16,096 research outputs found

    Planar motion of a human being under the action of a body-fixed thrust

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    Weightless astronaut maneuvering device for directional and attitude control feasibility study using two body system equations of motio

    Experimental investigation of planar motions of a human being under the action of a body- fixed thrust

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    Planar motion of human being subjected to action of body-fixed forc

    Elevated temperature deformation of thoria dispersed nickel-chromium

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    The deformation behavior of thoria nickel-chromium (TD-NiCr) was examined over the temperature range 593 C (1100 F) to 1260 C (2300 F) in tension and compression and at 1093 C (2000 F) in creep. Major emphasis was placed on: (1) the effects of the material and test related variables (grain size, temperature, stress and strain rate) on the deformation process; and (2) the evaluation of single crystal TD-NiCr material produced by a directional recrystallization process. Elevated temperature yield strength levels and creep activation enthalpies were found to increase with increasing grain size reaching maximum values for the single crystal TD-NiCr. Stress exponent of the steady state creep rate was also significantly higher for the single crystal TD-NiCr as compared to that determined for the polycrystalline materials. The elevated temperature deformation of TD-NiCr was analyzed in terms of two concurrent, parallel processes: diffusion controlled grain boundary sliding, and dislocation motion

    An in Situ Technique for Elemental Analysis of Lunar Surfaces

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    An in situ analytical technique that can remotely determine the elemental constituents of solids has been demonstrated. Laser-Induced Breakdown Spectroscopy (LIBS) is a form of atomic emission spectroscopy in which a powerful laser pulse is focused on a solid to generate a laser spark, or microplasma. Material in the plasma is vaporized, and the resulting atoms are excited to emit light. The light is spectrally resolved to identify the emitting species. LIBS is a simple technique that can be automated for inclusion aboard a remotely operated vehicle. Since only optical access to a sample is required, areas inaccessible to a rover can be analyzed remotely. A single laser spark both vaporizes and excites the sample so that near real-time analysis (a few minutes) is possible. This technique provides simultaneous multielement detection and has good sensitivity for many elements. LIBS also eliminates the need for sample retrieval and preparation preventing possible sample contamination. These qualities make the LIBS technique uniquely suited for use in the lunar environment

    Testing Gaugino Mass Unification Directly at the LHC

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    We report on the first step of a systematic study of how gaugino mass unification can be probed at the LHC in a quasi-model independent manner. Here we focus our attention on the theoretically well-motivated mirage pattern of gaugino masses, a one-parameter family of models of which universal (high scale) gaugino masses are a limiting case. Using a statistical method to optimize our signature selection we arrive at three ensembles of observables targeted at the physics of the gaugino sector, allowing for a determination of this non-universality parameter without reconstructing individual mass eigenvalues or the soft supersymmetry-breaking gaugino masses themselves. In this controlled environment we find that approximately 80% of the supersymmetric parameter space would give rise to a model for which our method will detect non-universality in the gaugino mass sector at the 10% level with approximately 10 inverse femptobarns of integrated luminosity.Comment: To appear in proceedings of "Beyond the Standard Model at the LHC (BSM-LHC)", June 2-4, 200

    Operational applications of NOAA-VHRR imagery in Alaska

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    Near-real time operational applications of NOAA satellite enhanced thermal infrared imagery to snow monitoring for river flood forecasts, and a photographic overlay technique of imagery to enhance snowcover are presented. Ground truth comparisons show a thermal accuracy of approximately + or - 1 C for detection of surface radiative temperatures. The application of NOAA imagery to flood mapping is also presented

    Hydrologic Properties of Subarctic Organic Soils

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    Completion Report for U. S. Forest Service Institute of Northern Forestry Cooperative Agreement No. 16 USC 581; 581a-581iThe need for understanding the natural system and how it responds to various stresses is important; this is especially so in an environment where the climate not only sustains permafrost, but develops massive seasonal frost as well. Consequently, the role of the shallow surface organic layer is also quite important. Since a slight change in the soil thermal regime may bring about a phase change in the water or ice, therefore, the system response to surface alterations such as burning can be quite severe. The need for a better understanding of the behavior and properties of the organic layer is, therefore, accentuated. The central theme of this study was the examination of the hydrologic and hydraulic properties of subarctic organic soils. Summarized in this paper are the results of three aspects of subarctic organic soil examinations conducted during the duration of the project. First, a field site was set up in Washington Creek with the major emphasis on measuring numerous variables of that soil system during the summer. The greatest variations in moisture content occur in the thick organic soils that exist at this site. Our major emphasis was to study the soil moisture levels in these soils. This topic is covered in the first major section, including associated laboratory studies. Those laboratory studies include investigations of several hydraulic and hydrologic properties of taiga organic and mineral soils. Second, some field data on organic moisture levels was collected at the site of prescribed burns in Washington Creek to ascertain the sustainability of fires as a function of moisture levels. This portion of the study is described under the second major heading. The last element of this study was a continued application of the two-dimensional flow model that was developed in an earlier study funded by the U. S. Forest Service, Institute of Northern Forestry, and reported by Kane, Luthin, and Taylor (1975a). Many of the results and concepts gathered in the field work were integrated into the modeling effort, which is aimed at producing better estimates of the hydrologic effects of surface disturbances in the black spruce taiga subarctic ecosystem. This knowledge should also contribute to better fire management decisions of the same system.The work upon which this report is based was made possible by a cooperative aid agreement funded by the U. S. Forest Service, Institute of Northern Forestry, Fairbanks, Alaska. Contribution to this study was also made by Ohio State University
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