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DOE OSTI2016

Use of local noise power spectrum and wavelet analysis in quantitative image quality assurance for EPIDs

Purpose: To investigate the use of local noise power spectrum (NPS) to characterize image noise and wavelet analysis to isolate defective pixels and inter-subpanel flat-fielding artifacts for quantitative quality assurance (QA) of electronic portal imaging devices (EPIDs). Methods: A total of 93 image sets including custom-made bar-pattern images and open exposure images were collected from four iViewGT a-Si EPID systems over three years. Global quantitative metrics such as modulation transform function (MTF), NPS, and detective quantum efficiency (DQE) were computed for each image set. Local NPS was also calculated for individual subpanels by sampling region of interests within each subpanel of the EPID. The 1D NPS, obtained by radially averaging the 2D NPS, was fitted to a power-law function. The r-square value of the linear regression analysis was used as a singular metric to characterize the noise properties of individual subpanels of the EPID. The sensitivity of the local NPS was first compared with the global quantitative metrics using historical image sets. It was then compared with two commonly used commercial QA systems with images collected after applying two different EPID calibration methods (single-level gain and multilevel gain). To detect isolated defective pixels and inter-subpanel flat-fielding artifacts, Haar wavelet transform was applied on the images. Results: Global quantitative metrics including MTF, NPS, and DQE showed little change over the period of data collection. On the contrary, a strong correlation between the local NPS (r-square values) and the variation of the EPID noise condition was observed. The local NPS analysis indicated image quality improvement with the r-square values increased from 0.80 ± 0.03 (before calibration) to 0.85 ± 0.03 (after single-level gain calibration) and to 0.96 ± 0.03 (after multilevel gain calibration), while the commercial QA systems failed to distinguish the image quality improvement between the two calibration methods. With wavelet analysis, defective pixels and inter-subpanel flat-fielding artifacts were clearly identified as spikes after thresholding the inversely transformed images. Conclusions: The proposed local NPS (r-square values) showed superior sensitivity to the noise level variations of individual subpanels compared with global quantitative metrics such as MTF, NPS, and DQE. Wavelet analysis was effective in detecting isolated defective pixels and inter-subpanel flat-fielding artifacts. The proposed methods are promising for the early detection of imaging artifacts of EPIDs.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Influence of Electrolyte Modulus on the Local Current Density at a Dendrite Tip on a Lithium Metal Electrode

Understanding and controlling the electrochemical deposition of lithium is imperative for the safe use of rechargeable batteries with a lithium metal anode. Solid block copolymer electrolyte membranes are known to enhance the stability of lithium metal anodes by mechanically suppressing the formation of lithium protrusions during battery charging. Time-resolved hard X-ray microtomography was used to monitor the internal structure of a symmetric lithium-polymer cell during galvanostatic polarization. The microtomography images were used to determine the local rate of lithium deposition, i.e. local current density, in the vicinity of a lithium globule growing through the electrolyte. Measurements of electrolyte displacement enabled estimation of local stresses in the electrolyte. At early times, the current density was maximized at the globule tip, as expected from simple current distribution arguments. At later times, the current density was maximized at the globule perimeter. We show that this phenomenon is related to the local stress fields that arise as the electrolyte is deformed. The local current density, normalized for the radius of curvature, decreases with increasing compressive stresses at the lithium-polymer interface. To our knowledge, our study provides the first direct measurement showing the influence of local mechanical stresses on the deposition kinetics at lithium metal electrodes.

25 ENERGY STORAGE↗

DOE OSTI2016

Identifying local structural states in atomic imaging by computer vision

Abstract The availability of atomically resolved imaging modalities enables an unprecedented view into the local structural states of materials, which manifest themselves by deviations from the fundamental assumptions of periodicity and symmetry. Consequently, approaches that aim to extract these local structural states from atomic imaging data with minimal assumptions regarding the average crystallographic configuration of a material are indispensable to advances in structural and chemical investigations of materials. Here, we present an approach to identify and classify local structural states that is rooted in computer vision. This approach introduces a definition of a structural state that is composed of both local and nonlocal information extracted from atomically resolved images, and is wholly untethered from the familiar concepts of symmetry and periodicity. Instead, this approach relies on computer vision techniques such as feature detection, and concepts such as scale invariance. We present the fundamental aspects of local structural state extraction and classification by application to simulated scanning transmission electron microscopy images, and analyze the robustness of this approach in the presence of common instrumental factors such as noise, limited spatial resolution, and weak contrast. Finally, we apply this computer vision-based approach for the unsupervised detection and classification of local structural states in an experimental electron micrograph of a complex oxides interface, and a scanning tunneling micrograph of a defect-engineered multilayer graphene surface.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2011

Re-visit local coupling correction in the interaction regions of RHIC

In this article we will re-visit the local coupling correction in the interaction regions (IRs) of the Relativistic Heavy Ion Collider (RHIC). We will review the measurement data of triplet quadrupole rolls, the local coupling correction strengths in the RHIC control system, and the methods for the local coupling correction with local skew quadrupole correctors. Based on the in-turnnel measurement data of triplet roll errors in 2011, we will analytically calculate and simulate IR-bump method to find out the local skew correction strengths and compare them at store and at injection with the Blue and Yellow ring lattices in the 2011 polarized proton (p-p) and Au-Au runs. The vertical dispersion from the triplet roll errors, local and global coupling correction skew quadrupoles, and the vertical dipole correctors are calculated and discussed.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

Re-Visit Local Coupling Correction in the Interaction Regions of RHIC

43 PARTICLE ACCELERATORS↗

DOE OSTI2026

Studies of Localization Effects on Transverse Kinematic Imbalance in the GENIE Generator

The forthcoming Deep Underground Neutrino Experiment (DUNE) requires precise modeling of neutrino--nucleus interactions to achieve its neutrino-oscillation measurement goals. GENIE, the Monte Carlo event generator used by DUNE and other Fermilab-based experiments as a central value model for neutrino-nucleus cross sections, exhibits known discrepancies in comparison to MicroBooNE cross section data, especially when considering neutrino scattering events' transverse kinematic imbalance (TKI). For quasielastic-like measurements, the data show a larger transverse missing momentum tail while maintaining a peak similar to that predicted by the baseline GENIE model. Previous attempts at a solution include variations of final-state interaction (FSI) strengths, incorrectly decreasing both the peak and tail, thus leaving the discrepancy unresolved. This work investigates whether inconsistencies between local and global treatments of intranuclear physics contribute to the observed mismodeling. In this work, GENIE FSI routines have been modified to directly utilize intranuclear particle positions, thereby introducing a newly localized momentum treatment in correlation with the nominal density in both the hA and hN intranuclear cascade models for their 2018 and 2025 variants. Meson-exchange-current (MEC) localization was also tested for the hN 2018 model. Comparisons of the intranuclear nucleons' ("scattering center") momentum and its radial dependence validate the localization implementation. However, while such consistent localization produces modest changes in the proton momentum spectrum at low-to-medium momenta, only small changes are observed in the TKI distributions. These changes are insufficient to account for the discrepancy with MicroBooNE data. Although a localized treatment improves the internal consistency of the GENIE model, the origin of the TKI discrepancy remains unresolved by such a solution.

Bulla, Braden [Ctr. Coll., Danville; Fermilab]↗

DOE OSTI2026

Localized Interactions in Neutrino Simulations

The Deep Underground Neutrino Experiment (DUNE) requires precise modeling of neutrino--nucleus interactions to achieve its neutrino-oscillation measurement goals. GENIE, the Monte Carlo event generator used by DUNE, exhibits a known discrepancy with MicroBooNE measurements of transverse kinematic imbalance (TKI): the data display a larger high-TKI tail while maintaining a peak similar to that predicted by the baseline GENIE model. Previous variations of final-state interaction (FSI) strength affected both the peak and the tail and therefore did not resolve the discrepancy. This work investigates whether inconsistencies between local and global treatments of intranuclear physics contribute to the observed mismodeling. The GENIE FSI routines were modified to use the particle position when generating nucleons, thereby introducing a local-density treatment in the hA and hN intranuclear models for their 2018 and 2025 implementations. Meson-exchange-current (MEC) localization was also tested for the hN 2018 model. Comparisons of the intranuclear scattering-center momentum and its radial dependence confirm that the localization was implemented as intended. Localization produces modest changes in the proton momentum spectrum, primarily at low momentum, but only a small change in the TKI distribution between approximately \SI{0.25}{\giga\electronvolt} and \SI{0.40}{\giga\electronvolt}. These changes are insufficient to account for the discrepancy with MicroBooNE data. Although a localized treatment improves the internal consistency of the GENIE model, the origin of the TKI discrepancy remains unresolved.

Bulla, Braden [Unlisted, US, IL]↗

DOE OSTI2024

Sound-localization-related activation and functional connectivity of dorsal auditory pathway in relation to demographic, cognitive, and behavioral characteristics in age-related hearing loss

Background Patients with age-related hearing loss (ARHL) often struggle with tracking and locating sound sources, but the neural signature associated with these impairments remains unclear. Materials and methods Using a passive listening task with stimuli from five different horizontal directions in functional magnetic resonance imaging, we defined functional regions of interest (ROIs) of the auditory “where” pathway based on the data of previous literatures and young normal hearing listeners ( n = 20). Then, we investigated associations of the demographic, cognitive, and behavioral features of sound localization with task-based activation and connectivity of the ROIs in ARHL patients ( n = 22). Results We found that the increased high-level region activation, such as the premotor cortex and inferior parietal lobule, was associated with increased localization accuracy and cognitive function. Moreover, increased connectivity between the left planum temporale and left superior frontal gyrus was associated with increased localization accuracy in ARHL. Increased connectivity between right primary auditory cortex and right middle temporal gyrus, right premotor cortex and left anterior cingulate cortex, and right planum temporale and left lingual gyrus in ARHL was associated with decreased localization accuracy. Among the ARHL patients, the task-dependent brain activation and connectivity of certain ROIs were associated with education, hearing loss duration, and cognitive function. Conclusion Consistent with the sensory deprivation hypothesis, in ARHL, sound source identification, which requires advanced processing in the high-level cortex, is impaired, whereas the right–left discrimination, which relies on the primary sensory cortex, is compensated with a tendency to recruit more resources concerning cognition and attention to the auditory sensory cortex. Overall, this study expanded our understanding of the neural mechanisms contributing to sound localization deficits associated with ARHL and may serve as a potential imaging biomarker for investigating and predicting anomalous sound localization.

Wu, Junzhi↗

DOE OSTI2016

LOCAL ANALOGS FOR HIGH-REDSHIFT GALAXIES: RESEMBLING THE PHYSICAL CONDITIONS OF THE INTERSTELLAR MEDIUM IN HIGH-REDSHIFT GALAXIES

We present a sample of local analogs for high-redshift galaxies selected in the Sloan Digital Sky Survey (SDSS). The physical conditions of the interstellar medium (ISM) in these local analogs resemble those in high-redshift galaxies. These galaxies are selected based on their positions in the [O iii]/Hβ versus [N ii]/Hα nebular emission-line diagnostic diagram. We show that these local analogs share similar physical properties with high-redshift galaxies, including high specific star formation rates (sSFRs), flat UV continuums, and compact galaxy sizes. In particular, the ionization parameters and electron densities in these analogs are comparable to those in z ≃ 2–3 galaxies, but higher than those in normal SDSS galaxies by ≃0.6 dex and ≃0.9 dex, respectively. The mass–metallicity relation (MZR) in these local analogs shows −0.2 dex offset from that in SDSS star-forming galaxies at the low-mass end, which is consistent with the MZR of the z∼2--3 galaxies. We compare the local analogs in this study with those in other studies, including Lyman break analogs (LBA) and green pea (GP) galaxies. The analogs in this study share a similar star formation surface density with LBAs, but the ionization parameters and electron density in our analogs are higher than those in LBAs by factors of 1.5 and 3, respectively. The analogs in this study have comparable ionization parameters and electron densities to the GP galaxies, but our method can select galaxies in a wider redshift range. We find the high sSFR and SFR surface density can increase the electron density and ionization parameters, but still cannot fully explain the difference in ISM condition between nearby galaxies and the local analogs/high-redshift galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2017

Facilitating Follow-up of LIGO–Virgo Events Using Rapid Sky Localization

We discuss an algorithm for accurate and very low-latency (<1 s) localization of gravitational-wave (GW) sources using only the relative times of arrival, relative phases, and relative signal-to-noise ratios for pairs of detectors. The algorithm is independent of distances and masses to leading order, and can be generalized to all discrete (as opposed to stochastic and continuous) sources detected by ground-based detector networks. Our approach is similar to that of BAYESTAR with a few modifications, which result in increased computational efficiency. For the LIGO two-detector configuration (Hanford+Livingston) operating in O1 we find a median 50% (90%) localization of 143 deg{sup 2} (558 deg{sup 2}) for binary neutron stars. We use our algorithm to explore the improvement in localization resulting from loud events, finding that the loudest out of the first 4 (or 10) events reduces the median sky-localization area by a factor of 1.9 (3.0) for the case of two GW detectors, and 2.2 (4.0) for three detectors. We also consider the case of multi-messenger joint detections in both the gravitational and the electromagnetic radiation, and show that joint localization can offer significant improvements (e.g., in the case of LIGO and Fermi /GBM joint detections). We show that a prior on the binary inclination, potentially arising from GRB observations, has a negligible effect on GW localization. Our algorithm is simple, fast, and accurate, and may be of particular utility in the development of multi-messenger astronomy.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2026

Improved Spectral Classification of Local K/M Dwarfs in SDSS Surveys. I. Chemodynamic Validation and Metallicity Calibration

An examination of 109,276 spectra of low-mass stars in the Sloan Digital Sky Survey (SDSS) data archive, collected pre-2010, provides a broad collection of K/M (sub)dwarfs tracing the local (d ≲ 250 pc) population of the thin-disk, thick-disk, and halo, based on 3D kinematics. These populations have distinct metallicities and kinematics, which should be reflected in lower-mass members. One complication is measuring metallicities of M dwarfs from low-resolution spectroscopy or photometry alone remains a challenge, even with the availability of Gaia data. To better characterize physical parameters of low-mass stars observed by SDSS, we define a set of 536 improved, empirical K/M dwarf classification templates to more accurately determine spectral subtypes (K5.5–M8.5) and morphology classes (MCs) (0.5–12.5). We select the best-fit template to every archival SDSS spectrum in the range 5000–8000 Å based on minimum χ 2 value. We then use secondary metallicity estimators to calibrate the most likely [Fe/H] values corresponding to the assigned MC. We confirm that the most metal-rich K/M dwarfs have thin-disk kinematics, and we observe the known effect of Galactic radial metallicity migration, which we confirm is strongly imprinted in the chemodynamics of the local disk M dwarfs. Confirmation of these chemodynamic trends validates the precision of our improved templates for estimating [Fe/H] for M (sub)dwarfs, notably at the low-metallicity end (–3 < [Fe/H] < –1). Substructure in the chemodynamics of the most metal-poor K/M subdwarfs begins to distinguish between local Gaia-Enceladus and local in situ halo objects. This methodology opens the door to use the ubiquitous, local K/M (sub)dwarfs to trace local Galactic chemodynamics with the highest possible resolution.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1972

Experiments with program locality.

Attempt to validate experimentally several intrinsic models for the concept of program locality. The models considered are a two-parameter simple locality model, a simple least recently used stack model, and an independent reference model. The first two models appear to produce good approximations to real world behavior, while the independent reference model, because of its static concept of locality, does very poorly. The working set is shown to be a good estimator of the simple two-parameters model's locality, provided that the locality does not change too rapidly. The working set exactly measures the locality in the case of the least recently used stack model and is thus nearly optimal for programs whose behavior can be closely approximated by this model.

Spirn, J. R.↗

NASA NTRS1993

Knowledge-based control for robot self-localization

Autonomous robot systems are being proposed for a variety of missions including the Mars rover/sample return mission. Prior to any other mission objectives being met, an autonomous robot must be able to determine its own location. This will be especially challenging because location sensors like GPS, which are available on Earth, will not be useful, nor will INS sensors because their drift is too large. Another approach to self-localization is required. In this paper, we describe a novel approach to localization by applying a problem solving methodology. The term 'problem solving' implies a computational technique based on logical representational and control steps. In this research, these steps are derived from observing experts solving localization problems. The objective is not specifically to simulate human expertise but rather to apply its techniques where appropriate for computational systems. In doing this, we describe a model for solving the problem and a system built on that model, called localization control and logic expert (LOCALE), which is a demonstration of concept for the approach and the model. The results of this work represent the first successful solution to high-level control aspects of the localization problem.

Bennett, Bonnie Kathleen Holte↗

NASA NTRS1994

Nonlinear equilibration of localized instabilities on a baroclinic jet

Dynamical mechanisms underlying the equilibration of absolute instability are examined in a nonlinear, quasigeostrophic, two-layer model. The key to understanding the nonlinear equilibration is in recognizing that linear absolute instabilities can be stabilized both by a reduction of the vertical shear and by enhancement of the mean barotropic velocity. In a localized domain, the equilibration process proceeds with the creation of locally convectively unstable regions downstream, which encroach onto the locally absolutely unstable region until the local instability is suppressed. That local instabilities exist only if absolutely unstable regions span a minimum size is verified by eigenvalue calculations of three-dimensional flows. Numerical examples suggest that this critical size is at least 9000 km for a wide range of parameter values chosen to investigate the midlatitude storm tracks. Fluctuations arising from local absolute instability obtain maximum amplitude in the downstream convectively unstable regions rather than in the absolutely unstable regions themselves. Together, these results suggest that if an equilibrated absolute instability were to occur in midlatitudes, a zonal band of surface easterlies exceeding 900 km would be required and the associated enhanced variances would not be found coincident with the regions of absolute instability.

Delsole, Timothy M.↗

NASA NTRS2002

Precipitation Recycling and the Vertical Distribution of Local and Remote Sources of Water for Precipitation

Precipitation recycling is defined as the amount of water that evaporates from a region that precipitates within the same region. This is also interpreted as the local source of water for precipitation. In this study, the local and remote sources of water for precipitation have been diagnosed through the use of passive constituent tracers that represent regional evaporative sources along with their transport and precipitation. We will discuss the differences between this method and the simpler bulk diagnostic approach to precipitation recycling. A summer seasonal simulation has been analyzed for the regional sources of the United States Great Plains precipitation. While the tropical Atlantic Ocean (including the Gulf of Mexico) and the local continental sources of precipitation are most dominant, the vertically integrated column of water contains substantial water content originating from the Northern Pacific Ocean, which is not precipitated. The vertical profiles of regional water sources indicate that local Great Plains source of water dominates the lower troposphere, predominantly in the PBL. However, the Pacific Ocean source is dominant over a large portion of the middle to upper troposphere. The influence of the tropical Atlantic Ocean is reasonably uniform throughout the column. While the results are not unexpected given the formulation of the model's convective parameterization, the analysis provides a quantitative assessment of the impact of local evaporation on the occurrence of convective precipitation in the GCM. Further, these results suggest that local source of water is not well mixed throughout the vertical column.

Bosilovich, Michael G.↗

NASA NTRS2001

Gravitoinertial force magnitude and direction influence head-centric auditory localization

We measured the influence of gravitoinertial force (GIF) magnitude and direction on head-centric auditory localization to determine whether a true audiogravic illusion exists. In experiment 1, supine subjects adjusted computer-generated dichotic stimuli until they heard a fused sound straight ahead in the midsagittal plane of the head under a variety of GIF conditions generated in a slow-rotation room. The dichotic stimuli were constructed by convolving broadband noise with head-related transfer function pairs that model the acoustic filtering at the listener's ears. These stimuli give rise to the perception of externally localized sounds. When the GIF was increased from 1 to 2 g and rotated 60 degrees rightward relative to the head and body, subjects on average set an acoustic stimulus 7.3 degrees right of their head's median plane to hear it as straight ahead. When the GIF was doubled and rotated 60 degrees leftward, subjects set the sound 6.8 degrees leftward of baseline values to hear it as centered. In experiment 2, increasing the GIF in the median plane of the supine body to 2 g did not influence auditory localization. In experiment 3, tilts up to 75 degrees of the supine body relative to the normal 1 g GIF led to small shifts, 1--2 degrees, of auditory setting toward the up ear to maintain a head-centered sound localization. These results show that head-centric auditory localization is affected by azimuthal rotation and increase in magnitude of the GIF and demonstrate that an audiogravic illusion exists. Sound localization is shifted in the direction opposite GIF rotation by an amount related to the magnitude of the GIF and its angular deviation relative to the median plane.

NASA Discipline Neuroscience↗

NASA NTRS1992

The use of additive and subtractive approaches to examine the nuclear localization sequence of the polyomavirus major capsid protein VP1

A nuclear localization signal (NLS) has been identified in the N-terminal (Ala1-Pro-Lys-Arg-Lys-Ser-Gly-Val-Ser-Lys-Cys11) amino acid sequence of the polyomavirus major capsid protein VP1. The importance of this amino acid sequence for nuclear transport of VP1 protein was demonstrated by a genetic "subtractive" study using the constructs pSG5VP1 (full-length VP1) and pSG5 delta 5'VP1 (truncated VP1, lacking amino acids Ala1-Cys11). These constructs were used to transfect COS-7 cells, and expression and intracellular localization of the VP1 protein was visualized by indirect immunofluorescence. These studies revealed that the full-length VP1 was expressed and localized in the nucleus, while the truncated VP1 protein was localized in the cytoplasm and not transported to the nucleus. These findings were substantiated by an "additive" approach using FITC-labeled conjugates of synthetic peptides homologous to the NLS of VP1 cross-linked to bovine serum albumin or immunoglobulin G. Both conjugates localized in the nucleus after microinjection into the cytoplasm of 3T6 cells. The importance of individual amino acids found in the basic sequence (Lys3-Arg-Lys5) of the NLS was also investigated. This was accomplished by synthesizing three additional peptides in which lysine-3 was substituted with threonine, arginine-4 was substituted with threonine, or lysine-5 was substituted with threonine. It was found that lysine-3 was crucial for nuclear transport, since substitution of this amino acid with threonine prevented nuclear localization of the microinjected, FITC-labeled conjugate.

Non-NASA Center↗

NASA NTRS2005

Local Flow Conditions for Propulsion Experiments on the NASA F-15B Propulsion Flight Test Fixture

Local flow conditions were measured underneath the National Aeronautics and Space Administration F-15B airplane to support development of future experiments on the Propulsion Flight Test Fixture (PFTF). The local Mach number and flow angles were measured using a conventional air data boom on a cone-cylinder mounted under the PFTF and compared with the airplane air data nose boom measurements. At subsonic flight speeds, the airplane and PFTF Mach numbers were approximately equal. Transonic Mach number values were up to 0.1 greater at the PFTF than the airplane, which is a counterintuitive result. The PFTF local supersonic Mach numbers were as much as 0.46 less than the airplane values. The maximum local Mach number at the PFTF was approximately 1.6 at an airplane Mach number near 2.0. The PFTF local angle of attack was negative at all Mach numbers, ranging from -3 to -8 degrees. When the airplane angle of sideslip was zero, the PFTF local value was zero between Mach 0.8 and Mach 1.1, -2 degrees between Mach 1.1 and Mach 1.5, and increased from zero to 1 degree from Mach 1.5 to Mach 2.0. Airplane inlet shock waves crossed the aerodynamic interface plane between Mach 1.85 and Mach 1.90.

Vachon, Michael J.↗