14,371 research outputs found
A study for development of aerothermodynamic test model materials and fabrication technique
A literature survey, materials reformulation and tailoring, fabrication problems, and materials selection and evaluation for fabricating models to be used with the phase-change technique for obtaining quantitative aerodynamic heat transfer data are presented. The study resulted in the selection of two best materials, stycast 2762 FT, and an alumina ceramic. Characteristics of these materials and detailed fabrication methods are presented
Design and testing of a contra-rotating tidal current turbine
A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. High-frequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials
Extended Hodge Theory for Fibred Cusp Manifolds
For a particular class of pseudo manifolds, we show that the intersection
cohomology groups for any perversity may be naturally represented by extended
weighted harmonic forms for a complete metric on the regular stratum with
respect to some weight determined by the perversity. Extended weighted
harmonic forms are harmonic forms that are almost in the given weighted
space for the metric in question, but not quite. This result is akin to the
representation of absolute and relative cohomology groups for a manifold with
boundary by extended harmonic forms on the associated manifold with cylindrical
ends. As in that setting, in the unweighted case, the boundary values of
the extended harmonic forms define a Lagrangian splitting of the boundary space
in the long exact sequence relating upper and lower middle perversity
intersection cohomology groups.Comment: 26 page
\u3ci\u3eDiscovering Dune: Essays on Frank Herbert’s Epic Saga.\u3c/i\u3e, edited by Dominic J. Nardi and N. Trevor Brierly
G. Connor Salter reviews Discovering Dune: Essays on Frank Herbert’s Epic Saga, edited by Dominic J. Nardi and N. Trevor Brierly, considering its new contributions to studies of Frank Herbert\u27s work. Essays included fit into four categories (Politics and Power, History and Religion, Biology and Ecology, and Philosophy, Choice and Ethics) and range from Herbert\u27s use of ecology in Dune to how game theory may help explain certain characters\u27 apparent ability to see the future. Discovering Dune also includes an appendix which contains the only up-to-date bibliography of Herbert\u27s work (primary and secondary sources)
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