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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

The 26 December 2004 tsunami source estimated from satellite radar altimetry and seismic waves

The 26 December 2004 Indian Ocean tsunami was the first earthquake tsunami of its magnitude to occur since the advent of both digital seismometry and satellite radar altimetry. Both have independently recorded the event from different physical aspects. The seismic data has then been used to estimate the earthquake fault parameters, and a three-dimensional ocean-general-circulation-model (OGCM) coupled with the fault information has been used to simulate the satellite-observed tsunami waves. Here we show that these two datasets consistently provide the tsunami source using independent methodologies of seismic waveform inversion and ocean modeling. Cross-examining the two independent results confirms that the slip function is the most important condition controlling the tsunami strength, while the geometry and the rupture velocity of the tectonic plane determine the spatial patterns of the tsunami.

ocean general circulation model (OGCM)↗
NASA NTRS2004

Aeroacoustic Study of a 26%-Scale Semispan Model of a Boeing 777 Wing in the NASA Ames 40- by 80-Foot Wind Tunnel

An acoustic and aerodynamic study was made of a 26%-scale unpowered Boeing 777 aircraft semispan model in the NASA Ames 40- by 80-Foot Wind Tunnel for the purpose of identifying and attenuating airframe noise sources. Simulated approach and landing configurations were evaluated at Mach numbers between 0.12 and 0.24. Cruise configurations were evaluated at Mach numbers between 0.24 and 0.33. The research team used two Ames phased-microphone arrays, a large fixed array and a small traversing array, mounted under the wing to locate and compare various noise sources in the wing high-lift system and landing gear. Numerous model modifications and noise alleviation devices were evaluated. Simultaneous with acoustic measurements, aerodynamic forces were recorded to document aircraft conditions and any performance changes caused by the geometric modifications. Numerous airframe noise sources were identified that might be important factors in the approach and landing noise of the full-scale aircraft. Several noise-control devices were applied to each noise source. The devices were chosen to manipulate and control, if possible, the flow around the various tips and through the various gaps of the high-lift system so as to minimize the noise generation. Fences, fairings, tip extensions, cove fillers, vortex generators, hole coverings, and boundary-layer trips were tested. In many cases, the noise-control devices eliminated noise from some sources at specific frequencies. When scaled to full-scale third-octave bands, typical noise reductions ranged from 1 to 10 dB without significant aerodynamic performance loss.

Horne, W. Clifton↗
NASA NTRS2006

GEOSAT Follow-On (GFO) Altimeter Document Series, Volume 8: GFO Altimeter Engineering Assessment Report Update:The First 109 Cycles Since Acceptance November 29, 2000 to December 26, 2005

The purpose of this document is to present and document GFO performance analyses and results. This is the fifth Assessment Report since the initial report. This report extends the performance assessment since acceptance to 26 December 2005. The initial GFO Altimeter Engineering Assessment Report, March 2001 (NASA/TM-2001-209984/Ver.1/Vol.1) covered the GFO performance from Launch to Acceptance (10 February 1998 to 29 November 2000). The second of the series covered the performance from Acceptance to the end of Cycle 20 (29 November 2000 to 21 November 2001). The third of the series covered the performance from Acceptance to the end of Cycle 42 (29 November 2000 to 30 November 2002). The fourth of the series covered the performance from Acceptance to the end of Cycle 64 (29 November 2000 to 17 December 2003). The fifth of the series covered performance from Acceptance to the end of Cycle 86 (29 November 2000 to 17 December 2004). Since launch, we have performed a variety of GFO performance studies; an accumulative index of those studies is provided in Appendix A.

Conger, A. M.↗
NASA NTRS1967

Performance of 26 Meter Diameter Ringsail Parachute in a Simulated Martian Environment

Inflation, drag, and stability characteristics of an 85.3-foot (26-meter) nominal diameter ringsail parachute deployed at a Mach number of 1.15 and at an altitude of 132,600 feet (40.42 kilometers) were obtained from the first flight test of the Planetary Entry Parachute Program. After deployment, the parachute inflated to the reefed condition. However, the canopy was unstable and produced low drag in the reefed condition. Upon disreefing and opening to full inflation, a slight instability in the canopy mouth was observed initially. After a short time, the fluctuations diminished and a stable configuration was attained. Results indicate a loss in drag during the fluctuation period prior to stable inflation. During descent, stability characteristics of the system were such that the average pitch-yaw angle from the local vertical was less than 10 degrees. Rolling motion between the payload and parachute canopy quickly damped to small amplitude.

Whitlock, Charles H.↗
NASA NTRS2011

Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event

We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of approx 240 km/s. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of approx 750 +/- 50 km/s, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave.

CMEs↗
NASA NTRS2013

All-Particle Cosmic Ray Energy Spectrum Measured with 26 Icetop Stations

We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, thesurface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysiswere taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 square kilometers.The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenithangle ranges between 0 and 46. Because of the isotropy of cosmic rays in this energy range the spectrafrom all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under differentassumptions on the primary mass composition. Good agreement of spectra in the three zenithangle ranges was found for the assumption of pure proton and a simple two-component model. Forzenith angles theta less than 30 deg., where the mass dependence is smallest, the knee in the cosmic ray energy spectrumwas observed at about 4 PeV, with a spectral index above the knee of about -3.1. Moreover, an indicationof a flattening of the spectrum above 22 PeV was observed.

icetop↗
NASA NTRS2017

Medical Countermeasures for Radiation Induced Health Effects: Reports of an Interagency Panel Session Held at the NASA Human Research Program Investigator's Workshop, January 26, 2017

An Interagency Panel Session organized by the NASA Human Research Program Space Radiation Program Element (SRPE) was held during the NASA Human Research Program (HRP) Investigator’s Workshop (IWS) in Galveston, Texas on January 26, 2017 to identify complementary research areas that will advance the testing and development of medical countermeasures (MCM) in support of radioprotection and radiation mitigation on the ground and in space. There were several areas of common interest identified among the various participating agencies. This report provides a summary of the topics discussed by each agency along with potential areas of intersection for mutual collaboration opportunities. Common goals included repurposing of pharmaceuticals, neutraceuticals for use as radioprotectors and/or mitigators, low-dose/chronic exposure paradigms, late effects post-radiation exposure, mixed-field exposures of gamma-neutron, performance decrements, and methods to determine individual exposure levels.

Carnell, Lisa S.↗
NASA NTRS2019

Daily evaluation of 26 precipitation datasets using Stage-IV gauge-radar data for the CONUS

New precipitation (P) datasets are released regularly, following innovations in weather forecasting models, satellite retrieval methods, and multi-source merging techniques. Using the conterminous US as a case study, we evaluated the performance of 26 gridded (sub-)daily P datasets to obtain insight into the merit of these innovations. The evaluation was performed at a daily timescale for the period 2008–2017 using the Kling–Gupta efficiency (KGE), a performance metric combining correlation, bias, and variability. As a reference, we used the high-resolution (4 km) Stage-IV gauge-radar P dataset. Among the three KGE components, the P datasets performed worst overall in terms of correlation (related to event identification). In terms of improving KGE scores for these datasets, improved P totals (affecting the bias score) and improved distribution of P intensity (affecting the variability score) are of secondary importance. Among the 11 gauge-corrected P datasets, the best overall performance was obtained by MSWEP V2.2, underscoring the importance of applying daily gauge corrections and accounting for gauge reporting times. Several uncorrected P datasets outperformed gauge-corrected ones. Among the 15 uncorrected P datasets, the best performance was obtained by the ERA5-HRES fourth-generation reanalysis, reflecting the significant advances in earth system modeling during the last decade. The (re)analyses generally performed better in winter than in summer, while the opposite was the case for the satellite-based datasets. IMERGHH V05 performed substantially better than TMPA-3B42RT V7, attributable to the many improvements implemented in the IMERG satellite P retrieval algorithm. IMERGHH V05 outperformed ERA5-HRES in regions dominated by convective storms, while the opposite was observed in regions of complex terrain. The ERA5-EDA ensemble average exhibited higher correlations than the ERA5-HRES deterministic run, highlighting the value of ensemble modeling. The WRF regional convection-permitting climate model showed considerably more accurate P totals over the mountainous west and performed best among the uncorrected datasets in terms of variability, suggesting there is merit in using high-resolution models to obtain climatological P statistics. Our findings provide some guidance to choose the most suitable P dataset for a particular application.

Hylke E. Beck↗
NASA NTRS2022

TESS Eclipsing Binary Stars. I. Short-cadence Observations of 4584 Eclipsing Binaries in Sectors 1–26

In this paper we present a catalog of 4584 eclipsing binaries observed during the first two years (26 sectors) of the TESS survey. We discuss selection criteria for eclipsing binary candidates, detection of hitherto unknown eclipsing systems, determination of the ephemerides, the validation and triage process, and the derivation of heuristic estimates for the ephemerides. Instead of keeping to the widely used discrete classes, we propose a binary star morphology classification based on a dimensionality reduction algorithm. Finally, we present statistical properties of the sample, we qualitatively estimate completeness, and we discuss the results. The work presented here is organized and performed within the TESS Eclipsing Binary Working Group, an open group of professional and citizen scientists; we conclude by describing ongoing work and future goals for the group. The catalog is available from http://tessEBs.villanova.edu and from MAST.

Andrej Prša↗
DOE OSTI2022

Powder X-ray diffraction of altrenogest, C 21 H 26 O 2

The crystal structure of altrenogest has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Altrenogest crystallizes in space group P2 1 2 1 2 1 (#19) with a = 7.286 916(16), b = 10.580 333(19), c = 22.266 08(7) Å, V = 1716.671(6) Å 3 , and Z = 4 at 295 K. Thermal expansion between 113 and 295 K is anisotropic. An O–H···O hydrogen bond links the molecules into chains along the c-axis. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

36 MATERIALS SCIENCE↗
DOE OSTI2020

Second International Symposium on Biomass/Wastes Energy and Environment (BEE 2019), Tianjin, China, May 23–26, 2019

The editorial will preface a special section of Energy and Fuels that showcases some of the work presented at an international conference held in Tianjin, China in Spring 2019. This symposium was chaired by Professor Guanyi Chen and hosted by Tianjin University. More than 400 experts from 11 countries participated, and presented new analyses, new technologies, and new ideas on ways to resolve the inherent tensions between cherishing the earth’s environment and meeting the ever-expanding demands of people and society for energy and other resources. A route to that happy future was described more than 100 years ago by Mr. Arthur D. Little who founded the eponymous company and who was also instrumental in establishing the formal study of chemical engineering in the United States. In 1909, he observed that the rapid growth of technology in the US was accompanied by the wastefulness that America is still, unfortunately, practicing. To encourage improvements in the chemical and energy industries, he reminded his readers that “Every waste that is prevented or turned to profit, … and every more effective process which is developed, makes for better living in the material sense and for more wholesome living in the higher sense.”

09 BIOMASS FUELS↗