Results for “Class generation” — Page 17

NASA NTRS1991

UV-optical from space

The following subject areas are covered: (1) the science program (star formation and origins of planetary systems; structure and evolution of the interstellar medium; stellar population; the galactic and extragalactic distance scale; nature of galaxy nuclei, AGNs, and QSOs; formation and evolution of galaxies at high redshifts; and cosmology); (2) implementation of the science program; (3) the observatory-class missions (HST; LST - the 6m successor to HST; and next-generation 16m telescope); (4) moderate and small missions (Delta-class Explorers; imaging astrometric interferometer; small Explorers; optics development and demonstrations; and supporting ground-based capabilities); (5) prerequisites - the current science program (Lyman-FUSE; HTS optimization; the near-term science program; data analysis, modeling, and theory funding; and archives); (6) technologies for the next century; and (7) lunar-based telescopes and instruments.

Illingworth, Garth↗

NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗

NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗

NASA NTRS2020

A Human-in-theLoop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗

DOE OSTI2020

A Step Towards Machine Learning-based Coherent Generator Grouping for Emergency Control Applications in Modern Power Grid

A dynamic neural network (NN) based multi-class classifier is proposed for improving online prediction of coherent generator groups (CGGs), following the occurrences of various contingencies in the power grid. This is motivated by the increasing availability of the measurements from phasor measurement units (PMUs) and the number of grouping schemes is limited. The proposed method consists of three steps. First, by performing offline simulations, a library of system dynamic responses characterized by post-contingency rotor angles and speeds of individual generators is obtained. To generate sufficient data, up to N-2 contingencies and the uncertain parameters associated with the power grid including type and location of disturbance and fault clearing times are modeled. Secondly, the training data-set is produced by generating labels for individual contingencies using a hierarchical clustering method based on rotor angle and speed data. Lastly, the dynamic NN models are trained for online applications such as emergency controls and controlled islanding. The proposed method is tested on the standard 16-generator 68-bus system to demonstrate its performance. Furthermore, the impact of the sample data lengths on the CGG numbers is evaluated. It is interesting to observe that the time domain stability behaviors can be determined by examining the changes in the CGG numbers.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2020

Will Solar Panels Help When the Power Goes Out? Planning for PV Resilience

PV systems, like all energy systems, must chart a difficult course in order to improve resilience. They need to simultaneously withstand extreme conditions that cause grid power disruptions, be configured in a way that allows electricity to be delivered to meet the PV user's needs, and overcome disruptions arising from solar resource intermittency. Certain considerations reveal themselves as key to a PV system's resilience benefits. Choice of hardware is critical, as is site selection for the PV array. Voluminous evidence in a hurricane context demonstrates that durable hardware, properly maintained and sited, leads to PV systems surviving extreme weather with their functionality intact. Structurally weak or poorly maintained PV equipment, on the other hand, has demonstrated failures during extreme weather events. PV system stakeholders should ensure that best practices are followed for hardware procurement and siting. It is also important to understand that PV systems are not one-size-fits-all. While incorporating islanding capabilities and energy storage into the system's electrical topology will typically enhance resilience, the user's needs will determine the optimally resilient conformation of any given system. These factors - appropriate hardware, siting, maintenance, and system design - are the primary drivers of PV resilience. PV systems possess high potential for resilient energy generation due to their distributed, abundant, and free fuel supply, but the technology itself does not inherently lead to resilient outcomes. Realizing PV's potential for resilience requires consideration of these determinative factors.

14 SOLAR ENERGY↗

NASA NTRS2000

Mapping Environmental Contaminants at Ray Mine, AZ

Airborne Visible and InfraRed Imaging Spectrometer (AVIRIS) data was collected over Ray Mine as part of a demonstration project for the Environmental Protection Agency (EPA) through the Advanced Measurement Initiative (AMI). The overall goal of AMI is to accelerate adoption and application of advanced measurement technologies for cost effective environmental monitoring. The site was selected to demonstrate the benefit to EPA in using advanced remote sensing technologies for the detection of environmental contaminants due to the mineral extraction industry. The role of the Jet Propulsion Laboratory in this pilot study is to provide data as well as performing calibration, data analysis, and validation of the AVIRIS results. EPA is also interested in developing protocols that use commercial software to perform such work on other high priority EPA sites. Reflectance retrieval was performed using outputs generated by the MODTRAN radiative transfer model and field spectra collected for the purpose of calibration. We are presenting advanced applications of the ENVI software package using n-Dimensional Partial Unmixing to identify image-derived endmembers that best match target materials reference spectra from multiple spectral libraries. Upon identification of the image endmembers the Mixture Tuned Match Filter algorithm was applied to map the endmembers within each scene. Using this technique it was possible to map four different mineral classes that are associated with mine generated acid waste.

McCubbin, Ian↗

DOE OSTI2024

Class Ib Ribonucleotide Reductases: Activation of a Peroxido-Mn II Mn III to Generate a Reactive Oxo-Mn III Mn IV Oxidant

Not Available

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Identification of Genome-Wide Mutations in Ciprofloxacin-Resistant F. tularensis LVS Using Whole Genome Tiling Arrays and Next Generation Sequencing

Francisella tularensis is classified as a Class A bioterrorism agent by the U.S. government due to its high virulence and the ease with which it can be spread as an aerosol. It is a facultative intracellular pathogen and the causative agent of tularemia. Ciprofloxacin (Cipro) is a broad spectrum antibiotic effective against Gram-positive and Gram-negative bacteria. Increased Cipro resistance in pathogenic microbes is of serious concern when considering options for medical treatment of bacterial infections. Identification of genes and loci that are associated with Ciprofloxacin resistance will help advance the understanding of resistance mechanisms and may, in the future, provide better treatment options for patients. It may also provide information for development of assays that can rapidly identify Cipro-resistant isolates of this pathogen. In this study, we then selected a large number of F. tularensis live vaccine strain (LVS) isolates that survived in progressively higher Ciprofloxacin concentrations, screened the isolates using a whole genome F. tularensis LVS tiling microarray and Illumina sequencing, and identified both known and novel mutations associated with resistance. For genes containing mutations encode DNA gyrase subunit A, a hypothetical protein, an asparagine synthase, a sugar transamine/perosamine synthetase and others. Finally, structural modeling performed on these proteins provides insights into the potential function of these proteins and how they might contribute to Cipro resistance mechanisms.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2015

Centrality dependence of particle production in p - Pb collisions at s NN = 5.02 TeV

We report measurements of the primary charged-particle pseudorapidity density and transverse momentum distributions in p-Pb collisions at √sNN=5.02TeV and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined by using different event-activity estimators, i.e., charged-particle multiplicities measured in three different pseudorapidity regions as well as the energy measured at beam rapidity (zero degree). The procedures to determine the centrality, quantified by the number of participants (N part ) or the number of nucleon-nucleon binary collisions (N coll ) are described. We show that, in contrast to Pb-Pb collisions, in p-Pb collisions large multiplicity fluctuations together with the small range of participants available generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an alternative event-centrality estimator. Based on zero-degree energy-centrality classes, the N part dependence of particle production is studied. Under the assumption that the multiplicity measured in the Pb-going rapidity region scales with the number of Pb participants, an approximate independence of the multiplicity per participating nucleon measured at mid-rapidity of the number of participating nucleons is observed. Furthermore, at high-p T the p-Pb spectra are found to be consistent with the pp spectra scaled by N coll for all centrality classes. Our results represent valuable input for the study of the event-activity dependence of hard probes in p-Pb collisions and, hence, help to establish baselines for the interpretation of the Pb-Pb data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1981

Evaluation of SLAR and thematic mapper MSS data for forest cover mapping using computer-aided analysis techniques

A set of training statistics for the 30 meter resolution simulated thematic mapper MSS data was generated based on land use/land cover classes. In addition to this supervised data set, a nonsupervised multicluster block of training statistics is being defined in order to compare the classification results and evaluate the effect of the different training selection methods on classification performance. Two test data sets, defined using a stratified sampling procedure incorporating a grid system with dimensions of 50 lines by 50 columns, and another set based on an analyst supervised set of test fields were used to evaluate the classifications of the TMS data. The supervised training data set generated training statistics, and a per point Gaussian maximum likelihood classification of the 1979 TMS data was obtained. The August 1980 MSS data was radiometrically adjusted. The SAR data was redigitized and the SAR imagery was qualitatively analyzed.

Hoffer, R. M.↗

NASA NTRS1998

Three-Dimensional Measurements of Fuel Distribution in High-Pressure, High- Temperature, Next-Generation Aviation Gas Turbine Combustors

In our world-class, optically accessible combustion facility at the NASA Lewis Research Center, we have developed the unique capability of making three-dimensional fuel distribution measurements of aviation gas turbine fuel injectors at actual operating conditions. These measurements are made in situ at the actual operating temperatures and pressures using the JP-grade fuels of candidate next-generation advanced aircraft engines for the High Speed Research (HSR) and Advanced Subsonics Technology (AST) programs. The inlet temperature and pressure ranges used thus far are 300 to 1100 F and 80 to 250 psia. With these data, we can obtain the injector spray angles, the fuel mass distributions of liquid and vapor, the degree of fuel vaporization, and the degree to which fuel has been consumed. The data have been used to diagnose the performance of injectors designed both in-house and by major U.S. engine manufacturers and to design new fuel injectors with overall engine performance goals of increased efficiency and reduced environmental impact. Mie scattering is used to visualize the liquid fuel, and laser-induced fluorescence is used to visualize both liquid and fuel vapor.

Hicks, Yolanda R.↗

NASA NTRS2000

Back to the Future: Consistency-Based Trajectory Tracking

Given a model of a physical process and a sequence of commands and observations received over time, the task of an autonomous controller is to determine the likely states of the process and the actions required to move the process to a desired configuration. We introduce a representation and algorithms for incrementally generating approximate belief states for a restricted but relevant class of partially observable Markov decision processes with very large state spaces. The algorithm presented incrementally generates, rather than revises, an approximate belief state at any point by abstracting and summarizing segments of the likely trajectories of the process. This enables applications to efficiently maintain a partial belief state when it remains consistent with observations and revisit past assumptions about the process' evolution when the belief state is ruled out. The system presented has been implemented and results on examples from the domain of spacecraft control are presented.

Kurien, James↗

DOE OSTI2015

Review of electric discharge microplasmas generated in highly fluctuating fluids: Characteristics and application to nanomaterials synthesis

Plasma-based fabrication of novel nanomaterials and nanostructures is indispensible for the development of next-generation electronic devices and for green energy applications. In particular, controlling the interactions between plasmas and materials interfaces, and the plasma fluctuations, is crucial for further development of plasma-based processes and bottom-up growth of nanomaterials. Electric discharge microplasmas generated in supercritical fluids represent a special class of high-pressure plasmas, where fluctuations on the molecular scale influence the discharge properties and the possible bottom-up growth of nanomaterials. This review discusses an anomaly observed for direct current microplasmas generated near the critical point, a local decrease in the breakdown voltage. This anomalous behavior is suggested to be caused by the concomitant decrease of the ionization potential due to the formation of clusters near the critical point, and the formation of extended electron mean free paths caused by the high-density fluctuation near the critical point. It is also shown that in the case of dielectric barrier microdischarges generated close to the critical point, the high-density fluctuation of the supercritical fluid persists. The final part of the review discusses the application of discharges generated in supercritical fluids to synthesis of nanomaterials, in particular, molecular diamond—so-called diamondoids—by microplasmas generated inside conventional batch-type and continuous flow microreactors.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2015

Stability of fissile solution systems - 14614

A Dynamic System Simulation (DSS) has been developed for aqueous homogenous reactors (AHR) and subcritical accelerator-driven system employing fissile solution fuel. These models are comprised of coupled non-linear differential equations describing the neutronics, thermal hydraulic and radiolytic gas behavior in the time domain. Models of specific historic AHR, SUPO (Super Power), KEWB (Kinetics Experiment Water Boiler), and SILENE exhibit close agreement with experimental data in all operating modes including steady-state, ramp and step reactivity insertions. The set of non-linear equations have been utilized to generate a generic transfer function for this class of systems. Output from specific DSS models operating at steady-state is then utilized as input parameters into a transfer function specific to each. Traditional Bode amplitude and phase, Nyquist and Nichols plots, are then generated to examine stability. Results for SUPO and a generic accelerator-driven system suggest these systems are unconditionally stable in the linear approximation. This treatment offers a method to examine the physics and time-based evolution of a critical excursion in a fissile solution system and provides a means to examine the severity of the consequence. This approach provides insight into the characteristics of such and even and sensitivity to materials involved and configuration of the physical system. (authors)

42 ENGINEERING↗

DOE OSTI2019

High harmonic generation in magnetically-doped topological insulators

As a new class of condensed matter, topological insulators challenge the traditional wisdom of condensed matter physics. Doping topological insulators with magnetic elements can realize the quantum anomalous Hall state, a two-dimensional bulk insulator with nonzero Chern number. High harmonic generation (HHG) has emerged as a very promising tool to probe electronic properties. However, its application to magnetically doped topological insulators has not been realized. Here, we predict that high harmonics from six quintuple layers of Bi2Se3(6QL-Bi2Se3) carry crucial information about its structure. HHG sensitively depends on crystal symmetry and laser polarization. While in the parent compound 6QL-Bi2Se3 all the harmonic orders are odd, once it is doped with a magnetic Cr atom, selective even and odd harmonics appear, depending on whether the laser field is in-plane or out-of-plane. With spin-orbit coupling, both even and odd harmonics appear. We find that these seemingly complicated harmonics have a simple origin: microscopic interplay between symmetry operations and laser polarization. Our finding demonstrates the unexplored power of HHG in topological insulators and will have a broad impact on future research.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2017

Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or not

For this article, we revisit models where a heavy chiral 4th generation doublet of fermions is embedded in a class of two Higgs doublets models (2HDM) with a discrete Z 2 symmetry, which couples the “heavy” scalar doublet only to the 4th generation fermions and the “light” one to the Standard Model (SM) fermions – the so-called 4G2HDM introduced by us several years ago. We study the constraints imposed on the 4G2HDM from direct searches of heavy fermions, from precision electroweak data (PEWD) and from the measured production and decay signals of the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even scalar h. We then show that the recently reported excess in the γγspectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the 4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing (sin α ≲ O (10 −3 )) between the two CP-even scalars h, Hand heavy 4th generation quark and lepton masses m t ' ,m b' ≲ 400 GeV and m ν' , m τ' ≳ 900 GeV, respectively. Whether or not the 750 GeV γγ resonance is confirmed, interesting phenomenology emerges in q' – Higgs systems (q' = t', b'), that can be searched for at the LHC. For example, the heavy scalar states of the model, S=H, A, H + , may have BR(S→$-\atop{q'}$q') ∼O(1), giving rise to observable $-\atop{q'}$q' signals on resonance, followed by the flavor changing q' decays t'→uh (u =u, c) and/or b'→dh (d =d, s, b). This leads to rather distinct signatures, with or without charged leptons, of the form $-\atop{q'}$q'→(nj +mb +ℓW) S (j and b being light and b-quark jets, respectively), with n +m +ℓ =6–8 and unique kinematic features. These high jet-multiplicity signals appear to be very challenging and may need new search strategies for detection of such heavy chiral quarks. It is also shown that the flavor structure of the 4G2HDM can easily accommodate the interesting recent indications of a percent-level branching ratio in the lepton-flavor-violating (LFV) decay h →τμ of the 125 GeV Higgs, if it is experimentally confirmed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

PFLOTRAN: Reactive Flow & Transport Code for Use on Laptops to Leadership-Class Supercomputers. In: Groundwater Reactive Transport Models

PFLOTRAN, a next-generation reactive flow and transport code for modeling subsurface processes, has been designed from the ground up to run efficiently on machines ranging from leadership-class supercomputers to laptops. Based on an object-oriented design, the code is easily extensible to incorporate additional processes. It can interface seamlessly with Fortran 9X, C and C++ codes. Domain decomposition parallelism is employed, with the PETSc parallel framework used to manage parallel solvers, data structures and communication. Features of the code include a modular input file, implementation of high-performance I/O using parallel HDF5, ability to perform multiple realization simulations with multiple processors per realization in a seamless manner, and multiple modes for multiphase flow and multicomponent geochemical transport. Chemical reactions currently implemented in the code include homogeneous aqueous complexing reactions and heterogeneous mineral precipitation/dissolution, ion exchange, surface complexation and a multirate kinetic sorption model. PFLOTRAN has demonstrated petascale performance using 217 processor cores on problems composed of over 2 billion degrees of freedom. The code is currently being applied to simulate uranium transport at the Hanford 300 Area and CO2 sequestration in deep geologic formations.

carbon sequestration↗