Design for Manufacture of a Brushless Synchronous Servomotor

This thesis presents research into the design of brushless permanent magnet (BPM) interior rotor synchronous servomotor for both performance and manufacturability. The investigation has been supported by experimental evidence gathered with the aid of two prototype servomotors, having the same frame sizes and stator stack lengths, designed by the author and manufactured by the sponsoring company, Control Techniques Dynamics (CTD) Ltd. One servomotor, upon which the research is focussed, has the relatively new segmented stator structure containing concentrated windings. The other servomotor has a conventional structure with a solid stator containing distributed windings and this has provided the means of assessing the degree of improvement attainable with the new structure. It has been established that the new structure enables more cost-effective manufacture than attainable with the conventional structure. A significant contribution of the research programme is the special notch for retention of the surface mounted permanent magnets in the rotor. This innovation enables a more uniform and smaller air gap, which greatly improves the dynamic and thermal performance for a given frame size and stator stack length, thereby advancing the state of the art. This, together with the greatly reduced stator winding overhang in the new structure, enables a physically smaller motor for a given application, thereby reducing active material usage. Also the design methodology has focused on reducing energy and eliminating waste in the manufacturing process. Regarding the thermal aspects, only natural cooling has been considered. Conduction, convection and radiation heat transfer in the servomotor has been investigated theoretically, by simulation and by experiments to identify where design improvements can be made. The most critical area identified is the paper wall insulation and comprehensive experiments have been carried out to identify the commercially available material with the highest thermal conductivity to maximise the removal of heat from the stator windings. An array of strategically located thermocouples was used to obtain temperature distributions. The performance indicators for comparison of the new and conventional servomotors are cogging torque, iron loss and dynamic torque. The cogging torque proved to iii increase with the permanent magnet retaining feature for the new servomotor and becomes unpredictable but this disadvantage was offset by material saving and its maximum torque being approximately 40% greater than that of the conventional servomotor. The iron losses have been measured at speeds ranging from 500 r/m to 6000 r/m and at surface housing reference temperatures approximately 810C. At maximum reference winding temperature ranging from 1000C and 1250C, the dynamic torque rating performances of the new and conventional servomotor prototypes have been compared, the torque/speed characteristics being generated from a near stall speed of 50 r/m to the rated 3000 r/m. The contributions of this research programme may be summarised as follows: 1. Above all this thesis provides valuable design steps for permanent magnet synchronous servomotors using three world leading software packages (OPERA_2D, SPEED and Motor-CAD) for machine design and will therefore be a useful reference for electrical machine designers, especially beginners. 2. Material saving and simplified BPM synchronous servomotor manufacturing process for segmented stator, concentrated winding configuration. 3. Novel permanent magnet retaining method permitting more uniform and smaller air gap giving performance enhancement. 4. Systematic finite element analysis (FEA) based optimisation is applied to implement a new design principle for BPM synchronous servomotors regarding the stator parameters. 5. A simplified frequency dependent equation for open-circuit iron loss calculation. 6. Experimental and theoretical investigation of thermal impact of stator wall paper insulation entailing comparison of several different materials. 7. Direct benefit to industry through adoption of the new servomotor design by the company who supported the researc

Development of new oil/water partitioning tracers for the determination of residual oil saturation in the inter-well region of water-flooded reservoirs

Most of the hydrocarbon-rich large unexplored basins are located in remote and/or highly environmentally sensitive regions. As more and more oilfields reach maturity at the end of the secondary stage of recovery, while on average more than 50% of the original reserves of hydrocarbons are left in place, the future of oil production on the Norwegian Continental shelf (NCS) will increasingly rely on IOR projects to face the demand. A partitioning inter-well tracer test (PITT) is a type of tracer test that measures the water contactable saturation of immobile oil (SOR) in the inter-well region of water flooded reservoirs. Knowledge about SOR in the swept volumes between injector/producer pairs is a key parameter for the design and evaluation of IOR projects. The PITT explores the lag in production experienced by an oil/water partitioning tracer relatively to a passive water tracer which directly correlates to SOR. This principle was introduced to the industry in 1971 and relied on the use of molecules successfully applied in hydrology and/or labelled with radioactive nuclides for easier detection. The conditions encountered in oil reservoirs, particularly in deep oil formations, are significantly harsher than in the near surface subsoil. Thus, several unsuccessful inter-well tracer tests resulted from a poor selection of the tracer compounds used at that time because of insufficient knowledge about their behaviour under typical reservoir conditions. Much work has been done to improve the original concept of the PITT regard its deployment and interpretation. However, little effort has been put in place to establish a systematic procedure for selecting, testing and describing the dynamic behaviour of the substances used as oil/water partitioning tracers. Thus, this thesis aims to present a methodology for selection and testing of new PITT tracer candidates, with the results and findings of its application to a selected group of molecules. The methodology presented here starts by describing the base requirements for selection of new oil/water partitioning tracer candidates. Additionally, guidelines for testing and qualification are presented. There are several steps in the qualification procedure. These can be divided into static stability experiments, development of analytical methods for laboratory samples, development of analytical methods for identification and quantification of the stable molecules in real produced waters, characterisation of the oil/water partition coefficient (K) of the molecules, and dynamic flooding experiments using cores of consolidated sedimentary rock. Following this method, step by step, 16 molecules from 4 different chemical “families” were selected and tested for qualification as new oil/water partitioning tracers. The static stability experiments evaluated the thermal stability of the PITT tracer candidates, in the absence and presence of typical reservoir rock materials, different pH conditions, and elevated salinity up to 150 0C for 12 weeks contact time. Ultra-performance liquid chromatography (UPLC) coupled with ultra-violet detection (UV) and high-resolution mass spectrometry (HRMS), and gas chromatography (GC) coupled with flame ionisation detection (FID) were the techniques used to follow the concentration of the PITT tracer candidates along the 12 weeks of experiment. UPLC-HRMS was used to try to obtain relevant information to describe the observed phenomena. The static stability experiments proved that only 5 of the 16 tested compounds were stable for 12 weeks up to 150 ℃. Two additional compounds were stable for the same period up to 125 ℃. This is sufficient to allow for their use in most oilfields, and they were thus included as possible inter-well PITT tracers. These experiments also revealed dramatic interactions between some of the studied molecules and clay minerals of undefined nature, as well as thermally driven degradation of the candidates that is well described by a pseudo-first order kinetic model. The latter two findings open the possibility of using tracers to retrieve information about temperature and geochemistry/mineralogy in the inter-well region, though the latter requires further development. A method based on sequential direct immersion (DI) headspace (HS) solid-phase microextraction (SPME) proved effective as analytical sample pre-treatment followed by GC-MS/MS for analysis of the PITT tracer candidate concentrations in real production waters. The DI-HS-SPME-GC-MS/MS method allows for quantification of the stable molecules investigated in low ng/L concentrations and introduces significant improvements in comparison to the commonly used methodologies for analysis of tracers in produced waters: it requires just 5 mL of sample and eliminates the need for use of organic solvents in the laboratory. Furthermore, sample processing times are significantly reduced as the cleaning/concentration step becomes much faster. This is of utmost importance for a PITT, as several hundreds of samples are analysed in these examinations. The characterisation of the K-values of the stable PITT tracer candidates revealed that they will likely vary along the volume swept between injector/producer pairs. K is influenced primarily by the ionic strength of the aqueous phase and composition of the hydrocarbon phase, and to a smaller extent by temperature T. The influence of temperature can, however, be very relevant: The K-value is used in the calculation of SOR together with the times of arrival of the different tracers using the same landmark of their respective production curves (i.e., the theoretically most correct is the first moments of the curves). It is likely that the temperature varies between injector and producer well-pairs. The variation of the K-value as function of T needs to be accounted for to determine accurate SOR values. Variations of the ionic strength will lead to even bigger variations of the K-value independently of the valency of the ions present in the aqueous phase. The experiments performed also confirmed the constant and reversible equilibrium distribution of the oil/water tracer candidates between hydrocarbon and aqueous phases, as well as their suitability for use on most oilfields of the NCS. The flooding experiments were performed on sandstone and chalk cores prepared both to pure water saturation and to residual oil saturation, SOR. Residence time distribution analysis (RTD) was used to interpret the production curves. These experiments proved that the PITT tracer candidates behave as water tracers in the absence of hydrocarbons, with no significant difference encountered between their production curves and the ones obtained from the reference water tracer (tritiated water). SOR was determined for two different mass recovery landmarks in each of the experiments for all partitioning tracers using the K-values previously determined in the experiments for characterisation of the K-values. Good agreement between all SOR values measured by the tracer candidates and the values determined by a balance to the oil used to prepare the cores was encountered. This is also valid when SOR measured by the tracers is compared to the value obtained by the differences in water flooded pore volumes measured by tritiated water. The methodology presented and applied in this thesis produced 7 new oil/water partitioning tracers ready to be used in oil fields with low probability of failure. The findings and observations presented here can be incorporated into reservoir models to obtain more accurate data from PITTs, and consequently better reservoir description. Furthermore, the reinjection of produced waters will lead to contaminations of the inter-well region with tracers used there. Thus, the present study offers guidelines and methods for the development of new tracers. The oil industry, service companies, and other researchers working with tracer technology will be the primary beneficiaries of this study, that will hopefully contribute to disseminate the use of PITTs by the industry. This technology has a large potential to contribute to a future efficient and profitable oil production

Colibacilose

A colibacilose é uma doença causada por estirpes patogénicas de Escherichia coli. É uma doença com graves prejuízos económicos e ocorre ao longo de todo o ano, com picos nas épocas de partos. Os animais jovens são os mais afetados, sendo a colibacilose considerada uma das principais causas de morte em efetivos de recria com leite arti cial. A ocorrência de colibacilose clínica depende do tipo e da patogenicidade da es- tirpe infetante de E. coli, da susceptibilidade do hospedeiro e da presença ou ausên- cia de fatores predisponentes. Dependendo da estirpe envolvida, distinguem-se duas formas clínicas principais: a forma entérica e a forma septicémica (colisepticemia).info:eu-repo/semantics/publishedVersio

Manual de formação para criadores de gado e para-veterinários

O presente manual foi elaborado no âmbito do projeto “Balal Gainako – Projeto de Dinamização dos Sistemas de Produção Pecuários nos Sectores de Pitche e Gabu”, Guiné-Bissau, com o financiamento da União Europeia e do Camões – Instituto da Cooperação e da Língua, I.P. tendo como objetivo geral contribuir para o crescimento económico e para a redução da pobreza na região de Gabu, através da dinamização do setor pecuário familiar. O projeto executado pelo Instituto Marquês de Valle Flôr em parceria com a DIVUTEC – Associação Guineense de Estudos e Divulgação de Tecnologias Apropriadas - tem como objetivo específico aumentar a produtividade dos sistemas de produção pecuários, dando particular ênfase ao maneio alimentar e sanitário do gado bovino. No âmbito do projeto, uma das lacunas encontradas foi a ausência de técnicos auxiliares de sanidade animal, ou seja, os para-veterinários, que pudessem apoiar os criadores em ligação, quer à Associação de Criadores de Gado de Gabu – Gaare Batoden, quer aos técnicos veterinários da Direção Provincial de Pecuária de Gabu. Assim, neste documento procuramos, de uma forma simples, sistematizar os conhecimentos veiculados nas ações de formação no quadro do projeto aos para-veterinários, aos criadores de gado e aos associados da Gaare Batoden. O manual começa por definir as competências e o papel do técnico auxiliar de sanidade animal, caracteriza as principais doenças e formas de tratamento dos ruminantes, aborda as questões práticas do maneio pecuário e sugere formas de melhorar a alimentação animal na região de Gabu, na Guiné-Bissau. Parte das orientações, nomeadamente no respeitante aos para-veterinários foi organizada de acordo com “A manual for the primary animal health care worker” da Organização para a Agricultura e Alimentação das Nações Unidas (FAO), publicado pela primeira vez em 1994. Todavia, não se trata de uma tradução para a língua portuguesa, nem se pretende substituir o referido manual. Por fim, uma palavra de agradecimento para os autores, primeiramente pelo seu entusiasmo ao longo do projeto, pelas incansáveis dicas e apoio, bem como pelas missões, as ações de formação e o trabalho de sistematização exposto neste manual. A sua colaboração, bem como a de outros colegas, foi possível através da parceria com o Instituto Politécnico de Bragança, nomeadamente através do Prof. Dr. Albino Bento, Diretor da Escola Superior Agrária do IPB, a quem muito agradecemos.Bayerinfo:eu-repo/semantics/publishedVersio

International evidence on stock returns and dividend growth predictability using dividend yields

Este artigo examina a previsibilidade dos retornos e do crescimento de dividendos utilizando dividend yields em sete mercados desenvolvidos: EUA, Reino Unido, Japão, França, Alemanha, Itália e Espanha. No total, esses países representam cerca de 85% do índice Morgan Stanley Capital International (MSCI) World Index. O uso de séries temporais longas com dados atualizados permite a comparação não apenas entre países, mas também entre períodos, colocando em perspectiva a existência ou não de mudanças perceptíveis desde a década de 1980. A maior parte da literatura sobre esse tópico está focada nos EUA. Essa ênfase nos EUA é ainda mais pronunciada quando se trata de examinar a relação entre imprevisibilidade de dividendos e suavização de dividendos. Há também a necessidade de saber se as relações já documentadas para o período pós-Segunda Guerra Mundial ainda se mantêm durante as últimas três décadas, quando as bolsas de valores foram submetidas a um alto nível de turbulência em todo o mundo. A relação entre dividend yield, retornos e crescimento de dividendos é central para se compreender o funcionamento dos mercados de capitais e tem implicações consideráveis na precificação de ativos de capital e nas estratégias de investimento. No geral, os resultados mostram que, mesmo para os mercados de capitais desenvolvidos, não existe um padrão claro sobre a capacidade preditiva dos dividend yields sobre os retornos de ações e o crescimento de dividendos; ao contrário, essas relações parecem ser dependentes do tempo e específicas de cada país. Para cada país, a capacidade preditiva do dividend yield é examinada em um modelo VAR estrutural de primeira ordem, aplicando testes de significância bootstrap, e o grau de suavização de dividendos é avaliado utilizando quatro modelos de ajuste parcial para o comportamento dos dividendos. Além disso, realizou-se uma análise fora da amostra, utilizando pseudo-R2 e uma estatística ajustada de erro quadrático médio de previsão (EQMP) normal. Para o período pós-Segunda Guerra Mundial, os retornos são previsíveis, mas os dividendos são imprevisíveis nos EUA e no Reino Unido, enquanto o padrão oposto é observado na Espanha e na Itália. Na Alemanha, há evidências de previsibilidade no curto prazo para retornos e dividendos, enquanto na França apenas os retornos são previsíveis. No Japão, nenhuma das variáveis pode ser prevista. Os resultados da suavização de dividendos mostram que os dividendos são mais persistentes nos EUA e no Reino Unido; entretanto, não há uma conexão clara entre suavização de dividendos e previsibilidade para os outros países. Uma conclusão importante a se reter da análise fora da amostra é que a previsibilidade dos retornos após a Segunda Guerra Mundial, especialmente presente nos EUA, pareceu estar ausente nas últimas três décadas, provavelmente devido à turbulência sofrida pelos mercados de ações durante este último período.Este artigo examina a previsibilidade dos retornos e do crescimento de dividendos utilizando dividend yields em sete mercados desenvolvidos: EUA, Reino Unido, Japão, França, Alemanha, Itália e Espanha. No total, esses países representam cerca de 85% do índice Morgan Stanley Capital International (MSCI) World Index. O uso de séries temporais longas com dados atualizados permite a comparação não apenas entre países, mas também entre períodos, colocando em perspectiva a existência ou não de mudanças perceptíveis desde a década de 1980. A maior parte da literatura sobre esse tópico está focada nos EUA. Essa ênfase nos EUA é ainda mais pronunciada quando se trata de examinar a relação entre imprevisibilidade de dividendos e suavização de dividendos. Há também a necessidade de saber se as relações já documentadas para o período pós-Segunda Guerra Mundial ainda se mantêm durante as últimas três décadas, quando as bolsas de valores foram submetidas a um alto nível de turbulência em todo o mundo. A relação entre dividend yield, retornos e crescimento de dividendos é central para se compreender o funcionamento dos mercados de capitais e tem implicações consideráveis na precificação de ativos de capital e nas estratégias de investimento. No geral, os resultados mostram que, mesmo para os mercados de capitais desenvolvidos, não existe um padrão claro sobre a capacidade preditiva dos dividend yields sobre os retornos de ações e o crescimento de dividendos; ao contrário, essas relações parecem ser dependentes do tempo e específicas de cada país. Para cada país, a capacidade preditiva do dividend yield é examinada em um modelo VAR estrutural de primeira ordem, aplicando testes de significância bootstrap, e o grau de suavização de dividendos é avaliado utilizando quatro modelos de ajuste parcial para o comportamento dos dividendos. Além disso, realizou-se uma análise fora da amostra, utilizando pseudo-R2 e uma estatística ajustada de erro quadrático médio de previsão (EQMP) normal. Para o período pós-Segunda Guerra Mundial, os retornos são previsíveis, mas os dividendos são imprevisíveis nos EUA e no Reino Unido, enquanto o padrão oposto é observado na Espanha e na Itália. Na Alemanha, há evidências de previsibilidade no curto prazo para retornos e dividendos, enquanto na França apenas os retornos são previsíveis. No Japão, nenhuma das variáveis pode ser prevista. Os resultados da suavização de dividendos mostram que os dividendos são mais persistentes nos EUA e no Reino Unido; entretanto, não há uma conexão clara entre suavização de dividendos e previsibilidade para os outros países. Uma conclusão importante a se reter da análise fora da amostra é que a previsibilidade dos retornos após a Segunda Guerra Mundial, especialmente presente nos EUA, pareceu estar ausente nas últimas três décadas, provavelmente devido à turbulência sofrida pelos mercados de ações durante este último período.This paper examines stock returns and dividend growth predictability using dividend yields in seven developed markets: United States of America (US), United Kingdom (UK), Japan, France, Germany, Italy, and Spain. Altogether, these countries account for around 85% of the Morgan Stanley Capital International (MSCI) World Index. The use of the long time series with up-to-date data allows the comparison not only between countries, but also across periods, putting into perspective the existence or not of noticeable changes since the 1980’s. The majority of the literature on this topic is US-centered. This emphasis on the US is even more pronounced when it comes to examining the relationship between the dividend unpredictability and dividend smoothing. There is also the need to know if the relationships already documented for the post-Second World War (WWII) period still hold during the last three decades, when stock markets were subjected to a high level of turbulence worldwide. The relationship between dividend yields and returns and dividend growth is central to understand the functioning of capital markets, and has considerable implications for capital asset pricing and investment strategies. Overall, the results show that even for developed capital markets there is no clear pattern on the predictive ability of dividend yields on stock returns and dividend growth, instead these relationships seem to be time-dependent and countryspecific. For each country, the predictive ability of the dividend yield is examined in a first-order structural VAR framework by applying bootstrap significance tests and the degree of dividend smoothing is assessed using four partial-adjustment models for the dividend behavior. Additionally, an out-of-sample analysis is conducted using pseudo-R2 and a normal mean squared prediction error (MSPE) adjusted statistic. For the post-WWII period, returns are predictable, but dividends are unpredictable in the US and the UK, while the opposite pattern is observed in Spain and Italy. In Germany, there is some evidence of short-term predictability for both returns and dividends, while in France only returns are predictable. In Japan, neither variable can be forecasted. The dividend smoothing results show that dividends are more persistent in the US and the UK, however, there is no clear connection between dividend smoothness and predictability for the other countries. An important conclusion to retain from the out-of-sample analysis is that the predictability of returns after the WWII, especially present in the US, appeared to have been missing in the last three decades, most probably due to the turmoil experienced by the stock markets during this last period