Autonomous homing and docking tasks for an underwater vehicle

This paper briefly introduces a strategy for autonomous homing and docking tasks using an autonomous underwater vehicle. The control and guidance based path following for those tasks are described in this work. A standard sliding mode for controller design is briefly given. The method provides robust motion control efforts for an underwater vehicle’s decoupled system whilst minimising chattering effects. In a guidance system, the vector field based on a conventional artificial potential field method gives a desired trajectory with a use of existing information from sensors in the network. A well structured Line-of-Sight method is used for an AUV to follow the path. It provides guidance for an AUV to follow the predefined trajectory to a required position with the final desired orientation at the dock. Integration of a control and guidance system provides a complete system for this application. Simulation studies are illustrated in the paper

Look-up Tables to Link 1991 Population Statistics to the 1998 Local Government Areas

Between 1995 and 1998 the local authority structure and geography of the United Kingdom was substantially revised. The two-tier system of local government was abolished in Wales, Scotland, and in parts of non-metropolitan England, and replaced with a single-tier system. This involved the creation of a new set of local authority area boundaries which in many places cut across those of the old districts. In addition, many of the local authorities unaffected by the reorganisation nonetheless had experienced small - though demographically significant - boundary changes since the last census. By the time the final phase of the reorganisation came into effect on 1st April 1998 the local government map of the United Kingdom was very different from that of April 1991. There is a need therefore to provide demographic and other geographically based data for the new geography for years prior to 1998. This paper aims to fill a part of this requirement by focusing on two important issues. First, it describes a look-up table detailing exactly how the 1998 local government geography relates to 1991 Census areas, and second, it sets out methods for producing 1991 Census data and mid-1991 population estimates (including single year age detail) for the new geography. A selection of the results produced by the described methods is included in tables and population pyramids

'Face Up to the Truth': Helping Gay Men in Vietnam Protect Themselves from AIDS.

Appropriate AIDS prevention information is not available in Vietnam for men who have sex with men. Current AIDS prevention messages can be misunderstood with potentially dangerous results. We outline some features of gay culture in a provincial city in Vietnam. We describe the activities of a peer educator who made contact with a small group of young gay men during 1996 and 1997. All the young men were ill-informed about AIDS. Their attitudes and sexual practices made them vulnerable to AIDS. The peer educator provided clear information and emotional support. The peer education was done without government endorsement and on a very low budget

Symplectic Deformations of Calabi-Yau threefolds

This manuscript from August 1995 (revised February 1996) studies the Kaehler cone of Calabi-Yau threefolds via symplectic methods. For instance, it is shown that if two Calabi-Yau threefolds are general in complex moduli and are symplectic deformations of each other, then their Kaehler cones are the same. The results are generalizations of those in the author's previous paper "The Kaehler cone on Calabi-Yau threefolds" (Inventiones math. 107 (1992), 561-583; Erratum: Inventiones math. 114 (1993), 231-233), where the behaviour of the Kaehler cone under deformations of the complex structure was studied -- these results may be recovered as a special case from this manuscript. The techniques used involve studying tamed almost complex deformations of the complex structure on the Calabi-Yau threefold, and in particular proving the non-vanishing of certain Gromov-Witten invariants, associated to codimension one faces of the Kaehler cone. This in turn involves a detailed study of primitive contractions on a smooth Calabi-Yau threefold, in particular for the case of Type III contractions. More detailed information concerning Gromov-Witten invariants associated to codimension one faces of the Kaehler cone may be found in a recent preprint of the author.Comment: 25 pages, plain TeX, to be published in J. Diff. Geom. 45 (1997

Operational alternatives for LANDSAT in California

Data integration is defined and examined as the means of promoting data sharing among the various governmental and private geobased information systems in California. Elements of vertical integration considered included technical factors (such as resolution and classification) and institutional factors (such as organizational control, and legal and political barriers). Attempts are made to fit the theoretical elements of vertical integration into a meaningful structure for looking at the problem from a statewide focus. Both manual (mapped) and machine readable data systems are included. Special attention is given to LANDSAT imagery because of its strong potential for integrated use and its primary in the California Integrated Remote Sensing System program

Neurobiological abnormalities in the first few years of life in individuals later diagnosed with Autistic Spectrum Disorder : A review of recent data

Peer reviewedPublisher PD