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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Increasing Crew Autonomy for Long Duration Exploration Missions: Self-Scheduling

Over the last three years, we have been investigating the operational concept of crew self-scheduling as a method of increasing crew autonomy for future exploration missions. Through Playbook, a planning and scheduling software tool, we have incrementally increased the ability for Earth analog mission crews to modify their schedules. Playbook allows the crew to add new activities from scratch, add new activities or groups of activities through a Task List, and reschedule or reassign flexible activities. The crew is also able to identify if plan modifications create violations, i.e., plan constraints not being met. This paper summarizes our observations with qualitative evidence from four NASA Extreme Environment Mission Operations (NEEMO) analog missions that supported self-scheduling as a feasible operational concept.

crew autonomy↗
NASA NTRS2017

Increasing Crew Autonomy for Long Duration Exploration Missions: Self-Scheduling

Over the last three years, we have been investigating the operational concept of crew self-scheduling as a method of increasing crew autonomy for future exploration missions. Through Playbook, a planning and scheduling software tool, we have incrementally increased the ability for Earth analog mission crews to modify their schedules. Playbook allows the crew to add new activities from scratch, add new activities or groups of activities through a Task List, and reschedule or reassign flexible activities. The crew is also able to identify if plan modifications create violations, i.e., plan constraints not being met. This paper summarizes our observations with qualitative evidence from four NASA Extreme Environment Mission Operations (NEEMO) analog missions that supported self-scheduling as a feasible operational concept.

planning and scheduling↗
DOE OSTI2025

Hierarchically ordered porous transition metal compounds from one-pot type 3D printing approaches

Solution-based soft matter self-assembly (SA) promises unique material structures and properties from approaches including additive manufacturing/three-dimensional (3D) printing. The 3D printing of periodically ordered porous functional inorganic materials through SA unfolding during printing remains a major challenge, however, due to the often vastly different ordering kinetics of separate processes at different length scales. Here, we report a “one-pot” direct ink writing process to produce hierarchically porous transition metal nitrides and precursor oxides from block copolymer (BCP) SA. Heat treatment protocols identified in various environments enable mesostructure retention in the final crystalline materials with periodic lattices on three distinct length scales. Moreover, embedded printing enables the first BCP directed mesoporous non-self-supporting helical oxides and nitrides. Resulting nitrides are superconducting, with record nanoconfinement-induced upper critical fields correlated with BCP molar mass and record surface areas for compound superconductors. Results suggest scalable porous functional inorganic material formation approaches for applications including catalysis, sensing, and microelectronics.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Non-Gaussianity from explicit U(1)-breaking interactions

We investigate primordial non-Gaussianity (NG) arising from the explicit U(1) symmetry-breaking interactions during inflation involving a nearly massless axial component of a complex scalar field P. We analyze the induced NG parameter f NL under scenarios where the axial field functions as either a curvaton or cold dark matter (CDM). In the curvaton framework, there is a conventional contribution to the local NG of f NL ≃ -O(1). Additional positive local NG can result from either the self-interactions of axial field fluctuations, their interactions with a light radial partner, or kinetic mixing with the inflaton via U(1) symmetry-breaking terms. We identify parameter regions where the interactions lead to cancellations, suppressing the overall local NG to |f loc NL | ≲ O(0.1). In the CDM scenario, these interactions enhance the NG in the isocurvature fluctuations. Moreover, interactions between the axial field and another light scalar, such as a curvaton, can generate O(1) curvature NG signals and significant mixed curvature-isocurvature NGs that are within the reach of future experiments with σ(f loc NL ) ∼ 1. We also explore the role of a heavy radial field in generating oscillating correlation signals, noting that such signals can dominate the shape of the mixed adiabatic-isocurvature bispectrum. In certain cases, an oscillatory isocurvature bispectrum signal may be observable in the future, aiding in distinguishing between certain types of the U(1)-breaking self-interactions of the axial field.

axions↗
DOE OSTI2023

Seasonal and Geographical Variations in Fundamental Weather Patterns during Extreme Precipitation as Identified from Omega Equation Forcing

Abstract We investigate the large-scale weather patterns during extreme precipitation (PEx) events over the conterminous United States (CONUS) by applying a version of the quasigeostrophic (QG) omega equation. This work aims to develop a climatology of the weather patterns most related to PEx events during current climate. Extreme events are examined for each of seven regions defined by consistent annual cycles of precipitation and spanning the CONUS. For the CONUS we train several self-organizing maps (SOM) on a pressure–time series of vertical velocity from each of the advective forcing terms in the QG omega equation for each extreme event. The unsupervised learning of the SOM allows us to identify the most descriptive set of nine patterns in vertical velocity associated with precipitation extremes. This method finds multiple frontal- and cyclone-driven patterns while grouping primarily convective events into one pattern. Frontal events include a synoptic pattern consistent with West Coast atmospheric river events as well as pattern groups linked to developing and to mature (“occluded”) frontal cyclones. The primary patterns found during PEx events vary seasonally and geographically. Frontal cyclone patterns are most common during PEx events during summer in the part of the Great Plains and during winter for the Northeast, Southeast, Pacific Northwest, and Southwest. Convection is the most common pattern during summer in all regions. Except in the Southeast, the annual cycles of monthly number of PEx events and average precipitation match well, partially validating our choice of regions to aggregate PEx events.

Meteorology & Atmospheric Sciences↗
NASA NTRS2006

Identifying Basic Factors for Communal Prosperity - Space Technologies are Bridging this Gap

There are many aspects, which are important for maintaining environmentally clean and safe conditions for a healthy and economically self-sufficient community. This problem was somewhat of a lesser concern in earlier days because many communities were small, isolated and solely dependent upon their owners or landlords. Due to an astronomical growth in human population within the last century, extensive use of combustion technologies, and changing environmental conditions has resulted in scarcity of natural resources. In reality, the societal sustainability issues are becoming much more acute and complex. Therefore, the researchers and social scientists are joining forces to address these topics and find solutions to many contentious areas such as public health and diseases, water resources, agriculture production, survivability during and after the natural disasters, energy needs and many others. Forthrightly speaking, there is no canned solution or a methodology to go about solving these issues since the magnitude and complexity of these issues are multi-dimensional and are further inter-locked with other areas. A common sense tells us that we need data, resources and technologies to begin addressing these problems. This is where space observations have provided us with tremendous information and opportunities, which are of great assets to the science, economist, and social scientists. This paper specifically addresses what are critical areas for a successful societal sustainability and growth; and how can we take advantage of multiple sensors and models already in existence. Increasing our knowledge of the home planet, via amplified set of observations, is certainly a right step in a right direction. Furthermore, this is a pre-requisite in understanding multiple hazard phenomena's. This paper further examines various space sensors and observing architectures that can be useful specifically in addressing some of these complex issues. The ultimate goal is to serve the society by providing such valuable information so the decision makers can take full advantage in making timely societal decisions.

Habib, Shahid↗
NASA NTRS1990

Finite-difference solutions of three-dimensional rotor blade-vortex interactions

A numerical finite-difference procedure has been developed for the modeling of rotor self-generated blade-vortex interactions (BVI). The interaction velocity field is obtained through a nonlinear superposition of the rotor and the vortex wake flow fields. Vortex effects are simulated using the velocity 'transpiration' approach. Potential blade-vortex encounters are identified and tracked in time at equal increments of rotor azimuth using the lifting-line helicopter/rotor trim code CAMRAD. Accuracy of the numerical results were found to rely heavily on the CAMRAD-predicted vortex orientation, vortex strength, and user specified vortex core radius. Results for the subcritical self-generated BVI for the model OLS rotor are presented. They show good agreement with the experimental wind tunnel data.

Hassan, A. A.↗
DOE OSTI2021

Avalanche transport of energetic-ions in magnetic confinement plasmas: nonlinear multiple wave-number simulation

Large burst activity, identified as toroidal Alfvén eigenmode (TAE) avalanche, occurs frequently in neutral-beam heated plasmas in National Spherical Torus Experiment (NSTX). Based on the typical experimental observation of TAE avalanche on NSTX, a self-consistent nonlinear multiple wave-number (k ∥ ≃ n/R, where n toroidal mode-number and R major radius) simulation associated with TAE avalanches is performed using the experimental parameters and profiles before the occurrence of TAE avalanche as the M3D-K input. The wave–wave nonlinear coupling among different modes and the resonant interaction between different modes and energetic-ions during TAE avalanches are identified in the nonlinear multiple wave-number simulations. The resonance overlap during the TAE avalanche is clearly observed in the simulation. It is found that the effective wave–wave coupling and a sufficiently strong drive are two important ingredients for the onset of TAE avalanches. TAE avalanche is considered to be a strongly nonlinear process and it is always accompanied by the simultaneous rapid frequency-chirping and large amplitude bursting of multiple modes and significant energetic-ion losses. The experimental phenomenon is observed on NSTX and is qualitatively reproduced by the simulation results in this work. These findings indicate that the onset of avalanche is triggered by nonlinearity of the system, and are also conducive to understanding the underlying mechanism of avalanche transport of energetic particles in the future burning plasmas, such as International Thermonuclear Experiment Reactor.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1999

Towards Self-Replicating Chemical Systems Based on Cytidylic and Guanylic Acids

This project was aimed towards a better understanding of template-directed reactions and, based on this, towards the development of efficient non-enzymatic RNA replicating systems. These systems could serve as models for the prebiotic synthesis of an RNA world. The major objectives of this project are: (a) To elucidate the mechanistic aspects of template-directed (TD) chemistry and (b) to identify active boundary regions, or conditions, environmental and other, that favor "organized chemistry" and stereo-selective polymerization of nucleotides. "Organized chemistry" may lead to enhanced polymerization efficiency which in turn is expected to facilitate the road towards a self-replicating chemical system based on all four nucleic acid bases.

Kanavarioti, Anastassia↗
NASA NTRS1991

Incoherent vs. coherent behavior in the normal state of copper oxide superconductors

The self-consistent quantum fluctuations around the mean-field Hartree-Fock state of the Hubbard model provide a very good description of the ground state and low temperature properties of a 2-D itinerant antiferromagnet. Very good agreement with numerical calculations and experimental data is obtained by including the one- and two-loop spin wave corrections to various physical quantities. In particular, the destruction of the long-range order above the Neel temperature can be understood as a spontaneous generation of a length-scale epsilon(T), which should be identified as the spin correlation length. For finite doping, the question of the Hartree-Fock starting point becomes a more complex one since an extra hole tends to self-trap in antiferromagnetic background. Such quantum defects in an underlying antiferromagnetic state can be spin-bags or vortex-like structures and tend to suppress the long-range order. If motion of the holes occurs on a time-scale shorter than the one associated with the motion of these quantum defects of a spin background, one obtains several important empirical features of the normal state of CuO superconductors like linear T-dependence of resistivity, the cusp in the tunneling density of states, etc. As opposed to a familiar Fermi-liquid behavior, the phenomenology of the above system is dominated by a large incoherent piece of a single hole propagator, resulting in many unusual normal state properties.

Tesanovic, Zlatko↗
DOE OSTI2021

Quantitative imaging and automated fuel pin identification for passive gamma emission tomography

Compliance of member States to the Treaty on the Non-Proliferation of Nuclear Weapons is monitored through nuclear safeguards. The Passive Gamma Emission Tomography (PGET) system is a novel instrument developed within the framework of the International Atomic Energy Agency (IAEA) project JNT 1510, which included the European Commission, Finland, Hungary and Sweden. The PGET is used for the verification of spent nuclear fuel stored in water pools. Advanced image reconstruction techniques are crucial for obtaining high-quality cross-sectional images of the spent-fuel bundle to allow inspectors of the IAEA to monitor nuclear material and promptly identify its diversion. In this work, we have developed a software suite to accurately reconstruct the spent-fuel cross sectional image, automatically identify present fuel rods, and estimate their activity. Unique image reconstruction challenges are posed by the measurement of spent fuel, due to its high activity and the self-attenuation. While the former is mitigated by detector physical collimation, we implemented a linear forward model to model the detector responses to the fuel rods inside the PGET, to account for the latter. The image reconstruction is performed by solving a regularized linear inverse problem using the fast-iterative shrinkage-thresholding algorithm. We have also implemented the traditional filtered back projection (FBP) method based on the inverse Radon transform for comparison and applied both methods to reconstruct images of simulated mockup fuel assemblies. Higher image resolution and fewer reconstruction artifacts were obtained with the inverse-problem approach, with the mean-square-error reduced by 50%, and the structural-similarity improved by 200%. We then used a convolutional neural network (CNN) to automatically identify the bundle type and extract the pin locations from the images; the estimated activity levels finally being compared with the ground truth. The proposed computational methods accurately estimated the activity levels of the present pins, with an associated uncertainty of approximately 5%.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1976

Predominance of two-armed spirals

A physical process accounts for the origin and widespread occurrence of two-armed spiral patterns with a high degree of symmetry extending from the nucleus to the outermost part of a galaxy. Self-gravitating systems, starting from a wide variety of initial conditions, settle down into twofold symmetries through a sequence of forms that were identified in numerical experiments. Twofold symmetries rarely develop directly. Instead, the systems pass through a sequence of more complicated shapes. The computer experiments and the sequence leading to twofold symmetries are described. At the end of this process, a two-armed spiral density wave with a 'grand design' has been set up in the galaxy, and the stage has been set for some mechanism, such as that of Lin and Shu (1971), to take over to assure a long lifetime for the pattern.

Miller, R. H.↗
NASA NTRS1984

The complex coronal transient of 1980 March 23

The time evolution of the coronal transient of 1980 March 23 is described, which contains as substructures a dark loop and an area of depletion similar to those seen by Fisher, Garcia, and Seagraves. The mass ejection pushes aside preexisting streamers, giving rise to the characteristic dark area with bright flanks seen in difference images of depletion transients. Time-height plots for five identifiable features in the transient event are shown; these substructures have velocities interrelated in a way approximately consistent with the hypothesis of self-similar MHD propagation. This implies that the event as a whole may be a self-similar dynamical system, and that the substructure loops are not independent units. A scenario for the event is presented, in which it is considered as a large, complex system which evolves dynamically as a whole.

Illing, R. M. E.↗
NASA NTRSDate not supplied

Acoustic and Performance Characteristics of an Ideally Twisted Rotor in Hover

A series of experiments were conducted in an anechoic chamber to investigate the noise and performance of an ideally twisted rotor design, leading to validation of a low-fidelity aerodynamic performance and acoustic modeling tool chain. An “ideally twisted” rotor was designed in order to simplify the theoretical rotor inflow for a target thrust condition in hover. This rotor design was then fabricated using state-of-the-art rapid prototyping and tested in an anechoic chamber. Aerodynamic load and acoustic data were acquired across a range of rotation rates and rotor collective settings in order to both identify noise trends and ascertain the accuracy of the low-fidelity modeling codes. Emphasis was placed on modeling of the broadband self-noise generated by the rotor system due to the fact that it was found to be a prominent contributor to the overall rotor system noise.

Nicole A Pettingill↗
NASA NTRS1997

Towards Self-Replicating Chemical Systems Based on Cytidylic and Guanylic Acids

This project is aimed towards a better understanding of template-directed reactions and, based on this, towards the development of efficient non-enzymatic RNA replicating systems. These systems could serve as models for the prebiotic synthesis of an RNA world. The major objectives of this project were: (a) To elucidate the mechanistic aspects of template-directed (TD) chemistry, (b) to identify the conditions, environmental and other, that favor "organized chemistry" and stereo selective polymerization of nucleotides and (c) to search and, hopefully, find catalysts that will improve the efficiency of these reactions. Enhanced efficiency is expected to facilitate the road towards a self-replicating chemical system based on all four nucleic acid bases. During the first nine months of the granting period from January 1997 to October 1997, we have made substantial progress towards the first two objectives. During this period our activities were directed towards (1) synthesizing activated nucleotides to be used as substrates, (2) using these substrates in order to determine the effect of the leaving group (imidazole (Im), 2-methylimidazole (2-MeIm), and 2,4-dimethylimidazole (2,4-diMeIm)) in the product distribution, (3) developing techniques for analysis of mixtures by LC/MS, (4) creating a protocol in order to obtain kinetic parameters of the dimerization reaction and (5) analyzing kinetic data obtained with the poly(C)/2-MeImpG system. With the exception of item (5), the experimental work for the projects (1) - (4) is still in progress. A list of publications and manuscripts resulted from this research is enclosed.

Kanavarioti, Anastassia↗
DOE OSTI2020

Covalent Linkage and Macrocylization Preserve and Enhance Synergistic Interactions in Catalytic Amyloids

The self-assembly of short peptides into catalytic amyloid-like nanomaterials has proven to be a powerful tool in both understanding the evolution of early proteins and identifying new catalysts for practically useful chemical reactions. Here we demonstrate that both parallel and antiparallel arrangements of beta-sheets can accommodate metal ions in catalytically productive coordination environments. Moreover, synergistic relationships, identified in catalytic amyloid mixtures, can be captured in macrocyclic and sheet-loop-sheet species, that offer faster rates of assembly and provide more complex asymmetric arrangements of functional groups, thus paving the way for future designs of amyloid-like catalytic proteins. Finally, our findings show how initial catalytic activity in amyloid assemblies can be propagated and improved in more-complex molecules, providing another link in a complex evolutionary chain between short, potentially abiotically produced peptides and modern-day enzymes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

A general framework for removing point-spread function additive systematics in cosmological weak lensing analysis

ABSTRACT Cosmological weak lensing measurements rely on a precise measurement of the shear two-point correlation function (2PCF) along with a deep understanding of systematics that affect it. In this work, we demonstrate a general framework for detecting and modelling the impact of PSF systematics on the cosmic shear 2PCF and mitigating its impact on cosmological analysis. Our framework can detect PSF leakage and modelling error from all spin-2 quantities contributed by the PSF second and higher moments, rather than just the second moments, using the cross-correlations between galaxy shapes and PSF moments. We interpret null tests using the HSC Year 3 (Y3) catalogs with this formalism and find that leakage from the spin-2 combination of PSF fourth moments is the leading contributor to additive shear systematics, with total contamination that is an order-of-magnitude higher than that contributed by PSF second moments alone. We conducted a mock cosmic shear analysis for HSC Y3 and find that, if uncorrected, PSF systematics can bias the cosmological parameters Ωm and S8 by ∼0.3σ. The traditional second moment-based model can only correct for a 0.1σ bias, leaving the contamination largely uncorrected. We conclude it is necessary to model both PSF second and fourth moment contaminations for HSC Y3 cosmic shear analysis. We also reanalyse the HSC Y1 cosmic shear analysis with our updated systematics model and identify a 0.07σ bias on Ωm when using the more restricted second moment model from the original analysis. We demonstrate how to self-consistently use the method in both real space and Fourier space, assess shear systematics in tomographic bins, and test for PSF model overfitting.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

INTERSECT Architecture Specification: Use Case Design Patterns (V.0.5)

Oak Ridge National Laboratory (ORNL)’s Self-driven Experiments for Science / Interconnected Science Ecosystem (INTERSECT) architecture project, titled “An Open Federated Architecture for the Laboratory of the Future”, creates an open federated hardware/software architecture for the laboratory of the future using a novel system of systems (SoS) and microservice architecture approach, connecting scientific instruments, robot-controlled laboratories and edge/center computing/data resources to enable autonomous experiments, “self-driving” laboratories, smart manufacturing, and artificial intelligence (AI)-driven design, discovery and evaluation. The project describes science use cases as design patterns that identify and abstract the involved hardware/software components and their interactions in terms of control, work and data flow. It creates a SoS architecture of the federated hardware/software ecosystem that clarifies terms, architectural elements, the interactions between them and compliance. It further designs a federated microservice architecture, mapping science use case design patterns to the SoS architecture with loosely coupled microservices, standardized interfaces and multi programming language support. The primary deliverable of this project is an INTERSECT Open Architecture Specification, containing the science use case design pattern catalog, the federated SoS architecture specification and the federated microservice architecture specification. This document represents the science use case design pattern catalog of the INTERSECT Open Architecture Specification.

42 ENGINEERING↗