The importance of thermal-vacuum testing in achieving high reliability of spacecraft mechanisms

The work performed on thermal vacuum testing of complex mechanisms is described. The objective of these tests is to assess the mechanism reliability by monitoring performance in an environment that closely resembles the environment that will occur during flight. To be both valid and cost effective, these tests are performed in a detailed, formally controlled manner. A review of the major test observations is given, during which time some failure modes are detected. Full confidence now exists in many mechanism and component designs, and much valuable data obtained

Computer-aided analysis for the Mechanics of Granular Materials (MGM) experiment

The Mechanics of Granular Materials (MGM) program is planned to provide experimental determinations of the mechanics of granular materials under very low gravity conditions. The initial experiments will use small glass beads as the granular material, and a precise tracking of individual beads during the test is desired. Real-time video images of the experimental specimen were taken with a television camera, and subsequently digitized by a frame grabber installed in a microcomputer. Easily identified red tracer beads were randomly scattered throughout the test specimen. A set of Pascal programs was written for processing and analyzing the digitized images. Filtering the image with Laplacian, dilation, and blurring filters when using a threshold function produced a binary (black on white) image which clearly identified the red beads. The centroids and areas for each bead were then determined. Analyzing a series of the images determined individual red bead displacements throughout the experiment. The system can provide displacement accuracies on the order of 0.5 to 1 pixel is the image is taken directly from the video camera. Digitizing an image from a video cassette recorder introduces an additional repeatability error of 0.5 to 1 pixel. Other programs were written to provide hardcopy prints of the digitized images on a dot-matrix printer

Computer-aided analysis for the Mechanics of Granular Materials (MGM) experiment, part 2

Computer vision based analysis for the MGM experiment is continued and expanded into new areas. Volumetric strains of granular material triaxial test specimens have been measured from digitized images. A computer-assisted procedure is used to identify the edges of the specimen, and the edges are used in a 3-D model to estimate specimen volume. The results of this technique compare favorably to conventional measurements. A simplified model of the magnification caused by diffraction of light within the water of the test apparatus was also developed. This model yields good results when the distance between the camera and the test specimen is large compared to the specimen height. An algorithm for a more accurate 3-D magnification correction is also presented. The use of composite and RGB (red-green-blue) color cameras is discussed and potentially significant benefits from using an RGB camera are presented

New atmospheric sensor analysis study

The functional capabilities of the ESAD Research Computing Facility are discussed. The system is used in processing atmospheric measurements which are used in the evaluation of sensor performance, conducting design-concept simulation studies, and also in modeling the physical and dynamical nature of atmospheric processes. The results may then be evaluated to furnish inputs into the final design specifications for new space sensors intended for future Spacelab, Space Station, and free-flying missions. In addition, data gathered from these missions may subsequently be analyzed to provide better understanding of requirements for numerical modeling of atmospheric phenomena

Scaling Relations in the Vortex State of Nodal Superconductors

In contrast to multigap superconductors (e.g. MgB$_{2}$), the low-temperature properties of nodal superconductors are dominated by nodal excitations. Here we extend for a variety of nodal superocnductors the earlier work by Simon and Lee and K\"ubert and Hirschfeld. The scaling relations seen in the thermodynamics and the thermal conductivity will provide an unequivocal test of nodal superconductivity.Comment: 9 pages, 3 figure

Unravelling mucosal immunity to poliovirus

Comment - No abstrac

A qualitative exploration of the experiences of the hospital discharge process, via the transforming care agenda

Background: Transforming Care was first introduced in 2012 to reduce the number of people with learning disabilities residing in hospital. Research has shown the process of supporting an individual to move out of hospital can be challenging and lengthy for all stakeholders involved. Aim: The current review aimed to systematically review qualitative literature to explore the experiences of being part of the discharge process from hospital to a community-based setting, via Transforming Care. Design: A systematic search was completed on five databases and relevant papers were used. Findings: Thirteen papers met the inclusion criteria. The papers were synthesised using thematic analysis, which produced four over-arching themes: Navigating within the system; Working within restrictions; Preparing to move; and Life after discharge. Clinical Implications: It was important for everyone involved in the discharge to communicate effectively to ensure the process was not delayed. It would be beneficial to have further training to understand the Transforming Care principles. Finally, providing further support in the hospital setting to explain the discharge process to the individual may help reduce anxiety levels

GIOTTO's antenna de-spin mechanism: Ots lubrication and thermal vacuum performance

Except in the near Earth phase of GIOTTO's mission to Comet Halley, the HGA (high gain antenna) on board GIOTTO was the only designed means of up/down communications. The spacecraft spin stabilization required that the HGA be despun at the same rotational rate of nominally 15 rpm in order to keep the HGA pointing accurately to a Earth. A dual servomotor despin mechanism was designed and built by SEP of France for this purpose. The expected thermal environment suggested that dry lubrication was preferable to wet for the ball bearings but there existed no relevant data on the torque noise spectrum of candidate solid lubricants. Therefore ad hoc torque noise tests were run with two solid lubricants: ion plated lead film plus lead bronze cage (retainer) and a PTFE composite cage only. The lead lubrication showed the better spectrum up to the mission lifetime point so it was selected for continued test over some 20 times the Halley mission life, with periodic torque spectrum monitoring. The spectrum remained well within the pointing error budget over the 100 million revolutions covered

Innovative Approach for Heating of Buildings Using Water from a Flooded Coal Mine Through an Open Loop Based Single Shaft GSHP System

Geothermal energy, deep and shallow, has always been identified as an important renewable energy resource. The stable temperature and relatively low enthalpy of mine water contained in the abandoned and flooded coal mines have the potential to form a geothermal resource to be used in conjunction with heat pumps to provide heating and cooling for buildings. The usage of heat pump for space heating and cooling can be classified as a low carbon technology and if heat pump is powered by solar or wind energy it can be classified as a truly renewable technology. This paper presents a novel application of Ground Source Heat Pump (GSHP) for space heating and cooling using a flooded coal mine through an open loop based single shaft system. In this novel application, a single shaft is used for both extraction and injection of mine water for the heating application. This research work will report on the performance of the system and its long term potential in comparison to standard gas boilers heating systems. The usage of a single shaft system has been found effective in developing an efficient heating system with reduced cost and neutral environmental impact