Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SHADING”

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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Size, shade, or shape? The contribution of galaxies of different types to the star formation history of the Universe from SDSS-IV MaNGA

ABSTRACT By fitting stellar populations to the fourth generation of the Sloan Digital Sky Survey (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey observations of ∼7000 suitably weighted individual galaxies, we reconstruct the star formation history of the Universe, which we find to be in reasonable agreement with previous studies. Dividing the galaxies by their present-day stellar mass, we demonstrate the downsizing phenomenon, whereby the more massive galaxies hosted the most star formation at earlier times. Further dividing the galaxy sample by colour and morphology, we find that a galaxy’s present-day colour tells us more about its historical contribution to the cosmic star formation history than its current morphology. We show that downsizing effects are greatest among galaxies currently in the blue cloud, but that the level of downsizing in galaxies of different morphologies depends quite sensitively on the morphological classification used, due largely to the difficulty in classifying the smaller low-mass galaxies from their ground-based images. Nevertheless, we find agreement that among galaxies with stellar masses $M_{\star } \gt 6\times 10^{9}\, \mathrm{ M}_{\odot }$, downsizing is most significant in spirals. However, there are complicating factors. For example, for more massive galaxies, we find that colour and morphology are predictors of the past star formation over a longer time-scale than in less massive systems. Presumably this effect is reflecting the longer period of evolution required to alter these larger galaxies’ physical properties, but shows that conclusions based on any single property do not tell the full story.

Peterken, Thomas↗
DOE OSTI2018

Partial Shade Endurance Testing for Monolithic Photovoltaic Modules

In monolithically integrated photovoltaic (PV) modules, including CdTe, CIGS, and a-Si modules, some shadows can cause permanent damage under some operating conditions. This damage reduces efficiency and causes shunts that are visible to the eye and in luminescence imaging. Although these shadows are sometimes forbidden by product documentation, we have observed this type of damage in utility-scale PV systems. Existing standards ensure that qualified modules are safe to use after they are damaged by shadows. But no standard test exists to quantify the loss of efficiency that can result from this damage. In this work we describe new, accelerated tests to quantify the power loss that occurs due to shadows from human bodies and narrow objects, such as tools, placed nearby or directly touching modules. The tests are designed to be easy to conduct uniformly across products and laboratories. The tests can be performed outdoors and last only a few minutes. In our trials on commercial products, these tests resulted in 2%-27% permanent loss in power at standard test conditions (STC). The relative loss was several times larger when measured at lower irradiance. The tests we describe can be used to differentiate products, to direct the development of technological solutions to shadow sensitivity at the cell and module levels, and to establish the need for system-level and administrative solutions to the occurrence of shadows. Similar tests will be the basis of a new International Electrotechnical Commission (IEC) technical specification (TS) 63140.

14 SOLAR ENERGY↗
DOE OSTI2024

Pinus ponderosa physiology data from the 2022 shade manipulation field experiment at Game Ridge, Missoula County, Montana, USA

This dataset contains physiology data on Pinus ponderosa saplings, including: leaf water potential (MPa, megapascals), leaf osmotic potential (MPa, megapascals), leaf pressure potential (MPa, megapascals), leaf relative water content (% saturated mass), as well as soluble sugars (% dry mass),starch (% dry mass), and total nonstructural carbohydrates (% dry mass) found in branch phloem and xylem. Data files and data dictionary(ies) are uploaded as .csv files and .xlsx files. The Users Guide is a .pdf file. Location data can be found in the Google Earth file GameRidge_SitePlotCoordinates.kmz.kml included here. These datasets were collected for Plant Carbohydrate Depletion, Mycorrhizal Networks, and Vulnerability to Drought: An Experimental Test in the Field. This experiment examined the interdependency between plant hydraulics and carbohydrate availability and sought to develop ways to incorporate interactions with below ground symbiotic organisms to better model and quantify forest response to drought.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Truth of Varying Shades: Analyzing Language in Fake News and Political Fact-Checking

We present an analytic study on the language of news media in the context of political fact-checking and fake news detection. We compare the language of real news with that of satire, hoax, and propaganda to find linguistic cues for untruthful text. To probe the feasibility of automatic political fact-checking, we present a case study based on PolitiFact.com using their factuality judgments on a 6-point scale. Experimental results show that while media fact-checking remains to be an open research question, stylistic cues can help determine the truthfulness of text.

fact-checking↗
DOE OSTI2013

A post-occupancy monitored evaluation of the dimmable lighting, automated shading, and underfloor air distribution system in The New York Times Building

With aggressive goals to reduce national energy use and carbon emissions, the US Department of Energy will be looking to exemplary buildings that have already invested in new approaches to achieving the energy performance goals now needed at a national level. The New York Times Building, in New York, New York, incorporates a number of innovative technologies, systems and processes and could become a model for widespread replication in new and existing buildings. Post-occupancy data are invaluable in establishing confidence in innovation. A year-long monitored study was conducted to verify energy performance, assess occupant comfort and satisfaction with the indoor environment, and evaluate impacts on maintenance and operations. Lessons learned were derived from the analysis; these lessons could help identify and shape policy, financial, or supporting strategies to accelerate diffusion in the commercial building market.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗