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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 sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Impact of Pretreatment Combined {sup 18}F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging on Radiation Therapy Treatment Decisions in Locally Advanced Breast Cancer

Purpose: To assess the diagnostic performance of pretreatment {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography ({sup 18}F-FDG PET/CT) and its impact on radiation therapy treatment decisions in patients with locally advanced breast cancer (LABC). Methods and Materials: Patients with LABC with Eastern Cooperative Oncology Group performance status <2 and no contraindication to neoadjuvant chemotherapy, surgery, and adjuvant radiation therapy were enrolled on a prospective trial. All patients had pretreatment conventional imaging (CI) performed, including bilateral breast mammography and ultrasound, bone scan, and CT chest, abdomen, and pelvis scans performed. Informed consent was obtained before enrolment. Pretreatment whole-body {sup 18}F-FDG PET/CT scans were performed on all patients, and results were compared with CI findings. Results: A total of 154 patients with LABC with no clinical or radiologic evidence of distant metastases on CI were enrolled. Median age was 49 years (range, 26-70 years). Imaging with PET/CT detected distant metastatic disease and/or locoregional disease not visualized on CI in 32 patients (20.8%). Distant metastatic disease was detected in 17 patients (11.0%): 6 had bony metastases, 5 had intrathoracic metastases (pulmonary/mediastinal), 2 had distant nodal metastases, 2 had liver metastases, 1 had pulmonary and bony metastases, and 1 had mediastinal and distant nodal metastases. Of the remaining 139 patients, nodal disease outside conventional radiation therapy fields was detected on PET/CT in 15 patients (10.8%), with involvement of ipsilateral internal mammary nodes in 13 and ipsilateral level 5 cervical nodes in 2. Conclusions: Imaging with PET/CT provides superior diagnostic and staging information in patients with LABC compared with CI, which has significant therapeutic implications with respect to radiation therapy management. Imaging with PET/CT should be considered in all patients undergoing primary staging for LABC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

H-Mediated Magnetic Interactions between Layers in a 2D Mn II -Dicyanamide Polymer: Neutron Diffraction, DFT, and Quantum Monte Carlo Calculations: H-Mediated Magnetic Interactions between Layers in a 2D Mn II -Dicyanamide Polymer: Neutron Diffraction, DFT, and Quantum Monte Carlo Calculations

We report neutron-diffraction investigations of the quasi-2D Mn-II(dca)(2)(pym)(H2O) (pym = N2C4H4) compound, where high-spin Mn-II ions are bridged by dicyanamide anions, [N(CN)(2)](-) (herein abbreviated dca). Inside the layers, Mn2+ ions are connected by single or double dca bridges. The magnetic phase diagram was established by neutron diffraction on a single crystal. In the low-field phase, the Mn-II ions are antiferro-magnetically ordered in the layers, with moments nearly parallel to the c axis, and the layers are antiferromagnetically coupled. The spin-flop phase corresponds to ferromagnetic coupling between the antiferromagnetic layers, in which the Mn-II moments are nearly perpendicular to the c axis. The induced spin-density distribution in the paramagnetic phase, determined by polarized neutron diffraction, visualizes the super-exchange pathways through the dca ligands within the layers and through H bonding between neighboring layers. The theoretical spin density obtained by bidimensional periodic DFT calculations is compared with the experimental results. Furthermore, quantum Monte Carlo simulations have been performed to compare the DFT results with experimental susceptibility measurements.

density functional calculations↗
DOE OSTI2018

Dual-Energy CT Pulmonary Angiography: Quantification of Disease Burden and Impact on Management

Purpose of Review: Computed tomography pulmonary angiography (CTPA) has become the imaging modality of choice for patients with suspected pulmonary embolism (PE). Post-processing techniques currently available for dual-energy CT pulmonary angiography (DE-CTPA) enhance image quality and provide additional value in the diagnosis of PE. The objective of this article is to summarize these recent developments and discuss the appropriate use of DE-CTPA post-processing applications. Recent Findings: DE-CTPA post-processing applications enable reconstruction of virtual monoenergetic images (VMI) and color-coded iodine-perfusion maps to increase contrast conditions and visualize lung perfusion defects in case of embolic occlusion of pulmonary arteries. Both techniques revealed a superior diagnostic performance for the detection of pulmonary emboli and assessment of the pulmonary perfusion compared to the standard image reconstructions. Summary: DE-CTPA is a well-established method for excluding or diagnosing PE. Continued developments in DE-CTPA post-processing techniques improve patient management and allow for a quantification of disease burden.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Investigation of Nanoparticle Degradation in Hydrogen Fuel Cell Systems through Automated Electron Microscopy

Proton exchange membrane fuel cells (PEMFC) are promising devices for the deployment of hydrogen-powered heavy-duty vehicles, providing a higher efficiency for similar driving range and fueling time than the existing ones. However, PEMFCs still encounter durability challenges mainly due to catalyst degradation in the cathode. Mitigating these performance losses requires a better understanding of the degradation mechanisms under heavy-duty accelerated stress tests (ASTs) [1]. Scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDS) are key tools for the analysis of Pt and PtCo nanoparticle size, spatial distribution and composition [2]. Electron tomography is also used to determine the rate and type of degradation of catalyst nanoparticles as a function of their position on the carbon support. In this work, automated data acquisition software, paired with a custom Python code, have been used to study the effect of different accelerated stress tests (ASTs) on nanoparticle coarsening [2]. Figure 1 shows high-angle annular dark-field (HAADF)-STEM images and EDS maps comparing the cathodes of membrane electrode assemblies (MEAs) following an electrocatalyst AST performed under H2/N2 with that of the heavy-duty AST performed under H2/air. We will discuss how AST conditions affect considerably the spatial distribution of the nanoparticles across the electrode between the membrane and microporous layer. Although the median particle size increased more in the MEA aged under the heavy-duty AST, as determined using a high-throughput image analysis, the quantitative EDS measurements demonstrate that the electrocatalyst AST resulted in more Pt and Co dissolution from the cathode, which is another important indicator of electrocatalyst degradation. We will further present the impact of the relative humidity (% RH) on the degradation mechanisms demonstrated using the same approach. Electron tomography has been used to distinguish the Pt nanoparticles residing on the carbon support surface (exterior) from those within the pore structure (interior) in order to determine the relative stability of interior and exterior nanoparticles. As shown in Figure 2, we will compare the Pt catalyst particle size at the beginning of test (BOT) and end of test (EOT), and discuss the importance of automating the electron tomography workflow, i.e. acquisition, reconstruction, and visualization, to increase sampling and determine the standard deviation of these measurement. The outlook for utilizing low-dose cryo-tomography for limiting damage to the catalyst, support, and especially proton-conducting ionomer will also be discussed [3].

Amichi, Lynda↗
DOE OSTI2020

Supercooled liquid sulfur maintained in three-dimensional current collector for high-performance Li-S batteries

In lithium-sulfur (Li-S) chemistry, the electrically/ionically insulating nature of sulfur and Li 2 S leads to sluggish electron/ion transfer kinetics for sulfur species conversion. Sulfur and Li 2 S are recognized as solid at room temperature, and solid-liquid phase transitions are the limiting steps in Li-S batteries. Here, we visualize the distinct sulfur growth behaviors on Al, carbon, Ni current collectors and demonstrate that (i) liquid sulfur generated on Ni provides higher reversible capacity, faster kinetics, and better cycling life compared to solid sulfur; and (ii) Ni facilitates the phase transition (e.g., Li 2 S decomposition). Accordingly, light-weight, 3D Ni-based current collector is designed to control the deposition and catalytic conversion of sulfur species toward high-performance Li-S batteries. This work provides insights on the critical role of the current collector in determining the physical state of sulfur and elucidates the correlation between sulfur state and battery performance, which will advance electrode designs in high-energy Li-S batteries.

25 ENERGY STORAGE↗
DOE OSTI2014

Estimating contact rates at a mass gathering by using video analysis: a proof-of-concept project

Current approaches for estimating social mixing patterns and infectious disease transmission at mass gatherings have been limited by various constraints, including low participation rates for volunteer-based research projects and challenges in quantifying spatially and temporally accurate person-to-person interactions. We developed a proof-of-concept project to assess the use of automated video analysis for estimating contact rates of attendees of the GameFest 2013 event at Rensselaer Polytechnic Institute (RPI) in Troy, New York. Video tracking and analysis algorithms were used to estimate the number and duration of contacts for 5 attendees during a 3-minute clip from the RPI video. Attendees were considered to have a contact event if the distance between them and another person was ≤1 meter. Contact duration was estimated in seconds. We also simulated 50 attendees assuming random mixing using a geospatially accurate representation of the same GameFest location. The 5 attendees had an overall median of 2 contact events during the 3-minute video clip (range: 0 6). Contact events varied from less than 5 seconds to the full duration of the 3- minute clip. The random mixing simulation was visualized and presented as a contrasting example. We were able to estimate the number and duration of contacts for five GameFest attendees from a 3-minute video clip that can be compared to a random mixing simulation model at the same location. In conclusion, the next phase will involve scaling the system for simultaneous analysis of mixing patterns from hours-long videos and comparing our results with other approaches for collecting contact data from mass gathering attendees.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Extrapolation Domains for Aggregating Environmental Outcomes from Local to Regional Levels

Billions of dollars are invested every year to run field experiments to quantify the response of crops to new technologies and associated environmental outcomes. Given the diversity of environments where crop production occurs, conducting these research studies without a robust framework for research site selection and upscaling results to larger spatial scales is inefficient. In this project, researchers from the University of Nebraska-Lincoln used their unique Technology Extrapolation Domains framework (TED) as a tool to guide the selection of experimental sites and as basis for aggregating and validating environmental outcomes from local to regional levels. In the present project, we first used the TED framework to evaluate the current distribution and area coverage of the current SMARTFARM sites. The purpose was to showcase how it is possible to use the TED framework to guide site selection and extrapolate results over space. Additionally, the original TED framework was expanded to account for other factors influencing environmental outcomes by inclusion of three additional variables: soil organic matter, soil texture, and topographic wetness index. The resulting expanded framework (TED-E) was validated using nitrogen (N) losses from corn in the United States as a case study. To do so, we used N balance as a proxy to N losses and we evaluated the capacity of the framework to explain variation in N balance across fields and across countries. We found that the TED-E has substantially higher predictive power than the original TED framework to explain spatial variation in N balance. However, improvements in predictive power with the TED-E tool come at the expense of a higher number of TEDs needed to achieve a given crop area coverage compared with the original TED framework. We conclude that the new TED-E framework can help aggregate and extrapolate environmental outcomes from research sites to regional levels and improve the visualization of their spatial patterns across the United States. An online version of the framework is available at: https://www.toolted.org/

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1972

Stellar ultraviolet colors and interstellar extinction

A sample of celescope results is studied. Most of the sample stars belong to the Orion and Vela regions. Stars with visual excess E(B-V) less than 0.05 are selected in order to derive relationships of intrinsic color index versus spectral type. The resulting intrinsic color-color relations are compared with existing blanketed and unblanketed model calculations. Finally, the preceding intrinsic relations are utilized to derive some results on interstellar extinction. Owing to the rather large scatter in the celescope data, the Vela stars give the more significant results because their visible excess E(B-V) is, in general, larger than that for the Orion stars.

Peytremann, E.↗
NASA NTRS1982

Resonant entrainment of a confined pulsed jet

This paper reports the discovery of a new resonant entrainment phenomenon associated with a confined, pulsed jet flow. It was found that a confined jet, when pulsed at an organ-pipe resonant frequency of the confinement tube, experiences greatly enhanced entrainment and mixing near the exit end of the confinement tube compared to a steady confined jet. The mixing and entrainment rates for the resonantly pulsed confined jet approach, and in some cases slightly exceed, those for an unconfined pulsed jet. Both visual and quantitative evidence of this phenomenon is presented. The new effect should be of considerable interest in ejector and combustor design, both of which benefit from any enhancement in mixing between a primary and a secondary flow

Parikh, P. G.↗
NASA NTRS1989

Diffuse interstellar clouds as a chemical laboratory - The chemistry of diatomic carbon species

The chemistry of C2, CH, and CO in diffuse interstellar clouds is analyzed and compared to absorption line measurements toward background stars. Analytical expressions in terms of column densities are derived for the rate equations. The results indicate that in clouds with 4 mag of visual extinction, the abundance of C+ has to decrease by a factor of about 15 from the value traditionally used for clouds with 1 mag of extinction. The rate coefficients for the reactions C+ + CH - C2+ + H and C+ + H2 - CH2+ + h-nu need to be reduced from previous estimates. Chemical arguments are presented for the revised rate coefficients.

Federman, S. R.↗
NASA NTRS1991

Effect of short-term exposure to stereoscopic three-dimensional flight displays on real-world depth perception

High-fidelity color pictorial displays that incorporate depth cues in the display elements are currently available. Depth cuing applied to advanced head-down flight display concepts potentially enhances the pilot's situational awareness and improves task performance. Depth cues provided by stereopsis exhibit constraints that must be fully understood so depth cuing enhancements can be adequately realized and exploited. A fundamental issue (the goal of this investigation) is whether the use of head-down stereoscopic displays in flight applications degrade the real-world depth perception of pilots using such displays. Stereoacuity tests are used in this study as the measure of interest. Eight pilots flew repeated simulated landing approaches using both nonstereo and stereo 3-D head-down pathway-in-the-sky displays. At this decision height of each approach (where the pilot changes to an out-the-window view to obtain real-world visual references) the pilots changed to a stereoacuity test that used real objects. Statistical analysis of stereoacuity measures (data for a control condition of no exposure to any electronic flight display compared with data for changes from nonstereo and from stereo displays) reveals no significant differences for any of the conditions. Therefore, changing from short-term exposure to a head-down stereo display has no more effect on real-world relative depth perception than does changing from a nonstereo display. However, depth perception effects based on sized and distance judgements and on long-term exposure remain issues to be investigated.

Busquets, Anthony M.↗
NASA NTRS1999

Comparison of Techniques for Non-Intrusive Fuel Drop Size Measurements in a Subscale Gas Turbine Combustor

In aviation gas turbine combustors, many factors, such as the degree and extent of fuel/air mixing and fuel vaporization achieved prior to combustion, influence the formation of undesirable pollutants. To assist in analyzing the extent of fuel/air mixing, flow visualization techniques have been used to interrogate the fuel distributions during subcomponent tests of lean-burning fuel injectors. Discrimination between liquid and vapor phases of the fuel was determined by comparing planar laser-induced fluorescence (PLIF) images, elastically-scattered light images, and phase/Doppler interferometer measurements. Estimates of Sauter mean diameters are made by ratioing PLIF and Mie scattered intensities for various sprays, and factors affecting the accuracy of these estimates are discussed. Mie calculations of absorption coefficients indicate that the fluorescence intensities of individual droplets are proportional to their surface areas, instead of their volumes, due to the high absorbance of the liquid fuel for the selected excitation wavelengths.

Zaller, Michelle↗
NASA NTRS1999

"Tools For Analysis and Visualization of Large Time- Varying CFD Data Sets"

During the four years of this grant (including the one year extension), we have explored many aspects of the visualization of large CFD (Computational Fluid Dynamics) datasets. These have included new direct volume rendering approaches, hierarchical methods, volume decimation, error metrics, parallelization, hardware texture mapping, and methods for analyzing and comparing images. First, we implemented an extremely general direct volume rendering approach that can be used to render rectilinear, curvilinear, or tetrahedral grids, including overlapping multiple zone grids, and time-varying grids. Next, we developed techniques for associating the sample data with a k-d tree, a simple hierarchial data model to approximate samples in the regions covered by each node of the tree, and an error metric for the accuracy of the model. We also explored a new method for determining the accuracy of approximate models based on the light field method described at ACM SIGGRAPH (Association for Computing Machinery Special Interest Group on Computer Graphics) '96. In our initial implementation, we automatically image the volume from 32 approximately evenly distributed positions on the surface of an enclosing tessellated sphere. We then calculate differences between these images under different conditions of volume approximation or decimation.

Wilhelms, Jane↗
NASA NTRS1985

Portable instant display and analysis reflectance spectrometer

A portable analysis spectrometer (10) for field mineral identification is coupled to a microprocessor (11) and memory (12) through a bus (13) and A/D converter (14) to display (16) a spectrum of reflected radiation in a band selected by an adjustable band spectrometer (20) and filter (23). A detector array (21) provides output signals at spaced frequencies within the selected spectrometer band which are simultaneously converted to digital form for display. The spectrum displayed is compared with a collection of spectra for known minerals. That collection is stored in memory and selectively displayed with the measured spectrum, or stored in a separate portfolio. In either case, visual comparison is made. Alternatively, the microprocessor may use an algorithm to make the comparisons in search for the best match of the measured spectrum with one of the stored spectra to identify the mineral in the target area.

Goetz, Alexander F. H.↗
NASA NTRS2014

General Aviation Flight Test of Advanced Operations Enabled by Synthetic Vision

A flight test was performed to compare the use of three advanced primary flight and navigation display concepts to a baseline, round-dial concept to assess the potential for advanced operations. The displays were evaluated during visual and instrument approach procedures including an advanced instrument approach resembling a visual airport traffic pattern. Nineteen pilots from three pilot groups, reflecting the diverse piloting skills of the General Aviation pilot population, served as evaluation subjects. The experiment had two thrusts: 1) an examination of the capabilities of low-time (i.e., <400 hours), non-instrument-rated pilots to perform nominal instrument approaches, and 2) an exploration of potential advanced Visual Meteorological Conditions (VMC)-like approaches in Instrument Meteorological Conditions (IMC). Within this context, advanced display concepts are considered to include integrated navigation and primary flight displays with either aircraft attitude flight directors or Highway In The Sky (HITS) guidance with and without a synthetic depiction of the external visuals (i.e., synthetic vision). Relative to the first thrust, the results indicate that using an advanced display concept, as tested herein, low-time, non-instrument-rated pilots can exhibit flight-technical performance, subjective workload and situation awareness ratings as good as or better than high-time Instrument Flight Rules (IFR)-rated pilots using Baseline Round Dials for a nominal IMC approach. For the second thrust, the results indicate advanced VMC-like approaches are feasible in IMC, for all pilot groups tested for only the Synthetic Vision System (SVS) advanced display concept.

Glaab, Louis J.↗
NASA NTRS2014

Flow Separation Control Over a Ramp Using Sweeping Jet Actuators

Flow separation control on an adverse-pressure-gradient ramp model was investigated using various flow-control methods in the NASA Langley 15-Inch Wind Tunnel. The primary flow-control method studied used a sweeping jet actuator system to compare with more classic flow-control techniques such as micro-vortex generators, steady blowing, and steady- and unsteady-vortex generating jets. Surface pressure measurements and a new oilflow visualization technique were used to characterize the effects of these flow-control actuators. The sweeping jet actuators were run in three different modes to produce steady-straight, steady-angled, and unsteady-oscillating jets. It was observed that all of these flow-control methods are effective in controlling the separated flows on the ramp model. The steady-straight jet energizes the boundary layer by momentum addition and was found to be the least effective method for a fixed momentum coefficient. The steady-angled jets achieved better performance than the steady-straight jets because they generate streamwise vortices that energize the boundary layer by mixing high-momentum fluid with near wall low-momentum fluid. The unsteady-oscillating jets achieved the best performance by increasing the pressure recovery and reducing the downstream flow separation. Surface flow visualizations indicated that two out-of-phase counter-rotating vortices are generated per sweeping jet actuator, while one vortex is generated per vortex-generating jets. The extra vortex resulted in increased coverage, more pressure recovery, and reduced flow separation.

Koklu, Mehti↗
NASA NTRS2018

VLTI-GRAVITY Measurements of Cool Evolved Stars I. Variable Photosphere and Extended Atmosphere of the Mira Star R Peg

Context. Dynamic model atmospheres of Mira stars predict variabilities in the photospheric radius and in atmospheric molecular layers which are not yet strongly constrained by observations. Aim. Here we measure the variability of the oxygen-rich Mira star R Peg in near-continuum and molecular bands. Methods. We used near-infrared K-band spectro-interferometry with a spectral resolution of about 4000 obtained at four epochs between post-maximum and minimum visual phases employing the newly available GRAVITY beam combiner at the Very Large Telescope Interferometer (VLTI). Results. Our observations show a continuum radius that is anti-correlated with the visual lightcurve. Uniform disc (UD) angular diameters at a near-continuum wavelength of 2.24 m are steadily increasing with values of 8.7 0.1 mas, 9.4 0.1 mas, 9.8 0.1 mas, and 9.9 0.1 mas at visual phases of 0.15, 0.36, 0.45, 0.53, respectively. UD diameters at a bandpass around 2.05 m, dominated by water vapour, follow the near-continuum variability at larger UD diameters between 10.7 mas and 11.7 mas. UD diameters at the CO 2-0 bandhead, instead, are correlated with the visual lightcurve and anti-correlated with the near-continuum UD diameters, with values between 12.3 mas and 11.7 mas. Conclusions. The observed anti-correlation between continuum radius and visual lightcurve is consistent with an earlier study of the oxygen-rich Mira S Lac, and with recent 1D CODEX dynamic model atmosphere predictions. The amplitude of the variation is comparable to the earlier observations of S Lac, and smaller than predicted by CODEX models. The wavelength-dependent visibility variations at our epochs can be reproduced by a set of CODEX models at model phases between 0.3 and 0.6. The anti-correlation of water vapour and CO contributions at our epochs suggests that these molecules undergo different processes in the extended atmosphere along the stellar cycle. The newly available GRAVITY instrument is suited to conducting longer time series observations, which are needed to provide strong constraints on the model-predicted intra- and inter-cycle variability.

photospheric radius↗
NASA NTRS2021

Assessing Cyanobacterial Frequency and Abundance at Surface Waters Near Drinking Water Intakes Across the United States

This study presents the first large-scale assessment of cyanobacterial frequency and abundance of surface water near drinking water intakes across the United States. Public water systems serve drinking water to nearly 90% of the United States population. Cyanobacteria and their toxins may degrade the quality of finished drinking water and can lead to negative health consequences. Satellite imagery can serve as a cost-effective and consistent monitoring technique for surface cyanobacterial blooms in source waters and can provide drinking water treatment operators information for managing their systems. This study uses satellite imagery from the European Space Agency’s Ocean and Land Colour Instrument (OLCI) spanning June 2016 through April 2020. At 300-m spatial resolution, OLCI imagery can be used to monitor cyanobacteria in 685 drinking water sources across 285 lakes in 44 states, referred to here as resolvable drinking water sources. First, a subset of satellite data was compared to a subset of responses (n = 84) submitted as part of the U.S. Environmental Protection Agency’s fourth Unregulated Contaminant Monitoring Rule (UCMR 4). These UCMR 4 qualitative responses included visual observations of algal bloom presence and absence near drinking water intakes from March 2018 through November 2019. Overall agreement between satellite imagery and UCMR 4 qualitative responses was 94% with a Kappa coefficient of 0.70. Next, temporal frequency of cyanobacterial blooms at all resolvable drinking water sources was assessed. In 2019, bloom frequency averaged 2% and peaked at 100%, where 100% indicated a bloom was always present at the source waters when satellite imagery was available. Monthly cyanobacterial abundances were used to assess short-term trends across all resolvable drinking water sources and effect size was computed to provide insight on the number of years of data that must be obtained to increase confidence in an observed change. Generally, 2016-2020 was an insufficient time period for confidently observing changes at these source waters; on average, a decade of satellite imagery would be required for observed environmental trends to outweigh variability in the data. However, five source waters did demonstrate a sustained short-term trend, with one increasing in cyanobacterial abundance from June 2016 to April 2020 and four decreasing.

remote sensing↗