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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xCP NEON Central Plains Experimental Range (CPER)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER). This is the FLUXNET version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER) produced by applying the standard ONEFlux (1F) software. Site Description - Central Plains Experimental Range (CPER) site in north central Colorado. CPER served as part of the Shortgrass Steppe LTER from 1982-2014 and is now home to a fully instrumented NEON site and a wealth of relevant historical data as well as ongoing collections of complementary data(i.e. airborne remote sensing, soil temperature and moisture, phenology measurements, plant biomass and more)

Network), NEON (National Ecological Observatory↗
DOE OSTI2022

A low-cost centralized HVAC control system solution for energy savings, load shedding, and improved maintenance

University campuses rely on centralized controls for managing and optimizing complex HVAC systems in larger buildings. However, most campuses also have many smaller buildings with packaged HVAC systems controlled by a stand-alone thermostat. Even when these distributed and often overlooked systems have modern programmable thermostats, they cannot be centrally monitored or controlled, and they are typically not programmed adequately. This paper describes the implementation of a low-cost centralized control solution for these systems serving smaller campus buildings, mostly under 5,000 sf and representative of light commercial spaces. Thanks to advances in technology spurred by residential and commercial IoT developments, simple networked thermostat solutions exist that can easily replace original thermostats, and, connect these systems to a web-based portal for monitoring and control. We show that, with small customizations, these platforms can be integrated into facility management workflows. Beyond the energy savings potential from improved scheduling and closer management of these systems, there are significant advantages for maintenance crews since these systems can now be monitored on smart phones or tablets. A grid-responsive load-shedding program has also been implemented for additional cost savings. The networked thermostats can also be connected to additional systems such as economizer controls for improved ventilation management and energy savings. With data from these systems integrated centrally, it can also be used for improved analytics and fault detection. A toolkit has been developed to share the program with other campuses, whether for energy savings, improved management of ventilation, or a more proactive maintenance approach.

Fauchier-Magnan, Nicolas↗
DOE OSTI2026

A Central Plant Retrofit Assessment Guide for Owners

This document offers support to owners considering optimization upgrades, retrofits, or complete replacement of a central plant, with a particular focus on improving energy efficiency and reliability of the central plant, ultimately leading to reduced energy costs. It outlines recommended steps to prepare for and facilitate a thorough central plant assessment, empowering owners to move forward with the appropriate next steps. While the primary focus is on central plants serving commercial and institutional buildings, the principles and recommendations presented can also be adapted for use in other building types, such as industrial or manufacturing facilities.

42 ENGINEERING↗
DOE OSTI2020

Central Plateau Vadose Zone Geoframework

The objective of this environmental calculation file (ECF) is to document the revision of the three dimensional (3D) geoframework model (GFM) of the Central Plateau Vadose Zone (CPVZ) on the Hanford Site. CP-60925, Model Package Report: Central Plateau Vadose Zone Geoframework, documents the original version of the CPVZGFM (herein after called the CPVZ-Rev.0) and is the underlying basis for the CPVZ conceptual model. The CPVZ GFM provides a more detailed interpretation of the vadose zone hydrostratigraphic units (HSUs) in the Central Plateau area of the greater Hanford South geoframework model (HSGFM) (ECF-HANFORD-13-0029, Development of the Hanford South Geologic Framework Model, Hanford Site, Washington). The development of the CPVZ GFM provides a consistent vadose zone geologic framework that is needed to support the 3D, multiple-waste-site modeling approach proposed in CP-60405, Hanford Site Composite Analysis Technical Approach Description: Vadose Zone, while incorporating an appropriate level of geologic data and interpretations for the size of the model using current site-standard HSUs. Future more detailed site-specific investigations within the Central Plateau can then use the CPVZ GFM as a starting point instead of the larger scale HSGFM. This GFM was developed using the site standard and approved for use IHS Kingdom software. This ECF is a revision to the original model described in CP-60925, but the underlying assumptions and conceptual model are unchanged. Therefore, this revision is a new calculation of version 1.0 of the CPVZ GFM and not a new version of the GFM. Throughout this report, the original model documented in CP-60925 is called CPVZ-Rev.0and the calculation for this revision of the model is called CPVZ-Rev.1.

58 GEOSCIENCES↗
DOE OSTI2021

Central Asia Seismic Hazard Assessment (Casha) "Complete" Catalog of Earthquakes

Probabilistic Seismic Hazard Assessments (PSHA) greatly benefit from reliable earthquake catalogs. Central Asia, while rich in seismic monitoring history, reports a fraction of their earthquake data to international data collection centres. Furthermore, since the collapse of Soviet Union until now, monitoring and data collection efforts in Central Asia have not been centralized, making monitoring and reporting uneven and disconnected in this time period. Lawrence Livermore National Laboratory (LLNL) has undertaken a multi-year effort to systematically work with national seismic monitoring and data centres and seismic networks in Kazakhstan, Kyrgyzstan, and Tajikistan to compile a unified seismological bulletin for Central Asia. In tandem with this effort, an earthquake catalog that is processed to be PSHA ready was also generated. The processing for this effort included further duplicate identification and removal, magnitude harmonization and catalog completeness analyses. This report describes the “complete” PSHA-ready earthquake catalog, including the completeness intervals that were applied.

58 GEOSCIENCES↗
DOE OSTI2023

Assessing sensitivities of climate model weighting to multiple methods, variables, and domains in the south-central United States

Given the increasing use of climate projections and multi-model ensemble weighting for a diverse array of applications, this project assesses the sensitivities of climate model weighting strategies and their resulting ensemble means to multiple components, such as the weighting schemes, climate variables, or spatial domains of interest. The purpose of this study is to assess the sensitivities associated with multi-model weighting strategies. The analysis makes use of global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and their statistically downscaled counterparts created with the localized constructed analogs (LOCA) method. This work focuses on historical and projected future mean precipitation and daily high temperatures of the south-central United States. Results suggest that the model weights and the corresponding weighted model means can be sensitive to the weighting strategy that is applied. For instance, when estimating model weights based on Louisiana precipitation, the weighted projections show a wetter and cooler south-central domain in the future compared to other weighting strategies. Alternatively, for example, when estimating model weights based on New Mexico temperature, the weighted projections show a drier and warmer south-central domain in the future. However, when considering the entire south-central domain in estimating the model weights, the weighted future projections show a compromise in the precipitation and temperature estimates. As for uncertainty, our matrix of results provided a more certain picture of future climate compared to the spread in the original model ensemble. If future impact assessments utilize weighting strategies, then our findings suggest that how the specific weighting strategy is used with climate projections may depend on the needs of an impact assessment or adaptation plan.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1978

Influence of central venous pressure upon sinus node responses to arterial baroreflex stimulation in man

Measurements were made of sinus node responses to arterial baroreceptor stimulation with phenylephrine injection or neck suction, before and during changes of central venous pressure provoked by lower body negative pressure or leg and lower truck elevation. Variations of central venous pressure between 1.1 and 9.0 mm Hg did not influence arterial baroreflex mediated bradycardia. Baroreflex sinus node responses were augmented by intravenous propranolol, but the level of responses after propranolol was comparable during the control state, lower body negative pressure, and leg and trunk elevation. Sinus node responses to very brief baroreceptor stimuli applied during the transitions of central venous pressure also were comparable in the three states. The authors conclude that physiological variations of central venous pressure do not influence sinus node responses to arterial baroreceptor stimulation in man.

Mark, A. L.↗
NASA NTRS1979

On the continuing stellar formation in the central regions of some globular clusters and their relation to the pulsars

The discrepancy between the predicted and observed quantities of gas in the central regions of massive globular clusters is discussed. It is hypothesized that star formation continues in the central regions by means of gas released during stellar evolution or trapped by the central region when the globular clusters pass through the center of the galaxy. Nine globular clusters are indicated at distances less than 1000 ps from which radio pulsars or X-ray sources are observed. It is argued that they could have formed relatively recently in closed pairs in the central regions and then ejected at the stage of supernova bursts with velocities over 100 ks/s.

Komberg, B. V.↗
NASA NTRS1979

The central regions of active galaxies and quasars

Theories describing the central regions of nonthermal extragalactic sources (radio galaxies, Seyfert nuclei, quasars, etc.) are examined in the light of the experimental possibilities afforded by the Space Telescope. In particular, the theory which proposes the accretion of stars or gas onto a black hole as the explanation of the central engine is discussed. Planned observations directed towards the problem of the mass, size, and structure of the central engine, and the phenomenological questions regarding the general environment of the central engine are outlined.

Sargent, W. L. W.↗
NASA NTRS1980

Orientations of central peaks in lunar craters - Implications for regional structural trends

Impact craters are dominant features on the lunar surface and all fresh craters with diameters greater than 35 km possess central peaks. Approximately half of these central peaks (54%) have either linear or arcuate geometry and display some preferential orientation. These orientations were measured for 200 lunar craters of Pre-Nectarian to Copernican age. A pervasive regional north-south trend is identified for central peak orientation, with secondary trends at + or - 20-30 deg from this axis. No evidence for regional east-west trends is found. These orientations are shown to persist in craters formed through the last 4 billion years of lunar history. A lack of coincidence between impact direction, as determined from ejecta asymmetries and peak orientation, argues for structural control by the target as a source of the linear peak morphology. This is supported by the regional and temporal persistence of preferred peak orientations. It is proposed that linear central peak orientations in lunar craters reflect a pervasive regional structural system which developed early in lunar history and has persisted through geologic time.

Hale, W.↗
NASA NTRS1982

Far-infrared observations of Sagittarius A - The luminosity and dust density in the central parsec of the Galaxy

Far-infrared observations of the central 4 arcmin of the Galaxy with 30-arcsec resolution made simultaneously at 30 microns, 50 microns, and 100 microns are presented. The 30-micron radiation peaks strongly at the position of the galactic center, as determined from the 2-micron surface brightness and the density of ionized gas. The 50- and 100-micron emission is much more extended along the plane and shows two emission lobes, one on either side of the 30-micron peak. At the position of the galactic center itself there is a local minimum in the 100-micron surface brightness. It is concluded that the dust density decreases inward over the central few parsecs of the Galaxy and that the dust density in the central parsec is so low that optical and ultraviolet radiation freely traverses this region. The total luminosity of the sources heating the dust which radiates the far-infrared emission from the central few parsecs is deduced to be between 1 x 10 to the 7th and 3 x 10 to the 7th solar luminosities.

Becklin, E. E.↗
NASA NTRS1983

Photovoltaic central station step and touch potential considerations in grounding system design

The probability of hazardous step and touch potentials is an important consideration in central station grounding system design. Steam turbine generating station grounding system design is based on accepted industry practices and there is extensive in-service experience with these grounding systems. A photovoltaic (PV) central station is a relatively new concept and there is limited experience with PV station grounding systems. The operation and physical configuration of a PV central station is very different from a steam electric station. A PV station bears some similarity to a substation and the PV station step and touch potentials might be addressed as they are in substation design. However, the PV central station is a generating station and it is appropriate to examine the effect that the differences and similarities of the two types of generating stations have on step and touch potential considerations.

Engmann, G.↗
NASA NTRS1990

Subarcsecond resolution observations of the central parsec of the Galaxy at 2.2 microns

Four separate lunar occultations of the Galactic center in the infrared K-band have been observed, and the results are used to estimate the size of the sources and to derive photometry. It is found that IRS 16NE, 16NW, and IRS 29 are smaller than about 510 AU and IRS 16SW-W and C are smaller than 85 AU. All sources brighter than K = 10 mag in the central pc are smaller than 510 AU and therefore seem to be stars. IRS 7 is smaller than about 100 AU. IRS 1W and 13, resolved into pairs of stars, are probably the exciting stars for these H II regions. The shape of the differential luminosity function of the stars in the central sq pc is similar to that of stars in the central 150 sq pc. There is a steady increase in star density toward the central few arcsec of the Galaxy.

Simon, M.↗
NASA NTRS1992

Planetary camera observations of the central parsec of M32

New HST observations are reported which show that the M32 nucleus is extremely dense, with rho0 not less than 4 x 10 exp 6 solar masses/cu pc if M32 has a core with rc not greater than 0.37 pc, and rho0 greater than 3 x 10 exp 7 solar masses/cu pc if it instead has a central r exp -1/2 cusp. Limits on the M32 core radius are nearly three times smaller, and those on the central density at least four times greater, than values inferred from the best ground-based observations. A central relaxation that is almost an order of magnitude shorter than previous estimates is inferred from the new core parameters; a shorter stellar collision time is also inferred. It is argued that a starlight cusp surrounds the central black hole.

Lauer, Tod R.↗
NASA NTRS1993

Neutral gas in the central 2 parsecs of the Galaxy

New spectroscopic observations are presented that elucidate the spatial distribution, kinematics, and density structure of atomic and molecular gas within about 2 p from IRS 16/SgrA*. The measurements confirm the presence of a dense clumpy molecular gas ring surrounding a short-lived central cavity of much lower mean gas density. It appears that this ring consists of several distinct and probably short-lived gas streamers that result from accretion from the massive molecular clouds within 10-30 pc of the center toward the central gravitational potential. Within 1 pc of SgrA* a large atomic cloud is found that appears to be falling in from more than 3 pc Galactocentric distance into the central cavity. The northern and eastern 'arms' of ionized gas are very likely dense bright rims at the surface of this atomic cloud that is now exposed to the intense UV radiation from the few central arcsec surrounding IRS 16/SgrA*.

Jackson, J. M.↗
NASA NTRS1997

Effect of Artificial Gravity: Central Nervous System Neurochemical Studies

The major objective of this project was to assess chemical and morphological modifications occurring in muscle receptors and the central nervous system of animals subjected to altered gravity (2 x Earth gravity produced by centrifugation and simulated micro gravity produced by hindlimb suspension). The underlying hypothesis for the studies was that afferent (sensory) information sent to the central nervous system by muscle receptors would be changed in conditions of altered gravity and that these changes, in turn, would instigate a process of adaptation involving altered chemical activity of neurons and glial cells of the projection areas of the cerebral cortex that are related to inputs from those muscle receptors (e.g., cells in the limb projection areas). The central objective of this research was to expand understanding of how chronic exposure to altered gravity, through effects on the vestibular system, influences neuromuscular systems that control posture and gait. The project used an approach in which molecular changes in the neuromuscular system were related to the development of effective motor control by characterizing neurochemical changes in sensory and motor systems and relating those changes to motor behavior as animals adapted to altered gravity. Thus, the objective was to identify changes in central and peripheral neuromuscular mechanisms that are associated with the re-establishment of motor control which is disrupted by chronic exposure to altered gravity.

Fox, Robert A.↗
NASA NTRS1998

Central Methysergide Prevents Renal Sympathoinhibition and Bradycardia during Hypotensive Hemorrhage

Central methysergide prevents renal sympathoinhibition and bradycardia during hypotensive hemorrhage. Mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were measured in conscious rats during either hemorrhage or cardiopulmonary receptor stimulation with phenylbiguanide (PBG) after intracerebroventricular injection of the 5-HT1/5-HT2-receptor antagonist, methysergide (40 microg). Progressive hemorrhage caused an initial rise (109 +/- 33%) followed by a fall in RSNA (-60 +/- 7%) and a fall in HR (-126 +/- 7 beats/min). Methysergide delayed the hypotension and prevented both the sympathoinhibitory and bradycardic responses to hemorrhage. Systemic 5-HT3-receptor blockade did not influence responses to hemorrhage. The PBG infusion caused transient depressor(-25 +/- 6 mmHg), bradycardic (-176 +/- 40 beats/min), and renal sympathostimulatory (182 +/-47% baseline) responses that were not affected by central methysergide (-20 +/- 6 mmHg, -162 +/- 18 beats/min, 227 +/- 46% baseline). These data indicate that a central serotonergic receptor-mediated component contributes to the sympathoinhibitory and bradycardic responses to hypotensive hemorrhage in conscious rats. Furthermore, the same central 5-HT-receptor populations involved in reflex responses to hypotensive hemorrhage probably do not mediate the sympathoinhibitory response to cardiopulmonary chemosensitive 5-HT3 receptors.

Veelken, Roland↗
NASA NTRS2001

Central Elemental Abundance Ratios In the Perseus Cluster: Resonant Scattering or SN Ia Enrichment?

We have determined abundance ratios in the core of the Perseus Cluster for several elements. These ratios indicate a central dominance of Type 1a supernova (SN Ia) ejects similar to that found for A496, A2199 and A3571. Simultaneous analysis of ASCA spectra from SIS1, GIS2, and GIS3 shows that the ratio of Ni to Fe abundances is approx. 3.4 +/- 1.1 times solar within the central 4'. This ratio is consistent with (and more precise than) that observed in other clusters whose central regions are dominated by SN Ia ejecta. Such a large Ni overabundance is predicted by "convective deflagration" explosion models for SNe Ia such as W7 but is inconsistent with delayed detonation models. We note that with current instrumentation the Ni K(alpha) line is confused with Fe K(beta) and that the Ni overabundance we observe has been interpreted by others as an anomalously large ratio of Fe K(beta) to Fe K(alpha) caused by resonant scattering in the Fe K(alpha) line. We argue that a central enhancement of SN Ia ejecta and hence a high ratio of Ni to Fe abundances are naturally explained by scenarios that include the generation of chemical gradients by suppressed SN Ia winds or ram pressure stripping of cluster galaxies. It is not necessary to suppose that the intracluster gas is optically thick to resonant scattering of the Fe K(alpha) line.

Dupke, Renato A.↗