<p>Detta arbete beskriver hur processen för att skapa en generell hjulklass har gått till. Klassen skall skapas med hjälp av fysikmotorn Bullet. Den generella hjulklassen skall användas som en komponent i Craft Animations fordonssimuleringar. Det finns stöd för 3 olika former av hjulupphängning. Oberoende hjul medkollisionskroppar, Länkade hjul med kollisionskroppar samt Hjul med strålföljning. Rapporten visar hur konstruktionen av dessa hjulupphängningar går till. Slutligen görs en sammanställning där de olika teknikerna diskuteras och jämförs.</p>

I Sverige är det idag färre kvinnor än män som väljer att vidareutbilda sig i ämnet fysik, trots att flickor generellt sett har högre slutbetyg i ämnet än pojkar när de slutar årskurs 9. Detta leder till en ojämn könsfördelning inom de yrken som kräver kunskaper i ämnet fysik och fysikyrket blir därmed mansdominerat. Syftet med denna kvantitativa undersökning var att ta reda på hur stora skillnaderna är mellan pojkar och flickor i kunskaperna i samt attityderna till ämnet fysik bland barn i årskurs 9 i Sverige, samt hur sociala faktorer såsom normer och familjebakgrund påverkar deras attityd till ämnet fysik. I studien undersöktes också vad dessa skillnader kan bero på samt hur man eventuellt skulle kunna minska dem. Detta undersöktes med hjälp av att elever i årskurs 9 dels fick göra ett kunskapstest i Newtonsk dynamik, dels fick svara på en semistrukturerad enkät med frågor som behandlar attityder till naturvetenskapliga ämnen med huvudfokus på ämnet fysik. Resultatet analyseras och diskuteras framför allt ur ett pragmatiskt perspektiv och till viss del ur ett hermeneutiskt perspektiv. Resultatet visade att flickor har en mer negativ attityd till ämnet fysik än vad pojkar har och att de i lägre grad än pojkarna kan tänka sig att jobba som fysiker i framtiden. Resultatet visade dock att flickor har en något mer positiv attityd till skolans fysiklektioner än vad pojkarna har och att de i högre utsträckning än pojkarna föredrar att lära sig genom att läraren har genomgång. Flickorna har också något lägre kunskaper i Newtonsk dynamik än vad pojkarna har. Resultatet visade också en hög korrelation mellan elevernas attityd till skolans fysiklektioner och intresset för att lära sig mer inom ämnet fysik, vilket är en indikation på att skolans fysiklektioner har en betydande roll för elevernas attityd till ämnet. Korrelationen mellan elevernas erfarenheter av fysik utanför skolan och elevens intresse för att lära sig mer inom ämnet fysik visade sig vara medelhög, vilket är en indikation på att sociala faktorer såsom vad eleven gör på sin fritid spelar roll för elevens attityd till ämnet fysik. Antalet informanter var dock för lågt och felmarginalerna för stora för att kunna dra några generella slutsatser. Eleverna hade överlag en negativ attityd till ämnet fysik och en stor majoritet av dem kan inte tänka sig att jobba som fysiker i framtiden. Många av eleverna motiverade detta med att de tycker att fysik är ett svårt ämne och önskade att fysikundervisningen görs med lättbegriplig för dem, gärna med kopplingar till deras egen vardag.

Insulation materials are selected based on their R-value, which is a measure of the thermal resistance of a material. Therefore, the higher the R-value of a material, the better its thermal insulation performance. There are two major groups of insulation materials: bulk and reflective insulation (or combine bulk and reflective). Bulk insulation is design to resist heat transfer due to conduction and convection. Reflective insulation resists radiant heat flow due to its high reflectivity and low emissivity. Insulation materials are not restricted to these materials only. Other low thermal conductive materials can be used as long as the primary aim of thermal insulation, which is increasing thermal resistance, is achieved. Hence, the aim of the project is to investigate the insulation ability of Translucent Water-based Acrylic Paint (TWAP) on the thermal performance of Low Cost Housing (LCH). To achieve the aim of the study, the inner surfaces of the external walls of LCH was coated with TWAP. Before the inner surfaces of the external walls were coated, the following techniques were used to characterised the paint; Scanning Electron Microscopy/ Energy Dispersive X-ray spectroscopy (SEM/EDX), Fourier Transform Infra-Red (FTIR) and IR thermography. SEM/EDX was adapted to view the surface morphology and to detect the elemental composition responsible for the thermal resistance of the TWAP. FTIR spectroscopy was used to determine the functional group and organic molecular composition of the paint. The heat resistance of TWAP was analyzed using IR thermography technique. A low cost house located in the Golf Course settlement in Alice, Eastern Cape, South Africa under the Nkonkobe Municipality Eastern Cape was used as a case study in this research. The house is facing geographical N16°E, It comprises a bedroom, toilet and an open plan living room and kitchen. The house has a floor dimension of 7.20 m x 5.70 m, giving an approximate area of 41 m2. The roof is made of galvanized corrugated iron sheets with no ceiling or any form of roof insulation. The walls of the buildings are made of the M6 (0.39 m 0.19 m x 0.14 m) hollow concrete blocks, with no plaster or insulation. The following meteorological parameters were measured: temperature, relative humidity, solar irradiance, wind speed and wind direction. Eleven type-K thermocouples were used to measure the indoor temperature, inner and outer surfaces temperature of the building walls. Two sets of HMP50 humidity sensors were used to measure the indoor and outdoor relative humidity as well as the ambient temperature. The indoor temperature and relative humidity were measured at a height of 1.80 m so as to have good indoor parameter variation patterns that are not influenced by the roof temperature. The outdoor relative humidity sensor together with a 03001 wind sentry anemometer/vane and Li-Cor pyranometer were installed at a height of 0.44 m above the roof of the building. Wind speed and direction were measured by the 03001 wind sentry anemometer/vane, while solar radiation was measured by the Li-Cor pyranometer. The entire set of sensors was connected to a CR1000 data logger from which data are stored and retrieved following a setup program.

The need for sustainable alternative energy technology is becoming more urgent as the demand for clean energy environment increases. For centuries, electricity in South Africa has been derived mostly from coal with results growing in multifold annually due to concerns about the impact of fossil fuel utilization related to emission of greenhouse gasses. It is practically impossible at the moment to replace coal with biomass resources because of the low energy value of biomass. However, the conversion of coal has experienced some challenges especially during its gasification which includes, but are not limited to a high reaction temperature exceeding 900°C which most gasifiers cannot achieve, and if achieved in most cases, combustion of the resulting syngas usually occur, leading to low conversion efficiency and the risk of reaching extremely high temperatures that may result in pressure build up and explosion may also occur. Therefore, this study sought to investigate the possibility of co-gasifying corn stover with coal with the ultimate aim establishing the best mixing ratio that would result in optimum co-gasification efficiency after computer simulation. Proximate and ultimate analysis, including energy values of corn stover and coal as well as their blends were undertaken and results showed significant differences between the two feedstocks and narrow range composition betwee their blends in terms of properties and energy value. Corn stover showed a higher fraction of volatile matter and lower ash content than coal, whereas those of their blends vary considerably in terms of physical properties. Differences in chemical composition also showed higher fraction of hydrogen and oxygen, and less carbon than coal while those of their blends vary according to the ratio of corn stover to coal and vice versa in the blends. The thermal stability of corn stover and coal as well as their blends were also established and the maximum temperature reached for thermal degradation of their blends was 900°C as depicted by TGA analysis. The SEM results revealed no changes in morphology of the pure samples of corn stover and coal which was due to the fact that a pre-treatment of the samples were not undertaken, whereas the blends showed significant changes in morphology as a result of blending. However, luminous and non-luminous features were noticed in both SEM images of the blends with the 10% coal/90% corn stover blend having higher percentages of luminosity as a result of higher quantities of coal in the blend. The energy density of the samples were also measured and found to be 16.1 MJ/kg and 22.8 MJ/kg for corn stover and coal respectively. Those of their blends varied from 16.9 to approximately 23.5 MJ/kg. These results were used to conduct computer simulation of the co-gasification process in order to establish the best blend that would result in maximum co-gasification efficiency. The blend 90% corn stover/10% coal was found to be the most suitable blend for co-gasification resulting in an efficiency of approximately 58% because its conversion was efficiently achieved at a temperature that is intermediate to that of coal and biomass independently. The simulation results were, however, compared with experimental data found in the literature and results showed only slight variation between them.

The first chapter considered the fundamental processes of laser operation: photon absorption, spontaneous and stimulated emissions. These processes are considered when designing a laser gain medium. A four-level laser scheme was also illustrated. Then, the basic components and operating principle of a simple laser system was presented using a diode end-pumped Nd:YAG solid state laser resonator. The second chapter considered laser light as light rays propagating in the resonator and extensively discussed the oscillating field in the laser resonators. It examined the characteristics of the fundamental Gaussian mode and the same theory was applied to higher-order modes. Chapter three started with an introduction to beam shaping and proceeded to present a review of some intra-cavity beam shaping techniques, the use of; graded phase mirrors, difractive elements { binary phase elements and spiral phase elements. Also, a brief discussion was given on the concept of conventional holography and digital holography. The phase-only spatial light modulator (SLM) was presented, which by default is used to perform (only) phase modulation of optical fields and how it can be use to perform amplitude modulation also. Finally, a detailed discussion of the digital laser which uses the intracavity SLM as a mode selection element was presented, since it was the technique used in the experiment. The elegance of dynamic on-demand mode selection that required only a change of the grey-scale hologram on the SLM was one quality that was exploited in using the digital laser. The next two chapters presented the experiments and results. The concept of the digital laser was first used in the experiment in chapter four, to assemble a stable diode endpumped Nd:YAG solid state laser resonator. Basically, the cavity was of hemispherical configuration using an intra-cavity SLM (virtual concave mirror) as a back re ector and a at mirror output coupler. A virtual concave mirror was achieve on the SLM by using phase modulation to generate the hologram of a lens, which when displayed on the SLM made it to mimic a concave mirror. Then the next phase was using symmetric Laguerre-Gaussian mode function, of zero azimuthal order to generate digital holograms that correspond to amplitude absorbing concentric rings. These holograms, combined with the hologram that iv mimics a concave mirror were used on the SLM to perform high-order Laguerre-Gaussian modes selection in the cavity. The fifth chapter presented the results of the mode selection and considered the purity of the beam at the output coupler by comparing measured modal properties with the theoretical prediction. The outcome confirmed that the modes were of high purity and quality which further implied that the cavity was indeed selecting single pure high-order modes. The results also demonstrated that forcing the cavity to oscillate at higher-order modes (p = 3) extracted 74% more power from the gain medium compared to the fundamental mode (p = 0), but this extra power is only accessible beyond a critical pump input power of 38.8 W. Laser brightness describes the potential of a laser beam to achieve high intensities while still maintaining a large Rayleigh range. It is a property that is dependent on beam power and its quality factor. To achieve high brightness one needs to generate a beam that extracts maximum power from the gain with good beam quality. Building on the experiments demonstrated in this study, one can make the correct choices of output coupler's re ectivity, the laser gain medium's length and doping concentration and the pump mode overlap for a particular mode to further enhance energy extraction from the cavity, and then using well known extra-cavity techniques to improve the output beams quality factor by transforming the high-order mode back to the fundamental mode. This will electively achieve higher laser brightness.

More and more people worldwide are becoming “carbon conscious”. This means they are becoming increasingly aware of the imminent adverse effects of global warming. Of late there has been an urgent drive for governments to be on the forefront of all carbon mitigation initiatives. One such drive involves the United Nations Framework Convention on Climate Change whose parties have been meeting regularly under the banner of Conference of Parties (COP) since 1995. At this conference, parties to the convention review progress made in dealing with climate change. Also key to the deliberations in such meetings are better ways of developing cleaner “carbon free” energy sources. Energy sources of this nature are commonly known as renewable energy sources. In essence global energy trends are constantly moving towards development of more renewable energy sources. It is an undeniable fact that some of viable renewable energy sources especially those with bulk capacity are usually located remotely from load centers. This inevitable reality necessitates the construction of long distance bulk power transmission corridors to link generation sites with load centers. Due to its many inherent advantages over High Voltage Alternate Current (HVAC) for long distance power transmission, High Voltage Direct Current (HVDC) is gradually winning the favor of many utilities. In fact, recent advances in HVDC technology have encouraged many utilities to explore the possibility of harnessing remotely located renewable energy sources which would have otherwise not been viable with HVAC transmission. Through the unfortunate and inevitable phenomenon known as corona effect, overhead HVDC conductors suffer real power losses to the air dielectric surrounding them. Through corona, part of the energy carried on the transmission line is expended through ionization and movement of charges in the air dielectric. This study combined physics, mathematical as well engineering concepts to review corona phenomenon around HVDC lines with specific emphasis on space charge generation and motion within ionized DC fields as well as the influence of temperature on corona discharge or power loss. Also, unlike HVAC, performance of an HVDC system relies heavily on the availability of a reliable and robust telecommunication system. One of the key ways of ensuring reliability of a telecommunication system is by making sure that reliable power supplies are in place to power remote repeater stations. A novel concept of quasi-autonomous corona-based power supply (or QC power supply in short) that works on the principle of magnetohydrodymic (MHD) power generation was developed. A small scale experiment was then designed to assess the feasibility of such power supplies. The experiment was conducted with DC supply of a maximum rated voltage of 30 kVDC and generated up to 6 VDC at an optimum ambient temperature of 23°C. These results have confirmed that with further development QC power supplies have the potential of proving reliable power to remotely located repeaters or any other small critical loads along the stretch of the HVDC transmission line. Practical HVDC transmission systems operate voltages in the excess of 500 kV. By linear extrapolation of the above mentioned results; one would expect to yield up to 100-, 120- and 160-VDC from a 500-, 600- and 800- kV HVDC system, respectively. Although the study succeeded in conceptualizing a CMHD idea upon which the novel QC power supply was developed, quite extensive and rigorous design, modeling, prototyping and experimentation processes are still required before the first QC power supply can be commissioned on a practical HVDC line

The increasing population and the rapid economic growth in South Africa have led to higher consumption of food resulting in the generation of large amounts of waste. In addition, South Africa has plenty of biomass from cattle, donkeys, horses, goats, pigs, chicken and sheep. However, anaerobic digestion could be an alternative solution for the utilization of these kinds of waste due to its environmental and economic benefits. Therefore, the main focus of the research was design, construct a field batch biogas digester, monitor its performance when fed with co-substrates and model the methane yield for an optimized mixing ratio.

This research project was based on the Design, Implementation and Evaluation of a Photovoltaic Water heating system in South Africa, Eastern Cape Province. The purpose of the study was to design and investigate the scientific and economic contribution of direct water cooling on the photovoltaic module. The method involved performance comparison of two photovoltaic modules, one naturally cooled (M1) and the other, direct water cooled module (M2). Module M2 was used to produce warm water and electricity, hence, a hybrid system. The study focused on comparing the modules’ efficiency, power output and their performance. The temperatures attained by water through cooling the module were monitored as well as the electrical energy generated. A data logger and a low cost I/V characteristic system were used for data collection for a full year. The data were then used for performance analysis of the modules. The results of the study revealed that the directly water cooled module could operate at a higher electrical efficiency for 87% of the day and initially produced 3.63% more electrical energy each day. This was found to be true for the first three months after installation. In the remaining months to the end of the year M2 was found to have more losses as compared to M1 as evidenced by the modules’ performance ratios. The directly water cooled module also showed an energy saving efficiency of 61%. A solar utilization of 47.93% was found for M2 while 8.77% was found for M1. Economically, the project was found to be viable and the payback period of the directly cooled module (M2) system was found to be 9.8 years. Energy economics showed that the system was more sensitive to the price changes and to the energy output as compared to other inputs such as operation and maintenance and years of operation. A generation cost of R0.84/kWh from the system was found and when compared to the potential revenue of R1.18 per kWh, the system was found to enable households to make a profit of 40.5 %. Use of such a system was also found to be able to contribute 9.55% towards carbon emission reduction each year. From these results, it was concluded that a directly cooled photovoltaic/thermal heating (PV/T) system is possible and that it can be of much help in terms of warm water and electricity provision.

Miniaturisation has been the holy grail of mobile technology. The ability to move around with our gadgets, especially the ones for communication and entertainment, has been what semiconductor scientists have battled over the past decades. Miniaturisation brings about reduced consumption in power and ease of mobility. However, the main impediment to untethered mobility of our gadgets has been the lack of unlimited power supply. The battery had filled this gap for some time, but due to the increased functionalities of these mobile gadgets, increasing the battery capacity would increase the weight of the device considerably that it would eventually become too heavy to carry around. Moreover, the fact that these batteries need to be recharged means we are still not completely free of power cords. The advent of low powered micro-controllers and sensors has created a huge industry for more powerful devices that consume a lot less power. These devices have encouraged hardware designers to reduce the power consumption of the gadgets. This has encouraged the idea of wireless power transmission on another level. With lots of radio frequency energy all around us, from our cordless phones to the numerous mobile cell sites there has not been a better time to delve more into research on WPT. This study looks at the feasibilities of WPT in small device applications where very low power is consumed to carry out some important functionality. The work done here compared two rectifying circuits’ efficiencies and ways to improve on the overall efficiencies. The results obtained show that the full wave rectifier would be the better option when designing a WPT system as more power can be drawn from the rectenna. The load also had a great role as this determined the amount of power drawn from the circuitry.

There is growing interest in research and development activities on biomass gasification technologies as an alternative to fossil fuels technologies. However not much has been done in terms of technology transfer, particularly in under-developed and developing countries such as South Africa. This is mainly because of the lack of resources such as funding. Most parts of the under-developed and developing countries fall within rural areas and semi-urban centers, which are endowed with biomass resources. South Africa has a number of sawmill operators who generate tons of biomass waste during processing of timber; the large proportion of this is burned in furnaces as a means for waste management while a very small proportion is collected and used by people in rural areas for cooking their food. The majority of people in rural areas of South Africa are either unemployed or cannot afford the current energy services. The main aim of this research was to establish the viability of electricity generation for community economic development through biomass gasification, specifically using the locally designed System Johansson Biomass Gasifier™ (SJBG), and to establish the efficiency of the gasifier and associated components with a view of developing strategies to enhance it. The study established the technical and economic feasibility of using the SJBG to generate low-cost electricity for community empowerment. The study also developed strategies to improve the particle collection efficiency of the cyclone. In addition to this, a low-cost gas and temperature monitoring system capable of monitoring gas and temperature at various points of the gasifier was developed. The system was built from three Non- Dispersive Infrared gas sensors, one Palladium/Nickel gas sensor and four type K thermocouples. The study also investigated the impact of fuel compartment condensates on gasifier conversion efficiency. This is an area that has not yet been well researched since much has been done on energy recovery using combined heat and power applications that do not utilize the energy in condensates because these are produced in the gasifier and drained with chemical energy stored in them. The study established that the condensates do not have a significant impact on efficiency.