Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “solar prediction”

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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska

Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.

Gaines, G. B.↗
NASA NTRS1987

A new computational model for the prediction of mass loading phenomena for solar wind interactions with cometary and planetary ionospheres

The modified gasdynamic convected-magnetic-field MHD model developed by Spreiter and Stahara (1980) to simulate the supersonic flow of the solar wind past planetary magnetoionospheres is extended to account for cases (such as Venus and comets) in which significant numbers of neutral atmospheric atoms become ionized in the surrounding flow and add to its momentum, energy, and mass. The mathematical model and the solution procedures for the nose and tail regions are explained; typical computational grids are shown; and numerical results for a comet and for the Venus ionosheath and bow shock are presented graphically. It is found that the bow shock weakens and moves further upstream of the obstacle as mass loading is increased and the flow upstream of the bow shock becomes more compressed.

Stahara, Stephen S.↗
NASA NTRS1994

Troilite formation kinetics and growth mechanism in the solar nebula

Troilite formation via the reaction Fe(s) + H2S(g) + H2(g) is the major mechanism for S retention in grains in the solar nebula. Thermodynamic calculations predict that troilite condenses from a solar composition gas. We present experimental results on the kinetics and growth of troilite crystals on Fe metal at temperature (450-650 C) and composition (50-1000 ppm H2S in H2) conditions similar to those in the solar nebula. The fraction of Fe reacted (based on gravimetric data) is plotted at 450, 505, 575, and 650 C. The thickness change of unreacted iron (measured by optical microscopy) is plotted at 575 and 650 C vs. time. the weight change per unit area varies as the square root of time at the lower temperatures and varies linearly with time at the highest temperature. The growth behavior along the lower isotherms is due to diffusion. This behavior suggests sulfide diffusion to the metal-sulfide interface and suggests Fe(2+) diffusion to the sulfide-gas interface. The reaction along the highest isotherm appears to be interface controlled. The formation of troilite crystals is a rapid process forming measurable layers in a few hours. The crystalgrowth is complicated. Initially there are intergrowths of troilite into the pure Fe metal. As the reaction progresses two distinct layers of troilite crystals form. One is in contact with the Fe metal and consists of small randomly oriented crystals with pore space between them. The outermost layer contains large crystals that are all oriented in the same direction. The intergrowth layer is much smaller at 650 C than at 575 C. This suggest that FeS nucleation is inhibited at the higher temperature, accounting for the initially slower reaction rate. Once nucleated, the reaction kinetics are apparently controlled by the growth of the crystals at the interface.

Lauretta, D. S.↗
NASA NTRS1985

Persistence of shocks to large distances in the solar wind

Present hydrodynamic models of solar wind streams predict that interactions will cause interplanetary shocks to decay and large-scale structures to coalesce and smooth out, with a decay length of 10-15 AU for moderate or small-amplitude shocks. The Pioneer 10 plasma data, extending 1-30 AU, are examined in the light of such predictions. It is found that coalescence of streams into a single stream per solar rotation does occur, in general, but that considerable structure remains by 30 AU. The leading edge of a stream often exhibits a velocity jump of greater than 20 km/s; many of these may be shocks. There is a characteristic velocity-density-temperature signature of these distant streams which differs from the close-in double-shock signature. A unique transient was seen in July 1982, at 28 AU, with a velocity jump of about 235 km/s.

Kayser, S. E.↗
NASA NTRS2014

Solar Ion Processing of Itokawa Grains: Reconciling Model Predictions with Sample Observations

Analytical TEM observations of Itokawa grains reported to date show complex solar wind ion processing effects in the outer 30-100 nm of pyroxene and olivine grains. The effects include loss of long-range structural order, formation of isolated interval cavities or "bubbles", and other nanoscale compositional/microstructural variations. None of the effects so far described have, however, included complete ion-induced amorphization. To link the array of observed relationships to grain surface exposure times, we have adapted our previous numerical model for progressive solar ion processing effects in lunar regolith grains to the Itokawa samples. The model uses SRIM ion collision damage and implantation calculations within a framework of a constant-deposited-energy model for amorphization. Inputs include experimentally-measured amorphization fluences, a Pi steradian variable ion incidence geometry required for a rotating asteroid, and a numerical flux-versus-velocity solar wind spectrum.

Christoffersen, Roy↗
DOE OSTI2021

Unsupervised Azimuth Estimation of Solar Arrays in Low-Resolution Satellite Imagery through Semantic Segmentation and Hough Transform

This paper explains the use of a convolutional neural network (CNN) to segment solar panels in a satellite image containing solar arrays, and extract associated metadata from the arrays. A novel unsupervised technique is introduced to estimate the azimuth of each individual solar panel from the predicted mask of the convolutional neural network. This pipeline was developed with the aim of extracting necessary metadata for a solar installation, using only a set of latitude–longitude coordinates. Azimuth prediction results for 669 individual solar installations associated with 387 sites located across the United States are provided. A mean average error and median average error of 21.65 degrees and 1.0 degrees were obtained, respectively, when predicting the azimuth of the solar fleet data set, with about 80% of the results within an error of zero degrees of the ground truth azimuth value and about 85% within an error of 25 degrees. The predicted azimuth was then used to estimate the energy conversion of the solar arrays. Results show a 90.9 and 90.6 R-squared value for estimating alternating current (AC) and direct current (DC) energy, respectively, and a mean absolute percentage error (MAPE) of 1.70% in estimating the alternating current (AC) energy using the fully automated algorithm.

14 SOLAR ENERGY↗
NASA NTRS1974

ATM solar array in-flight performance analysis

The physical and electrical characteristics of the Apollo Telescope Mount (ATM) solar array are described and in-flight performance data are analyzed and compared with predicted results. Two solar cell module configurations were used. Type I module consists of 228 2 x 6 cm solar cells with two cells in parallel and 114 cells in series. Type II modules contain 684 2 x 2 cm cells with six cells in parallel and 114 cells in series. A different interconnection scheme was used for each type. Panels using type II modules with mesh interconnect system performed marginally better than those using type I module with loop interconnect system. The average degradation rate for the ATM array was 8.2% for a 271-day mission.

Thornton, J. P.↗
NASA NTRS2012

JUNO Photovoltaic Power at Jupiter

This paper summarizes the Juno modeling team work on predicting the Juno solar array performance at critical mission points including Juno Orbit Insertion (JOI) and End of Mission (EOM). This report consists of background on Juno solar array design, a summary of power estimates, an explanation of the modeling approach used by Aerospace, a detailed discussion of loss factors and performance predictions, a thermal analysis, and a review of risks to solar array performance

solar powered mission↗
DOE OSTI2022

Implementation of a Model Predictive Control Strategy to Regulate Temperature Inside Plug-Flow Solar Reactor With Countercurrent Flow

Abstract Solar-driven thermochemical energy storage systems are proven to be promising energy carriers (solar fuels) to utilize solar energy by using reactive solid-state pellets. However, the production of solar fuel requires a quasi-steady-state process temperature, which represents the main challenge due to the transient nature of solar power. In this work, an adaptive model predictive controller (MPC) is presented to regulate the temperature inside a tubular solar reactor to produce solid-state solar fuel for long-term thermal storage systems. The solar reactor system consists of a vertical tube heated circumferentially over a segment of its length by concentrated solar power, and the reactive pellets (MgMn2O4) are fed from the top end and flow downwards through the heated tube. A countercurrent flowing gas supplied from the lower end interacts with flowing pellets to reduce it thermochemically at a temperature range of 1000—1500 °C. A low-order physical model was developed to simulate the dynamics of the solar reactor including the reaction kinetics, and the proposed model was validated numerically by using a 7-kW electric furnace. The numerical model then was utilized to design the MPC controller, where the control system consists of an MPC code linked to an adaptive system identification code that updates system parameters online to ensure system robustness against external disturbances (sudden change in the flow inside the reactor), model mismatches, and uncertainty. The MPC controller parameters are tuned to enhance the system performance with minimum steady-state error and overshoot. The controller is tested to track different temperature ranges between 500 °C and 1400 °C with different particles/gas mass flowrates and ramping temperature profiles. Results show that the MPC controller successfully regulated the reactor temperature within ± 1 °C of its setpoint and maintained robust performance with minimum input effort when subjected to sudden changes in the amount of flowing media and the presence of chemical reaction.

Engineering↗
NASA NTRS1993

The SCR Ne-21 and Ar-38 in lunar rock 68815: The solar proton energy spectrum over the past 2 MYR

We determined concentration profiles of Ne-21, Ne-22, and Ar-38 produced by solar protons as a function of depth in oriented lunar rock 68815. A comparison with model predictions indicate a solar proton flux J(4(pi)(r); E greater than 10 MeV) of 100-125 p/sq. cm/s and a rigidity, R sub 0, of 85-100 MV, assuming an erosion rate of 1-2 mm/Myr. These results for 68815 and similar results on 61016 define the integrated solar proton energy spectrum at the moon over the past approximately 2 Myr.

Garrison, D. H.↗
NASA NTRS1991

Chaos in the sunspot cycle - Analysis and prediction

The variability of solar activity over long time scales, given semiquantitatively by measurements of sunspot numbers, is examined as a nonlinear dynamical system. First, a discussion of the data set used and the techniques utilized to reduce the noise and capture the long-term dynamics inherent in the data is presented. Subsequently, an attractor is reconstructed from the data set using the method of time delays. The reconstructed attractor is then used to determine both the dimension of the underlying system and also the largest Lyapunov exponent, which together indicate that the sunspot cycle is indeed chaotic and also low dimensional. In addition, recent techniques of exploiting chaotic dynamics to provide accurate, short-term predictions are utilized in order to improve upon current forecasting methods and also to place theoretical limits on predictability extent. The results are compared to chaotic solar-dynamo models as a possible physically motivated source of this chaotic behavior.

Mundt, Michael D.↗
NASA NTRS1979

Active cavity radiometer type IV

A new cavity pyrheliometer, the active cavity radiometer type IV (ACR IV), has been developed for the measurement of total solar optical irradiance. Analysis predicts its ability to measure at the solar constant level with 0.1% uncertainty in SI units. In comparison tests ACR IVs have consistently demonstrated 0.3% higher results than the World Radiometric Reference scale. A prototype has been tested, and a flight instrument has been developed and flown in a sounding rocket experiment to determine the solar constant. ACR IV instrumentation is being developed for flight experiments on the Spacelab I and Solar Maximum missions to monitor the total solar output of optical radiation as part of a long-term program to detect variations of climatological significance.

Willson, R. C.↗
NASA NTRSDate not supplied

TPSAS-NF1676L-16422-DND

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Results from recent NAIRAS model updates and new data products are presented. In addition, current and ongoing radiation measurement campaigns and verification and validation efforts are discussed.

Christopher J Mertens↗
DOE OSTI2026

Comprehensive assessment of metrology techniques for heliostat efficiency and performance evaluation

Concentrating solar power plants, specifically central receiver type systems and their heliostat field, are struggling with negative reputation in the USA, due to perceived underperformance and reliability issues. This is in part due to a lack of standards for performance assessment as well as overly simplified techno-economical models. A better understanding of influences and losses along the solar radiation path from the sun, across the solar collector to the receiver, increases the fidelity of heliostat efficiency assessment as well as solar field performance predictions. Such data are currently scarce and require a complete set of metrology capabilities to evaluate direct solar irradiance, sun shape, atmospheric attenuation, reflectance, collector shape, slope errors and total beam dispersion. In preparation for establishing a 3rd party metrology platform in collaboration with Sandia National Labs, NLR conducted a scoping study on available metrology. We present an extensive overview of techniques and commercial systems for each category. Our work includes an analysis to increase understanding of strengths and limitations of the many techniques used for surface shape and slope measurement. This applies to a controlled, indoor or outdoor laboratory environment assessing a single heliostat.

14 SOLAR ENERGY↗
NASA NTRS1982

Large scale solar magnetic fields at the site of flares, the greatness of flares, and solar-terrestrial disturbances

Evidence is presented for an intrinsically solar effect which may dominate such solar-terrestrial correlations as that reported by Chertkov (1976), where large H-alpha flares during 1967-1972 in solar active regions with overlying fields on a 100,000 km scale and predominantly north-to-south orientation were more efficient in the production of geomagnetic disturbances than comparable flares in regions whose fields at the flare sites were directed south-to-north. In addition to being responsible for geomagnetic disturbance enhancements, this purely solar effect may cause solar wind velocity and solar flare proton flux enhancements. If the effect can be generalized to other portions of the solar cycle, it could improve present understanding of the flare mechanism and therefore prove useful in the prediction of solar-terrestrial disturbances.

Dodson, H. W.↗
NASA NTRS2010

Understanding Solar Eruptions with SDO/HMI Measuring Photospheric Flows, Testing Models, and Steps Towards Forecasting Solar Eruptions

The Solar Dynamics Observatory (SDO) is carrying the first full-disk imaging vector magnetograph, the Helioseismic and Magnetic Imager (HMI), into an inclined geosynchronous orbit. This magnetograph will provide nearly continuous measurements of photospheric vector magnetic fields at cadences of 90 seconds to 12 minutes with 1" resolution, precise pointing, and unfettered by atmospheric seeing. The enormous data stream of 1.5 Terabytes per day from SAO will provide an unprecedented opportunity to understand the mysteries of solar eruptions. These ground-breaking observations will permit the application of a new technique, the differential affine velocity estimator for vector magnetograms (DAVE4VM), to measure photospheric plasma flows in active regions. These measurements will permit, for the first time, accurate assessments of the coronal free energy available for driving CMEs and flares. The details of photospheric plasma flows, particularly along magnetic neutral-lines, are critical to testing models for initiating coronal mass ejections (CMEs) and flares. Assimilating flows and fields into state-of-the art 3D MHD simulations that model the highly stratified solar atmosphere from the convection zone to the corona represents the next step towards achieving NASA's Living with a Star forecasting goals of predicting "when a solar eruption leading to a CME will occur." Our presentation will describe these major science and predictive advances that will be delivered by SDO/HMI.

Schuck, Peter W.↗
NASA NTRS2010

Understanding Solar Eruptions with SDO/HMI Measuring Photospheric Flows, Testing Models, and Steps Towards Forecasting Solar Eruptions

The imminent launch of Solar Dynamics Observatory (SDO) will carry the first full-disk imaging vector magnetograph, the Helioseismic and Magnetic Imager (HMI), into an inclined geosynchronous orbit. This magnetograph will provide nearly continuous measurements of photospheric vector magnetic fields at cadences of 90 seconds to 12 minutes with I" resolution, precise pointing, and unfettered by atmospheric seeing. The enormous data stream of ~1.5 Terabytes per day from SDO will provide an unprecedented opportunity to understand the mysteries of solar eruptions. These ground-breaking observations will permit the application of a new technique, the differential affine velocity estimator for vector magnetograms (DAVE4VM), to measure photospheric plasma flows in active regions. These measurements will permit, for the first time, accurate assessments of the coronal free energy available for driving CMEs and flares. The details of photospheric plasma flows, particularly along magnetic neutral-lines, are critical to testing models for initiating coronal mass ejections (CMEs) and flares. Assimilating flows and fields into state-of-the art 3D MHD simulations that model the highly stratified solar atmosphere from the convection zone to the corona represents the next step towards achieving NASA's Living with a Star forecasting goals of predicting "when a solar eruption leading to a CME will occur." This talk will describe these major science and predictive advances that will be delivered by SDO /HMI.

Schuck, Peter W.↗
DOE OSTI2021

Test for the Origin of Solar Mass Black Holes

Solar-mass black holes with masses in the range of ~1–2.5 M ⊙ are not expected from conventional stellar evolution, but can be produced naturally via neutron star (NS) implosions induced by capture of small primordial black holes (PBHs) or from accumulation of some varieties of particle dark matter. We argue that a unique signature of such “transmuted” solar-mass BHs is that their mass distribution would follow that of the NSs. This would be distinct from the mass function of black holes in the solar-mass range predicted either by conventional stellar evolution or early Universe PBH production. We propose that analysis of the solar-mass BH population mass distribution in a narrow mass window of ~1–2.5 M ⊙ can provide a simple yet powerful test of the origin of these BHs. Recent LIGO/VIRGO gravitational wave (GW) observations of the binary merger events GW190425 and GW190814 are consistent with a BH mass in the range ~1.5–2.6 M ⊙ . Though these results have fueled speculation on dark matter-transmuted solar-mass BHs, we demonstrate that it is unlikely that the origin of these particular events stems from NS implosions. Data from upcoming GW observations will be able to distinguish between solar-mass BHs and NSs with high confidence. This capability will facilitate and enhance the efficacy of our proposed test.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗