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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

The rocket ultraviolet spectrum of the planetary nebula NGC 7027

An ultraviolet spectrum of NGC 7027 was obtained with a rocket-borne telescope. The observed fluxes are given on an absolute basis and upper limits are given for the strongest predicted lines which were not observed. The extinction correction was made on the basis of the observed and calculated line ratios for the hydrogenic recombination line of He 2 at 1640A to H beta. The extinction is in agreement with ground based determinations. When corrected for extinction the C 4 resonance line at 1549A is in good agreement with the intensity calculated from models, but the C 3 intercombination line at 1909A is a factor of ten too bright. The addition of dielectronic recombination to the models sufficiently changes the C 3 concentration to reduce the discrepancy to a factor of four. The abundance of carbon is assumed to be 2 x 0.0001 that of hydrogen. Using carbon abundances for the sun, this discrepancy disappears and there must be attenuation in the C 4 line. Since the optical depth is approximately 10,000 at the line center, no appreciable number of absorbing grains can exist in the C 4 producing region of the nebula.

Bohlin, R. C.↗
NASA NTRS2009

Chandra Detection of a Parsec Scale Wind in the Broad Line Radio Galaxy 3C 382

We present unambiguous evidence for a parsec scale wind in the Broad-Line Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN whereby an outflow has been measured with X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C 382 has revealed the presence of several high ionization absorption lines in the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are blue-shifted with respect to the systemic velocity of 3C 382 by -840+/-60 km/s and are resolved by Chandra with a velocity width of sigma = 340+/-70 km/s. The outflow appears to originate from a single zone of gas of column density N(sub H) = 1.3 x 10(exp 21)/sq cm and ionization parameter log(E/erg/cm/s) = 2.45. From the above measurements we calculate that the outflow is observed on parsec scales, within the likely range from 10-1000 pc, i.e., consistent with an origin in the Narrow Line Region. Finally we also discuss the possibility of a much faster (0.1c) outflow component, based on a blue-shifted iron K(alpha) emission line in the Suzaku observation of 3C 382, which could have an origin in an accretion disk wind.

Reeves, J. N.↗
NASA NTRS1986

Evidence for coronal turbulence in a quiescent active region

The first evidence for nonthermal broadening of X-ray lines in a quiescent active region was based on a single observation of a limb active region by the Flat Crystal Spectrometer (FCS) on the SMM satellite, reported by Acton et al. (1981). With the renewal of SMM operations, the FCS has been used to further investigate this phenomenon. On April 28, 1984 a map of Mg XI resonance line profiles was made for a bright area in NOAA Active Region 4474 during a nonflaring period. The narrowest line profiles are consistent with the nominal instrumental width plus a thermal width equivalent to about 3 million K, the temperature derived from line ratios of O VIII, Ne IX, and Mg XI. The broadest line profiles are consistent with the instrumental width plus a thermal width equivalent to about 7 million K, but a substantial amount of plasma at this temperature would result in much greater flux in the FCS higher-temperature channels than was seen. If the excess width is attributed solely to plasma turbulence, the corresponding velocity would be about 40 + or - 10 km/s.

Saba, Julia L. R.↗
DOE OSTI2017

Crack detection in crystalline silicon solar cells using dark-field imaging

The high capital expenditure (capex) necessary to manufacture crystalline silicon PV modules negatively affects the levelized cost of electricity (¢/kWh) and critically impacts the rate at which the PV industry can scale up. Wafer, cell, and module fabrication with thin free-standing silicon wafers is one key to reduce capex. Thin wafers reduce capex associated with silicon refining and wafer fabrication, which together sum to 58% of the total capex of silicon module manufacturing. In addition, thin wafers directly and significantly reduce variable costs. However, introducing 50 μm thin free-standing wafers into today’s manufacturing lines result in cracking, creating a yield-based disincentive. Due to the brittle nature of silicon, wafer breakage is the major concern due to the high stress that is induced during processes in manufacturing lines. In this paper, we describe an improved method for edge micro-crack detection that can help enable low-capex, thin free-standing Si wafers. We present a method of detecting and measuring cracks along wafer edges by using a dark-field IR scattering imaging technique which enables detection of edge cracks at the micron scale.

14 SOLAR ENERGY↗
DOE OSTI2021

Lattice Design of the Beam Transfer Line (BTL) from PIP-II LINAC to the Booster at Fermilab

PIP-II beam transfer line (BTL) to transport the beam from PIP-II Linac to the Booster ring at Fermilab. The latest design eliminates rolling the dipoles in the beam line to cross over the Tevatron tunnel. Also re-designed is the lattice in the region of the Booster Injection to meet the request of the civil construction needs and accommodate the constrains of the Booster injection request. A beam line to the beam absorber (BAL) is designed based on the request from the results of Mars simulations and ANASYS calculation of the absorber. Simulations with dipole and quadrupole field errors for the Beam Transport Line (BTL) to the Booster, which provides the specifications for all the magnets and Power supplies, will be presented too.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Moving Evidence Forward: Addressing the Barriers to Evidence-Based Practice in Radiotherapy

Improving the quality of care is an ongoing challenge for medical professionals in the Canadian healthcare system. One generally accepted method of improving health outcomes has been the clinical implementation of evidence-based practice. Historically, the barrier in clinical settings has been efficient access to reliable information. Point-of-care (P-O-C) tools have been proven to be effective and help promote evidence-based practice in professions outside radiation therapy. To examine the potential usefulness of a P-O-C tool for radiation therapists, a Canada-wide survey was distributed to practicing radiation therapists. Results showed a clear desire by radiation therapists for a P-O-C tool. Sixty-nine percent of surveyed practitioners stated that having a practitioner-focused evidence resource would change their daily work practice, but stipulated that the proper integration of resources into the day-to-day workplace is crucial to supporting clinical evidence-based decision-making. Study participants also highlighted several barriers to their ability to do so, including access to evidence-based data, differing organizational research philosophies and practices, lack of resources to promote discipline-specific practitioner research, and necessary integration of educational and mentoring programs into daily practices. Although they have not been found to be an all-encompassing remedy, P-O-C tools have the potential to aid front-line healthcare providers in fostering evidence-based practice.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2023

Evaluating Greenland Surface-Mass-Balance and Firn-Densification Data Using ICESat-2 Altimetry

Surface-mass-balance (SMB) and firn-densification (FD) models are widely used in altimetry studies as a tool to separate atmospheric-driven from ice-dynamics-driven ice-sheet mass changes and to partition observed volume changes into ice-mass changes and firn-air-content changes. Until now, SMB models have been principally validated based on comparison with ice core and weather station data or comparison with widely separated flight radar-survey flight lines. Firn-densification models have been primarily validated based on their ability to match net densification over decades, as recorded in firn cores, and the short-term time-dependent component of densification has rarely been evaluated at all. The advent of systematic ice-sheet-wide repeated ice-surface-height measurements from ICESat-2 (the Ice Cloud, and land Elevation Satellite, 2) allows us to measure the net surface-height change of the Greenland ice sheet at quarterly resolution and compare the measured surface-height differences directly with those predicted by three FD–SMB models: MARv3.5.11 (Modèle Atmosphérique Régional version 3.5.11) and GSFCv1.1 and GSFCv1.2 (the Goddard Space Flight Center FD–SMB models version 1.1 and 1.2). By segregating the data by season and elevation, and based on the timing and magnitude of modelled processes in areas where we expect minimal ice-dynamics-driven height changes, we investigate the models' accuracy in predicting atmospherically driven height changes. We find that while all three models do well in predicting the large seasonal changes in the low-elevation parts of the ice sheet where melt rates are highest, two of the models (MARv3.5.11 and GSFCv1.1) systematically overpredict, by around a factor of 2, the magnitude of height changes in the high-elevation parts of the ice sheet, particularly those associated with melt events. This overprediction seems to be associated with the melt sensitivity of the models in the high-elevation part of the ice sheet. The third model, GSFCv1.2, which has an updated high-elevation melt parameterization, avoids this overprediction.

Benjamin E. Smith↗
DOE OSTI2017

The Sloan Digital Sky Survey Reverberation Mapping Project: Composite Lags at z ≤ 1

We present composite broad-line region (BLR) reverberation mapping lag measurements for H α , H β , He ii λ 4686, and Mg ii for a sample of 144, z ≲ 1 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Using only the 32-epoch spectroscopic light curves in the first six-month season of SDSS-RM observations, we compile correlation function measurements for individual objects and then coadd them to allow the measurement of the average lags for our sample at mean redshifts of 0.4 (for H α ) and ∼0.65 (for the other lines). At similar quasar luminosities and redshifts, the sample-averaged lag decreases in the order of Mg ii, H α , H β , and He ii. This decrease in lags is accompanied by an increase in the mean line width of the four lines, and is roughly consistent with the virialized motion for BLR gas in photoionization equilibrium. These are among the first RM measurements of stratified BLR structure at z > 0.3. Dividing our sample by luminosity, H α shows clear evidence of increasing lags with luminosity, consistent with the expectation from the measured BLR size–luminosity relation based on H β . The other three lines do not show a clear luminosity trend in their average lags due to the limited dynamic range of luminosity probed and the poor average correlation signals in the divided samples, a situation that will be improved with the incorporation of additional photometric and spectroscopic data from SDSS-RM. We discuss the utility and caveats of composite lag measurements for large statistical quasar samples with reverberation mapping data.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

B2, B7 or B10: Which palm-based blend mandate wise to be chosen in Malaysia?

The diminishing fossil energy resources, coupled with heightened interest in the abatement of greenhouse gas emissions and concerns about energy security have motivated Malaysia to produce palm-based biodiesel and it has been started to be exported since 2006. In line with this issue, the government in Malaysia launched the palm-based biodiesel blending mandate of five percent (B5) in the federal administration of Putrajaya on 1{sup st} June 2011. This was then followed by four states: Malacca on July 11, Negeri Sembilan on August 1, Kuala Lumpur on September 1 and Selangor on October 1 of the same year but it is yet to be implemented nationwide. However what is the wise blend mandate to be chosen? Thus, this paper seeks to examine the possible impact of various blend mandates implementation (B2, B7 and B10) on the palm oil industry market variables (stock and price) since the main aim of biodiesel industry in Malaysia is to reduce domestic palm oil stock to below one million tones and provide a floor price to support Crude Palm Oil (CPO) prices at RM2,000 per tonne. A structural econometric model consisting of nine structural equations and three identities was proposed in this study. The model has been estimated by two stage least squares (2SLS) method using annual data for the period 1976-2013. The study indicates that counterfactual simulation of a decrease from B5 to B2 predicts a decrease (11.2 per cent) in CPO domestic consumption for biodiesel usage, 731.02 per cent reduction in CPO stock and an increase of 27.41 percent in domestic price of CPO. However the increase in the blend mandate from B5 to B7 and B10 suggest that domestic consumption of CPO for biodiesel purpose increase 7.40 and 18.55 percent respectively. The interesting findings in this study suggest that no matter whether Malaysian government increase or decrease the blend mandate the increase in the price of CPO are the same with an increase of is 27.41 percent. Hence, this study suggests that the lower blend mandate is the most favourable on.+-e compared to increasing it in this short period due to high production cost of CPO prices. However, future study on economic feasibility of palm-based biodiesel has to be conducted to support this study.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

The Grism Lens-Amplified Survey from space (GLASS). III. A census of Lyα emission at z≳7 from HST spectroscopy

We present a census of Lyα emission at z≳7, utilizing deep near-infrared Hubble Space Telescope grism spectroscopy from the first six completed clusters of the Grism Lens-Amplified Survey from Space (GLASS). In 24/159 photometrically selected galaxies we detect emission lines consistent with Lyα in the GLASS spectra. Based on the distribution of signal-to-noise ratios and on simulations, we expect the completeness and the purity of the sample to be 40%–100% and 60%–90%, respectively. For the objects without detected emission lines we show that the observed (not corrected for lensing magnification) 1σ flux limits reach 5 × 10{sup −18} erg s{sup −1} cm{sup −2} per position angle over the full wavelength range of GLASS (0.8–1.7 μm). Based on the conditional probability of Lyα emission measured from the ground at z∼7, we would have expected 12–18 Lyα emitters. This is consistent with the number of detections, within the uncertainties, confirming the drop in Lyα emission with respect to z∼6. Deeper follow-up spectroscopy, here exemplified by Keck spectroscopy, is necessary to improve our estimates of completeness and purity and to confirm individual candidates as true Lyα emitters. These candidates include a promising source at z = 8.1. The spatial extent of Lyα in a deep stack of the most convincing Lyα emitters with 〈z〉 = 7.2 is consistent with that of the rest-frame UV continuum. Extended Lyα emission, if present, has a surface brightness below our detection limit, consistent with the properties of lower-redshift comparison samples. From the stack we estimate upper limits on rest-frame UV emission line ratios and find f{sub CIV}/f{sub Lyα}≲0.32 and f{sub CIII]}/f{sub Lyα}≲0.23, in good agreement with other values published in the literature.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Refined Telluric Absorption Correction for Low-resolution Ground-based Spectroscopy: Resolution and Radial Velocity Effects in the O{sub 2}A-band for Exoplanets and K i Emission Lines

Telluric correction of spectroscopic observations is either performed via standard stars that are observed close in time and airmass along with the science target, or recently growing in importance, by theoretical telluric absorption modeling. Both approaches work fine when the telluric lines are resolved, i.e., at a spectral resolving power larger than about 10,000, and it is sufficient to facilitate the detection of spectral features at lower resolution. However, a meaningful quantitative analysis also requires the reliable recovery of line strengths. Here, we show for the Fraunhofer A-band of molecular O{sub 2} that the standard telluric correction approach fails in this at lower spectral resolutions, as an example for the general problem. Doppler-shift-dependent errors of the restored flux may arise, which can amount to more than 50% in extreme cases, depending on the line shapes of the target spectral features. Two applications are discussed: the recovery of the O{sub 2} band in the reflected light of an Earth analog atmosphere, as facilitated potentially in the future using an orbiting starshade and a ground-based extremely large telescope; and the recovery of the intrinsic ratio of the K i lines in the post-nova V4332 Sgr tracing the optical depth of the emitting region, to exemplify the relevance using present-day instrumentation. We show how one should derive correction functions for the compensation of the error in dependence of radial velocity shift, spectral resolution, and target line-profile function by use of high-resolution atmospheric transmission modeling, which has to be solved for the individual case.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1981

Evaluation of SLAR and thematic mapper MSS data for forest cover mapping using computer-aided analysis techniques

A set of training statistics for the 30 meter resolution simulated thematic mapper MSS data was generated based on land use/land cover classes. In addition to this supervised data set, a nonsupervised multicluster block of training statistics is being defined in order to compare the classification results and evaluate the effect of the different training selection methods on classification performance. Two test data sets, defined using a stratified sampling procedure incorporating a grid system with dimensions of 50 lines by 50 columns, and another set based on an analyst supervised set of test fields were used to evaluate the classifications of the TMS data. The supervised training data set generated training statistics, and a per point Gaussian maximum likelihood classification of the 1979 TMS data was obtained. The August 1980 MSS data was radiometrically adjusted. The SAR data was redigitized and the SAR imagery was qualitatively analyzed.

Hoffer, R. M.↗
DOE OSTI2016

Strain-induced nonsymmorphic symmetry breaking and removal of Dirac semimetallic nodal line in an orthoperovskite iridate

By using a combination of heteroepitaxial growth, structure refinement based on synchrotron x-ray diffraction, and first-principles calculations, we show that the symmetry-protected Dirac line nodes in the topological semimetallic perovskite SrIrO 3 can be lifted simply by applying epitaxial constraints. In particular, the Dirac gap opens without breaking the Pbnm mirror symmetry. In virtue of a symmetry-breaking analysis, we demonstrate that the original symmetry protection is related to the n -glide operation, which can be selectively broken by different heteroepitaxial structures. Here, this symmetry protection renders the nodal line a nonsymmorphic Dirac semimetallic state. The results highlight the vital role of crystal symmetry in spin-orbit-coupled correlated oxides and provide a foundation for experimental realization of topological insulators in iridate-based heterostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Self-Broadening and Carbon-Dioxide Broadening of Lines of the H{sub 2}S Molecule

Carbon-dioxide-broadening coefficients and self-broadening coefficients of lines of the main isotopic modification of Н{sub 2}S are estimated on the basis of literature data. The J′-dependences of the above line-profile parameters of the hydrogen-sulfide molecule are examined. In the case of CO{sub 2} broadening, the half-widths of lines are calculated by a semiempirical method based on a parametric modification of the impact semiclassical model; the model parameters were determined from the fit to experimental data.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS2011

If the MODIS Aerosol Product is so Infested with Cloud Contamination, Why Does Everybody Use the Product?

The MODIS aerosol cloud mask is based on a spatial variability test, using the assumption that aerosols are more homogeneous than clouds. On top of this first line of defense are a series of additional tests based on threshold values and ratios of various MODIS channels. The goal is to eliminate clouds and keep the aerosol. How well have we succeeded? There have been several studies showing cloud contamination in the MODIS aerosol product and several alternative cloud masks proposed. There are even "competing" MODIS aerosol products that offer an alternative "cloud free" world. Are these alternative products an improvement to the old standard product? We find there is a trade-off between retrieval availability and cloud contamination, and for many applications it is better to have a little bit of cloud in the product than to not have enough product. I will review the decisions that led us to the present MODIS cloud mask, and show how it is simultaneously too liberal and too conservative, some ideas on how to make it better and why in the end it doesn't matter. I hope to inspire a spirited discussion and will be very willing to take your complaints and suggestions.

Remeer, Lorraine A.↗
NASA NTRSDate not supplied

Qualification of A Transition Edge Sensor Based Anti-Coincidence Detector for A Probe Class Mission

The Line Emission Mapper (or LEM) is an X-ray probe class mission aimed to study the physics of galaxy formation, with a large field-of-view, high-resolution transition-edge sensor (TES) microcalorimeter. Because of the diffuse and faint nature of LEM’s targets, a high-fidelity anticoincidence detector (anti-co) is essential to reduce instrument background below the level of sky background. Lying directly behind the LEM sensor, the anti-co will detect ~3 counts per second per square centimeter from background galactic cosmic rays and the secondary particles they induce to detect and flag any events that could be confused with a science photon in the 0.3-2 keV signal band of LEM. Our design spans an active region 4-cm in diameter. It consists of 12 quasiparticle-trap-assisted electrothermal-feedback (QET) channels, each with 100 parallel TESes with common bias lines. The TES is a narrow strip of Mo/Au bilayer. We present fabrication processes that maintain the transition temperature (T c ) in Mo/Au bilayer structures across the active region. We further present a new design based on a a-Si/W TES layer that has previously achieved reasonable uniformity in lab testing.

x-ray↗
DOE OSTI2018

A novel lentiviral scFv display library for rapid optimization and selection of high affinity antibodies

Highlights: • We constructed a novel scFv display library based on lentivirus vector. • Stable transduced cell lines were obtained. • Characterization of mutants showed approximately upto three fold increase in antibody affinity. Antibody display libraries have become a popular technique to screen monoclonal antibodies for therapeutic purposes. An important aspect of display technology is to generate an optimization library by changing antibody affinity to antigen through mutagenesis and screening the high affinity antibody. In this study, we report a novel lentivirus display based optimization library antibody in which Agtuzumab scFv is displayed on cell membrane of HEK-293T cells. To generate an optimization library, hotspot mutagenesis was performed to achieve diverse antibody library. Based on sequence analysis of randomly selected clones, library size was estimated approximately to be 1.6 × 10{sup 6}. Lentivirus display vector was used to display scFv antibody on cell surface and flow cytometery was performed to check the antibody affinity to antigen. Membrane bound scFv antibodies were then converted to secreted antibody through cre/loxP recombination. One of the mutant clones, M8 showed higher affinity to antigen in flow cytometery analysis. Further characterization of cellular and secreted scFv through western blot showed that antibody affinity was increased by three fold after mutagenesis. This study shows successful construction of a novel antibody library and suggests that hotspot mutagenesis could prove a useful and rapid optimization tool to generate similar libraries with various degree of antigen affinity.

60 APPLIED LIFE SCIENCES↗