1,164 research outputs found

    Status of the Combined Cycle Engine Rig

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    Status for the past year is provided of the turbine-based Combined-Cycle Engine (CCE) Rig for the hypersonic project. As part of the first stage propulsion of a two-stage-to-orbit vehicle concept, this engine rig is designed with a common inlet that supplies flow to a turbine engine and a dual-mode ramjet / scramjet engine in an over/under configuration. At Mach 4 the inlet has variable geometry to switch the airflow from the turbine to the ramjet / scramjet engine. This process is known as inlet mode-transition. In addition to investigating inlet aspects of mode transition, the rig will allow testing of turbine and scramjet systems later in the test series. Fully closing the splitter cowl "cocoons" the turbine engine and increases airflow to the scramjet duct. The CCE Rig will be a testbed to investigate integrated propulsion system and controls technology objectives. Four phases of testing are planned to 1) characterize the dual inlet database, 2) collect inlet dynamics using system identification techniques, 3) implement an inlet control to demonstrate mode-transition scenarios and 4) demonstrate integrated inlet/turbine engine operation through mode-transition. Status of the test planning and preparation activities is summarized with background on the inlet design and small-scale testing, analytical CFD predictions and some details of the large-scale hardware. The final stages of fabrication are underway

    Overview of CCE-LIMX Testing

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    Portfolio Vol. II N 4

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    Browne, Phil. Alumni . Picture. 2. Martindale, Virginia. A Statue By Jude . Prose. 3. Maxwell, Robert. Reflections . Poem. 6. Lewis, Lucy. Quiet Zone . Prose. 7. Varney, Chester. Tinder Box . Prose. 9. Beckham, Adela. Spring Harvest . Poem. 10. Beckham, Adela. Morning . Poem. 10. Black, James. The Drama at Denison . Prose. 11. Mackie, Reino. Landscape . Picture. 6. Flory, Doris. April Showers . Poem. 14. Flory, Doris. Aspiration . Poem. 14. Wager, Dick. Solitude . Poem. 14. Wager, Dick. Regret . Poem. 14. Bastida, Sorella y. Children on the Beach . Picture. 14. Saunders, Paul. Review of New Books . Prose. 15. Smith, Bob. Review of New Recordings . Prose. 15. Mitchell, Dave. A Farmyard . Picture. 16. Bonnet, Elsie. Hidden Village . Picture. 16. Taylor, Dave. Concerning Art . Prose. 17. Browne, Phil. Master Craftsman . Picture. 18. Deeds, Ed. Brothers, Sing On . Prose. 19. Boyd, Kate Olive. Spring at Denison . Poem. 20. Barss, William. Landscape . Picture. 20. Deane, Dorothy. The Taming of the Shrew . Prose. 21

    TBCC Inlet Experiments and Analysis

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    A research plan is being implemented at NASA to investigate inlet mode transition for turbine-based combined-cycle (TBCC) propulsion for the hypersonic community. Unresolved issues have remained on how to design an inlet system to supply both a turbine engine and a ram/scramjet flowpath that operate with both high performance and stability. The current plan is aimed at characterizing the design, performance and operability of TBCC inlets through a series of experiments and analyses. A TBCC inlet has been designed that is capable of high performance (near MIL-E-5008B recovery) with smooth transitioning characteristics. Traditional design techniques were used in an innovative approach to balance the aerodynamic and mechanical constraints to create a new TBCC inlet concept. The inlet was designed for top-end Mach 7 scramjet speeds with an over/under turbine that becomes cocooned beyond its Mach 4 peak design point. Conceptually, this propulsion system was picked to meet the needs of the first stage of a two-stage to orbit vehicle. A series of increasing fidelity CFD-based tools are being used throughout this effort. A small-scale inlet experiment is on-going in the GRC 1'x1' Supersonic Wind Tunnel (SWT). Initial results from both the CFD analyses and test are discussed showing that high performance and smooth mode transitions are possible. The effort validates the design and is contributing to a large-scale inlet/propulsion test being planned for the GRC 10' x10' SWT. This large-scale effort provide the basis for a Combined Cycle Engine Testbed, (CCET), that will be able to address integrated propulsion system and controls objectives

    Superconductivity in AuNiGe Ohmic contacts to a GaAs-based high mobility two-dimensional electron gas

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    To cool a high mobility two-dimensional electron gas (2DEG) at a GaAs-AlGaAs heterojunction to milliKelvin temperatures, we have fabricated low resistance Ohmic contacts based on alloys of Au, Ni, and Ge. The Ohmic contacts have a typical contact resistance of R C ≈ 0.8 ω at 4.2 K, which drops to 0.2 ω below 0.9 K. Scanning electron microscope images establish that the contacts have the same inhomogeneous microstructure that has been observed in previous studies. Measurements of the contact resistance R C, the four-terminal resistance along the top of a single contact, and the vertical resistance RV all show that there is a superconductor in the Ohmic contact, which can be turned completely normal with a magnetic field of 0.15 T. We briefly discuss how this superconductivity may be affecting the electrical transport measurements of 2DEGs, especially how it may hinder the cooling of electrons in a 2DEG below 0.1 K

    Effectiveness of primary care psychological therapy services for treating depression and anxiety in autistic adults in England: a retrospective, matched, observational cohort study of national health-care records.

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    BackgroundAutistic adults report a higher prevalence of anxiety and depression than adults without identified autism but have poorer access to appropriate mental health care. Evidence-based psychological therapies are recommended in treatment guidelines for autistic adults, but no study has investigated their effectiveness in large samples representative of the autistic population accessing routine care. This study aimed to examine therapy outcomes for autistic adults in a primary care service.MethodsIn this retrospective, matched, observational cohort study of national health-care records, we used the MODIFY dataset that used linked electronic health-care records, including national data, for individuals who accessed psychological therapy in primary care in Improving Access to Psychological Therapies (IAPT) services in 211 clinical commissioning group areas in England, UK. All adults aged 18 years or older who had completed a course of IAPT in 2012-19 were eligible, and were propensity score matched (1:1) with a comparison group without identified autism. Exact matching was used, when possible, for a range of sociodemographic factors. Primary outcomes were routine metrics that have been nationally defined and used to evaluate IAPT treatments: reliable improvement, reliable recovery, and reliable deterioration. Secondary outcomes were calculated pre-post treatment changes in scores for Patient Health Questionnaire-9, Generalised Anxiety Disorder Assessment-7, and Work and Social Adjustment Scale measures. Subgroup analyses investigated differential effects across a range of sociodemographic factors.FindingsOf 2 515 402 adults who completed at least two sessions of IAPT in 2012-19, 8761 had an autism diagnosis (5054 [57·7%] male and 3707 [42·3%] female) and 1 918 504 did not (631 606 [32·9%] male and 1 286 898 [67·0%] female). After propensity score matching, 8593 autistic individuals were matched with an individual in the comparison group. During IAPT treatment, symptoms of depression and generalised anxiety disorder decreased for most autistic adults, but symptoms were less likely to improve in the autism group than in the comparison group (4820 [56·1%] of 8593 autistic adults had reliable improvement vs 5304 [61·7%] of 8593 adults in the matched group; adjusted odds ratio [ORadj] 0·75, 95% CI 0·70-0·80; padj 1·34, 1·18-1·48; pInterpretationEvidence-based psychological therapy for depression or anxiety might be effective for autistic adults but less so than for adults without identified autism. Treatment moderators appear different for autistic individuals, so more research is needed to allow for better targeted and personalised care.FundingAlzheimer's Society
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