or continuous wave (CW) signal by these structures in conjunction with the presence of an electric field generates photocurrent, which is fed into an antenna structure fabricated on the surface of the active layers. As a result of such a sequence, a THz signal is generated and radiated from the substrate side into free space. Therefore, the efficiency of the devices is determined by the characteristics of the photoconductors and the geometry of the designed antenna structures. The desired material characteristics are high absorption at the corresponding illumination wavelength, high dark resistivity, high electron mobility and sub picosecond carrier lifetime. The determination of these characteristics for all the structures grown in this work composes the characterisation part of the thesis. The fabrication part comprises of the design of several antenna structures with various geometrical characteristics, while the testing part consists of their evaluation as THz sources and detectors in a time-domain spectroscopy (TDS) system under pulsed excitation. To date, THz devices based on low temperature grown GaAs (LT-GaAs) photoconductors have been reported to be the most efficient. However, their operational wavelength, at 800 nm, requires very expensive and complex components spurring interests in solutions consisting of devices operating at longer wavelengths, where cheaper and simpler components exist. The most desirable and practical operational wavelength is the telecommunication one at 1.55 μm. Thus, the biggest challenge is the development of efficient devices operating at this illumination wavelength. In this work, devices operating at the very important wavelength of 1.55 μm as well as at the wavelengths of 1 μm and 800 nm are presented. The key findings for the long wavelength devices (1.55 μm) demonstrate photoconductors with ultrafast carrier lifetimes (~ 120 fs), high resistivity (> 105 Ω / sq), high mobility (> 1000 cm2 / Vs) and system responses with spectral range up to 3 THz and power-to-noise ratio of 60 dB. These characteristics are among the best ever reported for such material systems, making them efficient THz devices for various optoelectronic applications, especially for telecommunication laser-driven CW THz systems.

We investigate the conditions under which electron irradiation of single-walled carbon nanotube (SWCNT) bundles with 2 keV electrons produces an increase in the Raman D peak. We find that an increase in the D peak does not occur when SWCNTs are preheated in situ at 600 C for 1 h in ultrahigh vacuum (UHV) before irradiation is performed. Exposing SWCNTs to air or other gases after preheating in UHV and before irradiation results in an increase in the D peak. Small diameter SWCNTs that are not preheated or preheated and exposed to air show a significant increase in the D and G bands after irradiation. X-ray photoelectron spectroscopy shows no chemical shifts in the C1s peak of SWCNTs that have been irradiated versus SWCNTs that have not been irradiated, suggesting that the increase in the D peak is not due to chemisorption of adsorbates on the nanotubes.

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