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  • 1
    Publication Date: 2019-07-13
    Description: Engineers in the Entry Systems and Technology Division at NASA Ames Research Center developed a fully instrumented, small atmospheric entry probe called SPRITE (Small Probe Reentry Investigation for TPS Engineering). SPRITE, conceived as a flight test bed for thermal protection materials, was tested at full scale in an arc-jet facility so that the aerothermal environments the probe experiences over portions of its flight trajectory and in the arc-jet are similar. This ground-to-flight traceability enhances the ability of mission designers to evaluate margins needed in the design of thermal protection systems (TPS) of larger scale atmospheric entry vehicles. SPRITE is a 14-inch diameter, 45 deg. sphere-cone with a conical aftbody and designed for testing in the NASA Ames Aerodynamic Heating Facility (AHF). The probe is a two-part aluminum shell with PICA (phenolic impregnated carbon ablator) bonded on the forebody and LI-2200 (Shuttle tile material) bonded to the aftbody. Plugs with embedded thermocouples, similar to those installed in the heat shield of the Mars Science Laboratory (MSL), and a number of distributed sensors are integrated into the design. The data from these sensors are fed to an innovative, custom-designed data acquisition system also integrated with the test article. Two identical SPRITE models were built and successfully tested in late 2010-early 2011, and the concept is currently being modified to enable testing of conformable and/or flexible materials.
    Keywords: Spacecraft Design, Testing and Performance
    Type: ARC-E-DAA-TN4730 , AFOSR/NASA/Sandia Ablation Workshop; 28 Feb. - 1 Mar. 2012; Lexington, KY; United States
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  • 2
    Publication Date: 2019-07-12
    Description: This report describes an integrated system for Multi-mission System Analysis for Planetary Entry (M-SAPE). The system in its current form is capable of performing system analysis and design for an Earth entry vehicle suitable for sample return missions. The system includes geometry, mass sizing, impact analysis, structural analysis, flight mechanics, TPS, and a web portal for user access. The report includes details of M-SAPE modules and provides sample results. Current M-SAPE vehicle design concept is based on Mars sample return (MSR) Earth entry vehicle design, which is driven by minimizing risk associated with sample containment (no parachute and passive aerodynamic stability). By M-SAPE exploiting a common design concept, any sample return mission, particularly MSR, will benefit from significant risk and development cost reductions. The design provides a platform by which technologies and design elements can be evaluated rapidly prior to any costly investment commitment.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM2014-218507 , L-20440 , NF1676L-19269
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  • 3
    Publication Date: 2019-07-13
    Description: We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO science run and the second and third Virgo science runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to 2,254 h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range of projected semimajor axes of the orbit from 0.6 10(exp 3) ls to 6,500 ls assuming the orbit of the binary is circular. While no plausible candidate gravitational wave events survive the pipeline, upper limits are set on the analyzed data. The most sensitive 95% confidence upper limit obtained on gravitational wave strain is 2.3 10(exp 24) at 217 Hz, assuming the source waves are circularly polarized. Although this search has been optimized for circular binary orbits, the upper limits obtained remain valid for orbital eccentricities as large as 0.9. In addition, upper limits are placed on continuous gravitational wave emission from the low-mass x-ray binary Scorpius X-1 between 20 Hz and 57.25 Hz.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN22620 , Physical Review D (ISSN 0031-899X) (e-ISSN 1536-6065); 90; 6; 062010
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  • 4
    Publication Date: 2019-08-13
    Description: No abstract available
    Keywords: Spacecraft Design, Testing and Performance
    Type: ARC-E-DAA-TN4845 , 5th Ablation Workshop; Feb 28, 2012 - Mar 01, 2012; Lexington, KY; United States
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1983-03-04
    Description: The mutant mouse pearl, characterized by its hypopigmentation, has a specific functional defect in a sensory system--the retina. The intact pearl mouse has reduced sensitivity in the dark-adapted condition. Normal sensitivity is restored by isolation and superfusion of the retina with bicarbonate-buffered Ringer solution, suggesting that the retinal expression of the pearl mutation depends on a diffusible substance. The pearl phenotype is described as a possible model for human congenital stationary night blindness.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Balkema, G W -- Mangini, N J -- Pinto, L H -- R01EY02536/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1983 Mar 4;219(4588):1085-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6600521" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Dark Adaptation ; *Disease Models, Animal ; Mice ; Mice, Mutant Strains/*physiology ; Night Blindness/*genetics/physiopathology ; Retina/physiopathology ; Vision, Ocular/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 1984-10-01
    Description: The mineralogy and composition of sediments and manganese micronodules from the northern and central sectors of the Peru Basin are discussed. Because of the proximity of the basin to the Carbonate Compensation Depth (C.C.D.), surface sediments vary between calcareous oozes and siliceous muds. Besides biogenic components clay minerals are important. By far the most abundant clay mineral is smectite which is thought to be of diagenetic origin. On a carbonate-free basis, the surface sediments are rather uniform in composition throughout the basin and are similar in composition to those of the equatorial Pacific. Sedimentation rates for the uppermost core sections are in the range of 3 to 5 mm/ 1000 yr. Micronodule compositions show significant variations related to the size class of the micronodules and the depth of occurrence within the sediment column. In general, the chemistry of the micronodules can be explained by the reductive mobilization of Mn within the sediment column and by oxic diagenetic reactions between ferromanganese hydroxides and biogenic opal. The dominant mineral phase is todorokite.Краткое содержаниеОписана минералогич еский и химический со став седиментов и марганц евых желваков северной и центральн ой части перуанского бассейна. Покрывные седименты состоят, в зависимост и от уровня линии карб онатного равновесия (C. C. D.) из карбо натов, или силикатов. Наряду с биогенными компоне нтами здесь важную роль играют и глинистые минералы (с мектит, иллит). Наиболе е часто встречаются диагене тически образовавшийся смек тит. У основания, где от сутствуют карбонаты, химически й состав отложений очень пост оянен и его можно срав нить с составом осадочных п ород центральной части Тихого океана. С помощью изотопа тори я 230 удалось установить, что скорость отложения д ля верхних слоев седи ментов составляет 3–5 мм/1000 лет. Марганцевые желваки проявляют в осадочно й колонке различный химизм в за висимости от глубины их залеган ия и гранулометричес кого состава. Отмечаются п роцессы вторичной их мобилиз ации при восстановит ельных условиях среды в осад очной колонке, а также диагенетичес кие реакции между гид роокисями железа и марганца и би огенным опалом известного хи мического состава в микрожелваках марга нца. Господствующей мине ральной фазой являет ся тодорокит.ZusammenfassungMineralogie und chemische Zusammensetzung von Sedimenten und Manganmikroknollen aus dem nördlichen und zentralen Teil des Peru-Beckens werden beschrieben. Die Oberflächensedimente bestehen je nach der Lage zur Karbonatkompensationstiefe (C.C.D.) aus karbonatischen bzw. kieseligen Ablagerungen. Neben den biogenen Komponenten sind Tonmineralien (Smektit, Illit) von Bedeutung. Das häufigste Tonmineral ist diagenetisch gebildeter Smektit. Auf karbonatfreier Basis ist die chemische Zusammensetzung der Sedimente sehr einheitlich, vergleichbar mit dem Chemismus zentralpazifischer Sedimente.230Th-Datierungen ergeben eine Sedimentationsrate von 3–5 mm/1000 a für die obersten Sedimentschichten. In Abhängigkeit von der Korngrößenklasse und der Tiefe in der Sedimentsäule zeigen die Manganmikroknollen große Schwankungen im Chemismus. Remobilisationsprozesse unter reduzierenden Bedingungen in der Sedimentsäule sowie die diagenetischen Reaktionen zwischen Fe-Mn-Hydroxiden und biogenem Opal bestimmen die chemische Zusammensetzung der Manganmikroknollen. Die vorherrschende Mineralphase ist Todorokit.RésuméCette note décrit la minéralogie et la composition des sédiments et des nodules polymétalliques de la partie septentrionale et centrale du bassin de Perou. Les sédiments de surface consistent en dépôts calcaires ou siliceux selon leur situation par rapport à la profondeur de compensation des carbonates (C. C. D.). A côté des composants biogènes, des minéraux argileux (smectites, illites) sont présents en quantité importante. Le minéral argileux le plus fréquent est une smectite diagenétique. La composition chimique de la fraction non carbonatée des sédiments est uniforme, comparable au chimisme de ceux du Pacifique central. Dans les couches les plus élevées, la vitesse de sédimentation, basée sur des datations par230Th, est de 3 à 5 mm/1000 ans. Le chimisme des micronodules polymétalliques est très variable et dépend de leur profondeur dans le sédiment et de leur dimension. Le chimisme est déterminé par des processus de remobilisation en conditions réductrices dans la colonne sêdimentaire, ainsi que par des réactions diagénétiques entre les hydroxydes de Fe-Mn et l'opale biogène. Le minéral dominant est la todorokite. ©1984 Ferdinand Enke Verlag Stuttgart
    Print ISSN: 1437-3254
    Electronic ISSN: 1437-3262
    Topics: Geosciences
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  • 7
    Publication Date: 2013-04-19
    Description: We present an update (COMNISPA II) of a precisely dated, high-resolution speleothem 18 O record from the Austrian Alps. COMNISPA II consists of five stalagmites from Spannagel Cave, which have comparable 18 O values within periods of simultaneous growth and show similar 18 O variations on centennial to millennial timescales. This allows combining the five stalagmites to one composite record using a newly developed statistical approach. The COMNISPA II stack differs slightly from the previous version, but is better constrained because of additional stalagmites used for the reconstruction and a more objective method used for constructing the composite record. Furthermore, the record now covers the last 11 ka and shows variations in 18 O values by about 2. As previously shown, these variations compare well with other records in central Europe and the North Atlantic, and thus reflect a large-scale climate evolution.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 8
    Publication Date: 2012-11-23
    Description: Here we present the first high-resolution 18 O record of a stalagmite from western Cuba. The record reflects precipitation variability in the northwestern Caribbean during the last 1.3 ka and exhibits a correlation to the Atlantic Multidecadal Oscillation (AMO). This suggests a relationship between Caribbean rainfall intensity and North Atlantic sea-surface temperature (SST) anomalies. A potential mechanism for this relationship may be the strength of the Thermohaline Circulation (THC). For a weaker THC, lower SSTs in the North Atlantic possibly lead to a southward shift of the Intertropical Convergence Zone and drier conditions in Cuba. Thus, this Cuban stalagmite records drier conditions during cold phases in the North Atlantic such as the ‘Little Ice Age’. This study contributes to the understanding of teleconnections between North Atlantic SSTs and northern Caribbean climate variability during the past 1.3 ka.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 9
    Publication Date: 2014-08-01
    Description: We report fossil coral records from the Seychelles comprising individual time slices of 14–20 sclerochronological years between 2 and 6.2 kyr BP to reconstruct changes in the seasonal cycle of western Indian Ocean sea surface temperature (SST) compared to the present (1990–2003). These reconstructions allowed us to link changes in the SST bimodality to orbital changes, which were causing a reorganization of the seasonal insolation pattern. Our results reveal the lowest seasonal SST range in the Mid-Holocene (6.2–5.2 kyr BP) and around 2 kyr BP, while the highest range is observed around 4.6 kyr BP and between 1990 and 2003. The season of maximum temperature shifts from austral spring (September to November) to austral autumn (March to May), following changes in seasonal insolation over the past 6 kyr. However, the changes in SST bimodality do not linearly follow the insolation seasonality. For example, the 5.2 and 6.2 kyr BP corals show only subtle SST differences in austral spring and autumn. We use paleoclimate simulations of a fully coupled atmosphere–ocean general circulation model to compare with proxy data for the Mid-Holocene around 6 kyr BP. The model results show that in the Mid-Holocene the austral winter and spring seasons in the western Indian Ocean were warmer while austral summer was cooler. This is qualitatively consistent with the coral data from 6.2 to 5.2 kyr BP, which shows a similar reduction in the seasonal amplitude compared to the present day. However, the pattern of the seasonal SST cycle in the model appears to follow the changes in insolation more directly than indicated by the corals. Our results highlight the importance of ocean–atmosphere interactions for Indian Ocean SST seasonality throughout the Holocene. In order to understand Holocene climate variability in the countries surrounding the Indian Ocean, we need a much more comprehensive analysis of seasonally resolved archives from the tropical Indian Ocean. Insolation data alone only provides an incomplete picture. ©2014 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0930-7575
    Electronic ISSN: 1432-0894
    Topics: Geosciences , Physics
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  • 10
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    PANGAEA
    In:  Supplement to: Krishnaswami, Seth; Mangini, Augusto; Thomas, J H; Sharma, P; Cochran, J Kirk; Turekian, Karl K; Parker, P D (1982): 10Be and Th isotopes in manganese nodules and adjacent sediments: Nodule growth histories and nuclide behavior. Earth and Planetary Science Letters, 59(2), 217-234, https://doi.org/10.1016/0012-821X(82)90127-3
    Publication Date: 2020-01-17
    Description: The usefulness of cosmogenic beryllium-10 (half life = 2.5 Ma) for studying the rates of accumulation of ferromanganese nodules is reported based on its measured depth distribution in the top 20 mm of these deposits. Accumulation rates have been obtained in the range of 1 to 4 mm/Ma, which are in good agreement with rates determined using the 230Th method on the same nodules. The use of 10Be offers promise in extending the dating to the outer few cm of the nodules. This contrasts with conventional methods using 230Th and 231Pa isotopes which, due to their comparatively short half lives, are limited to a few mm at the surface of the nodules. Detailed studies of 10Be in the manganese deposits coupled with other trace element analyses should prove valuable in understanding the processes of formation of these deposits and the chronology of events recorded by them.
    Type: Dataset
    Format: application/zip, 2 datasets
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