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At least 811 records · Page 45

Modeling Materials: Design for Planetary Entry, Electric Aircraft, and Beyond

NASA missions push the limits of what is possible. The development of high-performance materials must keep pace with the agency's demanding, cutting-edge applications. Researchers at NASA's Ames Research Center are performing multiscale computational modeling to accelerate development times and further the design of next-generation aerospace materials. Multiscale modeling combines several computationally intensive techniques ranging from the atomic level to the macroscale, passing output from one level as input to the next level. These methods are applicable to a wide variety of materials systems. For example: (a) Ultra-high-temperature ceramics for hypersonic aircraft-we utilized the full range of multiscale modeling to characterize thermal protection materials for faster, safer air- and spacecraft, (b) Planetary entry heat shields for space vehicles-we computed thermal and mechanical properties of ablative composites by combining several methods, from atomistic simulations to macroscale computations, (c) Advanced batteries for electric aircraft-we performed large-scale molecular dynamics simulations of advanced electrolytes for ultra-high-energy capacity batteries to enable long-distance electric aircraft service; and (d) Shape-memory alloys for high-efficiency aircraft-we used high-fidelity electronic structure calculations to determine phase diagrams in shape-memory transformations. Advances in high-performance computing have been critical to the development of multiscale materials modeling. We used nearly one million processor hours on NASA's Pleiades supercomputer to characterize electrolytes with a fidelity that would be otherwise impossible. For this and other projects, Pleiades enables us to push the physics and accuracy of our calculations to new levels.

Supercomputing↗

The Kepler Science Data Processing Pipeline Source Code Road Map

We give an overview of the operational concepts and architecture of the Kepler Science Processing Pipeline. Designed, developed, operated, and maintained by the Kepler Science Operations Center (SOC) at NASA Ames Research Center, the Science Processing Pipeline is a central element of the Kepler Ground Data System. The SOC consists of an office at Ames Research Center, software development and operations departments, and a data center which hosts the computers required to perform data analysis. The SOC's charter is to analyze stellar photometric data from the Kepler spacecraft and report results to the Kepler Science Office for further analysis. We describe how this is accomplished via the Kepler Science Processing Pipeline, including, the software algorithms. We present the high-performance, parallel computing software modules of the pipeline that perform transit photometry, pixel-level calibration, systematic error correction, attitude determination, stellar target management, and instrument characterization.

Kepler pipeline software↗

Exploring the Evolutionary Accident Hypothesis: Are Extant Protein Folds the Fittest or the Luckiest?

Considering the range of functions proteins perform, it is surprising they fold into a relatively small set of structures or "folds" that facilitate such function. One explanation is that only a minority were fit enough to emerge from Darwinian selection during the early evolution of life. Alternatively, perhaps only a fraction of all possible folds were trialed. Understanding proto-catalyst selection will aid understanding of the origins and early evolution of life. To investigate which explanation is correct, we study a protein evolved in vitro to bind ATP by Jack Szostak (Fig. 1). This protein adopts a fold which is absent from nature. We are testing whether this fold would have possessed the capability to evolve that would have been essential to survive natural selection on early Earth. Folds that couldn't improve their fitness and evolve to perform new functions would have been replaced by rivals that could. To determine whether the fold is evolvable, we are attempting to change the function of the protein by rationally redesigning to bind GTP. Two design strategies in the region of the nucleobase have been implemented to provide hydrogen bonding partners for the ligand i) an insertion ii) a MET to ASN mutation. Redesigns are being studied computationally at Ames Research Center including free energy of binding calculations. Binding affinities of promising redesigns are to be validated by experimental collaborators at ForteBio using Super Streptavidin Biosensors. If the fold is found to be non-evolvable, this may suggest that many structures were trialed, but the majority were pruned on the basis of their evolvability. Alternatively, if the fold is demonstrated to be evolvable, it would be difficult to explain its absence from nature without considering the possibility that the fold simply wasn't sampled on early Earth. This would not only further our understanding of the origins of life on Earth but also suggest a common phe-nomenon of proto-catalyst evolution.

Shannon, G.↗

Design and Characterization of a New Nozzle in a NASA Arc-Jet

The design of a new 76 mm (3 inch) nozzle of the Interaction Heating Facility arc jet at NASA Ames Research Center is described. The computational efforts which were an integral part of the preliminary design and characterization of the nozzle are described as well. Details of heat flux measurements made in this new nozzle are provided. Apart from showing the flow characteristics of the nozzle, predictions of stagnation point heat flux are compared against measurements made with a nullpoint calorimeter; the agreement between computation and measurement is found to be good. Unfortunately, pressure measurements could not be made in the first round. The predicted stagnation point pressures and heat fluxes, with appropriate scaling for a 25 mm (1 inch) diameter iso-q geometry (reference geometry), are used to establish a provisional operating envelope for the new nozzle. The envelope is shown to enclose relevant heating portions of representative atmospheric trajectories at Venus and Saturn.

Arcjet↗

Material Response Analysis of a Titan Entry Heatshield

Accurate calculation of thermal protection material response is critical to the vehicle design for missions to the Saturn moon Titan. In this study, Icarus, a three-dimensional, unstructured, finite-volume material response solver under active development at NASA Ames Research Center, is used to compute the in-depth material response of the Huygens spacecraft along its November 11 entry trajectory. The heatshield analyzed in this study consists of a five-layer stack-up of Phenolic Impregnated Carbon Ablator (PICA), aluminum honeycomb, adhesive, and face sheetmaterials. During planetary entry, the PICA outer layer is expected to undergo pyrolysis. A surface energy balance boundary condition that captures both time- and spatial-variance of surface properties during entry is used in the simulation.

material response↗

Edge Based Viscous Method for Node-Centered Formulations

This paper presents a novel, efficient, conservative, edge-based method for evaluation of mean flow viscous fluxes and turbulence-model diffusion terms of the Reynolds-averaged Navier-Stokes equations on tetrahedral grids. The new method is implemented in a practical, node-centered, finite-volume computational fluid dynamics solver. The baseline finite-volume scheme that is equivalent to a second-order accurate finite-element Galerkin approximation of viscous stresses is reformulated. The order of operations to compute the cell-based Green-Gauss gradients is changed to combine the operations by edge, which leads to an equivalent formulation on tetrahedral grids, improves efficiency, and preserves the compact discretization stencil based on the nearest neighbors. The computational results presented in this paper verify the implementation of this edge-based method by comparing its accuracy and iterative convergence with those of the well verified and validated baseline formulation. Efficiency gains for residual and Jacobian evaluations result in significant reduction of time to solution. This novel edge-based formulation on tetrahedra can be seamlessly combined with the baseline formulation on cells of other types for computing solutions on mixed-element grids.

Edge Based↗

Transforming Energy through Computational Science: Computing for Clean Energy

This fact sheet discusses the opportunity space for NREL's computational science capabilities to address national clean energy objectives. Achieving a carbon-free power sector by 2035 as a step towards a decarbonized U.S. energy economy in 2050 will require major advances in power generation, autonomous energy systems, transportation, and buildings/communities. Development of integrated modeling approaches for complex energy systems will be essential for deployment. Success requires developments in optimization and control theory, complemented by machine learning (ML) and artificial intelligence (AI), all of which in turn need targeted investments in breadth and scale of computing. This document defines an opportunity space where: embracing computing can link established research and development (R&D) to a decarbonization agenda; pursuing emerging approaches can accelerate the pace of technology advancement across the portfolio; and leading by example could reduce the carbon footprint of computing worldwide.

advanced computing↗

Klipper Firmware Tools

Tools for building containers to ease building Klipper and CanBoot for multiple targets. Note: This is being submitted to DOECODE as per instructions received after providing notification of creation of IP outside of work as part of a site-specific IP assignment agreement. This work was not funded by, nor was any work performed under any DOE contract.

Haun, AaronB. [Oak Ridge National Laboratory (ORNL↗

A hybrid nodal-staggered pseudo-spectral electromagnetic particle-in-cell method with finite-order centering

Electromagnetic particle-in-cell (PIC) codes are widely used to perform computer simulations of a variety of physical systems, including fusion plasmas, astrophysical plasmas, plasma wakefield particle accelerators, and secondary photon sources driven by ultra-intense lasers. In a PIC code, Maxwell's equations are solved on a grid with a numerical method of choice. This article focuses on pseudo-spectral analytical time-domain (PSATD) algorithms and presents a novel hybrid PSATD PIC scheme that combines the respective advantages of standard nodal and staggered methods. The novelty of the hybrid scheme consists in using finite-order centering of grid quantities between nodal and staggered grids, in order to combine the solution of Maxwell's equations on a staggered grid with the deposition of charges and currents and the gathering of electromagnetic forces on a nodal grid. The correctness and performance of the novel hybrid scheme are assessed by means of numerical tests that employ different classes of PSATD equations in a variety of physical scenarios, ranging from the modeling of electron-positron pair creation in vacuum to the simulation of laser-driven and particle beam-driven plasma wakefield acceleration. It is shown that the novel hybrid scheme offers significant numerical and computational advantages, compared to purely nodal or staggered methods, for all the test cases presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

How the Theory of Computing Can Help in Space Exploration

The opening of the NASA Pan American Center for Environmental and Earth Sciences (PACES) at the University of Texas at El Paso made it possible to organize the student Center for Theoretical Research and its Applications in Computer Science (TRACS). In this abstract, we briefly describe the main NASA-related research directions of the TRACS center, and give an overview of the preliminary results of student research.

Kreinovich, Vladik↗

Transport of ions injected by AMPTE magnetotail releases

The BA and Li ions released in the magnetotail by the AMPTE IRM satellite were not observed in the inner magnetosphere with the AMPTE CCE satellite. In an effort to understand these results, Cladis and Francis (1988) modeled the expansion and ionization of the released atoms and computed several hundred guiding-center trajectories of the ions to sample the motion of each ion cloud. Here, the transport calculations are improved, principally by computing the full gyration motion of the ions in a more realistic model of the geomagnetic tail. The results indicate that the Ba(+) ions were convected inward along a narrow corridor, which was at least 2 earth radii away from the satellite in the case of the first Ba release and at least 3 earth radii away in the case of the second Ba release. Even if the ions had reached the satellite, their energies would have been too low to be detected. The Li(+) ions from both releases drifted inward over broad regions which overlapped the satellite in space and time. However, their fluxes at the satellite were somewhat too low to be detected.

Cladis, J. B.↗

A Fractional-Step Method Of Computing Incompressible Flow

Method of computing time-dependent flow of incompressible, viscous fluid involves numerical solution of Navier-Stokes equations on two- or three-dimensional computational grid based on generalized curvilinear coordinates. Equations of method derived in primitive-variable formulation. Dependent variables are pressure at center of each cell of computational grid and volume fluxes across faces of each cell. Volume fluxes replace Cartesian components of velocity; these fluxes correspond to contravariant components of velocity multiplied by volume of computational cell, in staggered grid. Choice of dependent variables enables simple extension of previously developed staggered-grid approach to generalized curvilinear coordinates and facilitates enforcement of conservation of mass.

Kwak, Dochan↗

Inspection of composites using a computer-based real-time radiographic facility

A radiographic inspection facility was developed at the NASA Lewis Research Center. The facility uses a digital computer to provide enhanced images in near real-time. Some capabilities of the facility are demonstrated in the inspection of a fan frame ring for an experimental aircraft gas turbine. The ring was fabricated from a carbon-fiber-reinforced epoxy composite material. Inspection procedures were evaluated, and comparisons were made with an ultrasonic C-scan and conventional film X-ray.

Roberts, E., Jr.↗

Introduction to USRA

The Universities Space Research Association (USRA) was incorporated 25 years ago in the District of Columbia as a private nonprofit corporation under the auspices of the National Academy of Sciences. Institutional membership in the association has grown from 49 colleges and universities, when it was founded, to 76 in 1993. USRA provides a mechanism through which universities can cooperate effectively with one another, with the government, and with other organizations to further space science and technology and to promote education in these areas. Its mission is carried out through the institutes, centers, divisions, and programs that are described in detail in this booklet. These include the Lunar and Planetary Institute, the Institute for Computer Applications in Science and Engineering (ICASE), the Research Institute for Advanced Computer Science (RIACS), and the Center of Excellence in Space Data and Information Sciences (CESDIS).

Davis, M. H.↗

Computer Science Research at Langley

A workshop was held at Langley Research Center, November 2-5, 1981, to highlight ongoing computer science research at Langley and to identify additional areas of research based upon the computer user requirements. A panel discussion was held in each of nine application areas, and these are summarized in the proceedings. Slides presented by the invited speakers are also included. A survey of scientific, business, data reduction, and microprocessor computer users helped identify areas of focus for the workshop. Several areas of computer science which are of most concern to the Langley computer users were identified during the workshop discussions. These include graphics, distributed processing, programmer support systems and tools, database management, and numerical methods.

Voigt, S. J.↗

Research through simulation

The design of the computer operating system at Langley Research Center allows for concurrent support of time-critical simulations and background analytical computing on the same machine. Signal path interconnections between computing hardware and flight simulation hardware is provided to allow up to six simulation programs to be in operation at one time. Capabilities and research applications are discussed for the: (1) differential maneuvering simulator; (2) visual motion simulator; (3) terminal configured vehicle simulator; (4) general aviation aircraft simulator; (5) general purpose fixed based simulator; (6) transport simulator; (7) digital fly by wire simulator; (8) general purpose fighter simulator; and (9) the roll-up cockpit. The visual landing display system and graphics display system are described and their simulator support applications are listed.

Copeland, J. L.↗

Next Generation Flight Controller Trainer System

The Next Generation Flight Controller Trainer (NGFCT) is a relatively inexpensive system of hardware and software that provides high-fidelity training for spaceshuttle flight controllers. NGFCT provides simulations into which are integrated the behaviors of emulated space-shuttle vehicle onboard general-purpose computers (GPCs), mission-control center (MCC) displays, and space-shuttle systems as represented by high-fidelity shuttle mission simulator (SMS) mathematical models. The emulated GPC computers enable the execution of onboard binary flight-specific software. The SMS models include representations of system malfunctions that can be easily invoked. The NGFCT software has a flexible design that enables independent updating of its GPC, SMS, and MCC components.

Arnold, Scott↗