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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Systems and Methods for Transmitting Data Using Parallel Decode Capacity Optimized Symbol Constellations

Transmitters are described that use non-uniformly spaced symbol constellations that have increased capacity compared to conventional constellations. In many embodiments, a transmitter includes a coder configured to receive bits and output encoded bits, a mapper configured to map said encoded bits to symbols in a non-uniform symbol constellation selected from a plurality of symbol constellations, and a modulator configured to generate a signal for transmission via the communication channel using symbols generated by the mapper. In a variety of embodiments, wherein the non-uniform symbol constellation comprises a set of non-uniformly spaced constellation points, and the location points in the non-uniform symbol constellation are chosen to optimize parallel decode capacity of the non-uniform symbol constellation subject to at least one optimization constraint. In many embodiments, the non-uniform symbol constellation is a quadrature amplitude modulation constellation or a phase shift keyed constellation.

Barsoum, Maged F.↗
NASA NTRS2018

PA51C-0786 Informing NASA's Indigenous Peoples Capacity Building Pilot Project Through Collaborative Storytelling and Systems Mapping

NASA's Capacity Building Program (CBP) aims to empower communities to use NASA Earth Observations for environmental decision-making. A new project, the Indigenous Peoples Pilot Project, focuses on building relationships across NASA and indigenous communities through remote sensing training, community engagement, and research opportunities. A recent workshop, held on the lands of the Red Cliff Band of Lake Superior Chippewa in Wisconsin, focused on understanding indigenous knowledge systems and comparisons with western science, and more specifically, NASA Earth Science. In order to meet the workshop goals, North American tribal members and NASA managers participated in storytelling and systems mapping. The storytelling portion focused on personal narratives to understand the barriers, challenges, and pathways to incite change in the context of western scientists working with tribal nations. This was based on the traditional model of oral history and allowed participants to share their unique experiences of failures and successes. The systems mapping portion of the workshop focused on finding leverage points within the "NASA Ecosystem" for creating sustained instrumental change. This included (1) dedicating time and resources to explore how to recognize western science and indigenous knowledge as equal, (2) supporting innovation in communication and knowledge system frameworks, and (3) identifying new partners, allies, and champions for the western science/indigenous relationship. These leverage points were then used to generate recommendations for NASA which included (1) an awareness phase (for NASA and for indigenous communities) for NASA/Indigenous work, (2) creating a cultural immersion for NASA managers, (3) developing a protocol for working with indigenous groups, (4) creating a NASA tribal liaison office, (5) acknowledging and accepting indigenous knowledge systems in funding solicitations and proposals, and (6) incorporation of indigenous knowledge into capacity building activities.

Mccullum, Amber Jean Kuss↗
NASA NTRS2019

Diverse Photosynthetic Capacity of Global Ecosystems Mapped by Satellite Chlorophyll Fluorescence Measurements

Photosynthetic capacity is often quantified by the Rubisco-limited photosynthetic capacity (i.e. maximum carboxylation rate, V(sub cmax)). It is a key plant functional trait that is widely used in Earth System Models for simulation of the global carbon and water cycles. Measuring V(sub cmax) is time-consuming and laborious; therefore, the spatiotemporal distribution of V(sub cmax) is still poorly understood due to limited measurements of V(sub cmax). In this study, we used a data assimilation approach to map the spatial variation of V(sub cmax) for global terrestrial ecosystems from a 11-year-long satellite-observed solar-induced chlorophyll fluorescence (SIF) record. In this SIF-derived V(sub cmax) map, the mean V(sub cmax) value for each plant function type (PFT) is found to be comparable to a widely used N-derived V(sub cmax) dataset by Kattge et al. (2009). The gradient of V(sub cmax) along PFTs is clearly revealed even without land cover information as an input. Large seasonal and spatial variations of V(sub cmax) are found within each PFT, especially for diverse crop rotation systems. The distribution of major crop belts, characterized with high V(sub cmax) values, is highlighted in this V(sub cmax) map. Legume plants are characterized with high V(sub cmax) values. This V(sub cmax) map also clearly illustrates the emerging soybean revolution in South America where V(sub cmax) is the highest among the world. The gradient of V(sub cmax) in Amazon is found to follow the transition of soil types with different soil N and P contents. This study suggests that satellite-observed SIF is powerful in deriving the important plant functional trait, i.e. V(sub cmax), for global climate change studies.

Liming He↗
NASA NTRS2020

Constraining Remote Oxidation Capacity with ATom Observations

The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July–August 2016 and January–February 2017 to evaluate the oxidation capacity over the remote oceans and its representation in the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NOy concentrations, ozone photolysis frequencies) also show minimal bias with the exception of wintertime NOy, for which a model overestimate may indicate insufficient wet scavenging and/or missing loss on seasalt aerosol but large uncertainties remain that require further studies of NOy partitioning and removal in the troposphere. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by new estimates of ocean VOC sources and additional modeled reactivity in this region would be difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOC, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in modeled acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean VOC sources in the model increases annual surface cOHRmod by 10 % and improves model-measurement agreement for acetaldehyde particularly in winter but cannot resolve the model summertime bias. Doing so would require a 100 Tg yr−1 source of a long-lived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land.

Travis, Katherine R.↗
NASA NTRS2021

ATHLETE Offloader Limb as a High-capacity Crane

A new concept for the NASA Jet Propulsion Laboratory (JPL) All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) robotic constructor / mobility system employs tendon-driven actuation of individual limbs, similar to high-capacity cranes in terrestrial work environments. While maintaining mechanical joints that allow each limb to function as a highly dexterous multi-Degree-Of-Freedom (DOF) robotic arm, tendon-driven truss sections increase the capacity of moment loads for extended configurations of the limb. This paper describes the analysis, work cell, operations, actuation, control, and instrumentation of limbs designed to address specific target load cases that might be required for human exploration missions on planetary surfaces.

Wilcox, Brian H.↗
NASA NTRS2021

ATHLETE Offloader Limb as a High-capacity Crane

A new concept for the NASA Jet Propulsion Laboratory (JPL) All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) robotic constructor / mobility system employs tendon-driven actuation of individual limbs, similar to high-capacity cranes in terrestrial work environments, that can offload cargo from tall landers. While maintaining mechanical joints that allow each limb to function as a highly dexterous multi-Degree-Of-Freedom (DOF) robotic arm, tendon-driven truss sections increase the capacity of moment loads for extended configurations of the limb. The tendon-driven crane-like limb will be capable of offloading cargo from tall landers such as the SpaceX Starship. This paper describes the structural analysis, operations, calibration, and actuation of limbs designed to address specific target load cases that might be required for human exploration missions on planetary surfaces.

Wilcox, Brian↗
NASA NTRS2023

Analysis of VFR Traffic Uncertainty and its Impact on Uncrewed Aircraft Operational Capacity at Regional Airports

This paper proposes a method to characterize Visual Flight Rules traffic around a regional airport. The applicability of the method is discussed in the context of Uncrewed Aircraft operations at a regional airport. The relation between traffic interaction uncertainty and operational capacity at the runway is also investigated. The spatio-temporal distribution of traffic operating under Visual Flight Rules is analyzed from historical track data and visualized as heat maps generated at different altitudes. These are used to characterize the spatio-temporal uncertainty associated with traffic density, around a given airport, down to the runway. The traffic patterns at the runway are used to compute the runway capacity as a function of the probability of interaction with traffic operating under visual flight rules. Fort Worth Alliance is used as a representative regional airport for the study. Applications of the traffic characterization methods developed in this paper are also discussed.

VFR traffic, uncertainty, air mobility↗
NASA NTRS2023

Analysis of VFR Traffic Uncertainty and its Impact on Uncrewed Aircraft Operational Capacity at Regional Airports

This paper proposes a method to characterize Visual Flight Rules traffic around a regional airport. The applicability of the method is discussed in the context of Uncrewed Aircraft operations at a regional airport. The relation between traffic interaction uncertainty and operational capacity at the runway is also investigated. The spatio-temporal distribution of traffic operating under Visual Flight Rules is analyzed from historical track data and visualized as heat maps generated at different altitudes. These are used to characterize the spatio-temporal uncertainty associated with traffic density, around a given airport, down to the runway. The traffic patterns at the runway are used to compute the runway capacity as a function of the probability of interaction with traffic operating under visual flight rules. Fort Worth Alliance is used as a representative regional airport for the study. Applications of the traffic characterization methods developed in this paper are also discussed.

VFR traffic↗
NASA NTRSDate not supplied

Analysis of Electrical Grid Capacity in Major U.S. Metropolitan Areas for Urban Air Mobility

A wide range of challenges must be overcome to conduct Urban Air Mobility (UAM) operations at scale with electric vertical takeoff and landing aircraft as envisioned. This paper documents an analysis of one potential infrastructure challenge for UAM: available electrical grid power capacity. The success of UAM depends on the availability of electricity, which will be increasingly impacted by the proliferation of ground electric vehicles (EVs) over time. Under the worst-case assumption that each U.S. Metropolitan Statistical Area (MSA) can only access and utilize the electricity generated by power plants within its boundaries, it is estimated that the maximum number of UAM aircraft that can charge simultaneously in the 25 most populous MSAs will decrease by about 61% from about 129,000 in the year 2021 to about 51,000 in the year 2050, due to the projected increase in ground EVs. Also, it is estimated that the number of these MSAs that may lack any available electrical grid power capacity for UAM operations will increase from zero MSAs in 2021 to eleven MSAs in 2050—including three MSAs that prospective UAM operators have announced as target markets (Los Angeles, Miami, and Orlando)—unless electricity demand for other purposes is reduced.

electrical grid↗
NASA NTRSDate not supplied

Analysis of Electrical Grid Capacity in Major U.S. Metropolitan Areas for Urban Air Mobility

A wide range of challenges must be overcome to conduct Urban Air Mobility (UAM) operations at scale with electric vertical takeoff and landing aircraft as envisioned. This paper documents an analysis of one potential infrastructure challenge for UAM: available electrical grid power capacity. The success of UAM depends on the availability of electricity, which will be increasingly impacted by the proliferation of ground electric vehicles (EVs) over time. Under the worst-case assumption that each U.S. Metropolitan Statistical Area (MSA) can only access and utilize the electricity generated by power plants within its boundaries, it is estimated that the maximum number of UAM aircraft that can charge simultaneously in the 25 most populous MSAs will decrease by about 61% from about 129,000 in the year 2021 to about 51,000 in the year 2050, due to the projected increase in ground EVs. Also, it is estimated that the number of these MSAs that may lack any available electrical grid power capacity for UAM operations will increase from zero MSAs in 2021 to eleven MSAs in 2050—including three MSAs that prospective UAM operators have announced as target markets (Los Angeles, Miami, and Orlando)—unless electricity demand for other purposes is reduced.

electrical grid↗
NASA NTRSDate not supplied

NASA MUREP-DEAP Institutes - Year 1 Updates on Capacity Building, Community Building and Research Initiatives

Through the Minority University Research and Education Project (MUREP), NASA engages underrepresented populations via various initiatives, including by means of three year competitive awards for Data Science Equity, Access, and Priority in Research and Education (DEAP) Institutes led by Historically Black Colleges and Universities (HBCUs). MUREP DEAP Institutes, multi-institutional consortia, conduct data science research and capacity building initiatives that aim to enhance the research, academic, and technological capabilities of the participating HBCUs while providing NASA-specific knowledge, skills and opportunities for students and faculty who have historically been underrepresented and underserved in the STEM workforce. Three MUREP DEAP Institutes, led by Bethune-Cookman University, North Carolina A&T University, and North Carolina Central University, are conducting data science and natural hazard related research utilizing remote sensing and earth observations, with mentorship for the Institutes provided by scientists from NASA’s Marshall Space Flight Center. Each Institute has unique capabilities, needs, and goals, but overlap in their common interest to conduct cutting edge data science and natural hazard related research and to build capacity, broaden participation, and increase retention of a diverse group of participating students and faculty​. Here, successes and challenges from the first year of activities at each MUREP DEAP institute are discussed, where activities focused primarily on the recruitment of a diverse group of students and the upskilling of students and faculty in data science and remote sensing concepts. The planned activities and goals of each DEAP Institute for the upcoming two years of activities will also be discussed, both from research and community-building perspectives.

Ronan Lucey↗