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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Understanding Adoption of a Key Soft Cost Reduction Strategy: Modeling Administrative Choices Regarding Streamlined Solar Permitting (Final Technical Report)

In the U.S., the process by which residential rooftop solar photovoltaic (PV) system installations are permitted and inspected by an “authority having jurisdiction” (AHJ) and interconnected to the grid varies across the country. As the U.S. has roughly 23,000 AHJs and 3,000 utilities with varying degrees of local autonomy, permitting, inspection, and interconnection (PI&I) heterogeneity represents a significant “soft cost” barrier to the growth of the residential solar PV market. Burkhardt et al. (2015), for example, finds that variations in local permitting procedures alone can lead to differences in average residential PV prices of approximately ${$}$0.14-${$}$0.18/W. When the authors considered jurisdictional variation in permitting plus regulatory procedures, that price differential grew to ${$}$0.64-${$}$0.93/W between the least-favorable and most-favorable jurisdictions. The objective of this project was to determine suites of PI&I reforms that fit the preferences of AHJs and utilities nationwide, as mediated through the preferences of PV installers, with the hoped-for impact of significantly improving the consistency of PI&I for solar PV across the U.S. To accomplish this objective, the project team set out to design and implement survey instruments with embedded discrete choice experiments (DCEs) that used individual PI&I reforms as attributes, with levels informed by a detailed understanding of the PI&I reforms. The analysis of the surveys was to include both defined and latent class analysis of the survey results, in order to identify different sets of AHJs and utilities that would prefer different “mass customized” SSP practice combinations. Note that this project would also have advanced the social science by applying well-established choice analysis techniques to the novel setting of public administration.

14 SOLAR ENERGY↗
NASA NTRS1982

Order reduction for models of space structures using modal cost analysis

Modal cost analysis furnishes a promising methodology for developing dynamical models of space structures for use in control systems analysis. Economy and accuracy can be attained by only retaining vibration modes that contribute significantly to an appropriately defined cost function. Expressions for modal costs (especially simple for 'lightly damped' structures) are derived for attitude control, vibration suppression, and shape control. These techniques are illustrated through application to a high-order finite element model of a large platform-type structure.

Skelton, R. E.↗
NASA NTRS2016

Wind Tunnel Test of a Risk-Reduction Wing/Fuselage Model to Examine Juncture-Flow Phenomena

A wing/fuselage wind-tunnel model was tested in the Langley 14- by 22-foot Subsonic Wind Tunnel in preparation for a highly-instrumented Juncture Flow Experiment to be conducted in the same facility. This test, which was sponsored by the NASA Transformational Tool and Technologies Project, is part of a comprehensive set of experimental and computational research activities to develop revolutionary, physics-based aeronautics analysis and design capability. The objectives of this particular test were to examine the surface and off-body flow on a generic wing/body combination to: 1) choose a final wing for a future, highly instrumented model, 2) use the results to facilitate unsteady pressure sensor placement on the model, 3) determine the area to be surveyed with an embedded laser-doppler velocimetry (LDV) system, 4) investigate the primary juncture corner- flow separation region using particle image velocimetry (PIV) to see if the particle seeding is adequately entrained and to examine the structure in the separated region, and 5) to determine the similarity of observed flow features with those predicted by computational fluid dynamics (CFD). This report documents the results of the above experiment that specifically address the first three goals. Multiple wing configurations were tested at a chord Reynolds number of 2.4 million. Flow patterns on the surface of the wings and in the region of the wing/fuselage juncture were examined using oil- flow visualization and infrared thermography. A limited number of unsteady pressure sensors on the fuselage around the wing leading and trailing edges were used to identify any dynamic effects of the horseshoe vortex on the flow field. The area of separated flow in the wing/fuselage juncture near the wing trailing edge was observed for all wing configurations at various angles of attack. All of the test objectives were met. The staff of the 14- by 22-foot Subsonic Wind Tunnel provided outstanding support and delivered exceptional value to the experiment, which exceeded expectations. The results of this test will directly inform the planning for the first of a series of instrumented-model tests at the same Reynolds number. These tests will be performed on a slightly larger-scale model with the selected wing, and will include off-body measurements with LDV and PIV, steady and unsteady pressure measurements, and the flow-visualization techniques that are discussed in this report.

Kegerise, Michael A.↗