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  • 2000-2004  (33)
  • 1930-1934  (2)
  • 1
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    In:  Geological Society Special Publication 207: 131-150.
    Publication Date: 2003-01-01
    Description: The margin between Cote d'Ivoire and the Niger Delta is a region with a common structural history, this being reflected in similarities in the stratigraphic response and play fairways identified across the region. There has been significant exploration on the narrow shelf characterizing the margin, resulting in a series of modest oil and gas discoveries. It is shown in this paper that many of the aspects of the plays in the unexplored deep-water regions of the margin are considerably more favourable to the development of giant fields than those on the shelf. This play-fairway review is based on the integration of existing publications with focused studies of multiclient 3-D seismic data over a number of areas. Play fairways are classified by seismic sequence and trap type, with an analysis of each undertaken. The most attractive deep-water play types are: (1) anticlinal traps involving late syn-transform (Apto-Albian) and early post-transform (Late Cretaceous) reservoirs, (2) combination traps involving ponded turbidites on the shoreward flanks of these highs, and (3) stratigraphic traps associated with large Late Cretaceous submarine fan complexes. The anticlinal play is associated with the terminations of the St Paul and Romanche fracture zones, with the more recent structuring generally associated with the latter. 3-D imaging and amplitude mapping is critical to prospect delineation, particularly for the combination and stratigraphic plays. Active kitchens are evidenced involving Early and Late Cretaceous source rocks in the Cote d'Ivoire and western Ghana to Nigeria segments of the region, which are consequently upgraded. Considerable volumetric potential is indicated that promises to make the region one of significant new exploration activity in coming years.
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  • 2
    Publication Date: 2019-07-10
    Description: This report compares seven double-plate penetration predictor equations for accuracy and effectiveness of a shield design. Three of the seven are the Johnson Space Center original, modified, and new Cour-Palais equations. The other four are the Nysmith, Lundeberg-Stern-Bristow, Burch, and Wilkinson equations. These equations, except the Wilkinson equation, were derived from test results, with the velocities ranging up to 8 km/sec. Spreadsheet software calculated the projectile diameters for various velocities for the different equations. The results were plotted on projectile diameter versus velocity graphs for the expected orbital debris impact velocities ranging from 2 to 15 km/sec. The new Cour-Palais double-plate penetration equation was compared to the modified Cour-Palais single-plate penetration equation. Then the predictions from each of the seven double-plate penetration equations were compared to each other for a chosen shield design. Finally, these results from the equations were compared with test results performed at the NASA Marshall Space Flight Center. Because the different equations predict a wide range of projectile diameters at any given velocity, it is very difficult to choose the "right" prediction equation for shield configurations other than those exactly used in the equations' development. Although developed for various materials, the penetration equations alone cannot be relied upon to accurately predict the effectiveness of a shield without using hypervelocity impact tests to verify the design.
    Keywords: Structural Mechanics
    Type: NASA/TM-2000-209907 , NAS 1.15:209907 , M-962
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: In response to a NASA request, the National Space Propulsion Synergy Team (SPST) team agreed to provide technical and programmatic support to NASA in formulating a Spaceliner 100 Technology Program. The SPST offered a broad cross-section of expertise and experience. Its membership consists of senior level, volunteer representatives from across government, industry, and academia. The purpose of this paper is to provide a summary of the SPST support of SL100, which culminated in a propulsion technologies assessment and prioritization workshop conducted at MSFC. The results of this workshop and the follow-up analysis are part of this report. Also included, is a review of some "lessons learned" that were solicited from the workshop participants.
    Keywords: Space Transportation and Safety
    Type: AIAA Paper 2000-3603 , Joint Propulsion; 17-19 Jul. 2000; Huntsville, AL; United States
    Format: application/pdf
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  • 4
    Publication Date: 2019-07-13
    Description: Following the breakup of the Space Shuttle Columbia during reentry a NASA/Contractor investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System elements by impact of External Tank insulating foam projectiles. The authors formed a working subgroup within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the Orbiter's tiles and of the Tank's foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working subgroups who performed tests on these items for this purpose. Two- and three-dimensional models of the tiles were constructed, including the glass outer layer, the main body of LI-900 insulation, the densified lower layer of LI-900, the Nomex felt mounting layer, and the Aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with Southwest Research Institute foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger foam projectiles on the examples of tile systems used on the Orbiter. Results for impacts on the main landing gear door are presented in this paper, including effects of impacts at several angles, and of rapidly rotating projectiles. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rotation up to 17 rps failed to increase the damage for the two cases considered. This does not rule out other cases in which the rotational energy might lead to an increase in tile damage, but suggests that in most cases rotation will not be an important factor.
    Keywords: Structural Mechanics
    Type: 42nd AIAA Aerospace Sciences Meeting and Exhibit; 5-8 Jan. 2004; Reno, NV; United States
    Format: application/pdf
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  • 5
    Publication Date: 2019-07-18
    Description: Following the breakup of the Space Shuttle Columbia during reentry a NASA-wide investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System (TPS) elements by impact of External Tank insulating foam projectiles. Our team was to apply rigorous, physics-based analysis techniques to help determine parameters of interest for an experimental test program, utilize validated codes to investigate the full range of impact scenarios, and use analysis derived models to predict aero-thermal-structural responses to entry conditions. We were to operate on a non-interference basis with the j Team, and were to supply significant findings to that team and to the Orbiter Vehicle Engineering Working Group, being responsive to any solicitations for support from these entities. The authors formed a working sub-group within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the LI-900 TPS tiles and of the BX-250 foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working sub-groups who performed tests on these items for this purpose. Two- and three- dimensional models of the tiles were constructed, including the glass outer layer, the densified lower layer of LI-900 insulation, the Nomex felt Strain Isolation Pad (SIP) mounting layer, and the underlying aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with the Southwest Research Institute (SwRI) foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger ET foam projectiles on the TPS tile systems used on the wings of the orbiter. Tiles used on the Wing Acreage, the Main Landing Gear Door, and the Carrier Panels near the front edge of the wing were modeled. Foam impacts shot for the CAB investigation were modeled, as well as impacts at larger angles, including rapid rotation of the projectile, and with varying foam properties. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rapid (17 rps) rotation failed to increase the damage for the two cases considered. This does not rule out other cases in which the rotational energy might lead to an increase in tile damage, but suggests that in most cases rotation will not be an important factor. Similar models will be applied for other impacting materials, other velocities, and other geometries as part of the Return to Flight process.
    Keywords: Spacecraft Design, Testing and Performance
    Type: 42nd AIAA Aerospace Sciences Meeting and Exhibit; 5-8 Jan. 2004; Reno, NV; United States
    Format: text
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  • 6
    Publication Date: 2004-07-01
    Print ISSN: 0959-3780
    Electronic ISSN: 1872-9495
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Elsevier
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  • 7
    Publication Date: 2002-07-01
    Print ISSN: 0959-3780
    Electronic ISSN: 1872-9495
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Elsevier
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  • 8
    Publication Date: 2004-06-01
    Description: Inclusion in the diet of concentrations of vitamin E and selenium (Se) above requirement is associated with variable improvements in animal performance and immune function. At the cellular and molecular level, research in the last decade has produced a clearer understanding of the mechanisms underlying the multiple functions of vitamin E and Se and it is apparent that these functions extend beyond antioxidant protection. This paper reviews recent research relating to the functionality of vitamin E and Se in relation to the ewe and her lambs and attempts to relate this understanding to the whole animal level. Important aspects of this improved understanding are descriptions of three groups of seleno-proteins and the appreciation that there is a hierarchy in both the distribution of selenium between tissues and in the synthesis of different enzymes within tissues. In addition, there is diversity in the effects of vitamin E and Se derivatives on immune cell function. Given this heterogeneity in function it is not surprising that published responses for the production and health of ewes and lambs to supplementary vitamin E and selenium are variable and not always positive. Coupled with information on factors influencing variability in supply of vitamin E and Se from fresh and conserved forages and concentrate supplements, this review highlights the need for greater awareness of the importance of adequate supplementation of ewe and lamb diets with vitamin E and Se.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
    Publication Date: 2003-01-01
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
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  • 10
    Publication Date: 2000-11-01
    Print ISSN: 0044-0604
    Electronic ISSN: 2041-4811
    Topics: Geosciences
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