Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

The basic objective of this investigation was to identify and to examine factors determining the volume of imports of inshell and shelled Brazil nuts in major importing countries: the United States, the Federal Republic of Germany and the United Kingdom. The approach followed involved the construction and analysis of an adjusted bilateral trade model of this commodity market, based upon consumer demand theory and an understanding of the industry. This model, employing single stage least squares method (OLS), identifies a number of factors as important determinants of the volume of nut imports, such as: (a) the price of the commodity relative to the general price level, (b) consumer's income, and (c) price or quantity of related commodities. Demand for Brazil nuts is price inelastic in all markets, except for shelled nuts in the German market. Because of the peculiar situation of Brazil as, practically, the only producer and exporter of Brazil nuts, some consideration is given to the possibility of increasing gross revenues by means of market control. / Graduation date: 1981

Thesis (M.Sc. Hons.) -- University of Western Sydney, Hawkesbury. / Includes bibliographical references.

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Typescript. / Thesis (Ph. D.)--University of Hawaii, 1969. / Bibliography: leaves [195]-197. / xi, 197 l illus

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

With the advent of supergravity and superstring theory, it is of great importance to study higher-dimensional solutions to the Einstein equations. In this dissertation, we study the higher dimensional Kerr-AdS metrics, and show how they admit further generalisations in which additional NUT-type parameters are introduced. The choice of coordinates in four dimensions that leads to the natural inclusion of a NUT parameter in the Kerr-AdS solution is rather well known. An important feature of this coordinate system is that the radial variable and the latitude variable are placed on a very symmetrical footing. The NUT generalisations of the highdimensional Kerr-AdS metrics obtained in this dissertation work in a very similar way. We first consider the Kerr-AdS metrics specialised to cohomogeneity 2 by appropriate restrictions on their rotation parameters. A latitude coordinate is introduced in such a way that it, and the radial variable, appeared in a very symmetrical way. The inclusion of a NUT charge is a natural result of this parametrisation. This procedure is then applied to the general D dimensional Kerr-AdS metrics with cohomogeneity [D/2]. The metrics depend on the radial coordinate r and [D/2] latitude variables µi that are subject to the constraint Ei µ2i = 1. We find a coordinate reparameterisation in which the µi variables are replaced by [D/2]−1 unconstrained coordinates yα, and put the coordinates r and yα on a parallel footing in the metrics, leading to an immediate introduction of ([D/2]−1) NUT parameters. This gives the most general Kerr-NUT-AdS metrics in D dimensions. We discuss some remarkable properties of the new Kerr-NUT-AdS metrics. We show that the Hamilton-Jacobi and Klein-Gordon equations are separable in Kerr- NUT-AdS metrics with cohomogeneity 2. We also demonstrate that the general cohomogeneity-n Kerr-NUT-AdS metrics can be written in multi-Kerr-Schild form. Lastly, We study the BPS limits of the Kerr-NUT-AdS metrics. After Euclideanisation, we obtain new families of Einstein-Sassaki metrics in odd dimensions and Ricci-flat metrics in even dimensions. We also discuss their applications in String theory.

In this study, Effect of Molybdenum disulfide (MoS2), Anglamol(SP) and Tricresyl phosphate(TCP) additives on the tribological performance of loosing and tightening process of screw and nut were investigated by using a self-developed tribological tester. The screw and nut are made of SCM 440 and HBsC3, respectively. Result shows that the MoS2 additives with Grease#0 give the best tribological performance but TCP with Grease#0 is worst. With increasing concentration of MoS2 , the lubricant life increases, reaches a maximum at about 5wt% and finally diminishes with decreasing. Surface pressure between the screw and nut, the lubricant life increases. Under the surface pressure of 2.64kg/mm2, the lubricant life can achieve 8000 cycles or more. To maintain the long life of the screw and nut, the surface pressure should be equal to or less than 2.64kg/mm2.

With the advent of supergravity and superstring theory, it is of great importance to study higher-dimensional solutions to the Einstein equations. In this dissertation, we study the higher dimensional Kerr-AdS metrics, and show how they admit further generalisations in which additional NUT-type parameters are introduced. The choice of coordinates in four dimensions that leads to the natural inclusion of a NUT parameter in the Kerr-AdS solution is rather well known. An important feature of this coordinate system is that the radial variable and the latitude variable are placed on a very symmetrical footing. The NUT generalisations of the highdimensional Kerr-AdS metrics obtained in this dissertation work in a very similar way. We first consider the Kerr-AdS metrics specialised to cohomogeneity 2 by appropriate restrictions on their rotation parameters. A latitude coordinate is introduced in such a way that it, and the radial variable, appeared in a very symmetrical way. The inclusion of a NUT charge is a natural result of this parametrisation. This procedure is then applied to the general D dimensional Kerr-AdS metrics with cohomogeneity [D/2]. The metrics depend on the radial coordinate r and [D/2] latitude variables µi that are subject to the constraint Ei µi² = 1. We find a coordinate reparameterisation in which the µi variables are replaced by [D/2] - 1 unconstrained coordinates yα, and put the coordinates r and yα on a parallel footing in the metrics, leading to an immediate introduction of ([D/2] - 1) NUT parameters. This gives the most general Kerr-NUT-AdS metrics in D dimensions. We discuss some remarkable properties of the new Kerr-NUT-AdS metrics. We show that the Hamilton-Jacobi and Klein-Gordon equations are separable in Kerr- NUT-AdS metrics with cohomogeneity 2. We also demonstrate that the general cohomogeneity-n Kerr-NUT-AdS metrics can be written in multi-Kerr-Schild form. Lastly, We study the BPS limits of the Kerr-NUT-AdS metrics. After Euclideanisation, we obtain new families of Einstein-Sassaki metrics in odd dimensions and Ricci-flat metrics in even dimensions. We also discuss their applications in String theory.