The resupply interface mechanism RMS compatibility test

Spacecraft on-orbit servicing consists of exchanging components such as payloads, orbital replacement units (ORUs), and consumables. To accomplish the exchange of consumables, the receiving vehicle must mate to the supplier vehicle. Mating can be accomplished by a variety of docking procedures. However, these docking schemes are mission dependent and can vary from shuttle bay berthing to autonomous rendezvous and docking. Satisfying the many docking conditions will require use of an innovative docking device. The device must provide fluid, electrical, pneumatic and data transfer between vehicles. Also, the proper stiffness must be obtained and sustained between the vehicles. A device to accomplish this, the resupply interface mechanism (RIM), was developed. The RIM is a unique device because it grasps the mating vehicle, draws the two vehicles together, simultaneously mates all connectors, and rigidizes the mating devices. The NASA-Johnson Manipulator Development Facility was used to study how compatible the RIM is to on orbit docking and berthing. The facility contains a shuttle cargo bay mockup with a remote manipulator system (RMS). This RMS is used to prepare crew members for shuttle missions involving spacecraft berthing operations. The MDF proved to be an excellant system for testing the RIM/RMS compatibility. The elements examined during the RIM JSC test were: RIM gross and fine alignment; berthing method sequence; visual cuing aids; utility connections; and RIM overall performance. The results showed that the RIM is a good device for spacecraft berthing operations. Mating was accomplished during every test run and all test operators (crew members) felt that the RIM is an effective device. The purpose of the JSC RIM test and its results are discussed

Equivalence of two mathematical forms for the bound angular momentum of the electromagnetic field

It is shown that the mathematical form, obtained in a recent paper, for the angular momentum of the electromagnetic field in the vicinity of electric charge is equivalent to another form obtained previously by Cohen-Tannoudji, Dupont-Roc and Gilbert. In this version of the paper an improved derivation is given.Comment: 4 pages pdf, simpler derivatio

Body composition and basal metabolic rate in pre-school children : no sex difference

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.Peer reviewedPublisher PD

Parliament or protest? : The parliamentary impact of the Greens (WA) in the Legislative Council : May 1993 to May 1999

From their beginnings as a protest party in the early 1970s to their election to the federal parliaments of countries around the world, the Greens have largely been seen us the political wing of a direct action movement. As a political organisation, however, Greens are now making a transition away from an exclusive focus on direct action to mainstream parliamentary activity. The key benchmark in assessing the success or otherwise of the Greens remains the environment, and their capacity to effect changes to the benefit of the environment. This thesis, then, addresses the central question in the evolution of the Greens: To what extent is parliament an effective means by which the Greens can advance environmental causes. This is done via a case study examining the activities of the three Greens (WA) parliamentarians in the Legislative Council over two periods; during the period 1993-1997 when Jim Scott sat alone in the Council, and; during the period after the 1997 change in composition of the Council. Analysis of the second period will focus particularly on the establishment of the Standing Committee on Ecologically Sustainable Development and its reports. The effectiveness of the Green parliamentarians during these two periods is examined in three ways, by assessing; the various methods that can be used by a parliamentarian to influence legislation and the policy process; whether there has been any positive changes to legislation or policy; and under what conditions those changes were able to be made. In taking up their seats in May 1997, the three Green parliamentarians became part of the first Legislative Council to have a majority of non-conservative members. This is important, because being in the balance of power dramatically improved their ability to effect Government legislation. Prior to this, Jim Scott sat alone as the only Greens (WA) Legislative Councillor in a Coalition controlled Council between 1993 and 1997. During the debate on the Environmental Protection Act Amendment Bill 1993 he was not able to effect any changes or to initiate much debate on the legislation. The ESD Committee process shows a different approach to parliament from 1993-97. The Committee was approached as a necessity by Christine Sharp, and followed on the work of the Wilderness Society\u27s lobbying efforts at the time of the 1996 State election. Following Sharp\u27s election, she worked with the various interested parties involved in the forest industry. During this time, Sharp found that there was some common ground on issues surrounding the sustainability of forestry in W A. If Green parliamentarians find themselves in the balance of power, as from 1997 until the present, then the opportunities for change are increased. In this situation there is of course a requirement to work with the other parties that may also occupy the non-Government benches, such as the Democrats and Labor, to achieve their aims, but the possibility for change is concomitantly higher

Controlled manipulation of light by cooperative response of atoms in an optical lattice

We show that a cooperative atom response in an optical lattice to resonant incident light can be employed for precise control and manipulation of light on a subwavelength scale. Specific collective excitation modes of the system that result from strong light-mediated dipole-dipole interactions can be addressed by tailoring the spatial phase-profile of the incident light. We demonstrate how the collective response can be used to produce optical excitations at well-isolated sites on the lattice.Comment: 8 pages, 1 figur

Evolution of a localized thermal explosion in a reactive gas

Experimental observations of ignition in premixed gaseous reactants indicate that perfectly homogeneous initiation is practically unrealizable. Instead, combustion first sets in, as a rule, at small, discrete sites where inherent inhomogeneities cause chemical activity to proceed preferentially and lead to localized explosions. Combustion waves propagating away from these hot spots or reaction centers eventually envelop the remaining bulk. This study examines the spatial structure and temporal evolution of a hot spot for a model involving Arrhenius kinetics. The hot spot, characterized by peaks in pressure and temperature with little diminution in local density, is shown to have one of two possible self-similar structures. The analysis employs a combination of asymptotics and numerics, and terminates when pressure and temperature in the explosion have peaked

Lifting the Publishing Curtain: The editor interview project of the EPAT Editorial Development Group (EDG)

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Even decentralised parties aren’t immune from the instinct to centralise

Green Parties are often decentralised and highly internally democratic. But how do decentralised party arrangements respond to power, or proximity to power? Looking at the case of the Australian Greens, Narelle Miragliotta and Stewart Jackson find that there has been gradual growth of the party’s national level, even in spite of formal provisions which guarantee the autonomy of the state organisations

Helical Symmetry in Linear Systems

We investigate properties of solutions of the scalar wave equation and Maxwell's equations on Minkowski space with helical symmetry. Existence of local and global solutions with this symmetry is demonstrated with and without sources. The asymptotic properties of the solutions are analyzed. We show that the Newman--Penrose retarded and advanced scalars exhibit specific symmetries and generalized peeling properties.Comment: 11 page