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NASA NTRS1979

The effects of regional insolation differences upon advanced solar thermal electric power plant performance and energy costs

This paper presents the performance and cost of four 10-MWe advanced solar thermal electric power plants sited in various regions of the continental United States. Each region has different insolation characteristics which result in varying collector field areas, plant performance, capital costs, and energy costs. The paraboloidal dish, central receiver, cylindrical parabolic trough, and compound parabolic concentrator (CPC) comprise the advanced concepts studied. This paper contains a discussion of the regional insolation data base, a description of the solar systems' performances and costs, and a presentation of a range for the forecast cost of conventional electricity by region and nationally over the next several decades.

Latta, A. F.↗

NASA NTRS1993

Secular Slip, Regional, Coseismic Effects and Post-Seismic Deformation From the June 28, 1992 Landers Earthquake: Mojave Desert GPS Results

This paper describes the constraints on long-term, post-seismic deformation within the Mojave Desert and on cumulative slip across the northern part of the Eastern California shear zone from May 1991 to August 1993.

GPS earthquake coseismic↗

DOE OSTI2025

Self-Assembled Oligomers Facilitate Amino Acid-Driven CO 2 Capture at the Air–Aqueous Interface

Direct air capture of CO 2 using amino acid absorbents, such as glycine or sarcosine, is constrained by the relatively slow mass transfer of CO 2 through the air–aqueous interface. Our recent study showed a marked improvement in CO 2 capture by introducing CO 2 -permeable oligo-dimethylsiloxane (ODMS-MIM + ) oligomers with cationic (imidazolium, MIM + ) headgroups. Here, in this work, we have employed all-atom molecular dynamics simulations in combination with subensemble analysis using network theory to provide a detailed molecular picture of the behavior of CO 2 and the glycinate anions (Gly – ) at the ODMS-MIM + decorated air–aqueous interfaces. We show that the cationic head groups of the surfactants enhance the concentration and lifetime of Gly – in the interfacial region, while ODMS tails promote the physisorption of CO 2 in the interfacial region. Together, these two factors increase the effective region of contact and the probability of interactions between CO 2 and Gly – compared to that of the pure air–aqueous interface. The fundamental insights gained in this work establish essential foundations for developing hybrid systems with oligomer-decorated interfaces to maximize the overall CO 2 capture rates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1979

Effects of D region ionization on radio wave propagation

The effects of anomalous D region ionization upon radio wave propagation are described for the main types of disturbances: sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, polar cap events, and stratospheric warmings. Examples of radio wave characteristics for such conditions are given for the frequencies between the extremely low (3-3000 Hz) and high (3-30 MHz) frequency domains. Statistics on the disturbance effects and radio wave data are given in order to contribute towards the evaluation of possibilities for predicting the radio effects.

Larsen, T. R.↗

NASA NTRS1992

ARCLITE: the Arctic Lidar Technology Facility at Sondre Stromfjord, Greenland

SRI International is presently developing an Arctic lidar (ARCLITE) facility at the incoherent-scatter radar site in Sondre Stromfjord, Greenland (67.0 degrees N, 209.2 degrees W). The project, funded by NSF through the CEDAR (Coupling Energetics and Dynamics of Atmospheric Regions) initiative, is to perform high-altitude molecular/aerosol backscatter measurements in the Arctic covering the stratosphere/mesosphere region during nighttime and daytime conditions. The lidar system employs an injection seeded, high-energy GCR-5 Spectra Physics Nd:YAG laser for primary operation at 532 nm (550 mJ per pulse at 30 Hz). The receiver system is designed around a 36-inch Cassegrainian telescope of astronomical quality with receiver components and photon-counting electronics for day and night operations. The Rayleigh backscatter measurements will conduct investigations concerning long-term studies of the basic density and temperature structure of the Arctic stratosphere/mesosphere region; effects of stratospheric warming on the structure of the stratosphere/mesosphere region; occurrence and properties of polar stratospheric clouds; occurrence of noctilucent clouds and their properties at high latitudes; and dynamic and thermodynamic coupling between the stratosphere/mesosphere region and the lower thermosphere.

Thayer, J. P.↗

NASA NTRS1991

Volcanic effects on climate

Volcanic eruptions which inject large amounts of sulfur-rich gas into the stratosphere produce dust veils which last years and cool the earth's surface. At the same time, these dust veils absorb enough solar radiation to warm the stratosphere. Since these temperature changes at the earth's surface and in the stratosphere are both in the opposite direction of hypothesized effects from greenhouse gases, they act to delay and mask the detection of greenhouse effects on the climate system. Tantalizing recent research results have suggested regional effects of volcanic eruptions, including effects on El Nino/Southern Oscillation (ENSO). In addition, a large portion of the global climate change of the past 100 years may be due to the effects of volcanoes, but a definite answer is not yet clear. While effects of several years were demonstrated with both data studies and numerical models, long-term effects, while found in climate model calculations, await confirmation with more realistic models. Extremely large explosive prehistoric eruptions may have produced severe weather and climate effects, sometimes called a 'volcanic winter'. Complete understanding of the above effects of volcanoes is hampered by inadequacies of data sets on volcanic dust veils and on climate change. Space observations can play an increasingly important role in an observing program in the future. The effects of volcanoes are not adequately separated from ENSO events, and climate modeling of the effects of volcanoes is in its infancy. Specific suggestions are made for future work to improve the knowledge of this important component of the climate system.

Robock, Alan↗

NASA NTRS1980

Viscous characteristics analysis

Program considers combustion and diffusive effects in analysis of supersonic, combustion-flow fields with imbedded subsonic regions. Effects of finite-rate chemistry, mixing, and wave propagation are linked together. Program handles up to 20 simultaneous shock waves. Some chemistry terms are computed for seven-species, eight-mechanism, hydrogen-and-air reaction scheme. Program is aid for supersonic-combustor development studies and is written in FORTRAN IV for batch execution on CYBER 175.

Jenkins, R. V.↗

NASA NTRS1984

Seasonal Characteristics of Mesospheric Plasma and Their Transitions

The main seasonal features of the middle atmosphere are arising from the different dynamical basic states in winter and summer. The development of the two controversial circulation systems and the also different peculiarities of transition between them in spring and autumn create the completely dominant seasonal variations in strato- and mesosphere. Even in the plasma structures of the mesospheric D-region the seasonal variation is towering above the amplitudes of extraterrestrial influences. From standard ionospheric sounding, significant seasonal D- and E-region effects, adhering to equally significant structure changes in the neutral gas in the height region from 20 to 100 km were discovered. Results about such typical seasonal features are summarized.

Lauter, E. A.↗

NASA NTRS1990

Effects of nose bluntness and shock-shock interactions on blunt bodies in viscous hypersonic flows

A numerical study was conducted to investigate the effects of blunt leading edges on the viscous flow field around a hypersonic vehicle such as the proposed National Aero-Space Plane. Attention is focused on two specific regions of the flow field. In the first region, effects of nose bluntness on the forebody flow field are investigated. The second region of the flow considered is around the leading edges of the scramjet inlet. In this region, the interaction of the forebody shock with the shock produced by the blunt leading edges of the inlet compression surfaces is analyzed. Analysis of these flow regions is required to accurately predict the overall flow field as well as to get necessary information on localized zones of high pressure and intense heating. The results for the forebody flow field are discussed first, followed by the results for the shock interaction in the inlet leading edge region.

Singh, D. J.↗

DOE OSTI2025

Climate adaptation in Populus trichocarpa : key adaptive loci identified for stomata and leaf traits

We investigated adaptive genetic variation in Populus trichocarpa, a potential biofuel feedstock crop, to better understand how physiological traits may influence tolerance to water limitation. Our study focused on leaf and stomatal traits, given their roles in plant–water relations and adaptation. Using a diversity panel of over 1300 genotypes, we measured 14 leaf and stomatal traits under control (well-watered) and drought (water-limited) conditions. We conducted genome-wide association studies (GWAS), climate association analyses, and transcriptome (RNA-seq) profiling to identify genetic loci associated with phenotypic variation and adaptation. Stomatal traits, including size and density, were correlated with the climate of origin, with genotypes from more arid regions tending to have smaller but denser stomata. GWAS identified multiple loci associated with trait variation, including a major-effect region on chromosome 10 linked to stomatal size and abaxial contact angle. This locus overlapped with a tandem array of 3-ketoacyl-CoA synthase (KCS) genes and showed strong allele–climate and gene expression associations. Our findings reveal genetic and phenotypic variation consistent with local adaptation and suggest that future climates may favor alleles associated with smaller stomata, particularly under increasing aridity. This work provides insights into climate adaptation and breeding strategies for resilience in perennial crops.

Populus trichocarpa↗

NASA NTRS1992

Atmospheric nuclei in the remote free-troposphere

An extensive flight series to survey aerosol present in the upper-troposphere was undertaken aboard the NASA DC-8 as part of the Global Backscatter Experiment. Aerosol with diameters greater than 3 nm were counted and sized with a combination of condensation nuclei counters and optical particle counters. Aerosol number and mass concentrations were separately identified with regard to both refractory and volatile components. Regions of the free-troposphere with the lowest mass concentrations were generally found to have the highest number concentrations and appeared to be effective regions for new particle production. These new particle concentrations appear inversely related to available aerosol surface area, and their volatility suggests a sulfuric acid composition. The long lifetime of these new particles aloft can result in their growth to sizes effective as CN and CCN that can be mixed throughout the troposphere.

Clarke, Antony D.↗

NASA NTRS1998

Impact of the 1997-1998 El-Nino of Regional Hydrology

The 1997-1998 El-Nino brought with it a range of severe local-regional hydrological phenomena. Record high temperatures and extremely dry soil conditions in Texas is an example of this regional effect. The El-Nino and La-Nina change the continental weather patterns considerably. However, connections between continental weather anomalies and regional or local anomalies have not been established to a high degree of confidence. There are several unique features of the recent El-Nino and La-Nina. Due to the recognition of the present El-Nino well in advance, there have been several coupled model studies on global and regional scales. Secondly, there is a near real-time monitoring of the situation using data from satellite sensors, namely, SeaWIFS, TOVS, AVHRR and GOES. Both observations and modeling characterize the large scale features of this El-Nino fairly well. However the connection to the local and regional hydrological phenomenon still needs to be made. This paper will use satellite observations and analysis data to establish a relation between local hydrology and large scale weather patterns. This will be the first step in using satellite data to perform regional hydrological simulations of surface temperature and soil moisture.

Lakshmi, Venkataraman↗

NASA NTRS1967

Presunrise effects due to conjugate region photoelectrons

Presunrise heating effects due to conjugate region photoelectrons

SUNRISE↗

NASA NTRS1984

Buckling of a sublaminate in a quasi-isotropic composite laminate

The buckling of an elliptic delamination embedded near the surface of a thick quasi-isotropic laminate was predicted. The thickness of the delaminated ply group (the sublaminate) was assumed to be small compared to the total laminate thickness. Finite-element and Rayleigh-Ritz methods were used for the analyses. The Rayleigh-Ritz method was found to be simple, inexpensive, and accurate, except for highly anisotropic delaminated regions. Effects of delamination shape and orientation, material anisotropy, and layup on buckling strains were examined. Results show that: (1) the stress state around the delaminated region is biaxial, which may lead to buckling when the laminate is loaded in tension; (2) buckling strains for multi-directional fiber sublaminates generally are bounded by those for the 0 deg and 90 deg unidirectional sublaminates; and (3) the direction of elongation of the sublaminate that has the lowest buckling strain correlates with the delamination growth direction.

Shivakumar, K. N.↗

NASA NTRS1985

Buckling of a sublaminate in a quasi-isotropic composite laminate

Shivakumar, K. N.↗

NASA NTRS1990

Determination of depth-viewing volumes for stereo three-dimensional graphic displays

Real-world, 3-D, pictorial displays incorporating true depth cues via stereopsis techniques offer a potential means of displaying complex information in a natural way to prevent loss of situational awareness and provide increases in pilot/vehicle performance in advanced flight display concepts. Optimal use of stereopsis requires an understanding of the depth viewing volume available to the display designer. Suggested guidelines are presented for the depth viewing volume from an empirical determination of the effective region of stereopsis cueing (at several viewer-CRT screen distances) for a time multiplexed stereopsis display system. The results provide the display designer with information that will allow more effective placement of depth information to enable the full exploitation of stereopsis cueing. Increasing viewer-CRT screen distances provides increasing amounts of usable depth, but with decreasing fields-of-view. A stereopsis hardware system that permits an increased viewer-screen distance by incorporating larger screen sizes or collimation optics to maintain the field-of-view at required levels would provide a much larger stereo depth-viewing volume.

Parrish, Russell V.↗

NASA NTRS1972

Dynamical behavior of the polar topside ionosphere.

A review is given of magnetospheric interactions with the polar ionosphere using recent experimental and theoretical results. The effect of the polar wind is discussed with reference to the observational data of J. Hoffman. These and the results of other experiments support the concept of polar wind ion flows as a general feature of the topside ionosphere for all regions outside the plasmasphere. It is shown that most of the semi-permanent topside density features result from changes in plasma temperature and F2-region effects rather than being associated with changes in ion composition. Finally, the polar peak density enhancement is discussed in terms of recent observations of the polar cusp.

Banks, P. M.↗

NASA NTRS1990

Depth-viewing-volume increase by collimation of stereo 3-D displays

Typical stereo 3-D displays are produced using a single-image-source, which is time-multiplexed, to present disparate, directly-viewed views (stereo pairs) of the visual scene to each eye. However, current stereoscopic viewing techniques impose severe restrictions in the effective viewing-volume of the stereo 3-D display. Recent experiments at Langley Research Center determined that the effective region of stereopsis cuing, the depth-viewing volume, increased with increasing viewer-to-screen distances. This increase was also accompanied by a decrease in the field-of-view of the system. It was postulated that collimation of the display source would dramatically increase the depth-viewing volume, as the effective accommodation distance would be near infinity, while maintaining the field-of-view at required levels. The goal of this proof-of-concept effort was to investigate whether or not a dramatic increase in depth-viewing volume for stereo 3-D displays would be provided by the application of collimated optics to the stereo display source.

Busquets, Anthony M.↗