15,719 research outputs found

    Study of ephemeris accuracy of the minor planets

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    The current state of minor planet ephemerides was assessed, and the means for providing and updating these emphemerides for use by both the mission planner and the astronomer were developed. A system of obtaining data for all the numbered minor planets was planned, and computer programs for its initial mechanization were developed. The computer based system furnishes the osculating elements for all of the numbered minor planets at an adopted date of October 10, 1972, and at every 400 day interval over the years of interest. It also furnishes the perturbations in the rectangular coordinates relative to the osculating elements at every 4 day interval. Another computer program was designed and developed to integrate the perturbed motion of a group of 50 minor planets simultaneously. Sampled data resulting from the operation of the computer based systems are presented

    Surface parameters of stannic oxide in powder, ceramic, and gel form by nitrogen adsorption techniques Interim report

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    Surface parameters of stannic oxide in powder, ceramic, and gel form by nitrogen adsorption techniques - analysis of adsorption isotherm

    Performance of alumina-supported Pt catalysts in an electron-beam-sustained CO2 laser amplifier

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    The performance of an alumina-supported Pt catalyst system used to maintain the gas purity in an electron-beam-sustained (636) isotope CO2 laser amplifier has been tested. The system characteristics using the two-zone, parallel flow reactor were determined for both continuous- and end-of-day reactor operation using on-line mass spectrometric sampling. The laser amplifier was run with an energy loading of typically 110 J-l/atm and an electron-beam current of 4 mA/sq cm. With these conditions and a pulse repetition frequency of 10 Hz for up to 10,000 shots, increases on the order of 100 ppm O2 were observed with the purifier on and 150 ppm with it off. The 1/e time recovery time was found to be approximately 75 minutes

    NLC-2 graph recognition and isomorphism

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    NLC-width is a variant of clique-width with many application in graph algorithmic. This paper is devoted to graphs of NLC-width two. After giving new structural properties of the class, we propose a O(n2m)O(n^2 m)-time algorithm, improving Johansson's algorithm \cite{Johansson00}. Moreover, our alogrithm is simple to understand. The above properties and algorithm allow us to propose a robust O(n2m)O(n^2 m)-time isomorphism algorithm for NLC-2 graphs. As far as we know, it is the first polynomial-time algorithm.Comment: soumis \`{a} WG 2007; 12

    Subscale Flight Testing for Aircraft Loss of Control: Accomplishments and Future Directions

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    Subscale flight-testing provides a means to validate both dynamic models and mitigation technologies in the high-risk flight conditions associated with aircraft loss of control. The Airborne Subscale Transport Aircraft Research (AirSTAR) facility was designed to be a flexible and efficient research facility to address this type of flight-testing. Over the last several years (2009-2011) it has been used to perform 58 research flights with an unmanned, remotely-piloted, dynamically-scaled airplane. This paper will present an overview of the facility and its architecture and summarize the experimental data collected. All flights to date have been conducted within visual range of a safety observer. Current plans for the facility include expanding the test volume to altitudes and distances well beyond visual range. The architecture and instrumentation changes associated with this upgrade will also be presented

    The calibration of photographic and spectroscopic films: Reciprocity failure and thermal responses of IIaO film at liquid nitrogen temperatures

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    Reciprocity failure was examined for IIaO spectroscopic film. The results indicate reciprocity failure occurs at three distinct minimum points in time; 15 min, 30 min and 90 min. The results are unique because theory suggests only one minimum reciprocity failure point should occur. When incubating 70mm IIaO film for 15 and 30 min at temperatures of 30, 40, 50, and 60 C and then placing in a liquid nitrogen bath at a temperature of -190 C the film demonstrated an increase of the optical density when developed at a warm-up time of 30 min. Longer warm-up periods of 1, 2 and 3 hrs yield a decrease in optical density of the darker wedge patterns; whereas, shorter warm-up times yield an overall increase in the optical densities
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