26,958 research outputs found

    Discrimination techniques employing both reflective and thermal multispectral signals

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    Recent improvements in remote sensor technology carry implications for data processing. Multispectral line scanners now exist that can collect data simultaneously and in registration in multiple channels at both reflective and thermal (emissive) wavelengths. Progress in dealing with two resultant recognition processing problems is discussed: (1) More channels mean higher processing costs; to combat these costs, a new and faster procedure for selecting subsets of channels has been developed. (2) Differences between thermal and reflective characteristics influence recognition processing; to illustrate the magnitude of these differences, some explanatory calculations are presented. Also introduced, is a different way to process multispectral scanner data, namely, radiation balance mapping and related procedures. Techniques and potentials are discussed and examples presented

    Experimental Effervescence and Freezing Point Depression Measurements of Nitrogen in Liquid Methane-Ethane Mixtures

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    NASA is designing an unmanned submarine to explore the depths of the hydrocarbon-rich seas on Saturn's moon Titan. Data from Cassini indicates that the Titan north polar environment sustains stable seas of variable concentrations of ethane, methane, and nitrogen, with a surface temperature near 93 K. The submarine must operate autonomously, study atmosphere/sea exchange, interact with the seabed, hover at the surface or any depth within the sea, and be capable of tolerating variable hydrocarbon compositions. Currently, the main thermal design concern is the effect of effervescence on submarine operation, which affects the ballast system, science instruments, and propellers. Twelve effervescence measurements on various liquid methane-ethane compositions with dissolved gaseous nitrogen are thus presented from 1.5 bar to 4.5 bar at temperatures from 92 K to 96 K to simulate the conditions of the seas. After conducting effervescence measurements, two freezing point depression measurements were conducted. The freezing liquid line was depressed more than 15 K below the triple point temperatures of pure ethane (90.4 K) and pure methane (90.7 K). Experimental effervescence measurements will be used to compare directly with effervescence modeling to determine if changes are required in the design of the thermal management system as well as the propellers

    Evaluation of algorithms for estimating wheat acreage from multispectral scanner data

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    The author has identified the following significant results. Fourteen different classification algorithms were tested for their ability to estimate the proportion of wheat in an area. For some algorithms, accuracy of classification in field centers was observed. The data base consisted of ground truth and LANDSAT data from 55 sections (1 x 1 mile) from five LACIE intensive test sites in Kansas and Texas. Signatures obtained from training fields selected at random from the ground truth were generally representative of the data distribution patterns. LIMMIX, an algorithm that chooses a pure signature when the data point is close enough to a signature mean and otherwise chooses the best mixture of a pair of signatures, reduced the average absolute error to 6.1% and the bias to 1.0%. QRULE run with a null test achieved a similar reduction

    Mercator's Southern Continent

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    The age-old concept that a vast southern landmass must of necessity exist to counterbalance that in the northern hemisphere was given graphic expression by many cartographers, including Ptolemy, Johannes Schoener and Oronce Fine, but undoubtedly the most famous one is that depicted by Gerard Mercator

    Review of Rainer Daehnhardt, George Collingridge & Richard H. Major, 'Segredos da descoberta da Australia pelos portugueses'. Sintra (Portugal): Zefiro, 2009

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    This is the latest book claiming that the Portuguese discovered Australia. Belief in the validity of the claim appears to be contagious, despite the lack of any reliable evidence to support it

    REGIONAL COTTON ACREAGE RESPONSE

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    An econometric model of cotton acreage response was estimated for four distinct production regions in the United States. This work builds on previous work in the area of supply response under government farm programs and provides up-to-date regionalized estimates of own-price elasticity of cotton acreage supply. The own-price variable used in this study is a weighted combination of expected market price and government policy variables. Results indicate regional similarity in response to own price but differences with respect to the prices of alternative enterprises. Differences in regional response to paid diversion are also indicated.Crop Production/Industries,

    EFFECTS OF ALTERNATIVE FARM PROGRAMS AND LEVELS OF PRICE VARIABILITY ON TEXAS COTTON FARMS

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    This study examines the effects of alternative government farm programs and hypothetical price variability levels on two Texas cotton farms which were simulated stochastically over a 10-year period. Results indicate that a combination of high price variability and participation in government programs stimulates growth and wealth accumulation.Public Economics,

    Initial results from the NASA Lewis Bumpy Torus experiment

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    Initial results were obtained from low power operation of the NASA Lewis Bumpy Torus experiment, in which a steady-state ion heating method based on the modified Penning discharge is applied in a bumpy torus confinement geometry. The magnet facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 T, equally spaced in a toroidal array 1.52 m in major diameter. A 18 cm i.d. anode ring is located at each of the 12 midplanes and is maintained at high positive potentials by a dc power supply. Initial observations indicate electron temperatures from 10 to 150 eV, and ion kinetic temperatures from 200 eV to 1200 eV. Two modes of operation were observed, which depend on background pressure, and have different radial density profiles. Steady state neutron production was observed. The ion heating process in the bumpy torus appears to parallel closely the mechanism observed when the modified Penning discharge was operated in a simple magnetic mirror field

    DISTRIBUTION CHOICE UNDER NULL PRIORS AND SMALL SAMPLE SIZE

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    Defining appropriate probability distributions for the variables in an economic model is an important and often arduous task. This paper evaluates the performance of several common probability distributions under different distributional assumptions when sample sizes are small and there is limited information about the data.Research Methods/ Statistical Methods,

    ECONOMETRIC MODEL OF THE U.S. SHEEP INDUSTRY FOR POLICY ANALYSIS

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    The U.S. sheep inventory has been declining for many years. To further investigate this trend, an econometric sector model using single demand equations was developed to analyze the impacts of two alternative levels of wool marketing loan rates.Marketing,
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