Magnetic declination and solar control of the topside ionosphere
Effects of magnetic declination and solar control on topside ionospheric electron density distribution
SOLAR EFFECT↗
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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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Investigating Atmospheric Effects on Impact Ejecta Morphology: Possible Tool for Determining Past Climate Conditions on Mars?
The combined use of impact crater morphology and mechanics provides important information on the physical conditions of both planetary atmospheres and planetary and asteroid surfaces present during crater formation, while an understanding of the rate of crater production on the surface of asteroids provides information of their surface and spin rate evolution. The research performed with support from this project improves our understanding of (1) the mechanics of impact cratering in order to gain insights on the evolution of these physical surface conditions on planets with atmospheres and asteroids, and (2) how impact flux across an asteroid surface may vary due to anisotropic distribution of impactors in the solar system. As part of this project, we have undertaken three studies. In the first study, we investigate atmospheric effects on the morphology of ejecta excavated during a cratering event in order to determine the atmospheric and target conditions from observed crater morphologies. In the second study, we use the physical and morphological consequences of oblique impacts on an asteroid to understand how the asteroid Mathilde (recently imaged by the Near Earth Asteroid Rendezvous - NEAR- spacecraft) could have survived the formation of five giant craters. In a third study, we use a Monte Carlo method to calculate the impact flux on an asteroid given a distribution of impactors on elliptical orbits. In the following section, we present the result obtained from all three studies.
Appleby, John F.↗
The Beryllium-10 Abundance in an Unusual Hibonite-Perovskite Refractory Inclusion from Allende: Implications for the Origin of Be-10
Beryllium-10 (decays to B-10, t1/2 = t(sub 1/2) = 1.3 Myr) 1.3 Myr) is a radionuclide that exclusively requires a is a radionuclide that exclusively requires a spallation origin. Therefore, one could obtain important insights into the irradiation environment in the solar nebula by understanding the distribution and abundance of this radionuclide in meteoritic inclusions. Most previous data are derived from B isotopic analysis of coarse-grained CV3 Ca-Al-rich Inclusions (CAIs) that have AL-26.Al-27 Al close to the canonical level of 5 x 10 (exp -5) and inferred Be-10/Be-9 ratios between 4 x 10(exp -4) and 1 x 10 (exp -2=3) [1-5]. Al-26-depleted FUN (Fractionaed and Unknown Nuclear anomalies) CAIs are less studied due to their rarity. FUN CAIs are thought to have formed prior to homogenization of Al-26/Al-27 Al and stable isotope anomalies (e.g., Ti-50) in the solar nebula, and thus represent one of the oldest Solar System solids [6]. So far, only three FUN CAIs (Axtell 2771, KT-1 and HAL) from CV3 chondrites have been measured for Be-10. They are characterized by variable Be-10/Be-9 ratios between (2.7−4.4) × 10(exp -4) [4,7]. Another group of rare, Al-26-free and and isotopically more anomalous inclusions, namely platy hibonite crystals (PLACs) from CM2 chondrites, have well-defined Be-10/Be-9 = (5.3 +/- 1.0) x 10 (exp -4) [9]. Al-26-free CAIs appear to have lower Be-1-/Be-9 than Al-26-bearing CAIs, although large analytical errors associated with some data would allow for an apparent overlap. It has been argued that the observed Be-10 variation resulted from the in-situ production of this radionuclide in CAIs (or their precursors) by irradiation, and the ratio difference simply reflects the fluctuation in projectile fluences [e.g., 9]. Another observation in support of this explanation comes from these CAIs' initial B-10/B-11 ratios, most of which are higher than the chondritic value 0.2478 [10]. This has been interpreted as a result of mixing between spallogenic B (B-10/B-11 = 0.4, co-produced with Be-10 in the irradiated solids) and a chondritic component [5,8]. Alternatively, given that all the inferred ratios, most of which are higher than chondritic value 0.2478 [10]. This has been interpreted as a result of mixing between spallogenic B (B-10/B-11 = 0.4, co-produced with Be-10 in the irradiated solics) and a chondritic component [5,8], Alternatively, given that all the inferred ratios in CAIs never fall below 3x10(exp -4), it has been proposed that the Solar System formed with baseline Be-10/Be-9 at this level, which originated from cosmic ray irradiation of the parental molecular cloud, and any value higher than this is a result of additional in-situ spallation [4,11]. Although not explicitly stated in this model, one would expect that inclusions that incorporated the background Be-10 abundance should form with the chondritic B isotopic ratio. However, the three FUN CAIs all have supra-chondritic B-10/B-11 indicative of the presence of a spallogenic component. To test whether some Be-10 did come into the solar nebula by inheritance,a better understanding of Be-10/Be-9 and initial B-10/B-11 in Al-26-free isotopically anomalous samples is needed. Here we present the result of Be10−B-10 system in an unsual hibonite-perovskite inclusion SHAL (son of HAL) from Allende.
Liu, M-C.↗
AI-Driven Smart Community Control for Accelerating PV Adoption and Enhancing Grid Resilience
Rapid deployment of residential photovoltaic (PV) systems helps decarbonize our electricity supplies, but under certain circumstances, high-penetration PV may pose challenges to the electrical distribution grid. In a project funded by the U.S. Department of Energy's Solar Energy Technologies Office and Building Technologies Office, the National Renewable Energy Laboratory and its partners studied how flexible building loads and battery storage, when coordinated at home-level and community-level scales, can be used to address those challenges and enhance grid resilience. In this webinar, we will discuss the methodology, simulation and field pilot results, insights from partners, and lessons learned from the project.
artificial intelligence↗
IEA/SPS 500 kW distributed collector system
Engineering studies for an International Energy Agency project for the design and construction of a 500 kW solar thermal electric power generation system of the distributed collector system (DCS) type are reviewed. The DCS system design consists of a mixed field of parabolic trough type solar collectors which are used to heat a thermal heat transfer oil. Heated oil is delivered to a thermocline storage tank from which heat is extracted and delivered to a boiler by a second heat transfer loop using the same heat transfer oil. Steam is generated in the boiler, expanded through a steam turbine, and recirculated through a condenser system cooled by a wet cooling tower.
Neumann, T. W.↗
Cybersecurity Assessment for a Behind-the-Meter Solar PV System: A Use Case for the DER-CF
The world's energy production is shifting toward lower-cost, cleaner, more efficient, and sustainable sources. The increasing numbers of distributed energy resources (DERs) are allowing for the rapid transformation of electric grids toward achieving the goal of energy decarbonization. Along with cleaner and more efficient energy, however, we must also aim for a secure energy future. Solar photovoltaic (PV) systems are an important part of this transition. This paper discusses a cybersecurity risk assessment for behind-the-meter DERs using a solar PV system as a use case of the Distributed Energy Resource Cybersecurity Framework (DER-CF) developed by the National Renewable Energy Laboratory. This poster presents a conference paper on the risk assessment processes and summarizes the DER-CF's use case recommendations to strengthen the cybersecurity posture of the electric grid.
cybersecurity↗
Impact of molten salt inflow on the temperature distribution in thermal energy storage tanks at startup for central receiver concentrating solar power plants
Concentrating Solar Power (CSP) systems with molten salt thermal energy storage (TES) tanks are one of the most promising, renewable-based energy conversion technologies for larger-scale power generation. The TES tank is one of the most critical components in CSP plants due to its high-temperature operation (up to 565 °C), daily thermal cycling, and intermittent solar radiation conditions. The plant startup is one of the most challenging operation conditions that could lead to damaging thermal gradients due to low salt inventory levels. In this study an analytical model for the sparger ring was developed and integrated with a detailed computational fluid dynamics model of a commercial-scaled molten salt tank. The integrated model allows an accurate representation of the tank operation to evaluate the effect of molten salt inflow on the mixing process. The tank filling process during plant startup was analyzed considering sparger rings with variations in design features, including inlet orifice configurations, number of orifices, direction of the inlets, and orifice diameter. The results demonstrated that higher temperature gradients are obtained in the tank floor during the plant startup. A sparger ring configuration with a predetermined orifice inlet inclination (30°, 45° and 60°) leads to significant temperature differences in the floor, between 57 °C and 62 °C, but better homogeneity in the temperature of the salt inventory. Lower salt inflow velocities result in a more homogeneous floor temperature, with maximum temperature differences under 38 °C. The sparger ring configuration with 52 orifices of 1-in. diameter and vertical flow showed better homogeneity in the temperature differences as a function of the salt level and lower temperature gradients in the tank floor. Because large temperature gradients in the tank's floor have been identified as one of the main factors contributing to tank failures, assessing various sparger ring design features is fundamental to determining proper inflow conditions that lead to low-temperature gradients and reducing failure susceptibility.
14 SOLAR ENERGY↗
Power Hardware-in-the-Loop Testing of Distribution Solid State Transformers
Savannah River National Laboratory and Resilient Power Systems have developed a utility grade solid state transformer and are planning on deploying it for testing in January 2018. The solid state transformer is the next generation solution to implementation of distributed energy resources such as solar and batteries. They can directly connect the solar and battery systems to DC ports and rout power between these DC ports and load ports. The solid state transformer can revolutionize current grid modernization initiatives by supplying grid support and building support services at the edge of the grid. These services consist of volt-VAR optimization, power factor correction, voltage regulation, frequency regulation, fault current support, demand side management, DC bus for AC/DC capable houses, and power routing between multiple ports for transactive control. For this fiscal year a test plan for testing the SST capabilities was develop. Along with the FPGA controls for the SST output ports. These controls will allow for any waveform to be produced by each port of the SST. Finally, a hybrid distribution SST was tested at the eGRID resulting in medium voltage testing experience for SRNL engineering team. DOE is currently engaged, through the Building Technology Office and Infrastructure Security and Energy Restoration in future work building from this project.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Software Development: A Tool for Smart Integration of Solar Power (Final Report)
As part of its SunShot funded Grid Assessor work Kevala assembled a team with deep electricity market, solar, software and product expertise to address a significant problem - reducing the risk of investing in solar by determining the inherent value of solar electricity based on the location where it is produced. Kevala’s Grid Assessor product is now in the market transforming the way solar assets are proposed, assessed, and financed, resulting in lower capital costs, the opening of new markets, and the streamlining of siting in the utility scale portion of the solar industry. Grid assessor accomplishes this by using detailed electricity infrastructure data, pricing information, GIS mapping, and proprietary algorithms to lower financial risk by providing transparency into the current and future value of projects based on their location.
14 SOLAR ENERGY↗
The National Solar Radiation Database (NSRDB) Fiscal Years 2019-2021(Final Report)
The National Solar Radiation Database (NSRDB) is the leading public source of high-resolution solar resource data in the United States, with more than 166,000 users annually. This database represents the state of the art in satellite-based estimation of solar resource information and uses a unique physics-based modeling approach that enables improvements in accuracy with the deployment of the next-generation geostationary satellites. Making the highest quality, state-of-the-art, regularly updated data sets available on a timely basis for users reduces costs of solar deployment by providing accurate information for siting studies and system output prediction, and thereby reduces levelized cost of energy. Also, high-resolution information from the NSRDB enables moving beyond levelized cost of energy when valuing the impact of renewables on the grid. Additionally, the NSRDB enables the integration of large amounts of solar on the grid by providing critical information about solar availability and variability that is used to enhance grid reliability and power quality.
14 SOLAR ENERGY↗
Fast Quasi-Static Time-Series Simulation for Accurate PV Inverter Semiconductor Fatigue Analysis with a Long-Term Solar Profile
Power system simulations with long-term data typically have large time steps varying from one second to a few minutes. However, for PV inverter semiconductors, the minimum thermal stress cycle occurs over the fundamental grid frequency (50 or 60 Hz). This requires the time step of the fatigue simulation to be around 100 µs. This small time step requires long computation times to process yearly power production profiles. This paper proposes a fast fatigue simulation for inverter semiconductors using the quasi-static time series (QSTS) simulation concept. The proposed simulation calculates the steady state of the semiconductor junction temperature by using a Fast Fourier Transform (FFT). The small thermal cycling during a switching period and even over the fundamental waveform is disregarded to further accelerate the simulation speed. The resulting time step of the fatigue simulation is 15 minutes, which is consistent with the solar dataset. The error of the proposed simulation is 0.16% compared to the fatigue simulation results using the complete thermal stress profile. A PV inverter that responds to a Transactive Energy System (TES) is simulated to demonstrate the use of the proposed fatigue simulation. The proposed simulation has the potential to co-simulate with system level simulation tools that also adopt the QSTS concept.
Liu, Yunting↗
Time variations and angular distributions of alpha particles and medium nuclei for the October 27, 1972 solar particle event
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Armstrong, T. P.↗
The effect of impurity distribution on short-circuit current of N/+/-diffused region of silicon solar cells
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Wang, E. Y.↗
Vertical distribution of NO2 in the stratosphere as determined from balloon measurements of solar spectra in the 4500A region
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Goldman, A.↗
A simple method for obtaining a three-dimensional proton distribution function from Voyager plasma data
The main sensor of the Vogager plasma experiment consists of a cluster of three, modulated-grid Faraday cups whose normals are arranged symmetrically about the symmetry axis of the cluster at an angle of 20 degrees to that axis. In interplanetary space, each cup explores the positive ion distribution by accepting particles from contiguous slices in velocity space. The slices are narrow in the direction of the normal to the modulating grid but are broad in planes parallel to that grid. The resulting three sets of measurements can be combined to yield the three-dimensional distribution function in the following way: the distribution function is assumed to be gyrotropic. For each value of speed in a frame of reference moving with the bulk velocity of the solar wind, the variation of the distribution function with angle from the field direction is represented by a series of Legendre polynomials. Effects such as double-streaming and heat flow can be well represented by using only the first three terms of the series which are fully specified by the measurements. Examples of the use of this method in the analysis of Voyager data are shown.
Olbert, S.↗
Relations between the photospheric magnetic field and the emission from the outer atmospheres of cool stars. II - The C IV 1550 A doublet
Solar and stellar data are used to determine the relationship between C IV 1548 + 1551 A and magnetic flux densities. C IV SMM-UVSP spectroheliograms of solar quiet regions and plages are analyzed. Typical distribution functions of C IV flux densities over both quiet and active solar regions are presented. The C IV emission is shown to be dependent on magnetic flux density.
Schrijver, C. J.↗
Velocity-space distribution functions of protons and alpha particles in the high-speed solar wind
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protons solar wind↗
Visualizing Fault Induced Traveling Waves in Medium Voltage Systems: Preprint
Traveling waves are induced in power systems during most transient events in the grid. These waves travel close to the speed of light in overhead lines and 50% to 60% the speed of light in underground cables. Even though traveling wave-based protection schemes for transmission systems are available commercially, traveling waves in medium voltage distribution networks are still in research space. Compared to transmission system, medium voltage distribution systems contain more reflections and refractions. Thus, visualization is challenging and is critical in locating faults in distribution network. To address this visualization challenge, this paper presents an open-source tool to visualize the traveling waves using Bewley lattice approach. The developed visualization tool will be useful for the protection and safety engineers to detect and triangulate fault locations in the medium voltage systems and isolate the faults.
Bewley Lattice↗