Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.

Vibration energy harvesters, or energy scavengers, recover mechanical energy from their surrounding environment and convert it into useable electricity as sustainable self-sufficient power sources to drive micro-to milli-Watt scale power electronics in small, autonomous, wireless devices and sensors. Using semiconducting, organic piezoelectric nanomaterials are attractive in low-cost, high resistance to fatigue, and environmentally friendly applications. Significantly, the deposition processes of sputtering ZnO (zinc oxide) thin films with high c-axis preferred orientation and electrospun PVDF (polyvinylidene fluoride) nanofibers with high piezoelectric £]-phase crystallisation are controlled at room temperature. Thus they don¡¦t have the necessity of post-annealed and electrical repoling process to obtain an excellent piezoelectricity, and are suitable for all flexible substrates such as PET (polyethylene terephthalate) and PI (polyimide). These works are divided into two parts. Part 1: Flexible piezoelectric harvesters based on ZnO thin films for self-powering and broad bandwidth applications. A new design of Al (aluminum)/PET-based flexible energy harvester was proposed. It consists of flexible Al/PET conductive substrate, piezoelectric ZnO thin film, selectively deposited UV (ultraviolet)-curable resin lump structures and Cu (copper) foil electrode. The design and simulation of a piezoelectric cantilever plate was described by using commercial software ANSYS FEA (finite element analysis) to determine the optimum thickness of PET substrate, internal stress distribution, operation frequency and electric potential. With the optimum thickness predicted by developed accurate analytical formula analysis, the one-way mechanical strain that is efficient to enhance the induced electric potential can be controlled within the piezoelectric ZnO layer. In addition, the relationship among the model solution of piezoelectric cantilever plate equation, vibration induced electric potential and electric power was realized. ZnO thin film of high (002) c-axis preferred orientation with an excellent piezoelectricity was deposited on the Al/PET by RF (radio-frequency) magnetron sputtering in room temperature. Al was sputtered on the PET substrate as the bottom electrode because of its low sheet resistance, superior adhesion with PET, and lattice constants matching with ZnO thin film. The selectively deposited UV-curable resin lump structures as proof mass were directly constructed on flexible piezoelectric plate using electrospinning with a stereolithography technique. One individual harvester achieves a maximum OCV (open-circuit voltage) up to 4V with power density of 1.247 £gW/cm2. This self-powered storage system can drive the warning signal of the LED (light emitting diode) module in both resonant and non-resonant conditions. We also succeeded in accomplishing a broad bandwidth harvesting system with operating frequency range within 100 Hz to 400 Hz to enhance powering efficiency. This system comprises four units of individual ZnO piezoelectric harvester in the form of a cantilever structure connected in parallel, and rectifying circuit with storage module. In addition, a modified design of a flexible piezoelectric energy-harvesting system with a serial bimorph of ZnO piezoelectric thin film was presented to enhance significantly higher power generation. This high-output system was examined at 15 Hz. The maximum DC (direct current) voltage output voltage with loading was 3.18 V, and the maximum DC power remained at 2.89 £gW/cm2. Furthermore, in order to examine the deformation between interfaces and the adhesion mechanism of multi-layer flexible electronics composites (e.g., ITO (indium tin oxide)/PET, Al/PET, ZnO/ITO/PET, and ZnO/Al/PET), nanoscratching and nano-indention testing (nanoindenter XP system) were conducted to analyze the adhesion before and after the vibration test. The plastic deformation between the ductile Al film and PET substrate is observed using SEM (scanning electron microscopy). Delamination between the ZnO and Al/PET substrate was not observed. This indicates that Al film provides excellent adhesion between the ZnO thin film and PET substrate. Part 2: Pre-strained piezoelectric PVDF nanofiber array fabricated by near-field electrospining on cylindrical process for flexible energy conversion. In various methodologies of energy harvesting from ambient sources, one-dimensional nanoharvesters have been gaining more attention recently. However, these nanofibers fabricated by micro-forming technologies may not easily control their structural diameter and length. This study originally presented the HCNFES (hollow cylindrical near-field electrospining) process to fabricate permanent piezoelectricity of PVDF piezoelectric nanofibers. Under high in-situ electric poling and strong mechanical stretching effect during HCNFES process, large PVDF nanofiber array with high piezoelectric £]-phase crystallisation was demonstrated. These pre-strained piezoelectric PVDF nanofibers fabricated by HCNFES with high process flexibility at low cost, availability in ultra-long lengths, various thicknesses and shapes can be applied at power scavenge, sensing and actuation. Firstly, PVDF nanofibers lay on a PET substrate, silver paste was applied at both ends of fibers to fix their two ends tightly on a Cu foil electrode pair. The entire structure was packaged inside a thin flexible polymer to maintain its physical stability. Repeatedly stretching and releasing the nanoharvester (NH 1) with a strain of 0.05% at 5 Hz vibration created a maximum peak voltage and current of -50 mV and -10 nA in forward connection, respectively. Secondly, a total of 44 parallel nanofibers have been fabricated and transferred onto an IDT (interdigital) electrode with 64 electrode pairs as a nanohavester (NH 2) to amplify current outputs under repeated mechanical vibration and impact tests. Under a repeated maximum strain of 0.14% at 6 Hz vibration, a peak current of 39 nA and peak voltage of 20.2 mV have been measured. Impact testing at 15 Hz, peak current of 130 nA has been collected with a voltage of 24.4 mV. Finally, the single PVDF fiber as nanoharvester (NH 3) with a strain of 0.05-0.1% at 5 Hz vibration created a maximum peak voltage and current of -45 mV and -3.9 nA, respectively. The maximum power remained at 18.45 pW/cm2 with a load resistor of 6.8 M£[. Based on the mechanism of converes piezoelectric effect, ANSYS software with coupled field analysis was used to realize piezoelectric actuation behavior of the PVDF fibers. From the observation of actuation property, a fixed-fixed single nanofiber was tested under different DC voltage supply. Comparing the polarized fiber with non-polarized fibers, the measurement of the center displacements as a function of electric field was conducted and characterized.

By developing strong, self-sustaining individuals in organisations, employees will need to withstand the forces of stressors and be able to cope with continuous changes within their working environment. To move the equilibrium level from the current to the desired condition, the field of forces must be altered - by adding driving forces and by removing restraining forces. An individual's sense of coherence may either alleviate or aggravate reactions to a stressor and moderate the impact of occupational stressors on the individual's affective outcomes. The objectives of this study were to validate the 13-item version of the Orientation to Life Questionnaire (OLQ) (Antonovsky, 1987) and to determine the experience of employees with high levels of sense of coherence regarding helping and restraining factors within the workplace (compared to that of those with a low sense of coherence). A cross-sectional s w e y design was used. The total population (N = 2 678) of employees in a financial institution in Gauteng was used in this study. Random samples of groups with a strong (n = 300) and low (n = 300) sense of coherence were taken for purposes of the qualitative study. The OLQ (Antonovsky, 1987) and a biographical questionnaire were administered. The scale showed acceptable reliability and construct validity. The study set out to determine the applicability of the theoretical model of sense of coherence to employees in a financial institution. Reliability analysis revealed that the three subscales of sense of coherence were sufficiently internally consistent. The reliability of the measuring instrument were assessed with the use of Cronbach alpha coefficients. Descriptive statistics (e.g. mean and standard deviations) were used to analyse the data. By using the structural equation modelling approach, a one-dimensional factor structure for sense of coherence amongst employees in a financial institution emerged. The reliability analysis revealed that the alpha scores were acceptable. It can therefore be concluded that the 13-item version of the OLQ is a reliable and valid measuring instrument. The results showed that although employee groups with high and low levels of sense of coherence are experiencing similar helping and restraining factors within their working environment, helping factors are being experienced with a higher frequency by groups with high levels of sense of coherence and restraining factors with a higher frequency by groups with low levels of sense of coherence. Recommendations were made for future research. / Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007

This thesis is dealing with thermal fields and the possibilities of their solution by a finite element method. Thereinafter thesis describe assembling a 3D model of induction machine with known parameters, and solving thermal field of the model by Ansys Workbench program and verification of these results by practical measuring on real machine.

Historic tenant farmsteads are often thought to be redundant archaeological resources because of their limited temporal range and function which acts to limit the diversity of their archaeological assemblages. However, work has not been done that confirms this equivalence, and archaeologists often write off tenant farmsteads as being too modern or too disturbed to warrant investigation. This is a problematic approach as tenant farmsteads are quickly eroding from the American landscape and a representative sample of sites need to be investigated and preserved before they’re gone. This thesis tests different sampling strategies and field methods that may allow for the efficient investigation of tenant farmsteads without jeopardizing historical knowledge. The results show that the sites studied in this thesis are in fact redundant and a number of different methods can be used to investigate them in a much more efficient manner.

Salvinorin A is a non-nitrogenous, selective kappa opioid receptor agonist with potent hallucinogenic properties. Because Salvinorin A has no basic nitrogen, it does not readily adhere to the “message-address” concept of selectivity for the opioid receptors. Therefore, a better understanding of how salvinorin A and its analogs interact with the kappa opioid receptor may shed some light on how salvinorin A obtains its potency and selectivity. The structure-affinity relationships (SAFIR) of salvinorin A and its analogs along with a discussion of the selectivity of the opioid receptors, is presented. A fragment of salvinorin A, methyl-3-acetoxy-4-oxocyclohexanecarboxylate, was synthesized to determine if the B, C and D rings are or are not necessary for binding to the opioid receptors. The fragment was found not to bind to the kappa, delta or mu receptor which reinforces the importance of the B, C and D rings in the binding of salvinorin A to the kappa opioid receptor. Homology models of the kappa, delta and mu opioid receptors were constructed based on inactive bovine rhodopsin, light-activated bovine rhodopsin and the human beta-2 adrenergic receptors. The program MODELLER was also used to construct the kappa opioid receptor. Two comparative molecular field analysis (CoMFA) studies are then presented which compared three different types of alignment methods. The alignment methods employed included a receptor-docked alignment in which the salvinorin A analogs were docked into a model of the kappa opioid receptor using the program GOLD. The docked poses for this alignment were chosen based on their similarity to our postulated model of salvinorin A in the kappa opioid receptor. In our model the furan oxygen forms hydrogen bonds with Q115(2.60) and Y320(7.43), the methoxy oxygen of the C-4 position ester group may form a hydrogen bond with Y312(7.35) and the methyl group of the C-2 position acetoxy moiety forms a hydrophobic interaction with Y313(7.36). These interactions are consistent with mutagenesis studies. The other alignment methods employed were a FlexS alignment and a realignment of the receptor-docked poses using the Fit Atoms function within SYBYL. Only the receptor-docked alignment method resulted in robust and predictive CoMFA models which indicates that the analogs may bind to the kappa opioid receptor in a similar but non-identical way. In addition, information from the CoMFA models based on the receptor-docked alignment led to a postulated binding mode for a set of amine analogs of salvinorin A which were not part of the original data set. Docking studies have the positively charged C-2 position amine group interacting with E209(XL2.49) while the furan oxygen and C-4 position ester group interacts with the same residues as in our model of salvinorin A in the kappa opioid receptor. The studies presented here not only support our postulated model of salvinorin A binding to the kappa opioid receptor but may also explain the trend of the beta epimers of the amine analogs to have a higher affinity than the corresponding alpha epimers. Site-directed mutagenesis studies could provide data to support or refute the postulated models of the amines docked in the kappa opioid receptor presented here.

The dissertation gives an analysis of the contemporary condition in the area of fitness centres. The business plan for introducing a new fitness centre in the market follows. Based on research and analyses appropriate strategies and tools have been chosen, so that the enterprise could bring added value to the owners and above all customers´needs.

With tightening university budgets, never before has the activity level of research grant proposal writing been more intense. With increased proposal numbers, including for the National Science Foundation's (NSF) prestigious CAREER award, has also come increased competition and decreased funding rates. This dissertation has searched for successful and unsuccessful characteristics from funded and unfunded CAREER proposals. The research focused on a study of two key subjects: 1) a corpus of 20 texts that included 12 funded proposals and 8 unfunded proposals from across NSF programs, and 2) an ethnographic analysis comprised from interviews with 14 NSF program officers (PO) from varying programs. Coding elements with the texts to uncover topical chains of content, rhetorical, and document design strategies revealed sound rhetorical moves and rhetorical mistakes. The study also illustrated evidence of adherence to or neglect of NSF-mandated writing/formatting conventions as connected to the likelihood of receiving funding. Moreover, the study revealed conventions that have developed for the genre that are not prescribed by NSF but that, nevertheless, seem to be expected. Through genre field analysis, the study's interviews with program officers (PO) revealed a system of genre-agents and player-agents that interact together in a highly rhetorical and social system. This system, comprised of locales in which a multitude of play scenarios can be enacted to exert influence, operates within fairly exact rules of play. Such rules may be published by NSF or simply be "understood," yet principal investigators (PI) are held accountable for them regardless. The ethnography created from interviews with POs revealed multiple genre field elements (e.g., genre- and player-agents, transformative locales, play scenarios, penalty conditions) as well as common mistakes and best practices. A complete mapping of the CAREER award proposal preparation, submission, and review process resulted from the study, which mapping has offered insightful strategies to expand PI (and other agents') influence on the funding process. The dissertation concluded by offering investigators a step-by-step process to identify and map the elements of the proposal genre field in which they operate.

To achieve higher power density, converters and components must be able to handle higher voltage and current ratings at higher percentages of efficiency while also maintaining low cost and a compact footprint. To meet such demands, medium-voltage resonant converters have been favored by researchers for their ability to operate at higher switching frequencies. High frequency (HF) operation enables soft switching which, when achieved, reduces switching losses via either zero voltage switching (ZVS) or zero current switching (ZCS) depending on the converter topology. In addition to lower switching losses, the converter operates with low harmonic waveforms which produce less EMI compared to their hard switching counterparts. Finally, these resonant converters can be more compact because higher switching frequencies imply decreased volume of passive components. The passive component which benefits the most from this increased switching frequency is the transformer. The objective of this work is to design a >400 kHz, 100 kW transformer which will provide galvanic isolation in a Solid-State Transformer (SST) based PEBBs while maintaining high efficiency, high power density, and reduced size. This work aims to present a simplified design process for high frequency transformers, highlighting the trade-offs between co-dependent resonant converter and transformer parameters and how to balance them during the design process. This work will also demonstrate a novel high frequency transformer insulation design to achieve a partial discharge inception voltage (PDIV) of >10 kV. / Master of Science / As the world's population expands and countries progress, the demand for electricity that is high-powered, highly efficient, and dependable has increased exponentially. Further, it is integral to the longevity of global life that this development occurs in a fashion that mitigates environmental consequences. The power and technology sectors have been challenged to address the state of global environmental affairs, specifically regarding climate change, carbon dioxide emissions, and resource depletion. To move away from carbon emitting, non-renewable energy sources and processes, renewable energy sources and electric power systems must be integrated into the power grid. However, the challenge lies in the fact that there is not an easy way to interface between these renewable sources and the existing power grid. Such challenges have undermined the widespread adoption of renewable energy systems that are needed to address environmental issues in a timely manner. Recent developments in power electronics have enabled the practical application of the solid-state transformer (SST). The SST aims to replace the current, widespread form of power transformation: the line frequency transformer (50/60 Hz). This transformer is bulky, expensive, and requires a significant amount of additional circuitry to interface with renewable energy sources and electric power systems. The SST overcomes these drawbacks through high frequency operation (>200 kHz) which enables higher power at a reduced size by capitalizing on the indirect proportionality between the two parameters. The realization of the SST and its implementation has the ability to greatly advance the electrification of the transportation industry which is a top contributor to carbon emissions. This work aims to demonstrate a >400 kHz, 100 kW SST with a novel magnetic design and insulation structure suited for electric ship applications.

The aim of this research is to investigate the extent to which Open Source Software (OSS) adoption behaviour can empirically be shown to be governed by a set of self-reported (driving and inhibiting) salient beliefs of key informants in a sample of organisations. Traditional IS adoption/usage theory, methodology and practice are drawn on. These are then augmented with theoretical constructs derived from IT governance and organisational diagnostics to propose an artefact that aids the understanding of organisational OSS adoption behaviour, stimulates debate and aids operational management interventions. For this research, a combination of quantitative methods (via Fisher's Exact Test) and complimentary qualitative method (via Content Analysis) were used using self-selection sampling techniques. In addition, a combination of data and methods were used to establish a set of mixed-methods results (or meta-inferences). From a dataset of 32 completed questionnaires in the pilot study, and 45 in the main study, a relatively parsimonious set of statistically significant driving and inhibiting factors were successfully established (ranging from 95% to 99.5% confidence levels) for a variety for organisational OSS adoption behaviours (i.e. by year, by software category and by stage of adoption). In addition, in terms of mixed-methods, combined quantitative and qualitative data yielded a number of factors limited to a relatively small number of organisational OSS adoption behaviour. The findings of this research are that a relatively small set of driving and inhibiting salient beliefs (e.g. Security, Perpetuity, Unsustainable Business Model, Second Best Perception, Colleagues in IT Dept., Ease of Implementation and Organisation is an Active User) have proven very accurate in predicting certain organisational OSS adoption behaviour (e.g. self-reported Intention to Adopt OSS in 2014) via Binomial Logistic Regression Analysis.