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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 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Neural Learning Based Blind Source Separation for Detection of Material Defects in Pulsed Thermography Images

In this paper, we introduce a neural learning-based approach to blind source separation for detection of material flaws in pulsed thermography (PT) images. This approach can be used to detect internal defects (pores) in metallic Additively Manufactured (AM) materials. Such defects occur in high-strength alloys produced with direct laser sintering AM method for nuclear energy applications. Pulsed thermal imaging system utilizes a high intensity flash lamp to rapidly heat surface of sample, a high sensitivity infrared camera to capture data of surface temperature variations. The data cube obtained with PT (stack of surface temperature images at different times) can be analyzed with image processing algorithms to detect material defects. Compared with conventional nondestructive evaluation (NDE) methods, such as digital radiography and ultrasonic testing, the PT pulsed infrared thermal detection technique has advantages of one-sided non-contact measurements, fast processing of large sample areas captured in one image. Detection of small material defects requires finding features in thermal images, which have signal contrast levels approaching sensitivity limit of IR camera. In this study, an optimized Neural Learning based Blind Source Separation (NLBSS) algorithm, including Principal Component Analysis (PCA), and Independent Component Analysis (ICA) is demonstrated to automatically extract principal temporal and spatial features of thermography frames to enhance flaw detection. By using the NLBSS algorithm, material internal defects can be automatically detected. Furthermore, this processing approach compensates for experimental thermal imaging artifacts, such as noise and uneven heating. By merging artificial intelligence with the photothermic, the NDE system detects internal calibrated defects of various sizes and depths in AM nuclear-grade metallic alloys.

Zhang, Xin↗
NASA NTRS1985

In-situ detection of micron-sized dust particles in near-Earth space

In situ detectors for micron sized dust particles based on the measurement of impact ionization have been flown on several space missions (Pioneer 8/9, HEOS-2 and Helios 1/2). Previous measurements of small dust particles in near-Earth space are reviewed. An instrument is proposed for the measurement of micron sized meteoroids and space debris such as solid rocket exhaust particles from on board an Earth orbiting satellite. The instrument will measure the mass, speed, flight direction and electrical charge of individually impacting debris and meteoritic particles. It is a multicoincidence detector of 1000 sq cm sensitive area and measures particle masses in the range from 10 to the -14th power g to 10 to the -8th power g at an impact speed of 10 km/s. The instrument is lightweight (5 kg), consumes little power (4 watts), and requires a data sampling rate of about 100 bits per second.

Gruen, E.↗
NASA NTRS2017

Supersonic Retro-Propulsion for Future High-Mass Robotic Mars Lander Missions

A feasibility study was conducted to investigate the potential performance advantages of Supersonic Retro-Propulsion in support of future high-mass Mars robotic landing missions. A notional reference architecture for a potential future Mars Sample Return formed the basis for assuming a 4.7 m diameter SRP entry vehicle containing the Mars Ascent Vehicle element. Configuration analysis was conducted to ensure that the payload and required SRP components (including engines and propellant) fit within in the capsule volume. Optimized trajectory analysis highlighted several key performance sensitivities of SRP for ballistic coefficients of 150, 300, and 450 kg/m2. These results indicated a broad SRP ignition envelope (1-4 km altitude, 300-750 m/s velocity), as well as relatively small propellant mass fraction sensitivities to SRP thrust/weight, landing site elevation, and the application of a 4-g entry deceleration constraint (relevant for future crewed mission trajectories). Finally, mass-sizing was performed to assess sensitivities to ballistic coefficient and entry velocity, and showcased the ability of the SRP system to land payload masses on the order of twice that of MSL.

Whetsel, Charles↗
DOE OSTI2012

Rapidity gap cross sections measured with the ATLAS detector in pp collisions at root s=7 TeV

Pseudorapidity gap distributions in proton-proton collisions at {radical}s = 7 {approx} TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 {micro}b{sup -1}. Cross sections are measured differentially in terms of {Delta}{eta}{sup F}, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at {eta} = {+-}4.9, in which no final state particles are produced above a transverse momentum threshold p{sub T}{sup cut}. The measurements span the region 0 < {Delta}{eta}{sup F} < 8 for 200 {approx} MeV < p{sub T}{sup cut} < 800 {approx} MeV. At small {Delta}{eta}{sup F}, the data test the reliability of hadronization models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process (pp {yields} Xp), enhanced by double dissociation (pp {yields} XY) where the invariant mass of the lighter of the two dissociation systems satisfies M{sub Y} {approx}< 7 GeV. The resulting cross section is d{sigma}/d{Delta}{eta}{sup F} {approx}1 mb for {Delta}{eta}{sup F} {approx}>3. The large rapidity gap data are used to constrain the value of the Pomeron intercept appropriate to triple Regge models of soft diffraction. The cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Nanoscale Interfacial Smoothing and Dissolution during Unconventional Reservoir Stimulation Implications for Hydrocarbon Mobilization and Transport

Hydraulic fracturing of low-permeability rocks significantly enhances hydrocarbon production from unconventional reservoirs. However, fluid transport through low-permeability rocks, and the influence of geochemical transformations on pore networks, are poorly constrained. Mineral reactivity during interactions with injected water may alter the physical nature of the rock, which may affect hydrocarbon mobility. To assess alteration to the rock, we previously conducted a hydrothermal experiment that reacted cubed rock samples (1 cm3) with synthetic hydraulic fracturing fluid to simulate physicochemical reactivity during hydraulic fracturing. We analyzed unreacted and reacted rocks by small-angle neutron scattering and high-pressure mercury intrusion to determine how nanoscale (~1-1400 nm) pore networks of unconventional reservoir rocks are influenced by reaction with hydraulic fracturing injectates. We show that fluid-rock interactions have a two-fold influence on hydrocarbon recovery, promoting both hydrocarbon mobilization and transport. Pore-matrix interfaces smooth via removal of clay mineral surface asperities, reducing available surface area for hydrocarbon adsorption by ca. 12-75%. Additionally, hydraulic fracturing fluid-induced dissolution creates new pores with diameters ranging in size from 800-1400 nm, increasing the permeability of the rocks by a factor of 5-10. These two consequences of mineral dissolution act in concert to release hydrocarbons from the host rock and facilitate transport through the rock during unconventional reservoir production.

Herz-Thyhsen, Ryan↗
DOE OSTI2015

Atomic layer deposition of superparamagnetic and ferrimagnetic magnetite thin films

One of the key challenges in realizing superparamagnetism in magnetic thin films lies in finding a low-energy growth way to create sufficiently small grains and magnetic domains which allow the magnetization to randomly and rapidly reverse. In this work, well-defined superparamagnetic and ferrimagnetic Fe{sub 3}O{sub 4} thin films are successfully prepared using atomic layer deposition technique by finely controlling the growth condition and post-annealing process. As-grown Fe{sub 3}O{sub 4} thin films exhibit a conformal surface and poly-crystalline nature with an average grain size of 7 nm, resulting in a superparamagnetic behavior with a blocking temperature of 210 K. After post-annealing in H{sub 2}/Ar at 400 °C, the as-grown α−Fe{sub 2}O{sub 3} sample is reduced to Fe{sub 3}O{sub 4} phase, exhibiting a ferrimagnetic ordering and distinct magnetic shape anisotropy. Atomic layer deposition of magnetite thin films with well-controlled morphology and magnetic properties provides great opportunities for integrating with other order parameters to realize magnetic nano-devices with potential applications in spintronics, electronics, and bio-applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Estimation of Line Cross Sections Using Critical-Dimension Grazing-Incidence Small-Angle X-Ray Scattering

Currently, the semiconductor industry is continuously pushing the limits of photolithography, with feature sizes now smaller than 10 nm. To ensure quality, it has become necessary to look beyond the conventional metrological techniques. X-ray scattering has emerged as a possible contender to determine the average shape of a line grating with subnanometer precision. Yet, to fulfill its promise, faster algorithms must also be developed to interpret and extract metrics from reciprocal-space scattering data. In this paper, we present a fast and accurate x-ray technique and analysis algorithm: critical-dimension grazing-incidence small-angle x-ray scattering (CD GISAXS). The CD GISAXS technique is used in grazing-incidence configuration with a continuous azimuthal rotation of the sample, and thus does not require high-energy x-rays to penetrate the wafer and greatly reduces the data-acquisition times, permitting analysis within the framework of the distorted-wave Born approximation.

36 MATERIALS SCIENCE↗
DOE OSTI2016

TU-H-CAMPUS-TeP2-04: Measurement of Stereotactic Output Factors with DNA Double-Strand Breaks

Purpose: Radiotherapy treatment is specified by radiation dose prescriptions, but biological DNA damage actually controls treatment effectiveness. It is impractical to directly measure dose in the clinic, so we measure quantities, such as collected charge, and calculate the relationship to dose. At small fields, such as those in stereotactic radiosurgery (SRS), charged-particle equilibrium (CPE) breaks down and the accuracy of the measurement for delivered dose decreases. By measuring DNA double-strand breaks (DSB) directly, we believe treatment accuracy could improve by providing a more meaningful measurement. Methods: A DNA dosimeter, consisting of magnetic streptavidin beads attached to 4 kilobase pair DNA strands labeled with biotin and fluorescein amidite (FAM) on opposing ends, was suspended in phosphate-buffered saline (PBS). Twenty µL samples were placed in plastic micro-capillary tubes inside a water tank setup and irradiated with 10 cm, 3 cm, 1.25 cm, 0.75 cm, and 0.5 cm radiation field sizes, where the three smallest sizes were cones. After irradiation, the dosimeters were mechanically separated into beads (intact DNA) and supernatant (broken DNA/FAM) using a magnet. The fluorescence was read and the probability of DSB was calculated. This was used to calculate the output factor for an SRS beam and compared to that measured using a diode detector. Results: The output factors relative to a 10 cm field were 0.89±0.07, 0.76±0.08, 0.59±0.04, and 0.78±0.12 for the field sizes of 3 cm, 1.25 cm, 0.75 cm, and 0.5 cm, respectively. Some of the diode measurements do not fall within these uncertainties. Conclusion: This was the first attempt to measure output factors in a water tank with the DNA dosimeter. Although differences compared to the diode were observed, the uncertainty analysis ignored systematic errors. For future work, we will repeat this experiment to quantify and correct systematic errors, such as those caused by positional alignment and sample contamination. This work was funded in part by CPRIT (RP140105).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Detecting high-emitting methane sources in oil/gas fields using satellite observations

Methane emissions from oil/gas fields originate from a large number of relatively small and densely clustered point sources. A small fraction of high-mode emitters can make a large contribution to the total methane emission. Here we conduct observation system simulation experiments (OSSEs) to examine the potential of recently launched or planned satellites to detect and locate these high-mode emitters through measurements of atmospheric methane columns. We simulate atmospheric methane over a generic oil/gas field (20–500 production sites of different size categories in a 50 × 50 km 2 domain) for a 1-week period using the WRF-STILT meteorological model with 1.3 × 1.3 km 2 horizontal resolution. The simulations consider many random realizations for the occurrence and distribution of high-mode emitters in the field by sampling bimodal probability density functions (PDFs) of emissions from individual sites.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1980

Structure and optical properties of evaporated films of the Cr- and V-group metals

Thin films of Cr, Mo, and W rapidly evaporated in high vacuum (5 x 10 to the -7th torr) onto room-temperature substrates show anomalously low reflectance (compared to bulk samples). From electron and X-ray diffraction and electron microscopy, the normal bcc crystal structure is found, but with very fine grains. Columnar grains about 100 A in diameter were separated by a less dense grain-boundary network about 10-A wide. The measured optical conductivity agrees with an inhomogeneous-medium model that assumes the normal crystalline conductivity for the grain interiors, with model parameters that correlate to the observed columnar grain size. In contrast, V and Nb films rapidly evaporated onto room-temperature substrates have the reflectance of bulk crystalline material. On liquid-nitrogen temperature substrates, however, V and Nb have normal bcc crystal structure but with small flat-plate grains, and the same model, with appropriate parameters, accounts for the optical conductivity. The difference between these two groups apparently depends on residual gases segregated at the grain boundaries in the Cr-group films.

Nestell, J. E., Jr.↗
DOE OSTI2016

Integrated Systems Analysis for a Regional Deep Borehole Repository for Commercial Spent Nuclear Fuel - 16291

Some nuclear waste stakeholders have suggested private interim storage facilities (ISF), but little work has been done to consider the cost or logistics for nuclear waste management or disposal facilities smaller than the national scale. This paper performs an integrated system analysis for a deep borehole repository system which would accept waste from a regional subset of the national commercial reactor fleet. The regional subset is comprised of a centrally-located host state with a large SNF inventory surrounded by states with small SNF inventories. The chosen region will contain between one-fifth and one-quarter of the national commercial SNF inventory. Using best estimates of past and future SNF discharges in the sample region, the SNF inventory in the chosen region is characterized by reactor of origin. Basic parameters are then chosen for the regional repository, such as the annual rate of waste emplacement and the time necessary to process borehole-specific waste canisters. Scenarios chosen for analysis test the sensitivity of a variety of system parameters, including the annual rate of waste acceptance, the division of annual waste acceptance among sites, the use of bare fuel transportation canisters, and the size of the regional subset of reactors. Estimated costs for the facility are $13 billion for around 27,000 MT of SNF and $16 billion for around 35,000 MT. This translates to $490,000 per MT and $466,000 per MT, respectively. These unit costs are comparable to the $370,000 per MT estimate for the full 140,000 MT national inventory. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites

Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N{sub 2} adsorption, UV–vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co{sub 3}O{sub 4} nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co{sub 3}O{sub 4} detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic applied field µ{sub 0}Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion. - Graphical abstract: Room temperature hysteresis loops as a function of the Co content. Display Omitted - Highlights: • Co species as isolated Co{sup 2+}, oxide clusters and Co{sub 3}O{sub 4} nano-particles were detected. • For higher Co loads were detected, by XRD, Co{sub 3}O{sub 4} particles on the external surface. • The confining of Co species inside the mesopores was achieved by increasing Co load. • Paramagnetism from oxide clusters/nano-particles becomes dominant for higher Co loads. • Superparamagnetism can be assigned to Co species of small size and finely dispersed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Native and induced triplet nitrogen-vacancy centers in nano- and micro-diamonds: Half-field electron paramagnetic resonance fingerprint

Multiple frequency electron paramagnetic resonance (EPR) study of small (4–25 nm) nanodiamonds obtained by various dynamic synthesis techniques reveals systematic presence in the half-field (HF) region a distinctive doublet fingerprint consisting of resolved g{sub HF1} = 4.26 and g{sub HF2} = 4.00 signals. This feature is attributed to “forbidden” ΔM{sub S} = 2 transitions in EPR spectra of two native paramagnetic centers of triplet (S = 1) origin designated as TR1 and TR2, characterized by zero field splitting values D{sub 1} = 0.0950 ± 0.002 cm{sup −1} and D{sub 2} = 0.030 ± 0.005 cm{sup −1}. Nanodiamonds of ∼50 nm particle size, obtained by crushing of Ib type nitrogen rich synthetic diamonds, show only HF TR2 signal whereas the same sample undergone high energy (20 MeV) electron irradiation and thermal annealing demonstrates rise of HF TR1 signal. The same HF TR1 signals appear in the process of fabrication of fluorescent nanodiamonds from micron-size synthetic diamond precursors. Results obtained allow unambiguous attribution of the half-field TR1 EPR signals with g{sub HF1} = 4.26, observed in nano- and micron-diamond powders, to triplet negatively charged nitrogen-vacancy centers. These signals are proposed as reliable and convenient fingerprints in both qualitative and quantitative study of fluorescent nano- and micron-diamonds.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactive growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Seasonal controls on dynamic hyporheic zone redox biogeochemistry

Hyporheic zones (where surface water and groundwater mix in streambeds) play a critical role in the movement of chemicals within watersheds, particularly in upland headwater streams. Seasonal hydrology controls the expansion and contraction of hyporheic zones, with greater downwelling oxic river water influence during periods of peak river discharge (linked to snowmelt), and greater influence of upwelling anoxic groundwater during periods of low- and base-flow. Through this work, we aimed to quantify upwelling and downwelling fluxes across seasons and assess the impact of these dynamics on microbial community assembly and geochemical gradients at East River, Colorado. Further, we performed high spatial resolution sampling to capture heterogeneous mixing patterns around a characteristic meander on the river and developed reactive transport models to explain seasonal patterns of manganese (Mn) cycling in riverbed sediments. We were able to measure a dominant period of downwelling river water associated with high river discharge in Spring 2017 that led to the mixing of microbial communities across a 60-cm depth profile through the riverbed at three locations around the meander, and higher rates of aerobic respiration via delivery of dissolved oxygen (O2) and dissolved organic carbon (DOC). Conversely, we demonstrated that depth-resolved microbial communities became more distinct and stratified across a depth gradient during periods of low- and base-flow when upwelling groundwater exerted more influence in the riverbed. We also observed an increase in Mn concentrations within deeper streambed sediments during the baseflow season. Reactive transport models were developed to understand seasonal changes in Mn cycling in the streambed because Mn oxides influence the mobility of other metals in streams. In field observations and models, dissolved Mn is flushed from the streambed during spring snowmelt. A shift to upwelling conditions over the subsequent baseflow period allows for groundwater rich in dissolved Mn to mix with oxygenated river water in the shallow subsurface, resulting in net accumulation of Mn-oxides until the bed freezes in winter. We also developed models for hydrograph scenarios with snowmelt events of various size and timing. Our scenarios suggest that in years with less snowpack and a longer baseflow season, Mn oxidation will be favored in the upper riverbed sediments over more of the year, which may increase the sorption capacity of the streambed for other metals. Finally, we assessed fine-scale geochemical and hydrologic heterogeneity in the meandering riverbed by sampling pore water at 20 cm depth across more than 100 locations in August 2018. Sample locations span distinct zones of up-welling groundwater that contrast against dominant down-welling conditions. Clear differences in carbon quality and concentrations of redox sensitive solutes were detected between these zones, highlighting the importance of understanding heterogeneity at small scales across streambeds. Geochemical differences were associated with differences in microbial assemblage, but microbial diversity was generally uniform and high across all locations at the same depth, regardless of the extent of groundwater influence.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1978

CAVE3: A general transient heat transfer computer code utilizing eigenvectors and eigenvalues

The method of solution is a hybrid analytical numerical technique which utilizes eigenvalues and eigenvectors. The method is inherently stable, permitting large time steps even with the best of conductors with the finest of mesh sizes which can provide a factor of five reduction in machine time compared to conventional explicit finite difference methods when structures with small time constants are analyzed over long time periods. This code will find utility in analyzing hypersonic missile and aircraft structures which fall naturally into this class. The code is a completely general one in that problems involving any geometry, boundary conditions and materials can be analyzed. This is made possible by requiring the user to establish the thermal network conductances between nodes. Dynamic storage allocation is used to minimize core storage requirements. This report is primarily a user's manual for CAVE3 code. Input and output formats are presented and explained. Sample problems are included which illustrate the usage of the code as well as establish the validity and accuracy of the method.

Palmieri, J. V.↗
NASA NTRS1985

Large-cell Monte Carlo renormalization of irreversible growth processes

Monte Carlo sampling is applied to a recently formulated direct-cell renormalization method for irreversible, disorderly growth processes. Large-cell Monte Carlo renormalization is carried out for various nonequilibrium problems based on the formulation dealing with relative probabilities. Specifically, the method is demonstrated by application to the 'true' self-avoiding walk and the Eden model of growing animals for d = 2, 3, and 4 and to the invasion percolation problem for d = 2 and 3. The results are asymptotically in agreement with expectations; however, unexpected complications arise, suggesting the possibility of crossovers, and in any case, demonstrating the danger of using small cells alone, because of the very slow convergence as the cell size b is extrapolated to infinity. The difficulty of applying the present method to the diffusion-limited-aggregation model, is commented on.

Nakanishi, H.↗