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All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Soil, water, and vegetation conditions in South Texas

The author has identified the following significant results. Reflectance measurements with a field spectroradiometer on nine dates (between December 9 and April 8) during the growing season of two wheat varieties, Milam and Penjamo, showed that the reflectance curves had the characteristic shape of vegetated surfaces by 4 weeks after the emergence. Green light (0.55 micron) reflectance was maximal and between water absorption bands (1.65 and 2.2 microns) reflectance was minimal when green vegetation development was greatest. Computer classification was accomplished for 81,000 hectare coastal rangeland area for October 13 and December 10, 1975, overpass dates. A hard freeze occurred between these two dates and many of the deciduous woody species defoliated so that more light penetrated to the herbaceous understory in December than in October.

Wiegand, C. L.↗
NASA NTRS1999

JANNAF 18th Propulsion Systems Hazards Subcommittee Meeting

This volume, the first of two volumes is a compilation of 18 unclassified/unlimited-distribution technical papers presented at the Joint Army-Navy-NASA-Air Force (JANNAF) 18th Propulsion Systems Hazards Subcommittee (PSHS) meeting held jointly with the 36th Combustion Subcommittee (CS) and 24th Airbreathing Propulsion Subcommittee (APS) meetings. The meeting was held 18-21 October 1999 at NASA Kennedy Space Center and The DoubleTree Oceanfront Hotel, Cocoa Beach, Florida. Topics covered at the PSHS meeting include: shaped charge jet and kinetic energy penetrator impact vulnerability of gun propellants; thermal decomposition and cookoff behavior of energetic materials; violent reaction; detonation phenomena of solid energetic materials subjected to shock and impact stimuli; and hazard classification, insensitive munitions, and propulsion systems safety.

Cocchiaro, James E.↗
NASA NTRS1988

Laser agile illumination for object tracking and classification - Feasibility study

The 'agile illumination' concept for discrimination between ICBM warheads and decoys involves a two-aperture illumination with coherent light, diffraction of light by propagation, and a resulting interference pattern on the object surface. A scanning two-beam interference pattern illuminates one object at a time; depending on the shape, momentum, spinning, and tumbling characteristics of the interrogated object, different temporal signals will be obtained for different classes of objects.

Scholl, Marija S.↗
DOE OSTI2018

Pulse discrimination with a Gaussian mixture model on an FPGA

A Gaussian Mixture Model (GMM) based machine learning algorithm has been applied to the problem of gamma/neutron pulse shape discrimination (PSD). The algorithm has been successfully implemented on a standard PC as well as a field programmable gate array (FPGA). We describe the GMM classifier and its implementation on these two different types of hardware. We compare the performance of the algorithm on these two platforms against each other, along with other standard techniques applied in PSD. Our results show that the FPGA-based GMM classifier outperforms the standard PSD techniques in terms of classification accuracy at low particle energy and executes more quickly than its CPU-based counterpart.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Robust Containment Queries over Collections of Rational Parametric Curves via Generalized Winding Numbers

Point containment queries for regions bound by watertight geometric surfaces, i.e., closed and without self-intersections, can be evaluated straightforwardly with a number of well-studied algorithms. When this assumption on domain geometry is not met, such methods are either unusable, or prone to misclassifications that can lead to cascading errors in downstream applications. More robust point classification schemes based on generalized winding numbers have been proposed, as they are indifferent to these imperfections. However, existing algorithms are limited to point clouds and collections of linear elements. We extend this methodology to encompass more general curved shapes with an algorithm that evaluates the winding number scalar field over unstructured collections of rational parametric curves. In particular, we evaluate the winding number for each curve independently, making the derived containment query robust to how the curves are arranged. We ensure geometric fidelity in our queries by treating each curve as equivalent to an adaptively constructed polyline that provably has the same generalized winding number at the point of interest. Our algorithm is numerically stable for points that are arbitrarily close to the model, and explicitly treats points that are coincident with curves. We demonstrate the improvements in computational performance granted by this method over conventional techniques as well as the robustness induced by its application.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

3D face analysis for demographic biometrics

Despite being increasingly easy to acquire, 3D data is rarely used for face-based biometrics applications beyond identification. Recent work in image-based demographic biometrics has enjoyed much success, but these approaches suffer from the well-known limitations of 2D representations, particularly variations in illumination, texture, and pose, as well as a fundamental inability to describe 3D shape. This paper shows that simple 3D shape features in a face-based coordinate system are capable of representing many biometric attributes without problem-specific models or specialized domain knowledge. The same feature vector achieves impressive results for problems as diverse as age estimation, gender classification, and race classification.

Tokola, Ryan A↗
NASA NTRS1984

Classification of volcanoes of the Kane Patera Quadrangle of Io: Proportions of lava flows and pyroclastic flows

Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.

Elston, W. E.↗
DOE OSTI2022

Classification of Orbits in Poincare Maps Using Machine Learning

Poincare plots, also called Poincare maps, are used by plasma physicists to understand the behavior of magnetically confined plasma in numerical simulations of a tokamak. These plots are created by the intersection of field lines with a two-dimensional poloidal plane that is perpendicular to the axis of the torus representing the tokamak. A plot is composed of multiple orbits, each created by a different field line as it goes around the torus. Each orbit can have one of four distinct shapes, or classes, that indicate changes in the topology of the magnetic fields confining the plasma. Given the (x, y) coordinates of the points that form an orbit, the analysis task is to assign a class to the orbit, a task that appears ideally suited for a machine learning approach. In this paper, we describe how we overcame two major challenges in solving this problem - creating a high-quality training set, with few mislabeled orbits, and converting the coordinates of the points into features that are discriminating, despite the variation within the orbits of a class and the apparent similarities between orbits of different classes. Our automated approach is not only more objective and accurate than visual classification, but is also less tedious, making it easier for plasma physicists to analyze the topology of magnetic fields from numerical simulations of the tokamak.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Bioaerosol Properties using WIBS from SAIL on Mt. Crested Butte, CO

We deployed a Wideband Integrated Bioaerosol Sensor (WIBS-Neo, DMT) to measure different properties of fluorescent bioaerosol particles (FBAP) during SAIL. Our measurements were collected at the supplementary site on Crested Butte Mountain from inside the ARM Aerosol Observing System (AOS) sampling from the AOS inlet. We had two deployment periods at SAIL during biologically active seasons: summer 2022 (15 June 2022 - 13 September 2022) and spring 2023 (21 March 2023 - 19 June 2023). The WIBS is an online single-particle measurement that detects FBAPs (within a size range of 0.5 - 30 microns in diameter) based on the excitation and emission wavelengths of the individual particles. Using two xenon lamps, the WIBS excites FBAPs at 280 nm and 370 nm. Their emission is detected across two wavebands of 310-400 nm and 420-650 nm. We classified the FBAPs into seven different categories (A, B, C, AB, BC, AC, and ABC) using the classification scheme in Perring et. al. (2015) [1]. Here, we report one-minute averaged number concentration of FBAPs (total and by category) and NFBAPs. We also present one-minute-averaged size distributions and the asymmetry factor (AF, a surrogate for shape) of all FBAPs and NFBAPs. The logarithmic bin width of the size bins is the same as the average bin width of the AOS's optical particle counter (OPC, Grimm) for the range of sizes in which they overlap (26 bins from 0.5 - 30 microns). AF of the particles ranges from 0-100 and is divided into five bins with a linear spacing at increments of 20. The smallest AF bin represents more spherical particles while the largest bin represents more rod-shaped particles. We recommend referring to the readme file for more details of the variables present in the files. [1] Perring, A. E., et al. (2015), Airborne observations of regional variation in fluorescent aerosol across the United States, J. Geophys. Res. Atmos., 120, 1153-1170, doi:10.1002/2014JD022495. Abstract and description of the campaign can be found here: https://www.arm.gov/research/cam

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1981

The RS Canum Venaticorum binaries

This review presents a brief up-to-date summary of observational properties of RS CVn binaries, with emphasis on the photometric. A table of the 69 systems known at this time give the orbital period, mean apparent V magnitude, spectral classification, range of amplitude determinations for the photometric wave, and an indication of known period variations and eclipses. Points considered are (1) the underlying cause of the extreme surface activity, (2) the evolutionary status, (3) the geometric configuration, (4) the temperature, size, shape, location, and lifetimes of the dark spot regions, (5) synchronization of rotational and orbital motion, (6) spectroscopic features in the optical and far ultraviolet, (7) the wave migration, (8) the search for spot cycles, and (9) the orbital period variations produced by the enhanced stellar wind.

Hall, D. S.↗
NASA NTRS2007

Preplanetary Nebulae: A Hubble Space Telescope Imaging Survey and a New Morphological Classification System

Using the Hubble Space Telescope (HST ), we have carried out a survey of candidate preplanetary nebulae (PPNs). We report here our discoveries of objects having well-resolved geometric structures, and we use the large sample of PPNs now imaged with HST (including previously studied objects in this class) to devise a comprehensive morphological classification system for this category of objects. The wide variety of aspherical morphologies which we have found for PPNs are qualitatively similar to those found for young planetary nebulae (PNs) in previous surveys. We also find prominent halos surrounding the central aspherical shapes in many of our objects; these are direct signatures of the undisturbed circumstellar envelopes of the progenitor AGB stars. Although the majority of these have surface brightness distributions consistent with a constant mass-loss rate with a constant expansion velocity, there are also examples of objects with varying mass-loss rates. As in our surveys of young PNs, we find no round PPNs. The similarities in morphologies between our survey objects and young PNs supports the view that the former are the progenitors of aspherical PNs. This suggests that the primary shaping of a PN does not occur during the PN phase via the fast radiative wind of the hot central star, but significantly earlier in its evolution.

AGB and post-AGB↗
DOE OSTI2017

Triton: Igiugig Fish Video Analysis (Project Report)

This document summarizes the analysis of video data collected around the Ocean Renewable Power Company’s RivGen® device in the Kvichak River during July and August 2015. Human (manual) analysis of the data was undertaken and used to develop automated algorithms to detect fish in the frames and describe interaction behavior. In addition, a web application, EyeSea, was developed to combine manual and automated processing, so that ultimately the automated algorithms could be used to identify where human analysis was needed (i.e., when fish are present in video frames). The aim of the project was to develop algorithms that could identify video frames with fish present that could then be used to enable faster manual analysis. However, the project has also identified recommendations for future data collection, and research that could help analysis and interpretation. The manual analysis started to look at all data from the start of the deployment; this was to ensure rare events were seen, and initially focused on night-time data when more fish were present. This process highlighted the amount of time taken to identify fish, and ultimately only 42.33 hours of video were reviewed due to the time-consuming analysis. The data were classified as ‘Fish’, when the reviewer was confident it was a fish, and ‘Maybe’ fish, when it was difficult to distinguish. This was based on the movement, shape and color characteristics. ‘Fish’ were further classified as ‘adult’, ‘juvenile’, or ‘unidentifiable’. Behavioral attributes were noted, which were broadly divided into passive and avoidance activities. In over 42 hours data, there were only 20 potential contact interactions, of which 3 were ‘Maybe’ classifications, 12 were juveniles and 5 were adults; on only one occasion was an actual contact confirmed, and this was an adult fish with the camera, not the turbine itself. This also highlights the difficulties associated with confirming a strike or collision event as occurring or being a near-miss. More interactions were detected at night; this was probably biased by nighttime artificial light use, which may have attracted fish, but also could have increased detection probability as the light is reflected from the fish itself. For the algorithm development, background subtraction, optical flow, and deep learning techniques were considered. The deep learning approach was determined as needing too much training data for this application, and therefore was not continued. The optical flow analysis was considered promising, but did not give immediate results, so would need further investigation. Therefore, background subtraction was the main focus. Three methods of background subtraction were tried: Robust Principal Components Analysis (RPCA), Gaussian Mixture Model (GMM) and Video Background Extraction(ViBE). A classification technique was then applied to the foreground images to determine fish presence. Using this combination, it was found that fish could be accurately detected when occupying more pixels (>200 pixels, 98.2% correct; 100-200 pixels, 99.6% correct; 5-100 pixels, 85.4% correct; 2-5 pixels, 66.3% correct). In parallel, EyeSea was developed to convert the video data to a usable form and to enable manual and automated analysis of the data that would have a standardized output. Recommendations for further research, and standardized methods for data collection are given.

13 HYDRO ENERGY↗
DOE OSTI2020

End-to-End Physics Event Classification with CMS Open Data: Applying Image-Based Deep Learning to Detector Data for the Direct Classification of Collision Events at the LHC

This paper describes the construction of novel end-to-end image-based classifiers that directly leverage low-level simulated detector data to discriminate signal and background processes in pp collision events at the Large Hadron Collider at CERN. To better understand what end-to-end classifiers are capable of learning from the data and to address a number of associated challenges, we distinguish the decay of the standard model Higgs boson into two photons from its leading background sources using high-fidelity simulated CMS Open Data. We demonstrate the ability of end-to-end classifiers to learn from the angular distribution of the photons recorded as electromagnetic showers, their intrinsic shapes, and the energy of their constituent hits, even when the underlying particles are not fully resolved, delivering a clear advantage in such cases over purely kinematics-based classifiers.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

A two-stage method for microcalcification cluster segmentation in mammography by deformable models

Purpose: Segmentation of microcalcification (MC) clusters in x-ray mammography is a difficult task for radiologists. Accurate segmentation is prerequisite for quantitative image analysis of MC clusters and subsequent feature extraction and classification in computer-aided diagnosis schemes. Methods: In this study, a two-stage semiautomated segmentation method of MC clusters is investigated. The first stage is targeted to accurate and time efficient segmentation of the majority of the particles of a MC cluster, by means of a level set method. The second stage is targeted to shape refinement of selected individual MCs, by means of an active contour model. Both methods are applied in the framework of a rich scale-space representation, provided by the wavelet transform at integer scales. Segmentation reliability of the proposed method in terms of inter and intraobserver agreements was evaluated in a case sample of 80 MC clusters originating from the digital database for screening mammography, corresponding to 4 morphology types (punctate: 22, fine linear branching: 16, pleomorphic: 18, and amorphous: 24) of MC clusters, assessing radiologists’ segmentations quantitatively by two distance metrics (Hausdorff distance—HDIST{sub cluster}, average of minimum distance—AMINDIST{sub cluster}) and the area overlap measure (AOM{sub cluster}). The effect of the proposed segmentation method on MC cluster characterization accuracy was evaluated in a case sample of 162 pleomorphic MC clusters (72 malignant and 90 benign). Ten MC cluster features, targeted to capture morphologic properties of individual MCs in a cluster (area, major length, perimeter, compactness, and spread), were extracted and a correlation-based feature selection method yielded a feature subset to feed in a support vector machine classifier. Classification performance of the MC cluster features was estimated by means of the area under receiver operating characteristic curve (Az ± Standard Error) utilizing tenfold cross-validation methodology. A previously developed B-spline active rays segmentation method was also considered for comparison purposes. Results: Interobserver and intraobserver segmentation agreements (median and [25%, 75%] quartile range) were substantial with respect to the distance metrics HDIST{sub cluster} (2.3 [1.8, 2.9] and 2.5 [2.1, 3.2] pixels) and AMINDIST{sub cluster} (0.8 [0.6, 1.0] and 1.0 [0.8, 1.2] pixels), while moderate with respect to AOM{sub cluster} (0.64 [0.55, 0.71] and 0.59 [0.52, 0.66]). The proposed segmentation method outperformed (0.80 ± 0.04) statistically significantly (Mann-Whitney U-test, p < 0.05) the B-spline active rays segmentation method (0.69 ± 0.04), suggesting the significance of the proposed semiautomated method. Conclusions: Results indicate a reliable semiautomated segmentation method for MC clusters offered by deformable models, which could be utilized in MC cluster quantitative image analysis.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1975

Observations of the structure and evolution of solar flares with a soft X-ray telescope

One hundred thirty-two soft X-ray flare events have been observed with the S-056 X-ray telescope aboard Skylab. The observations are summarized, and a detailed discussion of the X-ray flare structures is presented. The data indicated that soft X-rays emitted by a flare come primarily from an intense well-defined core surrounded by a region of fainter more diffuse emission. Loop structures are found to constitute a fundamental characteristic of flare cores, and arcades of loops are found to play a more important role in flare phenomena than previously thought. Size distributions of these core features are presented, and a classification scheme describing the brightest flare X-ray features is proposed. Analysis of flare evolution indicates evidence for preliminary heating and energy release prior to the main phase of the flare. Core features are found to be remarkably stable and to retain their shape throughout a flare. Most changes in the overall configuration seem to be the result of the appearance, disappearance, or change in brightness of individual features, rather than the restructuring or reorientation of these features.

Vorpahl, J. A.↗
DOE OSTI2016

Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8–1.0 were significantly different between the system without BACs removal and the system with BACs removal, 0.129 ± 0.009 versus 0.144 ± 0.008 (p<0.05), respectively. Additionally, the sensitivity at one false positive per 50 cases and one false positive per 25 cases increased as well, 37% versus 51% (p<0.05) and 58% versus 67% (p<0.05) sensitivity, respectively. Additionally, the CADe system with BACs removal reduces the number of false positives per case by 29% on average. The same sensitivity at one false positive per 50 cases in the CADe system without BACs removal can be achieved at one false positive per 80 cases in the CADe system with BACs removal. Conclusions: By using dedicated algorithms to detect and remove breast arterial calcifications, the performance of CADe systems can be improved, in particular, at false positive rates representative for operating points used in screening.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Bicep2. III. INSTRUMENTAL SYSTEMATICS

In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call “deprojection,” for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3–6) × 10{sup −3}.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Passive spiral galaxies deeply captured by Subaru Hyper Suprime-Cam

Abstract This paper presents a thousand passive spiral galaxy samples at z = 0.01–0.3 based on a combined analysis of the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP PDR3) and the GALEX–SDSS–WISE Legacy Catalog (GSWLC-2). Among 54871 gri galaxy cutouts taken from the HSC-SSP PDR3 over 1072 deg2, we conducted a search with deep-learning morphological classification for candidates of passive spirals below the star-forming main sequence derived by ultraviolet to mid-infrared spectral energy distribution fitting in the GSWLC-2. We then classified the candidates into 1100 passive spirals and 1141 secondary samples based on visual inspections. Most of the latter cases are considered to be passive ringed S0 or pseudo-ringed galaxies. The remaining secondary samples have ambiguous morphologies, including two peculiar objects with diamond-shaped stellar wings. The selected passive spirals have a similar distribution to the general quiescent galaxies on the EWHδ–Dn4000 diagram and concentration indices. Moreover, we detected an enhanced passive fraction of spiral galaxies in X-ray clusters. Passive spirals in galaxy clusters are preferentially located in the midterm or late infall phase on the phase–space diagram, supporting the ram pressure scenario, which has been widely advocated in previous studies. The source catalog and gri-composite images are available on the HSC-SSP PDR3 website 〈https://hsc.mtk.nao.ac.jp/ssp/data-release/〉. Future updates, including integration with a citizen science project dedicated to the HSC data, will achieve more effective and comprehensive classifications.

Shimakawa, Rhythm (ORCID:0000000344422750)↗