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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Light-quark and gluon jet discrimination in pp collisions at √s = 7 TeV with the ATLAS detector

A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb -1 of proton–proton collision data at √s = 7 TeV collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant. The discriminating power of the jet tagger is established in both data and Monte Carlo samples within a systematic uncertainty of ≈ 10–20 %. In data, light-quark jets can be tagged with an efficiency of ≈ 50% while achieving a gluon-jet mis-tag rate of ≈ 25% in a p T range between 40 GeV and 360 GeV for jets in the acceptance of the tracker. The rejection of gluon-jets found in the data is significantly below what is attainable using a Pythia 6 Monte Carlo simulation, where gluon-jet mis-tag rates of 10 % can be reached for a 50 % selection efficiency of light-quark jets using the same jet properties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Review of Landscaping Equipment Vibration Risk Exposure, LLNL Site 200 (Various Locations), Whole Body Vibration Seated and Standing Mowers

WBV (Whole-Body Vibration) for operators of seated and standing lawn mowers was conducted during landscape activities from April 2019 through August 2019 at various locations around LLNL Site 200. Mowing is generally performed by each landscaper for 2-3 days every other week with a maximum duration of 3-5 hours each day. On mowing days, other tasks are performed for the remainder of the day that do not expose the worker to WBV such as irrigation, blowing, or sweeping. The mowing terrain at LLNL is variable with typical reported conditions such as gopher holes, exposed tree roots, quick turns, normal and high growth, weeds, and mushy/wet ground that can result in jolts to the mower operator. The Larson Davis HVM200 seat pad with tri-axial accelerometer was used for monitoring workers. For the seated mowers, the HVM200 seat pad with tri-axial accelerometer was placed on the seat between the user and seat pan of the mower. For standing mowers, the seat pad with tri-axial accelerometer was wrapped with Dycem (for seat pad protection) and placed directly on top of the mower deck and underneath the end-user’s right foot. Monitoring for WBV was conducted while operators used different types, makes, and models of mowers. A total of sixteen samples were collected from the operators of seated mower and 6 samples were collected from operators of standing mower. This initial data sampling was part of a discovery phase to identify if WBV exposure met the 2016 ACGIH TLVs (Threshold Limit Values). This initial data identified that workers operating the mowers do not exceed either the TLV or Action Level (AL) for Weighted Acceleration Levels (A(8)) but typically exceed the Vibration Dose Value (VDV) lower boundary for the standing mowers.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Sensor-Equipped Unmanned Surface Vehicle for High-Resolution Mapping of Water Quality in Low- to Mid-Order Streams

Longitudinal profiling of water quality via the deployment of sensors from watercraft has advanced the understanding of spatial patterns in large rivers and lakes; however, a similar approach in low- to mid-order streams is lacking. To fill this gap, we developed an unmanned surface vehicle (USV)-water quality measurement platform (the “AquaBOT”). The components of the AquaBOT included a nitrate sensor, multiparameter sonde (temperature, conductivity, turbidity, dissolved oxygen, chlorophyll), quantum sensor, and global positioning system (GPS) mounted to a small pontoon-style USV. The AquaBOT was tested in four streams and rivers in Iowa and Tennessee. All measured water quality parameters varied longitudinally, and greater ranges were generally observed along the low-order, agriculturally influenced streams in Iowa. Nitrate, in particular, was spatially heterogeneous. For example, during one run in early June, concentrations ranged from 10.5 to 12.5 mg N L –1 along a 2.3 km reach and hotspots were observed directly downstream of some tile drains. The spatial resolution of AquaBOT data collected in June was 10× higher than grab sampling data, and measurements were collected in less time and at a comparable cost. Here, the AquaBOT can complement existing measurement approaches and will lead to advancements in understanding the processes driving water quality along the stream-to-river continuum.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Large-scale structure catalogues for cosmological analysis

ABSTRACT We present large-scale structure catalogues from the completed extended Baryon Oscillation Spectroscopic Survey (eBOSS). Derived from Sloan Digital Sky Survey (SDSS) IV Data Release 16 (DR16), these catalogues provide the data samples, corrected for observational systematics, and random positions sampling the survey selection function. Combined, they allow large-scale clustering measurements suitable for testing cosmological models. We describe the methods used to create these catalogues for the eBOSS DR16 Luminous Red Galaxy (LRG) and Quasar samples. The quasar catalogue contains 343 708 redshifts with 0.8 < z < 2.2 over 4808 deg2. We combine 174 816 eBOSS LRG redshifts over 4242 deg2 in the redshift interval 0.6 < z < 1.0 with SDSS-III BOSS LRGs in the same redshift range to produce a combined sample of 377 458 galaxy redshifts distributed over 9493 deg2. Improved algorithms for estimating redshifts allow that 98 per cent of LRG observations result in a successful redshift, with less than one per cent catastrophic failures (Δz > 1000 km s−1). For quasars, these rates are 95 and 2 per cent (with Δz > 3000 km s−1). We apply corrections for trends between the number densities of our samples and the properties of the imaging and spectroscopic data. For example, the quasar catalogue obtains a χ2/DoF = 776/10 for a null test against imaging depth before corrections and a χ2/DoF= 6/8 after. The catalogues, combined with careful consideration of the details of their construction found here-in, allow companion papers to present cosmological results with negligible impact from observational systematic uncertainties.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Testing hadronic-model predictions of depth of maximum of air-shower profiles and ground-particle signals using hybrid data of the Pierre Auger Observatory

We test the predictions of hadronic interaction models regarding the depth of maximum of air-shower profiles, X max , and ground-particle signals in water-Cherenkov detectors at 1000 m from the shower core, S ( 1000 ) , using the data from the fluorescence and surface detectors of the Pierre Auger Observatory. The test consists of fitting the measured two-dimensional ( S ( 1000 ) , X max ) distributions using templates for simulated air showers produced with hadronic interaction models pos-, et--04, 2.3d and leaving the scales of predicted X max and the signals from hadronic component at ground as free-fit parameters. The method relies on the assumption that the mass composition remains the same at all zenith angles, while the longitudinal shower development and attenuation of ground signal depend on the mass composition in a correlated way. The analysis was applied to 2239 events detected by both the fluorescence and surface detectors of the Pierre Auger Observatory with energies between 10 18.5 eV to 10 19.0 eV and zenith angles below 60°. We found, that within the assumptions of the method, the best description of the data is achieved if the predictions of the hadronic interaction models are shifted to deeper X max values and larger hadronic signals at all zenith angles. Given the magnitude of the shifts and the data sample size, the statistical significance of the improvement of data description using the modifications considered in the paper is larger than 5 σ even for any linear combination of experimental systematic uncertainties. Published by the American Physical Society 2024

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

First observation of the rare B + → D + K + π - decay

The B + → D + K + π - decay is observed in a data sample corresponding to 3.0 fb -1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. The signal significance is 8σ and the branching fraction is measured to be B(B + →D + K + π - )=(5.31±0.90±0.48±0.35)×10 -6 , where the uncertainties are statistical, systematic and due to the normalization mode B + → D - K + π + , respectively. The Dalitz plot appears to be dominated by broad structures. Angular distributions are exploited to search for quasi-two-body contributions from B + → D$ ^&lowast;_2 $(2460) 0 K + and B + → D + K &lowast; (892) 0 decays. No significant signals are observed and upper limits are set on their branching fractions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Study of excited Ξ c states decaying into Ξ c 0 and Ξ c + baryons

Here, with a data sample of 980 fb - 1 of e + e - annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy e + e - collider, we discuss the results of a study of excited Ξ c states that decay, via the emission of photons and/or charged pions, into Ξ c 0 or Ξ c + ground state charmed-strange baryons. We present new measurements of the masses of all members of the Ξ c ' , Ξ c ( 2645 ) , Ξ c ( 2790 ) , Ξ c ( 2815 ) , and Ξ c ( 2980 ) isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Amplitude analysis of B - → D + π - π - decays

The Dalitz plot analysis technique is used to study the resonant substructures of B - → D + π - π - decays in a data sample corresponding to 3.0 fb -1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. A model-independent analysis of the angular moments demonstrates the presence of resonances with spins 1, 2 and 3 at high D + π - mass. The data are fitted with an amplitude model composed of a quasi-model-independent function to describe the D + π - S wave together with virtual contributions from the D*(2007) 0 and B* 0 states, and components corresponding to the D$*\atop{2}$(2460) 0 , D$*\atop{1}$(2680) 0 , D$*\atop{3}$(2760) 0 and D$*\atop{2}$(3000) 0 resonances. The masses and widths of these resonances are determined together with the branching fractions for their production in B- → D + π - π - decays. The D + π - S wave has phase motion consistent with that expected due to the presence of the D$*\atop{0}$(2400) 0 state. These results constitute the first observations of the D$*\atop{3}$(2760) 0 and D$*\atop{2}$(3000) 0 resonances, with significances of 10σ and 6.6σ, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurements of charmless b-hadron decays at CDF; first evidence for the annihilation $B^0_s \to \pi^+ \pi^-$ decay mode.

In this thesis I report on several results obtained from an accurate analysis of the $Bhh$ data sample: Annihilation decay modes: using 6 fb$^{-1}$ of data collected by the CDF experiment, I obtained the first evidence of the $B_s^0\to \pi^+ \pi^-$ decay mode, with a significance of about 3.7$\sigma$, and I performed the most precise measurement of the Branching Ratio of the $B_d^0\to K^+ K^-$ decay mode at the time, corresponding to an excess of 2$\sigma$ level. These measurements have important consequences as discussed in the previous sections: the comparison between these branching fractions and the theoretical predictions provides unique information for tuning the phenomenological models. Our results prompted intense theoretical work both using pQCD and QCDF approaches to accommodate the discrepancies between predictions and experimental results. CP violation: using the full CDF 10 fb$^{-1}$ of data collected by the CDF experiment, I found evidence of the \textbf{CP violation} of $B_s^0 \to K \pi$ decay mode, with a significance of 3$\sigma$, confirming the result recently obtained at LHCb. I also measured the CP asymmetries of the $B_d^0 \to K \pi$ decay modes, in agreement and of comparable resolution with the b-factories experiments, while the most precise measurement up to date is from LHCb. The precision reached in the Acp($B_s^0 \to K \pi$ ) measurement gives the possibility to perform interesting checks of the Standard Model predictions, explained in the previous sections. I also obtained the world's best measurements of the CP asymmetries in $\Lambda_b^0 \to p\pi$ and $\Lambda_b^0 \to pK$ decay modes. These measurements are unique and represent a step forward in the understanding of the \CP\ violation phenomena in the relatively unexplored $\Lambda_b^0$ sector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Extreme-Scale Distribution-Based Data Analysis

Scientists overview and identify regions of interest by transforming data into compact information descriptors that characterize simulation results and allow detailed analysis on demand. Among many existing feature descriptors, statistical information derived from data samples is a promising approach to taming the big data avalanche because data distributionscomputed from a population can compactly describe the presence and characteristics of salient data features with minimal data movement. The ability to computationally summarize and process data using distributions also provides an efficient and representative capture of information that can adjust to size and resource constraints, with the added benefit that uncertainty associated with results can be quantified and communicated. In this project, we have developed a distribution-based data analysis and visualization framework for optimizing in situ processing and analysis of extreme-scale scientific data.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Improved Data Interpretation through Identification of Time Series Periodicity Changes

Analysis and interpretation of time series data is easiest when the data values occur at uniform intervals in time, but actual data may have differing data sampling frequencies, such as monthly and daily readings. Applying data analysis techniques, such as smoothing, to such a data set may not give a representative result between time segments. The ability to automatically distinguish time segments of differing data frequency would provide a means for applying data analysis independently to each segment, though a suitable blending at segment boundaries would be required. A method for detecting frequency changes was developed and applied to Gaussian and median smoothing of hydraulic head data from groundwater wells at the U.S. Department of Energy Hanford Site in southeastern Washington state. The process identifies time segments of high-frequency (daily) or low-frequency (greater than daily) data using adjusted-bandwidth Gaussian kernel density estimation and a threshold value, which are further refined to address small blocks of low-frequency data within larger blocks of high-frequency data. User-selectable levels of smoothing are then applied independently to the time segments prior to combining the segment results for a single smoothed data set. This time segment identification approach provides effective low- and high-frequency data separation, which provides a method to apply data analysis independently to each time segment.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Experiment GlueX: Early results and future plans

The GlueX experiment in Hall D at Jefferson Lab has just finished the data taking for the first phase of the project. The main purpose of the experiment is the search for hybrid mesons in the light quark sector. The experiment studies interactions of a linearly polarized photon beam made by 11.7 GeV electrons with a hydrogen target, with the help of a nearly hermetic spectrometer for charged and neutral particles. About 25% of the data acquired have been analyzed. The first physics results include studies of photoproduction of light mesons by a linearly polarized beam, and a measurement of the J/psi photoproduction close to threshold. The latter allows to search for the LHCb's pentaquarks in photoproduction. The first results on the search for hybrid mesons are expected after the whole data sample has been analyzed. The next stage of GlueX data taking will include a new detector for charged kaon identification, and will run at higher luminosity, in order to search for hybrid mesons decaying to strange particles, as well as to contribute to the spectroscopy of hyperons. I will also discuss a proposal to modify the Hall D facility in order to provide a K0L beam, which would allow to study strange baryons and mesons at a new level of precision.

Chudakov, Eugene↗
DOE OSTI2013

GPS Data Filtration Method for Drive Cycle Analysis Applications

When employing GPS data acquisition systems to capture vehicle drive-cycle information, a number of errors often appear in the raw data samples, such as sudden signal loss, extraneous or outlying data points, speed drifting, and signal white noise, all of which limit the quality of field data for use in downstream applications. Unaddressed, these errors significantly impact the reliability ofsource data and limit the effectiveness of traditional drive-cycle analysis approaches and vehicle simulation software. Without reliable speed and time information, the validity of derived metrics for drive cycles, such as acceleration, power, and distance, become questionable. This study explores some of the common sources of error present in raw onboard GPS data and presents a detailedfiltering process designed to correct for these issues. Test data from both light and medium/heavy duty applications are examined to illustrate the effectiveness of the proposed filtration process across the range of vehicle vocations. Graphical comparisons of raw and filtered cycles are presented, and statistical analyses are performed to determine the effects of the proposed filtration processon raw data. Finally, an evaluation of the overall benefits of data filtration on raw GPS data and present potential areas for continued research is presented.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1974

Transport dynamics of a high-power-density matrix-type hydrogen-oxygen fuel cell

Experimental transport dynamics tests were made on a space power fuel cell of current design. Various operating transients were introduced and transport-related response data were recorded with fluidic humidity sensing instruments. Also, sampled data techniques were developed for measuring the cathode-side electrolyte concentration during transient operation.

Prokopius, P. R.↗
NASA NTRS1978

A new two-dimensional oscillating wing apparatus for unsteady aerodynamics research

An apparatus for experimental research into unsteady transonic flows is described. The apparatus, as installed in the NASA-Ames 11 by 11 Foot Transonic Wind Tunnel, can impart full two-degree-of-freedom motions at reduced frequencies to 0.3, oscillatory amplitudes to tn-2 degs, mean angles to 12 degs, Mach numbers to 1.4 and Reynolds numbers to 12x10. The test wing is fully instrumented for dynamic waveform measurements and the data can be acquired, processed, and displayed in real-time with a new computational data acquisition system. Following a description of the apparatus, sample data from a recently completed test program is presented.

Davis, S. S.↗
NASA NTRS1978

A declaration of independence for Mg/Si

The weak covariation that exists between Al/Si and Mg/Si for large areas of the lunar surface is little, if any, stronger than that forced on a random set of numbers that are subject to closure. The Mg and Al variations implied by the Mg/Si and Al/Si intensity ratio data are qualitatively like those seen in lunar soil sample data. Two petrogenetic provinces are suggested for terra materials; one appears to have 50% higher Mg values than the other. Using the improved data, Mg/Si variations can be studied at a signal-to-noise ratio greater than 5/1.

Hubbard, N.↗
NASA NTRS1980

Lunar highland crustal models based on iron concentrations - Isostasy and center-of-mass displacement

Data is introduced on the iron concentrations of the lunar surface which have been refined by means of convolution corrections to restore the spatial resolution and contrast lost by the omnidirectional spectrometer. This refined iron data is synthesized with other orbital seismic, and lunar sample data to derive highland crustal density and thickness, and isostasy and lunar centers of mass models are examined in light of this new information. A model is developed by which highland crustal density is calculated for each highland region from orbital observations of Fe, Mg and Ti concentrations. The results of this model are presented numerically and graphically for 35 highland and two non-highland regions. Density and thickness results are then applied to two long-standing lunar problems: (1) the nature of highland isostasy, which is shown to be controlled by crustal thickness rather than density, and (2) the separation of the moon's mass and figure centers, which is shown to be due to the crustal thickness difference between the lunar near and far sides.

Haines, E. L.↗
NASA NTRS1989

The density distribution of refractory elements away from the Galactic plane

The density distributions of the three refractory elements Ti II, Ca II, and Fe II away from the Galactic plane are compared with the distribution of hydrogen and dust by examining plots of N s in b versus z. It is found that Ti II and Ca II are considerably more extended in z than the H I and dust and that Fe II has an intermediate extension. Although the results are strongly influenced by sample bias, the indicated exponential scale heights for the data sample are h(Ti II) not less than 2 kpc, h(Ca II) = 1 kpc, h(Fe II) = 0.5 kpc, H(H I) = 0.3 kpc, and h(E/B-V) = 0.1 kpc. Furthermore, it is demonstrated that Ti II and Ca II are much more smoothly distributed in space than the hydrogen or dust. The large scale heights for Ti II and Ca II and their smooth distributions are most easily understood as the effect of a mixture along the line of sight of two H I phases namely, a diffuse cloud phase, in which nearly all of the Ti and Ca are tied up in dust, and an intercloud medium, where refractory elements are less depleted. It is found that Ti II and Ca II mostly trace the smoothly distributed intercloud medium. The smoothness of the distributions of Ti II and Ca II makes them candidates for use as distance indicators.

Edgar, Richard J.↗