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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

CIP Training Manual: Collaborative Information Portal Advance Training Information for Field Test Participants

The Collaborative Information Portal (CIP) is a web-based information management and retrieval system. Its purpose is to provide users at MER (Mars Exploration Rover) mission operations with easy access to a broad range of mission data and products and contextual information such as the current operations schedule. The CIP web-server provides this content in a user customizable web-portal environment. Since CIP is still under development, only a subset of the full feature set will be available for the EDO field test. The CIP web-portal will be accessed through a standard web browser. CIP is intended to be intuitive and simple to use, however, at the training session, users will receive a one to two page reference guide, which should aid them in using CIP. Users must provide their own computers for accessing CIP during the field test. These computers should be configured with Java 1.3 and a Java 2 enabled browser. Macintosh computers should be running OS 10.1.3 or later. Classic Mac OS (OS 9) is not supported. For more information please read section 7.3 in the FIASCO Rover Science Operations Test Mission Plan. Several screen shots of the Beta Release of CIP are shown on the following pages.

Schreiner, John↗
NASA NTRS2005

Isotopic And Geochemical Investigations Of Meteorites

The primary goals of our research over the past four years are to constrain the timing of certain early planetary accretion/differentiation events, and to constrain the proportions and provenance of materials involved in these processes. This work was achieved via the analysis and interpretation of long- and short-lived isotope systems, and the study of certain trace elements. Our research targeted these goals primarily via the application of the Re-187, Os-187, Pt-190 Os-186 Tc-98 Ru-99 and Tc-99 Ru-99 isotopic systems, and the determination/modeling of abundances of the highly siderophile elements (HSE; including Re, Os, Ir, Ru, Pd, Pt, and maybe Tc). The specific events we examined include the segregation and crystallization histories of asteroidal cores, the accretion and metamorphic histories of chondrites and chondrite components, and the accretionary and differentiation histories of Mars and the Moon.

Walker, Richard J.↗
NASA NTRS2005

Climatic Versus Biotic Constraints on Carbon and Water Fluxes in Seasonally Drought-affected Ponderosa Pine Ecosystems

We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS ( 50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

Schwarz, P. A.↗
NASA NTRS2007

Highly Sideophile Element Abundance Constraints on the Nature of the Late Accretionary Histories of Earth, Moon and Mars

The highly siderophile elements (HSE) include Re, Os, Ir, Ru, Pt and Pd. These elements are initially nearly-quantitatively stripped from planetary silicate mantles during core segregation. They then may be re-enriched in mantles via continued accretion sans continued core segregation. This suite of elements and its included long-lived radiogenic isotopes systems (Re-187 (right arrow) Os-187; Pt-190 (right arrow) Os-186) can potentially be used to fingerprint the characteristics of late accreted materials. The fingerprints may ultimately be useful to constrain the prior nebular history of the dominant late accreted materials, and to compare the proportion and genesis of late accretionary materials added to the inner planets. The past ten years have seen considerable accumulation of isotopic and compositional data for HSE present in the Earth's mantle, lunar mantle and impact melt breccias, and Martian meteorites. Here we review some of these data and consider the broader implications of the compiled data.

Walker, R. J.↗
NASA NTRS2007

Processes in Early Planetesimals: Evidence from Ureilite Meteorites

Ureilites are primitive ultramafic achondrites composed largely of olivine and pigeonite, with minor augite, carbon, sulphide and metal. They represent very early material in the history of the Solar System and form a bridge between undifferentiated chondrites and fully differentiated asteroids. They show a mixture of chemical characteristics, some of which are considered to be nebula-derived (e.g. a negative correlation between Mg/Fe and Delta O-17 that resembles that of the ordinary chondrites but at lower Delta O-17 values) whereas others have been imposed by asteroidal differentiation. Carbon isotope data show a striking negative correlation of delta C-13 values with mg# in olivine. delta C-13 also correlates positively with Delta O-17, and therefore this isotopic variation was probably also nebula-derived. Thus, oxygen and carbon isotope compositions and Fe-Mg systematics of each monomict ureilite were established before differentiation processes began. Heated by decay of short-lived radioactive isotopes, the ureilite asteroid started to melt. Metal and sulphide would have melted first, forming a Fe-S eutectic liquid, which removed chalcophile elements and incompatible siderophile elements, and basaltic melts that removed Al, Ca and the LREE. Several elements show different abundances and/or correlations with Fo content in olivine, e.g. carbon shows a positive correlation in ferroan ureilites, and a weak or even negative correlation in more magnesian compositions. HSE such as Os and Ir also show different distributions, i.e. ureilites with Fo < 82 have very scattered Os and Ir concentrations, which reach high values, whereas ureilites with Fo > 82 tend to have much less scattered and overall lower Os and Ir abundances. A similar change in elemental behaviour is shown by the Fe-Mn relations in ureilitic olivines: those with Fo contents < 85 show a good negative correlation, whereas those with Fo > 85 show much greater scatter. This suggests that a major change affected the parent body at a time when melting had reached relatively magnesian bulk compositions. We consider that this event may have been a hit and run collision in which the ureilite parent body collided with a larger object. During the collision, the ureilite mantle broke up catastrophically but re-accreted in a jumbled state around the still-intact core. Mg-rich basaltic melts that were in the process of being formed at the time of break-up were retained in part as melt clasts that re-accreted to the regolith and are found in polymict ureilites.

Mittlefehldt, David W.↗
NASA NTRS2011

Planetary Protection Considerations in EVA System Design

To better constrain their origin, we have performed systematic studies of the siderophile element distribution in metal from Enstatite achondrites and iron-rich meteorites linked to Enstatite achondrites. Humayun (2010) reported 20 siderophile elements in the metal of Horse Creek, Mt. Egerton and Tucson, three iron meteorites known for their high Si content in their metal. The Horse Creek and Mt. Egerton irons have elemental patterns identical to metallic solids derived from partially molten enstatite chondrites. Tucson has an unusual siderophile element pattern that is reminiscent of IVA irons, except for the most volatile siderophiles with condensation temperatures below that of Cu (Sb, Ge, Sn) which are more depleted. The origin of Tucson metal is likely linked to an impact involving a reduced chondritic body that provided the silicates, and IVA iron. In a related study, van Acken et al. (2010) reported siderophile element abundances in metal and sulfides from aubrites, chondritic inclusions in aubrites, and other enstatite achondrites (including a separate section of Mt. Egerton). They found that aubrite metal was linked to metal in enstatite chondrites by low degree partial melting forming sulfur-rich metallic liquids. A restite origin of aubrites is not consistent with these metal compositions. The link between the metal compositions and cumulate silicates is not simple. The metal must have been incorporated from enstatite chondritic material that was assimilated by the aubrite magma. A manuscript is in preparation (van Acken et al., 2010). In a related study, van Acken et al. (2010, submitted) reported new precise Os isotope ratios and highly siderophile element abundances in Enstatite chondrites, Enstatite achondrites, Rumurutite chondrites to explore the range of nucleosynthetic variation in s-process Os. They observed nucleosynthetic anomalies, deficiencies of s-process Os, in most primitive enstatite chondrites, but showed the Rumurutite chondrites have very little expression of these anomalies. hardware from the human-occupied area may limit (although not likely eliminate) external materials in the human habitat. Definition of design-to requirements is critical to understanding technical feasibility and costs. The definition of Planetary Protection needs in relation to EVA mission and system element development cost impacts should be considered and interpreted in terms of Plausible Protection criteria. Since EVA operations will have the most direct physical interaction with the Martian surface, PP needs should be considered in the terms of mitigating hardware and operations impacts and costs.

Eppler, Dean B.↗
NASA NTRS2012

Network acceleration techniques

Splintered offloading techniques with receive batch processing are described for network acceleration. Such techniques offload specific functionality to a NIC while maintaining the bulk of the protocol processing in the host operating system ("OS"). The resulting protocol implementation allows the application to bypass the protocol processing of the received data. Such can be accomplished this by moving data from the NIC directly to the application through direct memory access ("DMA") and batch processing the receive headers in the host OS when the host OS is interrupted to perform other work. Batch processing receive headers allows the data path to be separated from the control path. Unlike operating system bypass, however, the operating system still fully manages the network resource and has relevant feedback about traffic and flows. Embodiments of the present disclosure can therefore address the challenges of networks with extreme bandwidth delay products (BWDP).

Crowley, Patricia↗
DOE OSTI2020

Dynamically adapting mechanism for translation lookaside buffer shootdowns

An operating system (OS) of a processing system having a plurality of processor cores determines a cost associated with different mechanisms for performing a translation lookaside buffer (TLB) shootdown in response to, for example, a virtual address being remapped to a new physical address, and selects a TLB shootdown mechanism to purge outdated or invalid address translations from the TLB based on the determined cost. In some embodiments, the OS selects an inter-processor interrupt (IPI) as the TLB shootdown mechanism if the cost associated with sending an IPI is less than a threshold cost. In some embodiments, the OS compares the cost of using an IPI as the TLB shootdown mechanism versus the cost of sending a hardware broadcast to all processor cores of the processing system as the shootdown mechanism and selects the shootdown mechanism having the lower cost.

42 ENGINEERING↗
DOE OSTI2020

Materials Data on Ba(POs)2 by Materials Project

Ba(OsP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. All Ba–Os bond lengths are 3.69 Å. Os2- is bonded to four equivalent Ba2+ and four equivalent P1+ atoms to form a mixture of distorted corner, edge, and face-sharing OsBa4P4 tetrahedra. All Os–P bond lengths are 2.35 Å. P1+ is bonded in a 4-coordinate geometry to four equivalent Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd(BOs)4 by Materials Project

Nd(OsB)4 is alpha Pu-derived structured and crystallizes in the tetragonal P4_2/n space group. The structure is three-dimensional. Nd2+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. There are four shorter (3.22 Å) and four longer (3.23 Å) Nd–Os bond lengths. Os2- is bonded in a 4-coordinate geometry to two equivalent Nd2+ and four equivalent B+1.50+ atoms. There are a spread of Os–B bond distances ranging from 2.14–2.19 Å. B+1.50+ is bonded in a 4-coordinate geometry to four equivalent Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si2Os by Materials Project

OsSi2 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Os8+ sites. In the first Os8+ site, Os8+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Os–Si bond distances ranging from 2.48–2.53 Å. In the second Os8+ site, Os8+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Os–Si bond distances ranging from 2.47–2.50 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 4-coordinate geometry to four Os8+ and five Si4- atoms. There are a spread of Si–Si bond distances ranging from 2.55–2.72 Å. In the second Si4- site, Si4- is bonded in a 4-coordinate geometry to four Os8+ and five Si4- atoms. There are one shorter (2.62 Å) and one longer (2.71 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(POs)2 by Materials Project

Eu(OsP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. All Eu–Os bond lengths are 3.38 Å. Os2- is bonded in a 12-coordinate geometry to four equivalent Eu2+ and four equivalent P1+ atoms. All Os–P bond lengths are 2.34 Å. P1+ is bonded in a 4-coordinate geometry to four equivalent Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu(SiOs)2 by Materials Project

PuOs2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pu4+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. All Pu–Os bond lengths are 3.18 Å. Os2- is bonded in a 4-coordinate geometry to four equivalent Pu4+ and four equivalent Si atoms. All Os–Si bond lengths are 2.40 Å. Si is bonded in a 5-coordinate geometry to four equivalent Os2- and one Si atom. The Si–Si bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H12OsN5Cl3O by Materials Project

OsN5H12OClCl2 crystallizes in the tetragonal I4mm space group. The structure is zero-dimensional and consists of four hydrochloric acid molecules and two OsN5H12OCl clusters. In each OsN5H12OCl cluster, Os8+ is bonded in an octahedral geometry to five N3- and one Cl1- atom. There is one shorter (1.75 Å) and four longer (2.14 Å) Os–N bond length. The Os–Cl bond length is 2.33 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a linear geometry to one Os8+ and one O2- atom. The N–O bond length is 1.18 Å. In the second N3- site, N3- is bonded in a trigonal non-coplanar geometry to one Os8+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.04 Å) N–H bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. O2- is bonded in a single-bond geometry to one N3- atom. Cl1- is bonded in a single-bond geometry to one Os8+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LuB2Os3 by Materials Project

LuOs3B2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Lu3+ is bonded to twelve equivalent Os1- atoms to form LuOs12 cuboctahedra that share corners with twelve equivalent LuOs12 cuboctahedra, edges with six equivalent LuOs12 cuboctahedra, edges with twelve equivalent BOs6 pentagonal pyramids, faces with two equivalent LuOs12 cuboctahedra, and faces with six equivalent BOs6 pentagonal pyramids. All Lu–Os bond lengths are 3.15 Å. Os1- is bonded in a distorted square co-planar geometry to four equivalent Lu3+ and four equivalent B atoms. All Os–B bond lengths are 2.20 Å. B is bonded to six equivalent Os1- atoms to form distorted BOs6 pentagonal pyramids that share corners with six equivalent BOs6 pentagonal pyramids, edges with six equivalent LuOs12 cuboctahedra, edges with three equivalent BOs6 pentagonal pyramids, faces with three equivalent LuOs12 cuboctahedra, and faces with two equivalent BOs6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on OsO3F2 by Materials Project

OsO3F2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of two OsO3F2 ribbons oriented in the (0, 1, 0) direction. Os8+ is bonded to three O2- and three F1- atoms to form distorted corner-sharing OsO3F3 octahedra. The corner-sharing octahedral tilt angles are 34°. All Os–O bond lengths are 1.71 Å. There are a spread of Os–F bond distances ranging from 1.91–2.20 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Os8+ atom. In the second F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Os8+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on OsCl2O by Materials Project

OsOCl2 crystallizes in the orthorhombic Immm space group. The structure is two-dimensional and consists of two OsOCl2 sheets oriented in the (0, 0, 1) direction. Os4+ is bonded to two equivalent O2- and four equivalent Cl1- atoms to form a mixture of edge and corner-sharing OsCl4O2 octahedra. The corner-sharing octahedral tilt angles are 0°. Both Os–O bond lengths are 1.86 Å. All Os–Cl bond lengths are 2.41 Å. O2- is bonded in a linear geometry to two equivalent Os4+ atoms. Cl1- is bonded in a water-like geometry to two equivalent Os4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca2Os2O7 by Materials Project

Ca2Os2O7 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to eight O2- atoms to form distorted CaO8 hexagonal bipyramids that share corners with two equivalent CaO8 hexagonal bipyramids, corners with two equivalent OsO6 octahedra, and edges with six OsO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.24–2.84 Å. In the second Ca2+ site, Ca2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.40 Å) and four longer (2.76 Å) Ca–O bond lengths. There are two inequivalent Os5+ sites. In the first Os5+ site, Os5+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with six OsO6 octahedra and edges with four equivalent CaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–42°. There is two shorter (1.92 Å) and four longer (1.96 Å) Os–O bond length. In the second Os5+ site, Os5+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with two equivalent CaO8 hexagonal bipyramids, corners with four equivalent OsO6 octahedra, and edges with two equivalent CaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There is four shorter (1.96 Å) and two longer (1.99 Å) Os–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Os5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ca2+ and two equivalent Os5+ atoms. In the third O2- site, O2- is bonded to three Ca2+ and one Os5+ atom to form a mixture of distorted edge and corner-sharing OCa3Os tetrahedra.

36 MATERIALS SCIENCE↗