HREM imaging was performed using the Jeol 4000ex microscope on specimens prepared from an as-grown ingot of semi-insulating Gallium Arsenide. Various low angle grain boundaries were imaged in the [110] orientation, misorientations varying between 4°-13°. Detailed study of a grain boundary of 11.5° misorientation about the [110] rotation axis has been carried out. Burgers vector analysis showed the presence of perfect 60° and [001] dislocations. Modelling of the [001] dislocation has been carried out using the Tersoff potential, Bond Order Potential and a tight binding Hamiltonian for GaAs, using Chadi (1984) parameters. The dislocation core was associated with an 8-membered and two 5-membered rings. Assum- ing there is a minimum of wrong bonds, we predict that the core has two wrong bonds, one being Ga-Ga, and the other As-As, both in equivalent positions where the two 5-membered rings were appended to the 8-membered ring. The Ga-Ga bond is considerably shorter and hence stronger than the As-As bond. Band structure calculations performed using a Vogl (1983) sp³s* Hamiltonian revealed deep states in the gap, which are associated with atoms in the core only. Using Stadelmann's (1987) EMS program, successful image matching of calculated images of the [001] dislocation has been achieved with the experimental image, using the atomic structure generated by tight binding relaxation. Ga and As being only two atomic numbers apart have similar scattering factors and cannot be easily distinguished in the experimental image. The equivalence of the position of the two wrong bonds greatly eases image matching as it is no longer necessary to know which is the Ga-Ga , and which is the As-As bond. This is the first suggested model of the [001] dislocation in GaAs, to the best of my knowledge. It is found to be similar to the atomic structure of the 90° partial dislocation in silicon (Bigger et al., 1992). No account of segregation of impurities to the grain boundary, or the [001] dislocation core is taken here, though it is very likely that an impurity atom would sit itself in this large space. The relaxed atomic structure for the 60° dislocation showed a doubling of periodicity along the dislocation line, similar to that found in the 30° partial in Si. The core consists of a 7-membered and a 5-membered ring with a minimum of two wrong bonds. In addition to this, quantitative comparisons of the [001] HREM image and simulated structures have been made and an iterative structure refinement carried out in order to achieve the best image matching. The resultant 'experimental-best-fit' structure was not found to be physically or chemically plausible.

Biopolymers are polymers produced by certain microorganisms, that are readily degradable in the environment. These biodegradable plastics have the potential to be used as substitutes for conventional petroleum based plastic provided that the production costs can be greatly reduced. The high cost of biopolymer production is due to the cost of substrate which mainly is glucose. / The enzymatic hydrolysis of potato processing wastes was to produce glucose as a least expensive feedstock substrate for the production of biopolymers of polyhydroxybutirate (PHB) from the bacterium Alcaligenes eutrophus was studied. The enzymatic hydrolysis experiments were carried out using $ alpha$-amylase liquefaction enzymes from Aspergillus oryzae and barley-malt, and amyloglucosidase saccharification enzyme from Rhizopus. / The results indicated that the production of glucose from potato starch waste to be used as a substrate to produce biopolymers was both technically and economically feasible. A 10 to 90 ratio of barley-malt to potato starch waste gave the highest conversion of starch to glucose of 194.30 gL$ sp{-1}$ (96.56%), and the lowest liquefaction enzyme cost ($0.054) to hydrolyze one kg of potato starch waste. { it A. eutrophus /} produced PHB of 5.0 gL$ sp-1$ (76.9 % of biomass) using the glucose substrate generated from the potato starch waste.

A beta-galactosidase gene from Bifidobacterium breve B24 which showed the higher hydrolytic and synthetic activity was cloned in E. coli. The complete beta-galactosidase gene contained 2076 bp nucleotides and encoded 691 amino acids which had a high homology to the other Bifidobacterium species. This beta-galactosidase was homologous to that of the LacA family. The galA gene was successfully over-expressed in E. coli ER2566. To observe any change in the recombinant enzyme, beta-galactosidases from Bifidobacterium breve B24 and recombinant E. coli ER2566 were purified to homogeneity by ion exchange chromatography (Mono-Q) and gel-filtration chromatography (Superose-12 and Superdex 200) columns. The molecular mass of both beta-galactosidases was estimated to be 75 kDa on SDS-PAGE. Activity staining on non-denaturing Native-PAGE and Superose-12 gel-filtration chromatography showed that the enzymes are composed of a dimer with a molecular mass of 150 kDa. / The optimum pHs of the native and recombinant enzymes for hydrolyzing O-nitrophenyl-beta-D-galactopyranose (ONPG) were pH 6.0 and 7.0, respectively, and they were stable over the pH range of 5-8 and 6-9, respectively. The optimum temperature of both enzymes for hydrolyzing ONPG was similar at 45 °C and they were stable over the temperature range of 20-45 °C. Both enzymes were stable up to 45 °C during 5 h of incubation at pH 6.5. The recombinant enzyme was slightly activated by bivalent metal ions, Mg2+, Mn2+, and Zn2+ at 1 mM but strongly inhibited by Hg2+ and p-chloromercuribenzoic acid (PCMB). The K m values of both native and recombinant beta-galactosidases for ONPG were 2.77 and 1.82 mM, respectively, and the Vmax values were 1.02 and 1.39 mM/min, respectively. / The two beta-galactosidase activities were also tested with lactose as substrate. The optimum pH of the native and recombinant enzymes for hydrolyzing lactose was similar at pH 6.0. Both enzymes had more than 80 % of their activity in the range of pH 6-8, indicating that the enzymes were stable at neutral pH. However, the native beta-galactosidase had around 40 % of its activity at pH 5.0, whereas the recombinant enzyme had no activity at this pH. On the other hand, the recombinant enzyme had over 50 % of its activity at pH 9.0, while the native beta-galactosidase showed lower than 5 % of its activity. The optimum temperature of both enzymes was at 45 °C. The profiles of both enzyme activities were very similar except at the temperature of 10 °C. The recombinant beta-galactosidase still had around 20 % of its enzyme activity at 10 °C, while no enzyme activity from the native enzyme was detected at this temperature.

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 56-58). / xiii, 58 leaves, bound ill. 29 cm

Over the last few years, commodity Graphics Processing Units (GPUs) have evolved from fixed graphics pipeline processors into more flexible and powerful data-parallel processors. These stream processors are capable of sustaining computation rates of greater than ten times that of a single-core CPU. GPUs are inexpensive and are becoming ubiquitous in a wide variety of computer architectures including desktop and laptop computers, PDAs and cell phones. This research works investigates possible ways to use modern GPUs for real-time computer vision and pattern classification tasks. Special attention is paid to algorithms, where the power of the CPU is a limiting factor. This is in particular the case for real-time tracking algorithms on video streams, where many candidate regions must be evaluated at once to allow stable tracking of features. They impose a high computational burdon on sequential processing units such as the CPU. The proposed implementation presented in this thesis is considering standard PC platforms rather than expensive special dedicated hardware to allow a broad variety of users to benefit from powerful computer vision applications. In particular, this thesis includes following topics: 1. First, we present a framework for computer vision on the GPU, which is used as a foundation for the implementation of computer vision methods. 2. We continue with the discussion of GPU-based implementation of Kernel Methods, including Support Vector Machines and Kernel PCA. 3. Finally, we propose GPU-accelerated implementations of two tracking algorithms. The first algorithm uses geometric templates in a gradient vector field. The second algorithm is a color-based approach in a particle filter framework. Both are able to track objects in a video stream. This thesis concludes with a final discussion of the presented methods and will propose directions for further research work. It will also briefly present the features of the next generation of GPUs.

The semiconductor industry has seen a paradigm shift from Application Specific Integrated Circuits to Multiprocessor System on Chip systems over the last decade, primarily due to the miniaturization of the transistor. However, billion of transistors available on a single chip need to be used efficiently to provide more functionalities in portable devices, yet minimize power and chip area, which increases the design complexity of multiprocessor systems. Tighter time to market deadlines further pressurizes the designer, requiring a comprehensive automation of the design process of such complex multiprocessor systems. This thesis presents a design automation methodology for the design of Multiprocessor System on Chip (MPSoC) systems for multimedia applications. This thesis introduces a heterogeneous multiprocessor system where processing elements are connected in a pipelined fashion. A multimedia application is executed very efficiently on a pipelined system due to the stream oriented data flow nature of such applications. Application Specific Instruction set Processors (ASIPs) are used as the elementary processing elements in the multiprocessor system as they can be customized according to the application tasks assigned to them. The problem of selecting a processor configuration for each of the ASIPs in the pipelined system is formalized. We present three different techniques to select processor configurations by exploring the design space of an ASIP based pipelined system, and integrating them into a flexible and designer driven design flow for efficient exploration of large design spaces in order of 10^16 design points. The first two techniques are based on Integer Linear Programming (ILP), named Exact ILP formulation (EIF) and Reduced ILP formulation (RIF), while the third technique is based on a novel heuristic. We also developed a design space pruning algorithm that can enable the use of EIF and RIF to obtain optimal or near optimal design points from large design spaces. For four multimedia applications, we show that RIF and the heuristic can explore the design space and reveal the Pareto front in several hours, while EIF took several days to obtain the Pareto front. The quick availability of the Pareto front of a design space will help the designer to make early changes in the design. Furthermore, it is shown that, on average, the error incurred by RIF and the heuristic is within 1.25% and 2.25% of the optimal design points obtained via EIF for all the four multimedia applications. In the worst case, RIF introduced an error of 17.08% while the heuristic had an error of 11.39%.

[Abstract]: With the increasing use of fibre reinforced polymer (FRP) composites in civil engineering structures, there is a growing realisation of the need to develop newstructural systems which can utilise the unique characteristics of these materials in a more efficient and economical manner. In many instances this will require thedevelopment of new materials tailored to address the unique performance and economic parameters of mainstream construction. Over recent years, researchers at the University of Southern Queensland have pioneeredthe use of a new type of particulate filled polymer core material which greatly improves the robustness and cost effectiveness of FRP structural systems. These compositematerials are composed of small hollow spherical fillers (microspheres) in a thermosetting polymer matrix. Initial research into these materials, including theirfeasibility in prototype structural elements, have shown these materials to have major potential for widespread application in structural composite systems.One of the most promising classes of these materials investigated to date are vinyl ester / cenosphere composites, which utilise cenospheres derived from fly ash in a vinyl ester matrix. Previously reported studies into these materials have been restricted to initialsurveys of material behaviour which sought to identify key parameters in achieving desired performance outcomes in the composite. This dissertation presents the first in-depth investigation of these materials specifically as a core material option for civil infrastructure applications. The particular focus of this work is on the relationship of the vinyl ester matrix to the characteristics of the resultingcomposite. Several key matrix parameters were identified and assessed as to their influence on cure characteristics, fabrication operations, mechanical properties and theretention of such properties under elevated service temperatures. The outcomes of this work have significantly improved the understanding of matrix influences on the behaviour of these composite systems and have been drawn together to provide a number of recommendations on the application of this new technology to new structural systems.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 4 uppsatser.

Thesis (M.S.)--Ohio University, March, 2008. / Title from PDF t.p. Includes bibliographical references.

Zugl.: München, Techn. Univ., Diss., 2007 / Hergestellt on demand