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abstract: This thesis addresses the problem of online schema updates where the goal is to be able to update relational database schemas without reducing the database system's availability. Unlike some other work in this area, this thesis presents an approach which is completely client-driven and does not require specialized database management systems (DBMS). Also, unlike other client-driven work, this approach provides support for a richer set of schema updates including vertical split (normalization), horizontal split, vertical and horizontal merge (union), difference and intersection. The update process automatically generates a runtime update client from a mapping between the old the new schemas. The solution has been validated by testing it on a relatively small database of around 300,000 records per table and less than 1 Gb, but with limited memory buffer size of 24 Mb. This thesis presents the study of the overhead of the update process as a function of the transaction rates and the batch size used to copy data from the old to the new schema. It shows that the overhead introduced is minimal for medium size applications and that the update can be achieved with no more than one minute of downtime. / Dissertation/Thesis / M.S. Computer Science 2011

A dynamic lumbar spinal stabilizer with a helical machined spring element was created in the first stage. The stabilizer was built with 30 N/mm of axial stiffness because if the human body is moved to flexion and extension, this amount of a compressive and tensile load would be applied to the intervertebral disc. The stabilizer supports the loads instead of the disc. The stiffness was influenced by the number of coils, the thickness of coils, and length of the coil element. The stiffness can be determined by analytical equations or by finite element analysis (FE), such as ANSYS Workbench. In the second stage, the lumbar spine FE model was successfully constructed by using Autodesk Inventor 2010. There were three different analyzed models; (1) intact model, (2) fused model, and (3) dynamically stabilized model. This intact model is a simplified and basic model used for fused model and dynamically stabilized model. The range of motion (ROM) was the key term in this study. In other words, examination of each model was based on how much ROM was shown when the flexion, extension, and bending moments have been applied on the spine. The ROM of each model with three moments produced appropriate values compared to the references. The stress analysis is also important to optimize the design of the dynamic stabilizer. The maximum stress was 472 MPa on the stabilizer that is less than yield strength of Titanium alloy.

The work presented in this dissertation centers around the development of analytical tools for the study of advanced proteomics. Section 1 of this work reviews the need for high efficiency protein separation techniques. Dynamic isoelectric focusing (DIEF) is new technique similar to capillary isoelectric focusing (CIEF) invented by Dr. Luke Tolley at Southern Illinois University Carbondale. Using DIEF, the electric field inside the separation capillary can be modified using high voltage electrodes, additional to the anode and cathode, to control the depth and shape of the resulting pH gradient. By changing the pH gradient, the location and width of focused protein bands can be controlled. As a new analytical technique, the development of DIEF required the design and fabrication of special holders which allow for electrical connections to be made at lengths along the separation capillary. These holders were also designed to have a removable section of capillary to extract very specific pH range proteins from high-resolution separations. Higher throughput DIEF systems were investigated, as well as multiplexed DIEF systems. Section 2 covers the topic of dynamic isoelectric/anisotropy ligand binding assay (DIABLA). DIABLA is a new method used to identify proteins in a complex sample that bind to a known molecule. DIABLA has the potential to be used in two complimentary ways, discovery mode and scanning mode. Both modes are accomplished by using DIEF, followed by fluorescence anisotropy as a sensitive detection method. This allows the entire length of capillary to be scanned to identify areas of non-zero anisotropy, which indicate binding interactions between the protein and target molecule. The binding protein(s) can then be extracted using the removable section of capillary from the DIEF holder, and can be identified by using a second dimension analysis, such as LC/MS/MS. DIABLA was verified in a series of proof-of-concept experiments in both discovery and scanning modes. These experiments involved fluorescently tagging proteins that were focused in the presence of a ligand tagged with a different fluorophore. The usefulness of DIABLA as a separation technique was demonstrated in four specific analyses of complex protein samples in Chapter 10.

Since the work of Gardener and his associates in the 1950s, the role of motivation in learning a second language has continued to interest researchers. Previous studies on L2 motivation, were largely based on product oriented models of motivation, which tends to view motivation as a static phenomenon. Recently, however, there has been a shift in emphasis from a study of L2 motivation as a product to its study as a process. The methodological framework of this study was based on Dörnyei and Otto's (1998) Process Model of L2 Motivation. This model proposed that the construct of motivation is not static and changing in nature and influenced by many internal and external factors during learning process. The previous studies that analyzed the motivational variables in the Saudi EFL settings have not investigated the temporal nature of motivation in L2 learning. Using qualitative methodology, the current study aimed to investigate how motivation in English L2 learning changed over time for Saudi students. The participants were seven Saudi students at a mid-western University in the U.S. They had all first begun learning English in Saudi Arabia and had later come to the U.S to pursue their undergraduate or graduate studies. The participants were interviewed on an individual basis using a semi-structured interview format. They also completed a language history questionnaire. The transcripts of the audio-recorded interviews were analyzed using the tools of thematic analysis. Specifically, the participants' oral narratives were analyzed for emerging themes and patterns relating to the development of their motivation for English language learning. The results of this study revealed the temporal and changing nature of motivation in learning English for Saudi students. The emerging themes/patterns related to motivational fluctuations included the learning environment, the role of teacher, economic factor, standardized English tests (e.g. TOEFL and IELTS) and the role of an effective person in enhancing or ceasing the motivational abilities of students learning English. The thesis concluded by discussing implications for future work in this interesting area of research.

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-09Bitstream added on 2014-06-13T21:06:53Z : No. of bitstreams: 1 barros_e_dr_guara.pdf: 1499137 bytes, checksum: 5a94296d58a74230125376ce4552f941 (MD5) / Universidade Estadual Paulista (UNESP) / Na presença de não linearidades, a resposta forçada de estruturas exibe diversos fenômenos físicos que não podem ser descritos através de modelos lineares. Estes fenômenos incluem ressonâncias sub-harmônicas, ressonâncias super-harmônicas, jumps , movimentos quasi-periódicos, movimentos de período múltiplo, caos e interações modais. Recentes estudos experimentais indicam que um novo tipo de interação modal pode ocorrer através de mecanismos não ressonantes, decorrente da transferência de energia de modos de alta freqüência e baixa amplitude para modos de baixa freqüência e alta amplitude. Neste trabalho, interações modais não ressonantes são investigadas na resposta planar não linear de vigas cantilever flexíveis sujeitas a excitações externas e paramétricas. As equações diferenciais e as condições de contorno associadas que governam o movimento flexional-flexional não linear de uma viga assumida inextensível, metálica e isotrópica, são apresentadas. O estudo experimental conduzido revelou que a transferência de energia entre modos de alta freqüência para modos de baixa freqüência ocorre via modulação, sendo função do valor da amplitude de excitação e da proximidade entre os valores da freqüência de modulação e da freqüência dos modos ativados. O estudo revelou também que a ativação de modos de baixa freqüência pode ocorrer sob uma variedade de condições de entrada. Em adição, outros fenômenos dinâmicos não lineares classificados como rotas para o movimento caótico são também observados. Em determinadas condições, movimentos quasi-periódicos com amplitudes moduladas caoticamente e moduladas periodicamente são exibidos. Um movimento de resposta de período dois é também observado. / Interesting physical phenomena occur in the forced response of structures in the presence of nonlinearities, which cannot be explained by linear models. These phenomena include subharmonic resonances, superharmonic resonances, jumps, period-multiplying motions, quasiperiodic motions, chaos and modal interactions. Recent studies suggest that another type of modal interaction may occur through nonresonant mechanisms, due to the energy transfer from the low-amplitude highfrequency modes to high-amplitude low-frequency modes. In this work, nonresonant modal interactions in the nonlinear planar motions of flexible cantilever beams subjected to transverse and parametric harmonic excitations are investigated. The governing equations of the nonlinear bending-bending motions and the associated boundary conditions for an isotropic metallic inextensional beam are presented. An experimental study revealed that the transfer of energy from high-frequency to lowfrequency modes occurs via modulation and is found to be function of the excitation amplitude and the closeness of the modulation frequency to the frequencies of the low modes activated. The experimental study also revealed that the energy transfer from high-frequency modes to low-frequency modes occurs for a variety of conditions. In addition, others nonlinear dynamic phenomenas routes to the chaotic motions, are also observed. Under certain conditions, quasiperiodic motion with periodically and chaotically modulated amplitudes are exhibited. Period-doubling motion is also observed.

This thesis introduces a versatile finite element package, which is tailored for the static and dynamic analysis of radial tyres. A new axisymmetric solid-of-revolution element which takes into consideration, large deformation, the influence of composite orthotropic material and the viscoelasticity and the nonlinearity of the material properties, has been developed for a general loaded tyre. The finite element package has been verified by comparing its results with available analytical, numerical and experimental results. A full static and dynamic investigation has been carried out for a commercial tyre 175 HR 14 and results obtained by using the package have been compared with available experimental results developed by DUNLOP or carried out at Cranfieid. The package has proved to be reliable, flexible, efficient, economic and accurate. The numerical instability problems which are prevalent in this type of analysis have been overcome by the derivation of a developed Newton-Raphson iterative scheme.

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Traditionally the tuning of DMC-type multivariable controllers is done by trial and error. The APC engineer would choose arbitrary starting values and test the performance on a simulated controller. The engineer would then either increase the values to suppress movement more, or decrease them to have the manipulated variables move faster. When the controller performs acceptably in simulation, then the tuning is improved during the commissioning of the controller on the plant. This is a time consuming and unscientific exercise and therefore often does not get the required attention, leading to unacceptable controller behaviour during commissioning and sub-optimal control once commissioning is completed. This dissertation presents a new method to obtain move suppression factors for DMC type multivariable controllers. The challenge in choosing move suppressions lies in the multivariable nature of the controller. Changing the move suppression on one manipulated variable will not only change the performance of that manipulated variable, it will also change the performance of every other manipulated variable with models to the same controlled variables. In the same way, changing the steady state cost of a manipulated variable or the equal concern error of a controlled variable will also affect the behaviour of every other manipulated variable with shared models. There have been attempts to calculate the required move suppression factors mathematically. Some methods used an approach that is based on the premise that move suppression factors that present a well-conditioned controller matrix will provide a well behaved controller in terms of tuning. Some other methods focussed on providing parameters that will cause desirable controlled variable response, either by determining tuning parameters offline, or by re-tuning the controller in real time. The method described in this paper uses a Nelder Mead (Nelder and Mead, 1965) search algorithm to search for move suppressions that will provide acceptable control behaviour. Acceptable behaviour is defined by characterising the dynamic move plan calculated by the controller for each of the manipulated variables, or by characterising the controlled variable path that will result from the manipulated variable moves. The search algorithm can change the move suppressions, the steady state costs, or the move suppression multipliers as used in DMC type controllers. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

In this thesis we investigate important issues in the area of dynamic pricing for revenue management. Studying the effect of competition and strategic consumer behavior, we characterize the dynamic pricing policies for retailers who sell homogeneous goods in multi-period, discrete time, finite horizon settings. In the first essay an impatient consumer visits only one of two competing retailers in each period. If he does not purchase the good, he visits the competing retailer in the ensuing period. Compared to the corresponding single store monopoly, when the consumer’s valuation is uniformly distributed, prices decline exponentially rather than linearly, with a dramatically lower initial price, and a substantially lower system profit. The model is extended to accommodate many consumers, who may be either identical or similar, a more general valuation distribution, and situations wherein capacities are limited. The base case of a centralized two-store monopoly is also examined. In the second essay the consumer may return to the same retailer with some certain probability. This probability is either affected by market structure characteristics, or it may depend on the consumer’s experience at the last store visited. The robustness of the exponential decline of prices is reinforced. It occurs even when a strong retailer faces competition from a relatively much weaker retailer. We investigate the impact of the return probabilities on prices, profits, and consumer surplus. The model is extended to an oligopoly, and to situations with many similar consumers. The effect of strategic consumer behavior on prices and profits is revealed in the third essay. Characterizing the pricing policies arising in a two-period monopoly and duopoly settings, we find that strategic consumer behavior inflicts larger losses to a duopoly than to a monopoly. A lower strategic consumers’ discounting factor, which is beneficial to a monopoly, may be harmful to a duopoly. Ignoring strategic consumer behaviour is costly to a monopoly, but may, on the other hand, be beneficial to a duopoly. An extension to three periods is studied, and with longer horizons the model is analyzed for the case when all the consumers are strategic. / Business, Sauder School of / Graduate