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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Nuclear Spectroscopy for the Exploration of Mars and Beyond

Nuclear spectroscopy will continue to play a critical role in planetary exploration in the next decade, including searching for habitable environments and biosignatures, identifying ideal targets for in-situ resource utilization, and continuing its track record in understanding planetary evolution. Nuclear spectroscopy is the only technique that provides bulk geochemical abundance at depth, at a range of spatial scales depending on platform.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Torque control system

System stabilizes aximuth of gondolas which are carried by high-altitude balloons as platforms for tracking telescopes. When telescopes must be constantly aimed at specific targets, control system stabilizes gondola to within 5 arc-seconds.

Studenick, D. K.↗
NASA NTRS1977

GEOS-2 refraction program summary document

Data from an extensive array of collocated instrumentation at the Wallops Island test facility were intercompared in order to (1) determine the practical achievable accuracy limitations of various tropospheric and ionospheric correction techniques; (2) examine the theoretical bases and derivation of improved refraction correction techniques; and (3) estimate internal systematic and random error levels of the various tracking stations. The GEOS 2 satellite was used as the target vehicle. Data were obtained regarding the ionospheric and tropospheric propagation errors, the theoretical and data analysis of which was documented in some 30 separate reports over the last 6 years. An overview of project results is presented.

Mallinckrodt, A. J.↗
NASA NTRS1979

Analysis of GEOS-3 altimeter data and extraction of ocean wave height and dominant wavelength

When the amplitude and timing biases are removed from the GEOS-3 Sample and Hold (S&H) gates, the mean return waveforms can be excellently fitted with a theoretical template which represents the convolution of: (1) the radar point target response; (2) the range noise (jitter) in the altimeter tracking loop; (3) the sea surface height distribution; and (4) the antenna pattern as a function of the range to mean sea level. Several techniques of varying complexity to remove the effect of the tracking loop jitter in computing the wave height are considered. They include: (1) realigning the S&H gates to their actual positions with respect to mean sea level before averaging; (2) using the observed standard deviation on the altitude measurement to remove the integrated effect of the tracking loop jitter, and (3) using a look-up table to correct for the expected value of range noise. Analysis of skewness in the GEOS return waveform demonstrates the potential of a satellite radar altimeter to determine the dominant wavelength of ocean waves.

Walsh, E. J.↗
NASA NTRS1987

A post-processing system for automated rectification and registration of spaceborne SAR imagery

An automated post-processing system has been developed that interfaces with the raw image output of the operational digital SAR correlator. This system is designed for optimal efficiency by using advanced signal processing hardware and an algorithm that requires no operator interaction, such as the determination of ground control points. The standard output is a geocoded image product (i.e. resampled to a specified map projection). The system is capable of producing multiframe mosaics for large-scale mapping by combining images in both the along-track direction and adjacent cross-track swaths from ascending and descending passes over the same target area. The output products have absolute location uncertainty of less than 50 m and relative distortion (scale factor and skew) of less than 0.1 per cent relative to local variations from the assumed geoid.

Curlander, John C.↗
NASA NTRS1991

Intelligent systems technology infrastructure for integrated systems

A system infrastructure must be properly designed and integrated from the conceptual development phase to accommodate evolutionary intelligent technologies. Several technology development activities were identified that may have application to rendezvous and capture systems. Optical correlators in conjunction with fuzzy logic control might be used for the identification, tracking, and capture of either cooperative or non-cooperative targets without the intensive computational requirements associated with vision processing. A hybrid digital/analog system was developed and tested with a robotic arm. An aircraft refueling application demonstration is planned within two years. Initially this demonstration will be ground based with a follow-on air based demonstration. System dependability measurement and modeling techniques are being developed for fault management applications. This involves usage of incremental solution/evaluation techniques and modularized systems to facilitate reuse and to take advantage of natural partitions in system models. Though not yet commercially available and currently subject to accuracy limitations, technology is being developed to perform optical matrix operations to enhance computational speed. Optical terrain recognition using camera image sequencing processed with optical correlators is being developed to determine position and velocity in support of lander guidance. The system is planned for testing in conjunction with Dryden Flight Research Facility. Advanced architecture technology is defining open architecture design constraints, test bed concepts (processors, multiple hardware/software and multi-dimensional user support, knowledge/tool sharing infrastructure), and software engineering interface issues.

Lum, Henry↗
NASA NTRS2001

Use of a genetic algorithm for the analysis of eye movements from the linear vestibulo-ocular reflex

It is common in vestibular and oculomotor testing to use a single-frequency (sine) or combination of frequencies [sum-of-sines (SOS)] stimulus for head or target motion. The resulting eye movements typically contain a smooth tracking component, which follows the stimulus, in which are interspersed rapid eye movements (saccades or fast phases). The parameters of the smooth tracking--the amplitude and phase of each component frequency--are of interest; many methods have been devised that attempt to identify and remove the fast eye movements from the smooth. We describe a new approach to this problem, tailored to both single-frequency and sum-of-sines stimulation of the human linear vestibulo-ocular reflex. An approximate derivative is used to identify fast movements, which are then omitted from further analysis. The remaining points form a series of smooth tracking segments. A genetic algorithm is used to fit these segments together to form a smooth (but disconnected) wave form, by iteratively removing biases due to the missing fast phases. A genetic algorithm is an iterative optimization procedure; it provides a basis for extending this approach to more complex stimulus-response situations. In the SOS case, the genetic algorithm estimates the amplitude and phase values of the component frequencies as well as removing biases.

Non-NASA Center↗
DOE OSTI2016

Capillary absorption spectrometer and process for isotopic analysis of small samples

A capillary absorption spectrometer and process are described that provide highly sensitive and accurate stable absorption measurements of analytes in a sample gas that may include isotopologues of carbon and oxygen obtained from gas and biological samples. It further provides isotopic images of microbial communities that allow tracking of nutrients at the single cell level. It further targets naturally occurring variations in carbon and oxygen isotopes that avoids need for expensive isotopically labeled mixtures which allows study of samples taken from the field without modification. The method also permits sampling in vivo permitting real-time ambient studies of microbial communities.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Capillary absorption spectrometer and process for isotopic analysis of small samples

A capillary absorption spectrometer and process are described that provide highly sensitive and accurate stable absorption measurements of analytes in a sample gas that may include isotopologues of carbon and oxygen obtained from gas and biological samples. It further provides isotopic images of microbial communities that allow tracking of nutrients at the single cell level. It further targets naturally occurring variations in carbon and oxygen isotopes that avoids need for expensive isotopically labeled mixtures which allows study of samples taken from the field without modification. The process also permits sampling in vivo permitting real-time ambient studies of microbial communities.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

High-Pressure Gaseous Argon TPC for the DUNE Near Detector

The DUNE Near Detector design consists of multiple components, each designed to produce complementary constraints on flux and neutrino interaction systematic uncertainties for the oscillation analyses. One of these subdetectors is a magnetized high-pressure gaseous-argon TPC (HPgTPC), which will provide fine-grained tracking in a low-density detector, using the same target nucleus as the DUNE far detector. With its low momentum threshold for particle detection, the HPgTPC will be able to constrain one of the most crucial - and least-well understood - uncertainties for the oscillation analysis: nuclear effects in neutrino-argon interactions. These proceedings describe the current design, physics goals, and projected performance of the HPgTPC, as well as the ongoing R&D work at Fermilab, in which a test-stand TPC is being built and will be operated at up to 10 atm pressure.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Status of the JLab Eta Factory (JEF) experiment

The JLab Eta Factory (JEF) experiment is designed to study various decays of the ? meson using the GlueX detector in Hall D at Jefferson Lab. The experimental program includes measuring the Dalitz distribution from ???+???0 to determine the up/down quark mass difference, looking for evidence for new C-violating/P-conserving physics, providing input to higher-order chiral perturbation theory calculations, and searching for evidence of dark matter. The latter two items rely on measuring the rare ???0?? decay mode that will require an upgrade to the existing GlueX equipment, which is a fixed target apparatus based on a 2-Tesla solenoid magnet. Charged tracks are reconstructed using drift chambers within the magnet and neutral particles are detected in the forward direction in the Forward Calorimeter (FCAL), an array of lead glass blocks. The JEF program calls for replacing the ?80×80 cm2 region of the FCAL around the beam line with an array of 2×2×20 cm3 lead tungstate crystals. The status of this upgrade will be presented.

Taylor, Simon↗
DOE OSTI2021

NACHOS, a CubeSat-based high-resolution UV-Visible hyperspectral imager for remote sensing of trace gases: system overview and science objectives

Here, the Nano-satellite Atmospheric Chemistry Hyperspectral Observation System (NACHOS) is a high-throughput (f/2.9), high spectral resolution (~1.3 nm optical resolution, 0.6 nm sampling) Offner-design hyperspectral imager operating in the 300-500 nm spectral region. The 1.5U instrument payload (1U optical system, 0.5U electronics module) is hosted by a 1.5U LANL-designed CubeSat bus to comprise a 3U complete satellite. Spectroscopically similar to NASA’s Ozone Monitoring Instrument (OMI), which provides wide-field global mapping of ozone and other gases at coarse spatial resolution, NACHOS fills the complementary niche of targeted measurements at much higher spatial resolution. With 350 across-track spatial pixels and a 15-degree across-track field of view, NACHOS will provide spectral imaging at roughly 0.4 km per pixel from 500 km altitude. NACHOS incorporates highly streamlined gas-retrieval algorithms for rapid onboard processing, alleviating the need to routinely downlink massive hyperspectral data cubes. We will discuss the instrument design, challenges in achieving mechanical robustness to launch vibration in such a compact instrument, the onboard calibration system, and gas-retrieval data downlink strategy. We will also discuss potential science missions, including monitoring of NO 2 as an easily detected proxy for anthropogenic fossil-fuel greenhouse gases, monitoring lowlevel SO 2 degassing at pre-eruptive volcanoes, H 2 CO from wildfires, and characterization of aerosols. The long-term vision is for a many-satellite constellation that could provide both high spatial resolution and frequent revisits for selected targets of interest. As an initial technology demonstration of this vision, the NACHOS project is currently slated to launch two CubeSats in early 2022.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

e08-008: Exclusive study of deuteron electrodisintegration near threshold

The study of threshold electrodisintegration of and elastic scattering on the only stable two nucleon system, the deuteron, can reveal specific aspects of the N-N interaction. The simplicity of electrodisintegration along with the simplicity of the deuteron makes this study most appropriate for revealing these interactions. By using an incident beam of polarized electrons and by measuring the polarization of the recoiling proton, the ratio of the electric (G {sub E }) and magnetic (G {sub M }) form factors for d( e-vector ,e{sup ′} p-vector ) (and p( e-vector ,e{sup ′} p-vector )) reactions may be extracted. This experiment was conducted in Hall A at Jefferson Lab in Newport News, Virginia using a beam of polarized electrons provided by the CEBAF Accelerator incident on a liquid deuterium (and hydrogen) target. The scattered electron and the recoiling (polarized) proton were detected using the High Resolution Spectrometers of Hall A. To determine the polarization of the recoil proton, an analyzing material was placed perpendicular to the protons trajectory through the spectrometer, in front of a set of straw chambers. Due to the spin-orbit interactions involved in the scattering of the proton from the analyzer material, asymmetries seen in the distribution of events detected by these straw chambers reveal the polarization of the recoil proton. By tracking the spin procession of the polarized protons from the straw chambers back to the target, the transferred and induced polarization of the proton may be determined. The (double-spin) asymmetries observed in the straw chambers will first be studied for the well-known elastic p( e-vector ,e{sup ′} p-vector ) process and compared to the asymmetries for d( e-vector ,e{sup ′} p-vector )n(x{sub B}=1). The analysis will then be repeated to determine how these asymmetries change with increasing x {sub B }(to the kinematic limit for deuteron electrodisintegration).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

The correlation between the radial distribution of high-energetic ions and the structural as well as electrical properties of magnetron sputtered ZnO:Al films

The origin of the pronounced radial distributions of structural and electrical properties of magnetron sputtered ZnO:Al films has been investigated. The film properties were correlated with the radially resolved ion-distribution functions. While the positive ions exhibit low energies and a radial distribution with a maximum intensity opposite the center of the target, the negative ions can have energies up to several hundred eV, depending on the target potential, with a radial distribution with two maxima opposite the erosion tracks. The most prominent positive ion is that of the working gas (Ar{sup +}), while the highest flux of the negative ions is measured for negative oxygen O{sup −}. The radial distribution of the flux of the high-energetic negative ions can clearly be related to the radial variations of the structural (c-axis lattice parameter, crystallite size) and electronic (resistivity) properties for sputtering from the planar target, which points to the decisive role of the high-energetic negative oxygen ions for the film quality. The relation between the negative ion bombardment and the structural as well as electronic properties can be explained by a qualitative model recently developed by us. The same target has also been investigated in the eroded state. In this case, the limited acceptance angle of the mass spectrometer leads to a misinterpretation of the radial distribution of the flux of the high-energetic negative ions. This effect can be explained by a simulation, based on the assumption that the high-energetic negative ions are mainly accelerated in the cathode (target) sheath perpendicular to the uneven substrate surface.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Differentiating multi-MeV, multi-ion spectra with CR-39 solid-state nuclear track detectors

The development of high intensity petawatt lasers has created new possibilities for ion acceleration and nuclear fusion using solid targets. In such laser-matter interaction, multiple ion species are accelerated with broad spectra up to hundreds of MeV. To measure ion yields and for species identification, CR-39 solid-state nuclear track detectors are frequently used. However, these detectors are limited in their applicability for multi-ion spectra differentiation as standard image recognition algorithms can lead to a misinterpretation of data, there is no unique relation between track diameter and particle energy, and there are overlapping pit diameter relationships for multiple particle species. In this report, we address these issues by first developing an algorithm to overcome user bias during image processing. Second, we use calibration of the detector response for protons, carbon and helium ions (alpha particles) from 0.1 to above 10 MeV and measurements of statistical energy loss fluctuations in a forward-fitting procedure utilizing multiple, differently filtered CR-39, altogether enabling high-sensitivity, multi-species particle spectroscopy. To validate this capability, we show that inferred CR-39 spectra match Thomson parabola ion spectrometer data from the same experiment. Filtered CR-39 spectrometers were used to detect, within a background of ~ 2 × 10 11 sr -1 J -1 protons and carbons, (1.3 ± 0.7) × 10 8 sr -1 J -1 alpha particles from laser-driven proton-boron fusion reactions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1984

Exact nonlinear command generation and tracking for robot manipulators and spacecraft slewing maneuvers

In connection with the current interest in agile spacecraft maneuvers, it has become necessary to consider the nonlinear coupling effects of multiaxial rotation in the treatment of command generation and tracking problems. Multiaxial maneuvers will be required in military missions involving a fast acquisition of moving targets in space. In addition, such maneuvers are also needed for the efficient operation of robot manipulators. Attention is given to details regarding the direct nonlinear command generation and tracking, an approach which has been successfully applied to the design of control systems for V/STOL aircraft, linearizing transformations for spacecraft controlled with external thrusters, the case of flexible spacecraft dynamics, examples from robot dynamics, and problems of implementation and testing.

Dywer, T. A. W., III↗
NASA NTRS2002

Simulations of Ground and Space-Based Oxygen Atom Experiments

Fast, pulsed atomic oxygen sources are a key tool in ground-based investigations of spacecraft contamination and surface erosion effects. These technically challenging ground-based studies provide a before and after picture of materials under low-earth-orbit (LEO) conditions. It would be of great interest to track in real time the pulsed flux from the source to the surface sample target and beyond in order to characterize the population of atoms and molecules that actually impact the surface and those that make it downstream to any coincident detectors. We have performed simulations in order to provide such detailed descriptions of these ground-based measurements and to provide an assessment of their correspondence to the actual LEO environment. Where possible we also make comparisons to measured fluxes and erosion yields. To perform the calculations we use a detailed description of a measurement beam and surface geometry based on the W, pulsed apparatus at Montana State University. In this system, a short pulse (on the order of 10 microseconds) of an O/O2 beam impacts a flat sample about 40 cm downstream and slightly displaced &om the beam s central axis. Past this target, at the end of the beam axis is a quadrupole mass spectrometer that measures the relative in situ flux of 0102 to give an overall normalized erosion yield. In our simulations we use the Direct Simulation Monte Carlo (DSMC) method, and track individual atoms within the atomic oxygen pulse. DSMC techniques are typically used to model rarefied (few collision) gas-flows which occur at altitudes above approximately 110 kilometers. These techniques are well suited for the conditions here, and multi-collision effects that can only be treated by this or a similar technique are included. This simulation includes collisions with the surface and among gas atoms that have scattered from the surface. The simulation also includes descriptions of the velocity spread and spatial profiles of the O/O2 beam obtained from separate measurements. These computations use basic engineering models for the gas-gas and gas-surface scattering and focus on the influence of multi-collision effects. These simulations characterize many important quantities of interest including the actual flux of atoms that reach the surface, the energy distribution of this flux, as well as the direction of the velocity of the flux that strikes the surface. These quantities are important in characterizing the conditions which give rise to measured surface erosion. The calculations also yield time- snapshots of the pulse as it impacts and flows around the surface. These snapshots reveal the local environment of gas near the surface for the duration of the pulse. We are also able to compute the flux of molecules that travel downstream and reach the spectrometer, and we characterize their velocity distribution. The number of atoms that reach the spectrometer can in fact be influenced by the presence of the surface due to gas-gas collisions from atoms scattered h m the surface, and it will generally be less than that with the surface absent. This amounts to an overall normalization factor in computing erosion yields. We discuss these quantities and their relationship to the gas-surf$ce interaction parameters. We have also performed similar calculations corresponding to conditions (number densities, temperatures, and velocities) of low-earth orbit. The steady-state nature and lower overall flux of the actual space environment give rise to differences in the nature of the gas-impacts on the surface from those of the ground-based measurements using a pulsed source.

Minton, T. K.↗