Abstract In this literary, we discuss with structure and morphology improvement of GaN epilayer on c-sapphire by multi-step method in molecular-beam epitaxy. Our research is caused for the critical results of defect in GaN epilayer and rough surface morphology. In order to solve these problems we used a novel technique which we called multi-step method. In this thesis, the results of X-ray, SEM, AFM all demonstrated the achievement in our composition. However, we obtained the results of full width of half maxima (FWHM) of (0002) and (10 2) XRD rocking curves with 60~120 arcseconds and 700~ 1200 arcseconds from a series of multi-step samples respectively. Comparing with previous measurement, multi-step method is relatively superior, and the measurement of AFM roughness is under 2 nm from the series of multi-step samples. If we discuss the flat area further, we can get smoother surface which roughness is about 0.4 nm. It is obviously to recognize the flat and rough regions, but in SEM image we made sure that the flat region occupied the greater part of surface. So, in this literary we verified that the method of multi-step can improve the structure and morphology of GaN by molecular-beam epitaxy.

Thesis (M.S. Ed.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 81-87). Also available via the Internet.

Thesis (M.A.)--Catholic Theological Union at Chicago, 1996. / Vita. Includes bibliographical references (leaves 136-138).

Thesis (M.A.)--York University, 2007. Graduate Programme in Dance. / Typescript. Includes bibliographical references (leaves 92-96). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29296

Thesis (M.A.)--Emmanuel School of Religion, Johnson City, Tenn., 2003. / Vita. Includes bibliographical references (leaves [108]-111).

Thesis (M.A.)--Emmanuel School of Religion, Johnson City, Tenn., 2003. / Vita. Includes bibliographical references (leaves [108]-111).

Thesis (M.A.)--Emmanuel School of Religion, Johnson City, Tenn., 2003. / Vita. Includes bibliographical references (leaves [108]-111).

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[pt] Este trabalho apresenta o desenvolvimento e testes de um sistema de acionamento de motores de passo em nível de micropasso, utilizando duas tecnologias distintas. A crescente capacidade de regulação e a possibilidade de chaveamentos precisos das correntes de fase dos motores de passo têm possibilitado o surgimento de acionamentos em micropasso cada vez mais eficientes. Com isto, a nociva, e, muitas vezes, limitadoras trepidação dos motores de passo operando em passo inteiro ou meio passo, foi quase todos os projetos de automação e robótica. Nos acionamentos convencionais, é fundamental o acompanhamento do nível da corrente na fase do motor. Este acompanhamento, por ser realizado em baixos níveis de tensão e na presença de ruído, acaba sendo um sério inconveniente exigindo uma montagem elaborada e eventuais filtros. O presente trabalho apresenta duas propostas de acionamentos em micropasso. Uma, do tipo convencional com realimentação de corrente de fase, e outra, em que a necessidade do acompanhamento da corrente é eliminado. Os teste indicam a viabilidade do novo conceito, apresentando resultados extremamente animadores. / [en] The present work discusses the development and experimental test of a step motor driver operating in microstepping mode. The work explores two different technologies for the power switching tecnhique. The increassing ability of fast and precise curent switching, brought to the market high performance step motors drivers operating in microstepping resolution. The main advantage of working with microstepping in a smooth operation with very low vibration level when compared with traditional full step of half step driving mode. This fact, made possible to specify step motors to many automatic and robotic systems where only servomotors could be used up to a very short past. In conventional chopper driving, it is necessary to sense the phase current, in order to chop the voltage when the level exceeded. This is done using very small resistor in series with the motor phases. The problem is that the low voltage across the resistor is easily affected by electromagnetic noise giving a false information to the chopper. The present research has explored the possibility of voltage chopping based on fixed timing with the elimination of the whole sensing circuitry. The first results are very encouraging.

Children in stepfamilies accept, for the most part, both their fathers - their noncustodial biological father and their stepfather - as part of the family, even when the children are representing the ideal family as they imagine it. Important factors in children's level of acceptance of their stepfathers include children's perception of a warm relationship between them and their stepfather, and between them and their mother, as well as a positive emotional climate in the family overall. Stepfathers are accepted by children if they impose a lower level of parental control over them. Children are also more likely to accept their stepfathers the longer the time has elapsed since the divorce of their biological parents, and the longer they have lived with their stepfather. Children wish to have closer relationships with their non-custodial biological. They would also prefer if stepfathers exercised less authority over their families. Children often express a wish for the relationships among the significant adults in the family to be free of conflict. As expressed by one of the children: "I am not happy that dad has moved away, but if my parents have decided that it should be so, then at least I want everyone to get along."