The threat posed by non-ferrous metal theft to industries in South Africa is substantial but is also regarded with indifference. A reason for this view may be that the criminal act is ordinarily not accompanied by violence and the target of the crime is an object that is far removed from the vicinity of the majority of South Africans. Non-ferrous metal theft may sometimes even be erroneously termed a victimless crime. This study endeavours to shed light on the complexities of non-ferrous metal theft and the industrial dangers that may be suffered if this crime is not eradicated. A case study from the mining industry was used to examine the nature and extent of non-ferrous metal theft. A mixed methods approach was followed in terms of which qualitative and quantitative research was done sequentially to provide the best possible representation of the situation. The participant allowed access to data over a six-year period as well as access to mine employees for interviews to assist with understanding the safety and security measures that the mine put in place to protect its workforce. This information led to another realisation, namely that if non-ferrous metal thieves cut an electricity supply line that is critical for life support and transportation in the mine, mineworkers may succumb to the harsh conditions underground. It also became evident that the police and the criminal justice system must develop a better understanding of the seriousness of non-ferrous metal theft. If this does not happen in the near future, managing the consequences of nonferrous metal theft at South African mines will become a mammoth task. Such mines and other industries affected by non-ferrous metal related theft must collaborate with each other and the police in order to understand the nature of the crime and to ensure that the prosecution of the perpetrators is handled properly. These industries should also subscribe to a pragmatic approach to crime prevention whereby various components from different crime prevention strategies are used to address the issues being experienced and whereby a unique crime prevention model for each industry and mining site can be developed. / Police Practice / M.A. (Policing)

Les bobinages des machines électriques tournantes actuelles sont, pour la plupart, isolés avec des matériaux issus de la chimie organique. La limite en température des bobinages actuels se situe au-dessous de 240°C. L’augmentation significative de la température de fonctionnement d’une machine permettrait d’envisager, indirectement, une augmentation de la densité de courant dans les conducteurs actifs. Dans ces conditions, ces nouvelles machines peuvent présenter une puissance, tant massique que volumétrique, supérieures à celles exploitées actuellement. De plus, les matériaux magnétiques permettent vraisemblablement de fonctionner jusqu’à 800°C. La limite technologique actuelle pour les machines est clairement l’isolant des conducteurs électriques. Ce sujet de thèse propose de définir une approche théorique couplée à des validations expérimentales pour définir les matériaux les mieux adaptés aux machines hautes températures en termes de mise en œuvre et de performances électriques. La conception, repensée autour du bobinage, sera concrétisée par le calcul d’une machine asynchrone à haute température (400°C au cœur du bobinage). Le bobinage devra être placé au cœur de la démarche de conception des machines en adaptant les formes et les propriétés des circuits magnétiques aux caractéristiques des nouvelles bobines. / The windings that are currently used in electrical machines are mostly insulated based on organic insulation. The temperature limit of these windings is up to 240°C. Increasing the working temperature of electrical motors means, indirectly the increasing of current density on the main conductors. Therefore these new motors may provide a higher mass and volume power as classical machines. Furthermore, the magnetic materials can work up to 800 °C. Indeed, in reality technical limit today is the wire insulation. The objective of thesis is to define a theoretical approach combined with experimental validations for identify the appropriate electrical materials used on high-temperature electrical machines. Design is fixed around the winding, that will implemented by calculating a high-temperature asynchronous machine (400°C of windings). The windings are placed as the base of machine design and will determine the geometrical shape and properties of magnetic core.

The submitted work deals with the methods for manufacturing and analysis of contacts on crystalline silicon solar cells. It is focused on selective processes for the production of solar cells metal contacts. The masking feature of silicon nitride is used for selective silicon etching, selective phosphorus diffusion and selective electro-less nickel deposition. Properties of metal contacts precursors are investigated using optical microscopy and their electrical properties using methods based on a four-point probe method. Results are used for the manufacturing of silicon, solar cell with an innovative type of the structure of the front side metallization: chemical nickel, conductive adhesive and copper wire. This approach allows to reduce shading of the front area of PV cells with the ability to avoid usage of busbars. The another advantage of this approach is in replacement of costly silver in at least 2/3 cross section of the front side metallization. Selective ablation of silicon nitride layer was conducted by means of IR laser beam.

Предметом исследования является производство прямоугольной медной проволоки для электротехнических целей. Приведен патентно-литературный обзор, включающий в себя некоторые особенности производства медной проволоки, а также способы ее производства, оборудование и инструмент. Представлена общая технологическая схема производства прямоугольной медной проволоки. Также приведена информация, касающаяся схемы напряженного состояния в зоне очага деформации при волочении и конфигурация канала волоки. Помимо вышеприведенной, приведена информация, касающаяся испытаний проволоки на растяжение и анализ их результатов. / The subject of the study is production of rectangular copper wire for electrical purposes. There are patent and literature review which include several features of production of copper wire, methods of production, equipment and tools. Given the general technological scheme of production of rectangular copper wire. Given information about scheme of stress state in deformation zone when drawing and configuration of die hole. Also given information about tensile test and analysis of its results.

This work deals with the option of substitute aluminum for copper as winding material in induction motor in several variants and compare them. The advantages and disadvantages of these materials for the application are mentioned. The default element is the machine with power 29 kW, 2p = 4, which is the basis for other variants. It is about the verification of the default copper wire machine with cataloging data and then verification of several aluminum wire variants of the machine. Veryfying the machine designs is performed on the basis of three programs - RMxprt, ANSYS Maxwell and Matlab. In all of these programs, the machine calculations were realized for copper and aluminum winding in point close to the nominal. Final results are evaluated. There are also heat and ventilation calculations of the machine.