9,575 research outputs found

    Advances in understanding autogyro flight dynamics

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    A comprehensive flight dynamics study of the autogyro is presented in this paper. A state of the art generic simulation of the vehicle type was developed and validated against flight data. This validation is presented in the paper and it is shown that the model can be applied to the autogyro with some confidence within well defined limitations bounds. It is also shown that the general stability characteristics of the autogyro can be considered as a mix of helicopter and fixed wing aircraft modes of flight. Most significantly the autogyro has a lightly damped, high frequency phugoid mode. Further, it is demonstrated that the only significant configurational effect is related to the relative vertical position of the centre of gravity with respect to the propeller thrustline, a centre of gravity which lies above the thrustline being more desirable. Results from preliminary handling qualities trials applying the techniques of ADS33 to an autogyro are also presented. Results from flight trials to investigate the teetering motion of the rotor are described, and the influence of the research on air accident investigation is also discussed

    Influence of coherent mesoscale structures on satellite-based Doppler lidar wind measurements

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    Efforts to develop display routines for overlaying gridded and nongridded data sets are discussed. The primary objective is to have the capability to review global patterns of winds and lidar samples; to zoom in on particular wind features or global areas; and to display contours of wind components and derived fields (e.g., divergence, vorticity, deformation, etc.). Current considerations in support of a polar orbiting shuttle lidar mission are discussed. Ground truth for a shuttle lidar experiment may be limited to fortuitous alignment of lidar wind profiles and scheduled rawinsonde profiles. Any improvement on this would require special rawinsonde launches and/or optimization of the shuttle orbit with global wind measurement networks

    Application LANDSAT imagery to geologic mapping in the ice-free valleys of Antarctica

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    The author has identified the following significant results. Studies in the Ice-Free Valleys are resulted in the compilation of a sizeable library of maps and publications. Rock reflectance measurements were taken during the Antarctic summer of 1973. Spectral reflectance of rocks (mostly mafic lava flows) in the McMurdo and Ice-Free Valleys areas were measured using a filter wheel photometer equipped to measure reflectances in the four Landsat bands. A series of samples were collected at regular intervals across a large differentiated, mafic sill near Lake Vida. Chemical analyses of the sample suggest that the tonal variations in this sill are controlled by changes in the iron content of the rock. False color images were prepared for a number of areas by the diazo method and with an optical multispectral biviewer. These images were useful in defining boundaries of sea ice, snow cover, and in the study of ablating glaciers, but were not very useful for rock discrimination

    Technical writing practically unified through industry

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    General background details in the development of a university level technical writing program, based upon the writing tasks of the student's occupations, are summarized. Objectives and methods for unifying the courses of study with the needs of industry are discussed. Four academic course divisions, Industries Technologies, in which preparation and training are offered are: Animal, Horticulture, Agriculture, and Agricultural Business. Occupational competence is cited as the main goal for these programs in which technical writing is to be practically unified through industry. Course descriptions are also provided

    Enhancing SPH using moving least-squares and radial basis functions

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    In this paper we consider two sources of enhancement for the meshfree Lagrangian particle method smoothed particle hydrodynamics (SPH) by improving the accuracy of the particle approximation. Namely, we will consider shape functions constructed using: moving least-squares approximation (MLS); radial basis functions (RBF). Using MLS approximation is appealing because polynomial consistency of the particle approximation can be enforced. RBFs further appeal as they allow one to dispense with the smoothing-length -- the parameter in the SPH method which governs the number of particles within the support of the shape function. Currently, only ad hoc methods for choosing the smoothing-length exist. We ensure that any enhancement retains the conservative and meshfree nature of SPH. In doing so, we derive a new set of variationally-consistent hydrodynamic equations. Finally, we demonstrate the performance of the new equations on the Sod shock tube problem.Comment: 10 pages, 3 figures, In Proc. A4A5, Chester UK, Jul. 18-22 200

    Attitudes of Students to Independent Learning

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    Some illustrations of the advantages of improved resolution in geologic studies

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    There are no author-identified significant results in this report

    Models for pattern formation in somitogenesis: a marriage of cellular and molecular biology

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    Somitogenesis, the process by which a bilaterally symmetric pattern of cell aggregations is laid down in a cranio-caudal sequence in early vertebrate development, provides an excellent model study for the coupling of interactions at the molecular and cellular level. Here, we review some of the key experimental results and theoretical models related to this process. We extend a recent chemical pre-pattern model based on the cell cycle Journal of Theoretical Biology 207 (2000) 305-316, by including cell movement and show that the resultant model exhibits the correct spatio-temporal dynamics of cell aggregation. We also postulate a model to account for the recently observed spatio-temporal dynamics at the molecular level
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