A determinação das principais propriedades magnéticas de um ímã permanente geralmente requer sistemas de medição sofisticados e custosos. Este trabalho analisa e propõe um sistema de caracterização de ímãs permanentes de Terras Raras e Cerâmicos à temperatura ambiente de baixo custo e de implementação mais simples. Para isso, o Histerisímetro de Entreferro Variável, HEV, é concebido e estudado. Ele consiste de um circuito magnético formado pelo ímã permanente sob caracterização, uma culatra de aço, um entreferro variável, bobinas de magnetização e desmagnetização de baixa potência, uma sonda de efeito Hall com seu respectivo gaussímetro, um fluxímetro com sua bobina exploradora, o circuito eletrônico de comando das bobinas de excitação e a interface a um sistema de instrumentação virtual. Para demonstrar os desenvolvimentos do trabalho são apresentados o estado da arte da caracterização dos ímãs permanentes, conceitos básicos de magnetismo em relação aos ímãs permanentes, instrumentação necessária para sua caracterização, a concepção e modelagem do HEV, os resultados dos testes realizados e uma abrangente análise de suas incertezas. Com isso é demonstrado que o Histerisímetro de Entreferro Variável é uma alternativa de caracterização de ímãs permanentes com desmagnetização linear com incertezas dentro do que é definido pela norma. / The determination of the main magnetic properties of permanent magnets usually requires sophisticated and expensive measuring systems. This work analyses and proposes a low-cost system for the characterization of Rare Earth and Ceramics permanent magnets at room temperature with simpler implementation. It comprehends a magnetic circuit with the permanent magnet under test, a steel yoke with appropriate pole pieces, a variable air gap, low power magnetization and demagnetization coils, a Hall Effect probe with its respective gaussmeter, a fluxmeter with its own search coil, a coil driver electronic circuit and a virtual instrumentation system (computer plus graphical interface software). To demonstrate the developments of the work, it is presented the state of the art of permanent magnets characterization, basic concepts of magnetism related to permanent magnets, the instrumentation required for its characterization, the HEV design and modeling, the results of the tests and a comprehensive analysis of related uncertainties. Thus, it is shown that the Variable Gap Hysteresimeter is an alternative characterization system for linear demagnetization permanent magnets with uncertainties within those defined by the standards.

Energy resources are under tremendous pressure with society’s ever increasing need for electricity. However, resources are becoming scarce and the effect of our power generation on the environment is cause for concern. The cost of electricity is also increasing and thus the need to reduce energy consumption is apparent. Most electrical energy generated is consumed by electric motors. Most of these motors are induction motors because they are reliable, efficient and durable. Though these motors are highly efficient, there is still room for improvement when the strain on electrical energy is taken into account. Constructing motors with better efficiency can result in a reduction in energy consumption and cost savings to the consumer. One method of increasing a motor’s efficiency is to use permanent magnets in the construction of the motor’s core. Permanent magnets eliminate the excitation losses experienced by induction machines, thereby increasing the motor’s efficiency. A retrofit design is considered because of the ease of manufacturing for motor suppliers and the ability to apply the solution to existing operating induction machines. The prototype will lay the foundation for future optimisation strategies. The optimised design should provide improved efficiency with a minimum effect on the motors already operating in industry. The design process followed uses the design principles for inductions machines and for sizing permanent magnets. The design is then verified through the use of finite element method software packages, FEMM and ANSYS Maxwell®, and validated by performance testing. A comparison is drawn between the calculated results and the results determined from the performance analysis. The retrofit design performed as expected during the testing with some discrepancies in final values attributed to the manufacturing process. However, the efficiency is lower than designed and requires the implementation of machine optimisation strategies. / MSc (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Energy resources are under tremendous pressure with society’s ever increasing need for electricity. However, resources are becoming scarce and the effect of our power generation on the environment is cause for concern. The cost of electricity is also increasing and thus the need to reduce energy consumption is apparent. Most electrical energy generated is consumed by electric motors. Most of these motors are induction motors because they are reliable, efficient and durable. Though these motors are highly efficient, there is still room for improvement when the strain on electrical energy is taken into account. Constructing motors with better efficiency can result in a reduction in energy consumption and cost savings to the consumer. One method of increasing a motor’s efficiency is to use permanent magnets in the construction of the motor’s core. Permanent magnets eliminate the excitation losses experienced by induction machines, thereby increasing the motor’s efficiency. A retrofit design is considered because of the ease of manufacturing for motor suppliers and the ability to apply the solution to existing operating induction machines. The prototype will lay the foundation for future optimisation strategies. The optimised design should provide improved efficiency with a minimum effect on the motors already operating in industry. The design process followed uses the design principles for inductions machines and for sizing permanent magnets. The design is then verified through the use of finite element method software packages, FEMM and ANSYS Maxwell®, and validated by performance testing. A comparison is drawn between the calculated results and the results determined from the performance analysis. The retrofit design performed as expected during the testing with some discrepancies in final values attributed to the manufacturing process. However, the efficiency is lower than designed and requires the implementation of machine optimisation strategies. / MSc (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

The Norwegian Network Code FIKS from the Norwegian Transmission System Operator (TSO) Statnett, states that synchronous generators ≥ 25 MVA must have a static excitation system. It also includes requirements on the step time response and the available field winding ceiling voltage of the excitation system. An improved brushless excitation system is in operation in some pilot power plants. A rotating thyristor bridge is controlled via Bluetooth. The step time response is as fast as conventional static excitation systems. However, a ceiling voltage factor of 2 requires the thyristor bridge to operate at firing angles about 60 degrees. High torque pulsations, low power factor and low utilization of the exciter is the end result. New power electronic interfaces on the shaft results in a betterutilization of the designed exciter and improves the mechanical performance as well as the controllability of the generator field winding. Permanent magnet rotating exciters increase the field forcing strength of the synchronous generator, yielding improved transient stability (Fault Ride-Through req.). Brushless exciters also reduces regular maintenance of the generator. The thesis includes experiments on a state of the art synchronous generator test setup including constructed PM exciter and different power electronic solutions. Some investigations has been done on industrial power plants as well.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Permanent magnets are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In the wind power project at Uppsala University permanent magnet synchronous generators have been studied for over a decade. However, a tool for studying demagnetization has not been available. This Ph.D. thesis covers the development of a simulation model in a commercial finite element method software capable of studying demagnetization. Further, the model is also capable of simulating the connected electrical circuit of the generator. The simulation model has continuously been developed throughout the project. The simulation model showed good agreement compared to experiment, see paper IV, and has in paper III and V successfully been utilized in case studies. The main focus of these case studies has been different types of short-circuit faults in the electrical system of the generator, at normal or at an elevated temperature. Paper I includes a case study with the latest version of the model capable of handling multiple short-circuits events, which was not possible in earlier versions of the simulation model. The influence of the electrical system on the working point ripple of the permanent magnets was evaluated in paper II. In paper III and VI, an evaluation study of the possibility of creating a generator with an interchangeable rotor is presented.  A Neodymium-Iron-Boron (Nd-Fe-B) rotor was exchanged for a ferrite rotor with the electrical properties almost maintained.

- Legal Status of an Arbitrator Main aim of this thesis is to describe the legal status of an arbitrator in international and national arbitration. Arbitration is an alternative dispute resolution which is nowadays very frequently used and which has been established in Czech Republic by Arbitration Act. Arbitrator is the most important person in arbitration because he leads the trial and makes binding and enforceable decisions. Thesis is divided into six parts which concern about alternative dispute resolutions, about arbitration generally, historical evolution of legal status of an arbitrator in Czech Republic, current legislation, legal status of an arbitrator and permanent arbitration courts and legal status of a financial arbitrator. The merit of this thesis is to grasp main problems which arise on the field of legal status of an arbitrator and describe the approach of courts and legal experts. Paper also contains comparison with the legal system of Slovakia, Germany and the United Kingdom and incorporates the latest amendments. of Arbitration Act.

Background: Ostomy surgery refers to surgical procedures that reroute the elimination process of the bowel and alters the usual form of elimination. There are different reasons why a person gets a ostomy, depending on the reason for the surgery. The number of persons living with ostomys in Sweden is unknown. However, the reaction to intestinal diversion surgery can be a devastating experience. Living with a ostomy for a longer period may affect the individual. Nurses are important members of the health care team and have a significant role in caring for patients with ostomy. Aim: The aim was to describe experiences living with a permanent ostomy. Method: A qualitative litterature-based design was used in the study. CINAHL and PubMed databases were used to search qualitative articles. Articles were analyzed and reviewed by the five-step method in Friberg. Results: The result is based on ten qualitative articles. After making the analysis three main themes and nine sub-themes were identified. The three main themes were: the altered body appearance, the changing of daily life and interference with anticipated return to normal. The sub- themes were: fear, anxiety, disgrace and irritated skin, body image, acceptance, independence, daily activities, diet, impact on relationships, supporting, loneliness and isolation. Conclusion: Having a ostomy is a major event and it affects personal self-concept and restricts their lives in various ways. Nurses need to provide education, support advice and referral for specialist help if required to promote health and reduce suffering.

Information technology is a driving factor in the process of globalisation. Improvements in the early 1990s in computer hardware, software and telecommunications greatly increased people’s ability to access information. (The Levin Institute, 2013). Globalisation is not a new concept however the pace of integration of national economies and markets has substantially increased in recent years (OECD, 2013e: 7). It can be argued that ‘globalisation’ began with Christopher Columbus and Vasco da Gama (O’Rourke and Williamson, 2000), but the term has only been in existence since the 1960s (Jeffery, 2002). It can be said that information technology has been the most recent major catalyst for global integration (The Levin Institute, 2013) which has enabled globalisation to change the way in which companies do business (PWC, 2013a). In relation to the globalisation of the world’s economies, the concept of ‘a permanent establishment’ has gained significant importance worldwide, due to the direct impact on the tax revenue generated (Nayyar, 2010). In the current era of cross-border transactions and the increase in international trade and commerce among nations, there is a continuous movement of human capital across borders. One of the most significant results of globalisation is the noticeable impact of one country’s domestic tax policies on the economy of another country. Double taxation has an adverse effect on trade and services. Taxation of the same income by two or more countries (juridical double taxation) would constitute an unfair burden on the taxpayer. (Aimurie, 2013). Many countries agree that in order to eliminate double taxation, a base of clear and predictable international tax rules must be applied in order to give certainty to both governments and businesses (OECD, 2013e: 7). Hence the question of taxing rights is created. The possibility of creating a permanent establishment in a jurisdiction by a company or its employees or an agent arises as well as the taxing rights of the tax authorities. This research report will examine the concept of a permanent establishment and its application in commercial business activities, the building and construction industry and in the activities of an agent.