Powered by Deep Web Technologies
Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Nature's Greatest Puzzles  

Science Conference Proceedings (OSTI)

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.

Quigg, Chris; /Fermilab

2005-02-01T23:59:59.000Z

2

The low-energy nuclear density of states and the saddle point approximation  

E-Print Network (OSTI)

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.

Sanjay K. Ghosh; Byron K. Jennings

2001-07-30T23:59:59.000Z

3

Secrets of the “Greatest Snow on Earth”  

Science Conference Proceedings (OSTI)

State license plates and tourism brochures boast that Utah ski areas receive the “greatest snow on Earth,” but is there really anything special about Utah's snow? Often it is argued in ski industry brochures that Utah's snow is the greatest ...

W. James Steenburgh; Trevor I. Alcott

2008-09-01T23:59:59.000Z

4

An Approximate Analytic Expression for the Flux Density of Scintillation Light at the Photocathode  

Science Conference Proceedings (OSTI)

The flux density of light exiting scintillator crystals is an important factor affecting the performance of radiation detectors, and is of particular importance for position sensitive instruments. Recent work by T. Woldemichael developed an analytic expression for the shape of the light spot at the bottom of a single crystal [1]. However, the results are of limited utility because there is generally a light pipe and photomultiplier entrance window between the bottom of the crystal and the photocathode. In this study, we expand Woldemichael s theory to include materials each with different indices of refraction and compare the adjusted light spot shape theory to GEANT 4 simulations [2]. Additionally, light reflection losses from index of refraction changes were also taken into account. We found that the simulations closely agree with the adjusted theory.

Braverman, Joshua B [ORNL; Harrison, Mark J [ORNL; Ziock, Klaus-Peter [ORNL

2012-01-01T23:59:59.000Z

5

Oak Ridge Removes Laboratory's Greatest Source of Groundwater  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge Removes Laboratory's Greatest Source of Groundwater Oak Ridge Removes Laboratory's Greatest Source of Groundwater Contamination Oak Ridge Removes Laboratory's Greatest Source of Groundwater Contamination May 1, 2012 - 12:00pm Addthis Workers remove the 4,000-gallon Tank W-1A, which was ORNL’s greatest source of groundwater contamination. Workers remove the 4,000-gallon Tank W-1A, which was ORNL's greatest source of groundwater contamination. Workers load boxes containing contaminated soil that surrounded Tank W-1A. Workers load boxes containing contaminated soil that surrounded Tank W-1A. The 6,500-pound Tank W-1A is shipped away from ORNL. The 6,500-pound Tank W-1A is shipped away from ORNL. Workers remove the 4,000-gallon Tank W-1A, which was ORNL's greatest source of groundwater contamination. Workers load boxes containing contaminated soil that surrounded Tank W-1A.

6

Oak Ridge Removes Laboratory's Greatest Source of Groundwater  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge Removes Laboratory's Greatest Source of Groundwater Oak Ridge Removes Laboratory's Greatest Source of Groundwater Contamination Oak Ridge Removes Laboratory's Greatest Source of Groundwater Contamination May 1, 2012 - 12:00pm Addthis Workers remove the 4,000-gallon Tank W-1A, which was ORNL’s greatest source of groundwater contamination. Workers remove the 4,000-gallon Tank W-1A, which was ORNL's greatest source of groundwater contamination. Workers load boxes containing contaminated soil that surrounded Tank W-1A. Workers load boxes containing contaminated soil that surrounded Tank W-1A. The 6,500-pound Tank W-1A is shipped away from ORNL. The 6,500-pound Tank W-1A is shipped away from ORNL. Workers remove the 4,000-gallon Tank W-1A, which was ORNL's greatest source of groundwater contamination. Workers load boxes containing contaminated soil that surrounded Tank W-1A.

7

What the World's Greatest Energy Managers Do Differently  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

the World's GREATEST the World's GREATEST Energy Managers Do Differently? Nasr Alkadi, PhD, CEM U.S. DOE Advanced Manufacturing Office (AMO) Tuesday Webcast for Industry Role of an Energy Manager July 10, 2012 Oak Ridge National Laboratory (ORNL) is DOE's Largest Science and Energy Laboratory ï‚· World's most powerful open scientific computer ï‚· Operating the world's most intense pulsed neutron source and a world-class research reactor ï‚· $1.4B budget ï‚· 4,550 employees ï‚· 4,000 research guests annually ï‚· $500M invested in modernization ï‚· Nation's most diverse energy portfolio ï‚· Nation's largest

8

DENSITY  

Science Conference Proceedings (OSTI)

... Table 2: Principal mineral phases found in the granite rock. Mineral phase. ... Table 4. Average density of 12 granite rocks by Archimedes and CT. ...

2007-01-08T23:59:59.000Z

9

The Subinertial Mixed Layer Approximation  

Science Conference Proceedings (OSTI)

The density of the mixed layer is approximately uniform in the vertical but has dynamically important horizontal gradients. These nonuniformities in density result in a vertically sheared horizontal pressure gradient. Subinertial motions balance ...

W. R. Young

1994-08-01T23:59:59.000Z

10

Question of the Week: What Change Has Made the Greatest Difference in the  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Change Has Made the Greatest Difference Change Has Made the Greatest Difference in the Efficiency of Your Home? Question of the Week: What Change Has Made the Greatest Difference in the Efficiency of Your Home? January 29, 2009 - 10:24am Addthis Many of our readers have commented on changes, both large and small, that they've made to improve the comfort and energy efficiency of their homes. The changes that will make the greatest difference can vary depending on your location, the age of your home, and the improvements needed, but tell us: What change have you made that has made the greatest difference in improving the comfort and efficiency of your home? E-mail your responses to the Energy Saver team at consumer.webmaster@nrel.gov. Addthis Related Articles Question of the Week: What Change Has Made the Greatest Difference in the Efficiency of Your Home?

11

Question of the Week: What Change Has Made the Greatest Difference in the  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Change Has Made the Greatest Difference Change Has Made the Greatest Difference in the Efficiency of Your Home? Question of the Week: What Change Has Made the Greatest Difference in the Efficiency of Your Home? January 29, 2009 - 10:24am Addthis Many of our readers have commented on changes, both large and small, that they've made to improve the comfort and energy efficiency of their homes. The changes that will make the greatest difference can vary depending on your location, the age of your home, and the improvements needed, but tell us: What change have you made that has made the greatest difference in improving the comfort and efficiency of your home? E-mail your responses to the Energy Saver team at consumer.webmaster@nrel.gov. Addthis Related Articles Question of the Week: What Change Has Made the Greatest Difference in the Efficiency of Your Home?

12

Approximate diagonalization  

E-Print Network (OSTI)

Abstract. We describe a new method of computing functions of highly non-normal matrices, by using the concept of approximate diagonalization. We formulate a conjecture about its efficiency, and provide both theoretical and numerical evidence in support of the conjecture. We apply the method to compute arbitrary real powers of highly non-normal matrices. Key words. Jordan matrices, ill-posedness, regularization, fractional powers, functional calculus, spectral theory.

E B Davies

2007-01-01T23:59:59.000Z

13

Approximations: Atomic Ref. Data Elect. Struct. Calculations  

Science Conference Proceedings (OSTI)

... where ? xc (?) is the exchange-correlation energy per particle for the uniform electron gas of density ?. This approximation ...

14

The concept of primes and the algorithm for counting the greatest common divisor in Ancient China  

E-Print Network (OSTI)

When people mention the number theoretical achievements in Ancient China, the famous Chinese Remainder Theorem always springs to mind. But, two more of them--the concept of primes and the algorithm for counting the greatest common divisor, are rarely spoken. Some scholars even think that Ancient China has not the concept of primes. The aim of this paper is to show that the concept of primes in Ancient China can be traced back to the time of Confuciusor (about 500 B.C.) or more ago. This implies that the concept of primes in Ancient China is much earlier than the concept of primes in Euclid's \\emph{Elements}(about 300 B.C.) of Ancient Greece. We also shows that the algorithm for counting the greatest common divisor in Ancient China is essentially the Euclidean algorithm or the binary gcd algorithm. Donald E. Knuth said that "the binary gcd algorithm was discovered by J. Stein in 1961". Nevertheless, Knuth was wrong. The ancient Chinese algorithm is clearly much earlier than J. Stein's algorithm.

Zhang, Shaohua

2009-01-01T23:59:59.000Z

15

Facility location: distributed approximation  

Science Conference Proceedings (OSTI)

In this paper, we initiate the study of the approximability of the facility location problem in a distributed setting. In particular, we explore a trade-off between the amount of communication and the resulting approximation ratio. We give a distributed ... Keywords: distributed approximation, facility location, linear programming, primal-dual algorithms

Thomas Moscibroda; Rogert Wattenhofer

2005-07-01T23:59:59.000Z

16

Approximation of Stochastic Process  

E-Print Network (OSTI)

May 8, 2012 ... The approximation of stochastic processes by trees is an important topic in ... process ? is replaced by a finitely valued stochastic scenario ...

17

Particle size for greatest penetration of HEPA filters - and their true efficiency  

SciTech Connect

The particle size that most greatly penetrates a filter is a function of filter media construction, aerosol density, and air velocity. In this paper the published results of several experiments are compared with a modern filtration theory that predicts single-fiber efficiency and the particle size of maximum penetration. For high-efficiency particulate air (HEPA) filters used under design conditions this size is calculated to be 0.21 ..mu..m diam. This is in good agreement with the experimental data. The penetration at 0.21 ..mu..m is calculated to be seven times greater than at the 0.3 ..mu..m used for testing HEPA filters. Several mechanisms by which filters may have a lower efficiency in use than when tested are discussed.

da Roza, R.A.

1982-12-01T23:59:59.000Z

18

delta-Approximable Functions  

Science Conference Proceedings (OSTI)

In this paper we study several notions of approximability of functions in the framework of the BSS model. Denoting with ¿¿M the function computed by a BSS machine M when its comparisons are against -¿ rather than 0, we study ...

Charles Meyssonnier; Paolo Boldi; Sebastiano Vigna

2000-09-01T23:59:59.000Z

19

Retrocommissioning's Greatest Hits  

E-Print Network (OSTI)

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 and maintenance of buildings. Although owners' priorities for RCX projects may vary, it typically focuses on energy-using equipment such as lighting, HVAC, refrigeration, and the related controls. This paper highlights key findings from several of PECI's retrocommissioning projects that have produced significant benefits for low costs. The RCX measures are described along with the estimated savings, simple paybacks, and related benefits.

Haasl, T.; Potter, A.; Irvine, L.

2001-01-01T23:59:59.000Z

20

The Density of Alternation Points in Rational Approximation ... - CECM  

E-Print Network (OSTI)

page of such transmission. JSTOR is a ... numerator degree row and the ..... on the real line, J. Math. Phys.

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Density and pair-density scaling for deriving the Euler equation in density-functional and pair-density-functional theory  

Science Conference Proceedings (OSTI)

A link between density and pair density functional theories is presented. Density and pair density scaling are used to derive the Euler equation in both theories. Density scaling provides a constructive way of obtaining approximations for the Pauli potential. The Pauli potential (energy) of the density functional theory is expressed as the difference of the scaled and original exchange-correlation potentials (energies).

Nagy, A. [Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen (Hungary)

2011-09-15T23:59:59.000Z

22

Potential Vorticity Conservation, Hydrostatic Adjustment, and the Anelastic Approximation  

Science Conference Proceedings (OSTI)

An examination of the anelastic equations of Lipps and Hemler shows that the approximation requires the temperature and potential temperature scale heights of the base state are large compared to the pressure and density scale heights. As a ...

Peter R. Bannon

1995-06-01T23:59:59.000Z

23

Scaled hydrogenic approximation wavefunctions. [Hartree-Fock approximation  

DOE Green Energy (OSTI)

Although widespread use of computer codes for the solution of Schrodinger equations makes available numerical Hartree-Fock model radial wave functions, there remains persistant interest in simple analytic expressions for atomic wave functions. One such frequency favored approach employs hydrogenic functions, suitably scaled, as approximate wave functions. The following note displays typical inaccuracies to be expected from such approximations. 13 references.

Shore, B.W.

1979-09-01T23:59:59.000Z

24

On the Beta Plane Approximation  

Science Conference Proceedings (OSTI)

The beta plane approximation as it is usually derived suffers from the difficulty that it is only valid if the quasi-geostrophic approximation is made. It is not valid for the underlying momentum and continuity equations. The problem in the ...

W. T. M. Verkley

1990-10-01T23:59:59.000Z

25

Density-dependent covariant energy density functionals  

Science Conference Proceedings (OSTI)

Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

Lalazissis, G. A. [Physics Department, Aristotle University of Thessaloniki, GR-54124 (Greece)

2012-10-20T23:59:59.000Z

26

The Quasi-Hydrostatic Approximation  

Science Conference Proceedings (OSTI)

Second-order expansion of the aspect ratio gives rise to simple equations with a quasi-hydrostatic approximation that perform far better than the classical hydrostatic system in the simulation of moist convection in a mesoscale model. It also ...

Isidoro Orlanski

1981-03-01T23:59:59.000Z

27

Heat pipe transient response approximation.  

SciTech Connect

A simple and concise routine that approximates the response of an alkali metal heat pipe to changes in evaporator heat transfer rate is described. This analytically based routine is compared with data from a cylindrical heat pipe with a crescent-annular wick that undergoes gradual (quasi-steady) transitions through the viscous and condenser boundary heat transfer limits. The sonic heat transfer limit can also be incorporated into this routine for heat pipes with more closely coupled condensers. The advantages and obvious limitations of this approach are discussed. For reference, a source code listing for the approximation appears at the end of this paper.

Reid, R. S. (Robert Stowers)

2001-01-01T23:59:59.000Z

28

Hydrogen Beyond the Classic Approximation  

E-Print Network (OSTI)

The classical nucleus approximation is the most frequently used approach for the resolution of problems in condensed matter physics.However, there are systems in nature where it is necessary to introduce the nuclear degrees of freedom to obtain a correct description of the properties.Examples of this, are the systems with containing hydrogen.In this work, we have studied the resolution of the quantum nuclear problem for the particular case of the water molecule.The Hartree approximation has been used, i.e. we have considered that the nuclei are distinguishable particles.In addition, we have proposed a model to solve the tunneling process, which involves the resolution of the nuclear problem for configurations of the system away from its equilibrium position

Scivetti, I

2003-01-01T23:59:59.000Z

29

The Greatest Story Never Told  

E-Print Network (OSTI)

mutual reductions in nuclear weapons and an East-Weston the testing of nuclear weapons today." Presto! Thein a world without nuclear weapons, in a world where Soviet

Gitlin, Todd

1987-01-01T23:59:59.000Z

30

Gluon Condensate in Pion Superfluid beyond Mean Field Approximation  

E-Print Network (OSTI)

We study gluon condensate in a pion superfluid, through calculating the equation of state of the system in the Nambu-Jona-Lasinio model. While in mean field approximation the growing pion condensate leads to an increasing gluon condensate, meson fluctuations reduce the gluon condensate and the broken scalar symmetry can be smoothly restored at finite isospin density.

Yin Jiang; Pengfei Zhuang

2010-12-10T23:59:59.000Z

31

Equivalence of Local Potential Approximations  

E-Print Network (OSTI)

In recent papers it has been noted that the local potential approximation of the Legendre and Wilson-Polchinski flow equations give, within numerical error, identical results for a range of exponents and Wilson-Fisher fixed points in three dimensions, providing a certain ``optimised'' cutoff is used for the Legendre flow equation. Here we point out that this is a consequence of an exact map between the two equations, which is nothing other than the exact reduction of the functional map that exists between the two exact renormalization groups. We note also that the optimised cutoff does not allow a derivative expansion beyond second order.

Tim R. Morris

2005-03-21T23:59:59.000Z

32

Weak lensing and the Dyer-Roeder approximation  

E-Print Network (OSTI)

The distance-redshift relation plays an important role in cosmology. In the standard approach to cosmology it is assumed that this relation is the same as in the homogeneous universe. As the real universe is not homogeneous there are several methods to calculate the correction. The weak lensing approximation and the Dyer-Roeder relation are one of them. This paper establishes a link between these two approximations. It is shown that if the universe is homogeneous with only small, vanishing after averaging, density fluctuations along the line of sight, then the distance correction is negligible. It is also shown that a vanishing 3D average of density fluctuations does not imply that the mean of density fluctuations along the line of sight is zero. In this case, even within the linear approximation, the distance correction is not negligible. The modified version of the Dyer-Roeder relation is presented and it is shown that this modified relation is consistent with the correction obtained within the weak lensing approximation. The correction to the distance for a source at z ~ 2 is of order of a few percent. Thus, with an increasing precision of cosmological observations an accurate estimation of the distance is essential. Otherwise errors due to miscalculation the distance can become a major source of systematics.

Krzysztof Bolejko

2010-11-17T23:59:59.000Z

33

Fully Polynomial Time Approximation Schemes for Stochastic ...  

E-Print Network (OSTI)

Jun 10, 2013 ... finite horizon dynamic program (DP, to be distinguished from dynamic ... state of the system is observed before an action is taken. .... methods from statistical physics. ..... is the greatest convex function that does not lie above ? over the ...... of the (linear) multi-period knapsack problem [Faaland, 1981], our.

34

Efficient algorithm for approximating one-dimensional ground states  

Science Conference Proceedings (OSTI)

The density-matrix renormalization-group method is very effective at finding ground states of one-dimensional (1D) quantum systems in practice, but it is a heuristic method, and there is no known proof for when it works. In this article we describe an efficient classical algorithm which provably finds a good approximation of the ground state of 1D systems under well-defined conditions. More precisely, our algorithm finds a matrix product state of bond dimension D whose energy approximates the minimal energy such states can achieve. The running time is exponential in D, and so the algorithm can be considered tractable even for D, which is logarithmic in the size of the chain. The result also implies trivially that the ground state of any local commuting Hamiltonian in 1D can be approximated efficiently; we improve this to an exact algorithm.

Aharonov, Dorit; Arad, Itai; Irani, Sandy [School of Computer Science and Engineering, Hebrew University, Jerusalem (Israel); School of Computer Science, Tel-Aviv University, Tel-Aviv (Israel); Computer Science Department, University of California, Irvine, California (United States)

2010-07-15T23:59:59.000Z

35

Saturated Pseudoadiabats—A Noniterative Approximation  

Science Conference Proceedings (OSTI)

Two noniterative approximations are presented for saturated pseudoadiabats (also known as moist adiabats). One approximation determines which moist adiabat passes through a point of known pressure and temperature, such as through the lifting ...

Atoossa Bakhshaii; Roland Stull

2013-01-01T23:59:59.000Z

36

Rational Approximation for a Quasilinear Parabolic Equation  

E-Print Network (OSTI)

Approximation theorems, analogous to known results for linear elliptic equations, are obtained for solutions of the heat equation. Via the Cole-Hopf transformation, this gives rise to approximation theorems for a nonlinear parabolic equation, Burgers' equation.

P. M. Gauthier; N. Tarkhanov

2007-09-22T23:59:59.000Z

37

Enabling ?-approximate querying in sensor networks  

Science Conference Proceedings (OSTI)

Data approximation is a popular means to support energy-efficient query processing in sensor networks. Conventional data approximation methods require users to specify fixed error bounds a prior to address the trade-off between result accuracy ...

Liu Yu; Jianzhong Li; Hong Gao; Xiaolin Fang

2009-08-01T23:59:59.000Z

38

Velocity Probability Density Functions for Oceanic Floats  

Science Conference Proceedings (OSTI)

Probability density functions (PDFs) of daily velocities from subsurface floats deployed in the North Atlantic and equatorial Atlantic Oceans are examined. In general, the PDFs are approximately Gaussian for small velocities, but with significant ...

Annalisa Bracco; J. H. LaCasce; Antonello Provenzale

2000-03-01T23:59:59.000Z

39

An approximation trichotomy for Boolean #CSP  

E-Print Network (OSTI)

We give a trichotomy theorem for the complexity of approximately counting the number of satisfying assignments of a Boolean CSP instance. Such problems are parameterised by a constraint language specifying the relations that may be used in constraints. If every relation in the constraint language is affine then the number of satisfying assignments can be exactly counted in polynomial time. Otherwise, if every relation in the constraint language is in the co-clone IM_2 from Post's lattice, then the problem of counting satisfying assignments is complete with respect to approximation-preserving reductions in the complexity class #RH\\Pi_1. This means that the problem of approximately counting satisfying assignments of such a CSP instance is equivalent in complexity to several other known counting problems, including the problem of approximately counting the number of independent sets in a bipartite graph. For every other fixed constraint language, the problem is complete for #P with respect to approximation-prese...

Dyer, Martin; Jerrum, Mark

2007-01-01T23:59:59.000Z

40

Improved Error Bounds for the Adiabatic Approximation  

E-Print Network (OSTI)

Since the discovery of adiabatic quantum computing, a need has arisen for rigorously proven bounds for the error in the adiabatic approximation. We present in this paper, a rigorous and elementary derivation of upper and lower bounds on the error incurred from using the adiabatic approximation for quantum systems. Our bounds are often asymptotically tight in the limit of slow evolution for fixed Hamiltonians, and are used to provide sufficient conditions for the application of the adiabatic approximation. We show that our sufficiency criteria exclude the Marzlin--Sanders counterexample from the class of Hamiltonians that obey the adiabatic approximation. Finally, we demonstrate the existence of classes of Hamiltonians that resemble the Marzlin--Sanders counterexample Hamiltonian, but also obey the adiabatic approximation.

Cheung, Donny; Wiebe, Nathan

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Boussinesq approximation of the Cahn-Hilliard-Navier-Stokes equations  

E-Print Network (OSTI)

We study the interactions between the thermodynamic transition and hydrodynamic flows which would characterise a thermo- and hydro-dynamic evolution of a binary mixture in a dissolution/nucleation process. The primary attention is given to the slow dissolution dynamics. The Cahn-Hilliard approach is used to model the behaviour of evolving and diffusing interfaces. An important peculiarity of the full Cahn-Hilliard-Navier-Stokes equations is the use of the full continuity equation required even for a binary mixture of incompressible liquids, firstly, due to dependence of mixture density on concentration and, secondly, due to strong concentration gradients at liquids' interfaces. Using the multiple-scale method we separate the physical processes occurring on different time scales and, ultimately, provide a strict derivation of the Boussinesq approximation for the Cahn-Hilliard-Navier-Stokes equations. This approximation forms a universal theoretical model that can be further employed for a thermo/hydro-dynamic ...

Vorobev, Anatoliy

2010-01-01T23:59:59.000Z

42

A family of algorithms for approximate Bayesian inference  

E-Print Network (OSTI)

One of the major obstacles to using Bayesian methods for pattern recognition has been its computational expense. This thesis presents an approximation technique that can perform Bayesian inference faster and more accurately than previously possible. This method, "Expectation Propagation," unifies and generalizes two previous techniques: assumeddensity filtering, an extension of the Kalman filter, and loopy belief propagation, an extension of belief propagation in Bayesian networks. The unification shows how both of these algorithms can be viewed as approximating the true posterior distribution with a simpler distribution, which is close in the sense of KL-divergence. Expectation Propagation exploits the best of both algorithms: the generality of assumed-density filtering and the accuracy of loopy belief propagation. Loopy belief propagation, because it propagates exact belief states, is useful for limited types of belief networks, such as purely discrete networks. Expectation Propagati...

Rosalind Picard; Thomas P. Minka; Thomas P Minka

2001-01-01T23:59:59.000Z

43

COSMOLOGICAL POST-NEWTONIAN APPROXIMATION COMPARED WITH PERTURBATION THEORY  

Science Conference Proceedings (OSTI)

We compare the cosmological first-order post-Newtonian (1PN) approximation with the relativistic cosmological linear perturbation theory in a zero-pressure medium with the cosmological constant. We compare equations and solutions in several different gauge conditions available in both methods. In the PN method we have perturbation equations for density, velocity, and gravitational potential independently of the gauge condition to 1PN order. However, correspondences with these 1PN equations are available only in certain gauge conditions in the perturbation theory. Equations of perturbed velocity and the perturbed gravitational potential in the zero-shear gauge exactly coincide with the Newtonian equations, which remain valid even to 1PN order (the same is true for perturbed velocity identified in the comoving gauge), and equations of perturbed density in the zero-shear gauge and the uniform-expansion gauge coincide to 1PN order. We identify other correspondences available in different gauge conditions of the perturbation theory.

Noh, Hyerim [Korea Astronomy and Space Science Institute, Daejon 305-348 (Korea, Republic of); Hwang, Jai-chan [Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

2012-10-01T23:59:59.000Z

44

Determination of approximate nonlinear self-adjointenss and approximate conservation law  

E-Print Network (OSTI)

Approximate nonlinear self-adjointness is an effective method to construct approximate conservation law of perturbed partial differential equations (PDEs). In this paper, we study the relations between approximate nonlinear self-adjointness of perturbed PDEs and nonlinear self-adjointness of the corresponding unperturbed PDEs, and consequently provide a simple approach to discriminate approximate nonlinear self-adjointness of perturbed PDEs. Moreover, a succinct approximate conservation law formula by virtue of the known conservation law of the unperturbed PDEs is given in an explicit form. As an application, we classify a class of perturbed wave equations to be approximate nonlinear self-adjointness and construct the general approximate conservation laws formulae. The specific examples demonstrate that approximate nonlinear self-adjointness can generate new approximate conservation laws.

Zhi-Yong Zhang

2013-01-19T23:59:59.000Z

45

Polymer state approximations of Schroedinger wave functions  

E-Print Network (OSTI)

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.

Klaus Fredenhagen; Felix Reszewski

2006-06-21T23:59:59.000Z

46

Improved approximations for k-exchange systems  

Science Conference Proceedings (OSTI)

Submodular maximization and set systems play a major role in combinatorial optimization. It is long known that the greedy algorithm provides a 1/(k + 1)-approximation for maximizing a monotone submodular function over a k-system. For the ...

Moran Feldman; Joseph Naor; Roy Schwartz; Justin Ward

2011-09-01T23:59:59.000Z

47

N-Stream Approximations to Radiative Transfer  

Science Conference Proceedings (OSTI)

Schuster's two-stream approximation is first derived from Chandrasekhar's radiative transfer equation, and then generalized to an arbitrary number of streams. The resulting technique for solving the transfer equation that is similar to the ...

Charles Acquista; Frederick House; James Jafolla

1981-07-01T23:59:59.000Z

48

Linear source approximation in CASMO5  

Science Conference Proceedings (OSTI)

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)

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

49

Blind multiuser detection based on kernel approximation  

Science Conference Proceedings (OSTI)

A kernel based multiuser detection (MUD) scheme in code-division multiple-access (CDMA) system is proposed. In this scheme, the support vector (SV) under support vector (SVM) framework is obtained through a kernel sparsity approximation, which regulates ...

Tao Yang; Bo Hu

2006-05-01T23:59:59.000Z

50

Casimir forces beyond the proximity approximation  

E-Print Network (OSTI)

The proximity force approximation (PFA) relates the interaction between closely spaced, smoothly curved objects to the force between parallel plates. Precision experiments on Casimir forces necessitate, and spur research ...

Bimonte, G.

51

Convergence Rates of Approximation by Translates  

E-Print Network (OSTI)

In this paper we consider the problem of approximating a function belonging to some funtion space Φ by a linear comination of n translates of a given function G. Ussing a lemma by Jones (1990) and Barron (1991) we show ...

Girosi, Federico

1992-03-01T23:59:59.000Z

52

An approximation trichotomy for Boolean #CSP  

E-Print Network (OSTI)

We give a trichotomy theorem for the complexity of approximately counting the number of satisfying assignments of a Boolean CSP instance. Such problems are parameterised by a constraint language specifying the relations that may be used in constraints. If every relation in the constraint language is affine then the number of satisfying assignments can be exactly counted in polynomial time. Otherwise, if every relation in the constraint language is in the co-clone IM2 from Post’s lattice, then the problem of counting satisfying assignments is complete with respect to approximation-preserving reductions in the complexity class #RH?1. This means that the problem of approximately counting satisfying assignments of such a CSP instance is equivalent in complexity to several other known counting problems, including the problem of approximately counting the number of independent sets in a bipartite graph. For every other fixed constraint language, the problem is complete for #P with respect to approximation-preserving reductions, meaning that there is no fully polynomial randomised approximation scheme for counting satisfying assignments unless NP=RP. 1

Martin Dyer; Leslie Ann Goldberg; Mark Jerrum

2007-01-01T23:59:59.000Z

53

Mass Conservation and the Anelastic Approximation  

Science Conference Proceedings (OSTI)

Numerical anelastic models solve a diagnostic elliptic equation for the pressure field using derivative boundary conditions. The pressure is therefore determined to within a function proportional to the base-state density field with arbitrary ...

Peter R. Bannon; Jeffrey M. Chagnon; Richard P. James

2006-10-01T23:59:59.000Z

54

On the Accuracy of the MINC approximation  

DOE Green Energy (OSTI)

The method of ''multiple interacting continua'' is based on the assumption that changes in thermodynamic conditions of rock matrix blocks are primarily controlled by the distance from the nearest fracture. The accuracy of this assumption was evaluated for regularly shaped (cubic and rectangular) rock blocks with uniform initial conditions, which are subjected to a step change in boundary conditions on the surface. Our results show that pressures (or temperatures) predicted from the MINC approximation may deviate from the exact solutions by as much as 10 to 15% at certain points within the blocks. However, when fluid (or heat) flow rates are integrated over the entire block surface, MINC-approximation and exact solution agree to better than 1%. This indicates that the MINC approximation can accurately represent transient inter-porosity flow in fractured porous media, provided that matrix blocks are indeed subjected to nearly uniform boundary conditions at all times.

Lai, C.H.; Pruess, K.; Bodvarsson, G.S.

1986-02-01T23:59:59.000Z

55

The Exact Renormalisation Group and Approximate Solutions  

E-Print Network (OSTI)

We investigate the structure of Polchinski's formulation of the flow equations for the continuum Wilson effective action. Reinterpretations in terms of I.R. cutoff greens functions are given. A promising non-perturbative approximation scheme is derived by carefully taking the sharp cutoff limit and expanding in `irrelevancy' of operators. We illustrate with two simple models of four dimensional $\\lambda \\varphi^4$ theory: the cactus approximation, and a model incorporating the first irrelevant correction to the renormalized coupling. The qualitative and quantitative behaviour give confidence in a fuller use of this method for obtaining accurate results.

Tim R. Morris

1993-08-12T23:59:59.000Z

56

Consistent Velocity Approximation for Finite Volume or Element Discretizations of Density  

E-Print Network (OSTI)

The CSR used in this experiment is part of an SDS [1], as was mentioned earlier. The speech material

Frolkovic, Peter

57

Symbolic Test Selection Based on Approximate Analysis  

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

58

Approximations to the Distributed Activation Energy Model  

E-Print Network (OSTI)

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

McGuinness, Mark

59

Nonlinear piecewise polynomial approximation: Theory and Algorithms  

E-Print Network (OSTI)

algorithms for compression and quick rendering of Digital Terrain Elevation Data (DTED) maps and implement by these and further theoretical results, we develop eÃ?cient practical algorithms for compression and quick rendering linear approximation 23 2.3. Slim B-spaces 32 2.4. Skinny B-spaces 42 2.5. Fat B-spaces: The link

Karaivanov, Borislav

60

Nonlinear piecewise polynomial approximation: Theory and Algorithms  

E-Print Network (OSTI)

algorithms for compression and quick rendering of Digital Terrain Elevation Data (DTED) maps and implement results, we develop efficient practical algorithms for compression and quick rendering of Digital Terrain approximation 23 2.3. Slim B-spaces 32 2.4. Skinny B-spaces 42 2.5. Fat B-spaces: The link to Besov spaces 46 2

Karaivanov, Borislav

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Real-time creased approximate subdivision surfaces  

Science Conference Proceedings (OSTI)

We present an extension of recently developed Loop and Schaefer's approximation of Catmull-Clark surfaces (ACC) for surfaces with creases and corners which are essential for most applications. We discuss the integration of ACC into Valve's Source game ... Keywords: GPU tessellation, geometric modeling, hardware rendering, subdivision surfaces, video games

Denis Kovacs; Jason Mitchell; Shanon Drone; Denis Zorin

2009-02-01T23:59:59.000Z

62

Complete Orders, Categories and Lattices of Approximations  

Science Conference Proceedings (OSTI)

The present article deals with the problem whether and how the bilattice orderings of knowledge ⩽$_k$ and truth ⩽$_t$ might enrich the theory of rough sets. Passing to the chief idea of the paper, we develop a bilattice-theoretic generalisation ... Keywords: *-autonomous category, Chu construction, Nelson lattice, approximation, bilattice, complete partial order, rough set

Marcin Wolski

2006-09-01T23:59:59.000Z

63

UNIFORM SEMICLASSICAL APPROXIMATION IN QUANTUM STATISTICAL MECHANICS.  

SciTech Connect

We present a simple method to deal with caustics in the semiclassical approximation to the partition function of a one-dimensional quantum system. The procedure, which makes use of complex trajectories, is applied to the quartic double-well potential.

De Carvalho, C.A.A.; Cavalcanit, R.M.; Fraga, E.S.; Joras, S.E.

2000-10-23T23:59:59.000Z

64

Scattering Length Density Calculator  

Science Conference Proceedings (OSTI)

... For energy dependent cross sections please go to ... The neutron scattering length density is defined ... To calculate scattering length densities enter a ...

65

Testing approximations beyond the proton-neutron quasiparticle random phase approximation  

Science Conference Proceedings (OSTI)

In this work we analyze the validity of recently proposed extensions of the Quasiparticle Random Phase Approximation (QRPA). Particularly, we focus our attention on the Fully Renormalized QRPA (FRQRPA). We found that the results of this approximation do not differ from the results of the QRPA. This finding is supported by a detailed comparison between both formalisms, their assumptions and approximations, in the context of realistic calculations.

Civitarese, O.; Mariano, A. [Department of Physics. University of La Plata, C. C. 67 1900 La Plata (Argentina); Hirsch, J. G. [Instituto de Ciencias Nucleares, UNAM, A. P. 70-543, 04510 Mexico City, D. F. (Mexico); Reboiro, M. [Department of Physics. University of La Plata, C. C. 67 1900 La Plata (Argentina); Faculty of Engineering, University of Lomas de Zamora, Km 2 (1836) Lavallol (Argentina)

2007-08-15T23:59:59.000Z

66

Approximating stochastic volatility by recombinant trees  

E-Print Network (OSTI)

A general method to construct recombinant tree approximations for stochastic volatility models is developed and applied to the Heston model for stock price dynamics. In this application, the resulting approximation is a four tuple Markov process. The ?first two components are related to the stock and volatility processes and take values in a two dimensional Binomial tree. The other two components of the Markov process are the increments of random walks with simple values in {-1; +1}. The resulting effi?cient option pricing equations are numerically implemented for general American and European options including the standard put and calls, barrier, lookback and Asian type pay-o?ffs. The weak and extended weak convergence are also proved.

Akyildirim, Erdinc; Soner, H Mete

2012-01-01T23:59:59.000Z

67

Approximate gauge symmetry of composite vector bosons  

SciTech Connect

It can be shown in a solvable field theory model that the couplings of the composite vector bosons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in a more intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.

Suzuki, Mahiko [Lawrence Berkeley National Laboratory and Department of Physics, University of California, Berkeley, California 94720 (United States)

2010-08-15T23:59:59.000Z

68

Approximate gauge symemtry of composite vector bosons  

SciTech Connect

It can be shown in a solvable field theory model that the couplings of the composite vector mesons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in more an intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.

Suzuki, Mahiko

2010-06-01T23:59:59.000Z

69

Dictionary Approximation For Matching Pursuit Video Coding  

E-Print Network (OSTI)

Previously, we demonstrated an efficient video codec based on overcomplete signal decomposition using matching pursuits. Dictionary design is an important issue for this system, and others have shown alternate dictionaries which lead to either coding efficiency improvements or reduced encoder complexity. In this work, we introduce for the first time a design methodology which incorporates both coding efficiency and complexity in a systematic way. The key to our new method is an algorithm which takes an arbitrary 2-D dictionary and generates approximations of the dictionary which have fast 2-stage implementations. By varying the quality of the approximation, we can explore a systematic tradeoff between the coding efficiency and complexity of the matching pursuit video encoder. As a practical result, we show cases where complexity is reduced by a factor of 500 to 1000 in exchange for small coding efficiency losses of around 0.1 dB PSNR. 1. INTRODUCTION Most video codecs in use today ar...

Ralph Neff; Avideh Zakhor

2000-01-01T23:59:59.000Z

70

Entanglement in GaAs and CdSe quantum dots: Exact calculations and DFT approximations  

Science Conference Proceedings (OSTI)

We consider two electrons confined in spherical GaAs and CdSe quantum dots and calculate their ground-state spatial entanglement exactly within a parabolic confinement model. We propose a perturbative scheme to approximate the above entanglement within ... Keywords: Density-functional theory, Entanglement, Quantum dots, Quantum information, Semiconductors

J. P. Coe; A. Sudbery; I. D'Amico

2009-03-01T23:59:59.000Z

71

Nuclear matter EOS with light clusters within the mean-field approximation  

E-Print Network (OSTI)

The crust of a neutron star is essentially determined by the low-density region ($\\rholight clusters in nuclear matter will be energetically favorable at finite temperature. At very low densities and moderate temperatures, the few body correlations are expected to become important and light nuclei like deuterons, tritons, helions and $\\alpha$-particles will form. Due to Pauli blocking, these clusters will dissolve at higher densities $\\rho\\gtrsim 0.1\\rho_0$. The presence of these clusters influences the cooling process and quantities, such as the neutrino emissivity and gravitational waves emission. The dissolution density of these light clusters, treated as point-like particles, will be studied within the Relativistic Mean Field approximation. In particular, the dependence of the dissolution density on the clusters-meson couplings is studied.

Márcio Ferreira; Constança Providência

2013-07-09T23:59:59.000Z

72

Shear viscosity in the postquasistatic approximation  

Science Conference Proceedings (OSTI)

We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of anisotropic nonadiabatic 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 noncomoving coordinates, with the Vaidya exterior solution. Two simple models are presented, based on the Schwarzschild and Tolman VI solutions, in the nonadiabatic and adiabatic limit. In both cases, the eventual collapse or expansion of the distribution is mainly controlled by the anisotropy induced by the viscosity.

Peralta, C.; Rosales, L.; Rodriguez-Mueller, B.; Barreto, W. [Deutscher Wetterdienst, Frankfurter Str. 135, 63067 Offenbach (Germany); Laboratorio de Fisica Computacional, Universidad Experimental Politecnica 'Antonio Jose de Sucre', Puerto Ordaz (Venezuela, Bolivarian Republic of); Computational Science Research Center, College of Sciences, San Diego State University, San Diego, California (United States); Centro de Fisica Fundamental, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of)

2010-05-15T23:59:59.000Z

73

Analytic approximate radiation effects due to Bremsstrahlung  

SciTech Connect

The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

Ben-Zvi I.

2012-02-01T23:59:59.000Z

74

The benchmark of gutzwiller density functional theory in hydrogen systems  

SciTech Connect

We propose an approximate form of the exchange-correlation energy functional for the Gutzwiller density functional theory. It satisfies certain physical constraints in both weak and strong electron correlation limits. We benchmark the Gutzwiller density functional approximation in the hydrogen systems, where the static correlation error is shown to be negligible. The good transferability is demonstrated by applications to the hydrogen molecule and some crystal structures.

Yao, Y.; Wang, Cai-Zhuang; Ho, Kai-Ming

2012-02-23T23:59:59.000Z

75

Computing Polynomial Greatest Common Divisors over ... - CECM  

E-Print Network (OSTI)

problems, which makes computing with polynomials involving field extensions ? hopeless?. .... g := 2*t*x^2-3*s*y^2-alpha*s^3*x*y + alpha^2*s*x + 5*beta*t^3;.

76

Semiclassical approximation to supersymmetric quantum gravity  

SciTech Connect

We develop a semiclassical approximation scheme for the constraint equations of supersymmetric canonical quantum gravity. This is achieved by a Born-Oppenheimer type of expansion, in analogy to the case of the usual Wheeler-DeWitt equation. The formalism is only consistent if the states at each order depend on the gravitino field. We recover at consecutive orders the Hamilton-Jacobi equation, the functional Schroedinger equation, and quantum gravitational correction terms to this Schroedinger equation. In particular, the following consequences are found: (i) the Hamilton-Jacobi equation and therefore the background spacetime must involve the gravitino, (ii) a (many-fingered) local time parameter has to be present on super Riem {sigma} (the space of all possible tetrad and gravitino fields) (iii) quantum supersymmetric gravitational corrections affect the evolution of the very early Universe. The physical meaning of these equations and results, in particular, the similarities to and differences from the pure bosonic case, are discussed.

Kiefer, Claus; Lueck, Tobias; Moniz, Paulo [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Cologne (Germany); Astronomy Unit, School of Mathematical Sciences, Queen Mary College, University of London, Mile End Road, London E1 4NS (United Kingdom)

2005-08-15T23:59:59.000Z

77

Heat flow in the postquasistatic approximation  

Science Conference Proceedings (OSTI)

We apply the postquasistatic approximation to study the evolution of spherically symmetric fluid distributions undergoing dissipation in the form of radial heat flow. For a model that corresponds to an incompressible fluid departing from the static equilibrium, it is not possible to go far from the initial state after the emission of a small amount of energy. Initially collapsing distributions of matter are not permitted. Emission of energy can be considered as a mechanism to avoid the collapse. If the distribution collapses initially and emits one hundredth of the initial mass only the outermost layers evolve. For a model that corresponds to a highly compressed Fermi gas, only the outermost shell can evolve with a shorter hydrodynamic time scale.

Rodriguez-Mueller, B. [Computational Science Research Center, College of Sciences, San Diego State University, San Diego, California (United States); Peralta, C. [Deutscher Wetterdienst, Frankfurter Strasse 135, 63067 Offenbach (Germany); School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Barreto, W. [Centro de Fisica Fundamental, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Rosales, L. [Laboratorio de Fisica Computacional, Universidad Experimental Politecnica, 'Antonio Jose de Sucre', Puerto Ordaz (Venezuela, Bolivarian Republic of)

2010-08-15T23:59:59.000Z

78

Generic sequential sampling for metamodel approximations  

SciTech Connect

Metamodels approximate complex multivariate data sets from simulations and experiments. These data sets often are not based on an explicitly defined function. The resulting metamodel represents a complex system's behavior for subsequent analysis or optimization. Often an exhaustive data search to obtain the data for the metalnodel is impossible, so an intelligent sampling strategy is necessary. While inultiple approaches have been advocated, the majority of these approaches were developed in support of a particular class of metamodel, known as a Kriging. A more generic, cotninonsense approach to this problem allows sequential sampling techniques to be applied to other types of metamodeis. This research compares recent search techniques for Kriging inetamodels with a generic, inulti-criteria approach combined with a new type of B-spline metamodel. This B-spline metamodel is competitive with prior results obtained with a Kriging metamodel. Furthermore, the results of this research highlight several important features necessary for these techniques to be extended to more complex domains.

Turner, C. J. (Cameron J.); Campbell, M. I. (Matthew I.)

2003-01-01T23:59:59.000Z

79

Comonotonic approximations for optimal portfolio selection problems  

E-Print Network (OSTI)

We investigate multiperiod portfolio selection problems in a Black & Scholes type market where a basket of 1 riskfree and m risky securities are traded continuously. We look for the optimal allocation of wealth within the class of ’constant mix ’ portfolios. First, we consider the portfolio selection problem of a decision maker who invests money at predetermined points in time in order to obtain a target capital at the end of the time period under consideration. A second problem concerns a decision maker who invests some amount of money (the initial wealth or provision) in order to be able to fullfil a series of future consumptions or payment obligations. Several optimality criteria and their interpretation within Yaari’s dual theory of choice under risk are presented. For both selection problems, we propose accurate approximations based on the concept of comonotonicity, as studied in Dhaene, Denuit, Goovaerts, Kaas & Vyncke (2002 a,b). Our analytical approach avoids simulation, and hence reduces the computing effort drastically. 1

J. Dhaene; S. Vanduffel; M. J. Goovaerts; R. Kaas; D. Vyncke

2005-01-01T23:59:59.000Z

80

Thermal Density Functional Theory in Context  

E-Print Network (OSTI)

This chapter introduces thermal density functional theory, starting from the ground-state theory and assuming a background in quantum mechanics and statistical mechanics. We review the foundations of density functional theory (DFT) by illustrating some of its key reformulations. The basics of DFT for thermal ensembles are explained in this context, as are tools useful for analysis and development of approximations. We close by discussing some key ideas relating thermal DFT and the ground state. This review emphasizes thermal DFT's strengths as a consistent and general framework.

Pribram-Jones, Aurora; Gross, E K U; Burke, Kieron

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Evolution of primordial magnetic fields in mean-field approximation  

E-Print Network (OSTI)

We study the evolution of phase-transition-generated cosmic magnetic fields coupled to the primeval cosmic plasma in turbulent and viscous free-streaming regimes. The evolution laws for the magnetic energy density and correlation length, both in helical and non-helical cases, are found by solving the autoinduction and Navier-Stokes equations in mean-field approximation. Analytical results are derived in Minkowski spacetime and then extended to the case of a Friedmann universe with zero spatial curvature, both in radiation and matter dominated eras. The three possible viscous free-streaming phases are characterized by a drag term in the Navier-Stokes equation which depends on the free-steaming properties of neutrinos, photons, or hydrogen atoms, respectively. In the case of non-helical magnetic fields, the magnetic intensity $B$ and the magnetic correlation length $\\xi_B$ evolve asymptotically with the temperature $T$ as $B(T) \\simeq \\kappa_B (N_i v_i)^{\\varrho_1} (T/T_i)^{\\varrho_2}$ and $\\xi_B(T) \\simeq \\kap...

Campanelli, Leonardo

2013-01-01T23:59:59.000Z

82

A Class of Semi-Lagrangian Approximations for Fluids  

Science Conference Proceedings (OSTI)

This paper discusses a class of finite-difference approximations to the evolution equations of fluid dynamics. These approximations derive from elementary properties of differential forms. Values of a fluid variable ? at any two points of a space-...

Piotr K. Smolarkiewicz; Janusz A. Pudykiewicz

1992-11-01T23:59:59.000Z

83

Four-Stream Isosector Approximation for Solar Radiative Transfer  

Science Conference Proceedings (OSTI)

For radiative transfer in a thin atmosphere, an analytical four-stream isosector approximation for solar radiative transfer is presented. This approximation method is based on the assumption of four spherical sectors of isotropic intensities. ...

J. Li; J. S. Dobbie

1998-02-01T23:59:59.000Z

84

Weak Pressure Gradient Approximation and Its Analytical Solutions  

Science Conference Proceedings (OSTI)

A weak pressure gradient (WPG) approximation is introduced for parameterizing supradomain-scale (SDS) dynamics, and this method is compared to the relaxed form of the weak temperature gradient (WTG) approximation in the context of 3D, linearized, ...

David M. Romps

2012-09-01T23:59:59.000Z

85

Dynamic Enthalpy, Conservative Temperature, and the Seawater Boussinesq Approximation  

Science Conference Proceedings (OSTI)

A new seawater Boussinesq system is introduced, and it is shown that this approximation to the equations of motion of a compressible binary solution has an energy conservation law that is a consistent approximation to the Bernoulli equation of ...

William R. Young

2010-02-01T23:59:59.000Z

86

Table A3. Approximate Heat Content of Petroleum Consumption and ...  

U.S. Energy Information Administration (EIA)

Table A3. Approximate Heat Content of Petroleum Consumption and Biofuels Production, 1949-2011 (Million Btu per Barrel)

87

Weighted trapezoidal approximation-preserving cores of a fuzzy number  

Science Conference Proceedings (OSTI)

Recently, various researchers have proved that approximations of fuzzy numbers may fail to be fuzzy numbers. In this contribution, we suggest a new weighted trapezoidal approximation of an arbitrary fuzzy number, which preserves its cores. We prove that ... Keywords: Core of fuzzy number, Fuzzy numbers, Trapezoidal fuzzy numbers, Weighted approximation

S. Abbasbandy; T. Hajjari

2010-05-01T23:59:59.000Z

88

Curvilinear parabolic approximation for surface wave transformation with wavecurrent interaction  

E-Print Network (OSTI)

Curvilinear parabolic approximation for surface wave transformation with wave­current interaction not be an appropriate method for the purpose of simplifying the curvilinear parabolic approximation of the vector form of the wave­current equation given by Kirby [Higher-order approximations in the parabolic equation method

Kirby, James T.

89

Density | OpenEI  

Open Energy Info (EERE)

Density Density Dataset Summary Description This dataset is part of a larger internal dataset at the National Renewable Energy Laboratory (NREL) that explores various characteristics of large solar electric (both PV and CSP) facilities around the United States. This dataset focuses on the land use characteristics for solar facilities that are either under construction or currently in operation. Source Land-Use Requirements for Solar Power Plants in the United States Date Released June 25th, 2013 (5 months ago) Date Updated Unknown Keywords acres area average concentrating solar power csp Density electric hectares km2 land land requirements land use land-use mean photovoltaic photovoltaics PV solar statistics Data application/vnd.openxmlformats-officedocument.spreadsheetml.sheet icon Master Solar Land Use Spreadsheet (xlsx, 1.5 MiB)

90

Single-Nucleon Densities  

NLE Websites -- All DOE Office Websites (Extended Search)

Densities Densities This web page presents single-nucleon densities calculated for a variety of nuclei in the range A=2-10 with some preliminary results for A=11,12. These are from variational Monte Carlo calculations (VMC) using the Argonne v18 two-nucleon and Urbana X three-nucleon potentials (AV18+UX). (Urbana X is intermediate between the Urbana IX and Illinois-7 models; it has the form of UIX supplemented with a two-pion S-wave piece, while the strengths of its terms are taken from the IL7 model. It does NOT have the three-pion-ring term of IL7.) These VMC wave functions are the starting trial functions for a number of recent Green's function Monte Carlo (GFMC) calculations: Brida, et al., Phys. Rev. C 84, 024319 (2011); McCutchan, et al., Phys. Rev. C 86, 024315 (2012);

91

Density Inhomogeneities and Electron Mobility in Supercritical Xenon  

NLE Websites -- All DOE Office Websites (Extended Search)

Density Inhomogeneities and Electron Mobility in Supercritical Xenon Density Inhomogeneities and Electron Mobility in Supercritical Xenon Richard A. Holroyd, Kengo Itoh, and Masaru Nishikawa J. Chem. Phys. 118, 706-710 (2003) [Find paper at Scitation] Abstract: The low-field mobility of electrons in supercritical Xe has been measured isothermally as a function of density above the critical temperature (289.7 K). At 293 K the mobility varies from a high of 890 cm2/Vs at 9.2 x 1021 atoms/cm3 to a minimum value of 4.6 cm2/Vs at a density of 3.5 x 1021 atoms/cm3, which is just below the critical density. The density dependence of the mobility is reasonably well predicted by the deformation potential model if the adiabatic compressibility is used to characterize the electron-medium interactions. Approximate agreement indicates that

92

SoftPCM: Enhancing Energy Efficiency and Lifetime of Phase Change Memory in Video Applications via Approximate Write  

Science Conference Proceedings (OSTI)

Modern video applications such as video codecs are memory-intensive. As an emerging non-volatile memory technology, phase change memory (PCM) will benefit video applications due to its high density, low leakage power and superior scalability. However, ... Keywords: Approximate write, data-comparison write, error tolerance, PCM, write endurance

Yuntan Fang; Huawei Li; Xiaowei Li

2012-11-01T23:59:59.000Z

93

N-density representability and the optimal transport limit of the Hohenberg-Kohn functional  

E-Print Network (OSTI)

We derive and analyze a hierarchy of approximations to the strongly correlated limit of the Hohenberg-Kohn functional. These "density representability approximations" are obtained by first noting that in the strongly correlated limit, N-representability of the pair density reduces to the requirement that the pair density must come from a symmetric N-point density. One then relaxes this requirement to the existence of a representing symmetric k-point density with k < N. The approximate energy can be computed by simulating a fictitious k-electron system. We investigate the approximations by deriving analytically exact results for a 2-site model problem, and by incorporating them into a self-consistent Kohn-Sham calculation for small atoms. We find that the low order representability conditions already capture the main part of the correlations.

Friesecke, Gero; Pass, Brendan; Cotar, Codina; Klüppelberg, Claudia

2013-01-01T23:59:59.000Z

94

An Approximation Algorithm for Computing a Parsimonious ... - CECM  

E-Print Network (OSTI)

Due to the large number of species in the real data set ? 6808 fungal gene trees from 23 species ? we applied only our approximation algorithm. We observed.

95

Finding approximately rank-one submatrices with the nuclear norm ...  

E-Print Network (OSTI)

Nov 8, 2010 ... Abstract: We propose a convex optimization formulation with the nuclear norm and $\\ell_1$-norm to find a large approximately rank-one ...

96

Hardness and Approximation Results for Lp–Ball Constrained ...  

E-Print Network (OSTI)

Oct 31, 2012... a fundamental research issue is to determine their approximability. ...... R. Saigal, and L. Vandenberghe, editors, Handbook of Semidefinite ...

97

Polynomial time algorithms to approximate mixed volumes within a ...  

E-Print Network (OSTI)

Apr 11, 2007 ... ellipsoid method and a randomized poly-time time algorithm for the approximation of the volume of a convex set. ? gurvits@lanl.gov.

98

Table A3. Approximate Heat Content of Petroleum Consumption and ...  

U.S. Energy Information Administration (EIA)

U.S. Energy Information Administration / Annual Energy Review 2011 323 Table A3. Approximate Heat Content of Petroleum Consumption and Biofuels Production, Selected ...

99

Table A3. Approximate Heat Content of Petroleum Consumption and ...  

U.S. Energy Information Administration (EIA)

Table A3. Approximate Heat Content of Petroleum Consumption and Biofuels Production, 1949-2011 (Million Btu per Barrel) Year: Total Petroleum 1 ...

100

Multiple density layered insulator  

DOE Patents (OSTI)

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.

Alger, T.W.

1994-09-06T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Multiple density layered insulator  

DOE Patents (OSTI)

A multiple density layered insulator for use with a laser is disclosed wh 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.

Alger, Terry W. (Tracy, CA)

1994-01-01T23:59:59.000Z

102

Approximating the traffic grooming problem in tree and star networks  

Science Conference Proceedings (OSTI)

We consider the problem of grooming paths in all-optical networks with tree topology so as to minimize the switching cost, measured by the total number of used ADMs. We first present efficient approximation algorithms with approximation factor of 2 ln ... Keywords: add-drop multiplexer (ADM), optical networks, traffic grooming, tree networks, wavelength division multiplexing (WDM)

Michele Flammini; Gianpiero Monaco; Luca Moscardelli; Mordechai Shalom; Shmuel Zaks

2006-06-01T23:59:59.000Z

103

On the progressive iteration approximation property and alternative iterations  

Science Conference Proceedings (OSTI)

This note revisits the progressive iteration approximation property and some recent modifications from the point of view of iterative methods for solving linear systems. In particular we show the connection with the classical Richardson iteration and ... Keywords: GMRES, Interpolation, Iterative methods, Progressive iteration approximation

J. M. Carnicer; J. Delgado; J. M. Peña

2011-12-01T23:59:59.000Z

104

A constrained binary knapsack approximation for shortest path network interdiction  

Science Conference Proceedings (OSTI)

A modified shortest path network interdiction model is approximated in this work by a constrained binary knapsack which uses aggregated arc maximum flow as the objective function coefficient. In the modified shortest path network interdiction problem, ... Keywords: Approximation techniques, Homeland security, Integer programming, Network interdiction

Justin Yates; Kavitha Lakshmanan

2011-11-01T23:59:59.000Z

105

Error estimates for the numerical approximation of Neumann control problems  

Science Conference Proceedings (OSTI)

We continue the discussion of error estimates for the numerical analysis of Neumann boundary control problems we started in Casas et al. (Comput. Optim. Appl. 31:193-219, 2005). In that paper piecewise constant functions were used to approximate the ... Keywords: boundary control, error estimates, numerical approximation, semilinear elliptic equation

Eduardo Casas; Mariano Mateos

2008-04-01T23:59:59.000Z

106

On-line Approximate String Matching in Natural Language  

Science Conference Proceedings (OSTI)

We consider approximate pattern matching in natural language text. We use the words of the text as the alphabet, instead of the characters as in traditional string matching approaches. Hence our pattern consists of a sequence of words. From the algorithmic ... Keywords: Approximate string matching, filtering, natural language processing, phrase matching, word alphabet

Kimmo Fredriksson

2006-09-01T23:59:59.000Z

107

Quantile approximations in auto-regressive portfolio models  

Science Conference Proceedings (OSTI)

This paper develops an analytical approximation for the distribution function of a terminal value of a periodic series of buy-and-hold investments placed over a fixed time horizon for the case when log-returns of assets follow a p-th order vector auto-regressive ... Keywords: Multi-period portfolio return, Taylor conditioned approximation, Vector auto-regressive returns

Aleš Ah?an; Igor Masten; Sašo Polanec; Mihael Perman

2011-02-01T23:59:59.000Z

108

Thermodynamic Consistency of the Anelastic Approximation for a Moist Atmosphere  

Science Conference Proceedings (OSTI)

The primary goal of this paper is to validate the use of the anelastic approximation for fluids with a complex equation of state such as moist air or seawater. The anelastic approximation is based on a leading-order expansion of the equations of ...

Olivier Pauluis

2008-08-01T23:59:59.000Z

109

Reasoning with rough description logics: An approximate concepts approach  

Science Conference Proceedings (OSTI)

The current research progress and the existing problems of uncertain or imprecise knowledge representation and reasoning in description logics are analyzed in this paper. Approximate concepts are introduced to description logics based on rough set theory, ... Keywords: Approximate concepts, Concepts, Description logics, Rough description logics, Rough set theory

Yuncheng Jiang; Ju Wang; Suqin Tang; Bao Xiao

2009-02-01T23:59:59.000Z

110

Neural Acceleration for General-Purpose Approximate Programs  

Science Conference Proceedings (OSTI)

This paper describes a learning-based approach to the acceleration of approximate programs. We describe the \\emph{Parrot transformation}, a program transformation that selects and trains a neural network to mimic a region of imperative code. After the ... Keywords: Approximate Computing, Neural Networks, Accelerator, Neural Processing Unit, NPU

Hadi Esmaeilzadeh; Adrian Sampson; Luis Ceze; Doug Burger

2012-12-01T23:59:59.000Z

111

Approximating Selective Sweeps by Richard Durrett and Jason Schweinsberg  

E-Print Network (OSTI)

Approximating Selective Sweeps by Richard Durrett and Jason Schweinsberg Dept. of Math, Cornell U of selective sweeps on genealogies. However, most subsequent work has simplified their approach by assuming that the impact of a selective sweep can be accurately approximated by a random partition created by a stick

Durrett, Richard

112

An approximation algorithm for convex multi-objective programming problems  

Science Conference Proceedings (OSTI)

In multi-objective convex optimization it is necessary to compute an infinite set of nondominated points. We propose a method for approximating the nondominated set of a multi-objective nonlinear programming problem, where the objective functions and ... Keywords: ?-nondominated point, Approximation algorithm, Convex optimization, Multi-objective optimization

Matthias Ehrgott; Lizhen Shao; Anita Schöbel

2011-07-01T23:59:59.000Z

113

Tensor Product Approximation (DMRG) and Coupled Cluster method in Quantum Chemistry  

E-Print Network (OSTI)

We present the Copupled Cluster (CC) method and the Density matrix Renormalization Grooup (DMRG) method in a unified way, from the perspective of recent developments in tensor product approximation. We present an introduction into recently developed hierarchical tensor representations, in particular tensor trains which are matrix product states in physics language. The discrete equations of full CI approximation applied to the electronic Schr\\"odinger equation is casted into a tensorial framework in form of the second quantization. A further approximation is performed afterwards by tensor approximation within a hierarchical format or equivalently a tree tensor network. We establish the (differential) geometry of low rank hierarchical tensors and apply the Driac Frenkel principle to reduce the original high-dimensional problem to low dimensions. The DMRG algorithm is established as an optimization method in this format with alternating directional search. We briefly introduce the CC method and refer to our theoretical results. We compare this approach in the present discrete formulation with the CC method and its underlying exponential parametrization.

Örs Legeza; Thorsten Rohwedder; Reinhold Schneider; Szilárd Szalay

2013-10-10T23:59:59.000Z

114

Effective pairing interactions with isospin density dependence  

Science Conference Proceedings (OSTI)

We perform Hartree-Fock-Bogoliubov (HFB) calculations for semi-magic calcium, nickel, tin, and lead isotopes and N=20,28,50, and 82 isotones using density-dependent pairing interactions recently derived from a microscopic nucleon-nucleon interaction. These interactions have an isovector component so that the pairing gaps in symmetric and neutron matter are reproduced. Our calculations well account for the experimental data for the neutron number dependence of binding energy, two-neutron separation energy, and odd-even mass staggering of these isotopes. This result suggests that by introducing the isovector term in the pairing interaction, one can construct a global effective pairing interaction that is applicable to nuclei in a wide range of the nuclear chart. It is also shown with the local density approximation that the pairing field deduced from the pairing gaps in infinite matter reproduces qualitatively well the pairing field for finite nuclei obtained with the HFB method.

Margueron, J. [Institut de Physique Nucleaire, IN2P3-CNRS and Universite Paris-Sud, F-91406 Orsay Cedex (France); Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, 965-8580 Fukushima (Japan); Sagawa, H. [Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, 965-8580 Fukushima (Japan); Hagino, K. [Department of Physics, Tohoku University, Sendai, 980-8578 (Japan)

2008-05-15T23:59:59.000Z

115

Shock wave collisions in AdS5: approximate numerical solutions  

E-Print Network (OSTI)

We numerically study the evolution of a boost-invariant N=4 SYM medium using AdS/CFT. We consider a toy model for the collision of gravitational shock waves, finding that the energy density first increases, reaches a maximum and then starts to decrease, matching hydrodynamics for late times. For the initial conditions we consider, the hydrodynamic scale governing the late time behaviour is to very good approximation determined by the area of the black hole horizon at initial times. Our results provide a toy model for the early time evolution of the bulk system in heavy-ion collisions at RHIC and the LHC.

Bin Wu; Paul Romatschke

2011-08-18T23:59:59.000Z

116

The influence of annual species composition and density on perennial seedling density in four plant communities in the Northern Mojave Desert  

SciTech Connect

According to the Nuclear Waste Policy Act of 1982 (as amended in 1987), the US Department of Energy (DOE) must study and characterize Yucca Mountain as a potential site for long-term underground storage of high-level nuclear waste. Part of the overall site characterization program is to monitor potential impacts on the biological resources at Yucca Mountain. A part of the biological monitoring program, assessed vegetation parameters included density of annual and perennial seedlings. This data was used to evaluate: (1) seed germination and seed survival; and (2) if annual plant species density and cover influence perennial seedling survival. Twelve permanent 200 {times} 200-m ,study plots were established in each of four vegetation associations present in the Yucca Mountain Project area. During the spring of 1992, 20 to 60, 1-m{sup 2} randomly-located quadrats per study plot were measured for perennial seedling density, annual species density, and annual species composition. Perennial seedlings found in 1992 were relocated in the spring of 1993, and survival determined. Cover was measure in the spring of 1992. Annual plant density and cover was greatest in the Larrea-Lycium-Grayia vegetation association, and lowest in the Larrea-Ambrosia vegetation association. Annual seedling density had a negative exponential relationship with perennial seedling density in 1992. However, non-linear regression analysis indicated that 1992 annual seedling density had a greater impact on survival of pernnial seedlings from 1992 to 1993.

Hall, P.F.; Angerer, J.P.; Ostler, W.K. [EG and G Energy Measurements, Inc., Las Vegas, NV (United States); Schultz, B.W. [Nevada Univ., Reno, NV (United States). Desert Research Inst.

1993-12-31T23:59:59.000Z

117

Approximate Coulomb distortion effects in (e,e'p) reactions  

E-Print Network (OSTI)

In this paper we apply a well-tested approximation of electron Coulomb distortion effects to the exclusive reaction (e,e'p) in the quasielastic region. We compare the approximate treatment of Coulomb distortion effects to the exact distorted wave Born approximation evaluated by means of partial wave analysis to gauge the quality of our approximate treatment. We show that the approximate M\\"oller potential has a plane-wave-like structure and hence permits the separation of the cross section into five terms which depend on bilinear products of transforms of the transition four current elements. These transforms reduce to Fourier transforms when Coulomb distortion is not present, but become modified with the inclusion of Coulomb distortion. We investigate the application of the approximate formalism to a model of 208Pb(e,e'p) using Dirac-Hartree single particle wave functions for the ground state and relativistic optical model wave functions for the continuum proton. We show that it is still possible to extract, albeit with some approximation, the various structure functions from the experimentally measured data even for heavy nuclei.

K. S. Kim; L. E. Wright

2005-03-30T23:59:59.000Z

118

HIGH DENSITY SLAG CONCRETE  

SciTech Connect

Test results are presented that show that a strong concrete weighing approximately 185 lb/ft/sup 3/ can be made using water, waste lead slag, and Ciment Fondu. Feasibility, materials, mortar tests, concrete tests, and Ciment Fondu concretes are discussed. A 24-in.-thick concrete shield wall would have to be increased in thickness by 5 in. if slag concrete is used in place of barytes or magnetite concrete. On a pound-for-pound basis, the waste lead slag concrete materials were 30% cheaper than barytes and magnetite concrete materials. (M.C.G.)

Northup, T.E.

1963-08-01T23:59:59.000Z

119

High Energy Density Capacitors  

SciTech Connect

BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s 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.

None

2010-07-01T23:59:59.000Z

120

WKBJ Approximation of the Stability of a Frontal Mean State  

Science Conference Proceedings (OSTI)

The baroclinic instability of a frontal mean state is investigated using the WKBJ approximation. The results are compared with numerical calculations performed on the same mean state. Excellent agreement (within 5%) is found for jets whose half-...

Petros Ioannou; Richard S. Lindzen

1990-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

An empirical comparison of some approximate methods for graph coloring  

Science Conference Proceedings (OSTI)

The Graph Coloring Problem (GCP) is a classical NP-complete problem for which several approximate solution algorithms have been proposed: Brelaz algorithm, simulated annealing (SA), ant colony optimization (ACO). This paper reports empirical results ... Keywords: graph coloring, gravitational swarm

Israel Rebollo-Ruiz; Manuel Graña

2012-03-01T23:59:59.000Z

122

The Approximating Hamiltonian Method for the Imperfect Boson Gas  

E-Print Network (OSTI)

The pressure for the Imperfect (Mean Field) Boson gas can be derived in several ways. The aim of the present note is to provide a new method based on the Approximating Hamiltonian argument which is extremely simple and very general.

Joseph V. Pule; Valentin A. Zagrebnov

2004-05-14T23:59:59.000Z

123

Approximate expressions for polar gap electric field of pulsars  

E-Print Network (OSTI)

We derive easy-to-handle approximations for the polar gap electric field due to inertial frame dragging as derived by Harding & Muslimov 1998. A simple formula valid for polar gap height comparable to the polar cap radius is presented.

J. Dyks; B. Rudak

2000-06-19T23:59:59.000Z

124

Testing and Comparing the Modified Anomalous Diffraction Approximation  

Science Conference Proceedings (OSTI)

The modified anomalous diffraction approximation (MADA) is used to predict absorption and extinction in water and ice clouds, but it does not predict the scattering phase function or asymmetry parameter g. In conjunction with g parameterizations, ...

David L. Mitchell; Anthony J. Baran; W. P. Arnott; C. Schmitt

2006-11-01T23:59:59.000Z

125

Numerical Tests of the Weak Pressure Gradient Approximation  

Science Conference Proceedings (OSTI)

Cloud-resolving simulations of convection over a surface temperature hot spot are used to evaluate the weak pressure gradient (WPG) and weak temperature gradient (WTG) approximations. The premise of the relaxed form of WTG—that vertical velocity ...

David M. Romps

2012-09-01T23:59:59.000Z

126

Approximate translation : media, narrative, and experience in urban design  

E-Print Network (OSTI)

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, ...

Crisman, Jonathan

2013-01-01T23:59:59.000Z

127

Relativistic plasma dispersion functions: Series, integrals, and approximations  

SciTech Connect

A number of results are presented involving the plasma dispersion functions appropriate to waves in weakly relativistic, magnetized, thermal plasmas. These results include generating functions, series, integral forms and interrelations, and several useful approximations.

Robinson, P.A.

1987-05-01T23:59:59.000Z

128

Statistical theory of Langmuir turbulence. [Direct interaction approximation  

SciTech Connect

A statistical theory of Langmuir turbulence is developed by applying a generalization of the direction interaction approximation (DIA) of Kraichnan to the Zakharov equations describing Langmuir turbulence. 7 references.

DuBois, D.F.; Rose, H.A.; Goldman, M.V.

1979-01-01T23:59:59.000Z

129

A Practical Approximation to Optimal Four-Dimensional Objective Analysis  

Science Conference Proceedings (OSTI)

An iterative four-dimensional objective analysis scheme is described. The method is derived by approximating a variational algorithm which should give an optimal four-dimensional analysis The complete set of operationally available observations, ...

Andrew C. Lorenc

1988-03-01T23:59:59.000Z

130

A discrete BGK approximation for strongly degenerate parabolic problems  

E-Print Network (OSTI)

A discrete BGK approximation for strongly degenerate parabolic problems with boundary conditions F strongly degenerate hyperbolic--parabolic equations with initial boundary condition. We prove a priori -- strongly degenerate parabolic equations -- singular perturbation problems -- BGK models 1 Introduction

131

Approximate query answering in unstructured peer-to-peer databases.  

E-Print Network (OSTI)

??Peer-to-peer networks are considered the new generation of distributed databases, termed peer-to-peer databases. With very large size, open architecture, and extreme dynamism and autonomy, approximate… (more)

Banaei-Kashani, Farnoush

2007-01-01T23:59:59.000Z

132

On the Median Volume Diameter Approximation for Droplet Collision Efficiency  

Science Conference Proceedings (OSTI)

In this note, we examine a shortcut for calculating the overall collision efficiency of a droplet spectrum, known as the “median volume diameter” (mvd) approximation. By calculating the overall collision efficiency of a circular cylinder for a ...

Karen J. Finstad; Edward P. Lozowski; Lasse Makkonen

1988-12-01T23:59:59.000Z

133

A Free-Algebraic Solution for the Planar Approximation  

E-Print Network (OSTI)

An explicit solution for the generating functional of n-point functions in the planar approximation is given in terms of two sets of free-algebraic annihilation and creation operators.

O. Haan

2004-08-11T23:59:59.000Z

134

On Safe Tractable Approximations of Chance Constrained Linear ...  

E-Print Network (OSTI)

†Faculty of Industrial Engineering and Management, Technion – Israel Institute of Technology, ... its scenario approximation is the random optimization program min x. { f0(x) : fi(x ..... We generate a training sample of N independent realizations.

135

Approximation algorithms for stochastic scheduling on unrelated machines  

E-Print Network (OSTI)

Motivated by problems in distributed computing, this thesis presents the first nontrivial polynomial time approximation algorithms for an important class of machine scheduling problems. We study the family of preemptive ...

Scott, Jacob (Jacob Healy)

2008-01-01T23:59:59.000Z

136

Linear Baroclinic instability with the Geostrophic Momentum Approximation  

Science Conference Proceedings (OSTI)

The linear Eady model of baroclinic instability with the geostrophic momentum (GM) approximation is solved analytically in physical space and shown to be identical to linear three-dimensional semigeostrophic theory. Both the growth rates and the ...

Peter R. Bannon

1989-02-01T23:59:59.000Z

137

Approximate dynamic programming with applications in multi-agent systems  

E-Print Network (OSTI)

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 ...

Valenti, Mario J. (Mario James), 1976-

2007-01-01T23:59:59.000Z

138

Approximating the traffic grooming problem in tree and star networks  

Science Conference Proceedings (OSTI)

We consider the problem of grooming paths in all-optical networks with tree topology so as to minimize the switching cost, measured by the total number of used ADMs. We first present efficient approximation algorithms with approximation factor of 2ln(@d@?g)+o(ln(@d@?g)) ... Keywords: Add-drop multiplexer (ADM), Optical networks, Traffic grooming, Tree networks, Wavelength division multiplexing (WDM)

Michele Flammini; Gianpiero Monaco; Luca Moscardelli; Mordechai Shalom; Shmuel Zaks

2008-07-01T23:59:59.000Z

139

Indexing methods for approximate dictionary searching: Comparative analysis  

Science Conference Proceedings (OSTI)

The primary goal of this article is to survey state-of-the-art indexing methods for approximate dictionary searching. To improve understanding of the field, we introduce a taxonomy that classifies all methods into direct methods and sequence-based filtering ... Keywords: k-errata tree, q-gram, q-sample, Damerau-Levenshtein distance, Levenshtein distance, NR-grep, agrep, approximate searching, frequency distance, frequency vector trie, metric trees, neighborhood generation, trie

Leonid Boytsov

2011-05-01T23:59:59.000Z

140

The Generalized SIC-OEP formalism and the Generalized SIC-Slater approximation (stationary and time-dependent cases)  

E-Print Network (OSTI)

We present a generalized formulation of the Optimized Effective Potential (OEP) approach to the Self Interaction Correction (SIC) problem in Time Dependent (TD) Density Functional Theory (DFT). The formulation relies on the introduction of a double set of single electron orbitals. It allows the derivation of a generalized Slater approximation to the full OEP formulation, which extends the domain of validity of the standard Slater approximation. We discuss both formal aspects and practical applications of the new formalism and give illustrations in cluster and molecules. The new formalism provides a valuable ansatz to more elaborate (and computationally very demanding) full TD OEP and full TD SIC calculations especially in the linear domain.

Messud, J; Reinhard, P -G; ~Suraud, E

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

The Generalized SIC-OEP formalism and the Generalized SIC-Slater approximation (stationary and time-dependent cases)  

E-Print Network (OSTI)

We present a generalized formulation of the Optimized Effective Potential (OEP) approach to the Self Interaction Correction (SIC) problem in Time Dependent (TD) Density Functional Theory (DFT). The formulation relies on the introduction of a double set of single electron orbitals. It allows the derivation of a generalized Slater approximation to the full OEP formulation, which extends the domain of validity of the standard Slater approximation. We discuss both formal aspects and practical applications of the new formalism and give illustrations in cluster and molecules. The new formalism provides a valuable ansatz to more elaborate (and computationally very demanding) full TD OEP and full TD SIC calculations especially in the linear domain.

J. Messud; P. M. Dinh; P. -G. Reinhard; E. ~Suraud

2010-07-24T23:59:59.000Z

142

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge  

SciTech Connect

Recently, an anomalous evolution of argon metastable density with plasma discharge power (electron density) was reported [A. M. Daltrini, S. A. Moshkalev, T. J. Morgan, R. B. Piejak, and W. G. Graham, Appl. Phys. Lett. 92, 061504 (2008)]. Although the importance of the metastable atom and its density has been reported in a lot of literature, however, a basic physics behind the anomalous evolution of metastable density has not been clearly understood yet. In this study, we investigated a simple global model to elucidate the underlying physics of the anomalous evolution of argon metastable density with the electron density. On the basis of the proposed simple model, we reproduced the anomalous evolution of the metastable density and disclosed the detailed physics for the anomalous result. Drastic changes of dominant mechanisms for the population and depopulation processes of Ar metastable atoms with electron density, which take place even in relatively low electron density regime, is the clue to understand the result.

Park, Min; Chang, Hong-Young [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); You, Shin-Jae; Kim, Jung-Hyung [Center for Vacuum Technology, Korea Research Institute of Standards and Science, Daejeon, 305-306 (Korea, Republic of); Shin, Yong-Hyeon

2011-10-15T23:59:59.000Z

143

Density Coordinate Mixed Layer Models  

Science Conference Proceedings (OSTI)

The development of mixed layer models in so-called density coordinates is discussed. Density coordinates, or isopycnal coordinates as they are sometimes called, are becoming increasingly popular for use in ocean models due to their highly ...

William K. Dewar

2001-02-01T23:59:59.000Z

144

Charge Density Wave Compounds  

NLE Websites -- All DOE Office Websites (Extended Search)

Fisher Research Group Fisher Research Group Layered Chalcogenides 29 February 2008 Controlling the Wave by Brad Plummer, SLAC Communications Stanford University researchers working in part at SSRL have discovered a novel set of properties pertaining to a compound of materials called tritellurides. These compounds, composed of three atoms of tellurium and a single atom of one of the rare earth elements, demonstrate unique electronic properties that can be controlled by altering the temperature of the material. The tritellurides display phenomena known as charge density waves (CDW). In a normal conductive metal, electrons persist in a "sea" wherein they are evenly distributed and equally available, or conductive. A CDW occurs under certain circumstances and causes the electrons to clump together, lowering their availability, and thereby lowering the compound's conductivity. Tellurium, when crystallized into quasi-two-dimensional planes and combined with rare earth elements, produces a material with CDWs that can be manipulated and controlled.

145

Low density microcellular foams  

DOE Patents (OSTI)

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.

LeMay, James D. (Castro Valley, CA)

1992-01-01T23:59:59.000Z

146

Low density microcellular foams  

DOE Patents (OSTI)

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.

LeMay, James D. (Castro Valley, CA)

1991-01-01T23:59:59.000Z

147

ON THE LOCAL DARK MATTER DENSITY  

SciTech Connect

An analysis of the kinematics of 412 stars at 1-4 kpc from the Galactic midplane by Moni Bidin et al. has claimed to derive a local density of dark matter that is an order of magnitude below standard expectations. We show that this result is incorrect and that it arises from the assumption that the mean azimuthal velocity of the stellar tracers is independent of Galactocentric radius at all heights. We substitute the assumption, supported by data, that the circular speed is independent of radius in the midplane. We demonstrate that the assumption of constant mean azimuthal velocity is implausible by showing that it requires the circular velocity to drop more steeply than allowed by any plausible mass model, with or without dark matter, at large heights above the midplane. Using the approximation that the circular-velocity curve is flat in the midplane, we find that the data imply a local dark matter density of 0.008 {+-} 0.003 M{sub Sun} pc{sup -3} = 0.3 {+-} 0.1 GeV cm{sup -3}, fully consistent with standard estimates of this quantity. This is the most robust direct measurement of the local dark matter density to date.

Bovy, Jo; Tremaine, Scott [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)

2012-09-01T23:59:59.000Z

148

The Complexity of Approximating Bounded-Degree Boolean #CSP  

E-Print Network (OSTI)

The degree of a CSP instance is the maximum number of times that a variable may appear in the scope of constraints. We consider the approximate counting problem for Boolean CSPs with bounded-degree instances for constraint languages containing the two unary constant relations {0} and {1}. When the maximum degree is at least 25 we obtain a complete classification of the complexity of this problem. It is exactly solvable in polynomial-time if every relation in the constraint language is affine. It is equivalent to the problem of approximately counting independent sets in bipartite graphs if every relation can be expressed as conjunctions of {0}, {1} and binary implication. Otherwise, there is no FPRAS unless NP=RP. For lower degree bounds, additional cases arise in which the complexity is related to the complexity of approximately counting independent sets in hypergraphs.

Dyer, Martin; Jalsenius, Markus; Richerby, David

2009-01-01T23:59:59.000Z

149

The Monte Carlo Independent Column Approximation Model Intercomparison  

NLE Websites -- All DOE Office Websites (Extended Search)

The Monte Carlo Independent Column Approximation Model Intercomparison The Monte Carlo Independent Column Approximation Model Intercomparison Project (McMIP) Barker, Howard Meteorological Service of Canada Cole, Jason Meteorological Service of Canada Raisanen, Petri Finnish Meteorological Institute Pincus, Robert NOAA-CIRES Climate Diagnostics Center Morcrette, Jean-Jacques European Centre for Medium-Range Weather Forecasts Li, Jiangnan Canadian Center for Climate Modelling Stephens, Graeme Colorado State University Vaillancourt, Paul Environment Canada Oreopoulos, Lazaros JCET/UMBC and NASA/GSFC Siebesma, Pier KNMI Los, Alexander KNMI Clothiaux, Eugene The Pennsylvania State University Randall, David Colorado State University Iacono, Michael Atmospheric & Environmental Research, Inc. Category: Radiation The Monte Carlo Independent Column Approximation (McICA) method for

150

Discrete Variational Calculus for B-spline Approximated Curves  

E-Print Network (OSTI)

We study variational problems for curves approximated by B-spline curves. We show that, one can obtain discrete Euler-Lagrange equations, for the data describing the approximated curves. Our main application is to the curve completion problem in 2D and 3D. In this case, the aim is to find various aesthetically pleasing solutions as opposed to a solution of a physical problem. The Lagrangians of interest are invariant under the special Euclidean group action for which B-spline approximated curves are well suited. Smooth Lagrangians with special Euclidean symmetries involve curvature, torsion, and arc length. Expressions in these, in the original coordinates, are highly complex. We show that, by contrast, relatively simple discrete Lagrangians offer excellent results for the curve completion problem. The methods we develop for the discrete curve completion problem are general and can be used to solve other discrete variational problems for B-spline curves.

Zhao, Jun

2010-01-01T23:59:59.000Z

151

approximately 200 megawatts (MWs) of power from TCEP, making  

NLE Websites -- All DOE Office Websites (Extended Search)

approximately 200 megawatts (MWs) of power from TCEP, making approximately 200 megawatts (MWs) of power from TCEP, making it the first U.S. purchase by a utility of low-carbon power from a commercial-scale, coal-based power plant with carbon capture. The 400-MW TCEP plant is a first-of-its-kind integrated gasification combined cycle (IGCC) poly-generation facility capable of capturing 90 percent of the carbon dioxide (CO 2 ) it produces. The $2.4-billion plant was a third round selection under DOE's Clean Coal Power Initiative

152

Are there approximate relations among transverse momentum dependent distribution functions?  

SciTech Connect

Certain {\\sl exact} relations among transverse momentum dependent parton distribution functions due to QCD equations of motion turn into {\\sl approximate} ones upon the neglect of pure twist-3 terms. On the basis of available data from HERMES we test the practical usefulness of one such ``Wandzura-Wilczek-type approximation'', namely of that connecting $h_{1L}^{\\perp(1)a}(x)$ to $h_L^a(x)$, and discuss how it can be further tested by future CLAS and COMPASS data.

Harutyun AVAKIAN; Anatoli Efremov; Klaus Goeke; Andreas Metz; Peter Schweitzer; Tobias Teckentrup

2007-10-11T23:59:59.000Z

153

On k-jet field approximations of geodesic deviation equations  

E-Print Network (OSTI)

Let M be a smooth manifold and S a spray defined on the convex cone C of the tangent bundle TM. It is proved that the only non-trivial k-jet approximation of the exact geodesic deviation equation of S, linear on the deviation functions and invariant under arbitrary local coordinate transformations corresponds to the Jacobi equation. However, if linearity in the deviation functions is not required, there are differential equations whose solutions admit k-jet approximations and are invariant under arbitrary coordinate transformations. As an example of higher order geodesic deviation equations we study the first and second order jet geodesic deviation equations for a Finsler spray.

Torromé, Ricardo Gallego

2013-01-01T23:59:59.000Z

154

QueryLines: approximate query for visual browsing  

E-Print Network (OSTI)

We introduce approximate query techniques for searching and analyzing two-dimensional data sets such as line or scatter plots. Our techniques allow users to explore a dataset by defining QueryLines: soft constraints and preferences for selecting and sorting a subset of the data. By using both preferences and soft constraints for query composition, we allow greater flexibility and expressiveness than previous visual query systems. When the user over-constrains a query, for example, a system using approximate techniques can display ¨near misses¨to enable users to quickly and continuously refine queries.

Kathy Ryall; Neal Lesh; Hiroaki Miyashita; Shigeru Makino; Tom Lanning; Tom Lanning; Darren Leigh; Darren Leigh

2005-01-01T23:59:59.000Z

155

Properties of derivative expansion approximations to the renormalization group  

E-Print Network (OSTI)

Approximation only by derivative (or more generally momentum) expansions, combined with reparametrization invariance, turns the continuous renormalization group for quantum field theory into a set of partial differential equations which at fixed points become non-linear eigenvalue equations for the anomalous scaling dimension $\\eta$. We review how these equations provide a powerful and robust means of discovering and approximating non-perturbative continuum limits. Gauge fields are briefly discussed. Particular emphasis is placed on the r\\^ole of reparametrization invariance, and the convergence of the derivative expansion is addressed.

Tim R. Morris

1996-10-02T23:59:59.000Z

156

Efficient classical simulation of the approximate quantum Fourier transform  

E-Print Network (OSTI)

We present a method for classically simulating quantum circuits based on the tensor contraction model of Markov and Shi (quant-ph/0511069). Using this method we are able to classically simulate the approximate quantum Fourier transform in polynomial time. Moreover, our approach allows us to formulate a condition for the composability of simulable quantum circuits. We use this condition to show that any circuit composed of a constant number of approximate quantum Fourier transform circuits and log-depth circuits with limited interaction range can also be efficiently simulated.

Nadav Yoran; Anthony J. Short

2006-11-23T23:59:59.000Z

157

Tomographic reconstruction of ionospheric electron density based on constrained algebraic reconstruction technique  

Science Conference Proceedings (OSTI)

A constrained algebraic reconstruction technique (CART) is proposed for the tomographic reconstruction of the ionospheric electron density distribution. The method uses a popular two-dimensional multi-point finite difference approximation of the second ... Keywords: ART, Electron density, Ionospheric tomography, TEC

Debao Wen; Sanzhi Liu; Pingying Tang

2010-09-01T23:59:59.000Z

158

Dynamical density functional theory for dense atomic liquids  

E-Print Network (OSTI)

Starting from Newton's equations of motion, we derive a dynamical density functional theory (DDFT) applicable to atomic liquids. The theory has the feature that it requires as input the Helmholtz free energy functional from equilibrium density functional theory. This means that, given a reliable equilibrium free energy functional, the correct equilibrium fluid density profile is guaranteed. We show that when the isothermal compressibility is small, the DDFT generates the correct value for the speed of sound in a dense liquid. We also interpret the theory as a dynamical equation for a coarse grained fluid density and show that the theory can be used (making further approximations) to derive the standard mode coupling theory that is used to describe the glass transition. The present theory should provide a useful starting point for describing the dynamics of inhomogeneous atomic fluids.

A. J. Archer

2006-04-25T23:59:59.000Z

159

Best Approximation in the Mean by Analytic and Harmonic Functions  

E-Print Network (OSTI)

* *ng the annihilator Ann (Hp) in Lq(T, d`)as Hq0= {f 2 Hq : f(0) = 0}, q = __p__pt-u1rns* * out is organized as follows. In Section 2we prove the exi* *stence of best approximations and characterize them

McCarthy, John E.

160

Choosing an Approximation to the Equation of Radiative Transfer  

Science Conference Proceedings (OSTI)

We examine the accuracy of the PL, approximation to the equation of radiative transfer in the presence of scattering/absorbing clouds of various optical thicknesses. We find that very accurate net fluxes can be obtained with the P1, (two-stream) ...

James A. Fillmore; Alan H. Karp

1980-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Hierarchical Structure for function approximation using radial basis function  

Science Conference Proceedings (OSTI)

The hierarchial network proposed (Multi-RBFNN), is composed of complete Radial Basis Function Neural Networks (RBFNNs) that are in charge of a reduced set of input variables with the property of which every Sub-RBFNN can take charge of a set of input ... Keywords: function approximation, hierarchical architectures, input variable selection, radial bases functions

A. Awad; H. Pomares; I. Rojas; L. J. Herrera; A. Guillen; O. Valenzuela

2005-12-01T23:59:59.000Z

162

Asymptotic Approximations to the Distributed Activation Energy Model  

E-Print Network (OSTI)

Asymptotic Approximations to the Distributed Activation Energy Model M.J.McGuinness1 , E. Donskoi2 by a continuum distribution in activation energy of individual re- actions. An individual reaction is characterised by a pre-exponential coefficient and an activation energy. The distribution, usually Gaussian

McGuinness, Mark

163

Uniqueness and Approximated Computation of Optimal Incomplete Transportation Plans  

E-Print Network (OSTI)

Uniqueness and Approximated Computation of Optimal Incomplete Transportation Plans P. C. ´Alvarez Transportation, where a part of the mass could be not necessarily transported. Since optimal transportation plans consistency result. As a remarkable and unexpected additional result, with important implications for future

Cuesta, Juan Antonio

164

On the Approximability of Reachability Preserving Network Orientations  

E-Print Network (OSTI)

On the Approximability of Reachability Preserving Network Orientations Michael Elberfeld Institute@post.tau.ac.il Abstract We introduce a graph orientation problem arising in the study of biological networks. Given an undirected graph and a list of ordered source-target vertex pairs, the goal is to orient the graph

Sharan, Roded

165

Elastic approximation for a solar parabolic February 29, 2012  

E-Print Network (OSTI)

Elastic approximation for a solar parabolic trough February 29, 2012 Gang Xiao (University of Nice, France) Abstract For the production of the reective surface of a solar parabolic trough concentrator energy solutions. Introduction A parabolic trough [8] is a concentrating solar thermal energy collector

Paris-Sud XI, Université de

166

Matrix Approximation and Projective Clustering via Iterative Sampling  

E-Print Network (OSTI)

We present two new results for the problem of approximating a given real m by n matrix A by a rank-k matrix D, where k < min{m, n}, so as to minimize ||A-D||_F^2. It is known that bysampling O(k/eps) rows of the matrix, ...

Rademacher, Luis

2005-03-29T23:59:59.000Z

167

APPROXIMATE DYNAMIC PROGRAMMING METHODS FOR COOPERATIVE UAV SEARCH  

E-Print Network (OSTI)

APPROXIMATE DYNAMIC PROGRAMMING METHODS FOR COOPERATIVE UAV SEARCH Matthew Flint Emmanuel 01801 matt.flint@baesystems.com Dept. of Electrical and Computer Engineering and Computer Science by the authors of this paper e.g. (Flint et al., 2003b), (Flint et al., 2003a), (Flint et al., 2004); and others

Fernandez, Emmanuel

168

Absorption Approximation with Scattering Effect for Infrared Radiation  

Science Conference Proceedings (OSTI)

A scheme that can handle cloud infrared scattering based on the absorption approximation is developed. In a two-stream mode, the new scheme produces more accurate results than those from the modified two-stream discrete ordinate method. For low ...

J. Li; Qiang Fu

2000-09-01T23:59:59.000Z

169

Weak Bonds from a Semilocal Density Functional with the Right Ingredients  

E-Print Network (OSTI)

Computationally-efficient semilocal approximations of density functional theory at the level of the local spin density approximation (LSDA) or generalized gradient approximation (GGA) poorly describe weak interactions. We show improved descriptions for weak bonds (without loss of accuracy for strong ones) from a newly-developed semilocal meta-GGA (MGGA), by applying it to: 1) the binding energy curve of graphene adsorbed on a Ni (111) surface, where both chemi- and physisorption minima are present; 2) stacking of DNA/RNA nucleobases. We argue that this improvement comes from using the right MGGA dimensionless ingredient to recognize all degrees of orbital overlap.

Sun, Jianwei; Fang, Yuan; Haunschild, Robin; Hao, Pan; Ruzsinszky, Adrienn; Csonka, Gabor I; Scuseria, Gustavo E; Perdew, John P

2013-01-01T23:59:59.000Z

170

Nuclear symmetry potential in the relativistic impulse approximation RID A-2398-2009 RID C-6879-2009  

E-Print Network (OSTI)

Using the relativistic impulse approximation with the Love-Franey NN scattering amplitude developed by Murdock and Horowitz, we investigate the low-energy (100 nuclear symmetry potential in isospin asymmetric nuclear matter. We find that the nuclear symmetry potential at fixed baryon density decreases with increasing nucleon energy. In particular, the nuclear symmetry potential at saturation density changes from positive to negative values at nucleon kinetic energy of about 200 MeV. Furthermore, the obtained energy and density dependence of the nuclear symmetry potential is consistent with those of the isospin- and momentum-dependent MDI interaction with x=0, which has been found to describe reasonably well both the isospin diffusion data from heavy-ion collisions and the empirical neutron-skin thickness of (208)Pb.

Li, Zeng-Hua; Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An; Ma, Hong-Ru.

2006-01-01T23:59:59.000Z

171

Density rise experiment on PLT  

SciTech Connect

The evolution of the density profile in PLT during intense gas puffing is documented and analyzed. Measurements of the spectrum of low energy edge neutrals and of the change in central neutral density indicate that charge-exchange processes alone cannot account for the central density rise. The transient density profile changes can be reproduced numerically by a diffusivity of approx. 10/sup 4/ cm/sup 2//s, and a spatially averaged inward flow of 10/sup 3/ cm/s. These transport coefficients are 10 ..-->.. 10/sup 2/ times larger than neoclassical. The ion energy confinement is reduced, the small scale density fluctuations are increased, and runaway electrons losses are increased during the density rise.

Strachan, J.D.; Bretz, N.; Mazzucato, E.

1982-05-01T23:59:59.000Z

172

3D thermal-aware floorplanner using a MOEA approximation  

Science Conference Proceedings (OSTI)

Two of the major concerns in 3D stacked technology are heat removal and power density distribution. In our work, we propose a novel 3D thermal-aware floorplanner. Our contributions include:1.A novel multi-objective formulation to consider the thermal ... Keywords: 3D architecture, Evolutionary algorithm, Hot spots, Reliability, Temperature, Thermal-aware floorplan, Through silicon vias optimization

David Cuesta; José L. Risco-Martin; José L. Ayala; J. Ignacio Hidalgo

2013-01-01T23:59:59.000Z

173

Study of nuclear matter density distributions using hadronic probes  

Science Conference Proceedings (OSTI)

We briefly review our formula for a proton-nucleus total reaction cross section, {sigma}{sub R}, constructed in the black-sphere approximation of nuclei, in which a nucleus is viewed as a 'black' sphere of radius 'a'. Some years ago, using the Glauber model, one of the authors (A.K.) and his collaborators performed numerical simulations to examine the possibility to probe the nuclear matter density distributions of neutron-rich unstable nuclei from proton elastic scatterings 'model-independently'. The present study is another attempt to seek a 'model-independent' framework for systematically analyzing scattering data for studying the matter density distributions of atomic nuclei.

Kohama, Akihisa [RIKEN Nishina Center, RIKEN, Saitama (Japan); Iida, Kei [Department of Natural Science, Faculty of Science, Kochi University, Kochi (Japan); Oyamatsu, Kazuhiro [Department of Library and Information Science, Faculty of Letters, Aichi Shukutoku University, Aichi (Japan)

2011-05-06T23:59:59.000Z

174

Fine-grained efficient resource allocation using approximated combinatorial auctions: A parallel greedy winner approximation for large-scale problems  

Science Conference Proceedings (OSTI)

Combinatorial auctions, one of the most popular market mechanisms, have a huge effect on electronic markets and political strategies. Combinatorial auctions provide suitable mechanisms for efficient allocation of resources to self-interested attendees. ... Keywords: approximation, combinatorial auction, multi-agent system, optimization, resource allocation

Naoki Fukuta; Takayuki Ito

2009-01-01T23:59:59.000Z

175

Energy Densities for LLNL EMB  

Summary of Projected Power and Energy Density Parameters for the “New Generation” LLNL Electromechanical Batteries R.F. Post June 24, 2013

176

Quantum Calisthenics: Gaussians, The Path Integral and Guided Numerical Approximations  

SciTech Connect

It is apparent to anyone who thinks about it that, to a large degree, the basic concepts of Newtonian physics are quite intuitive, but quantum mechanics is not. My purpose in this talk is to introduce you to a new, much more intuitive way to understand how quantum mechanics works. I begin with an incredibly easy way to derive the time evolution of a Gaussian wave-packet for the case free and harmonic motion without any need to know the eigenstates of the Hamiltonian. This discussion is completely analytic and I will later use it to relate the solution for the behavior of the Gaussian packet to the Feynman path-integral and stationary phase approximation. It will be clear that using the information about the evolution of the Gaussian in this way goes far beyond what the stationary phase approximation tells us. Next, I introduce the concept of the bucket brigade approach to dealing with problems that cannot be handled totally analytically. This approach combines the intuition obtained in the initial discussion, as well as the intuition obtained from the path-integral, with simple numerical tools. My goal is to show that, for any specific process, there is a simple Hilbert space interpretation of the stationary phase approximation. I will then argue that, from the point of view of numerical approximations, the trajectory obtained from my generalization of the stationary phase approximation specifies that subspace of the full Hilbert space that is needed to compute the time evolution of the particular state under the full Hamiltonian. The prescription I will give is totally non-perturbative and we will see, by the grace of Maple animations computed for the case of the anharmonic oscillator Hamiltonian, that this approach allows surprisingly accurate computations to be performed with very little work. I think of this approach to the path-integral as defining what I call a guided numerical approximation scheme. After the discussion of the anharmonic oscillator I will turn to tunneling problems and show that the instanton can also be though of in the same way. I will do this for the classic problem of a double well potential in the extreme limit when the splitting between the two lowest levels is extremely small and the tunneling rate from one well to another is also very small.

Weinstein, Marvin; /SLAC

2009-02-12T23:59:59.000Z

177

Ohmically heated high-density Z pinch  

SciTech Connect

The gross properties of a high-density (n approximately equal to 10$sup 27$ m$sup -3$), small-radius, (r = 10$sup -4$ m) gas-imbedded Z pinch have been examined considering only classical processes. The rate equation using only ohmic heating along with bremsstrahlung and radial heat transport shows that ohmic heating will rapidly take the pinch to thermonuclear temperatures for currents, I, greater than 1 MA. The radial heat loss for the pinch is very small for I greater than 1.5 MA. This suggests that the pinch could tolerate being driven to a nearby wall by an m = 1 kink. The laser technology for initiation of the small-diameter filament and the high-voltage technology for giving a 30-ns rise to a MA or more are available now. Some reactor considerations have been included. (auth)

Hammel, J.E.

1976-01-01T23:59:59.000Z

178

projects are valued at approximately $67 million (including $15 million  

NLE Websites -- All DOE Office Websites (Extended Search)

projects are valued at approximately $67 million (including $15 million projects are valued at approximately $67 million (including $15 million in non-Federal cost sharing) over four years. The overall goal of the research is to develop carbon dioxide (CO 2 ) capture and separation technologies that can achieve at least 90 percent CO 2 removal at no more than a 35 percent increase in the cost of electricity. The projects, managed by FE's National Energy Technology Laboratory (NETL), include: (1) Linde, LLC, which will use a post-combustion capture technology incorporating BASF's novel amine-based process at a 1-megawatt electric (MWe) equivalent slipstream pilot plant at the National Carbon Capture Center (NCCC) (DOE contribution: $15 million); (2) Neumann Systems Group, Inc., which will design, construct, and test a patented NeuStreamTM absorber at the Colorado

179

A Multithreaded Algorithm for Network Alignment Via Approximate Matching  

SciTech Connect

Network alignment is an optimization problem to find the best one-to-one map between the vertices of a pair of graphs that overlaps in as many edges as possible. It is a relaxation of the graph isomorphism problem and is closely related to the subgraph isomorphism problem. The best current approaches are entirely heuristic, and are iterative in nature. They generate real-valued heuristic approximations that must be rounded to find integer solutions. This rounding requires solving a bipartite maximum weight matching problem at each step in order to avoid missing high quality solutions. We investigate substituting a parallel, half-approximation for maximum weight matching instead of an exact computation. Our experiments show that the resulting difference in solution quality is negligible. We demonstrate almost a 20-fold speedup using 40 threads on an 8 processor Intel Xeon E7-8870 system (from 10 minutes to 36 seconds).

Khan, Arif; Gleich, David F.; Pothen, Alex; Halappanavar, Mahantesh

2012-11-16T23:59:59.000Z

180

Product-state Approximations to Quantum Ground States  

E-Print Network (OSTI)

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.

Fernando G. S. L. Brandão; Aram W. Harrow

2013-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Applicability of Boussinesq approximation in a turbulent fluid with constant properties  

E-Print Network (OSTI)

The equations of motion describing buoyant fluids are often simplified using a set of approximations proposed by J. Boussinesq one century ago. To resume, they consist in assuming constant fluid properties, incompressibility and conservation of calories during heat transport. Assuming fulfilment of the first requirement (constant fluid properties), we derive a set of 4 criteria for assessing the validity of the two other requirements in turbulent Rayleigh-B\\'enard convection. The first criterion $\\alpha \\Delta \\ll 1 $ simply results from the incompressibility condition in the thermal boundary layer ($\\alpha$ and $\\Delta$ are the thermal expansion coefficient and the temperature difference driving the flow). The 3 other criteria are proportional or quadratic with the density stratification or, equivalently with the temperature difference resulting from the adiabatic gradient across the cell $\\Delta_{h}$. Numerical evaluations with air, water and cryogenic helium show that most laboratory experiments are free f...

Roche, Philippe-Emmanuel P -E

2007-01-01T23:59:59.000Z

182

Beyond the Quantum Adiabatic Approximation: Adiabatic Perturbation Theory  

E-Print Network (OSTI)

We introduce a perturbative approach to solving the time dependent Schroedinger equation, named adiabatic perturbation theory (APT), whose zeroth order term is the quantum adiabatic approximation. The small parameter in the power series expansion of the time-dependent wave function is the inverse of the time it takes to drive the system's Hamiltonian from the initial to its final form. We review other standard perturbative and non-perturbative ways of going beyond the adiabatic approximation, extending and finding exact relations among them, and also compare the efficiency of those methods against the APT. Most importantly, we determine APT corrections to the Berry phase by use of the Aharonov-Anandan geometric phase. We then solve several time dependent problems allowing us to illustrate that the APT is the only perturbative method that gives the right corrections to the adiabatic approximation. Finally, we propose an experiment to measure the APT corrections to the Berry phase and show, for a particular spin-1/2 problem, that to first order in APT the geometric phase should be two and a half times the (adiabatic) Berry phase.

Gustavo Rigolin; Gerardo Ortiz; Victor Hugo Ponce

2008-07-09T23:59:59.000Z

183

Local Linear Convergence of Approximate Projections onto Regularized Sets  

E-Print Network (OSTI)

The numerical properties of algorithms for finding the intersection of sets depend to some extent on the regularity of the sets, but even more importantly on the regularity of the intersection. The alternating projection algorithm of von Neumann has been shown to converge locally at a linear rate dependent on the regularity modulus of the intersection. In many applications, however, the sets in question come from inexact measurements that are matched to idealized models. It is unlikely that any such problems in applications will enjoy metrically regular intersection, let alone set intersection. We explore a regularization strategy that generates an intersection with the desired regularity properties. The regularization, however, can lead to a significant increase in computational complexity. In a further refinement, we investigate and prove linear convergence of an approximate alternating projection algorithm. The analysis provides a regularization strategy that fits naturally with many ill-posed inverse problems, and a mathematically sound stopping criterion for extrapolated, approximate algorithms. The theory is demonstrated on the phase retrieval problem with experimental data. The conventional early termination applied in practice to unregularized, consistent problems in diffraction imaging can be justified fully in the framework of this analysis providing, for the first time, proof of convergence of alternating approximate projections for finite dimensional, consistent phase retrieval problems.

D. Russell Luke

2011-08-10T23:59:59.000Z

184

Approximate Controllability for Linear Stochastic Differential Equations in Infinite Dimensions  

SciTech Connect

The objective of the paper is to investigate the approximate controllability property of a linear stochastic control system with values in a separable real Hilbert space. In a first step we prove the existence and uniqueness for the solution of the dual linear backward stochastic differential equation. This equation has the particularity that in addition to an unbounded operator acting on the Y-component of the solution there is still another one acting on the Z-component. With the help of this dual equation we then deduce the duality between approximate controllability and observability. Finally, under the assumption that the unbounded operator acting on the state process of the forward equation is an infinitesimal generator of an exponentially stable semigroup, we show that the generalized Hautus test provides a necessary condition for the approximate controllability. The paper generalizes former results by Buckdahn, Quincampoix and Tessitore (Stochastic Partial Differential Equations and Applications, Series of Lecture Notes in Pure and Appl. Math., vol. 245, pp. 253-260, Chapman and Hall, London, 2006) and Goreac (Applied Analysis and Differential Equations, pp. 153-164, World Scientific, Singapore, 2007) from the finite dimensional to the infinite dimensional case.

Goreac, D. [Universite Paris-Est, LAMA, UMR 8050 (France)], E-mail: dan.goreac@univ-mlv.fr

2009-08-15T23:59:59.000Z

185

Density-based logistic regression  

Science Conference Proceedings (OSTI)

This paper introduces a nonlinear logistic regression model for classification. The main idea is to map the data to a feature space based on kernel density estimation. A discriminative model is then learned to optimize the feature weights as well as ... Keywords: density estimation, logistic regression, medical prediction, nonlinear classification

Wenlin Chen, Yixin Chen, Yi Mao, Baolong Guo

2013-08-01T23:59:59.000Z

186

Density Log | Open Energy Information  

Open Energy Info (EERE)

Density Log Density Log Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Density Log Details Activities (6) Areas (6) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Downhole Techniques Exploration Sub Group: Well Log Techniques Parent Exploration Technique: Well Log Techniques Information Provided by Technique Lithology: provides data on the bulk density of the rock surrounding the well Stratigraphic/Structural: Stratigraphic correlation between well bores. Hydrological: Porosity of the formations loggesd can be calculated for the Density log andprovide an indication potential aquifers. Thermal: Cost Information Low-End Estimate (USD): 0.4040 centUSD 4.0e-4 kUSD 4.0e-7 MUSD 4.0e-10 TUSD / foot Median Estimate (USD): 0.6868 centUSD

187

Very Light Jets I. Axisymmetric Parameter Study and Analytic Approximation  

E-Print Network (OSTI)

The propagation of extragalactic jets is studied by a series of twelve axisymmetric hydrodynamic simulations. Motivated by observational constraints, but unlike most previous simulations, the regime of jet to external medium density (eta) from 10^-5 to 10^-2 is explored, for Mach numbers (M) between 2.6 and 26. The computational domain contained the bow shocks for the whole simulation time. The bow shocks are found to be spherical at source sizes below a critical value r1 (blastwave phase), which can reach up to 10 jet radii. [...] The numerical work is complemented by an analytic approach for the spherical phase. Extending previous work, the radial force balance could be integrated for arbitrary background density and energy input, which results in a global solution. The analytic results are shown to be consistent with the numerical work, and a lower limit to r1 can be calculated, which falls below the numerical results by a few jet radii. It is shown explicitely how a King density distribution changes the discussed aspects of the bow shock propagation. Because the jet head propagates very fast in the blastwave phase, it turns out that it is not possible to ``frustrate'' a jet by a high density environment. This is very important for the class of small radio galaxies (compact symmetric objects / GHz peaked sources): They have to be young. During its blastwave phase, a powerful jet can transfer typically 10^60 erg to the environmental gas. This is enough to balance the radiative losses in a cooling flow, if one of the cluster galaxies harbours a powerful jet every Gigayear.

Martin Krause

2002-11-20T23:59:59.000Z

188

Approximating RR Lyrae light curves using cubic polynomials  

E-Print Network (OSTI)

In this paper, we use cubic polynomials to approximate RR Lyrae light curves and apply the method to HST data of RR Lyraes in the halo of M31. We compare our method to the standard method of Fourier decomposition and find that the method of cubic polynomials eliminates virtually all ringing effects and does so with significantly fewer parameters than the Fourier technique. Further, for RRc stars the parameters in the fit are all physical. Our study also reveals a number of additional periodicites in this data not found previously: we find 23 RRc stars, 29 RRab stars and 3 multiperiodic stars.

Reyner, Steven; Ngeow, C; Morgan, C

2010-01-01T23:59:59.000Z

189

Analytical Approximation for 2-D Nonlinear Periodic Deep Water Waves  

E-Print Network (OSTI)

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.

Saleh Tanveer

2013-09-20T23:59:59.000Z

190

Densities and energies of nuclei in dilute matter  

E-Print Network (OSTI)

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.

P. Papakonstantinou; J. Margueron; F. Gulminelli; Ad. R. Raduta

2013-05-01T23:59:59.000Z

191

Calculations of nonspherically averaged charge densities for subtitutionally disordered alloys  

Science Conference Proceedings (OSTI)

Based on screening transformations of muffin-tin orbitals introduced by Andersen et al. [Phys. Rev. Lett. 53, 2571 (1984)], we have developed a formalism for calculating the non-spherically averaged charge densities of substitutionally disordered alloys using the Korringa-Kohn-Rostoker coherent potential approximation (KKR CPA) method in the atomic-sphere approximation (ASA). We have validated our method by calculating charge densities for ordered structures, where we find that our approach yields charge densities that are essentially indistinguishable from the results of full-potential methods. For substitutionally disordered alloys, where full-potential methods have not been implemented so far, our approach can be used to calculate reliable non-spherically averaged charge densities from spherically symmetric one-electron potentials obtained from the KKR-ASA CPA. We report on our study of differences in charge denisty between ordered AlLi in L1{sub o} phase and substitutionally disordered Al{sub 0.5}Li{sub 0.5} on face-centered cubic lattice.

Singh, P.P.; Gonis, A.

1994-02-01T23:59:59.000Z

192

Improved association in a classical density functional theory for water  

E-Print Network (OSTI)

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.

Eric J. Krebs; Jeff B. Schulte; David Roundy

2013-09-07T23:59:59.000Z

193

5-Axis Freeform Surface Milling using Piecewise Ruled Surface Approximation  

E-Print Network (OSTI)

This paper presents a 5-axis side milling scheme for freeform surfaces based on automatic piecewise ruled surface approximation. With this scheme, resulting surface finish is accurate and pleasing, and has a smaller scallop height compared to ball-end milling. The ruled surface approximation can be made arbitrarily precise resulting in an overall fast milling operation that satisfies tight tolerances, and smoother surface finish. The class of surfaces that can take advantage of this type of 5-axis milling operation includes both convex and saddle-like (hyperbolic) shapes. 1 Introduction The automatic toolpath generation for manufacturing of models consisting of freeform surfaces is a difficult problem addressed by numerous researchers [Bob85, Choi89, Choi93, Chou89, Elb93, Elb94, Fers86, Jera91, Lone87, Sait91, Spen90, Zhan86]. 3-axis machining [Bob85, Choi89, Fers86, Jera91, Lone87, Sait91, Spen90, Zhan86] is more frequently used than 4- or 5-axis machining modes. While deri...

Gershon Elber; Russ Fish

2000-01-01T23:59:59.000Z

194

Asymptotic analysis of multiscale approximations to reaction networks  

E-Print Network (OSTI)

A reaction network is a chemical system involving multiple reactions and chemical species. Stochastic models of such networks treat the system as a continuous time Markov chain on the number of molecules of each species with reactions as possible transitions of the chain. In many cases of biological interest some of the chemical species in the network are present in much greater abundance than others and reaction rate constants can vary over several orders of magnitude. We consider approaches to approximation of such models that take the multiscale nature of the system into account. Our primary example is a model of a cell’s viral infection for which we apply a combination of averaging and law of large number arguments to show that the “slow ” component of the model can be approximated by a deterministic equation and to characterize the asymptotic distribution of the “fast ” components. The main goal is to illustrate techniques that can be used to reduce the dimensionality of much more complex models. 1. Stochastic models for reaction networks. A reaction network is a chemical system involving multiple reactions and chemical species. The simplest stochastic model for a network treats the system as a continuous time Markov chain whose state X is a vector giving the number of molecules of each species present with each reaction modeled as a possible transition for the state. The model for the kth reaction is determined by a vector of inputs ?k specifying the number of molecules of each chemical species that are

Karen Ball; Thomas G. Kurtz; Lea Popovic; Greg Rempala

1961-01-01T23:59:59.000Z

195

Complexity and approximability of certain bicriteria location problems  

SciTech Connect

We investigate the complexity and approximability of some location problems when two distance values are specified for each pair of potential sites. These problems involve the selection of a specified number of facilities (i.e. a placement of a specified size) to minimize a function of one distance metric subject to a budget constraint on the other distance metric. Such problems arise in several application areas including statistical clustering, pattern recognition and load-balancing in distributed systems. We show that, in general, obtaining placements that are near-optimal with respect to the first distance metric is NP-hard even when we allow the budget constraint on the second distance metric to be violated by a constant factor. However, when both the distance metrics satisfy the triangle inequality, we present approximation algorithms that produce placements which are near-optimal with respect to the first distance metric while violating the budget constraint only by a small constant factor. We also present polynomial algorithms for these problems when the underlying graph is a tree.

Krumke, S.O.; Noltemeier, H. [Wuerzburg Univ. (Germany); Ravi, S.S. [State Univ. of New York, Albany, NY (United States); Marathe, M.V. [Los Alamos National Lab., NM (United States)

1995-10-01T23:59:59.000Z

196

Nonadiabatic charged spherical evolution in the postquasistatic approximation  

Science Conference Proceedings (OSTI)

We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of dissipative and electrically charged distributions in general relativity. The numerical implementation of our approach leads to a solver which is globally second-order convergent. We evolve nonadiabatic distributions assuming an equation of state that accounts for the anisotropy induced by the electric charge. Dissipation is described by streaming-out or diffusion approximations. We match the interior solution, in noncomoving coordinates, with the Vaidya-Reissner-Nordstroem exterior solution. Two models are considered: (i) a Schwarzschild-like shell in the diffusion limit; and (ii) a Schwarzschild-like interior in the free-streaming limit. These toy models tell us something about the nature of the dissipative and electrically charged collapse. Diffusion stabilizes the gravitational collapse producing a spherical shell whose contraction is halted in a short characteristic hydrodynamic time. The streaming-out radiation provides a more efficient mechanism for emission of energy, redistributing the electric charge on the whole sphere, while the distribution collapses indefinitely with a longer hydrodynamic time scale.

Rosales, L. [Laboratorio de Fisica Computacional, Universidad Experimental Politecnica 'Antonio Jose de Sucre', Puerto Ordaz (Venezuela, Bolivarian Republic of); Barreto, W. [Centro de Fisica Fundamental, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Peralta, C. [Deutscher Wetterdienst, Frankfurter Str. 135, 63067 Offenbach (Germany); School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Rodriguez-Mueller, B. [Computational Science Research Center, College of Sciences, San Diego State University, San Diego, California (United States)

2010-10-15T23:59:59.000Z

197

Low density carbonized composite foams  

DOE Patents (OSTI)

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. 3 figs.

Kong, Fung-Ming.

1989-12-07T23:59:59.000Z

198

Quarkonium at nonzero isospin density  

E-Print Network (OSTI)

We calculate the energies of quarkonium bound states in the presence of a medium of nonzero isospin density using lattice QCD. The medium, created using a canonical (fixed isospin charge) approach, induces a reduction of ...

Detmold, William

199

Approximate Weighted Matching On Emerging Manycore and Multithreaded Architectures  

SciTech Connect

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.

Halappanavar, Mahantesh; Feo, John T.; Villa, Oreste; Tumeo, Antonino; Pothen, Alex

2012-11-30T23:59:59.000Z

200

Finite temperature electronic simulations beyond the Born-Oppenheimer approximation  

E-Print Network (OSTI)

We introduce a general technique to compute finite temperature electronic properties by a novel covariant formulation of the electronic partition function. By using a rigorous variational upper bound to the free energy we are led to the evaluation of a partition function that can be computed stochastically by sampling electronic wave functions and atomic positions (assumed classical). In order to achieve this target we show that it is extremely important to consider the non trivial geometry of the space defined by the wave function ansatz. The method can be extended to any technique capable to provide an energy value over a given wave function ansatz depending on several variational parameters and atomic positions. In particular we can take into account electronic correlation, by using the standard variational quantum Monte Carlo method, that has been so far limited to zero temperature ground state properties. We show that our approximation reduces correctly to the standard Born-Oppenheimer (BO) one at zero t...

Mazzola, Guglielmo; Sorella, Sandro

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Pion - Nucleon Bremsstrahlung beyond the Soft-Photon approximation  

E-Print Network (OSTI)

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.

A. Mariano

2000-04-06T23:59:59.000Z

202

Improved first order mean spherical approximation for simple fluids  

E-Print Network (OSTI)

A perturbation approach based on the first-order mean spherical approximation (FMSA) is proposed. It consists in adopting a hard-sphere plus short-range attractive Yukawa fluid as the novel reference system, over which the perturbative solution of the Ornstein-Zernike equation is performed. A choice of the optimal range of the reference attraction is discussed. The results are compared against conventional FMSA/HS theory and Monte-Carlo simulation data for compressibility factor and vapor-liquid phase diagrams of the medium-ranged Yukawa fluid. Proposed theory keeps the same level of simplicity and transparency, as the conventional FMSA/HS approach does, but shows to be more accurate.

S. Hlushak; A. Trokhymchuk; I. Nezbeda

2012-02-20T23:59:59.000Z

203

ANALYTIC APPROXIMATION OF CARBON CONDENSATION ISSUES IN TYPE II SUPERNOVAE  

SciTech Connect

I present analytic approximations for some issues related to condensation of graphite, TiC, and silicon carbide in oxygen-rich cores of supernovae of Type II. Increased understanding, which mathematical analysis can support, renders researchers more receptive to condensation in O-rich supernova gases. Taking SN 1987A as typical, my first analysis shows why the abundance of CO molecules reaches an early maximum in which free carbon remains more abundant than CO. This analysis clarifies why O-rich gas cannot oxidize C if {sup 56}Co radioactivity is as strong as in SN 1987A. My next analysis shows that the CO abundance could be regarded as being in chemical equilibrium if the CO molecule is given an effective binding energy rather than its laboratory dissociation energy. The effective binding energy makes the thermal dissociation rate of CO equal to its radioactive dissociation rate. This preserves possible relevance for the concept of chemical equilibrium. My next analysis shows that the observed abundances of CO and SiO molecules in SN 1987A rule out frequent suggestions that equilibrium condensation of SUNOCONs has occurred following atomic mixing of the He-burning shell with more central zones in such a way as to reproduce roughly the observed spectrum of isotopes in SUNOCONs while preserving C/O > 1. He atoms admixed along with the excess carbon would destroy CO and SiO molecules, leaving their observed abundances unexplained. The final analysis argues that a chemical quasiequilibrium among grains (but not gas) may exist approximately during condensation, so that its computational use is partially justified as a guide to which mineral phases would be stable against reactions with gas. I illustrate this point with quasiequilibrium calculations by Ebel and Grossman that have shown that graphite is stable even when O/C >1 if prominent molecules are justifiably excluded from the calculation of chemical equilibrium.

Clayton, Donald D., E-mail: claydonald@gmail.com [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States)

2013-01-01T23:59:59.000Z

204

Testing the accuracy of the Hydro-PM approximation in numerical simulations of the Lyman-alpha forest  

E-Print Network (OSTI)

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 la...

Viel, M; Springel, V; Viel, Matteo; Haehnelt, Martin G.; Springel, Volker

2006-01-01T23:59:59.000Z

205

A Parallel Algorithm to Compute the Greatest Common ... - CECM  

E-Print Network (OSTI)

this poster, we present a first multivariate GCD computation algorithm over Z which is based on the Ben-Or/Tiwari interpolation [1]. By using Ben-Or/Tiwari.

206

What Are Your Greatest Energy Concerns for Summer? | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

21, 2009 - 5:00am Addthis We're getting closer to the official start of summer and the weather is heating up. While many people are very happy about this (skiers and snowboarders...

207

Homes show greatest seasonal variation in electricity use ...  

U.S. Energy Information Administration (EIA)

Energy Information Administration ... solar, wind, geothermal, ... as changes in temperature and humidity affect the demand for space heating and cooling.

208

Review: CO(2) Rising: The World's Greatest Environmental Challenge  

E-Print Network (OSTI)

Challenge By Tyler Volk Reviewed by Byron AndersonIllinois University, USA Volk, Tyler. CO 2 Rising: Theor 130 billion tons. Volk cleverly introduces carbon cycling

Anderson, Byron P.

2009-01-01T23:59:59.000Z

209

Computing the Greatest Common Divisor of Multivariate ... - CECM  

E-Print Network (OSTI)

During the interpolation, we also apply Zip- pel's linear space and quadratic time algorithm to solve Vandermonde ma- trices. We use Javadi's approach with a ...

210

Let G be their greatest common divisor (gcd) - CECM  

E-Print Network (OSTI)

the correctness of G ' is established by testing if G ' divides A and B. 3 ..... c o lu m ns w ou ld b e r ep lac ed by a sin gle c o lu m n o f c onst a nts . F o r t ha t ca ...

211

Information technology is our greatest strength and at the ...  

Science Conference Proceedings (OSTI)

... Page 3. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY 5 Unconventional Threats to Security Connectivity Complexity ...

2010-09-28T23:59:59.000Z

212

Question of the Week: What are Your Greatest Energy Concerns...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

thoughts. The cost of fuel oil is so expensive and winter is fast approaching. I have a wood stove to supplement the oil furnace, but the cost of firewood is going up as well. If...

213

Homes show greatest seasonal variation in electricity use - Today ...  

U.S. Energy Information Administration (EIA)

Tools; Glossary › All Reports ... Electricity use varies with the weather, as changes in temperature and humidity affect the demand for space heating and cooling.

214

Oak Ridge Removes Laboratory's Greatest Source of Groundwater...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

soil that surrounded Tank W-1A. The 6,500-pound Tank W-1A is shipped away from ORNL. The 6,500-pound Tank W-1A is shipped away from ORNL. Workers remove the 4,000-gallon...

215

The Greatest Compliment One Can Pay Is, ?You Made a ...  

Science Conference Proceedings (OSTI)

... And if any of you ever has the opportunity to visit, for example, Google, you'll see that the entire complex has been designed around getting people ...

2013-04-30T23:59:59.000Z

216

Question of the Week: What are Your Greatest Energy Concerns...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

by: Allison Casey | September 08, 2008 at 05:18 PM I am concerned with the high cost of heating my home. Heating costs have recently doubled. I believe there should be more...

217

On Euclid's Algorithm and the Computation of Polynomial Greatest ...  

E-Print Network (OSTI)

F C 9[x] are arranged in the order of decreasing exponents, the first term is ..... If the coefficients of F1 and F2 are integers bounded in magnitude by c, then by.

218

LONGITUDINAL OSCILLATIONS IN DENSITY STRATIFIED AND EXPANDING SOLAR WAVEGUIDES  

Science Conference Proceedings (OSTI)

Waves and oscillations can provide vital information about the internal structure of waveguides in which they propagate. Here, we analytically investigate the effects of density and magnetic stratification on linear longitudinal magnetohydrodynamic (MHD) waves. The focus of this paper is to study the eigenmodes of these oscillations. It is our specific aim to understand what happens to these MHD waves generated in flux tubes with non-constant (e.g., expanding or magnetic bottle) cross-sectional area and density variations. The governing equation of the longitudinal mode is derived and solved analytically and numerically. In particular, the limit of the thin flux tube approximation is examined. The general solution describing the slow longitudinal MHD waves in an expanding magnetic flux tube with constant density is found. Longitudinal MHD waves in density stratified loops with constant magnetic field are also analyzed. From analytical solutions, the frequency ratio of the first overtone and fundamental mode is investigated in stratified waveguides. For small expansion, a linear dependence between the frequency ratio and the expansion factor is found. From numerical calculations it was found that the frequency ratio strongly depends on the density profile chosen and, in general, the numerical results are in agreement with the analytical results. The relevance of these results for solar magneto-seismology is discussed.

Luna-Cardozo, M. [Instituto de Astronomia y Fisica del Espacio, CONICET-UBA, CC. 67, Suc. 28, 1428 Buenos Aires (Argentina); Verth, G. [School of Computing, Engineering and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Erdelyi, R., E-mail: mluna@iafe.uba.ar, E-mail: robertus@sheffield.ac.uk, E-mail: gary.verth@northumbria.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2012-04-01T23:59:59.000Z

219

Rock Density | Open Energy Information  

Open Energy Info (EERE)

form form View source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit with form History Facebook icon Twitter icon » Rock Density Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Rock Density Details Activities (2) Areas (2) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Lab Analysis Techniques Exploration Sub Group: Rock Lab Analysis Parent Exploration Technique: Rock Lab Analysis Information Provided by Technique Lithology: Density of different lithologic units. Stratigraphic/Structural: Hydrological: Thermal: Cost Information Low-End Estimate (USD): 10.001,000 centUSD 0.01 kUSD 1.0e-5 MUSD 1.0e-8 TUSD / sample

220

A Sublogarithmic Approximation for Highway and Tollbooth Pricing  

E-Print Network (OSTI)

An instance of the tollbooth problem consists of an undirected network and a collection of single-minded customers, each of which is interested in purchasing a fixed path subject to an individual budget constraint. The objective is to assign a per-unit price to each edge in a way that maximizes the collective revenue obtained from all customers. The revenue generated by any customer is equal to the overall price of the edges in her desired path, when this cost falls within her budget; otherwise, that customer will not purchase any edge. Our main result is a deterministic algorithm for the tollbooth problem on trees whose approximation ratio is O(log m / log log m), where m denotes the number of edges in the underlying graph. This finding improves on the currently best performance guarantees for trees, due to Elbassioni et al. (SAGT '09), as well as for paths (commonly known as the highway problem), due to Balcan and Blum (EC '06). An additional interesting consequence is a computational separation between tol...

Gamzu, Iftah

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

The Framework for Approximate Queries on Simulation Data  

SciTech Connect

AQSim is a system intended to enable scientists to query and analyze a large volume of scientific simulation data. The system uses the state of the art in approximate query processing techniques to build a novel framework for progressive data analysis. These techniques are used to define a multi-resolution index, where each node contains multiple models of the data. The benefits of these models are two-fold: (1) they are compact representations, reconstructing only the information relevant to the analysis, and (2) the variety of models capture different aspects of the data which may be of interest to the user but are not readily apparent in their raw form. To be able to deal with the data interactively, AQSim allows the scientist to make an informed tradeoff between query response accuracy and time. In this paper, we present the framework of AQSim with a focus on its architectural design. We also show the results from an initial proof-of-concept prototype developed at LLNL. The presented framework is generic enough to handle more than just simulation data.

Abdulla, G; Baldwin, C; Critchlow, T; Kamimura, R; Lee, B; Musick, R; Snapp, R; Tang, N

2001-09-27T23:59:59.000Z

222

2008. Approximating learning curves for active-learning-driven annotation  

E-Print Network (OSTI)

Active learning (AL) is getting more and more popular as a methodology to considerably reduce the annotation effort when building training material for statistical learning methods for various NLP tasks. A crucial issue rarely addressed, however, is when to actually stop the annotation process to profit from the savings in efforts. This question is tightly related to estimating the classifier performance after a certain amount of data has already been annotated. While learning curves are the default means to monitor the progress of the annotation process in terms of classifier performance, this requires a labeled gold standard which – in realistic annotation settings, at least – is often unavailable. We here propose a method for committee-based AL to approximate the progression of the learning curve based on the disagreement among the committee members. This method relies on a separate, unlabeled corpus and is thus well suited for situations where a labeled gold standard is not available or would be too expensive to obtain. Considering named entity recognition as a test case we provide empirical evidence that this approach works well under simulation as well as under real-world annotation conditions. 1.

Katrin Tomanek; Udo Hahn

2008-01-01T23:59:59.000Z

223

Controlled Nonlinear Stochastic Delay Equations: Part I: Modeling and Approximations  

SciTech Connect

This two-part paper deals with 'foundational' issues that have not been previously considered in the modeling and numerical optimization of nonlinear stochastic delay systems. There are new classes of models, such as those with nonlinear functions of several controls (such as products), each with is own delay, controlled random Poisson measure driving terms, admissions control with delayed retrials, and others. There are two basic and interconnected themes for these models. The first, dealt with in this part, concerns the definition of admissible control. The classical definition of an admissible control as a nonanticipative relaxed control is inadequate for these models and needs to be extended. This is needed for the convergence proofs of numerical approximations for optimal controls as well as to have a well-defined model. It is shown that the new classes of admissible controls do not enlarge the range of the value functions, is closed (together with the associated paths) under weak convergence, and is approximatable by ordinary controls. The second theme, dealt with in Part II, concerns transportation equation representations, and their role in the development of numerical algorithms with much reduced memory and computational requirements.

Kushner, Harold J., E-mail: hjk@dam.brown.edu [Brown University, Applied Math (United States)

2012-08-15T23:59:59.000Z

224

Asymptotic safety in the f(R) approximation  

E-Print Network (OSTI)

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.

Juergen A. Dietz; Tim R. Morris

2012-11-05T23:59:59.000Z

225

Short-range tensor interaction and high-density nuclear symmetry energy  

E-Print Network (OSTI)

Effects of the short-range tensor interaction on the density-dependence of nuclear symmetry energy are examined by applying an approximate expression for the second-order tensor contribution to the symmetry energy derived earlier by G.E. Brown and R. Machleidt. It is found that the uncertainty in the short-range tensor force leads directly to a divergent high-density behavior of the nuclear symmetry energy.

Li, Ang

2011-01-01T23:59:59.000Z

226

Building a Universal Nuclear Energy Density Functional  

NLE Websites -- All DOE Office Websites (Extended Search)

Building a Universal Nuclear Energy Density Functional Building a Universal Nuclear Energy Density Functional VaryMatrix.png Collaboration with mathematicians and computational...

227

Plasma digital density determining device  

DOE Patents (OSTI)

The density of a decaying plasma in an electrically conducting enclosure is determined by applying an excitation to the cavity formed by the enclosure and counting digitally the number of resonant frequencies traversed by the combination of the cavity and the decaying plasma.

Sprott, Julien C. (Madison, WI); Lovell, Thomas W. (Madison, WI); Holly, Donald J. (Madison, WI)

1976-01-01T23:59:59.000Z

228

A Hierarchy of Approximations of the Master Equation Scaled by a Size Parameter  

Science Conference Proceedings (OSTI)

Solutions of the master equation are approximated using a hierarchy of models based on the solution of ordinary differential equations: the macroscopic equations, the linear noise approximation and the moment equations. The advantage with the approximations ... Keywords: Linear noise approximation, Master equation, Moment equations, Reaction rate equations

Lars Ferm; Per Lötstedt; Andreas Hellander

2008-02-01T23:59:59.000Z

229

Upgrading of biorenewables to high energy density fuels  

DOE Green Energy (OSTI)

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.

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

230

herbicides, burning, and high-density loblolly pine  

DOE Green Energy (OSTI)

Kudzu is an aggressive, nonnative vine that currently dominates an estimated 810,000 ha of mesic forest communities in the eastern United States. To test an integrated method of weed control, abundances of kudzu and other plant species were compared during 4 yr after six herbicide treatments (clopyralid, triclopyr, metsulfuron, picloram 1 2,4-D, tebuthiuron, and a nonsprayed check), in which loblolly pines were planted at three densities (0, 1, and 4 seedlings m22) to induce competition and potentially delay kudzu recovery. This split-plot design was replicated on each of the four kudzu-dominated sites near Aiken, SC. Relative light intensity (RLI) and soil water content (SWC) were measured periodically to identify mechanisms of interference among plant species. Two years after treatment (1999), crown coverage of kudzu averaged , 2% in herbicide plots compared with 93% in the nonsprayed check, and these differences were maintained through 2001, except in clopyralid plots where kudzu cover increased to 15%. In 2001, pine interference was associated with 33, 56, and 67% reductions in biomass of kudzu, blackberry, and herbaceous vegetation, respectively. RLI in kudzu-dominated plots (4 to 15% of full sun) generally was less than half that of herbicide-treated plots. SWC was greatest in tebuthiuron plots, where total vegetation cover averaged 26% compared with 77 to 111% in other plots. None of the treatments eradicated kudzu, but combinations of herbicides and induced pine competition delayed its recovery.

T.B. Harrington; L.T. Rader-Dixon; J.W. Taylor, Jr.

2003-11-01T23:59:59.000Z

231

Definition: Density Log | Open Energy Information  

Open Energy Info (EERE)

Density Log Density Log Jump to: navigation, search Dictionary.png Density Log Density logging is a well logging tool that can provide a continuous record of a formation's bulk density along the length of a borehole. In geology, bulk density is a function of the density of the minerals forming a rock (i.e. matrix) and the fluid enclosed in the pore spaces.[1] View on Wikipedia Wikipedia Definition Density logging is a well logging tool that can provide a continuous record of a formation's bulk density along the length of a borehole. In geology, bulk density is a function of the density of the minerals forming a rock and the fluid enclosed in the pore spaces. This is one of three well logging tools that are commonly used to calculate porosity, the other two being sonic logging and neutron porosity logging

232

Existence of Ground State of an Electron in the BDF Approximation  

E-Print Network (OSTI)

The Bogoliubov-Dirac-Fock (BDF) model allows to describe relativistic elec- trons interacting with the Dirac sea. It can be seen as a mean-field approximation of Quantum Electro-dynamics (QED) where photons are neglected. This paper treats the case of an electron together with the Dirac sea in absence of any external field. Such a system is described by its one-body density matrix, an infinite rank, self-adjoint operator which is a compact pertubation of the negative spectral projector of the free Dirac operator. We prove the existence of minimizers of the BDF-energy under the charge constraint of one electron assuming that the coupling constant {\\alpha} and the quantity L = \\alpha log(\\Lambda) are small where \\Lambda > 0 is the ultraviolet cut-off and chosen very large. We then study the non-relativistic limit of such a system in which the speed of light c tends to infinity (or equivalently \\alpha tends to zero) with L fixed: after rescaling the electronic solution tends to the Choquard-Pekar ground state.

Jérémy Sok

2012-11-16T23:59:59.000Z

233

Skyrme random-phase-approximation description of spin-flip M1 giant resonance  

SciTech Connect

The spin-flip M1 giant resonance is explored in the framework of the random-phase-approximation (RPA) on the basis of the Skyrme energy functional. A representative set of eight Skyrme parametrizations (SkT6, SkM*, SLy6, SG2, SkO, SkO', SkI4, and SV-bas) is used. Light and heavy, spherical and deformed nuclei ({sup 48}Ca, {sup 158}Gd, {sup 208}Pb, and {sup 238}U) are considered. The calculations show that spin densities play a crucial role in forming the collective shift in the spectrum. The interplay of the collective shift and spin-orbit splitting determines the quality of the description. None of the considered Skyrme parametrizations is able to describe simultaneously the M1 strength distribution in closed-shell and open-shell nuclei. It is found that the problem lies in the relative positions of proton and neutron spin-orbit splitting. This calls for a better modeling of the tensor and isovector spin-orbit interaction.

Vesely, P.; Kvasil, J. [Institute of Particle and Nuclear Physics, Charles University, CZ-18000, Praha 8 (Czech Republic); Nesterenko, V. O. [Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, RU-141980 (Russian Federation); Kleinig, W. [Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, RU-141980 (Russian Federation); Technische Universitaet Dresden, Inst. fuer Analysis, D-0106 Dresden (Germany); Reinhard, P.-G. [Institut fuer Theoretische Physik II, Universitaet Erlangen, D-91058 Erlangen (Germany); Ponomarev, V. Yu. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany)

2009-09-15T23:59:59.000Z

234

Density estimation for data with rounding errors  

Science Conference Proceedings (OSTI)

Rounding of data is common in practice. The problem of estimating the underlying density function based on data with rounding errors is addressed. A parametric maximum likelihood estimator and a nonparametric bootstrap kernel density estimator are proposed. ... Keywords: Bootstrapping, Deconvolution density estimation, Fast Fourier transformation, Kernel density estimation, Measurement error

B. Wang, W. Wertelecki

2013-09-01T23:59:59.000Z

235

Explanation of persistent high frequency density structure in coalesced bunches  

SciTech Connect

It has been observed that after the Main Ring rf manipulation of coalescing (where 5 to 13 primary bunches are transferred into a single rf bucket) the new secondary bunch displays evidence of high frequency density structure superimposed on the approximately Gaussian longitudinal bunch length distribution. This structure is persistent over a period of many seconds (hundreds of synchrotron oscillation periods). With the help of multiparticle simulation programs, an explanation of this phenomenon is given in terms of single particle longitudinal phase space dynamics. No coherent effects need be taken into account. 6 refs., 10 figs.

Jackson, Gerald P.

1988-07-01T23:59:59.000Z

236

Effect of electron density profile on power absorption of high frequency electromagnetic waves in plasma  

SciTech Connect

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.

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

237

Probability Densities in Strong Turbulence  

E-Print Network (OSTI)

According to modern developments in turbulence theory, the "dissipation" scales (u.v. cut-offs) $\\eta$ form a random field related to velocity increments $\\delta_{\\eta}u$. In this work we, using Mellin's transform combined with the Gaussain large -scale boundary condition, calculate probability densities (PDFs) of velocity increments $P(\\delta_{r}u,r)$ and the PDF of the dissipation scales $Q(\\eta, Re)$, where $Re$ is the large-scale Reynolds number. The resulting expressions strongly deviate from the Log-normal PDF $P_{L}(\\delta_{r}u,r)$ often quoted in the literature. It is shown that the probability density of the small-scale velocity fluctuations includes information about the large (integral) scale dynamics which is responsible for deviation of $P(\\delta_{r}u,r)$ from $P_{L}(\\delta_{r}u,r)$. A framework for evaluation of the PDFs of various turbulence characteristics involving spatial derivatives is developed. The exact relation, free of spurious Logarithms recently discussed in Frisch et al (J. Fluid Mech. {\\bf 542}, 97 (2005)), for the multifractal probability density of velocity increments, not based on the steepest descent evaluation of the integrals is obtained and the calculated function $D(h)$ is close to experimental data. A novel derivation (Polyakov, 2005), of a well-known result of the multi-fractal theory [Frisch, "Turbulence. {\\it Legacy of A.N.Kolmogorov}", Cambridge University Press, 1995)), based on the concepts described in this paper, is also presented.

Victor Yakhot

2005-12-12T23:59:59.000Z

238

Effective 3-Body Interaction for Mean-Field and Density-Functional Theory  

Science Conference Proceedings (OSTI)

Density functionals for nuclei usually include an effective 3-body interaction that depends on a fractional power of the density. Using insights from the many-body theory of the low-density two-component Fermi gas, we consider a new, nonlocal, form for the energy functional that is consistent with the Fock-space representation of interaction operators. In particular, there is a unique spatially nonlocal generalization of the contact form of the interaction that preserves the {rho}{sup 7/3} density dependence required by the many-body theory. We calculate the ground-state energies for particles in a harmonic trap by using the nonlocal induced 3-body interaction and compare them to numerically accurate Green's function Monte Carlo calculations. Using no free parameters, we find that a nonlocality in the space domain provides a better description of the weak-coupling regime than the local-density approximation.

Gezerlis, Alexandros [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Bertsch, G. F. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1560 (United States)

2010-11-19T23:59:59.000Z

239

Definition: Power density | Open Energy Information  

Open Energy Info (EERE)

density density Jump to: navigation, search Dictionary.png Power density The rate of energy flow (power) per unit volume, area or mass. Common metrics include: horsepower per cubic inch, watts per square meter and watts per kilogram.[1][2] View on Wikipedia Wikipedia Definition Power density (or volume power density or volume specific power) is the amount of power (time rate of energy transfer) per unit volume. In energy transformers like batteries, fuel cells, motors, etc. but also power supply units or similar, power density refers to a volume. It is then also called volume power density which is expressed as W/m. Volume power density is sometimes an important consideration where space is constrained. In reciprocated internal combustion engines, power density- power per swept

240

DENSITY CONTROL IN A REACTOR  

DOE Patents (OSTI)

A reactor is described in which natural-uranium bodies are located in parallel channels which extend through the graphite mass in a regular lattice. The graphite mass has additional channels that are out of the lattice and contain no uranium. These additional channels decrease in number per unit volume of graphite from the center of the reactor to the exterior and have the effect of reducing the density of the graphite more at the center than at the exterior, thereby spreading neutron activity throughout the reactor. (AEC)

Marshall, J. Jr.

1961-10-24T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Comparison of Daily Averaged Reflection, Transmission, and Absorption for Selected Radiative Flux Transfer Approximations  

Science Conference Proceedings (OSTI)

This paper compares accuracy for the daily averaged reflection, transmission, and absorption of solar flux derived from the delta-four-stream approximation and a few selected two-stream approximations. In the chosen variety of two-stream ...

Xun Zhu; Albert Arking

1994-12-01T23:59:59.000Z

242

Numerical Approximations Can Create Chaos-related Errors in Blocking Forecasts  

Science Conference Proceedings (OSTI)

The chaotic structure of two-dimensional atmospheric flow is illustrated. It is shown that certain errors in numerical approximations can Prevent the correct prediction of chaotic processes. This is the case when the numerical approximations do ...

Juhani Rinne; Heikki Järvinen

1992-05-01T23:59:59.000Z

243

CLUSTER-VARIATION METHOD FOR THE TRIANGULAR LATTICE GAS II. TRIANGLE APPROXIMATION  

E-Print Network (OSTI)

with the zero~field lattice gas can be identified IsingFOR THE TRIANGULAR LATTICE GAS II. TRIANGLE APPROXIMATION R.method for the triangular lattice gas Triangle approximation

Osorio, R.

2013-01-01T23:59:59.000Z

244

Phase diagram of amorphous solid water: Low-density, high-density, and very-high-density amorphous ices  

E-Print Network (OSTI)

for the understanding of the transformation between the different amorphous ices and the two hypothesized phasesPhase diagram of amorphous solid water: Low-density, high-density, and very-high-density amorphous ices Nicolas Giovambattista,1,2 H. Eugene Stanley,2 and Francesco Sciortino3 1 Department of Chemical

Sciortino, Francesco

245

Laboratory testing of high energy density capacitors for electric vehicles  

DOE Green Energy (OSTI)

Laboratory tests of advanced, high energy density capacitors in the Battery Test Laboratory of the Idaho National Engineering Laboratory have been performed to investigate their suitability for load-leveling the battery in an electric vehicle. Two types of devices were tested -- 3 V, 70 Farad, spiral wound, carbon-based, single cell devices and 20 V, 3. 5 Farad, mixed-oxide, multi-cell bipolar devices. The energy density of the devices, based on energy stored during charge to the rated voltage, was found to be 1--2 Wh/kg, which agreed well with that claimed by the manufacturers. Constant power discharge tests were performed at power densities up to 1500 W/kg. Discharges at higher power densities could have been performed had equipment been available to maintain constant power during discharges of less than one second. It was found that the capacitance of the devices were rate dependent with the rate dependency of the carbon-based devices being higher than that of the mixed-oxide devices. The resistance of both types of devices were relatively low being 20--30 milliohms. Testing done in the study showed that the advanced high energy density capacitors can be charged and discharged over cycles (PSFUDS) which approximate the duty cycle that would be encountered if the devices are used to load-level the battery in an electric vehicle. Thermal tests of the advanced capacitors in an insulated environment using the PSFUDS cycle showed the devices do not overheat with their temperatures increasing only 4--5{degrees}C for tests that lasted 5--7 hours. 7 refs., 33 figs., 11 tabs.

Burke, A.F.

1991-10-01T23:59:59.000Z

246

Risk Bounds for Mixture Density Estimation  

E-Print Network (OSTI)

In this paper we focus on the problem of estimating a bounded density using a finite combination of densities from a given class. We consider the Maximum Likelihood Procedure (MLE) and the greedy procedure described by ...

Rakhlin, Alexander

2004-01-27T23:59:59.000Z

247

Oxides having high energy densities  

DOE Patents (OSTI)

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.

Ceder, Gerbrand; Kang, Kisuk

2013-09-10T23:59:59.000Z

248

Bivariate density estimation using BV regularisation  

Science Conference Proceedings (OSTI)

The problem of bivariate density estimation is studied with the aim of finding the density function with the smallest number of local extreme values which is adequate with the given data. Adequacy is defined via Kuiper metrics. The concept of the taut-string ... Keywords: Density estimation, Modality, Regularisation

Andreas Obereder; Otmar Scherzer; Arne Kovac

2007-08-01T23:59:59.000Z

249

Testing the accuracy of the Hydro-PM approximation in numerical simulations of the Lyman-alpha forest  

E-Print Network (OSTI)

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.

Matteo Viel; Martin G. Haehnelt; Volker Springel

2005-04-28T23:59:59.000Z

250

Troubleshooting time-dependent density-functional theory for photochemical applications: Oxirane  

Science Conference Proceedings (OSTI)

The development of analytic-gradient methodology for excited states within conventional time-dependent density-functional theory (TDDFT) would seem to offer a relatively inexpensive alternative to better established quantum-chemical approaches for the modeling of photochemical reactions. However, even though TDDFT is formally exact, practical calculations involve the use of approximate functional, in particular the TDDFT adiabatic approximation, the use of which in photochemical applications must be further validated. Here, we investigate the prototypical case of the symmetric CC ring opening of oxirane. We demonstrate by direct comparison with the results of high-quality quantum Monte Carlo calculations that, far from being an approximation on TDDFT, the Tamm-Dancoff approximation is a practical necessity for avoiding triplet instabilities and singlet near instabilities, thus helping maintain energetically reasonable excited-state potential energy surfaces during bond breaking. Other difficulties one would encounter in modeling oxirane photodynamics are pointed out.

Cordova, Felipe; Doriol, L. Joubert; Ipatov, Andrei; Casida, Mark E.; Filippi, Claudia; Vela, Alberto [Laboratoire de Chimie Theorique, Departement de Chimie Molecularie (DCM, UMR CNRS/UJF 5250), Institut de Chimie Moleculaire de Grenoble (ICMG, FR2607), Universite Joseph Fourier - Grenoble I, 301 rue de la Chimie, BP 53, F-38041 Grenoble Cedex 9 (France); Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, Leiden NL-2333 CA Netherlands (Netherlands); Departamento de Quimica, Cinvestav, Avenida Instituto Politecnico Nacional 2508, A.P. 14-740, Mexico D.F. 07000 (Mexico)

2007-10-28T23:59:59.000Z

251

Transport Energy Use and Population Density  

NLE Websites -- All DOE Office Websites (Extended Search)

Transport Energy Use and Population Density Transport Energy Use and Population Density Speaker(s): Masayoshi Tanishita Date: July 1, 2004 - 10:00pm Location: Bldg. 90 Seminar Host/Point of Contact: Jonathan Sinton After Peter Newman and Jeffrey Kenworthy published "Cities and Automobile Dependence" in 1989, population density was brought to public attention as an important factor to explain transport mobility and energy use. However, several related issues still remain open: Is an increase in population density more effective than rising gas prices in reducing transport energy use? How much does per capita transport energy use change as population density in cities changes? And what kind of factors influence changes in population density? In this presentation, using city-level data in the US, Japan and other countries, the population-density elasticity of

252

Effects of Disorder in Mg1?xTaxB2 Alloys using Coherent-Potential Approximation  

E-Print Network (OSTI)

Using Korringa-Kohn-Rostoker coherent-potential approximation in the atomicsphere approximation (KKR-ASA CPA) method for taking into account the effects of disorder, Gaspari-Gyorffy formalism for calculating the electron-phonon coupling constant ?, and Allen-Dynes equation for calculating Tc, we have studied the variation of Tc in Mg1?xTaxB2 alloys as a function of Ta concentration. Our results show that the Tc decreases with the addition of Ta for upto 40at % and remains essentially zero from 60at % to 80at % of Ta. We also find TaB2 to be superconducting, albeit at a lower temperature. Our analysis shows that the variation in Tc in Mg1?xTaxB2 is mostly dictated by the changes in the B p density of states with the addition of Ta.. The experimental [1–3] and theoretical [4] efforts aimed at understanding the nature of superconductivity in MgB2 have made substantial progress since the discovery of superconductivity in it [1]. With an enhanced understanding of superconductivity in MgB2, attempts are now being made to understand

P. Jiji; Thomas Joseph; Prabhakar P. Singh

2002-01-01T23:59:59.000Z

253

Extension of the weak-line approximation and application to correlated-k methods  

Science Conference Proceedings (OSTI)

Global climate models require accurate and rapid computation of the radiative transfer through the atmosphere. Correlated-k methods are often used. One of the approximations used in correlated-k models is the weakline approximation. We introduce an approximation T/sub g/ which reduces to the weak-line limit when optical depths are small, and captures the deviation from the weak-line limit as the extinction deviates from the weak-line limit. This approximation is constructed to match the first two moments of the gamma distribution to the k-distribution of the transmission. We compare the errors of the weak-line approximation with T/sub g/ in the context of a water vapor spectrum. The extension T/sub g/ is more accurate and converges more rapidly than the weak-line approximation.

Conley, A.J.; Collins, W.D.

2011-03-15T23:59:59.000Z

254

Table A6. Approximate Heat Rates for Electricity, and Heat Content ...  

U.S. Energy Information Administration (EIA)

State energy information, detailed and overviews. Maps. ... Table A6. Approximate Heat Rates for Electricity, and Heat Content of Electricity, 1949-2011

255

High Density Fuel Development for Research Reactors  

SciTech Connect

An international effort to develop, qualify, and license high and very high density fuels has been underway for several years within the framework of multi-national RERTR programs. The current development status is the result of significant contributions from many laboratories, specifically CNEA in Argentina, AECL in Canada, CEA in France, TUM in Germany, KAERI in Korea, VNIIM, RDIPE, IPPE, NCCP and RIARR in Russia, INL, ANL and Y-12 in USA. These programs are mainly engaged with UMo dispersion fuels with densities from 6 to 8 gU/cm3 (high density fuel) and UMo monolithic fuel with density as high as 16 gU/cm3 (very high density fuel). This paper, mainly focused on the French & US programs, gives the status of high density UMo fuel development and perspectives on their qualification.

Daniel Wachs; Dennis Keiser; Mitchell Meyer; Douglas Burkes; Curtis Clark; Glenn Moore; Jan-Fong Jue; Totju Totev; Gerard Hofman; Tom Wiencek; Yeon So Kim; Jim Snelgrove

2007-09-01T23:59:59.000Z

256

The Quantum Energy Density: Improved E  

Science Conference Proceedings (OSTI)

We establish a physically meaningful representation of a quantum energy density for use in Quantum Monte Carlo calculations. The energy density operator, dened in terms of Hamiltonian components and density operators, returns the correct Hamiltonian when integrated over a volume containing a cluster of particles. This property is demonstrated for a helium-neon \\gas," showing that atomic energies obtained from the energy density correspond to eigenvalues of isolated systems. The formation energies of defects or interfaces are typically calculated as total energy dierences. Using a model of delta-doped silicon (where dopant atoms form a thin plane) we show how interfacial energies can be calculated more eciently with the energy density, since the region of interest is small. We also demonstrate how the energy density correctly transitions to the bulk limit away from the interface where the correct energy is obtainable from a separate total energy calculation.

Krogel, Jaron [University of Illinois, Urbana-Champaign; Yu, Min [Lawrence Berkeley National Laboratory (LBNL); Kim, Jeongnim [ORNL; Ceperley, David M. [University of Illinois, Urbana-Champaign

2013-01-01T23:59:59.000Z

257

Relationship between swelling and irradiation creep in cold-worked PCA stainless steel irradiated to {approximately}178 dpa at {approximately}400{degrees}C  

Science Conference Proceedings (OSTI)

The eighth and final irradiation segment for pressurized tubes constructed from the fusion Prime Candidate Alloy (PCA) has been completed in FFTF. At 178 dpa and {approximately}400{degrees}C, the irradiation creep of 20% cold-worked PCA has become dominated by the {open_quotes}creep disappearance{close_quotes} phenomenon. The total diametral deformation rate has reached the limiting value of 0.33%/dpa at the three highest stress levels employed in this test. The stress-enhancement of swelling tends to camouflage the onset of creep disappearance, however, requiring the use of several non-traditional techniques to extract the creep coefficients. No failures occurred in these tubes, even though the swelling ranged from {approximately}20 to {approximately}40%.

Toloczko, M.B. [Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical and Nuclear Engineering; Garner, F.A. [Pacific Northwest Lab., Richland, WA (United States)

1993-09-01T23:59:59.000Z

258

Low complexity channel models for approximating flat Rayleigh fading in network simulations  

E-Print Network (OSTI)

The intricate dependency of networking protocols upon the performance of the wireless channel motivates the investigation of network channel approximations for fading channels. Wireless networking protocols are increasingly being designed and evaluated with the assistance of networking simulators. While evaluating networking protocols such as medium access control, routing, and reliable transport, the network channel model, and its associated capacity, will drastically impact the achievable network throughput. Researcher relying upon simulation results must therefore use extreme caution to ensure the use of similar channel models when performing protocol comparisons. Some channel approximations have been created to mimic the behavior of a fading environment, however there exists little to no justification for these channel approximations. This dissertation addresses the need for a computationally efficient fading channel approximation for use in network simulations. A rigorous flat fading channel model was developed for use in accuracy measurements of channel approximations. The popular two-state Markov model channel approximation is analyzed and shown to perform poorly for low to moderate signal-to-noise ratios (SNR). Three novel channel approximations are derived, with multiple methods of parameter estimation. Each model is analyzed for both statistical performance and network performance. The final model is shown to achieve very accurate network throughput performance by achieving a very close matching of the frame run distributions. This work provides a rigorous evaluation of the popular two-state Markov model, and three novel low complexity channel models in both statistical accuracy and network throughput performance. The novel models are formed through attempts to match key statistical parameters of frame error run and good frame run statistics. It is shown that only matching key parameters is insufficient to achieve an acceptable channel approximation and that it is necessary to approximate the distribution of frame error duration and good frame run duration. The final novel channel approximation, the three-state run-length model, is shown to achieve a good approximation of the desired distributions when some key statistical parameters are matched.

McDougall, Jeffrey Michael

2003-08-01T23:59:59.000Z

259

Considering Air Density in Wind Power Production  

E-Print Network (OSTI)

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.

Zénó Farkas

2011-03-11T23:59:59.000Z

260

Colle-Salvetti-type local density functional for the exchange-correlation energy in two dimensions  

Science Conference Proceedings (OSTI)

We derive an approximate local density functional for the exchange-correlation energy to be used in density-functional calculations of two-dimensional systems. In the derivation we employ the Colle-Salvetti wave function within the scheme of Salvetti and Montagnani [Phys. Rev. A 63, 052109 (2001)] to satisfy the sum rule for the exchange-correlation hole. We apply the functional to the two-dimensional homogeneous electron gas as well as to a set of quantum dots and find a very good agreement with exact reference data.

Sakiroglu, S. [Nanoscience Center, Department of Physics, University of Jyvaeskylae, P. O. Box 35, FI-40014 Jyvaeskylae (Finland); Physics Department, Faculty of Arts and Sciences, Dokuz Eyluel University, 35160 Izmir (Turkey); Raesaenen, E. [Nanoscience Center, Department of Physics, University of Jyvaeskylae, P. O. Box 35, FI-40014 Jyvaeskylae (Finland)

2010-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Dynamic Evolution for Risk-Neutral Densities  

E-Print Network (OSTI)

We solved the scaled formulation for problems (7) and (10) and obtained the dynamic evolution for the densities (see Figure 1). For this data set, we.

262

Some challenges for Nuclear Density Functional Theory  

E-Print Network (OSTI)

We discuss some of the challenges that the DFT community faces in its quest for the truly universal energy density functional applicable over the entire nuclear chart.

T. Duguet; K. Bennaceur; T. Lesinski; J. Meyer

2006-06-20T23:59:59.000Z

263

Application of Precession Electron Diffraction in Density ...  

Science Conference Proceedings (OSTI)

In this paper, GND density calculations obtained using SEM-based EBSD and transmission electron microscope-based PED techniques in ?+? titanium alloys ...

264

MECHANICALLY ROBUST, ELECTRICALLY CONDUCTIVE ULTRALOW-DENSITY ...  

A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an ...

265

Betatron radiation from density tailored plasmas  

E-Print Network (OSTI)

Betatron radiation from density tailored plasmas K. Tathe resulting betatron radiation spectrum can therefore bepro?le, the betatron radiation emitted by theses electrons

Ta Phuoc, Kim

2010-01-01T23:59:59.000Z

266

3-D capacitance density imaging system  

DOE Patents (OSTI)

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.

Fasching, G.E.

1988-03-18T23:59:59.000Z

267

High Energy Density Secondary Lithium Batteries  

High Energy Density Secondary Lithium Batteries Note: The technology described above is an early stage opportunity. Licensing rights to this intellectual property may

268

An accurate approximation to the average error probability of cooperative diversity in Nakagami-m fading  

Science Conference Proceedings (OSTI)

A new approximation to the average symbol error rate of cooperative diversity is derived for independent and non-identically distributed Nakagami-m fading channels. The new approximation has the same computational complexity as previous lower bounds ... Keywords: Nakagami, cooperative diversity, fading channels, symbol error rate

Norman C. Beaulieu; Yunfei Chen

2010-09-01T23:59:59.000Z

269

On spectral approximation of static and dynamical problems for elastic multistructures  

Science Conference Proceedings (OSTI)

The present paper is devoted to the construction and investigation of algorithms of spectral approximation of three-dimensional problems for nonhomogeneous anisotropic elastic multistructures in curvilinear coordinates, which are junctions of three-dimensional ... Keywords: elastic multistructures, error bounds, spectral approximation

Gia Avalishvili; Mariam Avalishvili

2009-06-01T23:59:59.000Z

270

Optimal approximations for risk measures of sums of lognormals based on conditional expectations  

Science Conference Proceedings (OSTI)

In this paper we investigate the approximations for the distribution function of a sum S of lognormal random variables. These approximations are obtained by considering the conditional expectation E[S|@L] of S with respect to a conditioning random variable ... Keywords: Comonotonicity, Conditional expectation, Jensen's inequality, Lognormal, Maximal variance

S. Vanduffel; X. Chen; J. Dhaene; M. Goovaerts; L. Henrard; R. Kaas

2008-11-01T23:59:59.000Z

271

Shock-compressible-vortex interactions: Computing approximate post-shock fields  

E-Print Network (OSTI)

Shock-compressible-vortex interactions: Computing approximate post-shock fields G.K. O'Reilly and D of the passage of a planar shock through a steady compressible vortex is developed. To compute the approximate post-shock fields, the steady pre-shock vortex is decomposed into a sum of frozen sinusoidal modes

Barr, Al

272

Certified Approximation of Parametric Space Curves with Cubic B-spline Curves  

E-Print Network (OSTI)

Approximating complex curves with simple parametric curves is widely used in CAGD, CG, and CNC. This paper presents an algorithm to compute a certified approximation to a given parametric space curve with cubic B-spline curves. By certified, we mean that the approximation can approximate the given curve to any given precision and preserve the geometric features of the given curve such as the topology, singular points, etc. The approximated curve is divided into segments called quasi-cubic B\\'{e}zier curve segments which have properties similar to a cubic rational B\\'{e}zier curve. And the approximate curve is naturally constructed as the associated cubic rational B\\'{e}zier curve of the control tetrahedron of a quasi-cubic curve. A novel optimization method is proposed to select proper weights in the cubic rational B\\'{e}zier curve to approximate the given curve. The error of the approximation is controlled by the size of its tetrahedron, which converges to zero by subdividing the curve segments. As an applic...

Shen, Liyong; Gao, Xiao-Shan

2012-01-01T23:59:59.000Z

273

A scaling approximation for structure factors in the integral equation theory of polydisperse nonionic colloidal fluids  

E-Print Network (OSTI)

Integral equation of pure liquids, combined with a new "scaling approximation" based on a corresponding states treatment of pair correlation functions, is used to evaluate approximate structure factors for colloidal fluids constituted of uncharged particles with polydispersity in size and energy parameters. Both hard spheres and Lennard-Jones interactions are considered. For polydisperse hard spheres, the scaling approximation is compared to theories utilized by small angle scattering experimentalists (decoupling approximation, local monodisperse approximation)and to the van der Waals one-fluid theory. The results are tested against predictions from analytical expressions, exact within the Percus-Yevick approximation. For polydisperse Lennard-Jones particles, the scaling approximation combined with a "modified hypernetted chain" integral equation, is tested against molecular dynamics data generated for the present work. Despite ist simplicity, the scaling approximation exhibits a satisfactory performance for both potentials and represents a considerable improvement over the above mentioned theories. Shortcomings of the proposed theory, its applicability to the analysis of experimental scattering data, and its possible extensions to different potentials are finally discussed.

Domenico Gazzillo; Achille Giacometti; Raffaele G. Della Valle; Elisabetta Venuti; Flavio Carsughi

1999-07-23T23:59:59.000Z

274

Hardness of approximation and integer programming frameworks for searching for caterpillar trees  

Science Conference Proceedings (OSTI)

We consider the problems of finding a caterpillar tree in a graph. We first prove that, unless P=NP, there is no approximation algorithms for finding a minimum spanning caterpillar in a graph within a factor of f(n); where f(n) ... Keywords: approximation algorithm, caterpillar trees, integer programming, optimization, semidefinite programming

Micheal J. Dinneen, Masoud Khosravani

2011-01-01T23:59:59.000Z

275

Density gradient free electron collisionally excited x-ray laser  

DOE Patents (OSTI)

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.

Campbell, E.M.; Rosen, M.D.

1984-11-29T23:59:59.000Z

276

Ballistics considerations for small-caliber, low-density projectiles  

SciTech Connect

One major application for single- and two-stage light gas guns is for fueling magnetic fusion confinement devices. Powder guns are not a feasible alternative due to possible plasma contamination by residual powder gases and the eventual requirement of steady-state operation at {approximately} 1 Hz, which will dictate a closed gas handling system where propellant gases are recovered, processed and recompressed. Interior ballistic calculations for single-stage light gas guns, both analytical and numerical, are compared to an extensive data base for low density hydrogenic projectiles (pellets). Some innovative range diagnostics are described for determining the size and velocity of these small (several mm) size projectiles. A conceptual design of a closed cycle propellant gas system is presented including tradeoffs between different light propellant gases.

Gouge, M.J.; Baylor, L.R.; Combs, S.K.; Fisher, P.W.; Foster, C.A.; Foust, C.R.; Milora, S.L.; Qualls, A.L.

1993-11-01T23:59:59.000Z

277

Dynamical eigenfunctions and critical density in loop quantum cosmology  

E-Print Network (OSTI)

We offer a new, physically transparent argument for the existence of the critical, universal maximum matter density in loop quantum cosmology for the case of a flat Friedmann-Lemaitre-Robertson-Walker cosmology with scalar matter. The argument is based on the existence of a sharp exponential ultraviolet cutoff in momentum space on the eigenfunctions of the quantum cosmological dynamical evolution operator (the gravitational part of the Hamiltonian constraint), attributable to the fundamental discreteness of spatial volume in loop quantum cosmology. The existence of the cutoff is proved directly from recently found exact solutions for the eigenfunctions for this model. As a consequence, the operators corresponding to the momentum of the scalar field and the spatial volume approximately commute. The ultraviolet cutoff then implies that the scalar momentum, though not a bounded operator, is in effect bounded on subspaces of constant volume, leading to the upper bound on the expectation value of the matter densit...

Craig, David A

2012-01-01T23:59:59.000Z

278

Density and Tensile Properties Changed by Aging Plutonium  

Science Conference Proceedings (OSTI)

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.

Chung, B W; Choi, B W; Thompson, S R; Woods, C H; Hopkins, D J; Ebbinghaus, B B

2005-03-14T23:59:59.000Z

279

Approximate deconvolution large eddy simulation of a barotropic ocean circulation model  

E-Print Network (OSTI)

This paper puts forth a new large eddy simulation closure modeling strategy for two-dimensional turbulent geophysical flows. This closure modeling approach utilizes approximate deconvolution, which is based solely on mathematical approximations and does not employ phenomenological arguments, such as the concept of an energy cascade. The new approximate deconvolution model is tested in the numerical simulation of the wind-driven circulation in a shallow ocean basin, a standard prototype of more realistic ocean dynamics. The model employs the barotropic vorticity equation driven by a symmetric double-gyre wind forcing, which yields a four-gyre circulation in the time mean. The approximate deconvolution model yields the correct four-gyre circulation structure predicted by a direct numerical simulation, on a much coarser mesh but at a fraction of the computational cost. This first step in the numerical assessment of the new model shows that approximate deconvolution could represent a viable alternative to standar...

San, Omer; Wang, Zhu; Iliescu, Traian

2011-01-01T23:59:59.000Z

280

Approximate treatment of electron Coulomb distortion in quasielastic (e,e') reactions  

E-Print Network (OSTI)

In this paper we address the adequacy of various approximate methods of including Coulomb distortion effects in (e,e') reactions by comparing to an exact treatment using Dirac-Coulomb distorted waves. In particular, we examine approximate methods and analyses of (e,e') reactions developed by Traini et al. using a high energy approximation of the distorted waves and phase shifts due to Lenz and Rosenfelder. This approximation has been used in the separation of longitudinal and transverse structure functions in a number of (e,e') experiments including the newly published 208Pb(e,e') data from Saclay. We find that the assumptions used by Traini and others are not valid for typical (e,e') experiments on medium and heavy nuclei, and hence the extracted structure functions based on this formalism are not reliable. We describe an improved approximation which is also based on the high energy approximation of Lenz and Rosenfelder and the analyses of Knoll and compare our results to the Saclay data. At each step of our analyses we compare our approximate results to the exact distorted wave results and can therefore quantify the errors made by our approximations. We find that for light nuclei, we can get an excellent treatment of Coulomb distortion effects on (e,e') reactions just by using a good approximation to the distorted waves, but for medium and heavy nuclei simple additional ad hoc factors need to be included. We describe an explicit procedure for using our approximate analyses to extract so-called longitudinal and transverse structure functions from (e,e') reactions in the quasielastic region.

K. S. Kim; L. E. Wright; Yanhe Jin; D. W. Kosik

2005-03-30T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

High density laser-driven target  

DOE Patents (OSTI)

A high density target for implosion by laser energy composed of a central quantity of fuel surrounded by a high-Z pusher shell with a low-Z ablator-pusher shell spaced therefrom forming a region filled with low-density material.

Lindl, John D. (San Ramon, CA)

1981-01-01T23:59:59.000Z

282

Laser light absorption with density profile modifications  

SciTech Connect

Two-dimensional computer simulations studied plasma heating by electron plasma waves. The results emphasize the importance of nonlinear steepening of the density profile near the critical density. A typical simulation result is presented in order to illustrate these profile modifications. It is shown that large dc magnetic field generation is an inherent property of the absorption of obliquely-incident light. (MOW)

Kruer, W.; Valeo, E.; Estabrook, K.; Langdon, B.; Lasinski, B.

1974-12-01T23:59:59.000Z

283

Estimate of dielectric density using spectroscopic ellipsometry  

Science Conference Proceedings (OSTI)

The optical dielectric functions for hafnium oxide and hafnium silicate films were extracted from spectroscopic ellipsometry measurements and the density then calculated using a previously proposed method. The values obtained were then compared to those ... Keywords: Density, Gadolinium oxide, Hafnium silicate, Medium energy ion scattering, Spectroscopic ellipsometry, X-ray reflectometry

W. Davey; O. Buiu; M. Werner; I. Z. Mitrovic; S. Hall; P. Chalker

2009-07-01T23:59:59.000Z

284

Density of Spray-Formed Materials  

SciTech Connect

Spray Forming is an advanced materials processing technology that transforms molten metal into a near-net-shape solid by depositing atomized droplets onto a substrate. Depending on the application, the spray-formed material may be used in the as-deposited condition or it may undergo post-deposition processing. Regardless, the density of the as-deposited material is an important issue. Porosity is detrimental because it can significantly reduce strength, toughness, hardness and other properties. While it is not feasible to achieve fully-dense material in the as-deposited state, density greater than 99% of theoretical density is possible if the atomization and impact conditions are optimized. Thermal conditions at the deposit surface and droplet impact angle are key processing parameters that influence the density of the material. This paper examines the factors that contribute to porosity formation during spray forming and illustrates that very high as-deposited density is achieved by optimizing processing parameters.

Kevin M. McHugh; Volker Uhlenwinkel; Nils Ellendr

2008-06-01T23:59:59.000Z

285

Empirical vertical structure of density anomaly in the Gulf of Mexico  

E-Print Network (OSTI)

Climatological vertical structure of density anomaly in the Gulf of Mexico is realistically characterized in a form useful for calibration and/or verification of numerical circulation models, employing a new method that allows variable depth and thermocline ventilation. We do this by local flat bottom dynamic analysis based on the primitive equations referred to an isopycnic coordinate system, so that potential density is treated as a conservative property. A global reference column is constructed for use in a dynamic modal decomposition in terms of local vertical structure functions that integrates seafloor depth and station data in a common spectral representation. The dynamic procedure is followed by joint and simple indirect EOF (empirical orthogonal function) analysis of modal coefficients for the complete data set and for binned subsets of the data. The dominant EOFs resemble dynamic modes, but combinations of dynamic modes are observed in EOFs having small contribution to the total variance. Indirect EOF representation of the data appears to have its greatest implications in the physical interpretation of the dynamic system, specifically in the coupling of dynamic modes.

Current, Carole Louise

1993-01-01T23:59:59.000Z

286

Osteoporotic-like effects of cadmium on bone mineral density and content in aged ovariectomized beagles  

SciTech Connect

Our purpose was to evaluate the effects of ovariectomy in conjunction with cadmium (Cd) exposure on bone. Aged female beagles with {sup 45}Ca-labeled skeletons ovariectomized and exposed to Cd. Successive vertebral scans by dual photon absorptiometry monitored changes in bone mineral density (BMD) in each dog with time. Results showed that ovariectomy or Cd exposure alone caused significant decreases in BMD; ovariectomy with Cd exposure caused the greatest decrease. Ovariectomy alone did not decrease BMD in the distal end or mid-shaft of the tibia while BMD of the distal tibia decreased significantly due to Cd exposure alone. Combination treatment resulted in significant decreases in BMD of both tibial regions. At necropsy, tibiae, humeri, lumbar vertebrae and ribs were obtained for biochemical analysis. No group-to-group differences in bone weights (wet, dry, ash), in ash/dry ratios, or in long bone and vertebral Ca/dry or Ca/ash ratios were observed. Significantly higher total {sup 45}Ca content and {sup 45}Ca/dry and {sup 45}Ca/ash ratios were observed in long bones and vertebrae of OV- and OV+ groups. In contrast, intact ribs showed significantly decreased Ca/dry and Ca/ash ratios compared to the SO-group. Quartered ribs demonstrated regional responses to specific treatment; decreases in total Ca content were greatest in the mid-rib region ({minus}36 to {minus}46%). Results suggest that in the aged female beagle, bone mineral loss associated with estrogen depletion is not only related to bone type (trabecular versus cortical) but also to bone Ca pools. Our results also suggest that a regional heterogeneity of bone plays a role in responsiveness to ovariectomy and Cd exposure. These aspects suggest that Cd is an exogenous factor affecting bone mineral loss independently of estrogen depletion. However, estrogen depletion primes bone for responsiveness to Cd-induced bone mineral loss.

Sacco-Gibson, N.; Abrams, J.; Chaudhry, S.; Hurst, D.; Peterson, D.; Bhattacharyya, M.

1992-12-31T23:59:59.000Z

287

Optimal Constant-Time Approximation Algorithms and (Unconditional) Inapproximability Results for Every Bounded-Degree CSP  

E-Print Network (OSTI)

Raghavendra (STOC 2008) gave an elegant and surprising result: if Khot's Unique Games Conjecture (STOC 2002) is true, then for every constraint satisfaction problem (CSP), the best approximation ratio is attained by a certain simple semidefinite programming and a rounding scheme for it. In this paper, we show that a similar result holds for constant-time approximation algorithms in the bounded-degree model. Specifically, we present the followings: (i) For every CSP, we construct an oracle that serves an access, in constant time, to a nearly optimal solution of a basic LP relaxation of the CSP. (ii) Using the oracle, we present a constant-time rounding scheme that achieves an approximation ratio coincident with the integrality gap of the basic LP. (iii) We give a generic conversion from integrality gaps of basic LPs to hardness results. All of those results are ``unconditional.'' Therefore, for every bounded-degree CSP, we give the best constant-time approximation algorithm among all.

Yoshida, Yuichi

2010-01-01T23:59:59.000Z

288

Longwave 3D Benchmarks for Inhomogeneous Clouds and Comparisons with Approximate Methods  

Science Conference Proceedings (OSTI)

The purpose of this study is twofold: to (i) establish three-dimensional (3D) longwave radiative transfer benchmarks for inhomogeneous cloud fields and (ii) compare the results with three approximate, 1D methods. The benchmark results are ...

George P. Kablick III; Robert G. Ellingson; Ezra E. Takara; Jlujing Gu

2011-04-01T23:59:59.000Z

289

Approximation fixpoint theory and the semantics of logic and answers set programs  

Science Conference Proceedings (OSTI)

Approximation Fixpoint Theory was developed as a fixpoint theory of lattice operators that provides a uniform formalization of four main semantics of three major nonmonotonic reasoning formalisms. This paper clarifies how this fixpoint theory can define ...

Marc Denecker; Maurice Bruynooghe; Joost Vennekens

2012-01-01T23:59:59.000Z

290

EA-1915: Conveyance of Approximately 1,641 Acres of Unimproved Land to the  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

5: Conveyance of Approximately 1,641 Acres of Unimproved Land 5: Conveyance of Approximately 1,641 Acres of Unimproved Land to the Tri-City Development Council, the Local Community Reuse Organization, Richland, WA EA-1915: Conveyance of Approximately 1,641 Acres of Unimproved Land to the Tri-City Development Council, the Local Community Reuse Organization, Richland, WA Summary This EA will evaluate the environmental impacts of conveyance of approximately 1,641 acres of unimproved land at DOE's Hanford Site, Richland, Washington to the Tri-City Development Council, the local community reuse organization. Public Comment Opportunities None available at this time. Documents Available for Download September 19, 2012 EA-1915: Notice of Intent to Prepare an Environmental Assessment and Notice of Potential Floodplain and Wetland Involvement

291

Approximate analysis of the temperature induced stresses and deformations of composite shells  

Science Conference Proceedings (OSTI)

In this paper simple formulas are presented which can be used to estimate the response of composite plates and shells to hygrothermal loads. The layup of the shell can be arbitrary (i.e., it can be symmetric or unsymmetric, balanced or unbalanced). The formulas serve two purposes. First, they can be used to calculate directly the stresses, strains, and displacements caused by a temperature and a moisture gradient. Second, the formulas can be used to determine the 'effective' thermal and moisture expansion coefficients which are the parameters needed in more accurate numerical (FEM) calculations. The accuracies of the approximate formulas were assessed by sample problems. In these problems the hygrothermal deformations of cylinders and cylindrical segments were calculated by the present approximate formulas and by an exact, three-dimensional analysis. The results of the exact and approximate methods were compared. These comparisons showed that the approximate formulas yield the deformations with a high degree of accuracy. 18 refs.

Kollar, L.P. (Stanford Univ., Stanford, CA (United States))

1994-01-01T23:59:59.000Z

292

Approximating game-theoretic optimal strategies for full-scale poker  

Science Conference Proceedings (OSTI)

The computation of the first complete approximations of game-theoretic optimal strategies for full-scale poker is addressed. Several abstraction techniques are combined to represent the game of 2-player Texas Hold'em, having size O(1018), ...

D. Billings; N. Burch; A. Davidson; R. Holte; J. Schaeffer; T. Schauenberg; D. Szafron

2003-08-01T23:59:59.000Z

293

Analytic Approximation of Discrete Field Samples with Weighted Sums and the Gridless Computation of Field Derivatives  

Science Conference Proceedings (OSTI)

Objective analysis by weighted sums of discrete observations is equivalent to the approximation of the distribution of an observed parameter by a function which is also analytic, provided that the weighting function is both analytic and positive ...

F. Caracena

1987-12-01T23:59:59.000Z

294

Base-state Substitution: An Idealized Modeling Technique for Approximating Environmental Variability  

Science Conference Proceedings (OSTI)

Base-state substitution (BSS) is a novel modeling technique for approximating environmental heterogeneity in idealized simulations. After a certain amount of model run time, base-state substitution replaces the original horizontally homogeneous ...

Casey E. Letkewicz; Adam J. French; Matthew D. Parker

295

Bounds and Approximations for Sums of Dependent Log-Elliptical Random Variables  

E-Print Network (OSTI)

Dhaene, Denuit, Goovaerts, Kaas & Vyncke (2002a,b) have studied convex bounds for a sum of dependent random variables and applied these to sums of log-normal random variables. In particular, they have shown how these convex bounds can be used to derive closed-form approximations for several of the risk measures of such a sum. In this paper we investigate to which extent their general results on convex bounds can also be applied to sums of log-elliptical random variables which incorporate sums of log-normals as a special case. Firstly, we show that unlike the log-normal case, for general sums of log-ellipticals the convex lower bound does no longer result in closed form approximations for the different risk measures. Secondly, we demonstrate how instead the weaker stop-loss order can be used to derive such closed form approximations. We also present numerical examples to show the accuracy of the proposed approximations.

unknown authors

2008-01-01T23:59:59.000Z

296

Modified Delta-Eddington Approximation for Solar Reflection, Transmission, and Absorption Calculations  

Science Conference Proceedings (OSTI)

The fractional factor f of ?-function scaling in the ?-Eddington approximation modifies the fractional scattering into the forward peak. As shown in this paper, reasonably choosing the factor f can yield a great improvement of transmission, ...

Jinhuan Qiu

1999-08-01T23:59:59.000Z

297

A New Approximate Solution of the Optimal Nonlinear Filter for Data Assimilation in Meteorology and Oceanography  

Science Conference Proceedings (OSTI)

This paper introduces a new approximate solution of the optimal nonlinear filter suitable for nonlinear oceanic and atmospheric data assimilation problems. The method is based on a local linearization in a low-rank kernel representation of the ...

I. Hoteit; D-T. Pham; G. Triantafyllou; G. Korres

2008-01-01T23:59:59.000Z

298

Medial Spheres for Shape Approximation Svetlana Stolpner, Paul Kry, Kaleem Siddiqi  

E-Print Network (OSTI)

distance tests than the state-of-the-art method for sphere set approximation for the class of (, )-fat-of-detail rendering [4], shape matching [5], and shape deformation [6]. In the above applications, it is desirable

Dudek, Gregory

299

Monotone Finite-Difference Approximations to the Advection-Condensation Problem  

Science Conference Proceedings (OSTI)

We discuss herein numerical difficulties with finite-difference approximations to the thermodynamic conservation laws near sharp, cloud-environment interfaces. The Conservation laws for entropy and water substance variables are coupled through ...

Wojciech W. Grabowski; Piotr K. Smolarkiewicz

1990-10-01T23:59:59.000Z

300

A Comparison of Ekman Pumping in Approximate Models of the Accelerating Planetary Boundary Layer  

Science Conference Proceedings (OSTI)

Several theories of the planetary boundary layer that retain the flow accelerations in approximate form are compared. Two special test cases focus on the role of either local or convective accelerations. The semigeotriptic theory of Cullen ...

Peter R. Bannon

1998-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Base-State Substitution: An Idealized Modeling Technique for Approximating Environmental Variability  

Science Conference Proceedings (OSTI)

Base-state substitution (BSS) is a novel modeling technique for approximating environmental heterogeneity in idealized simulations. After a certain amount of model run time, base-state substitution replaces the original horizontally homogeneous ...

Casey E. Letkewicz; Adam J. French; Matthew D. Parker

2013-09-01T23:59:59.000Z

302

Four-Stream Spherical Harmonic Expansion Approximation for Solar Radiative Transfer  

Science Conference Proceedings (OSTI)

This paper presents a four-stream extension of the ?-Eddington approximation by considering the higher-order spherical harmonic expansion in radiative intensity. By using the orthogonality relation of the spherical harmonic functions, the ...

J. Li; V. Ramaswamy

1996-04-01T23:59:59.000Z

303

Effects of the Boussinesq Approximation on the Results of Strongly-Buoyant Plume Calculations  

Science Conference Proceedings (OSTI)

Nearly all mathematical models which are commonly used to predict the dispersion of chimney gases in the atmosphere or heated water discharges in the aquatic environment employ the so-called Boussinesq approximation. It is part of this ...

M. Schatzmann; A. J. Policastro

1984-01-01T23:59:59.000Z

304

A Coupled Atmosphere–Ocean Radiative Transfer System Using the Analytic Four-Stream Approximation  

Science Conference Proceedings (OSTI)

A coupled atmosphere–ocean radiative transfer model based on the analytic four-stream approximation has been developed. It is shown that this radiation model is computationally efficient and at the same time can achieve acceptable accuracy for ...

Wei-Liang Lee; K. N. Liou

2007-10-01T23:59:59.000Z

305

An Approximation to Multiple Scattering in the Earth's Atmosphere: Almucantar Radiance Formulation  

Science Conference Proceedings (OSTI)

The retrieval of aerosol size distributions from solar aureole measurements, in the past, have been made tractable by assuming the single-scattering approximation, since the inclusion of multiple scattering by solving the complete radiative ...

M. A. Box; A. Deepak

1981-05-01T23:59:59.000Z

306

Table A6. Approximate Heat Rates for Electricity, and Heat Content ...  

U.S. Energy Information Administration (EIA)

Total Fossil Fuels 6,7: ... 7 The fossil-fuels heat rate is used as the thermal conversion factor for ... approximate the quantity of fossil fuels replaced by these ...

307

A Simple Model of a Convectively Coupled Walker Circulation Using the Weak Temperature Gradient Approximation  

Science Conference Proceedings (OSTI)

An idealized model of a Walker circulation based on the weak temperature gradient (WTG) approximation and a single baroclinic vertical mode for all fields is analyzed. The circulation is forced by a sinusoidal variation of sea surface temperature ...

Christopher S. Bretherton; Adam H. Sobel

2002-10-01T23:59:59.000Z

308

Approximate consensus in the dynamic stochastic network with incomplete information and measurement delays  

Science Conference Proceedings (OSTI)

Consideration was given to the problem of achieving an approximate consensus in the decentralized stochastic dynamic network under incomplete information about the current states of the nodes, measurement delay, and variable structure of links. Solution ...

N. O. Amelina; A. L. Fradkov

2012-11-01T23:59:59.000Z

309

Instabilities in the Nuclear Energy Density Functional  

E-Print Network (OSTI)

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.

M. Kortelainen; T. Lesinski

2010-02-05T23:59:59.000Z

310

Low density, resorcinol-formaldehyde aerogels  

DOE Patents (OSTI)

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.

Pekala, R.W.

1989-10-10T23:59:59.000Z

311

Low density, resorcinol-formaldehyde aerogels  

DOE Patents (OSTI)

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 {le}100 mg/cc; cell size {le}0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A{degrees}. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 ref., 1 tab.

Pekala, R.W.

1989-09-12T23:59:59.000Z

312

Low density, resorcinol-formaldehyde aerogels  

DOE Patents (OSTI)

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.

Pekala, Richard W. (Pleasant Hill, CA)

1989-01-01T23:59:59.000Z

313

Low density, resorcinol-formaldehyde aerogels  

DOE Patents (OSTI)

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.

Pekala, Richard W. (Pleasant Hill, CA)

1991-01-01T23:59:59.000Z

314

Phase Diagram of Amorphous Solid Water: Low-Density, High-Density, and Very-High-Density Amorphous Ices  

E-Print Network (OSTI)

We describe the phase diagram of amorphous solid water by performing molecular dynamics simulations. Our simulations follow different paths in the phase diagram: isothermal compression/decompression, isochoric cooling/heating and isobaric cooling/heating. We are able to identify low-density amorphous (LDA), high-density amorphous (HDA), and very-high density amorphous (VHDA) ices. The density $\\rho$ of these glasses at different pressure $P$ and temperature $T$ agree well with experimental values. We also study the radial distribution functions of glassy water. We obtain VHDA by isobaric heating of HDA, as in experiment. We also find that ``other forms'' of glassy water can be obtained upon isobaric heating of LDA, as well as amorphous ices formed during the transformation of LDA to HDA. We argue that these other forms of amorphous ices, as well as VHDA, are not altogether new glasses but rather are the result of aging induced by heating. Samples of HDA and VHDA with different densities are recovered at normal $P$, showing that there is a continuum of glasses. Furthermore, the two ranges of densities of recovered HDA and recovered VHDA overlap at ambient $P$. Our simulations are consistent with the possibility of HDA$\\to$LDA and VHDA$\\to$LDA transformations, reproducing the experimental findings. We do not observe a VHDA$\\to$HDA transformation.

Nicolas Giovambattista; H. Eugene Stanley; Francesco Sciortino

2005-02-22T23:59:59.000Z

315

Few body impulse and fixed scatterer approximations for high energy scattering  

E-Print Network (OSTI)

The elastic scattering differential cross section is calculated for proton scattering from $^6$He at 717 MeV, using single scattering terms of the multiple scattering expansion of the total transition amplitude (MST). We analyse the effects of different scattering frameworks, specifically the Factorized Impulse Approximation (FIA) and the Fixed Scatterer (adiabatic) Approximation (FSA) and the uncertainties associated with the use different structure models.

R. Crespo; A. M. Moro; I. J. Thompson

2006-03-02T23:59:59.000Z

316

Estimating the Bias of Local Polynomial Approximations Using the Peano Kernel  

SciTech Connect

These presentation visuals define local polynomial approximations, give formulas for bias and random components of the error, and express bias error in terms of the Peano kernel. They further derive constants that give figures of merit, and show the figures of merit for 3 common weighting functions. The Peano kernel theorem yields estimates for the bias error for local-polynomial-approximation smoothing that are superior in several ways to the error estimates in the current literature.

Blair, J., and Machorro, E.

2012-03-22T23:59:59.000Z

317

Expancel Foams: Fabrication and Characterization of a New Reduced Density Cellular Material for Structural Applications  

Science Conference Proceedings (OSTI)

This study was initiated to produce a low-density centering medium for use in experiments investigating the response of materials to shock-loading. While the main drivers for material selection were homogeneity, dimensional stability, performance and cost, other secondary requirements included fine cell size, the ability to manufacture 5--10 cm-sized parts and an extremely compressed development time. The authors chose a non-traditional methodology using a hollow, expandable, polymeric microballoon material system called Expancel{reg_sign}. These microballoons are made from a copolymer of polyacrylonitrile (PAN) and polymethacrylonitrile (PMAN) and use iso-pentane as the blowing agent. The average diameter (by volume) of the unexpanded powder is approximately 13 {micro}m, while the average of the expanded powder is 35--55 {micro}m, with a few large microballoons approaching 150--200 p.m. A processing method was developed that established a pre-mixed combination of unexpanded and expanded Expancel at a ratio such that the tap (or vibration) density of the mixed powders was the same as that desired of the final part. Upon heating above the tack temperature of the polymer, this zero-rise approach allowed only expansion of the unexpanded powder to fill the interstices between the pre-expanded balloons. The mechanical action of the expanding powder combined with the elevated processing temperature yielded flee-standing and mechanically robust parts. Although mechanical properties of these foams were not a key performance requirement, the data allowed for the determination of the best temperature to heat the samples. Processing the foam at higher temperatures enhanced both modulus and strength. The maximum allowable temperature was limited by dimensional stability and shrinkback considerations. Tomographic analysis of foam billets revealed very flat density profiles. Parts of any density between the low density expanded powder (approximately 0.013 g/cm{sup 3}) and the higher density unexpanded powder (approximately 0.5 g/cm{sup 3}) can be produced using this technique. The extremely wide range of accessible densities, ease of processing, relatively inexpensive materials, uniformity of the density, scaleable nature of the process should make this technology highly competitive for a variety of Defense Programs and commercial applications.

L. Whinnery; S. Goods; B. Even

2000-08-01T23:59:59.000Z

318

Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei  

E-Print Network (OSTI)

Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness Delta r(np) of Sn isotopes give an important constraint on the symmetry energy E(sym)(rho(0)) and its density slope L at saturation density rho(0). Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on L approximately independent of E(sym)(rho(0)). The implication of these new constraints on the Delta r(np) of (208)Pb as well as the core-crust transition density and pressure in neutron stars is discussed.

Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An; Xu, Jun.

2010-01-01T23:59:59.000Z

319

Ab initio and density functional studies of hydrocarbon adsorption in zeolites.  

SciTech Connect

The adsorption energies of methane and ethane in zeolites are investigated with ab initio molecular orbital theory and density functional theory. In this work we have used zeolite cluster models containing two, three, and five tetrahedral (Si, Al) atoms and have found equilibrium structures for complexes of methane, ethane, and propane with an acid site. If a large enough cluster is used and correlation effects are included via perturbation theory, the calculated adsorption energy for ethane is about 5 kcal/mol compared with the experimental value of 7.5 kcal/mol. The B3LYP density functional method gives a much smaller binding of {approximately}1 kcal/mol for ethane. The reason for the failure of density fictional theory is unclear.

Curtiss, L. A.

1998-08-21T23:59:59.000Z

320

Development of iteration strategies for a practical implementation of a higher order transverse leakage approximation  

Science Conference Proceedings (OSTI)

Transverse integrated nodal diffusion methods currently represent the standard in full core neutronic simulation. The primary shortcoming in this approach is the utilization of the quadratic transverse leakage approximation. This approach, although proven to work well for typical LWR problems, is not consistent with the formulation of nodal methods and can cause accuracy and convergence problems. In previous work, an improved, consistent quadratic leakage approximation was formulated, which derived from the class of higher order nodal methods developed some years ago. In this paper a number of iteration schemes are developed around this consistent quadratic leakage approximation which yield accurate node average results in much improved calculational times. The developed consistent leakage approximation is extended in this work via a number of numerical schemes, the most promising of which results from utilizing the consistent leakage approximation as a correction method to the standard quadratic leakage approximation. Numerical results are demonstrated on a set of benchmark problems, such as the 3D IAEA LWR and MOX C5 problems. (authors)

Prinsloo, R. H.; Tomasevic, D. I. [Necsa, PO Box 582, Pretoria, 0001 (South Africa)

2012-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Approximation of lateral distribution of atmospheric Cherenkov light at different observation levels for different primary particles. Applications for cosmic ray studies  

E-Print Network (OSTI)

This work summarizes the results presented at 29th International Cosmic Ray Conference in Pune India. Generally the aim of this work is to obtain the lateral distribution of the atmospheric Cherenkov light in extensive air showers produced by different primary particles in wide energy range and at several observation levels and to fit the obtained lateral distributions. Using one large detector and partially modified CORSIKA code version are obtained the lateral distributions of Cherenkov light flux densities at several observation levels for different particle primaries precisely at 536 g/cm2 Chacaltaya, 700 g/cm2 Moussala and 875 g/cm2 Kartalska field observation levels for hadronic primaries and gamma quanta in the energy range 1011 eV-1016 eV. On the basis of the solution of over-determined inverse problem the approximation of these distributions is obtained. The same model function for all the primaries is used and for the different observation levels. The different model parameters for the different primaries and levels are obtained. The approximations are compared with polynomial approximation obtained with different method. Both approximations are used for detector efficiency estimation for the different experiments in preparation and estimation of the accuracy of the reconstruction techniques. At the same time inclined showers up to 30 degrees zenith angle are studied at Chacaltaya observation level. The obtained lateral distributions of vertical showers are compared with vertical showers model and the previously obtained approximation. This permits to adjust the reconstruction strategy and to study the model parameters behavior.

Alexander Mishev; Strashimir Mavrodiev; Jordan Stamenov

2005-11-29T23:59:59.000Z

322

wave power density | OpenEI  

Open Energy Info (EERE)

power density power density Dataset Summary Description This project estimates the naturally available and technically recoverable U.S. wave energy resources, using a 51-month Wavewatch III hindcast database developed especially for this study by National Oceanographic and Atmospheric Administration's (NOAA's) National Centers for Environmental Prediction. For total resource estimation, wave power density in terms of kilowatts per meter is aggregated across a unit diameter circle. Source Electric Power Research Institute (EPRI) Date Released December 05th, 2011 (2 years ago) Date Updated Unknown Keywords EPRI MHK NREL ocean Virginia Tech wave wave power density Data application/pdf icon Download Full Report (pdf, 8.8 MiB) Quality Metrics Level of Review Some Review Comment

323

Definition: Rock Density | Open Energy Information  

Open Energy Info (EERE)

in crustal rocks. Rock density is a physical characteristic that is governed by the chemical composition (in situ minerals) and pore spaces of a specific rock or rock type.1...

324

High density load bearing insulation peg  

DOE Patents (OSTI)

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.

Nowobilski, J.J.; Owens, W.J.

1985-01-29T23:59:59.000Z

325

Velocity Probability Density Functions from Altimetry  

Science Conference Proceedings (OSTI)

Probability density functions (pdfs) are employed to evaluate the distribution of velocities in the global ocean. This study computes pdfs of ocean surface velocity using altimetric data from the TOPEX/Poseidon satellite. Results show that the ...

Sarah T. Gille; Stefan G. Llewellyn Smith

2000-01-01T23:59:59.000Z

326

Density controlled carbon nanotube array electrodes  

DOE Patents (OSTI)

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.

Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)

2008-12-16T23:59:59.000Z

327

Separation of carbon nanotubes in density gradients  

DOE Patents (OSTI)

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2012-02-07T23:59:59.000Z

328

Separation of carbon nanotubes in density gradients  

DOE Patents (OSTI)

The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)

2010-02-16T23:59:59.000Z

329

High density load bearing insulation peg  

DOE Patents (OSTI)

A high density peg 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.

Nowobilski, Jeffert J. (Orchard Park, NY); Owens, William J. (Kenmore, NY)

1985-01-01T23:59:59.000Z

330

Local Atomic Density of Microporous Carbons  

DOE Green Energy (OSTI)

We investigated the structure of two disordered carbons: activated carbon fibers (ACF) and ultramicroporous carbon (UMC). These carbons have highly porous structure with large surface areas and consequently low macroscopic density that should enhance adsorption of hydrogen. We used the atomic pair distribution function to probe the local atomic arrangements. The results show that the carbons maintain an in-plane local atomic structure similar to regular graphite, but the stacking of graphitic layers is strongly disordered. Although the local atomic density of these carbons is lower than graphite, it is only {approx}20% lower and is much higher than the macroscopic density due to the porosity of the structure. For this reason, the density of graphene sheets that have optimum separation for hydrogen adsorption is lower than anticipated.

Dmowski, Wojtek; Contescu, Cristian I.; Llobet, Anna; Gallego, Nidia C.; Egami, Takeskhi (Tennessee-K); (ORNL); (LANL)

2012-07-12T23:59:59.000Z

331

Fast alogorithms for Bayesian uncertainty quantification in large-scale linear inverse problems based on low-rank partial Hessian approximations  

SciTech Connect

We consider the problem of estimating the uncertainty in large-scale linear statistical inverse problems with high-dimensional parameter spaces within the framework of Bayesian inference. When the noise and prior probability densities are Gaussian, the solution to the inverse problem is also Gaussian, and is thus characterized by the mean and covariance matrix of the posterior probability density. Unfortunately, explicitly computing the posterior covariance matrix requires as many forward solutions as there are parameters, and is thus prohibitive when the forward problem is expensive and the parameter dimension is large. However, for many ill-posed inverse problems, the Hessian matrix of the data misfit term has a spectrum that collapses rapidly to zero. We present a fast method for computation of an approximation to the posterior covariance that exploits the lowrank structure of the preconditioned (by the prior covariance) Hessian of the data misfit. Analysis of an infinite-dimensional model convection-diffusion problem, and numerical experiments on large-scale 3D convection-diffusion inverse problems with up to 1.5 million parameters, demonstrate that the number of forward PDE solves required for an accurate low-rank approximation is independent of the problem dimension. This permits scalable estimation of the uncertainty in large-scale ill-posed linear inverse problems at a small multiple (independent of the problem dimension) of the cost of solving the forward problem.

Akcelik, Volkan [ORNL; Flath, Pearl [University of Texas, Austin; Ghattas, Omar [University of Texas, Austin; Hill, Judith C [ORNL; Van Bloemen Waanders, Bart [Sandia National Laboratories (SNL); Wilcox, Lucas [University of Texas, Austin

2011-01-01T23:59:59.000Z

332

Boussinesq and Anelastic Approximations Revisited: Potential Energy Release during Thermobaric Instability  

Science Conference Proceedings (OSTI)

Expressions are derived for the potential energy of a fluid whose density depends on three variables: temperature, pressure, and salinity. The thermal expansion coefficient is a function of depth, and the application is to thermobaric convection ...

Andrew P. Ingersoll

2005-08-01T23:59:59.000Z

333

Dressed-bound-state molecular strong-field approximation: Application to above-threshold ionization of heteronuclear diatomic molecules  

Science Conference Proceedings (OSTI)

The molecular strong-field approximation (MSFA), which includes dressing of the molecular bound state, is introduced and applied to above-threshold ionization of heteronuclear diatomic molecules. Expressions for the laser-induced molecular dipole and polarizability as functions of the laser parameters (intensity and frequency) and molecular parameters [molecular orientation, dipole, and parallel and perpendicular polarizabilities of the highest occupied molecular orbital (HOMO)] are presented. Our previous MSFA theory, which incorporates the rescattering effects, is generalized from homonuclear to heteronuclear diatomic molecules. Angle- and energy-resolved high-order above-threshold ionization spectra of oriented heteronuclear diatomic molecules, exemplified by the carbon monoxide (CO) molecule, exhibit pronounced minima, which can be related to the shape of their HOMO-electron-density distribution. For the CO molecule we have found an analytical condition for the positions of these minima. We have also shown that the effect of the dressing of the HOMO is twofold: (i) the laser-induced Stark shift decreases the ionization yield and (ii) the laser-induced time-dependent dipole and polarizability change the oscillatory structure of the spectra.

Hasovic, E. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, BA-71000 Sarajevo (Bosnia and Herzegowina); Max-Born-Institut, Max-Born-Strasse 2a, DE-12489 Berlin (Germany); Busuladzic, M. [Medical Faculty, University of Sarajevo, Cekalusa 90, BA-71000 Sarajevo (Bosnia and Herzegowina); Becker, W. [Max-Born-Institut, Max-Born-Strasse 2a, DE-12489 Berlin (Germany); Milosevic, D. B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, BA-71000 Sarajevo (Bosnia and Herzegowina); Max-Born-Institut, Max-Born-Strasse 2a, DE-12489 Berlin (Germany); Academy of Sciences and Arts of Bosnia and Herzegovina, Bistrik 7, BA-71000 Sarajevo (Bosnia and Herzegowina)

2011-12-15T23:59:59.000Z

334

A Finite-Difference Numerical Method for Onsager's Pancake Approximation for Fluid Flow in a Gas Centrifuge  

SciTech Connect

Gas centrifuges exhibit very complex flows. Within the centrifuge there is a rarefied region, a transition region, and a region with an extreme density gradient. The flow moves at hypersonic speeds and shock waves are present. However, the flow is subsonic in the axisymmetric plane. The analysis may be simplified by treating the flow as a perturbation of wheel flow. Wheel flow implies that the fluid is moving as a solid body. With the very large pressure gradient, the majority of the fluid is located very close to the rotor wall and moves at an azimuthal velocity proportional to its distance from the rotor wall; there is no slipping in the azimuthal plane. The fluid can be modeled as incompressible and subsonic in the axisymmetric plane. By treating the centrifuge as long, end effects can be appropriately modeled without performing a detailed boundary layer analysis. Onsager's pancake approximation is used to construct a simulation to model fluid flow in a gas centrifuge. The governing 6th order partial differential equation is broken down into an equivalent coupled system of three equations and then solved numerically. In addition to a discussion on the baseline solution, known problems and future work possibilities are presented.

de Stadler, M; Chand, K

2007-11-12T23:59:59.000Z

335

Noise kernel for a quantum field in Schwarzschild spacetime under the Gaussian approximation  

E-Print Network (OSTI)

A method is given to compute an approximation to the noise kernel, defined as the symmetrized connected 2-point function of the stress tensor, for the conformally invariant scalar field in any spacetime conformal to an ultra-static spacetime for the case in which the field is in a thermal state at an arbitrary temperature. The most useful applications of the method are flat space where the approximation is exact and Schwarzschild spacetime where the approximation is better than it is in most other spacetimes. The two points are assumed to be separated in a timelike or spacelike direction. The method involves the use of a Gaussian approximation which is of the same type as that used by Page to compute an approximate form of the stress tensor for this field in Schwarzschild spacetime. All components of the noise kernel have been computed exactly for hot flat space and one component is explicitly displayed. Several components have also been computed for Schwarzschild spacetime and again one component is explicitly displayed.

A. Eftekharzadeh; Jason D. Bates; Albert Roura; Paul R. Anderson; B. L. Hu

2010-11-22T23:59:59.000Z

336

Exact and approximate solutions for the quantum minimum-Kullback-entropy estimation problem  

E-Print Network (OSTI)

The minimum Kullback entropy principle (mKE) is a useful tool to estimate quantum states and operations from incomplete data and prior information. In general, the solution of a mKE problem is analytically challenging and an approximate solution has been proposed and employed in different context. Recently, the form and a way to compute the exact solution for finite dimensional systems has been found, and a question naturally arises on whether the approximate solution could be an effective substitute for the exact solution, and in which regimes this substitution can be performed. Here, we provide a systematic comparison between the exact and the approximate mKE solutions for a qubit system when average data from a single observable are available. We address both mKE estimation of states and weak Hamiltonians, and compare the two solutions in terms of state fidelity and operator distance. We find that the approximate solution is generally close to the exact one unless the initial state is near an eigenstate of the measured observable. Our results provide a rigorous justification for the use of the approximate solution whenever the above condition does not occur, and extend its range of application beyond those situations satisfying the assumptions used for its derivation.

Carlo Sparaciari; Stefano Olivares; Francesco Ticozzi; Matteo G. A. Paris

2013-11-23T23:59:59.000Z

337

Density logging and density of rocks in Rainier Mesa Area, Nevada Test Site  

SciTech Connect

Density logs from all 35 vertical drill holes in the Rainier Mesa area in which logs were obtained were evaluated and the distribution of densities of units in the geologic section was derived. Densities were obtained in only 10 holes in which calibrated logging tools had been run. The logs from an additional 10 holes were calibrated with core. Densities vary from nearly 1 g/cc in tunnel bed 5 to over 2.8 g/cc in the dolomitic rocks. Log densities were found to agree well with core data in those subunits (chiefly within tunnel beds 3 and 4) where an adequate number of core measurements were available for comparison. Lithologic correlations based on density log signatures were found to extend for more than 8 km in several units and subunits in the area. Although the volcanic rocks in the Rainier Mesa area are comprised of a wider spectrum of minerals than the petroliferous rocks generally involved in most commercial logging applications, grain density may be estimated with good accuracy with only a knowledge of glass and zeolite content. The variability of the Z/A ratio of the matrix in these volcanic rocks is also negligible compared to the value of 0.5 generally assumed in density logging. However, due to the assumptions made concerning the Z/A of water in deriving the output of commercial density tools, one should be aware of the errors inherent in assuming that recorded log densities are true densities. These errors are normally small, being less than 3 percent for compensated limestone'' tools and 2 percent for tools which output electron density. 35 refs., 25 figs., 12 tabs.

Carroll, R.D.

1989-01-01T23:59:59.000Z

338

Precise and Accurate Density Determination of Explosives Using Hydrostatic Weighing  

SciTech Connect

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.

B. Olinger

2005-07-01T23:59:59.000Z

339

The Complexity of Approximating Bounded-Degree Boolean #CSP (Extended Abstract)  

E-Print Network (OSTI)

The degree of a CSP instance is the maximum number of times that a variable may appear in the scope of constraints. We consider the approximate counting problem for Boolean CSPs with bounded-degree instances, for constraint languages containing the two unary constant relations {0} and {1}. When the maximum degree is at least 25 we obtain a complete classification of the complexity of this problem. It is exactly solvable in polynomial-time if every relation in the constraint language is affine. It is equivalent to the problem of approximately counting independent sets in bipartite graphs if every relation can be expressed as conjunctions of {0}, {1} and binary implication. Otherwise, there is no FPRAS unless NP=RP. For lower degree bounds, additional cases arise in which the complexity is related to the complexity of approximately counting independent sets in hypergraphs.

Dyer, Martin E; Jalsenius, Markus; Richerby, David

2010-01-01T23:59:59.000Z

340

Tests of Monte Carlo Independent Column Approximation in the ECHAM5  

NLE Websites -- All DOE Office Websites (Extended Search)

Tests of Monte Carlo Independent Column Approximation in the ECHAM5 Tests of Monte Carlo Independent Column Approximation in the ECHAM5 Atmospheric GCM Raisanen, Petri Finnish Meteoroligical Institute Jarvenoja, Simo Finnish Meteorological Institute Jarvinen, Heikki Finnish Meteorological Institute Category: Modeling The Monte Carlo Independent Column Approximation (McICA) was recently introduced as a new approach for parametrizing broadband radiative fluxes in global climate models (GCMs). The McICA allows a flexible description of unresolved cloud structure, and it is unbiased with respect to the full ICA, but its results contain conditional random errors (i.e., noise). In this work, McICA and a stochastic cloud generator have been implemented to the Max Planck Institute for Meteorology's ECHAM5 atmospheric GCM. The

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

DOE Seeks to Invest Approximately $1.3 Billion to Commercialize CCS  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

to Invest Approximately $1.3 Billion to Commercialize CCS to Invest Approximately $1.3 Billion to Commercialize CCS Technology DOE Seeks to Invest Approximately $1.3 Billion to Commercialize CCS Technology June 24, 2008 - 2:15pm Addthis Funding Opportunity Announcement Solicits Applications for Restructured FutureGen Program WASHINGTON, DC - The U.S. Department of Energy (DOE) today issued a Funding Opportunity Announcement (FOA) to invest in multiple commercial-scale Integrated Gasification Combined Cycle (IGCC) or other clean coal power plants with cutting-edge carbon capture and storage (CCS) technology under the Department's restructured FutureGen program. The solicitation is seeking multiple cost-shared projects to advance coal-based power generation technologies that capture and store the greenhouse gas carbon

342

Controlled Nonlinear Stochastic Delay Equations: Part II: Approximations and Pipe-Flow Representations  

SciTech Connect

This is the second part of a work dealing with key issues that have not been addressed in the modeling and numerical optimization of nonlinear stochastic delay systems. We consider new classes of models, such as those with nonlinear functions of several controls (such as products), each with is own delay, controlled random Poisson measure driving terms, admissions control with delayed retrials, and others. Part I was concerned with issues concerning the class of admissible controls and their approximations, since the classical definitions are inadequate for our models. This part is concerned with transportation equation representations and their approximations. Such representations of nonlinear stochastic delay models have been crucial in the development of numerical algorithms with much reduced memory and computational requirements. The representations for the new models are not obvious and are developed. They also provide a template for the adaptation of the Markov chain approximation numerical methods.

Kushner, Harold J., E-mail: hjk@dam.brown.edu [Brown University, Applied Math (United States)

2012-08-15T23:59:59.000Z

343

Low-energy dipole excitations in neon isotopes and N=16 isotones within the quasiparticle random-phase approximation and the Gogny force  

SciTech Connect

Low-energy dipole excitations in neon isotopes and N=16 isotones are calculated with a fully consistent axially-symmetric-deformed quasiparticle random phase approximation (QRPA) approach based on Hartree-Fock-Bogolyubov (HFB) states. The same Gogny D1S effective force has been used both in HFB and QRPA calculations. The microscopical structure of these low-lying resonances, as well as the behavior of proton and neutron transition densities, are investigated in order to determine the isoscalar or isovector nature of the excitations. It is found that the N=16 isotones {sup 24}O, {sup 26}Ne, {sup 28}Mg, and {sup 30}Si are characterized by a similar behavior. The occupation of the 2s{sub 1/2} neutron orbit turns out to be crucial, leading to nontrivial transition densities and to small but finite collectivity. Some low-lying dipole excitations of {sup 28}Ne and {sup 30}Ne, characterized by transitions involving the {nu}1d{sub 3/2} state, present a more collective behavior and isoscalar transition densities. A collective proton low-lying excitation is identified in the {sup 18}Ne nucleus.

Martini, M.; Peru, S.; Dupuis, M. [CEA/DAM/DIF, F-91297 Arpajon (France)

2011-03-15T23:59:59.000Z

344

Stabilizing control of parallel AC-DC power transmission systems by approximate switching curve  

SciTech Connect

A method to improve the transient stability of bulk power transmission system is presented. The method stabilizes the control of parallel ac-dc transmission systems using an approximate switching curve. The optimal switching curve is approximated by a power series and the resulting switching curve is determined independent of type and duration of faults that occur to the system. In addition, coefficients of the switching curve can be calculated on a off-line basis which allows use of simple on-line algebraic calculations in emergency conditions.

Ichiyanagi, K.; Kobayashi, H.; Kakehu, H.

1980-01-01T23:59:59.000Z

345

Scalar O(N) Model at Finite Temperature -- 2PI Effective Potential in Different Approximations  

E-Print Network (OSTI)

We calculate the two-particle irreducible (2PI) effective potential of the O(N) linear sigma model in 1+1 dimensions. The approximations we use are the next-to-leading order of a 1/N expansion (for arbitrary N) and a kind of "resummed loop approximation" for N=1. We show that the effective potential of the 1/N expansion is convex for N=4 and N=10 whereas it is not for the "loop" expansion and the case N=1 of the 1/N expansion.

Jurgen Baacke; Stefan Michalski

2004-09-14T23:59:59.000Z

346

Pulsed power drivers for ICF and high energy density physics  

SciTech Connect

Nanosecond Pulsed Power Science and Technology has its origins in the 1960s and over the past decade has matured into a flexible and robust discipline capable of addressing key physics issues of importance to ICF and high Energy Density Physics. The major leverage provided by pulsed power is its ability to generate and deliver high energy and high power at low cost and high efficiency. A low-cost, high-efficiency driver is important because of the very large capital investment required for multi-megajoule ignition-class systems. High efficiency is of additional importance for a commercially viable inertial fusion energy option. Nanosecond pulsed power has been aggressively and successfully developed at Sandia over the past twenty years. This effort has led to the development of unique multi-purpose facilities supported by highly capable diagnostic, calculational and analytic capabilities. The Sandia Particle-beam Fusion Program has evolved as part of an integrated national ICF Program. It applies the low-cost, high-efficiency leverage provided by nanosecond pulsed power systems to the longer-term goals of the national program, i.e., the Laboratory Microfusion Facility and Inertial Fusion Energy. A separate effort has led to the application of nanosecond pulsed power to the generation of intense, high-energy laboratory x-ray sources for application to x-ray laser and radiation effects science research. Saturn is the most powerful of these sources to date. It generates {approximately}500 kilojoules of x-rays from a magnetically driven implosion (Z-pinch). This paper describes results of x-ray physics experiments performed on Saturn, plans for a new Z-pinch drive capability for PBFA-II, and a design concept for the proposed {approximately}15 MJ Jupiter facility. The opportunities for ICF-relevant research using these facilities will also be discussed.

Ramirez, J.J.; Matzen, M.K.; McDaniel, D.H.

1995-12-31T23:59:59.000Z

347

Fission Cross Section Calculation Using TALYS Based on Two Different Level Density Models  

Science Conference Proceedings (OSTI)

Fission cross sections in statistical model of fission are calculated using one of important parameter such as transmission coefficients. This parameter calculated using optical model parameter and level density. There are several models of level density that can be used to predict fission cross section. They are Constant Temperature Model, Fermi Gas Model, Back-Shifted Fermi Gas Model, and Generalized Superfluid Model. In this work, fission cross section would be calculated using two different model of level density, such as Constant Temperature Model Plus Fermi Gas and Generalized Superfluid Model on Th-232 (n,f) fission reaction. Calculation result from two different model then would be compared with experimental data from ENDF B/VI. Analysis of result would lead to the conclusion of spesific characteristic for each model in every fission cases. This work has became a preliminary study to calculate fission cross section using different set of level density models. Further work will be implemented to calculate similar fission cross section using level density parameter that approximated by Thermal wavelength [see 21].

Kurniadi, R.; Basar, K.; Waris, A. [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia); Perkasa, Yudha S. [Department of Physics, Jl. Ganesa 10 Bandung 40132 (Indonesia); Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia)

2010-06-22T23:59:59.000Z

348

Modeled Salt Density for Nuclear Material Estimation in the Treatment of Spent Nuclear Fuel  

SciTech Connect

Spent metallic nuclear fuel is being treated in a pyrometallurgical process that includes electrorefining the uranium metal in molten eutectic LiCl-KCl as the supporting electrolyte. We report a model for determining the density of the molten salt. Inventory operations account for the net mass of salt and for the mass of actinides present. It was necessary to know the molten salt density but difficult to measure, and it was decided to model the salt density for the initial treatment operations. The model assumes that volumes are additive for the ideal molten salt solution as a starting point; subsequently a correction factor for the lanthanides and actinides was developed. After applying the correction factor, the percent difference between the net salt mass in the electrorefiner and the resulting modeled salt mass decreased from more than 4.0% to approximately 0.1%. As a result, there is no need to measure the salt density at 500 C for inventory operations; the model for the salt density is found to be accurate.

DeeEarl Vaden; Robert. D. Mariani

2010-09-01T23:59:59.000Z

349

High-Energy-Density Plasmas, Fluids  

NLE Websites -- All DOE Office Websites (Extended Search)

High-Energy-Density Plasmas, Fluids High-Energy-Density Plasmas, Fluids /science-innovation/_assets/images/icon-science.jpg High-Energy-Density Plasmas, Fluids National security depends on science and technology. The United States relies on Los Alamos National Laboratory for the best of both. No place on Earth pursues a broader array of world-class scientific endeavors. TRIDENT target chamber Sasi Palaniyappan, right, and Rahul Shah left inside a target chamber where the TRIDENT short pulse laser is aimed at a very thin diamond- foil target, a fraction of a micrometer thick. The laser delivers a power on target of 150 Terawatts focused into a 7 micrometer spot, yielding laser brilliance over 100 times more intense than needed to make the target electrons fully relativistic. These experiments test novel methods of producing intense

350

Low density, resorcinol-formaldehyde aerogels  

DOE Patents (OSTI)

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.

Pekala, R.W.

1988-05-26T23:59:59.000Z

351

Fabrication of low density ceramic material  

DOE Patents (OSTI)

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.

Meek, T.T.; Blake, R.D.; Sheinberg, H.

1985-01-01T23:59:59.000Z

352

Relation between the High Density Phase and the Very-High Density Phase of Amorphous Solid Water  

E-Print Network (OSTI)

Relation between the High Density Phase and the Very-High Density Phase of Amorphous Solid Water; published 18 March 2005) It has been suggested that high-density amorphous (HDA) ice is a structurally arrested form of high- density liquid (HDL) water, while low-density amorphous ice is a structurally

Sciortino, Francesco

353

Measurements of long-wavelength density fluctuations in TFTR  

SciTech Connect

Several experiments have been devised to measure plasma fluctuations in an effort to help elucidate a possible connection between plasma microturbulence and anomalous transport. Results from microwave scattering on the Tokamak Fusion Test Reactor (TFTR) (Nucl. Fusion {bold 18}, 1089 (1978)) show that the level of plasma fluctuations increases toward the long-wavelength region ({ital k}{sub {perpendicular}}{rho}{sub {ital s}}{le}0.2), at which point the fluctuations cannot be spatially resolved. The desire to measure long-wavelength fluctuations has motivated the development of two fluctuation diagnostics, beam emission spectroscopy (BES), and microwave reflectometry on TFTR. BES measures long-wavelength density fluctuations ({ital k}{sub {perpendicular}}{le}2 cm{sup {minus}1}) by observing the fluorescence emitted from collisionally excited atoms in a TFTR heating beam. In L-mode discharges with relatively flat density profiles, the fluctuations measured with BES are concentrated in the low-frequency region ({le}30 kHz). In the laboratory frame, the fluctuations have a poloidal propagation velocity that is approximately equal to that of the plasma rotation, and the frequency spectra are broadened by Doppler effects. Measured fluctuation levels are 5%--10% at the edge of the plasma. In the core, the level falls to less than 1%, which is comparable to observations made with microwave reflectometry and scattering. The fluctuation level in the core ({ital r}/{ital a}=0.7) is seen to increase with injected beam power, as is observed with microwave scattering at shorter wavelengths ({ital k}{sub {perpendicular}}{approx}2--10 cm{sup {minus}1}). In contrast, the fluctuation level in the edge region does not change significantly with neutral beam power.

Paul, S.F.; Bretz, N.; Durst, R.D.; Fonck, R.J.; Kim, Y.J.; Mazzucato, E.; Nazikian, R. (Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States))

1992-09-01T23:59:59.000Z

354

Low density, microcellular foams, preparation, and articles  

DOE Patents (OSTI)

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.

Young, A.T.

1982-03-03T23:59:59.000Z

355

NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR  

DOE Patents (OSTI)

The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

Young, G.J.

1959-06-30T23:59:59.000Z

356

Dark Energy Density in Brane World  

E-Print Network (OSTI)

We present a possible explanation to the tiny positive cosmological constant under the frame of AdS$_5$ spacetime embedded by a dS$_4$ brane. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS$_5$ spacetime. Under the assumption that the radius of AdS$_5$ spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS$_4$ brane is obtained, which is smaller than the observational value. The reasons are also discussed.

Hai-Bao Wen; Xin-Bing Huang

2005-02-08T23:59:59.000Z

357

Buffer sizing for minimum energy-delay product by using an approximating polynomial  

Science Conference Proceedings (OSTI)

This paper first presents an accurate and efficient method of estimating the short circuit energy dissipation and the output transition time of CMOS buffers. Next, the paper describes a sizing method for tapered buffer chains. It is shown that the first-order ... Keywords: buffer sizing, polynomial approximation, short circuit energy

Chang Woo Kang; Soroush Abbaspour; Massoud Pedram

2003-04-01T23:59:59.000Z

358

Use of symbolic and numeric methods in an algorithm for the approximation of multivariate functions  

Science Conference Proceedings (OSTI)

In this paper, we discuss aspects of a particular algorithm, namely that of finding an approximation to a real function of n variables, that uses both symbolic and numeric manipulations. Development of this algorithm was motivated in part by an actual ...

David K. Kahaner; Mark B. Wells

1976-08-01T23:59:59.000Z

359

Approximate k-NN delta test minimization method using genetic algorithms: Application to time series  

Science Conference Proceedings (OSTI)

In many real world problems, the existence of irrelevant input variables (features) hinders the predictive quality of the models used to estimate the output variables. In particular, time series prediction often involves building large regressors of ... Keywords: Approximate k-nearest neighbors, Delta test, Genetic algorithm, Time series, Variable projection, Variable scaling, Variable selection

Fernando Mateo; Dušan Sovilj; Rafael Gadea

2010-06-01T23:59:59.000Z

360

The estimates of approximation by using a new type of weighted modulus of continuity  

Science Conference Proceedings (OSTI)

In this paper, we introduce a new type modulus of continuity for function f belonging to a particular weighted subspace of C[0,~) and show that it has some properties of ordinary modulus of continuity. We obtain some estimates of approximation of functions ... Keywords: Beurling classes, Modulus of continuity, Positive linear operators, Weighted spaces

A. D. Gadjiev; A. Aral

2007-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Approximation of optimal moving paths of huge robot reclaimer with a 3d range finder  

Science Conference Proceedings (OSTI)

This paper proposes a simple method for approximating the optimal moving paths of a huge robot reclaimer located in the outdoor material stock yard with emphasis on safety, energy consumption, and transfer time. The reclaimer is equipped with a 3D range ...

Kwan-Hee Lee; Hyo-Jung Bae; Sung-Je Hong

2006-05-01T23:59:59.000Z

362

An approximate algorithm for the flux from a rectangular volume source  

SciTech Connect

An exact semi-analytic formula for the flux from a rectangular surface source with a slab shield has been derived and the required function table has been calculated. This formula is the basis for an algorithm which gives a good approximation for the flux from a rectangular volume source. No other hand calculation method for this source geometry is available in the literature.

Wallace, O.J.

1994-11-09T23:59:59.000Z

363

A O(1/?2)n-time sieving algorithm for approximate integer programming  

Science Conference Proceedings (OSTI)

The Integer Programming Problem (IP) for a polytope P??n is to find an integer point in P or decide that P is integer free. We give a randomized algorithm for an approximate version of this problem, ... Keywords: closest vector problem, integer programming, shortest vector problem

Daniel Dadush

2012-04-01T23:59:59.000Z

364

Approximate Equations of Motion for Compact Spinning Bodies in General Relativity  

E-Print Network (OSTI)

Approximate equations are derived for the motion of a gyroscope on the earth's gravitational field using the Einstein, Infeld, Hoffmann surface integral method. This method does not require a knowledge of the energy-momentum-stress tensor associated with the gyroscope and uses only its exterior field for its characterization. The resulting equations of motion differ from those of previous derivations.

James L. Anderson

2005-11-16T23:59:59.000Z

365

Approximation and error estimation in high dimensional space for stochastic collocation methods on arbitrary sparse samples  

Science Conference Proceedings (OSTI)

We have develop a fast method that can capture piecewise smooth functions in high dimensions with high order and low computational cost. This method can be used for both approximation and error estimation of stochastic simulations where the computations can either be guided or come from a legacy database.

Archibald, Richard K [ORNL; Deiterding, Ralf [ORNL; Hauck, Cory D [ORNL; Jakeman, John D [ORNL; Xiu, Dongbin [ORNL

2012-01-01T23:59:59.000Z

366

Approximate posterior distributions for convolutional two-level hidden Markov models  

Science Conference Proceedings (OSTI)

A convolutional two-level hidden Markov model is defined and evaluated. The bottom level contains an unobserved categorical Markov chain, and given the variables in this level the middle level contains unobserved conditionally independent Gaussian variables. ... Keywords: Approximation, Convolution, Forward-backward algorithm, Hidden Markov model, Seismic inversion

Kjartan Rimstad; Henning Omre

2013-02-01T23:59:59.000Z

367

Approximate forward-backward algorithm for a switching linear Gaussian model  

Science Conference Proceedings (OSTI)

A hidden Markov model with two hidden layers is considered. The bottom layer is a Markov chain and given this the variables in the second hidden layer are assumed conditionally independent and Gaussian distributed. The observation process is Gaussian ... Keywords: Approximation, Forward-backward algorithm, Hidden Markov model, Metropolis-Hastings algorithm, Seismic inversion

Hugo Hammer; Håkon Tjelmeland

2011-01-01T23:59:59.000Z

368

Two approximations of the present value distribution of a disability annuity  

Science Conference Proceedings (OSTI)

The distribution function of the present value of a cash flow can be approximated by means of a distribution function of a random variable, which is also the present value of a sequence of payments, but with a simpler structure. The corresponding random ... Keywords: Comonotonic joint distribution, Convex order, Multistate life insurance contracts, Present value distributions

Jaap Spreeuw

2006-02-01T23:59:59.000Z

369

Two approximations of the present value distribution of a disability annuity  

Science Conference Proceedings (OSTI)

The distribution function of the present value of a cash flow can be approximated by means of a distribution function of a random variable, which is also the present value of a sequence of payments, but with a simpler structure. The corresponding random ... Keywords: comonotonic joint distribution, convex order, multistate life insurance contracts, present value distributions

Jaap Spreeuw

2006-02-01T23:59:59.000Z

370

Optimal Policies and Approximations for a Bayesian Linear Regression Inventory Model  

Science Conference Proceedings (OSTI)

In this paper, we consider a periodic review inventory problem where demand in each period is modeled by linear regression. We use a Bayesian formulation to update the regression parameters as new information becomes available. We find that a state-dependent ... Keywords: Bayesian regression, approximations heuristics, inventory production, stochastic models

Katy S. Azoury; Julia Miyaoka

2009-05-01T23:59:59.000Z

371

Programs in Mathematica relevant to Phase Integral Approximation for coupled ODEs of the Schrödinger type  

E-Print Network (OSTI)

Three programs in Mathematica are presented, which produce expressions for the lowest order and the higher order corrections of the Phase Integral Approximation. First program is pertinent to one ordinary differential equation of the Schr\\"odinger type. The remaining two refer to a set of two such equations.

Andrzej A. Skorupski

2007-10-29T23:59:59.000Z

372

Algorithm for stochastic approximation with trial input perturbation in the nonstationary problem of optimization  

Science Conference Proceedings (OSTI)

Consideration was given to the randomized stochastic approximation algorithm with simultaneous trial input perturbation and two measurements used to optimize the unconstrained nonstationary functional. The upper boundary of the mean-square residual was ... Keywords: 02.50.Sk, 02.60.Pn

A. T. Vakhitov; O. N. Granichin; L. S. Gurevich

2009-11-01T23:59:59.000Z

373

A New 2D-Transport, 1D-Diffusion Approximation of the Boltzmann Transport equation  

Science Conference Proceedings (OSTI)

The work performed in this project consisted of the derivation, implementation, and testing of a new, computationally advantageous approximation to the 3D Boltz- mann transport equation. The solution of the Boltzmann equation is the neutron flux in nuclear reactor cores and shields, but solving this equation is difficult and costly. The new “2D/1D” approximation takes advantage of a special geometric feature of typical 3D reactors to approximate the neutron transport physics in a specific (ax- ial) direction, but not in the other two (radial) directions. The resulting equation is much less expensive to solve computationally, and its solutions are expected to be sufficiently accurate for many practical problems. In this project we formulated the new equation, discretized it using standard methods, developed a stable itera- tion scheme for solving the equation, implemented the new numerical scheme in the MPACT code, and tested the method on several realistic problems. All the hoped- for features of this new approximation were seen. For large, difficult problems, the resulting 2D/1D solution is highly accurate, and is calculated about 100 times faster than a 3D discrete ordinates simulation.

Larsen, Edward

2013-06-17T23:59:59.000Z

374

FilMINT: An Outer Approximation-Based Solver for Convex Mixed-Integer Nonlinear Programs  

Science Conference Proceedings (OSTI)

We describe a new solver for convex mixed-integer nonlinear programs (MINLPs) that implements a linearization-based algorithm. The solver is based on an algorithm of Quesada and Grossmann [Quesada, I., I. E. Grossmann. 1992. An LP/NLP based branch-and-bound ... Keywords: LP/NLP-based branch and bound, mixed-integer nonlinear programming, outer approximation

Kumar Abhishek; Sven Leyffer; Jeff Linderoth

2010-10-01T23:59:59.000Z

375

Optimal approximation of linear systems using Taguchi-sliding-based differential evolution algorithm  

Science Conference Proceedings (OSTI)

A Taguchi-sliding-based differential evolution algorithm (TSBDEA) is proposed in this study to solve the problem of optimally approximating linear systems. The TSBDEA is an approach of combining the differential evolution algorithm (DEA) with the Taguchi-sliding-level-method ... Keywords: Differential evolution algorithm, Model reduction, Taguchi sliding level method

Jinn-Tsong Tsai; Wen-Hsien Ho; Jyh-Horng Chou; Ching-Yi Guo

2011-03-01T23:59:59.000Z

376

Approximation algorithm for minimal convergecast time problem in wireless sensor networks  

Science Conference Proceedings (OSTI)

In this paper we consider how to collect data from sensors deployed in the Euclidean plane in a time-efficient way. We assume that all sensors could adjust their transmission ranges and aggregate data received from other sensors. We adopt a collision-free ... Keywords: Approximation algorithm, Convergecast, Latency, Wireless sensor networks

Weiping Shang; Pengjun Wan; Xiaodong Hu

2010-07-01T23:59:59.000Z

377

An approximate two-dimensional Riemann solver for hyperbolic systems of conservation laws  

Science Conference Proceedings (OSTI)

A two-dimensional Riemann solver is proposed for the solution of hyperbolic systems of conservation laws in two dimensions of space. The solver approximates the solution of a so-called angular two-dimensional Riemann problem as the weighted sum of the ... Keywords: Conservation laws, Godunov-type schemes, Riemann solver, Shallow-water equations, Shock waves, Source term discretization

Vincent Guinot

2005-05-01T23:59:59.000Z

378

Definition of Systematic, Approximately Separable and Modular Internal Coordinates (SASMIC) for macromolecular simulation  

E-Print Network (OSTI)

A set of rules is defined to systematically number the groups and the atoms of organic molecules and, particularly, of polypeptides in a modular manner. Supported by this numeration, a set of internal coordinates is defined. These coordinates (termed Systematic, Approximately Separable and Modular Internal Coordinates, SASMIC) are straightforwardly written in Z-matrix form and may be directly implemented in typical Quantum Chemistry packages. A number of Perl scripts that automatically generate the Z-matrix files for polypeptides are provided as supplementary material. The main difference with other Z-matrix-like coordinates normally used in the literature is that normal dihedral angles (``principal dihedrals'' in this work) are only used to fix the orientation of whole groups and a somewhat non-standard type of dihedrals, termed ``phase dihedrals'', are used to describe the covalent structure inside the groups. This physical approach allows to approximately separate soft and hard movements of the molecule using only topological information and to directly implement constraints. As an application, we use the coordinates defined and ab initio quantum mechanical calculations to assess the commonly assumed approximation of the free energy, obtained from ``integrating out'' the side chain degree of freedom chi, by the Potential Energy Surface (PES) in the protected dipeptide HCO-L-Ala-NH2. We also present a sub-box of the Hessian matrix in two different sets of coordinates to illustrate the approximate separation of soft and hard movements when the coordinates defined in this work are used.

Pablo Echenique; J. L. Alonso

2005-11-03T23:59:59.000Z

379

A two-phase approximation for model checking probabilistic unbounded until properties of probabilistic systems  

Science Conference Proceedings (OSTI)

We have developed a new approximate probabilistic model-checking method for untimed properties in probabilistic systems, expressed in a probabilistic temporal logic (PCTL, CSL). This method, in contrast to the existing ones, does not require the ... Keywords: CSL, CTMC, DTMC, PCTL

Paul Jennings; Arka P. Ghosh; Samik Basu

2012-06-01T23:59:59.000Z

380

On the applicability of the minimal configured hierarchical fuzzy control and its relevance to function approximation  

Science Conference Proceedings (OSTI)

This paper presents an approach to minimal hierarchical fuzzy control systems design. It maintains the idea of distributing behaviors inside a fuzzy structure, while the minimal hierarchical fuzzy control is an effective procedure for dealing with systems ... Keywords: ANFIS, Behavioral decomposition, Control, Design, FIS, FLU, Function approximation, Hierarchical fuzzy systems, MCANHFLS, Methodology, RMSE, TSK

Taher M. Jelleli; Adel M. Alimi

2009-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

On the Approximation of the Coriolis Terms in C-Grid Models  

Science Conference Proceedings (OSTI)

A new representation of the Coriolis terms on the Arakawa C grid is proposed. The approximation dumps the grid-scale noise that arises because of spatial averaging of the Coriolis terms when the grid spacing is larger than the deformation radius. ...

Dmitri Nechaev; Max Yaremchuk

2004-09-01T23:59:59.000Z

382

An Approximate Dynamic Programming Algorithm for Large-Scale Fleet Management: A Case Application  

Science Conference Proceedings (OSTI)

We addressed the problem of developing a model to simulate at a high level of detail the movements of over 6,000 drivers for Schneider National, the largest truckload motor carrier in the United States. The goal of the model was not to obtain a better ... Keywords: approximate dynamic programming, driver management, fleet management, truckload trucking

Hugo P. Simão; Jeff Day; Abraham P. George; Ted Gifford; John Nienow; Warren B. Powell

2009-05-01T23:59:59.000Z

383

Preprint of the paper: "Stability analysis of BEM approximate solutions in grounding analysis"  

E-Print Network (OSTI)

the grounding grid its main element. In general, most of grounding grids of electrical substations consist thrusted ground rods in certain places of the substation site. The most important parametersPreprint of the paper: "Stability analysis of BEM approximate solutions in grounding analysis" J

Colominas, Ignasi

384

Pseudo-Linear Approximations for ARX Ciphers With Application to Threefish  

E-Print Network (OSTI)

Kay and Poorvi L. Vora The George Washington University, Washington DC 20052, USA kerry@gwu.edu and poorvi examine a window (grouping of contiguous bits) of size w for w observations. First, addition modulo 2n on the window can be approximated by addition modulo 2w . Second

International Association for Cryptologic Research (IACR)

385

Approximation Algorithms for Deadline-TSP and Vehicle Routing with Time-Windows  

E-Print Network (OSTI)

Approximation Algorithms for Deadline-TSP and Vehicle Routing with Time-Windows Nikhil Bansal by their deadlines. We also consider the more general Vehicle Routing with Time- Windows problem, in which each node their "time-windows" [R(v), D(v)]. No good ap- proximations were known previously for these problems

Sheridan, Jennifer

386

Approximate eigensolutions of the deformed Woods-Saxon potential via AIM  

E-Print Network (OSTI)

By using the Pekeris approximation, the Schr\\"{o}dinger equation is solved for the nuclear deformed Woods-Saxon potential within the framework of the asymptotic iteration method (AIM). The energy levels are worked out and the corresponding normalized eigenfunctions are obtained in terms of hypergeometric function.

Sameer M. Ikhdair; Babatunde James Falaye; Majid Hamzavi

2013-07-31T23:59:59.000Z

387

On the angular defect of triangulations and the pointwise approximation of curvatures  

Science Conference Proceedings (OSTI)

Let S be a smooth surface of E3, p a point on S, km, kM, kG and kH the maximum, minimum, Gauss and mean curvatures of S at p. Consider a set {pippi+1}i ... Keywords: approximations, curvatures, differential geometry, meshes, smooth surfaces

V. Borrelli; F. Cazals; J.-M. Morvan

2003-09-01T23:59:59.000Z

388

tribution and abundance. In analysis of survey data, these results are a first approximation of correction  

E-Print Network (OSTI)

variables affecting aerial surveys, but the effects of glare on shipboard surveys and observer variabilitytribution and abundance. In analysis of survey data, these results are a first approximation conditions or animal behavior. Further work on survey methodology should examine the effect of eye height

389

Physics 116C Fall 2012 The Normal Approximation to the Binomial Distribution  

E-Print Network (OSTI)

Physics 116C Fall 2012 The Normal Approximation to the Binomial Distribution 1. Properties of the binomial distribution Consider a the binomial distribution, f(x) = C(n, x)px qn-x , where C(n, x) n! x of the binomial distribution can be computed using the follow- ing trick. Consider the binomial expansion (p + q

California at Santa Cruz, University of

390

Physics 116C Fall 2012 The Normal Approximation to the Binomial Distribution  

E-Print Network (OSTI)

Physics 116C Fall 2012 The Normal Approximation to the Binomial Distribution 1. Properties of the binomial distribution Consider a the binomial distribution, f(x) = C(n, x)p x q n-x , where C(n, x) # n! x. The expectation value of the binomial distribution can be computed using the follow­ ing trick. Consider

California at Santa Cruz, University of

391

Vibrated Bulk Density (VBD) of Calcined Petroleum Coke and ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Vibrated bulk density (VBD) is a quantitative measurement used in the aluminum industry to evaluate the density of calcined petroleum coke.

392

High Energy Density Laboratory Plasmas Program | National Nuclear...  

National Nuclear Security Administration (NNSA)

NNSA Archive Federal Employment Apply for Our Jobs Our Jobs Working at NNSA Blog High Energy Density Laboratory Plasmas Program Home > High Energy Density Laboratory Plasmas...

393

An Optimization of Electrode Energy and Power Density through...  

NLE Websites -- All DOE Office Websites (Extended Search)

An Optimization of Electrode Energy and Power Density through of Variations in Inactive Material and Electrode Porosity Title An Optimization of Electrode Energy and Power Density...

394

Probability density function method for variable-density pressure-gradient-driven turbulence and mixing  

SciTech Connect

Probability density function (PDF) methods are extended to variable-density pressure-gradient-driven turbulence. We apply the new method to compute the joint PDF of density and velocity in a non-premixed binary mixture of different-density molecularly mixing fluids under gravity. The full time-evolution of the joint PDF is captured in the highly non-equilibrium flow: starting from a quiescent state, transitioning to fully developed turbulence and finally dissipated by molecular diffusion. High-Atwood-number effects (as distinguished from the Boussinesq case) are accounted for: both hydrodynamic turbulence and material mixing are treated at arbitrary density ratios, with the specific volume, mass flux and all their correlations in closed form. An extension of the generalized Langevin model, originally developed for the Lagrangian fluid particle velocity in constant-density shear-driven turbulence, is constructed for variable-density pressure-gradient-driven flows. The persistent small-scale anisotropy, a fundamentally 'non-Kolmogorovian' feature of flows under external acceleration forces, is captured by a tensorial diffusion term based on the external body force. The material mixing model for the fluid density, an active scalar, is developed based on the beta distribution. The beta-PDF is shown to be capable of capturing the mixing asymmetry and that it can accurately represent the density through transition, in fully developed turbulence and in the decay process. The joint model for hydrodynamics and active material mixing yields a time-accurate evolution of the turbulent kinetic energy and Reynolds stress anisotropy without resorting to gradient diffusion hypotheses, and represents the mixing state by the density PDF itself, eliminating the need for dubious mixing measures. Direct numerical simulations of the homogeneous Rayleigh-Taylor instability are used for model validation.

Bakosi, Jozsef [Los Alamos National Laboratory; Ristorcelli, Raymond J [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

395

Density Functional Theory Approach to Nuclear Fission  

E-Print Network (OSTI)

The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.

N. Schunck

2012-12-13T23:59:59.000Z

396

Nonlinear spectral density estimation: thresholding the correlogram  

E-Print Network (OSTI)

in a nonlinear way. The rate of convergence of the new estimators is quantified, and practical issues estimation of the spectral density function; examples include astronomy, economics, electrical engineering Einstein (1914); see Brillinger (1993) for a historical perspective. The prevalent spectral estimation

Politis, Dimitris N.

397

Density estimation for spatial data streams  

Science Conference Proceedings (OSTI)

In this paper we study the problem of estimating several types of spatial queries in a streaming environment. We propose a new approach, which we call Local Kernels, for computing density estimators by using local rather than global statistics on the ...

Cecilia M. Procopiuc; Octavian Procopiuc

2005-08-01T23:59:59.000Z

398

Lattice QCD and High Baryon Density State  

SciTech Connect

We report our recent studies on the finite density QCD obtained from lattice QCD simulation with clover-improved Wilson fermions of two flavor and RG-improved gauge action. We approach the subject from two paths, i.e., the imaginary and chemical potentials.

Nagata, Keitaro [Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Research Institute for Information Science and Education, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Nakamura, Atsushi; Motoki, Shinji [Research Institute for Information Science and Education, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Nakagawa, Yoshiyuki [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Saito, Takuya [Integrated Information Center, Kochi University, Kochi, 780-8520 (Japan)

2011-10-21T23:59:59.000Z

399

Interferometer for the measurement of plasma density  

SciTech Connect

An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

Jacobson, Abram R. (Los Alamos, NM)

1980-01-01T23:59:59.000Z

400

Bayesian Generalized Probability Calculus for Density Matrices  

E-Print Network (OSTI)

One of the main concepts in quantum physics is a density matrix, which is a symmetric positive definite matrix of trace one. Finite probability distributions can be seen as a special case when the density matrix is restricted to be diagonal. We develop a probability calculus based on these more general distributions that includes definitions of joints, conditionals and formulas that relate these, including analogs of the Theorem of Total Probability and various Bayes rules for the calculation of posterior density matrices. The resulting calculus parallels the familiar "conventional" probability calculus and always retains the latter as a special case when all matrices are diagonal. We motivate both the conventional and the generalized Bayes rule with a minimum relative entropy principle, where the Kullbach-Leibler version gives the conventional Bayes rule and Umegaki's quantum relative entropy the new Bayes rule for density matrices. Whereas the conventional Bayesian methods maintain uncertainty about which model has the highest data likelihood, the generalization maintains uncertainty about which unit direction has the largest variance. Surprisingly the bounds also generalize: as in the conventional setting we upper bound the negative log likelihood of the data by the negative log likelihood of the MAP estimator.

Manfred K Warmuth; Dima Kuzmin

2009-01-09T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Collision frequencies in density-matrix kinetic equations describing nonlinear effects in the wings of spectral lines  

SciTech Connect

Using the eikonal approximation, we have calculated effective collision frequencies in density-matrix kinetic equations describing nonlinear effects in the wings of spectral lines. We have established the relation between the probabilities of absorption and stimulated emission and the characteristics of the radiation and elementary scattering event. The example of the power interaction potential shows that quantum mechanical calculation of the collision frequencies in the eikonal approximation and previously known spectral line wing theory give similar results for the probability of radiation absorption.

Parkhomenko, A I; Shalagin, Anatolii M [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2011-11-30T23:59:59.000Z

402

Hybrid Dynamic Density Functional Theory for Polymer Melts and Blends  

E-Print Network (OSTI)

We propose a high-speed and accurate hybrid dynamic density functional theory for the computer simulations of the phase separation processes of polymer melts and blends. The proposed theory is a combination of the dynamic self-consistent field (SCF) theory and a time-dependent Ginzburg-Landau type theory with the random phase approximation (GRPA). The SCF theory is known to be accurate in evaluating the free energy of the polymer systems in both weak and strong segregation regions although it has a disadvantage of the requirement of a considerable amount of computational cost. On the other hand, the GRPA theory has an advantage of much smaller amount of required computational cost than the SCF theory while its applicability is limited to the weak segregation region. To make the accuracy of the SCF theory and the high-performance of the GRPA theory compatible, we adjust the chemical potential of the GRPA theory by using the SCF theory every constant time steps in the dynamic simulations. The performance of the GRPA and the hybrid theories is tested by using several systems composed of an A/B homopolymer, an AB diblock copolymer, or an ABC triblock copolymer. Using the hybrid theory, we succeeded in reproducing the metastable complex phase-separated domain structures of an ABC triblock copolymer observed by experiments.

Takashi Honda; Toshihiro Kawakatsu

2006-09-05T23:59:59.000Z

403

Tests of Monte Carlo Independent Column Approximation With a Mixed-Layer Ocean Model  

NLE Websites -- All DOE Office Websites (Extended Search)

Tests of Monte Carlo Independent Column Tests of Monte Carlo Independent Column Approximation With a Mixed-Layer Ocean Model Petri Simo Järvenoja Heikki Järvinen Räisänen Finnish Meteorological Institute Figure 1. Root-mean-square sampling errors in local instant- aneous total (LW+SW) net flux at the surface and total radiative heating rate for the 1COL, CLDS, and REF approaches. Global rms values are given at the upper right hand corner of the plots. 1. Introduction The Monte Carlo Independent Column Approximation (McICA) separates the description of unresolved cloud structure from the radiative transfer solver very flexible ! unbiased with respect to ICA ! However, the radiative fluxes and heating rates contain conditional random errors ("McICA noise"). ? The topic of this poster: All previous tests of McICA

404

Low-frequency plasma conductivity in the average-atom approximation  

E-Print Network (OSTI)

Low-frequency properties of a plasma are examined within the average-atom approximation, which presumes that scattering of a conducting electron on each atom takes place independently of other atoms. The relaxation time tau distinguishes a high-frequency region omega tau > 1, where the single-atom approximation is applicable explicitly, from extreme low frequencies omega tau 1, reproducing the Ziman formula in the static limit, results based on the Kubo-Greenwood formula for high frequencies, and satisfying the conductivity sum-rule precisely. The correspondence between physical processes leading to the conventional Ohm's law and the infrared properties of QED is discussed. The suggested average-atom approach to frequency-dependent conductivity is illustrated by numerical calculations for the an aluminum plasma in the temperature range 2--10 eV.

Kuchiev, M Yu

2008-01-01T23:59:59.000Z

405

Probing the nonlocal approximation to resonant collisions ofelectrons with diatomic molecules  

SciTech Connect

A numerically solvable two-dimensional model introduced bythe authors [Phys. Rev. A 73, 032721 (2006)]is used to investigate thevalidity of the nonlocal approximation to the dynamics of resonantcollisions of electrons with diatomic molecules. The nonlocalapproximation to this model is derived in detail, all underlyingassumptions are specified and explicit expressions for the resonant andnon-resonant (background) T matrix for the studied processes are given.Different choices of the so-called discrete state, which fully determinesthe nonlocal approximation, are discussedand it is shown that a physicalchoice of this state can in general give poorer results than otherchoices that minimize the non-adiabatic effects and/or the backgroundterms of the T matrix. The background contributions to the crosssections, which are usually not considered in the resonant theory ofelectron-molecule collisions, can be significant not only for elasticscattering but also for the inelastic process of vibrationalexcitation.

Houfek, Karel; Rescigno, Thomas N.; McCurdy, C. William

2007-09-07T23:59:59.000Z

406

B-Spline Surface Approximation to Cross-Sections Using Distance Maps  

E-Print Network (OSTI)

this paper, we present a method of surface approximation to cross-sections with multiple branching problems. In this method, we first decompose each multiple branching problem into a set of single branching problems by providing a set of intermediate contours using distance maps. For each single branching region, a procedure then performs the skinning of contour curves represented by cubic B-spline curves on a common knot vector, each of which is fitted to its contour points within a given accuracy. In order to acquire a more compact representation for the surface, the method includes an algorithm for reducing the number of knots in the common knot vector. The approximation surface to the crosssections is represented by a set of bicubic B-spline surfaces. This method provides a smooth surface model, yet realises efficient data reduction.

J. Jeong; K. Kim; H. Park; H. Cho; M. Jung

1999-01-01T23:59:59.000Z

407

LinguisticBelief: a java application for linguistic evaluation using belief, fuzzy sets, and approximate reasoning.  

Science Conference Proceedings (OSTI)

LinguisticBelief is a Java computer code that evaluates combinations of linguistic variables using an approximate reasoning rule base. Each variable is comprised of fuzzy sets, and a rule base describes the reasoning on combinations of variables fuzzy sets. Uncertainty is considered and propagated through the rule base using the belief/plausibility measure. The mathematics of fuzzy sets, approximate reasoning, and belief/ plausibility are complex. Without an automated tool, this complexity precludes their application to all but the simplest of problems. LinguisticBelief automates the use of these techniques, allowing complex problems to be evaluated easily. LinguisticBelief can be used free of charge on any Windows XP machine. This report documents the use and structure of the LinguisticBelief code, and the deployment package for installation client machines.

Darby, John L.

2007-03-01T23:59:59.000Z

408

Coupled-cluster method: A lattice-path-based subsystem approximation scheme for quantum lattice models  

Science Conference Proceedings (OSTI)

An approximation hierarchy, called the lattice-path-based subsystem (LPSUBm) approximation scheme, is described for the coupled-cluster method (CCM). It is applicable to systems defined on a regular spatial lattice. We then apply it to two well-studied prototypical (spin-(1/2) Heisenberg antiferromagnetic) spin-lattice models, namely, the XXZ and the XY models on the square lattice in two dimensions. Results are obtained in each case for the ground-state energy, the ground-state sublattice magnetization, and the quantum critical point. They are all in good agreement with those from such alternative methods as spin-wave theory, series expansions, quantum Monte Carlo methods, and the CCM using the alternative lattice-animal-based subsystem (LSUBm) and the distance-based subsystem (DSUBm) schemes. Each of the three CCM schemes (LSUBm, DSUBm, and LPSUBm) for use with systems defined on a regular spatial lattice is shown to have its own advantages in particular applications.

Bishop, R. F.; Li, P. H. Y. [School of Physics and Astronomy, Schuster Building, University of Manchester, Manchester M13 9PL (United Kingdom)

2011-04-15T23:59:59.000Z

409

Time-dependent Generalized SIC-OEP formalism and Generalized SIC-Slater approximation  

E-Print Network (OSTI)

We propose a simplification of the full "2 sets" Time dependent Self Interaction Correction (TD-SIC) method, applying the Optimized Effective Potential (OEP) method. The new resulting scheme is called time-dependent "Generalized SIC-OEP". A straightforward approximation, using the spatial localization of one set of orbitals, leads to the "Generalized SIC-Slater" formalism. We show that it represents a great improvement compared to the traditional SIC-Slater/KLI formalisms.

Messud, J; Reinhard, P -G; Suraud, E

2009-01-01T23:59:59.000Z

410

Time-dependent Generalized SIC-OEP formalism and Generalized SIC-Slater approximation  

E-Print Network (OSTI)

We propose a simplification of the full "2 sets" Time dependent Self Interaction Correction (TD-SIC) method, applying the Optimized Effective Potential (OEP) method. The new resulting scheme is called time-dependent "Generalized SIC-OEP". A straightforward approximation, using the spatial localization of one set of orbitals, leads to the "Generalized SIC-Slater" formalism. We show that it represents a great improvement compared to the traditional SIC-Slater/KLI formalisms.

J. Messud; P. M. Dinh; P. -G. Reinhard; E. Suraud

2009-08-06T23:59:59.000Z

411

Two-photon approximation in the theory of electron recombination in hydrogen  

Science Conference Proceedings (OSTI)

A rigorous quantum electrodynamics theory of the multiphoton decay of excited states in a hydrogen atom is presented. The ''two-photon'' approximation is formulated which is limited by the one- and two-photon transitions including cascade transitions with two-photon links. This may be helpful for the strict description of the recombination process in a hydrogen atom and, in principle, for the history of hydrogen recombination in the early universe.

Solovyev, D. [V. A. Fock Institute of Physics, St. Petersburg State University, Petrodvorets, Oulianovskaya 1, 198504 St. Petersburg (Russian Federation); Labzowsky, L. [V. A. Fock Institute of Physics, St. Petersburg State University, Petrodvorets, Oulianovskaya 1, 198504 St. Petersburg (Russian Federation); Petersburg Nuclear Physics Institute, Gatchina, 188300 St. Petersburg (Russian Federation)

2010-06-15T23:59:59.000Z

412

Geophysical imaging method utilizing backpropagation and zeroth-order phase approximation  

DOE Patents (OSTI)

A method is provided for determining, under field conditions and in near-real time, an image of a geophysical objective under the ground in a geophysical medium, utilizing a zeroth order phase approximation implemented with first signal-to-detector arrival times for a plurality of signal transmitters transmitting signals through the geologic medium and the geologic objective to a plurality of signal receivers, disposed adjacent to the geologic objective in a predetermined manner. 9 figs.

Witten, A.J.

1989-09-12T23:59:59.000Z

413

Approximations of the operator exponential in a periodic diffusion problem with drift  

SciTech Connect

A Cauchy problem for a parabolic diffusion equation with 1-periodic coefficients containing first order terms is studied. For the corresponding semigroup we construct approximations in the L{sup 2}-operator norm on sections t=const of order O(t{sup -m/2}) as t{yields}{infinity} for m=1 or m=2. The spectral method based on the Bloch representation of an operator with periodic coefficients is used. Bibliography: 25 titles.

Pastukhova, Svetlana E [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)] [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

2013-02-28T23:59:59.000Z

414

Approximate analytical solutions for nonlinear Emden-Fowler type equations by differential transform method  

E-Print Network (OSTI)

In this paper, approximate analytical solutions of nonlinear Emden-Fowler type equations are obtained by the differential transform method (DTM). The DTM is a numerical as well as analytical method for solving integral equations, ordinary and partial diferential equations. To show the efficiency of the DTM, some examples are presented. Comparisons with exact solution show that the DTM is a powerful method for the solution of the nonlinear Emden-Fowler type equations.

Birol Ibis

2012-11-15T23:59:59.000Z

415

Magnetic state of K0.8Fe1.6Se2 from a five-orbital Hubbard model in the Hartree-Fock approximation  

SciTech Connect

Motivated by the recent discovery of Fe-based superconductors close to an antiferromagnetic insulator in the experimental phase diagram, here the five-orbital Hubbard model (without lattice distortions) is studied using the real-space Hartree-Fock approximation, employing a 10 10 Fe cluster with Fe vacancies in a5 5 pattern. Varying the Hubbard and Hund couplings, and at electronic density n = 6.0, the phase diagram contains an insulating state with the same spin pattern as observed experimentally, involving 2 2 ferromagnetic plaquettes coupled with one another antiferromagnetically. The presence of local ferromagnetic tendencies is in qualitative agreement with Lanczos results for the three-orbital model also reported here. The magnetic moment 3 B /Fe is in good agreement with experiments. Several other phases are also stabilized in the phase diagram, in agreement with recent calculations using phenomenological models.

Luo, Qinlong [ORNL; Nicholson, Andrew D [ORNL; Riera, J. A. [Universidad Nacional de Rosario; Yao, Dao-Xin [Sun Yat-Sen University, Guangzhou, China; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL

2011-01-01T23:59:59.000Z

416

The development of an approximate dynamic analysis of insulating glass units  

E-Print Network (OSTI)

The goal of this thesis is to develop an approximate dynamic analysis of sealed insulating glass (IG) units subject to uniform blast loads, the formulation of which will be incorporated into a computer program that will be used as a tool to estimate their dynamic response. The formulation of this approximate dynamic analysis of IG units is achieved by modeling the unit with two equivalent single degree of freedom systems consisting of equivalent masses, equivalent structural stiffnesses, equivalent forces, and by incorporating air space compatibility relationships into this model. The equations of motion which define the behavior of this dynamic model are incorporated into a computer program that computes the dynamic response of an IG unit subjected to a prescribed blast loading. This response includes the displacements, velocities, and accelerations of the glass plates of the IG unit. The blast loading will be idealized in order to simplify the analysis. The program will approximate the positive pressure phase of a blast load with an equivalent triangular loading. IG units designed by existing methods will be analyzed using the program, and their performance evaluated. This analysis will not only provide valuable data on the behavior of the IG units to blast loadings, but will lend insight into the acceptability of the existing design approach. The results will also indicate the acceptability of the technique developed in this thesis as a tool in the design and analysis of IG units subject to blast loads.

Sequeira, Miguel Angel

1995-01-01T23:59:59.000Z

417

PROCESS FOR IMPROVING THE ENERGY DENSITY OF FEEDSTOCKS USING ...  

PROCESS FOR IMPROVING THE ENERGY DENSITY OF FEEDSTOCKS USING FORMATE SALTS United States Patent Application

418

On the density of a graph and its blowup  

Science Conference Proceedings (OSTI)

It is well known that, of all graphs with edge-density p, the random graph G(n,p) contains the smallest density of copies of K"t","t, the complete bipartite graph of size 2t. Since K"t","t is a t-blowup of an edge, the following intriguing open question ... Keywords: Blowup, Graph density, Triangle density

Asaf Shapira; Raphael Yuster

2010-11-01T23:59:59.000Z

419

Electronic structure calculations with the Tran-Blaha modified Becke-Johnson Density Functional  

Science Conference Proceedings (OSTI)

We report a series of calculations testing the predictions of the Tran-Blaha functional for the electronic structure and magnetic properties of condensed systems. We find a general improvement in the properties of semiconducting and insulating systems, relative to calculations with standard generalized gradient approximations, although this is not always by the same mechanism as other approaches such as the quasiparticle GW method. In ZnO the valence bands are narrowed and the band gap is increased to a value in much better agreement with experiment. The Zn d states do not move to higher binding energy as they do in local-density approximation+U calculations. The functional is effective for systems with hydride anions, where correcting self-interaction errors in the 1s state is important. Similarly, it correctly opens semiconducting gaps in the alkaline-earth hexaborides. It correctly stabilizes an antiferromagnetic insulating ground state for the undoped cuprate parent CaCuO{sub 2}, but seriously degrades the agreement with experiment for ferromagnetic Gd relative to the standard local-spin-density approximation and generalized gradient approximations. This is due to positioning of the minority-spin 4f states at too low an energy. Conversely, the position of the La 4f conduction bands of La{sub 2}O{sub 3} is in reasonable accord with experiment as it is with standard functionals. The functional narrows the Fe d bands of the parent compound LaFeAsO of the iron high-temperature superconductors while maintaining the high Fe spectral weight near the Fermi energy.

Singh, David J [ORNL

2010-01-01T23:59:59.000Z

420

Kinetics driving high-density chlorine plasmas  

Science Conference Proceedings (OSTI)

A simple fluid model was developed in order to investigate the driving kinetics of neutral and charged species in high-density chlorine plasmas. It was found that the dissociation degree of Cl{sub 2} molecules is directly linked to the power balance of the discharge which controls the electron density. The model was also used to identify those reactions that could be neglected in the particle balance of charged species and those that must be included. Our results further indicate that diffusion losses need to be considered up to a pressure that depends on magnetic-field intensity and reactor aspect ratio. Finally, it is shown that the dominant charged carriers are linked to the dissociation level of Cl{sub 2} molecules.

Stafford, L.; Margot, J.; Vidal, F.; Chaker, M.; Giroux, K.; Poirier, J.-S.; Quintal-Leonard, A.; Saussac, J. [Department de physique, Universite de Montreal, Montreal, Quebec (Canada); INRS-Energie, Materiaux et Telecommunications, Varennes, Quebec (Canada); Department de physique, Universite de Montreal, Montreal, Quebec (Canada)

2005-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Turbulent Density Spectrum in Solar Wind Plasma  

E-Print Network (OSTI)

The density fluctuation spectrum in the solar wind reveals a Kolmogorov-like scaling with a spectral slope of -5/3 in wavenumber space. The energy transfer process in the magnetized solar wind, characterized typically by MHD turbulence, over extended length-scales remains an unresolved paradox of modern turbulence theories, raising the question of how a compressible magnetofluid exhibits a turbulent spectrum that is characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfv\\'enic, supersonic and strongly magnetized plasma fluid. It is shown that a Kolmogorov-like density spectrum can develop by plasma motions that are dominated by Alfv\\'enic cascades whereas compressive modes are dissipated.

Shaikh, Dastgeer

2009-01-01T23:59:59.000Z

422

Density Spectrum in the Solar Wind Plasma  

E-Print Network (OSTI)

The density fluctuation spectrum in the solar wind reveals a Kolmogorov-like scaling with a spectral slope of -5/3 in wavenumber space. The energy transfer process in the magnetized solar wind, characterized typically by MHD turbulence, over extended length-scales remains an unresolved paradox of modern turbulence theories, raising the question of how a compressible magnetofluid exhibits a turbulent spectrum that is characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfv\\'enic, supersonic and strongly magnetized plasma fluid. It is shown that a Kolmogorov-like density spectrum can develop by plasma motions that are dominated by Alfv\\'enic cascades whereas compressive modes are dissipated.

Shaikh, Dastgeer

2009-01-01T23:59:59.000Z

423

Single stage to orbit mass budgets derived from propellant density and specific impulse  

DOE Green Energy (OSTI)

The trade between specific impulse (Isp) and density is examined in view of Single Stage To Orbit (SSTO) requirements. Mass allocations for vehicle hardware are derived from these two properties, for several propellant combinations and a dual-fuel case. This comparative analysis, based on flight-proven hardware, indicates that the higher density of several alternative propellants compensates for reduced Isp, when compared with cryogenic oxygen and hydrogen. Approximately half the orbiting mass of a rocket- propelled SSTO vehicle must be allocated to propulsion hardware and residuals. Using hydrogen as the only fuel requires a slightly greater fraction of orbiting mass for propulsion, because hydrogen engines and tanks are heavier than those for denser fuels. The advantage of burning both a dense fuel and hydrogen in succession depends strongly on tripropellant engine weight. The implications of the calculations for SSTO vehicle design are discussed, especially with regard to the necessity to minimize non-tankage structure.

Whitehead, J.C.

1996-06-06T23:59:59.000Z

424

Complete density perturbations in the Jordan-Fierz-Brans-Dicke theory  

E-Print Network (OSTI)

In the context of scalar-tensor theories we study the evolution of the density contrast for Jordan-Fierz-Brans-Dicke theories in a Friedmann-Lemaitre-Robertson-Walker Universe. Calculations are performed in the Einstein Frame with the cosmological background described as Lambda-Cold Dark Matter (Lambda-CDM) and supplemented by a Jordan-Fierz-Brans-Dicke field. By using a completely general procedure valid for all scalar-tensor theories, we obtain the exact fourth-order differential equation for the density contrast evolution in modes of arbitrary size. In the case of sub-Hubble modes, the expression reduces to a simpler but still fourth-order equation that is then compared with the standard (quasistatic) approximation. Differences with respect to the evolution as predicted by the standard Concordance Lambda-CDM model are observed depending on the value of the coupling.

J. A. R. Cembranos; A. de la Cruz Dombriz; L. Olano Garcia

2013-07-01T23:59:59.000Z

425

Ferromagnetism in GaN: Gd: A density functional theory study  

SciTech Connect

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.

Stevenson, Cynthia; Stevenson, Cynthia

2008-02-04T23:59:59.000Z

426

Excitation density distribution in electron-beam-pumped ZnSe semiconductor lasers  

Science Conference Proceedings (OSTI)

The spatial density distribution of the absorbed energy in ZnSe semiconductor lasers excited by electrons with energies from 2 keV to 1 MeV is calculated by the Monte-Carlo method. Approximate analytic expressions determining the absorbed energy of electrons in ZnSe are presented. The pump power threshold in a semiconductor quantum-well ZnSe structure is experimentally determined. The lasing threshold in such structures is estimated as a function of the electron energy. (active media)

Donskoi, E N; Zalyalov, A N; Petrushin, O N; Savel'ev, Yu A; Tarasov, M D; Shigaev, Yu S [Russian Federal Nuclear Center 'All-Russian Scientific Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod Region (Russian Federation); Zhdanova, E V; Zverev, M M; Peregudov, D V [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation); Ivanov, S V; Sedova, I V; Sorokin, S V [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

2008-12-31T23:59:59.000Z

427

Mapping densities in a noisy state space  

E-Print Network (OSTI)

Weak noise smooths out fractals in a chaotic state space and introduces a maximum attainable resolution to its structure. The balance of noise and deterministic stretching/contraction in each neighborhood introduces local invariants of the dynamics that can be used to partition the state space. We study the local discrete-time evolution of a density in a two-dimensional hyperbolic state space, and use the asymptotic eigenfunctions for the noisy dynamics to formulate a new state space partition algorithm.

Domenico Lippolis

2013-03-05T23:59:59.000Z

428

Nuclear fission in covariant density functional theory  

E-Print Network (OSTI)

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.

A. V. Afanasjev; H. Abusara; P. Ring

2013-09-12T23:59:59.000Z

429

Lipoprotein subclass analysis by immunospecific density  

E-Print Network (OSTI)

Apolipoprotein C-1 (apo C-1) enriched HDL has been described as an atherogenic form of HDL associated with an increased risk for cardiovascular disease (CVD). The objective of the present study was to develop a rapid method for the separation, purification, and characterization of Apo C-1 from serum. We isolated and characterize HDL subclasses from individuals with and without angiographically-proven CVD who have elevated and normal-to-low HDL-C levels. Ultracentrifugation was linked with immunoaffinity separations for the specific separation of Apo C-1 enriched HDL from other lipoproteins. A 50 ?L sample of serum is diluted in TRIS HCl buffer (pH 7.5) and incubated with CNBr-activated Sepharose (Amersham) containing antibodies to apo C-1 (Academy Bio-medical Company). The apo C-1-depleted serum is removed by centrifugation and all apo C-1-containing lipoproteins are released from the Sepharose beads at pH 2. The apo C-1-depleted sample and the apo C-1-containing sample were ultracentrifuged 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 HDL. An additional advantage of this approach is that lipoprotein-a (Lp(a)), which is often an interfering component in the HDL density region, is eliminated. Results show feasibility that these methods could be used in a clinical setting, was achieved. This measurement may yield a precise and quantitative profile of the distribution of apo C-1 for all lipoprotein particles including HDL.

Lester, Sandy Marie

2008-12-01T23:59:59.000Z

430

High Energy Density Utracapacitors: Low-Cost, High Energy and Power Density, Nanotube-Enhanced Ultracapacitors  

Science Conference Proceedings (OSTI)

Broad Funding Opportunity Announcement Project: FastCAP is improving the performance of an ultracapacitor—a battery-like electronic device that can complement, and possibly even replace, an HEV or EV battery pack. Ultracapacitors have many advantages over conventional batteries, including long lifespans (over 1 million cycles, as compared to 10,000 for conventional batteries) and better durability. Ultracapacitors also charge more quickly than conventional batteries, and they release energy more quickly. However, ultracapacitors have fallen short of batteries in one key metric: energy density—high energy density means more energy storage. FastCAP is redesigning the ultracapacitor’s internal structure to increase its energy density. Ultracapacitors traditionally use electrodes made of irregularly shaped, porous carbon. FastCAP’s ultracapacitors are made of tiny, aligned carbon nanotubes. The nanotubes provide a regular path for ions moving in and out of the ultracapacitor’s electrode, increasing the overall efficiency and energy density of the device.

None

2010-04-01T23:59:59.000Z

431

The string of variable density: Further results  

Science Conference Proceedings (OSTI)

We analyze the problem of calculating the solutions and the spectrum of a string with arbitrary density and fixed ends. We build a perturbative scheme which uses a basis of WKB-type functions and obtain explicit expressions for the eigenvalues and eigenfunctions of the string. Using this approach we show that it is possible to derive the asymptotic (high energy) behavior of the string, obtaining explicit expressions for the first three coefficients (the first two can also be obtained with the WKB method). Finally, using an iterative approach we also obtain analytical expressions for the low energy behavior of the eigenvalues and eigenfunctions of a string with rapidly oscillating density, recovering (in a simpler way) results in the literature. - Highlights: > We devise a perturbative approach to finding the modes of a string with arbitrary density. > We obtain explicitly the first three coefficients of the asymptotic high energy expansion. > We apply our findings to a series of examples, obtaining both analytical and numerical results.

Amore, Paolo, E-mail: paolo.amore@gmail.com

2011-09-15T23:59:59.000Z

432

Energy trapping from Hagedorn densities of states  

E-Print Network (OSTI)

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.

Connor Behan; Klaus Larjo; Nima Lashkari; Brian Swingle; Mark Van Raamsdonk

2013-04-26T23:59:59.000Z

433

Metastable liquid-liquid coexistence and density anomalies in a core-softened fluid  

E-Print Network (OSTI)

Linearly-sloped or `ramp' potentials belong to a class of core-softened models which possess a liquid-liquid critical point (LLCP) in addition to the usual liquid-gas critical point. Furthermore they exhibit thermodynamic anomalies in the density and compressibility, the nature of which may be akin to those occurring in water. Previous simulation studies of ramp potentials have focused on just one functional form, for which the LLCP is thermodynamically stable. In this work we construct a series of ramp potentials, which interpolate between this previously studied form and a ramp-based approximation to the Lennard-Jones (LJ) potential. By means of Monte Carlo simulation, we locate the LLCP, the first order high density liquid (HDL)-low density liquid (LDL) coexistence line, and the line of density maxima for a selection of potentials in the series. We observe that as the LJ limit is approached, the LLCP becomes metastable with respect to freezing into a hexagonal close packed crystalline solid. The qualitative nature of the phase behaviour in this regime shows a remarkable resemblance to that seen in simulation studies of accurate water models. Specifically, the density of the liquid phase exceeds that of the solid; the gradient of the metastable LDL-HDL line is negative in the pressure (p)-temperature (T) plane; while the line of density maxima in the p-T plane has a shape similar to that seen in water and extends well into the {\\em stable} liquid region of the phase diagram. As such, our results lend weight to the `second critical point' hypothesis as an explanation for the anomalous behaviour of water.

Helen M. Gibson; Nigel B. Wilding

2006-01-20T23:59:59.000Z

434

Breakdown of the linear approximation in the perturbative analysis of heat conduction in relativistic systems  

E-Print Network (OSTI)

We analyze the effects of thermal conduction in a relativistic fluid just after its departure from spherical symmetry, on a time scale of the order of relaxation time. Using first order perturbation theory, it is shown that, as in spherical systems, at a critical point the effective inertial mass density of a fluid element vanishes and becomes negative beyond that point. The impact of this effect on the reliability of causality conditions is discussed.

L. Herrera; A. Di Prisco; J. Martinez

1998-03-25T23:59:59.000Z

435

Size-Resolved Density Measurements of Particulate Emissions from an Advanced Combustion Diesel Engine: Effect of Aggregate Morphology  

Science Conference Proceedings (OSTI)

We report the first in situ size-resolved density measurements of particles produced by premixed charge compression ignition (PCCI) and compare these with conventional diesel particles. The densities of size-classified particles were determined by measurements with a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). Particle masses of the different size classes were evaluated with a proposed DMA-APM response function for aggregates. Our results indicate that the effective densities of PCCI and conventional diesel particles were approximately the same for 50 and 100 nm electrical mobility diameters (0.9 and 0.6 g/cc, respectively), but the PCCI particle effective density (0.4 g/cc) was less than the conventional (0.5 g/cc) for 150 nm. The lowest effective particle densities were observed for exhaust gas recirculation (EGR) levels somewhat less than that required for PCCI operation. The inherent densities of conventional particles in the 50 and 100 nm size classes were 1.22 and 1.77 g/cc, which is in good agreement with Park et al. (2004). PCCI inherent particle densities for these same size classes were higher (1.27 and 2.10 g/cc), suggesting that there may have been additional adsorbed liquid hydrocarbons. For 150 nm particles, the inherent densities were nearly the same for PCCI and conventional particles at 2.20 g/cc. We expect that the lower effective density of PCCI particles may improve particulate emissions control with diesel particulate filters (DPFs). The presence of liquid hydrocarbons may also promote oxidation in DPFs.

Barone, Teresa L [ORNL; Storey, John Morse [ORNL; Prikhodko, Vitaly Y [ORNL; Parks, II, James E [ORNL

2011-01-01T23:59:59.000Z

436

AN EFFICIENT APPROXIMATION OF THE CORONAL HEATING RATE FOR USE IN GLOBAL SUN–HELIOSPHERE SIMULATIONS  

E-Print Network (OSTI)

The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun–heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent one-dimensional models have been found to reproduce many observed features of the solar wind by assuming the energy comes from Alfvén waves that are partially reflected, then dissipated by magnetohydrodynamic turbulence. However, the nonlocal physics of wave reflection has made it difficult to apply these processes to more sophisticated (three-dimensional) models. This paper presents a set of robust approximations to the solutions of the linear Alfvén wave reflection equations. A key ingredient of the turbulent heating rate is the ratio of inward-to-outward wave power, and the approximations developed here allow this to be written explicitly in terms of local plasma properties at any given location. The coronal heating also depends on the frequency spectrum of Alfvén waves in the open-field corona, which has not yet been measured directly. A modelbased assumption is used here for the spectrum, but the results of future measurements can be incorporated easily. The resulting expression for the coronal heating rate is self-contained, computationally efficient, and applicable directly to global models of the corona and heliosphere. This paper tests and validates the approximations by comparing the results to exact solutions of the wave transport equations in several cases relevant to the fast and slow solar wind. Key words: interplanetary medium – magnetohydrodynamics (MHD) – solar wind – Sun: corona – turbulence – waves Online-only material: tar file of source code 1.

Steven R. Cranmer

2010-01-01T23:59:59.000Z

437

When is the two-level approximation untenable in issues of Decoherence?  

E-Print Network (OSTI)

We examine the conditions in favor and necessity of a realistic multileveled description of a decohering quantum system. Under these conditions approximate techniques to simplify a multileveled system by its first two levels is unreliable and a realistic multilevel description in the formulation of decoherence is unavoidable. In this regard, our first crucial observation is that, the validity of the two level approximation of a multileveled system is not controlled purely by {\\it sufficiently low temperatures}. We demonstrate using three different environmental spectral models that the type of system-environment coupling and the environmental spectrum have a dominant role over the temperature. Particularly, zero temperature quantum fluctuations induced by the Caldeira-Leggett type linear coordinate coupling can be influential in a wide energy range in the systems allowed transitions. The second crucial observation against the validity of the two level approximation is that the decoherence times being among the system's short time scales are found to be dominated not by the resonant but {\\it non-resonant} processes. We demonstrate this in three stages. Firstly, our zero temperature numerical calculations reveal that, the calculated decoherence rates including relaxation, dephasing and leakage phenomena show, a linear dependence on the spectral area for all spectral models used, independent from the spectral shape within a large environmental spectral range compared to the quantum system's energies. Secondly, within the same range, the decoherence times only have a marginal dependence on the translations of the entire frequency spectrum. Finally, the same decoherence rates show strong dependence on the number of coupled levels by the system-environment coupling.

Kerim Savran; Tugrul Hakioglu; Emine Mese

2004-06-22T23:59:59.000Z

438

Parallel FE Approximation of the Even/Odd Parity Form of the Linear Boltzmann Equation  

Science Conference Proceedings (OSTI)

A novel solution method has been developed to solve the linear Boltzmann equation on an unstructured triangular mesh. Instead of tackling the first-order form of the equation, this approach is based on the even/odd-parity form in conjunction with the conventional mdtigroup discrete-ordinates approximation. The finite element method is used to treat the spatial dependence. The solution method is unique in that the space-direction dependence is solved simultaneously, eliminating the need for the conventional inner iterations, and the method is well suited for massively parallel computers.

Drumm, Clifton R.; Lorenz, Jens

1999-07-21T23:59:59.000Z

439

Post-quasistatic approximation as a test bed for numerical relativity  

Science Conference Proceedings (OSTI)

It is shown that observers in the standard ADM 3+1 treatment of matter are the same as the observers used in the matter treatment of Bondi: they are comoving and local Minkowskian. Bondi's observers are the basis of the post-quasistatic approximation (PQSA) to study a contracting distribution of matter. This correspondence suggests the possibility of using the PQSA as a test bed for numerical relativity. The treatment of matter by the PQSA and its connection with the ADM 3+1 treatment are presented, for its practical use as a calibration tool and as a test bed for numerical relativistic hydrodynamic codes.

Barreto, W. [Centro de Fisica Fundamental, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of)

2009-05-15T23:59:59.000Z

440

p-barp-Annihilation processes in the tree approximation of SU(3) chiral effective theory  

Science Conference Proceedings (OSTI)

The p-barp-annihilation reactions p-barp {yields} {eta}{eta} {eta} and p-barp {yields} {eta}KK-bar at rest are considered in the tree approximation in the framework of SU(3) chiral effective theory at leading order. The calculated branchings are compared with the data. The results for neutral ({eta}{eta}{eta}, K{sup 0}K-bar{sup 0}{sub {eta}}) and charged (K{sup +}K{sup -}{sub {eta}}) channels are essentially different.

Tarasov, V. E.; Kudryavtsev, A. E., E-mail: kudryavt@itep.ru; Romanov, A. I.; Weinberg, V. M. [Institute of Theoretical and Experimental Physics (Russian Federation)

2012-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Approximate Integrals of rf-driven Particle Motion in Magnetic Field  

DOE Green Energy (OSTI)

For a particle moving in nonuniform magnetic field under the action of an rf wave, ponderomotive effects result from rf-driven oscillations nonlinearly coupled with Larmor rotation. Using Lagrangian and Hamiltonian formalism, we show how, despite this coupling, two independent integrals of the particle motion are approximately conserved. Those are the magnetic moment of free Larmor rotation and the quasi-energy of the guiding center motion parallel to the magnetic field. Under the assumption of non-resonant interaction of the particle with the rf field, these integrals represent adiabatic invariants of the particle motion.

I.Y. Dodin; N.J. Fisch

2004-04-26T23:59:59.000Z

442

Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density  

NLE Websites -- All DOE Office Websites (Extended Search)

1: February 7, 1: February 7, 2011 Population Density to someone by E-mail Share Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on Facebook Tweet about Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on Twitter Bookmark Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on Google Bookmark Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on Delicious Rank Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on Digg Find More places to share Vehicle Technologies Office: Fact #661: February 7, 2011 Population Density on AddThis.com... Fact #661: February 7, 2011 Population Density The density of the population in the U.S., measured as the number of people

443

Symmetry energy in nuclear density functional theory  

E-Print Network (OSTI)

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.

W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar

2013-07-22T23:59:59.000Z

444

Symmetry energy in nuclear density functional theory  

E-Print Network (OSTI)

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.

Nazarewicz, W; Satula, W; Vretenar, D

2013-01-01T23:59:59.000Z

445

Optimal Design of Transonic Fan Blade Leading Edge Shape Using CFD and Simultaneous Perturbation Stochastic Approximation Method  

E-Print Network (OSTI)

Simultaneous Perturbation Stochastic Approximation method has attracted considerable application in many different areas such as statistical parameter estimation, feedback control, simulation-based optimization, signal & ...

Xing, X.Q.

446

Some numerical reslts on best uniform polynomial approximation of. chi. sup. alpha. on (0,1)  

Science Conference Proceedings (OSTI)

Let {alpha} be a positive number, and let E{sub n}(chi{sup {alpha}}; (0,1)) denote the error of best uniform approximation to {chi}{sup {alpha}}, by polynomials of degree at most n, on the interval (0,1). The Russian mathematician S.N. Bernstein established the existence of a nonnegative constant {Beta}({alpha}) such that {Beta}({alpha}):= {sub n{yields}{infinity}lim(2n){sup 2{alpha}}E{sub n}({chi}{sup {alpha}};(0.1)). In addition, Bernstein showed that {Beta}{alpha} 0) and that {Gamma}(2{alpha}){vert bar}sin({pi}{alpha}){vert bar}/{pi} (1{minus}1/2{alpha}{minus}1) {1/2}), so that the asymptotic behavior of {Beta}({alpha}) is known when {alpha}{yields}{infinity}. Still, the problem of trying to determine {Beta}({alpha}) more precisely, for all {alpha} > 0, is intriguing. To this end, we have rigorously determined the numbers for thirteen values of {alpha}, where these numbers were calculated with a precision of at least 200 significant digits. For each of these thirteen values of {alpha}, Richardson's extrapolation was applied to the products to obtain estimates of {Beta}({alpha}) to approximately 40 decimal places. Included are graphs of the points ({alpha},{Beta}({alpha})) for the thirteen values of {alpha} that we considered.

Carpenter, A.J.; Varga, R.S.

1992-01-01T23:59:59.000Z

447

Some numerical reslts on best uniform polynomial approximation of. chi. sup. alpha. on (0,1)  

SciTech Connect

Let {alpha} be a positive number, and let E{sub n}(chi{sup {alpha}}; (0,1)) denote the error of best uniform approximation to {chi}{sup {alpha}}, by polynomials of degree at most n, on the interval (0,1). The Russian mathematician S.N. Bernstein established the existence of a nonnegative constant {Beta}({alpha}) such that {Beta}({alpha}):= {sub n{yields}{infinity}lim(2n){sup 2{alpha}}E{sub n}({chi}{sup {alpha}};(0.1)). In addition, Bernstein showed that {Beta}{alpha} < {Gamma}(2{alpha}){vert bar}sin(pi}{alpha}){vert bar}/{pi} ({alpha} > 0) and that {Gamma}(2{alpha}){vert bar}sin({pi}{alpha}){vert bar}/{pi} (1{minus}1/2{alpha}{minus}1) < {Beta}({alpha}) ({alpha} > {1/2}), so that the asymptotic behavior of {Beta}({alpha}) is known when {alpha}{yields}{infinity}. Still, the problem of trying to determine {Beta}({alpha}) more precisely, for all {alpha} > 0, is intriguing. To this end, we have rigorously determined the numbers for thirteen values of {alpha}, where these numbers were calculated with a precision of at least 200 significant digits. For each of these thirteen values of {alpha}, Richardson's extrapolation was applied to the products to obtain estimates of {Beta}({alpha}) to approximately 40 decimal places. Included are graphs of the points ({alpha},{Beta}({alpha})) for the thirteen values of {alpha} that we considered.

Carpenter, A.J.; Varga, R.S.

1992-01-01T23:59:59.000Z

448

An application of distributed approximating functional-wavelets to reactive scattering  

SciTech Connect

A newly developed distributed approximating functional (DAF)-wavelet, the Dirichlet{endash}Gabor DAF-wavelet (DGDW), is applied in a calculation of the state-to-state reaction probabilities for the three-dimensional (3-D) (J=0)H+H{sub 2} reaction, using the time-independent wave-packet reactant-product decoupling (TIWRPD) method. The DGDWs are reconstructed from a rigorous mathematical sampling theorem, and are shown to be DAF-wavelet generalizations of both the sine discrete variable representation (sinc-DVR) and the Fourier distributed approximating functionals (DAFs). An important feature of the generalized sinc-DVR representation is that the grid points are distributed at equally spaced intervals and the kinetic energy matrix has a banded, Toeplitz structure. Test calculations show that, in accordance with mathematical sampling theory, the DAF-windowed sinc-DVR converges much more rapidly and to higher accuracy with bandwidth, 2W+1. The results of the H+H{sub 2} calculation are in very close agreement with the results of previous TIWRPD calculations, demonstrating that the DGDW representation is an accurate and efficient representation for use in FFT wave-packet propagation methods, and that, more generally, the theory of wavelets and related techniques have great potential for the study of molecular dynamics. {copyright} {ital 1998 American Institute of Physics.}

Wei, G.W.; Althorpe, S.C.; Kouri, D.J. [Department of Chemistry and Department of Physics, University of Houston, Houston, Texas77204-5641 (United States); Hoffman, D.K. [Department of Chemistry and Ames Laboratory, Iowa State University, Ames, Iowa50011 (United States)

1998-05-01T23:59:59.000Z

449

Experimental Test of the "Isotropic" Approximation for Granular Materials using p=constant Compression  

E-Print Network (OSTI)

Experimental data from axially symmetric compression test at constant mean pressure p on Hostun sand from Bouvard experiments are used to study the validity of an "isotropic" modelling as a function of the density .The isotropic assumption is found to be quite good for loose samples and/or in the range of large pressure. For smaller mean pressure, anisotropic response is observed at few percents of axial deformation. Relation with anisotropic distribution of local force is made. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn

P. Evesque

2005-07-07T23:59:59.000Z

450

Density-Dependent Relations among Properties of Hadronic Matter and Applications to Hadron-Quark Stars  

SciTech Connect

Density-dependent relations among the saturation properties of symmetric nuclear matter and hyperonic matter, and properties of hadron-(strange) quark stars are shown by applying the conserving nonlinear {sigma}-{omega}-{rho} hadronic mean-field theory. Nonlinear interactions are renormalized self-consistently as effective coupling constants, effective masses, and sources of equations of motion by maintaining thermodynamic consistency to the mean-field approximation. Effective masses and coupling constants at the saturation point of symmetric nuclear matter simultaneously determine the binding energy and saturation properties of hyperonic matter. The coupling constants expected from the hadronic mean-field model and SU(6) quark model for the vector coupling constants are compared by calculating masses of hadron-quark neutron stars. The nonlinear {sigma}-{omega}-{rho} mean-field approximation with vacuum fluctuation corrections and strange quark matter defined by the MIT-bag model were employed to examine properties of hadron-(strange) quark stars. We found that hadron-(strange) quark stars become more stable at high densities compared to pure hadronic and strange quark stars.

Uechi, Hiroshi [Department of Distributions and Communication Sciences, Osaka Gakuin University, Osaka (Japan); Uechi, Schun T. [Research Center for Nuclear Physics (RCNP), Osaka University, Osaka (Japan)

2011-05-06T23:59:59.000Z

451

Relations between light emission and electron density and temperature fluctuations in a helium plasma  

Science Conference Proceedings (OSTI)

The relations between three atomic lines, He I 667.8 nm (3{sup 1}D{yields} 2{sup 1}P), 706.5 nm (3{sup 3}S{yields} 2{sup 3}P), and 728.1 nm (3{sup 1}S{yields} 2{sup 1}P), and the underlying fluctuations in a helium plasma are investigated for the quantitative interpretation of optical observations in plasma fluctuation measurements. Frequency dependent fluctuation amplitude ratios and phase delays between the line emission fluctuation and the electron density and temperature fluctuations are calculated based on a quasi-static collisional-radiative model and a linear approximation technique. For frequencies up to the upper limit of practical interest (<1 MHz), the fluctuation amplitude ratios and phase delays are similar to those directly evaluated by the quasi-static model. It is found that the difference between the results from the linear approximation technique and from the quasi-static model is due to the absence of metastable fluctuations. Contributions of the 2{sup 1}S and 2{sup 3}S metastable fluctuations to the three helium line emission fluctuations are analyzed. The linearity between fluctuations in the line emission and in the electron density and temperature is valid for fluctuation levels higher than 10%.

Ma Shuiliang; Howard, John; Thapar, Nandika [Plasma Research Laboratory, Australian National University, Canberra ACT 0200 (Australia)

2011-08-15T23:59:59.000Z

452

Computing 1-D atomic densities in macromolecular simulations: the Density Profile Tool for VMD  

E-Print Network (OSTI)

Molecular dynamics simulations have a prominent role in biophysics and drug discovery due to the atomistic information they provide on the structure, energetics and dynamics of biomolecules. Specialized software packages are required to analyze simulated trajectories, either interactively or via scripts, to derive quantities of interest and provide insight for further experiments. This paper presents the Density Profile Tool, a package that enhances the Visual Molecular Dynamics environment with the ability to interactively compute and visualize 1-D projections of various density functions of molecular models. We describe how the plugin is used to perform computations both via a graphical interface and programmatically. Results are presented for realistic examples, all-atom bilayer models, showing how mass and electron densities readily provide measurements such as membrane thickness, location of structural elements, and how they compare to X-ray diffraction experiments.

Giorgino, Toni

2013-01-01T23:59:59.000Z

453

Thermodynamics and Structural Properties of the High Density Gaussian Core Model  

E-Print Network (OSTI)

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.

Atsushi Ikeda; Kunimasa Miyazaki

2011-04-18T23:59:59.000Z

454

High power density supercapacitors using locally aligned carbon nanotube electrodes  

E-Print Network (OSTI)

B E 1999 Electrochemical Supercapacitor ( New York: Kluwer–power density of a supercapacitor is its most remarkablepower density of a supercapacitor is given by P max = V i

Du, C S; Yeh, J; Pan, Ning

2005-01-01T23:59:59.000Z

455

Orthobaric Density: A Thermodynamic Variable for Ocean Circulation Studies  

Science Conference Proceedings (OSTI)

A new density variable, empirically corrected for pressure, is constructed. This is done by first fitting compressibility (or sound speed) computed from global ocean datasets to an empirical function of pressure and in situ density (or specific ...

Roland A. de Szoeke; Scott R. Springer; David M. Oxilia

2000-11-01T23:59:59.000Z

456

Innovative fuel designs for high power density pressurized water reactor  

E-Print Network (OSTI)

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 ...

Feng, Dandong, Ph. D. Massachusetts Institute of Technology

2006-01-01T23:59:59.000Z

457

Constrained Density-Functional Theory--Configuration Interaction  

E-Print Network (OSTI)

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 ...

Kaduk, Benjamin James

2012-01-01T23:59:59.000Z

458

Design of annular fuel for high power density BWRs  

E-Print Network (OSTI)

Enabling high power density in the core of Boiling Water Reactors (BWRs) is economically profitable for existing or new reactors. In this work, we examine the potential for increasing the power density in BWR plants by ...

Morra, Paolo

2005-01-01T23:59:59.000Z

459

Density of Freshly Fallen Snow in the Central Rocky Mountains  

Science Conference Proceedings (OSTI)

New snow density distributions are presented for six measurement sites in the mountains of Colorado and Wyoming. Densities were computed from daily measurements of new snow depth and water equivalent from snow board cores. All data were measured ...

Arthur Judson; Nolan Doesken

2000-07-01T23:59:59.000Z

460

On the Elimination of Reactive Element Loops and the Useof Special Approximations in the Design of OTA-C Filters  

Science Conference Proceedings (OSTI)

Loops of reactive elements in passive filters cause a series of problems in OTA-C simulations of these structures. These loops can be eliminated in a systematic way by the procedures described in the paper. The use of special approximations in the ... Keywords: OTA-C filters, approximation, filters

Antonio Carlos M. De Queiroz; Luiz P. Caloba

1997-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Determination of a control parameter in a one-dimensional parabolic equation using the moving least-square approximation  

Science Conference Proceedings (OSTI)

In this paper the approximation of moving least-square (MLS) is used for finding the solution of a one-dimensional parabolic inverse problem with source control parameter. Comparing with other numerical methods based on meshes such as finite difference ... Keywords: inverse problem, meshless method, moving least-square approximation, overspecification, parabolic equation

Rongjun Cheng

2008-09-01T23:59:59.000Z

462

Estimation of a new stochastic transform for solving the complex exponentials approximation problem: Computational aspects and applications  

Science Conference Proceedings (OSTI)

Many real life problems can be reduced to the solution of a complex exponentials approximation problem which is usually ill-posed. Recently a new transform for solving this problem, formulated as a specific moments problem in the plane, has been proposed ... Keywords: Complex moments problem, Logarithmic potentials, Padé approximants, Pencils of matrices, Random determinants

Piero Barone

2010-05-01T23:59:59.000Z

463

A scattered data approximation tool to map single-walled carbon nanotube dispersion to the processing parameters in polymer nanocomposites  

Science Conference Proceedings (OSTI)

The relationship of nanocomposite dispersion to dispersion techniques and other processing parameters was studied. Examining all permutations of the various factors in the laboratory is a challenging task. In this paper, we propose to map a correlation ... Keywords: CNTs, RBF, carbon nanotubes, classification, dispersion, feature selection, functional mapping, greedy algorithms, nanotechnology, polymer nanocomposites, polymer processing, radial basis function, scattered data approximation, sequential function approximation

Jonathan W. Lee; Andrew J. Meade; Enrique V. Barrera

2010-08-01T23:59:59.000Z

464

Controlling Defect Density in Polymer-Fullerene Bulk Heterojunction ...  

Science Conference Proceedings (OSTI)

Controlling Defect Density in Polymer-Fullerene Bulk Heterojunction Solar Cells by Optimizing ... Engineering Carbon Nanomaterials for Energy Application.

465

Density without Disruption [EDRA / Places Awards, 2004 -- Awards Commentary  

E-Print Network (OSTI)

Density without Disruption Awards Commentary country today,CCS Architecture for a planning award. Such work stands as a

Gratz, Roberta Brandes

2004-01-01T23:59:59.000Z

466

Inexpensive Production of High Density Thin Ceramic Films ...  

For Industry; For Researchers; Success Stories; About Us; Available Technologies. Browse By Category Advanced Materials; ... density of the ceramic ...

467

Fatigue Weak-Link Density and Strength Distribution in High ...  

Science Conference Proceedings (OSTI)

Symposium, Fatigue and Corrosion Damage in Metallic Materials: Fundamentals, Modeling and Prevention. Presentation Title, Fatigue Weak-Link Density and ...

468

Improving Baked Anode Density and Air Permeability Through ...  

Science Conference Proceedings (OSTI)

Presentation Title, Improving Baked Anode Density and Air Permeability Through Process Optimization and Coke Blending. Author(s), Bienvenu Ndjom, ...

469

The d-bar approach to approximate inverse scattering at fixed energy in three dimensions  

E-Print Network (OSTI)

We develop the d-bar approach to inverse scattering at fixed energy in dimensions $d\\ge 3$ of [Beals, Coifman 1985] and [Henkin, Novikov 1987]. As a result we propose a stable method for nonlinear approximate finding a potential $v$ from its scattering amplitude $f$ at fixed energy $E>0$ in dimension $d=3$. In particular, in three dimensions we stably reconstruct n-times smooth potential $v$ with sufficient decay at infinity, $n>3$, from its scattering amplitude $f$ at fixed energy $E$ up to $O(E^{-(n-3-\\epsilon)/2})$ in the uniform norm as $E\\to +\\infty$ for any fixed arbitrary small $\\epsilon >0$ (that is with almost the same decay rate of the error for $E\\to +\\infty$ as in the linearized case near zero potential).

Roman Novikov

2005-05-10T23:59:59.000Z

470

Approximate Bregman near neighbors in sublinear time: Beyond the triangle inequality  

E-Print Network (OSTI)

Bregman divergences are important distance measures that are used extensively in data-driven applications such as computer vision, text mining, and speech processing, and are a key focus of interest in machine learning. Answering nearest neighbor (NN) queries under these measures very important in these applications and has been the subject of extensive study, but is problematic because these distance measures lack metric properties like symmetry and the triangle inequality. In this paper, we present the first approximate nearest-neighbor (ANN) algorithms, which run in polylog(n) time for Bregman divergences of fixed dimension. To do so, we explore two properties of Bregman divergences that are vital to the analysis: a reverse triangle inequality (RTI) and a relaxed triangle inequality called mu-defectiveness. We show that even though Bregman divergences do not satisfy the triangle inequality, the above properties can be utilized to design an efficient search data structure that follows the general two-stage ...

Abdullah, Amirali; Venkatasubramanian, Suresh

2011-01-01T23:59:59.000Z

471

Skyrme-Random-Phase-Approximation description of spin-flip and orbital giant resonances  

E-Print Network (OSTI)

The self-consistent separable random-phase approximation (SRPA) model with Skyrme forces is extended to the case of magnetic excitations and applied to the description of spin-flip and orbital M1 giant resonances in the isotopic chain $^{142-152}$Nd. The Skyrme forces SkT6, SkM*, SLy6 and SkI3 are used. The calculations show the onset of the scissors mode with increasing deformation. A specific three-peak structure of the spin-flip response is found and explained by particular neutron and proton spin-flip transitions. Although the employed forces provide an acceptable qualitative description, the Skyrme functional still needs further improvement to reproduce quantitatively the experimental data.

V. O. Nesterenko; J. Kvasil; P. Vesely; W. Kleinig; P. -G. Reinhard

2009-11-12T23:59:59.000Z

472

Low-lying states of heavy nuclei within the nucleon pair approximation  

Science Conference Proceedings (OSTI)

In this article we perform systematic calculations on low-lying states of 33 nuclei with A=202-212, using the nucleon pair approximation of the shell model. We use a phenomenological shell-model Hamiltonian that includes single-particle energies, monopole and quadrupole pairing interactions, and quadrupole-quadrupole interactions. The building blocks of our model space include one J=4 valence neutron pair, and one J=4,6,8 valence proton pair, in addition to the usual S and D pairs. We calculate binding energies, excitation energies, electric quadrupole and magnetic dipole moments of low-lying states, and E2 transition rates between low-lying states. Our calculated results are reasonably consistent with available experimental data. The calculated quadrupole moments and magnetic moments, many of which have not yet been measured for these nuclei, are useful for future experimental measurements.

Xu, Z. Y.; Lei, Y. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhao, Y. M. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); CCAST, World Laboratory, P.O. Box 8730, Beijing 100080 (China); Xu, S. W.; Xie, Y. X. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Arima, A. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Science Museum, Japan Science Foundation, 2-1 Kitanomaru-koen, Chiyoda-ku, Tokyo 102-0091 (Japan)

2009-05-15T23:59:59.000Z

473

Bayesian inference of solar and stellar magnetic fields in the weak-field approximation  

E-Print Network (OSTI)

The weak-field approximation is one of the simplest models that allows us to relate the observed polarization induced by the Zeeman effect with the magnetic field vector present on the plasma of interest. It is usually applied for diagnosing magnetic fields in the solar and stellar atmospheres. A fully Bayesian approach to the inference of magnetic properties in unresolved structures is presented. The analytical expression for the marginal posterior distribution is obtained, from which we can obtain statistically relevant information about the model parameters. The role of a-priori information is discussed and a hierarchical procedure is presented that gives robust results that are almost insensitive to the precise election of the prior. The strength of the formalism is demonstrated through an application to IMaX data. Bayesian methods can optimally exploit data from filter-polarimeters given the scarcity of spectral information as compared with spectro-polarimeters. The effect of noise and how it degrades ou...

Ramos, A Asensio

2011-01-01T23:59:59.000Z

474

Competition between superconductivity and spin density wave  

E-Print Network (OSTI)

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.

Tian De Cao

2011-01-02T23:59:59.000Z

475

Vacuum Outgassing of High Density Polyethylene  

Science Conference Proceedings (OSTI)

A combination of thermogravimetric analysis (TGA) and temperature programmed decomposition (TPD) was employed to identify the outgassing species, the total amount of outgassing, and the outgassing kinetics of high density polyethylene (HDPE) in a vacuum environment. The isoconversional kinetic analysis was then used to analyze the outgassing kinetics and to predict the long-term outgassing of HDPE in vacuum applications at ambient temperature. H{sub 2}O and C{sub n}H{sub x} with n as high as 9 and x centering around 2n are the major outgassing species from solid HDPE, but the quantities evolved can be significantly reduced by vacuum baking at 368 K for a few hours prior to device assembly.

Dinh, L N; Sze, J; Schildbach, M A; Chinn, S C; Maxwell, R S; Raboin, P; McLean II, W

2008-08-11T23:59:59.000Z

476

BRST technique for the cosmological density matrix  

E-Print Network (OSTI)

The microcanonical density matrix in closed cosmology has a natural definition as a projector on the space of solutions of Wheeler-DeWitt equations, which is motivated by the absence of global non-vanishing charges and energy in spatially closed gravitational systems. Using the BRST/BFV formalism in relativistic phase space of gauge and ghost variables we derive the path integral representation for this projector and the relevant statistical sum. This derivation circumvents the difficulties associated with the open algebra of noncommutative quantum Dirac constraints and the construction/regularization of the physical inner product in the subspace of BRS singlets. This inner product is achieved via the Batalin-Marnelius gauge fixing in the space of BRS-invariant states, which in its turn is shown to be a result of truncation of the BRST/BFV formalism to the "matter" sector of relativistic phase space.

Andrei O. Barvinsky

2013-08-14T23:59:59.000Z

477

A digital rock density map of New Zealand  

Science Conference Proceedings (OSTI)

Digital geological maps of New Zealand (QMAP) are combined with 9256 samples with rock density measurements from the national rock catalogue PETLAB and supplementary geological sources to generate a first digital density model of New Zealand. This digital ... Keywords: Crust, Database, Density, Geological mapping, Gravimetry, Rock types

Robert Tenzer; Pascal Sirguey; Mark Rattenbury; Julia Nicolson

2011-08-01T23:59:59.000Z

478

High fidelity field simulations using density and pressure based approaches  

Science Conference Proceedings (OSTI)

Density-based and pressure-based approaches in solving the Navier-Stokes equations for computational field simulations for compressible and incompressible flows have been presented. For the density-based flow solver, a generalized grid based framework ... Keywords: CFD, Density-based method, Pressure-based method

Gary C. Cheng; Roy P. Koomullil; Bharat K. Soni

2005-11-01T23:59:59.000Z

479

Density-Enthalpy Phase Diagram 0D Boiler Simulation  

E-Print Network (OSTI)

Density-Enthalpy Phase Diagram 0D Boiler Simulation Finite Element Method Further Research Finite Transitions #12;Density-Enthalpy Phase Diagram 0D Boiler Simulation Finite Element Method Further Research;Density-Enthalpy Phase Diagram 0D Boiler Simulation Finite Element Method Further Research Goal

Vuik, Kees

480

Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities  

DOE Patents (OSTI)

A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.

Harrison, Neil (Santa Fe, NM); Singleton, John (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)

2008-08-05T23:59:59.000Z

Note: This page contains sample records for the topic "greatest density approximately" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

A new numerical method for conversion of sonic second virial coefficients to density second virial coefficients  

E-Print Network (OSTI)

A new numerical method has been developed for calculation of density second virial coefficients, B(T), from sonic velocity measurements in gases at low pressures. Unlike existing methods, this procedure requires no model assumption as to the form of the temperature variation of B(T). Rather it gathers additional information by differencing the measured acoustic second virial coefficient in accordance with a new mathematical approximation. While two higher-ordered terms in the complete identity must be ignored to initiate the numerical calculations, the magnitude of these terms can later be estimated from the initial determination of B(T). By such an iterative procedure, the method can be made exact or, from a second viewpoint, the initial estimate allows calculation of the errors in the method itself. The new method is simple and easy to use as it employs only standard numerical techniques. It requires a digital computer program; although limited calculations can be made on a modern hand-held calculator. The objectives of this research are (1) to prove that our method is more accurate than existing methods for extracting second density virial coefficients from sonic velocity data, (2) to illustrate that the new numerical method is much simpler in convening sonic velocity data to second density virial coefficients and finally (3) to show that with the new method, no model assumptions for the temperature profile need to be made to get accurate results.

Mossaad, Ehab

1999-01-01T23:59:59.000Z

482

Microwave measurements of electron density in a spherical inertial- electrostatic confinement system using six ion guns  

SciTech Connect

The electron density in a spherical inertial-electrostatic confinement device using six ion beams was studied with microwave techniques involving the fundamental and higher order cavity resonances. Thermal expansion problems were circumvented by switched operation of the device. The deuterium background pressure was found to be a dominant factor in determining n/sub e/ throughout the entire range of 0.4 to 10 milliTorr. With 1 m Torr pressure and 10 mA total ion current (at 20 to 40 keV) central electron densities of the order of 10$sup 9$ electrons/ cm$sup 3$ were estimated, with total population of approximately 10$sup 10$ electrons. No evidence of shell structure of the electron density was found, although the use of higher order modes to obtain better spatial resolution was precluded by the low magnitude of n/sub e/. Indirect indication of weak ion trapping was obtained by measurement of the enhancement of neutron flux that resulted when the guns were operated simultaneously. (auth)

Chan, A.I.Y.

1975-08-01T23:59:59.000Z

483

Use of periodic approximants in a dynamical LEED study of the quasicrystalline tenfold surface of decagonal Al-Ni-Co  

SciTech Connect

The determination of quasicrystal (QC) surface structures is a challenge to current surface structure techniques. Low-energy electron diffraction (LEED) is the primary technique for the determination of periodic surface structures, but application of dynamical LEED to quasicrystals requires the use of many approximations. In this study, two different approaches were used to apply dynamical LEED to the structure of the tenfold surface of decagonal Al{sub 73}Ni{sub 10}Co{sub 17}. One method (method 1) involves the use of a quasicrystalline model along with approximations that average over the composition and local geometries. The other method (method 2) uses periodic models that approximate the actual local QC structure (approximants) in more exact, atomistic calculations. Although the results using the two methods were consistent, the results of the approximant analysis (method 2) suggested a different way to apply the approximations in method 1, resulting in a better fit between experimental and calculated beams. Thus, periodic approximant structure models can provide a simpler and more efficient method for the determination of local geometries in QC surfaces, and may also facilitate analyses using quasicrystal models.

Pussi, K.; Ferralis, N.; Mihalkovic, M.; Widom, M.; Curtarolo, S.; Gierer, M.; Jenks, C. J.; Canfield, P.; Fisher, I. R.; Diehl, R. D. [Department of Electrical Engineering, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland); Physics Department and Materials Research Institute, Penn State University, University Park, Pennsylvania 16802 (United States); Slovak Academy of Sciences, Dubravska Cesta 9, Bratislava 84228 (Slovakia); Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Department of Materials Science and Mechanical Engineering, Duke University, Durham, North Carolina 27708 (United States); Institute for Crystallography and Applied Mineralogy, Theresienstrasse 41, 80333 Muenchen (Germany); Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States); Physics Department and Materials Research Institute, Penn State University, University Park, Pennsylvania 16802 (United States)

2006-05-01T23:59:59.000Z

484

Discretization and Approximation Methods for Reinforcement Learning of Highly Reconfigurable Systems  

E-Print Network (OSTI)

There are a number of techniques that are used to solve reinforcement learning problems, but very few that have been developed for and tested on highly reconfigurable systems cast as reinforcement learning problems. Reconfigurable systems refers to a vehicle (air, ground, or water) or collection of vehicles that can change its geometrical features, i.e. shape or formation, to perform tasks that the vehicle could not otherwise accomplish. These systems tend to be optimized for several operating conditions, and then controllers are designed to reconfigure the system from one operating condition to another. Q-learning, an unsupervised episodic learning technique that solves the reinforcement learning problem, is an attractive control methodology for reconfigurable systems. It has been successfully applied to a myriad of control problems, and there are a number of variations that were developed to avoid or alleviate some limitations in earlier version of this approach. This dissertation describes the development of three modular enhancements to the Q-learning algorithm that solve some of the unique problems that arise when working with this class of systems, such as the complex interaction of reconfigurable parameters and computationally intensive models of the systems. A multi-resolution state-space discretization method is developed that adaptively rediscretizes the state-space by progressively finer grids around one or more distinct Regions Of Interest within the state or learning space. A genetic algorithm that autonomously selects the basis functions to be used in the approximation of the action-value function is applied periodically throughout the learning process. Policy comparison is added to monitor the state of the policy encoded in the action-value function to prevent unnecessary episodes at each level of discretization. This approach is validated on several problems including an inverted pendulum, reconfigurable airfoil, and reconfigurable wing. Results show that the multi-resolution state-space discretization method reduces the number of state-action pairs, often by an order of magnitude, required to achieve a specific goal and the policy comparison prevents unnecessary episodes once the policy has converged to a usable policy. Results also show that the genetic algorithm is a promising candidate for the selection of basis functions for function approximation of the action-value function.

Lampton, Amanda K.

2009-12-01T23:59:59.000Z

485

Recent developments in classical density functional theory: Internal energy functional and diagrammatic structure of fundamental measure theory  

E-Print Network (OSTI)

An overview of several recent developments in density functional theory for classical inhomogeneous liquids is given. We show how Levy's constrained search method can be used to derive the variational principle that underlies density functional theory. An advantage of the method is that the Helmholtz free energy as a functional of a trial one-body density is given as an explicit expression, without reference to an external potential as is the case in the standard Mermin-Evans proof by reductio ad absurdum. We show how to generalize the approach in order to express the internal energy as a functional of the one-body density distribution and of the local entropy distribution. Here the local chemical potential and the bulk temperature play the role of Lagrange multipliers in the Euler-Lagrange equations for minimiziation of the functional. As an explicit approximation for the free-energy functional for hard sphere mixtures, the diagrammatic structure of Rosenfeld's fundamental measure density unctional is laid out. Recent extensions, based on the Kierlik-Rosinberg scalar weight functions, to binary and ternary non-additive hard sphere mixtures are described.

M. Schmidt; M. Burgis; W. S. B. Dwandaru; G. Leithall; P. Hopkins

2012-12-27T23:59:59.000Z

486

An approximate-reasoning-based method for screening high-level waste tanks for flammable gas  

DOE Green Energy (OSTI)

The in situ retention of flammable gas produced by radiolysis and thermal decomposition in high-level waste can pose a safety problem if the gases are released episodically into the dome space of a storage tank. Screening efforts at Hanford have been directed at identifying tanks in which this situation could exist. Problems encountered in screening motivated an effort to develop an improved screening methodology. Approximate reasoning (AR) is a formalism designed to emulate the kinds of complex judgments made by subject matter experts. It uses inductive logic structures to build a sequence of forward-chaining inferences about a subject. AR models incorporate natural language expressions known as linguistic variables to represent evidence. The use of fuzzy sets to represent these variables mathematically makes it practical to evaluate quantitative and qualitative information consistently. The authors performed a pilot study to investigate the utility of AR for flammable gas screening. They found that the effort to implement such a model was acceptable and that computational requirements were reasonable. The preliminary results showed that important judgments about the validity of observational data and the predictive power of models could be made. These results give new insights into the problems observed in previous screening efforts.

Eisenhawer, S.W.; Bott, T.F.; Smith, R.E.

1998-07-01T23:59:59.000Z

487

Discrete Dipole Approximation for Low-Energy Photoelectron Emission from NaCl Nanoparticles  

SciTech Connect

This work presents a model for the photoemission of electrons from sodium chloride nanoparticles 50-500 nm in size, illuminated by vacuum ultraviolet light with energy ranging from 9.4-10.9 eV. The discrete dipole approximation is used to calculate the electromagnetic field inside the particles, from which the two-dimensional angular distribution of emitted electrons is simulated. The emission is found to favor the particle?s geometrically illuminated side, and this asymmetry is compared to previous measurements performed at the Lawrence Berkeley National Laboratory. By modeling the nanoparticles as spheres, the Berkeley group is able to semi-quantitatively account for the observed asymmetry. Here however, the particles are modeled as cubes, which is closer to their actual shape, and the interaction of an emitted electron with the particle surface is also considered. The end result shows that the emission asymmetry for these low-energy electrons is more sensitive to the particle-surface interaction than to the specific particle shape, i.e., a sphere or cube.

Berg, Matthew J.; Wilson, Kevin R.; Sorensen, Chris; Chakrabarti, Amit; Ahmed, Musahid

2011-09-22T23:59:59.000Z

488

Born-Oppenheimer-type Approximations for Degenerate Potentials: Recent Results and a Survey on the area  

E-Print Network (OSTI)

This paper is devoted to the asymptotics of eigenvalues for a Schr\\"o-dinger operator in the case when the potential V does not tend to infinity at infinity. Such a potential is called degenerate. The point is that the set in the phase space where the associated hamiltonian is smaller than a fixed energy E may have an infinite volume, so that the Weyl formula which gives the behaviour of the counting function has to be revisited. We recall various results in this area, in the classical context as well as in the semi-classical one and comment the different methods. In sections 3, 4 we present our joint works with A Morame, (Universit\\'e de Nantes),concerning a degenerate potential V(x) =f(y) g(z), where g is assumed to be a homogeneous positive function of m variables, and f is a smooth and strictly positive function of n variables, with a minimum in 0. In the case where f tends to infinity at infinity, we give the semi-classical asymptotic behaviour of the number of eigenvalues less than a fixed energy . Then we give a sharp estimate of the low eigenvalues, using a Born Oppenheimer approximation. With a refined approach we localize also higher energies . Finally we apply the previous methods to a class of potentials which vanish on a regular hypersurface.

Francoise Truc

2009-01-05T23:59:59.000Z

489

Prioritizing the purchase of spare parts using an approximate reasoning models.  

SciTech Connect

The complexity of a spare parts prioritization model should be consonant with the amount and quality of data available to populate it. When production processes are new and the reliability database is sparse and represents primarily expert knowledge, an approximate reasoning (AR) based model is appropriate. AR models are designed to emulate the inferential processes used by experts in making judgments. We have designed and tested such a model for the planned component production process for nuclear weapons at Los Alamos National Laboratory. The model successfully represents the experts knowledge concerning the frequency and consequences of a part failure. The use of linguistic variables provides an adaptable format for eliciting this knowledge and providing a consistent brisis for valuing the effect on production of different parts. Ranking the parts for inclusion in a spare parts inventory is a straightforward transformation of the AR output. The basis for this ranking is directly traceable to the elicitation results. AR-based models are well-suited to prioritization problems with these characteristics.

Eisenhawer, S. W. (Stephen W.); Bott, T. F. (Terrence F.); Jackson, J. W. (Joseph W.)

2001-01-01T23:59:59.000Z

490

Strong-field approximation for ionization of a diatomic molecule by a strong laser field  

Science Conference Proceedings (OSTI)

We present a theory of ionization of diatomic molecules by a strong laser field. A diatomic molecule is considered as a three-particle system, which consists of two heavy atomic (ionic) centers and an electron. After the separation of the center-of-mass coordinate, the dynamics of this system is reduced to the relative electronic and nuclear coordinates. The exact S-matrix element for ionization is presented in a form in which the laser-molecule interaction is emphasized. This form is useful for application of the molecular strong-field approximation (SFA). We introduced two forms of the molecular SFA, one with the field-free and the other with the field-dressed initial molecular bound state. We relate these two forms of our modified molecular SFA to the standard molecular SFAs, introduced previously using the length gauge and the velocity gauge. Numerical examples of the ionization rates of N{sub 2} and O{sub 2} molecules are shown and compared for all four versions of the molecular SFA and we suggest that our modified molecular SFA should be used instead of the standard molecular SFA.

Milosevic, D. B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo, Bosnia and Herzegovina and Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)

2006-12-15T23:59:59.000Z

491

A correlated-polaron electronic propagator: open electronic dynamics beyond the Born-Oppenheimer approximation  

E-Print Network (OSTI)

In this work we develop a theory of correlated many-electron dynamics dressed by the presence of a finite-temperature harmonic bath. The theory is based on the ab-initio Hamiltonian, and thus well-defined apart from any phenomenological choice of collective basis states or electronic coupling model. The equation-of-motion includes some bath effects non-perturbatively, and can be used to simulate line- shapes beyond the Markovian approximation and open electronic dynamics which are subjects of renewed recent interest. Energy conversion and transport depend critically on the ratio of electron-electron coupling to bath-electron coupling, which is a fitted parameter if a phenomenological basis of many-electron states is used to develop an electronic equation of motion. Since the present work doesn't appeal to any such basis, it avoids this ambiguity. The new theory produces a level of detail beyond the adiabatic Born-Oppenheimer states, but with cost scaling like the Born-Oppenheimer approach. While developing this model we have also applied the time-convolutionless perturbation theory to correlated molecular excitations for the first time. Resonant response properties are given by the formalism without phenomenological parameters. Example propagations with a developmental code are given demonstrating the treatment of electron-correlation in absorption spectra, vibronic structure, and decay in an open system.

John A. Parkhill; Thomas Markovich; David G. Tempel; Alan Aspuru-Guzik

2012-06-12T23:59:59.000Z

492

A correlated-polaron electronic propagator: open electronic dynamics beyond the Born-Oppenheimer approximation  

E-Print Network (OSTI)

In this work we develop a theory of correlated many-electron dynamics dressed by the presence of a finite-temperature harmonic bath. The theory is based on the ab-initio Hamiltonian, and thus well-defined apart from any phenomenological choice of collective basis states or electronic coupling model. The equation-of-motion includes some bath effects non-perturbatively, and can be used to simulate line- shapes beyond the Markovian approximation and open electronic dynamics which are subjects of renewed recent interest. Energy conversion and transport depend critically on the ratio of electron-electron coupling to bath-electron coupling, which is a fitted parameter if a phenomenological basis of many-electron states is used to develop an electronic equation of motion. Since the present work doesn't appeal to any such basis, it avoids this ambiguity. The new theory produces a level of detail beyond the adiabatic Born-Oppenheimer states, but with cost scaling like the Born-Oppenheimer approach. While developing th...

Parkhill, John A; Tempel, David G; Aspuru-Guzik, Alan

2012-01-01T23:59:59.000Z

493

Beyond the born approximation: Measuring the two-photon exchange effect at CLAS  

Science Conference Proceedings (OSTI)

Recent results from experiments at Jefferson Laboratory, Newport News VA, which measured the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and newer polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE) processes. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1 CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams