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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 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Influence of the source distribution on the age distribution of galactic cosmic rays

The age distribution of galactic cosmic rays in the diffusion approximation is calculated. The influence of the scale height of the spatial source distribution on the mean age of particles arriving at the solar system is discussed. The broader the source distribution with respect to the galactic plane, the longer the mean age. This result provides a natural explanation for the shorter mean age of secondary cosmic rays compared to primary cosmic rays necessary for the understanding of the observed secondary/primary ratio.

Lerche, I.↗
NASA NTRS1985

Solar and thermal radiation in the Venus atmosphere

Attention is given to the solar and thermal radiation fields of Venus. Direct measurements and the results of numerical models based on direct measurements are presented. Radiation outside the atmosphere is considered with emphasis placed on global energy budget parameters, spectral and angular dependences, spatial distribution, and temporal variations of solar and thermal radiation. Radiation fluxes inside the atmosphere below 90 km are also considered with attention given to the solar flux at the surface, solar and thermal radiation fluxes from 100 km to the surface, and radiative heating and cooling below 100 km.

Moroz, V. I.↗
DOE OSTI2020

Stochastic multi-period optimal dispatch of energy storage in unbalanced distribution feeders

This report presents a convex, multi-period, AC-feasible Optimal Power Flow (OPF) framework that robustly dispatches flexible demand-side resources in unbalanced distribution feeders against uncertainty in very-short timescale solar Photo-Voltaic (PV) forecasts. This is valuable for power systems with significant behind-the-meter solar PV generation as their operation is affected by uncertainty from forecasts of demand and solar PV generation. The aim of this work is then to ensure the feasibility and reliability of distribution system operation under high solar PV penetration. We develop and present a novel, robust OPF formulation that accounts for both the nonlinear power flow constraints and the uncertainty in forecasts. This is achieved by linearizing an optimal trajectory and using first-order methods to systematically tighten voltage bounds. Case studies on a realistic distribution feeder shows the effectiveness of a receding-horizon implementation.

25 ENERGY STORAGE↗
NASA NTRS1971

Average solar wind proton properties from Pioneers 6 and 7.

Distributions and average values for the proton speed, azimuthal and polar flow directions, and the proton temperature and density in the solar wind are presented. The data are obtained from the Ames plasma probes on Pioneers 6 and 7. The time periods covered include Dec. 18, 1965 to mid-February 1966, and mid-August to mid-October 1966. The distributions of the parameters, except for the polar flow direction, are skewed, partially because of stream-stream interactions in the solar wind. The average values of the basic plasma parameters from the two spacecraft are different which could be due partially to different solar activity at the two times, and partially to sector and beam structure dependence.

Mihalov, J. D.↗
NASA NTRS2014

Organics Exposure in Orbit (OREOcube): A Next-Generation Space Exposure Platform

The OREOcube (ORganics Exposure in Orbit cube) experiment on the International Space Station (ISS) will investigate the effects of solar and cosmic radiation on organic thin films supported on inorganic substrates. Probing the kinetics of structural changes and photomodulated organic− inorganic interactions with real-time in situ UV−visible spectroscopy, this experiment will investigate the role played by solid mineral surfaces in the (photo)chemical evolution, transport, and distribution of organics in our solar system and beyond. In preparation for the OREOcube ISS experiment, we report here laboratory measurements of the photostability of thin films of the 9,10-anthraquinone derivative anthrarufin (51 nm thick) layered upon ultrathin films of iron oxides magnetite and hematite (4 nm thick), as well as supported directly on fused silica. During irradiation with UV and visible light simulating the photon flux and spectral distribution on the surface of Mars, anthrarufin/iron oxide bilayer thin films were exposed to CO2 (800 Pa), the main constituent (and pressure) of the martian atmosphere. The time-dependent photodegradation of anthrarufin thin films revealed the inhibition of degradation by both types of underlying iron oxides relative to anthrarufin on bare fused silica. Interactions between the organic and inorganic thin films, apparent in spectral shifts of the anthrarufin bands, are consistent with presumed free-electron quenching of semiquinone anion radicals by the iron oxide layers, electively protecting the organic compound from photodegradation. Combining such in situ real-time kinetic measurements of thin films in future space exposure experiments on the ISS with postflight sample return and analysis will provide time-course studies complemented by in-depth chemical analysis. This will facilitate the characterization and modeling of the chemistry of organic species associated with mineral surfaces in astrobiological contexts.

Organics↗
DOE OSTI2019

Influence of Different Light Sources, Light Intensities, and Water Flow Lens (WFL) System on Dye-Sensitized Solar Cell Performances

Recently, dye-sensitized solar cells demonstrated a superior performance under ambient light conditions. In this study, the influence on dye-sensitized solar cell performances was investigated under different light sources, light intensity, spectra, and water flow lens (WFL) system. Three types of light sources (xenon, halogen, and tungsten) with various spectral distributions (spectra) were used. Dyes-sensitized solar cells with varied sensitizers and co-sensitizers were tested depending on the light sources. Higher efficiency was obtained under irradiance of tungsten and halogen lamp in comparison to the xenon lamp, specifically at lower light intensities. Additionally, a new way of spectral adjustment was demonstrated. The use of a WFL system changes the distribution of spectra and remarkably influence for better performances of solar cells and efficiency values up to 30%. The results revealed that at lower light intensity, the influence of spectra was dominant and by changing spectral distribution various values of efficiency can be obtained. Also, a great influence on solar cells characteristics had a light source used for measurements. IEEE.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1981

The distribution of free electrons in the inner galaxy from pulsar dispersion measures

The dispersion measures of a sample of 149 pulsars in the inner Galaxy (absolute value of l 50 deg) were statistically analyzed to deduce the large-scale distribution of free thermal electrons in this region. The dispersion measure distribution of these pulsars shows significant evidence for a decrease in the electron scale height from a local value greater than the pulsar scale height to a value less than the pulsar scale height at galactocentric radii inside of approximately 7 kpc. An increase in the electron density (to a value around .15/cu cm at 4 to 5 kpc) must accompany such a decrease in scale height. There is also evidence for a large-scale warp in the electron distribution below the b + 0 deg plane inside the Solar circle. A model is proposed for the electron distribution which incorporates these features and Monte Carlo generated dispersion measure distributions are presented for parameters which best reproduce the observed pulsar distributions.

Harding, D. S.↗
NASA NTRS1986

The radial distribution of galactic gamma rays. III - The distribution of cosmic rays in the Galaxy and the CO-H2 calibration

The cosmic ray (CR) distribution in the Galaxy inside the solar circle is determined by using the kinematics of both H I and CO to ascertain the spatial distribution of the interstellar gas. The conversion factor between integrated CO line intensity and the molecular hydrogen column density is found, and possible large-scale variations of this relationship throughout the Galaxy are investigated. The galactocentric CR distributions are shown to be described satisfactorily by exponential distributions for radii larger than about three, with a radial scale length of 4-11 kpc for electrons and a scale length greater than 18 kpc for nuclei.

Bloemen, J. B. G. M.↗
NASA NTRS1994

Modulating terrestrial impacts from Oort cloud comets by the adiabatically changing galactic tides

Time modulation of the flux of new Jupiter-dominated Oort cloud comets is the subject of interest here. The major perturbation of these comets during the present epoch is due to the tidal field of the relatively smooth distribution of matter in the galactic disk. A secondary source of the near-parabolic comet flux are stars penetrating the inner Oort cloud and providing impulses that create brief comet showers. Substantial stellar-induced showers occur approximately every 100 m.y. Less frequent (but stronger) impulses due to giant molecular clouds can also perturb comets from the inner cloud. These occur on timescales of approximately equal to 500 m.y. In contrast to these infrequent stochastic shower phenomena is the continuously varying tidal-induced flux due to the galaxy. As the Sun orbits the galactic center it undergoes quasiharmonic motion about the galactic midplane, which is superimposed on the small eccentricity, near-Keplerian motion in the plane having epicycle period approximately equal to 150 m.y. In the process the galactic tidal field on the Sun/cloud system will vary causing a modulation of the observable Oort cloud flux. We have created a model of the galactic matter distribution as it affects the solar motion over a time interval ranging from 300 m.y. in the past to 100 m.y. into the future. As constraints on the disk's compact dark matter component we require consistency with the following: (1) the observed galactic rotation curve, (2) today's flux distribution of new comets, (3) the studies of K-giant distributions, and (4) the periodicity found in the terrestrial cratering record. The adiabatically varying galactic tidal torque is then determined and used to predict the time dependence of the flux. We find that a model in which approximately half the disk matter is compact is consistent with these constraints. Under such circumstances the peak-to-trough flux variation will be approx. equal to 5:1 with a full width of 9 m.y. This variability will manifest in the terrestrial cratering record and is consistent with the observed cratering periodicity, if over half of the impacts on Earth are caused by comets or asteroids that originate in the outer Oort cloud.

Matese, J. J.↗
NASA NTRS2012

DSCOVR High Time Resolution Solar Wind Measurements

The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

Szabo, Adam↗
NASA NTRS1980

Retrieval of aerosol size distributions from scattering and extinction measurements in the presence of multiple scattering

A fast technique, based on approximation to atmospheric radiative transfer in the solar aureole, is presented for the retrieval of aerosol size distribution from multispectral measurements of both scattered sky radiance and extinction by aerosol media. In this approximation, it is assumed that for a relatively clear day, the sky radiance is due to single scattering by molecules and aerosols, and to multiple scattering by molecules alone. The accuracy of this approximation is discussed in connection with the inversion of scattered radiation data. Results for aerosol size distributions retrieved from multispectral solar extinction measurements by the nonlinear least squares method are discussed, and the retrievals are found to be accurate when checked against ground truth measurements.

Deepak, A.↗
DOE OSTI2020

Solar Resource and Infrastructure Assessment for the Town of Wendell

This report is a solar resource and infrastructure assessment for the town of Wendell, Massachusetts. The assessment was funded through the National Renewable Energy Laboratory, Solar Energy Innovation Network (NREL SEIN) Solar in Rural Communities Program, as part of a project to develop a Community-Informed Proactive Solar Siting and Financing Model. As a first step, the project lead organization, UMass Clean Energy Extension prepared an assessment of existing infrastructure, resources, and potential solar development opportunities in participating municipalities, including Wendell. This assessment was designed to describe relevant bylaws and infrastructure within the town, identify the types of solar facilities that could be developed, and quantify the total space available for each type of facility. In this report, we reviewed existing electricity grid infrastructure, and the potential to interconnect additional solar facilities. At the present time, both distribution lines providing electricity to Wendell are over-saturated with authorized and proposed solar projects, and cannot accommodate additional solar projects to interconnect to the grid. It appears that National Grid is planning an upgrade to the Wendell Depot substation, which might then allow in-process projects are to proceed, and potentially free up additional capacity for new, large projects. Meanwhile, most three-phase lines could likely accommodate additional small-to-medium scale projects (under 200 kW), and most single-phase lines could likely accommodate additional projects under 50 kW in size. This description represents the local grid infrastructure as it is - planning for future scenarios of development could include recommendations for areas of grid infrastructure improvement to allow siting of distributed generation in locations preferred by the community. Future scenarios may also include the addition energy storage and other "non-wires alternatives."

14 SOLAR ENERGY↗
DOE OSTI2020

Solar Resource and Infrastructure Assessment for the Town of Blandford

This report is a solar resource and infrastructure assessment for the town of Blandford, Massachusetts. The assessment was funded through the National Renewable Energy Laboratory, Solar Energy Innovation Network (NREL SEIN) Solar in Rural Communities Program, as part of a project to develop a Community-Informed Proactive Solar Siting and Financing Model. As a first step, the project lead organization, UMass Clean Energy Extension prepared an assessment of existing infrastructure, resources, and potential solar development opportunities in participating municipalities, including Blandford. This assessment was designed to describe relevant bylaws and infrastructure within the town, identify the types of solar facilities that could be developed, and quantify the total space available for each type of facility. In this report, we reviewed existing electricity grid infrastructure, and the potential to interconnect additional solar facilities. At the present time, most distribution lines providing electricity to Blandford are over-saturated with authorized and proposed solar projects, and cannot accommodate additional solar projects to interconnect to the grid. We can expect significant upgrades to these circuits, if any of the in-process projects are to proceed, which might then free up additional capacity for new projects. There is one circuit which serves a section of North Blandford Road that is not over-saturated; for the immediate future, this is the most cost-effective location for new large-scale projects to be sited. Meanwhile, most three-phase lines could likely accommodate additional small-to-medium scale projects (under 200 kW), and most single-phase lines could likely accommodate additional projects under 50 kW in size. This description represents the local grid infrastructure as it is - planning for future scenarios of development could include recommendations for areas of grid infrastructure improvement to allow siting of distributed generation in preferred locations. Future scenarios may also include the addition energy storage and other "non-wires alternatives."

14 SOLAR ENERGY↗
NASA NTRS1986

Non-Lambertian effects on remote sensing of surface reflectance and vegetation index

This paper discusses the effects of non-Lambertian reflection from a homogeneous surface on remote sensing of the surface reflectance and vegetation index from a satellite. Remote measurement of the surface characteristics is perturbed by atmospheric scattering of sun light. This scattering tends to smooth the angular dependence of non-Lambertian surface reflectances, an effect that is not present in the case of Lambertian surfaces. This effect is calculated to test the validity of a Lambertian assumption used in remote sensing. For the three types of vegetations considered in this study, the assumption of Lambertian surface can be used satisfactorily in the derivation of surface reflectance from remotely measured radiance for a view angle outside the backscattering region. Within the backscattering region, however, the use of the assumption can result in a considerable error in the derived surface reflectance. Accuracy also deteriorates with increasing solar zenith angle. The angular distribution of the surface reflectance derived from remote measurements is smoother than that at the surface. The effect of surface non-Lambertianity on remote sensing of vegetation index is very weak. Since the effect is similiar in the visible and near infrared part of the solar spectrum for the vegetations treated in this study, it is canceled in deriving the vegetation index. The effect of the diffuse skylight on surface reflectance measurements at ground level is also discussed.

Lee, T. Y.↗
DOE OSTI2019

Capturing More Value from Combinations of PV and Other Distributed Energy Resources

Much has been written about the value of solar photovoltaic generation, but less about the value of some of the other distributed energy resources - other forms of distributed generation, energy storage, electric vehicles, demand response, and energy efficiency - or how these resources can be combined. This paper considers the types of values (or "value streams") that combinations of distributed energy resources can create, examines three "use cases," and explores a path for capturing more of the full value of these combinations.

14 SOLAR ENERGY↗
NASA NTRS2016

Is There an Exoplanet in the Solar System?

We investigate the prospects for the capture of the proposed Planet 9 from other stars in the Sun’s birth cluster. Any capture scenario must satisfy three conditions: the encounter must be more distant than ∼150 au to avoid perturbing the Kuiper belt; the other star must have a wide-orbit planet (a ≳ 100 au); the planet must be captured on to an appropriate orbit to sculpt the orbital distribution of wide-orbit Solar system bodies. Here we use N-body simulations to show that these criteria may be simultaneously satisfied. In a few per cent of slow close encounters in a cluster, bodies are captured on to heliocentric, Planet 9-like orbits. During the ∼100 Myr cluster phase, many stars are likely to host planets on highly eccentric orbits with apastron distances beyond 100 au if Neptune-sized planets are common and susceptible to planet–planet scattering. While the existence of Planet 9 remains unproven, we consider capture from one of the Sun’s young brethren a plausible route to explain such an object’s orbit. Capture appears to predict a large population of trans-Neptunian objects (TNOs) whose orbits are aligned with the captured planet, and we propose that different formation mechanisms will be distinguishable based on their imprint on the distribution of TNOs.

Kuiper belt↗
NASA NTRS2001

Interactive Learning During Solar Maximum

The goal of this project is to develop and distribute e-educational material for space science during times of solar activity that emphasizes underlying basic science principles of solar disturbances and their effects on Earth. This includes materials such as simulations, animations, group projects and other on-line materials to be used by students either in high school or at the introductory college level. The on-line delivery tool originally intended to be used is known as Interactive Multimedia Education at a Distance (IMED), which is a web-based software system used at UCLA for interactive distance learning. IMED is a password controlled system that allows students to access text, images, bulletin boards, chat rooms, animation, simulations and individual student web sites to study science and to collaborate on group projects.

Ashour-Abdalla, Maha↗
NASA NTRS1990

Three-dimensional analytical model for the spatial variation of the foreshock electron distribution function - Systematics and comparisons with ISEE observations

A model which is consistent with the solar wind and shock surface boundary conditions for the foreshock electron distribution in the absence of wave-particle effects is formulated for an arbitrary location behind the magnetic tangent to the earth's bow shock. Variations of the gyrophase-averaged velocity distribution are compared and contrasted with in situ ISEE observations. It is found that magnetic mirroring of solar wind electrons is the most important process by which nonmonotonic reduced electron distributions in the foreshock are produced. Leakage of particles from the magnetosheath is shown to be relatively unimportant in determining reduced distributions that are nonmonotonic. The two-dimensional distribution function off the magnetic field direction is the crucial contribution in producing reduced distributions which have beams. The time scale for modification of the electron velocity distribution in velocity space can be significantly influenced by steady state spatial gradients in the background imposed by the curved shock geometry.

Fitzenreiter, R. J.↗