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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 91 records · Page 5

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NASA NTRS1974

Theory to test comparisons for selected aerospace multishell structures and their interfaces under thermomechanical loadings

Guidelines for structural shell analyses were obtained on the basis of theory-to-test comparisons made on two large-scale aerospace structures subject to thermomechanical loads. The first structural test was the cylindrical aluminum skin-stringer-ring construction of the S-IC forward skirt and S-II interstage. The second structural test included the truncated, cone-shaped, bonded honeycomb sandwich shell of the Spacecraft Lunar Module Adapter; the cylindrical bonded aluminum honeycomb sandwich construction of the Instrument Unit; and the skin-stringer construction with rings and intercostals of the S-IVB forward skirt. Analyses were made for loadings simulating the flight environment. Elementary shear lag theory was superimposed on shell analysis for interface junctions between stages to obtain favorable theory-to-test stress comparisons.

Ferdie, R. D.↗

DOE OSTI2024

Parasitic conduction loss of lithium niobate on insulator platform

Thin-film lithium niobate on insulator (LNOI) has recently emerged as an exciting platform for nonlinear integrated photonic devices, drawing parallels with the impact of silicon on insulator (SOI) in the electronic device realm. While the influence of interfacial states of SOI on electronic device performance, particularly their contribution to parasitic radio frequency (RF) losses, is well-documented, this aspect remains relatively unexplored in LNOI, despite their shared silicon/oxide interface structure. Here, we investigate the RF loss arising from mobile charges at the silicon/oxide interface of the LNOI platform. We show that this parasitic conduction can be exacerbated, especially during plasma etching, and leads to substantial RF losses. Through strategic incorporation of a trap-rich poly-silicon layer at this interface, we effectively eliminate this parasitic conduction, resulting in the suppression of RF losses. This work establishes crucial guidelines for harnessing LNOI in applications such as high-frequency electro-mechanical devices, high-speed electro-optic modulators, and high-efficiency microwave-to-optics converters.

Physics↗

NASA NTRS2012

Aquarius Main Structure Configuration

The Aquarius/SAC-D Observatory is a joint US-Argentine mission to map the salinity at the ocean surface. This information is critical to improving our understanding of two major components of Earth's climate system - the water cycle and ocean circulation. By measuring ocean salinity from space, the Aquarius/SAC-D Mission will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Aquarius is the primary instrument on the SAC-D spacecraft. It consists of a Passive Microwave Radiometer to detect the surface emission that is used to obtain salinity and an Active Scatterometer to measure the ocean waves that affect the precision of the salinity measurement. The Aquarius Primary Structure houses instrument electronics, feed assemblies, and supports a deployable boom with a 2.5 m Reflector, and provides the structural interface to the SAC-D Spacecraft. The key challenge for the Aquarius main structure configuration is to satisfy the needs of component accommodations, ensuring that the instrument can meet all operational, pointing, environmental, and launch vehicle requirements. This paper describes the evolution of the Aquarius main structure configuration, the challenges of balancing the conflicting requirements, and the major configuration driving decisions and compromises.

Eremenko, Alexander↗

DOE OSTI2025

Optimizing Grain Boundary Structures with LAMMPS Using Evolutionary Algorithms

Grain boundary structure optimization is an important part of materials modeling. Current methods for grain boundary structure optimization involve inefficient, time-consuming processes that do not fully explore the interface parameter space. Evolutionary algorithms have recently been demonstrated to be effective at determining both stable and metastable grain boundary interface structures. In this work, we demonstrate the use of GBOpt, a grain boundary structure optimization software designed to use the Large-scale Atomic/Molecular Massively Parallel Simulation (LAMMPS) software to efficiently determine grain boundary structures. We demonstrate that a only a few manipulations, namely atom insertion, atom removal, and relative grain displacement, are sufficient to explore much of the grain boundary structure parameter space. The efficacy of this approach is demonstrated on an FCC Ni system, and a BCC Fe system. The computational cost is compared against the gamma-surface sampling approach to demonstrate performance improvement.

Evolutionary algorithms↗

DOE OSTI2023

Ultrathin epitaxial MgB 2 on SiC: Substrate surface-polarity-dependent properties

High-quality, ultrathin superconducting films are required for advanced devices such as hot-electron bolometers, superconducting nanowire single-photon detectors, and quantum applications. Using hybrid physical-chemical vapor deposition, we show that MgB 2 films as thin as 4 nm can be fabricated on the carbon-terminated 6⁢H-SiC (0001) surface with a superconducting transition temperature above 33 K and a rms roughness of 0.7 nm. Remarkably, the film quality is a function of the SiC surface termination, with the C-terminated surface preferred to the Si-terminated surface. To understand the MgB 2 thin film/SiC substrate interactions giving rise to this difference, we characterized the interfacial structures using Rutherford backscattering spectroscopy/channeling, electron-energy-loss spectroscopy, and x-ray photoemission spectroscopy. The MgB 2 /SiC interface structure is complex and different for the two terminations. Both terminations incorporate substantial unintentional oxide layers influencing MgB 2 growth and morphology, but with a different extent, intermixing, and interface chemistry. In this paper, we report measurements of transport, resistivity, and the critical superconducting temperature of MgB 2 /SiC that are different for the two terminations, and they link interfacial structure variations to observed differences. The result shows that the C face of SiC is a preferred substrate for the deposition of ultrathin superconducting MgB 2 films.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Equipment Testing Environment (ETE) Process Specification

This document is intended to be utilized with the Equipment Test Environment being developed to provide a standard process by which the ETE can be validated. The ETE is developed with the intent of establishing cyber intrusion, data collection and through automation provide objective goals that provide repeatability. This testing process is being developed to interface with the Technical Area V physical protection system. The document will overview the testing structure, interfaces, device and network logging and data capture. Additionally, it will cover the testing procedure, criteria and constraints necessary to properly capture data and logs and record them for experimental data capture and analysis.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2023

Plasma-assisted deposition and characterization of Al 2 O 3 dielectric layers on (001) β -Ga 2 O 3

In this work, we have investigated plasma-assisted deposition of Al 2 O 3 on HVPE (001) β-Ga 2 O 3 and evaluated the dielectric quality from electrical measurements on fabricated metal-oxide-semiconductor (MOS) capacitors. The interface structure and crystallinity of the films were investigated as a function of the growth temperature. The dielectric/semiconductor interfaces were found to have reverse breakdown electric fields up to 5.3 MV/cm in the β-Ga 2 O 3 , with relatively low hysteresis in capacitance–voltage and low leakage current. We determined a negative fixed interface charge density at the interface from analysis of thickness-dependent capacitance voltage data. In conclusion, this study shows the advantage of using plasma-assisted deposition to achieve high breakdown strength Al 2 O 3 /β-Ga 2 O 3 MOS structures for device application purposes.

42 ENGINEERING↗

NASA NTRS1988

Scanning Tunneling Microscopy methods for spectroscopic imaging of subsurface interfaces

A new method for spatially-resolved, spectroscopic investigation of subsurface interface structure has been developed. The method, Ballistic Electron Emission Microscopy (BEEM), is based on Scanning Tunneling Microscopy (STM) techniques. BEEM combines STM vacuum tunneling with unique ballistic electron spectroscopy capabilities. BEEM enables, for the first time, direct imaging of subsurface interface electronic properties with nanometer spatial resolution. STM topographic images of surface structure and BEEM images of subsurface properties are obtained simultaneously. BEEM capabilities are demonstrated by investigation of important metal-semiconductor interfaces.

Bell, L. D.↗

NASA NTRS1982

Development of deployable structures for large space platform systems, part 1

Eight deployable platform design objectives were established: autodeploy/retract; fully integrated utilities; configuration variability; versatile payload and subsystem interfaces; structural and packing efficiency; 1986 technology readiness; minimum EVA/RMS; and Shuttle operational compatibility.

Cox, R. L.↗

NASA NTRS1985

A computer analysis program for interfacing thermal and structural codes

A software package has been developed to transfer three-dimensional transient thermal information accurately, efficiently, and automatically from a heat transfer analysis code to a structural analysis code. The code is called three-dimensional TRansfer ANalysis Code to Interface Thermal and Structural codes, or 3D TRANCITS. TRANCITS has the capability to couple finite difference and finite element heat transfer analysis codes to linear and nonlinear finite element structural analysis codes. TRANCITS currently supports the output of SINDA and MARC heat transfer codes directly. It will also format the thermal data output directly so that it is compatible with the input requirements of the NASTRAN and MARC structural analysis codes. Other thermal and structural codes can be interfaced using the transfer module with the neutral heat transfer input file and the neutral temperature output file. The transfer module can handle different elemental mesh densities for the heat transfer analysis and the structural analysis.

Thompson, R. L.↗

NASA NTRS1985

A computer analysis program for interfacing thermal and structural codes

Thompson, R. L.↗

DOE OSTI2020

In Situ Phosphatizing of Triphenylphosphine Encapsulated within Metal–Organic Frameworks to Design Atomic Co 1 –P 1 N 3 Interfacial Structure for Promoting Catalytic Performance

The engineering coordination environment offers great opportunity in performance tunability of isolated metal single-atom catalysts. For the most popular metal–N x (MN x ) structure, the replacement of N atoms by some other atoms with relatively weak electronegativity has been regarded as a promising strategy for optimizing the coordination environment of an active metal center and promoting its catalytic performance, which is still a challenge. Herein, we proposed a new synthetic strategy of an in situ phosphatizing of triphenylphosphine encapsulated within metal–organic frameworks for designing atomic Co 1 –P 1 N 3 interfacial structure, where a cobalt single atom is costabilized by one P atom and three N atoms (denoted as Co-SA/P-in situ). In the acidic media, the Co-SA/P-in situ catalyst with Co 1 –P 1 N 3 interfacial structure exhibits excellent activity and durability for the hydrogen evolution reaction (HER) with a low overpotential of 98 mV at 10 mA cm –2 and a small Tafel slope of 47 mV dec –1 , which are greatly superior to those of catalyst with Co 1 –N 4 interfacial structure. We discover that the bond-length-extended high-valence Co 1 –P 1 N 3 atomic interface structure plays a crucial role in boosting the HER performance, which is supported by in situ X-ray absorption fine structure (XAFS) measurements and density functional theory (DFT) calculation. With this work, we hope to promote the development of high performance metal single-atom catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

A plausible method of preparing the ideal p-n junction interface of a thermoelectric material by surface doping

Recent advances in two-dimensional (2D) crystals make it possible to realize an ideal interface structure that is required for device applications. Specifically, a p-n junction made of 2D crystals is predicted to exhibit an atomically well-defined interface that will lead to high device performance. Using angle-resolved photoemission spectroscopy, a simple surface treatment was shown to allow the possible formation of such an interface. Furthermore, Ta adsorption on the surface of a p-doped SnSe shifts the valence band maximum towards the higher binding energy due to the charge transfer from Ta to SnSe that is highly localized at the surface due to the layered structure of SnSe. As a result, the charge carriers of the surface are changed from holes of its bulk characteristics to electrons, while the bulk remains as a p-type semiconductor. This observation suggests that the well-defined interface of a p-n junction with an atomically thin n-region is formed between Ta-adsorbed surface and bulk.

36 MATERIALS SCIENCE↗

NASA NTRS1993

Aircraft empennage structural detail design

This project involved the detailed design of the aft fuselage and empennage structure, vertical stabilizer, rudder, horizontal stabilizer, and elevator for the Triton primary flight trainer. The main design goals under consideration were to illustrate the integration of the control systems devices used in the tail surfaces and their necessary structural supports as well as the elevator trim, navigational lighting system, electrical systems, tail-located ground tie, and fuselage/cabin interface structure. Accommodations for maintenance, lubrication, adjustment, and repairability were devised. Weight, fabrication, and (sub)assembly goals were addressed. All designs were in accordance with the FAR Part 23 stipulations for a normal category aircraft.

Meholic, Greg↗

NASA NTRS1994

SEQ-POINTER: Next generation, planetary spacecraft remote sensing science observation design tool

Since Mariner, NASA-JPL planetary missions have been supported by ground software to plan and design remote sensing science observations. The software used by the science and sequence designers to plan and design observations has evolved with mission and technological advances. The original program, PEGASIS (Mariners 4, 6, and 7), was re-engineered as POGASIS (Mariner 9, Viking, and Mariner 10), and again later as POINTER (Voyager and Galileo). Each of these programs were developed under technological, political, and fiscal constraints which limited their adaptability to other missions and spacecraft designs. Implementation of a multi-mission tool, SEQ POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions as they were being adapted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required. The current and planned capabilities of the tool will be discussed. The presentation will also include a 5-10 minute video presentation demonstrating the capabilities of a proto-Cassini Project version that was adapted to test the tool. The work described in this abstract was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

Boyer, Jeffrey S.↗

NASA NTRS2017

Vented Launch Vehicle Adaptor for a Manned Spacecraft with "Pusher" Launch Abort System

A system, method, and apparatus for a vented launch vehicle adaptor (LVA) for a manned spacecraft with a "pusher" launch abort system are disclosed. The disclosed LVA provides a structural interface between a commercial crew vehicle (CCV) crew module/service module (CM/SM) spacecraft and an expendable launch vehicle. The LVA provides structural attachment of the module to the launch vehicle. It also provides a means to control the exhaust plume from a pusher-type launch abort system that is integrated into the module. In case of an on-pad or ascent abort, which requires the module to jettison away from the launch vehicle, the launch abort system exhaust plume must be safely directed away from critical and dangerous portions of the launch vehicle in order to achieve a safe and successful jettison.

Vandervort, Robert E.↗

NASA NTRS1994

(abstract) SEQ_POINTER: Next Generation, Planetary Spacecraft Remote Sensing Science Observation Design Tool

Implementation of a multimission tool, SEQ_POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions when being adopted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ_POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required.

remote↗

DOE OSTI2024

Electronic conductivity in metal-graphene composites: the role of disordered carbon structures, defects, and impurities

Abstract This paper explores the transport properties of aluminum-carbon composite material via ab initio methods. Interfacial and electronic dynamics of the aluminum-graphene interface structure were investigated using models of amorphous graphene added to an aluminum matrix. We examine the impact on electronic conduction caused by the presence of nitrogen impurities within the interfacial amorphous graphene layer. We elucidate the conduction mechanisms by using a projection of the electronic conductivity into space.

36 MATERIALS SCIENCE↗