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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 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

A Temporal Approach to Monitor Surface Mine Reclamation Progress via LANDSAT

Using LANDSAT satellite imagery, the mine reclamation process can be studied on a temporal and continuing basis. Not only can the progress of reclamation be readily monitored, but also a breakdown in the mining reclamation process can be detected. In viewing reclamation, it is important to monitor the mined site well past initial revegation stages. With present mining law and bonding procedures, fast revegetational growth is encouraged, often leading to poor soil fertilizing and inappropriate stabilizing species. As a result, the initial reclamation may exhibit good qualities for one or two years but then may experience vegetational deterioration after the state has relinquished the mining company from it's responsibility. It is this small-scale breakdown in the reclamation process that was detected using an unsupervised classification technique with eight-year temporal LANDSAT imagery coverage.

Davis, A. L.↗
DOE OSTI2010

Single Variable and Multivariate Analysis of Remote Laser-Induced Breakdown Spectra for Prediction of Rb, Sr, Cr, Ba, and V in Igneous Rocks

Laser-induced breakdown spectroscopy (LIBS) will be employed by the ChemCam instrument on the Mars Science Laboratory rover Curiosity to obtain UV, VIS, and VNIR atomic emission spectra of surface rocks and soils. LIBS quantitative analysis is complicated by chemical matrix effects related to abundances of neutral and ionized species in the resultant plasma, collisional interactions within plasma, laser-to-sample coupling efficiency, and self-absorption. Atmospheric composition and pressure also influence the intensity of LIBS plasma. These chemical matrix effects influence the ratio of intensity or area of a given emission line to the abundance of the element producing that line. To compensate for these complications, multivariate techniques, specifically partial least-squares regression (PLS), have been utilized to predict major element compositions (>1 wt.% oxide) of rocks, PLS methods regress one or multiple response variables (elemental concentrations) against multiple explanatory variables (intensity at each pixel of the spectrometers). Because PLS utilizes all available explanatory variable and eliminates multicollinearity, it generally performs better than univariate methods for prediction of major elements. However, peaks arising from emissions from trace elements may be masked by peaks of higher intensities from major elements. Thus in PLS regression, wherein a correlation coefficient is determined for each elemental concentration at each spectrometer pixel, trace elements may show high correlation with more intense lines resulting from optical emissions of other elements. This could result in error in predictions of trace element concentrations. Here, results of simple linear regression (SLR) and multivariate PLS-2 regression for determination of trace Rb, Sr, Cr, Ba, and V in igneous rock samples are compared. This study focuses on comparisons using only line intensities rather than peak areas to highlight differences between SLR and PLS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 18

Topics discussed include: PoDS: A Powder Delivery System for Mars In-Situ Organic, Mineralogic and Isotopic Analysis Instruments Planetary Differentiation of Accreting Planetesimals with 26Al and 60Fe as the Heat Sources Ground-based Observation of Lunar Surface by Lunar VIS/NIR Spectral Imager Mt. Oikeyama Structure: First Impact Structure in Japan? Central Mounds in Martian Impact Craters: Assessment as Possible Perennial Permafrost Mounds (Pingos) A Further Analysis of Potential Photosynthetic Life on Mars New Insight into Valleys-Ocean Boundary on Mars Using 128 Pixels per Degree MOLA Data: Implication for Martian Ocean and Global Climate Change; Recursive Topography Based Surface Age Computations for Mars: New Insight into Surficial Processes That Influenced Craters Distribution as a Step Toward the Formal Proof of Martian Ocean Recession, Timing and Probability; Laser-induced Breakdown Spectroscopy: A New Method for Stand-Off Quantitative Analysis of Samples on Mars; Milk Spring Channels Provide Further Evidence of Oceanic, >1.7-km-Deep Late Devonian Alamo Crater, Southern Nevada; Exploration of Martian Polar Residual Caps from HEND/ODYSSEY Data; Outflow Channels Influencing Martian Climate: Global Circulation Model Simulations with Emplaced Water; Presence of Nonmethane Hydrocarbons on Pluto; Difference in Degree of Space Weathering on the Newborn Asteroid Karin; Circular Collapsed Features Related to the Chaotic Terrain Formation on Mars; A Search for Live (sup 244)Pu in Deep-Sea Sediments: Preliminary Results of Method Development; Some Peculiarities of Quartz, Biotite and Garnet Transformation in Conditions of Step-like Shock Compression of Crystal Slate; Error Analysis of Remotely-Acquired Mossbauer Spectra; Cloud Activity on Titan During the Cassini Mission; Solar Radiation Pressure and Transient Flows on Asteroid Surfaces; Landing Site Characteristics for Europa 1: Topography; and The Crop Circles of Europa.

Source record↗
DOE OSTI2014

Detonator Bridgewire Gap Tests Using SE-1/31 Detonator Housings with High Surface Area PETN

The purpose of this work is to develop a basis for addressing broken and damaged bridgewires in exploding bridgewire (EBW) detonators and their vulnerability to electrostatic discharge (ESD) sources. Parameters such as gap width, breakdown voltage, charge voltage, and source energy are explored. We are interested in understanding how bridgewire gap length affects the detonator initiability and safety.

42 ENGINEERING↗
DOE OSTI2023

Microstructure and corrosion of CrFeMnV multi-principal element alloy

In this study, a multi-principal element alloy consisting of equiatomic concentrations of Cr, Fe, Mn, and V was produced by arc melting. The combination of X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy indicated that the CrFeMnV MPEA was comprised of a BCC matrix with a dispersion of a secondary phase. Cyclic potentiodynamic polarization tests in 0.6M NaCl revealed high corrosion resistance – superior to that of stainless steel 304L, as evident from high breakdown and repassivation potentials. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry provided insight into the formed multi-layer surface film after constant immersion and potentiostatic conditioning.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Metal additively manufactured wavy fin cold-plate architecture for improved thermal-hydraulic performance

Rapid growth in artificial intelligence and data center workloads demands high-performance liquid cooling to manage increasing chip power. This study presents two metal-additive-manufactured cold plates with sinusoidal fins, constant-amplitude wavy fins and linearly variable-amplitude wavy fins and compares them against metal-additive-manufactured straight fins using experiments conducted at 1 kW heat dissipation as well as high-fidelity 3D conjugate computational fluid dynamic simulations. The cold plates were printed in AlSi10Mg material and underwent design using a Python-automated workflow prior to manufacture and testing. The experiments show that wavy fins reduce the normalized thermal resistance by 35 to 45 % at water flow rates from 1 to 4 LPM. At a fixed 20 kPa pressure drop, the variable-waviness design lowered peak surface temperature by 9 °C and thermal resistance by 51 %, while edge-channel maldistribution in the constant wavy fin design limited gains. A thermal resistance breakdown revealed that 55–63 % of the total thermal resistance in wavy designs comes from base heat conduction, 27–33 % from fin heat conduction, and 9–13 % from fin heat convection, indicating the need to address conduction bottlenecks. Parametric sweeps identify a 3 mm fin pitch as optimal, and that horizontal inlet/outlet manifolds further reduce pressure drop by 30–60 % and thermal resistance by 9–16 % relative to vertical inlet-outlet manifolds. The results yield comprehensive guidelines for fin geometry, manifold alignment, material selection and additive-manufacturing constraints to realize high-performance liquid-cooled cold plates for power-dense electronics.

3d printing↗
DOE OSTI2017

Hydrodynamic model of a dielectric-barrier discharge in pure chlorine

A one-dimensional hydrodynamic model of a dielectric-barrier discharge (DBD) in pure chlorine is developed, and the properties of the discharge are modeled. The discharge is excited in an 8-mm-long discharge gap between 2-mm-thick dielectric quartz layers covering metal electrodes. The DBD spatiotemporal characteristics at gas pressures of 15–100 Torr are modeled for the case in which a 100-kHz harmonic voltage with an amplitude of 8 kV is applied to the electrodes. The average power density deposited in the discharge over one voltage period is 2.5–5.8 W/cm{sup 3}. It is shown that ions and electrons absorb about 95 and 5% of the discharge power, respectively. In this case, from 67 to 97% of the power absorbed by electrons is spent on the dissociation and ionization of Cl{sub 2} molecules. Two phases can be distinguished in the discharge dynamics: the active (multispike) phase, which follows the breakdown of the discharge gap, and the passive phase. The active phase is characterized by the presence of multiple current spikes, a relatively high current, small surface charge density on the dielectrics, and large voltage drop across the discharge gap. The passive phase (with no current spikes) is characterized by a low current, large surface charge density on the dielectrics, and small voltage drop across the discharge gap. The peak current density in the spikes at all pressures is about 4 mA/cm{sup 2}. In the multispike phase, there are distinct space charge sheaths with thicknesses of 1.5–1.8 mm and a mean electron energy of 4.3–7 eV and the central region of quasineutral plasma with a weak electric field and a mean electron energy of 0.8–3 eV. The degree of ionization of chlorine molecules in the discharge is ~0.02% at a pressure of 15 Torr and ~0.01% at 100 Torr. The DBD plasma is electronegative due to the fast attachment of electrons to chlorine atoms: e + Cl{sub 2} → Cl + Cl{sup –}. The most abundant charged particles are Cl{sub 2}{sup +} and Cl{sup −} ions, and the degree of ionization during current spikes in the active phase is (4.1–5.5) × 10{sup –7}. The mechanism of discharge sustainment is analyzed. The appearance of a series of current spikes in the active phase of the discharge is explained.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1974

High-voltage distributors

Two distributors reduce high-voltage breakdowns and corona discharges. Both distributors are constructed to prevent air traps and facilitate servicing without soldering. Occurrence of coronas is also minimized due to smooth surfaces of device.

Mcchesney, J. F., Jr.↗
NASA NTRS1986

Investigation of empennage buffeting

Theoretical methods of predicting aircraft buffeting are reviewed. For the buffeting due to leading edge vortex breakdown, a method is developed to convert test data of mean square values of fluctuating normal force to buffeting vortex strength through an unsteady lifting-surface theory and unsteady suction analogy. The resulting buffeting vortex from the leading edge extension of an F-18 configuration is used to generate a fluctuating flow field which produces unsteady pressure distribution on the vertical tails. The root mean square values of root bending moment on the vertical tails are calculated for a rigid configuration.

Lan, C. E.↗
NASA NTRS1987

Investigation of empennage buffeting

Theoretical methods of predicting aircraft buffeting are reviewed. For the buffeting due to leading-edge vortex breakdown, a method is developed to convert test data of mean square values of fluctuating normal force to buffeting vortex strength through an unsteady lifting-surface theory and unsteady suction analogy. The resulting buffeting vortex from the leading-edge extension of an F-18 configuration is used to generate a fluctuating flow field which produces unsteady pressure distribution on the vertical tails. The root mean square values of root bending moment on the vertical tails are calculated for a rigid configuration. Results from a flow visualization and hot films study in a water tunnel facility using a 1/48 scale model of an F-18 are included in an appendix. The results confirm that the LEX vortex is the dominant forcing function of fin buffet at high angles of attack.

Lan, C. Edward↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Meteorites: Experiments and Spectroscopy

The session "Meteorites: Experiments and Spectroscopy" included the following reports:The Suitability of Laser Induced Breakdown Spectroscopy for Determining the Compositions of Extraterrestrial Material; Deconvolving Terrestrial Alteration Mineral Spectral Signatures from Meteorite Reflectance Measurements; Impacts of Ions and Micrometeorites on Mineral Surfaces: Reflectance and Chemical Changes Found in Ordinary Chondrites; FT-IR Micro-spectroscopy of Fine-grained Planetary Materials: Further Results; Effusion Cell Measurements of the Vapor Pressure of Cobalt at Temperatures up to 2000K: Comparisons with Iron and Nickel; Kinetics of Fe2+-Mg Order-Disorder in P21/c Pigeonite: Implications for Cooling Rates Calculations; Compressional and Shear Wave Velocities in Meteorites; Chemical and Mineralogical Size Segregation in the Impact Disruption of Anhydrous Stone Meteorites; and Shock Pressures of Impacts vs. Crystallization Pressures of Shock-induced Melt Veins of the chondrites.

Source record↗
DOE OSTI2025

Single particle trace element analysis of uranium oxide standards with laser-induced breakdown spectroscopy

Femtosecond Laser-Induced Breakdown Spectroscopy (LIBS) was used to analyze over 1000 individual particles of uranium oxide trace element standard CRM124. Intra-granular analysis showed elemental concentrations were consistent across different surface locations on each uranium grain. However, inter-granular comparison revealed large heterogeneity between different grains of the same sample. By comparing the distribution of elemental concentrations across the particle populations, we were able to correctly identify a manufacturing process involving wet chemistry, rather than a dry mixing of two powders to give an overall chemical average. In conclusion, this demonstrates the utility of LIBS as a large-scale single particle analysis tool for nuclear forensics.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Micro-Laser-Induced Breakdown Spectroscopy: A Novel Approach Used in the Detection of Six Rare Earths and One Transition Metal

Laser-induced breakdown spectroscopy (LIBS) was undertaken using an instrument which used a high-powered microscope to deliver the light and tightly focused the low energy laser beam onto the surface of a solid sample. A micro-plasma was generated on the surface of the sample under test even though the amount of energy/pulse from a beam of 532 nm was <1 mJ. Rare earth elements such as europium, gadolinium, lanthanum, neodymium, praseodymium, samarium, and a transition metal, yttrium, were tested. These elements are important in nuclear fission reactions especially for estimation of actinide masses for non-proliferation “safeguards”. Each element was mixed in the graphite matrix in different percentages from 1% to 50% by weight and the LIBS spectra were obtained for each composition as well as after mixing each element in the same amount using oxides of the elements. The data for the 5% mixture of the rare earth elements with graphite powder along with the transition metal has been presented in this article. A micro-LIBS approach was used to demonstrate that these rare earth elements can be identified individually and in a complex mixture in glove boxes in which the microscope LIBS instrument is housed in a nuclear research environment.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Elemental content of enamel and dentin after bleaching of teeth (a comparative study between laser-induced breakdown spectroscopy and x-ray photoelectron spectroscopy)

The elemental content of the superficial and inner enamel as well as that of dentin was analyzed using laser-induced breakdown spectroscopy (LIBS) and x-ray photoelectron spectroscopy (XPS) of bleached and unbleached tooth specimens. It is thus clear from the spectral analysis using both the LIBS and XPS technique that elemental changes (though insignificant within the scopes of this study) of variable intensities do occur on the surface of the enamel and extend deeper to reach dentin. The results of the LIBS revealed a slight reduction in the calcium levels in the bleached compared to the control specimens in all the different bleaching groups and in both enamel and dentin. The good correlation found between the LIBS and XPS results demonstrates the possibility of LIBS technique for detection of minor loss in calcium and phosphorus in enamel and dentin.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2010

Quantitative fluid inclusion gas analysis of airburst, nuclear, impact and fulgurite glasses.

We present quantitative fluid inclusion gas analysis on a suite of violently-formed glasses. We used the incremental crush mass spectrometry method (Norman & Blamey, 2001) to analyze eight pieces of Libyan Desert Glass (LDG). As potential analogues we also analyzed trinitite, three impact crater glasses, and three fulgurites. The 'clear' LDG has the lowest CO{sub 2} content and O{sub 2}/Ar ratios are two orders of magnitude lower than atmospheric. The 'foamy' glass samples have heterogeneous CO{sub 2} contents and O{sub 2}/Ar ratios. N{sub 2}/Ar ratios are similar to atmospheric (83.6). H{sub 2} and He are elevated but it is difficult to confirm whether they are of terrestrial or meteoritic origin. Combustion cannot account for oxygen depletion that matches the amount of CO{sub 2} produced. An alternative mechanism is required that removes oxygen without producing CO{sub 2}. Trinitite has exceedingly high CO{sub 2} which we attribute to carbonate breakdown of the caliche at ground zero. The O{sub 2}/Ar ratio for trinitite is lower than atmospheric but higher than all LDG samples. N{sub 2}/Ar ratios closely match atmospheric. Samples from Lonar, Henbury and Aouelloul impact craters have atmospheric N{sub 2}/Ar ratios. O{sub 2}/Ar ratios at Lonar and Henbury are 9.5 to 9.9 whereas the O{sub 2}/Ar ratio is 0.1 for the Aouelloul sample. In most fulgurites the N{sub 2}/Ar ratio is higher than atmospheric, possibly due to interference from CO. Oxygen ranges from 1.3 to 19.3%. Gas signatures of LDG inclusions neither match those from the craters, trinitite nor fulgurites. It is difficult to explain both the observed depletion of oxygen in the LDG and a CO{sub 2} level that is lower than it would be if the CO{sub 2} were simply a product of hydrocarbon combustion in air. One possible mechanism for oxygen depletion is that as air turbulently mixed with a hot jet of vaporized asteroid from an airburst and expanded, the atmospheric oxygen reacted with the metal vapor to form metal oxides that condensed. This observation is compatible with the model of Boslough & Crawford (2008) who suggest that an airburst incinerates organic materials over a large area, melting surface materials that then quench to form glass. Bubbles would contain a mixture of pre-existing atmosphere with combustion products from organic material and products of the reaction between vaporized cosmic materials (including metals) and terrestrial surface and atmosphere.

58 GEOSCIENCES↗
DOE OSTI2022

Influence of copper and aluminum substitution on high-temperature oxidation of the FeCoCrNiMn “Cantor” alloy

In this study, the oxidation behavior of FeCoCrNiMn (HEA + Mn) is compared to three modified HEAs manufactured by substituting Mn with Al, Cu, or Al + Cu. Oxidation tests were conducted between 600°C and 800°C for up to 500 h in synthetic air. Substitution of Mn leads to a significant improvement in the oxidation resistance for the three modified HEAs. For FeCoCrNiCu (HEA + Cu), a local attack of a Cu-rich phase was observed, leading to the formation of CuO blisters on the surface. The FeCoCrNiAl (HEA + Al) alloy was characterized by the formation of a thin Al 2 O 3 surface layer for all temperatures. However, for the HEA + Al alloy the formation of AlN was observed after 300 h at 800°C, leading to a partial breakdown of the protective scale. FeCoCrNiCuAl (HEA + Cu + Al) by far showed the best oxidation resistance, characterized by the formation of a highly protective Al 2 O 3 scale that effectively inhibited nitrogen penetration into the metal subsurface and local attack of the Cu-rich phase.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Influence of Impurities in Module Packaging on Potential-Induced Degradation

Chemical compounds were added into crystalline silicon cell mini modules, including in the encapsulant, interfaces, and glass, to determine their effect on potential-induced degradation (PID). Fe, either in the glass or at the glass/encapsulant interface, was found to be correlated with increased PID, but the difference in module power loss was not statistically significant compared to controls. Additions of Cu, Cr, Pb, Sn, Ag, and Na compounds to either the encapsulant or at the glass/encapsulant interface did not appear correlated with PID. Lock-in thermography on bare cells affected by PID removed from the mini modules show highly localized areas of junction breakdown, and SIMS analysis indicates localized impurities as well, though a spatial relation between the two was not established. Deposition of a conductive layer on the front surface of the cell, either with semitransparent Ta or Poly 3,4-ethylenedioxythiophene (PEDOT), eliminated PID when the cells were stressed at -1000 V bias, 50°C, with the glass face grounded for 140 h.

14 SOLAR ENERGY↗
DOE OSTI2014

What is the importance of climate model bias when projecting the impacts of climate change on land surface processes?

Regional climate change impact (CCI) studies have widely involved downscaling and bias-correcting (BC) Global Climate Model (GCM)-projected climate for driving land surface models. However, BC may cause uncertainties in projecting hydrologic and biogeochemical responses to future climate due to the impaired spatiotemporal covariance of climate variables and a breakdown of physical conservation principles. Here we quantify the impact of BC on simulated climate-driven changes in water variables(evapotranspiration, ET; runoff; snow water equivalent, SWE; and water demand for irrigation), crop yield, biogenic volatile organic compounds (BVOC), nitric oxide (NO) emissions, and dissolved inorganic nitrogen (DIN) export over the Pacific Northwest (PNW) Region. We also quantify the impacts on net primary production (NPP) over a small watershed in the region (HJ Andrews). Simulation results from the coupled ECHAM5/MPI-OM model with A1B emission scenario were firstly dynamically downscaled to 12 km resolutions with WRF model. Then a quantile mapping based statistical downscaling model was used to downscale them into 1/16th degree resolution daily climate data over historical and future periods. Two series climate data were generated according to the option of bias-correction (i.e. with bias-correction (BC) and without bias-correction, NBC). Impact models were then applied to estimate hydrologic and biogeochemical responses to both BC and NBC meteorological datasets. These im20 pact models include a macro-scale hydrologic model (VIC), a coupled cropping system model (VIC-CropSyst), an ecohydrologic model (RHESSys), a biogenic emissions model (MEGAN), and a nutrient export model (Global-NEWS). Results demonstrate that the BC and NBC climate data provide consistent estimates of the climate-driven changes in water fluxes (ET, runoff, and water demand), VOCs (isoprene and monoterpenes) and NO emissions, mean crop yield, and river DIN export over the PNW domain. However, significant differences rise from projected SWE, crop yield from dry lands, and HJ Andrews’s ET between BC and NBC data. Even though BC post-processing has no significant impacts on most of the studied variables when taking PNW as a whole, their effects have large spatial variations and some local areas are substantially influenced. In addition, there are months during which BC and NBC post-processing produces significant differences in projected changes, such as summer runoff. Factor-controlled simulations indicate that BC post-processing of precipitation and temperature both substantially contribute to these differences at region scales. We conclude that there are trade-offs between using BC climate data for offline CCI studies vs. direct modeled climate data. These trade-offs should be considered when designing integrated modeling frameworks for specific applications; e.g., BC may be more important when considering impacts on reservoir operations in mountainous watersheds than when investigating impacts on biogenic emissions and air quality (where VOCs are a primary indicator).

Liu, M. L.↗