9,166 research outputs found

    A New Handbook for the Development of Space Vehicle Terrestrial Environment Design Requirements

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    A new NASA document entitled "Terrestrial Environment (Climatic) Criteria Handbook for Use in Aerospace Vehicle Development (NASA-HDBK-IOO1A) has been developed. The Handbook provides terrestrial environment information, data bases, models, recommendations, etc. for use in the design, development, trade studies, testing, and mission analyses for space (or launch) vehicles. This document is organized into fourteen specific natural environment disciplines of which some are winds, atmospheric models, thermal radiation, precipitation-for-icing, cloud cover, atmospheric electricity, geologic hazards, toxic chemical release by propulsion systems, and sea state. Atmospheric phenomena play a significant role in the design and flight of aerospace vehicles and in the integrity of the associated aerospace systems and structures. Environmental design criteria guidelines in this document are based on measurements and observations of atmospheric and climatic phenomena relative to various aerospace development, operational, and vehicle launch locations. The natural environment criteria guidelines data presented in this Handbook were formulated based on discussions with and requests from engineers involved in aerospace vehicle development and operations. Therefore, they represent responses to actual engineering problems and are not just a general compilation of environmental data. The Handbook addresses the basis for the information presented, the interpretations of the terrestrial environment guideline given in the Handbook, and its application to the development of aerospace vehicle design requirements. Specific examples of the Handbook content and associated "lessons lenmed" are given in this paper

    Evaluation of Fluorapatite as a Waste-Form Material: Third Quarter Report, March 1 - May 31 2003

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    Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite-based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal will develop a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF4, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form with natural analogs. Characterization of the material will be accomplished through probing the molecular-scale electronic and geometric structure of the materials in order to relate them to macroscopic properties, with the goal of developing techniques to evaluate and predict the performance of different waste-form materials. Time and funding permitting, other waste forms for the zirconium fluoride, fission product salt waste stream will be examined and benchmarked against the fluorapatite matrix baseline. Highlights of Accomplishments: 1. Baseline spectroscopic measurements have been obtained for commercial hydroxyapatite and natural fluorapatite using a wide variety of techniques (e.g., Raman, XPS, FT-IR) useful for probing the chemical and physical properties of materials. 2. Detailed SEM images of natural fluorapatite crystals indicate the presence of naturally included minerals (e.g., Ni), offering the possibility of studying natural analogs to waste-loaded apatite materials

    A Summary of Various Economic Data From Accounts of Farm Record-Keeping Families in Taiwan, Yearly Averages Covering 1960 Through 1970

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    Citations, Research and Agricultural Economists in 25 Universities, 1966-1990

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    Changes in Small Farmer Credit Use in Southern Brazil, 1965-69

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    Evaluation of Fluorapatite as a Waste-Form Material

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    Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal will develop a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF4, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form with natural analogs. Characterization of the material will be accomplished through probing the molecular-scale electronic and geometric structure of the materials in order to relate them to macroscopic properties, with the goal of developing techniques to evaluate and predict the performance of different waste-form materials. Time and funding permitting, other waste forms for the zirconium fluoride, fission product salt waste stream will be examined and benchmarked against the fluorapatite matrix baseline

    Expanding Rural Lending Through Merchant-Credit Projects

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    Merchant-credit projects offer the potential of providing short-term stop-gap informal loans to small borrowers in countries where the formal financial system is in disarray and where weak property rights hinder formal finance. Credit projects involving the Agricultural Bank of Malaysia, contract or bridge lending in the Dominican Republic, the PNN Scheme in Sri Lanka, and the NAPP program in the Philippines are briefly reviewed. The advantages and weaknesses of merchant-credit projects are summarized
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