No description available.

Electrical generating sets powered by gas turbines are required for many applications, in particular for emergency situations due to their critical attributes; high reliability, lightweight, small size, multi-fuel capabilities, low maintenance, low noise and low gas emissions. This research contends that a permanent magnet axial flux (PMAF) high-speed generator with a small gas turbine engine offers advantages over the radial flux permanent magnet generators. Higher power densities can be achieved with the axial flux configuration when compared to their counter parts of the radial flux machines of similar output power. The attributes of the PMAF machines were certainly appealing; lightweight, small size, high efficiency and ease of construction. In this research, a design approach for the PMAF high-speed generator which accounts for the mechanical and electrical aspects was provided. The machine's key components such as retainment ring was carefully designed and the materials utilised in their structures were appropriately selected to insure high mechanical integrity, ease of construction and low manufacturing cost. The generator's principle dimensions were determined from a theoretical model which was derived from the machine's main design parameters. This theoretical model was then correlated by some empirical coefficients determined through the manipulation of the experimentally validated finite element (FE) results. The analytical results have shown that with the appropriate design considerations, PMAF high-speed generators can be designed with high power densities in the range of 6-8 kW/kg and high efficiencies ideally in the range of 94 - 96 %. The mechanical integrity and the steady state electrical performance of the machine were analysed using three-dimensional (3D) FE models. More in this research, a parametric study was carried out on the most influential parameters of the machine to improve its electrical performance through minimise rotor and stator eddy current losses. In addition, the total harmonic distortion in the output waveform was minimised through the appropriate and careful design of the magnet shape and topology with the aid of 3D electromagnetic FE analysis. Furthermore, using FE it was possible to design, optimise and analyse the rotor back-iron disc through the selection of best material, shape and size for use in the PMAF high-speed generator. A prototype of the PMAF high-speed generator was constructed and tested preliminary at low speed for the purpose of the evaluation of the electrical performance of the machine. Experimental results have shown that the machine was capable to meet the design requirements. For the mechanical integrity of the machine, the rotors were safely tested on a cold run test rig at the speed of 47,000 rpm. This thesis describes also the trends and the technical details in the manufacturing, construction and experimental setup for the PMAF high-speed generator.

In der vorliegenden Arbeit wird ein Maschinenkonzept präsentiert, welches für die Additive Fertigung von großvolumigen Titanbauteilen speziell entwickelt wurdet. Hierbei wird mit den Direct-Energy_Deposition Verfahren das Bauteil in einer separaten Inertgasatmosphäre erzeugt. Zur Führung der Prozesstechnik soll erstmals ein Roboter verwendet werden, der ebenfalls in dieser Atmosphäre verbaut ist. Dieser ist allerdings schwierigen Bedingungen ausgesetzt, da die Spannungsfestigkeit sowie die Isolationsschwelle in Argon im Vergleich zu Luft drastisch reduziert sind.

Small satellites and CubeSats have established themselves within the aerospace community because of their low cost and high return on investment. Many CubeSats are developed in a short time frame and often leverage commercial off the shelf components for quick turnaround missions. With regard to the Electrical Power System, commercially available products typically use a centralized architecture. However, a centralized architecture is not reusable, since missions that require additional solar arrays or batteries would necessitate a redesign of the power system. With the range of CubeSat sizes and mission goals, it is obvious that a one-size-fits-all solution is not appropriate. This thesis details a reusable and scalable power system architecture applicable to a variety of missions. Reusability is achieved by using common building blocks or "modules," where the same modules can be used between missions. Scalability is achieved by not limiting the number of modules that can be connected together—more modules can be added as needed. In this system, solar arrays and battery units connect directly to a common bus, supplying an unregulated voltage to each subsystem. These subsystems then regulate the bus voltage to their individual needs. The power system also features direct energy transfer and solar-only operation.

Wire and Arc Additive Manufacturing is a novel Additive Manufacturing technology. As a result, the process for progressing from a solid model to manufacturing code, i.e. the Part Programming process, is undeveloped. In this report the Part Programming process, unique for Wire and Arc Additive Manufacturing, has been investigated to answer three questions; What is the Part Programming process for Wire and Arc Additive Manufacturing? What are the requirements on the Part Programming process? What software can be used for the Part Programming process? With a systematic review of publications on Wire and Arc Additive Manufacturing and related subjects, the steps of the Part Programming process and its requirements have been clarified. The Part Programming process has been used for evaluation of software solutions, resulting in multiple recommendations for implemented usage. Verification of assumptions, made by the systematic review, has been done by physical experiments to give further credibility to the results.

A scaled direct energy conversion device was built to convert kinetic energy of singly ionized helium ions into an electric potential by the process of direct conversion. The experiments in this paper aimed to achieve higher potentials and higher efficiencies than ever before. The predicted maximum potential that could be produced by the 150 kV accelerator at the Texas A&M Ion Beam Lab was 150 kV, which was achieved with 92% collection efficiency. Also, an investigation into factors affecting collection efficiency was made. It was concluded that charge was being lost due to charge exchange occurring near the surface of the target which caused positive target atoms to be ejected from the face and accelerated away. Introducing a wire mesh near the face of the target with an electric potential, positive or negative, which aimed to control secondary ion emissions, did not have an effect on the collection efficiency of the system. Also, it was found that the gas pressure inside the chamber did not have an effect on the collection efficiency. The goal of achieving higher electric potentials and higher efficiencies than previous direct conversion work was met.

The rising cost of energy coupled with an increasing awareness of Greenhouse Gas (GHG) emissions has led to a concerted effort to reduce fossil fuel Energy Use (EU) in all sectors. Sugarcane production in South Africa is dependent on fossil fuel to provide a source of energy for production. To remain commercially and environmentally sustainable, measures need to be taken to reduce EU and increase EU efficiencies of on-farm operations. The first step toward realising this is to identify and quantify energy inputs. Following on from this, total GHG emissions, also known as carbon footprint, can be estimated. The primary objective of this research is to develop an energy calculator to estimate EU in sugarcane production in South Africa. The results generated by the calculator highlight areas of high energy intensity and low energy efficiencies at three different levels of detail. Based on these results, changes in management practices and technological improvements can be made to reduce EU and carbon footprint. Case studies were used to test the functionality of the calculator. Results from the case studies show that, in irrigated sugarcane production, the harvest and transport process together with irrigation account for a majority of the total on-farm EU. For one of the case studies, an estimated 20 % saving in the total on-farm EU was identified and can be achieved if appropriate technology is adopted in irrigation practices. Less significant energy savings were realised when in-field tractor operations were optimised for best tractor-implement matching. It is envisaged that the energy calculator will help farmers minimise on-farm EU and subsequently reduce input costs and carbon footprint. It will also provide a valuable tool for researchers to benchmark and profile EU in sugarcane production in South Africa. Research focussed on the sustainable production of sugar, from the agricultural to milling phase is of high priority at present. The quantification of on-farm EU in sugarcane production will form a critical component of such research. / M.Sc.Eng. University of KwaZulu-Natal, Pietermaritzburg 2014.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2008. / Includes bibliographical references (leaves 121-130). Also available online.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

No description available.