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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 433 records · Page 24

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NASA NTRS2015

Environment Modeling Using Runtime Values for JPF-Android

Software applications are developed to be executed in a specific environment. This environment includes external native libraries to add functionality to the application and drivers to fire the application execution. For testing and verification, the environment of an application is simplified abstracted using models or stubs. Empty stubs, returning default values, are simple to generate automatically, but they do not perform well when the application expects specific return values. Symbolic execution is used to find input parameters for drivers and return values for library stubs, but it struggles to detect the values of complex objects. In this work-in-progress paper, we explore an approach to generate drivers and stubs based on values collected during runtime instead of using default values. Entry-points and methods that need to be modeled are instrumented to log their parameters and return values. The instrumented applications are then executed using a driver and instrumented libraries. The values collected during runtime are used to generate driver and stub values on- the-fly that improve coverage during verification by enabling the execution of code that previously crashed or was missed. We are implementing this approach to improve the environment model of JPF-Android, our model checking and analysis tool for Android applications.

Verification↗

NASA NTRS2017

Aerial Vehicles to Detect Maximum Volume of Plume Material Associated with Habitable Areas in Extreme Environments

Current technologies of exploring habitable areas of icy moons are limited to flybys of space probes. This research project addresses long-term navigation of icy moons by developing a MATLAB adjustable trajectory based on the volume of plume material observed. Plumes expose materials from the sub-surface without accessing the subsurface. Aerial vehicles capable of scouting vapor plumes and detecting maximum plume material volumes, which are considered potentially habitable in inhospitable environments, would enable future deep-space missions to search for extraterrestrial organisms on the surface of icy moons. Although this platform is still a prototype, it demonstrates the potential aerial vehicles can have in improving the capabilities of long-term space navigation and enabling technology for detecting life in extreme environments. Additionally, this work is developing the capabilities that could be utilized as a platform for space biology research. For example, aerial vehicles that are sent to map extreme environments of icy moons or the planet Mars, could also carry small payloads with automated cell-biology experiments, designed to probe the biological response of low-gravity and high-radiation planetary environments, serving as a pathfinder for future human missions.

Vehicles Extreme Environment↗

NASA NTRSDate not supplied

The Generation and Application of Paylaod Thermal Environments for a Lunar Lander Mission

In today’s space industry many organizations develop payloads or other components that will fly on a vehicle or lander developed by a different organization. This creates a challenge for the payload developers of knowing the thermal environment, including effects from the spacecraft, of their instrument because the payload engineers will not have continuous access to an up-to-date thermal model of the spacecraft. To circumvent the vehicle developer having to provide a thermal model of the spacecraft to payload developers for detailed thermal analysis, the vehicle developer can provide environmental data to the payload engineers to apply to their payload model, instead. This data must include the boundary temperatures where the payload is mounted, sink temperatures, and both incident solar and infrared thermal flux. This paper will describe the method used to generate thermal environments for payloads on the Astrobotic Lunar Lander and how those environments were applied to an example payload, the Neutron Measurement at the Lunar Surface (NMLS) instrument. This work is unique because a standard method for generating and delivering payload environments does not exist. Benefits and drawbacks of using this method will also be discussed.

Thermal Environments↗

NASA NTRSDate not supplied

Electrical and Dielectric Characterizations of HTCC Electronic Packages for High Temperature Harsh Environment Applications

A prototype high temperature co-fired ceramic (HTCC) alumina packaging system composed of a 32-I/Os package and a compatible circuit board was previously developed and demonstrated for long term operation in 500 °C environments. The electrical / dielectric parasitic parameters of that chip level package were characterized and reported. This co-fired packaging system with platinum (Pt) conductor has successfully facilitated tests of silicon carbide (SiC) analog and digital integrated circuits (ICs) developed at NASA GRC at 500°C for up to 10,000 hours in ambient oven environment and 60 earth days in Venus surface environment with simulated temperature, pressure, and chemical constituents. Based on these previous results, this paper introduces new designs of Pt-HTCC packages with 16, 24, and 44 I/Os for packaging a new generation SiC ICs with 8, 24, 56, 62, and 72 I/Os to be tested in high temperature harsh environments. The package with 44 I/Os is specifically designed for the new SiC ICs with 56, 62, and 72-I/Os and electrical connection needs, the power pads of this package are consolidated, and an array of I/O pads distributed on separated vertical levels (inside the package) is used to control the overall package dimensions and mitigate the parasitic effects at high temperatures. This paper will present the detailed design of these chip-level packages and results of electrical and dielectric characterization of these newly fabricated chip-level Pt-HTCC packages.

High temperature↗

NASA NTRSDate not supplied

Electrical and Dielectric Characterizations of HTCC Electronic Packages for High Temperature Harsh Environment Applications

High temperature↗

NASA NTRSDate not supplied

GEER (Glenn Extreme Environments Rig): An Introduction

Our solar system contains many examples of what may be called extreme environments. These can be examples of high temperature and pressure environments in places like the deep atmospheres of the gas giants or on the surface of Venus. The permanently shadowed regions of the moon are examples of extreme cold conditions, a more common phenomena in space. Other extreme environments may be driven by high radiation conditions, or perhaps reactive atmospheric chemistry, which happens to be another feature of Venus. The extreme environments in the solar system pose interesting challenges to missions and technologists as they plan approaches to exploring and understanding our solar system.

GEER↗

NASA NTRSDate not supplied

Artemis Radiation Environment

NASA’s Artemis program is tasked with going back to the Moon sustainably, paving the way for Mars crewed missions. The long-term architecture of living around and on the Moon necessitates a more comprehensive understanding of the radiation environment that is much different than what is seen in low-Earth orbit on the International Space Station. Without the Earth’s protective magnetic field, high-energy charged particles from the Sun and galactic space can affect both avionics and crew if mitigation strategies are not considered. Programs under Artemis such as Gateway, the Human Landing System, the Space Launch System, Orion, and others use the space environments as defined in the Design Specification for Natural Environments for all engineering design partners. In this paper, the space radiation environments applicable to the Artemis program are discussed.

Artemis↗

DOE OSTI2022

Maximum Impact of Ionic Strength on Acid‐Catalyzed Reaction Rates Induced by a Zeolite Microporous Environment

Abstract The intracrystalline ionic environment in microporous zeolite can remarkably modify the excess chemical potential of adsorbed reactants and transition states, thereby influencing the catalytic turnover rates. However, a limit of the rate enhancement for aqueous‐phase dehydration of alcohols appears to exist for zeolites with high ionic strength. The origin of such limitation has been hypothesized to be caused by the spatial constraints in the pores via, e.g., size exclusion effects. It is demonstrated here that the increase in turnover rate as well as the formation of a maximum and the rate drop are intrinsic consequences of the increasingly dense ionic environment in zeolite. The molecularly sized confines of zeolite create a unique ionic environment that monotonically favors the formation of alcohol‐hydronium ion complexes in the micropores. The zeolite microporous environment determines the kinetics of catalytic steps and tailors the impact of ionic strength on catalytic rates.

Liu, Qiang↗

DOE OSTI2023

Switchgrass sward establishment selection is consistent across multiple environments and fertilization levels

Strong selection can occur during switchgrass sward establishment. Differences in establishment selection due to environment or management could provide information on genotype-by-environment variation and could influence strategies for breeding perennial grasses. Leaf samples were collected before sward establishment and from 3-year-old swards for two breeding groups (lowland and hybrid) at three locations. Within two locations, samples were collected from paired fertilized (112 kg N ha –1 ) and unfertilized plots. Allele frequencies from pooled DNA samples were studied through multivariate analysis of variance, genomewide trait predictions (heading date and winter survivorship), and genomically estimated breeding values (GEBVs) for individual sward survival within an independent data set. This study found only minor variations in selection due to location or management. Predicted heading dates of the hybrid population had significant changes due to fertilization and location. There were strong correlations among sward establishment survival GEBVs between growing environments (hybrid r = 0.77; gulf r = 0.97). Interestingly, this study found a small number of genotypes that were over-represented in established swards across all growing environments. This study reinforces a prior report of selection during sward establishment and indicates that only a small degree of establishment selection is location-specific within these diverse growing conditions.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Impact of the built, social, and food environment on long‐term weight loss within a behavioral weight loss intervention

Abstract Background Behavioral weight loss interventions can lead to an average weight loss of 5%–10% of initial body weight, however there is wide individual variability in treatment response. Although built, social, and community food environments can have potential direct and indirect influences on body weight (through their influence on physical activity and energy intake), these environmental factors are rarely considered as predictors of variation in weight loss. Objective Evaluate the association between built, social, and community food environments and changes in weight, moderate‐to‐vigorous physical activity (MVPA), and dietary intake among adults who completed an 18‐month behavioral weight loss intervention. Methods Participants included 93 adults (mean ± SD; 41.5 ± 8.3 years, 34.4 ± 4.2 kg/m 2 , 82% female, 75% white). Environmental variables included urbanicity, walkability, crime, Neighborhood Deprivation Index (includes 13 social economic status factors), and density of convenience stores, grocery stores, and limited‐service restaurants at the tract level. Linear regressions examined associations between environment and changes in body weight, waist circumference (WC), MVPA (SenseWear device), and dietary intake (3‐day diet records) from baseline to 18 months. Results Grocery store density was inversely associated with change in weight ( β = −0.95; p = 0.02; R 2 = 0.062) and WC ( β = −1.23; p < 0.01; R 2 = 0.109). Participants living in tracts with lower walkability demonstrated lower baseline MVPA and greater increases in MVPA versus participants with higher walkability (interaction p = 0.03). Participants living in tracts with the most deprivation demonstrated greater increases in average daily steps ( β = 2048.27; p = 0.02; R 2 = 0.039) versus participants with the least deprivation. Limited‐service restaurant density was associated with change in % protein intake ( β = 0.39; p = 0.046; R 2 = 0.051). Conclusion Environmental factors accounted for some of the variability (<11%) in response to a behavioral weight loss intervention. Grocery store density was positively associated with weight loss at 18 months. Additional studies and/or pooled analyses, encompassing greater environmental variation, are required to further evaluate whether environment contributes to weight loss variability.

Tewahade, Selam↗

DOE OSTI2024

Visual feedback and guided balance training in an immersive virtual reality environment for lower extremity rehabilitation

Balance training is essential for physical rehabilitation procedures, as it can improve functional mobility and enhance cognitive coordination. However, conventional balance training methods may have limitations in terms of motivation, real-time objective feedback, and personalization, which a virtual reality (VR) setup may provide a better alternative. In this work, we present an immersive VR training environment for lower extremity balance rehabilitation with real-time guidance and feedback. The VR training environment immerses the user in a 3D ice rink model where a virtual coach (agent) leads them through a series of balance poses, and the user controls a trainee avatar with their own movements. Here we developed two coaching styles: positive-reinforcement and autonomous-supportive, and two viewpoints of the trainee avatar: first-person and third-person. The proposed environment was evaluated in a user study with healthy, non-clinical participants (n = 16, 24.4 ± 5.7 years old, 9 females). Our results show that participants showed stronger performance in the positive-reinforcement style compared to the autonomous-supportive style. Additionally, in the third-person viewpoint, the participants exhibited more stability in the positive-reinforcement style compared to the autonomous-supportive style. For viewpoint, participants exhibited stronger performance in the first-person viewpoint compared to third-person in the autonomous-supportive style, while they were comparable in the positive-reinforcement style. We observed no significant effects on the foot height and number of mistakes. Furthermore, we report the analysis of user performance with balance training poses and subjective measures based on questionnaires to assess the user experience, usability, and task load. The proposed VR balance training could offer an interactive, adaptive, and engaging environment and open new potential research directions for lower extremity rehabilitation.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2022

Simulated CO 2 storage efficiency factors for saline formations of various lithologies and depositional environments using new experimental relative permeability data

Saline formations are attractive geologic reservoirs for permanent carbon dioxide (CO 2 ) storage. Here, the U.S. Department of Energy's National Energy Technology Laboratory (DOE-NETL) has worked to develop and refine methods and tools for the calculation of CO 2 storage potential in subsurface reservoirs. DOE-NETL's CO 2 -SCREEN provides an online tool for executing these storage methods. CO 2 storage efficiency terms are input parameters in DOE-NETL's methods and equations embedded in the CO 2 -SCREEN, which assesses pore space available for CO 2 storage. In this work, a modeling workflow was initiated to refine two CO 2 storage efficiency terms - volumetric displacement (E V ) and microscopic displacement (E d ). The models are based on new experimental relative permeability data that are specific to homogenous lithology and depositional environments of key subsurface saline formations targeted for CO 2 storage. In future work, heterogenous features will be added to this initial modeling effort to update efficiency factors as described in DOE-NETL's methods and CO 2 -SCREEN tool. E V accounts for the volume utilized in the reservoir under the areal plume, while E d accounts for saturation values in the plume to assess efficiency of CO 2 storage at the pore scale. The results of this work are significant in that prior values were based on a limited geologically non-specific relative permeability data set that were collected prior to 2009. Specifically, we applied numerical simulations using TOUGH3 models to update CO 2 storage efficiency values for supercritical CO 2 injection into brine-saturated reservoirs for three lithologies (clastics, limestone, dolomite) and six depositional environments (Marginal Marine, Strand Plain, Deltaic Complex Fluvial, Aeolian, Shallow Marine, and Reef) that have a high potential for geologic CO 2 storage. Experimental relative permeability data in cores from these environments were utilized in the models with corresponding rock type/sedimentary environment. Results of this study showed that dolomite followed by limestone generated higher ranges of storage efficiency compared to clastics. The updated values provided a tighter efficiency range for clastics, lower P 10 but higher P 90 range for limestone, and higher P 10 and P 90 for dolomite. In general, tighter reservoirs with relatively low permeability and porosity were associated with higher E V and E d , showing efficient reservoir and pore utilization in these scenarios. High reservoir pressure and temperature associated with increasing depth increased the E V , and high CO 2 injection rates resulted in increases in E V and E d , while the impact of permeability anisotropy was minimal after the 30-year injection period.

03 NATURAL GAS↗

DOE OSTI2022

Carburization and decarburization behavior of Grade 91 ferritic-martensitic steel in liquid sodium environments

Here, this paper presents a study of carbon transfer and its effect on microstructure and tensile properties of Grade 91 (G91) ferritic-martensitic steel exposed to sodium at 550–650 °C. Sodium exposure tests were conducted in Argonne's forced convection sodium loops up to exposure times of ~40,000 h. Thermal aging study of G91 steel was conducted in parallel to isolate the thermal aging effect from the sodium effect. It was found that sodium exposures at 650 °C dissolved M 23 C 6 carbides, eliminated the martensite subgrain structure resulting in excessive grain growth and reduced the tensile strength by >50%, while sodium exposures at 550 and 600 °C had an insignificant effect on its microstructure and tensile properties. These effects were attributed to the carburization/decarburization process of G91 steel in sodium environments. Carbon concentrations in sodium were determined by a foil equilibration method. The estimated carbon concentration was in the range of 0.8–1.2 ppm in the SMT-1 loop and 0.3–0.7 ppm in the SMT-2 loop. Thermodynamic analysis of the carburization – decarburization process was conducted for G91 steels exposed in sodium environments. The carbon activity-concentration relationship for G91 was evaluated by considering four phases in G91, i.e. bcc ferrite, M 23 C 6 , NbC and VC carbides. It was found that the carburization-decarburization process in G91 steel was dictated by M 23 C 6 carbides at high carbon activities, while NbC and VC carbides dominated the process at low carbon activities. The calculated carburization-decarburization boundary showed that G91 would undergo decarburization at 650 °C and carburization at 550 °C in the sodium loop environments, which was consistent with our experimental observations. This experimental and theoretical analysis provided a basis for predicting the effect of carbon transfer on the integrity of reactor components in sodium environments and for the design of new alloys used in sodium-cooled fast reactors.

36 MATERIALS SCIENCE↗

DOE OSTI2025

An end-to-end deep learning solution for automated LiDAR tree detection in the urban environment

Cataloging and classifying trees in the urban environment is a crucial step in urban and environmental planning; however, manual collection and maintenance of this data is expensive and time-consuming. Although algorithmic approaches that rely on remote sensing data have been developed for tree detection in forests, they generally struggle in the more varied urban environment. This work proposes a novel end-to-end deep learning method for the detection of trees in the urban environment from remote sensing data. Specifically, we develop and train a novel PointNet-based neural network architecture to predict tree locations directly from LiDAR data augmented with multi-spectral imagery. We compare this model to a number of high-performing baselines on a large and varied dataset in the Southern California region, and find that our method outperforms all baselines in terms of tree detection ability (75.5% F-score) and positional accuracy (2.28 meter root mean squared error), while being highly efficient. We then analyze and compare the sources of errors, and how these reveal the strengths and weaknesses of each approach. Our results highlight the importance of fusing spectral and structural information for remote sensing tasks in complex urban environments.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Harmonic Infrared and Raman Spectra in Molecular Environments Using the Polarizable Embedding Model

We present a fully analytic approach to calculate infrared (IR) and Raman spectra of molecules embedded in complex molecular environments modeled using the fragment-based polarizable embedding (PE) model. We provide the theory for the calculation of analytic second-order geometric derivatives of molecular energies and first-order geometric derivatives of electric dipole moments and dipole–dipole polarizabilities within the PE model. The derivatives are implemented using a general open-ended response theory framework, thus allowing for an extension to higher-order derivatives. The embedding-potential parameters used to describe the environment in the PE model are derived through first-principles calculations, thus allowing a wide variety of systems to be modeled, including solvents, proteins, and other large and complex molecular environments. Here, we present proof-of-principle calculations of IR and Raman spectra of acetone in different solvents. This work is an important step toward calculating accurate vibrational spectra of molecules embedded in realistic environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Revealing Sintering Kinetics of MoS 2 -Supported Metal Nanocatalysts in Atmospheric Gas Environments via Operando Transmission Electron Microscopy

The decoration of two-dimensional (2D) substrates with nanoparticles (NPs) serve as heterostructures for various catalysis applications. Deep understanding of catalyst degradation mechanisms during service conditions is crucial to improve the catalyst durability. In this work, we studied the sintering behavior of Pt and bimetallic Au-core Pt-shell (Au@Pt core–shell) NPs on MoS 2 supports at high temperatures under vacuum, nitrogen (N 2 ), hydrogen (H 2 ), and air environments by in situ gas-cell transmission electron microscopy (TEM). The key observations are summarized as effect of environment: while particle migration and coalescence (PMC) was the main mechanism that led to Pt and Au@Pt NPs degradation under vacuum, N 2 , and H 2 environments, the degradation of MoS 2 substrate was prominent under exposure to air at high temperatures. Pt NPs were less stable in H 2 environment when compared with the Pt NPs under vacuum or N 2 , due to Pt–H interactions that weakened the adhesion of Pt on MoS 2 . Effect of NP composition: under H 2 , the stability of Au@Pt NPs was higher in comparison to Pt NPs. This is because H 2 promotes the alloying of Pt–Au, thus reducing the number of Pt at the surface (reducing H 2 interactions) and increasing Pt atoms in contact with MoS 2 . Effect of NP size: The alloying effect promoted by H 2 was more pronounced in small size Au@Pt NPs resulting in their higher sintering resistance in comparison to large size Au@Pt NPs and similar size Pt NPs. The present work provides key insights into the parameters affecting the catalyst degradation mechanisms on 2D supports.

2D materials↗

DOE OSTI2021

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

Anthropogenic radionuclides, including long-lived heavy actinides such as americium and curium, represent the primary long-term challenge for management of nuclear waste. The potential release of these wastes into the environment necessitates understanding their interactions with biogeochemical compounds present in nature. Here, we characterize the interactions between the heavy actinides, Am 3+ and Cm 3+ , and the natural lanthanide-binding protein, lanmodulin (LanM). LanM is produced abundantly by methylotrophic bacteria, including Methylorubrum extorquens, that are widespread in the environment. We determine the first stability constant for an Am 3+ -protein complex (Am 3 LanM) and confirm the results with Cm 3 LanM, indicating a ~5-fold higher affinity than that for lanthanides with most similar ionic radius, Nd 3+ and Sm 3+ , and making LanM the strongest known heavy actinide-binding protein. The protein’s high selectivity over 243 Am’s daughter nuclide 239 Np enables lab-scale actinide-actinide separations as well as provides insight into potential protein-driven mobilization for these actinides in the environment. The luminescence properties of the Cm 3+ -LanM complex, and NMR studies of Gd 3+ -LanM, reveal that lanmodulin-bound f-elements possess two coordinated solvent molecules across a range of metal ionic radii. Finally, we show under a wide range of environmentally relevant conditions that lanmodulin effectively outcompetes desferrioxamine B, a hydroxamate siderophore previously proposed to be important in trivalent actinide mobility. Overall, these results suggest that natural lanthanide-binding proteins such as lanmodulin may play important roles in speciation and mobility of actinides in the environment; it also suggests that protein-based biotechnologies may provide a new frontier in actinide remediation, detection, and separations.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2022

Improved Boundary Conditions for Coupled Geospace Models: An Application in Modeling Spacecraft Surface Charging Environment

Abstract Spacecraft surface charging in the inner magnetosphere often occurs in the pre‐midnight to the dawn sector when electron fluxes of tens of keV increase. Inner magnetosphere ring current models can be used to simulate/predict the spacecraft surface charging environment, with their outer boundary conditions specified either based on observations or provided by other models, such as MHD models. In the latter approach, using MHD quantities, the flux spectrum at the outer boundary is commonly assumed to follow a Kappa or Maxwellian distribution function. Such a method however often departs greatly from the realistic spectrum at E < tens of keV, a crucial energy range in the surface charging anomaly. In order to achieve a better representation of the surface charging environment, we propose to combine the MHD‐parameterized flux spectrum with an empirical electron flux model of E < 40 keV to set the electron flux boundary condition. Results indicate that as opposed to the case where the MHD‐parameterized flux distribution is solely used at the model boundary, simulations with the new boundary condition yields a more intense surface charging environment. The integrated electron flux between 10 < E < 50 keV, a measure of the severity of the surface charging environment, is significantly enhanced by 1‐2 orders of magnitude, leading to a much better agreement with Van Allen Probes measurements. This study hence demonstrates a reasonable solution to the setting of outer boundary conditions for inner magnetosphere models and is recommended for coupled geospace circulation models.

79 ASTRONOMY AND ASTROPHYSICS↗