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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Spin-orbit coupling controlled ground state in Sr 2 ScOsO 6

In this paper, we report neutron scattering experiments which reveal a large spin gap in the magnetic excitation spectrum of weakly-monoclinic double perovskite Sr 2 ScOsO 6 . The spin gap is demonstrative of appreciable spin-orbit-induced anisotropy, despite nominally orbitally-quenched 5d 3 Os 5+ ions. The system is successfully modeled including nearest neighbor interactions in a Heisenberg Hamiltonian with exchange anisotropy. We find that the presence of the spin-orbit-induced anisotropy is essential for the realization of the type I antiferromagnetic ground state. Finally, this demonstrates that physics beyond the LS or JJ coupling limits plays an active role in determining the collective properties of 4d 3 and 5d 3 systems and that theoretical treatments must include spin-orbit coupling.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Spin-orbit coupling controlled ground states in the double perovskite iridates $\textit{A}_2\textit{B}$IrO$_6$ ($\textit{A}$ = Ba, Sr; $\textit{B}$ = Lu, Sc)

Iridates with the 5$d^4$ electronic configuration have attracted recent interest due to reports of magnetically ordered ground states despite longstanding expectations that their strong spin-orbit coupling would generate a $\textit{J}$ = 0 electronic ground state for each Ir 5+ ion. The major focus of prior research has been on the double perovskite iridates Ba 2 YIrO 6 and Sr 2 YIrO 6 , where the nature of the ground states (i.e., ordered vs nonmagnetic) is still controversial. Here, in this work, we present neutron powder diffraction, high-energy-resolution fluorescence-detected x-ray absorption spectroscopy (HERFD-XAS), resonant inelastic x-ray scattering (RIXS), magnetic susceptibility, and muon spin relaxation data on the related double perovskite iridates Ba 2 LuIrO 6 , Sr 2 LuIrO 6 , Ba 2 ScIrO 6 , and Sr 2 ScIrO 6 that enable us to gain a general understanding of the electronic and magnetic properties for this family of materials. Our HERFD-XAS and RIXS measurements establish $\textit{J}$ = 0 electronic ground states for the Ir 5+ ions in all cases, with similar values for Hund's coupling $J_H$ and the spin-orbit coupling constant $λ_{\text{SOC}}$. Our bulk susceptibility and muon spin relaxation data find no evidence for long-range magnetic order or spin freezing, but they do exhibit weak magnetic signals that are consistent with extrinsic local moments. Our results indicate that the large $λ_{\text{SOC}}$ is the key driving force behind the electronic and magnetic ground states realized in the $5d^4$ double perovskite iridates, which agrees well with conventional wisdom.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1973

Multispectral signatures in relation to ground control signatures using nested sampling approach

The author has identified the following signficant results. An experiment was conducted to evaluate the feasibility of using ERTS-1 MSS imagery for spot transmission measurements on selected sites. Using the 15-unit gray scale on the 70 mm positive imagery as the base of comparison, a correlation was made between the transmittance measured at each site on the imagery and the radiance values (counts) recorded on CCT tape by the spacecraft over the same sites. The imagery was enlarged by a 750-watt projector and focused on a white cardboard screen 6 meters from the screen. Observations were made on 30 sub-sites which were pre-selected for their differing image brightness and total area; all are dried pond beds. Observations were also made on average gray backgrounds and a small lake. There was a very good correlation between the density values obtained from projected imagery and radiance values received by the detector on the spacecraft. A shorter experiment time and closer integration of gray scale and site readings would avoid the variation in lamp intensities that occurred.

Lyon, R. J. P.↗
NASA NTRS1974

Multispectral signatures in relation to ground control signature using nested sampling approach

The author has identified the following significant results. Principal effort has been on the development of a PDP-10 software package to read the CCT tapes more cheaply and rapidly. This is 90% completed and debugged. A shade print example of Treasure Island is provided. Stanford area was overflown with the U-2 as an add-on photographic mission to help fill in record-gaps in ERTS-1 overpass which was clouded out.

Lyon, R. J. P.↗
NASA NTRS1981

Onboard utilization of ground control points for image correction. Volume 2: Analysis and simulation results

An approach to remote sensing that meets future mission requirements was investigated. The deterministic acquisition of data and the rapid correction of data for radiometric effects and image distortions are the most critical limitations of remote sensing. The following topics are discussed: onboard image correction systems, GCP navigation system simulation, GCP analysis, and image correction analysis measurement.

Source record↗
NASA NTRS1982

Electrophoresis tests on STS-3 and ground control experiments - A basis for future biological sample selections

Static zone electrophoresis is an electrokinetic method of separating macromolecules and small particles. However, its application for the isolation of biological cells and concentrated protein solutions is limited by sedimentation and convection. Microgravity eliminates or reduces sedimentation, floatation, and density-driven convection arising from either Joule heating or concentration differences. The advantages of such an environment were first demonstrated in space during the Apollo 14 and 16 missions. In 1975 the Electrophoresis Technology Experiment (MA-011) was conducted during the Apollo-Soyuz Test Project flight. In 1979 a project was initiated to repeat the separations of human kidney cells. One of the major objectives of the Electrophoresis Equipment Verification Tests (EEVT) on STS-3 was to repeat and thereby validate the first successful electrophoretic separation of human kidney cells. Attention is given to the EEVT apparatus, the preflight electrophoresis, and inflight operational results.

Morrison, D. R.↗
NASA NTRS1983

Evaluation of LANDSAT-4 TM and MSS ground segment geometry performance without ground control

The along-line one dimensional FFT algorithm was successfully used to test band-to-band, swath-to-swath, and inter-swath registration of a Washington, D.C. scene. Analysis of the tabulated and plotted results of the MSS and TM P-data shows that a slow spacecraft roll condition of under one hertz exists in this scene. Characteristics of the data for both instruments are listed.

Source record↗
NASA NTRS1983

Evaluation of LANDSAT-4 TM and MSS ground geometry performance without ground control

Techniques and software developed to characterize the Washington, D.C. scene were improved and are being systematically applied to an Imperial Valley, CA scene. Digital elevation files are being acquired. One hundred seventy-two tiepoints were located in the Imperial Valley scene. They were digitized from USGS maps to determine their lat-long coordinates. A least squares fit is currently being performed between line-sample image data and the lat-long positions of the tiepoints. Thematic mapper scanner sweeps were determined for the Imperial Valley P-data. VICAR jobs are currently under way to analyze sample-direction offsets between sweeps in the data, as well as band to band registration offsets. Tiepoint location is about to begin in the Harrisburg, PA scene.

Bryant, N. A.↗
NASA NTRS1991

Networked simulation for team training of Space Station astronauts, ground controllers, and scientists - A training and development environment

The purpose of this paper is to describe plans for the Space Station Training Facility (SSTF) which has been designed to meet the envisioned training needs for Space Station Freedom. To meet these needs, the SSTF will integrate networked simulators with real-world systems in five training modes: Stand-Alone, Combined, Joint-Combined, Integrated, and Joint-Integrated. This paper describes the five training modes within the context of three training scenaries. In addition, this paper describes an authoring system which will support the rapid integration of new real-world system changes in the Space Station Freedom Program.

Hajare, Ankur R.↗