2,983 research outputs found

    Multispectral processing based on groups of resolution elements

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    Several nine-point rules are defined and compared with previously studied rules. One of the rules performed well in boundary areas, but with reduced efficiency in field interiors; another combined best performance on field interiors with good sensitivity to boundary detail. The basic threshold gradient and some modifications were investigated as a means of boundary point detection. The hypothesis testing methods of closed-boundary formation were also tested and evaluated. An analysis of the boundary detection problem was initiated, employing statistical signal detection and parameter estimation techniques to analyze various formulations of the problem. These formulations permit the atmospheric and sensor system effects on the data to be thoroughly analyzed. Various boundary features and necessary assumptions can also be investigated in this manner

    Experimental clean combustor program, alternate fuels addendum, phase 2

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    The characteristics of current and advanced low-emissions combustors when operated with special test fuels simulating broader range combustion properties of petroleum or coal derived fuels were studied. Five fuels were evaluated; conventional JP-5, conventional No. 2 Diesel, two different blends of Jet A and commercial aromatic mixtures - zylene bottoms and haphthalene charge stock, and a fuel derived from shale oil crude which was refined to Jet A specifications. Three CF6-50 engine size combustor types were evaluated; the standard production combustor, a radial/axial staged combustor, and a double annular combustor. Performance and pollutant emissons characteristics at idle and simulated takeoff conditions were evaluated in a full annular combustor rig. Altitude relight characteristics were evaluated in a 60 degree sector combustor rig. Carboning and flashback characteristics at simulated takeoff conditions were evaluated in a 12 degree sector combustor rig. For the five fuels tested, effects were moderate, but well defined

    Experimental clean combustor program, phase 1

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    Full annular versions of advanced combustor designs, sized to fit within the CF6-50 engine, were defined, manufactured, and tested at high pressure conditions. Configurations were screened, and significant reductions in CO, HC, and NOx emissions levels were achieved with two of these advanced combustor design concepts. Emissions and performance data at a typical AST cruise condition were also obtained along with combustor noise data as a part of an addendum to the basic program. The two promising combustor design approaches evolved in these efforts were the Double Annular Combustor and the Radial/Axial Combustor. With versions of these two basic combustor designs, CO and HC emissions levels at or near the target levels were obtained. Although the low target NOx emissions level was not obtained with these two advanced combustor designs, significant reductions were relative to the NOx levels of current technology combustors. Smoke emission levels below the target value were obtained

    The Visual Experience of Image Metaphor: Cognitive Insights into Imagist Figures

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    In this essay I investigate how image metaphors – metaphors that link one concrete object to another, such as “her spread hand was a starfish” – promote visualization in the reader. Focusing on image metaphors in Imagist poetry, I assert that the two terms (e.g., the hand and the starfish) of many of these metaphors are similar in shape, and that this “structural correspondence” encourages the reader to visualize those metaphors. Readers may spontaneously form a “visual template,” a schematic middle ground that mediates between those similar shapes, in order to smoothly move between the two images within each metaphor. The structural correspondence and the mediating visual template allow readers to mentally shift back and forth between the two images, yet readers cannot fuse the two terms through visual imagery. Research supports these claims: reader reports have demonstrated that subjects understand image metaphors primarily through their physical features, and work on the visual interpretation of ambiguous figures suggests that though one cannot fuse images together, one may switch back and forth between multiple images of a figure, especially if the images share the same frame of reference. These findings indicate that readers may be particularly likely to understand image metaphor through visual imagery, especially when the terms of the metaphor correspond physically. This essay is drawn from a larger project on the “poetics of literary visualization” – a part-by-part investigation of the formal features of texts that elicit visual imagery. Such an account helps to reveal the workings of the visual imagination and restore critical attention to this neglected aspect of the reading experience

    Letter from Herbert W. Gleason to John Muir, 1912 Jun 20.

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    Our National Parks Yellowstone ParkYosemite Park Glacier ParkMt. Rainier ParkGrand Canyon of ArizonaLuther Burbank and his Wonderful Plant ProductionsEl Camino Real — a Tour Among the Old Spanish MissionsThe Gardens and Deserts of Southern California,Yosemite Valley and the Big TreesCamping and Tramping with the Sierra Club in the High Sierras Along the California Coast Trees and Wild Flowers of CaliforniaHetch-Hetchy and the Grand Canyon of the TuolumneVolcanic Peaks of the Pacific Coast AlaskaThe Canadian AlpsIn the Heart of the SelkirksRambles in the Canadian Rockies At the Sources of the Columbia RiverWild Flowers of the Canadian RockiesIn Thoreau\u27s CountryThe Maine WoodsWild Flowers of New England Cape CodRambles in Bird-landAmong the Wild Flowers Mushrooms and Other Fungi Glacier Studies The Ocean The Prairie The DesertHERBRT W. GLEASONILLUSTRATED LECTURES ON TRAVEL ANDNATURE STUDY83 PINCKNEY STREET.BOSTON.MASS.June 20, 1912.My dear Mr. Muir:I have just read John Burroughs review of your Yosemite in the Literary Digest of June 1. I hope you will go on with your glorious writing, describing the glorious scenes of California\u27s glorious mountains and glorious parks and glorious forests and glorious water-falls, just as long and just as GLORIOUSLY as you can! And don\u27t forget to tell us all about the psalms and hymms and spiritual songs which you hear in the aforesaid mountains, water-falls, etc. J. B., cold-blooded agnostic that he is, may not like it, but it appeals immensely to the people who read your books.We are just off on a three months\u27 trip to the West, going first to the Canadian Rockies, then to Glacier Park, then to the Olympics and possibly home by way of Enos Mills ranch in the shadow of Long\u27s Peak, Colorado. How I wish you were going with us!Love from us both.Faithfully yours,[illegible]0521

    Combustor concepts for aircraft gas turbine low-power emissions reduction

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    Several combustor concepts were designed and tested to demonstrate significant reductions in aircraft engine idle pollutant emissions. Each concept used a different approach for pollutant reductions: the hot wall combustor employs a thermal barrier coating and impingement cooled liners; the recuperative cooling combustor preheats the air before entering the combustion chamber; and the catalytic converter combustor is composed of a conventional primary zone followed by a catalytic bed for pollutant cleanup. The designs are discussed in detail and test results are presented for a range of aircraft engine idle conditions. The results indicate that ultralow levels of unburned hydrocarbons and carbon monoxide emissions can be achieved

    Consideration of radar target glint from ST during OMV rendezvous

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    The nature of radar target glint and the factors upon which it depends when using the Hubble Space Telescope as a radar target is discussed. An analysis of the glint problem using a 35 MHz or 94 MHz radar on the orbital maneuvering vehicle is explored. A strategy for overcoming glint is suggested

    Multispectral system analysis through modeling and simulation

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    The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in LANDSAT data, examining system design and operational configuration, and development of information extraction techniques

    Atmospheric modeling related to Thematic Mapper scan geometry

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    A simulation study was carried out to characterize atmospheric effects in LANDSAT-D Thematic Mapper data. In particular, the objective was to determine if any differences would result from using a linear vs. a conical scanning geometry. Insight also was gained about the overall effect of the atmosphere on Thematic Mapper signals, together with the effects of time of day. An added analysis was made of the geometric potential for direct specular reflections (sun glint). The ERIM multispectral system simulation model was used to compute inband Thematic Mapper radiances, taking into account sensor, atmospheric, and surface characteristics. Separate analyses were carried out for the thermal band and seven bands defined in the reflective spectral region. Reflective-region radiances were computed for 40 deg N, 0 deg, and 40 deg S latitudes; June, Mar., and Dec. days; and 9:30 and 11:00 AM solar times for both linear and conical scan modes. Also, accurate simulations of solar and viewing geometries throughout Thematic Mapper orbits were made. It is shown that the atmosphere plays an important role in determining Thematic Mapper radiances, with atmospheric path radiance being the major component of total radiances for short wavelengths and decreasing in importance as wavelength increases. Path radiance is shown to depend heavily on the direct radiation scattering angle and on haze content. Scan-angle-dependent variations were shown to be substantial, especially for the short-wavelength bands

    Wheat signature modeling and analysis for improved training statistics: Supplement. Simulated LANDSAT wheat radiances and radiance components

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    Simulated scanner system data values generated in support of LACIE (Large Area Crop Inventory Experiment) research and development efforts are presented. Synthetic inband (LANDSAT) wheat radiances and radiance components were computed and are presented for various wheat canopy and atmospheric conditions and scanner view geometries. Values include: (1) inband bidirectional reflectances for seven stages of wheat crop growth; (2) inband atmospheric features; and (3) inband radiances corresponding to the various combinations of wheat canopy and atmospheric conditions. Analyses of these data values are presented in the main report
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