24,023 research outputs found

    Use of a transcendental approximation in transient conduction analysis

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    Variation method applied to transient thermal conductivity in semiinfinite slab with nonlinear boundary conditio

    Commercial air transport hazard warning and avoidance system. Volume 1 - Summary Final report

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    Operational requirements for commercial air transport hazard warning and avoidance syste

    Use of a transcendental approximation in transient conduction analysis

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    Boundary condition solution and transcendental approximation for transient heat conduction proble

    Tungsten thermal neutron dosimeter

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    Tungsten-185 activity, which is produced by neutron activation of tungsten-184, determines thermal neutron flux. Radiochemical separation methods and counting techniques for irradiated tungsten provide accurate determination of the radiation exposure

    Progress Report to the TNRC for Analysis of the Economics of Atrazine Remediation for Representative Grain Farms in the Aquilla Watershed, Hill County, Texas: Subtasks 4.0-4.4

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    Four alternative BMPs for atrazine remediation were reported by Harmon and Wang for the study area. The BMPs involved alternative incorporation practices, tillage operations, and sediment ponds. Harmon and Wang reported no statistical difference in corn yields under the alternative BMPs. An economic analysis of four alternative best management practices (BMPs) for atrazine remediation in Hill County, Texas, was performed by the Agricultural and Food Policy Center (AFPC) at Texas A&M University. Using the farm-level economic simulation model FLIPSIM, AFPC scientists analyzed the financial effects of the alternative BMPs on the Texas Blackland Prairie representative farm. This farm consists of 2,000 dryland acres, divided among corn (600 acres), sorghum (750 acres), wheat (250 acres), and native pasture (150 acres). This farm also maintains a small beef cowherd. Regularly updated, the AFPC maintains more than 80 farms across the nation that form the basis for probabilistic-based agricultural policy evaluation.Agricultural and Food Policy, Resource /Energy Economics and Policy,

    Improvements in estimating proportions of objects from multispectral data

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    Methods for estimating proportions of objects and materials imaged within the instantaneous field of view of a multispectral sensor were developed further. Improvements in the basic proportion estimation algorithm were devised as well as improved alien object detection procedures. Also, a simplified signature set analysis scheme was introduced for determining the adequacy of signature set geometry for satisfactory proportion estimation. Averaging procedures used in conjunction with the mixtures algorithm were examined theoretically and applied to artificially generated multispectral data. A computationally simpler estimator was considered and found unsatisfactory. Experiments conducted to find a suitable procedure for setting the alien object threshold yielded little definitive result. Mixtures procedures were used on a limited amount of ERTS data to estimate wheat proportion in selected areas. Results were unsatisfactory, partly because of the ill-conditioned nature of the pure signature set

    Interplanetary Trajectory Optimization with Powerlimited Propulsion Systems

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    A trajectory-optimization process is described in which the optimum thrust equations are derived using the calculus of variations. The magnitude of the thrust is constrained within an upper and a lower bound, but the thrust direction is arbitrary. This formulation allows both the constant-thrust program and the variable-thrust program to be considered. For the constant-thrust program, certain propulsion-system parameters are optimized for maximum final vehicle mass. This theory has been used to study interplanetary missions to Venus and Mars using a power-limited propulsion system. Both one-way and round trip rendezvous trajectories are considered. The analysis employs a two-body inverse-square force-field model of three dimensions. An iterative routine used to solve the two-point boundary-value problem is described in the Appendix

    K-orbit closures on G/B as universal degeneracy loci for flagged vector bundles with symmetric or skew-symmetric bilinear form

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    We use equivariant localization and divided difference operators to determine formulas for the torus-equivariant fundamental cohomology classes of KK-orbit closures on the flag variety G/BG/B, where G = GL(n,\C), and where KK is one of the symmetric subgroups O(n,\C) or Sp(n,\C). We realize these orbit closures as universal degeneracy loci for a vector bundle over a variety equipped with a single flag of subbundles and a nondegenerate symmetric or skew-symmetric bilinear form taking values in the trivial bundle. We describe how our equivariant formulas can be interpreted as giving formulas for the classes of such loci in terms of the Chern classes of the various bundles.Comment: Minor revisions and corrections suggested by referees. Final version, to appear in Transformation Group
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