Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “EAST”

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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Occurrence of Low-Level Jets over the Eastern U.S. Coastal Zone at Heights Relevant to Wind Energy

Two years of high-resolution simulations conducted with the Weather Research and Forecasting (WRF) model are used to characterize the frequency, intensity and height of low-level jets (LLJ) over the U.S. Atlantic coastal zone. Meteorological conditions and the occurrence and characteristics of LLJs are described for (i) the centroids of thirteen of the sixteen active offshore wind energy lease areas off the U.S. east coast and (ii) along two transects extending east from the U.S. coastline across the northern lease areas (LA). Flow close to the nominal hub-height of wind turbines is predominantly northwesterly and southwesterly and exhibits pronounced seasonality, with highest wind speeds in November, and lowest wind speeds in June. LLJs diagnosed using vertical profiles of modeled wind speeds from approximately 20 to 530 m above sea level exhibit highest frequency in LA south of Massachusetts, where LLJs are identified in up to 12% of hours in June. LLJs are considerably less frequent further south along the U.S. east coast and outside of the summer season. LLJs frequently occur at heights that intersect the wind turbine rotor plane, and at wind speeds within typical wind turbine operating ranges. LLJs are most frequent, intense and have lowest core heights under strong horizontal temperature gradients and lower planetary boundary layer heights.

17 WIND ENERGY↗
DOE OSTI2020

Atmospheric teleconnection processes linking winter air stagnation and haze extremes in China with regional Arctic sea ice decline

Abstract. Recent studies suggested significant impacts of boreal cryosphere changes on wintertime air stagnation and haze pollution extremes in China. However, the underlying mechanisms of such a teleconnection relationship remains unclear. Here we use the Whole Atmosphere Community Climate Model (WACCM) to investigate dynamic processes leading to atmospheric circulation and air stagnation responses to Arctic sea ice changes. We conduct four climate sensitivity experiments by perturbing sea ice concentrations (SIC) and corresponding sea surface temperature (SST) in autumn and early winter over the whole Arctic and three subregions in the climate model. The results indicate distinct responses in circulation patterns and regional ventilation to the region-specific Arctic changes, with the largest increase of both the probability (by 132 %) and the intensity (by 30 %) of monthly air stagnation extremes being found in the experiment driven by SIC and SST changes over the Pacific sector of the Arctic (the East Siberian and Chukchi seas). The increased air stagnation extremes are mainly driven by an amplified planetary-scale atmospheric teleconnection pattern that resembles the negative phase of the Eurasian (EU) pattern. Dynamical diagnostics suggest that convergence of transient eddy forcing in the vicinity of Scandinavia in winter is largely responsible for the amplification of the teleconnection pattern. Transient eddy vorticity fluxes dominate the transient eddy forcing and produce a barotropic anticyclonic anomaly near Scandinavia and wave train propagation across Eurasia to the downstream regions in East Asia. The piecewise potential vorticity inversion analysis reveals that this long-range atmospheric teleconnection of Arctic origin takes place primarily via the middle and upper troposphere. The anomalous ridge over East Asia in the middle and upper troposphere worsens regional ventilation conditions by weakening monsoon northwesterlies and enhancing temperature inversions near the surface, leading to more and stronger air stagnation and pollution extremes over eastern China in winter. Ensemble projections based on state-of-the-art climate models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) corroborate this teleconnection relationship between high-latitude environmental changes and midlatitude weather extremes, though the tendency and magnitude vary considerably among each participating model.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Source attribution of Arctic black carbon and sulfate aerosols and associated Arctic surface warming during 1980–2018

Observations show that the concentrations of Arctic sulfate and black carbon (BC) aerosols have declined since the early 1980s. Previous studies have reported that reducing sulfate aerosols potentially contributed to the recent rapid Arctic warming. In this study, a global aerosol–climate model (Community Atmosphere Model, version 5) equipped with Explicit Aerosol Source Tagging (CAM5-EAST) is applied to quantify the source apportionment of aerosols in the Arctic from 16 source regions and the role of aerosol variations in affecting changes in the Arctic surface temperature from 1980 to 2018. The CAM5-EAST simulated surface concentrations of sulfate and BC in the Arctic had a decrease of 43% and 23%, respectively, in 2014–2018 relative to 1980–1984 mainly due to the reduction of emissions from Europe, Russia and local Arctic sources. Increases in emissions from South and East Asia led to positive trends in Arctic sulfate and BC in the upper troposphere. All aerosol radiative impacts are considered including aerosol–radiation and aerosol–cloud interactions, as well as black carbon deposition on snow- and ice-covered surfaces. Within the Arctic, sulfate reductions caused a top-of-atmosphere (TOA) warming of 0.11 and 0.25 W m -2 through aerosol–radiation and aerosol–cloud interactions, respectively. While the changes in Arctic atmospheric BC has little impact on local radiative forcing, the decrease in BC in snow and ice led to a net cooling of 0.05 W m -2 . By applying climate sensitivity factors for different latitudinal bands, global changes in sulfate and BC during 2014–2018 (with respect to 1980–1984) exerted a +0.088 and 0.057 K Arctic surface warming, respectively, through aerosol–radiation interactions. Through aerosol–cloud interactions, the sulfate reduction caused an Arctic warming of +0.193 K between the two time periods. The weakened BC effect on snow–ice albedo led to an Arctic surface cooling of -0.041 K. The changes in atmospheric sulfate and BC outside the Arctic produced a total Arctic warming of +0.25 K, the majority of which is due to the midlatitude changes in radiative forcing. Our results suggest that changes in aerosols over the midlatitudes of the Northern Hemisphere have a larger impact on Arctic temperature than other regions through enhanced poleward heat transport. The combined total effects of sulfate and BC produced an Arctic surface warming of +0.297 K, explaining approximately 20% of the observed Arctic warming since the early 1980s.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Hybrid deep learning architecture for general disruption prediction across tokamaks

In this paper, we present a new deep learning disruption prediction algorithm based on important findings from explorative data analysis which effectively allows knowledge transfer from existing devices to new ones, thereby predicting disruptions using very limited disruptive data from the new devices. The explorative data analysis conducted via unsupervised clustering techniques confirms that time-sequence data are much better separators of disruptive and non-disruptive behavior than the instantaneous plasma state data with further advantageous implications for a sequence-based predictor. Based on such important findings, we have designed a new algorithm for multi-machine disruption prediction that achieves high predictive accuracy on the C-Mod (AUC=0.801), DIII-D (AUC=0.947) and EAST (AUC=0.973). tokamaks with limited hyperparameter tuning. Through numerical experiments, we show that boosted accuracy (AUC=0.959) is achieved on EAST predictions by including in the training only 20 disruptive discharges, thousands of non-disruptive discharges from EAST, and combining this with more than a thousand discharges from DIII-D and C-Mod. The improvement of predictive ability obtained by combining disruptive data from other devices is found to be true for all permutations of the three devices. Furthermore, by comparing the predictive performance of each individual numerical experiment, we find that non-disruptive data are machine-specific while disruptive data from multiple devices contain device-independent knowledge that can be used to inform predictions for disruptions occurring on a new device.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1973

Orbit analysis for coastal zone oceanography observations.

A study has been performed to define the orbital characteristics of a satellite dedicated to monitoring the coastal zones of the United States. The primary area of coverage is the east coast with secondary coverage of the west coast. Since no one orbital inclination fits both coasts, the inclination was determined by the east coast to be 63 deg. This inclination was found to give better coverage of the east coast than either its retrograde counterpart or a sun synchronous orbit. The two coasts require quite different orbits to maximize the coverage. The use of a small propulsive maneuver could be used to compromise the coverage between the two coastlines and change from one type orbit to the other.

Harrison, E. F.↗
NASA NTRS1974

Solar longitude dependence of some characteristics of type III radio bursts from metric to hectometric wavelengths

Using the observed data for metric and hectometric type III radio bursts, the dependence of burst characteristics on the solar longitude has been examined over a wide frequency range. It is found that there exists and east-west asymmetry for the extension of metric type III bursts into the hectometric wavelength range. In particular, hectometric bursts are rarely observed for solar flares associated with metric bursts east of 60 E solar longitude. Furthermore, for east longitudes, the low-frequency radio observations show a large dispersion in drift time interval.

Sakurai, K.↗
NASA NTRS1975

Measurements of cosmic ray anisotropies from Pioneers 10 and 11

A progress report is presented on cosmic ray anisotropy measurements performed in interplanetary space on the Pioneers 10 and 11. A directional Cerenkov counter, sensitive to protons and alpha particles with kinetic energies exceeding 480 MeV/nucleon, was used to determine east-west and north-south anisotropies. Large variations in anisotropies with a time scale of about 60 days were found for the period April-November 1973. The total data set shows an east-west anisotropy of 0.46 plus or minus 0.11% and a north-south anisotropy of 0.03 plus or minus 0.11%. This result for the east-west anisotropy is compatible with a large value of the ratio of the perpendicular to the parallel components of the diffusion coefficient.

Axford, W. I.↗
NASA NTRS1977

Chemical character of the partially flooded Smythii Basin based on Al/Si orbital X-ray data

Orbital X-ray fluorescence data indicate that continuous mare-basalt flooding is confined to the northeastern quadrant of the Smythii Basin. Al/Si values for soils in the unflooded northwestern section of the Smythii Basin closely approximate those for the adjacent terra to the west. Terra soils east of Mare Smythii, however, are unusually aluminous compared to terra soils west of the basin. This pronounced contrast between Al/Si values for terra soils to the east and west of Smythii as well as the minimal difference in values between the northwestern section of the basin and adjacent terra to the west are most likely due to a chemically homogeneous layer of ejecta from a large impact event west of Mare Smythii, such as that which formed the Crisium Basin. An alternate hypothesis is that the unflooded section of the basin is predominantly original basin floor material, indicating that the impact forming the 4km deep Smythii Basin did not penetrate into a horizon chemically different from the terra west of Smythii. The chemical contrast between the terra east and west of Smythii, then, would be ascribed to lateral heterogeneity within the lunar crust

Andre, C. G.↗
NASA NTRS1981

An investigation of MAGSAT and complementary data emphasizing precambrian shields and adjacent areas of West Africa and South America

Several possible causes for the east-west striping of the MAGSAT anomaly maps are listed and discussed including: (1) the inadequacy of the field model used for core-crustal separation of geomagnetic anomalies; (2) external field noise remaining in the available maps; (3) east-west trends of crustal uplift and depression; (4) east-west trends to convection patterns in the mantle; (5) bands of crustal materials of similar metamorphic grade; (6) variations in the depth of the Curie isotherm; and (7) the data processing techniques used to overcome the absence of tie lines and orbital path of MAGSAT.

Hastings, D. A.↗
NASA NTRS1983

Focal depths and fault plane solutions of earthquakes under the Tibetan plateau

Seismic data are used to place constraints on the focal depths and fault plane solutions of 16 crustal earthquakes beneath the highest parts of the Tibetan plateau. Synthetic seismograms were computed for large events from 1962 to 1976, and compared with the observed waveforms. All of the events studied are found to have occurred at depths less than 15 km and probably between 5 and 10 km, suggesting that the crust below 10-15 km is essentially aseismic, as in most of the Western United States. Fault-plane solutions show combinations of normal and strike slip faulting with T axes consistently oriented approximately east-west, supporting the inference that the upper crust of Tibet is actively extending in an east-west direction. In addition, solutions for two intermediate-depth events at depths of 90 and 85 km show primarily normal faulting with east-west T axes. Results show that brittle deformation occurs at shallow depths in the crust and in the uppermost mantle, but the lower crust seems to be aseismic.

Molnar, P.↗
NASA NTRS1983

Tectonic deformation of the Andes and the configuration of the subducted slab in central Peru: Results from a micro-seismic experiment

The vast majority of the microearthquakes recorded occurred to the east: on the Huaytapallana fault in the Eastern Cordillera or in the western margin of the sub-Andes. The sub-Andes appear to be the physiographic province subjected to the most intense seismic deformation. Focal depths for the crustal events here are as deep as 50 km, and the fault plane solutions, show thrust faulting on steep planes oriented roughly north-south. The Huaytapallana fault in the Cordillera Oriental also shows relatively high seismicity along a northeast-southwest trend that agrees with the fault scarp and the east dipping nodal plane of two large earthquakes that occurred on this fault in 1969. The recorded microearthquakes of intermediate depth show a flat seismic zone about 25 km thick at a depth of about 100 km. This agrees with the suggestion that beneath Peru the slab first dips at an angle of 30 deg to a depth of 100 km and then flattens following a quasi-horizontal trajectory. Fault plane solutions of intermediate depth microearthquakes have horizontal T axes oriented east-west.

Suarez, G.↗
NASA NTRS1984

Outer satellite atmospheres: Their extended nature and planetary interactions

Model calculations for the brightness of the sodium cloud in Region A were performed to clarify the role played by the plasma torus sink in producing the east-west intensity asymmetry observed in the sodium D-lines. It was determined that the east-west electric field, proposed by Barbosa and Kievelson (1983) and Ip and Goertz (1983) to explain the dawn-dusk asymmetry in the torus ion emissions measured by the Voyager UVS instrument, could also produce the east-west sodium intensity asymmetry discovered earlier by Bergstralh et al. (1975, 1977). Model results for the directional features of the sodium cloud are also reported. The completion of the development of the Io potassium cloud model, progress in improving the Titan hydrogen torus model, and efforts in developing our model for hydrogen cometary atmospheres are also discussed.

Smyth, W. H.↗
NASA NTRS1984

On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific

A composite map produced by combining 90 passes of SST data show good agreement with conventional GEM models. The SEASAT altimeter data were deduced and found to agree with both the SST and GEM fields. The maps are dominated (especially in the east) by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Comparison with regional bathymetric data shows a remarkedly close correlation with plate age. Most anomalies in the east half of the Pacific could be partly caused by regional differences in plate age. The amplitude of these geoid or gravity anomalies caused by age differences should decrease with absolute plate age, and large anomalies (approximately 3 m) over old, smooth sea floor may indicate a further deeper source within or perhaps below the lithosphere. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration was considered. A plume emanating from a buoyant layer 100 km thick and 10,000 times less viscous than the surrounding mantle should have a diameter of about 400 km and must ascend at about 10 cm/yr to arrive still anomalously hot in the uppermost mantle.

Marsh, B. D.↗
NASA NTRS1984

Outer satellite atmospheres: Their nature and planetary interactions

Significant insights regarding the nature and interactions of Io and the planetary magnetosphere were gained through modeling studies of the spatial morphology and brightness of the Io sodium cloud. East-west intensity asymmetries in Region A are consistent with an east-west electric field and the offset of the magnetic and planetary-spin axes. East-west orbital asymmetries and the absolute brightness of Region B suggest a low-velocity (3 km/sec) satellite source of 1 to 2 x 10(26) sodium atoms/sec. The time-varying spatial structure of the sodium directional features in near Region C provides direct evidence for a magnetospheric-wind-driven escape mechanism with a high-velocity (20 km/sec) source of 1 x 10(26) atoms/sec and a flux distribution enhanced at the equator relative to the poles. A model for the Io potassium cloud is presented and analysis of data suggests a low velocity source rate of 5 x 10(24) atoms/sec. To understand the role of Titan and non-Titan sources for H atoms in the Saturn system, the lifetime of hydrogen in the planetary magnetosphere was incorporated into the earlier Titan torus model of Smyth (1981) and its expected impact discussed. A particle trajectory model for cometary hydrogen is presented and applied to the Lyman-alpha distribution of Comet Kohoutek (1973XII).

Smyth, W. H.↗
NASA NTRS1985

Tectonic rotations within the Rio Grande rift - Evidence from paleomagnetic studies

Paleomagnetic studies on Miocene Pliocene volcanic rocks from the Espanola basin of the Rio Grande rift, New Mexico, reveal directions discordant form the expected mean direction for North America. The Paliza Canyon Formation, Tschicoma Formation, and Lobato Basalt, all sampled in the Jemez Mountains west of the Pajarito fault zone, have mean declinations east of the expected mean. The Cerros del Rio volcanics, lying east of the Pajarito fault zone, have a westerly declination. Combined with published data on the Santa Fe Group sediments east of the fault zone, and the Valles Rhyolite, west of the fault zone, distinct rotations of the two areas are evident. The western block has rotated clockwise 12 deg, while the eastern block shows 16 deg of conter-clockwise motion. Differential rotations of 25-30 deg are calculated between the two blocks; 4 deg/m.y. is the minimum differential rotation for the past 5 m.y. Geologic explanations for these rotations include the opening of the Rio Grande rift in response to clockwise rotation of the Colorado Plateau and significant left slip along the Rio Grande rift.

Brown, L. L.↗
NASA NTRS1988

Determination of convergence rates across the Ventura Basin, Southern California, using GPS and historical triangulation

Comparison of angles from historical triangulation observations dating as far back as 1932 with Global Positions System (GPS) measurements taken in 1987 indicates that rapid convergence may be taking place on decade timescales in the central and eastern part of the Ventura basin, an east-west trending trough bounded by thrust faults. Changes in angles over this time were analyzed using Prescott's modified Frank's method and in terms of a model which assumes that the regions to the north and south of the basin are rigid blocks undergoing relative motion. For the two block model, inversion of the observed angle changes over the last 28 years for the relative motion vector leads to north-south convergence across the basin of 30 + or - 5 mm/yr, with a left lateral component of 10 + or - 1 mm/yr in the Fillmore-Santa Paula area in the central part of the basin. The modified Frank's method yields strain rates of approximately 2 microrad/yr in both the east and central parts of the basin for measurements spanning the 1971 San Fernando earthquake. Assuming no east-west strain yeilds north-south compression of approximately 3.5 + or - .2 cm/yr. Comparison of triangulation data prior to the earthquake shows no strain outside the margin of error. The convergence rates determined by geodetic techniques are consistent with geologic observations in the area. Such large geodetic deformation rates, with no apparent near-surface creep on the major thrust, can be understood if these faults become subhorizontal at relatively shallow depths and if the subhorizontal portions of the faults are creeping. An alternative explanation of the large displacement rates might be that the pumping of oil in the vicinity of the benchmarks caused large horizontal motions, although it is unlikely that meter scale horizontal motions are due to oil withdrawal. These and other hypotheses are evaluated to better constrain the tectonics of this active region.

Donnellan, Andrea↗
NASA NTRS1989

Fortuna Tessera, Venus - Evidence of horizontal convergence and crustal thickening

Structural and tectonic patterns mapped in Fortuna Tessera are interpreted to reflect a change in the style and intensity of deformation from east to west, beginning with simple tessera terrain at relatively low topographic elevations in the east and progressing through increasingly complex deformation patterns and higher topography to Maxwell Montes in the West. These morphologic and topographic patterns are consistent with east-to-west convergence and compression and the increasing elevations are interpreted to be due to crustal thickening processes associated with the convergent deformational environment. Using an Airy isostatic model, crustal thicknesses of approximately 35 km for the initial tessera terrain, and crustal thicknesses of over 100 km for the Maxwell Montes region are predicted. Detailed mapping with Magellan data will permit the deconvolution of individual components and structures in this terrain.

Vorder Bruegge, R. W.↗
NASA NTRS1989

Summary of 1987 and 1988 manatee aerial surveys at Kennedy Space Center

Aerial surveys of manatees conducted since 1977 at Kennedy Space Center (KSC) have provided a very useful and cost effective monitoring tool in the assessment of abundance and distribution of manatees in the northern Banana River. Data collected in the mid 1980's as part of the KSC Environmental Monitoring Program indicated that the numbers of manatees utilizing the northern Banana River had increased dramatically from earlier years and that the animals appeared to have changed their distribution patterns within the area as well (Provancha and Provancha 1988). United States Fish and Wildlife Service (USFWS) and Florida Department of Natural Resources (FLDNR) conducted bimonthly aerial surveys in 1986 for the entire Florida east coast. Their data clearly show that the Banana River has the highest concentration of manatees during the non-winter months when compared to all other segments of the east coast surveys (B. Wiegle/FLDNR, unpublished data). They further show that, in spring, an average of 71 percent of the manatees in Brevard county were located in the Banana River. During that period 85 percent of the animals were north of the NASA Causeway (State Road (SR) 402) in the KSC security zone. These data indicate the importance of the KSC waters to the Florida east coast manatee population. We reinitiated KSC surveys in 1987 to document distributions and numbers of manatees during the spring influx. Aerial censuses were continued throughout the year in 1988 and this report provides a summary of our findings for the two years.

Provancha, Jane A.↗