Sampling of planetary surface solids for unmanned in situ geological and biological analysis - Strategy, principles, and instrument requirements

Sampling requirements for in situ geological and biological analysis of planetary surface rocks by unmanned spacecraf

Solid sulfur in vacuum: Sublimation effects on surface microtexture, color and spectral reflectance, and applications to planetary surfaces

A form of sulfur that is white at room temperature and very fluffy in texture has been found in laboratory experiments on the effects of vacuum sublimation (evaporation) on solid sulfur. This work is an outgrowth of proton sputtering experiments on sulfur directed toward understanding Jovian magnetospheric effects on the surface of Io. Fluffy white sulfur is formed on the surface of solid yellow, tan, or brown sulfur melt freezes in vacuum by differential (fractional) evaporation of two or more sulfur molecular species present in the original sulfur; S(8) ring sulfur is thought to be the dominant sublimination phase lost to the vacuum sink, and polymeric chain sulfur S(u) the dominant residual phase that remains in place, forming the residual fluffy surface layer. The reflectance spectrum of the original sulfur surface is greaty modified by formation of the fluffy layer: the blue absorption band-edge and shoulder move 0.05 to 0.06 microns toward shorter wavelengths resulting in a permanent increase in reflectivity near 0.42 to 0.46 microns; the UV reflectivity below 0.40 microns is reduced. This form of sulfur should exist in large quantity on the surface of Io, especially in hotspot regions if there is solid free sulfur there that has solidified from a melt. Its color and spectra will indicate relative crystallization age on a scale of days to months and/or surface temperature distribution history

Sound-suppressing structure with thermal relief

Sound-suppressing structure comprising stacked acoustic panels wherein the inner high frequency panel is mounted for thermal expansion with respect to the outer low frequency panel is discussed. Slip joints eliminate the potential for thermal stresses, and a thermal expansion gap between the panels provides for additional relative thermal growth while reducing heat convection into the low frequency panel

Effects of local reinforcement on nozzles in dished ends

The results of a parametric design study, to determine the optimum diameter of reinforcing pad for nozzles in the knuckle region of an ellipsoidal pressure vessel head are presented herein. The study utilised a linear elastic finite element model, created using ANSYS finite element analysis software. Nozzle parameters of diameter, offset, and wall thickness were varied to ensure the results obtained were achieved through a thorough analysis. Optimum pad sizes were obtained for thrust, in plane moment and out-of-plane moment nozzle loads. Design curves were produced, allowing maximum permitted applied stress, to be calculated for any nozzle size subject to one of the three loading conditions. Recommendations for allowable offset and treatment of loading combinations are also presented

Mitigation of welding distortion and residual stresses via cryogenic CO2 cooling - a numerical investigation

Fusion welding remains the most common and convenient fabrication method for large, thinplate welded structures. However, the resulting tendency to out-of-plane distortion exacts severe design and fabrication penalties in terms of poorer buckling performance, lack of fairness in external appearance, poor fit-up and frequent requirements for expensive rework. There are several ways to mitigate welding distortion and this study concentrates on the use of cryogenic CO2 cooling to reduce distortion. A feasible combination of welding process and cooling parameters, was investigated computationally and the resulting effects on final deformation were predicted. Three different computational strategies were developed and applied to butt-welding and fillet-welding processes, with and without the inclusion of cryogenic cooling. In the first method, a fully transient, uncoupled thermo-elastoplastic model was investigated. This method is comprehensive but not readily applicable to predict welding distortions in complex, industrial-scale, welded structures, due to the large computational requirement. More computationally efficient models are needed therefore and two further models of this type are suggested in this study. The results show good agreement between the different models, despite substantial differences in computational budget. In butt-welded plates, a significant decrease in out-of-plane distortion is obtained when cryogenic cooling is applied. In fillet-welded plates, cooling had much less effect on welding distortion. This was largely due to the size and configuration of the test case assemblies and the fact that the attached stiffener greatly increased the overall stiffness and resistance to contraction forces

The construction of the decline of children’s outdoor play as a social problem in the UK

The past three decades have seen a substantial growth of interest in children’s play in scholarly and popular writing, the mass media and government policymaking. Implicit and explicit in this growing interest is the idea that children’s play, or more specifically, a decline or lack of children’s outdoor play, represents a serious problem in the UK and other western societies and that it therefore requires the intervention of a range of professional and political powers. The rapid and widespread affirmation that claims about children’s play have received deserves critical examination. This study examines the construction of children’s play as a social problem in four major UK newspapers. Focusing on the period from 1985 to 2016, it draws on theoretical and conceptual tools from the constructionist study of social problems and methodological tools from Qualitative Media Analysis to examine the roles played by various claimsmakers in the construction of the problem and the rhetoric used in support of their cause. It hence offers important insights into the prominent position children’s play holds on the public agenda and identifies some of the underlying cultural currents from which claims about children’s play draw

The Distributional Impact of Various Road Charging Schemes for London.

This Working Paper presents results obtained using the MVA START model for London, with the primary intention of investigating the distributional impact of road pricing in various forms and at various levels. In order to look at distributional effects the START model had to be 'disaggregated' by income groups - three each for non-car owning and car-owning households. Initially, this allowed us to see the distributional impact of the LPAC Preferred Strategy, mainly involving public transport and traffic management policies. Beyond this we tested three structures (or 'regimes') of road pricing, varying from a complex three cordon plus screenlines structure, to a single Central London cordon. Somewhat surprisingly, the latter was found to be regressive in its application. The structure with the highest benefits, as well as being relatively progressive, was the complex structure of three cordons plus screenlines, with an optimum charge level of 50 pence per cordon crossing, each way but with the outer two cordons being peak only

Study of EVA operations associated with satellite services

Extravehicular mobility unit (EMU) factors associated with satellite servicing activities are identified and the EMU improvements necessary to enhance satellite servicing operations are outlined. Areas of EMU capabilities, equipment and structural interfaces, time lines, EMU modifications for satellite servicing, environmental hazards, and crew training are vital to manned Eva/satellite services and as such are detailed. Evaluation of EMU capabilities indicates that the EMU can be used in performing near term, basic satellite servicing tasks; however, satellite servicing is greatly enhanced by incorporating key modifications into the EMU. The servicing missions involved in contamination sensitive payload repair are illustrated. EVA procedures and equipment can be standardized, reducing both crew training time and in orbit operations time. By standardizing and coordinating procedures, mission cumulative time lines fall well within the EMU capability

Digitally manipulating memory : effects of doctored videos and imagination in distorting beliefs and memories

In prior research on false autobiographical beliefs and memories, subjects have been asked to imagine fictional events and they have been exposed to false evidence that indicates the fictional events occurred. But what are the relative contributions of imagination and false evidence toward false belief and memory construction? Subjects observed and copied various simple actions, then viewed doctored videos that suggested they had performed extra actions, and they imagined performing some of those and some other actions. Subjects returned two weeks later for a memory test. False evidence or imagination alone was often sufficient to cause belief and memory distortions; the two techniques in combination appeared to have additive or even superadditive effects. The results bear on the mechanisms underlying false beliefs and memories, and we propose legal and clinical applications of these findings

"Behaviour of Lucilia sericata with special reference to genetics"

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