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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Helioseismic Observations of the Structure and Dynamics of a Rotating Sunspot Beneath the Solar Surface

Time-distance helioseismology is applied to study the subphotospheric structures and dynamics of an unusually fast-rotating sunspot observed by the Michelson Doppler Imager on bead SOH0 in 2000 August. The subsurface sound speed structures and velocity fields are obtained for the sunspot region at different depths from 0 to 12 Mm. By comparing the subsurface sound speed variations with the surface magnetic field, we find evidence for structural twists beneath the visible surface of this active region, which may indicate that magnetic twists often seen at the photosphere also exist beneath the photosphere. We also report on the observation of subsurface horizontal vortical flows that extend to a depth of 5 Mm around this rotating sunspot and present evidence that opposite vortical flows may exist below 9 Mm. It is suggested that the vortical flows around this active region may build up a significant amount of magnetic helicity and energy to power solar eruptions. Monte Carlo simulation has been performed to estimate the error propagation, and in addition the sunspot umbra is masked to test the reliability of our inversion results. On the basis of the three-dimensional velocity fields obtained from the time-distance helioseismology inversions, we estimate the subsurface kinetic helicity at different depths for the first time and conclude that it is comparable to the current helicity estimated from vector magnetograms.

Zhao, Junwei↗
NASA NTRS2010

Carbon Isotope Characterization of Organic Intermediaries in Hydrothermal Hydrocarbon Synthesis by Pyrolysis-GC-MS-C-IRMS

We report results of experiments designed to characterize the carbon isotope composition of intermediate organic compounds produced as a result of mineral surface catalyzed reactions. The impetus for this work stems from recently reported detection of methane in the Martian atmosphere coupled with evidence showing extensive water-rock interaction during Martian history. Abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions may be one possible process responsible for methane generation on Mars, and measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible isotope measurements. Our isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-Combustion-Isotope Ratio Mass Specrometry (Py-GC-MS-C-IRMS). Others have conducted similar pyrolysis-IRMS experiments on low molecular weight organic acids (Dias, et al, Organic Geochemistry, 33 [2002]). Our technique differs in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of the organic compounds. A sample of carboxylic acid (mixture of C1 through C6) was pyrolyzed at 100 XC and passed through the GC-MS-C-IRMS (combusted at 940 XC). In order to test the reliability of our technique we compared the _13C composition of different molecular weight organic acids (from C1 through C6) extracted individually by the traditional sealed-tube cupric oxide combustion (940 XC) method with the _13C produced by our pyrolysis technique. Our data indicate that an average 4.3. +/-0.5. (V-PDB) apparent isotopic fractionation accompanies the pyrolysis extractions. We postulate that this isotope offset could be the result of incomplete thermal desorption during pyrolysis. We are continuing to investigate the reliability of this pyrolysis technique for correcting carbon isotope measurements of mineral surface catalyzed organic compounds.

Socki, Richard A.↗
NASA NTRS2011

Fast Simulations of Gas Sloshing and Cold Front Formation

We present a simplified and fast method for simulating minor mergers between galaxy clusters. Instead of following the evolution of the dark matter halos directly by the N-body method, we employ a rigid potential approximation for both clusters. The simulations are run in the rest frame of the more massive cluster and account for the resulting inertial accelerations in an optimised way. We test the reliability of this method for studies of minor merger induced gas sloshing by performing a one-to-one comparison between our simulations and hydro+N-body ones. We find that the rigid potential approximation reproduces the sloshing-related features well except for two artefacts: the temperature just outside the cold fronts is slightly over-predicted, and the outward motion of the cold fronts is delayed by typically 200 Myr. We discuss reasons for both artefacts.

Roediger, E.↗
NASA NTRS2012

Fast Simulations of Gas Sloshing and Cold Front Formation

We present a simplified and fast method for simulating minor mergers between galaxy clusters. Instead of following the evolution of the dark matter halos directly by the N-body method, we employ a rigid potential approximation for both clusters. The simulations are run in the rest frame of the more massive cluster and account for the resulting inertial accelerations in an optimised way. We test the reliability of this method for studies of minor merger induced gas sloshing by performing a one-to-one comparison between our simulations and hydro+N-body ones. We find that the rigid potential approximation reproduces the sloshing-related features well except for two artifacts: the temperature just outside the cold fronts is slightly over-predicted, and the outward motion of the cold fronts is delayed by typically 200 Myr. We discuss reasons for both artifacts.

Roediger, E.↗
NASA NTRS2016

A Modified Edge Crack Torsion Test for Measurement of Mode III Fracture Toughness of Laminated Tape Composites

Modifications to the edge crack torsion (ECT) test are studied to improve the reliability of this test for measuring the mode-III fracture toughness, G (sub IIIc), of laminated tape fiber-reinforced polymeric (FRP) composites. First, the data reduction methods currently used in the ECT test are evaluated and deficiencies in their accuracy are discussed. An alternative data reduction technique, which uses a polynomial form to represent ECT specimen compliance solution, is evaluated and compared to FEA (finite element analysis) results. Second, seven batches of ECT specimens are tested, each batch containing specimens with a preimplanted midplane edge delamination and midplane plies with orientations of plus theta divided by minus theta, with theta ranging from 0 degrees to 90 degrees in 15-degree increments. Tests on these specimens show that intralaminar cracking occurs in specimens from all batches except for which theta = 15 degrees and 30 degrees. Tests on specimens of these two batches are shown to result in mode-III delamination growth at the intended ply interface. The findings from this study are encouraging steps towards the use of the ECT test as a standardized method for measuring G (sub IIIc), although further modification to the data reduction method is required to make it suitable for use as part of a standardized test method.

Czabaj, Michael W.↗
NASA NTRS2016

Flat H Redundant Frangible Joint Development

Orion and Commercial Crew Program (CCP) Partners have chosen to use frangible joints for certain separation events. The joints currently available are zero failure tolerant and will be used in mission safety applications. The goal is to further develop a NASA designed redundant frangible joint that will lower flight risk and increase reliability. FY16 testing revealed a successful design in subscale straight test specimens that gained efficiency and supports Orion load requirements. Approach / Innovation A design constraint is that the redundant joint must fit within the current Orion architecture, without the need for additional vehicle modification. This limitation required a design that changed the orientation of the expanding tube assemblies (XTAs), by rotating them 90deg from the standard joint configuration. The change is not trivial and affects the fracture mechanism and structural load paths. To address these changes, the design incorporates cantilevered arms on the break plate. The shock transmission and expansion of the XTA applies force to these arms and creates a prying motion to push the plate walls outward to the point of structural failure at the notched section. The 2014 test design revealed that parts could slip during functioning wasting valuable energy needed to separate the structure with only a single XTA functioning. Dual XTA functioning fully separated the assembly showing a discrepancy can be backed up with redundancy. Work on other fully redundant systems outside NASA is limited to a few patents that have not been subjected to functionality testing Design changes to prevent unwanted slippage (with ICA funding in 2015) showed success with a single XTA. The main goal for FY 2016 was to send the new Flat H RFJ to WSTF where single XTA test failures occurred back in 2014. The plan was to gain efficiency in this design by separating the Flat H RFJ with thicker ligaments with dimensions baselined in 2014. Other modifications included geometry changes to better disperse loads paths and to minimize air gaps. The design additionally added more structural strength to enhance the structural limits in static loads testing. The design also implemented a smoother load line through the assembly. Results / Knowledge Gained The new Flat H RFJ successfully fractured at WSTF with thicker ligaments and lower cord size. Where failure to separate occurred earlier, there is now excessive energy available for structural separation. The new challenge to provide some structural support to prevent secondary fracturing of the break plate remains to be completed. This future work is being funded by the JSC Engineering Directorate in 2017 to elevate the TRL on curved Flat H RFJs that configure with the Orion Service Panel Separation. Additional funding from JSC Engineering will provide new design testing to avoid secondary fracturing.

Brown, Chris↗
NASA NTRS2017

Battery Data MI Importer Template Quick Start Guide

In order to ensure the persistent availability and reliability of test data generated over the course of the project, the M-SHELLS Project has decided to store acquired test data, as well as associated pedigree information, in the Granta Materials Intelligence (MI) database. To facilitate that effort, an importer template and associated graphical user interface (GUI) software have been developed, with this guide providing the operating instructions for their use. The template and automation software GUI are contained in the BatteryDataImporter.xlsm Excel workbook, and are to be used to import M-SHELLS summary, or pedigree, data and the associated raw test data results into an importer template-based file, formatted in such a way as to be ready for immediate upload to the Test Data: Battery Performance table of the Granta MI database. The provided GUI enables the user to select the appropriate summary data file(s), with each file containing the required information to identify any associated raw test data file(s) to be processed. In addition to describing the setup and operation of the importer template and GUI software, this guide also provides instructions for uploading processed data to the database and for viewing the data following upload.

Levinson, Laurie H.↗
NASA NTRS2017

A Year in the Life of the NASA Electronic Parts and Packaging (NEPP) Program

NEPP Mission Statement: Provide NASAs leadership for developing and maintaining guidance for the screening, qualification, test, and reliable usage of electrical, electronic, and electromechanical (EEE) parts by NASA, in collaboration with other government Agencies and industry.

NASA Electronic Parts and Packaging (NEPP) Program↗
NASA NTRS2018

A Single Thread to Fortran Coarray Transition Process for the Control Algorithm in the Space Radiation Code HZETRN

Exa-scale computing is the direction by industry and government are going to generate solutions to problems they deem necessary. Computing hardware is being developed to achieve the transition from Peta-scale to Exa-scale with more CPUs (Central Processing Units) that have more cores per CPU and more accelerators (GPGPUs (General Purpose Graphics Processing Units) and MICs (Many Integrated Cores)) per node. To fully utilize the hardware available now and in the future, algorithms must become multi-threaded. There are a few methods to generate multi-threaded software such as MPI (Message Passing Interface) and OpenMP (Multi-Processing) / OpenACC (ACCelerator). This paper concentrates on using Coarray Fortran to convert the Fortran 95 based HZETRN (High Z and Energy TRaNsport) code's control algorithm from a single threaded code to a multithreaded code. The resultant Coarray code was 32.5 times faster (with a theoretical speed-up of 74.5 times) than the single threaded version on the hardware tested, as reliable as the Fortran 95 version, and, as it uses native Fortran, was as maintainable as the Fortran 95 version. The Coarray code can be maintained by the same project engineers and scientists who created the original single threaded code. This transition process can be utilized on a C language based code with a compiler that has the UPC (Universal Parallel C) extensions to C.

Singleterry, Robert C., Jr.↗
NASA NTRS2019

NASA Electronic Parts and Packaging (NEPP) Program Focus, Strategic Collaborations, and Our Path to the Future

NASA Electronic Parts and Packaging (NEPP) Program Overview Mission Statement: Provide NASA's leadership for developing and maintaining guidance for the screening, qualification, test, and reliable use of EEE parts by NASA, in collaboration with other government agencies and industry. The NASA Electronic Parts Assurance Group (NEPAG) is a core portion of NEPP.

NASA Electronic Parts and Packaging (NEPP) Program↗