Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “centrality measures”

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 1,513 records · Page 84
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Erratum: Lévy-stable two-pion Bose-Einstein correlations in s N N = 200 GeV Au + Au collisions [Phys. Rev. C 97 , 064911 (2018)]

We previously published in 2018 a detailed measurement recorded in 2010 for Au+Au collisions at $\sqrt{^SNN}$ = 200 GeV of charged two-pion correlation functions in 0%-30% centrality. We found the data to be well described by Bose-Einstein correlation functions stemming from L$\acute{e}$vy-stable source distributions. Using a fine transverse momentum binning, we extracted the correlation strength parameter λ, the L$\acute{e}$vy index of stability α and the L$\acute{e}$vy length scale parameter R as a function of average transverse mass of the pair m T .

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Contribution of coherent electron production to measurements of heavy-flavor decayed electrons in heavy-ion collisions

Abstract Heavy quarks, produced at early stages of heavy-ion collisions, are an excellent probe of the Quark-Gluon Plasma (QGP) also created in these collisions. Electrons from open heavy-flavor hadron decays (HFE) are good proxies for heavy quarks, and have been measured extensively in the last two decades to study QGP properties. These measurements are traditionally carried out by subtracting all known background sources from the inclusive electron sample. More recently, a significant enhancement of $$e^+e^-$$ e + e - pair production at very low transverse momenta was observed in peripheral heavy-ion collisions. The production characteristics is consistent with coherent photon–photon interactions, which should also constitute a background source to the HFE measurements. In this article, we provide theoretical predictions for the contribution of coherent electron production to HFEs as a function of transverse momentum, centrality and collision energy in Au+Au and Pb+Pb collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Comparing Occupant Light Exposure in Factory and Office Spaces

There is an increasing desire to provide healthy workplace environments that better serve people while minimizing the impact on the planet. Building recommendations help designers to incorporate the latest research and best practices, but translating research studies conducted in different settings to broader recommendations is challenging. This is particularly true for lighting, with researchers continuing to learn more about circadian, neuroendocrine, and neurobehavioral responses to light. The recommendations are regularly adjusting to incorporate the latest research as well as feedback from practitioners implementing these recommendations. There remains a need to better document the actual light exposure that people experience over the course of a day and across seasons, so that researchers can better understand the influence of light on people and recommendations can be refined. Thankfully, advances in sensor technology are making this more possible than ever. PNNL collaborated with ETC Inc. to understand actual occupant light exposure in factory and office spaces at ETC’s Headquarters in Middleton, WI. The primary building at ETC headquarters opened in 2004 and houses approximately 800 employees that contribute to central business functions, customer support, research and development, as well as the company’s primary 60,000 ft2 manufacturing facility. Vertical light exposure measurements including electric light and daylight were recorded in factory, research and development, and office work areas at occupant eye height. This document will focus on lighting measurements collected in six factory and office locations across work location, season, and time of day. Ultimately, detailed lighting measurements can be coupled with employee surveys to support development of satisfactory work environments.

42 ENGINEERING↗
DOE OSTI2025

Tantalum Experiments in Fully-Reflected Water-Moderated Triangular-Pitched U(6.90)O 2 Fuel Rod Lattices (1.02 cm Pitch)

The United States (US) Department of Energy (DOE) Nuclear Energy Research Initiative funded the design and construction of the Seven Percent Critical Experiment (7uPCX) at Sandia National Laboratories (SNL). The start-up of the experiment facility and the execution of the experiments described here were funded by the DOE Nuclear Criticality Safety Program. The 7uPCX is designed to investigate critical systems with fuel for light water reactors in the enrichment range above 5 % 235 U. The 7uPCX assembly is a water moderated and — reflected array of aluminum-clad U(6.90 %)O 2 fuel rods. Other critical experiments performed in the 7uPCX assembly are documented in LEU-COMP-THERM-078, LEU-COMP-THERM-080, LEU-COMP-THERM 096, LEU- COMP-THERM-097, LEU-COMP-THERM-101, LEU-COMP-THERM-102, and LEU-COMP-THERM-111. Applied interests in neutron-absorbing elements at epithermal and intermediate neutron energy ranges at DOE’s Hanford Site and Savannah River Site were identified through DOE Office of Environmental Management (EM) workshops and needs surveys performed in conjunction with the National Nuclear Security Administration/Nuclear Criticality Safety Program. In response, a team lead by Oak Ridge National Laboratory (ORNL) performed a study evaluating the use of 7uPCX for testing the epithermal cross sections of materials at SNL. This marked the inception of the set of experiments described here. The purpose of these experiments was to measure the effects of tantalum in nearly-critical systems. The tantalum was introduced into the fuel arrays as experiment rods within a central test region. The central test region was designed to target the epithermal neutron energy range by providing a dry cylindrical cavity constructed of aluminum and lined with 0.04 in (0.1016 cm) thick cadmium sheet. The central test region has an outer diameter of 3.75 in (9.525 cm) length of 31 in (78.74 cm) and can hold 85 tantalum rods nominally 0.25 in (0.635 cm) outside diameter and 31.25 in (79.375 cm) long. The critical experiments were done using a set of triangular-pitched grid plates fabricated for these experiments. The grid plate set accommodated a fuel array of a total of 2016 fuel rod positions on a pitch of 0.4 in (1.016 cm) in a series of 21 hexagonal rings positioned around the central test region. The fuel used in these experiments was fabricated using unirradiated 6.90 % enriched UO 2 fuel pellets from fuel elements designed to be used in the internal nuclear superheater section of the Pathfinder boiling water reactor operated in South Dakota by the Northern States Power Company in the 1960s. The fuel elements were obtained from The Pennsylvania State University where they had been stored for many years. The fuel pellets in those fuel elements were removed from the original Incoloy cladding and reclad in 3003 aluminum tubes and end caps for use in the experiments reported here. The eight cases in this experiment series were performed in 2024 in the Sandia Critical Experiments (SCX) at the Sandia Pulsed Reactor Facility by varying the number of fuel rods in the critical assembly. The personnel involved in conducting these experiments included David Ames, Elijah Lutz, Beth Hanson, Patrick Ward, Jason Soares, and Augie Chapa from SNL, as well as Mathieu Dupont and B.J. Marshall from ORNL. Case 1 had no tantalum experiment rods. Case 2 had seven tantalum rods in the center of the central test region. Case 3 had 18 tantalum rods in the third hexagonal ring of the central test region. Case 4 had 19 tantalum rods in the center of the central test region. Case 5 had 30 tantalum rods in the outer most positions of the central test region. Case 6 had 37 tantalum rods in the center of the central test region. Case 7 had 61 tantalum rods in the center of the central test region. Case 8 had 85 tantalum rods filling all positions in the central test region. All eight critical experiments are judged to be acceptable as benchmark experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1971

Infrared observations of the core of Centaurus A, NGC 5128.

Infrared radiation from the nucleus of NGC 5128 has been measured from 1 to 10 microns. Scans and aperture-size data show that there is only one bright infrared region within the central 1 min of the galaxy and that it is coincident to within 5 sec with the ?hot spot' of Kunkel and Bradt. The 3.5- and 2.2-micron radiation is more peaked toward the center than are the shorter wavelengths. The data are interpreted to indicate a small nonstellar infrared core superposed on an extended, reddened stellar component.

Becklin, E. E.↗
NASA NTRS1974

Investigation of a glass spherule from the Luna-16 probe

A glass spherule of the form of a flattened spheroid measuring 580 microns in diameter is studied. The spherule is transparent, shiny, and of a yellowish brown tint. It contains a number of central and peripheral spherical bubble-type cavities. The surface and morphology features resemble those of Apollo spherules, but differ in chemical composition, which is close to that of the Luna-16 regolith.

Glass, B. P.↗
NASA NTRS1978

Turbojet blade vibration data acquisition design and feasibility testing

A turbojet blade vibration data acquisition system was designed to allow the measurement of blade vibration. The data acquisition system utilizing 96 microprocessors to gather data from optical probes, store, sort and transmit to the central computer is described. Areas of high technical risk were identified and a two-microprocessor system was breadboarded and tested to investigate these areas. Results show that the system was feasible and that low technical risk would be involved in proceeding with the complete system fabrication.

Frarey, J. L.↗
NASA NTRS1979

Observations of solar oscillations with periods of 160 minutes

Severny et al. (1976) have reported oscillations of the sun with a period near 160 min. A description is presented of observations made at the Stanford Solar Observatory during the time from 1975 to the present which seem to support the reports by Severny et al. At Stanford the relative velocity between a central circular area of radius 0.5 solar radius on the solar disk and most of the remaining area of the solar disk is measured. A superposed epoch analysis of the observations using a period of 160 min is discussed. An apparent agreement in phase between the obtained observational data and those reported by Severny et al. tends to support the interpretation that solar oscillations are being observed.

Scherrer, P. H.↗
NASA NTRS1981

Application of superconducting coils to the NASA prototype magnetic balance

Application of superconducting coils to a general purpose magnetic balance was studied. The most suitable currently available superconducting cable for coils appears to be a bundle of many fine wires which are transposed and are mechanically confined. Sample coils were tested at central fields up to .5 Tesla, slewing rates up to 53 Tesla/ sec and frequencies up to 30 Hz. The ac losses were measured from helium boil-off and were approximately 20% higher than those calculated. Losses were dominated by hysteresis and a model for loss calculation which appears suitable for design purposes is presented along with computer listings. Combinations of two coils were also tested and interaction losses are reported. Two feasible geometries are also presented for prototype magnetic balance using superconductors.

Haldeman, C. W.↗
NASA NTRS1981

Pathogenesis of sudden death following water immersion (immersion syndrome)

Sympathetic activity under cold stress is investigated. Predominantly vagal cardio-depressive reflexes are discussed besides currently known mechanisms of sudden death after water immersion. Pronounced circulatory centralization in diving animals as well as following exposure in cold water indicates additional sympathetic activity. In cold water baths of 15 C, measurements indicate an increase in plasma catecholamine levels by more than 300 percent. This may lead to cardiac arrhythmias by the following mechanisms: cold water essentially induces sinus bradycardia; brady-and tachycardiarrhythmias may supervene as secondary complications; sinusbradycardia may be enhanced by sympathetic hypertonus. Furthermore, ectopic dysrhythmias are liable to be induced by the strictly sympathetic innervation of the ventricle. Myocardial ischemia following a rise in peripheral blood pressure constitutes another arrhythmogenic factor. Some of these reactions are enhanced by alcohol intoxication.

Buhring, M.↗
NASA NTRS1980

Application of a snowmelt-runoff model using LANDSAT data

The snowmelt-runoff model developed for two small central European watersheds simulate daily streamflow on the 228 sq km Dinwoody Creek basin in Wyoming, using snowcover extent for LANDSAT and conventionally measured temperature and precipitation. For the six-month snowmelt seasons of 1976 and 1974, the simulated seasonal runoff volumes were within 5 and 1%, respectively, of the measured runoff. Also the daily fluctuations of discharge were simulated to a high degree by the model. Thus far the limiting basin size for applying the model has not been reached, and improvements can be expected if the hydrometeorological data can be obtained from a station inside the basin. LANDSAT provides an efficient way to obtain the critical snowcover input parameter required by the model.

Source record↗
NASA NTRS1982

Reconstruction of atmospheric pollutant concentrations from remote sensing data - An application of distributed parameter observer theory

The reconstruction of a concentration distribution from spatially averaged and noise-corrupted data is a central problem in processing atmospheric remote sensing data. Distributed parameter observer theory is used to develop reconstructibility conditions for distributed parameter systems having measurements typical of those in remote sensing. The relation of the reconstructibility condition to the stability of the distributed parameter observer is demonstrated. The theory is applied to a variety of remote sensing situations, and it is found that those in which concentrations are measured as a function of altitude satisfy the conditions of distributed state reconstructibility.

Koda, M.↗
NASA NTRS1982

Large-area silicon sheet task

A set of computer models was used to define a growth system configuration that was then built and used to grow web with lower thermally generated stress. Aspects of research in the edge-defined film-fed growth (EFG) method of making Si ribbon are reported. A technique was developed to determine base resistivity and carrier lifetime in semicrystalline wafers. Automated growth of 150 kg of 15 cm-dia ingot material per crucible is reviewed. Scanning transmisson electron microscopy (STEM) and microprobe investigations of processed EFG ribbon are reported. The chemical composition of the large precipitates was studied. The structural arrangement and the electrical activity of distentions or close to the central twin plane in processed material were studied. The electrical and structural properties of grain boundaries in silicon are discussed. Temperature-dependence measurements of zero-bias conductance, a photoconductivity technique, and deep-level transient spectroscopy (DLTS) were developed. A grooving and staining technique, secondary ion mass spectroscopy, and EBIC measurements in scanning electron microscopy were used to study enhanced diffusion of phosphorus at grain boundaries in polycrystaline silicon. The fundamental mechanisms of abrasion and wear and the deformation of Si by a diamond in various fluid environments are described. The efficiency of solar cells made from EFG ribbon and Semix Inc. material is reported.

Morrison, A. D.↗
NASA NTRS1984

Personal Experience with the PVHD and Opinion of Situations in Which a Wide Field of View (FOV) PVHD Might Be Helpful

Personal experience with the PVHD indicates that it should have great promise in easing cockpit workload, improving situational awareness, and reducing spatial disorientation. It should not be assumed that the PVHD will automatically cue the pilot to his attitude without some training or exposure. Some measure of attention needs to be devoted to attitude although this can easily be accomplished by the peripheral visual fields without tying up central vision. The PVHD would appear useful in any aircraft that flies in spatially disorienting/misorienting conditions, such as night, weather, or formation. It would appear to be particularly useful in aircraft, that by their design, are especially disorienting in such circumstances.

Mcnaughton, G. B.↗
NASA NTRS1985

Star formation in the inner galaxy: A far-infrared and radio study of two H2 regions

Far-infrared and radio continuum maps have been made of the central 6' of the inner-galaxy H II regions G30.8-0.0 (in the W43 complex) and G25.4-02., along with radio and molecular line measurements at selected positions. An effort is made to understand far infrared wavelingths allow the dust temperature structures and total far infrared fluxes to be determined. Comparison of the radio and infrared maps shows a close relationship between the ionized gas and the infrared-emitting material. There is evidence that parts of G30.8 are substantially affected by extinction, even at far-infrared wavelengths. For G25.4-0.2, the radio recombination line and CO line data permit resolution of the distance ambiguity for this source. The confusion in distance determination is found to result from an extraordinary near-superposition of two bright H II regions. Using revised distances of 4.3 kpc for G26.4SE and 12 kpc for G25.4NW, that the latter, which is apparently the fainter of the two sources, is actually the more luminous. Though it is not seen on the Palomar Sky Survey, G25.4SE is easily visible in the 9532A line of S III and is mapped in this line. The ratio of total luminosity to ionizing luminosity is very similar to that of H II regions in the solar circle. Assuming a coeval population of ionizing stars, a normal initial mass function is indicated.

Lester, D. F.↗
NASA NTRS1988

Biomass-burning emissions and associated haze layers over Amazonia

The characteristics of haze layers, which were visually observed over the central Amazon Basin during many of the Amazon Boundary Layer Experiment 2A flights in July/August 1985, were investigated by remote and in situ measurements, using the broad range of instrumentation and sampling equipment on board the Electra aircraft. It was found that these layers strongly influenced the chemical and optical characteristics of the atmosphere over the eastern Amazon Basin. Relative to the regional background, the concentrations of CO, CO2, O3, and NO were significantly elevated in the plumes and haze layers, with the NO/CO ratio in fresh plumes much higher than in the aged haze layers. The haze aerosol was composed predominantly of organic material, NH4, K(+), NO3(-), SO4(2-), and organic anions (formate, acetate, and oxalate).

Andreae, M. O.↗
NASA NTRS1989

Remote sensing of the earth's surface; Proceedings of the Symposium 2, Topical Meeting, and Workshop I of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

The present conference discusses topics in the spaceborne study of the earth's surface, crust, and lithosphere, recent results from SPOT and Landsat TM investigations, and microwave observations of snowpack and soil properties. Attention is given to airborne and satellite-borne gravimetry, stereoviewing from space, TM studies of volcanism and tectonism in central Mexico, remote sensing of volcanoes, the uses of SPOT in forest management, the tectonics of the central Andes, and the application of VLBI to crustal movement studies. Also discussed are Landsat TM band ratios for soil investigations, snow dielectric measurements, the microwave radiometry of snow, microwave signatures of bare soil, the estimation of Alpine snow properties from Landsat TM data, and an experimental study of vegetable canopy microwave emissions.

Salomonson, V. V.↗
NASA NTRS1993

Total quality management: It works for aerospace information services

Today we are in the midst of information and 'total quality' revolutions. At the NASA STI Program's Center for AeroSpace Information (CASI), we are focused on using continuous improvements techniques to enrich today's services and products and to ensure that tomorrow's technology supports the TQM-based improvement of future STI program products and services. The Continuous Improvements Program at CASI is the foundation for Total Quality Management in products and services. The focus is customer-driven; its goal, to identify processes and procedures that can be improved and new technologies that can be integrated with the processes to gain efficiencies, provide effectiveness, and promote customer satisfaction. This Program seeks to establish quality through an iterative defect prevention approach that is based on the incorporation of standards and measurements into the processing cycle. Four projects are described that utilize cross-functional, problem-solving teams for identifying requirements and defining tasks and task standards, management participation, attention to critical processes, and measurable long-term goals. The implementation of these projects provides the customer with measurably improved access to information that is provided through several channels: the NASA STI Database, document requests for microfiche and hardcopy, and the Centralized Help Desk.

Erwin, James↗