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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Online Alpha Monitoring of High Cs-137 Hanford and SRS High Level Waste with Tensioned Metastable Fluid Detectors

The Department of Energy’s Hanford and Savannah River Sites maintain millions of gallons of caustic supernate and salt high activity waste in their high-level waste (HLW) tank farm inventories. The Savannah River Site is currently treating this waste with a calixarene-based solvent extraction of Cs-137 to reduce these inventories. Hanford is employing an at-tank crystalline silico titanate (CST) based solid phase extraction methodology to reduce their liquid HLW inventories. Due to the high solubility of Cs-137 and the relative insolubility of the actinides in these caustic waste forms, the beta to alpha radioactivity ratio can often exceed six orders of magnitude in the feed solutions to these treatment processes. This unique characteristic leads to significant technical challenges in making rapid gross alpha measurements in the presence of the overwhelming beta, gamma, as well as dissolved sodium salt in these HLW matrices. Conventional radioanalytical techniques, such as liquid scintillation analysis or gas flow proportional counting require significant radiochemistry preparation prior to the radiometric measurements for gross alpha activity. These required pretreatments render these technologies untenable for rapid quantification of gross alpha activity that could be required to support on or at-line measurements ensuring a waste stream will meet regulatory requirements. The radiation measurement properties of Tensioned Metastable Fluid Detectors (TMFDs) have been studied by Purdue University’s Taleyarkhan research group for well over a decade. Fluids tensioned to the appropriate degree will rupture when struck by radiation, resulting in a measurable cavitation event. The negative pressure generating this tension can be adjusted by centrifugal rotation or by acoustic means in such a way that these cavitation events can be generated from alpha radiation but will not be generated by beta or gamma radiation. Purdue University and the Savannah River National Laboratory are currently collaborating to develop a gamma/beta blind, spectroscopic alpha measurement system based on the Tensioned Metastable Fluid Detector technology to provide a potential solution for performing rapid gross alpha measurements on these high gamma/beta sample matrices. Measurements using the Indirect Drive Acoustically Tensioned Metastable Fluid Detectors developed as part of this collaboration were performed with an alpha emitting radionuclide. Successful determination of gross alpha activity was observed, indicating a potential pathway for rapid gross alpha measurements in remote-handled shielded cells or in process situations requiring online alpha monitoring. Measurements using this system have been conducted on high beta activity solutions, demonstrating the beta blind capability of this system. Measurements are currently underway to test the system’s capability to measure gross alpha activity on Savannah River Site high level waste high Cs-137 samples that have been measured by the SRNL radiochemistry team. This work was supported by the DOE EM Technology Development program.

DiPrete, David [Savannah River National Laboratory↗
DOE OSTI2016

From deep TLS validation to ensembles of atomic models built from elemental motions. Addenda and corrigendum

Researcher feedback has indicated that in Urzhumtsev et al. [(2015) Acta Cryst. D 71 , 1668–1683] clarification of key parts of the algorithm for interpretation of TLS matrices in terms of elemental atomic motions and corresponding ensembles of atomic models is required. Also, it has been brought to the attention of the authors that the incorrect PDB code was reported for one of test models. Lastly, these issues are addressed in this article.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Method used in Tokunaga, T. et al. 2018 for simulating time- and depth- dependent temperature variations in soil and sediment in Rifle, Colorado, 2013-2016.

This data package contains temperature, moisture content, matric potential, and carbon dioxide (CO2) concentration data from the Rifle, Colorado field site and from a 2 meter tall laboratory soil/sediment column designed to simulate field conditions. In addition, redox potential data from the laboratory column are included. The purpose of the data and paper is to demonstrate how a laboratory column was constructed to reproduce the dynamics of nonisothermal conditions in the field, such that CO2 production above a variable-depth water table can be studied in the laboratory. The data package contains 3 data files corresponding to the figures in the related paper (Tokunaga, T. et al. 2018) and 1 README file with the paper information.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

A novel nanoparticle-based disposable electrochemical immunosensor for diagnosis of exposure to toxic organophosphorus agents

We present a novel disposable electrochemical immunosensor for highly selective and sensitive detection of organophosphorylated butyrylcholinesterase (OP-BChE), a specific biomarker for exposure to toxic organophosphorus agents. In our new approach, the zirconia nanoparticles (ZrO-2) were employed to selectively capture the OP moiety of OP-BChE adducts, and followed by quantum dot (QD)-tagged anti-BChE antibodies for amplified quantification. The captured CdSe-QD tags can be sensitively detected by stripping voltammetry using in situ bismuth-plating method. The OP agent, diisopropylfluorophosphate (DFP), was selected to prepare OP-BChE adducts in various matrices. The formation of OP-BChE adducts in plasma sample was confirmed using mass spectroscopy. The developed electrochemical immunosensor demonstrates a highly linear voltammetric response over the range of 0.1 to 30 nM OP-BChE. Moreover, the immunosensor has been successfully applied for the detection of OP-BChE adducts in the plasma samples. This novel nanoparticle-based electrochemical immunosensor thus provides an alternative way for designing simple, fast, sensitive, and cost-effective sensing platform for on-site screening/evaluating exposure to a variety of OP agents.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Shift-and-invert parallel spectral transformation eigensolver: Massively parallel performance for density-functional based tight-binding

The Shift-and-invert parallel spectral transformations (SIPs), a computational approach to solve sparse eigenvalue problems, is developed for massively parallel architectures with exceptional parallel scalability and robustness. The capabilities of SIPs are demonstrated by diagonalization of density-functional based tight-binding (DFTB) Hamiltonian and overlap matrices for single-wall metallic carbon nanotubes, diamond nanowires, and bulk diamond crystals. The largest (smallest) example studied is a 128,000 (2000) atom nanotube for which ~330,000 (~5600) eigenvalues and eigenfunctions are obtained in ~190 (~5) seconds when parallelized over 266,144 (16,384) Blue Gene/Q cores. Weak scaling and strong scaling of SIPs are analyzed and the performance of SIPs is compared with other novel methods. Different matrix ordering methods are investigated to reduce the cost of the factorization step, which dominates the time-to-solution at the strong scaling limit. As a result, a parallel implementation of assembling the density matrix from the distributed eigenvectors is demonstrated.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Accelerating structural dynamics simulations with localised phenomena through matrix compression and projection‐based model order reduction

In this work, a novel approach is introduced for accelerating the solution of structural dynamics problems in the presence of localised phenomena, such as cracks. For this category of problems, conventional projection-based Model Order Reduction (MOR) methods are either limited with respect to the range of system configurations that can be represented or require frequent solutions of the Full Order Model (FOM) to update the low-dimensional spaces, in which solutions are represented. In the proposed approach, low-dimensional spaces, constructed for the healthy structure, are enriched with appropriately selected columns of the flexibility matrix of the system. It can be shown that these spaces contain the solution to the original problem for the static case, while their dimension is much smaller. In order to allow their online construction for arbitrary localised features, the full flexibility matrix of the system should be available. To this end, a hierarchical representation is used for the matrices involved, allowing to compute the flexibility matrix efficiently and with reduced memory requirements. The resulting method offers significant speedups, without sacrificing the flexibility and accuracy of the full order model. The performance and limitations of the approach are studied through a series of examples in structural dynamics.

fracture mechanics↗
DOE OSTI2017

Neutral kaon mixing beyond the Standard Model with n f = 2 + 1 chiral fermions. Part 2: non perturbative renormalisation of the ΔF = 2 four-quark operators

We compute the renormalisation factors (Z-matrices) of the ΔF = 2 four-quark operators needed for Beyond the Standard Model (BSM) kaon mixing. We work with nf = 2+1 flavours of Domain-Wall fermions whose chiral-flavour properties are essential to maintain a continuum-like mixing pattern. We introduce new RI-SMOM renormalisation schemes, which we argue are better behaved compared to the commonly-used corresponding RI-MOM one. We find that, once converted to MS¯, the Z-factors computed through these RI-SMOM schemes are in good agreement but differ significantly from the ones computed through the RI-MOM scheme. The RI-SMOM Z-factors presented here have been used to compute the BSM neutral kaon mixing matrix elements in the companion paper. In conclusion, we argue that the renormalisation procedure is responsible for the discrepancies observed by different collaborations, we will investigate and elucidate the origin of these differences throughout this work.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Asymptotic Growth of Solutions of Neutral Type Systems

We consider a differential system of neutral type with distributed delay. We obtain a precise norm estimation of semigroup generated by the operator corresponding to the system in question. Our result is based on a spectral analysis of the operator and some uniform estimation of norms of the exponentials of matrices. We also discuss the stability properties of corresponding solutions and the existence of the fastest growing solution.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Characterizing organic carbon dynamics during biostimulation of a uranium contaminated field site

Uranium contamination of groundwater remains a pressing problem at many former uranium mining and milling operations, such as the Rifle, Integrated Field Research Challenge (IFRC) site. Biostimulation of the subsurface with an organic carbon source such as acetate, followed by the microbially-induced reductive precipitation of uranium has been proposed as an effective remediation strategy. While uranium bioreduction has been studied in several field experiments, the transformation and fate of injected carbon remains poorly understood. This study evaluated the impact of added organic carbon on the long-term biogeochemical attenuation of uranium in the subsurface of a former mill tailings site. Fluorescence and ultraviolet–visible absorbance analyses were used together with dissolved organic carbon (DOC) measurements to track organic carbon dynamics during and post-biostimulation of the 2011 Rifle IFRC experiment. An electron mass balance was performed on well CD01 to account for any unidentified carbon sinks. Measured DOC values increased to 1.76 mM-C during biostimulation, and to 3.18 mM-C post-biostimulation over background DOC values of 0.3–0.4 mM-C. Elevated DOC levels persisted for 90 days after acetate injections ceased. The electron mass balance revealed that assumed electron acceptors would not account for the total amount of acetate consumed. Excitation–emission matrices showed an increase in signals associated with soluble microbial products, during biostimulation, which disappeared post-biostimulation despite an increase in total DOC. Specific ultraviolet absorbance analyses, indicated that DOC present post-biostimulation is less aromatic in nature, compared to background DOC. Furthermore, our results suggest that microbes convert injected acetate into a form of solid phase organic matter that may be available to sustain iron reduction post-stimulation.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Discrete Approximations of Determinantal Point Processes on Continuous Spaces: Tree Representations and Tail Triviality

We prove tail triviality of determinantal point processes μ on continuous spaces. Tail triviality has been proved for such processes only on discrete spaces, and hence we have generalized the result to continuous spaces. To do this, we construct tree representations, that is, discrete approximations of determinantal point processes enjoying a determinantal structure. There are many interesting examples of determinantal point processes on continuous spaces such as zero points of the hyperbolic Gaussian analytic function with Bergman kernel, and the thermodynamic limit of eigenvalues of Gaussian random matrices for Sine{sub 2},Airy{sub 2},Bessel{sub 2}, and Ginibre point processes. Our main theorem proves all these point processes are tail trivial.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Density Large Deviations for Multidimensional Stochastic Hyperbolic Conservation Laws

We investigate the density large deviation function for a multidimensional conservation law in the vanishing viscosity limit, when the probability concentrates on weak solutions of a hyperbolic conservation law. When the mobility and diffusivity matrices are proportional, i.e. an Einstein-like relation is satisfied, the problem has been solved in Bellettini and Mariani (Bull Greek Math Soc 57:31–45, 2010). When this proportionality does not hold, we compute explicitly the large deviation function for a step-like density profile, and we show that the associated optimal current has a non trivial structure. We also derive a lower bound for the large deviation function, valid for a more general weak solution, and leave the general large deviation function upper bound as a conjecture.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

The Pfaffian Sign Theorem for the Dimer Model on a Triangular Lattice

We prove the Pfaffian Sign Theorem for the dimer model on a triangular lattice embedded in the torus. More specifically, we prove that the Pfaffian of the Kasteleyn periodic-periodic matrix is negative, while the Pfaffians of the Kasteleyn periodic-antiperiodic, antiperiodic-periodic, and antiperiodic-antiperiodic matrices are all positive. The proof is based on the Kasteleyn identities and on small weight expansions. As an application, we obtain an asymptotic behavior of the dimer model partition function with an exponentially small error term.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Multiparameter Methods are the New Field in Statistics

During the last decade statistical problems of a new kind have appeared more and more often, in which the dimensionality of observations is large, and the sample size is small or comparable with the dimensionality of observations. These problems may be characterized as multiparameter problems. The theory of multiparameter analysis, proposed by A.N.Kolmogorov and supported by the studies on the spectral theory of random matrices of V. A.Marchenko, L. A.Pastur, V. L.Girko, and others, revealed some specific phenomena appearing in statistics with a large number of weakly dependent variables. Particularly, there are stable relations between the principal parts of parameter set functions and the set of observed variables, which may be used to improve the statistical analysis. The use of these phenomena allows one to develop a thorough, always stable, and approximately optimal (irrespective of samples) versions of mostly used statistical procedures. The multiparameter versions of the discriminant analysis are of special interest.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On Solutions to the Schwarz Problem in a Disk in the Three-Dimensional Case

We consider the Schwarz problem for first order elliptic systems in the plane. We obtain the conditions on three– and two-dimensional matrices J admitting nondiagonal Jordan form under which a solution to the Schwarz problem in an arbitrary disk exists and is unique in Hölder classes. We describe an algorithm for constructing the solution. Bibliography: 5 titles.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Sufficient Condition for Consistency of Infinite Systems

Based on the theory of double series, we obtain a sufficient condition for the existence of strictly partial solutions to infinite systems of linear algebraic equations. We prove series expansion theorems for infinite determinants of Gaussian infinite matrices. Examples of application of the proposed condition are given.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Discretization Procedure for Linear Dynamical Systems

We describe in detail a method of construction of a discrete linear dynamical model of a controllable object in the recurrent Cauchy form corresponding to an initial continuous dynamical system. We describe discretization algorithms for free and forced motion of a linear continuous dynamical system and propose methods of construction of the state, control, and perturbation transition matrices.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On Stability of Linear Systems with Impulsive Action at the Matrix

We discuss properties of stability and asymptotic stability of solutions to linear systems of differential equations with generalized actions in matrices of systems. We obtain sufficient conditions that guarantee the stability and asymptotic stability of solutions to these system. A distinctive feature of systems considered is the fact that the right-hand sides of systems contain the ill-posed operation of multiplication of discontinuous functions by generalized functions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Oscillation, Rotation, and Wandering of Solutions to Linear Differential Systems

For solutions of a linear system on the semi-axis, we introduce a series of Lyapunov exponents that describe the oscillation, rotation, and wandering properties of these solutions. In the case of systems with constant matrices, these exponents are closely related to the imaginary parts of the eigenvalues. We examine the problem on the existence of a similar relationship in the case of piecewise constant of arbitrary systems.

97 MATHEMATICS AND COMPUTING↗