Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “coordinate computing”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Cis-Divacant Octahedral Fe(II) in a Dimensionally Reduced Family of 2-(Pyridin-2-yl)pyrrolide Complexes

Four-coordinate transition metal complexes can adopt a diverse array of coordination geometries, with square planar and tetrahedral coordination being the most prevalent. Previously, we reported the synthesis of a trinuclear Fe(II) complex, Fe 3 TPM 2 , supported by a three-fold symmetric 2-pyridylpyrrolide ligand (i.e., tris(5-(pyridin-2-yl)-1H-pyrrol-2-yl)methane), that featured a rare cis-divacant octahedral (CDO) geometry at each Fe(II) center. Here, a series of truncated 2-pyridylpyrrolide ligands is described that support mono- and binuclear Fe(II) complexes that also exhibit CDO geometries. Metallation of tetradentate ligand bis(5-(pyridin-2-yl)-1H-pyrrol-2-yl)methane (H 2 BPM) in THF results in a binuclear complex Fe 2 (BPM) 2 (THF) 2 in which both Fe(II) ions are octahedrally coordinated. The coordinated THF solvent ligands are labile: THF dissociation leads to Fe 2 (BPM) 2 , which features five-coordinate Fe(II) ions. The Fe–Fe distance in these binuclear complexes can be elongated by ligand methylation. Metalation of bis(5-(6-methylpyridin-2-yl)-1H-pyrrol-2-yl)methane (H 2 BPM Me ) in THF leads to the formation of four-coordinate, CDO Fe(II) centers in Fe(BPM Me ) 2 . Further ligand truncation affords bidentate ligands 2-(1H-pyrrol-2-yl)pyridine (PyrPyrrH) and 2-methyl-6-(1H-pyrrol-2-yl)pyridine (Pyr Me PyrrH). Metalation of these ligands in THF affords six-coordinate complexes Fe(PyrPyrr) 2 (THF) 2 and Fe(Pyr Me Pyrr) 2 (THF) 2 . Dissociation of labile solvent ligands provides access to fourcoordinate Fe(II) complexes. Ligand disproportionation at Fe(PyrPyrr) 2 results in the formation of Fe(PyrPyrr) 3 and Fe(0). Ligand methylation suppresses this disproportionation and enables isolation of Fe(Pyr Me Pyrr) 2 , which is rigorously CDO. Complete ligand truncation, by separating the 2-pyridylpyrrolide ligands into the constituent monodentate pyridyl and pyrrolide donors, affords Fe(Pyr) 2 (Pyrr) 2 in which the Fe(II) is tetrahedrally coordinated. Computational analysis indicates that the potential energy surface that dictates the coordination geometry in this family of four-coordinate complexes is fairly flat in the vicinity of CDO coordination. Furthermore, these synthetic studies provide the structural basis to explore the implications of CDO geometry on Fe-catalyzed reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1987

Algebraic grid generation

Algebraic grid generation is the direct expression of a physical coordinate system as a function of a uniform grid in a rectangular computational coordinate system. Algebraic grid generation is based on mathematical interpolation and is presented in general terms of multivariate transfinite interpolation. The multisurface method and the two-boundary technique are described as univariate procedures that can be applied within the context of transfinite interpolation. A technique for grid clustering is described. Problems that are commonly encountered in three-dimensional grid generation are discussed and approaches for dealing with complex physical domains using multiple computational grid blocks are presented.

Smith, Robert E.↗
NASA NTRS1980

A new coordinate transformation for turbulent boundary layer flows

The transformation permits a uniform mesh to be used in the computational coordinate which extends across the layer. This coordinate transformation uses the local value of the skin friction coefficient to scale the thickness of the wall layer region, and the local maximum value of turbulent viscosity to scale the boundary-layer thickness. Results are presented for two dimensional boundary layers in both positive and negative pressure gradients and comparisons are made with experimental data and conventional variable-grid results for low speed turbulent boundary-layers. The cases chosen illustrate the capability of this new transformation to capture the boundary layer growth over the full extent of laminar, transitional, and turbulent flow with no grid adjustment as well as its ability to consistently enlarge the wall layer region for accurate shear stress representation. Results of mesh refinement studies using the new coordinate transformation are presented.

Carter, J. E.↗
NASA NTRS1991

Parallel Inferencing For Rule-Based Expert Systems

Improved approach to development of expert-system computer programs increases speed of execution on parallel processors; that is, on multiple coordinated computers operating simultaneously, each on different part of problem. Based on detection and analysis of hidden parallelism in knowledge bases (collections of "if...then..." rules) and exploitation of this parallelism to maximize speed of execution on parallel processors connected to each other in hypercube configuration.

Schwuttke, Ursula M.↗
NASA NTRS1987

The control networks of the satellites of Jupiter

Geodetic control networks are being computed photogrammetrically for the large satellites of Jupiter, using pictures from the Voyager 1 and 2 encounters. Control points have been identified on the satellites and their coordinates computed by single-block analytical triangulation. The data sets have been converted from the B1950 to the J2000 inertial coordinate system to be compatible with future flight missions.

Davies, Merton E.↗
NASA NTRS1983

A shock-fitting solution of the supersonic flowfield in a rounded internal corner

A comparison is presented of a computational investigation of the flowfield created by supersonic flow over an internal corner with rounding and experimental results at a freestream Mach number of 4.1. The computational study uses a shock-fitting finite difference scheme with explicit formulation of the transformation to computational coordinates. The solutions calculated agree with previous ones for the sharp corner case and with the experimental investigation results for the rounded corner case. Parametric effects were computed for variations in corner rounding, freestream Mach number, symmetric wedge angle and unsymmetric wedge angle. A region is described over which successful executions were obtained.

Martin, J. A.↗
NASA NTRS1985

The Control Networks of the Satellites of Jupiter and Saturn

Geodetic control networks are being computed photogrammetrically for the large satellites of Jupiter and many of the satellites of Saturn using pictures from the Voyager 1 and 2 encounters. Control points have been identified on the satellites and their coordinates computed by single-block analytical triangulations. Contents of data sets for Io, Europa, Ganymede, Callisto, and Rhea are summarized.

Davies, M. E.↗
DOE OSTI2023

Opportunities for enhancing MLCommons efforts while leveraging insights from educational MLCommons earthquake benchmarks efforts

MLCommons is an effort to develop and improve the artificial intelligence (AI) ecosystem through benchmarks, public data sets, and research. It consists of members from start-ups, leading companies, academics, and non-profits from around the world. The goal is to make machine learning better for everyone. In order to increase participation by others, educational institutions provide valuable opportunities for engagement. In this article, we identify numerous insights obtained from different viewpoints as part of efforts to utilize high-performance computing (HPC) big data systems in existing education while developing and conducting science benchmarks for earthquake prediction. As this activity was conducted across multiple educational efforts, we project if and how it is possible to make such efforts available on a wider scale. This includes the integration of sophisticated benchmarks into courses and research activities at universities, exposing the students and researchers to topics that are otherwise typically not sufficiently covered in current course curricula as we witnessed from our practical experience across multiple organizations. As such, we have outlined the many lessons we learned throughout these efforts, culminating in the need for benchmark carpentry for scientists using advanced computational resources. The article also presents the analysis of an earthquake prediction code benchmark while focusing on the accuracy of the results and not only on the runtime; notedly, this benchmark was created as a result of our lessons learned. Energy traces were produced throughout these benchmarks, which are vital to analyzing the power expenditure within HPC environments. Additionally, one of the insights is that in the short time of the project with limited student availability, the activity was only possible by utilizing a benchmark runtime pipeline while developing and using software to generate jobs from the permutation of hyperparameters automatically. It integrates a templated job management framework for executing tasks and experiments based on hyperparameters while leveraging hybrid compute resources available at different institutions. The software is part of a collection called cloudmesh with its newly developed components, cloudmesh-ee (experiment executor) and cloudmesh-cc (compute coordinator).

58 GEOSCIENCES↗
NASA NTRS1983

Three-dimensional algebraic grid generation

One of the major approaches to numerical grid generation is the explicit algebraic expression of a physical grid as a function of a uniform grid in a rectangular computational coordinate system. The algebraic methods are based on mathematical interpolation, and the primary advantages are speed and directness. The relation between interpolation and grid generation is described. For three-dimensional grid generation, transfinite interpolation using the coordinate control processes developed in the multisurface method and two-boundary technique are advocated. Grid singularities encountered in three dimensions are discussed, and the exploration of multiple overlapping grids is proposed. Some aspects of interactive algebraic grid computation in three dimensions are discussed.

Smith, R. E.↗
NASA NTRS1988

Three-dimensional incompressible Navier-Stokes computations of internal flows

Several incompressible Navier-Stokes solution methods for obtaining steady and unsteady solutions are discussed. Special attention is given to internal flows which involve distinctly different features from external flows. The characterisitcs of the flow solvers employing the method of pseudocompressibility and a fractional step method are briefly described. This discussion is limited to a primitive variable formulation in generalized curvilinear coordinates. Computed results include simple test cases and internal flow in the Space Shuttle main engine hot-gas manifold.

Kwak, D.↗
NASA NTRS1984

Potential application of artificial concepts to aerodynamic simulation

The concept of artificial intelligence as it applies to computational fluid dynamics simulation is investigated. How expert systems can be adapted to speed the numerical aerodynamic simulation process is also examined. A proposed expert grid generation system is briefly described which, given flow parameters, configuration geometry, and simulation constraints, uses knowledge about the discretization process to determine grid point coordinates, computational surface information, and zonal interface parameters.

Kutler, P.↗
NASA NTRS1989

EAC: A program for the error analysis of STAGS results for plates

A computer code is now available for estimating the error in results from the STAGS finite element code for a shell unit consisting of a rectangular orthotropic plate. This memorandum contains basic information about the computer code EAC (Error Analysis and Correction) and describes the connection between the input data for the STAGS shell units and the input data necessary to run the error analysis code. The STAGS code returns a set of nodal displacements and a discrete set of stress resultants; the EAC code returns a continuous solution for displacements and stress resultants. The continuous solution is defined by a set of generalized coordinates computed in EAC. The theory and the assumptions that determine the continuous solution are also outlined in this memorandum. An example of application of the code is presented and instructions on its usage on the Cyber and the VAX machines have been provided.

Sistla, Rajaram↗
NASA NTRS2014

Flight Avionics Hardware Roadmap

The Avionics Technology Roadmap takes an 80% approach to technology investment in spacecraft avionics. It delineates a suite of technologies covering foundational, component, and subsystem-levels, which directly support 80% of future NASA space mission needs. The roadmap eschews high cost, limited utility technologies in favor of lower cost, and broadly applicable technologies with high return on investment. The roadmap is also phased to support future NASA mission needs and desires, with a view towards creating an optimized investment portfolio that matures specific, high impact technologies on a schedule that matches optimum insertion points of these technologies into NASA missions. The roadmap looks out over 15+ years and covers some 114 technologies, 58 of which are targeted for TRL6 within 5 years, with 23 additional technologies to be at TRL6 by 2020. Of that number, only a few are recommended for near term investment: 1. Rad Hard High Performance Computing 2. Extreme temperature capable electronics and packaging 3. RFID/SAW-based spacecraft sensors and instruments 4. Lightweight, low power 2D displays suitable for crewed missions 5. Radiation tolerant Graphics Processing Unit to drive crew displays 6. Distributed/reconfigurable, extreme temperature and radiation tolerant, spacecraft sensor controller and sensor modules 7. Spacecraft to spacecraft, long link data communication protocols 8. High performance and extreme temperature capable C&DH subsystem In addition, the roadmap team recommends several other activities that it believes are necessary to advance avionics technology across NASA: center dot Engage the OCT roadmap teams to coordinate avionics technology advances and infusion into these roadmaps and their mission set center dot Charter a team to develop a set of use cases for future avionics capabilities in order to decouple this roadmap from specific missions center dot Partner with the Software Steering Committee to coordinate computing hardware and software technology roadmaps and investment recommendations center dot Continue monitoring foundational technologies upon which future avionics technologies will be dependent, e.g., RHBD and COTS semiconductor technologies

Some, Raphael↗
DOE OSTI2025

PDB-IHM: A System for Deposition, Curation, Validation, and Dissemination of Integrative Structures

Structures of many large biomolecular assemblies are now being determined using integrative approaches. In these approaches, information derived from multiple experimental and computational methods is combined to compute three-dimensional structures of multi-protein complexes and other macromolecular machines. A standalone prototype data resource for integrative structures called PDB-Dev was built, based on recommendations of the Integrative and Hybrid Methods (IHM) Task Force of the Worldwide Protein Data Bank (wwPDB). This effort included developing data standards and software tools for collecting, curating, validating, visualizing, archiving, and disseminating integrative structures that span diverse spatiotemporal scales and conformational states. Mechanisms have been created to validate integrative structures based on the experimental data underpinning them. Building upon this foundational framework, PDB-Dev has been further expanded to handle large dynamic macromolecular systems and integrative structures that combine, for example, experimental restraints with atomic coordinates computed by machine learning algorithms. Data standards and supporting tools have also been extended to capture information about biomolecular dynamics, such as conformational transitions and related kinetic data derived from biophysical methods. Recently, PDB-Dev was unified with the PDB archive and rebranded as PDB-IHM (pdb-ihm.org), further promoting FAIR (Findable, Accessible, Interoperable, and Reusable) principles of data stewardship for integrative structural biology.

IHMCIF↗
DOE OSTI2021

Understanding the TiH (2-x) /TiO y System at Elevated Temperature: A Literature Review

Titanium hydride of varying TiH stoichiometry is used in pyrotechnic compositions. In order to yield consistent performance, manufacturing processes must be developed to ensure precise and reproducible material properties, including composition and morphology. Legacy synthesis protocols are not comprehensive nor are the required apparatuses still available. To guide the development of novel production procedures, this report reviews literature on relevant chemical reactions and diffusion events occurring at elevated temperature in the TiH (2-x) /TiO y system. Titanium hydride exposed to air spontaneously forms a passivating oxide layer. Upon heating, significant hydrogen release, which is accompanied by changes to the surface oxide layer, is noted by 375–400°C. At higher temperatures (above about 500°C) the oxide layer is reported to be essentially nonexistent as a result of oxide-layer dissolution processes and, potentially, oxide-layer reduction due to water formation. Based on the reviewed literature, we hypothesize that, by 500°C, the surface layer consists of an oxyhydride phase, which is a solid solution of oxygen in titanium hydride. We believe that hydrogen release from titanium hydride is controlled by the kinetics of molecular hydrogen desorption on the oxyhydride surface. No literature data is available for corresponding activation energies of the dynamic desorption process, and the equilibrium phase diagram of this three-component system remains largely unexplored as well. These gaps in knowledge might be addressed through coordinated computational modeling and experimental efforts.

36 MATERIALS SCIENCE↗
NASA NTRS1978

High-precision laser distance measurement in support of lunar laser ranging at Haleakala, Maui, 1976-1977

The Hawaii Institute of Geophysics has implemented a comprehensive geodetic-geophysical support program to monitor local and regional crustal deformation on the island of Maui. Presented are the actual laser-measured line lengths and new coordinate computations of the line terminals, and the internal consistency of the measured line lengths is discussed. Several spacial chord lengths have been reduced to a Mercator plane, and conditioned adjustments on that plane have been made.

Berg, E.↗