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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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269 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Finite-Volume Diffusion Schemes for Svard's Eulerian Governing Equations

This paper, contains discussion on the implementation of new diffusion schemes for Svard’s Eulerian flow (EF) governing equations. It contains an alpha-damping type scheme and a new hyperbolic Eulerian flow (HEF) discretization paralleling previous work on hyperbolic Navier-Stokes (HNS). It shows these equations have simplified hyperbolic discretizations due to the simplicity of the new stress tensor and compares these schemes to established Navier-Stokes (NS) discretizations to verify the predictive utilities of such diffusion schemes.

Computational Fluid Dynamics↗
NASA NTRS2024

Finite-Volume Diffusion Schemes for Svard's Eulerian Governing Equations

This paper, contains discussion on the implementation of new diffusion schemes for Svard’s Eulerian flow (EF) governing equations. It contains an alpha-damping type scheme and a new hyperbolic Eulerian flow (HEF) discretization paralleling previous work on hyperbolic Navier-Stokes (HNS). It shows these equations have simplified hyperbolic discretizations due to the simplicity of the new stress tensor and compares these schemes to established Navier-Stokes (NS) discretizations to verify the predictive utilities of such diffusion schemes.

Computational Fluid Dynamics↗
NASA NTRSDate not supplied

NASA Ames Flight Instrument Group - MARS Exploration Efforts Overview

The NASA Ames Flight Instrument Group (FIG) MARS development activities include Aeolus, an integrated multi-probe mission to observe surface and atmospheric forcing and general circulation of Mars; the Mars Sonic Anemometer (MSA), a sonic-based, in-situ wind measuring instrument and the Saltation Sensor to detect the critical wind stress threshold for sand motion, which is believed to be a key aspect of dust lifting at Mars. These efforts are readying the instruments to fly, and their measurements are regarded as data of high scientific priority for future flight missions. Each of these efforts focuses on addressing a measurement or capability considered critical within the Agency and traceable to the decadal survey and MEPAG Goals. As we elevate the Technology Readiness Level (TRL) of these instruments to 6 through rigorous environmental testing, and participate in forming mission concepts, we make them viable for inclusion in flight mission proposals. Below, we outline FIG's highest priority advancements for Mars exploration.

Mars↗
NASA NTRSDate not supplied

Insights and Observations From Operating A Laser Communication Terminal on the International Space Station (ISS)

The Integrated Laser Communication Relay Demonstration (LCRD) Low Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T) is the first user platform for NASA’s first laser communication relay, LCRD. ILLUMA-T is hosted on the International Space Station (ISS) as an external payload of the Japanese Experiment Module – Exposed Facility (JEM-EF) situated in slot 3. The LCRD payload is hosted on the STPSat-6 spacecraft, which orbits Earth in a geostationary orbit at position 112 W. The ILLUMA-T-to-LCRD system provides a bidirectional, space-to-ground laser communication relay link transferring data up to 1.2 Gbps utilizing two optical ground stations (OGS), OGS-1 in California and OGS-2 in Hawai’i. This paper describes lessons learned from operating the ILLUMA-T system and examines topics such as the end-to-end system availability, predictive versus actual ephemeris, acquisition adjustments, modem timing and handshaking, the terminal’s physical placement and accommodations, and experiment development, execution, and analysis. The authors of this paper operate both the LCRD and ILLUMA-T laser terminals on a daily basis including pass planning, procedure execution, acquisition analysis, and real-time terminal commanding and telemetry monitoring. LCRD is a joint project involving NASA Goddard Space Flight Center (GSFC), the California Institute of Technology Jet Propulsion Laboratory (JPL), and Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). The ILLUMA-T payload is managed by NASA GSFC in Greenbelt, Maryland whose partners include the ISS program office at NASA’s Johnson Space Center (JSC) in Houston, Texas; the Huntsville Operations Support Center (HOSC) at Marshall Space Flight Center (MSFC) in Huntsville, Alabama; the Glenn Research Center (GRC) in Cleveland, Ohio; and the MIT LL in Lexington, Massachusetts. ILLUMA-T is funded by the Space Communications and Navigation (SCaN) Program at NASA Headquarters in Washington, D.C.

Laser Communications↗
NASA NTRSDate not supplied

Experimental Results from Integrated LCRD Low-Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T) Program

The National Aeronautics and Space Administration’s (NASA) Integrated LCRD Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) payload was launched and installed on the International Space Station’s (ISS) Japanese Experiment Module - Exposed Facility (JEM-EF) in November 2023. ILLUMA-T was the first space-based user to communicate with NASA’s Laser Communications Relay Demonstration (LCRD) using free space optical communication to transfer data from the ISS at return rates to Earth of up to 1.244 Gbps and forward rates from Earth of up to 155 Mbps. A 6-month long Experiments Program on ILLUMA-T concluded in June 2024, after which the payload was removed from the ISS and is currently de-orbiting. The Experiments Program was carefully designed to understand and characterize the Pointing, Acquisition, and Track (PAT) process with the new Modular, Agile, Scalable Optical Terminal (MAScOT), optical modem performance, and end-to-end relay performance.

ISS↗
DOE OSTI2021

Deriving Simulation Parameters for Storage-Type Water Heaters Using Ratings Data Produced from the Uniform Energy Factor Test Procedure: Preprint

Building energy modeling (BEM) is commonly used to estimate the energy usage of residential buildings. Uses for BEM include calculating home energy ratings, demonstrating compliance with performance-based energy codes, and establishing whether designs meet voluntary program requirements, such as ENERGY STAR® qualified homes. BEM requires simulating subsystems within the building, including storage-type water heaters. To properly simulate the in-situ performance of residential storage water heaters, it is necessary to determine key water heater parameters, including the overall heat loss coefficient (UA) and conversion efficiency (?c) of the water heater, based on the rated efficiency of the water heater. The testing procedure and rating standard for residential water heaters have recently changed: the new rating standard provides a Uniform Energy Factor (UEF) rather than the Energy Factor (EF) used previously. This paper discusses how to derive the necessary model parameters from the ratings data produced from the latest test procedure.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Compositions and methods for making selenocysteine containing polypeptides

Non-naturally occurring tRNASec and methods of using them for recombinant expression of proteins engineered to include one or more selenocysteine residues are disclosed. The non-naturally occurring tRNASec can be used for recombinant manufacture of selenocysteine containing polypeptides encoded by mRNA without the requirement of an SECIS element. In some embodiments, selenocysteine containing polypeptides are manufactured by co-expressing a non-naturally occurring tRNASec a recombinant expression system, such as E. coli, with SerRS, EF-Tu, SelA, or PSTK and SepSecS, and an mRNA with at least one codon that recognizes the anticodon of the non-naturally occurring tRNASec.

Soll, Dieter↗
DOE OSTI2021

Structure Perception in 3D Point Clouds: Preprint

Understanding human perception is critical to the design of ef- fective visualizations. The relative benefits of using 2D versus 3D techniques for data visualization is a complex decision space, with varying levels of uncertainty and disagreement in both the liter- ature and in practice. This study aims to add easily reproducible, empirical evidence on the role of depth cues in perceiving structures or patterns in 3D point clouds. We describe a method to synthesize a 3D point cloud that contains a 3D structure, where 2D projec- tions of the data strongly resemble a Gaussian distribution. We performed a within-subjects structure identification study with 128 participants that compared scatterplot matrices (canonical 2D projections) and 3D scatterplots under three types of motion: rota- tion, xy-translation, and z-translation. We found that users could consistently identify three separate hidden structures under ro- tation, while those structures remained hidden in the scatterplot matrices and under translation. This work contributes a set of 3D point clouds that provide definitive examples of 3D patterns per- ceptible in 3D scatterplots under rotation but imperceptible in 2D scatterplots.

data analysis↗
DOE OSTI2021

Computational Fermi Level Engineering and Doping-Type Conversion of Ga2O3 Via Three-Step Processing

Ga2O3 is being actively explored for power electronics, and other applications due to its ultra- wide bandgap and low projected fabrication cost of high-quality crystals. N-type doping of Ga2O3 can be achieved and tuned, but p-type doping faces fundamental obstacles. Successful engineering of Ga2O3 based devices requires critical control of doping density, Fermi level position, providing opportunities for predictive process simulation. We use first-principles defect equilibrium calculations to simulate a 3-step growth- annealing-quench protocol for hydrogen assisted Mg doping in Ga2O3, taking into account the hydrogen- oxygen-water gas phase equilibrium. We predict type conversion to a net p-type regime following O-rich annealing after growth under reducing conditions in the presence of H2. We show that there is an optimal temperature that maximizes the net acceptor density during the equilibrium annealing step for a given Mg doping level. Quenching of non-equilibrium annealed samples then results in a Fermi level EF below mid-gap down to about EV +1.5 eV, creating a significant number of uncompensated neutral MgGa0 acceptors. This type converted Ga2O3 can create significant built-in field in a p-n junction with an adjoining n-type material and could enable vertical MOSFETs.

CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS,M↗
DOE OSTI2021

Computational Fermi Level Engineering and Doping-Type Conversion of Ga2O3 Via Three-Step Processing

Ga2O3 is being actively explored for power electronics, deep-ultraviolet optoelectronics, and other applications due to its ultra-wide bandgap and low projected fabrication cost of large-size and high-quality crystals. N-type doping of Ga2O3 can be achieved and tuned, but p-type doping faces fundamental obstacles due to deep character of acceptor levels and polaron transport of resulting holes. However, successful engineering of Ga2O3 based devices requires critical control of doping density, Fermi level position, and free carrier concentration, providing opportunities for predictive process simulation. We use first-principles defect theory and defect equilibrium calculations to simulate a 3-step growth-annealing-quench protocol for hydrogen assisted Mg doping in Ga2O3, taking into account the hydrogen-oxygen-water gas phase equilibrium. We predict type conversion to a net p-type regime following O-rich annealing after growth under reducing conditions in the presence of H2. This process is similar to the Mg acceptor activation by H removal in GaN. We show that there is an optimal temperature that maximizes the net acceptor density during the equilibrium annealing step for a given Mg doping level. Quenching of non-equilibrium annealed samples then results in a Fermi level EF below mid-gap down to about EV +1.5 eV, creating a significant number of uncompensated neutral MgGa0 acceptors. The resulting free hole concentration in quenched samples is very low (109 – 1012 cm-3) due to deep energy level of these Mg acceptors, but this type converted Ga2O3 material can create a significant built-in field in a p-n junction with an adjoining n-type material. Additionally, the electron concentration is greatly suppressed in such acceptor-doped Ga2O3, which could enable the use as a current blocking layer to fabricate normally-off (enhancement-mode) vertical Ga2O3 based metal-oxide-semiconductor field effect transistors (MOSFETs), and as a guard ring for edge termination in MOSFETs and Schottky barrier diodes (SBDs) with increased breakdown voltage.

CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS,M↗
DOE OSTI2022

Electrification Futures Study: Impact of Electric Vehicles on Bulk Power Systems

This presentation builds on work presented at IEW2019 on "Transportation Scenarios of Electric Technology Adoption and Power Consumption" by providing insights on the impact of demand-side electrification, and electric vehicles in particular, on electricity supply and bulk power systems. This talk summarizes some results from the multi-year and multi-stakeholder Electrification Futures Study (EFS) series of reports. In particular, this work leverages integrated demand and supply modelling of future energy systems to provide insights on system design and operations focusing on demand flexibility and integration of variable renewables.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
DOE OSTI2023

Compositions and methods for making selenocysteine containing polypeptides

Non-naturally occurring tRNA Sec and methods of using them for recombinant expression of proteins engineered to include one or more selenocysteine residues are disclosed. The non-naturally occurring tRNA Sec can be used for recombinant manufacture of selenocysteine containing polypeptides encoded by mRNA without the requirement of an SECIS element. In some embodiments, selenocysteine containing polypeptides are manufactured by co-expressing a non-naturally occurring tRNASec a recombinant expression system, such as E. coli, with SerRS, EF-Tu, SelA, or PSTK and SepSecS, and an mRNA with at least one codon that recognizes the anticodon of the non-naturally occurring tRNA Sec .

Soll, Dieter↗
DOE OSTI2024

Guided cold atom inertial sensors with membrane integrated photonics on atom trap integrated platforms

A guided cold-atom inertial sensor system comprises an atom trap integrated platform, a laser system, a magnetic field system, a control system, and a computing system. The laser system and magnetic field system are adapted to form a magneto-optical trap (MOT) about a suspended waveguide of the atom trap integrated platform made of membrane integrated photonics. After loading cold atoms from a MOT, the photonic atom trap integrated platform generates one-dimensional guided atoms with an evanescent field optical dipole trap (EF-ODT) along the optical waveguide to create guided atomic accelerometers/gyroscopes. Motion of atomic wavepackets in a superposition state is created along the guided atom geometry by way of state-dependent momentum kicks. The light-pulse sequence of guided atom interferometry splits, redirects, and recombines atomic wavepackets, which allows measurement of atom interference fringes sensitive to inertial forces via a probe laser.

Lee, Jongmin↗
DOE OSTI2025

Ca X ML: Chemistry‐informed machine learning explains mutual changes between protein conformations and calcium ions in calcium‐binding proteins using structural and topological features

Proteins' flexibility is a feature in communicating changes in cell signaling instigated by binding with secondary messengers, such as calcium ions, associated with the coordination of muscle contraction, neurotransmitter release, and gene expression. When binding with the disordered parts of a protein, calcium ions must balance their charge states with the shape of calcium-binding proteins and their versatile pool of partners depending on the circumstances they transmit. Accurately determining the ionic charges of those ions is essential for understanding their role in such processes. However, it is unclear whether the limited experimental data available can be effectively used to train models to accurately predict the charges of calcium-binding protein variants. Here, we developed a chemistry-informed, machine-learning algorithm that implements a game theoretic approach to explain the output of a machine-learning model without the prerequisite of an excessively large database for high-performance prediction of atomic charges. We used the ab initio electronic structure data representing calcium ions and the structures of the disordered segments of calcium-binding peptides with surrounding water molecules to train several explainable models. Network theory was used to extract the topological features of atomic interactions in the structurally complex data dictated by the coordination chemistry of a calcium ion, a potent indicator of its charge state in protein. Our design created a computational tool of Ca X ML, which provided a framework of explainable machine learning model to annotate ionic charges of calcium ions in calcium-binding proteins in response to the chemical changes in an environment. Our framework will provide new insights into protein design for engineering functionality based on the limited size of scientific data in a genome space.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Electrification Futures Study Supply-Side Scenarios Report Figure Data

The file includes the data for figures in the Electrification Futures Study Supply-Side Scenarios report. Additional information on the data can be found in the report: Murphy, Caitlin, Trieu Mai, Yinong Sun, Paige Jadun, Matteo Muratori, Brent Nelson, and Ryan Jones. 2021. Electrification Futures Study: Scenarios of Power System Evolution and Infrastructure Development for the United States. Golden, CO: National Renewable Energy Laboratory. NREL/TP-6A20-72330. https://www.nrel.gov/docs/fy21osti/72330.pdf.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2000

Regulation of RYR1 activity by Ca(2+) and calmodulin

The skeletal muscle calcium release channel (RYR1) is a Ca(2+)-binding protein that is regulated by another Ca(2+)-binding protein, calmodulin. The functional consequences of calmodulin's interaction with RYR1 are dependent on Ca(2+) concentration. At nanomolar Ca(2+) concentrations, calmodulin is an activator, but at micromolar Ca(2+) concentrations, calmodulin is an inhibitor of RYR1. This raises the question of whether the Ca(2+)-dependent effects of calmodulin on RYR1 function are due to Ca(2+) binding to calmodulin, RYR1, or both. To distinguish the effects of Ca(2+) binding to calmodulin from those of Ca(2+) binding to RYR1, a mutant calmodulin that cannot bind Ca(2+) was used to evaluate the effects of Ca(2+)-free calmodulin on Ca(2+)-bound RYR1. We demonstrate that Ca(2+)-free calmodulin enhances the affinity of RYR1 for Ca(2+) while Ca(2+) binding to calmodulin converts calmodulin from an activator to an inhibitor. Furthermore, Ca(2+) binding to RYR1 enhances its affinity for both Ca(2+)-free and Ca(2+)-bound calmodulin.

Non-NASA Center↗
NASA NTRS2004

Decoding Ca2+ signals in plants

Different input signals create their own characteristic Ca2+ fingerprints. These fingerprints are distinguished by frequency, amplitude, duration, and number of Ca2+ oscillations. Ca(2+)-binding proteins and protein kinases decode these complex Ca2+ fingerprints through conformational coupling and covalent modifications of proteins. This decoding of signals can lead to a physiological response with or without changes in gene expression. In plants, Ca(2+)-dependent protein kinases and Ca2+/calmodulin-dependent protein kinases are involved in decoding Ca2+ signals into phosphorylation signals. This review summarizes the elements of conformational coupling and molecular mechanisms of regulation of the two groups of protein kinases by Ca2+ and Ca2+/calmodulin in plants.

Non-NASA Center↗