2,742 research outputs found

    NASA Marshall Space Flight Center Range Report - May 2015

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    The following is a summary of the major meteorological/atmospheric projects and research that have been or currently are being accomplished at Marshall Space Flight Center (MSFC). Listed below are highlights of work done during the past 6 months in the Engineering Directorate (ED) and in the Science and Mission Systems Office (ZP)

    MEASUREMENT OF PRICE RISK IN REVENUE INSURANCE: IMPLICATIONS OF DISTRIBUTIONAL ASSUMPTIONS

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    A variety of crop revenue insurance programs have recently been introduced. A critical component of revenue insurance contracts is quantifying the risk associated with stochastic prices. Forward-looking, market-based measures of price risk which are often available in form of options premia are preferable. Because such measures are not available for every crop, some current revenue insurance programs alternatively utilize historical price data to construct measures of price risk. This study evaluates the distributional implications of alternative methods for estimating price risk and deriving insurance premium rates. A variety of specification tests are employed to evaluate distributional assumptions. Conditional heteroskedasticity models are used to determine the extent to which price distributions may be characterized by nonconstant variances. In addition, these models are used to identify variables which may be used for conditioning distributions for rating purposes. Discrete mixtures of normals provide flexible parametric specifications capable of recognizing the skewness and kurtosis present in commodity pricesRisk and Uncertainty,

    Defining the Natural Atmospheric Environment Requirements for the NASA Constellation Program

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    The National Aeronautics and Space Administration began developing a new vehicle under the Constellation Program to replace the Space Shuttle. The Ares-1 launch vehicle and the Orion capsule will be used to ferry crew and some payloads to the International Space Station and will also be used for new missions to the moon, As development of this new vehicle begins, the Natural Environments Branch at Marshall Space Flight Center has been tasked with defining the natural environments the vehicle will encounter and working with the program to develop natural environmental requirements for the vehicles' elements. An overview of the structure of the program is given, along with a description of the Constellation Design Specification for Natural Environments and the Constellation Natural Environments Definition for Design documents and how they apply to the Ares-I and Orion vehicles

    Current Activities and Capabilities of the Terrestrial Environment Group at NASA's Marshall Space Flight Center

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    The National Aeronautics and Space Administration (NASA) designated Marshall Space Flight Center (MSFC) the center of excellence for space transportation. The Aerospace Environments and Effects (AEE) team of the Electromagnetics and Aerospace Environments Branch (EL23) in the Systems Analysis and Integration Laboratory at MSFC, supports the center of excellence designation by providing near-Earth space, deep space, planetary, and terrestrial environments expertise to projects as required. The Terrestrial Environment (TE) group within the AEE team maintains an extensive TE data base. Statistics and models derived from this data are applied to the design and development of new aerospace vehicles, as well as performance enhancement of operational vehicles such as the Space Shuttle. The TE is defined as the Earth's atmospheric environment extending from the surface to orbital insertion altitudes (approximately 90 km)

    Reflection Mode Diffraction Tomography

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    In the field of ultrasound diffraction tomography, a cross section of a weakly scattering object is reconstructed from measurements of the sound scattered from the insonified object. This research studies tomographic imaging algorithms that deal only with the sound that is backscattered from the object. The use of the backscattered sound provides higher resolution reconstructions due to the higher spatial frequency information about the object that is obtained from the backscatter. Unfortunately the cost of the high frequency information contained in the backscatter is the loss of low frequency information. Different approaches to compensate for this loss are discussed. An additional benefit of reflection mode tomography is that it has the advantage of requiring only 180° access to the object whereas transmission mode requires 360°. The charter of this research is to explore the effectiveness of current reflection mode diffraction tomography algorithms and to theoretically develop, as well as experimentally verify, new algorithms. Different scanning geometries with different methods of insonification are explored. Many different approaches to the analysis of the problem are taken

    A chromatin modifying enzyme, SDG8, is involved in morphological, gene expression, and epigenetic responses to mechanical stimulation

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    Thigmomorphogenesis is viewed as being a response process of acclimation to short repetitive bursts of mechanical stimulation or touch. The underlying molecular mechanisms that coordinate changes in how touch signals lead to long-term morphological changes are enigmatic. Touch responsive gene expression is rapid and transient, and no transcription factor or DNA regulatory motif has been reported that could confer a genome wide mechanical stimulus. We report here on a chromatin modifying enzyme, SDG8/ASHH2, which can regulate the expression of many touch responsive genes identified in Arabidopsis. SDG8 is required for the permissive expression of touch induced genes; and the loss of function of sdg8 perturbs the maximum levels of induction on selected touch gene targets. SDG8 is required to maintain permissive H3K4 trimethylation marks surrounding the Arabidopsis touch-inducible gene TOUCH 3 (TCH3), which encodes a calmodulin-like protein (CML12). The gene neighboring was also slightly down regulated, revealing a new target for SDG8 mediated chromatin modification. Finally, sdg8 mutants show perturbed morphological response to wind-agitated mechanical stimuli, implicating an epigenetic memory-forming process in the acclimation response of thigmomorphogenesis

    Upper Atmospheric Monitoring for Ares I-X Ascent Loads and Trajectory Evaluation on the Day-of-Launch

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    During the launch countdown of the Ares I-X test vehicle, engineers from Langley Research Center will use profiles of atmospheric density and winds in evaluating vehicle ascent loads and controllability. A schedule for the release of balloons to measure atmospheric density and winds has been developed by the Natural Environments Branch at Marshall Space Flight Center to help ensure timely evaluation of the vehicle ascent loads and controllability parameters and support a successful launch of the Ares I-X vehicle

    Dynamic Properties of Fine-Grained Coal Refuse

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    A simplified method of slope stability analysis is presented for upstream-constructed coal tailings dams subjected to earthquake shaking. The method employs a conventional method of slices approach, in which dynamic loads are represented as psuedostatic forces applied to each slice. Excess pore water pressures are estimated from cyclic triaxial tests performed on specimens of fine coal refuse. Cyclic triaxial test results are presented for fine coal refuse materials from six sites in the western Appalachian region. Measured excess pore water pressure values appear to be influenced by fine coal processing procedures, although material plasticity and grain characteristics are also important. Additional studies are ongoing

    Cross-Program Design Specification for Natural Environments (DSNE)

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    This document is derived from the former National Aeronautics and Space Administration (NASA) Constellation Program (CxP) document CxP 70023, titled The Design Specification for Natural Environments (DSNE), Revision C. The original document has been modified to represent updated Design Reference Missions (DRMs) for the NASA Exploration Systems Development (ESD) Programs
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