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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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Exploring Unstructured Mesh Adaptation for Hybrid Reynolds-Averaged Navier–Stokes/Large Eddy Simulation

Mesh adaptation methods for the Reynolds-averaged Navier–Stokes (RANS) equations are rapidly maturing and beginning to impact the design of aerospace vehicles. RANS turbulence modeling improvements have slowed and may stagnate. Wall-modeled large eddy simulation (LES) and hybrid RANS/LES (HRLES) may provide an improved modeling capability but require specialized expertise to construct appropriate meshes and are considered be too ex-pensive for routine practical use. The realization of the CFD Vision 2030 Study includes improving geometry linkage, mesh generation/adaptation, and turbulence modeling/resolving methods for automated management of errors and uncertainties of physics-based, predictive modeling that can set the stage for ensuring a vehicle is in compliance with a regulation or specification (i.e., certification or qualification by analysis). An exploration of mesh adaptation for HRLES is performed to document synergies and challenges between mesh adaptation and HRLES. Vortex breakdown over a delta wing is examined to show the improvement of HRLES over RANS turbulence modeling approaches. A high lift configuration is shown to demonstrate complex geometry capability. Research and development opportunities are identified to advocate for continuing investments that may allow HRLES to enter routine practical use as a tool for aerospace vehicle analysis and design.

Michael A Park↗
NASA NTRSDate not supplied

Lunar Mega Project: Processes, Work Flow and Terminology of the Terrestrial Construction Industry versus the Space Industry

Recent developments around the world show an increased interest and international activity toward developing a lunar surface human and robotic presence with a long term, sustainable vision. In Europe, the construction of a "Moon Village" has been proposed, and China has stated its intention to build a research station with a crew at the lunar South Pole. Russia stated it will land cosmonauts on the Moon in the 2030's. India has sent an orbiter, a robotic lander, and rover to the Moon. The USA intends to land the first woman and a man on the Moon by 2024 to initiate a sustained human lunar presence.A lunar research station with associated commercial activities will require infrastructure to become a permanent capability. Landing and launch pads, propellant storage and distribution farms, spacecraft access and handling structures, cranes, blast protection berms or walls, roads, graded areas, dust stabilized areas, foundations, parking lots, radiation shelters, micro-meteorite protection hangars, habitats and other human shelters, greenhouse farms, utility trenches, power plants, industrial water and oxygen extraction plants, communications antenna towers, thermal protection, mining zones, crater access and sub-surface access will be required to create a safe and sustainable lunar operations capability. This infrastructure will require significant construction activities in an extreme environment, with risky and expensive operations. On Earth, there are similar large and expensive projects (>$1 Billion) in difficult locations that attract a lot of public attention. These are known as "Mega Projects" and examples include bridges, tunnels, highways, railways, airports, seaports, power plants, dams, wastewater projects, Special Economic Zones (SEZ), oil and natural gas extraction projects, public buildings, information technology systems, aerospace projects, and weapons systems. Large consortiums consisting of public and private entities typically implement these infrastructure Mega-Projects.This paper will compare the typical design process, project management process, and work flow in the terrestrial construction industry to the space industry in order to create a better understanding between the terrestrial construction industry and the space industry, to further enable collaboration on a lunar Mega Project to build infrastructure on the Moon. In addition, a glossary of respective industry terminology with annotated linkages and definitions has been compiled. This information will enable contracts and business practices to be formulated for generating requests for proposals (RFP) by governments to consortiums consisting of construction and space industry companies that will bid on Lunar Infrastructure Projects that could lead to contracts to build the permanent capabilities.

Robert P Mueller↗
NASA NTRS2018

Space Science and Technology Partnership Forum: In-Space Assembly Data Collection and Analysis

The Space Science and Technology Partnership Forum was established in 2015 to identify synergistic efforts and technologies across the government. In-Space Assembly (iSA) is the focus of the topic area that NASA is currently coordinating with other government agencies. This paper focuses on the data collection process, the data analysis of that information, and preliminary insights gleaned from the data. The goal of the analysis is to understand the linkages within the collected data, identifying synergies and gaps, and provide visualization of the current state of iSA needs and capability development across the government. Capability roadmaps, Venn diagrams, bubble charts, and scorecards (an overview of each individual iSA capability) are used to visualize the results of this analysis, which reveals areas of possible inter-agency collaboration, investment gaps in capabilities relative to the need, and capabilities that warrant engagement across multiple agencies to eliminate potential inefficiencies.

Dale C Arney↗
NASA NTRS2020

Changes in Vegetation Phenology and Productivity in Alaska Over the Past Two Decades

Understanding trends in vegetation phenology and growing season productivity at a regional scale is important for global change studies, particularly as linkages can be made between climate shifts and the vegetation’s potential to sequester or release carbon into the atmosphere. Trends and geographic patterns of change in vegetation growth and phenology from the MODerate resolution Imaging Spectroradiometer (MODIS) satellite data sets were analyzed for the state of Alaska over the period 2000 to 2018. Phenology metrics derived from the MODIS Normalized Difference Vegetation Index (NDVI) time-series at 250 m resolution tracked changes in the total integrated greenness cover (TIN), maximum annual NDVI (MAXN), and start of the season timing (SOST) date over the past two decades. SOST trends showed significantly earlier seasonal vegetation greening (at more than one day per year) across the northeastern Brooks Range Mountains, on the Yukon-Kuskokwim coastal plain, and in the southern coastal areas of Alaska. TIN and MAXN have increased significantly across the western Arctic Coastal Plain and within the perimeters of most large wildfires of the Interior boreal region that burned since the year 2000, whereas TIN and MAXN have decreased notably in watersheds of Bristol Bay and in the Cook Inlet lowlands of southwestern Alaska, in the same regions where earlier-trending SOST was also detected. Mapping results from this MODIS time-series analysis have identified a new database of localized study locations across Alaska where vegetation phenology has recently shifted notably, and where land cover types and ecosystem processes could be changing rapidly.

Vegetation↗
NASA NTRS2020

Seasonality of Biological and Physical Systems as Indicators of Climate Variation and Change

Evidence-based responses to climate change by society require operational and sustained information including biophysical indicator systems that provide up-to-date measures of trends and patterns against historical baselines. Two key components linking anthropogenic climate change to impacts on socio-ecological systems are the periodic inter- and intra-annual variations in physical climate systems (seasonality) and in plant and animal life cycles (phenology). We describe a set of national indicators that reflect sub-seasonal to seasonal drivers and responses of terrestrial physical and biological systems to climate change and variability at the national scale. Proposed indicators and metrics include seasonality of surface climate conditions (e.g., frost and freeze dates and durations), seasonality of freeze/thaw in freshwater systems (e.g., timing of stream runoff and durations of lake/river ice), seasonality in ecosystem disturbances (e.g., wildfire season timing and duration), seasonality in vegetated land surfaces (e.g., green-up and brown-down of landscapes), and seasonality of organismal life-history stages (e.g., timings of bird migration). Recommended indicators have strong linkages to variable and changing climates, include abiotic and biotic responses and feedback mechanisms, and are sufficiently simple to facilitate communication to broad audiences and stakeholders interested in understanding and adapting to climate change.

Seasonality↗
NASA NTRSDate not supplied

Integrated Framework to Enable Design Space Exploration of In-Space Transportation Architectures

Even with the recent shift in focus of NASA’s human spaceflight program towards the Moon, the long-term goal continues to be crewed missions to Mars. Regardless of the accepted architecture, in-space transportation systems are a critical portion to achieving this goal. An emphasis is placed on presenting decision makers with many options early on to make an informed down-selection. Although current processes are able to address any aspects of the challenging underlying multi-disciplinary analysis and optimization problem of these advanced concepts, they are unable to comprehensively perform design space exploration inexpensively,potentially leaving attractive alternatives on the table. A design framework is proposed that is capable of enabling the integrated mission analysis, vehicle sizing and synthesis problem for in-space transportation architectures. This framework is enabled through the use of the vehicle synthesis tool, Dynamic Rocket Equation Tool, various subsystem sizing models, and low-thrust trajectory optimization codes. As a case study to demonstrate the framework, two design points of a hybrid propulsion stage concept, studied by Georgia Tech’s 2018 Revolutionary Aerospace Systems Concepts-Academic Linkage team, is explored.

Akshay Prasad↗
NASA NTRSDate not supplied

Integrated Framework to Enable Design Space Exploration of In-Space Transportation Architectures

Even with the recent shift in focus of NASA’s human spaceflight program towards the Moon, the long-term goal continues to be crewed missions to Mars. Regardless of the accepted architecture, in-space transportation systems are a critical portion to achieving this goal. An emphasis is placed on presenting decision makers with many options early on to make an informed down-selection. Although current processes are able to address any aspects of the challenging underlying multi-disciplinary analysis and optimization problem of these advanced concepts, they are unable to comprehensively perform design space exploration inexpensively, potentially leaving attractive alternatives on the table. A design framework is proposed that is capable of enabling the integrated mission analysis, vehicle sizing and synthesis problem for in-space transportation architectures. This framework is enabled through the use of the vehicle synthesis tool, Dynamic Rocket Equation Tool, various subsystem sizing models, and low-thrust trajectory optimization codes. As a case study to demonstrate the framework, two design points of a hybrid propulsion stage concept, studied by Georgia Tech’s 2018 Revolutionary Aerospace Systems Concepts-Academic Linkage team, is explored.

Akshay Prasad↗
NASA NTRSDate not supplied

Enhancing NASA Earth Science Data Discovery from Scientific Publications

Earth observations from space borne instruments have evolved explosively in the past decades. Following closely are reanalysis systems assimilating model and observational data, yielding even longer records and larger number of variables. Thanks to advances in internet technology, it is now easier than ever to visualize and analyze these data using web interfaces. On the other hand, it also becomes an increasingly daunting task to build upon the existing knowledge published in various peer reviewed sources, and navigate toward the most relevant data, analysis, and visualization. We present an analysis of a subset of publications that utilized a popular visualization web interface at the NASA Goddard Earth Science Data and Information Services Center. Known as "Giovanni", it allows researchers from wide backgrounds to work with hundreds of variables from space observations and assimilation systems. Since coming online more than a decade ago, Giovanni has been credited in more than 100 papers per year, and the total count now is estimated to be nearly 1,500. Many of these papers contain valuable information about when, where and how Giovanni has been used, and hence forge an opportunity to learn and share the knowledge of which variables were used for what research projects. The purpose of our work is to retrieve the information from the papers and organize it as a knowledge repository which links together datasets, variables, places, dates and phenomena all of which reflect the essence of the published research. Since the publications are unstructured texts, we use natural language processing along with machine learning methods in the retrieval process. One of the challenges is deciphering the dataset names, because in many cases researchers refer to variables, rather than the datasets containing them. To constrain the number of terms, we deploy Earth Science ontologies as dictionaries for the term extraction. We demonstrate that storing these terms and underlying ontologies, along with datasets, variables and papers in the knowledge graph database, enables various linkages between all these entities facilitating the data discovery. Thus, we are setting a qualitatively new stage in improvements of web data interfaces, where machine learning techniques are used to establish and optimize usage-based discovery of data.

Irina V Gerasimov↗
NASA NTRS2017

Extension of MBSE for Project Programmatics Management on the Asteroid Redirect Robotic Mission

Model-based Systems Engineering can be employed beyond management of the technical architecture development of a system to also manage the programmatics associated with Systems Engineering activities of a project. On NASA’s Asteroid Redirect Robotic Mission, MBSE has been successfully employed to manage, generate, and interact with the documentation-based deliverables associated with System Engineering activities. This has been involved in defining and tracking project document, milestone, and personnel metadata via the same modeling framework used for the technical architecture management. Additionally, it has focused on improving overall user experiences through linkage of documentation to technical content in the system model, automation of manually intensive tasks, and others stakeholderoriented features.

Mozafari, Tanaz↗
NASA NTRS2018

Characterizing the Architectures, Diversity and Habitability of Nearby Planetary Systems: The HabEx Observatory

Ongoing research, upcoming developments in ground-based facilities, and the launch of new space missions (Transiting Exoplanet Survey Satellite [TESS], James Webb Space Telescope [JWST], and Wide Field Infrared Survey Telescope [WFIRST]) will continue to advance knowledge of the variety and nature of exoplanetary system components over the next decade and a half. However, many key questions will remain: What is the architecture and full diversity of mature planetary systems? What is the linkage between individual planet properties, planetary system architectures and circumstellar dust structures? How diverse are planetary atmospheres over the full range of planet sizes and stellar insulation levels? Are there Earth-sized planets orbiting in the habitable zone (HZ) of nearby sunlike stars, with water vapor in their atmospheres, evidence for surface oceans and signs of life? Are these signs of life really of biotic origin? Answering all of these questions requires direct imaging and spectroscopy from space in reflected light and/or thermal emission. We exclusively discuss reflected light (near ultraviolet [UV] to near infrared [IR]) investigations, identifying some of the observational, technological, and theoretical challenges that must be met to accomplish such a feat. This paper concentrates on one possible implementation strategy currently under study: the HabEx (Habitable Exoplanet) Observatory mission concept.

Mennesson, B.↗
NASA NTRS2018

The Habitable Exoplanet Observatory (HabEx): Science Goals and Projected Capabilities

Ongoing research, upcoming developments in ground-based facilities, and the launch of new space missions (Transiting Exoplanet Survey Satellite [TESS], James Webb Space Telescope [JWST], and Wide Field Infrared Survey Telescope [WFIRST]) will continue to advance knowledge of the variety and nature of exoplanetary system components over the next decade and a half. However, many key questions will remain: What is the architecture and full diversity of mature planetary systems? What is the linkage between individual planet properties, planetary system architectures, and circumstellar dust structures? How diverse are planetary atmospheres over the full range of planet sizes and stellar insulation levels? Are there Earth-sized planets orbiting in the habitable zone (HZ) of nearby sun-like stars, with water vapor in their atmospheres, evidence for surface oceans and signs of life? Are these really of biotic origin? Answering all of these questions requires direct imaging and spectroscopy from space in reflected light and/or thermal emission. We exclusively discuss reflected light (near ultraviolet [UV] to near infrared [IR]) investigations, identifying some of the observational, technological, and theoretical challenges that must be met to accomplish such a feat. This paper concentrates on one possible implementation strategy and mission concept currently under study: the HabEx (Habitable Exoplanet) Observatory.

Mennesson, Bertrand↗
NASA NTRSDate not supplied

Impact of a Regional Drought on Land and Atmospheric Carbon over the North America

The spatiotemporal extent of a regional drought’s impact on land-atmosphere carbon and their mechanistic linkages are still poorly understood. Allowing carbon-water-energy feedback in an ensemble of coupled land-atmosphere simulations, this study quantifies induced changes in meteorology and carbon caused by an idealized 3-month meteorological drought over to the lower Mississippi River Valley (~500,000 km2). The imposed drought leads to a 23% Gross Primary Production (GPP) reduction in the drought area and the GPP reductions in some remote areas that are adjacent to the imposed drought through the changes in remote meteorology, particularly by the induced precipitation. The effect of the meteorological anomalies on GPP is greater, by at least an order of magnitude, than that of the atmospheric CO2 anomalies. While the magnitude of induced CO2 anomalies near the land surface can be as large as 3.57ppm, the column-averaged CO2 increases up to 0.78ppm and thus is below the precision limit (~1ppm) of current greenhouse gas (GHG) observing satellites. Spatially, the CO2 anomalies cover an area up to three times of that of the imposed drought, which suggests that the atmospheric transport needs to be considered in the interpretation of carbon anomalies in the atmosphere.

Eunjee Lee↗
NASA NTRS2021

Supraglacial River Forcing of Subglacial Water Storage and Diurnal Ice Sheet Motion

Surface melting impacts ice sheet sliding by supplying water to the bed, but subglacial processes driving ice accelerations are complex. We examine linkages between surface runoff, transient subglacial water storage, and short-term ice motion from 168 consecutive hourly measurements of meltwater discharge (moulin input) and GPS-derived ice surface motion for Rio Behar, a ∼60 sq. km moulin-terminating supraglacial river catchment on the southwest Greenland Ice Sheet. Short-term accelerations in ice speed correlate strongly with lag-corrected measures of supraglacial river discharge (r = 0.9, τ = 0.7, p < 0.01). Though our 7 days record cannot address seasonal-scale forcing, diurnal ice accelerations align with normalized differenced supraglacial and proglacial discharge, a proxy for subglacial storage change, better than GPS-derived ice surface uplift. These observations counter theoretical steady state basal sliding laws and suggest that moulin and proglacially induced fluctuations in subglacial water storage, rather than absolute subglacial water storage, drive short-term ice accelerations.

Glacial↗
NASA NTRS2021

Micromechanics-based Modeling of Laminated SiC/SiC Ceramic Matrix Composites

The behavior and response of ceramic matrix composites (CMCs), in particular silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC), is affected by many factors such as variation of fiber volume fraction, residual stresses resulting from processing of the composites at high temperature, random microstructures, and the presence of matrix flaws (e.g., voids, pores, cracks etc.) as well as general material nonlinearity and heterogeneity that occurs randomly in a composite. Residual stresses arising from the phase change of constituents are evaluated in this paper and it is shown that they do influence composite strength and need to be properly accounted for. Additionally, the microstructures (location of fiber centers, coating thickness etc.) of advanced CMCs are usually disordered (or random) and fiber diameter and strength typically have a distribution. They rarely resemble the ordered fiber packing (square, rectangular, or hexagonal) that is generally assumed in micromechanics-based models with periodic boundary conditions for computational expediency. These issues raise the question of how should one model such systems effectively? Can an ordered hexagonal packed repeating unit cell (RUC) accurately represent the random microstructure behavior? How many fibers need to be included to enable accurate representation? Clearly, the number of fibers within an RUC must be limited to insure a balance between accuracy and efficiency. NASA’s in-house micromechanics-based code MAC/GMC provides a framework to analyze such RUCs for the overall composite behavior and the FEAMAC computer code provides linkage of MAC/GMC to the commercial FEA code, ABAQUS. The appropriate level of discretization of the RUC as well as the analysis method employed, i.e., Generalized Method of Cells (GMC) or High Fidelity Generalized Method of Cells (HFGMC), is investigated in this paper in the context of a unidirectional as well as a cross-ply laminated CMC. Results including effective composite properties, proportional limit stress (an important design parameter) and fatigue are shown utilizing both GMC as well as HFGMC. Finally, a few multiscale analyses are performed on smooth bar test coupons as well as test coupons with features such as open-hole and double notches using FEAMAC. Best practices and guidance are provided to take these phenomena into account and keep a proper balance between fidelity (accuracy) and efficiency. Following these guidelines can account for important physics of the problem and provide significant advantages when performing large multiscale composite structural analyses.

Ceramic Matrix Composites↗
NASA NTRS2022

4. Parallels in Communication and Navigation Technology and Natural Phenomenon

This chapter represents an introspective search for hidden connections between technology and nature and inadvertent influence on biomimicry – especially as it pertains to links to electromagnetics in navigation and communication systems. Several devices, phenomena, and approaches to problem solving are considered and an attempt is made to identify linkages between experiences, observables and the way we think about and create new technology.

Advanced Air Mobility↗
NASA NTRS2020

Global Airborne Sampling Reveals a Previously Unobserved Dimethyl Sulfide Oxidation Mechanism in the Marine Atmosphere

Dimethyl sulfide (DMS), emitted from the oceans, is the most abundant biological source of sulfur to the marine atmosphere. Atmospheric DMS is oxidized to condensable products that form secondary aerosols that affect Earth’s radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report the atmospheric discovery of a previously unquantified DMS oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), identified through global-scale airborne observations that demonstrate it to be a major reservoir of marine sulfur. Observationally constrained model results show that more than 30% of oceanic DMS emitted to the atmosphere forms HPMTF. Coincident particle measurements suggest a strong link between HPMTF concentration and new particle formation and growth. Analyses of these observations show that HPMTF chemistry must be included in atmospheric models to improve representation of key linkages between the biogeochemistry of the ocean, marine aerosol formation and growth, and their combined effects on climate.

DMS gas-phase oxidation product↗
NASA NTRSDate not supplied

Quasi-Wireless Capacitive Power Transfer with Secure Data Acquisition for Robotic Systems in Space Infrastructure

Space exploration is dependent on robotic systems that utilize end-effectors to collect samples, probe surfaces, and manipulate objects. These systems can rarely be designed to do all three, forcing engineers to make tradeoffs based on the mission parameters - i.e. should the robotic appendage have a claw, drill, or shovel, and which would be best suited for the mission? Additionally, as more industrial and government entities partake in space exploration, data protection is needed in transit and at rest. To address these challenges, we present a first-of-its- kind robotic linkage that has no wiring between the joints. Instead, quasi-wireless capacitive (QWiC) power transfer is used to send energy over the robot’s chassis without a return wire. This enables the system to be completely modular through the use of single-contact permanent magnet connections, allowing rapid alterations in joint kinematics and/or the changing of end-effectors. For collecting sensor data from the robotic arm and to send remote commands to it, we use a Supervisory Control and Data Acquisition (SCADA) system. Data transmission relies on MQTT and OPC UA communication protocols with encryption. The SCADA server logs and archives sensor data and provides the functionality for authorized users to send remote commands from SCADA client(s) to motors. A SCADA client can be any of the web browsers that connects to a server via a secure communication channel using SSL protocol. Furthermore, as an extra data protection mechanism, we inject noise to the sensor data traffic, which obfuscates the timing of sensor data packets and adds confusion about which data packet represents which motor.

wireless sensor networks↗