7,582 research outputs found

    Exhaust-nozzle characterisitcs for a twin-jet variable-wing-sweep fighter airplane model at Mach numbers to 2.2

    Get PDF
    A wind-tunnel investigation has been conducted to determine the exhaust-nozzle aerodynamic and propulsive characteristics for a twin-jet variable-wing-sweep fighter airplane model. The powered model was tested in the Langley 16-foot transonic tunnel and in the Langley 4-foot supersonic pressure tunnel at Mach numbers to 2.2 and at angles of attack from about minus 2 to 6 deg. Compressed air was used to simulate the nozzle exhaust flow at values of jet total-pressure ratio from approximately 1 (jet off) to about 21. Effects of configuration variables such as speed-brake deflection, store installation, and boundary-layer thickness on the the nozzle characteristics were also investigated

    Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model

    Get PDF
    The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude

    The development of direct payments in the UK: implications for social justice

    Get PDF
    Direct payments have been heralded by the disability movement as an important means to achieving independent living and hence greater social justice for disabled people through enhanced recognition as well as financial redistribution. Drawing on data from the ESRC funded project Disabled People and Direct Payments: A UK Comparative Perspective, this paper presents an analysis of policy and official statistics on use of direct payments across the UK. It is argued that the potential of direct payments has only partly been realised as a result of very low and uneven uptake within and between different parts of the UK. This is accounted for in part by resistance from some Labour-controlled local authorities, which regard direct payments as a threat to public sector jobs. In addition, access to direct payments has been uneven across impairment groups. However, from a very low base there has been a rapid expansion in the use of direct payments over the past three years. The extent to which direct payments are able to facilitate the ultimate goal of independent living for disabled people requires careful monitoring

    Crystallization of Yamato 980459 at 0.5 GPA: Are Residual Liquids Like QUE 94201?

    Get PDF
    The Martian basaltic meteorites Y980459 and QUE94201 (henceforth referred to as Y98 and QUE respectively) are thought to represent magmatic liquid compositions, rather than being products of protracted crystallization and accumulation like the majority of other martian meteorites. Both meteorite compositions have been experimentally crystallized at 1 bar, and liquidus phases were found to match corresponding mineral core compositions in the meteorites, consistent with the notion that these meteorites represent bona fide melts. They also represent the most primitive and most evolved basaltic martian samples, respectively. Y98 has Mg# (molar Mg/Mg+Fe) approximates 65, and lacks plagioclase; whereas QUE has Mg# approximates 40, and lacks olivine. However they share important geochemical characteristics (e.g. superchondritic CaO/Al2O3, very high epsilon(sub Nd) and low Sr-87/Sr-87) that suggest they sample a similar highly depleted mantle reservoir. As such, they represent likely endmembers of martian magmatic liquid compositions, and it is natural to seek petrogenetic linkages between the two. We make no claim that the actual meteorites themselves share a genetic link (the respective ages rule that out); we are exploring only in general whether primitive martian liquids like Y98 could evolve to liquids resembling QUE. Both experimental and computational efforts have been made to determine if there is indeed such a link. Recent petrological models at 1 bar generated using MELTS suggest that a QUE-like melt can be derived from a parental melt with a Y98 composition. However, experimental studies at 1 bar have been less successful at replicating this progression. Previous experimental crystallization studies of Y98 by our group at 0.5 GPa have produced melt compositions approaching that of QUE, although these results were complicated by the presence of small, variable amounts of H2O in some of the runs owing to the use of talc/pyrex experimental assemblies. Therefore we have repeated the four experiments, augmented with additional runs, all using BaCO3 cell assemblies, which are devoid of water, and these new experiments supersede those reported earlier. Here we report results of experiments simulating equilibrium crystallization; fractional crystallization experiments are currently underway

    Predicting sexual problems in women: The relevance of sexual excitation and sexual inhibition

    Get PDF
    This is the post-print version of the article. The official published version can be obtained from the link below.Data from a non-clinical sample of 540 heterosexual women were used to examine the relationships between scores on the Sexual Excitation/Sexual Inhibition Inventory for Women (SESII-W) and ratings of current sexual problems, lifetime arousal difficulty, lifetime orgasm difficulty, and lifetime problems with low sexual interest. Multiple regression analyses also included several demographic/background variables as predictors: age, full-time employment, completed college, children in household, married, health ratings, importance of sex, and whether the woman was in a sexual relationship. The strongest statistical predictors of both current and lifetime sexual problems were the SESII-W inhibition factors Arousal Contingency and Concerns about Sexual Function. Demographic factors did not feature largely in any of the models predicting sexual problems even when statistically significant relationships were found. If future research supports the predictive utility of the SESII-W in identifying women who are more likely to experience sexual difficulties, these scales may be used as prognostic factors in treatment studies.This study was funded, in part, by a grant from the Lilly Centre for Women's Health

    Computations for the 16-foot transonic tunnel, NASA, Langley Research Center, revision 1

    Get PDF
    The equations used by the 16 foot transonic tunnel in the data reduction programs are presented in eight modules. Each module consists of equations necessary to achieve a specific purpose. These modules are categorized in the following groups: tunnel parameters; jet exhaust measurements; skin friction drag; balance loads and model attitudes calculations; internal drag (or exit-flow distributions); pressure coefficients and integrated forces; thrust removal options; and turboprop options. This document is a companion document to NASA TM-83186, A User's Guide to the Langley 16 Foot Transonic Tunnel, August 1981

    Teacher interventions in small group work in secondary mathematics and science lessons

    Get PDF
    Collaborative problem solving, when students work in pairs or small groups on a curriculum-related task, has become an increasingly common feature of classroom education. This paper reports a study of a topic which has received relatively little attention: how teachers can most usefully intervene when students are working in a group, but have encountered some sort of problem. The data used comes from a large scale interventional study of mathematics and science teaching in secondary schools in south east England, in which interactions between teachers and students were recorded in their usual classrooms. We identify the typical problem situations which lead to teachers’ interventions, and describe the different ways teachers were observed to intervene. We examine the different types of intervention, and consider how effective they are in helping group work proceed in a productive manner. Finally, we offer some conclusions about the practical implications of these findings.This is the final version of the article. It was first available from Taylor & Francis via http://dx.doi.org/10.1080/09500782.2015.112536

    From multiple perspectives to shared understanding

    Get PDF
    The aim of this study was to explore how learners operating in a small group reach shared understanding as they work out joint research questions and build a theoretical framework and to identify the resources and tools they used in the process. The learners’ own interpretations of their group activities and learning were also taken into account. The data, consisting of group discussions and the documents produced by the group, were subjected to a qualitative content analysis. The group members employed a variety of resources and tools to exchange their individual perspectives and achieve shared understanding. Summaries of relevant literature laid a foundation for the group’s theoretical discussions. Reflective comparisons between their book knowledge and their personal experiences of online interaction and collaboration were frequent, suggesting that such juxtapositions may have enhanced their learning by intertwining the content to be mastered and the activities entailed by this particular content
    corecore