A design assessment of multiwall, metallic stand-off, and RSI reusable thermal protection systems including space shuttle application

The design and assessment of reusable surface insulation (RSI), metallic stand off and multiwall thermal protection systems (TPS) is discussed. Multiwall TPS is described in some detail, and analyses useful for design of multiwall are included. Results indicate that multiwall has the potential to satisfy the TPS design goals better than the other systems. The total mass of the stand-off TPS and of the metallic systems require less primary structure mass than the RSI system, since the nonbuckling skin criteria required for RSI may be removed. Continued development of multiwall TPS is required to verify its potential and to provide the necessary data base for design

Device and method for frictionally testing materials for ignitability

Test apparatus for determining ignition characteristics of various metal in oxidizer environments simulating operating conditions for materials is invented. The test apparatus has a chamber through which the oxidizing agent flows, and means for mounting a stationary test sample therein, a powered, rotating shaft in the chamber rigidly mounts a second test sample. The shaft is axially movable to bring the samples into frictional engagement and heated to the ignition point. Instrumentation connected to the apparatus provides for observation of temperatures, pressures, loads on and speeds of the rotating shaft, and torques whereby components of stressed oxygen systems can be selected which will avoid accidental fires under working conditions

BRS Cohomology of the Supertranslations in D=4

Supersymmetry transformations are a kind of square root of spacetime translations. The corresponding Lie superalgebra always contains the supertranslation operator $\delta = c^{\alpha} \sigma^{\mu}_{\alpha \dot \beta} {\overline c}^{\dot \beta} (\epsilon^{\mu})^{\dag}$. We find that the cohomology of this operator depends on a spin-orbit coupling in an SU(2) group and has a quite complicated structure. This spin-orbit type coupling will turn out to be basic in the cohomology of supersymmetric field theories in general.Comment: 14 pages, CTP-TAMU-13/9

A pragmatic cluster randomized controlled trial of an educational intervention for GPs in the assessment and management of depression

Background. General practitioners (GPs) can be provided with effective training in the skills to manage depression. However, it remains uncertain whether such training achieves health gain for their patients. Method. The study aimed to measure the health gain from training GPs in skills for the assessment and management of depression. The study design was a cluster randomized controlled trial. GP participants were assessed for recognition of psychological disorders, attitudes to depression, prescribing patterns and experience of psychiatry and communication skills training. They were then randomized to receive training at baseline or the end of the study. Patients selected by GPs were assessed at baseline, 3 and 12 months. The primary outcome was depression status, measured by HAM-D. Secondary outcomes were psychiatric symptoms (GHQ-12) quality of life (SF-36), satisfaction with consultations, and health service use and costs. Results. Thirty-eight GPs were recruited and 36 (95%) completed the study. They selected 318 patients, of whom 189 (59%) were successfully recruited. At 3 months there were no significant differences between intervention and control patients on HAM-D, GHQ-12 or SF-36. At 12 months there was a positive training effect in two domains of the SF-36, but no differences in HAM-D, GHQ-12 or health care costs. Patients reported trained GPs as somewhat better at listening and understanding but not in the other aspects of satisfaction. Conclusions. Although training programmes may improve GPs' skills in managing depression, this does not appear to translate into health gain for depressed patients or the health service

Technical innovation changes standard radiographic protocols in veterinary medicine: is it necessary to obtain two dorsoproximal-palmarodistal oblique views of the equine foot when using computerised radiography systems?

Since the 1950s, veterinary practitioners have included two separate dorsoproximal–palmarodistal oblique (DPr–PaDiO) radiographs as part of a standard series of the equine foot. One image is obtained to visualise the distal phalanx and the other to visualise the navicular bone. However, rapid development of computed radiography and digital radiography and their post-processing capabilities could mean that this practice is no longer required. The aim of this study was to determine differences in perceived image quality between DPr–PaDiO radiographs that were acquired with a computerised radiography system with exposures, centring and collimation recommended for the navicular bone versus images acquired for the distal phalanx but were subsequently manipulated post-acquisition to highlight the navicular bone. Thirty images were presented to four clinicians for quality assessment and graded using a 1–3 scale (1=textbook quality, 2=diagnostic quality, 3=non-diagnostic image). No significant difference in diagnostic quality was found between the original navicular bone images and the manipulated distal phalanx images. This finding suggests that a single DPr–PaDiO image of the distal phalanx is sufficient for an equine foot radiographic series, with appropriate post-processing and manipulation. This change in protocol will result in reduced radiographic study time and decreased patient/personnel radiation exposure

Materials and structures for hypersonic vehicles

Hypersonic vehicles are envisioned to require, in addition to carbon-carbon and ceramic-matrix composities for leading edges heated to above 2000 F, such 600 to 1800 F operating temperature materials as advanced Ti alloys, nickel aluminides, and metal-matrix composited; These possess the necessary low density and high strength and stiffness. The primary design drivers are maximum vehicle heating rate, total heat load, flight envelope, propulsion system type, mission life requirements and liquid hydrogen containment systems. Attention is presently given to aspects of these materials and structures requiring more intensive development

Critical velocity ionisation in substellar atmospheres

The observation of radio, X-ray and Hα emission from substellar objects indicates the presence of plasma regions and associated high-energy processes in their surrounding envelopes. This paper numerically simulates and characterises Critical Velocity Ionisation, a potential ionisation process, that can efficiently generate plasma as a result of neutral gas flows interacting with seed magnetized plasmas. By coupling a Gas-MHD interactions code (to simulate the ionisation mechanism) with a substellar global circulation model (to provide the required gas flows) we quantify the spatial extent of the resulting plasma regions, their degree of ionisation and their lifetime for a typical substellar atmosphere. It is found that the typical average ionisation fraction reached at equilibrium (where the ionisation and recombination rates are equal and opposite) ranges from 10-5 to 10-8, at pressures between 10-1 and 10-3 bar, with a trend of increasing ionisation fraction with decreasing atmospheric pressure. The ionisation fractions reached as a result of Critical Velocity Ionisation are sufficient to allow magnetic fields to couple to gas flows in the atmosphere

Autonomous Integrated Receive System (AIRS) requirements definition. Volume 2: Design and development

Functional requirements and specifications are defined for an autonomous integrated receive system (AIRS) to be used as an improvement in the current tracking and data relay satellite system (TDRSS), and as a receiving system in the future tracking and data acquisition system (TDAS). The AIRS provides improved acquisition, tracking, bit error rate (BER), RFI mitigation techniques, and data operations performance compared to the current TDRSS ground segment receive system. A computer model of the AIRS is used to provide simulation results predicting the performance of AIRS. Cost and technology assessments are included

Structures and materials technology issues for reusable launch vehicles

Projected space missions for both civil and defense needs require significant improvements in structures and materials technology for reusable launch vehicles: reductions in structural weight compared to the Space Shuttle Orbiter of up to 25% or more, a possible factor of 5 or more increase in mission life, increases in maximum use temperature of the external surface, reusable containment of cryogenic hydrogen and oxygen, significant reductions in operational costs, and possibly less lead time between technology readiness and initial operational capability. In addition, there is increasing interest in hypersonic airbreathing propulsion for launch and transmospheric vehicles, and such systems require regeneratively cooled structure. The technology issues are addressed, giving brief assessments of the state-of-the-art and proposed activities to meet the technology requirements in a timely manner

Entry Systems Panel deliberations

The Entry Systems Panel was chaired by Don Rummler, LaRC and Dan Rasky, ARC. As requested, each panel participant prior to the workshop prepared and delivered presentations to: (1) identify technology needs; (2) assess current programs; (3) identify technology gaps; and (4) identify highest payoff areas R&D. Participants presented background on the entry systems R&D efforts and operations experiences for the Space Shuttle Orbiter. These participants represented NASA Centers involved in research (Ames Research Center), development (Johnson Space Center) and operations (Kennedy Space Center) and the Shuttle Orbiter prime contractor. The presentations lead to the discovery of several lessons learned