25,144 research outputs found

    Development of Thermal Testing Techniques at High Solar Intensities Final Report, 13 Aug. 1965 - 13 May 1967

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    Solar energy simulation techniques for testing spacecraft thermal performanc

    Thermal and structural modeling of superinsulation

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    Model permits direct physical measurement of the thermal response of critical components of space telescopes, thus providing flexibility for systems studies and design changes

    Spacecraft nitrogen generation

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    Two spacecraft nitrogen (N2) generation systems based on the catalytic dissociation of hydrazine (N2H4) were evaluated. In the first system, liquid N2H4 is catalytically dissociated to yield an N2 and hydrogen (H2) gas mixture. Separation of the N2/H2 gas mixture to yield N2 and a supply of H2 is accomplished using a polymer-electrochemical N2/H2 separator. In the second system, the N2/H2 gas mixture is separated in a two-stage palladium/silver (Pd/Ag) N2/H2 separator. The program culminated in the successful design, fabrication, and testing of a N2H4 catalytic dissociator, a polymer-electrochemical N2/H2 separator, and a two-stage Pd/Ag N2/H2 separator. The hardware developed was sized for an N2 delivery rate of 6.81 kg/d (15lb/day). Experimental results demonstrated that both spacecraft N2 generation systems are capable of producing 6.81 kg/d (15lb/day) of 99.9% pure N2 at a pressure greater than or equal to 1035 kN/m(2) (150 psia)

    Gratings photowritten in ion-exchanged glass channel waveguides

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    Gratings are photowritten in ion-exchanged glass channel waveguides. The transmission of these waveguides shows a rejection dip of almost 20dB. The polarisation dependence of these waveguide gratings is measured and discussed

    Grating formation in BGG31 glass by UV exposure

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    A three-dimensional index variation grating in bulk BGG31 glass written using neither hydrogen loading nor germanium doping is demonstrated. This material is useful for fabricating ion-exchanged waveguides, and its photosensitivity to ultraviolet (UV) radiation at 248nm has not been previously explored. Intensity measurements of the Bragg diffracted spots indicated a maximum index variation (Delta n) of similar to 4 x 10(-5)

    HABITATTITUDE™: GETTING A BACKBONE ABOUT THE PET RELEASE PATHWAY

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    Many people would not consider their family complete without a pet. Unfortunately, for some pet owners, circumstances arise that prevent them from being able to properly care for their companions and pet abandonment has become one of the most common pathways of vertebrate species introduction. It is also one of the most challenging pathways to address once the animals become established, eradication and control programs face significant public scrutiny and are often challenged by “animal rights” groups. Prevention measures are thus the key to minimizing the size and impacts of the “pet release pathway.” Habitattitude™ is a proactive campaign designed and implemented by the Pet Industry Joint Advisory Council and partners to prevent the introduction of unwanted pets into natural systems. The campaign has three components: (1) educating consumers to make wise pet choices, (2) providing resources to enable high standards in animal care and maintenance, and (3) encouraging pet owners to choose among several alternatives to the release of their pets if problems do arise. Habitattitude™ messages are being promoted in pet stores, product advertisements, industry trade shows, and industry-relevant magazines

    Local magnetic anisotropy in BaFe2_2As2_2: a polarized inelastic neutron scattering study

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    The anisotropy of the magnetic excitations in BaFe2_2As2_2 was studied by polarized inelastic neutron scattering which allows one to separate the components of the magnetic response. Despite the in-plane orientation of the static ordered moment we find the in-plane polarized magnons to exhibit a larger gap than the out-of-plane polarized ones indicating very strong single-ion anisotropy within the layers. It costs more energy to rotate a spin within the orthorhombic {\it a-b} plane than rotating it perpendicular to the FeAs layers.Comment: 4 pages, 4 figure

    Adjustment with aphasia after stroke: study protocol for a pilot feasibility randomised controlled trial for SUpporting wellbeing through PEeR Befriending (SUPERB)

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    Background: Despite the high prevalence of mood problems after stroke, evidence on effective interventions particularly for those with aphasia is limited. There is a pressing need to systematically evaluate interventions aiming to improve wellbeing for people with stroke and aphasia. This study aims to evaluate the feasibility of a peer-befriending intervention. Methods/design: SUPERB is a single blind, parallel group feasibility trial of peer befriending for people with aphasia post-stroke and low levels of psychological distress. The trial includes a nested qualitative study and pilot economic evaluation and it compares usual care (n = 30) with usual care + peer befriending (n = 30). Feasibility outcomes include proportion screened who meet criteria, proportion who consent, rate of consent, number of missing/incomplete data on outcome measures, attrition rate at follow-up, potential value of conducting main trial using value of information analysis (economic evaluation), description of usual care, and treatment fidelity of peer befriending. Assessments and outcome measures (mood, wellbeing, communication, and social participation) for participants and significant others will be administered at baseline, with outcome measures re-administered at 4 and 10 months post-randomisation. Peer befrienders will complete outcome measures before training and after they have completed two cycles of befriending. The qualitative study will use semi-structured interviews of purposively sampled participants (n = 20) and significant others (n = 10) from both arms of the trial, and all peer befrienders to explore the acceptability of procedures and experiences of care. The pilot economic evaluation will utilise the European Quality of life measure (EQ-5D-5 L) and a stroke-adapted version of the Client Service Receipt Inventory (CSRI). Discussion: This study will provide information on feasibility outcomes and an initial indication of whether peer befriending is a suitable intervention to explore further in a definitive phase III randomised controlled trial. Trial registration: ClinicalTrials.gov identifier NCT02947776, registered 28th October 2016

    Estimates on Green functions of second order differential operators with singular coefficients

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    We investigate the Green functions G(x,x^{\prime}) of some second order differential operators on R^{d+1} with singular coefficients depending only on one coordinate x_{0}. We express the Green functions by means of the Brownian motion. Applying probabilistic methods we prove that when x=(0,{\bf x}) and x^{\prime}=(0,{\bf x}^{\prime}) (here x_{0}=0) lie on the singular hyperplanes then G(0,{\bf x};0,{\bf x}^{\prime}) is more regular than the Green function of operators with regular coefficients.Comment: 16 page
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