Many commercial and laboratory applications of fiber optics require an ability to manipulate, change and control the state of polarization of light. This is usually accomplished with bulk-optic wave plates which are inherently narrowband, bulky, and often require careful manual tuning and adjustments. H.C. Huang has recently proposed that a variably spun birefringent fiber with spin rate slowly varying from zero to very fast (or vice versa) will transform the state of polarization (SOP) from linear to circular (and vice versa). The most remarkable feature of a Huang fiber is that the transformation from linear to circular polarization is independent of wavelength over entire single mode range of the fiber. In this thesis, using simulations and experiments we explore the properties of such a fiber element and investigate its similarities and differences as compared to a bulk-optic quarter-wave plate. In the simulations, we modeled the Huang fiber as a stack of birefringent waveplates and used this model verify the theoretically predicted polarization transformation behavior and the wideband nature of the Huang fiber. We analyzed the dependence of the polarization transformation by this device on various structural parameters and showed that while the fiber has loose tolerances with respect to the fiber length and the spin variation, it has a strong dependence on the maximum spin rate at the high-spun end. We investigated the PMD characteristics of the Huang fiber for short pulse applications. Using simulations we also verified that two such quarter wave-transforming fibers can be appropriately cascaded to obtain half-wave and full-wave transformation, analogous to bulk optics half wave and full wave plate respectively. In the experiments we studied the polarization transformation behavior of a Huang fiber sample when it is excited by different input states of polarization both from the un-spun end and the high-spun end. We found that the results from the experiments strongly support the simulation results. The experiment was performed at 1310 nm and 1550 nm to verify the wideband nature of the Huang fiber sample. We found that the Huang fiber indeed performs the prescribed state of polarization transformation over a wide band. / Master of Science

Effective project management (PM) is increasingly required for strategy implementation, business transformation management, continual improvement and pioneering product development and service provision. The systematic approach of PM (based on best practices and experience) aims to improve the chances of project success in a competitive environment where scarce resources (capital, human, opportunity, time, etc.) needs to be utilized most effectively. The contribution a project management office (PMO) can make in the medium sized consulting engineering industry to deliver more successful projects was investigated. The investigation involved determining the current state of both PM and PMO maturity in medium sized consulting engineering organisations in South Africa. Furthermore, the required maturity, or level of development, of PM and PMOs were also determined using the prediction orientated Delphi survey method. In the literature study, the concepts of PM, PMO and their maturity determination, successful project delivery, background to the consulting engineering industry in South Africa and similar PM and PMO maturity studies were investigated. From the literature study, an existing maturity survey was selected for each of the concepts PM and PMO. These existing and tested maturity surveys were combined into a single survey. Some demographic information deemed applicable from the literature study was also included in the survey and distributed in a multi-round survey to medium sized organisations similar to the author's organisation, operating in the mining and energy sectors mainly. The current PM and PMO maturity of the organisations taking part in the survey were determined in round 1 of the survey. The required PM and PMO maturity were determined from the round 2 survey results that were completed after the respondents were provided with the round 1 survey statistically averaged maturity levels in an effort to reach a form of consensus amongst the respondents. The round 1 survey was distributed to 161 respondents (response rate of 53%). Round 2 was distributed to the 86 respondents that completed round 1 (response rate of 55%). From the survey results and literature study it was found that there is a definite increase in PM and PMO maturity required in order for medium sized consulting engineering organisations to deliver more successful projects in the mining and energy sector. It was also seen that the maturity levels required for both PM and PMO are not the maximum maturity levels possible. From the empirical study, a definite relationship between PMO and PM was confirmed and it was seen that generally an organisation with a PMO tends to have higher PM maturity levels. For a PMO to be successful, from literature it was seen that the PMO needs to adapt to the organisation and environment it functions in. It was also discovered that a PMO is successful if it reaches the goals it set for itself. The PMO also contributes by systematically and continuously improving and adapting the PM of the company to add the most value to both internal and external customers of the PMO. It is the researcher's opinion that the study is not representative of all medium sized consulting engineering organisations in SA and further research is required to determine industry specific PM and PMO maturity levels and to determine the resulting contribution a PMO can make in this regard. / MBA, North-West University, Potchefstroom Campus, 2014

Effective project management (PM) is increasingly required for strategy implementation, business transformation management, continual improvement and pioneering product development and service provision. The systematic approach of PM (based on best practices and experience) aims to improve the chances of project success in a competitive environment where scarce resources (capital, human, opportunity, time, etc.) needs to be utilized most effectively. The contribution a project management office (PMO) can make in the medium sized consulting engineering industry to deliver more successful projects was investigated. The investigation involved determining the current state of both PM and PMO maturity in medium sized consulting engineering organisations in South Africa. Furthermore, the required maturity, or level of development, of PM and PMOs were also determined using the prediction orientated Delphi survey method. In the literature study, the concepts of PM, PMO and their maturity determination, successful project delivery, background to the consulting engineering industry in South Africa and similar PM and PMO maturity studies were investigated. From the literature study, an existing maturity survey was selected for each of the concepts PM and PMO. These existing and tested maturity surveys were combined into a single survey. Some demographic information deemed applicable from the literature study was also included in the survey and distributed in a multi-round survey to medium sized organisations similar to the author's organisation, operating in the mining and energy sectors mainly. The current PM and PMO maturity of the organisations taking part in the survey were determined in round 1 of the survey. The required PM and PMO maturity were determined from the round 2 survey results that were completed after the respondents were provided with the round 1 survey statistically averaged maturity levels in an effort to reach a form of consensus amongst the respondents. The round 1 survey was distributed to 161 respondents (response rate of 53%). Round 2 was distributed to the 86 respondents that completed round 1 (response rate of 55%). From the survey results and literature study it was found that there is a definite increase in PM and PMO maturity required in order for medium sized consulting engineering organisations to deliver more successful projects in the mining and energy sector. It was also seen that the maturity levels required for both PM and PMO are not the maximum maturity levels possible. From the empirical study, a definite relationship between PMO and PM was confirmed and it was seen that generally an organisation with a PMO tends to have higher PM maturity levels. For a PMO to be successful, from literature it was seen that the PMO needs to adapt to the organisation and environment it functions in. It was also discovered that a PMO is successful if it reaches the goals it set for itself. The PMO also contributes by systematically and continuously improving and adapting the PM of the company to add the most value to both internal and external customers of the PMO. It is the researcher's opinion that the study is not representative of all medium sized consulting engineering organisations in SA and further research is required to determine industry specific PM and PMO maturity levels and to determine the resulting contribution a PMO can make in this regard. / MBA, North-West University, Potchefstroom Campus, 2014

The exponential growth of multimedia data challenges effectiveness and efficiency of the state-of-the- art retrieval techniques. In this thesis, we focus on browsing of large datasets using exploration approaches where query cannot be particularly expressed or where the need of some general notion of the dataset is required. More specifically, we study exploration scenarios utilizing the metric access method PM-Tree which natively creates a hierarchy of nested metric regions. We enhance the PM- Tree for the exploration purposes and define different traversing and querying strategies. Further, we investigate range multi-query (range query defined by multiple objects) approaches. We propose new effective and efficient cut-region range query and compare the new query with other approaches for efficient multi-query processing. Finally, we implemented all new methods and strategies for the PM- Tree into multimedia exploration framework and tested browsing algorithms on a game-like demo application.

Made available in DSpace on 2014-12-17T14:55:54Z (GMT). No. of bitstreams: 1 DiegoRC_DISSERT.pdf: 1983615 bytes, checksum: 7f5b15ea84a6c8bb36201c679b18226f (MD5) Previous issue date: 2011-07-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The occurrence of transients in electrocardiogram (ECG) signals indicates an electrical phenomenon outside the heart. Thus, the identification of transients has been the most-used methodology in medical analysis since the invention of the electrocardiograph (device responsible for benchmarking of electrocardiogram signals). There are few papers related to this subject, which compels the creation of an architecture to do the pre-processing of this signal in order to identify transients. This paper proposes a method based on the signal energy of the Hilbert transform of electrocardiogram, being an alternative to methods based on morphology of the signal. This information will determine the creation of frames of the MP-HA protocol responsible for transmitting the ECG signals through an IEEE 802.3 network to a computing device. That, in turn, may perform a process to automatically sort the signal, or to present it to a doctor so that he can do the sorting manually / A ocorr?ncia de transientes em sinais de eletrocardiograma (ECG) ? um indicativo de um fen?meno el?trico externo ao cora??o, sendo a identifica??o de transientes a metodologia mais utilizada na an?lise m?dica desde que o eletrocardi?grafo (dispositivo respons?vel pelo aferimento dos sinais de eletrocardiograma) foi inventado. Existem poucos trabalhos relacionados a esse assunto, o que motiva a cria??o de uma arquitetura para fazer o pr?-processamento desse sinal em busca da identifica??o de transientes. O presente trabalho prop?e um m?todo baseado na energia do sinal da transformada Hilbert de eletrocardiograma, sendo uma alternativa aos m?todos baseados em morfologia do sinal. Essa informa??o determinar? a forma??o de Quadros do protocolo PM-AH respons?vel por transmitir os sinais de ECG atrav?s de uma rede de computadores do tipo IEEE 802.3 at? um dispositivo computacional. Que por sua vez poder? realizar um processamento para fazer a classifica??o autom?tica do sinal ou apresent?-lo para um m?dico realizar essa classifica??o de forma manual

Airborne particulate matter (PM) consists of solid and liquid particles suspended in air. PM causes many negative health effects when inhaled like exacerbations of asthma, chronic obstructive pulmonary disease (COPD), and premature death. The health impacts of PM depend on the physical size and chemical composition of the inhaled particles. Particles less than 2.5 micrometers can penetrate the deep lung and enter the bloodstream. Understanding the composition of PM helps study human exposures and evaluate PM sources to support control and mitigation strategies. This thesis examines PM in power plant emissions, in ambient air, and in homes, with an emphasis on characterizing hazardous metals. PM emissions from the University of Iowa power plant were examined during a transition away from coal. Biomass is a renewable fuel and when used in place of or co-fired alongside coal it directly reduces emissions of fossil CO2 and PM to the atmosphere. PM emissions were examined under two scenarios: the first was a stoker boiler that fired 100% renewable energy pellets. PM and metal emissions reduced by 59 and 80% respectively despite increases to polycyclic aromatic hydrocarbons (PAHs) that was attributed to emission of unburned carbon fuel. The second test was done in a circulating fluidized bed boiler firing 78% oat hulls, 17% coal, and 5% energy pellets. Decreases in PM, PAHs, and metal emissions were 32, 33, and 50%, respectively. Reductions in PM, PAHs, and metals when firing renewable fuels provide environmental advantages to local air quality while trying to eliminate the use of coal. Ambient air quality was examined downwind of the power plant. The levels of PM2.5 in Iowa City in 2016 ranged from 1.4-32.1 µg m-3 with an annual mean of 7.5 µg m-3. These levels are below the National Ambient Air Quality Standards (NAAQS) for 24-hours (35 µg m-3) and the annual average (12 µg m-3). On average, the analyzed metals accounted for 10.7 ± 5.3% of PM2.5. Potassium, calcium, and zinc were the most abundant metals (averaging 250 ± 10, 170 ± 40, and 11.2 ± 0.5 ng m-3, respectively) and are associated with geological sources and biomass burning. Metals associated with fossil fuel combustion such as arsenic, lead, or vanadium were observed at low levels (averaging 0.58 ± 0.01, 1.32 ± 0.03, and 0.19 ± 0.01 ng m 3, respectively). Harmful metals were at least an order of magnitude lower than the World Health Organization’s guideline concentrations in Iowa City PM2.5. Overall, the hazardous metals in ambient PM2.5 observed in Iowa City were not at concerning levels. The work in this chapter helps provide a metal speciation profile for future studies and these measurements can be used to assess future changes in PM2.5 metal concentrations. Indoor PM collected in homes of Eastern Iowa COPD patients was characterized for its metal content. COPD patients are at higher risk of developing respiratory infections, which cause acute exacerbations of COPD—the leading cause of mortality in COPD patients—and airborne PM increases risk of infection. From the 21 homes studied 6-87 mg of indoor PM was collected over 30 days in winter. Crustal metals such as magnesium, iron, and aluminum were the most concentrated in indoor PM, having mass fractions from 3000-25,000 ng mg-1. Toxic metals like vanadium and arsenic were at lower levels from 3-65 ng mg-1. Between homes the relative abundance of metals was similar, but the absolute abundance was highly variable. Analyzing indoor PM is essential since Americans on average spend 80% of their day indoors making it a significant environment for PM exposure. This chapter provides a chemical profile for different homes when studying the impact PM has on respiratory health. This thesis also provides new measurements of the chemical composition of PM at the point of emission, in ambient air, and within homes. Advancing knowledge of PM composition in different environments is vital in understanding its impacts on human health. Improvements to local air quality with reductions to PM and metal emissions were observed when firing alternative fuels. Ambient PM2.5 concentrations in Iowa City were lower than NAAQS levels and the composition of both ambient and indoor PM was evaluated. With greater understanding of PM composition, better control strategies can be studied and employed to improve local air quality.

The nucleotide sequence at the 5´ end of genes can be specified as the sequence of a promoter associated 5´ untranslated region (UTR) together with the initial coding sequence of a gene. Because this genetic region has been implicated in the control of translation, messenger RNA (mRNA) stability and even transcription, it can be looked at as one of the central control points in gene expression. Both the 5´-UTR and the coding sequence have often been included in optimization strategies targeted to simulate recombinant protein production in E. coli and numerous reports describe various sequence-dependent structural features that can positively influence the overall expression process. Nevertheless, the actual mechanisms by which the regulation of gene expression is exerted at the 5´ end remain obscure. The work reported in this thesis has involved various types of analyses of the functionality of the 5´ end, by using mutations as a major tool. The work can be seen as mainly a detailed empirical analysis of the relation between the specific nucleotide sequences at the 5’ end of genes and the final outcome at the protein production level. The results also indicate that optimizations based on empirical laboratory protocols are currently unlikely to be exceeded by predictions based on bioinformatics software. Sequence mutagenesis of elements in the XylS/Pm - positive regulator/promoter system coupled to high-throughput screening had been previously proven to be a powerful method for increasing the expression of recombinant genes from this expression cassette. At the beginning of this thesis work the effect of introducing random mutations in the DNA sequence of the Pm promoter associated 5´-UTR and two 5´ fusion partners, whose sequences correspond either to a consensus translocation signal peptide or the first 23 codons of a well-expressed celB gene (encoding a cytoplasmic phosphoglucomutase) was investigated. The core of the experimental work was construction of large combinatorial libraries of the different DNA sequences and subsequent selection for improved expression of a reporter gene (either ampicillin or apramycin resistance gene), that was indicated by an increase in antibiotic tolerance of the corresponding E. coli host cells. A shared result of the three individual studies was the establishment of a collection of optimized sequences that generally improved protein production properties of both reporter and industrially relevant heterologous genes. In addition to random mutagenesis, also synonymous mutations were introduced in the DNA sequence of the consensus signal peptide (CSP) and the consequent expression effects were evaluated. As a conclusion, the DNA changes that did not alter the amino acid sequence led to a lesser stimulation of expression of the bla reporter (ampicillin resistance) than when complete sequence randomization was applied. Moreover, similar results were obtained when synonymous codon usage of the first 9 codons of the medically important ifn-α2b gene was optimized by a bioinformatic method, followed by experimental determination of expression levels of several rationally selected ifn-α2b synonymous variants. These results indicated that optimization of the codon usage of the 5´ coding sequence has limited effects, probably due to the sequence intrinsic characteristics. However, the use of optimized 5´ fusion partners or 5´-UTR variants can often overcome such limitations. Besides evaluating the expression at the protein level, the work also addressed how the changes of the 5´ end of a gene influence expression at the level of transcript accumulation and mRNA stability. For that purpose, a non-invasive method for accessing recombinant mRNA stability in bacteria was developed. The procedure was based on the removal of diffusible transcriptional inducers followed by qRT-PCR determination of mRNA levels at consecutive time-points. Among the principal findings was that a 5´ fusion partner (specifically: translocation signals pelB and ompA, together with the celB-based 5´ fusion) contributes to the stimulation of recombinant gene expression by enhancing the stability of the corresponding fusion mRNA. The stimulation of expression caused by specific mutations in the 5´-UTR and adjacent coding sequence (synonymous changes), on the other hand, surprisingly appeared to result from improved rate of mRNA synthesis. Three selected promoter systems (Pm, Ptac and the T7 based) were used in these studies, and part of the work also evaluated how fast each system responds to addition and removal of its inducer, respectively. The expression systems were found to affect both transcript accumulation and decay in a specific way that correlated with the type of transcription regulation each system is subjected to. Finally, a study comparing five bacterial expression systems (XylS/Pm, XylS/Pm ML1-17 (a Pm variant), the bacteriophage T7 RNA polymerase/promoter system, LacI/Ptrc and AraC/PBAD) with respect to their production capacity of five different recombinant proteins was carried out. The comparison revealed many expression system and model gene specific features and that none of the systems was superior in all evaluated aspects; which included system´s adaptability, maximum protein yield, basal expression in the absence of inducer, use of cellular resources and homogeneity of expression. However, particularly because of a large associated collection of optimized genetic elements (such as sequence variants of the Pm promoter, the XylS regulator, 5´-UTR and various translocation signals) and the possibility of simple genetic adjustments that can lead to both higher and lower expression levels, the XylS/Pm system appeared as a good starting point for optimization of various kinds of protein production processes. / A Combinatorial Mutagenesis Approach to Improve Microbial Expression Systems

Automatic voltage regulation is necessary for all power producing synchronous generators to ensure that the produced power have a constant and stable voltage level and to sustain grid stability. The aim of this thesis is to design and build an automatic voltage regulator for a synchronous generator. A six-phase permanent magnet alternator will be used to excite the rotor with solid-state relay controlled rotating bridge rectifier. The field current is regulated by a closed loop control system that is based on a programmable logic controller, PLC. Programing of the PLC is executed in the developing environment CoDeSys, IEC 61131-3, which is the international standard for programing PLC applications. Simulations for predicting the system behavior is done with a web based in-browser tool, circuitlab.com. The results show a good performance of the regulator and the closed loop system although there is room for improvement of the solid-state controlled rectifier system.

The wind energy conversion system considered in this thesis is based on a vertical axis wind turbine with a cable wound direct drive PM generator. Diode rectifiers are used to connect several such units to a single DC-bus and a single inverter controls the power flow from the DC-bus to a utility grid. This work considers the described system from a generator perspective i.e. the turbine is primarily seen as a torque and the inverter is seen as a controlled load. A 12 kW VAWT prototype with a single turbine has been constructed within the project. The power coefficient of this turbine has been measured when the turbine is operated at various tip speed ratios. This measurement determines both how much energy the turbine can convert in a given wind and at what speed the turbine should be operated in order to maximise the energy capture. The turbine torque variation during the revolution of the turbine has also been studied. A PM generator prototype has been constructed in order to study power loss in the stator core at low electrical frequencies. Heat exchange between the stator and the air-gap between the stator and the rotor has been studied. Heat exchange between the stator and the air-gap is increased by turbulence caused by the rotor. The generator was also used in a demonstration of a DC-grid where two diode rectified PM generators supplied power to a single DC load.  An initial study of an inverter suitable for grid connection of the 12 kW PM generator has been performed. Several turbine control strategies are evaluated in simulations. The control strategies only require the parameter "turbine speed" to determine the optimal system load.

Previous studies have demonstrated that EPA approved federal reference method (FRM) samplers can substantially misrepresent the fractions of particles being emitted from agricultural operations due to the relationship between the performance characteristics of these samplers and existing ambient conditions. Controlled testing in a wind tunnel is needed to obtain a clearer understanding and quantification of the performance shifts of these samplers under varying aerosol concentrations, wind speeds and dust types. In this study, sampler performance was tested in a controlled environment wind tunnel meeting EPA requirements for particulate matter (PM) sampler evaluation. The samplers evaluated included two low-volume PM10 and Total Suspended Particulate (TSP) pre-separators. The masses and particle size distributions (PSDs) obtained from the filters of tested samplers were compared to those of a collocated isokinetic sampler. Sampler performance was documented using two parameters: cut-point (d_50) and slope. The cut-point is the particle diameter corresponding to 50% collection efficiency of the pre-separator while the slope is the ratio of particle sizes corresponding to cumulative collection efficiencies of 84.1% and 50% (d_84.1/d_50) or 50% and 15.9% (d_50/d_15.9) or the square root of 84.1% and 15.9% (d_84.1/d_ 15.9). The test variables included three levels of wind speeds (2-, 8-, and 24-km/h), five aerosol concentrations varying from 150 to 1,500 mu g/m3 and three aerosols with different PSDs (ultrafine Arizona Road Dust (ARD), fine ARD and cornstarch). No differences were detected between the performance of the flat and louvered FRM PM10 samplers (a = 0.05). The mean cut-point of both the PM10 samplers was 12.23 mu m while the mean slope was 2.46. The mean cut-point and slope values were statistically different from the upper limit of EPA-specified performance criteria of 10.5 mu m for the cut-point and 1.6 for the slope. The PM10 samplers over-sampled cornstarch but under-sampled ultrafine and fine ARD. The performance of the dome-top TSP sampler was close to the isokinetic sampler, and thus it can be used as a reference sampler in field sampling campaigns to determine true PM concentrations. There were large variations in the performance of the cone-top TSP samplers as compared to the isokinetic sampler. Dust type and wind speed along with their interaction had an impact on sampler performance. Cut-points of PM10 samplers were found to increase with increasing wind speeds. Aerosol concentration did not impact the cut-points and slopes of the tested samplers even though their interaction with dust types and wind speeds had an impact on sampler performance.