Numerical Approximation of Vortex Density Evolution in a Superconductor.
Styles, Vanessa
Numerical Approximation of Vortex Density Evolution in a Superconductor. C.M. Elliott & V. Styles Abstract A #12;nite volume/element approximation of a mean #12;eld model of superconducting vortices in one approximations of a two-dimensional version of the mean #12;eld model of superconducting vortices considered
Crystallization of polyethylene by modified weighted density approximation(MWDA)
Razeghizadeh, Alireza; Lavafpour, Farhad
2015-01-01T23:59:59.000Z
In this article, we use the modified weighted density approximation to study the crystallization of polyethylene. We also use a direct correlation function of polyethylene based on RISM theory. The free energy of a polyethylene is calculated using density functional theory. The crystallization and solid and liquid density are calculated and finally compared with the prism simulation and experimental results. That shown the result obtained by MWDA is in better agreement, compared with the experimental result than the prism.
Crystallization of polyethylene by modified weighted density approximation(MWDA)
Alireza Razeghizadeh; Vahdat Rafee; Farhad Lavafpour
2015-02-07T23:59:59.000Z
In this article, we use the modified weighted density approximation to study the crystallization of polyethylene. We also use a direct correlation function of polyethylene based on RISM theory. The free energy of a polyethylene is calculated using density functional theory. The crystallization and solid and liquid density are calculated and finally compared with the prism simulation and experimental results. That shown the result obtained by MWDA is in better agreement, compared with the experimental result than the prism.
Quigg, Chris; /Fermilab
2005-02-01T23:59:59.000Z
It is a pleasure to be part of the SLAC Summer Institute again, not simply because it is one of the great traditions in our field, but because this is a moment of great promise for particle physics. I look forward to exploring many opportunities with you over the course of our two weeks together. My first task in talking about Nature's Greatest Puzzles, the title of this year's Summer Institute, is to deconstruct the premise a little bit.
Relativistic Coulomb excitation within Time Dependent Superfluid Local Density Approximation
I. Stetcu; C. Bertulani; A. Bulgac; P. Magierski; K. J. Roche
2015-01-13T23:59:59.000Z
Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus $^{238}$U. The approach is based on Superfluid Local Density Approximation (SLDA) formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We have computed the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance and giant quadrupole modes were excited during the process. The one body dissipation of collective dipole modes is shown to lead a damping width $\\Gamma_\\downarrow \\approx 0.4$ MeV and the number of pre-equilibrium neutrons emitted has been quantified.
Error Analysis of Free Probability Approximations to the Density of States of Disordered Systems
Chen, Jiahao
Theoretical studies of localization, anomalous diffusion and ergodicity breaking require solving the electronic structure of disordered systems. We use free probability to approximate the ensemble-averaged density of states ...
The low-energy nuclear density of states and the saddle point approximation
Sanjay K. Ghosh; Byron K. Jennings
2001-07-30T23:59:59.000Z
The nuclear density of states plays an important role in nuclear reactions. At high energies, above a few MeV, the nuclear density of states is well described by a formula that depends on the smooth single particle density of states at the Fermi surface, the nuclear shell correction and the pairing energy. In this paper we present an analysis of the low energy behaviour of the nuclear density of states using the saddle point approximation and extensions to it. Furthermore, we prescribe a simple parabolic form for excitation energy, in the low energy limit, which may facilitate an easy computation of level densities.
Nishikawa, Takeshi, E-mail: nishikawa.takeshi@okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan)
2014-07-15T23:59:59.000Z
Most conventional atomic models in a plasma do not treat the effect of the plasma on the free-electron state density. Using a nearest neighbor approximation, the state densities in hydrogenic plasmas for both bound and free electrons were evaluated and the effect of the plasma on the atomic model (especially for the state density of the free electron) was studied. The model evaluates the electron-state densities using the potential distribution formed by the superposition of the Coulomb potentials of two ions. The potential from one ion perturbs the electronic state density on the other. Using this new model, one can evaluate the free-state density without making any ad-hoc assumptions. The resulting contours of the average ionization degree, given as a function of the plasma temperature and density, are shifted slightly to lower temperatures because of the effect of the increasing free-state density.
Relativistic equation of state at subnuclear densities in the Thomas-Fermi approximation
Zhang, Z. W.; Shen, H., E-mail: shennankai@gmail.com [School of Physics, Nankai University, Tianjin 300071 (China)
2014-06-20T23:59:59.000Z
We study the non-uniform nuclear matter using the self-consistent Thomas-Fermi approximation with a relativistic mean-field model. The non-uniform matter is assumed to be composed of a lattice of heavy nuclei surrounded by dripped nucleons. At each temperature T, proton fraction Y{sub p} , and baryon mass density ? {sub B}, we determine the thermodynamically favored state by minimizing the free energy with respect to the radius of the Wigner-Seitz cell, while the nucleon distribution in the cell can be determined self-consistently in the Thomas-Fermi approximation. A detailed comparison is made between the present results and previous calculations in the Thomas-Fermi approximation with a parameterized nucleon distribution that has been adopted in the widely used Shen equation of state.
Thermally-assisted-occupation density functional theory with generalized-gradient approximations
Chai, Jeng-Da, E-mail: jdchai@phys.ntu.edu.tw [Department of Physics, Center for Theoretical Sciences, and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)] [Department of Physics, Center for Theoretical Sciences, and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)
2014-05-14T23:59:59.000Z
We extend the recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] to generalized-gradient approximation (GGA) exchange-correlation density functionals. Relative to our previous TAO-LDA (i.e., the local density approximation to TAO-DFT), the resulting TAO-GGAs are significantly superior for a wide range of applications, such as thermochemistry, kinetics, and reaction energies. For noncovalent interactions, TAO-GGAs with empirical dispersion corrections are shown to yield excellent performance. Due to their computational efficiency for systems with strong static correlation effects, TAO-LDA and TAO-GGAs are applied to study the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, and symmetrized von Neumann entropy) of acenes with different number of linearly fused benzene rings (up to 100), which is very challenging for conventional electronic structure methods. The ground states of acenes are shown to be singlets for all the chain lengths studied here. With the increase of acene length, the singlet-triplet energy gaps, vertical ionization potentials, and fundamental gaps decrease monotonically, while the vertical electron affinities and symmetrized von Neumann entropy (i.e., a measure of polyradical character) increase monotonically.
Mussard, Bastien; Ángyán, János G
2015-01-01T23:59:59.000Z
Analytical forces have been derived in the Lagrangian framework for several random phase approximation (RPA) correlated total energy methods based on the range separated hybrid (RSH) approach, which combines a short-range density functional approximation for the short-range exchange-correlation energy with a Hartree-Fock-type long-range exchange and RPA long-range correlation. The RPA correlation energy has been expressed as a ring coupled cluster doubles (rCCD) theory. The resulting analytical gradients have been implemented and tested for geometry optimization of simple molecules and intermolecular charge transfer complexes, where intermolecular interactions are expected to have a non-negligible effect even on geometrical parameters of the monomers.
Senjean, Bruno; Jensen, Hans Jřrgen Aa; Fromager, Emmanuel
2015-01-01T23:59:59.000Z
The computation of excitation energies in range-separated ensemble density-functional theory (DFT) is discussed. The latter approach is appealing as it enables the rigorous formulation of a multi-determinant state-averaged DFT method. In the exact theory, the short-range density functional, that complements the long-range wavefunction-based ensemble energy contribution, should vary with the ensemble weights even when the density is held fixed. This weight dependence ensures that the range-separated ensemble energy varies linearly with the ensemble weights. When the (weight-independent) ground-state short-range exchange-correlation functional is used in this context, curvature appears thus leading to an approximate weight-dependent excitation energy. In order to obtain unambiguous approximate excitation energies, we simply propose to interpolate linearly the ensemble energy between equiensembles. It is shown that such a linear interpolation method (LIM) effectively introduces weight dependence effects. LIM has...
Truhlar, Donald G
Tests of the RPBE, revPBE, -HCTHhyb, B97X-D, and MOHLYP density functional approximations and 29 density functional approximations are tested against two diverse databases, one with 18 bond energies Some tests of density functionals against the representa- tive databases have already been reported.2
Oak Ridge Removes Laboratory's Greatest Source of Groundwater...
Broader source: Energy.gov (indexed) [DOE]
Workers remove the 4,000-gallon Tank W-1A, which was ORNLs greatest source of groundwater contamination. Workers remove the 4,000-gallon Tank W-1A, which was ORNL's greatest...
Dey, Debarshi
2010-01-01T23:59:59.000Z
2 1.2 Normal Distribution and Simple Linear5 1.3 Skew Normal Distribution andthe Standard Normal Density and Distribution Functions 3.1
Is climate change the greatest threat to global health?
Jones, Peter JS
Commentary Is climate change the greatest threat to global health? ANDREW PAPWORTH, MARK MASLIN for publication in October 2014 This commentary critically engages with the argument that climate change that although it is important to be aware of the risk that climate change presents, health status is caused
Mardirossian, Narbe; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Department of Chemistry, University of California, Berkeley and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, Berkeley and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2014-05-14T23:59:59.000Z
The limit of accuracy for semi-empirical generalized gradient approximation (GGA) density functionals is explored by parameterizing a variety of local, global hybrid, and range-separated hybrid functionals. The training methodology employed differs from conventional approaches in 2 main ways: (1) Instead of uniformly truncating the exchange, same-spin correlation, and opposite-spin correlation functional inhomogeneity correction factors, all possible fits up to fourth order are considered, and (2) Instead of selecting the optimal functionals based solely on their training set performance, the fits are validated on an independent test set and ranked based on their overall performance on the training and test sets. The 3 different methods of accounting for exchange are trained both with and without dispersion corrections (DFT-D2 and VV10), resulting in a total of 491 508 candidate functionals. For each of the 9 functional classes considered, the results illustrate the trade-off between improved training set performance and diminished transferability. Since all 491 508 functionals are uniformly trained and tested, this methodology allows the relative strengths of each type of functional to be consistently compared and contrasted. The range-separated hybrid GGA functional paired with the VV10 nonlocal correlation functional emerges as the most accurate form for the present training and test sets, which span thermochemical energy differences, reaction barriers, and intermolecular interactions involving lighter main group elements.
Climate change is one of the greatest threats facing us today. CICERO's mission
Johansen, Tom Henning
Climate change is one of the greatest threats facing us today. CICERO's mission is to provide reliable and comprehensive knowledge about all aspects of the climate change problem. Foto: Scanpix #12;Climate change is one of the greatest threats facing us today. CICERO's mission is to provide reliable
Cuendet, Michel
coupling vectors and compared them with results from high level MR-CISD electronic structure calculations electrons and nuclei dynamics from the adiabatic BO approximation. The knowl- edge of the NACs is therefore; published online 16 November 2010 Recently, we have proposed a scheme for the calculation of nonadiabatic
Steury, Todd D.
to tube. 5) Vortex for 15 min to break cells. 6) Add 1 ľL of 50 ľg/ľL Proteinase K to each tube. 7L eppie tube. Pellet cells by centrifugation (approximately 3 min). 2) Remove f/2 media and replace with ddH2O. Vortex and pellet cells again by centrifugation. Remove all but 25 ľL of the ddH2O. 3) Vortex
A. M. Sukhovoj; V. A. Khitrov
2011-05-30T23:59:59.000Z
In the frameworks of hypothesis of practical constancy of the neutron resonance number in small fixed intervals of neutron energy, their most probable value was determined for nucleus mass region 230approximation of the reduced neutron widths by superposition of two or four independent distributions. This was done under assumption that a set of the measured neutron amplitudes can correspond to one or to superposition of some normal distributions with non-zero average and dispersion differing from reduced neutron width. The main result of the analysis: the mean spacing and neutron strength function values can be determined only with unknown systematical uncertainty whose magnitude is determined by unknown precision of the Porter-Thomas hypothesis correspondence to concrete experimental sets of resonances and unknown experimental mean neutron widths.
Javaid, Saqib [EMMG, Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre of Physics, Islamabad (Pakistan); Javed Akhtar, M., E-mail: javedakhtar6@gmail.com [EMMG, Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)
2014-07-14T23:59:59.000Z
We have investigated the behavior of orthoferrite LaFeO{sub 3} at ambient conditions and under pressure using DFT (generalized gradient approximation (GGA))?+?U approach. Ground state electronic (band gap) and magnetic properties are considerably improved due to the Hubbard correction. Moreover, the experimentally observed pressure-driven phase transition, namely, the simultaneous occurrence of spin crossover, isostructural volume collapse, and drastic reduction in electrical resistance (electronic phase transition) is nicely described by GGA?+?U calculations. In particular, despite a sharp drop in resistance, a small band gap still remains in the low spin state indicating an insulator to semiconductor phase transition, in good agreement with the experiments but in contrast to GGA, which predicts metallic behavior in low spin state. We discuss the origin of variation in electronic structure of LaFeO{sub 3} in low spin state as obtained from GGA to GGA?+?U methods. These results emphasize the importance of correlation effects in describing the pressure-driven phase transition in LaFeO{sub 3} and other rare-earth orthoferrites.
SCIENCE SUBJECT GUIDE -I/S 100 greatest science discoveries of all time / Kendall Haven
Fletcher, Robin
SCIENCE SUBJECT GUIDE - I/S Books: 100 greatest science discoveries of all time / Kendall Haven Q180.55.D57 H349 2007 All in a day's work: careers using science / by Megan Sullivan Q149.U5 S92 2007 Analyze this!: understanding the scientific method / Susan Glass on order Assessment in science: practical
Lead in Species of Greatest Conservation Need: Free-flying Bald Eagles as Indicators
Koford, Rolf R.
Lead in Species of Greatest Conservation Need: Free-flying Bald Eagles as Indicators Principal Wildlife Grant Goals and Objectives: o Characterize lead levels in nesting and wintering Bald Eagles in Iowa State University o Compare lead exposure in free-flying eagles with eagles admitted
Einstein as the Greatest of the Nineteenth Century Physicists John D. Norton
Einstein as the Greatest of the Nineteenth Century Physicists John D. Norton Department of History://www.pitt.edu/~jdnorton This text is based on the chapter of the same name in my online textbook, Einstein for Everyone at http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/index.html Modern day writers often endow Einstein with a 21st century prescience about
Approximate Information Theory
Penny, Will
Gaussians Asymmetry Multimodality Variational Bayes Variational Free Energy Factorised Approximations Variational Energy Approximate Posteriors Nonlinear Regression Nonlinear Regression Priors Posterior Energies Variational Free Energy Factorised Approximations Variational Energy Approximate Posteriors Nonlinear
Multivariate approximation Robert Schaback
Schaback, Robert
Multivariate approximation Robert Schaback July 30, 2013 1 Synonyms Approximation by functions Approximations of functions are multivariate, if they replace functions of n 2 variables defined on a domain. 4 Overview Multivariate approximation is an extension of Approximation Theory and Approximation
Fast Approximate Convex Decomposition
Ghosh, Mukulika
2012-10-19T23:59:59.000Z
Approximate convex decomposition (ACD) is a technique that partitions an input object into "approximately convex" components. Decomposition into approximately convex pieces is both more efficient to compute than exact ...
Approximate Maximum Principle for Discrete Approximations of ...
2012-03-20T23:59:59.000Z
Approximations of Optimal Control Systems with. Nonsmooth .... of any endpoint constraints on trajectories of linear one-dimensional control systems in (PN ).
Retrocommissioning's Greatest Hits
Haasl, T.; Potter, A.; Irvine, L.
2001-01-01T23:59:59.000Z
It is possible to save thousands of dollars in energy costs through a few low-cost operational adjustments but those opportunities are often hidden. Retrocommissioning is a systematic investigation process for improving and optimizing the operation...
Ayako Yoshisato; Takahiko Matsubara; Masahiro Morikawa
1997-08-11T23:59:59.000Z
Among various analytic approximations for the growth of density fluctuations in the expanding Universe, Zel'dovich approximation and its extensions in Lagrangian scheme are known to be accurate even in mildly non-linear regime. The aim of this paper is to investigate the reason why these Zel'dovich-type approximations work accurately beyond the linear regime from the following two points of view: (1) Dimensionality of the system and (2) the Lagrangian scheme on which the Zel'dovich approximation is grounded. In order to examine the dimensionality, we introduce a model with spheroidal mass distribution. In order to examine the Lagrangian scheme, we introduce the Pad\\'e approximation in Eulerian scheme. We clarify which of these aspects supports the unusual accuracy of the Zel'dovich-type approximations. We also give an implication for more accurate approximation method beyond the Zel'dovich-type approximations.
Theory&approximations Quasiparticles
Marini, Andrea
.yambo-code.org Step 1: Build-up independent particles response function electrons space of phases holes space to calculate the response function www.yambo-code.org Step 2: Towards the "real" response function level by its electronic density: change in the electronic density: Key quantity: Density response Describe
Monte Carlo Greeks for financial products via approximative transition densities
Schoenmakers, John
expansions. 2000 AMS subject classification: 60H10, 62G07, 65C05 1 Introduction Valuation methods for high
Multicriteria approximation through decomposition
Burch, C. [Carnegie Mellon Univ., Pittsburgh, PA (United States). School of Computer Sciences]|[Sandia National Labs., Albuquerque, NM (United States); Krumke, S. [Univ. of Wuerzburg (Germany). Dept. of Computer Science; Marathe, M. [Los Alamos National Lab., NM (United States); Phillips, C. [Sandia National Labs., Albuquerque, NM (United States). Applied Mathematics Dept.; Sundberg, E. [Rutgers Univ., NJ (United States). Dept. of Computer Science]|[Sandia National Labs., Albuquerque, NM (United States)
1997-12-01T23:59:59.000Z
The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of the technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. The method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) The authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing. (2) They show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.
Multicriteria approximation through decomposition
Burch, C. [Carnegie Mellon Univ., Pittsburgh, PA (United States). School of Computer Science; Krumke, S. [Univ. of Wuerzburg (Germany). Dept. of Computer Science; Marathe, M. [Los Alamos National Lab., NM (United States); Phillips, C. [Sandia National Labs., Albuquerque, NM (United States). Applied Mathematics Dept.; Sundberg, E. [Rutgers Univ., NJ (United States). Dept. of Computer Science
1998-06-01T23:59:59.000Z
The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of their technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. Their method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) the authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing; (2) they also show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.
Approximations non-recursively
ĂbrahĂĄm, Erika
) * x Regard non-recursively de#12;ned approximations fact 0 = nx -> bot fact 1 = nx -> if x else fact 0 (x 1) #3; x fact 2 = nx -> if x fact of fact should satisfy the de#12;ning equation fact = nx -> if x
Wave-mechanics and the adhesion approximation
C. J. Short; P. Coles
2006-11-22T23:59:59.000Z
The dynamical equations describing the evolution of a self-gravitating fluid of cold dark matter (CDM) can be written in the form of a Schrodinger equation coupled to a Poisson equation describing Newtonian gravity. It has recently been shown that, in the quasi-linear regime, the Schrodinger equation can be reduced to the exactly solvable free-particle Schrodinger equation. The free-particle Schrodinger equation forms the basis of a new approximation scheme -the free-particle approximation - that is capable of evolving cosmological density perturbations into the quasi-linear regime. The free-particle approximation is essentially an alternative to the adhesion model in which the artificial viscosity term in Burgers' equation is replaced by a non-linear term known as the quantum pressure. Simple one-dimensional tests of the free-particle method have yielded encouraging results. In this paper we comprehensively test the free-particle approximation in a more cosmologically relevant scenario by appealing to an N-body simulation. We compare our results with those obtained from two established methods: the linearized fluid approach and the Zeldovich approximation. We find that the free-particle approximation comprehensively out-performs both of these approximation schemes in all tests carried out and thus provides another useful analytical tool for studying structure formation on cosmological scales.
Supporting Text Approximation of the Multinomial. Using Stirling's approximation
Peterson, Carsten
Supporting Text Approximation of the Multinomial. Using Stirling's approximation n! (n/e)n 2n! . [S12] To calculate B L (^n) limN BN L (^n), we apply Stirling's formula to N!, n0!, and n1!, which that r Stirling's formula
Approximation Algorithms for Covering Problems
Koufogiannakis, Christos
2009-01-01T23:59:59.000Z
1.3.1 Sequential Algorithms . . . . . . . . . . . . .Distributed 2-approximation algorithm for CMIP 2 (Alg.2 Sequential Algorithm 2.1 The Greedy Algorithm for Monotone
Takahiko Matsubara; Ayako Yoshisato; Masahiro Morikawa
1997-08-17T23:59:59.000Z
Among several analytic approximations for the growth of density fluctuations in the expanding Universe, Zel'dovich approximation in Lagrangian coordinate scheme is known to be unusually accurate even in mildly non-linear regime. This approximation is very similar to the Pad\\'e approximation in appearance. We first establish, however, that these two are actually different and independent approximations with each other by using a model of spheroidal mass collapse. Then we propose Pad\\'e-prescribed Zel'dovich-type approximations and demonstrate, within this model, that they are much accurate than any other known nonlinear approximations.
Turbulent density fluctuations in the solar wind
Ingale, Madhusudan
2015-01-01T23:59:59.000Z
Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and quantify the relative error introduced by the approximations. We show that the regimes where GSF predictions are accurate than those of its asymptotic approximations is not only of practical relevance, but are where inner scale effects influence the estimate of the scatter-broadening. Thus we propose that GSF should henceforth be used for scatter broadening calculations and estimates of quantities characterizing density turbulence in the solar corona and solar wind. In the next part of this thesis we use measurements of density turbulence in the solar wind from previously publish observations of radio wave scattering and interplanetary scintillations. Density fluctuations are inferred using the GSF for radio scattering data and existing analysis methods for IPS. Assuming that...
Approximate Graph Products Marc Hellmutha
Stadler, Peter F.
Approximate Graph Products Marc Hellmutha , Wilfried Imrichb , Werner Kl¨ocklb , Peter F. Stadlera or fingers) can vary independently of other traits, or Email addresses: marc@bioinf.uni-leipzig.de (Marc
How Synchronisation Strategy Approximation in PEPA Implementations affects Passage Time
Imperial College, London
time densities and dis- tributions from stochastic models defined in PEPA, a stochastic process algebra. In stochastic process algebras, the synchronisation policy is important for defin- ing how different system;good approximation to underlying aggregate complex but deterministic dynamics or genuine random
How Synchronisation Strategy Approximation in PEPA Implementations affects Passage Time
Bradley, Jeremy
passage time densities and dis tributions from stochastic models defined in PEPA, a stochastic process algebra. In stochastic process algebras, the synchronisation policy is important for defin ing how, or a #12; good approximation to underlying aggregate complex but deterministic dynamics or genuine random
Planning numerical approximations Richard Power
Williams, Sandra
Planning numerical approximations Richard Power Sandra Williams 21st September 2009 #12;Table proportions (e.g., more than a quarter, 25.9 per cent) Proportions are a convenient well-defined subproblem Common in factual discourse (e.g., newspaper articles) Important for generating from data (but neglected
Burke, Kieron
Leading corrections to local approximations Attila Cangi, Donghyung Lee, Peter Elliott, and Kieron efficiency and accuracy. The original density functional theory was that of Thomas1 and Fermi2 TF , in which
Convex approximations in stochastic programming by semidefinite ...
2010-04-19T23:59:59.000Z
This experience leads us to force the convexity of the approximating quadratic ..... As we can see, the least-squares approximation works well only if the data ...
Laboratory Density Functionals
B. G. Giraud
2007-07-26T23:59:59.000Z
We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.
Marking Streets to Improve Parking Density
Xu, Chao
2015-01-01T23:59:59.000Z
Street parking spots for automobiles are a scarce commodity in most urban environments. The heterogeneity of car sizes makes it inefficient to rigidly define fixed-sized spots. Instead, unmarked streets in cities like New York leave placement decisions to individual drivers, who have no direct incentive to maximize street utilization. In this paper, we explore the effectiveness of two different behavioral interventions designed to encourage better parking, namely (1) educational campaigns to encourage parkers to "kiss the bumper" and reduce the distance between themselves and their neighbors, or (2) painting appropriately-spaced markings on the street and urging drivers to "hit the line". Through analysis and simulation, we establish that the greatest densities are achieved when lines are painted to create spots roughly twice the length of average-sized cars. Kiss-the-bumper campaigns are in principle more effective than hit-the-line for equal degrees of compliance, although we believe that the visual cues of...
The slope-dependent nuclear-symmetry energy within the effective surface approximation
J. P. Blocki; A. G. Magner; P. Ring
2015-06-08T23:59:59.000Z
The effective surface approximation is extended taking into account derivatives of the symmetry energy density per particle over the mean particle density. The isoscalar and isovector particle densities in this extended effective surface approximation are derived. The improved expressions of the surface symmetry energy, in particular, its surface tension coefficients in the sharp edged proton-neutron asymmetric nuclei take into account important gradient terms of the energy density functional. For most Skyrme forces the surface symmetry-energy constants and the corresponding neutron skins and isovector stiffnesses are calculated as functions of the Swiatecki derivative of the non-gradient term of the symmetry energy density per particle with respect to the isoscalar density. Using the analytical isovector surface energy constants in the framework of the Fermi-liquid droplet model we find energies and sum rules of the isovector giant dipole resonance structure in a reasonable agreement with the experimental data and other theoretical approaches.
The slope-dependent nuclear-symmetry energy within the effective surface approximation
Blocki, J P; Ring, P
2015-01-01T23:59:59.000Z
The effective surface approximation is extended taking into account derivatives of the symmetry energy density per particle over the mean particle density. The isoscalar and isovector particle densities in this extended effective surface approximation are derived. The improved expressions of the surface symmetry energy, in particular, its surface tension coefficients in the sharp edged proton-neutron asymmetric nuclei take into account important gradient terms of the energy density functional. For most Skyrme forces the surface symmetry-energy constants and the corresponding neutron skins and isovector stiffnesses are calculated as functions of the Swiatecki derivative of the non-gradient term of the symmetry energy density per particle with respect to the isoscalar density. Using the analytical isovector surface energy constants in the framework of the Fermi-liquid droplet model we find energies and sum rules of the isovector giant dipole resonance structure in a reasonable agreement with the experimental da...
Density functional theory for self-bound systems
Nir Barnea
2007-11-06T23:59:59.000Z
The density functional theory is extended to account for self-bound systems. To this end the Hohenberg-Kohn theorem is formulated for the intrinsic density and a Kohn-Sham like procedure for an $N$--body system is derived using the adiabatic approximation to account for the center of mass motion.
Frogel, Jay A
2010-01-01T23:59:59.000Z
This paper is based on the 100 most cited papers in astronomy for each year from 2000 to 2009 and from 1995 and 1990. The main findings are: The total number of authors of the top 100 articles per year has more than tripled. This is seen most strongly in papers with more than 6 authors. The yearly number of papers with 5 or fewer authors has declined over the same time period. The most highly cited papers tend to have the largest number of authors and visa versa. The distribution of normalized citation counts versus ranking is constant from year to year except for the top ranked half dozen or so papers. It is closely approximated by a power law. The papers that show the most divergence from the power law all have a high number of citations and are based on large surveys. The average page length of the top 100 papers is one and a half times that for astronomy papers in general. The same 5 journals (A&A, AJ, ApJ, ApJS, and MNRAS; Nature and Science are not included here) account for 80 to 85% of the total c...
Lula, J.W.
1982-01-01T23:59:59.000Z
A formulation for low density syntactic foam desiccant, using a polyimide resin binder, glass microbubble filler, and molecular sieve desiccant powder has been developed. The formulation may be modified easily to meet specific part requirements such as density and desired moisture pickup. Some parts can be molded to size.
Approximations by Orthonormal Mapped Chebyshev Functions for ...
2014-03-12T23:59:59.000Z
a School of Mathematical Science, Xiamen University, 361005 Xiamen, China .... suitable mapping can be used to approximate functions on the whole line R (cf.
Section 2.5: Approximations Using Increments
2014-04-05T23:59:59.000Z
Feb 26, 2014 ... Lesson 19. Definition. Examples. In this lesson we will discuss a method for approximating the value of a function at a specified point.
Optimization Online - Equivalence of an Approximate Linear ...
Alejandro Toriello
2013-02-07T23:59:59.000Z
Feb 7, 2013 ... Equivalence of an Approximate Linear Programming Bound with the Held-Karp Bound for the Traveling Salesman Problem. Alejandro Toriello ...
Near approximations via general ordered topological spaces
M. Abo-Elhamayel
2014-12-27T23:59:59.000Z
Rough set theory is a new mathematical approach to imperfect knowledge. The notion of rough sets is generalized by using an arbitrary binary relation on attribute values in information systems, instead of the trivial equality relation. The topology induced by binary relations is used to generalize the basic rough set concepts. This paper studies near approximation via general ordered topological approximation spaces which may be viewed as a generalization of the study of near approximation from the topological view. The basic concepts of some increasing (decreasing) near approximations, increasing (decreasing) near boundary regions and increasing (decreasing) near accuracy were introduced and sufficiently illustrated. Moreover, proved results, implications and add examples.
Optimization Online - Probabilistic optimization via approximate p ...
W. van vAckooij
2015-05-27T23:59:59.000Z
May 27, 2015 ... Probabilistic optimization via approximate p-efficient points and bundle methods. W. van vAckooij(wim.van-ackooij ***at*** edf.fr )
Lower bounds for approximate factorizations via semidefinite ...
ABSTRACT The problem of approximately factoring a real or complex multivariate polynomial f seeks minimal perturbations ? f to the coefficients of the input ...
Blood Management Using Approximate Linear Programming
Shenoy, Prashant
Blood Management Using Approximate Linear Programming Marek Petrik and Shlomo Zilberstein January 13th, 2009 Marek Petrik and Shlomo Zilberstein () Blood Management Using Approximate Linear ProgrammingJanuary 13th, 2009 1 / 36 #12;Blood Inventory Management Problem Regional blood banks: Aggregate
APPROXIMATION RESULTS FOR REFLECTIONLESS JACOBI MATRICES
Remling, Christian
APPROXIMATION RESULTS FOR REFLECTIONLESS JACOBI MATRICES ALEXEI POLTORATSKI AND CHRISTIAN REMLING Abstract. We study spaces of reflectionless Jacobi matrices. The main theme is the following type of question: Given a reflectionless Jacobi matrix, is it possible to approximate it by other reflection- less
APPROXIMATE SIMULATION RELATIONS FOR HYBRID SYSTEMS 1
Pappas, George J.
. Pappas Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia, PA been introduced as a powerful tool for the approximation of discrete and continuous systems systems approximation. An example of application in the context of safety verification is shown. Keywords
Approximate error conjugation gradient minimization methods
Kallman, Jeffrey S
2013-05-21T23:59:59.000Z
In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.
Paho Lurie-Gregg; Jeff B. Schulte; David Roundy
2014-09-24T23:59:59.000Z
We introduce an approximation for the pair distribution function of the inhomogeneous hard sphere fluid. Our approximation makes use of our recently published averaged pair distribution function at contact which has been shown to accurately reproduce the averaged pair distribution function at contact for inhomogeneous density distributions. This approach achieves greater computational efficiency than previous approaches by enabling the use of exclusively fixed-kernel convolutions and thus allowing an implementation using fast Fourier transforms. We compare results for our pair distribution approximation with two previously published works and Monte-Carlo simulation, showing favorable results.
Statistical mechanics of the nonlinear Schroedinger equation. II. Mean field approximation
Lebowitz, J.L.; Rose, H.A.; Speer, E.R.
1989-01-01T23:59:59.000Z
The authors investigate a mean field approximation to the statistical mechanics of complex fields with dynamics governed by the nonlinear Schroedinger equation. Such fields, whose Hamiltonian is unbounded below, may model plasmas, lasers, and other physical systems. Restricting themselves to one-dimensional systems with periodic boundary conditions, we find in the mean field approximation a phase transition from a uniform regime to a regime in which the system is dominated by solitons. They compute explicitly, as a function of temperature and density (L/sup 2/ norm), the transition point at which the uniform configuration becomes unstable to local perturbations; static and dynamic mean field approximations yield the same result.
Generalized random phase approximation of soft-matter systems
Derek Frydel
2015-07-30T23:59:59.000Z
A general RPA approximation is developed within the liquid-state formalism as a systematic first step beyond the mean-field and toward a more realistic description of the weak-coupling regime. The resulting RPA is self-consistent and, in principle, valid for arbitrary particle interactions. RPA is introduced into the liquid-state framework via adiabatic connection -- by adiabatically switching on the particle interactions while keeping the particle density fixed at its physical value by means of an auxiliary external potential. Correlational free energy Fc involves a coupling-strength integral $\\int_0^1d{\\lambda}\\,h_{\\lambda}({\\bf r},{\\bf r}')$, where a correlation function of a fictitious system, $h_{\\lambda}({\\bf r},{\\bf r}')$, is obtained from the Ornstein-Zernike equation and an appropriate closure relation. The closure $c_{\\lambda}({\\bf r},{\\bf r}')=-\\beta\\lambda u({\\bf r},{\\bf r}')$ yields the RPA approximation. The coupling constant integral within Fc can alternatively be expressed as a summation of ring diagrams to infinite order, a known feature of RPA. The ring series can, in turn, be linked to a functional determinant known to be a solution of a Gaussian integral, therefore, connecting the RPA to the Gaussian type of an approximation.
J. R. Stone
2013-02-11T23:59:59.000Z
The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has lead to the necessary reliance on theoretical models. However, there remains great uncertainty in these models, which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this review the latest developments in construction of the Equation of State (EoS) of high-density matter at zero and finite temperature assuming different composition of the matter are surveyed. Critical comparison of model EoS with available observational data on neutron stars, including gravitational masses, radii and cooling patterns is presented. The effect of changing rotational frequency on the composition of neutron stars during their lifetime is demonstrated. Compatibility of EoS of high-density, low temperature compact objects and low density, high temperature matter created in heavy-ion collisions is discussed.
The Columbia Americas Greatest Power Stream
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (MillionStructural Basis of WntSupportB 18B() |PortalBroadband Heating RateThe Cold War
1987A: The greatest supernova since Kepler
Trimble, V; Trimble, V
1988-01-01T23:59:59.000Z
Woosley, S. E. , 1988b, in Supernovae 19873 in the LargeGalactic Nuclei, and Supernovae, edited by S. Hayakawa andGalactic nuclei, and Supernovae, edited by S. Hayakawa and
January 2006 The 11 Greatest Supply
Bartholdi III, John J.
project to revamp both its IT systems and its distribution facilities. This involved a new ERP system, this was perhaps SAP's first foray into the world of high volume distribution. The system was unable to handle for product movement. The company was estimating huge efficiency gains from the new systems so much so
Visualization of electronic density
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Grosso, Bastien; Cooper, Valentino R; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan
2015-01-01T23:59:59.000Z
The spatial volume occupied by an atom depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent algorithms and packages to calculate it numerically for other materials. Three-dimensional visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. In this paper, we explore several approaches to this, including the extension of an analglyphic stereo visualization application based on the AViz package for hydrogen atoms and simple molecules to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answeringmore ťinteresting physical questions about nanotube properties.Ť less
Updated: June 21, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: June 21, 2010 Diophantine approximation, irrationality and transcendence Michel] Chap. 3. See also [1] Chap. III. References [1] S. Lang, Introduction to transcendental numbers transcendants, Springer-Verlag, Berlin, 1974. Lecture Notes in Mathematics, Vol. 402. http
Approximate inference in Gaussian graphical models
Malioutov, Dmitry M., 1981-
2008-01-01T23:59:59.000Z
The focus of this thesis is approximate inference in Gaussian graphical models. A graphical model is a family of probability distributions in which the structure of interactions among the random variables is captured by a ...
Optimization of Multibody Systems using Approximation Concepts
Etman, L.F. Pascal
UNIVERSITEIT EINDHOVEN Optimization of multibody systems using approximation concepts / Lodewijk Franciscus Pascal Etman. - Eindhoven : Technische Universiteit Eindhoven, 1997. - XVIII, 140 p. - With ref concepts / crashworthiness design / vehicle suspension Druk: Universiteitsdrukkerij TU Eindhoven Support
Linear source approximation in CASMO5
Ferrer, R.; Rhodes, J. [Studsvik Scandpower, Inc., 504 Shoup Ave., Idaho Falls, ID 83402 (United States); Smith, K. [Dept. of Nuclear Science and Engineering, Massachusetts Inst. of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
2012-07-01T23:59:59.000Z
A Linear Source (LS) approximation has been implemented in the two-dimensional Method of Characteristics (MOC) transport solver in a prototype version of CASMO5. The LS approximation, which relies on the computation of trajectory-based spatial moments over source regions to obtain the linear source expansion coefficients, improves the solution accuracy relative to the 'flat' or constant source approximation. In addition, the LS formulation is capable of treating arbitrarily-shaped source regions and is compatible with standard Coarse-Mesh Finite Difference (CMFD) acceleration. Numerical tests presented in this paper for the C5G7 MOX benchmark show that, for comparable accuracy with respect to the reference solution, the LS approximation can reduce the run time by a factor of four and the memory requirements by a factor often relative to the FS scheme. (authors)
Signal approximation using the bilinear transform
Venkataraman, Archana, Ph. D. Massachusetts Institute of Technology
2007-01-01T23:59:59.000Z
This thesis explores the approximation properties of a unique basis expansion. The expansion implements a nonlinear frequency warping between a continuous-time signal and its discrete-time representation according to the ...
Polymer state approximations of Schroedinger wave functions
Klaus Fredenhagen; Felix Reszewski
2006-08-25T23:59:59.000Z
It is shown how states of a quantum mechanical particle in the Schroedinger representation can be approximated by states in the so-called polymer representation. The result may shed some light on the semiclassical limit of loop quantum gravity.
A fresh look at the adhesion approximation
Thomas Buchert
1997-11-04T23:59:59.000Z
I report on a systematic derivation of the phenomenological ``adhesion approximation'' from gravitational instability together with a brief evaluation of the related status of analytical modeling of large-scale structure.
Grover, William H.
We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of ...
Multiple density layered insulator
Alger, T.W.
1994-09-06T23:59:59.000Z
A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.
Vranjes, J
2015-01-01T23:59:59.000Z
Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...
Reduced Operator Approximation for Modelling Open Quantum Systems
Agnieszka Werpachowska
2015-08-05T23:59:59.000Z
We present the Reduced Operator Approximation: a simple, physically transparent and computationally efficient method of modelling open quantum systems. It employs the Heisenberg picture of the quantum dynamics, which allows us to focus on the system degrees of freedom in a natural and easy way. We describe different variants of the method, low- and high-order in the system-bath interaction operators, defining them for either general quantum harmonic oscillator baths or specialising them for independent baths with Lorentzian spectral densities. Its wide applicability is demonstrated on the examples of systems coupled to different baths (with varying system-bath interaction strength and bath memory length), and compared with the exact pseudomode and the popular quantum state diffusion approach. The method captures the decoherence of the system interacting with the bath, while conserving the total energy. Our results suggest that quantum coherence effects persist in open quantum systems for much longer times than previously thought.
Extending the Eikonal Approximation to Low Energy
Pierre Capel; Tokuro Fukui; Kazuyuki Ogata
2014-11-21T23:59:59.000Z
E-CDCC and DEA, two eikonal-based reaction models are compared to CDCC at low energy (e.g. 20AMeV) to study their behaviour in the regime at which the eikonal approximation is supposed to fail. We confirm that these models lack the Coulomb deflection of the projectile by the target. We show that a hybrid model, built on the CDCC framework at low angular momenta and the eikonal approximation at larger angular momenta gives a perfect agreement with CDCC. An empirical shift in impact parameter can also be used reliably to simulate this missing Coulomb deflection.
Approximate initial data for binary black holes
Kenneth A. Dennison; Thomas W. Baumgarte; Harald P. Pfeiffer
2006-08-26T23:59:59.000Z
We construct approximate analytical solutions to the constraint equations of general relativity for binary black holes of arbitrary mass ratio in quasicircular orbit. We adopt the puncture method to solve the constraint equations in the transverse-traceless decomposition and consider perturbations of Schwarzschild black holes caused by boosts and the presence of a binary companion. A superposition of these two perturbations then yields approximate, but fully analytic binary black hole initial data that are accurate to first order in the inverse of the binary separation and the square of the black holes' momenta.
Communication: Random phase approximation renormalized many-body perturbation theory
Bates, Jefferson E.; Furche, Filipp, E-mail: filipp.furche@uci.edu [Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025 (United States)] [Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025 (United States)
2013-11-07T23:59:59.000Z
We derive a renormalized many-body perturbation theory (MBPT) starting from the random phase approximation (RPA). This RPA-renormalized perturbation theory extends the scope of single-reference MBPT methods to small-gap systems without significantly increasing the computational cost. The leading correction to RPA, termed the approximate exchange kernel (AXK), substantially improves upon RPA atomization energies and ionization potentials without affecting other properties such as barrier heights where RPA is already accurate. Thus, AXK is more balanced than second-order screened exchange [A. Grüneis et al., J. Chem. Phys. 131, 154115 (2009)], which tends to overcorrect RPA for systems with stronger static correlation. Similarly, AXK avoids the divergence of second-order Mřller-Plesset (MP2) theory for small gap systems and delivers a much more consistent performance than MP2 across the periodic table at comparable cost. RPA+AXK thus is an accurate, non-empirical, and robust tool to assess and improve semi-local density functional theory for a wide range of systems previously inaccessible to first-principles electronic structure calculations.
Updated: May 28, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: May 28, 2010 Diophantine approximation, irrationality and transcendence Michel Waldschmidt [3] is: Theorem 121 (Lambert, 1761). For any r Q \\ {0}, the numbers tan r and er are irrational. In particular the number is irrational. The main tool is continued fractions, and the first goal of Lambert
Updated: June 16, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: June 16, 2010 Diophantine approximation, irrationality and transcendence Michel. It is known (see for instance [31] p. 25) that if k is a positive integer, if an irrational real number has, 31, 13, 1]. Definition Given a real irrational number , a function = N R>0 is an irrationality
Updated: May 16, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: May 16, 2010 Diophantine approximation, irrationality and transcendence Michel Waldschmidt of 2 We first give a geometrical proof of the irrationality of the number 2 = 1, 414 213 562 373 095 rectangle. This proves the irrationality of 2. In algebraic terms, the number x = 1 + 2 satisfies x = 2
Updated: June 1, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: June 1, 2010 Diophantine approximation, irrationality and transcendence Michel Waldschmidt on the irrationality of er when r is a non-zero rational number. Next we show how a slight modification implies.1.1 Irrationality of er for r Q If r = a/b is a rational number such that er is also rational, then e|a| is also
Updated: June 23, 2010 Diophantine approximation,
Waldschmidt, Michel
Updated: June 23, 2010 Diophantine approximation, irrationality and transcendence Michel://www.math.jussieu.fr/ miw/articles/ps/eccm.ps [5] -- , Elliptic functions and transcendence, in Surveys in number theory of and . Schneider's Theorem on the transcendence of j() (corollary 174). 11 Algebraic independence 11.1 Chudnovskii
Approximating Human Reaching Volumes Using Inverse Kinematics
Rodríguez, Inmaculada
of reach: standing reach, which is useful in computer animation where virtual humans have to interact. Introduction Virtual Humans are a valuable medium for gaining knowledge and understanding about the human bodyApproximating Human Reaching Volumes Using Inverse Kinematics I. Rodrígueza , M. Peinadoa , R
Approximate Inference and Protein-Folding
Weiss, Yair
Approximate Inference and Protein-Folding Chen Yanover and Yair Weiss School of Computer Science Side-chain prediction is an important subtask in the protein-folding problem. We show that #12;nding algorithms, including a widely used protein-folding software (SCWRL). 1 Introduction Inference in graphical
Approximations to the Distributed Activation Energy Model
Approximations to the Distributed Activation Energy Model for Pyrolysis C.P. Please, 1 M.J. Mc, then resubmitted after minor revisions in September 2002. Abstract The Distributed Activation Energy Model (DAEM effective method for estimating kinetic parameters and the distribution of activation energies. Comparison
The Observer Algorithm for Visibility Approximation
Doherty, Patrick
, with dif- ferent view ranges and grid cell sizes. By changing the size of the grid cells that the algorithm or more sentries while moving to a goal position. Algorithms for finding a covert paths in the presence of stationary and moving sentries has been devised by [5] [6]. An approximate visibility algorithm was devised
Notion of p-value Parametric Approximations
Nuel, Gregory
Notion of p-value Parametric Approximations Power Significance of an Observation in Post-Genomics G, March 7 - 10, 2011 G. NUEL Significance of an Observation in Post-Genomics #12;Notion of p Power of a test ROC and AUC Example with GWAS G. NUEL Significance of an Observation in Post-Genomics
Symbolic Test Selection Based on Approximate Analysis
Paris-Sud XI, Université de
Symbolic Test Selection Based on Approximate Analysis Bertrand Jeannet, Thierry J´eron, Vlad Rusu}@irisa.fr Abstract. This paper addresses the problem of generating symbolic test cases for testing the conformance. The challenge we consider is the selection of test cases according to a test purpose, which is here a set
Approximating Power Indices --Theoretical and Empirical Analysis
Rosenschein, Jeff
, by providing lower bounds for both deter- ministic and randomized algorithms for calculating power indices. WeApproximating Power Indices -- Theoretical and Empirical Analysis Yoram Bachrach School and Computer Science, The Hebrew University, Jerusalem, Israel Amin Saberi Department of Management Science
Exact and Approximate REML for Heteroscedastic Regression
Smyth, Gordon K.
Exact and Approximate REML for Heteroscedastic Regression Gordon K. Smyth Department of Mathematics, the above het- eroscedastic regression model is the most general model of the type considered by LN98 and SV to estimate the het- eroscedastic regression model by way of two coupled generalized linear models
Thermodynamics of the low density excluded volume hadron gas
Zalewski, Kacper
2015-01-01T23:59:59.000Z
We discuss the influence of the excluded volume of hadrons on macroscopic variables and thermal parameters of the hadron gas at finite temperature and chemical potential in the low density approximation. Based solely on elementary thermodynamics we show that when the excluded volume grows at constant temperature, pressure, and number of particles, the overall volume increases just as much as the excluded volume, while the entropy and energy remain unchanged. The growth of the chemical potentials is equal to the work needed to create the respective excluded volumes. Consequently, the bulk density functions of a gas with excluded volume are expressed by the corresponding variables in a system of point particles with the shifted chemical potentials. Our results are fully consistent with the previous findings obtained upon applications of more advanced methods of statistical physics. A validity limit for the low density approximation is derived and discussed in the context of the hadron gas created in heavy ion c...
Thermodynamics of the low density excluded volume hadron gas
Kacper Zalewski; Krzysztof Redlich
2015-07-20T23:59:59.000Z
We discuss the influence of the excluded volume of hadrons on macroscopic variables and thermal parameters of the hadron gas at finite temperature and chemical potential in the low density approximation. Based solely on elementary thermodynamics we show that when the excluded volume grows at constant temperature, pressure, and number of particles, the overall volume increases just as much as the excluded volume, while the entropy and energy remain unchanged. The growth of the chemical potentials is equal to the work needed to create the respective excluded volumes. Consequently, the bulk density functions of a gas with excluded volume are expressed by the corresponding variables in a system of point particles with the shifted chemical potentials. Our results are fully consistent with the previous findings obtained upon applications of more advanced methods of statistical physics. A validity limit for the low density approximation is derived and discussed in the context of the hadron gas created in heavy ion collisions.
Pion Superfluidity and Meson Properties at Finite Isospin Density
Lianyi He; Meng Jin; Pengfei Zhuang
2009-09-27T23:59:59.000Z
We investigate pion superfluidity and its effect on meson properties and equation of state at finite temperature and isospin and baryon densities in the frame of standard flavor SU(2) NJL model. In mean field approximation to quarks and random phase approximation to mesons, the critical isospin chemical potential for pion superfluidity is exactly the pion mass in the vacuum, and corresponding to the isospin symmetry spontaneous breaking, there is in the pion superfluidity phase a Goldstone mode which is the linear combination of the normal sigma and charged pion modes. We calculate numerically the gap equations for the chiral and pion condensates, the phase diagrams, the meson spectra, and the equation of state, and compare them with that obtained in other effective models. The competitions between pion superfluidity and color superconductivity at finite baryon density and between pion and kaon superfluidity at finite strangeness density in flavor SU(3) NJL model are briefly discussed.
Energy loss and (de)coherence effects beyond eikonal approximation
Liliana Apolinário; Néstor Armesto; Guilherme Milhano; Carlos A. Salgado
2014-10-21T23:59:59.000Z
The parton branching process is known to be modified in the presence of a medium. Colour decoherence processes are known to determine the process of energy loss when the density of the medium is large enough to break the correlations between partons emitted from the same parent. In order to improve existing calculations that consider eikonal trajectories for both the emitter and the hardest emitted parton, we provide in this work, the calculation of all finite energy corrections for the gluon radiation off a quark in a QCD medium that exist in the small angle approximation and for static scattering centres. Using the path integral formalism, all particles are allowed to undergo Brownian motion in the transverse plane and the offspring allowed to carry an arbitrary fraction of the initial energy. The result is a general expression that contains both coherence and decoherence regimes that are controlled by the density of the medium and by the amount of broadening that each parton acquires independently.
Weber, J. W.; Bol, A. A. [Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Sanden, M. C. M. van de [Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research (DIFFER), Nieuwegein (Netherlands)
2014-07-07T23:59:59.000Z
This work presents an improved thin film approximation to extract the optical conductivity from infrared transmittance in a simple yet accurate way. This approximation takes into account the incoherent reflections from the backside of the substrate. These reflections are shown to have a significant effect on the extracted optical conductivity and hence on derived parameters as carrier mobility and density. By excluding the backside reflections, the error for these parameters for typical chemical vapor deposited (CVD) graphene on a silicon substrate can be as high as 17% and 45% for the carrier mobility and density, respectively. For the mid- and near-infrared, the approximation can be simplified such that the real part of the optical conductivity is extracted without the need for a parameterization of the optical conductivity. This direct extraction is shown for Fourier transform infrared (FTIR) transmittance measurements of CVD graphene on silicon in the photon energy range of 3707000?cm{sup ?1}. From the real part of the optical conductivity, the carrier density, mobility, and number of graphene layers are determined but also residue, originating from the graphene transfer, is detected. FTIR transmittance analyzed with the improved thin film approximation is shown to be a non-invasive, easy, and accurate measurement and analysis method for assessing the quality of graphene and can be used for other 2-D materials.
High Energy Density Capacitors
None
2010-07-01T23:59:59.000Z
BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of todays best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.
Aggelen, Helen van [Department of Inorganic and Physical Chemistry, Ghent University, Ghent (Belgium) [Department of Inorganic and Physical Chemistry, Ghent University, Ghent (Belgium); Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Yang [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Weitao [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)
2014-05-14T23:59:59.000Z
Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H{sub 2}, and eliminates delocalization errors in H{sub 2}{sup +} and other single-bond systems. It gives surprisingly good non-bonded interaction energies competitive with the ph-RPA with the correct R{sup ?6} asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.
Corrections to Thomas-Fermi densities at turning points and beyond
Raphael F. Ribeiro; Donghyung Lee; Attila Cangi; Peter Elliott; Kieron Burke
2015-02-25T23:59:59.000Z
Uniform semiclassical approximations for the number and kinetic-energy densities are derived for many non-interacting fermions in one-dimensional potentials with two turning points. The resulting simple, closed-form expressions contain the leading corrections to Thomas-Fermi theory, involve neither sums nor derivatives, are spatially uniform approximations, and are exceedingly accurate.
A numerical approximation to distribution function
Tuttle, Keith Allan
1977-01-01T23:59:59.000Z
then is to approximate F(Y) numerically. We sub- divide the unit cube Q into N cubes eqch of length h I/N on a n n side. Within each individual subcube Q , we will define an affine approximation to f, W = g(x , . . . , x ), which requires the gradient of 1' ' 'n our... & h/2, k k i + 1/2 2 n k k = 1, 2, . . . , n]. Let f(x) f C [Q ] the space of twice continuously n differentiable functions on Q , and define the auxiliary function g(x) as the tangent to f at x. i + 1 2 for x f Q. . That is, if x I Q i (x) f (x1 2...
VISCOSITY AND RELAXATION APPROXIMATIONS FOR HYPERBOLIC SYSTEMS OF CONSERVATION LAWS
Tzavaras, Athanasios E.
VISCOSITY AND RELAXATION APPROXIMATIONS FOR HYPERBOLIC SYSTEMS deal with the approximation of conservation * *laws via viscosity or relaxation. The following topics are covered: The general structure of viscosity and relaxation approximations is discu
Nonlinear adaptive control using radial basis function approximants
Petersen, Jerry Lee
1993-01-01T23:59:59.000Z
The purpose of this research is to present an adaptive control strategy using the radial basis function approximation method. Surface approximation methods using radial basis function approximants will first be discussed. The Hamiltonian dynamical...
Orthogonal Polynomial Approximation in Higher Dimensions: Applications in Astrodynamics
Bani Younes, Ahmad H.
2013-08-05T23:59:59.000Z
harmonic series by a family of locally precise orthogonal polynomial approximations for efficient computation. A method is introduced which adapts the approximation degree radially, compatible with the truth that the highest degree approximations (to...
Approximating spheroid inductive responses using spheres
Smith, J. Torquil; Morrison, H. Frank
2003-12-12T23:59:59.000Z
The response of high permeability ({mu}{sub r} {ge} 50) conductive spheroids of moderate aspect ratios (0.25 to 4) to excitation by uniform magnetic fields in the axial or transverse directions is approximated by the response of spheres of appropriate diameters, of the same conductivity and permeability, with magnitude rescaled based on the differing volumes, D.C. magnetizations, and high frequency limit responses of the spheres and modeled spheroids.
Semiclassical approximation in Batalin-Vilkovisky formalism
Albert Schwarz
1992-10-23T23:59:59.000Z
The geometry of supermanifolds provided with $Q$-structure (i.e. with odd vector field $Q$ satisfying $\\{ Q,Q\\} =0$), $P$-structure (odd symplectic structure ) and $S$-structure (volume element) or with various combinations of these structures is studied. The results are applied to the analysis of Batalin-Vilkovisky approach to the quantization of gauge theories. In particular the semiclassical approximation in this approach is expressed in terms of Reidemeister torsion.
Compressed Indexes for Approximate String Matching
Sung, Wing-Kin Ken"
Compressed Indexes for Approximate String Matching Ho-Leung Chan1 Tak-Wah Lam1, Wing-Kin Sung2 Siu the index space to O(n log n). Huynh et al. [10] and Lam et al. [11] further compressed the index to O,wongss}@comp.nus.edu.sg Abstract. We revisit the problem of indexing a string S[1..n] to support searching all substrings
Approximate convex decomposition and its applications
Lien, Jyh-Ming
2009-05-15T23:59:59.000Z
Approved by: Chair of Committee, Nancy M. Amato Committee Members, Ergun Akleman Ricardo Gutierrez-Osuna Donald H. House John C. Keyser Head of Department, Valerie E. Taylor December 2006 Major Subject: Computer Science iii ABSTRACT Approximate Convex...-Yen Li, for teaching me about research. I would like to thank my committee members, John Keyser, Donald House, Ergun Akleman, and Ricardo Gutierrez-Osuna, who supported me through this challenging journey. I would like to thank everyone in the Algorithms...
WKB Approximation to the Power Wall
F. D. Mera; S. A. Fulling; J. D. Bouas; K. Thapa
2013-03-28T23:59:59.000Z
We present a semiclassical analysis of the quantum propagator of a particle confined on one side by a steeply, monotonically rising potential. The models studied in detail have potentials proportional to $x^{\\alpha}$ for $x>0$; the limit $\\alpha\\to\\infty$ would reproduce a perfectly reflecting boundary, but at present we concentrate on the cases $\\alpha =1$ and 2, for which exact solutions in terms of well known functions are available for comparison. We classify the classical paths in this system by their qualitative nature and calculate the contributions of the various classes to the leading-order semiclassical approximation: For each classical path we find the action $S$, the amplitude function $A$ and the Laplacian of $A$. (The Laplacian is of interest because it gives an estimate of the error in the approximation and is needed for computing higher-order approximations.) The resulting semiclassical propagator can be used to rewrite the exact problem as a Volterra integral equation, whose formal solution by iteration (Neumann series) is a semiclassical, not perturbative, expansion. We thereby test, in the context of a concrete problem, the validity of the two technical hypotheses in a previous proof of the convergence of such a Neumann series in the more abstract setting of an arbitrary smooth potential. Not surprisingly, we find that the hypotheses are violated when caustics develop in the classical dynamics; this opens up the interesting future project of extending the methods to momentum space.
Low density microcellular foams
LeMay, J.D.
1991-11-19T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.
Oberacker, V E
2015-01-01T23:59:59.000Z
In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1991-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1992-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
V. E. Oberacker; A. S. Umar
2015-02-13T23:59:59.000Z
In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.
Low density microcellular foams
Aubert, James H. (Albuquerque, NM); Clough, Roger L. (Albuquerque, NM); Curro, John G. (Placitas, NM); Quintana, Carlos A. (Albuquerque, NM); Russick, Edward M. (Albuquerque, NM); Shaw, Montgomery T. (Mansfield Center, CT)
1987-01-01T23:59:59.000Z
Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.
Low density microcellular foams
Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.
1985-10-02T23:59:59.000Z
Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.
BLOCK DIAGONALLY DOMINANT POSITIVE DEFINITE APPROXIMATE FILTERS AND SMOOTHERS
BLOCK DIAGONALLY DOMINANT POSITIVE DEFINITE APPROXIMATE FILTERS AND SMOOTHERS Running title: BLOCKĆciently small as to preclude the loss of positive de#12;niteness in the approximate equations. Therefore
BLOCK DIAGONALLY DOMINANT POSITIVE DEFINITE APPROXIMATE FILTERS AND SMOOTHERS
BLOCK DIAGONALLY DOMINANT POSITIVE DEFINITE APPROXIMATE FILTERS AND SMOOTHERS Running title: BLOCK the loss of positive definiteness in the approximate equations. Therefore previous analyses have
Kernel density estimation of a multidimensional efficiency profile
Anton Poluektov
2014-11-20T23:59:59.000Z
Kernel density estimation is a convenient way to estimate the probability density of a distribution given the sample of data points. However, it has certain drawbacks: proper description of the density using narrow kernels needs large data samples, whereas if the kernel width is large, boundaries and narrow structures tend to be smeared. Here, an approach to correct for such effects, is proposed that uses an approximate density to describe narrow structures and boundaries. The approach is shown to be well suited for the description of the efficiency shape over a multidimensional phase space in a typical particle physics analysis. An example is given for the five-dimensional phase space of the $\\Lambda_b^0\\to D^0p\\pi$ decay.
Sensitivity approximation for robust stability and tracking
McLean, Chris Steven
1984-01-01T23:59:59.000Z
) Norman W. Na gle (Member) Don R. Halverson (Member) William B. Jones (Head of Department) May 1984 1n Abstract Sensitivity Approximation for Robust Stability and Tracking. (May 1984) Chris Steven McLean, B. S, , Louisiana Tech University... indispensable to the completion of this thesis. I would like to thank Dr. S. P. Bhattacharyya for introducing me to the wonders of automatic control. I also would like to thank Dr. D. R. Halverson and Dr. N. W. Naugle for serving on my committee, Dr. John...
Recycling Authorizations: Toward Secondary and Approximate Authorizations Model
of matching best suitable approximate authorizations. 1 Introduction Although, every authorization decision
Bethe free energy, Kikuchi approximations and belief propagation
Bethe free energy, Kikuchi approximations and belief propagation algorithms Jonathan S. Yedidia to a stationary point of an approximate free energy, known as the Bethe free energy in statis- tical physics- curate free energy approximations, of which Bethe's approximation is the simplest. Exploiting
The Background Field Approximation in (quantum) cosmology
R. Parentani
1998-03-12T23:59:59.000Z
We analyze the Hamilton-Jacobi action of gravity and matter in the limit where gravity is treated at the background field approximation. The motivation is to clarify when and how the solutions of the Wheeler-DeWitt equation lead to the Schr\\"odinger equation in a given background. To this end, we determine when and how the total action, solution of the constraint equations of General Relativity, leads to the HJ action for matter in a given background. This is achieved by comparing two neighboring solutions differing slightly in their matter energy content. To first order in the change of the 3-geometries, the change of the gravitational action equals the integral of the matter energy evaluated in the background geometry. Higher order terms are governed by the ``susceptibility'' of the geometry. These classical properties also apply to quantum cosmology since the conditions which legitimize the use of WKB gravitational waves are concomitant with those governing the validity of the background field approximation.
The validity of the Background Field Approximation
R. Parentani
1997-10-10T23:59:59.000Z
In the absence of a tractable theory of quantum gravity, quantum matter field effects have been so far computed by treating gravity at the Background Field Approximation. The principle aim of this paper is to investigate the validity of this approximation which is not specific to gravity. To this end, for reasons of simplicity and clarity, we shall compare the descriptions of thermal processes induced by constant acceleration (i.e. the Unruh effect) in four dynamical frameworks. In this problem, the position of the ``heavy'' accelerated system plays the role of gravity. In the first framework, the trajectory is treated at the BFA: it is given from the outset and unaffected by radiative processes. In the second one, recoil effects induced by these emission processes are taken into account by describing the system's position by WKB wave functions. In the third one, the accelerated system is described by second quantized fields and in the fourth one, gravity is turned on. It is most interesting to see when and why transitions amplitudes evaluated in different frameworks but describing the same process do agree. It is indeed this comparison that determines the validity of the BFA. It is also interesting to notice that the abandonment of the BFA delivers new physical insights concerning the processes. For instance, in the fourth framework, the ``recoils'' of gravity show that the acceleration horizon area acts as an entropy in delivering heat to accelerated systems.
The local potential approximation in quantum gravity
Dario Benedetti; Francesco Caravelli
2012-10-09T23:59:59.000Z
Within the context of the functional renormalization group flow of gravity, we suggest that a generic f(R) ansatz (i.e. not truncated to any specific form, polynomial or not) for the effective action plays a role analogous to the local potential approximation (LPA) in scalar field theory. In the same spirit of the LPA, we derive and study an ordinary differential equation for f(R) to be satisfied by a fixed point of the renormalization group flow. As a first step in trying to assess the existence of global solutions (i.e. true fixed point) for such equation, we investigate here the properties of its solutions by a comparison of various series expansions and numerical integrations. In particular, we study the analyticity conditions required because of the presence of fixed singularities in the equation, and we develop an expansion of the solutions for large R up to order N=29. Studying the convergence of the fixed points of the truncated solutions with respect to N, we find a characteristic pattern for the location of the fixed points in the complex plane, with one point stemming out for its stability. Finally, we establish that if a non-Gaussian fixed point exists within the full f(R) approximation, it corresponds to an R^2 theory.
Temperature Power Law of Equilibrium Heavy Particle Density
Sh. Matsumoto; M. Yoshimura
1999-10-19T23:59:59.000Z
A standard calculation of the energy density of heavy stable particles that may pair-annihilate into light particles making up thermal medium is performed to second order of coupling, using the technique of thermal field theory. At very low temperatures a power law of temperature is derived for the energy density of the heavy particle. This is in sharp contrast to the exponentially suppressed contribution estimated from the ideal gas distribution function. The result supports a previous dynamical calculation based on the Hartree approximation, and implies that the relic abundance of dark matter particles is enhanced compared to that based on the Boltzmann equation.
Minimization of Fractional Power Densities
Minimization of Fractional Power Densities. Robert Hardt, Rice University. Abstract: A k dimensional rectifiable current is given by an oriented k dimensional
Approximate Stokes Drift Profiles in Deep Water
Breivik, Řyvind; Bidlot, Jean-Raymond
2014-01-01T23:59:59.000Z
A deep-water approximation to the Stokes drift velocity profile is explored as an alternative to the monochromatic profile. The alternative profile investigated relies on the same two quantities required for the monochromatic profile, viz the Stokes transport and the surface Stokes drift velocity. Comparisons with parametric spectra and profiles under wave spectra from the ERA-Interim reanalysis and buoy observations reveal much better agreement than the monochromatic profile even for complex sea states. That the profile gives a closer match and a more correct shear has implications for ocean circulation models since the Coriolis-Stokes force depends on the magnitude and direction of the Stokes drift profile and Langmuir turbulence parameterizations depend sensitively on the shear of the profile. The alternative profile comes at no added numerical cost compared to the monochromatic profile.
Conductivity Recovery from One Component of the Current Density
Carlos Montalto
2014-08-02T23:59:59.000Z
We prove global injectivity and H\\"older stability in the reconstruction of an isotopic conductivity in the electrostatic approximation of Maxwell's equations, from the information of one voltage at the boundary and one (well chosen) component of the current density. We study the full and partial data problem. We work under the assumption that the voltage potential has no critical points inside the domain.
A Conjecture about the Density of Prime Numbers
L. A. Amarante Ribeiro
2008-03-04T23:59:59.000Z
We present in this work a heuristic expression for the density of prime numbers. Our expression leads to results which possesses approximately the same precision of the Riemann's function in the domain that goes from 2 to 1010 at least. Instead of using a constant as was done by Legendre and others in the formula of Gauss, we try to adjust the data through a function. This function has the remarkable property: its points of discontinuity are the prime numbers.
Improved association in a classical density functional theory for water
Eric J. Krebs; Jeff B. Schulte; David Roundy
2013-09-07T23:59:59.000Z
We present a modification to our recently published SAFT-based classical density functional theory for water. We have recently developed and tested a functional for the averaged radial distribution function at contact of the hard-sphere fluid that is dramatically more accurate at interfaces than earlier approximations. We now incorporate this improved functional into the association term of our free energy functional for water, improving its description of hydrogen bonding. We examine the effect of this improvement by studying two hard solutes: a hard hydrophobic rod and a hard sphere. The improved functional leads to a moderate change in the density profile and a large decrease in the number of hydrogen bonds broken in the vicinity of the solutes.We present a modification to our recently published SAFT-based classical density functional theory for water. We have recently developed and tested a functional for the averaged radial distribution function at contact of the hard-sphere fluid that is dramatically more accurate at interfaces than earlier approximations. We now incorporate this improved functional into the association term of our free energy functional for water, improving its description of hydrogen bonding. We examine the effect of this improvement by studying two hard solutes: a hard hydrophobic rod and a hard sphere. The improved functional leads to a moderate change in the density profile and a large decrease in the number of hydrogen bonds broken in the vicinity of the solutes.
Report on some recent advances in Diophantine approximation
Waldschmidt, Michel
by linear forms Âˇ irrationality measures Âˇ transcendence criterion Âˇ criteria for algebraic inde- pendence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Rational approximation to a real number . . . . . . . . . . . . . . . . . . . . . . . . 6 1, algebraic and simultaneous approximation to a single number
VISCOSITY AND RELAXATION APPROXIMATIONS FOR HYPERBOLIC SYSTEMS OF CONSERVATION LAWS
Tzavaras, Athanasios E.
VISCOSITY AND RELAXATION APPROXIMATIONS FOR HYPERBOLIC SYSTEMS OF CONSERVATION LAWS Athanasios E. Tzavaras Abstract. These lecture notes deal with the approximation of conservation laws via viscosity or relaxation. The following topics are covered: The general structure of viscosity and relaxation
Guest Editorial Sparse Approximations in Signal and Image Processing
Paris-Sud XI, Université de
Guest Editorial Sparse Approximations in Signal and Image Processing Sparse approximation to solve many other signal processing problems, including blind source separation, feature extraction techniques to images as well as audio and biomedical signals, new efficient im- plementations of greedy
On the complexity of approximating a nash equilibrium
Daskalakis, Constantinos
2011-01-01T23:59:59.000Z
We show that computing a relative---that is, multiplicative as opposed to additive---approximate Nash equilibrium in two-player games is PPAD-complete, even for constant values of the approximation. Our result is the first ...
Density Functional Resonance Theory of Unbound Electronic Systems
Daniel L. Whitenack; Adam Wasserman
2011-06-20T23:59:59.000Z
Density Functional Resonance Theory (DFRT) is a complex-scaled version of ground-state Density Functional Theory (DFT) that allows one to calculate the resonance energies and lifetimes of metastable anions. In this formalism, the exact energy and lifetime of the lowest-energy resonance of unbound systems is encoded into a complex "density" that can be obtained via complex-coordinate scaling. This complex density is used as the primary variable in a DFRT calculation just as the ground-state density would be used as the primary variable in DFT. As in DFT, there exists a mapping of the N-electron interacting system to a Kohn-Sham system of N non-interacting particles in DFRT. This mapping facilitates self consistent calculations with an initial guess for the complex density, as illustrated with an exactly-solvable model system. Whereas DFRT yields in principle the exact resonance energy and lifetime of the interacting system, we find that neglecting the complex-correlation contribution leads to errors of similar magnitude to those of standard scattering close-coupling calculations under the bound-state approximation.
Densities and energies of nuclei in dilute matter
P. Papakonstantinou; J. Margueron; F. Gulminelli; Ad. R. Raduta
2013-05-01T23:59:59.000Z
We explore the ground-state properties of nuclear clusters embedded in a gas of nucleons with the help of Skyrme-Hartree-Fock microscopic calculations. Two alternative representations of clusters are introduced, namely coordinate-space and energy-space clusters. We parameterize their density profiles in spherical symmetry in terms of basic properties of the energy density functionals used and propose an analytical, Woods-Saxon density profile whose parameters depend, not only on the composition of the cluster, but also of the nucleon gas. We study the clusters' energies with the help of the local-density approximation, validated through our microscopic results. We find that the volume energies of coordinate-space clusters are determined by the saturation properties of matter, while the surface energies are strongly affected by the presence of the gas. We conclude that both the density profiles and the cluster energies are strongly affected by the gas and discuss implications for the nuclear EoS and related perspectives. Our study provides a simple, but microscopically motivated modeling of the energetics of clusterized matter at subsaturation densities, for direct use in consequential applications of astrophysical interest.
Communication: Self-interaction correction with unitary invariance in density functional theory
Pederson, Mark R., E-mail: mark.pederson@science.doe.gov [Office of Basic Energy Sciences, SC22.1, U.S. Department of Energy, Washington, DC 20585 (United States); Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Ruzsinszky, Adrienn [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)] [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Perdew, John P. [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States) [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)
2014-03-28T23:59:59.000Z
Standard spin-density functionals for the exchange-correlation energy of a many-electron ground state make serious self-interaction errors which can be corrected by the Perdew-Zunger self-interaction correction (SIC). We propose a size-extensive construction of SIC orbitals which, unlike earlier constructions, makes SIC computationally efficient, and a true spin-density functional. The SIC orbitals are constructed from a unitary transformation that is explicitly dependent on the non-interacting one-particle density matrix. When this SIC is applied to the local spin-density approximation, improvements are found for the atomization energies of molecules.
Viscosity and Relaxation Approximation for Hyperbolic Systems of Conservation Laws
Tzavaras, Athanasios E.
Viscosity and Relaxation Approximation for Hyperbolic Systems of Conservation Laws Athanasios E with the approximation of conservation laws via viscosity or relaxation. The following topics are covered: The general structure of viscosity and relaxation approximations is discussed, as suggested by the second law
Technical Note Variational free energy and the Laplace approximation
Daunizeau, Jean
Technical Note Variational free energy and the Laplace approximation Karl Friston,a, Jérémie October 2006 This note derives the variational free energy under the Laplace approximation, with a focus. This is relevant when using the free energy as an approximation to the log-evidence in Bayesian model averaging
Modulated power-law behaviour in Stirling's approximation
Hatton, Les
Modulated power-law behaviour in Stirling's approximation Les Hatton CISM, University of Kingston. This argument used Stirling's approximation which limits its relevance to larger component sizes. Although power to broaden Stirling's approximation to see if it corresponds with the departures from power-law observed
BUILDING SURROGATE MODELS BASED ON DETAILED AND APPROXIMATE SIMULATIONS
Seepersad, Carolyn Conner
- Page 1 - BUILDING SURROGATE MODELS BASED ON DETAILED AND APPROXIMATE SIMULATIONS Zhiguang Qian is taken to integrate data from approximate and detailed simulations to build a surrogate model approximate simulations form the bulk of the data, and they are used to build a model based on a Gaussian
Smoluchowski-Kramers approximation in the case of variable friction
Mark Freidlin; Wenqing Hu
2012-03-03T23:59:59.000Z
We consider the small mass asymptotics (Smoluchowski-Kramers approximation) for the Langevin equation with a variable friction coefficient. The limit of the solution in the classical sense does not exist in this case. We study a modification of the Smoluchowski-Kramers approximation. Some applications of the Smoluchowski-Kramers approximation to problems with fast oscillating or discontinuous coefficients are considered.
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J. [Univ. of Chicago, IL (United States)
1993-12-01T23:59:59.000Z
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Low density carbonized composite foams
Kong, Fung-Ming (Pleasanton, CA)
1991-01-01T23:59:59.000Z
A carbonized composite foam having a density less than about 50 mg/cm.sup.3 and individual cell sizes no greater than about 1 .mu.m in diameter is described, and the process of making it.
High Energy Density Laboratory Plasmas
to IFE #12;5 The PorDolio FY 2012 1. High Energy Density (HED) Hydrodynamics (HYDRO SBIR IFE Technology Small-Business JS-1 JS-2 JS-3 Lab-DS ECA's Facili
Low density metal hydride foams
Maienschein, Jon L. (Oakland, CA); Barry, Patrick E. (Pleasant Hill, CA)
1991-01-01T23:59:59.000Z
Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.
Maximum-likelihood density modification
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Structural Biology Group, Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2000-08-01T23:59:59.000Z
A likelihood-based density modification approach is developed that can incorporate expected electron-density information from a wide variety of sources. A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ?), Acta Cryst. D55, 18631871].
Physical approximations for the nonlinear evolution of perturbations in dark energy scenarios
L. R. Abramo; R. C. Batista; L. Liberato; R. Rosenfeld
2008-06-20T23:59:59.000Z
The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy as well, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model, and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.
Abramo, L. R.; Batista, R. C. [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970, Sao Paulo (Brazil); Liberato, L.; Rosenfeld, R. [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Pamplona 145, 01405-900, Sao Paulo (Brazil)
2009-01-15T23:59:59.000Z
The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.
Upgrading of biorenewables to high energy density fuels
Gordon, John C [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Chen, Weizhong [Los Alamos National Laboratory; Currier, Robert P [Los Alamos National Laboratory; Dirmyer, Matthew R [Los Alamos National Laboratory; John, Kevin D [Los Alamos National Laboratory; Kim, Jin K [Los Alamos National Laboratory; Keith, Jason [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Pierpont, Aaron W [Los Alamos National Laboratory; Silks Ill, L. A. "" Pete [Los Alamos National Laboratory; Smythe, Mathan C [Los Alamos National Laboratory; Sutton, Andrew D [Los Alamos National Laboratory; Taw, Felicia L [Los Alamos National Laboratory; Trovitch, Ryan J [Los Alamos National Laboratory; Vasudevan, Kalyan V [Los Alamos National Laboratory; Waidmann, Christopher R [Los Alamos National Laboratory; Wu, Ruilian [Los Alamos National Laboratory; Baker, R. Thomas [UNIV OF OTTAWWA; Schlaf, Marcel [UNIV OF GUELPH
2010-12-07T23:59:59.000Z
According to a recent report, lignocellulose is the most abundant renewable biological resource on earth, with an annual production of {approx} 200 x 10{sup 9} tons. Conversion of lignocellulosics derived from wood, agricultural wastes, and woody grasses into liquid fuels and value-added chemical feedstocks is an active area of research that has seen an explosion of effort due to the need to replace petroleum based sources. The carbohydrates D-glucose (C{sub 6}), L-arabinose (C{sub 5}), and D-xylose (C{sub 5}) are readily obtained from the hydrolysis of lignocellulose and constitute the most abundant renewable organic carbon source on the planet. Because they are naturally produced on such a large scale, these sugars have the greatest potential to displace petrochemical derived transportation fuel. Recent efforts in our laboratories aimed towards the production of high energy density transportation fuels from carbohydrates have been structured around the parameters of selective carbohydrate carbon chain extension chemistries, low reaction temperatures, and the desired use of water or neat substrate as the solvent. Some of our efforts in this regard will be presented.
Partial level density of the n-quasiparticle excitations in the nuclei of the 39< A <201 region
A. M. Sukhovoj; V. A. Khitrov
2005-12-16T23:59:59.000Z
Level density and radiative strength functions are obtained from the analysis of two-step cascades intensities following the thermal neutrons capture. The data on level density are approximated by the sum of the partial level densities corresponding to n quasiparticles excitation. The most probable values of the collective enhancement factor of the level density are found together with the thresholds of the next Cooper nucleons pair breaking. These data allow one to calculate the level density of practically any nucleus in given spin window in the framework of model concepts, taking into account all known nuclear excitation types. The presence of an approximation results discrepancy with theoretical statements specifies the necessity of rather essentially developing the level density models. It also indicates the possibilities to obtain the essentially new information on nucleon correlation functions of the excited nucleus from the experiment.
Cosmic density and velocity fields in Lagrangian perturbation theory
Mikel Susperregi; Thomas Buchert
1997-08-04T23:59:59.000Z
A first- and second-order relation between cosmic density and peculiar-velocity fields is presented. The calculation is purely Lagrangian and it is derived using the second-order solutions of the Lagrange-Newton system obtained by Buchert & Ehlers. The procedure is applied to two particular solutions given generic initial conditions. In this approach, the continuity equation yields a relation between the over-density and peculiar-velocity fields that automatically satisfies Euler's equation because the orbits are derived from the Lagrange-Newton system. This scheme generalizes some results obtained by Nusser et al. (1991) in the context of the Zel'dovich approximation. As opposed to several other reconstruction schemes, in this approach it is not necessary to truncate the expansion of the Jacobian given by the continuity equation in order to calculate a first- or second-order expression for the density field. In these previous schemes, the density contrast given by (a) the continuity equation and (b) Euler's equation are mutually incompatible. This inconsistency arises as a consequence of an improper handling of Lagrangian and Eulerian coordinates in the analysis. Here, we take into account the fact that an exact calculation of the density is feasible in the Lagrangian picture and therefore an accurate and consistent description is obtained.
General relativistic corrections to $N$-body simulations and the Zel'dovich approximation
Fidler, Christian; Tram, Thomas; Crittenden, Robert; Koyama, Kazuya; Wands, David
2015-01-01T23:59:59.000Z
The initial conditions for $N$-body simulations are usually generated by applying the Zel'dovich approximation to the initial displacements of the particles using an initial power spectrum of density fluctuations generated by an Einstein-Boltzmann solver. We show that the initial displacements generated in this way generally receive a first-order relativistic correction. We define a new gauge, the $N$-body gauge, in which this relativistic correction is absent and show that a conventional Newtonian $N$-body simulation includes all first-order relativistic contributions if we identify the coordinates in Newtonian simulations with those in the $N$-body gauge.
Density functional theory of freezing for soft interactions in two dimensions
Sven van Teeffelen; Christos N. Likos; Norman Hoffmann; Hartmut Löwen
2006-04-18T23:59:59.000Z
A density functional theory of two-dimensional freezing is presented for a soft interaction potential that scales as inverse cube of particle distance. This repulsive potential between parallel, induced dipoles is realized for paramagnetic colloids on an interface, which are additionally exposed to an external magnetic field. An extended modified weighted density approximation which includes correct triplet correlations in the liquid state is used. The theoretical prediction of the freezing transition is in good agreement with experimental and simulation data.
Understanding Kernel Ridge Regression: Common behaviors from simple functions to density functionals
Vu, Kevin; Li, Li; Rupp, Matthias; Chen, Brandon F; Khelif, Tarek; Müller, Klaus-Robert; Burke, Kieron
2015-01-01T23:59:59.000Z
Accurate approximations to density functionals have recently been obtained via machine learning (ML). By applying ML to a simple function of one variable without any random sampling, we extract the qualitative dependence of errors on hyperparameters. We find universal features of the behavior in extreme limits, including both very small and very large length scales, and the noise-free limit. We show how such features arise in ML models of density functionals.
Time Dependent Density Functional Theory An introduction
Botti, Silvana
Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique (ETSF) Time Dependent Density Functional Theory Palaiseau, 7 February 2012 1 / 32 #12;Outline 1 Frontiers 4 Perspectives and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory
Statistical density modification using local pattern matching
Terwilliger, Thomas C.
2007-01-23T23:59:59.000Z
A computer implemented method modifies an experimental electron density map. A set of selected known experimental and model electron density maps is provided and standard templates of electron density are created from the selected experimental and model electron density maps by clustering and averaging values of electron density in a spherical region about each point in a grid that defines each selected known experimental and model electron density maps. Histograms are also created from the selected experimental and model electron density maps that relate the value of electron density at the center of each of the spherical regions to a correlation coefficient of a density surrounding each corresponding grid point in each one of the standard templates. The standard templates and the histograms are applied to grid points on the experimental electron density map to form new estimates of electron density at each grid point in the experimental electron density map.
The Numerical Approximation of Solutions of Partial Differential ...
2009-05-05T23:59:59.000Z
i.e., instead of thinking of the approximate solution as being linear between .... Consider the mildly nonlinear two-point boundary problem given by. ?(aux )x + c(
Approximation Algorithms for the Fault-Tolerant Facility Placement Problem
Yan, Li
2013-01-01T23:59:59.000Z
5.2 Algorithm ECHS with Ratio5.3 Algorithm EBGS with RatioFormulation 2.1.3 Approximation Algorithms . 2.1.4 Bifactor
Finding approximately rank-one submatrices with the nuclear norm ...
2010-11-08T23:59:59.000Z
a word in the language, excluding common words such as articles and prepositions. The (i, j) entry of ... quality of the approximation. One class of heuristic NMF ...
ON LEAST SQUARES EUCLIDEAN DISTANCE MATRIX APPROXIMATION AND COMPLETION
in biological or engineering applications, including molecular structure analysis, protein folding problem. distance geometry, least squares approximation, matrix completion, molecular structure, protein folding
ON LEAST SQUARES EUCLIDEAN DISTANCE MATRIX APPROXIMATION AND COMPLETION
in biological or engineering applications, including molecular structure analysis, protein folding problem approximation, matrix completion, molecular structure, protein folding, conformational analysis. 1. Introduction
Automating approximate Bayesian computation by local linear regression
Thornton, Kevin R
2009-01-01T23:59:59.000Z
computation by local linear regression Kevin R Thorntonof ABC based on using a linear regression to approximate theimplements the local linear-regression approach to ABC. The
Longitudinal polarized parton densities updated
Leader, Elliot; Sidorov, Aleksander V.; Stamenov, Dimiter B. [Imperial College, Prince Consort Road, London SW7 2BW (United Kingdom); Bogoliubov Theoretical Laboratory Joint Institute for Nuclear Research 141980 Dubna (Russian Federation); Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences Blvd. Tsarigradsko Chaussee 72, Sofia 1784 (Bulgaria)
2006-02-01T23:59:59.000Z
We have reanalyzed the world data on inclusive polarized DIS, in both NLO and LO QCD, including the new HERMES and COMPASS data. The updated NLO polarized densities are given in both the MS and JET schemes. The impact of the new data on the results is discussed.
About density functional theory interpretation
Kirill Koshelev
2015-05-28T23:59:59.000Z
Two forms of relativistic density functional are derived from Dirac equation. Based on their structure analysis model of split electron is proposed. In this model electric charge and mass of electron behave like two point-like particles. It is shown that two electrons obeying this model cannot occupy the same quantum state. Empirical verification of the model is discussed.
Parametric Optimization of Artificial Neural Networks for Signal Approximation Applications
Parametric Optimization of Artificial Neural Networks for Signal Approximation Applications J. Lane.thames@gatech.edu randal.abler@gatech.edu dirk.schaefer@me.gatech.edu ABSTRACT Artificial neural networks are used to solve set of configuration parameters for artificial neural networks such that the network's approximation
L^p Bernstein Inequalities and Radial Basis Function Approximation
Ward, John P.
2012-10-19T23:59:59.000Z
proving Bernstein inequalites for the RBF approximants, we will be able to use them to derive corresponding inverse theorems. Direct theorems concerning approximation by RBFs will be the focus of Section 4 3. The abilty of Greens functions to invert di...
Fresnel approximations for acoustic fields of rectangularly symmetric sources
Mast, T. Douglas
Fresnel approximations for acoustic fields of rectangularly symmetric sources T. Douglas Masta for determining the acoustic fields of rectangularly symmetric, baffled, time-harmonic sources under the Fresnel. The expressions presented are generalized to three different Fresnel approximations that correspond, respectively
Approximate and Multipartite Quantum Correlation (Communication) Zhaohui Wei
Jain, Rahul
classical distributions or bipartite quantum states in the single-shot setting by Zhang (Proc. 3rd Innov that the cost to approximate a bipartite quantum state equals that to approximate its exact purifications, which the latter. We characterize the relationship between them by giving upper and lower bounds. 4
Tutorial, GECCO'05, Washington D.C. Fitness Approximation
Yang, Shengxiang
1 Tutorial, GECCO'05, Washington D.C. Fitness Approximation in Evolutionary Computation Yaochu Jin Honda Research Institute Europe Khaled Rasheed University of Georgia Tutorial, GECCO'05, Washington D expensive fitness evaluations Tutorial, GECCO'05, Washington D.C. Fitness Approximation Methods ˇ Problem
Uncertainty, Performance, and Model Dependency in Approximate Adaptive Nonlinear Control
Szepesvari, Csaba
Uncertainty, Performance, and Model Dependency in Approximate Adaptive Nonlinear Control M. French, and the performance of a class of approximate model based adaptive controllers is studied. An upper performance bound uncertainty model; control effort bounds require both L 2 and L 1 uncertainty models), and various structural
Technical Note Variational free energy and the Laplace approximation
Penny, Will
Technical Note Variational free energy and the Laplace approximation Karl Friston,a, Jérémie the variational free energy under the Laplace approximation, with a focus on accounting for additional model complexity induced by increasing the number of model parameters. This is relevant when using the free energy
Fast Vectorless Power Grid Verification Using an Approximate Inverse Technique
Najm, Farid N.
Fast Vectorless Power Grid Verification Using an Approximate Inverse Technique Nahi H. Abdul Ghani Department of ECE University of Toronto Toronto, Ontario, Canada f.najm@utoronto.ca ABSTRACT Power grid Aids General Terms Performance, Algorithms, Verification Keywords Power grid, voltage drop, approximate
An Approximate Inference Approach to Temporal Optimization in Optimal Control
Vijayakumar, Sethu
on iterative local approximations present a practical approach to optimal control in robotic systems. However the optimal control framework. The proposed approach, which is applicable to plants with non-linear dynamicsAn Approximate Inference Approach to Temporal Optimization in Optimal Control Konrad C. Rawlik
Pixelcuts: Scalable Approximate Illumination from Many Point Lights
Keinan, Alon
Pixelcuts: Scalable Approximate Illumination from Many Point Lights Pramook Khungurn, Thatchaphol approximate low-frequency illumination from many point lights. Its running time is O(n+mk) where n is the number of pixels, m is the number of point lights, and k is a constant the user specifies. Our algorithm
THE DIFFUSION APPROXIMATION FOR THE LINEAR BOLTZMANN EQUATION
THE DIFFUSION APPROXIMATION FOR THE LINEAR BOLTZMANN EQUATION WITH VANISHING SCATTERING COEFFICIENT equation, Diffusion approximation, Neutron transport equation, Radiative transfer equation subject, 23], neutron transport theory [27]. A typical model linear Boltzmann equation is (t +ˇ x)f(t,x,)= 1
Approximation of Axisymmetric Darcy Flow V.J. Ervin
Ervin, Vincent J.
approximation of the Darcy equations in an ax- isymmetric domain, subject to axisymmetric data. Rewriting of convergence for the RT and BDM approximations. Key words. axisymmetric flow; Darcy equation, LBB condition AMSApproximation of Axisymmetric Darcy Flow V.J. Ervin Department of Mathematical Sciences Clemson
Approximate Dynamic Programming for Networks: Fluid Models and Constraint Reduction
Veatch, Michael H.
of approximating functions for the differential cost. The first contribution of this paper is identifying new or piece-wise quadratic. Fluid cost has been used to initialize the value iteration algorithm [5Approximate Dynamic Programming for Networks: Fluid Models and Constraint Reduction Michael H
Density waves in the shearing sheet I. Swing amplification
B. Fuchs
2001-03-02T23:59:59.000Z
The shearing sheet model of a galactic disk is studied anew. The theoretical description of its dynamics is based on three building blocks: Stellar orbits, which are described here in epicyclic approximation, the collisionless Boltzmann equation determining the distribution function of stars in phase space, and the Poisson equation in order to take account of the self-gravity of the disk. Using these tools I develop a new formalism to describe perturbations of the shearing sheet. Applying this to the unbounded shearing sheet model I demonstrate again how the disturbances of the disk evolve always into `swing amplified' density waves, i.e. spiral-arm like, shearing density enhancements, which grow and decay while the wave crests swing by from leading to trailing orientation. Several examples are given how such `swing amplification' events are incited in the shearing sheet.
Properties of the Boltzmann equation in the classical approximation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Tanji, Naoto; Epelbaum, Thomas; Gelis, Francois; Wu, Bin
2014-12-01T23:59:59.000Z
We study the Boltzmann equation with elastic point-like scalar interactions in two different versions of the the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated collision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the non-renormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we consider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since onemore ťhas also access to the non-approximated result for comparison.Ť less
Properties of the Boltzmann equation in the classical approximation
Tanji, Naoto [Nishina Center, RIKEN, Wako (Japan). Theoretical Research Division; Brookhaven National Lab. (BNL), Upton, NY (United States); Epelbaum, Thomas [Institut de Physique Theorique (France); Gelis, Francois [Institut de Physique Theorique (France); Wu, Bin [Institut de Physique Theorique (France)
2014-12-01T23:59:59.000Z
We study the Boltzmann equation with elastic point-like scalar interactions in two different versions of the the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated collision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the non-renormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we consider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since one has also access to the non-approximated result for comparison.
Evolution of the angular momentum of protogalaxies from tidal torques: Zel'dovich approximation
Paolo Catelan; Tom Theuns
1996-04-15T23:59:59.000Z
The growth of the angular momentum L of protogalaxies induced by tidal torques is reconsidered within the Zel'dovich approximation. We obtain a general expression for the ensemble expectation value of the square of L in terms of the first and second invariant of the inertia tensor of the Lagrangian volume enclosing the protoobject's collapsing mass. We then specialize the formalism to the particular case in which this volume is centered on a peak of the smoothed Gaussian density field and approximated by an isodensity ellipsoid. The result is the appropriate analytical estimate for the rms angular momentum of peaks to be compared against simulations that make use of the Hoffman-Ribak algorithm to set up a constrained density field that contains a peak with given shape. Extending the work of Heavens & Peacock, we calculate the joint probability distribution function for several spin parameters and peak mass M using the distribution of peak shapes, for different initial power spectra. The values of observed specific angular momentum versus mass are well fitted by our theoretical isoprobability contours. In contrast, the observed lower values for the specific angular momentum for ellipticals of the same mass cannot be accounted for within our linear regime investigation, highlighting the importance of strongly non-linear phenomena to explain the spin of such objects.
Progress at the interface of wave-function and density-functional theories
Gidopoulos, Nikitas I. [ISIS, Rutherford Appleton Laboratory, STFC, Didcot, OX11 0QX, Oxon (United Kingdom)
2011-04-15T23:59:59.000Z
The Kohn-Sham (KS) potential of density-functional theory (DFT) emerges as the minimizing effective potential in a variational scheme that does not involve fixing the unknown single-electron density. Using Rayleigh Schroedinger (RS) perturbation theory (PT), we construct ab initio approximations for the energy difference, the minimization of which determines the KS potential directly - thereby bypassing DFT's traditional algorithm to search for the density that minimizes the total energy. From second-order RS PT, we obtain variationally stable energy differences to be minimized, solving the severe problem of variational collapse of orbital-dependent exchange-correlation functionals based on second-order RS PT.
Xi Yanbin; Liu Yue [MOE Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
2012-07-15T23:59:59.000Z
Considering different typical electron density profiles, a multi slab approximation model is built up to study the power absorption of broadband (0.75-30 GHz) electromagnetic waves in a partially ionized nonuniform magnetized plasma layer. Based on the model, the power absorption spectra for six cases are numerically calculated and analyzed. It is shown that the absorption strongly depends on the electron density fluctuant profile, the background electron number density, and the collision frequency. A potential optimum profile is also analyzed and studied with some particular parameters.
Updated Axion CDM energy density
Ji-Haeng Huh
2008-10-08T23:59:59.000Z
We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale Lambda_{QCD}, the current quark masses m_q's and the Peccei-Quinn scale F_a, including firstly introduced 1.85 factor which is from the initial overshoot.
Corrections to Thomas-Fermi Densities at Turning Points and Beyond Raphael F. Ribeiro,1
Burke, Kieron
Corrections to Thomas-Fermi Densities at Turning Points and Beyond Raphael F. Ribeiro,1 Donghyung Lee,2 Attila Cangi,3 Peter Elliott,3 and Kieron Burke1 1 Department of Chemistry, University corrections to Thomas-Fermi theory, involve neither sums nor derivatives, are spatially uniform approximations
A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*
Ceder, Gerbrand
. The effect of the framework on the physical structure and electronic structure of the organic linker initio molecular dynamics in the generalized gradient approximation to density functional theory, and calculations indicate that the sites with the strongest interaction with hydrogen are located near the Zn4O
Shulenburger, Luke; Desjarlais, M P
2015-01-01T23:59:59.000Z
Motivated by the disagreement between recent diffusion Monte Carlo calculations and experiments on the phase transition pressure between the ambient and beta-Sn phases of silicon, we present a study of the HCP to BCC phase transition in beryllium. This lighter element provides an oppor- tunity for directly testing many of the approximations required for calculations on silicon and may suggest a path towards increasing the practical accuracy of diffusion Monte Carlo calculations of solids in general. We demonstrate that the single largest approximation in these calculations is the pseudopotential approximation. After removing this we find excellent agreement with experiment for the ambient HCP phase and results similar to careful calculations using density functional theory for the phase transition pressure.
Yang, Yang [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Aggelen, Helen van [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States) [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Inorganic and Physical Chemistry, Ghent University, 9000 Ghent (Belgium); Yang, Weitao, E-mail: weitao.yang@duke.edu [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)
2013-12-14T23:59:59.000Z
Double, Rydberg, and charge transfer (CT) excitations have been great challenges for time-dependent density functional theory (TDDFT). Starting from an (N ą 2)-electron single-determinant reference, we investigate excitations for the N-electron system through the pairing matrix fluctuation, which contains information on two-electron addition/removal processes. We adopt the particle-particle random phase approximation (pp-RPA) and the particle-particle Tamm-Dancoff approximation (pp-TDA) to approximate the pairing matrix fluctuation and then determine excitation energies by the differences of two-electron addition/removal energies. This approach captures all types of interesting excitations: single and double excitations are described accurately, Rydberg excitations are in good agreement with experimental data and CT excitations display correct 1/R dependence. Furthermore, the pp-RPA and the pp-TDA have a computational cost similar to TDDFT and consequently are promising for practical calculations.
Rapid chain tracing of polypeptide backbones in electron-density maps
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2010-03-01T23:59:59.000Z
A method for rapid chain tracing of polypeptide backbones at moderate resolution is presented. A method for the rapid tracing of polypeptide backbones has been developed. The method creates an approximate chain tracing that is useful for visual evaluation of whether a structure has been solved and for use in scoring the quality of electron-density maps. The essence of the method is to (i) sample candidate C{sup ?} positions at spacings of approximately 0.6 Ĺ along ridgelines of high electron density, (ii) list all possible nonapeptides that satisfy simple geometric and density criteria using these candidate C{sup ?} positions, (iii) score the nonapeptides and choose the highest scoring ones, and (iv) find the longest chains that can be made by connecting nonamers. An indexing and storage scheme that allows a single calculation of most distances and density values is used to speed up the process. The method was applied to 42 density-modified electron-density maps at resolutions from 1.5 to 3.8 Ĺ. A total of 21 428 residues in these maps were traced in 24 CPU min with an overall r.m.s.d. of 1.61 Ĺ for C{sup ?} atoms compared with the known refined structures. The method appears to be suitable for rapid evaluation of electron-density map quality.
Modeling and numerical approximation of two-phase ...
2011-02-09T23:59:59.000Z
Feb 9, 2011 ... phase incompressible flows with matching or non-matching density. ... The interfacial dynamics of two-phase immiscible fluids have attracted.
Marushka, Viktor; Zabeida, Oleg, E-mail: oleg.zabeida@polymtl.ca; Martinu, Ludvik [Engineering Physics Department, Polytechnique Montréal, P.O. Box 6079, Downtown station, Montreal, Quebec H3C 3A7 (Canada)
2014-11-01T23:59:59.000Z
The uniformity of ion density is critical for applications relying on the ion assisted deposition technique for the fabrication of the high quality thin films. The authors propose and describe here a method allowing one to calculate the ion density distribution on spherical substrate holders under stationary and rotating conditions for different positions of the ion source. The ion beam shape was approximated by a cos{sup n} function, and the ion current density was represented by a function inversely proportional to the distance from the ion source in accordance with our experimental results. As an example, a calculation of the current density distribution on the spherical cap substrate was performed for a broad beam ion source operated with an anode current of 3?A. The authors propose an approach for process optimization with respect to the ion source position and its inclination, in terms of uniformity and absolute value of the ion current density.
Density functional theory of freezing: Analysis of crystal density
Laird, Brian Bostian; McCoy, John D.; Haymet, A. D. J.
1987-09-01T23:59:59.000Z
the natural variables are temperature, chemical potential, and volume. The pressures are set equal by varying the liquid density until the grand thermodynamic potential, flO = - pV /kT, of the solid phase equals that of the liquid phase. It should... with temperature T, volume V, and chemical potential J.L. The particles interact via a potential energy U(rl, ... ,rn ) and feel an external single particle potential ifJ (r). Defining a dimen sionless single particle effective potential by u (r) = pJ.L - pif...
Dependence of polar hole density on magnetic and solar conditions
Hoegy, W.R.; Grebowsky, J.M. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))
1991-04-01T23:59:59.000Z
The dependence of electron density in the polar F region ionization hole on solar activity, universal time (UT), magnetic activity, season, and hemisphere is studied using data from the Langmuir probes on Atmosphere Explorer C and Dynamics Explorer 2. The AE-C data were obtained during solar minimum when the 3-month average 10.7-cm solar flux index varied from 70 to 140; the DE 2 data were obtained near solar maximum when 10.7-cm solar flux index varied from 120 to 220. The polar hole is a region on the nightside of the polar cap where reduced ionization exists because of the long transport time of ionization from the dayside across the polar cap. The behavior of this region as a function of 10.7-cm solar flux (F10.7), UT, and Kp is statistically modeled for equinox, summer, and winter conditions for each hemisphere separately. The strongest dependencies are observed in F10.7 and UT; the Kp dependence is weak because it poorly represents the complexities of convection across the polar cap. A strong hemispherical difference due to the offset of the magnetic poles from the Earth's rotation axis is observed in the UT dependence of the ionization hole: there is a density minimum at about 20.3 hours UT in the south and at about 4.8 hours UT in the north; the minimum to maximum UT density variation is about a factor of 8.9 in the south and about a factor of 2.1 in the north. There is a seasonal variation in the dependence of ion density (N{sub i}) on solar flux (F10.7). Use of the relationship (N{sub i}{approximately}F10.7{sup D}) yields values of D of approximately unity (1.) in the summer polar hole and about 2.1 during equinox. There is an overall asymmetry in the density level between hemispheres; it was found that the winter hole density is about a factor of 10 greater in the north than in the south. The Utah State University time dependent ionosphere model gives similar UT behavior to that found in the AE-C and DE 2 data.
The local potential approximation in the background field formalism
I. Hamzaan Bridle; Juergen A. Dietz; Tim R. Morris
2014-03-20T23:59:59.000Z
Working within the familiar local potential approximation, and concentrating on the example of a single scalar field in three dimensions, we show that the commonly used approximation method of identifying the total and background fields, leads to pathologies in the resulting fixed point structure and the associated spaces of eigenoperators. We then show how a consistent treatment of the background field through the corresponding modified shift Ward identity, can cure these pathologies, restoring universality of physical quantities with respect to the choice of dependence on the background field, even within the local potential approximation. Along the way we point out similarities to what has been previously found in the f(R) approximation in asymptotic safety for gravity.
A multiscale approximation algorithm for the cardinality constrained knapsack problem
Krishnan, Bharath Kumar
2006-01-01T23:59:59.000Z
I develop a multiscale approximation algorithm for the cardinality constrained knapsack problem. The algorithm consists of three steps: a rounding and reduction step where a hierarchical representation of the problem data ...
Mean Field Variational Approximations in Continuous-Time Markov Processes
Friedman, Nir
Mean Field Variational Approximations in Continuous-Time Markov Processes A thesis submitted Processes . . . . . . . . . . . . . . . . . . . 18 2.3 Continuous Time Markov Processes-component Representation - Continuous Time Bayesian Networks . 24 2.3.3 Inference in Continuous Time Markov Processes
The WKB approximation for a linear potential and ceiling
Zapata, Todd Austin
2009-05-15T23:59:59.000Z
The physical problem this thesis deals with is a quantum system with linear potential driving a particle away from a ceiling (impenetrable barrier). This thesis will construct the WKB approximation of the quantum mechanical propagator...
Approximate translation : media, narrative, and experience in urban design
Crisman, Jonathan
2013-01-01T23:59:59.000Z
Approximate translation is developed as a design process through which the place-embedded history of an urban environment can be understood, allowing for better design and intervention in that urban environment. Generally, ...
Fast Approximations for Online Scheduling of Outpatient Procedure ...
2014-06-18T23:59:59.000Z
Jun 18, 2014 ... ? > SmU , any permutation of items to bins that uses the full amount of ... approximation solution value will both tend to cf mU + cv(? ? SmU ).
Numerical Approximations of Stochastic Optimal Stopping and Control Problems
Siska, David
2007-01-01T23:59:59.000Z
We study numerical approximations for the payoff function of the stochastic optimal stopping and control problem. It is known that the payoff function of the optimal stopping and control problem corresponds to the solution ...
Approximate dynamic programming with applications in multi-agent systems
Valenti, Mario J. (Mario James), 1976-
2007-01-01T23:59:59.000Z
This thesis presents the development and implementation of approximate dynamic programming methods used to manage multi-agent systems. The purpose of this thesis is to develop an architectural framework and theoretical ...
Approximate inference : decomposition methods with applications to networks
Jung, Kyomin
2009-01-01T23:59:59.000Z
Markov random field (MRF) model provides an elegant probabilistic framework to formulate inter-dependency between a large number of random variables. In this thesis, we present a new approximation algorithm for computing ...
Density functional theory study of mercury adsorption on metal surfaces
Steckel, J.A.
2008-01-01T23:59:59.000Z
Density functional theory #1;DFT#2; calculations are used to characterize the interaction of mercury with copper, nickel, palladium, platinum, silver, and gold surfaces. Mercury binds relatively strongly to all the metal surfaces studied, with binding energies up to #3;1 eV for Pt and Pd. DFT calculations underestimate the energy of adsorption with respect to available experimental data. Plane-wave DFT results using the local density approximation and the Perdew-Wang 1991 and Perdew-Burke-Ernzerhof parametrizations of the generalized gradient approximation indicate that binding of mercury at hollow sites is preferred over binding at top or bridge sites. The interaction with mercury in order of increasing reactivity over the six metals studied is Ag #1;Au#1;Cu#1;Ni#1;Pt#1;Pd. Binding is stronger on the #1;001#2; faces of the metal surfaces, where mercury is situated in fourfold hollow sites as opposed to the threefold hollow sites on #1;111#2; faces. In general, mercury adsorption leads to decreases in the work function; adsorbate-induced work function changes are particularly dramatic on Pt.
Density Log | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaP aCentrotherm PhotovoltaicsDOI-BLM-NV-W030-20??-????-CXDawuDelawareEnergyDenmark:Density Log Jump to:
Approximate Description of the Mandelbrot Set. Thermodynamic Analogy
O. B. Isaeva; S. P. Kuznetsov
2005-04-29T23:59:59.000Z
Analogy between an approximate version of Feigenbaum renormalization group analysis in complex domain and the phase transition theory of Yang-Lee (based on consideration of formally complexified thermodynamic values) is discussed. It is shown that the Julia sets of the renormalization transformation correspond to the approximation of Mandelbrot set of the original map. New aspects of analogy between the theory of dynamical systems and the phase transition theory are uncovered.
Resonant-state expansion Born Approximation applied to Schrodinger's Equation
Doost, M B
2015-01-01T23:59:59.000Z
The RSE Born Approximation is a new scattering formula in Physics, it allows the calculation of strong scattering via the Fourier transform of the scattering potential and Resonant-states. In this paper I apply the RSE Born Approximation to Schr\\"odinger's Equation. The resonant-states of the system can be calculated using the recently discovered RSE perturbation theory and normalised correctly to appear in spectral Green's functions via the flux volume normalisation.
Mean field approximation for noisy delay coupled excitable neurons
Nikola Buric; Dragana Rankovic; Kristina Todorovic; Nebojsa Vasovic
2010-03-26T23:59:59.000Z
Mean field approximation of a large collection of FitzHugh-Nagumo excitable neurons with noise and all-to-all coupling with explicit time-delays, modelled by $N\\gg 1$ stochastic delay-differential equations is derived. The resulting approximation contains only two deterministic delay-differential equations but provides excellent predictions concerning the stability and bifurcations of the averaged global variables of the exact large system.
Ensemble density variational methods with self- and ghost-interaction-corrected functionals
Pastorczak, Ewa [Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, ul. Wroblewskiego 15, 93-590 Lodz (Poland)] [Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, ul. Wroblewskiego 15, 93-590 Lodz (Poland); Pernal, Katarzyna, E-mail: pernalk@gmail.com [Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90-924 Lodz (Poland)] [Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90-924 Lodz (Poland)
2014-05-14T23:59:59.000Z
Ensemble density functional theory (DFT) offers a way of predicting excited-states energies of atomic and molecular systems without referring to a density response function. Despite a significant theoretical work, practical applications of the proposed approximations have been scarce and they do not allow for a fair judgement of the potential usefulness of ensemble DFT with available functionals. In the paper, we investigate two forms of ensemble density functionals formulated within ensemble DFT framework: the Gross, Oliveira, and Kohn (GOK) functional proposed by Gross et al. [Phys. Rev. A 37, 2809 (1988)] alongside the orbital-dependent eDFT form of the functional introduced by Nagy [J. Phys. B 34, 2363 (2001)] (the acronym eDFT proposed in analogy to eHF ensemble Hartree-Fock method). Local and semi-local ground-state density functionals are employed in both approaches. Approximate ensemble density functionals contain not only spurious self-interaction but also the so-called ghost-interaction which has no counterpart in the ground-state DFT. We propose how to correct the GOK functional for both kinds of interactions in approximations that go beyond the exact-exchange functional. Numerical applications lead to a conclusion that functionals free of the ghost-interaction by construction, i.e., eDFT, yield much more reliable results than approximate self- and ghost-interaction-corrected GOK functional. Additionally, local density functional corrected for self-interaction employed in the eDFT framework yields excitations energies of the accuracy comparable to that of the uncorrected semi-local eDFT functional.
Choosing the Summary Statistics and the Acceptance Rate in Approximate Bayesian
Blum, Michael G. B.
Choosing the Summary Statistics and the Acceptance Rate in Approximate Bayesian Computation or not. In this paper, I incorporate Approximate Bayesian Computation into a local Bayesian regression Computation, evidence approximation, empirical Bayes, Bayesian local regression 1 Introduction Approximate
Lower crustal density estimation using the density-slowness relationship: a preliminary study
Jones, Gary Wayne
1996-01-01T23:59:59.000Z
The density of the Earths crust is an important parameter. Carlson and Raskin [1984] and Carlsan and Herrick (1990] used an empirical approach an the relationship between density and seismic slowness to estimate the density ...
DENSITY OF STATES CALCULATIONS FOR CARBON
Adler, Joan
DENSITY OF STATES CALCULATIONS FOR CARBON ALLOTROPES AND MIXTURES EDUARDO WARSZAWSKI #12;#12;DENSITY OF STATES CALCULATIONS FOR CARBON ALLOTROPES AND MIXTURES Research Thesis Submitted in Partial;#12;Contents Abstract xiii 1 Introduction 1 1.1 Carbon allotropes
Oxides having high energy densities
Ceder, Gerbrand; Kang, Kisuk
2013-09-10T23:59:59.000Z
Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.
Lipoprotein subclass analysis by immunospecific density
Lester, Sandy Marie
2009-05-15T23:59:59.000Z
to obtain a lipoprotein density profile in the absence and presence of apo C-1. Density Lipoprotein Profiling (DLP) gives relevant information of lipoproteins, such as density and subclass characterization, and is a novel approach to purify apo C-1-enriched...
Liquid Walls Innovative High Power Density Concepts
California at Los Angeles, University of
Liquid Walls Innovative High Power Density Concepts (Based on the APEX Study) http better? #12;Primary Goals 1. High Power Density Capability (main driver) Neutron Wall Load > 10 MW/m2\\VLFV UHJLPHV LI OLTXLG PHWDOV DUH XVHG ˇ High Power Density Capability -Eliminate thermal stress and wall
Jacek Dobaczewski Density functional theory and energy
Dobaczewski, Jacek
in Poland per voivodship Energy density functional 245 647 Price voivodship functional 654 763 295 580Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek://www.fuw.edu.pl/~dobaczew/Stellenbosch/dobaczewski_lecture.pdf Home page: http://www.fuw.edu.pl/~dobaczew/ #12;Jacek Dobaczewski Nuclear Structure Energy scales
Ultimate Energy Densities for Electromagnetic Pulses
Mankei Tsang
2008-03-06T23:59:59.000Z
The ultimate electric and magnetic energy densities that can be attained by bandlimited electromagnetic pulses in free space are calculated using an ab initio quantized treatment, and the quantum states of electromagnetic fields that achieve the ultimate energy densities are derived. The ultimate energy densities also provide an experimentally accessible metric for the degree of localization of polychromatic photons.
Variational principles with Padé approximants for tearing mode analysis
Cole, Andrew J. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)] [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Finn, John M. [Applied Mathematics and Plasma Physics, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)] [Applied Mathematics and Plasma Physics, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
2014-03-15T23:59:59.000Z
Tearing modes occur in several distinct physical regimes, and it is often important to compute the inner layer response for these modes with various effects. There is a need for an approximate and efficient method of solving the inner layer equations in all these regimes. In this paper, we introduce a method of solving the inner layer equations based on using a variational principle with Padé approximants. For all the regimes considered, the main layer equations to be solved are inhomogeneous, and Padé approximants give a convenient and efficient method of satisfying the correct asymptotic behavior at the edge of the layer. Results using this variational principlePadé approximant method in three of these regimes is presented. These regimes are the constant-? resistive-inertial (RI) regime, the constant-? viscoresistive regime, and the non-constant-? inviscid tearing regime. The last regime includes the constant-? RI regime and the inertial regime. The results show that reasonable accuracy can be obtained very efficiently with Padé approximants having a small number of parameters.
Electronic Structure via Potential Functional Approximations Attila Cangi,1
Burke, Kieron
Elliott,2 Kieron Burke,1 and E. K. U. Gross3 1 Department of Chemistry, University of California, 1102 of density-functional theory (DFT), suggested by Thomas [1] and Fermi [2] (TF) and made formally exact
SHOCK EMERGENCE IN SUPERNOVAE: LIMITING CASES AND ACCURATE APPROXIMATIONS
Ro, Stephen; Matzner, Christopher D. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON M5S 3H4 (Canada)
2013-08-10T23:59:59.000Z
We examine the dynamics of accelerating normal shocks in stratified planar atmospheres, providing accurate fitting formulae for the scaling index relating shock velocity to the initial density and for the post-shock acceleration factor as functions of the polytropic and adiabatic indices which parameterize the problem. In the limit of a uniform initial atmosphere, there are analytical formulae for these quantities. In the opposite limit of a very steep density gradient, the solutions match the outcome of shock acceleration in exponential atmospheres.
Gong, Xingao
A density-functional study of small titanium clusters S. H. Wei Department of Physics, Xiangtan-functional theory with a local spin density approximation. We find that the inner-shells (3s3p) of the titanium atom of titanium clusters, Ti7 is found to be a magic cluster, which is in good agreement with the experimental
Fourth-post-Newtonian-exact approximation to General Relativity
David Brizuela; Gerhard Schaefer
2010-04-12T23:59:59.000Z
An approximation to General Relativity is presented that agrees with the Einstein field equations up to and including the fourth post-Newtonian (PN) order. This approximation is formulated in a fully constrained scheme: all involved equations are explicitly elliptic except the wave equation that describes the two independent degrees of freedom of the gravitational field. The formalism covers naturally the conformal-flat-condition (CFC) approach by Isenberg, Wilson, and Mathews and the improved second PN-order exact approach CFC+. For stationary configurations, like Kerr black holes, agreement with General Relativity is achieved even through 5PN order. In addition, a particularly interesting 2PN-exact waveless approximation is analyzed in detail, which results from imposing more restrictive conditions. The proposed scheme can be considered as a further development on the waveless approach suggested by Schaefer and Gopakumar [Phys. Rev. D {\\bf 69}, 021501 (2004)].
Non-perturbative QCD amplitudes in quenched and eikonal approximations
Fried, H.M. [Physics Department, Brown University, Providence, RI 02912 (United States); Grandou, T., E-mail: Thierry.Grandou@inln.cnrs.fr [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France); Sheu, Y.-M., E-mail: ymsheu@alumni.brown.edu [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France)
2014-05-15T23:59:59.000Z
Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. - Highlights: We discuss the physical insight of effective locality to QCD fermionic amplitudes. We show that an unavoidable delta function goes along with the effective locality property. The generic structure of QCD fermion amplitudes is obtained through Random Matrix calculus.
Approximations by gravitational fields due to restricted unit point masses
Shull, Carolyn Sue Flowers
1973-01-01T23:59:59.000Z
approximations by Chui (1, 3, 4j and D. J. Newman $12$. Some open problems will be discussed including a conjecture by Chui f2]. I ht th ' th ~Pdl f~hA 1 Mth i I ~gociet is used as a pattern for format, CHAPTER I UNIFORM APPROXIMATION ON COMPACT SETS Let C... free analytic functions in D are not approximable. Also the following result was obtained in fgj . THEOREM 1. 4. A closed set R dis oint from a domain D which lies in som h lf- 1 ne H is ol omial a roximation set relative t b~fl fRt~tbf th I t f3d...
Exact PDF equations and closure approximations for advective-reactive transport
Venturi, D.; Tartakovsky, Daniel M.; Tartakovsky, Alexandre M.; Karniadakis, George E.
2013-06-01T23:59:59.000Z
Mathematical models of advectionreaction phenomena rely on advective flow velocity and (bio) chemical reaction rates that are notoriously random. By using functional integral methods, we derive exact evolution equations for the probability density function (PDF) of the state variables of the advectionreaction system in the presence of random transport velocity and random reaction rates with rather arbitrary distributions. These PDF equations are solved analytically for transport with deterministic flow velocity and a linear reaction rate represented mathematically by a heterog eneous and strongly-correlated random field. Our analytical solution is then used to investigate the accuracy and robustness of the recently proposed large-eddy diffusivity (LED) closure approximation [1]. We find that the solution to the LED-based PDF equation, which is exact for uncorrelated reaction rates, is accurate even in the presence of strong correlations and it provides an upper bound of predictive uncertainty.
Approximate treatment of semicore states in GW calculations with application to Au clusters
Xian, Jiawei [SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy)] [SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy); Baroni, Stefano [SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy) [SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy); CNR-IOM Democritos, Theory-Elettra group, Trieste (Italy); Umari, P., E-mail: paolo.umari@unipd.it [CNR-IOM Democritos, Theory-Elettra group, Trieste (Italy); Dipartimento di Fisica e Astronomia, Universitŕ di Padova, Via Marzolo 8, I-35131 Padova (Italy)
2014-03-28T23:59:59.000Z
We address the treatment of transition metal atoms in GW electronic-structure calculations within the plane-wave pseudo-potential formalism. The contributions of s and p semi-core electrons to the self-energy, which are essential to grant an acceptable accuracy, are dealt with using a recently proposed scheme whereby the exchange components are treated exactly at the G{sub 0}W{sub 0} level, whereas a suitable approximation to the correlation components is devised. This scheme is benchmarked for small gold nano-clusters, resulting in ionization potentials, electron affinities, and density of states in very good agreement with those obtained from calculations where s and p semicore states are treated as valence orbitals, and allowing us to apply this same scheme to clusters of intermediate size, Au{sub 20} and Au{sub 32}, that would be otherwise very difficult to deal with.
Statistical density modification using local pattern matching
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2003-10-01T23:59:59.000Z
Statistical density modification can make use of local patterns of density found in protein structures to improve crystallographic phases. A method for improving crystallographic phases is presented that is based on the preferential occurrence of certain local patterns of electron density in macromolecular electron-density maps. The method focuses on the relationship between the value of electron density at a point in the map and the pattern of density surrounding this point. Patterns of density that can be superimposed by rotation about the central point are considered equivalent. Standard templates are created from experimental or model electron-density maps by clustering and averaging local patterns of electron density. The clustering is based on correlation coefficients after rotation to maximize the correlation. Experimental or model maps are also used to create histograms relating the value of electron density at the central point to the correlation coefficient of the density surrounding this point with each member of the set of standard patterns. These histograms are then used to estimate the electron density at each point in a new experimental electron-density map using the pattern of electron density at points surrounding that point and the correlation coefficient of this density to each of the set of standard templates, again after rotation to maximize the correlation. The method is strengthened by excluding any information from the point in question from both the templates and the local pattern of density in the calculation. A function based on the origin of the Patterson function is used to remove information about the electron density at the point in question from nearby electron density. This allows an estimation of the electron density at each point in a map, using only information from other points in the process. The resulting estimates of electron density are shown to have errors that are nearly independent of the errors in the original map using model data and templates calculated at a resolution of 2.6 Ĺ. Owing to this independence of errors, information from the new map can be combined in a simple fashion with information from the original map to create an improved map. An iterative phase-improvement process using this approach and other applications of the image-reconstruction method are described and applied to experimental data at resolutions ranging from 2.4 to 2.8 Ĺ.
Aerodynamic Focusing Of High-Density Aerosols
Ruiz, D. E.; Fisch, Nathaniel
2014-02-24T23:59:59.000Z
High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1#22; m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.
Trigonometric Pade approximants for functions with regularly decreasing Fourier coefficients
Labych, Yuliya A; Starovoitov, Alexander P [Gomel State University, Gomel (Belarus)
2009-08-31T23:59:59.000Z
Sufficient conditions describing the regular decrease of the coefficients of a Fourier series f(x)=a{sub 0}/2 + {sigma} a{sub n} cos kx are found which ensure that the trigonometric Pade approximants {pi}{sup t}{sub n,m}(x;f) converge to the function f in the uniform norm at a rate which coincides asymptotically with the highest possible one. The results obtained are applied to problems dealing with finding sharp constants for rational approximations. Bibliography: 31 titles.
On the approximation of crack shapes found during inservice inspection
Bhate, S.R.; Chawla, D.S.; Kushwaha, H.S. [Bhabha Atomic Research Centre, Bombay (India)] [and others
1997-04-01T23:59:59.000Z
This paper addresses the characterization of axial internal flaw found during inservice inspection of a pipe. J-integral distribution for various flaw shapes is obtained using line spring finite, element method. The peak J-value and its distribution across the crack is found to be characteristic feature of each shape. The triangular shape yields peak J-value away from the center, the point of depth. The elliptic approximation results in large overestimate of J-value for unsymmetric flaws. Triangular approximation is recommended for such flaws so that further service can be obtained from the component.
L^p Bernstein Inequalities and Radial Basis Function Approximation
Ward, John P.
2012-10-19T23:59:59.000Z
are bounded in terms of certain measurements of the set X. The error of approximation will typically be given in terms of the ll distance hX = sup x2Rd inf 2X jjx jj2 ; which measures how far a point in Rd can be from X, and the stability of the ap... will typically be restricted to sets X for which hX is comparable to qX , and sets for which the mesh ratio X := hX=qX is bounded by a constant will be called quasi-uniform. In this paper, we will only consider approximation spaces SX( ) where X is quasi...
Peer Exchange Calls Inspire New Lessons Learned Greatest Hits | Department
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaP a g e OctoberEnergy FormerSitesof EnergyEnergyof Energy2,Past ProjectsPatriciaPaulof
Oak Ridge Removes Laboratory's Greatest Source of Groundwater
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasma | Department ofEnergy 9 LehmanDepartment of EnergyOAHUensure thatOSSEnergyFCTOContamination |
What the World's GREATEST Energy Managers Do Differently | Department of
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankShale_Gas.pdfService on the Target Host | DepartmentWelcome to the CulturalWhat Is theEXTERNALEnergy
What the World's Greatest Energy Managers Do Differently
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankShale_Gas.pdfService on the Target Host | DepartmentWelcome to the CulturalWhat Is
Review: CO(2) Rising: The World's Greatest Environmental Challenge
Anderson, Byron P.
2009-01-01T23:59:59.000Z
is Dave, a molecule of calcium carbonate that entered theanother molecule of calcium carbonate. Each tells their own
JAMES E. HANSEN World's Greatest Crime against Humanity and Nature
Hansen, James E.
down in an emergency such as an earthquake and cool themselves without outside power. "Fast" reactors's nuclear plants for billions of years, once fast reactors are operational. Thus we can stop mining uranium in countries such as China and India, and all the energy technologies can be improved. Today's nuclear reactors
Allan Tameshtit
2012-04-09T23:59:59.000Z
High temperature and white noise approximations are frequently invoked when deriving the quantum Brownian equation for an oscillator. Even if this white noise approximation is avoided, it is shown that if the zero point energies of the environment are neglected, as they often are, the resultant equation will violate not only the basic tenet of quantum mechanics that requires the density operator to be positive, but also the uncertainty principle. When the zero-point energies are included, asymptotic results describing the evolution of the oscillator are obtained that preserve positivity and, therefore, the uncertainty principle.
Zeynab Harsij; Behrouz Mirza
2014-09-24T23:59:59.000Z
A helicity entangled tripartite state is considered in which the degree of entanglement is preserved in non-inertial frames. It is shown that Quantum Entanglement remains observer independent. As another measure of quantum correlation, Quantum Discord has been investigated. It is explicitly shown that acceleration has no effect on the degree of quantum correlation for the bipartite and tripartite helicity entangled states. Geometric Quantum Discord as a Hilbert-Schmidt distance is computed for helicity entangled states. It is shown that living in non-inertial frames does not make any influence on this distance, either. In addition, the analysis has been extended beyond single mode approximation to show that acceleration does not have any impact on the quantum features in the limit beyond the single mode. As an interesting result, while the density matrix depends on the right and left Unruh modes, the Negativity as a measure of Quantum Entanglement remains constant. Also, Quantum Discord does not change beyond single mode approximation.
Measuring the Density Fluctuation From the Cluster Gas Mass Function
Kazuhiro Shimasaku
1997-01-27T23:59:59.000Z
We investigate the gas mass function of clusters of galaxies to measure the density fluctuation spectrum on cluster scales. The baryon abundance confined in rich clusters is computed from the gas mass function and compared with the mean baryon density in the universe which is predicted by the Big Bang Nucleosynthesis. This baryon fraction and the slope of the gas mass function put constraints on $\\sigma_8$, the rms linear fluctuation on scales of $8h^{-1}\\Mpc$, and the slope of the fluctuation spectrum, where $h$ is the Hubble constant in units of 100 $\\kms \\oMpc$. We find $\\sigma_8 = 0.80 \\pm 0.15$ and $n \\sim -1.5$ for $0.5 \\le h \\le 0.8$, where we assume that the density spectrum is approximated by a power law on cluster scales: $\\sigma(r) \\propto r^{-{3+n\\over{2}}}$. Our value of $\\sigma_8$ is independent of the density parameter, $\\Omega_0$, and thus we can estimate $\\Omega_0$ by combining $\\sigma_8$ obtained in this study with those from $\\Omega_0$-dependent analyses to date. We find that $\\sigma_8(\\Omega_0)$ derived from the cluster abundance such as the temperature function gives $\\Omega_0 \\sim 0.5$ while $\\sigma_8(\\Omega_0)$ measured from the peculiar velocity field of galaxies gives $\\Omega_0 \\sim 0.2-1$, depending on the technique used to analyze peculiar velocity data. Constraints are also derived for open, spatially flat, and tilted Cold Dark Matter models and for Cold + Hot Dark Matter models.
Securely Computing an Approximate Median in Wireless Sensor Networks
Setia, Sanjeev
Securely Computing an Approximate Median in Wireless Sensor Networks Sankardas Roy 1 sroy1@gmu and the unattended nature of sensor nodes, sensor network protocols need to be designed with security in mind and efficient. Categories and Subject Descriptors C.2.0 [Computer-Communication Networks]: General- Security
Successive Rank-One Approximations of Nearly Orthogonally ...
2015-03-01T23:59:59.000Z
Mar 1, 2015 ... approximating SROA based on the power iteration method of [DLDMV00]. There ... perturbation E is sufficiently small (roughly on the order of 1/n under a natural measure). ... A real p-th order n-dimensional tensor ? ? ? p. R.
Non-linear regression models for Approximate Bayesian Computation
Robert, Christian P.
Non-linear regression models for Approximate Bayesian Computation (ABC) Michael Blum Olivier ABC #12;Blum and OF (2009) suggest the use of non-linear conditional heteroscedastic regression models) Linear regression-based ABC can sometimes be improved #12;abc of ABC Using stochastic simulations
Sensitivity, Approximation and Uncertainty in Power System Dynamic Simulation
1 Sensitivity, Approximation and Uncertainty in Power System Dynamic Simulation Ian A. Hiskens, Fellow, IEEE Jassim Alseddiqui Student Member, IEEE Abstract-- Parameters of power system models the influence of uncertainty in simulations of power system dynamic behaviour. It is shown that trajectory
A new shallow approximation for tridimensional non-isothermal viscoplastic
Saramito, Pierre
. The risk assessments for volcanic lava flow pose a difficult challenge to numerical methods. Indeed approximated by an autoadaptive finite element method, based on the Rheolef C++ library, allowing to track with non-isothermal experimental measurements for a silicone oil dome. Next, the December 2010 eruption
Continued fractions with low complexity: Transcendence measures and quadratic approximation
Bugeaud, Yann
expansion of an irrational algebraic number either is ultimately periodic (this is the case if, and only if. Theorems 3.2 and 3.3 give transcendence mea- sures for a class of transcendental numbers defined by theiContinued fractions with low complexity: Transcendence measures and quadratic approximation Yann
Local RBF Approximation for Scattered Data Fitting with Bivariate Splines
Davydov, Oleg
and large scale optimization problems arising if the interpolating, smoothing or minimal energy spline in [5], a hybrid polynomial/radial basis scheme was considered in [4], where the local knot locations of radial basis functions, so defining hybrid approximations which are still computed by discrete least
Jitter-Approximation Tradeoff for Periodic Scheduling Zvika Brakerski
Patt-Shamir, Boaz
Jitter-Approximation Tradeoff for Periodic Scheduling Zvika Brakerski Dept. of Electrical the average period of a job in the schedule is blown up w.r.t. its requested period, and the jitter ratio with low jitter ratio allow the mobile devices to save power by hav- ing their receivers switched off
Approximating many-body induction to efficiently describe molecular liquids
Herbert, John
on the structure and solvation dynamics of the excess electron (in the ground state) but does have a large impact as the structures and properties of molecular systems. This study focuses on approximating many-body electronic methods in order to allow "on-the-fly" energy and force evaluations in dynamical calculations
Dynamic Adaptive Search Based Software Engineering Needs Fast Approximate Metrics
Harman, Mark
1 Dynamic Adaptive Search Based Software Engineering Needs Fast Approximate Metrics Mark Harman. University College Dublin, Ireland. Abstract--Search Based Software Engineering (SBSE) uses fitness functions to guide an automated search for solutions to challenging software engineering problems. The fitness
Novel approximations for inference and learning in nonlinear dynamical systems
Heskes, Tom
Novel approximations for inference and learning in nonlinear dynamical systems Alexander Ypma #3 from marketing research. 1 Introduction Many real-world systems are nonlinear, dynamical and stochastic in nature. Inference and learning of nonlinear system models with hidden dynamics is a diĆcult task, which
Approximation in Mechanism Design By JASON D. HARTLINE
Hartline, Jason D.
Approximation in Mechanism Design By JASON D. HARTLINE A mechanism gives a mapping between will arise in the equilibrium of selfish agent play. Mechanism design then considers the optimization question of what mechanisms have good outcomes in equilibrium. Optimal mechanism design searches
August and September Approximately 29 percent from husks
minutes. Cool promptly in several changes of cold water and drain. Whole-kernel corn: Cut kernels from. Scrape the cobs with the back of the knife to remove the juice and the hearts of the kernels. Pack corn for approximately the same length of time the corn was blanched) and drain well. Tightly ',vrap ears individually
New approximate radial wave functions for power-law potentials
Vladimir Kudryashov
2007-09-26T23:59:59.000Z
Radial wave functions for power-law potentials are approximated with the help of power-law substitution and explicit summation of the leading constituent WKB series. Our approach reproduces the correct behavior of the wave functions at the origin, at the turning points and far away from the turning points
Approximate Inference in Probabilistic Models Manfred Opper1
of Electronics and Computer Science University of Southampton SO17 1BJ, United Kingdom mo@ecs.soton.ac.uk 2 on free energies. The free energy is constructed from two approximating distributions which encode differ Energy (GFE), an entropic quantity which (originally developed in Statistical Physics) allows us
Approximate Dynamic Programming in Transportation and Logistics: A Unified Framework
Powell, Warren B.
Approximate Dynamic Programming in Transportation and Logistics: A Unified Framework Warren B Engineering Princeton University, Princeton, NJ 08544 European J. of Transportation and Logistics, Vol. 1, No optimization has enjoyed a rich place in transportation and logistics, where it repre- sents a mature field
Exploiting Correlated Keywords to Improve Approximate Information Filtering
Tryfonopoulos, Christos
, Christos Tryfonopoulos, and Gerhard Weikum Databases and Information Systems Department Max-Planck Institut- scribe to information sources and be notified whenever new documents of interest are published. In approximate infor- mation filtering only selected information sources, that are likely to publish documents
Clustering With or Without the Approximation Frans Schalekamp
Schalekamp, Frans
Clustering With or Without the Approximation Frans Schalekamp ITCS, Tsinghua University Michael Yu MIT Anke van Zuylen ITCS, Tsinghua University Abstract We study algorithms for clustering data if we do not know values of and for which the assumption holds. Finally, we implement these methods
Boundary approximate controllability of some linear parabolic April 5, 2013
Paris-Sud XI, Université de
Boundary approximate controllability of some linear parabolic systems April 5, 2013 Guillaume Olive controllability of two classes of linear parabolic systems, namely a system of n heat equations coupled through are the only ones concerning the boundary controllability of linear parabolic systems of heat-type. For more
Approximating Radon measures on first--countable compact spaces
Plebanek, Grzegorz
Approximating Radon measures on first--countable compact spaces Grzegorz Plebanek (Wroc/law) Abstract The assertion every Radon measure defined on a first--countable compact space is uniformly regular under CH. In this note we consider some properties of finite Radon measures defined on compact spaces
The Exemplar Breakpoint Distance for nontrivial genomes cannot be approximated
Fertin, Guillaume
The Exemplar Breakpoint Distance for nonÂtrivial genomes cannot be approximated Guillaume Blin 1 Â France guillaume.fertin@univÂnantes.fr Abstract. A promising and active field of comparative genomics conÂ sists in comparing two genomes by establishing a oneÂtoÂone corresponÂ dence (i.e., a matching) between
Self-similar and charged spheres in the diffusion approximation
W. Barreto; A. Da Silva
2005-08-12T23:59:59.000Z
We study spherical, charged and self--similar distributions of matter in the diffusion approximation. We propose a simple, dynamic but physically meaningful solution. For such a solution we obtain a model in which the distribution becomes static and changes to dust. The collapse is halted with damped mass oscillations about the absolute value of the total charge.
An Equivalence Between Sparse Approximation and Support Vector Machines 1
Poggio, Tomaso
An Equivalence Between Sparse Approximation and Support Vector Machines 1 Federico Girosi Center is equivalent to SVM in the following sense: if applied to the same data set the two techniques give the same; Chen, Donoho and Saunders, 1995), are actually equivalent, in the case of noiseless data. By equivalent
Aqua: A Fast Decision Support System Using Approximate Query Answers
Gibbons, Phillip B.
commercial relational DBMS. Aqua precomputes synopses (special sta- tistical summaries) of the original data and stores them in the DBMS. It provides approximate an- swers (with quality guarantees) by rewriting on top of any SQL- compliant DBMS managing a data warehouse. Aqua pre- computes statistical summaries
Approximate Minimum-Energy Multicasting in Wireless Ad Hoc Networks
Liang, Weifa
Approximate Minimum-Energy Multicasting in Wireless Ad Hoc Networks Weifa Liang, Senior Member, IEEE Abstract--A wireless ad hoc network consists of mobile nodes that are equipped with energy on energy conservation in wireless ad hoc networks have been conducted. For example, energy efficient
Geometric Wavelet Approximations and Abdourrahmane M. Atto1
Paris-Sud XI, Université de
1 Geometric Wavelet Approximations and Dierencing Abdourrahmane M. Atto1 , Emmanuel Trouve2 Jean-Marie Nicolas3 , Abstract--The paper introduces the concept of ge- ometric wavelets defined from multiplicative algebras. These wavelets perform generalized geometric approx- imations and differencing. The paper also
A Study of Approximate Data Management Techniques for Sensor Networks
Martin, Ralph R.
the monitoring operation of sensor nodes by efficiently using their limited energy, bandwidth and computation. The network can therefore be treated as a distributed sensor data management system. Sensor networks differA Study of Approximate Data Management Techniques for Sensor Networks Adonis Skordylis, Niki
3-D cinematography with approximate and no geometry
Magnor, Marcus
3-D cinematography with approximate and no geometry Martin Eisemann, Timo Stich and Marcus Magnor Abstract 3-D cinematography is a new step towards full immersive video, allow- ing complete control of the book Image and Geometry Processing for 3-D Cinematography published by Springer. 1 Introduction
A COMPUTATONAL METHOD FOR APPROXIMATING A DARCY-STOKES SYSTEM
Arbogast, Todd
of a second order elliptic (i.e., Darcy) equation on part of the domain coupled to a Stokes equation equation representing Darcy's law and mass conservation, and in the vugs s = \\ Żd by the Stokes equationA COMPUTATONAL METHOD FOR APPROXIMATING A DARCY-STOKES SYSTEM GOVERNING A VUGGY POROUS MEDIUM TODD
Accelerating Search of Approximate Match on Large Protein Sequence Databases
Wang, Wei
of supporting indexed search on large biological sequence databases since the construction cost of the index Yang 2 , Yi Xia 3 , Philip Yu 4 Keywords: protein sequence index, approximate match. Due. Building an appropriate index structure is one of the possibilities to achieve such a goal, which
Benchmarking a Scalable Approximate Dynamic Programming Algorithm for Stochastic Control
Powell, Warren B.
for the optimal control of such power systems are critical for the deployment of reliable and more economical and within 1.34% in stochastic ones, much lower than those obtained using model predictive control. We useBenchmarking a Scalable Approximate Dynamic Programming Algorithm for Stochastic Control
Approximate bisimulation for a class of stochastic hybrid systems
Pappas, George J.
, target tracking, robotics, and power systems [35]. The field of stochastic hybrid systems is a veryApproximate bisimulation for a class of stochastic hybrid systems (Invited Paper) Agung Julius of stochastic hybrid systems, namely, the jump linear stochastic systems (JLSS). The idea is based
Fast approximation of the bootstrap for model selection
Verleysen, Michel
Fast approximation of the bootstrap for model selection G. Simon1 , A. Lendasse2 , V. Wertz2 , M. The bootstrap resampling method may be efficiently used to estimate the generalization error of a family with the bootstrap in real-world applications is the high computation load. In this paper we propose a simple
Bootstrap for model selection: linear approximation of the optimism
Verleysen, Michel
Bootstrap for model selection: linear approximation of the optimism G. Simon1 , A. Lendasse2 , M. Lemaître 4, B-1348 Louvain-la-Neuve, Belgium, lendasse@auto.ucl.ac.be Abstract. The bootstrap resampling, as artificial neural networks. Nevertheless, the use of the bootstrap implies a high computational load
APPROXIMATION THEORY OF OUTPUT STATISTICS Dept. Information Systems
Verdú, Sergio
. In order to generate a ran- dom process we assume that a primary random source with an equiprobableAPPROXIMATION THEORY OF OUTPUT STATISTICS Te Sun Han Dept. Information Systems Senshu University-length) source coding rate of any finite-alphabet source, and a strong converse of the identijication coding
Tao, Jianmin [Los Alamos National Laboratory; Perdew, John P [TULANE UNIV; Staroverov, Viktor N [UNIV OF WESTERN ONTARIO; Scuseria, Gustavo E [RICE UNIV
2008-01-01T23:59:59.000Z
We construct a nonlocal density functional approximation with full exact exchange, while preserving the constraint-satisfaction approach and justified error cancellations of simpler semilocal functionals. This is achieved by interpolating between different approximations suitable for two extreme regions of the electron density. In a 'normal' region, the exact exchange-correlation hole density around an electron is semilocal because its spatial range is reduced by correlation and because it integrates over a narrow range to -1. These regions are well described by popular semilocal approximations (many of which have been constructed nonempirically), because of proper accuracy for a slowly-varying density or because of error cancellation between exchange and correlation. 'Abnormal' regions, where non locality is unveiled, include those in which exchange can dominate correlation (one-electron, nonuniform high-density, and rapidly-varying limits), and those open subsystems of fluctuating electron number over which the exact exchange-correlation hole integrates to a value greater than -1. Regions between these extremes are described by a hybrid functional mixing exact and semi local exchange energy densities locally (i.e., with a mixing fraction that is a function of position r and a functional of the density). Because our mixing fraction tends to 1 in the high-density limit, we employ full exact exchange according to the rigorous definition of the exchange component of any exchange-correlation energy functional. Use of full exact exchange permits the satisfaction of many exact constraints, but the nonlocality of exchange also requires balanced nonlocality of correlation. We find that this nonlocality can demand at least five empirical parameters (corresponding roughly to the four kinds of abnormal regions). Our local hybrid functional is perhaps the first accurate size-consistent density functional with full exact exchange. It satisfies other known exact constraints, including exactness for all one-electron densities, and provides an excellent, fit 1.0 the 223 molecular enthalpies of formation of the G3/99 set and the 42 reaction barrier heights of the BH42/03 set, improving both (but especially the latter) over most semilocal functionals and global hybrids. Exact constraints, physical insights, and paradigm examples hopefully suppress 'overfitting'.
Ping He; Li-Zhi Fang
2002-02-12T23:59:59.000Z
We investigate the constraint on the abundance of primordial black holes (PBHs) and the spectral index $n$ of primeval density perturbations given by the ionizing photon background at the epoch of reionization. Within the standard inflationary cosmogony, we show that the spectral index $n$ of the power-law power spectrum of primeval density perturbations should be $n<$1.27. Since the universe is still optical thick at the reionization redshift $z\\sim 6$ - 8, this constraint is independent of the unknown parameter of reheating temperature of the inflation. The ionizing photon background from the PBHs can be well approximated by a power law spectrum $J(\
Yao, Kun
2015-01-01T23:59:59.000Z
We demonstrate a convolutional neural network trained to reproduce the Kohn-Sham kinetic energy of hydrocarbons from electron density. The output of the network is used as a non-local correction to the conventional local and semi-local kinetic functionals. We show that this approximation qualitatively reproduces Kohn-Sham potential energy surfaces when used with conventional exchange correlation functionals. Numerical noise inherited from the non-linearity of the neural network is identified as the major challenge for the model. Finally we examine the features in the density learned by the neural network to anticipate the prospects of generalizing these models.
Quartz resonator fluid density and viscosity monitor
Martin, Stephen J. (Albuquerque, NM); Wiczer, James J. (Albuquerque, NM); Cernosek, Richard W. (Albuquerque, NM); Frye, Gregory C. (Cedar Crest, NM); Gebert, Charles T. (Albuquerque, NM); Casaus, Leonard (Bernalillo, NM); Mitchell, Mary A. (Tijeras, NM)
1998-01-01T23:59:59.000Z
A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.
New theory of superconductivity. Method of equilibrium density matrix
Boris Bondarev
2013-09-22T23:59:59.000Z
A new variational method for studying the equilibrium states of an interacting particles system has been proposed. The statistical description of the system is realized by means of a density matrix. This method is used for description of conduction electrons in metals. An integral equation for the electron distribution function over wave vectors has been obtained. The solutions of this equation have been found for those cases where the single-particle Hamiltonian and the electron interaction Hamiltonian can be approximated by a quite simple expression. It is shown that the distribution function at temperatures below the critical value possesses previously unknown features which allow to explain the superconductivity of metals and presence of a gap in the energy spectrum of superconducting electrons.
Density and Tensile Properties Changed by Aging Plutonium
Chung, B W; Choi, B W; Thompson, S R; Woods, C H; Hopkins, D J; Ebbinghaus, B B
2005-03-14T23:59:59.000Z
We present volume, density, and tensile property change observed from both naturally and accelerated aged plutonium alloys. Accelerated alloys are plutonium alloys with a fraction of Pu-238 to accelerate the aging process by approximately 18 times the rate of unaged weapons-grade plutonium. After thirty-five equivalent years of aging on accelerated alloys, the dilatometry shows the samples at 35 C have swelled in volume by 0.12 to 0.14% and now exhibit a near linear volume increase due to helium in-growth while showing possible surface effects on samples at 50 C and 65 C. The engineering stress of the accelerated alloy at 18 equivalent years increased significantly compared to at 4.5 equivalent years.
Density gradient free electron collisionally excited X-ray laser
Campbell, Edward M. (Pleasanton, CA); Rosen, Mordecai D. (Berkeley, CA)
1989-01-01T23:59:59.000Z
An operational X-ray laser (30) is provided that amplifies 3p-3s transition X-ray radiation along an approximately linear path. The X-ray laser (30) is driven by a high power optical laser. The driving line focused optical laser beam (32) illuminates a free-standing thin foil (34) that may be associated with a substrate (36) for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the X-ray laser gain medium. The X-ray laser (30) may be driven by more than one optical laser beam (32, 44). The X-ray laser (30) has been successfully demonstrated to function in a series of experimental tests.
Density gradient free electron collisionally excited x-ray laser
Campbell, E.M.; Rosen, M.D.
1984-11-29T23:59:59.000Z
An operational x-ray laser is provided that amplifies 3p-3s transition x-ray radiation along an approximately linear path. The x-ray laser is driven by a high power optical laser. The driving line focused optical laser beam illuminates a free-standing thin foil that may be associated with a substrate for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the x-ray laser gain medium. The x-ray laser may be driven by more than one optical laser beam. The x-ray laser has been successfully demonstrated to function in a series of experimental tests.
Method of synthesizing a low density material
Lorensen, L.E.; Monaco, S.B.
1987-02-27T23:59:59.000Z
A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.
Some recent efforts toward high density implosions
McClellan, G.E.
1980-12-04T23:59:59.000Z
Some recent Livermore efforts towards achieving high-density implosions are presented. The implosion dynamics necessary to compress DT fuel to 10 to 100 times liquid density are discussed. Methods of diagnosing the maximum DT density for a specific design are presented along with results to date. The dynamics of the double-shelled target with an exploding outer shell are described, and some preliminary experimental results are presented.
Considering Air Density in Wind Power Production
Farkas, Zénó
2011-01-01T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Considering Air Density in Wind Power Production
Zénó Farkas
2011-03-11T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Global hybrids from the semiclassical atom theory satisfying the local density linear response
Fabiano, E; Cortona, P; Della Sala, F
2015-01-01T23:59:59.000Z
We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetical and structural testings, including thermochemistry and geometry, transition metal complexes, non-covalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20\\% o...
Zhang, Ping; Zhao, Xian-Geng
2010-01-01T23:59:59.000Z
Plutonium dioxide is of high technological importance in nuclear fuel cycle and is particularly crucial in long-term storage of Pu-based radioactive waste. Using first-principles density-functional theory, in this paper we systematically study the structural, electronic, mechanical, thermodynamic properties, and pressure induced structural transition of PuO$_{2}$. To properly describe the strong correlation in the Pu $5f$ electrons, the local density approximation$+U$ and the generalized gradient approximation$+U$ theoretical formalisms have been employed. We optimize the $U$ parameter in calculating the total energy, lattice parameters, and bulk modulus at the nonmagnetic, ferromagnetic, and antiferromagnetic configurations for both ground state fluorite structure and high pressure cotunnite structure. The best agreement with experiments is obtained by tuning the effective Hubbard parameter $U$ at around 4 eV within the LDA$+U$ approach. After carefully testing the validity of the ground state, we further in...
3-D capacitance density imaging system
Fasching, G.E.
1988-03-18T23:59:59.000Z
A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.
Uncertainty Quantification for Nuclear Density Functional Theory...
Office of Scientific and Technical Information (OSTI)
Uncertainty Quantification for Nuclear Density Functional Theory and Information Content of New Measurements Citation Details In-Document Search This content will become publicly...
Building a Universal Nuclear Energy Density Functional
Bertulani, Carlos A. [Texas A& M Univ., Commerce, TX (United States)
2014-09-10T23:59:59.000Z
This grant had two components: Density functional theory and pairing and Nuclear reactions. This final report summarizes the activities for this SciDAC-2 project.
On the Extensive Air Shower density spectrum
Aleksander Zawadzki; Tadeusz Wibig; Jerzy Gawin
1998-07-29T23:59:59.000Z
In search for new methods of determining the primary energy spectrum of Cosmic Rays, the attention was paid to the density spectrum measurement. New methods available at present warrant an accurateness of conclusions derived from the density spectrum measurements. The general statement about the change of the spectral index of the charged particle density spectrum is confirmed very clearly. Results concerning the shower size and primary energy spectra are also presented and discussed. Interesting future prospects for applications of the density spectrum method are proposed.
De Souza, J.C.C.; Pires, M.O.C., E-mail: jose.souza@ufabc.edu.br, E-mail: marcelo.pires@ufabc.edu.br [Centro de Cięncias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia 166, Santo André, SP, 09210-170 (Brazil)
2014-03-01T23:59:59.000Z
We show that the galactic dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate [6] trapped by a self-graviting potential [5], may be stable in the Thomas-Fermi approximation since appropriate choices for the dark matter particle mass and scattering length are made. The demonstration is performed by means of the calculation of the potential, kinetic and self-interaction energy terms of a galactic halo described by a Boehmer-Harko density profile. We discuss the validity of the Thomas-Fermi approximation for the halo system, and show that the kinetic energy contribution is indeed negligible.
Quasielastic electron-deuteron scattering in the weak binding approximation
Ethier, Jacob J. [William and Mary College, JLAB; Doshi, Nidhi P. [Carnegie Mellon University; Malace, Simona P. [JLAB; Melnitchouk, Wally [JLAB
2014-06-01T23:59:59.000Z
We perform a global analysis of all available electron-deuteron quasielastic scattering data using Q^2-dependent smearing functions that describe inclusive inelastic e-d scattering within the weak binding approximation. We study the dependence of the cross sections on the deuteron wave function and the off-shell extrapolation of the elastic electron-nucleon cross section, which show particular sensitivity at x >> 1. The excellent overall agreement with data over a large range of Q^2 and x suggest a limited need for effects beyond the impulse approximation, with the exception of the very high-x or very low-Q^2 regions, where short-distance effects in the deuteron become more relevant.
Quantum optimal control within the rotating wave approximation
Maximilian Keck; Matthias M. Müller; Tommaso Calarco; Simone Montangero
2015-03-06T23:59:59.000Z
We study the interplay between rotating wave approximation and optimal control. In particular, we show that for a wide class of optimal control problems one can choose the control field such that the Hamiltonian becomes time-independent under the rotating wave approximation. Thus, we show how to recast the functional minimization defined by the optimal control problem into a simpler multi-variable function minimization. We provide the analytic solution to the state-to-state transfer of the paradigmatic two-level system and to the more general star configuration of an $N$-level system. We demonstrate numerically the usefulness of this approach in the more general class of connected acyclic $N$-level systems with random spectra. Finally, we use it to design a protocol to entangle Rydberg via constant laser pulses atoms in an experimentally relevant range of parameters.
On approximate controllability of generalized KdV solitons
Claudio Muńoz
2014-05-24T23:59:59.000Z
We consider the approximate control of solitons in generalized Korteweg-de Vries equations. By introducing a suitable internal bilinear control on the equation, we prove that any soliton is locally null controllable, and moreover, any soliton can be accelerated to any particular positive velocity, after a suitable large amount of time. Precise estimates on the error terms and the rate of decay in the approximate null controllability result are also given. Our method introduces a new insight on the control of nonlinear objects, from the point of view of interaction and collision problems for nonlinear dispersive equations, recently developed by Y. Martel and F. Merle. It can be applied in principle, to several other models with soliton solutions.
Feedback stabilisation of switched systems via iterative approximate eigenvector assignment
Haimovich, Hernan
2010-01-01T23:59:59.000Z
This paper presents and implements an iterative feedback design algorithm for stabilisation of discrete-time switched systems under arbitrary switching regimes. The algorithm seeks state feedback gains so that the closed-loop switching system admits a common quadratic Lyapunov function (CQLF) and hence is uniformly globally exponentially stable. Although the feedback design problem considered can be solved directly via linear matrix inequalities (LMIs), direct application of LMIs for feedback design does not provide information on closed-loop system structure. In contrast, the feedback matrices computed by the proposed algorithm assign closed-loop structure approximating that required to satisfy Lie-algebraic conditions that guarantee existence of a CQLF. The main contribution of the paper is to provide, for single-input systems, a numerical implementation of the algorithm based on iterative approximate common eigenvector assignment, and to establish cases where such algorithm is guaranteed to succeed. We inc...
Exploring approximations to the GW self-energy ionic gradients
Faber, C; Attaccalite, C; Cannuccia, E; Duchemin, I; Deutsch, T; Blase, X
2015-01-01T23:59:59.000Z
The accuracy of the many-body perturbation theory GW formalism to calculate electron-phonon coupling matrix elements has been recently demonstrated in the case of a few important systems. However, the related computational costs are high and thus represent strong limitations to its widespread application. In the present study, we explore two less demanding alternatives for the calculation of electron-phonon coupling matrix elements on the many-body perturbation theory level. Namely, we test the accuracy of the static Coulomb-hole plus screened-exchange (COHSEX) approximation and further of the constant screening approach, where variations of the screened Coulomb potential W upon small changes of the atomic positions along the vibrational eigenmodes are neglected. We find this latter approximation to be the most reliable, whereas the static COHSEX ansatz leads to substantial errors. Our conclusions are validated in a few paradigmatic cases: diamond, graphene and the C60 fullerene. These findings open the way f...
On the Peterlin approximation for turbulent flows of polymer solutions
Dario Vincenzi; Prasad Perlekar; Luca Biferale; Federico Toschi
2015-05-26T23:59:59.000Z
We study the impact of the Peterlin approximation on the statistics of the end-to-end separation of poly- mers in a turbulent flow. The FENE and FENE-P models are numerically integrated along a large number of Lagrangian trajectories resulting from a direct numerical simulation of three-dimensional homogeneous isotropic turbulence. Although the FENE-P model yields results in qualitative agreement with those of the FENE model, quantitative differences emerge. The steady-state probability of large extensions is overesti- mated by the FENE-P model. The alignment of polymers with the eigenvectors of the rate-of-strain tensor and with the direction of vorticity is weaker when the Peterlin approximation is used. At large Weissenberg numbers, both the correlation times of the extension and of the orientation of polymers are underestimated by the FENE-P model.
On the Peterlin approximation for turbulent flows of polymer solutions
Vincenzi, Dario; Biferale, Luca; Toschi, Federico
2015-01-01T23:59:59.000Z
We study the impact of the Peterlin approximation on the statistics of the end-to-end separation of poly- mers in a turbulent flow. The FENE and FENE-P models are numerically integrated along a large number of Lagrangian trajectories resulting from a direct numerical simulation of three-dimensional homogeneous isotropic turbulence. Although the FENE-P model yields results in qualitative agreement with those of the FENE model, quantitative differences emerge. The steady-state probability of large extensions is overesti- mated by the FENE-P model. The alignment of polymers with the eigenvectors of the rate-of-strain tensor and with the direction of vorticity is weaker when the Peterlin approximation is used. At large Weissenberg numbers, both the correlation times of the extension and of the orientation of polymers are underestimated by the FENE-P model.
Isothermal and shock compression of high density ammonium nitrate and ammonium perchlorate
Sandstrom, F.W.; Persson, P.A. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Olinger, B. [Los Alamos National Lab., NM (United States)
1992-10-01T23:59:59.000Z
Given the widespread use of ammonium nitrate (AN) and ammonium perchlorate (AP) for energetic materials applications, relatively little data is available regarding their behavior under shock loading. We have evaluated the shock Hugoniots of AN and AP at high initial density ({ge} 94% TMD) to pressures of approximately 20 GPa. We have used sound speed measurements, isothermal compfession X-ray diffraction experiments and shock loading experiments to further explore the behavior of the two materials at elevated pressures.
Isothermal and shock compression of high density ammonium nitrate and ammonium perchlorate
Sandstrom, F.W.; Persson, P.A. (New Mexico Inst. of Mining and Technology, Socorro, NM (United States)); Olinger, B. (Los Alamos National Lab., NM (United States))
1992-01-01T23:59:59.000Z
Given the widespread use of ammonium nitrate (AN) and ammonium perchlorate (AP) for energetic materials applications, relatively little data is available regarding their behavior under shock loading. We have evaluated the shock Hugoniots of AN and AP at high initial density ([ge] 94% TMD) to pressures of approximately 20 GPa. We have used sound speed measurements, isothermal compfession X-ray diffraction experiments and shock loading experiments to further explore the behavior of the two materials at elevated pressures.
Particle-vibration coupling within covariant density functional theory
E. Litvinova; P. Ring; V. Tselyaev
2007-05-08T23:59:59.000Z
Covariant density functional theory, which has so far been applied only within the framework of static and time dependent mean field theory is extended to include Particle-Vibration Coupling (PVC) in a consistent way. Starting from a conventional energy functional we calculate the low-lying collective vibrations in Relativistic Random Phase Approximation (RRPA) and construct an energy dependent self-energy for the Dyson equation. The resulting Bethe-Salpeter equation in the particle-hole ($ph$) channel is solved in the Time Blocking Approximation (TBA). No additional parameters are used and double counting is avoided by a proper subtraction method. The same energy functional, i.e. the same set of coupling constants, generates the Dirac-Hartree single-particle spectrum, the static part of the residual $ph$-interaction and the particle-phonon coupling vertices. Therefore a fully consistent description of nuclear excited states is developed. This method is applied for an investigation of damping phenomena in the spherical nuclei with closed shells $^{208}$Pb and $^{132}$Sn. Since the phonon coupling terms enrich the RRPA spectrum with a multitude of $ph\\otimes$phonon components a noticeable fragmentation of the giant resonances is found, which is in full agreement with experimental data and with results of the semi-phenomenological non-relativistic approach.
Studies in Interpolation and Approximation of Multivariate Bandlimited Functions
Bailey, Benjamin Aaron
2012-10-19T23:59:59.000Z
&M University in partial ful llment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Co-Chairs of Committee, Thomas Schlumprecht N. Sivakumar Committee Members, Joel Zinn William Johnson Fred Dahm Head of Department, Albert...{Chairs of Advisory Committee: Dr. Thomas Schlumprecht Dr. N. Sivakumar The focus of this dissertation is the interpolation and approximation of multi- variate bandlimited functions via sampled (function) values. The rst set of results investigates polynomial...
New Algorithms for Finding Approximate Frequent Item Sets
Berthold, Michael R.
New Algorithms for Finding Approximate Frequent Item Sets Christian Borgelt1 , Christian Braune1,2 , Tobias KÂ¨otter3 and Sonja GrÂ¨un4,5 1 European Centre for Soft Computing c/ Gonzalo GutiÂ´errez QuirÂ´os s/n.borgelt@softcomputing.es, christian.braune@st.ovgu.de, tobias.koetter@uni-konstanz.de, s.gruen@fz-juelich.de Abstract. In standard
Denoising MR Spectroscopic Imaging Data with Low-Rank Approximations
Do, Minh N.
1 Denoising MR Spectroscopic Imaging Data with Low-Rank Approximations Hien M. Nguyen, Member, IEEE- temporal imaging data as well. Index Terms--MR spectroscopy, MR spectroscopic imaging, denoising, low spectroscopic (MRS) signal in (k, t)-space can be expressed as s(k, t) = (r, f)e-i2kˇr e-i2ft drdf + (k, t), (1
Product-state Approximations to Quantum Ground States
Fernando G. S. L. Brandăo; Aram W. Harrow
2014-12-15T23:59:59.000Z
The local Hamiltonian problem consists of estimating the ground-state energy (given by the minimum eigenvalue) of a local quantum Hamiltonian. First, we show the existence of a good product-state approximation for the ground-state energy of 2-local Hamiltonians with one or more of the following properties: (1) high degree, (2) small expansion, or (3) a ground state with sublinear entanglement with respect to some partition into small pieces. The approximation based on degree is a surprising difference between quantum Hamiltonians and classical CSPs (constraint satisfaction problems), since in the classical setting, higher degree is usually associated with harder CSPs. The approximation based on low entanglement, in turn, was previously known only in the regime where the entanglement was close to zero. Since the existence of a low-energy product state can be checked in NP, the result implies that any Hamiltonian used for a quantum PCP theorem should have: (1) constant degree, (2) constant expansion, (3) a "volume law" for entanglement with respect to any partition into small parts. Second, we show that in several cases, good product-state approximations not only exist, but can be found in polynomial time: (1) 2-local Hamiltonians on any planar graph, solving an open problem of Bansal, Bravyi, and Terhal, (2) dense k-local Hamiltonians for any constant k, solving an open problem of Gharibian and Kempe, and (3) 2-local Hamiltonians on graphs with low threshold rank, via a quantum generalization of a recent result of Barak, Raghavendra and Steurer. Our work introduces two new tools which may be of independent interest. First, we prove a new quantum version of the de Finetti theorem which does not require the usual assumption of symmetry. Second, we describe a way to analyze the application of the Lasserre/Parrilo SDP hierarchy to local quantum Hamiltonians.
The periodic standing-wave approximation: post-Minkowski computation
Christopher Beetle; Benjamin Bromley; Napoleón Hernández; Richard H. Price
2007-08-08T23:59:59.000Z
The periodic standing wave method studies circular orbits of compact objects coupled to helically symmetric standing wave gravitational fields. From this solution an approximation is extracted for the strong field, slowly inspiralling motion of black holes and binary stars. Previous work on this model has dealt with nonlinear scalar models, and with linearized general relativity. Here we present the results of the method for the post-Minkowski (PM) approximation to general relativity, the first step beyond linearized gravity. We compute the PM approximation in two ways: first, via the standard approach of computing linearized gravitational fields and constructing from them quadratic driving sources for second-order fields, and second, by solving the second-order equations as an ``exact'' nonlinear system. The results of these computations have two distinct applications: (i) The computational infrastructure for the ``exact'' PM solution will be directly applicable to full general relativity. (ii) The results will allow us to begin supplying initial data to collaborators running general relativistic evolution codes.
Time Dependent Density Functional Theory An Introduction
Botti, Silvana
Time Dependent Density Functional Theory An Introduction Francesco Sottile Laboratoire des Solides) Belfast, 29 Jun 2007 Time Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Linear Response Formalism 3 TDDFT in practice: The ALDA: Achievements and Shortcomings 4 Resources Time
Como, Giacomo
Automating efficiency-targeted approximations in modelling and simulation tools: dynamic decoupling (classical) efficiency-targeted approximation tech- niques, within a unified framework. Some application
Density functional theory for carbon dioxide crystal
Chang, Yiwen; Mi, Jianguo, E-mail: mijg@mail.buct.edu.cn; Zhong, Chongli [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)
2014-05-28T23:59:59.000Z
We present a density functional approach to describe the solid?liquid phase transition, interfacial and crystal structure, and properties of polyatomic CO{sub 2}. Unlike previous phase field crystal model or density functional theory, which are derived from the second order direct correlation function, the present density functional approach is based on the fundamental measure theory for hard-sphere repulsion in solid. More importantly, the contributions of enthalpic interactions due to the dispersive attractions and of entropic interactions arising from the molecular architecture are integrated in the density functional model. Using the theoretical model, the predicted liquid and solid densities of CO{sub 2} at equilibrium triple point are in good agreement with the experimental values. Based on the structure of crystal-liquid interfaces in different planes, the corresponding interfacial tensions are predicted. Their respective accuracies need to be tested.
Neutral depletion and the helicon density limit
Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E. [West Virginia University, Morgantown, West Virginia 26506 (United States)] [West Virginia University, Morgantown, West Virginia 26506 (United States)
2013-12-15T23:59:59.000Z
It is straightforward to create fully ionized plasmas with modest rf power in a helicon. It is difficult, however, to create plasmas with density >10{sup 20} m{sup ?3}, because neutral depletion leads to a lack of fuel. In order to address this density limit, we present fast (1 MHz), time-resolved measurements of the neutral density at and downstream from the rf antenna in krypton helicon plasmas. At the start of the discharge, the neutral density underneath the antenna is reduced to 1% of its initial value in 15 ?s. The ionization rate inferred from these data implies that the electron temperature near the antenna is much higher than the electron temperature measured downstream. Neutral density measurements made downstream from the antenna show much slower depletion, requiring 14 ms to decrease by a factor of 1/e. Furthermore, the downstream depletion appears to be due to neutral pumping rather than ionization.
Dynamics of false vacuum bubbles: beyond the thin shell approximation
Jakob Hansen; Dong-il Hwang; Dong-han Yeom
2009-11-08T23:59:59.000Z
We numerically study the dynamics of false vacuum bubbles which are inside an almost flat background; we assumed spherical symmetry and the size of the bubble is smaller than the size of the background horizon. According to the thin shell approximation and the null energy condition, if the bubble is outside of a Schwarzschild black hole, unless we assume Farhi-Guth-Guven tunneling, expanding and inflating solutions are impossible. In this paper, we extend our method to beyond the thin shell approximation: we include the dynamics of fields and assume that the transition layer between a true vacuum and a false vacuum has non-zero thickness. If a shell has sufficiently low energy, as expected from the thin shell approximation, it collapses (Type 1). However, if the shell has sufficiently large energy, it tends to expand. Here, via the field dynamics, field values of inside of the shell slowly roll down to the true vacuum and hence the shell does not inflate (Type 2). If we add sufficient exotic matters to regularize the curvature near the shell, inflation may be possible without assuming Farhi-Guth-Guven tunneling. In this case, a wormhole is dynamically generated around the shell (Type 3). By tuning our simulation parameters, we could find transitions between Type 1 and Type 2, as well as between Type 2 and Type 3. Between Type 2 and Type 3, we could find another class of solutions (Type 4). Finally, we discuss the generation of a bubble universe and the violation of unitarity. We conclude that the existence of a certain combination of exotic matter fields violates unitarity.
Density Prediction of Uranium-6 Niobium Ingots
D.F.Teter; P.K. Tubesing; D.J.Thoma; E.J.Peterson
2003-04-15T23:59:59.000Z
The densities of uranium-6 niobium (U-Nb) alloys have been compiled from a variety of literature sources such as Y-12 and Rocky Flats datasheets. We also took advantage of the 42 well-pedigreed, homogeneous baseline U-Nb alloys produced under the Enhanced Surveillance Program for density measurements. Even though U-Nb alloys undergo two-phase transitions as the Nb content varies from 0 wt. % to 8 wt %, the theoretical and measured densities vary linearly with Nb content. Therefore, the effect of Nb content on the density was modeled with a linear regression. From this linear regression, a homogeneous ingot of U-6 wt.% Nb would have a density of 17.382 {+-} 0.040 g/cc (95% CI). However, ingots produced at Y-12 are not homogeneous with respect to the Nb content. Therefore, using the 95% confidence intervals, the density of a Y-12 produced ingot would vary from 17.310 {+-} 0.043 g/cc at the center to 17.432 {+-} 0.039 g/cc at the edge. Ingots with larger Nb inhomogeneities will also have larger variances in the density.
Effect of low density H-mode operation on edge and divertor plasma parameters
Maingi, R. [Oak Ridge Associated Universities, Inc., TN (United States); Mioduszewski, P.K. [Oak Ridge National Lab., TN (United States); Cuthbertson, J.W. [Sandia National Labs., Albuquerque, NM (United States)] [and others
1994-07-01T23:59:59.000Z
We present a study of the impact of H-mode operation at low density on divertor plasma parameters on the DIII-D tokamak. The line-average density in H-mode was scanned by variation of the particle exhaust rate, using the recently installed divertor cryo-condensation pump. The maximum decrease (50%) in line-average electron density was accompanied by a factor of 2 increase in the edge electron temperature, and 10% and 20% reductions in the measured core and divertor radiated power, respectively. The measured total power to the inboard divertor target increased by a factor of 3, with the major contribution coming from a factor of 5 increase in the peak heat flux very close to the inner strike point. The measured increase in power at the inboard divertor target was approximately equal to the measured decrease in core and divertor radiation.
Spectral density of the Dirac operator in two-flavour QCD
Georg P. Engel; Leonardo Giusti; Stefano Lottini; Rainer Sommer
2014-11-24T23:59:59.000Z
We compute the spectral density of the (Hermitean) Dirac operator in Quantum Chromodynamics with two light degenerate quarks near the origin. We use CLS/ALPHA lattices generated with two flavours of O(a)-improved Wilson fermions corresponding to pseudoscalar meson masses down to 190 MeV, and with spacings in the range 0.05-0.08 fm. Thanks to the coverage of parameter space, we can extrapolate our data to the chiral and continuum limits with confidence. The results show that the spectral density at the origin is non-zero because the low modes of the Dirac operator do condense as expected in the Banks-Casher mechanism. Within errors, the spectral density turns out to be a constant function up to eigenvalues of approximately 80 MeV. Its value agrees with the one extracted from the Gell-Mann-Oakes-Renner relation.
Molecular Density Functional Theory for water with liquid-gas coexistence and correct pressure
Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel
2015-01-01T23:59:59.000Z
The solvation of hydrophobic solutes in water is special because liquid and gas are almost at coexistence. In the common hypernetted chain approximation to integral equations, or equivalently in the homogenous reference fluid of molecular density functional theory, coexistence is not taken into account. Hydration structures and energies of nanometer-scale hydrophobic solutes are thus incorrect. In this article, we propose a bridge functional that corrects this thermodynamic inconsistency by introducing a metastable gas phase for the homogeneous solvent. We show how this can be done by a third order expansion of the functional around the bulk liquid density that imposes the right pressure and the correct second order derivatives. Although this theory is not limited to water, we apply it to study hydrophobic solvation in water at room temperature and pressure and compare the results to all-atom simulations. With this correction, molecular density functional theory gives, at a modest computational cost, quantita...
Dark Energy Regulation with Approximate Emergent Conformal Symmetry
Yongsung Yoon
2013-08-28T23:59:59.000Z
A cosmic potential which can relax the vacuum energy is proposed in a framework of scalar-tensor gravity. In the phase of the gravity scalar field around the evolution with an approximate emergent conformal symmetry, we have obtained a set of cosmological equations with the dark energy regulated to the order of a conformal anomaly parameter. Through a role of the cosmic potential, the vacuum energy which could be generated in matter Lagrangian does not contribute to the dark energy in the phase.
Breakdown of the Dipole Approximation in Strong-Field Ionization
A. Ludwig; J. Maurer; B. W. Mayer; C. R. Phillips; L. Gallmann; U. Keller
2014-10-02T23:59:59.000Z
We report the breakdown of the electric dipole approximation in the long-wavelength limit in strong-field ionization with linearly polarized few-cycle mid-infrared laser pulses at intensities on the order of 10$^{13}$ W/cm$^2$. Photoelectron momentum distributions were recorded by velocity map imaging and projected onto the beam propagation axis. We observe an increasing shift of the peak of this projection opposite to the beam propagation direction with increasing laser intensities. From a comparison with semi-classical simulations, we identify the combined action of the magnetic field of the laser pulse and the Coulomb potential as origin of our observations.
Invariant-based pulse engineering without rotating wave approximation
S. Ibáńez; Yi-Chao Li; Xi Chen; J. G. Muga
2015-07-02T23:59:59.000Z
We inverse engineer realizable time-dependent semiclassical pulses to invert or manipulate a two- level system faster than adiabatically when the rotating-wave approximation cannot be applied. Different inversion routes, based on a counterdiabatic approach or invariants, lead quite generally to singular fields. Making use of the relation between the invariants of motion and the Hamiltonian, and canceling the troublesome singularities, an inversion scheme is put forward for the regime in which the pulse spans few oscillations. For many oscillations an alternative numerical minimization method is proposed and demonstrated.
Analytical Approximation for 2-D Nonlinear Periodic Deep Water Waves
Saleh Tanveer
2013-09-20T23:59:59.000Z
A recently developed method has been extended to a nonlocal equation arising in steady water wave propagation in two dimensions. We obtain analyic approximation of steady water wave solution in two dimensions with rigorous error bounds for a set of parameter values that correspond to heights slightly smaller than the critical. The wave shapes are shown to be analytic. The method presented in quite general and does not assume smallness of wave height or steepness and can be readily extended to other interfacial problems involving Laplace's equation.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1988-05-26T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1991-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1989-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density .ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 .ANG.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1989-10-10T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density [<=]100 mg/cc; cell size [<=]0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 [angstrom]. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Instabilities in the Nuclear Energy Density Functional
M. Kortelainen; T. Lesinski
2010-02-05T23:59:59.000Z
In the field of Energy Density Functionals (EDF) used in nuclear structure and dynamics, one of the unsolved issues is the stability of the functional. Numerical issues aside, some EDFs are unstable with respect to particular perturbations of the nuclear ground-state density. The aim of this contribution is to raise questions about the origin and nature of these instabilities, the techniques used to diagnose and prevent them, and the domain of density functions in which one should expect a nuclear EDF to be stable.
Hardness of Approximate Hypergraph Coloring Venkatesan Guruswami Johan Hastad y Madhu Sudan z
Guruswami, Venkatesan
Hardness of Approximate Hypergraph Coloring Venkatesan Guruswami #3; Johan HĹĄastad y Madhu Sudan #3
1.85 Approximation for Min-Power Strong Connectivity
Calinescu, Gruia
2012-01-01T23:59:59.000Z
Given a directed simple graph G=(V,E) and a nonnegative-valued cost function the power of a vertex u in a directed spanning subgraph H is given by the maximum cost of an arcs of H exiting u. The power of H is the sum of the power of its vertices. Power Assignment seeks to minimize the power of H while H satisfies some connectivity constraint. In this paper, we assume E is bidirected (for every directed edge e in E, the opposite edge exists and has the same cost), while H is required to be strongly connected. This is the original power assignment problem introduced by Chen and Huang in 1989, who proved that bidirected minimum spanning tree has approximation ratio at most 2 (this is tight). In Approx 2010, we introduced a Greedy approximation algorithm and claimed a ratio of 1.992. Here we improve the analysis to 1.85. The proof also shows that a natural linear programming relaxation, introduced by us in 2012, has the same 1.85 integrality gap.
Approximation Algorithms for Wireless Link Scheduling with Flexible Data Rates
Kesselheim, Thomas
2012-01-01T23:59:59.000Z
We consider scheduling problems in wireless networks with respect to flexible data rates. That is, more or less data can be transmitted per time depending on the signal quality, which is determined by the signal-to-interference-plus-noise ratio (SINR). Each wireless link has a utility function mapping SINR values to the respective data rates. We have to decide which transmissions are performed simultaneously and (depending on the problem variant) also which transmission powers are used. In the capacity-maximization problem, one strives to maximize the overall network throughput, i.e., the summed utility of all links. For arbitrary utility functions (not necessarily continuous ones), we present an O(log n)-approximation when having n communication requests. This algorithm is built on a constant-factor approximation for the special case of the respective problem where utility functions only consist of a single step. In other words, each link has an individual threshold and we aim at maximizing the number of lin...
Density controlled carbon nanotube array electrodes
Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)
2008-12-16T23:59:59.000Z
CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.
High density load bearing insulation peg
Nowobilski, J.J.; Owens, W.J.
1985-01-29T23:59:59.000Z
A high density peg is disclosed which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure. 4 figs.
Primordial Density Fluctuations in Phase Coupling Gravity
C. E. M. Batista; M. Schiffer
1996-01-10T23:59:59.000Z
In this paper we study the evolution of density perturbations in the framework of Phase Coupling Gravity theory at the very early universe. We show that these perturbation display an exponential-like behaviour.
Density shock waves in confined microswimmers
Tsang, Alan Cheng Hou
2015-01-01T23:59:59.000Z
Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from `subsonic' with compression at the back to `supersonic' with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a non-trivial interplay between hydrodynamic interactions and geometric confinement, and is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechan...
Magnetic fields and density functional theory
Salsbury Jr., Freddie
1999-02-01T23:59:59.000Z
A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.
Tweedie Family Densities: Methods of Evaluation
Smyth, Gordon K.
of Queensland, St Lucia, Q 4072, Australia. 2 University of Southern Queensland, Toowoomba, Q 4350, Australia. Tweedie family densities are characterised by power variance functions of the form V[ľ] = ľp , where p
Breast Density and Cancer | GE Global Research
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Breast Cancer Awareness Series: Understanding Breast Density Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in...
Spacetime Average Density (SAD) cosmological measures
Page, Don N., E-mail: profdonpage@gmail.com [Department of Physics, 4-183 CCIS, University of Alberta, Edmonton, Alberta, T6G 2E1 Canada (Canada)
2014-11-01T23:59:59.000Z
The measure problem of cosmology is how to obtain normalized probabilities of observations from the quantum state of the universe. This is particularly a problem when eternal inflation leads to a universe of unbounded size so that there are apparently infinitely many realizations or occurrences of observations of each of many different kinds or types, making the ratios ambiguous. There is also the danger of domination by Boltzmann Brains. Here two new Spacetime Average Density (SAD) measures are proposed, Maximal Average Density (MAD) and Biased Average Density (BAD), for getting a finite number of observation occurrences by using properties of the Spacetime Average Density (SAD) of observation occurrences to restrict to finite regions of spacetimes that have a preferred beginning or bounce hypersurface. These measures avoid Boltzmann brain domination and appear to give results consistent with other observations that are problematic for other widely used measures, such as the observation of a positive cosmological constant.
Shock compression of low-density foams
Holmes, N.C.
1993-07-01T23:59:59.000Z
Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.
Spin- and Pair-Density-Wave Glasses
Mross, David F.
Spontaneous breaking of translational symmetry, known as density-wave order, is common in nature. However, such states are strongly sensitive to impurities or other forms of frozen disorder leading to fascinating glassy ...
Alpha track density using a semiconductor detector
Hamilton, Ian Scott
1993-01-01T23:59:59.000Z
Determination of the alpha track density in the cellulose nitrate (CN) dielectric version of solid state nuclear track detectors (SSNTD) has traditionally been tedious work which produced results that relied upon the person counting the film as well...
The Chemistry of Atherogenic High Density Lipoprotein
Moore, D'Vesharronne J.
2012-07-16T23:59:59.000Z
An array of analytical methods including density gradient ultracentrifugation, capillary electrophoresis, and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), were utilized to analyze serum high ...
LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS
Kutyniok, Gitta
LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS KARLHEINZ GRÂ¨OCHENIG, GITTA KUTYNIOK's conditions to the setting of locally compact abelian (LCA) groups, relying in an analogous way on the basics
Alpha track density using a semiconductor detector
Hamilton, Ian Scott
1993-01-01T23:59:59.000Z
of factors including variation in the initial dielectric thickness, and other undefined parameters. In addition, the resultant radon concentration reading is dependent upon the calibration factor used to interpret the track density reading. Obtaining...
Approximate models for the ion-kinetic regime in
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformation Access toTenEnvironmentdecaysspin-density-waveinertial-confinement-fusion
Levy, Mel, E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States) [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, North Carolina A and T State University, Greensboro, North Carolina 27411 (United States); Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Anderson, James S. M.; Zadeh, Farnaz Heidar; Ayers, Paul W., E-mail: ayers@mcmaster.ca, E-mail: mlevy@tulane.edu [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario (Canada)
2014-05-14T23:59:59.000Z
Properties of exact density functionals provide useful constraints for the development of new approximate functionals. This paper focuses on convex sums of ground-level densities. It is observed that the electronic kinetic energy of a convex sum of degenerate ground-level densities is equal to the convex sum of the kinetic energies of the individual degenerate densities. (The same type of relationship holds also for the electron-electron repulsion energy.) This extends a known property of the Levy-Valone Ensemble Constrained-Search and the Lieb Legendre-Transform refomulations of the Hohenberg-Kohn functional to the individual components of the functional. Moreover, we observe that the kinetic and electron-repulsion results also apply to densities with fractional electron number (even if there are no degeneracies), and we close with an analogous point-wise property involving the external potential. Examples where different degenerate states have different kinetic energy and electron-nuclear attraction energy are given; consequently, individual components of the ground state electronic energy can change abruptly when the molecular geometry changes. These discontinuities are predicted to be ubiquitous at conical intersections, complicating the development of universally applicable density-functional approximations.
Treuille, Adrien
)-approximate with O(log4 n) congestion. This translates back to a O(log4+3 n)-approximation for the multicast energy-minimization)-approximate with O(log12 n) congestion, which translates back to a O(log12+5 n)-approximation for the unicast energy-minimizationCluster Before You Hallucinate: Approximating Node-Capacitated Network Design and Energy Efficient
Redshift Evolution of Galaxy Cluster Densities
R. G. Carlberg; S. L. Morris; H. K. C. Yee; E. Ellingson
1997-01-20T23:59:59.000Z
The number of rich galaxy clusters per unit volume is a strong function of Omega, the cosmological density parameter, and sigma_8, the linear extrapolation to z=0 of the density contrast in 8/h Mpc spheres. The CNOC cluster redshift survey provides a sample of clusters whose average mass profiles are accurately known, which enables a secure association between cluster numbers and the filtered density perturbation spectrum. We select from the CNOC cluster survey those EMSS clusters with bolometric L_x>=10^45 erg/s and a velocity dispersion exceeding 800 km/s in the redshift ranges 0.18-0.35 and 0.35-0.55. We compare the number density of these subsamples with similar samples at both high and low redshift. Using the Press-Schechter formalism and CDM style structure models, the density data are described with sigma_8=0.75+/-0.1 and Omega=0.4+/-0.2 (90% confidence). The cluster dynamical analysis gives Omega=0.2+/-0.1$ for which sigma_8=0.95+/-0.1 (90% confidence). The predicted cluster density evolution in an \\Omega=1 CDM model exceeds that observed by more than an order of magnitude.
Ligand identification using electron-density mapcorrelations
Terwilliger, Thomas C.; Adams, Paul D.; Moriarty, Nigel W.; Cohn,Judith D.
2006-12-01T23:59:59.000Z
A procedure for the identification of ligands bound incrystal structuresof macromolecules is described. Two characteristics ofthe density corresponding to a ligand are used in the identificationprocedure. One is the correlation of the ligand density with each of aset of test ligands after optimization of the fit of that ligand to thedensity. The other is the correlation of a fingerprint of the densitywith the fingerprint of model density for each possible ligand. Thefingerprints consist of an ordered list of correlations of each the testligands with the density. The two characteristics are scored using aZ-score approach in which the correlations are normalized to the mean andstandard deviation of correlations found for a variety of mismatchedligand-density pairs, so that the Z scores are related to the probabilityof observing a particular value of the correlation by chance. Theprocedure was tested with a set of 200 of the most commonly found ligandsin the Protein Data Bank, collectively representing 57 percent of allligands in the Protein Data Bank. Using a combination of these twocharacteristics of ligand density, ranked lists of ligand identificationswere made for representative (F-o-F-c) exp(i phi(c)) difference densityfrom entries in the Protein Data Bank. In 48 percent of the 200 cases,the correct ligand was at the top of the ranked list of ligands. Thisapproach may be useful in identification of unknown ligands in newmacromolecular structures as well as in the identification of whichligands in a mixture have bound to a macromolecule.
Electron density measurements in a pulse-repetitive microwave discharge in air
Nikolic, M.; Popovic, S.; Vuskovic, L. [Department of Physics, Center for Accelerator Science, Old Dominion University, Norfolk, Virginia 23529 (United States); Herring, G. C.; Exton, R. J. [NASA Langley Research Center, Hampton, Virginia 23681 (United States)
2011-12-01T23:59:59.000Z
We have developed a technique for absolute measurements of electron density in pulse-repetitive microwave discharges in air. The technique is based on the time-resolved absolute intensity of a nitrogen spectral band belonging to the Second Positive System, the kinetic model and the detailed particle balance of the N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) state. This new approach bridges the gap between two existing electron density measurement methods (Langmuir probe and Stark broadening). The electron density is obtained from the time-dependent rate equation for the population of N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) using recorded waveforms of the absolute C{sup 3}{Pi}{sub u}{yields}B{sup 3}{Pi}{sub g} (0-0) band intensity, the forward and reflected microwave power density. Measured electron density waveforms using numerical and approximated analytical methods are presented for the case of pulse repetitive planar surface microwave discharge at the aperture of a horn antenna covered with alumina ceramic plate. The discharge was generated in air at 11.8 Torr with a X-band microwave generator using 3.5 {mu}s microwave pulses at peak power of 210 kW. In this case, we were able to time resolve the electron density within a single 3.5 {mu}s pulse. We obtained (9.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the peak and (5.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the pulse-average electron density. The technique presents a convenient, non-intrusive diagnostic method for local, time-defined measurements of electron density in short duration discharges near atmospheric pressures.
Approximate Weighted Matching On Emerging Manycore and Multithreaded Architectures
Halappanavar, Mahantesh; Feo, John T.; Villa, Oreste; Tumeo, Antonino; Pothen, Alex
2012-11-30T23:59:59.000Z
Graph matching is a prototypical combinatorial problem with many applications in computer science and scientific computing, but algorithms for computing optimal matchings are challenging to parallelize. Approximate matching algorithms provide an alternate route for parallelization, and in many contexts compute near-optimal matchings for large-scale graphs. We present sharedmemory parallel implementations for computing half-approximate weighted matching on state-of-the-art multicore (Intel Nehalem and AMD Magny-Cours), manycore (Nvidia Tesla and Nvidia Fermi) and massively multithreaded (Cray XMT) platforms. We provide two implementations: the first implementation uses shared work queues, and is suited to all these platforms; the second implementation is based on dataflow principles, and exploits the architectural features of the Cray XMT. Using a carefully chosen dataset that exhibits characteristics from a wide range of real-world applications, we show scalable performance across different platforms. In particular, for one instance of the input, an R-MAT graph (RMAT-G), we show speedups of: about 32 on 48 cores of an AMD Magny-Cours; 7 on 8 cores of Intel Nehalem; 3 on Nvidia Tesla and 10 on Nvidia Fermi relative to one core of Intel Nehalem; and 60 on 128 processors of Cray XMT. We demonstrate good weak and strong scaling for graphs with up to a billion edges using up to 12, 800 threads. Given the breadth of this work, we focus on simplicity and portability of software rather than excessive fine-tuning for each platform. To the best of our knowledge, this is the first such large-scale study of the half-approximate weighted matching problem on shared-memory platforms. Driven by the critical enabling role of combinatorial algorithms such as matching in scientific computing and the emergence of informatics applications, there is a growing demand to support irregular computations on current and future computing platforms. In this context, we evaluate the capability of emerging multithreaded platforms to tolerate latency induced by irregular memory access patterns, and to support fine-grained parallelism via light-weight synchronization mechanisms. By contrasting the architectural features of these platforms against the Cray XMT, which is specifically designed to support irregular memory-intensive applications, we delineate the impact of these choices on performance.
Shear Viscosity in the Post-quasistatic Approximation
C. Peralta; L. Rosales; B. Rodrí guez-Mueller; W. Barreto
2010-04-20T23:59:59.000Z
We apply the post-quasi--static approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of anisotropic non-adiabatic radiating and dissipative distributions in General Relativity. Dissipation is described by viscosity and free-streaming radiation, assuming an equation of state to model anisotropy induced by the shear viscosity. We match the interior solution, in non-comoving coordinates, with the Vaidya exterior solution. Two simple models are presented, based on the Schwarzschild and Tolman VI solutions, in the non--adiabatic and adiabatic limit. In both cases the eventual collapse or expansion of the distribution is mainly controlled by the anisotropy induced by the viscosity.
Approximate Message Passing with Restricted Boltzmann Machine Priors
Tramel, Eric W; Krzakala, Florent
2015-01-01T23:59:59.000Z
Approximate Message Passing (AMP) has been shown to be an excellent statistical approach to signal inference and compressed sensing problem. The AMP framework provides modularity in the choice of signal prior; here we propose a hierarchical form of the Gauss-Bernouilli prior which utilizes a Restricted Boltzmann Machine (RBM) trained on the signal support to push reconstruction performance beyond that of simple iid priors for signals whose support can be well represented by a trained binary RBM. We present and analyze two methods of RBM factorization and demonstrate how these affect signal reconstruction performance within our proposed algorithm. Finally, using the MNIST handwritten digit dataset, we show experimentally that using an RBM allows AMP to approach oracle-support performance.
Particle-particle random phase approximation applied to Beryllium isotopes
Guillaume Blanchon; Nicole Vinh Mau; Angela Bonaccorso; Marc Dupuis; Nathalie Pillet
2010-07-16T23:59:59.000Z
This work is dedicated to the study of even-even 8-14 Be isotopes using the particle-particle Random Phase Approximation that accounts for two-body correlations in the core nucleus. A better description of energies and two-particle amplitudes is obtained in comparison with models assuming a neutron closed-shell (or subshell) core. A Wood-Saxon potential corrected by a phenomenological particle-vibration coupling term has been used for the neutron-core interaction and the D1S Gogny force for the neutron-neutron interaction. Calculated ground state properties as well as excited state ones are discussed and compared to experimental data. In particular, results suggest the same 2s_1/2-1p_1/2 shell inversion in 13Be as in 11Be.
A renormalisation group method. II. Approximation by local polynomials
David C. Brydges; Gordon Slade
2014-11-25T23:59:59.000Z
This paper is the second in a series devoted to the development of a rigorous renormalisation group method for lattice field theories involving boson fields, fermion fields, or both. The method is set within a normed algebra $\\mathcal{N}$ of functionals of the fields. In this paper, we develop a general method---localisation---to approximate an element of $\\mathcal{N}$ by a local polynomial in the fields. From the point of view of the renormalisation group, the construction of the local polynomial corresponding to $F$ in $\\mathcal{N}$ amounts to the extraction of the relevant and marginal parts of $F$. We prove estimates relating $F$ and its corresponding local polynomial, in terms of the $T_{\\phi}$ semi-norm introduced in part I of the series.
Pion - Nucleon Bremsstrahlung beyond the Soft-Photon approximation
A. Mariano
2000-04-06T23:59:59.000Z
A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction $ \\pi N \\to \\pi N \\gamma$ at low energies. The $\\Delta(1232)$ degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off the momentum-shell effects. The double differential distribution of photons is computed for three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behaviour of the different T-matrices under consideration. Finally an alternative simpler dynamical model that incorporates the unstable character of the isobar-$\\Delta(1232)$ through a complex mass, is presented. As we will see it is suitable for the study of the magnetic moment of the resonance.
Polymer quantization and the saddle point approximation of partition functions
Hugo A. Morales Técotl; Daniel H. Orozco Borunda; Saeed Rastgoo
2015-07-31T23:59:59.000Z
The saddle point approximation of the path integral partition functions is an important way of deriving the thermodynamical properties of black holes. However, there are certain black hole models and some mathematically analog mechanical models for which this method can not be applied directly. This is due to the fact that their action evaluated on a classical solution is not finite and its first variation does not vanish for all consistent boundary conditions. These problems can be dealt with by adding a counter-term to the classical action, which is a solution of the corresponding Hamilton-Jacobi equation. In this work we study the effects of polymer quantization on a mechanical model presenting the aforementioned difficulties and contrast it with the above counter-term method. This type of quantization for mechanical models is motivated by the loop quantization of gravity which is known to play a role in the thermodynamics of black holes systems. The model we consider is a non relativistic particle in an inverse square potential and analyze two polarizations of the polymer quantization in which either the position or the momentum is discrete. In the former case, Thiemann's regularization is applied to represent the inverse power potential but we still need to incorporate the Hamilton-Jacobi counter-term which is now modified by polymer corrections. In the latter, momentum discrete case however, such regularization could not be implemented. Yet, remarkably, due to the fact that the position is bounded, we do not need a Hamilton-Jacobi counter-term in order to have a well defined saddle point approximation. Further developments and extensions are commented upon in the discussion.
Holzwarth, Natalie
, RMP 80, 3 (2008). [2] P. Bl¨ochl, PRB 50, 17953 (1994); N. A. W. Holzwarth et al, PRB 55, 2005 (1997). [3] J. Paier et al, JCP 122, 234102 (2005). [4] R. A. Hyman et al, PRB 62, 15521 (2000). [5] S. K
Precise and Accurate Density Determination of Explosives Using Hydrostatic Weighing
B. Olinger
2005-07-01T23:59:59.000Z
Precise and accurate density determination requires weight measurements in air and water using sufficiently precise analytical balances, knowledge of the densities of air and water, knowledge of thermal expansions, availability of a density standard, and a method to estimate the time to achieve thermal equilibrium with water. Density distributions in pressed explosives are inferred from the densities of elements from a central slice.
Approximation Techniques for Incompressible Flows with Heterogeneous Properties
Salgado Gonzalez, Abner Jonatan
2011-10-21T23:59:59.000Z
; 1, 1:5, 2, 2:5, 3, 3:5, 4 and 4:5 : : : : : : : : : : : : 115 6 Falling Drop. Re = 1000; density ratio 100: The interface is shown at times 0; 1:5; 2, 2:25, 2:5, 2:75, 2:9, 3, 3:1, 3:2, 3:3 and 3:35 : : : : 117 1 CHAPTER I INTRODUCTION The e... on and normed, for 1 q <1; by kvkLq := Z jvjq 1=q ; and, for q =1 kvkL1 := esssup x2 jvj: For which these spaces are Banach spaces. In the case q = 2 we denote by h ; i the L2-scalar product. By W sq ( ); for an integer s; we denote...
Fabrication of low density ceramic material
Meek, T.T.; Blake, R.D.; Sheinberg, H.
1985-01-01T23:59:59.000Z
A precursor mixture and a method of making a low-density ceramic structural material are disclosed. The precursor mixture includes hollow microballoons, typically made of glass, together with a cementing agent capable of being cured by microwave irradiation. A preferred cementing agent is liquid hydrated potassium silicate, which is mixed with the glass microballoons to form a slurry. Upon irradiation the potassium silicate is dehydrated to form a solid porous matrix in which the microballoons are evenly distributed. Ground glass or other filling agents may be included in the slurry to enhance the properties of the final product. Low-density structural ceramics having densities on the order of 0.1 to 0.3 are obtained.
Statistical approach to nuclear level density
Sen'kov, R. A.; Horoi, M. [Department of Physics, Central Michigan University, Mount Pleasant, MI 48859 (United States); Zelevinsky, V. G. [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States)
2014-10-15T23:59:59.000Z
We discuss the level density in a finite many-body system with strong interaction between the constituents. Our primary object of applications is the atomic nucleus but the same techniques can be applied to other mesoscopic systems. We calculate and compare nuclear level densities for given quantum numbers obtained by different methods, such as nuclear shell model (the most successful microscopic approach), our main instrument - moments method (statistical approach), and Fermi-gas model; the calculation with the moments method can use any shell-model Hamiltonian excluding the spurious states of the center-of-mass motion. Our goal is to investigate statistical properties of nuclear level density, define its phenomenological parameters, and offer an affordable and reliable way of calculation.
High power density solid oxide fuel cells
Pham, Ai Quoc; Glass, Robert S.
2004-10-12T23:59:59.000Z
A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.
Balsa Terzic, Gabriele Bassi
2011-07-01T23:59:59.000Z
In this paper we discuss representations of charge particle densities in particle-in-cell (PIC) simulations, analyze the sources and profiles of the intrinsic numerical noise, and present efficient methods for their removal. We devise two alternative estimation methods for charged particle distribution which represent significant improvement over the Monte Carlo cosine expansion used in the 2d code of Bassi, designed to simulate coherent synchrotron radiation (CSR) in charged particle beams. The improvement is achieved by employing an alternative beam density estimation to the Monte Carlo cosine expansion. The representation is first binned onto a finite grid, after which two grid-based methods are employed to approximate particle distributions: (i) truncated fast cosine transform (TFCT); and (ii) thresholded wavelet transform (TWT). We demonstrate that these alternative methods represent a staggering upgrade over the original Monte Carlo cosine expansion in terms of efficiency, while the TWT approximation also provides an appreciable improvement in accuracy. The improvement in accuracy comes from a judicious removal of the numerical noise enabled by the wavelet formulation. The TWT method is then integrated into Bassi's CSR code, and benchmarked against the original version. We show that the new density estimation method provides a superior performance in terms of efficiency and spatial resolution, thus enabling high-fidelity simulations of CSR effects, including microbunching instability.
Density matrix of black hole radiation
Lasma Alberte; Ram Brustein; Andrei Khmelnitsky; A. J. M. Medved
2015-02-09T23:59:59.000Z
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective field-theory perspective, are much less suppressed and grow monotonically in time. In this case, the R\\'enyi entropy for the outgoing radiation is shown to grow linearly at early times; but this growth slows down and the entropy eventually starts to decrease at the Page time. In addition to comparing models, we emphasize the distinction between the state of the radiation emitted from a black hole, which is highly quantum, and that of the radiation emitted from a typical classical black body at the same temperature.
Low density, microcellular foams, preparation, and articles
Young, A.T.
1982-03-03T23:59:59.000Z
A microcellular low-density foam of poly(4-methyl-1-pentene) particularly useful for forming targets for inertial confinement fusion has been developed. Articles made from the foam have been machined to tolerances of 0.0001 inch, although the densities of the fragile foam are low (about 10 to about 100 mg/cc) and the cell sizes are small (about 10 to about 30 ..mu..m). Methods for forming the foam and articles are given. The yield strength of the foam of the invention is higher than was obtained in other structures of this same material.
Density functional theory study of (OCS)2^-
Bilalbegovic, G
2007-01-01T23:59:59.000Z
The structural and electronic properties of the carbonyl sulfide dimer anion are calculated using density functional theory within a pseudopotential method. Three geometries are optimized and investigated: C2v and C2 symmetric, as well as one asymmetric structure. A distribution of an excess charge in three isomers are studied by the Hirshfeld method. In an asymmetric (OCS)2^- isomer the charge is not equally divided between the two moieties, but it is distributed as OCS^{-0.6} OCS^{-0.4}. Low-lying excitation levels of three isomers are compared using the time-dependent density functional theory in the Casida approach.
Low density, microcellular foams, preparation, and articles
Young, Ainslie T. (Los Alamos, NM); Marsters, Robert G. (Jemez Springs, NM); Moreno, Dawn K. (Espanola, NM)
1984-01-01T23:59:59.000Z
A microcellular low density foam of poly(4-methyl-1-pentene) which is particularly useful for forming targets for inertial confinement fusion has been developed. Articles made from the foam have been machined to tolerances of 0.0001 inch, although the densities of the fragile foam are low (about 10 to about 100 mg/cc) and the cell sizes are small (about 10 to about 30 .mu.m). Methods for forming the foam and articles are given; and the yield strength of the foam of the invention is higher than was obtained in other structures of this same material.
Level densities of transitional Sm nuclei
Capote, R.; Ventura, A.; Cannata, F.; Quesada, J.M. [Nuclear Data Section, International Atomic Energy Agency, Vienna (Austria); Ente Nuove Tecnologie, Energia e Ambiente, and Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Dipartimento di Fisica dell Universita and Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla (Spain)
2005-06-01T23:59:59.000Z
Experimentally determined level densities of the transitional isotopes {sup 148,149,150,152}Sm at excitation energies below and around the neutron binding energy are compared with microcanonical calculations based on a Monte Carlo approach to noncollective level densities, folded with a collective enhancement estimated in the frame of the interacting boson model (IBM). The IBM parameters are adjusted so as to reproduce the low-lying discrete levels of both parities, with the exception of the odd-mass nucleus, {sup 149}Sm, where complete decoupling of the unpaired neutron from the core is assumed.
Error Analysis in Nuclear Density Functional Theory
Nicolas Schunck; Jordan D. McDonnell; Jason Sarich; Stefan M. Wild; Dave Higdon
2014-07-11T23:59:59.000Z
Nuclear density functional theory (DFT) is the only microscopic, global approach to the structure of atomic nuclei. It is used in numerous applications, from determining the limits of stability to gaining a deep understanding of the formation of elements in the universe or the mechanisms that power stars and reactors. The predictive power of the theory depends on the amount of physics embedded in the energy density functional as well as on efficient ways to determine a small number of free parameters and solve the DFT equations. In this article, we discuss the various sources of uncertainties and errors encountered in DFT and possible methods to quantify these uncertainties in a rigorous manner.
High power density supercapacitors using locally aligned carbon nanotube electrodes
Du, C S; Yeh, J; Pan, Ning
2005-01-01T23:59:59.000Z
4484/16/4/003 High power density supercapacitors usingproduced very high speci?c power density of about 30 kW kg ?manufacturing of high power density supercapacitors and
High-power-density spot cooling using bulk thermoelectrics
Zhang, Y; Shakouri, A; Zeng, G H
2004-01-01T23:59:59.000Z
model, the cooling power densities of the devices can alsothe cooling power densities 224 times. Experimentally, the14 4 OCTOBER 2004 High-power-density spot cooling using bulk
Asymptotic safety in the f(R) approximation
Juergen A. Dietz; Tim R. Morris
2013-01-28T23:59:59.000Z
In the asymptotic safety programme for quantum gravity, it is important to go beyond polynomial truncations. Three such approximations have been derived where the restriction is only to a general function f(R) of the curvature R>0. We confront these with the requirement that a fixed point solution be smooth and exist for all non-negative R. Singularities induced by cutoff choices force the earlier versions to have no such solutions. However, we show that the most recent version has a number of lines of fixed points, each supporting a continuous spectrum of eigen-perturbations. We uncover and analyse the first five such lines. Sensible fixed point behaviour may be achieved if one consistently incorporates geometry/topology change. As an exploratory example, we analyse the equations analytically continued to R<0, however we now find only partial solutions.We show how these results are always consistent with, and to some extent can be predicted from, a straightforward analysis of the constraints inherent in the equations.
Quasilocalized charge approximation in strongly coupled plasma physics
Golden, Kenneth I. [Department of Mathematics and Statistics, Department of Physics, University of Vermont, Burlington, Vermont 05401-1455 (United States)] [Department of Mathematics and Statistics, Department of Physics, University of Vermont, Burlington, Vermont 05401-1455 (United States); Kalman, Gabor J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States)] [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States)
2000-01-01T23:59:59.000Z
The quasilocalized charge approximation (QLCA) was proposed in 1990 [G. Kalman and K. I. Golden, Phys. Rev. A 41, 5516 (1990)] as a formalism for the analysis of the dielectric response tensor and collective mode dispersion in strongly coupled Coulomb liquids. The approach is based on a microscopic model in which the charges are quasilocalized on a short-time scale in local potential fluctuations. The authors review the application of the QLC approach to a variety of systems which can exhibit strongly coupled plasma behavior: (i) the one-component plasma (OCP) model in three dimensions (e.g., laser-cooled trapped ions) and (ii) in two dimensions (e.g., classical 2D electron liquid trapped above the free surface of liquid helium), (iii) binary ionic mixture in a neutralizing uniform background (e.g., carbon-oxygen white dwarf interiors), (iv) charged particle bilayers (e.g., semiconductor electronic bilayers), and (v) charged particles in polarizable background (e.g., laboratory dusty plasmas). (c) 2000 American Institute of Physics.
Polymer quantization and the saddle point approximation of partition functions
Técotl, Hugo A Morales; Rastgoo, Saeed
2015-01-01T23:59:59.000Z
The saddle point approximation of the path integral partition functions is an important way of deriving the thermodynamical properties of black holes. However, there are certain black hole models and some mathematically analog mechanical models for which this method can not be applied directly. This is due to the fact that their action evaluated on a classical solution is not finite and its first variation does not vanish for all consistent boundary conditions. These problems can be dealt with by adding a counter-term to the classical action, which is a solution of the corresponding Hamilton-Jacobi equation. In this work we study the effects of polymer quantization on a mechanical model presenting the aforementioned difficulties and contrast it with the above counter-term method. This type of quantization for mechanical models is motivated by the loop quantization of gravity which is known to play a role in the thermodynamics of black holes systems. The model we consider is a non relativistic particle in an i...
Convergence analysis of the thermal discrete dipole approximation
Edalatpour, Sheila; Trueax, Tyler; Backman, Roger; Francoeur, Mathieu
2015-01-01T23:59:59.000Z
The thermal discrete dipole approximation (T-DDA) is a numerical approach for modeling near-field radiative heat transfer in complex three-dimensional geometries. In this work, the convergence of the T-DDA is investigated using the exact solution for two spheres separated by a vacuum gap. The error associated with the T-DDA is reported for various size parameters, refractive indices and vacuum gap sizes. The results reveal that for a fixed number of sub-volumes, the accuracy of the T-DDA degrades as the refractive index and the sphere diameter to gap ratio increase. A converging trend is observed as the number of sub-volumes increases. The large computational requirements associated with increasing the number of sub-volumes, and the shape error induced by large sphere diameter to gap ratios, are mitigated by using a non-uniform discretization scheme. Non-uniform discretization is shown to significantly accelerate the convergence of the T-DDA, and is thus recommended for near-field thermal radiation simulation...
Maps of current density using density-functional methods A. Soncini,1,a
Helgaker, Trygve
, University of Durham, South Road, Durham DH1 3LE, United Kingdom Received 22 May 2008; accepted 17 July 2008 are compared and integration of the current densities to yield shielding constants is performed. In general of induced current density in molecules. Š 2008 American Institute of Physics. DOI: 10.1063/1.2969104 I
On the Determination of the Mean Cosmic Matter Density and the Amplitude of Density Fluctuations
Thomas H. Reiprich
2002-07-02T23:59:59.000Z
The cosmological implications from a new estimate of the local X-ray galaxy cluster abundance are summarized. The results are then compared to independent observations. It is suggested that `low' values for the mean cosmic matter density and the amplitude of mass density fluctuations currently do not appear unreasonable observationally.
Pauling bond strength, bond length and electron density distribution
Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, M. A.
2014-01-18T23:59:59.000Z
A power law regression equation, /r)-0.21, determined for a large number of oxide crystals at ambient conditions and /r)-0.22, determined for geometry optimized hydroxyacid molecules, that connect the bond lengths to the average Pauling electrostatic bond strength, , for the M-O bonded interactions. On the basis of the correspondence between the two sets of equations connecting ?(rc) and the Pauling bond strength s with bond length, it appears that Paulings simple definition of bond strength closely mimics the accumulation of the electron density between bonded pairs of atoms. The similarity of the expressions for the crystals and molecules is compelling evidence that the M-O bonded interactions for the crystals and molecules 2 containing the same bonded interactions are comparable. Similar expressions, connecting bond lengths and bond strength, have also been found to hold for fluoride, nitride and sulfide molecules and crystals. The Brown-Shannon bond valence, ?, power law expression ? = [R1/(R(M-O)]N that has found wide use in crystal chemistry, is shown to be connected to a more universal expression determined for oxides and the perovskites, = r[(1.41)/
Journal of Approximation Theory 147 (2007) 185195 www.elsevier.com/locate/jat
Elad, Michael
2007-01-01T23:59:59.000Z
Journal of Approximation Theory 147 (2007) 185195 www.elsevier.com/locate/jat On Lebesgue.L. Donoho et al. / Journal of Approximation Theory 147 (2007) 185195 Inequality (1.1) relates the error
Chetverikov, Denis
We derive a Gaussian approximation result for the maximum of a sum of high-dimensional random vectors. Specifically, we establish conditions under which the distribution of the maximum is approximated by that of the maximum ...
Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electron Density Distributions for Fe- and Cu-Sulfide Earth Materials: A Connection between Bond Length, Bond Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
Effects of Ambient Density and Temperature on Soot Formation...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Density and Temperature on Soot Formation under High-EGR Conditions Effects of Ambient Density and Temperature on Soot Formation under High-EGR Conditions Presentation given at...
Mitigating Breakdown in High Energy Density Perovskite Polymer...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Mitigating Breakdown in High Energy Density Perovskite Polymer Nanocomposite Capacitors Mitigating Breakdown in High Energy Density Perovskite Polymer Nanocomposite Capacitors 2012...
Real-Time Simultaneous Measurements of Size, Density, and Composition...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
of Size, Density, and Composition of Single Ultrafine Diesel Tailpipe Particles Real-Time Simultaneous Measurements of Size, Density, and Composition of Single Ultrafine Diesel...
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. Abstract: We will...
BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF...
Office of Scientific and Technical Information (OSTI)
Technical Report: BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF) Citation Details In-Document Search Title: BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL...
Pauling bond strength, bond length and electron density distribution...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Pauling bond strength, bond length and electron density distribution. Pauling bond strength, bond length and electron density distribution. Abstract: A power law regression...
Density Functional Theory Study of Oxygen Reduction Activity...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes. Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum...
A Density Functional Theory Study of Formaldehyde Adsorption...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Density Functional Theory Study of Formaldehyde Adsorption on Ceria. A Density Functional Theory Study of Formaldehyde Adsorption on Ceria. Abstract: Molecular adsorption of...
Engineering Density of States of Earth Abundant Semiconductors...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Density of States of Earth Abundant Semiconductors for Enhanced Thermoelectric Power Factor Engineering Density of States of Earth Abundant Semiconductors for Enhanced...
Using Radio Waves to Control Fusion Plasma Density
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Using Radio Waves to Control Fusion Plasma Density Using Radio Waves to Control Fusion Plasma Density Simulations Run at NERSC Support Fusion Experiments at MIT, General Atomics...
High Energy Density Laboratory Plasmas Program | National Nuclear...
National Nuclear Security Administration (NNSA)
Photo Gallery Jobs Apply for Our Jobs Our Jobs Working at NNSA Blog Home High Energy Density Laboratory Plasmas Program High Energy Density Laboratory Plasmas Program...
DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS
Bieniosek, F.M.
2010-01-01T23:59:59.000Z
for high energy density physics and fusion applications,IFSA 2007, Journal of Physics, Conference Series 112 (2008)high energy density physics experiments F. M. Bieniosek, E.
Estimating density of Florida Key deer
Roberts, Clay Walton
2006-08-16T23:59:59.000Z
for this species since 1968; however, a need to evaluate the precision of existing and alternative survey methods (i.e., road counts, mark-recapture, infrared-triggered cameras [ITC]) was desired by USFWS. I evaluated density estimates from unbaited ITCs and road...
Lipoprotein subclass analysis by immunospecific density
Lester, Sandy Marie
2009-05-15T23:59:59.000Z
Separation of Lipoprotein Particles by Single Spin Ultracentrifugation ......................................................................... 27 Layering Ultracentrifugation Tubes ............................................... 28 Digital..., and HDL. (Fig 4) 14 As one moves down the Ultracentrifugation (UC) tube, the density increases and the particle size decreases from chylomicrons to HDL. The lipoprotein fractions also differ in lipid to protein ratios, apolipoprotein...
Effective Field Theory and Finite Density Systems
R. J. Furnstahl; G. Rupak; T. Schaefer
2008-01-04T23:59:59.000Z
This review gives an overview of effective field theory (EFT) as applied at finite density, with a focus on nuclear many-body systems. Uniform systems with short-range interactions illustrate the ingredients and virtues of many-body EFT and then the varied frontiers of EFT for finite nuclei and nuclear matter are surveyed.
Density-Functional Theory for Complex Fluids
Wu, Jianzhong
. This generic methodology is built upon a mathematical theorem that states, for an equilibrium system at a given modeling of the microscopic struc- tures and phase behavior of soft-condensed matter. The methodol- ogy to the one-body density profile Grand potential: the free energy of an open system at fixed volume
Population density of San Joaquin kit fox
McCue, P.; O'Farrell, T.P.; Kato, T.; Evans, B.G.
1982-01-01T23:59:59.000Z
Populations of the endangered San Joaquin kit fox, vulpes macrotis mutica, are known to occur on the Elk Hills Naval Petroleum Reserve No. 1. This study assess the impact of intensified petroleum exploration and production and associated human activities on kit fox population density. (ACR)
ADAPTIVE DENSITY ESTIMATION WITH MASSIVE DATA SETS
Scott, David W.
recognition, density estima tion, and data visualization. However, one already hears stories of logistic the data, and some require the data to be in core. 1.1 Reversing Efficiency Roles What general solution can we propose? It is our po sition that massive data sets reverse our usual focus This research
Dynamic Evolution for Risk-Neutral Densities
2008-10-27T23:59:59.000Z
specifications of the data are as follows: the spot asset price is 590, the risk- free interest rate is ... than 10) the recovered risk-neutral densities exhibit less smoothness than in the cases .... Technical report, Purdue University, 1995. [31] A. M. ...
Photovoltaic retinal prosthesis with high pixel density
Palanker, Daniel
Photovoltaic retinal prosthesis with high pixel density Keith Mathieson1,4 , James Loudin1 to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which pixel, demonstrating the possibility of a fully integrated photovoltaic retinal prosthesis with high
Durable high-density data storage
Stutz, R.A.; Lamartine, B.C.
1996-09-01T23:59:59.000Z
This paper will discuss the Focus Ion Beam (FIB) milling process, media life considerations, and methods of reading the micromilled data. The FIB process for data storage provides a new non-magnetic storage method for archiving large amounts of data. The process stores data on robust materials such as steel, silicon, and gold coated silicon. The storage process was developed to provide a method to insure the long term storage life of data. We estimate the useful life of data written on silicon or gold coated silicon to be a few thousand years. The process uses an ion beam to carve material from the surface much like stone cutting. The deeper information is carved into the media the longer the expected life of the information. The process can read information in three formats: (1) binary at densities of 3.5 Gbits/cm{sup 2}, (2) alphanumeric at optical or non-optical density, and (3) graphical at optical and non-optical density. The formats can be mixed on the same media; and thus it is possible to record, in a human readable format, instructions that can be read using an optical microscope. These instructions provide guidance on reading the higher density information.
Density Functional Theory Models for Radiation Damage
Density Functional Theory Models for Radiation Damage S.L. Dudarev EURATOM/CCFE Fusion Association and informative as the most advanced experimental techniques developed for the observation of radiation damage investigation and assessment of radiation damage effects, offering new insight into the origin of temperature
High power density thermophotovoltaic energy conversion
Noreen, D.L. [R& D Technologies, Inc., Hoboken, New Jersey 07030 (United States); Du, H. [Department of Materials Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030 (United States)
1995-01-05T23:59:59.000Z
R&D Technologies is developing thermophotovoltaic (TPV) technology based on the use of porous/fibrous ceramic broadband-type emitter designs that utilize recuperative or regenerative techniques to improve thermal efficiency and power density. This paper describes preliminary estimates of what will be required to accomplish sufficient power density to develop a practical, commercially-viable TPV generator. It addresses the needs for improved, thermal shock-resistant, long-life porous/fibrous ceramic emitters and provides information on the photocell technology required to achieve acceptable power density in broadband-type (with selective filter) TPV systems. TPV combustors/systems operating at a temperature of 1500 {degree}C with a broadband-type emitter is proposed as a viable starting point for cost-effective TPV conversion. Based on current projections for photocell cost, system power densities of 7.5--10 watts per square centimeter of emitter area will be required for TPV to become a commercially viable technology. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Self-interaction corrections in density functional theory
Tsuneda, Takao, E-mail: ttsuneda@yamanashi.ac.jp [Fuel Cell Nanomaterials Center, University of Yamanashi, Kofu 400-0021 (Japan)] [Fuel Cell Nanomaterials Center, University of Yamanashi, Kofu 400-0021 (Japan); Hirao, Kimihiko [Computational Chemistry Unit, RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047 (Japan)] [Computational Chemistry Unit, RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047 (Japan)
2014-05-14T23:59:59.000Z
Self-interaction corrections for Kohn-Sham density functional theory are reviewed for their physical meanings, formulations, and applications. The self-interaction corrections get rid of the self-interaction error, which is the sum of the Coulomb and exchange self-interactions that remains because of the use of an approximate exchange functional. The most frequently used self-interaction correction is the Perdew-Zunger correction. However, this correction leads to instabilities in the electronic state calculations of molecules. To avoid these instabilities, several self-interaction corrections have been developed on the basis of the characteristic behaviors of self-interacting electrons, which have no two-electron interactions. These include the von Weizsäcker kinetic energy and long-range (far-from-nucleus) asymptotic correction. Applications of self-interaction corrections have shown that the self-interaction error has a serious effect on the states of core electrons, but it has a smaller than expected effect on valence electrons. This finding is supported by the fact that the distribution of self-interacting electrons indicates that they are near atomic nuclei rather than in chemical bonds.
?Linear Gas Jet with Tailored Density Profile"
KRISHNAN, Mahadevan
2012-12-10T23:59:59.000Z
Supersonic, highly collimated gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for Laser Plasma Accelerators (LPA) . Present gas jets have lengths of only 2-4 mm at densities of 1-4E19 cm-3, sufficient for self trapping and electron acceleration to energies up to ~150 MeV. Capillary structures 3 cm long have been used to accelerate beams up to 1 GeV. Capillary discharges used in LPAs serve to guide the pump laser and optimize the energy gain. A wall-stabilized capillary discharge provides a transverse profile across the channel that helps guide the laser and combat diffraction. Gas injection via a fast nozzle at one end provides some longitudinal density control, to improve the coupling. Gas jets with uniform or controlled density profiles may be used to control electron bunch injection and are being integrated into capillary experiments to add tuning of density. The gas jet for electron injection has not yet been optimized. Our Ph-I results have provided the LPA community with an alternative path to realizing a 2-3GeV electron bunch using just a gas jet. For example, our slit/blade combination gives a 15-20mm long acceleration path with tunable density profile, serving as an alternative to a 20-mm long capillary discharge with gas injection at one end. In Ph-II, we will extend these results to longer nozzles, to see whether we can synthesize 30 or 40-mm long plasma channels for LPAs.
Matrix multiplication over word-size prime fields using Bini's approximate formula
Paris-Sud XI, Université de
Matrix multiplication over word-size prime fields using Bini's approximate formula Brice Boyer Jean-Guillaume Dumas Abstract Bini's approximate formula (or border rank) for matrix multiplication achieves a better the approximate formula in the special case where the ring is Z/pZ. Besides, we show an implemen- tation ŕ la
A New Look at the High Frequency Boundary Element and Rayleigh Integral Approximations
Seybert, Andrew F.
03NVC-114 A New Look at the High Frequency Boundary Element and Rayleigh Integral Approximations D of Automotive Engineers, Inc. ABSTRACT This paper revisits the popular Rayleigh integral approximation, and also to the Rayleigh integral. Both methods are approximations to the boundary integral equation, and can solve
Approximate Dynamic Programming for Dynamic Capacity Allocation with Multiple Priority Levels
Topaloglu, Huseyin
Approximate Dynamic Programming for Dynamic Capacity Allocation with Multiple Priority Levels In this paper, we consider a quite general dynamic capacity allocation problem. There is a fixed amount of daily to construct separable approximations to the value functions. We use the value function approximations for two
A mixed formulation for the direct approximation -weighted controls for the linear heat
Boyer, Edmond
A mixed formulation for the direct approximation of L2 -weighted controls for the linear heat of null controls for the linear heat equa- tion. The goal is to compute approximations of controls-Cara & MÂ¨unch, Strong convergence approximations of null controls for the 1D heat equation, 2013], a so
Comparison of Approximation Methods for Computing Tolerance Factors for a Multivariate
Krishnamoorthy, Kalimuthu
Comparison of Approximation Methods for Computing Tolerance Factors for a Multivariate Normal approximation methods for computing the tolerance factors of a multivariate normal population. These approximate on the multivariate setup is rather limited, how- ever. The first attempt at constructing tolerance regions
PreDVS: Preemptive Dynamic Voltage Scaling for Real-time Systems using Approximation Scheme
Mishra, Prabhat
, dynamic voltage scal- ing, approximation algorithm 1. INTRODUCTION Energy conservation has been the main to save energy is that linear reduction in the supply voltage leads to approximately linear slow downPreDVS: Preemptive Dynamic Voltage Scaling for Real-time Systems using Approximation Scheme Weixun
Botti, Silvana
Motivation Green's functions The GW Approximation The Bethe-Salpeter Equation Introduction to Green=whiteMotivation Green's functions The GW Approximation The Bethe-Salpeter Equation Outline 1 Motivation 2 Green's functions 3 The GW Approximation 4 The Bethe-Salpeter Equation #12;bg=whiteMotivation Green's functions
An analytic approximation to the Diffusion Coefficient for the periodic Lorentz Gas
C. Angstmann; G. P. Morriss
2012-02-14T23:59:59.000Z
An approximate stochastic model for the topological dynamics of the periodic triangular Lorentz gas is constructed. The model, together with an extremum principle, is used to find a closed form approximation to the diffusion coefficient as a function of the lattice spacing. This approximation is superior to the popular Machta and Zwanzig result and agrees well with a range of numerical estimates.
Comparison of moment-closure approximations for stochastic chemical kinetics
David Schnoerr; Guido Sanguinetti; Ramon Grima
2015-08-07T23:59:59.000Z
In recent years moment-closure approximations (MA) of the chemical master equation have become a popular method for the study of stochastic effects in chemical reaction systems. Several different MA methods have been proposed and applied in the literature, but it remains unclear how they perform with respect to each other. In this paper we study the normal, Poisson, log-normal and central-moment-neglect MAs by applying them to understand the stochastic properties of chemical systems whose deterministic rate equations show the properties of bistability, ultrasensitivity and oscillatory behaviour. Our results suggest that the normal MA is favourable over the other studied MAs. In particular we found that (i) the size of the region of parameter space where a closure gives physically meaningful results, e.g. positive mean and variance, is considerably larger for the normal closure than for the other three closures; (ii) the accuracy of the predictions of the four closures (relative to simulations using the stochastic simulation algorithm) is comparable in those regions of parameter space where all closures give physically meaningful results; (iii) the Poisson and log-normal MAs are not uniquely defined for systems involving conservation laws in molecule numbers. We also describe the new software package MOCA which enables the automated numerical analysis of various MA methods in a graphical user interface and which was used to perform the comparative analysis presented in this paper. MOCA allows the user to develop novel closure methods and can treat polynomial, non-polynomial, as well as time-dependent propensity functions, thus being applicable to virtually any chemical reaction system.
Volnianska, O.; Zakrzewski, T. [Institute of Physics PAS, 02-668 Warsaw (Poland); Boguslawski, P. [Institute of Physics PAS, 02-668 Warsaw (Poland); Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz (Poland)
2014-09-21T23:59:59.000Z
Electronic structure of the Mn and Fe ions and of the gallium vacancy V{sub Ga} in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ? 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of V{sub Ga}, these effects lead to stabilization of spin polarization and the negative-U{sub eff} behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ? U(Mn) ? 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn)
Vazquez-Mayagoitia, Alvaro [ORNL; Sherrill, David [Georgia Institute of Technology; Apra, Edoardo [ORNL; Sumpter, Bobby G [ORNL
2010-01-01T23:59:59.000Z
A recently proposed double-hybrid functional called XYG3 and a semilocal GGA functional (B97-D) with a semiempirical correction for van der Waals interactions have been applied to study the potential energy curves along the dissociation coordinates of weakly bound pairs of molecules governed by London dispersion and induced dipole forces. Molecules treated in this work were the parallel sandwich, T-shaped, and parallel-displaced benzene dimer, (C6H6)2; hydrogen sulfide and benzene, H2S C6H6; methane and benzene, CH4 C6H6; the methane dimer, (CH4)2; and the pyridine dimer, (C5H5N)2. We compared the potential energy curves of these functionals with previously published benchmarks at the coupled cluster singles, doubles, and perturbative triplets [CCSD(T)] complete-basis-set limit. Both functionals, XYG3 and B97-D, exhibited very good performance, reproducing accurate energies for equilibrium distances and a smooth behavior along the dissociation coordinate. Overall, we found an agreement within a few tenths of one kcal mol-1 with the CCSD(T) results across the potential energy curves.
Scalettar, Richard T.
occupancy, we find a noticeable decrease in correlation on compression across the transition; however, even-liquid behavior with an effective mass of about 20me .6 Also the magnetic susceptibility and its temperature dependence change from a Curie-Weiss-like behavior in the phase to a Pauli paramagnetic behavior in the phase
Matteo Viel; Martin G. Haehnelt; Volker Springel
2006-04-20T23:59:59.000Z
We implement the hydro-PM (HPM) technique (Gnedin & Hui 1998) in the hydrodynamical simulation code GADGET-II and quantify the differences between this approximate method and full hydrodynamical simulations of the Lyman-alpha forest in a concordance LCDM model. At redshifts z=3 and z=4, the differences between the gas and dark matter (DM) distributions, as measured by the one-point distribution of density fluctuations, the density power spectrum and the flux power spectrum, systematically decrease with increasing resolution of the HPM simulqation. However, reducing these differences to less than a few percent requires a significantly larger number of grid-cells than particles, with a correspondingly larger demand for memory. Significant differences in the flux decrement distribution remain even for very high resolution hydro-PM simulations, particularly at low redshift. At z=2, the differences between the flux power spectra obtained from HPM simulations and full hydrodynamical simulations are generally large and of the order of 20-30 %, and do not decrease with increasing resolution of the HPM simulation. This is due to the presence of large amounts of shock-heated gas, a situation which is not adequately modelled by the HPM approximation. We confirm the results of Gnedin & Hui (1998) that the statistical properties of the flux distribution are discrepant by > 5-20 % when compared to full hydrodynamical simulations. The discrepancies in the flux power spectrum are strongly scale- and redshift-dependent and extend to large scales. Considerable caution is needed in attempts to use calibrated HPM simulations for quantitative predictions of the flux power spectrum and other statistical properties of the Lyman-alpha forest.
Growth mechanism of atomic layer deposition of zinc oxide: A density functional theory approach
Afshar, Amir; Cadien, Kenneth C., E-mail: kcadien@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)
2013-12-16T23:59:59.000Z
Atomic layer deposition of zinc oxide (ZnO) using diethylzinc (DEZ) and water is studied using density functional theory. The reaction pathways between the precursors and ZnO surface sites are discussed. Both reactions proceed by the formation of intermediate complexes on the surface. The Gibbs free energy of the formation of these complexes is positive at temperatures above ?120?°C and ?200?°C for DEZ and water half-reactions, respectively. Spectroscopic ellipsometry results show that the growth per cycle changes at approximately the same temperatures.
Ferromagnetism in GaN: Gd: A density functional theory study
Stevenson, Cynthia; Stevenson, Cynthia
2008-02-04T23:59:59.000Z
First principle calculations of the electronic structure and magnetic interaction of GaN:Gd have been performed within the Generalized Gradient Approximation (GGA) of the density functional theory (DFT) with the on-site Coulomb energy U taken into account (also referred to as GGA+U). The ferromagnetic p-d coupling is found to be over two orders of magnitude larger than the s-d exchange coupling. The experimental colossal magnetic moments and room temperature ferromagnetism in GaN:Gd reported recently are explained by the interaction of Gd 4f spins via p-d coupling involving holes introduced by intrinsic defects such as Ga vacancies.
Lower crustal density estimation using the density-slowness relationship: a preliminary study
Jones, Gary Wayne
1996-01-01T23:59:59.000Z
, and seismic velocity models were used to estimate the densities of th lower crustal rocks frcm the Wind River Mountains, the Ivrea Zone in Italy, and the average 1~ continental crustal model developed b/ ~istensen and Mconey [1995] . The. densities... by Carlson and Raskin [1984) yields a precision of about 1 percent. 'Ihe objective of this study is to evaluate this approach to estimate the density of the more complex continental crust, which is more variable in composition and affected hy a wider range...
Branch cuts of Stokes wave on deep water. Part I: Numerical solution and Pad\\'e approximation
Dyachenko, S A; Korotkevich, A O
2015-01-01T23:59:59.000Z
Complex analytical structure of Stokes wave for two-dimensional potential flow of the ideal incompressible fluid with free surface and infinite depth is analyzed. Stokes wave is the fully nonlinear periodic gravity wave propagating with the constant velocity. Simulations with the quadruple and variable precisions are performed to find Stokes wave with high accuracy and study the Stokes wave approaching its limiting form with $2\\pi/3$ radians angle on the crest. A conformal map is used which maps a free fluid surface of Stokes wave into the real line with fluid domain mapped into the lower complex half-plane. The Stokes wave is fully characterized by the complex singularities in the upper complex half-plane. These singularities are addressed by rational (Pad\\'e) interpolation of Stokes wave in the complex plane. Convergence of Pad\\'e approximation to the density of complex poles with the increase of the numerical precision and subsequent increase of the number of approximating poles reveals that the only singu...
Knyazev, D. V. [Joint Institute for High Temperatures RAS, Izhorskaya 13 Bldg. 2, Moscow 125412 (Russian Federation); Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); State Scientific Center of the Russian FederationInstitute for Theoretical and Experimental Physics of National Research Centre Kurchatov Institute, Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Levashov, P. R. [Joint Institute for High Temperatures RAS, Izhorskaya 13 Bldg. 2, Moscow 125412 (Russian Federation); Tomsk State University, Lenin Prospekt 36, Tomsk 634050 (Russian Federation)
2014-07-15T23:59:59.000Z
This work is devoted to the investigation of transport and optical properties of liquid aluminum in the two-temperature case. At first optical properties, static electrical, and thermal conductivities were obtained in the ab initio calculation which is based on the quantum molecular dynamics, density functional theory, and the Kubo-Greenwood formula. Then the semiempirical approximation was constructed based on the results of our simulation. This approximation yields the dependences ?{sub 1{sub D{sub C}}}?1/T{sub i}{sup 0.25} and K?T{sub e}/T{sub i}{sup 0.25} for the static electrical conductivity and thermal conductivity, respectively, for liquid aluminum at ??=?2.70?g/cm{sup 3}, 3?kK???T{sub i}???T{sub e}???20?kK. Our results are well described by the Drude model with the effective relaxation time ??T{sub i}{sup ?0.25}. We have considered a number of other models for the static electrical and thermal conductivities of aluminum, they are all reduced in the low-temperature limit to the Drude model with different expressions for the relaxation time ?. Our results are not consistent with the models in which ??T{sub i}{sup ?1} and support the models which use the expressions with the slower decrease of the relaxation time.
Density equalizing map projections: A new algorithm
Merrill, D.W.; Selvin, S.; Mohr, M.S.
1992-02-01T23:59:59.000Z
In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst`s task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm.
Density equalizing map projections: A new algorithm
Merrill, D.W.; Selvin, S.; Mohr, M.S.
1992-02-01T23:59:59.000Z
In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst's task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm.
Ultra-high density diffraction grating
Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.
2012-12-11T23:59:59.000Z
A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.
Current density fluctuations and ambipolarity of transport
Shen, W.; Dexter, R.N.; Prager, S.C.
1991-10-01T23:59:59.000Z
The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.
Current density fluctuations and ambipolarity of transport
Shen, W.; Dexter, R.N.; Prager, S.C.
1991-10-01T23:59:59.000Z
The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center_dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.
Ion Density Deviations in Semipermeable Ionic Microcapsules
Qiyun Tang; Alan R. Denton
2015-07-07T23:59:59.000Z
By implementing the nonlinear Poisson-Boltzmann theory in a cell model, we theoretically investigate the influence of polyelectrolye gel permeability on ion densities and pH deviations inside the cavities of ionic microcapsules. Our calculations show that variations in permeability of a charged capsule shell cause a redistribution of ion densities within the capsule, which ultimately affects the pH deviation and Donnan potential induced by the electric field of the shell. We find that semipermeable capsules can induce larger pH deviations inside their cavities that can permeable capsules. Furthermore, with increasing capsule charge, the influence of permeability on pH deviations progressively increases. Our theory, while providing a self-consistent method for modeling the influence of permeability on fundamental properties of ionic microgels, makes predictions of practical significance for the design of microcapsules loaded with fluorescent dyes, which can serve as biosensors for diagnostic purposes.
The 2dF Galaxy Redshift Survey: luminosity functions by density environment and galaxy type
Darren J. Croton; Glennys R. Farrar; Peder Norberg; Matthew Colless; John A. Peacock; I. K. Baldry; C. M. Baugh; J. Bland-Hawthorn; T. Bridges; R. Cannon; S. Cole; C. Collins; W. Couch; G. Dalton; R. De Propris; S. P. Driver; G. Efstathiou; R. S. Ellis; C. S. Frenk; K. Glazebrook; C. Jackson; O. Lahav; I. Lewis; S. Lumsden; S. Maddox; D. Madgwick; B. A. Peterson; W. Sutherland; K. Taylor
2005-02-08T23:59:59.000Z
We use the 2dF Galaxy Redshift Survey to measure the dependence of the bJ-band galaxy luminosity function on large-scale environment, defined by density contrast in spheres of radius 8h-1Mpc, and on spectral type, determined from principal component analysis. We find that the galaxy populations at both extremes of density differ significantly from that at the mean density. The population in voids is dominated by late types and shows, relative to the mean, a deficit of galaxies that becomes increasingly pronounced at magnitudes brighter than M_bJ-5log10h <-18.5. In contrast, cluster regions have a relative excess of very bright early-type galaxies with M_bJ-5log10h < -21. Differences in the mid to faint-end population between environments are significant: at M_bJ-5log10h=-18 early and late-type cluster galaxies show comparable abundances, whereas in voids the late types dominate by almost an order of magnitude. We find that the luminosity functions measured in all density environments, from voids to clusters, can be approximated by Schechter functions with parameters that vary smoothly with local density, but in a fashion which differs strikingly for early and late-type galaxies. These observed variations, combined with our finding that the faint-end slope of the overall luminosity function depends at most weakly on density environment, may prove to be a significant challenge for models of galaxy formation.
Arianna Carbone; Arnau Rios; Artur Polls
2014-11-19T23:59:59.000Z
The properties of symmetric nuclear and pure neutron matter are investigated within an extended self-consistent Green's function method that includes the effects of three-body forces. We use the ladder approximation for the study of infinite nuclear matter and incorporate the three-body interaction by means of a density-dependent two-body force. This force is obtained via a correlated average over the third particle, with an in-medium propagator consistent with the many-body calculation we perform. We analyze different prescriptions in the construction of the average and conclude that correlations provide small modifications at the level of the density-dependent force. Microscopic as well as bulk properties are studied, focusing on the changes introduced by the density dependent two-body force. The total energy of the system is obtained by means of a modified Galitskii-Migdal-Koltun sum rule. Our results validate previously used uncorrelated averages and extend the availability of chirally motivated forces to a larger density regime.
Fiber felts as low density structural materials
Milewski, J.V.; Newfield, S.E.
1981-01-01T23:59:59.000Z
Short fiber felts structures can be made which provide improvements in properties over foams. In applications where resistance to compression set or stress relaxation are important, bonded fiber felts excel due to the flexing of individual fibers within their elastic limit. Felts of stainless steel and polyester fibers were prepared by deposition from liquid slurries. Compressive properties were determined as a function of felt parent material, extent of bonding, felt density, and length-to-diameter (L/D) ratio of starting fibers.
Nuclear fission in covariant density functional theory
A. V. Afanasjev; H. Abusara; P. Ring
2013-09-12T23:59:59.000Z
The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.
Update of axion CDM energy density
Huh, Ji-Haeng [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of)
2008-11-23T23:59:59.000Z
We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale {lambda}{sub QCD}, the current quark masses m{sub q}'s and the Peccei-Quinn scale F{sub a}, including firstly introduced 1.85 factor which is from the initial overshoot.
Energy trapping from Hagedorn densities of states
Connor Behan; Klaus Larjo; Nima Lashkari; Brian Swingle; Mark Van Raamsdonk
2013-04-26T23:59:59.000Z
In this note, we construct simple stochastic toy models for holographic gauge theories in which distributions of energy on a collection of sites evolve by a master equation with some specified transition rates. We build in only energy conservation, locality, and the standard thermodynamic requirement that all states with a given energy are equally likely in equilibrium. In these models, we investigate the qualitative behavior of the dynamics of the energy distributions for different choices of the density of states for the individual sites. For typical field theory densities of states (\\log(\\rho(E)) ~ E^{\\alphaenergy spread out relatively quickly. For large N gauge theories with gravitational duals, the density of states for a finite volume of field theory degrees of freedom typically includes a Hagedorn regime (\\log(\\rho(E)) ~ E). We find that this gives rise to a trapping of energy in subsets of degrees of freedom for parametrically long time scales before the energy leaks away. We speculate that this Hagedorn trapping may be part of a holographic explanation for long-lived gravitational bound states (black holes) in gravitational theories.
Optimally focused cold atom systems obtained using density-density correlations
Putra, Andika; Campbell, Daniel L.; Price, Ryan M.; Spielman, I. B. [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States)] [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States); De, Subhadeep [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States) [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States); CSIR-National Physical Laboratory, New Delhi 110012 (India)
2014-01-15T23:59:59.000Z
Resonant absorption imaging is a common technique for detecting the two-dimensional column density of ultracold atom systems. In many cases, the system's thickness along the imaging direction greatly exceeds the imaging system's depth of field, making the identification of the optimally focused configuration difficult. Here we describe a systematic technique for bringing Bose-Einstein condensates (BEC) and other cold-atom systems into an optimal focus even when the ratio of the thickness to the depth of field is large: a factor of 8 in this demonstration with a BEC. This technique relies on defocus-induced artifacts in the Fourier-transformed density-density correlation function (the power spectral density, PSD). The spatial frequency at which these artifacts first appear in the PSD is maximized on focus; the focusing process therefore both identifies and maximizes the range of spatial frequencies over which the PSD is uncontaminated by finite-thickness effects.
Rom Pinchasi; Gershon Wolansky
2014-10-13T23:59:59.000Z
In this paper we generalize the classical theorem of Thue about the optimal circular disc packing in the plane. We are given a family of circular discs, not necessarily of equal radii, with the property that the inflation of every disc by a factor of $2$ around its center does not contain any center of another disc in the family (notice that this implies that the family of discs is a packing). We show that in this case the density of the given packing is at most $\\frac{\\pi}{2\\sqrt{3}}$, which is the density of the optimal unit disc packing. This result is used to obtain a discrete approximation to the Entropy functional in two dimensional domain.
Roberto Peverati; Donald G. Truhlar
2013-09-06T23:59:59.000Z
Kohn-Sham density functional theory is in principle an exact formulation of quantum mechanical electronic structure theory, but in practice we have to rely on approximate exchange-correlation (xc) functionals. The objective of our work has been to design an xc functional with broad accuracy across as wide an expanse of chemistry and physics as possible, leading-as a long-range goal-to a functional with good accuracy for all problems, i.e., a universal functional. To guide our path toward that goal and to measure our progress, we have developed-building on earlier work in our group-a set of databases of reference data for a variety of energetic and structural properties in chemistry and physics. These databases include energies of molecular processes such as atomization, complexation, proton addition, and ionization; they also include molecular geometries and solid-state lattice constants, chemical reaction barrier heights, and cohesive energies and band gaps of solids. For the present paper we gather many of these databases into four comprehensive databases, two with 384 energetic data for chemistry and solid-state physics and another two with 68 structural data for chemistry and solid-state physics, and we test 2 wave function methods and 77 density functionals (12 Minnesota meta functionals and 65 others) in a consistent way across this same broad set of data. We especially highlight the Minnesota density functionals, but the results have broader implications in that one may see the successes and failures of many kinds of density functionals when they are all applied to the same data. Therefore the results provide a status report on the quest for a universal functional.
Generalized Holographic Quantum Criticality at Finite Density
B. Goutéraux; E. Kiritsis
2013-01-23T23:59:59.000Z
We show that the near-extremal solutions of Einstein-Maxwell-Dilaton theories, studied in ArXiv:1005.4690, provide IR quantum critical geometries, by embedding classes of them in higher-dimensional AdS and Lifshitz solutions. This explains the scaling of their thermodynamic functions and their IR transport coefficients, the nature of their spectra, the Gubser bound, and regulates their singularities. We propose that these are the most general quantum critical IR asymptotics at finite density of EMD theories.
Method of high-density foil fabrication
Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.
2003-12-16T23:59:59.000Z
A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.
Wigner density of a rigid rotator
Malta, C.P. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo (Brazil)] [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo (Brazil); Marshall, T.S. [Department of Mathematics, University of Manchester, Manchester M139PL (United Kingdom)] [Department of Mathematics, University of Manchester, Manchester M139PL (United Kingdom); Santos, E. [Departamento de Fisica Moderna, Universidad de Cantabria, 39005, Santander (Spain)] [Departamento de Fisica Moderna, Universidad de Cantabria, 39005, Santander (Spain)
1997-03-01T23:59:59.000Z
We show that the Wigner density of the rigid rotator, in an appropriate, i.e., four-dimensional, phase space, is positive. This result holds in the ground state (S state), and also in the thermal mixture state at all finite temperatures. We discuss the implications of our result for the description of angular momentum in quantum mechanics; in particular, we reexamine, in the light of this new evidence, the suggestion made by Einstein and Stern [Ann. Phys. {bold 40}, 551 (1913)] that there is a nontrivial distribution of angular momentum in the S state. {copyright} {ital 1997} {ital The American Physical Society}
Symmetry energy in nuclear density functional theory
W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar
2013-07-22T23:59:59.000Z
The nuclear symmetry energy represents a response to the neutron-proton asymmetry. In this survey we discuss various aspects of symmetry energy in the framework of nuclear density functional theory, considering both non-relativistic and relativistic self-consistent mean-field realizations side-by-side. Key observables pertaining to bulk nucleonic matter and finite nuclei are reviewed. Constraints on the symmetry energy and correlations between observables and symmetry-energy parameters, using statistical covariance analysis, are investigated. Perspectives for future work are outlined in the context of ongoing experimental efforts.
Nuclear Energy Density Optimization: UNEDF2
M. Kortelainen; J. McDonnell; W. Nazarewicz; E. Olsen; P. -G. Reinhard; J. Sarich; N. Schunck; S. M. Wild; D. Davesne; J. Erler; A. Pastore
2014-10-30T23:59:59.000Z
The parameters of the UNEDF2 nuclear energy density functional (EDF) model were obtained in an optimization to experimental data consisting of nuclear binding energies, proton radii, odd-even mass staggering data, fission-isomer excitation energies, and single particle energies. In addition to parameter optimization, sensitivity analysis was done to obtain parameter uncertainties and correlations. The resulting UNEDF2 is an all-around EDF. However, the sensitivity analysis also demonstrated that the limits of current Skyrme-like EDFs have been reached and that novel approaches are called for.
Particle transport inferences from density sawteeth
Chen, J.; Li, Q.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Liao, K.; Gentle, K. W., E-mail: k.gentle@mail.utexas.edu [Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States)
2014-05-15T23:59:59.000Z
Sawtooth oscillations in tokamaks are defined by their effect on electron temperature: a rapid flattening of the core profile followed by an outward heat pulse and a slow core recovery caused by central heating. Recent high-resolution, multi-chord interferometer measurements on JTEXT extend these studies to particle transport. Sawteeth only partially flatten the core density profile, but enhanced particle diffusion on the time scale of the thermal crash occurs over much of the profile, relevant for impurities. Recovery between crashes implies an inward pinch velocity extending to the center.
Landau's necessary density conditions for LCA groups
Gröchenig, K; Seip, K
2008-01-01T23:59:59.000Z
H. Landau's necessary density conditions for sampling and interpolation may be viewed as a general principle resting on a basic fact of Fourier analysis: The complex exponentials $e^{i kx}$ ($k$ in $\\mathbb{Z}$) constitute an orthogonal basis for $L^2([-\\pi,\\pi])$. The present paper extends Landau's conditions to the setting of locally compact abelian (LCA) groups, relying in an analogous way on the basics of Fourier analysis. The technicalities--in either case of an operator theoretic nature--are however quite different. We will base our proofs on the comparison principle of J. Ramanathan and T. Steger.
Validity of Born Approximation for Nuclear Scattering in Path Integral Representation
M. R. Pahlavani; R. Morad
2009-07-01T23:59:59.000Z
The first and second Born approximation are studied with the path integral representation for $ {\\cal T} $ matrix. The $ {\\cal T}$ matrix is calculated for Woods-Saxon potential scattering. To make corresponding integrals solvable analytically, an approximate function for the Woods-Saxon potential is used. Finally it shown that the Born series is converge at high energies and orders higher than two in Born approximation series can be neglected.
The density of states approach for the simulation of finite density quantum field theories
K. Langfeld; B. Lucini; A. Rago; R. Pellegrini; L. Bongiovanni
2015-03-02T23:59:59.000Z
Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to free of a sign problem.
The density of states approach for the simulation of finite density quantum field theories
Langfeld, K; Rago, A; Pellegrini, R; Bongiovanni, L
2015-01-01T23:59:59.000Z
Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to fr...
Approximate life-cycle assessment of product concepts using learning systems
Sousa, Inęs (Maria Inęs Silva Sousa), 1972-
2002-01-01T23:59:59.000Z
This thesis develops an approximate, analytically based environmental assessment method that provides fast evaluations of product concepts. Traditional life-cycle assessment (LCA) studies and their streamlined analytical ...
A complete analytic inversion of supernova lines in the Sobolev approximation
Kasen, Daniel; Branch, David; Baron, E.; Jeffery, David
2001-01-01T23:59:59.000Z
D . & Branch, D . 1990, in Supernovae, ed. J . C . Wheeler &radia tive transfer supernovae Lawrence Berkeley Nationalgradients, such as supernovae. The Sobolev approximation has
A comparison of networked approximators in parallel mode identification of a bioreactor
Efe, Mehmet Önder
A comparison of networked approximators in parallel mode identification of a bioreactor Mehmet 2010 Keywords: Bioreactor Identification Multilayer perceptron ANFIS Support vector machine Chemical
Conformal Higgs model: predicted dark energy density
R. K. Nesbet
2014-11-03T23:59:59.000Z
Postulated universal Weyl conformal scaling symmetry provides an alternative to the $\\Lambda$CDM paradigm for cosmology. Recent applications to galactic rotation velocities, Hubble expansion, and a model of dark galactic halos explain qualitative phenomena and fit observed data without invoking dark matter. Significant revision of theory relevant to galactic collisions and clusters is implied, but not yet tested. Dark energy is found to be a consequence of conformal symmetry for the Higgs scalar field of electroweak physics. The present paper tests this implication. The conformal Higgs model acquires a gravitational effect described by a modified Friedmann cosmic evolution equation, shown to fit cosmological data going back to the cosmic microwave background epoch. The tachyonic mass parameter of the Higgs model becomes dark energy in the Friedmann equation. A dynamical model of this parameter, analogous to the Higgs mechanism for gauge boson mass, is derived and tested here. An approximate calculation yields a result consistent with the empirical magnitude inferred from Hubble expansion.
Thermodynamics and Structural Properties of the High Density Gaussian Core Model
Atsushi Ikeda; Kunimasa Miyazaki
2011-07-20T23:59:59.000Z
We numerically study thermodynamic and structural properties of the one-component Gaussian core model (GCM) at very high densities. The solid-fluid phase boundary is carefully determined. We find that the density dependence of both the freezing and melting temperatures obey the asymptotic relation, $\\log T_f$, $\\log T_m \\propto -\\rho^{2/3}$, where $\\rho$ is the number density, which is consistent with Stillinger's conjecture. Thermodynamic quantities such as the energy and pressure and the structural functions such as the static structure factor are also investigated in the fluid phase for a wide range of temperature above the phase boundary. We compare the numerical results with the prediction of the liquid theory with the random phase approximation (RPA). At high temperatures, the results are in almost perfect agreement with RPA for a wide range of density, as it has been already shown in the previous studies. In the low temperature regime close to the phase boundary line, although RPA fails to describe the structure factors and the radial distribution functions at the length scales of the interparticle distance, it successfully predicts their behaviors at shorter length scales. RPA also predicts thermodynamic quantities such as the energy, pressure, and the temperature at which the thermal expansion coefficient becomes negative, almost perfectly. Striking ability of RPA to predict thermodynamic quantities even at high densities and low temperatures is understood in terms of the decoupling of the length scales which dictate thermodynamic quantities from the interparticle distance which dominates the peak structures of the static structure factor due to the softness of the Gaussian core potential.
Measuring the entanglement of analogue Hawking radiation by the density-density correlation function
Steinhauer, Jeff
2015-01-01T23:59:59.000Z
We theoretically study the entanglement of Hawking radiation emitted by an analogue black hole. We find that this entanglement can be measured by the experimentally accessible density-density correlation function, which only requires standard imaging techniques. It is seen that the high energy tail of the distribution of Hawking radiation should be entangled, whereas the low energy part is not. This confirms a previous numerical study. The full Peres-Horodecki criterion is considered, but a significant simplification is found in the stationary, homogeneous case. Our method applies to systems which are sufficiently cold that the thermal phonons can be neglected.
Christian Iliadis; Richard Longland; Art Champagne; Alain Coc; Ryan Fitzgerald
2010-04-23T23:59:59.000Z
Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14 to 40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this series (Paper I). We present a low rate, median rate and high rate which correspond to the 0.16, 0.50 and 0.84 quantiles, respectively, of the cumulative reaction rate distribution. The meaning of these quantities is in general different from the commonly reported, but statistically meaningless expressions, "lower limit", "nominal value" and "upper limit" of the total reaction rate. In addition, we approximate the Monte Carlo probability density function of the total reaction rate by a lognormal distribution and tabulate the lognormal parameters {\\mu} and {\\sigma} at each temperature. We also provide a quantitative measure (Anderson-Darling test statistic) for the reliability of the lognormal approximation. The user can implement the approximate lognormal reaction rate probability density functions directly in a stellar model code for studies of stellar energy generation and nucleosynthesis. For each reaction, the Monte Carlo reaction rate probability density functions, together with their lognormal approximations, are displayed graphically for selected temperatures in order to provide a visual impression. Our new reaction rates are appropriate for bare nuclei in the laboratory. The nuclear physics input used to derive our reaction rates is presented in the subsequent paper of this series (Paper III). In the fourth paper of this series (Paper IV) we compare our new reaction rates to previous results.
Terzic, B.; Bassi, G.
2011-07-08T23:59:59.000Z
In this paper we discuss representations of charge particle densities in particle-in-cell simulations, analyze the sources and profiles of the intrinsic numerical noise, and present efficient methods for their removal. We devise two alternative estimation methods for charged particle distribution which represent significant improvement over the Monte Carlo cosine expansion used in the 2D code of Bassi et al. [G. Bassi, J.A. Ellison, K. Heinemann and R. Warnock Phys. Rev. ST Accel. Beams 12 080704 (2009)G. Bassi and B. Terzic, in Proceedings of the 23rd Particle Accelerator Conference, Vancouver, Canada, 2009 (IEEE, Piscataway, NJ, 2009), TH5PFP043], designed to simulate coherent synchrotron radiation (CSR) in charged particle beams. The improvement is achieved by employing an alternative beam density estimation to the Monte Carlo cosine expansion. The representation is first binned onto a finite grid, after which two grid-based methods are employed to approximate particle distributions: (i) truncated fast cosine transform; and (ii) thresholded wavelet transform (TWT). We demonstrate that these alternative methods represent a staggering upgrade over the original Monte Carlo cosine expansion in terms of efficiency, while the TWT approximation also provides an appreciable improvement in accuracy. The improvement in accuracy comes from a judicious removal of the numerical noise enabled by the wavelet formulation. The TWT method is then integrated into the CSR code [G. Bassi, J.A. Ellison, K. Heinemann and R. Warnock Phys. Rev. ST Accel. Beams 12 080704 (2009)], and benchmarked against the original version. We show that the new density estimation method provides a superior performance in terms of efficiency and spatial resolution, thus enabling high-fidelity simulations of CSR effects, including microbunching instability.
Cosmological and astrophysical aspects of finite-density QCD
Dominik J. Schwarz
1998-07-23T23:59:59.000Z
The different phases of QCD at finite temperature and density lead to interesting effects in cosmology and astrophysics. In this work I review some aspects of the cosmological QCD transition and of astrophysics at high baryon density.
Noisy Independent Factor Analysis Model for Density Estimation and Classification
Amato, U.
2009-06-09T23:59:59.000Z
We consider the problem of multivariate density estimation when the unknown density is assumed to follow a particular form of dimensionality reduction, a noisy independent factor analysis (IFA) model. In this model the ...
Observable to explore high density behaviour of symmetry energy
Aman D. Sood
2011-09-28T23:59:59.000Z
We aim to see the sensitivity of collective transverse in-plane flow to symmetry energy at low as well as high densities and also to see the effect of different density dependencies of symmetry energy on the same.
Innovative fuel designs for high power density pressurized water reactor
Feng, Dandong, Ph. D. Massachusetts Institute of Technology
2006-01-01T23:59:59.000Z
One of the ways to lower the cost of nuclear energy is to increase the power density of the reactor core. Features of fuel design that enhance the potential for high power density are derived based on characteristics of ...
Constrained Density-Functional Theory--Configuration Interaction
Kaduk, Benjamin James
2012-01-01T23:59:59.000Z
In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density ...
Nonparametric Comparison of Densities Based on Statistical Bootstrap
Nonparametric Comparison of Densities Based on Statistical Bootstrap De Brabanter, K.1 , Sahhaf, S. Keywords: Statistical Bootstrap, Variance Stabilization, Least Squares Support Vector Machines, Hypothesis on statistical bootstrap with variance stabilization and a nonparametric kernel density estimator, assisting
Gray squirrel density, habitat suitability, and behavior in urban parks
Gompper, Matthew E.
densities. We used linear regression (SAS Institute, SAS/STAT user's guide. SAS Institute, Cary, NC, 2005
Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring
Gonsalves, Anthony
2012-01-01T23:59:59.000Z
38 fs. Laser and electron beam diagnostics Laser radiationdiagnostic provided charge density images of the electron beam
Competition between superconductivity and spin density wave
Tian De Cao
2012-08-25T23:59:59.000Z
The Hubbard model has been investigated widely by many authors, while this work may be new in two aspects. One, we focus on the possible effects of the positions of the gaps associated with the pairing and the spin density wave. Two, we suggest that the models with different parameters are appropriate for different materials (or a material in different doped regions). This will lead to some new insights into the high temperature superconductors. It is shown that the SDW can appear at some temperature region when the on-site Coulomb interaction is larger, while the SC requires a decreased U at a lower temperature. This can qualitatively explain the relationship between superconducting and pseudogap states of Cu-based superconductors in underdoped and optimally doped regions. The superinsulator is also discussed.
Band terminations in density functional theory
A. V. Afanasjev
2009-02-01T23:59:59.000Z
The analysis of the terminating bands has been performed in the relativistic mean field framework. It was shown that nuclear magnetism provides an additional binding to the energies of the specific configuration and this additional binding increases with spin and has its {\\it maximum} exactly at the terminating state. This suggests that the terminating states can be an interesting probe of the time-odd mean fields {\\it provided that other effects can be reliably isolated.} Unfortunately, a reliable isolation of these effects is not that simple: many terms of the density functional theories contribute into the energies of the terminating states and the deficiencies in the description of those terms affect the result. The recent suggestion \\cite{ZSW.05} that the relative energies of the terminating states in the $N \
High energy density redox flow device
Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa
2014-05-13T23:59:59.000Z
Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.
Constant centrifugal potential approximation for atom-diatom chemical reaction dynamics
Takada, Shoji
Constant centrifugal potential approximation for atom-diatom chemical reaction dynamics Kengo,Myodaiji, Okazaki 444. Japan (Received 28 September 1993; accepted 8 December 1993) The constant centrifugal of such practically useful approxima- tions the constant centrifugal potential approximation (CCPA) (or the energy
Beam Propagation Method Using a [(p -1)/p] Pade Approximant of the Propagator
Lu, Ya Yan
propagation method (BPM) is developed based on a direct approximation to the propagator using the [(p - 1)/p of the BPM. 1 Introduction The beam propagation method (BPM)14 is widely used in numerical simulation, the governing equation is a scalar Helmholtz equation. The BPM relies on approximating the Helmholtz equation
Zelikovsky, Alexander
correspond to a group of up to eight nodes in the Group #3; This work was supported by a Packard Foundation a group of up to eight virtual positions (c). The only existing approximation algorithms for the GroupA New Approximation Scheme for the Group Steiner Problem #3; C. S. Helvig Gabriel Robins Alexander
Logic-Based Outer-Approximation Algorithm for Solving Discrete-Continuous Dynamic
Grossmann, Ignacio E.
In this work we present an extension of the Logic Outer-Approximation algorithm for deal- ing with disjunctive.e. the control actions) may involve logic decisions that can be modeled as disjunctions [16], [17] giving riseLogic-Based Outer-Approximation Algorithm for Solving Discrete-Continuous Dynamic Optimization
Numerical approximation of bang-bang controls for the heat equation: an optimal design approach
Paris-Sud XI, Université de
Numerical approximation of bang-bang controls for the heat equation: an optimal design approach approximation of null controls of minimal L -norm for the linear heat equation with a bounded potential. Both the internal and boundary controllability problem of a linear heat equation with a bounded potential. Let us
Approximate logic circuits for low overhead, non-intrusive concurrent error detection
Mohanram, Kartik
Approximate logic circuits for low overhead, non-intrusive concurrent error detection Mihir R for the synthesis of approximate logic circuits. A low overhead, non-intrusive solution for concurrent error as proposed in this paper. A low overhead, non-intrusive solution for CED based on ap- proximate
Validation of the correctness of the Hald approximation in assessing tolerance
Gurevich, M. I., E-mail: gur.m@mail.ru; Kalugin, M. A.; Chukbar, B. K. [National Research Center Kurchatov Institute (Russian Federation)
2014-12-15T23:59:59.000Z
An analysis was performed of the correctness of employing the approximate formula which is widely used when assessing tolerances in the results of regression analysis. The correctness of approximation with the frequently used ratio between the probability and significance level equal to 95/95 is demonstrated. Conditions of application of the formula under stricter requirements, for example, 99/99, are formulated.
ERROR BOUNDS FOR MONOTONE APPROXIMATION SCHEMES FOR HAMILTON-JACOBI-BELLMAN
ERROR BOUNDS FOR MONOTONE APPROXIMATION SCHEMES FOR HAMILTON-JACOBI-BELLMAN EQUATIONS GUY BARLES AND ESPEN R. JAKOBSEN Abstract. We obtain error bounds for monotone approximation schemes of Hamilton-Jacobi, (almost) smooth supersolutions for the Hamilton-Jacobi-Bellman equation. 1. Introduction This paper
Approximate model checking of stochastic hybrid systems , J.-P. Katoen
Abate, Alessandro
-room heating system. 1 Introduction Stochastic hybrid systems are a broad and widely applicable classApproximate model checking of stochastic hybrid systems A. Abate , J.-P. Katoen , J. Lygeros , and M. Prandini§ Abstract A method for approximate model checking of stochastic hybrid systems
Ada Numerica (1998), pp. 51-150 Cambridge University Press, 1998 Nonlinear approximation
DeVore, Ronald
1998-01-01T23:59:59.000Z
References 146 1. Nonlinear approximation: an overview The fundamental problem of approximation theory functionals applied to the target function are known. This information is then used to construct by certain smoothness conditions which are significantly weaker than required in the linear theory. Emphasis
Low complexity channel models for approximating flat Rayleigh fading in network simulations
McDougall, Jeffrey Michael
2004-09-30T23:59:59.000Z
of the requirements f DOCTOR OF PHILOSOPHY August 2003 Major Subject: Electrical Engineering LOW COMPLEXITY CHANNEL MODELS FOR APPROXIMATING FLAT RAYLEIGH FADING IN NETWORK SIMULATIONS A Dissertation by JEFFREY MICHAEL...) ____________________________ ____________________________ Du Li Chanan Singh (Member) (Head of Department) August 2003 Major Subject: Electrical Engineering iii ABSTRACT Low Complexity Channel Models for Approximating Flat Rayleigh Fading...
Serpen, Gursel
Search for A Lyapunov Function through Empirical Approximation by Artificial Neural Nets approximator for empirical modeling of a Lyapunov function for a nonlinear dynamic system that projects stable of designing the so-called Lyapunov neural network, which empirically models a Lyapunov function, is described
ENERGY-PRESERVING AND STABLE APPROXIMATIONS FOR THE TWO-DIMENSIONAL SHALLOW WATER EQUATIONS
ENERGY-PRESERVING AND STABLE APPROXIMATIONS FOR THE TWO-DIMENSIONAL SHALLOW WATER EQUATIONS EITAN water equations 13 5.1. Energy stable schemes 13 5.2. Energy preserving schemes 17 6. Numerical TADMOR AND WEIGANG ZHONG Abstract. We present a systematic development of energy-stable approximations
Approximate Association Rule Mining Jyothsna R. Nayak and Diane J. Cook
Cook, Diane J.
1 Approximate Association Rule Mining Jyothsna R. Nayak and Diane J. Cook Department of Computer. In this paper, we describe an associate rule mining algorithm that searches for approximate association rules and Engineering Box 19015 University of Texas at Arlington Arlington, TX 76019 Office: (817) 272-3606 Fax: (817
LOW DIMENSIONAL POLYTOPE APPROXIMATION AND ITS APPLICATIONS TO NONNEGATIVE MATRIX FACTORIZATION
factorization is recast as the problem of approximating a polytope on the probability simplex by another polytope with fewer facets. Working on the probability simplex has the advantage that data are limited, polytope approximation, probability simplex, supporting hyper- plane, Hahn-Banach theorem 1. Introduction
Approximations for Bit Error Probabilities in SSMA Communication Systems Using Spreading
Keller, Gerhard
Approximations for Bit Error Probabilities in SSMA Communication Systems Using Spreading Sequences@mi.uni-erlangen.de Abstract-- In previous research, we considered SSMA (spread spectrum multiple access) communication systems of spread spectrum multiple access (SSMA) communication systems, the standard Gaussian approximation (SGA
Validating a model of colon colouration using an Evolution Strategy with adaptive approximations
Rowe, Jon
Validating a model of colon colouration using an Evolution Strategy with adaptive approximations light interaction with the tissue, is aimed at correlating the histology of the colon and its colours been applied to solve it. An adaptive approximate optimisation method has been developed and applied
Real-Time Pricing for Demand Response Based on Stochastic Approximation
Wong, Vincent
1 Real-Time Pricing for Demand Response Based on Stochastic Approximation Pedram Samadi, Student to reduce their energy expenses. Keywords: Demand response, real-time pricing, PAR minimiza- tion, stochastic approximation, simultaneous perturbation. I. INTRODUCTION Demand response (DR) is an important
Wavelet-Based Piecewise Approximation of Steady-State Waveforms for
Tse, Chi K. "Michael"
Wavelet-Based Piecewise Approximation of Steady-State Waveforms for Power Electronics Circuits Kam Kong Polytechnic University, Hong Kong http://chaos.eie.polyu.edu.hk Abstract-- Wavelet transform has to maximize computational efficiency. In this paper, instead of applying one wavelet approximation
What is Concurrent Programming? Course Outline (Approximate) Evaluation & Deadlines Engineering 9869
Peters, Dennis
What is Concurrent Programming? Course Outline (Approximate) Evaluation & Deadlines Engineering 9869 Advanced Concurrent Programming Introduction Dennis Peters1 Fall 2007 1 Throughout this course I will be borrowing from Dr. Theo Norvell #12;What is Concurrent Programming? Course Outline (Approximate) Evaluation
Green's function approximation from cross-correlations of 20100 Hz noise during a tropical storm
Gerstoft, Peter
Green's function approximation from cross-correlations of 20100 Hz noise during a tropical storm Approximation of Green's functions through cross-correlation of acoustic signals in the ocean, a method referred-bottom-reflected interarray hydrophone travel times. The extracted Green's function depends on the propagating noise
Robert, Pincus
A fast, flexible, approximate technique for computing radiative transfer in inhomogeneous cloud.-J. Morcrette, A fast, flexible, approximate technique for computing radiative transfer in inhomogeneous cloud, which computes fluxes at each level. [3] The description of clouds in current LSMs is quite simple: Most
Improved approximation of the Brinkman equation using a lattice Boltzmann method
Bentz, Dale P.
conditions. The Brinkman equation3 is a generalization of Darcy's law that facilitates the matchingImproved approximation of the Brinkman equation using a lattice Boltzmann method by Nicos S. Martys;Improved approximation of the Brinkman equation using a lattice Boltzmann method Nicos S. Martys Building