1,627 research outputs found

    The relative influence of raw material components upon the thermal expansion of vitreous enamel.

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    Sample Acquisition and Instrument Deployment (SAID)

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    This report details the interim progress for contract NASW-4818, Sample Acquisition and Instrument Deployment (SAID), a robotic system for deploying science instruments and acquiring samples for analysis. The system is a conventional four degree of freedom manipulator 2 meters in length. A baseline design has been achieved through analysis and trade studies. The design considers environmental operating conditions on the surface of Mars, as well as volume constraints on proposed Mars landers. Control issues have also been studied, and simulations of joint and tip movements have been performed. A passively braked shape memory actuator with the ability to measure load has been developed. The wrist also contains a mechanism which locks the lid output to the bucket so that objects can be grasped and released for instrument deployment. The wrist actuator has been tested for operational power and mechanical functionality at Mars environmental conditions. The torque which the actuator can produce has been measured. Also, testing in Mars analogous soils has been performed

    Quantum-secured imaging

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    We have built an imaging system that uses a photon's position or time-of-flight information to image an object, while using the photon's polarization for security. This ability allows us to obtain an image which is secure against an attack in which the object being imaged intercepts and resends the imaging photons with modified information. Popularly known as "jamming," this type of attack is commonly directed at active imaging systems such as radar. In order to jam our imaging system, the object must disturb the delicate quantum state of the imaging photons, thus introducing statistical errors that reveal its activity.Comment: 10 pages (double spaced), 5 figure

    Cottontail Rabbit Habitat Use on Delaware Wildlife Area, Ohio

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    Author Institution: Ohio Department of Natural Resources, Division of WildlifeA radio telemetry study was performed on cottontail rabbits (Sylvilagus floridanus mearnsii) to quantify cover type use and infer selections with respect to cover type availability, year, sex- and age-class, time of day, and season. This study recorded 16,785 locations for 62 rabbits from 1981-1983. Briars (Rubus spp., Rosa multiflord) and old field were the two most used types of cover, together comprising more than 50% of locations. Relative to cover type availability, the briars type was the most preferred (P < 0.05). Both types were used heavily during day and night throughout the year, although use of briars was higher during day than night (P < 0.05). Rabbits that had survived a winter and spring spent more time in briars (P < 0.05) and less time in old field OP < 0.05) than those that had not. Implications are that wildlife managers must increase their emphasis on providing briars or other dense woody vegetation to maintain rabbit populations. Based on use percentages, rabbit cover type needs would be better met if percentages of area were: briars, herb-shrub, and cropland — each 25-35%; woodland — 0-10%

    Financial Metrics In Wide-Moat Firms

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    According to Morningstar companies with certain structural characteristics enjoy economic moats. Compared to benchmark indices, Morningstar hypothesizes that over a ten-year time frame these firms will evidence superior price appreciation. Based on analysis of 1360 companies, this study supports the thesis of historical performance among wide-moat firms

    LANDOWNER ATTITUDES REGARDING PENNSYLVANIA\u27S EXTENDED ANTERLESS DEER SEASON ON DEER-DAMAGED FARMS

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    The Pennsylvania Game Commission authorized an extension of the 1990-1991 anterless white-tailed deer (Odocoileus virginianus) season to reduce deer abundance on farms having excessive crop damage. A mail survey of the 574 participating landowners was conducted to assess the effectiveness of the program. After 2 mailings 93% (n = 531) responded, and 444 returns had completed information for numbers of hunters, hectares, and harvested deer. Based on landowner responses, an estimated 2,674 deer were harvested by 35,181 hunters on 58,525 ha. An average of 4.6 deer were harvested/km2 of huntable land, which compared to a statewide estimate of f2.3 deer harvested/km2 during the 1990 4-day regular anterless-deer season. Twenty-four percent (n = 107) of respondents reported zero deer harvested. Twenty-five percent of respondents (n = 110) were satisfied with the program. Landowners who were dissatisfied (n = 331, 75%) could provide up to 5 reasons for dissatisfaction. Four hundred sixty-nine responses were provided. Three-hundred-forty-seven responses (74%) indicated too few deer were killed, while 23% (n = 106) indicated that the program was inconvenient. Satisfaction related to number and density of deer harvested, hectares of huntable land, perception of hunter density, and suggested improvements. Many respondents (n = 204, 46%)indicated they would participate again, in spite of the high degree of dissatisfaction. Number and density of deer harvested, density of hunters, perception of hunter density, satisfaction, and reason for dissatisfaction, were related to willingness to participate again. Landowner suggestions for improvements (5 allowed per respondent, n = 364 recieved) centered on harvesting more deer by involving more land (n = 201, 55%) and moving the timing of the season (n = 119, 33%). Seventy-two percent (n = 320) of responses (5 allowed per respondent, n = 625 recieved) indicated neighboring posted land was the primary reason for too many deer on their property. This remains the greatest challenge in providing relief from high deer densities

    Characteristics of vertical and lateral tunnel turbulence measured in air in the Langley Transonic Dynamics Tunnel

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    Preliminary measurements of the vertical and lateral velocity components of tunnel turbulence were obtained in the Langley Transonic Dynamics Tunnel test section using a constant-temperature anemometer equipped with a hot-film X-probe. For these tests air was the test medium. Test conditions included tunnel velocities ranging from 100 to 500 fps at atmospheric pressure. Standard deviations of turbulence velocities were determined and power spectra were computed. Unconstrained optimization was employed to determine parameter values of a general spectral model of a form similar to that used to describe atmospheric turbulence. These parameters, and others (notably break frequency and integral scale length), were determined at each test condition and compared with those of Dryden and Von Karman atmospheric turbulence spectra. When the data were discovered to be aliased, the spectral model was modified to account for and 'eliminate' the aliasing

    Compressive Object Tracking using Entangled Photons

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    We present a compressive sensing protocol that tracks a moving object by removing static components from a scene. The implementation is carried out on a ghost imaging scheme to minimize both the number of photons and the number of measurements required to form a quantum image of the tracked object. This procedure tracks an object at low light levels with fewer than 3% of the measurements required for a raster scan, permitting us to more effectively use the information content in each photon.Comment: 10 pages, 4 figure

    Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor

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    We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns (group index of approximately 200) with little pulse distortion. The delay is made tunable with a fast reconfiguration time (hundreds of ns) by optically pumping out of the atomic ground states.Comment: 4 pages, 6 figure
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