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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Query Optimization for Graph Analytics on Linked Data Using SPARQL

Triplestores that support query languages such as SPARQL are emerging as the preferred and scalable solution to represent data and meta-data as massive heterogeneous graphs using Semantic Web standards. With increasing adoption, the desire to conduct graph-theoretic mining and exploratory analysis has also increased. Addressing that desire, this paper presents a solution that is the marriage of Graph Theory and the Semantic Web. We present software that can analyze Linked Data using graph operations such as counting triangles, finding eccentricity, testing connectedness, and computing PageRank directly on triple stores via the SPARQL interface. We describe the process of optimizing performance of the SPARQL-based implementation of such popular graph algorithms by reducing the space-overhead, simplifying iterative complexity and removing redundant computations by understanding query plans. Our optimized approach shows significant performance gains on triplestores hosted on stand-alone workstations as well as hardware-optimized scalable supercomputers such as the Cray XMT.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
NASA NTRS1985

The design and implementation of cost-effective algorithms for direct solution of banded linear systems on the vector processor system 32 supercomputer

The problem of solving banded linear systems by direct (non-iterative) techniques on the Vector Processor System (VPS) 32 supercomputer is considered. Two efficient direct methods for solving banded linear systems on the VPS 32 are described. The vector cyclic reduction (VCR) algorithm is discussed in detail. The performance of the VCR on a three parameter model problem is also illustrated. The VCR is an adaptation of the conventional point cyclic reduction algorithm. The second direct method is the Customized Reduction of Augmented Triangles' (CRAT). CRAT has the dominant characteristics of an efficient VPS 32 algorithm. CRAT is tailored to the pipeline architecture of the VPS 32 and as a consequence the algorithm is implicitly vectorizable.

Samba, A. S.↗
DOE OSTI2015

SU-F-BRA-06: Dose Distributions for the CivaSheet Pd-103 Directional Brachytherapy Device

Purpose: A flexible polymer membrane (CivaSheet) has been developed by CivaTech Oncology, Inc. (Research Triangle Park, NC) for permanent brachytherapy. Distributed throughout the array are small plastic disks containing Pd-103 and gold foil shielding on one side to provide a directional dose distribution and facilitate imaging. This study evaluated dosimetry for the CivaSheet. Methods: Manufacturer-provided dimensional and compositional information for the device were compared to physical samples for validation of design information, then entered into the MCNP6 radiation transport code for dosimetry simulations. Three device sizes (6×6, 6×12, or 6×18 disk-arrays) were simulated as the membrane can be custom-sized preceding surgical placement. Dose to water was estimated with 0.01 cm resolution from the surface to 10 cm on both sides of the device. Because this is a novel device with calibration methods under development, results were normalized using DVHs to provide 90% prescription coverage to a plane positioned 0.5 cm from the front surfaces. This same normalization was used for creating isodose distributions. Results: Planar dose distributions of flat CivaSheets were relatively homogeneous with acceptable dose uniformity variations. Differences in the results between the differently sized CivaSheets were not significant. At 0.5 mm, 87% of the target volume was within the therapeutic dose range. Dose hotspots on the CivaSheet forward surfaces were directly above the disks. However, dose hotspots on the rear-facing surfaces were positioned between the disks. Doses in contact with the front surface were similar to those observed for currently available brachytherapy sources. Maximum doses that occurred on the rear surface were approximately 55 times lower than the dose on the front surface. Conclusion: Monte Carlo calculations validated the directional capabilities and advantageous dosimetry of the new Pd-103 brachytherapy device. It appears feasible to re-size the CivaSheet in the operating room with an acceptable variation in prescription dose. Research was supported by CivaTech Oncology, Inc.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2002

Intellectual Dummies

Goddard Space Flight Center and Triangle Research & Development Corporation collaborated to create "Smart Eyes," a charge coupled device camera that, for the first time, could read and measure bar codes without the use of lasers. The camera operated in conjunction with software and algorithms created by Goddard and Triangle R&D that could track bar code position and direction with speed and precision, as well as with software that could control robotic actions based on vision system input. This accomplishment was intended for robotic assembly of the International Space Station, helping NASA to increase production while using less manpower. After successfully completing the two- phase SBIR project with Goddard, Triangle R&D was awarded a separate contract from the U.S. Department of Transportation (DOT), which was interested in using the newly developed NASA camera technology to heighten automotive safety standards. In 1990, Triangle R&D and the DOT developed a mask made from a synthetic, plastic skin covering to measure facial lacerations resulting from automobile accidents. By pairing NASA's camera technology with Triangle R&D's and the DOT's newly developed mask, a system that could provide repeatable, computerized evaluations of laceration injury was born.

Source record↗
DOE OSTI2012

Structure, growth and properties of a novel polar material, KSr{sub 4}B{sub 3}O{sub 9}

A novel polar material, KSr{sub 4}B{sub 3}O{sub 9}, has been obtained by the high temperature solution method for the first time. It crystallizes in the polar space group Ama2. The material exhibits a three-dimensional structure consisting of interconnecting KO{sub 10} groups, SrO{sub x} (x=8, 9) units and isolated BO{sub 3} triangles. DSC/TG curve shows that KSr{sub 4}B{sub 3}O{sub 9} melts incongruently. The calculated band structures and the density of states of KSr{sub 4}B{sub 3}O{sub 9} suggest that its direct gap is 3.897 eV. The absorption spectrum indicates the absorption edge of KSr{sub 4}B{sub 3}O{sub 9} is about 302 nm. It produces SHG intensity about as large as that of KH{sub 2}PO{sub 4} (KDP) and is phase matchable. - Graphical abstract: Viewed along the c-axis, B(2)O{sub 3} triangles and B(3)O{sub 3} triangles are parallel with the (0 1 0) face and opposite to each other. However, all the B(1)O{sub 3} triangles have the same direction along the c-axis. So the main SHG efficiency of the compound comes from B(1)O{sub 3} triangles according to the anion group theory. Highlights: Black-Right-Pointing-Pointer A polar material, KSr{sub 4}B{sub 3}O{sub 9}, has been obtained by high temperature solution method. Black-Right-Pointing-Pointer The material consists of KO{sub 10} units, SrO{sub x}(x=8, 9) units and isolated BO{sub 3} units. Black-Right-Pointing-Pointer KSr{sub 4}B{sub 3}O{sub 9} produces SHG intensity as large as that of KDP and is phase matchable. Black-Right-Pointing-Pointer The absorption edge of KSr{sub 4}B{sub 3}O{sub 9} is about 302 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2012

HolT Hunter: Software for Identifying and Characterizing Low-Strain DNA Holliday Triangles

Synthetic DNA nanostructures are most commonly held together via Holliday junctions. These junctions allow for a wide variety of different angles between the double helices they connect. Nevertheless, only constructs with a very limited selection of angles have been built, to date, because of the computational complexity of identifying structures that fit together with low strain at odd angles. I have developed an algorithm that finds over 95% of the possible solutions by breaking the problem down into two portions. First, there is a problem of how smooth rods can form triangles by lying across one another. This problem is easily handled by numerical computation. Second, there is the question of how distorted DNA double helices would need to be to fit onto the rod structure. This strain is calculated directly. The algorithm has been implemented in a Mathematica 8 notebook called Holliday Triangle Hunter. A large database of solutions has been identified. Additional interface software is available to facilitate drawing and viewing models.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRSDate not supplied

Extending an Economical Third-Order Inviscid Nodal-Gradient Cell-Centered Finite-Volume Method to Mixed-Element Grids

In this paper, we extend an economical third-order nodal-gradient cell-centered finite-volume method, originally developed for tetrahedral grids, to mixed-element grids. It is shown that the efficient quadratic interpolation formula essential to eliminating second derivatives from a third-order accurate discretization can be easily extended to an arbitrary cell type. For the surface flux integration, we consider a split-face approach, where a quadrilateral face is split into two triangles, and the third-order method for tetrahedra is directly applied. Also, we derive a second-derivative-free, high-order, volume quadrature formula for an arbitrary cell. Numerical results are presented for accuracy verification and applications with three-dimensional nontetrahedral grids.

Computational Fluid Dynamics↗
DOE OSTI2024

Light quark loops in ${K}^{\pm}\to {\pi}^{\pm}\nu \overline{\nu}$ from vector meson dominance and update on the Kaon Unitarity Triangle

We use vector meson dominance to calculate non-perturbative contributions to the branching ratio of the rare decay $K$ ± → π ± $v\overline{v}$ stemming from matrix elements involving up-quark loops. The importance of this observable as well as of K 0 → π 0 l + l - and of the direct CP violation parameter ϵ' K is then discussed in the context of a Unitarity Triangle sqtudy based on Kaon sector observables only.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Indirect Measurement of the 23 Na(p, γ) 24 Mg Direct Capture Reaction Rate via ( 3 He,d) Spectroscopy

The cross section of the $^{23}\text{Na}(p,γ)^{24}\text{Mg}$ reaction is dominated by direct capture at low energies relevant for stellar burning. Such cross sections can be constrained using spectroscopic factors($C^2S$) or asymptotic normalization coefficients(ANCs) from transfer reactions. In this work, the $^{23}\text{Na}(^3\text{He},d)^{24}\text{Mg}$ reaction was measured at $E_{lab}=21$ MeV to extract spectroscopic factors for $^{24}\text{Mg}$ states with excitation energies in $E_x=7 - 12$ MeV using the Enge split-pole spectrograph at the Triangle Universities Nuclear Laboratory. A new non-resonant astrophysical S factor and the direct capture reaction rate for the $^{23}\text{Na}(p,γ)$ reaction are calculated and presented based on this measurement. The new rate at $T<0.04$ GK is 43$\%$ smaller than in previous studies. Rigorous treatments of uncertainties are presented using a Bayesian Markov Chain Monte Carlo (MCMC) method. Finally, sources of uncertainties for computing the direct capture cross section are also discussed in detail.

electromagnetic moments↗
DOE OSTI2015

Colloidal self assembly of non-magnetic particles in magnetic nanofluid

Here we present a technique using magnetic nanofluid to induce bidispersed suspension of nonmagnetic particles to assemble into colloidal chain, triangle, rectangle, ring-flower configurations. By changing the amplitude and direction of the magnetic field, we could tune the structure of nonmagnetic particles in magnetic nanofluid. The structures are assembled using magneto static interactions between effectively nonmagnetic particles dispersed in magnetizable magnetic nanofluid. The assembly of complex structures out of simple colloidal building blocks is of practical interest in photonic crystals and DNA biosensors.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Triangle Method for Dense ReLU Layers [SWR-25-72]

This software is an implementation of the methods for initializing and training neural networks to be more efficient per parameter, described more fully below and in the related publication: In theory, depth should make a ReLU network EXPONENTIALLY more efficient by enabling it to produce an exponential number of piecewise linear sections in its output. This reasoning is largely based on the work of mathematicians that have hand-constructed networks that make good use of depth. In practice however, even very deep ReLU networks that have been randomly initialized will behave identically to their shallow counterparts - missing an entire exponential dimension of efficiency. The triangle method is a first attempt at realizing the exponential potential of deep networks. Instead of randomly setting weights, we force pairs of neurons in each layer learn to build triangles (i.e. functions from [0,1] -> [0,1] that look like triangles). This is a very efficient pattern for generating lots of linear pieces because composing two triangular functions doubles the number of pieces with each composition. The triangle method is more than just a different initialization, it is a new paradigm of training. Instead of making direct updates to the matrix weights, we do an extra step of backpropagation to collect the derivatives of the loss function with respect to the shapes of the triangles, training them to tilt left or right. This process essentially holds the networks hand throughout the loss landscape and forces it to always use depth effectively by producing triangular shapes internally. This can produce several orders of magnitude of improvement on convex one-dimensional regression problems. Much more theoretical work is needed to realize its full potential beyond this context, but the implementation in this repository will still work in arbitrary numbers of dimensions. The file Triangle_Method.py is a generalized form of the method that will build each neuron its own custom 1-d convex activation function (with exponential efficiency). Example usage on one dimensional problems can be found in Example_Usage.ipynb and an example of using this in a real neural network can be found in Example_VGG16_CIFAR10.ipynb.

Milkert, Max [National Renewable Energy Laboratory↗
DOE OSTI2026

Observable optimization for precision theory: machine learning energy correlators

The practice of collider physics typically involves the marginalization of multi-dimensional collider data to uni-dimensional observables relevant for some physics task. In many cases, such as classification or anomaly detection, the observable can be arbitrarily complicated, such as the output of a neural network. However, for precision measurements, the observable must correspond to something computable systematically beyond the level of current simulation tools. In this work, we demonstrate that precision-theory-compatible observable space exploration can be systematized by using neural simulation-based inference techniques from machine learning. We illustrate this approach by exploring the space of marginalizations of the energy 3-point correlator to optimize sensitivity to the top quark mass. We first learn the energy-weighted probability density from simulation, then search in the space of marginalizations for an optimal triangle shape. Although simulations and machine learning are used in the process of observable optimization, the output is an observable definition which can be then computed to high precision and compared directly to data without any memory of the computations which produced it. We find that the optimal marginalization is isosceles triangles on the sphere with a side ratio approximately $1 : 1 : \sqrt{2}$ (i.e. right triangles) within the set of marginalizations we consider.

Jets and Jet Substructure↗
DOE OSTI2014

Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination

A novel direct phase-selection method to select optimized phases from the ambiguous phases of a subset of reflections to replace the corresponding initial SAD phases has been developed. With the improved phases, the completeness of built residues of protein molecules is enhanced for efficient structure determination. Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (ϕ{sub 1} and ϕ{sub 2}) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ{sub DS} list as a criterion to select optimized phases ϕ{sub am} from ϕ{sub 1} or ϕ{sub 2} of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases ϕ{sub SAD} has been developed. Based on this work, reflections with an angle θ{sub DS} in the range 35–145° are selected for an optimized improvement, where θ{sub DS} is the angle between the initial phase ϕ{sub SAD} and a preliminary density-modification (DM) phase ϕ{sub DM}{sup NHL}. The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

PhytoPET, PhytoBeta and PhytoSPECT: Radioisotope Imaging Systems Being Developed for Plant Biology Research

The Radiation Detector and Imaging Group at Thomas Jefferson National Accelerator Facility (Jefferson Lab) is developing radioisotope imaging systems designed and constructed to facilitate plant biology studies at the Duke University Phytotron. The imaging systems utilize nuclear medicine imaging methodologies used in positron emission tomography (PET) and single photon emission computed tomography (SPECT) but designed specifically for plant biology. The range of plant shapes and the environmental conditions in plant growth chambers pose a technological challenge. Description: Jefferson Lab is collaborating with the Duke University Phytotron and the Triangle Universities Nuclear Laboratory (TUNL) in the construction and operation of PhytoPET and PhytoBeta (for direct beta particle detection) for plant and/or microbe imaging. The TUNL tandem Van de Graaff accelerator (maximum terminal voltage of 10 MV) has been used to generate 11C and 13N for plant biology research. The PhytoPET and PhytoBeta have been used with 11C as a 11CO2 tracer for plant ecophysiology imaging with corn, poplar, oak and barley utilizing technologies developed for nuclear physics research and nuclear medicine. The imaging detectors are based on position sensitive photomultiplier tubes coupled to scintillators. Additionally, the collaboration is investigating a methodology using single photon emitting radioisotope tracers for imaging the distribution of molecular compounds of interest in the rhizosphere, the interface between root and soil, without disturbing the root or soil habitat. Plans are underway to develop a single photon emission computed tomography (SPECT) system (PhytoSPECT) to image the bio-distribution of fungi in association with a host plant's roots. In addition to a description of the technology an overview will be given of the application of PhytoPET, PhytBeta and PhytoSPECT to plant biology research at Duke University. Conclusions: We have developed and used radioisotope imaging technologies based on PET and SPECT to visualize plant function in changing environments. There are many opportunities to provide radioisotope based imaging tools for plant ecophysiology imaging. Keywords: radioisotope detection, plant biology, carbon-11, accelerator produced isotopes

Weisenberger, Andrew↗
NASA NTRS2005

Effect of Tabs on a Rectangular Nozzle Studied

In a continuing research program, jets from nozzles of different geometries are being investigated with the aim of increasing mixing and spreading in those flows. Flow fields from nozzles with elliptic, rectangular, and other more complex cross-sectional shapes are being studied in comparison to circular nozzles over a wide Mach number range. As noted by previous researchers, noncircular jets usually spread faster than circular jets. Another technique being investigated to increase jet spreading even further for a given nozzle is the use of "tabs" to generate vortices. A typical tab is a triangular-shaped protrusion placed at the nozzle exit, with the base of the triangle touching the nozzle wall and the apex leaning downstream at 45 to the stream direction. This geometry was determined by a parametric study to produce the optimum effect for a given area blockage. The tabs can increase jet spreading significantly. The underlying mechanism traces to a pair of counter-rotating streamwise vortices originating from each tab. These vortex pairs persist in the flow; and with the appropriate number and strength, they can increase spreading.

Source record↗
NASA NTRS1994

NASA Technology Applications Team: Commercial applications of aerospace technology

The Research Triangle Institute (RTI) Team has maintained its focus on helping NASA establish partnerships with U.S. industry for dual use development and technology commercialization. Our emphasis has been on outcomes, such as licenses, industry partnerships and commercialization of technologies, that are important to NASA in its mission of contributing to the improved competitive position of U.S. industry. The RTI Team has been successful in the development of NASA/industry partnerships and commercialization of NASA technologies. RTI ongoing commitment to quality and customer responsiveness has driven our staff to continuously improve our technology transfer methodologies to meet NASA's requirements. For example, RTI has emphasized the following areas: (1) Methodology For Technology Assessment and Marketing: RTI has developed and implemented effective processes for assessing the commercial potential of NASA technologies. These processes resulted from an RTI study of best practices, hands-on experience, and extensive interaction with the NASA Field Centers to adapt to their specific needs. (2) Effective Marketing Strategies: RTI surveyed industry technology managers to determine effective marketing tools and strategies. The Technology Opportunity Announcement format and content were developed as a result of this industry input. For technologies with a dynamic visual impact, RTI has developed a stand-alone demonstration diskette that was successful in developing industry interest in licensing the technology. And (3) Responsiveness to NASA Requirements: RTI listened to our customer (NASA) and designed our processes to conform with the internal procedures and resources at each NASA Field Center and the direction provided by NASA's Agenda for Change. This report covers the activities of the Research Triangle Institute Technology Applications Team for the period 1 October 1993 through 31 December 1994.

Source record↗
NASA NTRS1994

NASA Technology Applications Team: Commercial applications of aerospace technology

The Research Triangle Institute (RTI) is pleased to report the results of NASA contract NASW-4367, 'Operation of a Technology Applications Team'. Through a period of significant change within NASA, the RTI Team has maintained its focus on helping NASA establish partnerships with U.S. industry for dual use development and technology commercialization. Our emphasis has been on outcomes, such as licenses, industry partnerships and commercialization of technologies that are important to NASA in its mission of contributing to the improved competitive position of U.S. industry. RTI's ongoing commitment to quality and customer responsiveness has driven our staff to continuously improve our technology transfer methodologies to meet NASA's requirements. For example, RTI has emphasized the following areas: (1) Methodology For Technology Assessment and Marketing: RTI has developed an implemented effective processes for assessing the commercial potential of NASA technologies. These processes resulted from an RTI study of best practices, hands-on experience, and extensive interaction with the NASA Field Centers to adapt to their specific needs; (2) Effective Marketing Strategies: RTI surveyed industry technology managers to determine effective marketing tools and strategies. The Technology Opportunity Announcement format and content were developed as a result of this industry input. For technologies with a dynamic visual impact, RTI has developed a stand-alone demonstration diskette that was successful in developing industry interest in licensing the technology; and (3) Responsiveness to NASA Requirements: RTI listened to our customer (NASA) and designed our processes to conform with the internal procedures and resources at each NASA Field Center and the direction provided by NASA's Agenda for Change. This report covers the activities of the Research Triangle Institute Technology Applications Team for the period 1 October 1993 through 31 December 1994.

Source record↗