Gas turbine engines provide thrust for aircraft engines and supply shaft power for various applications. They consist of three main components. That is, a compressor followed by a combustion chamber (burner) and a turbine. Both turbine and compressor components are either axial or centrifugal (radial) in design. The combustion chamber is stationary on the engine casing. The type of engine that is of interest here is the gas turbine auxiliary power unit (APU). A typical APU has a centrifugal compressor, burner and an axial turbine. APUs generate mechanical shaft power to drive equipments such as small generators and hydraulic pumps. In airplanes, they provide cabin pressurization and ventilation. They can also supply electrical power to certain airplane systems such as navigation. In comparison to thrust engines, APUs are usually much smaller in design. The purpose of this research was to investigate the possibility of combining the three components of an APU into a single centrifugal rotor. To do this, a set of equations were chosen that would describe the new turbomachinery cycle. They either were provided or derived using quasi-one-dimensional compressible flow equations. A MathCAD program developed for the analysis obtained best design points for various cases with the help of an optimizer called Model Center. These results were then compared to current machine specifications (gas turbine engine, gasoline and diesel generators). The result of interest was maximum specific power takeoff. The results showed high specific powers in the event there was no restriction to the material and did not exhaust at atmospheric pressure. This caused the rotor to become very large and have a disk thickness that was unrealistic. With the restrictions fully in place, they severely limited the performance of the rotor. Sample rotor shapes showed all of them to have unusual designs. They had a combination of unreasonable blade height variations and very large disk thicknesses. Indications from this study showed that the single radial rotor turbomachinery design might not be a good idea. Recommendations for continuation of research include secondary flow consideration, blade height constraints and extending the flow geometry to include the axial direction. / Master of Science

Auxiliary power supply (APS) plays a key role in ensuring the safe operation of the main circuit elements including gate drivers, sensors, controllers, etc. in medium voltage (MV) silicon carbide (SiC)-based converter systems. Such a converter requires APS to have high insulation capability, low common-mode coupling capacitance (Ccm ), and high-power density. Furthermore, considering the lifetime and simplicity of the auxiliary power supply system design in the MV converter, partial discharge (PD) free and multi-load driving ability are the additional two factors that need to be addressed in the design. However, today’s state-of-the-art products have either low power rating or bulky designs, which does not satisfy the demands. To improve the current designs, this thesis presents a 1 MHz isolated APS design using gallium nitride (GaN) devices with MV insulation reinforcement. By adopting LCCL-LC resonant topology, the proposed APS is able to supply multiple loads simultaneously and realize zero voltage switching (ZVS) at any load conditions. Since high reliability under faulty load conditions is also an important feature for APS in MV converter, the secondary side circuit of APS is designed as a regulated stage. To achieve MV insulation (> 20 kV) as well as low Ccm value (< 5 pF), a current-based transformer with a single turn structure using MV insulation wire is designed. Furthermore, by introducing different insulated materials and shielding structures, the APS is capable to achieve different partial discharge inception voltages (PDIV). In this thesis, the transformer design, resonant converter design, and insulation strategies will be detailly explained and verified by experiment results. Overall, this proposed APS is capable to supply multiple loads simultaneously with a maximum power of 120 W for the sending side and 20 W for each receiving side in a compact form factor. ZVS can be realized regardless of load conditions. Based on different insulation materials, two different receiving sides were built. Both of them can achieve a breakdown voltage of over 20 kV. The air-insulated solution can achieve a PDIV of 6 kV with Ccm of 1.2 pF. The silicone-insulated solution can achieve a PDIV of 17 kV with Ccm of 3.9 pF. / M.S. / Recently, 10 kV silicon carbide (SiC) MOSFET receives strong attention for medium voltage applications. Asit can switch at very high speed, e.g. > 50 V/ns, the converter system can operate at higher switching frequency condition with very small switching losses compared to silicon (Si) IGBT [8]. However, the fast dv/dt noise also creates the common mode current via coupling capacitors distributed inside the converter system, thereby introducing lots of electromagnetic interference (EMI) issues. Such issues typically occur within the gate driver power supplies due to the high dv/dt noises across the input and output of the supply. Therefore, the ultra-small coupling capacitor (<5 pF) of a gate driver power supply is strongly desired.[37] To satisfy the APS demands for high power modular converter system, a solution is proposed in this thesis. This work investigates the design of 1 MHz isolated APS using gallium nitride (GaN) devices with medium voltage insulation reinforcement. By increasing switching frequency, the overall converter size could be reduced dramatically. To achieve a low Ccm value and medium voltage insulation of the system, a current-based transformer with a single turn on the sending side is designed. By adopting LCCL-LC resonant topology, a current source is formed as the output of sending side circuity, so it can drive multiple loads importantly with a maximum of 120 W. At the same time, ZVS can use realized with different load conditions. The receiving side is a regulated stage, so the output voltage can be easily adjusted and it can operate in a load fault condition. Different insulation solutions will be introduced and their effect on Ccm will be discussed. To further reduce Ccm, shielding will be introduced. Overall, this proposed APS can achieve a breakdown voltage of over 20 kV and PDIV up to 16.6 kV with Ccm<5 pF. Besides, multi-load driving ability is able to achieve with a maximum of 120 W. ZVS can be realized. In the end, the experiment results will be provided.

Cette thèse propose une étude transversale des principales réalisations de DO dans l'anaphore verbale en anglais, à savoir : do this/that/it, do so, ellipse post-auxiliaire (EPA) et DO britannique. Chaque anaphorique fait l'objet d'une étude approfondie fondée sur un échantillon de plusieurs centaines d'occurrences authentiques prélevées dans le BNC et le COCA, ainsi que le corpus de Bos & Spenader (2011). Plusieurs variables sont analysées, notamment le registre, la nature grammaticale de DO, les propriétés sémantiques et syntaxiques du déclencheur d'antécédent, l’identité de sujet et d'état de choses, les alternances de polarité, de modalité, d'aspect, de temps et de voix ainsi que la présence éventuelle d'adjoints contrastifs ou non contrastifs.Une attention particulière est portée au DO britannique, c'est-à-dire l'emploi de formes non finies de DO anaphorique essentiellement limité au registre conversationnel de l'anglais britannique, qui n'a jamais fait l'objet d'une étude empirique auparavant. A partir d’un échantillon de 483 occurrences prélevées dans la composante orale du BNC et vérifiées systématiquement à l'écoute, cette étude met en lumière certaines caractéristiques socio-culturelles et situationnelles qui favorisent son utilisation, en plus de ses propriétés linguistiques et discursives. Ainsi, cette étude aboutit à la conclusion que le DO britannique constitue une réalisation particulière de l'EPA, qui met en œuvre des formes non finies du DO auxiliaire. / This dissertation presents research across the main types of verb-phrase anaphora involving DO, viz. do this/that/it anaphora, do so anaphora, post-auxiliary ellipsis (PAE) and British English DO. Each anaphor underwent close analysis based on a sample of several hundreds of occurrences retrieved from the BNC and the COCA, as well as Bos & Spenader's (2011) corpus. Different variables were studied including register, the grammatical status of DO, semantic and syntactic properties of antecedent triggers, identity of subjects and states of affairs, the presence or absence of contrastive and non-contrastive adjuncts, as well as polar, modal, aspectual, temporal and voice alternations.One item of particular interest involves British English DO which bears a strong resemblance to PAE, except that it involves non-finite forms of DO and is generally restricted to British conversational English. Unlike PAE, British English DO has never before been the focus of study based on empirical data. In this research, 483 naturally-occurring examples taken from the Spoken component of the BNC as well as the accompanying metadata and recorded material were fully examined. Sociolinguistic and situational information was investigated, as were the linguistic properties and discourse conditions that make the use of British English DO felicitous. The result has led to a far better understanding of the phenomenon. In particular, it was found that British English DO can be considered a sub-type of PAE, which involves non-finite forms of auxiliary DO.

This master thesis investigates and analyzes the energy use for traction and auxiliary equipment in passenger rail vehicles. It covers both the train service with passengers and when the trains are going through other stages in the everyday operation. The operational cycle and associated operational situations are introduced as a way of describing the varying use of a train over time. The descriptions focus on the most common activities and situations, such as stabling and parking, regular cleaning, inspections and maintenance. Also how these situations affect energy use by their need for different auxiliary systems to be active. An energy model is developed based on the operational cycle as a primary input, together with relevant vehicle parameters and climate conditions. The latter proving to be a major influence on the energy used by the auxiliary equipment. The model is applied in two case studies, on SJ's X55 and Västtrafik's X61 trains. Both are modern electric multiple units equipped with energy meters. Model input is gathered from available technical documentation, previous studies and by measurements and parameter estimations. Operational cycle input is collected through different planning systems and rolling stock rosters. Climate input is finally compiled from open meteorological data banks. The results of the case studies show that the method and models are useful for studying the energy used by the trains in their operational cycles. With the possibility to distinguish the energy used by the auxiliary equipment, both during and outside the time the trains are in service with passengers. With this it's also possible to further investigate and study potential energy saving measures for the auxiliary equipment. Simulations of new ventilation control functions and improved use of existing operating modes on the trains show that considerable energy savings could be achieved with potentially very small investments or changes to the trains. The results generally show the importance of a continued investigation of the auxiliary equipment's energy use, as well as how the different operational situations other than the train service affect the total energy use. / Detta examensarbete utreder och analyserar energianvändningen för passagerarjärnvägsfordons traktion- och hjälpkraftssystem, både under tågdriften med passagerare och andra delmoment som tågen genomgår under den normala dagliga driften. För detta introduceras driftcykeln och tillhörande driftsituationer som ett sätt att beskriva användningen av ett tåg över tiden. Syftet är att beskriva de vanligast förekommande aktiviteterna och situationerna, såsom uppställning och parkering, regelbundna inspektioner, klargörningar och underhåll. Även hur dessa situationer påverkar energianvändningen genom ett varierande behov av hjälpkraft och aktiva funktioner i tågen. En energimodell baserad på driftcykeln som huvudsaklig indata, tillsammans med tågets egenskaper samt det omgivande klimatet, tas fram. Klimatet visar sig vara en avgörande faktor i hjälpkraftens energianvändning. Modellen utvärderas i typstudier på SJs X55 och Västtrafiks X61. Båda är elektriska motorvagnståg utrustade med energimätare. Indata till modellen samlas in genom tillgänglig teknisk dokumentation, tidigare studier och genom mätningar samt parameterestimering. Driftcyklerna för tågtyperna sammanställs med hjälp av olika planeringssystem och omloppsplaner. Väder- och klimatdata samlas slutligen in från öppna databaser för metrologiska data. Resultaten från typstudierna visar att metoden och modellerna är användbara verktyg för att kunna beskriva tågens energianvändning i deras driftcykler. Med möjligheten att särskilja hjälpkraftssystemens energianvändning vid tågdriften med passagerare men även i de övriga situationerna. Med detta blir det också möjligt att undersöka potentiella energibesparingsåtgärder för hjälpkraftssystemen. Simulering av förbättrade styrfunktioner för ventilationen och förbättrat utnyttjade av redan inbygga energibesparande driftlägen på tågen visar att betydande energibesparingar kan fås med relativt små medel och få förändringar på fordonen. De sammantagna resultaten av arbetet visar på vikten av att fortsätta undersöka och utreda hjälpkraftens energianvändning samt hur driftsituationerna utanför tågdriften med passagerare påverkar den totala energianvändningen.

Control and monitoring networks often operate on AC/DC power systems. DC batteries and chargers are commonly used on industrial plants as auxiliary DC power systems for these control and monitoring networks. The energy demand and load profiles for these control networks differ from application to application. Proper design, sizing, and maintenance of the components that forms part of the DC control power system are therefore required. Throughout the load profile of a control and monitoring system there are various peak currents. The peak currents are classified as inrush and momentary loads. These inrush and momentary loads play a large role when calculating the required battery size for an application. This study investigates the feasibility of using supercapacitors in conjunction with batteries, in order to reduce the size of the required battery capacity. A reduction in the size of the required battery capacity not only influences the cost of the battery itself, but also influences the hydrogen emissions, the physical space requirements, and the required rectifiers and chargers. When calculating the required size batteries for an auxiliary power system, a defined load profile is required. Control and monitoring systems are used to control dynamic processes, which entails a continuous starting and stopping of equipment as the process demands. This starting and stopping of devices will cause fluctuations in the load profile. Ideally, data should be obtained from a live plant for the purpose of defining load profiles. Unfortunately, due to the economic risks involved, installing data logging equipment on a live industrial plant for the purpose of research, is not allowed. There are also no historical data available from which load profiles could be generated. In order to evaluate the influence of supercapacitors, complex load profiles are required. In this study, an alternative method of defining the load profile for a dynamic process is investigated. Load profiles for various applications are approximated using a probabilistic approach. The approximation methodology make use of plant operating philosophies as input to the Markov Chain Monte Carlo simulation theory. The required battery sizes for the approximated profiles are calculated using the IEEE recommended practice for sizing batteries. The approximated load profile, as well the calculated battery size are used for simulating the auxiliary power system. A supercapacitor is introduced into the circuit and the simulations are repeated. The introduction of the supercapacitor relieves the battery of the inrush and momentary loads of the load profile. The battery sizing calculations are repeated so as to test the influence of the supercapacitor on the required battery capacity. In order to investigate the full influence of adding a supercapacitor to the design, the impact on various factors are considered. In this study, these factors include the battery size, charger size, H2 extraction system, as well as maintenance requirements and the life of the battery. No major cost savings where evident from the results obtained. Primary reasons for this low cost saving are the fixed ranges in which battery sizes are available, as well as conservative battery data obtained from battery suppliers. It is believed that applications other than control and monitoring systems will show larger savings. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Worldwide, patients who visit health-care facilities generally have to wait very long to be attended by physicians and professional nurses. In South Africa, the Cape Triage Score system was implemented with great success in Emergency departments in the Cape Metropole. In primary health-care clinics the concern is that patients have to wait too long for service delivery, even if they are very ill and need hospitalisation. In this research study the role of triage in reducing waiting times in primary health-care clinics was examined. The Cape Triage Score system that was used in Emergency departments in the private sector and also in public hospitals was adapted for a pilot intervention study. This was done to determine if the utilisation of this system can reduce the waiting times of patients visiting primary health-care clinics. The researcher utilised a quantitative design with an intervention, after measuring the baseline waiting time. The strategies applied included an exploratory, descriptive and contextual strategy. The study was carried out in three steps according to the objectives set for the study. Firstly, the baseline assessment of the current waiting times in two PHC clinics in a sub-district of the North West Province was done. A waiting-time survey checklist was used to determine the baseline waiting time of patients visiting primary health-care clinics. These waiting-time survey checklists consisted of a few components that assessed different aspects of waiting time. The second objective was to explore and describe literature in order to understand primary health-care waiting times, triage and related constructs. The third objective was to pilot an adapted Cape Triage Score system to determine if the intervention contributed to reducing waiting times for patients visiting primary health-care clinics. Data was analysed according to Cohen’s effect sizes. The comparison between the baseline waiting times and pilot intervention waiting-time assessment was done according to Cohen’s effect sizes. The analysis of the data indicated a practical significance for the component where the pilot Cape Triage Score system was applied, as patients were referred to the physician and professional nurse according to the severity of their condition. The outcome of the study indicated no reduction in the overall waiting time of patients visiting primary health-care clinics due to the different components of the waiting-time survey checklist. Finally, the research was evaluated, limitations were identified and recommendations were stipulated for nursing practice, education, research and policy. / MCur, North-West University, Potchefstroom Campus, 2014

Control and monitoring networks often operate on AC/DC power systems. DC batteries and chargers are commonly used on industrial plants as auxiliary DC power systems for these control and monitoring networks. The energy demand and load profiles for these control networks differ from application to application. Proper design, sizing, and maintenance of the components that forms part of the DC control power system are therefore required. Throughout the load profile of a control and monitoring system there are various peak currents. The peak currents are classified as inrush and momentary loads. These inrush and momentary loads play a large role when calculating the required battery size for an application. This study investigates the feasibility of using supercapacitors in conjunction with batteries, in order to reduce the size of the required battery capacity. A reduction in the size of the required battery capacity not only influences the cost of the battery itself, but also influences the hydrogen emissions, the physical space requirements, and the required rectifiers and chargers. When calculating the required size batteries for an auxiliary power system, a defined load profile is required. Control and monitoring systems are used to control dynamic processes, which entails a continuous starting and stopping of equipment as the process demands. This starting and stopping of devices will cause fluctuations in the load profile. Ideally, data should be obtained from a live plant for the purpose of defining load profiles. Unfortunately, due to the economic risks involved, installing data logging equipment on a live industrial plant for the purpose of research, is not allowed. There are also no historical data available from which load profiles could be generated. In order to evaluate the influence of supercapacitors, complex load profiles are required. In this study, an alternative method of defining the load profile for a dynamic process is investigated. Load profiles for various applications are approximated using a probabilistic approach. The approximation methodology make use of plant operating philosophies as input to the Markov Chain Monte Carlo simulation theory. The required battery sizes for the approximated profiles are calculated using the IEEE recommended practice for sizing batteries. The approximated load profile, as well the calculated battery size are used for simulating the auxiliary power system. A supercapacitor is introduced into the circuit and the simulations are repeated. The introduction of the supercapacitor relieves the battery of the inrush and momentary loads of the load profile. The battery sizing calculations are repeated so as to test the influence of the supercapacitor on the required battery capacity. In order to investigate the full influence of adding a supercapacitor to the design, the impact on various factors are considered. In this study, these factors include the battery size, charger size, H2 extraction system, as well as maintenance requirements and the life of the battery. No major cost savings where evident from the results obtained. Primary reasons for this low cost saving are the fixed ranges in which battery sizes are available, as well as conservative battery data obtained from battery suppliers. It is believed that applications other than control and monitoring systems will show larger savings. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Worldwide, patients who visit health-care facilities generally have to wait very long to be attended by physicians and professional nurses. In South Africa, the Cape Triage Score system was implemented with great success in Emergency departments in the Cape Metropole. In primary health-care clinics the concern is that patients have to wait too long for service delivery, even if they are very ill and need hospitalisation. In this research study the role of triage in reducing waiting times in primary health-care clinics was examined. The Cape Triage Score system that was used in Emergency departments in the private sector and also in public hospitals was adapted for a pilot intervention study. This was done to determine if the utilisation of this system can reduce the waiting times of patients visiting primary health-care clinics. The researcher utilised a quantitative design with an intervention, after measuring the baseline waiting time. The strategies applied included an exploratory, descriptive and contextual strategy. The study was carried out in three steps according to the objectives set for the study. Firstly, the baseline assessment of the current waiting times in two PHC clinics in a sub-district of the North West Province was done. A waiting-time survey checklist was used to determine the baseline waiting time of patients visiting primary health-care clinics. These waiting-time survey checklists consisted of a few components that assessed different aspects of waiting time. The second objective was to explore and describe literature in order to understand primary health-care waiting times, triage and related constructs. The third objective was to pilot an adapted Cape Triage Score system to determine if the intervention contributed to reducing waiting times for patients visiting primary health-care clinics. Data was analysed according to Cohen’s effect sizes. The comparison between the baseline waiting times and pilot intervention waiting-time assessment was done according to Cohen’s effect sizes. The analysis of the data indicated a practical significance for the component where the pilot Cape Triage Score system was applied, as patients were referred to the physician and professional nurse according to the severity of their condition. The outcome of the study indicated no reduction in the overall waiting time of patients visiting primary health-care clinics due to the different components of the waiting-time survey checklist. Finally, the research was evaluated, limitations were identified and recommendations were stipulated for nursing practice, education, research and policy. / MCur, North-West University, Potchefstroom Campus, 2014

Avhandlingen, som är en kvalitativ studie, rör yrkesgruppen undersköterskor inom hälso- och sjukvården. Syftet med studien har varit att studera och bidra med ökad kunskap, dels om villkoren för lärande och kunskapsbildning i arbetslivet, dels mer specifikt om undersköterskors arbete, arbetsvillkor samt villkor för lärande och utveckling på arbetsplatsen. Avhandlingens teoretiska referensram utgår från tidigare forskning och teoribildning om arbetsrelaterat lärande som kunnat sammanfattas i en modell, i vilken fyra olika grupper av faktorer, som är betydelsefulla för lärande i och genom arbetet, beskrivs. De fyra är: 1) Arbetets och organisering 2) Formell och icke-formell utbildning 3) Sociala aspekter och 4) Individuella faktorer. Tre olika sjukvårdsenheter; en akutsjukvårdsenhet, en barnsjukvårdsenhet och en operationssjukvårdsenhet, samtliga vid ett större sjukhus, ingår i studien. 17 undersköterskor och 5 vårdenhetschefer har intervjuats. Avhandlingen visar att undersköterskor som verkar inom akut eller traumatisk sjukvård också har ett varierat och oförutsett arbete, vilket ger dem goda möjligheter till lärande och utveckling. Vidare har undersköterskor som arbetar med uppgifter inom vårdens kärnverksamhet möjlighet att lära i arbetet. Avgörande i sammanhanget är att dessa arbetsuppgifter uppfattas som intressanta, meningsfulla och stimulerande. Lärande underlättas för de undersköterskor som arbetar vid en vårdenhet där de görs delaktiga i vårdarbetet och arbetsgemenskapen. Undersköterskor som arbetar tillsammans med andra yrkesgrupper kan ha möjlighet att lära i arbetet. Även delegering av arbetsuppgifter har betydelse för möjligheterna att lära. Avhandlingen visar också att undersköterskor kan hindras från att lära i arbetet om den sjuksköterska som de arbetar närmast (i vårdpar eller i team) inte tillåter dem att utföra vissa arbetsuppgifter. Det framkommer också att undersköterskor som saknar intresse, eller ork hindras från att lära och utvecklas i arbetet. Undersköterskor har begränsade möjligheter att delta i, och utvecklas genom formella läraktiviteter. Kursutbudet är litet och en del av de kurser som erbjuds rör inte vårdens kärnverksamhet. / The dissertation, which is a qualitative study, concerns auxiliary nurses in the health care. The aim of the study has partly been to generate knowledge about the prerequisites for learning and knowledge development in working life and partly to specifically study the work of auxiliary nurses, their working conditions and the prerequisites for learning and development in the workplace. The dissertation’s theoretical frame of reference is based on previous research and theories of workplace learning and have been summarised in a model. Four different groups of factors that are significant for learning in and through the work are described. The four groups are: 1) Work and organisation 2) Formal and non-formal learning activities, 3) Social aspects and 4) Individual factors. Three different health care units – an emergency care unit, a children’s unit and an operating unit – in a large hospital were included in the study. 17 auxiliary nurses and 5 care unit managers were interviewed. The dissertation shows that the work of auxiliary nurses involved in emergency care or the treatment of trauma is varied and unpredictable, which creates good opportunities for learning and development. Further, auxiliary nurses who are involved in core care activities are able to learn on the job. What is crucial here is that these duties are perceived as interesting, meaningful and stimulating. Learning is facilitated for auxiliary nurses who work in a care unit where they are involved in both the work and the work community. Auxiliary nurses who collaborate with other professional groups may find it easier to learn on the job. The delegation of tasks also affects the possibilities to learn. The dissertation also shows that auxiliary nurses can be prevented from learning on the job if the nurse with whom they work (in a nursing pair or team) does not allow them to perform certain tasks. It is also clear that auxiliary nurses who lack interest or stamina are prevented from learning and developing. Auxiliary nurses have limited opportunities to take part in and develop through formal learning activities. Few courses are available for auxiliary nurses, and those offered are seldom dealing with core care work.

Enantiopure α-alkyl-substituted aldehydes are widely recognised as important building blocks in synthesis. Despite this, methods to prepare such substrates are limited. Strategically, asymmetric intermolecular S_N2 α-alkylation represents a highly straightforward transformation, but still remains an elusive feat. This thesis describes efforts to address this challenge, with attempted access to enantioenriched α-alkyl aldehydes by way of C-alkylation of chiral, non-racemic, hindered aldenamines using simple alkyl halides. Enamines derived from four types of auxiliary (a tropane, an oxazolidine, a pyrrolidine and a homotropane) have been prepared, and their alkylation profile examined. While the desired levels of asymmetric induction were not attained, use of the tropane and homotropane auxiliaries, which differ only by a single methylene group, interestingly, gave complimentary diastereocontrol during alkylation with EtI. The observed stereoselectivity is supported by density functional studies performed for ethylation of both enamines. Additionally, in the course of preparing the homotropane a highly efficient asymmetric synthesis of a homotropinone bearing gem-α-substitution has been developed.