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At least 973 records · Page 54

All sources NASA NTRS DOE OSTI

NASA NTRSDate not supplied

All-Metal Antennas for Applications in Extreme Space Environments

The feasibility of an all-metal antenna for transmission of science data by spacecraft, landers, and rovers operating in the extreme environment of space is investigated. The all-metal antenna is of the short backfire type with a waveguide feed and generates a linearly polarized radiation. The investigation includes the modeling, design, fabrication, and characterization of the antenna. The paper summarizes the preliminary results. Potential applications of an all-metal antenna include communication systems required to operate in the extreme hot environment of Mercury and Venus, extreme cold and high radiation environment of Jupiter’s icy moon, and Artemis missions that involve human/robotic exploration and long-term presence on the Moon.

Extreme Environment↗

NASA NTRS2022

RF Environment Data Analysis for UAS Operations

As the usage of radio frequency spectrum and uncrewed aircraft systems continue to grow, the radio frequency environment and its implications to flight safety should be understood. This is important to ensure control and command links as well as data collection links maintain strong communications during flight. NASA System-Wide Safety (SWS) is currently developing standards of flight safety but lacks methods for establishing confidence in the availability of radio frequency space to make a go/no-go decision for drone flights. This study examines information about the radio modules used by SWS and how they interact with the RF environment though analysis of historical spectrum data. This review studies the potential effectiveness of observing the power spread and occupancy methods as they apply to the flight system radios. It has been determined that viewing the frequency and time when the environment is greater than a threshold which indicates potential interference levels may give insight into the patterns of spectrum usage.

Radio Frequency↗

NASA NTRSDate not supplied

All-Metal Antennas for Applications in Extreme Space Environments

The feasibility of an all-metal antenna for transmission of science data by spacecraft, landers, and rovers operating in the extreme environment of space is investigated. The all-metal antenna is of the short backfire type with a waveguide feed and generates a circularly polarized radiation. The investigation includes the modeling, design, fabrication, and characterization of the antenna. The paper summarizes the preliminary results. Potential applications of an all-metal antenna include communication systems required to operate in the extreme hot environment of Venus and in the extreme cold and high radiation environment of Jupiter’s icy moon.

Antennas↗

NASA NTRSDate not supplied

Atomic Oxygen Environment, Effects and Simulation

Atomic oxygen is the most predominant constituent in the low Earth orbital environment between the altitudes of 180 and 650 km. It is also a major constituent of the Mars orbital environment. It is very chemically reactive and can oxidize materials on the outside of spacecraft. In many cases the reaction products are volatile which can lead to mechanical failure. Stable oxides can also form that change the optical or thermal properties of the material. The importance of understanding atomic oxygen reactions with materials has led to both flight experiments in low Earth orbit and ground-based testing in vacuum chambers containing atomic oxygen to study its’ effect on materials. This presentation will focus on defining atomic oxygen environments, discussing atomic oxygen effects on spacecraft materials, reviewing some methods of atomic oxygen simulation, and discussing differences in ground-based testing and space testing as well as synergistic effects.

atomic oxygen, space environment, ground-based tes↗

NASA NTRSDate not supplied

Materials for Power Transmission in Extreme Environments

NASA’s goal for a sustained human presence on the Moon and a future Lunar economy requires the development of novel power transmission materials for extreme environments. As an increasing number of public and private entities set their sights towards a future on the Moon, the demand for surface power will dramatically increase – potentially up to megawatt levels. A Lunar economy is envisioned to include a human habitat, manned and unmanned science exploration assets, excavation rovers and systems, and large-scale infrastructure construction such as solar arrays and power grids. A NASA trade study estimated that 1 to 3 km of power transmission lines (1 to 3 KV ac and dc) will be needed over time. Current high power and voltage SOA cables/wire can easily exceed 1 kg/m where mass is not as critical. Connectors, deployment spools and robots further increase the subsystem mass significantly increasing costs. On the other hand, advances in aeronautics provides path towards space missions. The operating environment on the Moon presents substantial risk to safe and reliable power transmission due to space weathering and degradation. These challenges include cosmic and UV radiation, extreme temperatures swings, the electrostatic Lunar exosphere, and the electrostatic and abrasive lunar regolith. The critical need for lightweight, safe and reliable power cables/wires materials is evident. In this presentation, the extreme high altitude and lunar environments and recent materials development from NASA Glenn Research Center’s High Voltage Materials team towards meeting NASA’s objectives and goals for aeronautics and space missions.

Cu/CNT conductors↗

DOE OSTI2023

Geographically Dependent Sustainability Indicators for Comparison of Conventional Vegetable Production to Controlled-Environment Agriculture

Many food system lifecycle analyses distill agricultural production and supply chain impacts into single-value sustainability metrics for various food categories. These studies provide an overview of the food supply system that highlight striking results such as the GHG impacts of meat production. The supply chain impacts of vegetable production occupy the middle ground; higher than average food loss and waste, lower than average overall energy use, etc. However, aggregated results obscure the sustainability implications of the location of food production, especially for vegetables. Moreover, the increasing instability of food production systems are not captured, as illustrated by a recent Washington Post article. According to a UC Merced study conducted for the state, California farmers left nearly 400,000 acres of agricultural land unplanted last year because of a lack of water. The result, the study found, was a direct economic cost to farmers of $1.1 billion and the loss of nearly 9,000 agricultural jobs. (The Washington Post, March 21, 2022.) Previous work quantified the food-energy-water nexus implications of transitioning vegetable production from large, centralized agricultural operations to smaller distributed production in controlled-environment farms (CEA). The importance of location-specific data is especially evident for water use. Water impacts of the food system are primarily local to the region where food is produced, water impacts vary significantly between locations, and water stress is a major concern in locations that currently host large agricultural operations. Location-specific data is needed to accurately assess the water impacts of transitioning to CEA. The location of farms in relation to consumers impacts transportation energy use, food loss and waste, and requirements for food processing (e.g., to reduce weight, preserve foods for long storage, and package foods to reduce damage and loss) Reducing transport is particularly relevant for agricultural products that could be grown in CEAs (fruits, vegetables, protein). Access to nutritious food is not evenly distributed in the population. Remote communities, communities in harsh environments, and economically-disadvantaged communities often have poor access to healthy foods. CEA is ideally suited to these environments. However, the energy and water use of CEA, while in many respects lower overall than conventional supply chains, are concentrated within communities and could have significant local impacts. This paper reports on development of sustainability metrics that seek to capture the tradeoffs between the current supply chain and a CEA supply chain for vegetables; focusing on the location-dependent implications of water use, the transition from largely fossil fuel based energy use to electricity, and the food access, resilience and wellbeing implications of urban versus rural food production.

controlled-environment agriculture↗

DOE OSTI2014

Interactions between cumulus convection and its environment as revealed by the MC3E sounding array

This study attempts to understand interactions between midlatitude convective systems and their environments through a heat and moisture budget analysis using the sounding data collected from the Midlatitude Continental Convective Clouds Experiment (MC3E) in central Oklahoma. Distinct large-scale structures and diabatic heating and drying profiles are presented for cases of weaker and elevated thunderstorms as well as intense squall line and supercell thunderstorm events during the campaign. The elevated cell events were nocturnal convective systems occurring in an environment having low convective available potential energy (CAPE) and a very dry boundary layer. In contrast, deeper convective events happened during the morning into early afternoon within an environment associated with large CAPE and a near-saturated boundary layer. As the systems reached maturity, the diagnosed diabatic heating in the latter deep convective cases was much stronger and of greater vertical extent than the former. Both groups showed considerable diabatic cooling in the lower troposphere, associated with the evaporation of precipitation and low-level clouds. The horizontal advection of moisture also played a dominant role in moistening the lower troposphere, particularly for the deeper convective events, wherein the near surface southeasterly flow allows persistent low-level moisture return from the Gulf of Mexico to support convection. The moisture convergence often was present before these systems develop, suggesting a strong correlation between the large-scale moisture convergence and convection. As a result, sensitivity tests indicated that the uncertainty in the surface precipitation and the size of analysis domain mainly affected the magnitude of these analyzed fields rather than their vertical structures.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Machine Learning-Enabled Correlation and Modeling of Multimodal Response of Thin Film to Environment on Macro and Nanoscale Using “Lab-on-a-Crystal”

To close the feedback loop between artificial intellegence-controlled materials synthesis and characterization, material functionality must be rapidly tested. A platform for high-throughput multifunctional materials characterization is developed using a quartz crystal microbalance with auxiliary in-plane electrodes and a custom gas/vapor flow cell, enabling simultaneous scanning probe microscopy and electrical, optical, gravimetric, and viscoelastic characterization on the same film under controlled environment. The lab-on-a-crystal in situ multifunctional output allows direct correlations between the gravimetric/viscoelastic, electrical, and optical responses of polymer film in response to environment. Finally, when multiple film properties are used to augment the training set for machine learning regression, prediction of material response to the environment improves by a factor of 13 when <5% of the total dataset is used for model training.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Probe the Localized Electrochemical Environment Effects and Electrode Reaction Dynamics for Metal Batteries using In Situ 3D Microscopy

Uncontrollable dendrite growth is closely related to non-uniform reaction environments. However, there is a lack of understanding and analysis methods to probe the localized electrochemical environment (LEE). Here the effects of the LEE are investigated, including localized ion concentrations, current density, and electric potential, on metal plating/stripping dynamics and dendrite minimization. A novel in situ 3D microscopy technique is developed to image the morphology dynamics and deposition rate of Zn plating/stripping processes on 3D Zn–Mn anodes. Using the in situ 3D microscope, the electrode morphology changes during the reactions are directly imaged and Zn deposition rate maps at different time points are obtained. It is found that reaction kinetics are highly correlated to LEE and electrode morphology. To further quantify the LEE effects, the digital twin technique is employed that allows the accurate calculation of the electrochemical environments, such as localized ion concentrations, current density, and electric potential, which cannot be directly measured from experiments. We found that the curvature of the 3D electrode surface determines the LEE and significantly influences reaction kinetics. This provides a new strategy to minimize the dendrite formation by designing and optimizing the 3D geometry of the electrode to control the LEE.

36 MATERIALS SCIENCE↗

DOE OSTI2017

K‐band luminosity–environment relation in three different galaxy samples of the Sloan Digital Sky Survey III

The aim of this work is to examine the environmental dependence of K‐band luminosity in the Main, Low Redshift (LOWZ), and Constant Mass (CMASS) galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10). Overall, the environmental dependence of K‐band luminosity is very mild. In two volume‐limited Main samples with the luminosity −20.5 ≤ M r ≤ −18.5 and −22.5 ≤ M r ≤ −20.5, respectively, we find that the environmental dependence of K‐band luminosity in the luminous volume‐limited Main galaxy sample still can be observed, but this dependence in the faint volume‐limited Main galaxy sample is very weak. Considering the disadvantages of the use of volume‐limited samples, we apply the apparent magnitude‐limited Main galaxy sample, divide the Main galaxy sample of the SDSS DR10 into subsamples with a redshift binning size of Δ z =0.01, and then analyze the environmental dependence of K‐band luminosity of subsamples in each redshift bin. Such a method also is used in the LOWZ and CMASS galaxy samples. K‐band luminosity of the Main galaxies shows substantial correlation with the local environment in many redshift bins. In the LOWZ galaxy sample, K‐band luminosity of galaxies shows substantial correlation with the local environment only in the redshift region 0.16 ≤ z ≤ 0.21, while K‐band luminosity of CMASS galaxy sample is only weakly correlated with the local environment. Statistical results also show that in the apparent magnitude‐limited main galaxy sample and the LOWZ galaxy sample, environmental dependence of K‐band luminosity becomes weak with increasing redshift.

Deng, X. ‐F.↗

DOE OSTI2022

Secure Collaborative Environment for Seamless Sharing of Scientific Knowledge

In a secure collaborative environment, tera-bytes of data generated from powerful scientific instruments are used to train secure machine learning (ML) models on exascale computing systems, which are then securely shared with internal or external collaborators as cloud-based services. Devising such a secure platform is necessary for seamless scientific knowledge sharing without compromising individual, or institute-level, intellectual property and privacy details. By enabling new computing opportunities with sensitive data, we envision a secure collaborative environment that will play a significant role in accelerating scientific discovery. Several recent technological advancements have made it possible to realize these capabilities. In this paper, we present our efforts at ORNL toward developing a secure computation platform. We present a use case where scientific data generated from complex instruments, like those at the Spallation Neutron Source (SNS), are used to train a differential privacy enabled deep learning (DL) network on Summit, which is then hosted as a secure multi-party computation (MPC) service on ORNL’s Compute and Data Environment for Science (CADES) cloud computing platform for third-party inference. In this feasibility study, we discuss the challenges involved, elaborate on leveraged technologies, analyze relevant performance results and present the future vision of our work to establish secure collaboration capabilities within and outside of ORNL.

Yoginath, Srikanth↗

DOE OSTI2023

Adrastea: An Efficient FPGA Design Environment for Heterogeneous Scientific Computing and Machine Learning

We present Adrastea, an efficient FPGA design environment for developing scientific machine learning applications. FPGA development is challenging, from deployment, proper toolchain setup, programming methods, interfacing FPGA kernels, and more importantly, the need to explore design space choices to get the best performance and area usage from the FPGA kernel design. Adrastea provides an automated and scalable design flow to parameterize, implement, and optimize complex FPGA kernels and associated interfaces. We show how virtualization of the development environment via virtual machines is leveraged to simplify the setup of the FPGA toolchain while deploying the FPGA boards and while scaling up the automated design space exploration to leverage multiple machines concurrently. Adrastea provides an automated build and test environment of FPGA kernels. By exposing design space hyper-parameters, Adrastea can automatically search the design space in parallel to optimize the FPGA design for a given metric, usually performance or area. Adrastea simplifies the task of interfacing with the FPGA kernels with a simplified interface API. To demonstrate the capabilities of Adrastea, we implement a complex random forest machine learning kernel with 10,000 input features while achieving extremely low computing latency without loss of prediction accuracy, which is required by a scientific edge application at SNS. We also demonstrate Adrastea using an FFT kernel and show that for both applications Adrastea is able to systematically and efficiently evaluate different design options, which reduced the time and effort required to develop the kernel from months of manual work to days of automatic builds.

Young, Aaron↗

DOE OSTI2020

Projected changes to severe thunderstorm environments as a result of twenty-first century warming from RegCM CORDEX-CORE simulations

Hazardous weather related to the occurrence of severe thunderstorms including tornadoes, high-winds, and hail cause significant damage globally to life and property every year. Yet the impact on these storms from a warming climate remains a difficult task due to their transient nature. Here, we investigate the change in large-scale environments in which severe thunderstorms form during twenty-first century warming (RCP2.6 and RCP8.5) in a group of RegCM CORDEX-CORE simulations. Severe potential is measured in terms of Convective Available Potential Energy (CAPE) and vertical wind-shear during the severe seasons in three regions which are known to currently be prone to severe hazards: North America, subtropical South America, and eastern India and Bangladesh. In every region, environments supportive for severe thunderstorms are projected to increase during the warm season months in both the RCP2.6 and RCP8.5 scenarios during the twenty-first century. The number of days supportive for severe thunderstorms increases by several days per season over the vast majority of each region by the end of the century. Analyzing the CAPE and shear trends during the twenty-first century, we find seasonally and regionally specific changes driving the increased severe potential. Twenty-first century surface warming is clearly driving a robust increase in CAPE in all regions, however poleward displacement of vertical shear in the future leads to the displacement of severe environments over North America and South America. The results found here relate that severe impacts in the future cannot be generalized globally, and that regionally specific changes in vertical shear may drive future movement of regions prone to severe weather.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

Corrosion Resistance of Cu-Ni-Si Alloy Under High-Temperature, High-Pressure H{sub 2}S and Cl{sup −} Environments

In this study, Cu-Ni-Si alloy was subjected to corrosion resistance tests under simulated high-temperature, high-pressure H{sub 2}S and Cl{sup −} environments. The corrosion rates, electrochemical performance, surface morphologies, and chemical compositions of the Cu-Ni-Si alloy after corrosion were analyzed by the mass loss method, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive x-ray spectrometry, and x-ray diffraction. The results showed that, at the initial stage of corrosion, because of the loose corrosion product layer initially formed on the surface, a high corrosion rate was observed for the Cu-Ni-Si alloy under high-temperature, high-pressure environments. With the progress of corrosion, the corrosion rate gradually decreased and reached a steady state. Because at the later stage, a passive film was formed on the alloy surface, further inhibiting the corrosion of the alloy and improved its corrosion resistance. The Cu-Ni-Si alloy exhibited good corrosion resistance under high-temperature, high-pressure H{sub 2}S and Cl{sup −} environments.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Nationwide Buildings Energy Research enabled through an integrated Data Intensive Scientific Workflow and Advanced Analysis Environment

Modern workflow systems enable scientists to run ensemble simulations at unprecedented scales and levels of complexity, allowing them to study system sizes previously impossible to achieve, due to the inherent resource requirements needed for the modeling work. However as a result of these new capabilities the science teams suddenly also face unprecedented data volumes that they are unable to analyze with their existing tools and methodologies in a timely fashion. In this paper we will describe the ongoing development work to create an integrated data intensive scientific workflow and analysis environment that offers researchers the ability to easily create and execute complex simulation studies and provides them with different scalable methods to analyze the resulting data volumes. The integration of simulation and analysis environments is hereby not only a question of ease of use, but supports fundamental functions in the correlated analysis of simulation input, execution details and derived results for multi-variant, complex studies. To this end the team extended and integrated the existing capabilities of the Velo data management and analysis infrastructure, the MeDICi data intensive workflow system and RHIPE the R for Hadoop version of the well-known statistics package, as well as developing a new visual analytics interface for the result exploitation by multi-domain users. The capabilities of the new environment are demonstrated on a use case that focusses on the Pacific Northwest National Laboratory (PNNL) building energy team, showing how they were able to take their previously local scale simulations to a nationwide level by utilizing data intensive computing techniques not only for their modeling work, but also for the subsequent analysis of their modeling results. As part of the PNNL research initiative PRIMA (Platform for Regional Integrated Modeling and Analysis) the team performed an initial 3 year study of building energy demands for the US Eastern Interconnect domain, which they are now planning to extend to predict the demand for the complete century. The initial study raised their data demands from a few GBs to 400GB for the 3year study and expected tens of TBs for the full century.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2023

Characterization of boundary precipitation in a heavy ion irradiated tungsten heavy alloy under the simulated fusion environment

In the concerted effort to identify materials capable of surviving the adverse environment of a fusion reactor interior, tungsten heavy alloys have been put forth as leading candidates. Experimental trials and behavioral studies have yielded positive results for their adoption by taking advantage of the alloy’s unique balance of inherently high fracture toughness and low sputter yields; yet due to their relative novelty in the fusion community, there remains a lack of understanding on the response of these materials to the extended high temperature irradiation environment of the reactor interior. Further, to alleviate this issue and provide the necessary data on the behavior of tungsten heavy alloys to the simulated fusion environment, a 90W-7Ni-3Fe alloy has been subjected to elevated temperature sequential Ni + and He + ion irradiations to mimic the expected displacement damage and gas production expected after five years of service as a plasma facing material component. Atomic-scale structural analyses and nanoscale chemical mapping have identified the formation of two distinct precipitation structures, a surface localized η-carbide and an a-W 2 C type tungsten carbide, both of which appear to originate at the bi-phase interface between W and the ductile phase. This irradiation assisted and induced precipitate formation respectively is anticipated to adversely affect these materials by selective embrittlement at bi-phase interfaces leading to a reduction in the material’s overall fracture toughness during prolonged high temperature irradiation. It is asserted that any potential exposure to C during fusion reactor operational service should be minimized as to prevent the formation of these phases.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Dynamic Wettability Alteration of Calcite, Silica and Illite Surfaces in Subsurface Environments: A Case Study of Asphaltene Self-Assembly at Solid Interfaces

A basic understanding of dynamic wettability alteration at complex solid interfaces in varying fluidic environments representative of the subsurface environments is essential for engineering field-scale strategies to enhance energy recovery while reducing environmental impacts. In this study, we characterize dynamic wettability alteration at solid surfaces (e.g., calcite, silica and illite) resulting from the self-assembly and adsorption of polyaromatic macromolecules known as asphaltenes in heptane and toluene solvents at 200 bar and 313 K using classical molecular dynamics simulations. These conditions are chosen to be representative of the subsurface environments. On adding asphaltenes, the equilibrium contact angles on calcite, silica and illite surfaces which are in the range of 25–34° increased to 69–79°. The adsorption and self-assembly of asphaltene molecules on the solid surfaces and the accumulation on water/hydrocarbon interfaces reduces the spreading distances of water molecules and enhances the hydrophobicity of the solid surfaces. Moreover, the accumulation of asphaltene molecules at the water/liquid hydrocarbon interfaces results in a reduction of the interfacial tension of water/heptane and water/toluene, thus stabilizing the water droplet. The enhanced surface hydrophobicity contributes to the formation of layered structures of heptane and toluene close to the solid surfaces and reduces the self-diffusivities of these molecules close to the surface.

42 ENGINEERING↗

DOE OSTI2024

Overview, Progress and Next Steps for Our Understanding of the Near-Earth Space Radiation and Plasma Environment: Science and Applications

The Near-Earth Space Radiation and Plasma Environment falls within the realm of G3 Cluster (G3 refers to ‘Near-Earth Radiation and Plasma Environment’ of the ‘Coupled Geospace System’) under the COSPAR (Committee On Space Research) /International Space Weather Action Teams (ISWAT) Initiative. The diverse and dynamic particle populations from this region pose challenges from both science and space weather-impact perspectives. The G3 cluster has intimate connections with solar, heliosphere clusters, and the other Geospace ones (G1, G2) through a chain of physical processes. This paper reviews recent scientific advances in understanding this complex space environment, identifies gaps in research and space weather applications, and maps out our recommendations on priorities for the next 5-10 years.

Zheng, Yihua↗