Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SGE”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Winds in collision. II - An analysis of the X-ray emission from the eruptive symbiotic HM Sge

X-ray emissions from HM Sge obtained in 1981 from the HEAO-2 satellite are analyzed and compared quantitatively with observations of HM Sge made in 1980 and of HM Sge, V 1016 Cyg, and RR Tel made in 1979. The change in the X-ray emission from HM Sge between 1979 and 1981 is found to be consistent with the X-ray luminosity and/or temperature of the emitting region declining with an e-folding timescale of the order of one to several decades. Comparison with X-ray data from V 1016 Cyg and RR Tel gives a composite X-ray light curve that is also consistent with such a decline. A comparison of the X-ray observation with spectroscopic information makes it possible to constrain the properties of the X-ray emitting region: the result is consistent with emission from an optically thin region between the two stars in the system where their winds collide head on. It is also shown that the observations are inconsistent with a stellar (blackbody) source, with emission from an accretion disk around a white dwarf or a neutron star, and with emission from a single star wind from either a white dwarf or a neutron star.

Willson, L. A.↗
NASA NTRS1981

Electron densities for six planetary nebulae and HM SGE derived from the C 3 lambda 1907/1909 ratio

Electron densities for IC 418, NGC 6572, IC 1297, NGC 3242, NGC 6818, NGC 3211, and HM Sge derived from high dispersion IUE C III spectrograms are consistently higher than those derived from either surface brightness measurements of forbidden line intensity ratios in the visible. The nebulae were selected for a range of excitation classes from 3 to 9. Line splitting due to expansion velocities is observed for three objects. The great width of the lambda 1909 C III line in HM Sge suggests large expansion velocities.

Source record↗
NASA NTRS1984

Winds in collision. I - Geometric implications of the emission lines for V 1016 Cyg and HM Sge

Emission line profiles and radial velocity data obtained from spectra in the visual region are presented for V1016 Cyg and HM Sge. The profiles of the forbidden emission lines are found to be inconsistent with spherical symmetry for the hot nebular material. It is argued that part of the nebular material in a detached binary system where both stars have spontaneous winds will naturally assume the shape of a curved, roughly conical, shell. The data can be satisfactorily interpreted in terms of the interaction of a low-velocity wind from a red giant with a high-velocity wind from a white dwarf in a detached binary system. This scheme provides a natural assignment of emission line forming regions to different portions of the interaction shell and the two winds, explaining both the profiles and the velocities of the features.

Willson, L. A.↗
NASA NTRS1993

The orbit and companion of the Cepheid S Sge - A probable triple system

New radial velocities for the classical Cepheid S Sge have been obtained and combined with previous observations to derive a new orbit. The revised orbital elements are: gamma, -10.3 +/- 0.4 km/s; K, 15.5 +/- 0.2 km/s; e, 0.23 +/- 0.02; omega, 203.1 +/- 4.2 deg; T0, 39902.3 +/- 6.6 JD; P, 675.79 +/- 0.18 days; f(m), 0.239 +/- 0.010 solar masses; a sin i, 0.935 AU = 139.9 +/- 2.0 x 10 exp 6 km; s.e., 1.2 km/s. The revised elements differ very little from the orbit determined by Herbig and Moore (1952). We have also obtained low resolution IUE spectra to search for the companion. The IUE spectra show excess flux at 1800 A when compared with spectra of the single Cepheid Delta Cep at the same (B-V)0. The spectral type of the companion determined from this flux excess is A7 V to F0 V. However, the mass of such a companion (1.7 to 1.5 solar masses) is smaller than the minimum mass (2.8 solar masses) required by the mass function and an evolutionary mass of the Cepheid. We infer that the companion is itself a short period binary.

Evans, Nancy R.↗
DOE OSTI2022

PNV J00444033+4113068: Early superhumps with 0.7 mag amplitude and non-red color

Abstract In the first days of WZ Sge-type dwarf nova (DN) outbursts, the 2 : 1 resonance induces a spiral arm structure in the accretion disk, which is observed as early superhumps in optical light curves. We reports on our optical observations of an eclipsing WZ Sge-type DN PNV J00444033+4113068 during its 2021 superoutburst using the 3.8 m Seimei telescope and through the Variable Star Network collaboration. The eclipse analysis showed that its orbital period was 0.055425534(1) d. Our observations confirmed early superhumps with an amplitude of 0.7 mag, the largest amplitude among known WZ Sge-type DNe. More interestingly, its early superhumps became the reddest around their secondary minimum, whereas other WZ Sge-type DNe show the reddest color around the early superhump maximum. The spectrum around the peak of the outburst showed two double-peaked emission lines of He ii 4686 Å and Hα with a peak separation of ≥700 km s−1, supporting a very high-inclination system. With the early superhump mapping, the unique profile and color of the early superhump are successfully reproduced by an accretion disk with a vertically extended double arm structure. Therefore, a large amplitude and a unique color behavior of the early superhumps in PNV J00444033+4113068 can be explained by the 2 : 1 resonance model along with other WZ Sge-type DNe.

Tampo, Yusuke (ORCID:0000000301963936)↗
NASA NTRS1985

IUE and optical spectral scans of U Sagittae - An analysis and comparison with U Cephei

Recent optical and ultraviolet observations of U Sge are presented, and the results are compared with observations of U Cephei. The observations were carried out with: the International Ultraviolet Explorer (IUE) satellite; with the ITS scanner of the Lick Observatory; and with a Varo image-tube camera attached to a coude spectrograph. Comparison with data for U Ceph showed that U Sge is of the B7.5 V spectral type with an effective temperature of 12,250 + or 250 K, and a surface gravity of 3.9 + or - 0.1 log g. The secondary component of U Sge appears to be of the G4 III-IV spectral type. The best estimate for the distance of U Sge was 295 + or - 20 pc. Emission lines of the W Serpentis type were found in the IUE spectrum for U Sge. Although the observed fluxes for the lines were low, the powers were half as strong as those observed in U Cep. Selected emission lines of Fe II, Si II, and Si III were also found assuming solar abundances. A complete summary of the IUE and optical data is provided in a series of graphs and tables.

Dobias, J. J.↗
DOE OSTI2011

Surface Geophysical Exploration – Compendium Document

This report documents the evolution of the surface geophysical exploration (SGE) program and highlights some of the most recent successes in imaging conductive targets related to past leaks within and around Hanford's tank farms. While it is noted that the SGE program consists of multiple geophysical techniques designed to (1) locate near surface infrastructure that may interfere with (2) subsurface plume mapping, the report will focus primarily on electrical resistivity acquisition and processing for plume mapping. Due to the interferences from the near surface piping network, tanks, fences, wells, etc., the results of the three-dimensional (3D) reconstruction of electrical resistivity was more representative of metal than the high ionic strength plumes. Since the first deployment, the focus of the SGE program has been to acquire and model the best electrical resistivity data that minimizes the influence of buried metal objects. Toward that goal, two significant advances have occurred: (1) using the infrastructure directly in the acquisition campaign and (2) placement of electrodes beneath the infrastructure. The direct use of infrastructure was successfully demonstrated at T farm by using wells as long electrodes (Rucker et al., 2010, 'Electrical-Resistivity Characterization of an Industrial Site Using Long Electrodes'). While the method was capable of finding targets related to past releases, a loss of vertical resolution was the trade-off. The burying of electrodes below the infrastructure helped to increase the vertical resolution, as long as a sufficient number of electrodes are available for the acquisition campaign.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Three-Dimensional Surface Geophysical Exploration of the 200-Series Tanks at the 241-C Tank Farm

A surface geophysical exploration (SGE) survey using direct current electrical resistivity was conducted within the C Tank Farm in the vicinity of the 200-Series tanks at the Hanford Site near Richland, Washington. This survey was the second successful SGE survey to utilize the Geotection TM -180 Resistivity Monitoring System which facilitated a much larger survey size and faster data acquisition rate. The primary objective of the C Tank Farm SGE survey was to provide geophysical data and subsurface imaging results to support the Phase 2 RCRA Facility Investigation, as outlined in the Phase 2 RCRA Facility Investigation/Corrective Measures work plan RPP-PLAN-39114.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Acoustic Impedance Inversions for Offshore CO 2 Storage: South Georgia Embayment, United States

This study builds and expands on previous CO 2 storage resource assessment studies of the southeastern offshore Atlantic margin by providing a detailed evaluation on how rock porosities and permeabilities are distributed across the Upper Cretaceous strata restricted to the South Georgia Embayment (SGE). Using legacy industry two-dimensional seismic reflection and well data, this assessment is the first application of multiple seismic inversion techniques in this area. This workflow provides a reliable and repeatable model-based inversion which gives an improved image to discriminate lithology and predict porosity. The workflow is applicable to future CO 2 storage resource assessment studies elsewhere. The inversion results indicate that distinct porosity and permeability regimes are present and distributed in the Upper Cretaceous strata within the SGE. The impedance and porosity relationships show well-founded and reliable correlation. These relationships reveal low impedance coincident to the high porosity intervals which are proposed as potential reservoir intervals for CO 2 storage. In addition, the result shows that the Upper Cretaceous strata have two main potential reservoirs in the lower part. These are overlain by a thick impermeable interval, mostly shale, which has high impedance, low porosity, and low permeability and extends within the SGE. This result is in agreement with a previous study that also proposed two significant storage reservoirs for CO 2 in the Upper Cretaceous strata. Since porosity distribution is estimated using multiple methods, it follows the trends of seismic signature and structures of the Upper Cretaceous strata. The extracted values of porosity, ranging from 15 to 36%, and permeability, ranging from 1 to 100 mD, are close to the measured values from the well core data at the Upper Cretaceous strata interval.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Anisotropy in the hole mobility measured along the [110] and [1{sup ¯}10] orientations in a strained Ge quantum well

In this paper, we report on anisotropic transport properties of strained germanium (sGe) quantum wells grown on Si (001) substrates with p-type doping beneath the sGe channel. Mobility measurements were made along orthogonal [110] directions. The level of measured resistivity anisotropy in the [110] and [1{sup ¯}10] orientations was found to vary between 2 and 9 for different samples. This corresponds to an actual mobility anisotropy ratio of between 1.3 and 2, values that are significantly higher than previously found for sGe. From modeling of the low temperature (12 K) mobility, using the relaxation time approach, the anisotropy in mobility was accounted for by a difference in interface roughness scattering between the two orientations. For the [110] orientation, a step height of Δ = 0.28 nm and interface roughness periodicity of λ = 7 nm were found while for the [1{sup ¯}10] orientation, λ reduced to 4 nm and Δ increased to 0.42 nm. High-resolution X-ray diffraction and transmission electron microscopy confirmed a 1° off-cut in the wafer towards the [1{sup ¯}10] direction.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1978

Infrared spectra of HM Sagittae and V1016 Cygni

Spectrophotometry of HM Sge from 2 to 13 microns is presented along with 2 to 4-micron spectrophotometry of V1016 Cyg. From 2.5 to 8 microns, the spectrum of HM Sge can be represented by a 950-K blackbody, and a strong silicate emission feature is seen from 8 to 13 microns. Both HM Sge and V1016 Cyg show evidence of CO absorption at 2.3 microns. It is suggested that the infrared radiation from these objects arises from a combination of emission by optically thin dust and by the reddened photosphere of a cool star.

Puetter, R. C.↗
NASA NTRS1988

Cepheid binaries with large mass ratios (M1/M2)

The IUE observations of 3 Cepheid systems (Polaris, FF Aql, and S Sge) are used to derive, or set limits on, the temperatures and masses of the companions. Light from the companions of FF Aql and S Sge from 1700 to 2000 A is consistent with an A5 to A7 main sequence companion for both Cepheids, with a mass of 1.8 solar mass. This mass for the companion of S Sge is smaller than required by the orbital mass function and an evolutionary mass of the Cepheid, suggesting that the companion may itself be a binary. For Polaris, the mass of the companion must be less than 1.8 solar mass.

Evans, Nancy Remage↗
DOE OSTI2013

NEW PRECISION ORBITS OF BRIGHT DOUBLE-LINED SPECTROSCOPIC BINARIES. VIII. HR 1528, HR 6993, 2 SAGITTAE, AND 18 VULPECULAE

Improved orbital elements for four A-star double-lined spectroscopic binaries have been determined with numerous new radial velocities. Three of the four systems, HR 1528, 2 Sge, and 18 Vul, have moderately short orbital periods of 7.05, 7.39, and 9.31 days, respectively, and also have circular or nearly circular orbits. Only HR 6993 with a period of 14.68 days has a significantly eccentric orbit. The close visual companion of 2 Sge has been detected spectroscopically, and its velocity measured. The orbital dimensions (a {sub 1} sin i and a {sub 2} sin i) and minimum masses (m {sub 1} sin{sup 3} i and m {sub 2} sin{sup 3} i) of the short-period binary components all have accuracies of 0.5% or better. We determine basic properties of the individual stars and compare them with solar-abundance evolutionary tracks to estimate their masses. Half of the eight components may be synchronously or pseudosynchronously rotating.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

INFRARED SPECTROSCOPY OF SYMBIOTIC STARS. IX. D-TYPE SYMBIOTIC NOVAE

Time-series spectra of the near-infrared 1.6 {mu}m region have been obtained for five of the six known D-type symbiotic novae. The spectra map the pulsation kinematics of the Mira component in the Mira-white dwarf binary system and provide the center-of-mass velocity for the Mira. No orbital motion is detected in agreement with previous estimates of orbital periods {approx}>100 yr and semimajor axes {approx}50 AU. The 1-5 {mu}m spectra of the Miras show line weakening during dust obscuration events. This results from scattering and continuum emission by 1000 K dust. In the heavily obscured HM Sge system the 4.6 {mu}m CO spectrum formed in 1000 K gas is seen in emission against an optically thick dust continuum. Spectral features that are typically produced in either the cool molecular region or the expanding circumstellar region of late-type stars cannot be detected in the D-symbiotic novae. This is in accord with the colliding wind model for interaction between the white dwarf and Mira. Arguments are presented that the 1000 K gas and dust are not Mira circumstellar material but are in the wind interaction region of the colliding winds. CO is the first molecule detected in this region. We suggest that dust condensing in the intershock region is the origin of the dust obscuration. This model explains variations in the obscuration. Toward the highly obscured Mira in HM Sge the dust zone is estimated to be {approx}0.1 AU thick. The intershock wind interaction zone appears thinnest in the most active systems. Drawing on multiple arguments masses are estimated for the system components. The Miras in most D-symbiotic novae have descended from intermediate mass progenitors. The large amount of mass lost from the Mira combined with the massive white dwarf companion suggests that these systems are supernova candidates. However, timescales and the number of objects make these rare events.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

A SEARCH FOR RAPIDLY ACCRETING WHITE DWARFS IN THE SMALL MAGELLANIC CLOUD

The nature of the progenitors of Type Ia supernovae (SNe Ia) is still a mystery. While plausible candidates are known for both the single-degenerate and double-degenerate models, the observed numbers fall significantly short of what is required to reproduce the SNe Ia rate. Some of the most promising single-degenerate Type Ia progenitors are recurrent novae and super-soft sources (SSS). White dwarfs (WDs) with higher mass transfer rates can also be SN Ia progenitors. For these rapidly accreting white dwarfs (RAWDs), more material than is needed for steady burning accretes on the WD, and extends the WD's photosphere. Unlike SSS, such objects will likely not be detectable at soft X-ray energies, but will be bright at longer wavelengths, such as the far-ultraviolet (UV). Possible examples include LMC N66 and the V Sagittae stars. We present a survey using multi-object spectrographs looking for RAWDs in the central core of the Small Magellanic Cloud (SMC), from objects selected to be bright in the far-UV and with blue far UV - V colors. While we find some unusual objects, and recover known planetary nebula and Wolf-Rayet (WR) stars, we detect no candidate RAWD. The upper limits from this non-detection depend on our expectations of what an RAWD should look like, as well assumptions about the internal extinction of the SMC. Assuming they resemble LMC N66 or fainter versions of WR stars we set an upper limit of 10-14 RAWDs in the SMC. However, our survey is unlikely to detect objects like V Sge, and hence we cannot set meaningful upper limits if RAWDs generally resemble V Sge.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Energy demand reduction in the built environment using shallow geothermal integrated energy systems: Part II – Hybrid ground source heat pump for building heating

The research collection aims at finding the various possible opportunities for the effective integration of shallow geothermal energy (SGE) to decrease the energy demand in the built environment and to reduce emission associated with it. The direct utilization of SGE using a ground source heat pump (GSHP) has been reviewed in comprehensive review part I and part II. From the extensive review, we have found that the hybrid GSHP is needed to avoid ground thermal imbalance and peak demand. Hybrid GSHP can adopt various supplemental heat sources and sinks according to the local climatic conditions and the balance of energy demands. The primary focus on the integration of subsystems such as biomass, solar energy (PV, PVT, and collector), phase change material, micro gas turbine, and absorption heat pump with GSHP is presented for heating application. This comprehensive review part III highlights the recent research findings and a potential gap in hybrid GSHP for further research and developments

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

DIRECT DETECTION OF THE L-DWARF DONOR IN WZ SAGITTAE

Analysis of a large set of phase-resolved K-band spectra of the cataclysmic variable WZ Sge shows that the secondary star of this system appears to be an L-dwarf. Previous K-band spectra of WZ Sge found that the CO overtone bandheads were in emission. We show that absorption from the {sup 12}CO{sub (2,0)} bandhead of the donor star creates a dip in the {sup 12}CO{sub (2,0)} emission feature. Measuring the motion of this feature over the orbital period, we construct a radial velocity curve that gives a velocity amplitude of K{sub abs} = 520 ± 35 km s{sup −1}, consistent with the previously published values for this parameter.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A Monte Carlo study of flux ratios of raman scattered o vi features at 6825 and 7082 Å in symbiotic stars

Symbiotic stars are regarded as wide binary systems consisting of a hot white dwarf and a mass losing giant. They exhibit unique spectral features at 6825 and 7082 Å, which are formed via Raman scattering of O vi λλ 1032 and 1038 with atomic hydrogen. We adopt a Monte Carlo technique to generate the same number of O vi λ1032 and λ1038 line photons and compute the flux ratio F(6825)/F(7082) of these Raman scattered O vi features formed in neutral regions with a simple geometric shape as a function of H i column density N {sub H i}. In cylindrical and spherical neutral regions with the O vi source embedded inside, the flux ratio F(6825)/F(7082) shows an overall decrease from 3 to 1 as N {sub H i} increases in the range 10{sup 22--24} cm{sup −2}. In cases of slab geometry and other geometries with the O vi source outside the H i region, Rayleigh escape operates to lower the flux ratio considerably. For moderate values of N{sub HI}∼10{sup 23} cm{sup −2} the flux ratio behaves in a complicated way to exhibit a broad bump with a peak value of 3.5 in the case of a sphere geometry. We find that the ratio of Raman conversion efficiencies of O vi λλ 1032, 1038 ranges from 0.8 to 3.5. Our high resolution spectra of “D” type HM Sge and “S” type AG Dra obtained with the Canada–France–Hawaii Telescope show that the flux ratio F(6825)/F(7082) of AG Dra is significantly smaller than that of HM Sge, implying that “S” type symbiotics are characterized by higher N {sub H i} than “D” type symbiotics.

79 ASTRONOMY AND ASTROPHYSICS↗