223 research outputs found

    [Review of] John Wrench and John Solomos, eds. Racism and Migration in Western Europe

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    This collection of fifteen essays edited by Wrench and Solomos is derived from the proceedings of a 1991 conference on Racism and Migration in Europe in the 1990s,” held in England and organized by the Centre for Research in Ethnic Relations at the University of Warwick and the Public Policy Centre of the Department of Politics and Sociology, Birkbeck College, University of London. The purpose of this international meeting was to bring together scholars working on these topics and to examine the European situation today. The proceedings analyze the social and political debates surrounding immigration in European countries, where the need to accommodate greater racial, ethnic, and religious diversity has been accompanied by growing intolerance and hostility towards immigrants. Since resolving social questions raised by immigration has become a priority for most governments and since the European Union plans to harmonize policies, legislation, and rights, this volume fulfills the need for greater international exchange and cooperation between researchers and policy makers. The present collection points to similarities in immigration, and sources and forms of racism in Europe as a whole, but also to differences due to specific socio-historical situations

    [Review of] Suzanne M. Sinke and Rudolph J. Vecoli, eds. A Century of European Migrations, 1830-1930

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    This collection of sixteen essays stems from the proceedings of a 1986 symposium commemorating the twentieth anniversary of the Immigration History Research Center at the University of Minnesota. Based on work by American and European scholars, this volume owes its strength to transnational and comparative perspectives and to theoretical approaches strongly inspired by Frank Thistlethwaite’s influential 1960 essay “Migration from Europe Overseas in the Nineteenth and Twentieth Century.” Reprinted in the present volume, Thistlethwaite’s paper advocated studying European migration -- and return migration -- as a means of social mobility in the context of industrialization and capitalism, within Europe and overseas. And it suggested that researchers scrutinize the particular economic, political, and cultural environments of the sending regions which created the propensity -- or lack thereof -- to migrate

    Commercial Crew Program Crew Safety Strategy

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    The purpose of this presentation is to explain to our international partners (ESA and JAXA) how NASA is implementing crew safety onto our commercial partners under the Commercial Crew Program. It will show them the overall strategy of 1) how crew safety boundaries have been established; 2) how Human Rating requirements have been flown down into programmatic requirements and over into contracts and partner requirements; 3) how CCP SMA has assessed CCP Certification and CoFR strategies against Shuttle baselines; 4) Discuss how Risk Based Assessment (RBA) and Shared Assurance is used to accomplish these strategies

    Observations on CFD Verification and Validation from the AIAA Drag Prediction Workshops

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    The authors provide observations from the AIAA Drag Prediction Workshops that have spanned over a decade and from a recent validation experiment at NASA Langley. These workshops provide an assessment of the predictive capability of forces and moments, focused on drag, for transonic transports. It is very difficult to manage the consistency of results in a workshop setting to perform verification and validation at the scientific level, but it may be sufficient to assess it at the level of practice. Observations thus far: 1) due to simplifications in the workshop test cases, wind tunnel data are not necessarily the correct results that CFD should match, 2) an average of core CFD data are not necessarily a better estimate of the true solution as it is merely an average of other solutions and has many coupled sources of variation, 3) outlier solutions should be investigated and understood, and 4) the DPW series does not have the systematic build up and definition on both the computational and experimental side that is required for detailed verification and validation. Several observations regarding the importance of the grid, effects of physical modeling, benefits of open forums, and guidance for validation experiments are discussed. The increased variation in results when predicting regions of flow separation and increased variation due to interaction effects, e.g., fuselage and horizontal tail, point out the need for validation data sets for these important flow phenomena. Experiences with a recent validation experiment at NASA Langley are included to provide guidance on validation experiments

    Development of a Common Research Model for Applied CFD Validation Studies

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    The development of a wing/body/nacelle/pylon/horizontal-tail configuration for a common research model is presented, with focus on the aerodynamic design of the wing. Here, a contemporary transonic supercritical wing design is developed with aerodynamic characteristics that are well behaved and of high performance for configurations with and without the nacelle/pylon group. The horizontal tail is robustly designed for dive Mach number conditions and is suitably sized for typical stability and control requirements. The fuselage is representative of a wide/body commercial transport aircraft; it includes a wing-body fairing, as well as a scrubbing seal for the horizontal tail. The nacelle is a single-cowl, high by-pass-ratio, flow-through design with an exit area sized to achieve a natural unforced mass-flow-ratio typical of commercial aircraft engines at cruise. The simplicity of this un-bifurcated nacelle geometry will facilitate grid generation efforts of subsequent CFD validation exercises. Detailed aerodynamic performance data has been generated for this model; however, this information is presented in such a manner as to not bias CFD predictions planned for the fourth AIAA CFD Drag Prediction Workshop, which incorporates this common research model into its blind test cases. The CFD results presented include wing pressure distributions with and without the nacelle/pylon, ML/D trend lines, and drag-divergence curves; the design point for the wing/body configuration is within 1% of its max-ML/D. Plans to test the common research model in the National Transonic Facility and the Ames 11-ft wind tunnels are also discussed

    Land and society in golden age Castile

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    Drag Prediction for the NASA CRM Wing-Body-Tail Using CFL3D and OVERFLOW on an Overset Mesh

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    In response to the fourth AIAA CFD Drag Prediction Workshop (DPW-IV), the NASA Common Research Model (CRM) wing-body and wing-body-tail configurations are analyzed using the Reynolds-averaged Navier-Stokes (RANS) flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built for DPW-IV. Grid Family 1 (GF1) consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 (GF2) is an extension of the first and includes a superfine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on GF1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on GF1 and to obtain results for GF2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes

    Contributions to the Sixth Drag Prediction Workshop Using Structured, Overset Grid Methods

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143028/1/1.C034486.pd

    Strategies for Solving High-Fidelity Aerodynamic Shape Optimization Problems

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140440/1/6.2014-2594.pd

    Slotted Aircraft Wing

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    An aircraft wing includes a leading airfoil element and a trailing airfoil element. At least one slot is defined by the wing during at least one transonic condition of the wing. The slot may either extend spanwise along only a portion of the wingspan, or it may extend spanwise along the entire wingspan. In either case, the slot allows a portion of the air flowing along the lower surface of the leading airfoil element to split and flow over the upper surface of the trailing airfoil element so as to achieve a performance improvement in the transonic condition
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