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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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All sources NASA NTRS DOE OSTI

NASA NTRS1999

Spatial Resolution Determination with the Stennis Edge Target and NIIRS

Methodologies for determining the modulation transfer function (MTF) and National Imagery Interpretability Rating Scale (NIIRS) of airborne panchromatic and multispectral digital imaging cameras using the NASA Stennis Space Center (SSC) edge target have been developed. The application of NIIRS for determining the relative utility of data sets against various applications is discussed. Sampling requirements and optimal flightlines for focal plane imagers have been investigated. It is shown that with sufficient flight tilt angle, an adequate number of samples can be obtained to define the edge response accurately. The relationships between the tilt angle, Ground Sample Distance (GSD), and the number of samples are discussed. Sample results using commercially available data and the NASA SSC edge target are presented and compared to theoretical results.

Ryan, Robert↗

NASA NTRS2006

Edge Response and NIIRS Estimates for Commercial Remote Sensing Satellites

Spatial resolution of panchromatic imagery from commercial remote sensing satellites was characterized based on edge response measurements using edge targets and the tilted-edge technique. Relative Edge Response (RER) was estimated as a geometric mean of normalized edge response differences measured in two directions of image pixels at points distanced from the edge by -0.5 and 0.5 of ground sample distance. RER is one of the engineering parameters used in the General Image Quality Equation to provide predictions of imaging system performance expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS). By assuming a plausible range of signal-to-noise ratio and assessing the effects of Modulation Transfer Function compensation, the NIIRS estimates were made and then compared with vendor-provided values and evaluations conducted by the National Geospatial-Intelligence Agency.

Blonski, Slawomir↗

DOE OSTI2021

Spin-liquid behavior of the three-dimensional magnetic system Ba 3 NiIr 2 O 9 with S = 1

The quantum spin liquid (QSL) is an exotic phase of magnetic materials where the spins continue to fluctuate without any symmetry breaking down to zero temperature. Among the handful reports of QSL with spin S ≥ 1, examples with magnetic ions on a three-dimensional (3D) magnetic lattice are extremely rare since both larger spin and higher dimension tend to suppress quantum fluctuations. In this work, we offer a new strategy to achieve 3D QSL with high spin by utilizing two types of transition metal ions; both are magnetically active but located at crystallographically inequivalent positions. Furthermore, we design a 3D magnetic system Ba 3 NiIr 2 O 9 consisting of interconnected corner-shared NiO 6 octahedra and face-shared Ir 2 O 9 dimer, both having triangular arrangements in a-b plane. X-ray absorption spectroscopy measurements confirm the presence of Ni 2+ (S = 1). Furthermore, our detailed thermodynamic and magnetic measurements reveal that this compound is a realization of gapless QSL state down to at least 100 mK. Ab initio calculations find a strong magnetic exchange between Ir and Ni sublattices and in-plane antiferromagnetic coupling between the dimers, resulting in dynamically fluctuating magnetic moments.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2020

Materials Data on NiIr by Materials Project

IrNi crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Ir sites. In the first Ir site, Ir is bonded to six equivalent Ir and six equivalent Ni atoms to form distorted IrNi6Ir6 cuboctahedra that share corners with twelve IrNi6Ir6 cuboctahedra, edges with twelve IrNi6Ir6 cuboctahedra, edges with twelve equivalent NiNi6Ir6 cuboctahedra, faces with six equivalent IrNi6Ir6 cuboctahedra, and faces with twelve equivalent NiNi6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.68 Å. All Ir–Ni bond lengths are 2.60 Å. In the second Ir site, Ir is bonded to six equivalent Ir and six Ni atoms to form distorted IrNi6Ir6 cuboctahedra that share corners with five equivalent NiNi10Ir6 cuboctahedra, corners with twelve IrNi6Ir6 cuboctahedra, edges with ten NiNi6Ir6 cuboctahedra, edges with twelve IrNi6Ir6 cuboctahedra, faces with six equivalent IrNi6Ir6 cuboctahedra, and faces with fifteen NiNi6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.68 Å. All Ir–Ni bond lengths are 2.60 Å. In the third Ir site, Ir is bonded to six equivalent Ir and six Ni atoms to form distorted IrNi6Ir6 cuboctahedra that share corners with five equivalent NiNi10Ir6 cuboctahedra, corners with twelve IrNi6Ir6 cuboctahedra, edges with ten NiNi6Ir6 cuboctahedra, edges with twelve IrNi6Ir6 cuboctahedra, faces with six equivalent IrNi6Ir6 cuboctahedra, and faces with fifteen NiNi6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.68 Å. All Ir–Ni bond lengths are 2.60 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to six Ir and six equivalent Ni atoms to form distorted NiNi6Ir6 cuboctahedra that share corners with twelve NiNi6Ir6 cuboctahedra, edges with twelve IrNi6Ir6 cuboctahedra, edges with twelve NiNi6Ir6 cuboctahedra, faces with six equivalent NiNi6Ir6 cuboctahedra, and faces with twelve IrNi6Ir6 cuboctahedra. All Ni–Ni bond lengths are 2.68 Å. In the second Ni site, Ni is bonded to six Ir and ten equivalent Ni atoms to form distorted NiNi10Ir6 cuboctahedra that share corners with ten IrNi6Ir6 cuboctahedra, corners with twelve NiNi6Ir6 cuboctahedra, edges with eight IrNi6Ir6 cuboctahedra, edges with sixteen NiNi6Ir6 cuboctahedra, faces with sixteen equivalent NiNi10Ir6 cuboctahedra, and faces with eighteen IrNi6Ir6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.68–5.35 Å.

36 MATERIALS SCIENCE↗

NASA NTRS2003

IKONOS Spatial Resolution and Image Interpretability Characterization

This paper contains research from five individual projects to characterize the spatial performance of the IKONOS commercial imaging sensor. The end result of the projects is determination of the spatial image quality of IKONOS data prodicts in terms of the National Imagery Interpretability Rating Scale (NIIRS), the system Modulation Transfer Function (MTF), the system stability over the first year, the characteristics of the Space Imaging MTF Compensation (MTFC) procedure, and the application-specific capabilities of IKONOS imagery. Both panchromatic and multispectral imagery were evaluated. Major conclusions of this work are that the system was stable im imaging performance during the first year of operation, tha its MTF meets the specification for the NASA Scientific Data Purchase program, that the initial MTFC processing appears to be transposed in the in-track and the cross-track directions, that the MTFC results in a noise amplification of 2x to 4x in addition to sharpening the imagery, and that IKONOS panchromatic imagery achieves an average NIIRS rating of 4.5.

Ryan, Robert↗