42,359 research outputs found

    TECHNOLOGICAL CHANGE AND LABOR'S RELATIVE SHARE: THE MECHANIZATION OF U.S. COTTON PRODUCTION

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    Research and Development/Tech Change/Emerging Technologies,

    ALTERNATIVE COTTON PRODUCTION SYSTEMS

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    Mississippi cotton farmers are adjusting to the current problem of low cotton price and high cotton production cost by modifying the way(s) they have traditionally grown cotton. This paper compares seven alternative production systems to the costs and returns associated with the conventional or traditional system labeled "solid cotton, 8-row equipment." Systems that combine wider equipment (less labor and machinery time per acre) with reduced tillage technology appear to offer opportunities to increase returns. Specific adjustments on individual farms will probably be dominated by the distribution of soil types.conservation tillage, ultra-narrow, no-till, skip-row, costs, returns, Production Economics,

    Design, construction, and utilization of a space station assembled from 5-meter erectable struts

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    The primary characteristics of the 5-meter erectable truss is presented, which was baselined for the Space Station. The relatively large 5-meter truss dimension was chosen to provide a deep beam for high bending stiffness yet provide convenient mounting locations for space shuttle cargo bay size payloads which are approx. 14.5 ft (4.4 m) in diameter. Truss nodes and quick attachment erectable joints are described which provide for evolutionary three dimensional growth and for simple maintenance and repair. A mobile remote manipulator system is described which is provided to assist in station construction and maintenance. A discussion is also presented of the construction of the Space Station and the associated extravehicular active (EVA) time

    The Effectiveness of State and Local Regulation of Handguns: A Statistical Analysis

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    One aspect of the continuing debate over weapons control, apart from Constitutional issues, is whether legislation is inherently capable of reducing crime and deaths by shooting. The opponents of increased control, tacitly admitting that empirical evidence is one means for measuring the effect of weapons regulation, have contended that [e]xpert opinion and compelling evidence seem to indicate that the amount or kind of crime in a community is not substantially affected by the relative ease with which a person can obtain a firearm. National Rifle Association of America, The Gun Law Problem 10. In the following study the authors employ data analysis techniques to examine the efficacy of state and municipal controls on handguns. They conclude that many lives would be saved if all states increased their level of control to that of New Jersey, the state having the most stringent gun control laws

    Candidate Technologies for the Integrated Health Management Program

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    The purpose of this report is to assess Vehicle Health Management (VHM) technologies for implementation as a demonstration. Extensive studies have been performed to determine technologies which could be implemented on the Atlas and Centaur vehicles as part of a bridging program. This paper discusses areas today where VHM can be implemented for benefits in reliability, performance, and cost reduction. VHM Options are identified and one demonstration is recommended for execution

    Preliminary design of a large tetrahedral truss/hexagonal heatshield panel aerobrake

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    An aerobrake structural concept is introduced which consists of two primary components: (1) a lightweight erectable tetrahedral support truss; and (2) sandwich hexagonal heatshield panels which, when attached to the truss, form a continuous impermeable aerobraking surface. Generic finite element models and a general analysis procedure to design tetrahedral truss/hexagonal heatshield panel aerobrakes is developed, and values of the aerobrake design parameters which minimize mass and packaging volume for a 120-foot-diameter aerobrake are determined. Sensitivity of the aerobrake design to variations in design parameters is also assessed. The results show that a 120-foot-diameter aerobrake is viable using the concept presented (i.e., the aerobrake mass is less than or equal to 15 percent of the payload spacecraft mass). Minimizing the aerobrake mass (by increasing the number of rings in the support truss) however, leads to aerobrakes with the highest part count
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