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We encourage you to perform a real-time search of NLEBeta
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1

Discrete space-time symmetries  

SciTech Connect

Symmetries have always fascinated human beings; they are found in nature, art, and architecture. Physicists, like other scientists have often used symmetries as a basis of their understanding of nature. When the dynamics is unknown, symmetries serve to delineate and define it. When the dynamics is known, symmetries are used to study structure. These two lectures review the theory and present understanding and status of two discrete space-time symmetries,, namely parity (P) and time reversal (T).

Henley, E.M.

1992-12-31T23:59:59.000Z

2

Discrete space-time symmetries  

SciTech Connect

Symmetries have always fascinated human beings; they are found in nature, art, and architecture. Physicists, like other scientists have often used symmetries as a basis of their understanding of nature. When the dynamics is unknown, symmetries serve to delineate and define it. When the dynamics is known, symmetries are used to study structure. These two lectures review the theory and present understanding and status of two discrete space-time symmetries,, namely parity (P) and time reversal (T).

Henley, E.M.

1992-01-01T23:59:59.000Z

3

Physics in discrete spaces (A): Space-Time organization  

E-Print Network (OSTI)

We put forward a model of discrete physical space that can account for the structure of space- time, give an interpretation to the postulates of quantum mechanics and provide a possible explanation to the organization of the standard model of particles.

P. Peretto

2010-12-29T23:59:59.000Z

4

Simple Space-Time Symmetries: Generalizing Conformal Field Theory  

E-Print Network (OSTI)

We study simple space-time symmetry groups G which act on a space-time manifold M=G/H which admits a G-invariant global causal structure. We classify pairs (G,M) which share the following additional properties of conformal field theory: 1) The stability subgroup H of a point in M is the identity component of a parabolic subgroup of G, implying factorization H=MAN, where M generalizes Lorentz transformations, A dilatations, and N special conformal transformations. 2) special conformal transformations in N act trivially on tangent vectors to the space-time manifold M. The allowed simple Lie groups G are the universal coverings of SU(m,m), SO(2,D), Sp(l,R), SO*(4n) and E_7(-25) and H are particular maximal parabolic subgroups. They coincide with the groups of fractional linear transformations of Euklidean Jordan algebras whose use as generalizations of Minkowski space time was advocated by Gunaydin. All these groups G admit positive energy representations. It will also be shown that the classical conformal groups SO(2,D) are the only allowed groups which possess a time reflection automorphism; in all other cases space-time has an intrinsic chiral structure.

Gerhard Mack; Mathias de Riese

2004-10-28T23:59:59.000Z

5

Discrete Differential Forms for $(1+1)$-Dimensional Cosmological Space-Times  

Science Conference Proceedings (OSTI)

In this article we describe applications of the numerical method of discrete differential forms in computational general relativity (GR). In particular, we consider the initial value problem for vacuum space-times that admit plane gravitational waves. ... Keywords: discrete differential forms, polarized gowdy, translationally symmetric space-time

Ronny Richter; Jörg Frauendiener

2010-04-01T23:59:59.000Z

6

Space-time discontinuous Galerkin discretization of rotating shallow water equations  

Science Conference Proceedings (OSTI)

A space-time discontinuous Galerkin (DG) discretization is presented for the (rotating) shallow water equations over varying topography. We formulate the space-time DG finite element discretization in an efficient and conservative discretization. The ... Keywords: 35Q35, 65N30, 75S05, 76B15, 76M10, Bores, Discontinuous Galerkin methods, Finite element methods, Moving grid, Numerical dissipation, Potential vorticity, Shallow water equations

V. R. Ambati; O. Bokhove

2007-08-01T23:59:59.000Z

7

Discrete symmetries and neutrino masses  

SciTech Connect

We constructed a model of neutrino masses using Froggatt-Nielsen mechanism with U(1)xZ{sub 3}xZ{sub 2} flavor symmetry. The model predicts that (2/3)m{sub 2}/m{sub 3}{approx}{radical}(2)sin{theta}{sub 13} at lepton number violating scale M{sub 1}. It is shown that the small values for m{sub 2}/m{sub 3} and sin{theta}{sub 13} are consequences of breaking discrete symmetries.

Siyeon, Kim [Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of)

2005-02-01T23:59:59.000Z

8

On Energy Distribution of Two Space-times with Planar and Cylindrical Symmetries  

E-Print Network (OSTI)

Considering encouraging Virbhadra's results about energy distribution of non-static spherically symmetric metrics in Kerr-Schild class, it would be interesting to study some space-times with other symmetries. Using different energy-momentum complexes, i.e. M{\\o}ller, Einstein, and Tolman, in static plane-symmetric and cylindrically symmetric solutions of Einstein-Maxwell equations in 3+1 dimensions, energy (due to matter and fields including gravity) distribution is studied. Energy expressions are obtained finite and well-defined. calculations show interesting coincidences between the results obtained by Einstein and Tolamn prescriptions. Our results support the Cooperstock hypothesis about localized energy.

Saeed Mirshekari; Amir M. Abbassi

2008-07-07T23:59:59.000Z

9

Neutrino Mass and Mixing with Discrete Symmetry  

E-Print Network (OSTI)

This is a review article about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of see-saw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mechanisms for flavon vacuum alignment and different model building strategies that have been proposed to generate the reactor angle. We then briefly review grand unified theories (GUTs) and how they may be combined with discrete family symmetry to describe all quark and lepton masses and mixing. Finally we discuss three model examples which combine an SU(5) GUT with the discrete family symmetries A4, S4 and Delta(96).

Stephen F. King; Christoph Luhn

2013-01-07T23:59:59.000Z

10

Neutrino Mass and Mixing with Discrete Symmetry  

E-Print Network (OSTI)

This is a review article about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of seesaw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mec...

King, Stephen F

2013-01-01T23:59:59.000Z

11

A Sparse Grid SpaceTime Discretization Scheme for Parabolic Problems  

E-Print Network (OSTI)

A Sparse Grid Space­Time Discretization Scheme for Parabolic Problems Michael Griebel, Daniel Oeltz Abstract In this paper we consider the discretization in space and time of parabolic di#erential equations. This holds in many applications due to the smoothing properties of the propagator of the parabolic PDE (heat

Bartels, Soeren

12

DISCRETE SYMMETRIES OF THE BLACK-SCHOLES EQUATION  

E-Print Network (OSTI)

DISCRETE SYMMETRIES OF THE BLACK-SCHOLES EQUATION Gheorghe Silberberg Abstract The paper computes the full automorphism group of the Lie al- gebra associated to the Black-Scholes equation and determines symmetries. The present paper applies the whole procedure to the famous Black- Scholes partial differential

13

On discrete symmetries for a whole Abelian model  

Science Conference Proceedings (OSTI)

Considering the whole concept applied to gauge theory a nonlinear abelian model is derived. A next step is to understand on the model properties. At this work, it will be devoted to discrete symmetries. For this, we will work based in two fields reference systems. This whole gauge symmetry allows to be analyzed through different sets which are the constructor basis {l_brace}D{sub {mu}},X{sup i}{sub {mu}}{r_brace} and the physical basis {l_brace}G{sub {mu}I}{r_brace}. Taking as fields reference system the diagonalized spin-1 sector, P, C, T and PCT symmetries are analyzed. They show that under this systemic model there are conservation laws driven for the parts and for the whole. It develops the meaning of whole-parity, field-parity and so on. However it is the whole symmetry that rules. This means that usually forbidden particles as pseudovector photons can be introduced through such whole abelian system. As result, one notices that the fields whole {l_brace}G{sub {mu}I}{r_brace} manifest a quanta diversity. It involves particles with different spins, masses and discrete quantum numbers under a same gauge symmetry. It says that without violating PCT symmetry different possibilities on discrete symmetries can be accommodated.

Chauca, J.; Doria, R. [CBPF, Rio de Janeiro (Brazil); Aprendanet, Petropolis, 25600 (Brazil)

2012-09-24T23:59:59.000Z

14

The discrete flavor symmetry D5  

E-Print Network (OSTI)

We consider the standard model (SM) extended by the flavor symmetry D5 and search for a minimal model leading to viable phenomenology. We find that it contains four Higgs fields apart from the three generations of fermions whose left- and left-handed conjugate parts do not transform in the same way under D5. We provide two numerical fits for the case of Dirac and Majorana neutrinos to show the viability of our low energy model. The fits can accommodate all data with the neutrinos being normally ordered. For Majorana neutrinos two of the right-handed neutrinos are degenerate. Concerning the Higgs sector we find that all potentials constructed with three SM-like Higgs doublets transforming as 1+2 under D5 have a further unwanted global U(1) symmetry. Therefore we consider the case of four Higgs fields forming two D5 doublets and show that this potential leads to viable solutions in general, however it does not allow spontaneous CP-violation (SCPV) for an arbitrary vacuum expectation value (VEV) configuration. Finally, we discuss extensions of our model to grand unified theories (GUTs) as well as embeddings of D5 into the continuous flavor symmetries SO(3)_f and SU(3)_f.

C. Hagedorn; M. Lindner; F. Plentinger

2006-04-28T23:59:59.000Z

15

The symmetry, inferable from Bogoliubov transformation, between the processes induced by the mirror in two-dimentional and the charge in four-dimentional space-time  

E-Print Network (OSTI)

The symmetry between the creation of pairs of massless bosons or fermions by accelerated mirror in 1+1 space and the emission of single photons or scalar quanta by electric or scalar charge in 3+1 space is deepened in this paper. The relation of Bogoliubov coefficients with Fourier's components of current or charge density leads to the coicidence of the spin of any disturbances bilinear in scalar or spinor field with the spin of quanta emitted by the electric or scalar charge. The mass and invariant momentum transfer of these disturbances are essential for the relation of Bogoliubov coefficients with Green's functions of wave equations both for 1+1 and 3+1 spaces. Namely the relation (20) leads to the coincidence of the self-action changes and vacuum-vacuum amplitudes for the accelerated mirror in 1+1 space and charge in 3+1 space. Thus, both invariants of the Lorentz group, spin and mass, perform intrinsic role in established symmetry. The symmetry embraces not only the processes of real quanta radiation. It extends also to the processes of the mirror and the charge interactions with the fields carring spacelike momenta. These fields accompany their sources and define the Bogoliubov matrix coefficients \\alpha^{B,F}. It is shown that the traces of \\alpha^{B,F} describe the vector and scalar interactions of accelerated mirror with uniformly moving detector. This interpretation rests essentially on the relation (100) between the propagators of the waves with spacelike momenta in 2- and 4-dimentional spaces. The traces of \\alpha^{B,F} coincide actually with the products of the mass shift \\Delta m_{1,0} of accelerated electric or scalar charge and the proper time of the shift formation. The symmetry fixes the value of the bare fine structure constant \\alpha_0=1/4\\pi.

V. I. Ritus

2003-09-18T23:59:59.000Z

16

Hamiltonian dynamics of a quantum of space: hidden symmetries and spectrum of the volume operator, and discrete orthogonal polynomials  

E-Print Network (OSTI)

The action of the quantum mechanical volume operator, introduced in connection with a symmetric representation of the three-body problem and recently recognized to play a fundamental role in discretized quantum gravity models, can be given as a second order difference equation which, by a complex phase change, we turn into a discrete Schr\\"odinger-like equation. The introduction of discrete potential-like functions reveals the surprising crucial role here of hidden symmetries, first discovered by Regge for the quantum mechanical 6j symbols; insight is provided into the underlying geometric features. The spectrum and wavefunctions of the volume operator are discussed from the viewpoint of the Hamiltonian evolution of an elementary "quantum of space", and a transparent asymptotic picture emerges of the semiclassical and classical regimes. The definition of coordinates adapted to Regge symmetry is exploited for the construction of a novel set of discrete orthogonal polynomials, characterizing the oscillatory components of torsion-like modes.

Vincenzo Aquilanti; Dimitri Marinelli; Annalisa Marzuoli

2013-01-09T23:59:59.000Z

17

Space Time Matter inflation  

E-Print Network (OSTI)

We study a model of power-law inflationary inflation using the Space-Time-Matter (STM) theory of gravity for a five dimensional (5D) canonical metric that describes an apparent vacuum. In this approach the expansion is governed by a single scalar (neutral) quantum field. In particular, we study the case where the power of expansion of the universe is $p \\gg 1$. This kind of model is more successful than others in accounting for galaxy formation.

Mariano Anabitarte; Mauricio Bellini

2005-08-31T23:59:59.000Z

18

The Higgs Sector on a Two-Sheeted Space Time  

E-Print Network (OSTI)

We present a general formalism based on the framework of non-commutative geometry, suitable to the study the standard model of electroweak interactions, as well as that of more general gauge theories. Left- and right-handed chiral fields are assigned to two different sheets of space-time (a discretized version of Kaluza-Klein theory). Scalar Higgs fields find themselves treated on the same footing as the gauge fields, resulting in spontaneous symmetry breaking in a natural and predictable way. We first apply the formalism to the Standard Model, where one can predict the Higgs mass and the top Yukawa coupling. We then study the left-right symmetric model, where we show that this framework imposes constraints on the type and coefficients of terms appearing in the Higgs potential.

Cosmin Macesanu; Kameshwar C. Wali

2005-03-15T23:59:59.000Z

19

Capacitance: A property of nanoscale materials based on spatial symmetry of discrete electrons  

Science Conference Proceedings (OSTI)

Capacitance is a measure of the ability to store electrons and is conventionally considered to be a constant dependent upon the shape of metal contacts and the dimensions of the system. In general, however, equipotentials of dielectric systems without ... Keywords: Capacitance, Discrete charges, Nanoscale materials, Periodic table

Tim LaFave, Jr.; Raphael Tsu

2008-03-01T23:59:59.000Z

20

Predictivity of models with spontaneously broken non-Abelian discrete flavor symmetries  

E-Print Network (OSTI)

In a class of supersymmetric flavor models predictions are based on residual symmetries of some subsectors of the theory such as those of the charged leptons and neutrinos. However, the vacuum expectation values of the so-called flavon fields generally modify the K\\"ahler potential of the setting, thus changing the predictions. We derive simple analytic formulae that allow us to understand the impact of these corrections on the predictions for the masses and mixing parameters. Furthermore, we discuss the effects on the vacuum alignment and on flavor changing neutral currents. Our results can also be applied to non--supersymmetric flavor models.

Chen, Mu-Chun; Omura, Yuji; Ratz, Michael; Staudt, Christian

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Dielectric Analog Space-Times  

E-Print Network (OSTI)

We generalize the notion of a dielectric analog Schwarzschild black hole model to analog models of arbitrary space-times; in particular, the approach is not restricted to static space-times. This is done by establishing a correspondence between electrodynamics on a curved, vacuum manifold, with electrodynamics in a general linear dielectric residing in Minkowski space-time. The mapping is not unique, allowing for some freedom in the specification of equivalent materials, which could be useful for exploiting recent developments in the production of metamaterials. Some examples are considered, with special attention paid to the dielectric analog of the exterior Kerr geometry, which is found to be reproducible with regular, linear, dielectrics.

Robert T. Thompson; Jörg Frauendiener

2010-10-08T23:59:59.000Z

22

Symmetry in Scheduling Problems  

E-Print Network (OSTI)

Nov 16, 2010 ... 2 Problem Symmetry and Fundamental Domains ...... Handbook of Computational Group Theory (Discrete Mathematics and Its Applica- tions).

23

(L{sub e}-L{sub {mu}-}L{sub {tau}}) discrete symmetry for heavy right-handed neutrinos and degenerate leptogenesis  

Science Conference Proceedings (OSTI)

The degenerate leptogenesis is studied when the degeneracy in two of the heavy right-handed neutrinos [the third one is irrelevant if {mu}-{tau} symmetry is assumed] is due to L{identical_to}(L{sub e}-L{sub {mu}-}L{sub {tau}}) discrete symmetry. It is shown that a sizable leptogenesis asymmetry ({epsilon}{>=}10{sup -6}) is possible. The level of degeneracy required also predicts the Majorana phase needed for the asymmetry and this prediction is testable since it is the same phase, which appears in the double {beta} decay. Implications of nonzero reactor angle {theta}{sub 13} are discussed. It is shown that the contribution from sin{sup 2{theta}}{sub 13} to the leptogenesis asymmetry parameter may even dominate. An accurate measurement of sin{sup 2{theta}}{sub 13} would have important implications for the mass degeneracy of heavy right-handed neutrinos.

Riazuddin [Centre for Advanced Mathematics and Physics, National University of Sciences and Technology, Rawalpindi (Pakistan) and National Centre for Physics, Quaid-i-Azam University, Islamabad (Pakistan)

2010-05-01T23:59:59.000Z

24

Gravity in Complex Hermitian Space-Time  

E-Print Network (OSTI)

A generalized theory unifying gravity with electromagnetism was proposed by Einstein in 1945. He considered a Hermitian metric on a real space-time. In this work we review Einstein's idea and generalize it further to consider gravity in a complex Hermitian space-time.

Ali H. Chamseddine

2006-10-09T23:59:59.000Z

25

Iodine photodissociation laser with an intracavity space - time light modulator  

SciTech Connect

A scheme of an iodine laser with two different intracavity space - time modulators based on electrooptic PLZT ceramics is experimentally studied. It is shown that lasing can occur in different angular directions with the use of both modulators. The output laser energy is 10 mJ with a pulse duration of 200 {mu}s and a beam divergence of 6.3 Multiplication-Sign 10{sup -4} rad. The laser field of view (5.1 Multiplication-Sign 10{sup -3} rad) consists of a discrete set of 8 Multiplication-Sign 8 directions. (control of laser radiation parameters)

Kachalin, G N; Pevny, S N; Pivkin, A N; Safronov, A S [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

2012-08-31T23:59:59.000Z

26

Space-Time Insight | Open Energy Information  

Open Energy Info (EERE)

Space-Time Insight Space-Time Insight Jump to: navigation, search Name Space-Time Insight Address 45680 Northport Loop East Place Fremont, California Zip 94538 Sector Efficiency Product SpaceTime Awareness Server Year founded 2008 Number of employees 11-50 Website http://www.spacetimeinsight.co Coordinates 37.4923832°, -121.9532879° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.4923832,"lon":-121.9532879,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

27

Space, time and nesting Integrated Assessment Models  

Science Conference Proceedings (OSTI)

Integrated Assessment Modelling in the field of air pollution has advanced greatly since the 1985 Helsinki Protocol on the reduction of Sulphur emissions and their transboundary fluxes. With subsequent protocols and increased understanding of the inter-relationships ... Keywords: CLRTAP, Integrated Assessment Modelling, Scale, Science-policy interaction, Space, Time

T. Oxley; H. M. ApSimon

2007-12-01T23:59:59.000Z

28

On the Metric of Space-time  

E-Print Network (OSTI)

Maxwell's equations are obeyed in a one-parameter group of isotropic gravity-free flat space-times whose metric depends upon the value of the group parameter. An experimental determination of this value has been proposed. If it is zero, the metric is Minkowski's. If it is non-zero, the metric is not Poincare invariant and local frequencies of electromagnetic waves change as they propagate. If the group parameter is positive, velocity independent red shifts develop and the group parameter plays a role similar to that of Hubble's constant in determining the relation of these redshifts to propagation distance. In the resulting space-times, the velocity dependence of Doppler shifts is a function of propagation distance. If the group parameter and Hubble's constant have the same order of magnitude, observed frequency shifts in radiation received from stellar sources can imply source velocities quite different from those implied in Minkowski space. In these space-times, electromagnetic waves received from bodies in galactic Kepler orbits undergo frequency shifts which are indistinguishable from shifts currently attributed to dark matter and dark energy in Minkowski space, or to a non-Newtonian physics.

Carl E. Wulfman

2013-02-02T23:59:59.000Z

29

Symmetry Energy from Holographic QCD  

E-Print Network (OSTI)

We review the symmetry energy in the context of AdS/CFT correspondence. After constructing $D$ brane configurations corresponding to dense system in boundary theory, we calculate the symmetry energy by solving DBI action of $D$ branes in confining and deconfining phase. We conclude the density dependence of the symmetry energy has scaling law whose power depends only on dimensionality of the branes and space-time.

Seo, Yunseok

2013-01-01T23:59:59.000Z

30

Space-time thermodynamics of the glass transition  

E-Print Network (OSTI)

Space-time Thermodynamics of the Glass Transition Maurobehavior in terms of a thermodynamics of trajectory space.

Merolle, Mauro; Garrahan, Juan P.; Chandler, David

2005-01-01T23:59:59.000Z

31

Interpretations of Space-Time Spectral Energy Equations  

Science Conference Proceedings (OSTI)

Interpretations are given of two different formulations of space-time spectral energy equations derived by Kao (1968) and Hayashi (1980).

Yoshikazu Hayashi

1982-03-01T23:59:59.000Z

32

Efficiently decoded full-rate space-time block codes  

Science Conference Proceedings (OSTI)

Space-time block codes with orthogonal structures typically provide full-diversity reception and simple receiver processing. However, rate-1 orthogonal codes for complex constellations have not been found for more than two transmit antennas. By using ... Keywords: diversity, genetic algorithm, quasi-orthogonal codes, space-time block codes

Don Torrieri; Matthew C. Valenti

2010-02-01T23:59:59.000Z

33

Surveillance to detect emerging space-time clusters  

Science Conference Proceedings (OSTI)

The interest is on monitoring incoming space-time events to detect an emergent space-time cluster as early as possible. Assume that point process events are continuously recorded in space and time. In a certain unknown moment, a small localized cluster ...

Renato Assunção; Thais Correa

2009-06-01T23:59:59.000Z

34

Bayesian dynamic models for space-time point processes  

Science Conference Proceedings (OSTI)

In this work we propose a model for the intensity of a space-time point process, specified by a sequence of spatial surfaces that evolve dynamically in time. This specification allows flexible structures for the components of the model, in order to handle ... Keywords: Bayesian inference, Disease mapping, Dynamic models, Integrated Laplace, Monte Carlo Markov chain, Space-time point processes

Edna A. Reis; Dani Gamerman; Marina S. Paez; Thiago G. Martins

2013-04-01T23:59:59.000Z

35

Quantum theory and gravity from a space-time wave  

E-Print Network (OSTI)

The quantum properties and gravitational field of a particle system are derived from a quantum theory of space-time. A field with quantized space-time vibrations has the same properties and equations for a particle field in quantum theory. The statistical nature of quantum mechanics can be explained by assuming the amplitudes of space-time waves serve as additional variables of the theory. The difficulty of associating a physical meaning with the quantum wave due to the unobservable overall phase is resolved. Instead of attempting to derive the properties of space-time from a quantum theory, as is usually the case, the quantum properties of matter can be derived from a theory of space-time. The energy of a space-time wave must correspond to the rest mass of a real particle; the vibrations are thus quantized. It is also demonstrated that the geometrical structure derived from a quantized space-time vibration is equivalent to the gravitational field of a point mass in general relativity. The fundamental questions of why and how a point mass gives rise to its gravitational singularity and curved space-time geometry can thereby be explained.

Hou Yau

2007-06-01T23:59:59.000Z

36

Quantum Geometry of the Dynamical Space-time  

E-Print Network (OSTI)

Quantum theory of field (extended) objects without a priori space-time geometry has been represented. Intrinsic coordinates in the tangent fibre bundle over complex projective Hilbert state space $CP(N-1)$ are used instead of space-time coordinates. The fate of quantum system modeled by the generalized coherent states is rooted in this manifold. Dynamical (state-dependent) space-time arises only at the stage of the quantum "yes/no" measurement. The quantum measurement of the gauge ``field shell'' of the generalized coherent state is described in terms of the affine parallel transport of the local dynamical variables in $CP(N-1)$.

Peter Leifer

2006-11-20T23:59:59.000Z

37

An almost sure invariance principle for random walks in a space-time random environment  

E-Print Network (OSTI)

We consider a discrete time random walk in a space-time i.i.d. random environment. We use a martingale approach to show that the walk is diffusive in almost every fixed environment. We improve on existing results by proving an invariance principle and considering environments with an annealed $L^2$ drift. We also state an a.s. invariance principle for random walks in general random environments whose hypothesis requires a subdiffusive bound on the variance of the quenched mean, under an ergodic invariant measure for the environment chain.

F. Rassoul-Agha; T. Seppalainen

2004-11-26T23:59:59.000Z

38

Detecting Climate Signals Using Space–Time EOFs  

Science Conference Proceedings (OSTI)

Estimates of the amplitudes of the forced responses of the surface temperature field over the last century are provided by a signal processing scheme utilizing space–time empirical orthogonal functions for several combinations of station sites ...

Gerald R. North; Qigang Wu

2001-04-01T23:59:59.000Z

39

Variability of Space–Time Mean Rain Rate  

Science Conference Proceedings (OSTI)

A mixed lognormal distribution is fit to rain-rate data for the purpose of estimating the space–time mean. Using Fisher information, the large sample variance is obtained for grouped and ungrouped data estimates. The asymptotic variance results ...

B. Kedem; R. Pfeiffer; D. A. Short

1997-05-01T23:59:59.000Z

40

Quantum mechanics as "space-time statistical mechanics"?  

E-Print Network (OSTI)

In this paper we discuss and analyse the idea of trying to see (non-relativistic) quantum mechanics as a ``space-time statistical mechanics'', by using the classical statistical mechanical method on objective microscopic space-time configurations. It is argued that this could perhaps be accomplished by giving up the assumption that the objective ``state'' of a system is independent of a future measurement performed on the system. This idea is then applied in an example of quantum state estimation on a qubit system.

Anders Månsson

2005-01-24T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

A massively space-time parallel N-body solver  

Science Conference Proceedings (OSTI)

We present a novel space-time parallel version of the Barnes-Hut tree code pepc using pfasst, the Parallel Full Approximation Scheme in Space and Time. The naive use of increasingly more processors for a fixed-size N-body problem is prone to saturate ...

R. Speck; D. Ruprecht; R. Krause; M. Emmett; M. Minion; M. Winkel; P. Gibbon

2012-11-01T23:59:59.000Z

42

Scalar Metric fluctuations in space time matter inflation  

E-Print Network (OSTI)

Using the Ponce de Leon background metric, which describes a 5D universe in an apparent vacuum: $\\bar{G}_{AB}=0$, we study the effective 4D evolution of both, the inflaton and gauge-invariant scalar metric fluctuations, in the recently introduced model of space time matter inflation.

Mariano Anabitarte; Mauricio Bellini

2006-05-15T23:59:59.000Z

43

Energy Distribution of a Gödel-Type Space-Time  

E-Print Network (OSTI)

We calculate the energy and momentum distributions associated with a G\\"{o}del-type space-time, using the well-known energy-momentum complexes of Landau and Lifshitz and M{\\o}ller. We show that the definitions of Landau and Lifshitz and M{\\o}ller do not furnish a consistent result.

Ragab M. Gad

2004-01-10T23:59:59.000Z

44

Parabosonic string and space-time non-commutativity  

Science Conference Proceedings (OSTI)

We investigate the para-quantum extension of the bosonic strings in a non-commutative space-time. We calculate the trilinear relations between the mass-center variables and the modes and we derive the Virasoro algebra where a new anomaly term due to the non-commutativity is obtained.

Seridi, M. A.; Belaloui, N. [Laboratoire de Physique Mathematique et Subatomique, Universite Mentouri Constantine (Algeria)

2012-06-27T23:59:59.000Z

45

Space-Time Diffeomorphisms in Noncommutative Gauge Theories  

E-Print Network (OSTI)

In previous work [Rosenbaum M. et al., J. Phys. A: Math. Theor. 40 (2007), 10367-10382, hep-th/0611160] we have shown how for canonical parametrized field theories, where space-time is placed on the same footing as the other fields in the theory, the representation of space-time diffeomorphisms provides a very convenient scheme for analyzing the induced twisted deformation of these diffeomorphisms, as a result of the space-time noncommutativity. However, for gauge field theories (and of course also for canonical geometrodynamics) where the Poisson brackets of the constraints explicitely depend on the embedding variables, this Poisson algebra cannot be connected directly with a representation of the complete Lie algebra of space-time diffeomorphisms, because not all the field variables turn out to have a dynamical character [Isham C.J., Kuchar K.V., Ann. Physics 164 (1985), 288-315, 316-333]. Nonetheless, such an homomorphic mapping can be recuperated by first modifying the original action and then adding addi...

Rosenbaum, Marcos; Juarez, L Roman

2008-01-01T23:59:59.000Z

46

Adaptive space-time transmission with side information  

Science Conference Proceedings (OSTI)

In this letter, a simple adaptive transmit diversity technique with side information is presented. The proposed scheme has a number of attractive characteristics. First, it is simple to implement. Second, it is efficient in terms of bandwidth requirements ... Keywords: Space-time block code, transmit diversity, wireless communications

T. Lo

2004-09-01T23:59:59.000Z

47

Ruler measurements give space-time-transformation-independent invariant lengths  

E-Print Network (OSTI)

Two thought experiments are described in which ruler measurements of spatial intervals are performed in different reference frames. They demonstrate that such intervals are frame-independent as well as independent of the nature of the space-time transformation equations. As explained in detail elsewhere, the `length contraction' effect of conventional special relativity theory is therefore spurious and unphysical.

J. H. Field

2013-07-30T23:59:59.000Z

48

Comparing non-stationary and irregularly spaced time series  

Science Conference Proceedings (OSTI)

In this paper, we present approximate distributions for the ratio of the cumulative wavelet periodograms considering stationary and non-stationary time series generated from independent Gaussian processes. We also adapt an existing procedure to use this ... Keywords: Distributions of quadratic forms, Hypothesis testing, Irregularly spaced time series, Locally stationary wavelet processes, Multiresolution approximation

Gladys E. Salcedo; RogéRio F. Porto; Pedro A. Morettin

2012-12-01T23:59:59.000Z

49

Ramifications of Discrete R Symmetries Rethinking Naturalness  

E-Print Network (OSTI)

, generic. Elaborate models to explain real data are one thing; Rube Goldberg contraptions to explain

California at Santa Cruz, University of

50

Fundamental Symmetries and Interactions  

E-Print Network (OSTI)

In nuclear physics numerous possibilities exist to investigate fundamental symmetries and interactions. In particular, the precise measurements of properties of fundamental fermions, searches for new interactions in ?-decays, and violations of discrete symmeties offer possibilities to search for physics beyond standard theory. Precise measurements of fundamental constants can be carried out. Low energy experiments allow to probe New Physics at mass scales far beyond the reach of present accelerators or such planned for the future and at which predicted new particles could be produced directly. 1. Fundamental Forces and Symmetries Symmetries play an important and crucial role in physics. Global symmetries give rise to conservation laws and local symmetries yield forces [ 1]. To date we know four fundamental interactions: (i) Electromagnetism, (ii) Weak Interactions, (iii) Strong Interactions, and (iv) Gravitation. These four forces are fundamental in the sense that all observed dynamical processes in physics can be traced back to one or a combination of them. Together with fundamental symmetries they from a framework on which all physical descriptions ultimately rest.

Klaus P. Jungmann A; Kernfysisch Versneller Instituut

2005-01-01T23:59:59.000Z

51

The Xi-transform for conformally flat space-time  

E-Print Network (OSTI)

The Xi-transform is a new spinor transform arising naturally in Einstein's general relativity. Here the example of conformally flat space-time is discussed in detail. In particular it is shown that for this case, the transform coincides with two other naturally defined transforms: one a two-variable transform on the Lie group SU(2, C), the other a transform on the space of null split octaves. The key properties of the transform are developed.

George Sparling

2006-12-01T23:59:59.000Z

52

ADER-WENO Finite Volume Schemes with Space-Time Adaptive Mesh Refinement  

E-Print Network (OSTI)

We present the first high order one-step ADER-WENO finite volume scheme with Adaptive Mesh Refinement (AMR) in multiple space dimensions. High order spatial accuracy is obtained through a WENO reconstruction, while a high order one-step time discretization is achieved using a local space-time discontinuous Galerkin predictor method. Due to the one-step nature of the underlying scheme, the resulting algorithm is particularly well suited for an AMR strategy on space-time adaptive meshes, i.e.with time-accurate local time stepping. The AMR property has been implemented 'cell-by-cell', with a standard tree-type algorithm, while the scheme has been parallelized via the Message Passing Interface (MPI) paradigm. The new scheme has been tested over a wide range of examples for nonlinear systems of hyperbolic conservation laws, including the classical Euler equations of compressible gas dynamics and the equations of magnetohydrodynamics (MHD). High order in space and time have been confirmed via a numerical convergenc...

Dumbser, Michael; Hidalgo, Arturo; Balsara, Dinshaw S

2012-01-01T23:59:59.000Z

53

A Topological Extension of General Relativity to Explore the Nature of Quantum Space-time, Dark Energy and Inflation  

E-Print Network (OSTI)

General Relativity is extended into the quantum domain. A thought experiment is explored to derive a specific topological build-up for Planckian space-time. The presented arguments are inspired by Feynman's path integral for superposition and Wheeler's quantum foam of Planck mass mini black holes/wormholes. Paths are fundamental and prime 3-manifolds like T^3, S^1xS^2 and S^3 are used to construct quantum space-time. A physical principle is formulated that causes observed paths to multiply: It takes one to know one. So topological fluctuations on the Planck scale take the form of multiple copies of any homeomorphically distinct path through quantum space-time. The discrete time equation of motion for this topological quantum gravity is derived by counting distinct paths globally. The equation of motion is solved to derive some properties of dark energy and inflation. The dark energy density depends linearly on the number of macroscopic black holes in the universe and is time dependent in a manner consistent with current astrophysical observations, having an effective equation of state w=-1.1 for redshifts smaller than unity. Inflation driven by mini black holes proceeds over n=55 e-foldings, without strong inhomogeneity, a scalar-to-tensor ratio r=ln(7)/n=0.036 and a spectral index n_s=1-r=0.964. A discrete time effect visible in the cosmic microwave background is suggested.

Marco Spaans

2013-05-20T23:59:59.000Z

54

Correlation of the electrical and space-time characteristics during electrical explosion of wires  

SciTech Connect

The electrical and space-time characteristics during electrical explosion of wires is studied. (AIP)

Litvinenko, V.P.; Koval' , S.V.

1983-04-01T23:59:59.000Z

55

The Dynamical Discrete Web  

E-Print Network (OSTI)

The dynamical discrete web (DDW), introduced in recent work of Howitt and Warren, is a system of coalescing simple symmetric one-dimensional random walks which evolve in an extra continuous dynamical parameter s. The evolution is by independent updating of the underlying Bernoulli variables indexed by discrete space-time that define the discrete web at any fixed s. In this paper, we study the existence of exceptional (random) values of s where the paths of the web do not behave like usual random walks and the Hausdorff dimension of the set of such exceptional s. Our results are motivated by those about exceptional times for dynamical percolation in high dimension by H\\"aggstrom, Peres and Steif, and in dimension two by Schramm and Steif. The exceptional behavior of the walks in DDW is rather different from the situation for dynamical random walks of Benjamini, H\\"aggstrom, Peres and Steif. In particular, we prove that there are exceptional values of s for which the walk from the origin S^s(n) has limsup S^s(n)/\\sqrt n \\leq K with a nontrivial dependence of the Hausdorff dimension on K. We also discuss how these and other results extend to the dynamical Brownian web, a natural scaling limit of DDW. The scaling limit is the focus of a paper in preparation; it was studied by Howitt and Warren and is related to the Brownian net of Sun and Swart.

L. R. G. Fontes; C. M. Newman; K. Ravishankar; E. Schertzer

2007-04-20T23:59:59.000Z

56

Dirac Quantization Condition for Monopole in Noncommutative Space-Time  

E-Print Network (OSTI)

Since the structure of space-time at very short distances is believed to get modified possibly due to noncommutativity effects and as the Dirac Quantization Condition (DQC), $\\mu e = \\frac{N}{2}\\hbar c$, probes the magnetic field point singularity, a natural question arises whether the same condition will still survive. We show that the DQC on a noncommutative space in a model of dynamical noncommutative quantum mechanics remains the same as in the commutative case to first order in the noncommutativity parameter $\\theta$, leading to the conjecture that the condition will not alter in higher orders.

Chaichian, Masud; Langvik, Miklos; Tureanu, Anca

2009-01-01T23:59:59.000Z

57

Quantum mechanics in curved space-time II  

E-Print Network (OSTI)

This paper is a sequence of the work presented in [1], where, the principles of the general relativity have been used to formulate quantum wave equations taking into account the effect of the electromagnetic and strong interactions in the space-time metric of quantum systems. Now, the role of the energy-momentum tensor in this theory is studied, and it is consistent with the formulation of the general quantum mechanics shown in [1]. With this procedure, a dynamical cut-off is generated and the constant $A$ of the field equation is calculated.

C. C. Barros Jr

2005-09-01T23:59:59.000Z

58

Comparison of some Lie-symmetry-based integrators  

Science Conference Proceedings (OSTI)

Lie-symmetry based integrators are constructed in order to preserve the local invariance properties of the equations. The geometrical methods leading to discretized equations for numerical computations involve many different concepts. Therefore they ... Keywords: Discrete differential invariant, Invariant scheme, Lie group method, Moving frame, Symmetry

M. Chhay; E. Hoarau; A. Hamdouni; P. Sagaut

2011-03-01T23:59:59.000Z

59

Photon Green Functions in Curved Space-Time  

E-Print Network (OSTI)

Quantization of electrodynamics in curved space-time in the Lorenz gauge and with arbitrary gauge parameter makes it necessary to study Green functions of non-minimal operators with variable coefficients. Starting from the integral representation of photon Green functions, we link them to the evaluation of integrals involving Gamma-functions. Eventually, the full asymptotic expansion of the Feynman photon Green function at small values of the world function, as well as its explicit dependence on the gauge parameter, are obtained without adding by hand a mass term to the Faddeev-Popov Lagrangian. Coincidence limits of second covariant derivatives of the associated Hadamard function are also evaluated, as a first step towards the energy-momentum tensor in the non-minimal case.

Giuseppe Bimonte; Enrico Calloni; Luciano Di Fiore; Giampiero Esposito; Leopoldo Milano; Luigi Rosa

2005-11-23T23:59:59.000Z

60

Fundamental Symmetries and Interactions  

E-Print Network (OSTI)

In Nuclear Physics numerous possibilities exist to investigate fundamental symmetries and interactions. In particular, the precise measurements of properties of fundamental fermions, searches for new interactions in $\\beta$-decays, and violations of discrete symmeties offer possibilities to search for physics beyond Standard Theory. Precise measurements of fundamental constants can be carried out. Low energy experiments allow to probe New Physics at mass scales far beyond the reach of present accelerators or such planned for the future and at which predicted new particles could be produced directly.

Klaus P. Jungmann

2005-02-10T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Symmetry Energy  

E-Print Network (OSTI)

Examination of symmetry energy is carried out on the basis of an elementary binding-energy formula. Constraints are obtained on the energy value at the normal nuclear density and on the density dependence of the energy at subnormal densities.

P. Danielewicz

2006-07-15T23:59:59.000Z

62

A Method of Estimating Space-Time Spectra from Polar-Orbiting Satellite Data  

Science Conference Proceedings (OSTI)

Space-time spectral formulas are modified to estimate wavenumber-frequency spectra correctly from space-time series data sampled at the same local time but at different hours of a day by a polar-orbiting satellite.

Yoshikazu Hayashi

1980-06-01T23:59:59.000Z

63

Two methods of space-time energy densification  

SciTech Connect

With a view to the goal of net energy production from a DT microexplosion, two ideas (methods) are studied through which (separately or in combination) energy may be ''concentrated'' into a small volume and short period of time--the so-called space-time energy densification or compression. The advantages and disadvantages of lasers and relativistic electron-beam (E-beam) machines as the sources of such energy are studied and the amplification of laser pulses as a key factor in energy compression is discussed. The pulse length of present relativistic E-beam machines is the most serious limitation of this pulsed-power source. The first energy-compression idea discussed is the reasonably efficient production of short-duration, high-current relativistic electron pulses by the self interruption and restrike of a current in a plasma pinch due to the rapid onset of strong turbulence. A 1-MJ plasma focus based on this method is nearing completion at this Laboratory. The second energy- compression idea is based on laser-pulse production through the parametric amplification of a self-similar or solitary wave pulse, for which analogs can be found in other wave processes. Specifically, the second energy-compression idea is a proposal for parametric amplification of a solitary, transverse magnetic pulse in a coaxial cavity with a Bennett dielectric rod as an inner coax. Amplifiers of this type can be driven by the pulsed power from a relativistic E- beam machine. If the end of the inner dielectric coax is made of LiDT or another fusionable material, the amplified pulse can directly drive a fusion reaction-- there would be no need to switch the pulse out of the system toward a remote target. (auth)

Sahlin, H.L.

1975-07-15T23:59:59.000Z

64

DISCRETE TRANSPARENT BOUNDARY CONDITIONS FOR WIDE ANGLE PARABOLIC EQUATIONS IN UNDERWATER  

E-Print Network (OSTI)

DISCRETE TRANSPARENT BOUNDARY CONDITIONS FOR WIDE ANGLE PARABOLIC EQUATIONS IN UNDERWATER ACOUSTICS "parabolic" equations (WAPEs) in underwater acoustics (assuming cylindrical symmetry). Existing the discretization of transparent bottom boundary conditions. In oceanography one wants to calculate the underwater

Ehrhardt, Matthias

65

The space-time CESE method for solving special relativistic hydrodynamic equations  

Science Conference Proceedings (OSTI)

The special relativistic hydrodynamic equations are more complicated than the classical ones due to the nonlinear and implicit relations that exist between conservative and primitive variables. In this article, a space-time conservation element and solution ... Keywords: Conservation laws, Discontinuous solutions, Hyperbolic systems, Space-time CESE method, Special relativistic hydrodynamics

Shamsul Qamar; Muhammad Yousaf

2012-05-01T23:59:59.000Z

66

Power allocation strategies for distributed space-time codes in two-way relay networks  

Science Conference Proceedings (OSTI)

We study a two-way relay network (TWRN), where distributed space-time codes are constructed across multiple relay terminals in an amplify-and-forward mode. Each relay transmits a scaled linear combination of its received symbols and their conjugates, ... Keywords: distributed space-time codes, power allocation, two-way relay channel

Wenjin Wang; Shi Jin; Xiqi Gao; Kai-Kit Wong; Matthew R. McKay

2010-10-01T23:59:59.000Z

67

Cooperative Space---Time Coding with Amplify-and- Forward Relaying  

Science Conference Proceedings (OSTI)

Cooperative diversity using distributed space-time codes has been recently proposed to form virtual antennas in order to achieve diversity gain. In this paper, we consider a multi-relay network operating in amplify-and-forward (AAF) mode. Motivated by ... Keywords: AAF relaying, Cooperative communications, Space---time coding, Spatial diversity

Azzam Y. Al-Nahari; Moawad I. Dessouky; Fathi E. Abd El-Samie

2012-05-01T23:59:59.000Z

68

Distributed GABBA space-time codes in amplify-and-forward relay networks  

Science Conference Proceedings (OSTI)

Cooperative communications via distributed space-time codes has been recently proposed as a way to form virtual multiple-antennas that provide dramatic gains in slow fading wireless environments. In this paper, we consider the design of practical distributed ... Keywords: cooperative communications, distributed space-time codes, performance analysis, wireless relay network

Behrouz Maham; Are Hjørungnes; Giuseppe Abreu

2009-04-01T23:59:59.000Z

69

Leveraging coherent distributed space-time codes for noncoherent communication in relay networks via training  

Science Conference Proceedings (OSTI)

For point to point multiple input multiple output systems, Dayal-Brehler-Varanasi have proved that training codes achieve the same diversity order as that of the underlying coherent space time block code (STBC) if a simple minimum mean squared error ... Keywords: cooperative diversity, distributed space time block code, noncoherent communication, training

G. Susinder Rajan; B. Sundar Rajan

2009-02-01T23:59:59.000Z

70

Performance analysis of space-time block codes in flat fading MIMO channels with offsets  

Science Conference Proceedings (OSTI)

We consider the effect of imperfect carrier offset compensation on the performance of space-time block codes. The symbol error rate (SER) for orthogonal space-time block code (OSTBC) is derived here by taking into account the carrier offset and the resulting ...

Manav R. Bhatnagar; R. Vishwanath; Vaibhav Bhatnagar

2007-01-01T23:59:59.000Z

71

Data detection and Kalman estimation for multiple space-time trellis codes  

Science Conference Proceedings (OSTI)

This work presents a joint channel estimation and data detection algorithm over high Doppler fading channels, for Space-Time Trellis Codes (STTCs) having more than one code vector per trellis branch. Such codes are referred to as Multiple STTCs (MSTTCs). ... Keywords: Doppler channels, Kalman estimation, channel estimation, decoding, fading channels, per-survivor processing, space-time trellis codes

Usa Vilaipornsawai; Harry Leib

2009-09-01T23:59:59.000Z

72

SYMMETRY Contract  

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

SYMMETRY SYMMETRY Contract - - L E G A L N O T I C E The Enrico Fermi I n s t i t u t e f o r Nuclear S t u d i e s and Department o f Physics, t h e U n i v e r s i t y of Chicago, Chicago, I l l i n o i s Outline of Talks Delivered a t t h e I n t e r n a t i o n a l Conference on Elementary P a r t i c l e s and a t t h e Symposium on Elementary P a r t i c l e s Kyoto, September 1965 Revised January 1 9 6 6 FELLEASED @R ANNOUNCEMENT N J C U SCIENCE ABSTRACTS No. AT ( 11-1) -264 EFINS 06-19 3 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process

73

An Approach to Integrate a Space-Time GIS Data Model with High Performance Computers  

Science Conference Proceedings (OSTI)

In this paper, we describe an approach to integrate a Space-Time GIS data model on a high performance computing platform. The Space-Time GIS data model has been developed on a desktop computing environment. We use the Space-Time GIS data model to generate GIS module, which organizes a series of remote sensing data. We are in the process of porting the GIS module into an HPC environment, in which the GIS modules handle large dataset directly via parallel file system. Although it is an ongoing project, authors hope this effort can inspire further discussions on the integration of GIS on high performance computing platforms.

Wang, Dali [ORNL; Zhao, Ziliang [University of Tennessee, Knoxville (UTK); Shaw, Shih-Lung [ORNL

2011-01-01T23:59:59.000Z

74

Validation of the Space–Time Variability of African Easterly Waves Simulated by the CNRM GCM  

Science Conference Proceedings (OSTI)

The ability of the Centre National de Recherches Météorologiques (CNRM) general circulation model (GCM) to properly simulate the space–time variability of the African easterly waves (AEWs) has been examined over the period 1982–88. The relative ...

J. P. Céron; J. F. Guérémy

1999-09-01T23:59:59.000Z

75

Electrostatic in Reissner-Nordstrom space-time with a conical defect  

E-Print Network (OSTI)

We calculate the electrostatic potential generated by a point charge in the space-time of Reissner-Nordstrom with a conical defect. An expression for the self-energy is also presented.

J. Spinelly; V. B. Bezerra

2000-12-19T23:59:59.000Z

76

ENSO Impact on the Space–Time Evolution of the Regional Asian Summer Monsoons  

Science Conference Proceedings (OSTI)

This study investigates how ENSO affects the space–time evolution of the Asian summer monsoon (ASM) precipitation and synoptic variables on a 5-day resolution over the entire ASM area. Cyclostationary EOF and regression methods were used to ...

Young-Kwon Lim; Kwang-Yul Kim

2007-06-01T23:59:59.000Z

77

On the Space–Time Scales of the Surface Solar Radiation Field  

Science Conference Proceedings (OSTI)

The characteristic space–time scales of surface solar radiation fields measured by the 111-instrument MESONET in Oklahoma are estimated after removal of the diurnal cycle. These estimates of “within-day” variability are used to deduce the ...

T. P. Barnett; J. Ritchie; J. Foat; G. Stokes

1998-01-01T23:59:59.000Z

78

Space–Time Variability of Rainfall and Extreme Flood Response in the Menomonee River Basin, Wisconsin  

Science Conference Proceedings (OSTI)

The hydrometeorological processes that control flash flooding are examined through analyses of space–time rainfall variability and flood response in the Milwaukee metropolitan region. The analyses focus on four flood events in the Menomonee River ...

Yu Zhang; James A. Smith

2003-06-01T23:59:59.000Z

79

Combining GA and iterative MVDR for DOA estimation in space-time CDMA systems  

Science Conference Proceedings (OSTI)

This paper deals with direction-of-arrival (DOA) estimation of minimum variance distortionless response (MVDR) approach based on iterative searching technique for space-time code-division multiple access (CDMA) systems. It has been shown that the iterative ...

Jhih-Chung Chang

2012-11-01T23:59:59.000Z

80

Applications of Asynoptic Space–Time Fourier Transform Methods to Scanning Satellite Measurements  

Science Conference Proceedings (OSTI)

A method proposed by Salby for computing the zonal space-time Fourier transform of asynoptically acquired satellite data has been tested and applied to soundings of brightness temperature taken by polar-orbiting satellites. The technique, which ...

Leslie R. Lait; John L. Stanford

1988-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Home range plus: A space-time characterization of movement over real landscapes  

E-Print Network (OSTI)

article as: Lyons et al. : Home range plus: a space-timeJM, Moorcroft PR: The home-range concept: Are traditionalMJ: A Critical Review of Home Range Studies. Journal of

Lyons, Andrew J; Turner, Wendy C; Getz, Wayne M

2013-01-01T23:59:59.000Z

82

Temporal variations in space-time and progenitors of gamma ray burst and millisecond pulsars  

E-Print Network (OSTI)

A time varying space-time metric is shown to be a source of electromagnetic radiation. The post-Newtonian approximation is used as a realistic model of the connection between the space-time metric and a time varying gravitational potential. Large temporal variations in the metric from the coalescence of colliding black holes and neutron stars are shown to be possible progenitors of gamma ray burst and millisecond pulsars.

Preston Jones

2006-06-23T23:59:59.000Z

83

Localized energy estimates for wave equations on high dimensional Schwarzschild space-times  

E-Print Network (OSTI)

The localized energy estimate for the wave equation is known to be a fairly robust measure of dispersion. Recent analogs on the $(1+3)$-dimensional Schwarzschild space-time have played a key role in a number of subsequent results, including a proof of Price's law. In this article, we explore similar localized energy estimates for wave equations on $(1+n)$-dimensional hyperspherical Schwarzschild space-times.

Laul, Parul

2010-01-01T23:59:59.000Z

84

Stabilized space---time computation of wind-turbine rotor aerodynamics  

Science Conference Proceedings (OSTI)

We show how we use the Deforming-Spatial-Domain/Stabilized Space---Time (DSD/SST) formulation for accurate 3D computation of the aerodynamics of a wind-turbine rotor. As the test case, we use the NREL 5MW offshore baseline wind-turbine rotor. This class ... Keywords: DSD/SST formulation, Rotating turbulent flow, Space---time variational multiscale method, Torque values, Wind-turbine aerodynamics

Kenji Takizawa; Bradley Henicke; Tayfun E. Tezduyar; Ming-Chen Hsu; Yuri Bazilevs

2011-09-01T23:59:59.000Z

85

Two-Dimensional Conformal Models of Space-Time and Their Compactification  

E-Print Network (OSTI)

We study geometry of two-dimensional models of conformal space-time based on the group of Moebius transformation. The natural geometric invariants, called cycles, are used to linearise Moebius action. Conformal completion of the space-time is achieved through an addition of a zero-radius cycle at infinity. We pay an attention to the natural condition of non-reversibility of time arrow in order to get a correct compactification in the hyperbolic case.

Vladimir V. Kisil

2006-11-21T23:59:59.000Z

86

NIST: Methane Symmetry Operations  

Science Conference Proceedings (OSTI)

*. Bookmark and Share. Version History Methane Symmetry Operations. JT Hougen Optical Technology Division Gloria Wiersma ...

2010-10-05T23:59:59.000Z

87

Measuring the foaminess of space-time with gravity-wave interferometers  

E-Print Network (OSTI)

By analyzing a gedanken experiment designed to measure the distance $l$ between two spatially separated points, we find that this distance cannot be measured with uncertainty less than $(ll_P^2)^{1/3}$, considerably larger than the Planck scale $l_P$ (or the string scale in string theories), the conventional wisdom uncertainty in distance measurements. This limitation to space-time measurements is interpreted as resulting from quantum fluctuations of space-time itself. Thus, at very short distance scales, space-time is "foamy." This intrinsic foaminess of space-time provides another source of noise in the interferometers. The LIGO/VIRGO and LISA generations of gravity-wave interferometers, through future refinements, are expected to reach displacement noise levels low enough to test our proposed degree of foaminess in the structure of space-time. We also point out a simple connection to the holographic principle which asserts that the number of degrees of freedom of a region of space is bounded by the area of the region in Planck units.

Y. Jack Ng; H. van Dam

1999-06-01T23:59:59.000Z

88

Relativistic Pseudospin Symmetry  

Science Conference Proceedings (OSTI)

We show that the pseudospin symmetry that Akito Arima discovered many years ago (with collaborators) is a symmetry of the the Dirac Hamiltonian for which the sum of the scalar and vector potentials are a constant. In this paper we discuss some of the implications of this relativistic symmetry and the experimental data that support these predictions. In his original paper Akito also discussed pseudo-U(3) symmetry. We show that pseudo-U(3) symmetry is a symmetry of the Dirac Hamiltonian for which the sum of harmonic oscillator vector and scalar potentials are equal to a constant, and we give the generators of pseudo-U(3) symmetry. Going beyond the mean field we summarize new results on non relativistic shell model Hamiltonians that have pseudospin symmetry and pseudo-orbital angular momentum symmetry as a dynamical symmetries.

Ginocchio, Joseph N. [MS 283, Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States)

2011-05-06T23:59:59.000Z

89

On discrete cosine transform  

E-Print Network (OSTI)

The discrete cosine transform (DCT), introduced by Ahmed, Natarajan and Rao, has been used in many applications of digital signal processing, data compression and information hiding. There are four types of the discrete cosine transform. In simulating the discrete cosine transform, we propose a generalized discrete cosine transform with three parameters, and prove its orthogonality for some new cases. A new type of discrete cosine transform is proposed and its orthogonality is proved. Finally, we propose a generalized discrete W transform with three parameters, and prove its orthogonality for some new cases.

Zhou, Jianqin

2011-01-01T23:59:59.000Z

90

Energy-momentum Prescriptions in General Spherically Symmetric Space-times  

E-Print Network (OSTI)

Einstein, Landau-Lifshitz, Papapetrou, Weinberg, and M{\\o}ller energy-momentum prescriptions in general spherically symmetric space-times are investigated. It is shown that for two special but not unusual classes of general spherically symmetric space-times several energy-momentum prescriptions in Schwarzschild Cartesian coordinates lead to some coincidences in energy distribution. It is also obtained that for a special class of spherically symmetric metrics M{\\o}ller and Einstein energy-momentum prescriptions give the same result for energy distribution if and only if it has a specific dependence on radial coordinate.

Saeed Mirshekari; Amir M. Abbassi

2008-08-01T23:59:59.000Z

91

Does the Apparent Horizon Exist in the Sultana-Dyer Space-Time?  

E-Print Network (OSTI)

Sultana-Dyer space-time is suggested as a model to describe a black hole embedded in an expanding universe. Recently, some authors argued that there is a singular surface in the Sultana-Dyer space-time and the surface is covered by an apparent horizon surface. Other authors argued that such an apparent horizon does not exist. Here, by directly calculating the expansions of the radial null vector fields normal to the space-like two-spheres, we find that such an apparent horizon does not exist.

Sun, Cheng-Yi

2010-01-01T23:59:59.000Z

92

NIST: Methane Symmetry Operations - Td Symmetry Species  

Science Conference Proceedings (OSTI)

Table of Contents Methane Symmetry Operations. 11. ... Magnetic-dipole transitions are observed in molecular-beam studies of methane [42]. ...

93

Power allocation strategies for distributed space-time codes in amplify-and-forward mode  

Science Conference Proceedings (OSTI)

We consider a wireless relay network with Rayleigh fading channels and apply distributed space-time coding (DSTC) in amplify-and-forward (AF) mode. It is assumed that the relays have statistical channel state information (CSI) of the local source-relay ...

Behrouz Maham; Are Hjørungnes

2009-01-01T23:59:59.000Z

94

The stability of Killing-Cauchy horizons in colliding plane wave space-times  

E-Print Network (OSTI)

It is confirmed rigorously that the Killing-Cauchy horizons, which sometimes occur in space-times representing the collision and subsequent interaction of plane gravitational waves in a Minkowski background, are unstable with respect to bounded perturbations of the initial waves, at least for the case in which the initial waves have constant aligned polarizations.

J. B. Griffiths

2005-01-05T23:59:59.000Z

95

Distributional Energy-Momentum Tensor of the Kerr-Newman Space-Time Family  

E-Print Network (OSTI)

Using the Kerr-Schild decomposition of the metric tensor that employs the algebraically special nature of the Kerr-Newman space-time family, we calculate the energy-momentum tensor. The latter turns out to be a well-defined tensor-distribution with disk-like support.

Herbert Balasin; Herbert Nachbagauer

1993-12-17T23:59:59.000Z

96

Photon emission in a constant magnetic field in 2+1 dimensional space-time  

E-Print Network (OSTI)

We calculate by the proper-time method the amplitude of the two-photon emission by a charged fermion in a constant magnetic field in (2+1)-dimensional space-time. The relevant dynamics reduces to that of a supesymmetric quantum-mechanical system with one bosonic and one fermionic degrees of freedom.

J. T. S. Amaral; S. I. Zlatev

2005-05-11T23:59:59.000Z

97

Landau energy levels for twisted N-enlarged Newton-Hooke space-time  

E-Print Network (OSTI)

We derive the Landau energy levels for twisted N-enlarged Newton-Hooke space-time, i.e. we find the time-dependent energy spectrum and the corresponding eigenstates for an electron moving in uniform magnetic as well as in uniform electric external fields.

Daszkiewicz, Marcin

2013-01-01T23:59:59.000Z

98

Physical interpretation of gauge invariant perturbations of spherically symmetric space-times  

E-Print Network (OSTI)

By calculating the Newman-Penrose Weyl tensor components of a perturbed spherically symmetric space-time with respect to invariantly defined classes of null tetrads, we give a physical interpretation, in terms of gravitational radiation, of odd parity gauge invariant metric perturbations. We point out how these gauge invariants may be used in setting boundary and/or initial conditions in perturbation theory.

Brien C. Nolan

2004-06-11T23:59:59.000Z

99

Space-Time Wind Speed Forecasting for Improved Power System Dispatch  

E-Print Network (OSTI)

In order to support large scale integration of wind power, state-of-the-art wind speed forecasting methods should provide accurate and adequate information to enable efficient scheduling of wind power in electric energy systems. In this article, space-time wind forecasts are incorporated into power system economic dispatch models. First, we proposed a new space-time wind forecasting model, which generalizes and improves upon a so-called regime-switching space-time model by allowing the forecast regimes to vary with the dominant wind direction and with the seasons. Then, results from the new wind forecasting model are implemented into a power system economic dispatch model, which takes into account both spatial and temporal wind speed correlations. This, in turn, leads to an overall more cost-effective scheduling of system-wide wind generation portfolio. The potential economic benefits arise in the system-wide generation cost savings and in the ancillary service cost savings. This is illustrated in a test system in the northwest region of the U.S. Compared with persistent and autoregressive models, our proposed method could lead to annual integration cost savings on the scale of tens of millions of dollars in regions with high wind penetration, such as Texas and the Northwest. Key words: Power system economic dispatch; Power system operation; Space-time statistical model; Wind data; Wind speed forecasting.

Xinxin Zhu; Marc G. Genton; Yingzhong Gu; Le Xie

2012-01-01T23:59:59.000Z

100

Model of hydrogen atom for twisted acceleration-enlarged Newton-Hooke space-times  

E-Print Network (OSTI)

We define the model of hydrogen atom for twist-deformed acceleration-enlarged Newton-Hooke space-time. Further, using time-dependent perturbation theory, we find in first step of iteration procedure the solution of corresponding Schroedinger equation as well as the probability of transition between two different energy-eigenstates.

Marcin Daszkiewicz

2013-12-09T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Symmetries in physics  

E-Print Network (OSTI)

The concept of symmetries in physics is briefly reviewed. In the first part of these lecture notes, some of the basic mathematical tools needed for the understanding of symmetries in nature are presented, namely group theory, Lie groups and Lie algebras, and Noether's theorem. In the second part, some applications of symmetries in physics are discussed, ranging from isospin and flavor symmetry to more recent developments involving the interacting boson model and its extension to supersymmetries in nuclear physics.

Roelof Bijker

2005-09-02T23:59:59.000Z

102

Symmetry Breaking in Linearly Coupled Dynamical Lattices  

E-Print Network (OSTI)

We examine one- and two-dimensional (1D and 2D) models of linearly coupled lattices of the discrete-nonlinear-Schr{\\"{o}}dinger type. Analyzing ground states of the systems with equal powers in the two components, we find a symmetry-breaking phenomenon beyond a critical value of the squared $l^2$-norm. Asymmetric states, with unequal powers in their components, emerge through a subcritical pitchfork bifurcation, which, for very weakly coupled lattices, changes into a supercritical one. We identify the stability of various solution branches. Dynamical manifestations of the symmetry breaking are studied by simulating the evolution of the unstable branches. The results present the first example of spontaneous symmetry breaking in 2D lattice solitons. This feature has no counterpart in the continuum limit, because of the collapse instability in the latter case.

Herring, G; Malomed, B A; Carretero-González, R; Frantzeskakis, D J

2007-01-01T23:59:59.000Z

103

Equations Governing Space-Time Variability of Liquid Water Path in Stratus Clouds  

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

Equations Governing Space-Time Variability of Equations Governing Space-Time Variability of Liquid Water Path in Stratus Clouds K. Ivanova Pennsylvania State University University Park, Pennsylvania T. P. Ackerman Pacific Northwest National Laboratory Richland, Washington M. Ausloos University of Liège B-4000 Liège, Belgium Abstract We present a method on how to derive an underlying mathematical (statistical or model free) equation for a liquid water path (LWP) signal directly from empirical data. The evolution of the probability density functions (PDFs) from small to large time scales is explicitly derived in the framework of Fokker-Planck equation. A drift and a diffusion term describing the deterministic and stochastic influences on the non-Gaussian fat tails of the liquid water probability distributions are obtained from

104

Particle with spin S=3/2 in Riemannian space-time  

E-Print Network (OSTI)

Equations for 16-component vector-bispinor field, originated from Rarita-Schwinger Lagrangian for spin 3/2 field extended to Riemannian space-time are investigated. Additional general covariant constrains for the field are produced, which for some space-time models greatly simplify original wave equation. Peculiarities in description of the massless spin 3/2 field are specified. In the flat Minkowski space for massless case there exist gauge invariance of the main wave equation, which reduces to possibility to produce a whole class of trivial solutions in the the form of 4-gradient of arbitrary (gauge) bispinor function, \\Psi ^{0}_{c} = \\partial_{c} \\psi. Generalization of that property for Riemannian model is performed; it is shown that in general covariant case solutions of the gradient type \\Psi^{0}_{\\beta} = (\

Red'kov, V M

2011-01-01T23:59:59.000Z

105

The C-metric as a colliding plane wave space-time  

E-Print Network (OSTI)

It is explicitly shown that part of the C-metric space-time inside the black hole horizon may be interpreted as the interaction region of two colliding plane waves with aligned linear polarization, provided the rotational coordinate is replaced by a linear one. This is a one-parameter generalization of the degenerate Ferrari-Ibanez solution in which the focussing singularity is a Cauchy horizon rather than a curvature singularity.

J. B. Griffiths; R. G. Halburd

2007-01-10T23:59:59.000Z

106

Space-time curvature due to quantum vacuum fluctuations: An alternative to dark energy?  

E-Print Network (OSTI)

It is pointed out that quantum vacuum fluctuations may give rise to a curvature of space-time equivalent to the curvature currently attributed to dark energy. A simple calculation is made, which suggests that the value of the dark energy density is roughly given by the product of Newton constant time the quantity m^6 c^4 h^-4, m being a typical mass of elementary particles. The estimate is compatible with observations.

Santos, Emilio

2010-01-01T23:59:59.000Z

107

The Energy Distribution in a Static Spherically Symmetric Nonsingular Black Hole Space-Time  

E-Print Network (OSTI)

We calculate the energy distribution in a static spherically symmetric nonsingular black hole space-time by using the Tolman's energy-momentum complex. All the calculations are performed in quasi-Cartesian coordinates. The energy distribution is positive everywhere and be equal to zero at origin. We get the same result as obtained by Y-Ching Yang by using the Einstein's and Weinberg's prescriptions.

I. Radinschi

2000-08-14T23:59:59.000Z

108

Renormalization of quantum field theory on curved space-times, a causal approach  

E-Print Network (OSTI)

The subject of the thesis is the construction of a perturbative quantum theory of interacting fields on a curved space-time, following a point of view pioneered by Stueckelberg and Bogoliubov and developed by Epstein-Glaser on the flat Minkowski space-time. In 2000, a breakthrough was done by Brunetti and Fredenhagen who were able to extend the Epstein-Glaser theory by exploiting the point of view developed by Radzikowski to define quantum states on a curved space-time in terms of wave-front sets. These results were further extended by Fredenhagen, Brunetti, Hollands, Wald, Rejzner, etc. to Yang-Mills fields and the gravitation. However, even for theories without gauge invariance, many mathematical details were left unexplored and unquestioned. Our task was precisely to derive fully rigorously this theory in the case there is no gauge invariance. We propose in our work a complete review of the result, solving numerous questions, adding many new results around this program and, eventually, giving more precise details on the counterterms and ambiguities in the renormalization process, and a deeper understanding of the geometry of the wave front set of the n-point functions.

Nguyen Viet Dang

2013-12-19T23:59:59.000Z

109

A Least Squares Method for Spectral Analysis of Space-Time Series  

Science Conference Proceedings (OSTI)

Common methods in spectral analyses of satellite data are the discrete Fourier transform (DFT) type of approaches, which generally require regular sampling and uniform spacing. These conditions sometimes cannot be met in the satellite ...

Dong L. Wu; Paul B. Hays; Wilbert R. Skinner

1995-10-01T23:59:59.000Z

110

Adaptive Discrete Cosine Transform  

Science Conference Proceedings (OSTI)

The theory and performance of the adaptive discrete cosine transform filter is examined. The discrete cosine transform filter is a realization of an FIR filter as the cascade of an all-zero FIR filter with a bank of IIR digital resonators. Each bank ... Keywords: FIR filter, IIR digital resonators, LMS algorithm, adaptive discrete cosine transform filter, adaptive filters, all-zero FIR filter, filter coefficient, frequency, magnitude, phase, transfer function, update method

S. J. Bukowinski; L. Gerhardt; M. Fargues; G. Coutu

1995-10-01T23:59:59.000Z

111

Broken symmetry as a stabilizing remnant  

Science Conference Proceedings (OSTI)

The Goldberger-Wise mechanism enables one to stabilize the length of the warped extra dimension employed in Randall-Sundrum models. In this work we generalize this mechanism to models with multiple warped throats sharing a common ultraviolet brane. For independent throats this generalization is straightforward. If the throats possess a discrete interchange symmetry like Z{sub n}, the stabilizing dynamics may respect the symmetry, resulting in equal throat lengths, or they may break it. In the latter case the ground state of an initially symmetric configuration is a stabilized asymmetric configuration in which the throat lengths differ. We focus on two- (three-) throat setups with a Z{sub 2} (Z{sub 3}) interchange symmetry and present stabilization dynamics suitable for either breaking or maintaining the symmetry. Though admitting more general application, our results are relevant for existing models in the literature, including the two-throat model with Kaluza-Klein parity, and the three-throat model of flavor with a broken Z{sub 3} symmetry.

Law, Sandy S. C. [Department of Physics, Chung Yuan Christian University, Chung-Li, Taiwan 320 (China); McDonald, Kristian L. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada); Max-Planck-Institut fuer Kernphysik, Postfach 10 39 80, 69029 Heidelberg (Germany)

2010-11-15T23:59:59.000Z

112

Reconstructing an Open Order from Its Closure, with Applications to Space-Time Physics and to Logic  

Science Conference Proceedings (OSTI)

In his logical papers, Leo Esakia studied corresponding ordered topological spaces and order-preserving mappings. Similar spaces and mappings appear in many other application areas such the analysis of causality in space-time. It is known that under ... Keywords: logic, open and closed orders, order-preserving mappings, ordered topological space, space-time geometry

Francisco Zapata; Vladik Kreinovich

2012-04-01T23:59:59.000Z

113

When Discrete Meets Differential  

Science Conference Proceedings (OSTI)

We provide a theoretical proof showing that under a proportional noise model, the discrete eight point algorithm behaves similarly to the differential eight point algorithm when the motion is small. This implies that the discrete algorithm can handle ... Keywords: Perturbation analysis, Structure from motion

Wen-Yan Lin; Geok-Choo Tan; Loong-Fah Cheong

2010-01-01T23:59:59.000Z

114

Motion of test particles in a regular black hole space--time  

E-Print Network (OSTI)

We consider the motion of test particles in the regular black hole space-time given by Ay\\'{o}n-Beato and Garc\\'{\\i}a in Phys. Rev. Lett. 80:5056 (1998). The complete set of orbits for neutral and weakly charged test particles is discussed, including for neutral particles the extreme and over-extreme metric. We also derive the analytical solutions for the equation of motion of neutral test particles in a parametric form and consider a post-Schwarzschild expansion of the periastron shift to second order in the charge.

Alberto Garcia; Eva Hackmann; Jutta Kunz; Claus Lämmerzahl; Alfredo Macias

2013-06-11T23:59:59.000Z

115

Global aspects of accelerating and rotating black hole space-times  

E-Print Network (OSTI)

The complete family of exact solutions representing accelerating and rotating black holes with possible electromagnetic charges and a NUT parameter is known in terms of a modified Plebanski-Demianski metric. This demonstrates the singularity and horizon structure of the sources but not that the complete space-time describes two causally separated black holes. To demonstrate this property, the metric is first cast in the Weyl-Lewis-Papapetrou form. After extending this up to the acceleration horizon, it is then transformed to the boost-rotation-symmetric form in which the global properties of the solution are manifest. The physical interpretation of these solutions is thus clarified.

J. B. Griffiths; J. Podolsky

2005-11-22T23:59:59.000Z

116

Energy and Momentum Distributions of Kantowski and Sachs Space-time  

E-Print Network (OSTI)

We use the Einstein, Bergmann-Thomson, Landau-Lifshitz and Papapetrou energy-momentum complexes to calculate the energy and momentum distributions of Kantowski and Sachs space-time. We show that the Einstein and Bergmann-Thomson definitions furnish a consistent result for the energy distribution, but the definition of Landau-Lifshitz do not agree with them. We show that a signature switch should affect about everything including energy distribution in the case of Einstein and Papapetrou prescriptions but not in Bergmann-Thomson and Landau-Lifshitz prescriptions.

Ragab M. Gad; A. Fouad

2007-04-12T23:59:59.000Z

117

Two-Dimensional Space-Time Dependent Multi-group Diffusion Equation with SLOR Method  

Science Conference Proceedings (OSTI)

The research of two-dimensional space-time diffusion equations with SLOR (Successive-Line Over Relaxation) has been done. SLOR method is chosen because this method is one of iterative methods that does not required to defined whole element matrix. The research is divided in two cases, homogeneous case and heterogeneous case. Homogeneous case has been inserted by step reactivity. Heterogeneous case has been inserted by step reactivity and ramp reactivity. In general, the results of simulations are agreement, even in some points there are differences.

Yulianti, Y. [Physics Department, University of Lampung (UNILA), Jl. Sumantri Brojonegoro No. 1 Bandar Lampung (Indonesia); Su'ud, Z.; Waris, A.; Khotimah, S. N. [Physics Department, Bandung Institute of Technology (ITB), Jl. Ganesha 10 Bandung (Indonesia)

2010-06-22T23:59:59.000Z

118

Energy of gravitational radiation in plane-symmetric space-times  

E-Print Network (OSTI)

Gravitational radiation in plane-symmetric space-times can be encoded in a complex potential, satisfying a non-linear wave equation. An effective energy tensor for the radiation is given, taking a scalar-field form in terms of the potential, entering the field equations in the same way as the matter energy tensor. It reduces to the Isaacson energy tensor in the linearized, high-frequency approximation. An energy conservation equation is derived for a quasi-local energy, essentially the Hawking energy. A transverse pressure exerted by interacting low-frequency gravitational radiation is predicted.

Sean A. Hayward

2008-05-19T23:59:59.000Z

119

Clock rates, clock settings and the physics of the space-time Lorentz transformation  

E-Print Network (OSTI)

A careful study is made of the operational meaning of the time symbols appearing in the space-time Lorentz transformation. Four distinct symbols, with different physical meanings, are needed to describe reciprocal measurements involving stationary and uniformly-moving clocks. Physical predictions concern only the observed rate of a clock as a function of its relative speed, not its setting. How the failure to make this distinction leads to the conventional predictions of spurious `relativity of simultaneity' and `length contraction' effects in special relativity is explained.

J. H. Field

2006-06-12T23:59:59.000Z

120

Opportunistic Relaying for Space-Time Coded Cooperation with Multiple Antenna Terminals  

E-Print Network (OSTI)

We consider a wireless relay network with multiple antenna terminals over Rayleigh fading channels, and apply distributed space-time coding (DSTC) in amplify-and-forward (A&F) mode. The A&F scheme is used in a way that each relay transmits a scaled version of the linear combination of the received symbols. It turns out that, combined with power allocation in the relays, A&F DSTC results in an opportunistic relaying scheme, in which only the best relay is selected to retransmit the source's space-time coded signal. Furthermore, assuming the knowledge of source-relay CSI at the source node, we design an efficient power allocation which outperforms uniform power allocation across the source antennas. Next, assuming M-PSK or M-QAM modulations, we analyze the performance of the proposed cooperative diversity transmission schemes in a wireless relay networks with the multiple-antenna source and destination. We derive the probability density function (PDF) of the received SNR at the destination. Then, th...

Maham, Behrouz

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

The effect of a fifth large-scale space-time dimension on orbital dynamics  

E-Print Network (OSTI)

A model based on simple assumptions about 4-dimensional space-time being closed and isotropic, and embedded in a 5th large-scale dimension, r, representing the radius of curvature of space-time, has been used in an application of Newton's Second Law to describe a system with angular momentum. It has been found that the equations of MOND used to explain the rotation curves of galaxies appear as a limit within this derivation and that there is a universal acceleration constant, ao, with a value, again consistent with that used by MOND. This approach does not require modification of Newtonian dynamics, only its extension into a fifth large-scale dimension. The transition from the classical Newtonian dynamics to the MOND regime emerges naturally and without the introduction of arbitrary fitting functions, if this 5-dimensional model is adopted. The paper also includes the derivation of an effect in 5-dimensional orbital dynamics which is in reasonable agreement with the observed Pioneer Anomaly.

M. B. Gerrard; T. J. Sumner

2006-05-12T23:59:59.000Z

122

Topological classification of crystalline insulators with space group symmetry  

Science Conference Proceedings (OSTI)

We show that in crystalline insulators, space group symmetry alone gives rise to a topological classification based on the discretization of electric polarization. Using C3 rotational symmetry as an example, we first prove that the polarization is discretized into three distinct classes, i.e., it can only take three inequivalent values. We then prove that these classes are topologically distinct. Therefore, a Z3 topological classification exists, with polarization as a topological class index. A concrete tight-binding model is derived to demonstrate the Z3 topological phase transition. Using first-principles calculations, we identify graphene on a BN substrate as a possible candidate to realize these Z3 topological states. To complete our analysis, we extend the classification of band structures to all 17 two-dimensional space groups. This work will contribute to a complete theory of symmetry-conserved topological phases and also elucidate topological properties of graphenelike systems.

Jadaun, Priyamvada [University of Texas at Austin; Xiao, Di [Carnegie Mellon University (CMU); Niu, Q. [University of Texas at Austin; Banerjee, Sanjay K. [University of Texas at Austin

2013-01-01T23:59:59.000Z

123

Fundamental Symmetries and Interactions - Some Aspects  

E-Print Network (OSTI)

In the framework of nuclear physics and at nuclear physics facilities a large number of different experiments can be performed which render the possibility to investigate fundamental symmetries and interactions in nature. In particular, the precise measurements of properties of fundamental fermions, searches for new interactions in $\\beta$-decays, and violations of discrete symmetries have a robust discovery potential for physics beyond standard theory. Precise measurements of fundamental constants can be carried out as well. Low energy experiments allow probing of New Physics models at mass scales far beyond the reach of present accelerators or such planned for the future in the domain of high energy physics and at which predicted new particles could be produced directly.

Klaus Jungmann

2005-01-30T23:59:59.000Z

124

A Uniform Space–Time Gridding Algorithm for Comparison of Satellite Data Products: Characterization and Sensitivity Study  

Science Conference Proceedings (OSTI)

To overcome the complexities associated with combining or comparing multisensor data, a statistical gridding algorithm is introduced for projecting data from their unique instrument domain to a uniform space–time domain. The algorithm has two ...

Nadia Smith; W. Paul Menzel; Elisabeth Weisz; Andrew K. Heidinger; Bryan A. Baum

2013-01-01T23:59:59.000Z

125

NIST: Methane Symmetry Operations - Introduction  

Science Conference Proceedings (OSTI)

Methane Symmetry Operations. ... At least three T d symmetry classification systems are widely used at present in the methane literature [5-13]. ...

126

Cooperative Transmission Using Quasi-Orthogonal Space-Time Block Codes with Adaptive Decode-and-Forward Relaying Protocol  

Science Conference Proceedings (OSTI)

In this paper, we propose a cooperative transmission scheme using quasi-orthogonal space-time block codes (QOSTBCs) for multiple-input multiple-output (MIMO) relay networks. Comparing with the conventional cooperative transmission scheme using orthogonal ... Keywords: Channel state information (CSI) feedback, Decode-and-forward (DF), Multiple-input multiple-output (MIMO) relay, Outage probability, Space-time block codes (STBCs)

Yang Gao; Jianhua Ge; Yancheng Ji

2012-04-01T23:59:59.000Z

127

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

128

Affordance and Symmetry  

Science Conference Proceedings (OSTI)

Whilst it is generally accepted as a positive criterion, affordance only gives the weakest of hints for interactive systems designers. This paper shows how useful it is to consider affordance as generated by a correspondence between program symmetries ...

Harold W. Thimbleby

2001-06-01T23:59:59.000Z

129

Quantum process and the foundation of relational theories of space-time  

E-Print Network (OSTI)

We present current theories about the structure of space and time, where the building blocks are some fundamental entities (yes-no experiment, quantum processes, spin net-work, preparticles) that do not presuppose the existence of space and time. The relations among these objects are the base for a pregeometry of discrete character, the continuous limit of which gives rise to the physical properties of the space and time.

M. Lorente

2003-12-30T23:59:59.000Z

130

A discrete fractional random transform  

E-Print Network (OSTI)

We propose a discrete fractional random transform based on a generalization of the discrete fractional Fourier transform with an intrinsic randomness. Such discrete fractional random transform inheres excellent mathematical properties of the fractional Fourier transform along with some fantastic features of its own. As a primary application, the discrete fractional random transform has been used for image encryption and decryption.

Zhengjun Liu; Haifa Zhao; Shutian Liu

2006-05-20T23:59:59.000Z

131

IBM: parameter symmetry, hidden symmetries and transformations of boson operators  

E-Print Network (OSTI)

A symmetry of the parameter space of interacting boson models IBM-1 and IBM-2 is studied. The symmetry is associated with linear canonical transformations of boson operators, or, equivalently, with the existence of different realizations of the symmetry algebras of the models. The relevance of the parameter symmetry to physical observables is discussed.

A. M. Shirokov; N. A. Smirnova; Yu. F. Smirnov; O. Castaños; A. Frank

1999-04-07T23:59:59.000Z

132

IBM parameter symmetry, hidden symmetries and transformations of boson operators  

E-Print Network (OSTI)

A symmetry of the parameter space of interacting boson models IBM-1 and IBM-2 is studied. The symmetry is associated with linear canonical transformations of boson operators, or, equivalently, with the existence of different realizations of the symmetry algebras of the models. The relevance of the parameter symmetry to physical observables is discussed.

Shirokov, A M; Smirnov, Yu F; Castaños, O; Frank, A I; Smirnov, Yu. F.

1999-01-01T23:59:59.000Z

133

Gravitational Collapse In Husain Space-time For Brans-Dicke Gravity Theory  

E-Print Network (OSTI)

The motive of this work is to study gravitational collapse in Husain space-time, in Brans-Dicke gravity theory. Among many scalar-tensor theories of gravity, Brans-Dicke is the simplest and the impact of it can be regulated by two parameters, coupling constant $\\omega$, and the assumed field dependency parameter $n$. V. Husain's work on exact solution for null fluid collapse in 1996 has influenced many authors to follow his way to find the end-state of the homogeneous/inhomogeneous dust cloud collapse using Vaidya's metric. Detecting whether the cosmological singularity is naked or wrapped by an event horizon, by the existence of future directed radial null geodesic emitted in past from the singularity is the basic objective. To point out the existence of positive trajectory tangent solution, both particular parametric cases (through tabular forms) and wide range contouring process have been applied. Precisely, perfect fluid's EoS ($p=k\\rho$) satisfies a wide range of phenomena: from dust to exotic fluid like dark energy. We have used this EoS parameter $k$ to determine the end state of collapse in different cosmological era. Our main target is to check low $\\omega$ (more Brans-Dicke effect) and negative $k$ zones. This particularly characterizes the nature of collapse end-state in accelerated expansion in Brans-Dicke gravity. It is noted that "low $\\omega$ $-$ low EoS parameter" increases the probability of getting naked singularities.

Prabir Rudra; Ritabrata Biswas; Ujjal Debnath

2013-07-23T23:59:59.000Z

134

Sparsity-Based Space-Time Adaptive Processing Using OFDM Radar  

Science Conference Proceedings (OSTI)

We propose a sparsity-based space-time adaptive processing (STAP) algorithm to detect a slowly-moving target using an orthogonal frequency division multiplexing (OFDM) radar. We observe that the target and interference spectra are inherently sparse in the spatio-temporal domain, and hence we exploit that sparsity to develop an efficient STAP technique. In addition, the use of an OFDM signal increases the frequency diversity of our system, as different scattering centers of a target resonate at different frequencies, and thus improves the target detectability. First, we formulate a realistic sparse-measurement model for an OFDM radar considering both the clutter and jammer as the interfering sources. Then, we show that the optimal STAP-filter weight-vector is equal to the generalized eigenvector corresponding to the minimum generalized eigenvalue of the interference and target covariance matrices. To estimate the target and interference covariance matrices, we apply a residual sparse-recovery technique that enables us to incorporate the partially known support of the sparse vector. Our numerical results demonstrate that the sparsity-based STAP algorithm, with considerably lesser number of secondary data, produces an equivalent performance as the other existing STAP techniques.

Sen, Satyabrata [ORNL

2012-01-01T23:59:59.000Z

135

OFDM Radar Space-Time Adaptive Processing by Exploiting Spatio-Temporal Sparsity  

Science Conference Proceedings (OSTI)

We propose a sparsity-based space-time adaptive processing (STAP) algorithm to detect a slowly-moving target using an orthogonal frequency division multiplexing (OFDM) radar. We observe that the target and interference spectra are inherently sparse in the spatio-temporal domain. Hence, we exploit that sparsity to develop an efficient STAP technique that utilizes considerably lesser number of secondary data and produces an equivalent performance as the other existing STAP techniques. In addition, the use of an OFDM signal increases the frequency diversity of our system, as different scattering centers of a target resonate at different frequencies, and thus improves the target detectability. First, we formulate a realistic sparse-measurement model for an OFDM radar considering both the clutter and jammer as the interfering sources. Then, we apply a residual sparse-recovery technique based on the LASSO estimator to estimate the target and interference covariance matrices, and subsequently compute the optimal STAP-filter weights. Our numerical results demonstrate a comparative performance analysis of the proposed sparse-STAP algorithm with four other existing STAP methods. Furthermore, we discover that the OFDM-STAP filter-weights are adaptable to the frequency-variabilities of the target and interference responses, in addition to the spatio-temporal variabilities. Hence, by better utilizing the frequency variabilities, we propose an adaptive OFDM-waveform design technique, and consequently gain a significant amount of STAP-performance improvement.

Sen, Satyabrata [ORNL

2013-01-01T23:59:59.000Z

136

Vector theory of gravity in Minkowski space-time: flat Universe without black holes  

E-Print Network (OSTI)

We propose a new classical theory of gravity which is based on the principle of equivalence and assumption that gravity, similarly to electrodynamics, is described by a vector field in Minkowski space-time. We show that such assumptions yield a unique theory of gravity; it passes all available tests and free of singularities such as black holes. In the present theory, gravity is described by four equations which have, e.g., exact analytical solution for arbitrary static field. For cosmology our equations give essentially the same evolution of the Universe as general relativity. Predictions of our theory can be tested within next few years making more accurate measurement of the time delay of radar signal traveling near the Sun or by resolving the supermassive object at the center of our Galaxy with VLBA. If general relativity is correct we must see a steady shadow from a black hole at the Galactic center. If the present theory is right then likely the shadow will appear and disappear periodically with a perio...

Svidzinsky, Anatoly A

2009-01-01T23:59:59.000Z

137

Relativity in binary systems as root of quantum mechanics and space-time  

E-Print Network (OSTI)

Inspired by Bohr's dictum that "physical phenomena are observed relative to different experimental setups", this article investigates the notion of relativity in Bohr's sense, starting from a set of binary elements. The most general form of information coding within such sets requires a description by four-component states. By using Bohr's dictum as a guideline a quantum mechanical description of the set is obtained in the form of a SO(3,2) based spin network. For large (macroscopic) sub-networks a flat-space approximation of SO(3,2) leads to a Poincare symmetrical Hilbert space. The concept of a position of four-component spinors relative to macroscopic sub-networks then delivers the description of 'free' massive spin-1/2 particles with a Poincare symmetrical Hilbert space. Hence Minkowskian space-time, equipped with spin-1/2 particles, is obtained as an inherent property of a system of binary elements when individual elements are described relative to macroscopic sub-systems.

W. Smilga

2004-08-14T23:59:59.000Z

138

Binary Tetrahedral Flavor Symmetry  

E-Print Network (OSTI)

A study of the T' Model and its variants utilizing Binary Tetrahedral Flavor Symmetry. We begin with a description of the historical context and motivations for this theory, together with some conceptual background for added clarity, and an account of our theory's inception in previous works. Our model endeavors to bridge two categories of particles, leptons and quarks, a unification made possible by the inclusion of additional Higgs particles, shared between the two fermion sectors and creating a single coherent system. This is achieved through the use of the Binary Tetrahedral symmetry group and an investigation of the Tribimaximal symmetry evidenced by neutrinos. Our work details perturbations and extensions of this T' Model as we apply our framework to neutrino mixing, quark mixing, unification, and dark matter. Where possible, we evaluate model predictions against experimental results and find excellent matching with the atmospheric and reactor neutrino mixing angles, an accurate prediction of the Cabibb...

Eby, David A

2013-01-01T23:59:59.000Z

139

Symmetries in Synaptic Algebras  

E-Print Network (OSTI)

A synaptic algebra is a generalization of the Jordan algebra of selfadjoint elements of a von Neumann algebra. We study symmetries in synaptic algebras, i.e., elements whose square is the unit element, and we investigate the equivalence relation on the projection lattice of the algebra induced by finite sequences of symmetries. In case the projection lattice is complete, or even centrally orthocomplete, this equivalence relation is shown to possess many of the properties of a dimension equivalence relation on an orthomodular lattice.

David J. Foulis; Sylvia Pulmannova

2013-04-16T23:59:59.000Z

140

Changes in the fine structure of stochastic distributions as a consequence of space-time fluctuations  

E-Print Network (OSTI)

Earlier we showed that the fine structure of the spectrum of amplitude variations in the results of measurements of the processes of different nature (in other words, the fine structure of the dispersion of results or the pattern of the corresponding histograms) is subject to macroscopic fluctuations, changing regularly with time. These changes indicate that the dispersion of results that remains after all artifacts are excluded inevitably accompanies any measurements and reflects very basic features of our world. In our research, we have come to the conclusion that this dispersion of results is the effect of space-time fluctuations, which, in their turn, are caused by the movement of the measured object in an anisotropic gravitational field. Among other things, this conclusion means that the examination of the detailed pattern of distributions obtained from the results of measurement of the dynamics of processes of different nature discovers laws, which cannot be revealed with traditional methods for the analysis of time series. These assertions are based on the results of long-term experimental investigations conducted for many decades. The major part of these results, starting with 1958, is published in Russian. The goal of this paper is to give a brief review of those results and provide corresponding references. The most general conclusion of our research is the evidence that the fine structure of stochastic distributions is not accidental. In other words, noncasual is the pattern of histograms plotted from a rather small number of the results of measurement of the dynamics of processes of different nature, from the biochemical reactions and noise in the gravitational antenna to the alpha-decay.

Simon E. Shnoll

2006-02-02T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Binary Tetrahedral Flavor Symmetry  

E-Print Network (OSTI)

A study of the T' Model and its variants utilizing Binary Tetrahedral Flavor Symmetry. We begin with a description of the historical context and motivations for this theory, together with some conceptual background for added clarity, and an account of our theory's inception in previous works. Our model endeavors to bridge two categories of particles, leptons and quarks, a unification made possible by the inclusion of additional Higgs particles, shared between the two fermion sectors and creating a single coherent system. This is achieved through the use of the Binary Tetrahedral symmetry group and an investigation of the Tribimaximal symmetry evidenced by neutrinos. Our work details perturbations and extensions of this T' Model as we apply our framework to neutrino mixing, quark mixing, unification, and dark matter. Where possible, we evaluate model predictions against experimental results and find excellent matching with the atmospheric and reactor neutrino mixing angles, an accurate prediction of the Cabibbo angle, and a dark matter candidate that remains outside the limits of current tests. Additionally, we include mention of a number of unanswered questions and remaining areas of interest for future study. Taken together, we believe these results speak to the promising potential of finite groups and flavor symmetries to act as an approximation of nature.

David A. Eby

2013-04-15T23:59:59.000Z

142

Higher-order discrete variational problems with constraints  

E-Print Network (OSTI)

An interesting family of geometric integrators for Lagrangian systems can be defined using discretizations of the Hamilton's principle of critical action. This family of geometric integrators is called variational integrators. In this paper, we derive new variational integrators for higher-order lagrangian mechanical system subjected to higher-order constraints. From the discretization of the variational principles, we show that our methods are automatically symplectic and, in consequence, with a very good energy behavior. Additionally, the symmetries of the discrete Lagrangian imply that momenta is conserved by the integrator. Moreover, we extend our construction to variational integrators where the lagrangian is explicitly time-dependent. Finally, some motivating applications of higher-order problems are considered; in particular, optimal control problems for explicitly time-dependent underactuated systems and an interpolation problem on Riemannian manifolds.

Leonardo Colombo; David Martín de Diego; Marcela Zuccalli

2013-06-03T23:59:59.000Z

143

Real-time road traffic forecasting using regime-switching space-time models and adaptive LASSO  

Science Conference Proceedings (OSTI)

Smart transportation technologies require real-time traffic prediction to be both fast and scalable to full urban networks. We discuss a method that is able to meet this challenge while accounting for nonlinear traffic dynamics and space-time dependencies ... Keywords: adaptive LASSO, real-time predictions, threshold regressions, traffic forecasting

Yiannis Kamarianakis; Wei Shen; Laura Wynter

2012-07-01T23:59:59.000Z

144

Hybridized enriched space-time finite element method for analysis of thin-walled structures immersed in generalized Newtonian fluids  

Science Conference Proceedings (OSTI)

The paper addresses the numerical treatment of a specific class of fluid-structure interaction problems: flow-immersed thin structures undergoing considerable motion and deformation. The simultaneous solution procedure uses a mixed-hybrid velocity-based ... Keywords: Embedded thin structure, Enriched space-time approximation, Fluid-structure interaction, Strong coupling

A. Zilian; H. Netuzhylov

2010-11-01T23:59:59.000Z

145

Cosmological perturbations of brane-induced gravity and the vDVZ discontinuity on FLRW space-times  

E-Print Network (OSTI)

We investigate the cosmological perturbations of the brane-induced (Dvali-Gabadadze-Porrati) model which exhibits a van Dam-Veltman-Zakharov (vDVZ) discontinuity when linearized over a Minkowski background. We show that the linear brane scalar cosmological perturbations over an arbitrary Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time have a well defined limit when the radius of transition between 4D and 5D gravity is sent to infinity with respect to the background Hubble radius. This radius of transition plays for the brane-induced gravity model a role equivalent to the Compton wavelength of the graviton in a Pauli-Fierz theory, as far as the vDVZ discontinuity is concerned. This well defined limit is shown to obey the linearized 4D Einstein's equations whenever the Hubble factor is non vanishing. This shows the disappearance of the vDVZ discontinuity for general FLRW background, and extends the previously know result for maximally-symmetric space-times of non vanishing curvature. Our reasoning is valid for matter with simple equation of state such as a scalar field, or a perfect fluid with adiabatic perturbations, and involves to distinguish between space-times with a vanishing scalar curvature and space-times with a non vanishing one. We also discuss the validity of the linear perturbation theory, in particular for those FLRW space-times where the Ricci scalar is vanishing only on a set of zero measure. In those cases, we argue that the linear perturbation theory breaks down when the Ricci scalar vanishes (and the radius of transition is sent to infinity), in a way similar to what has been found to occur around sources on a Minkowski background.

Cedric Deffayet

2004-12-22T23:59:59.000Z

146

Symmetry Energy in Nuclear Surface  

E-Print Network (OSTI)

Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. That interplay gives rise to the mass dependence of the symmetry coefficient in an energy formula. Charge symmetry of the nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of the magnitude of neutron-proton asymmetry.

Pawel Danielewicz; Jenny Lee

2008-11-10T23:59:59.000Z

147

Symmetry Energy in Nuclear Surface  

E-Print Network (OSTI)

Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. The interplay leads to a dependence of the symmetry coefficient, in energy formula, on nuclear mass. Charge symmetry of nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of neutron-proton asymmetry.

Danielewicz, Pawel

2008-01-01T23:59:59.000Z

148

Lepton Mixing Predictions from Delta(6n^2) Family Symmetry  

E-Print Network (OSTI)

We obtain predictions of lepton mixing parameters for direct models based on Delta(6n^2) family symmetry groups for arbitrarily large n in which the full Klein symmetry is identified as a subgroup of the family symmetry. After reviewing and developing the group theory associated with Delta(6n^2), we find many new candidates for large n able to yield reactor angle predictions within 3 sigma of recent global fits. We show that such Delta(6n^2) models with Majorana neutrinos predict trimaximal mixing with reactor angle theta_{13} fixed up to a discrete choice, an oscillation phase of either zero or pi and the atmospheric angle sum rules theta_{23}=45 degrees -/+ theta_{13}/sqrt{2}, respectively, which are consistent with recent global fits and will be tested in the near future.

King, Stephen F; Stuart, Alexander J

2013-01-01T23:59:59.000Z

149

Lepton Mixing Predictions from Delta(6n^2) Family Symmetry  

E-Print Network (OSTI)

We obtain predictions of lepton mixing parameters for direct models based on Delta(6n^2) family symmetry groups for arbitrarily large n in which the full Klein symmetry is identified as a subgroup of the family symmetry. After reviewing and developing the group theory associated with Delta(6n^2), we find many new candidates for large n able to yield reactor angle predictions within 3 sigma of recent global fits. We show that such Delta(6n^2) models with Majorana neutrinos predict trimaximal mixing with reactor angle theta_{13} fixed up to a discrete choice, an oscillation phase of either zero or pi and the atmospheric angle sum rules theta_{23}=45 degrees -/+ theta_{13}/sqrt{2}, respectively, which are consistent with recent global fits and will be tested in the near future.

Stephen F. King; Thomas Neder; Alexander J. Stuart

2013-05-14T23:59:59.000Z

150

Scalar torsion and a new symmetry of general relativity  

E-Print Network (OSTI)

We reformulate the general theory of relativity in the language of Riemann-Cartan geometry. We start from the assumption that the space-time can be described as a non-Riemannian manifold, which, in addition to the metric field, is endowed with torsion. In this new framework, the gravitational field is represented not only by the metric, but also by the torsion, which is completely determined by a geometric scalar field. We show that in this formulation general relativity has a new kind of invariance, whose invariance group consists of a set of conformal and gauge transformations, called Cartan transformations. These involve both the metric tensor and the torsion vector field, and are similar to the well known Weyl gauge transformations. By making use of the concept of Cartan gauges, we show that, under Cartan transformations, the new formalism leads to different pictures of the same gravitational phenomena. We show that in an arbitrary Cartan gauge general relativity has the form of a scalar-tensor theory. In this approach, the Riemann-Cartan geometry appears as the natural geometrical setting of the general relativity theory when the latter is viewed in an arbitrary Cartan gauge. We illustrate this fact by looking at the one of the classical tests of general relativity theory, namely the gravitational spectral shift. Finally, we extend the concept of space-time symmetry to the more general case of Riemann-Cartan space-times endowed with scalar torsion. As an example, we obtain the conservation laws for auto-parallel motion in a static spherically symmetric vacuum space-time in a Cartan gauge, whose orbits are identical to Schwarzschild orbits in general relativity.

J. B. Fonseca-Neto; C. Romero; S. P. G. Martinez

2012-11-07T23:59:59.000Z

151

NIST: Methane Symmetry Operations - Nuclear spin functions  

Science Conference Proceedings (OSTI)

Methane Symmetry Operations. 9. Symmetry Properties of Laboratory-Fixed Nuclear Spin Functions, Nuclear Spin Statistics, and Parities. ...

152

Application of the Space-Time Method to Stimulated Raman Adiabatic Passage on the Simple Harmonic Oscillator  

E-Print Network (OSTI)

The space-time method is applied to a model system-the Simple Harmonic Oscillator in a laser field to simulate the Stimulated Raman Adiabatic Passage (STIRAP) process. The Space-Time method is a computational theory first introduced by Weatherford et. al. to solve Time-Dependent Systems with one boundary value and applied to electron spin system with invariant Hamiltonian [Journal of Molecular Structure {\\bf 592} 47]. The implementation in the present work provides an efficient and general way to solve the Time-Dependent Schr{\\"o}dinger Equation and can be applied to multi-state systems. The algorithm for simulating the Simple Harmonic Oscillator STIRAP can be applied to solve STIRAP problems for complex systems.

Xingjun Zhang; Charles A. Weatherford

2013-06-02T23:59:59.000Z

153

Application of the Space-Time Method to Stimulated Raman Adiabatic Passage on the Simple Harmonic Oscillator  

E-Print Network (OSTI)

The space-time method is applied to a model system-the Simple Harmonic Oscillator in a laser field to simulate the Stimulated Raman Adiabatic Passage (STIRAP) process. The Space-Time method is a computational theory first introduced by Weatherford et. al. to solve Time-Dependent Systems with one boundary value and applied to electron spin system with invariant Hamiltonian [Journal of Molecular Structure {\\bf 592} 47]. The implementation in the present work provides an efficient and general way to solve the Time-Dependent Schr{\\"o}dinger Equation and can be applied to multi-state systems. The algorithm for simulating the Simple Harmonic Oscillator STIRAP can be applied to solve STIRAP problems for complex systems.

Zhang, Xingjun

2013-01-01T23:59:59.000Z

154

On the space of light rays of a space-time and a reconstruction theorem by Low  

E-Print Network (OSTI)

A reconstruction theorem in terms of the topology and geometrical structures on the spaces of light rays and skies of a given space-time is discussed. This result can be seen as part of Penrose and Low's programme intending to describe the causal structure of a space-time $M$ in terms of the topological and geometrical properties of the space of light rays, i.e., unparametrized time-oriented null geodesics, $\\mathcal{N}$. In the analysis of the reconstruction problem it becomes instrumental the structure of the space of skies, i.e., of congruences of light rays. It will be shown that the space of skies $\\Sigma$ of a strongly causal skies distinguishing space-time $M$ carries a canonical differentiable structure diffeomorphic to the original manifold $M$. Celestial curves, this is, curves in $\\mathcal{N}$ which are everywhere tangent to skies, play a fundamental role in the analysis of the geometry of the space of light rays. It will be shown that a celestial curve is induced by a past causal curve of events iff the legendrian isotopy defined by it is non-negative. This result extends in a nontrivial way some recent results by Chernov \\emph{et al} on Low's Legendrian conjecture. Finally, it will be shown that a celestial causal map between the space of light rays of two strongly causal spaces (provided that the target space is null non-conjugate) is necessarily induced from a conformal immersion and conversely. These results make explicit the fundamental role played by the collection of skies, a collection of legendrian spheres with respect to the canonical contact structure on $\\mathcal{N}$, in characterizing the causal structure of space-times.

A. Bautista; A. Ibort; J. Lafuente

2013-09-30T23:59:59.000Z

155

Dynamical symmetry breaking in geometrodynamics  

E-Print Network (OSTI)

We are going to analyze through a first order perturbative formulation the local loss of symmetry when a source of electromagnetic and gravitational field interacts with an agent that perturbes the original geometry associated to the source. As the symmetry in Abelian or even non-Abelian field structures in four dimensional Lorentzian spacetimes is displayed through the existence of local planes of symmetry that we previously called blades one and two, the loss of symmetry will be manifested by the tilting of these planes under the influence of the external agent. In this strict sense the original local symmetry will be lost. But we will prove that the new blades at the same point will correspond after the tilting generated by perturbation to a new symmetry. The point of this note is to prove that the geometrical manifestation of local gauge symmetries is dynamic. The local original symmetries will be lost, nonetheless new symmetries will arise. There is a dynamic evolution of local symmetries.

Alcides Garat

2013-06-03T23:59:59.000Z

156

A General Systems Theory for Chaos, Quantum Mechanics and Gravity for Dynamical Systems of all Space-Time Scales  

E-Print Network (OSTI)

Non-local connections, i. e. long-range space-time correlations intrinsic to the observed subatomic dynamics of quantum systems is also exhibited by macro-scale dynamical systems as selfsimilar fractal space-time fluctuations and is identified as self-organized criticality. The author has developed a general systems theory for the observed self-organized criticality applicable to dynamical systems of all space-time scales based on the concept that spatial integration of enclosed small-scale fluctuations results in the formation of large eddy circulation. The eddy energy spectrum therefore represents the statistical normal distribution according to the Central Limit Theorem. The additive amplitudes of eddies, when squared (variance or eddy kinetic energy), represent the statistical normal (probability) distribution, a result observed in the subatomic dynamics of quantum systems. The model predicts Kepler's laws of planetary motion for eddy circulation dynamics. Inverse square law of gravitation therefore applies to the eddy continuum ranging from subatomic to macro-scale dynamical systems, e.g. weather systems. The model is similar to a superstring model for subatomic dynamics which unifies quantum mechanical and classical concepts and manifestation of matter is visualised as vibrational modes in string-like energy flow patterns. The cumulative sum of centripetal forces in a hierarchy of vortex circulations may result in the observed inverse square law form for gravitational attraction between inertial masses of the eddies.

A M Selvam

2005-03-03T23:59:59.000Z

157

Dark Matter Stabilization Symmetries from Spontaneous Symmetry Breaking  

E-Print Network (OSTI)

We present a class of models in which the dark matter stabilization symmetry is generated by spontaneous symmetry breaking. These models naturally correlate the dark and electroweak symmetry breaking scales. The result is a generic mechanism linking the annihilation cross section for thermally populated dark matter with the weak scale. The thermal relic abundance, sensitivity to major precision electroweak observables and additional LHC signatures are also presented.

Walker, Devin G E

2009-01-01T23:59:59.000Z

158

Dark Matter Stabilization Symmetries from Spontaneous Symmetry Breaking  

E-Print Network (OSTI)

We present a class of models in which the dark matter stabilization symmetry is generated by spontaneous symmetry breaking. These models naturally correlate the dark and electroweak symmetry breaking scales. The result is a generic mechanism linking the annihilation cross section for thermally populated dark matter with the weak scale. The thermal relic abundance, sensitivity to major precision electroweak observables and additional LHC signatures are also presented.

Devin G. E. Walker

2009-07-20T23:59:59.000Z

159

Thermodynamics of discrete quantum processes  

E-Print Network (OSTI)

We define thermodynamic configurations and identify two primitives of discrete quantum processes between configurations for which heat and work can be defined in a natural way. This allows us to uncover a general second law for any discrete trajectory that consists of a sequence of these primitives, linking both equilibrium and non-equilibrium configurations. Moreover, in the limit of a discrete trajectory that passes through an infinite number of configurations, i.e. in the reversible limit, we recover the saturation of the second law. Finally, we show that for a discrete Carnot cycle operating between four configurations one recovers Carnot's thermal efficiency.

Janet Anders; Vittorio Giovannetti

2012-11-01T23:59:59.000Z

160

Observable T{sub 7] lepton flavor symmetry at the large hadron collider.  

SciTech Connect

More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T{sub 7} and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider.

Cao, Q.-H.; Khalil, S.; Ma, E.; Okada, H. (High Energy Physics); (Univ. of Chicago); (British Univ. in Egypt); (Ain Shams Univ.); (Univ. of California at Riverside)

2011-03-29T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Additional Symmetries of Generalized Hierarchies  

E-Print Network (OSTI)

The non-isospectral symmetries of a general class of integrable hierarchies are found, generalizing the Galilean and scaling symmetries of the Korteweg--de Vries equation and its hierarchy. The symmetries arise in a very natural way from the semi-direct product structure of the Virasoro algebra and the affine Kac--Moody algebra underlying the construction of the hierarchy. In particular, the generators of the symmetries are shown to satisfy a subalgebra of the Virasoro algebra. When a tau-function formalism is available, the infinitesimal symmetries act directly on the tau-functions as moments of Virasoro currents. Some comments are made regarding the r\\^ole of the non-isospectral symmetries and the form of the string equations in matrix-model formulations of quantum gravity in two-dimensions and related systems.

T. J. Hollowood; J. L. Miramontes; J. Sanchez Guillen

1993-11-11T23:59:59.000Z

162

Reformulations in Mathematical Programming: Symmetry  

E-Print Network (OSTI)

Dec 3, 2008 ... symmetries may change during the BB tree exploration, locally to ...... Optimal running and planning of a biomass-based energy production.

163

Trace Anomaly in Geometric Discretization  

E-Print Network (OSTI)

I develop the simplest geometric-discretized analogue of two dimensional scalar field theory, which qualitatively reproduces the trace anomaly of the continuous theory. The discrete analogue provides an interpretation of the trace anomaly in terms of a non-trivial transformation of electric-magnetic duality-invariant modes of resistor networks that accommodate both electric and magnetic charge currents.

Czech, B

2007-01-01T23:59:59.000Z

164

Symmetries and vanishing couplings in string-derived low energy effective field theory  

Science Conference Proceedings (OSTI)

We study 4D low-energy effective field theory, derived from heterotic string theory on the orbifolds. In particular, we study Abelian and non-Abelian discrete symmetries and their anomalies. Furthermore, stringy computations also provide with stringy coupling selection rules.

Kobayashi, Tatsuo [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2012-07-27T23:59:59.000Z

165

Testing the space-time geometry around black hole candidates with the available radio and X-ray data  

E-Print Network (OSTI)

Astrophysical black hole candidates are thought to be the Kerr black holes predicted by General Relativity, but the actual nature of these objects has still to be proven. The Kerr black hole hypothesis can be tested by observing strong gravity features and check if they are in agreement with the predictions of General Relativity. In particular, the study of the properties of the electromagnetic radiation emitted by the gas of the accretion disk can provide information on the geometry of the space-time around these objects and constrain possible deviations from the Kerr background.

Cosimo Bambi

2013-01-03T23:59:59.000Z

166

Primary and reciprocal space-time experiments, relativistic reciprocity relations and Einstein's train-embankment thought experiment  

E-Print Network (OSTI)

The concepts of primary and reciprocal experiments and base and travelling frames in special relativity are concisely described and applied to several different space-time experiments. These include Einstein's train/embankment thought experiment and a related thought experiment, due to Sartori, involving two trains in parallel motion with different speeds. Spatially separated clocks which are synchronised in their common proper frame are shown to be so in all inertial frames and their spatial separation to be Lorentz invariant. The interpretions given by Einstein and Sartori of their experiments, as well as those given by the present author in previous papers, are shown to be erroneous.

J. H. Field

2008-07-01T23:59:59.000Z

167

Symmetry Breaking of H2 Dissociation by a Single Photon  

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

by breaking the molecular symmetry. A Molecular Paradox Symmetries in nature, such as the human body's bilateral symmetry and the snowflake's six-fold rotational symmetry, abound...

168

Discrete generalized multigroup theory and applications  

E-Print Network (OSTI)

This study develops a fundamentally new discrete generalized multigroup energy expansion theory for the linear Boltzmann transport equation. Discrete orthogonal polynomials are used, in conjunction with the traditional ...

Zhu, Lei, Ph. D. Massachusetts Institute of Technology

2012-01-01T23:59:59.000Z

169

The Interplay Between GUT and Flavour Symmetries in a Pati-Salam x S4 Model  

E-Print Network (OSTI)

Both Grand Unified symmetries and discrete flavour symmetries are appealing ways to describe apparent structures in the gauge and flavour sectors of the Standard Model. Both symmetries put constraints on the high energy behaviour of the theory. This can give rise to unexpected interplay when building models that possess both symmetries. We investigate on the possibility to combine a Pati-Salam model with the discrete flavour symmetry $S_4$ that gives rise to quark-lepton complementarity. Under appropriate assumptions at the GUT scale, the model reproduces fermion masses and mixings both in the quark and in the lepton sectors. We show that in particular the Higgs sector and the running Yukawa couplings are strongly affected by the combined constraints of the Grand Unified and family symmetries. This in turn reduces the phenomenologically viable parameter space, with high energy mass scales confined to a small region and some parameters in the neutrino sector slightly unnatural. In the allowed regions, we can reproduce the quark masses and the CKM matrix. In the lepton sector, we reproduce the charged lepton masses, including bottom-tau unification and the Georgi-Jarlskog relation as well as the two known angles of the PMNS matrix. The neutrino mass spectrum can present a normal or an inverse hierarchy, and only allowing the neutrino parameters to spread into a range of values between $\\lambda^{-2}$ and $\\lambda^2$, with $\\lambda\\simeq0.2$. Finally, our model suggests that the reactor mixing angle is close to its current experimental bound.

Reinier de Adelhart Toorop; Federica Bazzocchi; Luca Merlo

2010-03-23T23:59:59.000Z

170

Spectral theorem and partial symmetries  

Science Conference Proceedings (OSTI)

A novel method of the decompositon of a quantum system's Hamiltonian is presented. In this approach the criterion of the decomposition is determined by the symmetries possessed by the sub-Hamiltonians. This procedure is rather generic and independent of the actual global symmetry, or the lack of it, of the full Hamilton operator. A detailed investigation of the time evolution of the various sub-Hamiltonians, therefore the change in time of the symmetry of the physical object, is presented for the case of a vibrator-plus-rotor model. Analytical results are illustrated by direct numerical calculations.

Gozdz, A. [University of Maria Curie-Sklodowska, Department of Mathematical Physics, Institute of Physics (Poland); Gozdz, M. [University of Maria Curie-Sklodowska, Department of Complex Systems and Neurodynamics, Institute of Informatics (Poland)

2012-10-15T23:59:59.000Z

171

Higgs family symmetry and supersymmetry  

E-Print Network (OSTI)

In this thesis we investigate building models of family symmetry that give the Higgs fields family structure. We construct several models, starting with 2 generation models then moving onto 3 generation models. These models ...

Patt, Brian Lawrence

2006-01-01T23:59:59.000Z

172

Nuclear Forces and Chiral Symmetry  

SciTech Connect

We review the main achievements of the research program for the study of nuclear forces in the framework of chiral symmetry and discuss some problems which are still open.

Renato Higa; Manoel Robilotta; Carlos Antonio da Rocha

2005-07-26T23:59:59.000Z

173

Dyon Solution in Einstein-Yang-Mills Theory on a Cylindrical Symmetric Space Time with Cosmological Constant  

E-Print Network (OSTI)

We investigated numerically dyon-like solutions of the SU(2) Einstein-Yang-Mills system on a cylindrically symmetric space time with a cosmological constant. We find a new kind of behaviour not found in the spherically symmetric models. For positive values of $\\Lambda$ we have an oscillatory behaviour of the magnetic component of the YM field around the r-axis, so there is an arbitrary number of nodes. For increasing positive $\\Lambda$, the frequency increases also and the solution breaks down at finite radius, indicating a singularity. The electric component, however, approaches a constant value. After further increasing $\\Lambda$, this global behaviour repeats itself at a larger r while the former singular behaviour disappears. For increasing negative $\\Lambda$, the oscillatory behaviour disappears and the magnetic and electric components behave like the scalar and gauge field in the Abelian cosmic string model.

Reinoud J. Slagter

2004-05-22T23:59:59.000Z

174

Space, time and acoustics  

E-Print Network (OSTI)

This thesis describes the development of new concepts in acoustical analysis from their inception to implementation as a computer design tool. Research is focused on a computer program which aids the designer to visually ...

Thompson, Philip R. Z. (Philip Reed Zane)

1988-01-01T23:59:59.000Z

175

Discrete Breathers in Deformed Graphene  

E-Print Network (OSTI)

The linear and nonlinear dynamics of elastically deformed graphene have been studied. The region of the stability of a planar graphene sheet has been represented in the space of the two-dimensional strain (? xx, ? yy) with the x and y axes oriented in the zigzag and armchair directions, respectively. It has been shown that the gap in the phonon spectrum appears in graphene under uniaxial deformation in the zigzag or armchair direction, while the gap is not formed under a hydrostatic load. It has been found that graphene deformed uniaxially in the zigzag direction supports the existence of spatially localized nonlinear modes in the form of discrete breathers, the frequency of which decreases with an increase in the amplitude. This indicates soft nonlinearity in the system. It is unusual that discrete breather has frequency within the phonon spectrum of graphene. This is explained by the fact that the oscillation of the discrete breather is polarized in the plane of the graphene sheet, while the phonon spectral band where the discrete breather frequency is located contains phonons oscillating out of plane. The stability of the discrete breather with respect to the small out-of-plane perturbation of the graphene sheet has been demonstrated. DOI: 10.1134/S0021364011190106 1.

unknown authors

2011-01-01T23:59:59.000Z

176

Quantum chaos on discrete graphs  

E-Print Network (OSTI)

Adapting a method developed for the study of quantum chaos on {\\it quantum (metric)} graphs \\cite {KS}, spectral $\\zeta$ functions and trace formulae for {\\it discrete} Laplacians on graphs are derived. This is achieved by expressing the spectral secular equation in terms of the periodic orbits of the graph, and obtaining functions which belongs to the class of $\\zeta$ functions proposed originally by Ihara \\cite {Ihara}, and expanded by subsequent authors \\cite {Stark,Sunada}. Finally, a model of "classical dynamics" on the discrete graph is proposed. It is analogous to the corresponding classical dynamics derived for quantum graphs \\cite {KS}.

Uzy Smilansky

2007-04-26T23:59:59.000Z

177

Chiral Symmetry Breaking in Graphene  

E-Print Network (OSTI)

The question of whether the Coulomb interaction is strong enough to break the sublattice symmetry of un-doped graphene is discussed. We formulate a strong coupling expansion where the ground state of the Coulomb Hamiltonian is found exactly and the kinetic hopping Hamiltonian is treated as a perturbation. We argue that many of the properties of the resulting system would be shared by graphene with a Hubbard model interaction. In particular, the best candidate sublattice symmetry breaking ground state is an antiferromagnetic Mott insulator. We discuss the results of some numerical simulations which indicate that the Coulomb interaction is indeed subcritical. We also point out the curious fact that, if the electron did not have spin degeneracy, the tendency to break chiral symmetry would be much greater and even relatively weak Coulomb interactions would likely gap the spectrum.

Gordon W. Semenoff

2011-08-15T23:59:59.000Z

178

Test particle motion in the space-time of a Kerr black hole pierced by a cosmic string  

Science Conference Proceedings (OSTI)

We study the geodesic equation in the space-time of a Kerr black hole pierced by an infinitely thin cosmic string and give the complete set of analytical solutions of this equation for massive and massless particles in terms of Mino time that allows one to decouple the r and {theta} components of the geodesic equation. The solutions of the geodesic equation can be classified according to the particle's energy and angular momentum, the mass and angular momentum per mass of the black hole. We give examples of orbits showing the influence of the cosmic string. We also discuss the perihelion shift and the Lense-Thirring effect for bound orbits and show that the presence of a cosmic string enhances both effects. Comparing our results with experimental data from the LAGEOS satellites we find an upper bound on the energy per unit length of a string piercing the earth which is approximately 10{sup 16} kg/m. Our work has also applications to the recently suggested explanation of the alignment of the polarization vector of quasars using remnants of cosmic string decay in the form of primordial magnetic field loops.

Hackmann, Eva [ZARM, Universitaet Bremen, Am Fallturm, 28359 Bremen (Germany); Hartmann, Betti; Sirimachan, Parinya [School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany); Laemmerzahl, Claus [ZARM, Universitaet Bremen, Am Fallturm, 28359 Bremen (Germany); Institut fuer Physik, Universitaet Oldenburg, 26111 Oldenburg (Germany)

2010-08-15T23:59:59.000Z

179

Exploiting lower face symmetry in appearance-based automatic speechreading  

E-Print Network (OSTI)

Appearance-based visual speech feature extraction is being widely used in the automatic speechreading and audio-visual speech recognition literature. In its most common application, the discrete cosine transform (DCT) is utilized to compress the image of the speaker’s mouth region-of-interest (ROI), and the highest energy spatial frequency components are retained as visual features. Good generalization performance of the resulting system however requires robust ROI extraction and its consistent normalization, designed to compensate for speaker headpose and other data variations. In general, one expects that the ROI- if correctly normalized- will be nearly laterally symmetric, due to the approximate symmetry of human faces. We thus argue that forcing lateral ROI symmetry can be beneficial to automatic speechreading, providing a mechanism to compensate for small face and mouth tracking errors, which would otherwise result to incorrect ROI normalization. In this paper, we propose to achieve such ROI symmetry indirectly, by considering the spatial frequency domain and exploiting the DCT properties. In particular, we propose to remove the odd frequency DCT components from the selected visual feature vector. We experimentally demonstrate that, in general, this approach does not hurt speechreading performance, while it reduces computation, since it results to less DCT features. In addition, for the same number of features, as in traditional DCT coefficient selection, the method results in significant speechreading improvements. For the connected-digit automatic speechreading experiments considered, and for low feature dimensionalities, such can reach up to 12 % relative reduction in word error rate. 1.

Gerasimos Potamianos; Patricia Scanlon

2005-01-01T23:59:59.000Z

180

The discrete versus continuous controversy in physics  

Science Conference Proceedings (OSTI)

This paper presents a sample of the deep and multiple interplay between discrete and continuous behaviours and the corresponding modellings in physics. The aim of this overview is to show that discrete and continuous features coexist in any natural phenomenon, ...

Annick Lesne

2007-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Locally exact modifications of discrete gradient schemes  

E-Print Network (OSTI)

Locally exact integrators preserve linearization of the original system at every point. We construct energy-preserving locally exact discrete gradient schemes for arbitrary multidimensional canonical Hamiltonian systems by modifying classical discrete gradient schemes. Modifications of this kind are found for any discrete gradient.

Cie?li?ski, Jan L

2013-01-01T23:59:59.000Z

182

Discrete conformal mappings via circle patterns  

Science Conference Proceedings (OSTI)

We introduce a novel method for the construction of discrete conformal mappings from surface meshes of arbitrary topology to the plane. Our approach is based on circle patterns, that is, arrangements of circles---one for each face---with prescribed ... Keywords: Conformal parameterizations, circle patterns, discrete analytic functions, discrete differential geometry, meshing, texture mapping

Liliya Kharevych; Boris Springborn; Peter Schröder

2006-04-01T23:59:59.000Z

183

Color Superconductivity: Symmetries and Effective Lagrangians  

E-Print Network (OSTI)

I briefly review the symmetries and the associated low energy effective Lagrangian for two light flavor Color Superconductivity (2SC).

Francesco Sannino

2001-07-24T23:59:59.000Z

184

Chiral symmetry breaking patterns in the U_L(n)xU_R(n) meson model  

E-Print Network (OSTI)

Chiral symmetry breaking patterns are investigated in the U_L(n)xU_R(n) meson model. It is shown that new classes of minima of the effective potential belonging to the center of the Lie algebra exist for arbitrary flavor number n. The true ground state of the system is searched nonperturbatively and although multiple local minima of the effective potential may exist, it is argued that in regions of the parameter space applicable for the strong interaction, strictly a U_L(n)xU_R(n)->U_V(n) spontaneous symmetry breaking is possible. The reason behind this is the existence of a discrete subset of axial symmetries, which connects various U_V(n) symmetric vacua of the theory. The results are in agreement with the Vafa-Witten theorem of QCD, illustrating that it remains valid, even without gauge fields, for an effective model of the strong interaction.

G. Fejos

2012-12-14T23:59:59.000Z

185

Critical Point Symmetries in Nuclei  

E-Print Network (OSTI)

Critical Point Symmetries (CPS) appear in regions of the nuclear chart where a rapid change from one symmetry to another is observed. The first CPSs, introduced by F. Iachello, were E(5), which corresponds to the transition from vibrational [U(5)] to gamma-unstable [O(6)] behaviour, and X(5), which represents the change from vibrational [U(5)] to prolate axially deformed [SU(3)] shapes. These CPSs have been obtained as special solutions of the Bohr collective Hamiltonian. More recent special solutions of the same Hamiltonian, to be described here, include Z(5) and Z(4), which correspond to maximally triaxial shapes (the latter with ``frozen'' gamma=30 degrees), as well as X(3), which corresponds to prolate shapes with ``frozen'' gamma=0. CPSs have the advantage of providing predictions which are parameter free (up to overall scale factors) and compare well to experiment. However, their mathematical structure [with the exception of E(5)] needs to be clarified.

Bonatsos, D; Petrellis, D; Terziev, P A; Yigitoglu, I; Bonatsos, Dennis

2006-01-01T23:59:59.000Z

186

Inhomogeneous chiral symmetry breaking phases  

Science Conference Proceedings (OSTI)

We investigate inhomogeneous chiral symmetry breaking phases in the phase diagram of the two-flavor Nambu-Jona-Lasinio model, concentrating on phases with one-dimensional modulations. It is found that the first-order transition line in the phase diagram of homogeneous phases gets completely covered by an inhomogeneous phase which is bordered by second-order transition lines. The inhomogeneous phase turns out to be remarkably stable when vector interactions are included.

Buballa, M., E-mail: michael.buballa@physik.tu-darmstadt.de; Carignano, S., E-mail: carignano@crunch.ikp.physik.tu-darmstadt.de [Technische Universitaet Darmstadt, Institut fuer Kernphysik (Germany); Nickel, D., E-mail: mdjn@u.washington.edu [University of Washington, Institute for Nuclear Theory (United States)

2012-06-15T23:59:59.000Z

187

Comparison of point kinetics, improved quasistatic and theta method as space-time kinetics solvers in DONJON-3 simulations  

Science Conference Proceedings (OSTI)

To ensure the safety of nuclear reactors, we have to simulate accurately their normal operation and also accident cases. To perform transient calculations, coupled neutronic and fhermo-hydraulic codes are used. This article compares three neutronic solvers. The first one is the point kinetic approach where the flux shape is constant during all the transient. For the second method (the improved quasistatic method), the flux shape is constant but only during small time steps. Finally, we used the theta approach where both flux and precursors distributions vary with time and space. Transients of Lost Of Coolant Accident in CANDU-6 reactors have been simulated with DONJON and the outputs of a thermalhydraulic system code. Results show that the point kinetics is inappropriate for transient with large distortion of the flux shape. Improved quasistatic and theta methods give relatively similar results. However, the improved quasistatic approach is less stable and a little bit more sensitive on time-step and spatial discretization than the theta method is. (authors)

Chambon, R.; Marleau, G. [Institut de Genie Nucleaire, Ecole Polytechnique de Montreal, 2500 chemin de la Polytechnique, Montreal, QC H3C 3A7 (Canada)

2012-07-01T23:59:59.000Z

188

Hidden Rotational Symmetries in Magnetic Domain Patterns  

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

Hidden Rotational Symmetries in Hidden Rotational Symmetries in Magnetic Domain Patterns Hidden Rotational Symmetries in Magnetic Domain Patterns Print Wednesday, 27 June 2012 00:00 Magnetic thin films have complicated domain patterns that may or may not repeat with each cycle through a hysteresis loop. A magnetic thin film with perpendicular anisotropy, such as that used in computer hard drives, for example, commonly exhibits labyrinthine domain patterns. These patterns are disordered over a macroscopic length scale, and intuitively we do not expect to observe any symmetry in such systems. Scientists at the ALS, the University of Oregon, and the University of California, San Diego, have recently used coherent soft x-ray scattering with angular Fourier analysis to discover that the disordered domain patterns do, in fact, exhibit rotational symmetries, which can be as small as two-fold or as large as 30-fold. Their study of magnetic symmetries gives scientists a toolbox for discovering hidden symmetries in diverse material systems.

189

Bell's Jump Process in Discrete Time  

E-Print Network (OSTI)

The jump process introduced by J. S. Bell in 1986, for defining a quantum field theory without observers, presupposes that space is discrete whereas time is continuous. In this letter, our interest is to find an analogous process in discrete time. We argue that a genuine analog does not exist, but provide examples of processes in discrete time that could be used as a replacement.

Jonathan Barrett; Matthew Leifer; Roderich Tumulka

2005-06-08T23:59:59.000Z

190

Discrete Frontal Propagation in a Nonconvective Environment  

Science Conference Proceedings (OSTI)

Surface discrete frontal propagation in a wintertime, nonconvective environment is documented using conventional surface and upper-air data and simulated using the PSU–NCAR mesoscale model.

Joseph J. Charney; J. Michael Fritsch

1999-09-01T23:59:59.000Z

191

NETL: Discrete Fracture Reservoir Simulation Software  

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

Discrete Fracture Reservoir Simulation FRACGENNFFLOW Shale Gas Flow Simulation Shale Gas Flow Simulation FRACGENNFFLOW, a fractured reservoir modeling software developed by the...

192

Recoverable Robust Knapsack: the Discrete Scenario Case  

E-Print Network (OSTI)

Feb 24, 2011... different customers according to their demands maximizing the profit of ... In this paper, we show that for a fixed number of discrete scenarios ...

193

Bayesian Analysis of Discrete Longitudinal Data.  

E-Print Network (OSTI)

??This thesis explores a Bayesian hierarchical model to compare treatment effectiveness for menopausal symptom relief. Specifically, this model recognizes the discrete nature of the data,… (more)

Bernini, Nicholas

2006-01-01T23:59:59.000Z

194

Discrete Thermodynamics of Chemical Equilibria  

E-Print Network (OSTI)

The paper sets forth comprehensive basics of Discrete Thermodynamics of Chemical Equilibria (DTD), developed by the author during the last decade and spread over series of publications. Based on the linear equations of irreversible thermodynamics, De Donder's definition of the thermodynamic force, and the Le Chatelier principle, DTD brings forward a notion of chemical equilibrium as a balance of internal and external thermodynamic forces, acting against a chemical system. The basic expression of DTD is a logistic map that ties together energetic characteristics of the chemical transformation in the system, its deviation from true thermodynamic equilibrium, and the sum of thermodynamic forces, causing that deviation. System deviation from thermodynamic equilibrium is the major variable of the theory. Solutions to the basic map define the chemical system domain of states comprising bifurcation diagrams with four areas, from true thermodynamic equilibrium to chaos, having specific distinctive meaning for chemica...

Zilbergleyt, B

2008-01-01T23:59:59.000Z

195

Horizontal Symmetries $?(150)$ and $?(600)$  

E-Print Network (OSTI)

Using group theory of mixing to examine all finite subgroups of SU(3) with an order less than 512, we found recently that only the group $\\Delta(150)$ can give rise to a correct reactor angle $\\th_{13}$ of neutrino mixing without any free parameter. It predicts $\\sin^22\\th_{13}=0.11$ and a sub-maximal atmospheric angle with $\\sin^22\\th_{23}=0.94$, in good agreement with experiment. The solar angle $\\th_{12}$, the CP phase $\\d$, and the neutrino masses $m_i$ are left as free parameters. In this article we provide more details of this case, discuss possible gain and loss by introducing right-handed symmetries, and/or valons to construct dynamical models. A simple model is discussed where the solar angle agrees with experiment, and all its mixing parameters can be obtained from the group $\\Delta(600)$ by symmetry alone. The promotion of $\\Delta(150)$ to $\\Delta(600)$ is on the one hand analogous to the promotion of $S_3$ to $S_4$ in the presence of tribimaximal mixing, and on the other hand similar to the extension from $A_4$ to $S_4$ in that case.

C. S. Lam

2013-01-09T23:59:59.000Z

196

Introduction to Electroweak Symmetry Breaking  

SciTech Connect

The Standard Model (SM) is the backbone of elementary particle physics-not only does it provide a consistent framework for studying the interactions of quark and leptons, but it also gives predictions which have been extensively tested experimentally. In these notes, I review the electroweak sector of the Standard Model, discuss the calculation of electroweak radiative corrections to observables, and summarize the status of SM Higgs boson searches. Despite the impressive experimental successes, however, the electroweak theory is not completely satisfactory and the mechanism of electroweak symmetry breaking is untested. I will discuss the logic behind the oft-repeated statement: 'There must be new physics at the TeV scale'. These lectures reflect my strongly held belief that upcoming results from the LHC will fundamentally change our understanding of electroweak symmetry breaking. In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.

Dawson,S.

2008-10-02T23:59:59.000Z

197

Hidden Rotational Symmetries in Magnetic Domain Patterns  

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

Hidden Rotational Symmetries in Magnetic Domain Patterns Print Hidden Rotational Symmetries in Magnetic Domain Patterns Print Magnetic thin films have complicated domain patterns that may or may not repeat with each cycle through a hysteresis loop. A magnetic thin film with perpendicular anisotropy, such as that used in computer hard drives, for example, commonly exhibits labyrinthine domain patterns. These patterns are disordered over a macroscopic length scale, and intuitively we do not expect to observe any symmetry in such systems. Scientists at the ALS, the University of Oregon, and the University of California, San Diego, have recently used coherent soft x-ray scattering with angular Fourier analysis to discover that the disordered domain patterns do, in fact, exhibit rotational symmetries, which can be as small as two-fold or as large as 30-fold. Their study of magnetic symmetries gives scientists a toolbox for discovering hidden symmetries in diverse material systems.

198

Discrete particle transport in porous media : discrete observations of physical mechanisms influencing particle behavior  

E-Print Network (OSTI)

An understanding of how discrete particles in the micron to submicron range behave in porous media is important to a number of environmental problems. Discrete particle behavior in the interior of a porous medium is complex ...

Yoon, Joon Sik, 1973-

2005-01-01T23:59:59.000Z

199

QCD, Symmetry Breaking and the Random Lattice  

E-Print Network (OSTI)

According to the Nielsen-Ninomiya No-Go theorem, the doubling of fermions on the lattice cannot be suppressed in a chiral theory. Whereas Wilson and staggered fermions suppress doublers with explicit breaking of chiral symmetry, the random lattice does so by spontaneous chiral symmetry breaking even in the free theory. I present results for meson masses, the chiral condensate and fermionic eigenvalues from simulations of quenched QCD on random lattices in four dimensions, focusing on chiral symmetry breaking. 1.

Saul D. Cohen A

2006-01-01T23:59:59.000Z

200

Partial Dynamical Symmetry and Mixed Dynamics  

E-Print Network (OSTI)

Partial dynamical symmetry describes a situation in which some eigenstates have a symmetry which the quantum Hamiltonian does not share. This property is shown to have a classical analogue in which some tori in phase space are associated with a symmetry which the classical Hamiltonian does not share. A local analysis in the vicinity of these special tori reveals a neighbourhood of phase space foliated by tori. This clarifies the suppression of classical chaos associated with partial dynamical symmetry. The results are used to divide the states of a mixed system into ``chaotic'' and ``regular'' classes.

A. Leviatan; N. D. Whelan

1996-08-24T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Hidden Rotational Symmetries in Magnetic Domain Patterns  

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

the large-scale pattern. Research reported by Su et al. shows how to address such esoteric questions, while specifically suggesting that hidden rotational symmetries may play...

202

Jefferson Lab Science Series - Symmetry - From Kaleidoscopes...  

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

Detecting Einstein's Gravity Waves Previous Video (Detecting Einstein's Gravity Waves) Science Series Video Archive Next Video (Physics IQ Test) Physics IQ Test Symmetry - From...

203

SLAC National Accelerator Laboratory - symmetry magazine  

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

Symmetry is a magazine about particle physics and its connections to other aspects of life and science, from interdisciplinary collaborations to policy to culture. It is...

204

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

205

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

206

Are there capacity limitations in symmetry perception?  

E-Print Network (OSTI)

1980). The demonstration of capacity limitation. Cognitive1972). Visual processing capacity and attentional control.J. (1996). Goodness of CAPACITY LIMIT OF SYMMETRY PERCEPTION

Huang, L Q; Pashler, Harold; Junge, J A

2004-01-01T23:59:59.000Z

207

Super Gabor frames on discrete periodic sets  

Science Conference Proceedings (OSTI)

Due to its potential applications in multiplexing techniques such as time division multiple access and frequency division multiple access, superframe has interested some mathematicians and engineering specialists. In this paper, we investigate super ... Keywords: 42C40, Discrete Zak transform, Discrete periodic sets, Gabor dual, Super Gabor frame, Superframe

Yun-Zhang Li; Qiao-Fang Lian

2013-05-01T23:59:59.000Z

208

Structural Workshop Paper---Estimating Discrete Games  

Science Conference Proceedings (OSTI)

This paper provides a critical review of the methods for estimating static discrete games and their relevance for quantitative marketing. We discuss the various modeling approaches, alternative assumptions, and relevant trade-offs involved in taking ... Keywords: discrete choice, games estimation, structural models

Paul B. Ellickson; Sanjog Misra

2011-11-01T23:59:59.000Z

209

Discrete-event modelling of fire spreading  

Science Conference Proceedings (OSTI)

We deal here with the application of discrete-event System Specification (DEVS) formalism to implement a semi-physical fire spread model. Currently, models from physics finely representing forest fires are not efficient and still under development. If ... Keywords: Cellular models, DEVS, Discrete-event modelling and simulation, Fire spread

Alexandre Muzy; Eric Innocenti; Antoine Aiello; Jean-François Santucci; Thierry Marcelli; Paul Antoine Santoni

2008-02-01T23:59:59.000Z

210

Black Hole Spectrum: Continuous or Discrete?  

E-Print Network (OSTI)

We formulate a qualitative argument, based on Heisenberg's uncertainty principle, to support the claim that when the effects of matter fields are assumed to overshadow the effects of quantum mechanics of spacetime, the discrete spectrum of black hole radiation, as such as predicted by Bekenstein's proposal for a discrete black hole area spectrum, reduces to Hawking's black-body spectrum.

Jarmo Makela

1996-08-30T23:59:59.000Z

211

Symmetries of Holographic Minimal Models  

E-Print Network (OSTI)

It was recently proposed that a large N limit of a family of minimal model CFTs is dual to a certain higher spin gravity theory in AdS_3, where the 't Hooft coupling constant of the CFT is related to a deformation parameter of the higher spin algebra. We identify the asymptotic symmetry algebra of the higher spin theory for generic 't Hooft parameter, and show that it coincides with a family of W-algebras previously discovered in the context of the KP hierarchy. We furthermore demonstrate that this family of W-algebras controls the representation theory of the minimal model CFTs in the 't Hooft limit. This provides a non-trivial consistency check of the proposal and explains part of the underlying mechanism.

Matthias R. Gaberdiel; Thomas Hartman

2011-01-14T23:59:59.000Z

212

Symmetries of Holographic Minimal Models  

E-Print Network (OSTI)

It was recently proposed that a large N limit of a family of minimal model CFTs is dual to a certain higher spin gravity theory in AdS_3, where the 't Hooft coupling constant of the CFT is related to a deformation parameter of the higher spin algebra. We identify the asymptotic symmetry algebra of the higher spin theory for generic 't Hooft parameter, and show that it coincides with a family of W-algebras previously discovered in the context of the KP hierarchy. We furthermore demonstrate that this family of W-algebras controls the representation theory of the minimal model CFTs in the 't Hooft limit. This provides a non-trivial consistency check of the proposal and explains part of the underlying mechanism.

Gaberdiel, Matthias R

2011-01-01T23:59:59.000Z

213

MULTISCALE DISCRETIZATION OF SHAPE CONTOURS  

SciTech Connect

We present an efficient multi-scale scheme to adaptively approximate the continuous (or densely sampled) contour of a planar shape at varying resolutions. The notion of shape is intimately related to the notion of contour, and the efficient representation of the contour of a shape is vital to a computational understanding of the shape. Any polygonal approximation of a planar smooth curve is equivalent to a piecewise constant approximation of the parameterized X and Y coordinate functions of a discrete point set obtained by densely sampling the curve. Using the Haar wavelet transform for the piecewise approximation yields a hierarchical scheme in which the size of the approximating point set is traded off against the morphological accuracy of the approximation. Our algorithm compresses the representation of the initial shape contour to a sparse sequence of points in the plane defining the vertices of the shape's polygonal approximation. Furthermore, it is possible to control the overall resolution of the approximation by a single, scale-independent parameter.

Prasad, L.; Rao, R.

2000-09-01T23:59:59.000Z

214

Nuclear symmetry energy: An experimental overview  

E-Print Network (OSTI)

The nuclear symmetry energy is a fundamental quantity important for studying the structure of systems as diverse as the atomic nucleus and the neutron star. Considerable efforts are being made to experimentally extract the symmetry energy and its dependence on nuclear density and temperature. In this article, we review experimental studies carried out up-to-date and their current status.

Shetty, D V

2010-01-01T23:59:59.000Z

215

Symmetry Problems in Low Energy Physics  

E-Print Network (OSTI)

Some recent experimental and theoretical work on 1) charge symmetry-breaking, 2) parity non-conservation, and 3) searches for breaking of time reversal invariance are reviewed. The examples illustrate the uses of symmetry to learn about underlying dynamics and/or structure.

Ernest M. Henley

1995-08-17T23:59:59.000Z

216

Exploiting Matrix Symmetries and Physical Symmetries in Matrix Product States and Tensor Trains  

E-Print Network (OSTI)

We focus on symmetries related to matrices and vectors appearing in the simulation of quantum many-body systems. Spin Hamiltonians have special matrix-symmetry properties such as persymmetry. Furthermore, the systems may exhibit physical symmetries translating into symmetry properties of the eigenvectors of interest. Both types of symmetry can be exploited in sparse representation formats such as Matrix Product States (MPS) for the desired eigenvectors. This paper summarizes symmetries of Hamiltonians for typical physical systems such as the Ising model and lists resulting properties of the related eigenvectors. Based on an overview of Matrix Product States (Tensor Trains or Tensor Chains) and their canonical normal forms we show how symmetry properties of the vector translate into relations between the MPS matrices and, in turn, which symmetry properties result from relations within the MPS matrices. In this context we analyze different kinds of symmetries and derive appropriate normal forms for MPS representing these symmetries. Exploiting such symmetries by using these normal forms will lead to a reduction in the number of degrees of freedom in the MPS matrices. This paper provides a uniform platform for both well-known and new results which are presented from the (multi-)linear algebra point of view.

T. Huckle; K. Waldherr; T. Schulte-Herbrueggen

2013-01-04T23:59:59.000Z

217

Discrete variable representation for highly excited states of hydrogen atoms in magnetic fields  

SciTech Connect

A discrete variable representation (DVR) appropriate for describing the highly excited states of hydrogen atoms in laboratory-strength magnetic fields is constructed by using a symmetry-adapted direct product of one-dimensional DVR{close_quote}s in parabolic coordinates related to generalized Gauss-Laguerre quadratures. The resulting sparse Hamiltonian matrix is used in an iterative (filter-diagonalization) procedure to obtain eigenvalues and eigenvectors in a given spectral domain. The method is applied to calculate eigenvalues and lifetimes of {open_quotes}circular{close_quotes} Rydberg states, as well as oscillator strengths for the excitation of highly excited states. {copyright} {ital 1997} {ital The American Physical Society}

Grozdanov, T.P.; Andric, L.; Manescu, C.; McCarroll, R. [Laboratoire de Dynamique des Ions, Atomes et Molecules (URA 774 du CNRS), Universite Pierre et Marie Curie, 4 Place Jussieu T12-B75, 75252 Paris Cedex 05 (France); Grozdanov, T.P. [Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia)

1997-09-01T23:59:59.000Z

218

Symmetry-Protected Quantum Spin Hall Phases in Two Dimensions  

E-Print Network (OSTI)

Symmetry-protected topological (SPT) states are short-range entangled states with symmetry. Nontrivial SPT states have symmetry-protected gapless edge excitations. In 2 dimension (2D), there are an infinite number of ...

Liu, Zheng-Xin

219

Graphene, Lattice QFT and Symmetries  

E-Print Network (OSTI)

Borrowing ideas from tight binding model, we propose a board class of Lattice QFT models that are classified by the ADE Lie algebras. In the case of su(N) series, we show that the couplings between the quantum states living at the first nearest neighbor sites of the lattice $\\mathcal{L}_{su(N)}$ are governed by the complex fundamental representations \\underline{${{\\mathbf{N}}}$} and $\\bar{{\\mathbf{N}}}$ of $su(N)$; and the second nearest neighbor interactions are described by its adjoint $\\underline{\\mathbf{N}} \\otimes \\bar{\\mathbf{N}}$. The lattice models associated with the leading su(2), su(3) and su(4) cases are explicitly studied and their fermionic field realizations are given. It is also shown that the su(2) and su(3) models describe respectively the electronic properties of the acetylene chain and the graphene. It is established as well that the energy dispersion of the first nearest neighbor couplings is completely determined by the $A_{N}$ roots $ \\mathbf{\\alpha}$ through the typical dependence $N/2+\\sum_{roots}\\cos(\\mathbf{k}.\\alpha) $ with $\\mathbf{k}$ the wave vector. Other features such as DE extension and other applications are also discussed. Keywords: Tight Binding Model, Graphene, Lattice QFT, ADE Symmetries.

L. B Drissi; E. H Saidi; M. Bousmina

2011-01-05T23:59:59.000Z

220

A discrete curvature on a planar graph  

E-Print Network (OSTI)

Given a planar graph derived from a spherical, euclidean or hyperbolic tessellation, one can define a discrete curvature by combinatorial properties, which after embedding the graph in a compact 2d-manifold, becomes the Gaussian curvature.

M. Lorente

2004-12-20T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Combining sustainability criteria with discrete event simulation  

Science Conference Proceedings (OSTI)

This paper attempts to highlight shortcomings in the concept of sustainability and ways to make the concept more workable by presenting the development of an Environmental Management Information System (EMIS) as a combination of discrete event simulation ...

Andi H. Widok; Volker Wohlgemuth; Bernd Page

2011-12-01T23:59:59.000Z

222

A discrete model of thin shells  

Science Conference Proceedings (OSTI)

We present a discrete model for the behavior of thin flexible structures, such as hats, leaves, and aluminum cans, which are characterized by a curved undeformed configuration. Previously such models required complex continuum mechanics formulations ...

Eitan Grinspun

2005-07-01T23:59:59.000Z

223

The effect of a fifth large-scale space-time dimension on the conservation of energy in a four dimensional Universe  

E-Print Network (OSTI)

The effect of introducing a fifth large-scale space-time dimension to the equations of orbital dynamics was analysed in an earlier paper by the authors. The results showed good agreement with the observed flat rotation curves of galaxies and the Pioneer Anomaly. This analysis did not require the modification of Newtonian dynamics, but rather only their restatement in a five dimensional framework. The same analysis derived a acceleration parameter ar, which plays an important role in the restated equations of orbital dynamics, and suggested a value for ar. In this companion paper, the principle of conservation of energy is restated within the same five-dimensional framework. The resulting analysis provides an alternative route to estimating the value of ar, without reference to the equations of orbital dynamics, and based solely on key cosmological constants and parameters, including the gravitational constant, G. The same analysis suggests that: (i) the inverse square law of gravity may itself be due to the conservation of energy at the boundary between a four-dimensional universe and a fifth large-scale space-time dimension; and (ii) there is a limiting case for the Tulley-Fisher relationship linking the speed of light to the mass of the Universe.

M. B. Gerrard; T. J. Sumner

2007-04-03T23:59:59.000Z

224

Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness  

E-Print Network (OSTI)

Contrary to what is often stated, a fundamental spacetime discreteness need not contradict Lorentz invariance. A causal set's discreteness is in fact locally Lorentz invariant, and we recall the reasons why. For illustration, we introduce a phenomenological model of massive particles propagating in a Minkowski spacetime which arises from an underlying causal set. The particles undergo a Lorentz invariant diffusion in phase space, and we speculate on whether this could have any bearing on the origin of high energy cosmic rays.

Fay Dowker; Joe Henson; Rafael D. Sorkin

2003-11-17T23:59:59.000Z

225

The Golden Ratio Prediction for the Solar Angle from a Natural Model with A5 Flavour Symmetry  

E-Print Network (OSTI)

We formulate a consistent model predicting, in the leading order approximation, maximal atmospheric mixing angle, vanishing reactor angle and tan {\\theta}_12 = 1/{\\phi} where {\\phi} is the Golden Ratio. The model is based on the flavour symmetry A5 \\tiems Z5 \\times Z3, spontaneously broken by a set of flavon fields. By minimizing the scalar potential of the theory up to the next-to-leading order in the symmetry breaking parameter, we demonstrate that this mixing pattern is naturally achieved in a finite portion of the parameter space, through the vacuum alignment of the flavon fields. The leading order approximation is stable against higher-order corrections. We also compare our construction to other models based on discrete symmetry groups.

Feruglio, Ferruccio

2011-01-01T23:59:59.000Z

226

The Golden Ratio Prediction for the Solar Angle from a Natural Model with A5 Flavour Symmetry  

E-Print Network (OSTI)

We formulate a consistent model predicting, in the leading order approximation, maximal atmospheric mixing angle, vanishing reactor angle and tan {\\theta}_12 = 1/{\\phi} where {\\phi} is the Golden Ratio. The model is based on the flavour symmetry A5 \\times Z5 \\times Z3, spontaneously broken by a set of flavon fields. By minimizing the scalar potential of the theory up to the next-to-leading order in the symmetry breaking parameter, we demonstrate that this mixing pattern is naturally achieved in a finite portion of the parameter space, through the vacuum alignment of the flavon fields. The leading order approximation is stable against higher-order corrections. We also compare our construction to other models based on discrete symmetry groups.

Ferruccio Feruglio; Alessio Paris

2011-01-02T23:59:59.000Z

227

Symmetries and relaxations in non-equilibrium thermodynamics.  

E-Print Network (OSTI)

??Static thermodynamic susceptibilities obey symmetries that have been known for a very long time. These are the Maxwell relations. Less well-known are the symmetry properties… (more)

DeSimone, Anthony Joseph Jr

2005-01-01T23:59:59.000Z

228

Symmetry energy coefficients for asymmetric nuclear matter  

E-Print Network (OSTI)

Symmetry energy coefficients of asymmetric nuclear matter are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions for the density fluctuations lead to certain isospin (n-p asymmetry) dependences of the polarizabilities. Secondly, with Skyrme type interactions, the static limit of the dynamical polarizability is investigated corresponding to the inverse symmetry energy coefficient which assumes different values at different asymmetries (and densities and temperatures). The symmetry energy coefficient (in the isovector channel) is found to increase as n-p asymmetries increase. The spin symmetry energy coefficient is also briefly investigated.

Fábio L. Braghin

2003-12-16T23:59:59.000Z

229

Asymptotic Symmetries of Yang-Mills Theory  

E-Print Network (OSTI)

Asymptotic symmetries at future null infinity (I+) of Minkowski space for electrodynamics with massless charged fields, as well as non-Abelian gauge theories with gauge group G, are considered at the semiclassical level. The possibility of charge/color flux through I+ suggests the symmetry group is infinite-dimensional. It is conjectured that the symmetries include a G Kac-Moody symmetry whose generators are "large" gauge transformations which approach locally holomorphic functions on the conformal two-sphere at I+ and are invariant under null translations. The Kac-Moody currents are constructed from the gauge field at the future boundary of I+. The current Ward identities include Weinberg's soft photon theorem and its colored extension.

Andrew Strominger

2013-08-02T23:59:59.000Z

230

R Symmetry and the Mu Problem  

E-Print Network (OSTI)

A natural origin for the mu and B parameters of weak scale supersymmetric theories is proposed, applicable to any supersymmetry breaking messenger scale between the weak and Planck scales. Although quite general, it requires supersymmetric interactions to respect an R symmetry with definite quantum numbers, and it requires some new scale of symmetry breaking. The required R symmetry distinguishes the Higgs boson from the sneutrino, preserves baryon number in operators of dimension four and five, and contains R parity so that the lightest superpartner is stable. This origin for mu works for a variety of mediation mechanisms, including gauge mediation, gaugino mediation, and boundary condition breaking of supersymmetry. In any of these mediation schemes, our mechanism leads to a real B parameter, and the supersymmetric CP problem is solved. This R symmetry may naturally arise from supersymmetric theories in higher dimensions.

Lawrence J. Hall; Yasunori Nomura; Aaron Pierce

2002-04-04T23:59:59.000Z

231

Symmetry energy of warm nuclear systems  

E-Print Network (OSTI)

The temperature dependence of the symmetry energy and symmetry free energy coefficients of infinite nuclear matter and of finite nuclei is investigated. For infinite matter, both these coefficients are found to have a weaker dependence on temperature at densities close to saturation; at low but homogeneous densities, the temperature dependence becomes stronger. For finite systems, different definitions of symmetry energy coefficients are encountered in the literature yielding different values. A resolution to this problem is suggested from a global liquid-drop-inspired fit of the energies and free energies of a host of nuclei covering the entire periodic table. The hot nucleus is modeled in a subtracted finite-temperature-Thomas-Fermi framework, with dynamical surface phonon coupling to nucleonic motion plugged in. Contrary to infinite nuclear matter, a substantial change in the symmetry energy coefficients is observed for finite nuclei with temperature.

Agrawal, B K; Samaddar, S K; Centelles, M; Viñas, X

2013-01-01T23:59:59.000Z

232

Symmetry energy of warm nuclear systems  

E-Print Network (OSTI)

The temperature dependence of the symmetry energy and symmetry free energy coefficients of infinite nuclear matter and of finite nuclei is investigated. For infinite matter, both these coefficients are found to have a weaker dependence on temperature at densities close to saturation; at low but homogeneous densities, the temperature dependence becomes stronger. For finite systems, different definitions of symmetry energy coefficients are encountered in the literature yielding different values. A resolution to this problem is suggested from a global liquid-drop-inspired fit of the energies and free energies of a host of nuclei covering the entire periodic table. The hot nucleus is modeled in a subtracted finite-temperature-Thomas-Fermi framework, with dynamical surface phonon coupling to nucleonic motion plugged in. Contrary to infinite nuclear matter, a substantial change in the symmetry energy coefficients is observed for finite nuclei with temperature.

B. K. Agrawal; J. N. De; S. K. Samaddar; M. Centelles; X. Viñas

2013-08-26T23:59:59.000Z

233

Discrete gravity models and Loop Quantum Gravity: a short review  

E-Print Network (OSTI)

We review the relation between loop quantum gravity on a fixed graph and discrete models of gravity. We compare Regge and twisted geometries, and discuss discrete actions based on twisted geometries and on the discretization of the Plebanski action. We discuss the role of discrete geometries in the spin foam formalism, with particular attention to the definition of the simplicity constraints.

Dupuis, Maite; Speziale, Simone

2012-01-01T23:59:59.000Z

234

Energy Levels of "Hydrogen Atom" in Discrete Time Dynamics  

E-Print Network (OSTI)

We analyze dynamical consequences of a conjecture that there exists a fundamental (indivisible) quant of time. In particular we study the problem of discrete energy levels of hydrogen atom. We are able to reconstruct potential which in discrete time formalism leads to energy levels of unperturbed hydrogen atom. We also consider linear energy levels of quantum harmonic oscillator and show how they are produced in the discrete time formalism. More generally, we show that in discrete time formalism finite motion in central potential leads to discrete energy spectrum, the property which is common for quantum mechanical theory. Thus deterministic (but discrete time!) dynamics is compatible with discrete energy levels.

Andrei Khrennikov; Yaroslav Volovich

2006-04-27T23:59:59.000Z

235

symmetry magazine | dimensions of particle physics  

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

symmetry magazine symmetry magazine symmetry magazine dimensions of particle physics dimensions of particle physics A joint Fermilab/SLAC publication Search form Search Search Facebook Twitter RSS Feed subscribe masthead contact Home Departments application breaking commentary contest Day in the life Deconstruction Essay explain it in 60 seconds feature gallery Logbook Signal to background Science Topics applied science astrophysics Cosmic Frontier dark energy dark matter Energy Frontier extra dimensions Higgs boson Intensity Frontier neutrinos underground science Image Bank Archives Full Archives PDF Issues Print Editions sections subscribe application breaking commentary contest day in the life deconstruction essay explain it in 60 seconds feature gallery logbook signal to background Full Archives PDF Issues Print Editions

236

Eugene Wigner and Fundamental Symmetry Principles  

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

Eugene Wigner and Fundamental Symmetry Principles Eugene Wigner and Fundamental Symmetry Principles Patents · Resources with Additional Information · Wigner Honored "[Eugene P.] Wigner's great contribution to science, for which he won the Nobel Prize in Physics in 1963, was his insight into the fundamental mathematics and physics of quantum mechanics. He applied and extended the mathematical theory of groups to the quantum world of the atom; specifically, he used group theory to organize the quantum energy levels of electrons in atoms in a way that is now standard. With that mathematical approach to the atom, Wigner became one of the first to apprehend the deep implications of symmetry, which has since emerged as one, if not the, key principle of 20th-century theoretical physics. ... Eugene P. Wigner

237

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

238

A viable axion from gauged flavor symmetries  

E-Print Network (OSTI)

We consider a string inspired non-supersymmetric extension of the standard model with gauged anomalous U(1) flavor symmetries. Consistency requires the Green-Schwarz mechanism to cancel mixed anomalies. The additional required scalars provide Stuckelberg masses for the $Z'$ particles associated to the gauged flavor symmetry, so they decouple at low energies. Our models also include a complex scalar field $\\phi$ to generate Froggatt-Nielsen mass terms for light particles giving a partial solution to the fermion mass problem. A residual approximate (anomalous) global symmetry survives at low energies. The associated pseudo-Goldstone mode is the phase of the $\\phi$ scalar field, and it becomes the dominant contribution to the physical axion. An effective field theory analysis that includes neutrino masses gives a prediction for the axion decay constant. We find a simple modeI where the axion decay constant is in the center of the allowed window.

Berenstein, David

2010-01-01T23:59:59.000Z

239

Fast Mix Table Construction for Material Discretization  

Science Conference Proceedings (OSTI)

An effective hybrid Monte Carlo--deterministic implementation typically requires the approximation of a continuous geometry description with a discretized piecewise-constant material field. The inherent geometry discretization error can be reduced somewhat by using material mixing, where multiple materials inside a discrete mesh voxel are homogenized. Material mixing requires the construction of a ``mix table,'' which stores the volume fractions in every mixture so that multiple voxels with similar compositions can reference the same mixture. Mix table construction is a potentially expensive serial operation for large problems with many materials and voxels. We formulate an efficient algorithm to construct a sparse mix table in $O(\\text{number of voxels}\\times \\log \\text{number of mixtures})$ time. The new algorithm is implemented in ADVANTG and used to discretize continuous geometries onto a structured Cartesian grid. When applied to an end-of-life MCNP model of the High Flux Isotope Reactor with 270 distinct materials, the new method improves the material mixing time by a factor of 100 compared to a naive mix table implementation.

Johnson, Seth R [ORNL

2013-01-01T23:59:59.000Z

240

Electroless plating apparatus for discrete microsized particles  

SciTech Connect

Method and apparatus are disclosed for producing very uniform coatings of a desired material on discrete microsized particles by electroless techniques. Agglomeration or bridging of the particles during the deposition process is prevented by imparting a sufficiently random motion to the particles that they are not in contact with each other for a time sufficient for such to occur.

Mayer, Anton (Los Alamos, NM)

1978-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Electrolytic plating apparatus for discrete microsized particles  

SciTech Connect

Method and apparatus are disclosed for electrolytically producing very uniform coatings of a desired material on discrete microsized particles. Agglomeration or bridging of the particles during the deposition process is prevented by imparting a sufficiently random motion to the particles that they are not in contact with a powered cathode for a time sufficient for such to occur.

Mayer, Anton (Los Alamos, NM)

1976-11-30T23:59:59.000Z

242

The Thermal Aspects of Relativistic Quantum Field Theory as an Observational Window in a Deeper Layer of Quantum Space-Time or: Dirac's Revenge  

E-Print Network (OSTI)

In this paper we shall derive the thermal properties of the relativistic quantum vacuum from a more primordial underlying structure which shares some properties with the old Dirac-sea picture. We show in particular how the Tomita-KMS structure in RQFT is a consequence of the structure and dynamics of the underlying pattern of vacuum fluctuations. We explain the origin of the doubling phenomenon in thermofield theory and the duality symmetry between a local algebra of fields or observables and its commutant in RQFT and give an interpretation of the notion of thermal time.

Manfred Requardt

2013-09-05T23:59:59.000Z

243

A gravity term from spontaneous symmetry breaking  

E-Print Network (OSTI)

In this model, the gravity term in the Lagrangean comes from spontaneous symmetry breaking of an additional scalar quadruplet field $\\Upsilon$. The resulting gravitational field is approximate to one of the models of coframe gravity with parameters $\\rho_1 + 4 \\rho_2 = 0$, $\\rho_3 = 0$. This article includes an exact solution of coframe gravity with model parameters $\\rho_1 \

Mihai Moise

2014-01-02T23:59:59.000Z

244

Geometry and symmetries in lattice spinor gravity  

SciTech Connect

Lattice spinor gravity is a proposal for regularized quantum gravity based on fermionic degrees of freedom. In our lattice model the local Lorentz symmetry is generalized to complex transformation parameters. The difference between space and time is not put in a priori, and the euclidean and the Minkowski quantum field theory are unified in one functional integral. The metric and its signature arise as a result of the dynamics, corresponding to a given ground state or cosmological solution. Geometrical objects as the vierbein, spin connection or the metric are expectation values of collective fields built from an even number of fermions. The quantum effective action for the metric is invariant under general coordinate transformations in the continuum limit. The action of our model is found to be also invariant under gauge transformations. We observe a 'geometrical entanglement' of gauge- and Lorentz-transformations due to geometrical objects transforming non-trivially under both types of symmetry transformations. - Highlights: Black-Right-Pointing-Pointer We formulate the geometrical aspects of a proposal for a lattice regularized model of quantum gravity. Black-Right-Pointing-Pointer The vierbein shows an entanglement between Lorentz symmetry and gauge symmetry. Black-Right-Pointing-Pointer Euclidean and Minkowski signatures of the collective metric and the vierbein are described within the same functional integral.

Wetterich, C., E-mail: c.wetterich@thphys.uni-heidelberg.de

2012-09-15T23:59:59.000Z

245

Exploiting group symmetry in semidefinite programming relaxations ...  

E-Print Network (OSTI)

ment problem, and show how to exploit group symmetry in the problem data. Thus we ..... nalized' in a canonical way via an orthogonal transformation. ..... Note that values from [4] do not always give the same bound as we obtained, .... CentER Discussion Paper 2007-101, Tilburg Univer- ... Available at Optimization Online.

246

Quantified symmetry for entorhinal spatial maps  

Science Conference Proceedings (OSTI)

General navigation requires a spatial map that is not anchored to one environment. The firing fields of the ''grid cells'' found in the rat dorsolateral medial entorhinal cortex (dMEC) could be such a map. dMEC firing fields are also thought to be modeled ... Keywords: Hippocampus, Neural coding, Spatial cognition, Symmetry

Erick Chastain; Yanxi Liu

2007-06-01T23:59:59.000Z

247

Global Cut Framework for Removing Symmetries  

Science Conference Proceedings (OSTI)

In this paper, we propose a general technique for removing symmetries in CSPs during search. The idea is to record no-goods, during the exploration of the search tree, whose symmetric counterpart (if any) should be removed. The no-good, called Global ...

Filippo Focacci; Michela Milano

2001-11-01T23:59:59.000Z

248

Weyl-Gauge Symmetry of Graphene  

E-Print Network (OSTI)

The conformal invariance of the low energy limit theory governing the electronic properties of graphene is explored. In particular, it is noted that the massless Dirac theory in point enjoys local Weyl symmetry, a very large symmetry. Exploiting this symmetry in the two spatial dimensions and in the associated three dimensional spacetime, we find the geometric constraints that correspond to specific shapes of the graphene sheet for which the electronic density of states is the same as that for planar graphene, provided the measurements are made in accordance to the inner reference frame of the electronic system. These results rely on the (surprising) general relativistic-like behavior of the graphene system arising from the combination of its well known special relativistic-like behavior with the less explored Weyl symmetry. Mathematical structures, such as the Virasoro algebra and the Liouville equation, naturally arise in this three-dimensional context and can be related to specific profiles of the graphene sheet. Speculations on possible applications of three-dimensional gravity are also proposed.

Alfredo Iorio

2010-07-28T23:59:59.000Z

249

A H-infinity Fault Detection and Diagnosis Scheme for Discrete Nonlinear System Using Output Probability Density Estimation  

Science Conference Proceedings (OSTI)

In this paper, a H-infinity fault detection and diagnosis (FDD) scheme for a class of discrete nonlinear system fault using output probability density estimation is presented. Unlike classical FDD problems, the measured output of the system is viewed as a stochastic process and its square root probability density function (PDF) is modeled with B-spline functions, which leads to a deterministic space-time dynamic model including nonlinearities, uncertainties. A weighting mean value is given as an integral function of the square root PDF along space direction, which leads a function only about time and can be used to construct residual signal. Thus, the classical nonlinear filter approach can be used to detect and diagnose the fault in system. A feasible detection criterion is obtained at first, and a new H-infinity adaptive fault diagnosis algorithm is further investigated to estimate the fault. Simulation example is given to demonstrate the effectiveness of the proposed approaches.

Zhang Yumin; Lum, Kai-Yew [Temasek Laboratories, National University of Singapore, Singapore 117508 (Singapore); Wang Qingguo [Depa. Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2009-03-05T23:59:59.000Z

250

Discrete variable theory of triatomic photodissociation  

SciTech Connect

The coupled equations describing the photodissociation process are expressed in the discrete variable representation (DVR) in which the coupled equations are labeled by quadrature points rather than by internal basis functions. A large reduction in the dimensionality of the coupled equations can be realized since the spatially localized bound state nuclear wave function vanishes at most of the quadrature points, making only certain orientations of the fragments important in the region of strong interaction (small separation). The discrete variable theory of photodissociation is applied to the model dissociation of bent HCN in which the CN fragment is treated as a rigid rotor. The truncated DVR rotational distributions are compared with the exact close coupled rotational distributions, and excellent agreement with greatly reduced dimensionality of the equations is found.

Heather, R.W.; Light, J.C.

1983-07-01T23:59:59.000Z

251

Bessel-Zernike Discrete Variable Representation Basis  

SciTech Connect

The connection between the Bessel discrete variable basis expansion and a specific form of an orthogonal set of Jacobi polynomials is demonstrated. These so-called Zernike polynomials provide alternative series expansions of suitable functions over the unit interval. Expressing a Bessel function in a Zernike expansion provides a straightforward method of generating series identities. Furthermore, the Zernike polynomials may also be used to efficiently evaluate the Hankel transform for rapidly decaying functions or functions with finite support.

Cerjan, C J

2005-10-24T23:59:59.000Z

252

Relativistic pseudospin symmetry and shell model Hamiltonians that conserve pseudospin symmetry  

SciTech Connect

Professor Akito Arima and his colleagues discovered 'pseudospin' doublets forty-one years ago in spherical nuclei. These doublets were subsequently discovered in deformed nuclei. We show that pseudospin symmetry is an SU(2) symmetry of the Dirac Hamiltonian which occurs when the scalar and vector potentials are opposite in sign but equal in magnitude. This symmetry occurs independent of the shape of the nucleus: spherical, axial deformed, triaxial, and gamma unstable. We survey some of the evidence that pseudospin symmetry is approximately conserved for a Dirac Hamiltonian with realistic scalar and vector potentials by examining the energy spectra, the lower components of the Dirac eigenfunctions, the magnetic dipole and Gamow-Teller transitions in nuclei, the upper components of the Dirac eigenfunctions, and nucleon-nucleus scattering. We shall also suggest that pseudospin symmetry may have a fundamental origin in chiral symmetry breaking by examining QCD sum rules. Finally we derive the shell model Hamiltonians which conserve pseudospin and show that they involve tensor interactions.

Ginocchio, Joseph N [Los Alamos National Laboratory

2010-09-21T23:59:59.000Z

253

Discretely-observable continuous time quantum walks on Möbius strips and other exotic structures in 3D integrated photonics  

E-Print Network (OSTI)

We theoretically analyze the dynamical evolution of photonic quantum walks on M\\"obius strips and other exotic structures in 3D integrated photonics. Our flexible design allows discrete observations of continuous time quantum walks of photons in a variety of waveguide arrays. Furthermore, our design allows one to inject photons during the evolution, allowing the possibility of interacting with the photons as they are 'walking'. We find that non-trivial array topologies introduce novel time-dependent symmetries of the two-photon correlations. These properties allow a large degree of control for quantum state engineering of multimode entangled states in these devices.

Michael Delanty; M. J. Steel

2012-07-31T23:59:59.000Z

254

Discrete mechanics, optimal control and formation flying spacecraft  

E-Print Network (OSTI)

Discrete mechanics, optimal control and formation flying spacecraft Oliver Junge Center-Bl¨obaum partially supported by the CRC 376 Oliver Junge Discrete mechanics, optimal control and formation flying spacecraft p.1 #12;Outline mechanical optimal control problem direct discretization of the variational

Patrick, George

255

Adaptive fuzzy logic control of discrete-time dynamical systems  

Science Conference Proceedings (OSTI)

The objective of this paper is to achieve tracking control of a class of unknown nonlinear dynamical systems using a discrete-time fuzzy logic controller (FLC). Designing a discrete-time FLC is significant because almost all FLCs are implemented on digital ... Keywords: Adaptive control, Discrete-time control, Fuzzy approximation, Fuzzy logic, Universal fuzzy controller

S. Jagannathan; M. W. Vandegrift; F. L. Lewis

2000-02-01T23:59:59.000Z

256

Nuclear symmetry energy at subnormal densities from measured nuclear masses  

E-Print Network (OSTI)

The symmetry energy coefficients for nuclei with mass number A=20~250 are extracted from more than 2000 measured nuclear masses. With the semi-empirical connection between the symmetry energy coefficients of finite nuclei and the nuclear symmetry energy at reference densities, we investigate the density dependence of symmetry energy of nuclear matter at subnormal densities. The obtained results are compared with those extracted from other methods.

Liu, Min; Li, Zhuxia; Zhang, Fengshou

2010-01-01T23:59:59.000Z

257

Nuclear symmetry energy at subnormal densities from measured nuclear masses  

E-Print Network (OSTI)

The symmetry energy coefficients for nuclei with mass number A=20~250 are extracted from more than 2000 measured nuclear masses. With the semi-empirical connection between the symmetry energy coefficients of finite nuclei and the nuclear symmetry energy at reference densities, we investigate the density dependence of symmetry energy of nuclear matter at subnormal densities. The obtained results are compared with those extracted from other methods.

Min Liu; Ning Wang; Zhuxia Li; Fengshou Zhang

2010-11-17T23:59:59.000Z

258

New forms of BRST symmetry in rigid rotor  

E-Print Network (OSTI)

We derive the different forms of BRST symmetry by using the Batalin-Fradkin-Vilkovisky formalism in a rigid rotor. The so called "dual-BRST" symmetry is obtained from usual BRST symmetry by making a canonical transformation in the ghost sector. On the other hand, a canonical transformation in the sector involving Lagrange multiplier and its corresponding momentum leads to a new form of BRST as well as dual-BRST symmetry.

Sumit Kumar Rai; Bhabani Prasad Mandal

2010-01-29T23:59:59.000Z

259

New forms of BRST symmetry in rigid rotor  

E-Print Network (OSTI)

We derive the different forms of BRST symmetry by using the Batalin-Fradkin-Vilkovisky formalism in a rigid rotor. The so called "dual-BRST" symmetry is obtained from usual BRST symmetry by making a canonical transformation in the ghost sector. On the other hand, a canonical transformation in the sector involving Lagrange multiplier and its corresponding momentum leads to a new form of BRST as well as dual-BRST symmetry.

Rai, Sumit Kumar

2010-01-01T23:59:59.000Z

260

Exact solutions with noncommutative symmetries in Einstein and gauge gravity  

Science Conference Proceedings (OSTI)

We present new classes of exact solutions with noncommutative symmetries constructed in vacuum Einstein gravity (in general

Sergiu I. Vacaru

2005-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

SO(4) symmetry in the relativistic hydrogen atom  

E-Print Network (OSTI)

We show that the relativistic hydrogen atom possesses an SO(4) symmetry by introducing a kind of pseudo-spin vector operator. The same SO(4) symmetry is still preserved in the relativistic quantum system in presence of an U(1) monopolar vector potential as well as a nonabelian vector potential. Lamb shift and SO(4) symmetry breaking are also discussed.

Jing-Ling Chen; Dong-Ling Deng; Ming-Guang Hu

2007-11-01T23:59:59.000Z

262

Circular symmetry in the Hitchin system  

E-Print Network (OSTI)

To study circularly symmetric field configurations in the SU(2) Hitchin system an SO(2) symmetry, [J_3, \\phi]=0 and [J_3, A_{\\pm}]=\\pm A_{\\pm}, is imposed on the Higgs scalar \\phi and the gauge fields A_{\\pm} of the system, respectively, where J_3 is a sum of the third components of the orbital angular momenta and the generators of the SU(2). The circular symmetry and the equation \\bar{D}\\phi=0 yield onstant, generally nonzero, vacuum expectation values for {\\rm Tr}(\\phi^{2}). The equation 4F_{z\\bar{z}}=[\\phi, \\phi^{*}] yields a system of differential equations which govern the circularly symmetric field configurations and an exact solution to these equations in a pure gauge form with nontrivial Higgs scalar is obtained.

Masaru Kamata

2013-07-15T23:59:59.000Z

263

Lorentz Transformation from Symmetry of Reference Principle  

E-Print Network (OSTI)

The Lorentz Transformation is traditionally derived requiring the Principle of Relativity and lightspeed universality. While the latter can be relaxed, the Principle of Relativity is seen as core to the transformation. The present letter relaxes both statements to the weaker, Symmetry of Reference Principle. Thus the resulting Lorentz transformation and its consequences (time dilatation, length contraction) are, in turn, effects of how we manage space and time.

M. Dima

2006-01-01T23:59:59.000Z

264

On chiral symmetry in extended nonlinear supersymmetry  

E-Print Network (OSTI)

We study the equations of the motion for Nambu-Goldstone (NG) fermions in the nonlinear representation of supersymmetry (NLSUSY) and show in N-extended NLSUSY that those equations under massless conditions are satisfied, provided the NG fermions are chiral eigenstates. The physical significance of the result is discussed in the context of NLSUSY general relativity through the relations between nonlinear and linear SUSY theories, which gives a new insight into the chiral symmetry for the low energy particle physics.

Kazunari Shima; Motomu Tsuda

2013-11-18T23:59:59.000Z

265

Some Aspects of Fundamental Symmetries and Interactions  

E-Print Network (OSTI)

The known fundamental symmetries and interactions are well described by the Standard Model. Features of this powerful theory, which are described but not deeper explained, are addressed in a variety of speculative models. Experimental tests of the predictions in such approaches can be either through direct observations at the highest possible accelerator energies or through precision measurements in which small deviations from calculated values within the Standard Model are searched for. Antiproton physics renders a number of possibilities to search for new physics.

Klaus P. Jungmann

2005-12-10T23:59:59.000Z

266

Chiral symmetry and lattice gauge theory  

E-Print Network (OSTI)

I review the problem of formulating chiral symmetry in lattice gauge theory. I discuss recent approaches involving an infinite tower of additional heavy states to absorb Fermion doublers. For hadronic physics this provides a natural scheme for taking quark masses to zero without requiring a precise tuning of parameters. A mirror Fermion variation provides a possible way of extending the picture to chirally coupled light Fermions. Talk presented at "Quark Confinement and the Hadron Spectrum," Como, Italy, 20-24 June 1994.

Michael Creutz

1994-10-19T23:59:59.000Z

267

Chiral symmetry and lattice gauge theory  

Science Conference Proceedings (OSTI)

I review the problem of formulating chiral symmetry in lattice gauge theory. I discuss recent approaches involving an infinite tower of additional heavy states to absorb Fermion doublers. For hadronic physics this provides a natural scheme for taking quark masses to zero without requiring a precise tuning of parameters. A mirror Fermion variation provides a possible way of extending the picture to chirally coupled light Fermions.

Creutz, M.

1994-08-01T23:59:59.000Z

268

Lorentz Transformation from Symmetry of Reference Principle  

E-Print Network (OSTI)

The Lorentz Transformation is traditionally derived requiring the Principle of Relativity and light-speed universality. While the latter can be relaxed, the Principle of Relativity is seen as core to the transformation. The present letter relaxes both statements to the weaker, Symmetry of Reference Principle. Thus the resulting Lorentz transformation and its consequences (time dilatation, length contraction) are, in turn, effects of how we manage space and time.

M. Dima

2006-05-24T23:59:59.000Z

269

Chiral symmetry, massive gluons and confinement  

SciTech Connect

It is quite difficult to obtain non-trivial chiral symmetry breaking solutions for the quark gap equation in the presence of dynamically generated gluon masses. An effective confining propagator has recently been proposed by Cornwall in order to solve this problem. We study phenomenological consequences of this approach, showing its compatibility with the experimental data. We argue that this confining propagator should be restricted to a small region of momenta, leading to effective four-fermion interactions at low energy.

Natale, A. A. [Instituto de Fisica Teorica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, Sao Paulo, SP (Brazil)

2013-03-25T23:59:59.000Z

270

Symmetry analysis for anisotropic field theories  

Science Conference Proceedings (OSTI)

The purpose of this paper is to study with the help of Noether's theorem the symmetries of anisotropic actions for arbitrary fields which generally depend on higher order spatial derivatives, and to find the corresponding current densities and the Noether charges. We study in particular scale invariance and consider the cases of higher derivative extensions of the scalar field, electrodynamics and Chern-Simons theory.

Parra, Lorena; Vergara, J. David [Instituto de Ciencias Nucleares, UNAM, Circuito Exterior s/n, Ciudad Universitaria. Delg. Coyoacan. C.P. 04510 Mexico DF (Mexico)

2012-08-24T23:59:59.000Z

271

Towards a Number Theoretic Discrete Hilbert Transform  

E-Print Network (OSTI)

This paper presents an approach for the development of a number theoretic discrete Hilbert transform. The forward transformation has been applied by taking the odd reciprocals that occur in the DHT matrix with respect to a power of 2. Specifically, the expression for a 16-point transform is provided and results of a few representative signals are provided. The inverse transform is the inverse of the forward 16-point matrix. But at this time the inverse transform is not identical to the forward transform and, therefore, our proposed number theoretic transform must be taken as a provisional result.

Kandregula, Renuka

2009-01-01T23:59:59.000Z

272

Bilinear control of discrete spectrum Schrödinger operators  

E-Print Network (OSTI)

The bilinear control problem of the Schr\\"odinger equation $i\\frac{\\partial}{\\partial t}\\psi(t)$ $=(A+u(t) B)\\psi(t)$, where $u(t)$ is the control function, is investigated through topological irreducibility of the set $\\mathfrak{M}=\\{e^{-it (A+u B)}, u\\in \\mathbb{R}, t>0\\}$ of bounded operators. This allows to prove the approximate controllability of such systems when the uncontrolled Hamiltonian $A$ has a simple discrete spectrum and under an appropriate assumption on $B$.

Kais Ammari; Zied Ammari

2010-04-30T23:59:59.000Z

273

Connected Green function approach to ground state symmetry breaking in $?^4_{1+1}$-theory  

E-Print Network (OSTI)

Using the cluster expansions for n-point Green functions we derive a closed set of dynamical equations of motion for connected equal-time Green functions by neglecting all connected functions higher than $4^{th}$ order for the $\\lambda \\Phi^4$-theory in $1+1$ dimensions. We apply the equations to the investigation of spontaneous ground state symmetry breaking, i.e. to the evaluation of the effective potential at temperature $T=0$. Within our momentum space discretization we obtain a second order phase transition (in agreement with the Simon-Griffith theorem) and a critical coupling of $\\lambda_{crit}/4m^2=2.446$ as compared to a first order phase transition and $\\lambda_{crit}/4m^2=2.568$ from the Gaussian effective potential approach.

J. M. Haeuser; W. Cassing; A. Peter; M. H. Thoma

1994-08-23T23:59:59.000Z

274

Yangian symmetries and integrability of the Dirac equation with spin symmetry  

SciTech Connect

We show that a Yangian symmetry, namely, Y(su(2)), exists in the Dirac equation with spin symmetry when the potential term takes a Coulomb form. We construct the generators of Y(su(2)) explicitly and get the energy spectrum of this model from the representation theory for Y(su(2)). We also show that this model is integrable, from RTT relations. - Highlights: Black-Right-Pointing-Pointer The Y(sl(2)) symmetry is found in a model, and the generators of Y(sl(2)) are constructed from the so(4) Lie algebra. Black-Right-Pointing-Pointer The energy spectrum is derived on the basis of the representation theory for Y(sl(2)). Black-Right-Pointing-Pointer The integrability of this model is proved from the RTT relation.

Xu, Lei [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)] [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Jing, Jian, E-mail: jingjian@mail.buct.edu.cn [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China) [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Yuan, Zi-Gang; Kong, Ling-Bao [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)] [Department of Physics and Electronics, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Long, Zheng-Wen [Laboratory for Photoelectric Technology and Applications, Department of Physics, GuiZhou University, GuiYang, 550025 (China)] [Laboratory for Photoelectric Technology and Applications, Department of Physics, GuiZhou University, GuiYang, 550025 (China)

2013-02-15T23:59:59.000Z

275

A Family of Discrete Magnetically Switchable Nanoballs  

Science Conference Proceedings (OSTI)

The thermal and light-induced magnetic properties of a family of discrete magnetically switchable 'nanoball' species (3 nm in diameter) is reported. The self-assembly of these materials is accomplished by the use of the metallo building block, [Cu([Tp{sup 4-py}])(NCCH{sub 3})] ([Tp{sup 4-py}]=tris-[3-(4{prime}-pyridyl)pyrazol-1-yl]hydroborate), combined with a [Fe(NCX){sub 2}] (X = S, Se and BH{sub 3}) species. We previously showed that the thiocyanate analogue (Fe(NCS)-nano) undergoes a thermal and light-induced spin crossover (SCO) - the largest such discrete SCO material reported. Now included in this family are the Se and BH{sub 3} analogues, Fe(NCSe)-nano and Fe(NCBH{sub 3})-nano, which show increased thermal transition temperatures (T{sub 1/2} = 124 K, 162 and 173 K). This variation in transition temperature over the series S < Se < BH{sub 3} results in diverse photomagnetic properties, such that the light-induced excited spin state trapping (LIESST) effect is exhibited to varying degrees and at different temperatures by the S, Se and BH{sub 3} analogues.

Duriska, Martin B.; Neville, Suzanne M.; Moubaraki, Boujemaa; Murray, Keith S.; Balde, Chérif; Létard, Jean-François; Kepert, Cameron J.; Batten, Stuart R. (Sydney); (Monash); (CNRS-LSP)

2012-08-20T23:59:59.000Z

276

Double-Scaling Limit of a Broken Symmetry Quantum Field Theory  

E-Print Network (OSTI)

The Ising limit of a conventional Hermitian parity-symmetric scalar quantum field theory is a correlated limit in which two bare Lagrangian parameters, the coupling constant $g$ and the {\\it negative} mass squared $-m^2$, both approach infinity with the ratio $-m^2/g=\\alpha>0$ held fixed. In this limit the renormalized mass of the asymptotic theory is finite. Moreover, the limiting theory exhibits universal properties. For a non-Hermitian $\\cal PT$-symmetric Lagrangian lacking parity symmetry, whose interaction term has the form $-g(i\\phi)^N/N$, the renormalized mass diverges in this correlated limit. Nevertheless, the asymptotic theory still has interesting properties. For example, the one-point Green's function approaches the value $-i\\alpha^{1/(N-2)}$ independently of the space-time dimension $D$ for $D<2$. Moreover, while the Ising limit of a parity-symmetric quantum field theory is dominated by a dilute instanton gas, the corresponding correlated limit of a $\\cal PT$-symmetric quantum field theory wit...

Bender, C M; Jones, H F; Meisinger, P N; Bender, Carl M.; Boettcher, Stefan; Meisinger, Peter N.

2001-01-01T23:59:59.000Z

277

Majorana Neutrino Masses from Flavor Symmetries  

E-Print Network (OSTI)

In this talk we discuss the implications of the Minimal Supersymmetric Standard Model augmented by a single U(1) anomalous family symmetry for neutrino masses and mixing angles. The left-handed neutrino states are provided with Majorana masses through a dimension-five operator in the absence of right handed neutrino components. Assuming symmetric lepton mass matrices, the model predicts inverse hierarchical neutrino mass spectrum, theta_13=0 and large mixing while at the same time it provides acceptable mass matrices for the charged fermions.

A. Psallidas

2005-05-11T23:59:59.000Z

278

Adaptive discrete cosine transform for feedback active noise control  

Science Conference Proceedings (OSTI)

The theory and performance of adaptive discrete cosine transform filters for feedback active noise control (ANC) is examined. The discrete cosine transform filter is a realization of an FIR filter as the cascade of an all-zero FIR filter with a bank ... Keywords: FIR filter, IIR digital resonators bank, active noise control, adaptive discrete cosine transform filters, adaptive filter, all-zero FIR filter, discrete cosine transform filter, feedback active noise control, filter-X LMS implementation, frequency, magnitude coefficient, phase coefficient, single error microphone, single loudspeaker, transfer function

G. Coutu; M. Dignan

1995-10-01T23:59:59.000Z

279

Discrete Quantum Spectrum of Observable Correlations from Inflation  

E-Print Network (OSTI)

The decoherence of quantum fluctuations into classical perturbations during inflation is discussed. A simple quantum mechanical argument, using a spatial particle wavefunction rather than a field description, shows that observable correlations from inflation must have a discrete spectrum, since they originate and freeze into the metric within a compact region. The number of discrete modes is estimated using a holographic bound on the number of degrees of freedom. The discreteness may be detectable in some models; for example, if there is a fundamental universal frequency spectrum, the inflationary gravitational wave background may be resolvable into discrete emission lines.

Craig J. Hogan

2005-04-16T23:59:59.000Z

280

The Discrete Variable Method for the Time Dependent and ...  

Science Conference Proceedings (OSTI)

... Abstract: The discrete variable representation (DVR) has been found to be a very effective approach for the numerical solution of the Schroedinger ...

2011-01-12T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Discrete Element Method Applied to the Vibration Process of Coke ...  

Science Conference Proceedings (OSTI)

In the present work, effects of particle shape and size distribution on vibrated bulk density (VBD) of dry coke samples have been investigated. Discrete Element ...

282

Horizontal Symmetries $\\Delta(150)$ and $\\Delta(600)$  

E-Print Network (OSTI)

Using group theory of mixing to examine all finite subgroups of SU(3) with an order less than 512, we found recently that only the group $\\Delta(150)$ can give rise to a correct reactor angle $\\th_{13}$ of neutrino mixing without any free parameter. It predicts $\\sin^22\\th_{13}=0.11$ and a sub-maximal atmospheric angle with $\\sin^22\\th_{23}=0.94$, in good agreement with experiment. The solar angle $\\th_{12}$, the CP phase $\\d$, and the neutrino masses $m_i$ are left as free parameters. In this article we provide more details of this case, discuss possible gain and loss by introducing right-handed symmetries, and/or valons to construct dynamical models. A simple model is discussed where the solar angle agrees with experiment, and all its mixing parameters can be obtained from the group $\\Delta(600)$ by symmetry alone. The promotion of $\\Delta(150)$ to $\\Delta(600)$ is on the one hand analogous to the promotion of $S_3$ to $S_4$ in the presence of tribimaximal mixing, and on the other hand similar to the extens...

Lam, C S

2013-01-01T23:59:59.000Z

283

Variational estimates using a discrete variable representation  

SciTech Connect

The advantage of using a discrete variable representation (DVR) is that the Hamiltonian of two interacting particles can be constructed in a very simple form. However, the DVR Hamiltonian is approximate and, as a consequence, the results cannot be considered as variational ones. We will show that the variational character of the results can be restored by performing a reduced number of integrals. In practice, for a variational description of the lowest n bound states only n(n+1)/2 integrals are necessary whereas D(D+1)/2 integrals are enough for the scattering states (D is the dimension of the S matrix). Applications of the method to the study of dimers of He, Ne and Ar, for both bound and scattering states, are presented.

Lombardi, M.; Barletta, P.; Kievsky, A. [Istituto Nazionale di Fisica Nucleare, Via Buonarroti 2, 56100 Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, 56100 Pisa (Italy)

2004-09-01T23:59:59.000Z

284

Decreasing Isosurface Complexity Via Discrete Fitting  

E-Print Network (OSTI)

Since the introduction of techniques for isosurface extraction from volumetric datasets, one of the hardest problems has been to reduce the number of generated triangles (or polygons). This paper presents an algorithm that considerably reduces the number of triangles generated by a Marching Cubes algorithm, while presenting very close or shorter running times. The algorithm first assumes discretization of the dataset space and replaces cell edge interpolation by midpoint selection. Under these assumptions the extracted surfaces are composed of polygons lying within a finite number of incidences, thus allowing simple merging of the output facets into large coplanar triangular facets. Lastly, the vertices which survived the decimation process are located on their exact positions and normals are computed. An experimental evaluation of the proposed approach on datasets relevant to biomedical imaging and chemical modeling is reported. 2000 Elsevier Science B.V. All rights reserved. Keywords: Volume rendering; Isosurface extraction; Marching cubes; Surface simplification 1.

Claudio Montani; Riccardo Scateni; Roberto Scopigno

2000-01-01T23:59:59.000Z

285

Probing the symmetry energy from the nuclear isoscaling  

E-Print Network (OSTI)

Using different parameterizations of the nuclear mass formula, we study the sensitivity of the isoscaling parameters to the mass formula employed in grand-canonical calculations. Previous works on isoscaling have suggested that the symmetry energy implied in such calculations is anomalously smaller than that suggested by fits to nuclear masses. We show that surface corrections to the symmetry energy naturally broadens the isotopic distribution thus allowing for values of the symmetry energy which more closely match those obtained from nuclear masses.

Souza, S R; Donangelo, R; Lynch, W G; Steiner, A W

2008-01-01T23:59:59.000Z

286

Page 1 NEW SYMMETRIES FROM OLD: EXPLOITING LIE ...  

E-Print Network (OSTI)

looking out for me. Funding for my stay in Canada was partially provided by a UBC research assistantship ...... The importance of symmetries has led to the.

287

NBS Monograph 115: 2. Symmetry prop. rotational energy ...  

Science Conference Proceedings (OSTI)

... The rotational energy levels of homonuclear diatomic ... in the usual group theory tables [6] (pp. ... symmetry operations on nuclear displacement vectors ...

288

Symmetry energy at subnuclear densities deduced from nuclear masses  

E-Print Network (OSTI)

We examine how nuclear masses are related to the density dependence of the symmetry energy. Using a macroscopic nuclear model we calculate nuclear masses in a way dependent on the equation of state of asymmetric nuclear matter. We find by comparison with empirical two-proton separation energies that a smaller symmetry energy at subnuclear densities, corresponding to a larger density symmetry coefficient L, is favored. This tendency, which is clearly seen for nuclei that are neutron-rich, nondeformed, and light, can be understood from the property of the surface symmetry energy in a compressible liquid-drop picture.

Oyamatsu, Kazuhiro

2010-01-01T23:59:59.000Z

289

Symmetry energy at subnuclear densities deduced from nuclear masses  

E-Print Network (OSTI)

We examine how nuclear masses are related to the density dependence of the symmetry energy. Using a macroscopic nuclear model we calculate nuclear masses in a way dependent on the equation of state of asymmetric nuclear matter. We find by comparison with empirical two-proton separation energies that a smaller symmetry energy at subnuclear densities, corresponding to a larger density symmetry coefficient L, is favored. This tendency, which is clearly seen for nuclei that are neutron-rich, nondeformed, and light, can be understood from the property of the surface symmetry energy in a compressible liquid-drop picture.

Kazuhiro Oyamatsu; Kei Iida

2010-02-23T23:59:59.000Z

290

Hidden Lorentz symmetry of the Horava - Lifshitz gravity  

E-Print Network (OSTI)

In this letter it is shown that the Horava-Lifshitz gravity theory admits Lorentz symmetry preserving preferred global time foliation of the spacetime.

Jakub Rembielinski

2013-09-03T23:59:59.000Z

291

Causal sets and conservation laws in tests of Lorentz symmetry  

E-Print Network (OSTI)

Many of the most important astrophysical tests of Lorentz symmetry also assume that energy-momentum of the observed particles is exactly conserved. In the causal set approach to quantum gravity a particular kind of Lorentz symmetry holds but energy-momentum conservation may be violated. We show that incorrectly assuming exact conservation can give rise to a spurious signal of Lorentz symmetry violation for a causal set. However, the size of this spurious signal is much smaller than can be currently detected and hence astrophysical Lorentz symmetry tests as currently performed are safe from causal set induced violations of energy-momentum conservation.

David Mattingly

2007-09-04T23:59:59.000Z

292

The discrete fractional random cosine and sine transforms  

E-Print Network (OSTI)

Based on the discrete fractional random transform (DFRNT), we present the discrete fractional random cosine and sine transforms (DFRNCT and DFRNST). We demonstrate that the DFRNCT and DFRNST can be regarded as special kinds of DFRNT and thus their mathematical properties are inherited from the DFRNT. Numeral results of DFRNCT and DFRNST for one and two dimensional functions have been given.

Zhengjun Liu; Qing Guo; Shutian Liu

2006-05-22T23:59:59.000Z

293

Discrete Wavelet Transform: Architectures, Design and Performance Issues  

Science Conference Proceedings (OSTI)

Due to the demand for real time wavelet processors in applications such as video compression [1], Internet communications compression [2], object recognition [3], and numerical analysis, many architectures for the Discrete Wavelet Transform (DWT) systems ... Keywords: computer architecture, digital filters, digital signal processors, discrete transforms, wavelet transforms

Michael Weeks; Magdy Bayoumi

2003-09-01T23:59:59.000Z

294

Mixed-hybrid discretization methods for the P1 equations  

Science Conference Proceedings (OSTI)

We consider mixed-hybrid discretization methods for the linear Boltzmann transport equation which is extensively used in computational neutron transport. Mixed-hybrid methods combine attractive features of both mixed and hybrid methods, namely the simultaneous ... Keywords: 02.60.Cb, 02.70.Dh, 65N12, 65N30, Linear Boltzmann transport equation, Mixed-hybrid discretization methods, P1 approximation

S. Van Criekingen; R. Beauwens

2007-02-01T23:59:59.000Z

295

Efficient optimal design of uncertain discrete time dynamical systems  

Science Conference Proceedings (OSTI)

In this paper we consider the problem of optimal design of an uncertain discrete time nonlinear dynamical system. The problem is formulated using an a-posterori design criterion, which can account for uncertainties generated by the dynamics of the system ... Keywords: Discrete time dynamical systems, Optimal design, Randomized algorithms, Uncertain parameters

Chenxi Lin; Thordur Runolfsson

2012-10-01T23:59:59.000Z

296

Discrete element modeling of machine-manure interactions  

Science Conference Proceedings (OSTI)

The discrete element method (DEM) was applied to the study of the machine-product interactions occurring in manure handling and land application equipment. Two types of conveying systems (scraper and 4-auger system) were modeled along with a hopper and ... Keywords: Conveying systems, Discrete element method (DEM), Flow rate, Manure, Numerical modeling, Specific energy, Spreader

H. Landry; C. Laguë; M. Roberge

2006-06-01T23:59:59.000Z

297

Two Classes of Elliptic Discrete Fourier Transforms: Properties and Examples  

Science Conference Proceedings (OSTI)

This paper analyzes the block structure of the matrix of the N-point discrete Fourier transform (DFT) in the real space R 2N . Each block of this matrix corresponds to the Givens transformation, or elementary rotation ... Keywords: Discrete Fourier transform, Fourier analysis, Signal and image processing

Artyom M. Grigoryan

2011-03-01T23:59:59.000Z

298

Partially blind threshold signatures based on discrete logarithm  

Science Conference Proceedings (OSTI)

In this paper, we propose a group-oriented partially blind (t, n) threshold signature scheme based on the discrete logarithm problem. By the scheme, any t out of n signers in a group can represent the group to sign partially blind threshold signatures, ... Keywords: Discrete logarithm, E-cash systems, Partially blind signatures, Privacy and security, Secure, Secure voting schemes, Threshold signatures

W. -S. Juang; C. -L. Lei

1999-01-01T23:59:59.000Z

299

Pricing Discretely Monitored Asian Options by Maturity Randomization  

Science Conference Proceedings (OSTI)

We present a new methodology based on maturity randomization to price discretely monitored arithmetic Asian options when the underlying asset evolves according to a generic Lévy process. Our randomization technique considers the option expiry ... Keywords: Asian option, Lévy process, discrete monitoring, fast Fourier transform, integral equation, option pricing, quadrature formula

Gianluca Fusai; Daniele Marazzina; Marina Marena

2011-01-01T23:59:59.000Z

300

On the solutions of generalized discrete Poisson equation  

E-Print Network (OSTI)

The set of common numerical and analytical problems is introduced in the form of the generalized multidimensional discrete Poisson equation. It is shown that its solutions with square-summable discrete derivatives are unique up to a constant. The proof uses the Fourier transform as the main tool. The necessary condition for the existence of the solution is provided.

Roman Werpachowski

2007-06-19T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Holst action and Dynamical Electroweak symmetry breaking  

E-Print Network (OSTI)

We consider Poincare gravity coupled in a nonminimal way to spinors. The gravitational action is considered that contains both Palatini and Holst terms. Due to torsion the effective four - fermion interactions appear that may lead to the left - right asymmetry and the condensation of fermions. When the mass parameter entering the mentioned terms of the gravitational action is at a Tev scale the given construction may provide the dynamical Electroweak symmetry breaking. This is achieved via an arrangement of all Standard Model fermions in the left - handed Dirac spinors while the right - handed spinors are reserved for the technifermions. Due to the gravitational action the technifermions are condensed and, therefore, cause the appearance of gauge boson masses.

M. A. Zubkov

2010-04-08T23:59:59.000Z

302

Lifshitz field theories with SDiff symmetries  

E-Print Network (OSTI)

We consider Lifshitz field theories with a dynamical critical exponent z equal to the dimension of space d and with a large group of base space symmetries, concretely space coordinate transformations with unit determinant ("Special Diffeomorphisms"). The field configurations of the theories considered may have the topology of skyrmions, vortices or monopoles, although we focus our detailed investigations on skyrmions. The resulting Lifshitz field theories have a BPS bound and exact soliton solutions saturating the bound, as well as time-dependent topological Q-ball solutions. Finally, we investigate the U(1) gauged versions of the Lifshitz field theories coupled to a Chern-Simons gauge field, where the BPS bound and soliton solutions saturating the bound continue to exist.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2012-01-01T23:59:59.000Z

303

Dynamical Local Chirality and Chiral Symmetry Breaking  

E-Print Network (OSTI)

We present some of the reasoning and results substantiating the notion that spontaneous chiral symmetry breaking (SChSB) in QCD is encoded in local chiral properties of Dirac eigenmodes. Such association is possible when viewing chirality as a dynamical effect, measured with respect to the benchmark of statistically independent left-right components. Following this rationale leads to describing local chiral behavior by a taylor-made correlation, namely the recently introduced correlation coefficient of polarization C_A. In this language, correlated modes (C_A>0) show dynamical preference for local chirality while anti-correlated modes (C_Aenergy correlation (chirality) over anti-correlation (anti-chirality) of Dirac sea. The spectral range of local chirality, chiral polarization scale Lambda_ch, is a dynamically generated scale in the theory associated with SChSB. One implication of these findings is briefly dis...

Alexandru, Andrei

2013-01-01T23:59:59.000Z

304

Modified Gravity via Spontaneous Symmetry Breaking  

E-Print Network (OSTI)

We construct effective field theories in which gravity is modified via spontaneous breaking of local Lorentz invariance. This is a gravitational analogue of the Higgs mechanism. These theories possess additional graviton modes and modified dispersion relations. They are manifestly well-behaved in the UV and free of discontinuities of the van Dam-Veltman-Zakharov type, ensuring compatibility with standard tests of gravity. They may have important phenomenological effects on large distance scales, offering an alternative to dark energy. For the case in which the symmetry is broken by a vector field with the wrong sign mass term, we identify four massless graviton modes (all with positive-definite norm for a suitable choice of a parameter) and show the absence of the discontinuity.

B. M. Gripaios

2004-08-17T23:59:59.000Z

305

Density-metric unimodular gravity: Vacuum maximal symmetry  

SciTech Connect

We have investigated the vacuum maximally symmetric solutions of recently proposed density-metric unimodular gravity theory. The results are widely different from inflationary scenario. The exponential dependence on time in deSitter space is substituted by a power law. Open space-times with non-zero cosmological constant are excluded.

Abbassi, A.H., E-mail: ahabbasi@modares.ac.ir [Department of Physics, School of Sciences, Tarbiat Modares University, P.O. Box 14155-4838, Tehran (Iran, Islamic Republic of); Abbassi, A.M., E-mail: amabasi@khayam.ut.ac.ir [Department of Physics, University of Tehran, P.O. Box 14155-6455, Tehran (Iran, Islamic Republic of)

2011-05-15T23:59:59.000Z

306

Symmetry in CSP solutions Nicoleta Neagu and Boi Faltings  

E-Print Network (OSTI)

Symmetry in CSP solutions Nicoleta Neagu and Boi Faltings Artificial Intelligence Laboratory (LIA for finding symmetric solutions of in a CSP. This method is using local symmetries of the CSP structure and research upon searching CSP solutions but few of them watch the relations between CSP solutions. In certain

Flener, Pierre

307

Pseudo-Symmetry and Majorana Operators in pf-Shell  

SciTech Connect

The Majorana operator of the pseudo ds-shell preserves the SU-tilde(4) symmetry, and in a unified manner it reproduces reasonably well the ground state energies of the nine nuclei in this shell. The study of {beta} decay in the same shell provides further support for the SU-tilde(4) symmetry.

Valencia, J. P.; Wu, H. C. [Instituto de Fisica, Universidad de Antioquia, Medellin (Colombia)

2007-10-26T23:59:59.000Z

308

Non-Noether symmetries in Hamiltonian Dynamical Systems  

E-Print Network (OSTI)

We discuss geometric properties of non-Noether symmetries and their possible applications in integrable Hamiltonian systems. Correspondence between non-Noether symmetries and conservation laws is revisited. It is shown that in regular Hamiltonian systems such a symmetries canonically lead to a Lax pairs on the algebra of linear operators on cotangent bundle over the phase space. Relationship between the non-Noether symmetries and other wide spread geometric methods of generating conservation laws such as bi-Hamiltonian formalism, bidifferential calculi and Frolicher-Nijenhuis geometry is considered. It is proved that the integrals of motion associated with the continuous non-Noether symmetry are in involution whenever the generator of the symmetry satisfies a certain Yang-Baxter type equation. Action of one-parameter group of symmetry on algebra of integrals of motion is studied and involutivity of group orbits is discussed. Hidden non-Noether symmetries of Toda chain, nonlinear Schrodinger equation, Korteweg-de Vries equations, Benney system, nonlinear water wave equations and Broer-Kaup system are revealed and discussed.

George Chavchanidze

2004-05-03T23:59:59.000Z

309

Self-consistent Models of Strong Interaction with Chiral Symmetry  

DOE R&D Accomplishments (OSTI)

Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)

Nambu, Y.; Pascual, P.

1963-04-00T23:59:59.000Z

310

On Symmetry and Multiple-View Geometry: Structure, Pose, and Calibration from a Single Image  

Science Conference Proceedings (OSTI)

In this paper, we provide a principled explanation of how knowledge in global 3-D structural invariants, typically captured by a group action on a symmetric structure, can dramatically facilitate the task of reconstructing a 3-D scene from one or more ... Keywords: multiple-view geometry, reflective symmetry, rotational symmetry, structure from symmetry, symmetry group, translational symmetry

Wei Hong; Allen Yang Yang; Kun Huang; Yi Ma

2004-12-01T23:59:59.000Z

311

Patterns of Spontaneous Chiral Symmetry Breaking in Vectorlike Gauge Theories  

E-Print Network (OSTI)

It has been conjectured that spontaneous chiral symmetry breaking in strongly coupled vectorlike gauge theories falls into only three different classes, depending on the gauge group and the representations carried by the fermions. We test this proposal by studying SU(2), SU(3) and SU(4) lattice gauge theories with staggered fermions in different irreducible representations. Staggered fermions away from the continuum limit should, for all complex representations, still belong to the continuum class of spontaneous symmetry breaking. But for all real and pseudo-real representations we show that staggered fermions should belong to incorrect symmetry breaking classes away from the continuum, thus generalizing previous results. As an unambiguous signal for whether chiral symmetry breaks, and which breaking pattern it follows, we look at the smallest Dirac eigenvalue distributions. We find that the patterns of symmetry breaking are precisely those conjectured.

P. H. Damgaard; U. M. Heller; R. Niclasen; B. Svetitsky

2008-01-01T23:59:59.000Z

312

Further study of an approach to the unification of gauge symmetries in theories with dynamical symmetry breaking  

Science Conference Proceedings (OSTI)

We extend to larger unification groups an earlier study exploring the possibility of unification of gauge symmetries in theories with dynamical symmetry breaking. Based on our results, we comment on the outlook for models that seek to achieve this type of unification.

Chen Ning; Shrock, Robert [C.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, New York 11794 (United States)

2008-08-01T23:59:59.000Z

313

Multidimensional electron-photon transport with standard discrete ordinates codes  

Science Conference Proceedings (OSTI)

A method is described for generating electron cross sections that are compatible with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled electron-photon transport capability is needed for many applications, including the modeling of the response of electronics components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional electronphoton transport problems.

Drumm, C.R.

1995-12-31T23:59:59.000Z

314

The Transmission Property of the Discrete Heisenberg Ferromagnetic Spin Chain  

E-Print Network (OSTI)

We present a mechanism for displaying the transmission property of the discrete Heisenberg ferromagnetic spin chain (DHF) via a geometric approach. By the aid of a discrete nonlinear Schr\\"odinger-like equation which is the discrete gauge equivalent to the DHF, we show that the determination of transmitting coefficients in the transmission problem is always bistable. Thus a definite algorithm and general stochastic algorithms are presented. A new invariant periodic phenomenon of the non-transmitting behavior for the DHF, with a large probability, is revealed by an adoption of various stochastic algorithms.

Qing Ding; Wei Lin

2008-01-14T23:59:59.000Z

315

The role of gauge symmetry in spintronics  

SciTech Connect

In this work we employ a field theoretical approach to explain the nature of the non-conserved spin current in spintronics. In particular, we consider the usual U(1) gauge theory for the electromagnetism at classical level in order to obtain the broken continuity equation involving the spin current and spin-transfer torque. Inspired by the recent work of A. Vernes, B. L. Gyorffy and P. Weinberger where they obtain such an equation in terms of relativistic quantum mechanics, we formalize their result in terms of the well known currents of field theory such as the Bargmann-Wigner current and the chiral current. Thus, an interpretation of spintronics is provided in terms of Noether currents (conserved or not) and symmetries of the electromagnetism. In fact, the main result of the present work is that the non-conservation of the spin current is associated with the gauge invariance of physical observables where the breaking term is proportional to the chiral current. Moreover, we generalize their result by including the electromagnetic field as a dynamical field instead of an external one.

Sobreiro, R.F., E-mail: sobreiro@if.uff.br [UFF - Universidade Federal Fluminense, Instituto de Fisica, Campus da Praia Vermelha, Av. General Milton Tavares de Souza s/n, 24210-346, Niteroi, RJ (Brazil); Vasquez Otoya, V.J. [IFSEMG - Instituto Federal de Educacao, Ciencia e Tecnologia do Sudeste de Minas Gerais, Rua Bernardo Mascarenhas 1283, 36080-001, Juiz de Fora, MG (Brazil)

2011-12-15T23:59:59.000Z

316

Radiation Reaction, Renormalization and Poincaré Symmetry  

E-Print Network (OSTI)

We consider the self-action problem in classical electrodynamics of a massive point-like charge, as well as of a massless one. A consistent regularization procedure is proposed, which exploits the symmetry properties of the theory. The radiation reaction forces in both 4D and 6D are derived. It is demonstrated that the Poincar\\'e-invariant six-dimensional electrodynamics of the massive charge is renormalizable theory. Unlike the massive case, the rates of radiated energy-momentum tend to infinity whenever the source is accelerated. The external electromagnetic fields, which do not change the velocity of the particle, admit only its presence within the interaction area. The effective equation of motion is the equation for eigenvalues and eigenvectors of the electromagnetic tensor. The interference part of energy-momentum radiated by two massive point charges arbitrarily moving in flat spacetime is evaluated. It is shown that the sum of work done by Lorentz forces of charges acting on one another exhausts the effect of combination of outgoing electromagnetic waves generated by the charges.

Yurij Yaremko

2005-11-25T23:59:59.000Z

317

Sensitivity of nuclear stopping towards density dependent symmetry energy  

E-Print Network (OSTI)

The effect of density dependent symmetry energy on nuclear-stopping is studied using isospin-dependent quantum molecular dynamics model(IQMD). We have used the reduced isospin-dependent cross-section with soft(S) equation of state for the systems having different isostopic content, to explore the various aspects of nuclear stopping. The aim is to pin down the nature of the nuclear stopping with density dependent symmetry energy. Nuclear stopping is found to be sensitive towards the various forms of the density dependent symmetry energy. The nuclear stopping tends to decrease for the stiffer equation of state (EOS), i.e. larger values of gamma.

Karan Singh Vinayak; Suneel Kumar

2011-10-11T23:59:59.000Z

318

Imprints of Nuclear Symmetry Energy on Properties of Neutron Stars  

E-Print Network (OSTI)

Significant progress has been made in recent years in constraining the density dependence of nuclear symmetry energy using terrestrial nuclear laboratory data. Around and below the nuclear matter saturation density, the experimental constraints start to merge in a relatively narrow region. At supra-saturation densities, there are, however, still large uncertainties. After summarizing the latest experimental constraints on the density dependence of nuclear symmetry energy, we highlight a few recent studies examining imprints of nuclear symmetry energy on the binding energy, energy release during hadron-quark phase transitions as well as the $w$-mode frequency and damping time of gravitational wave emission of neutron stars.

Li, Bao-An; Gearheart, Michael; Hooker, Joshua; Ko, Che Ming; Krastev, Plamen G; Lin, Wei-Kang; Newton, William G; Wen, De-Hua; Xu, Chang; Xu, Jun

2011-01-01T23:59:59.000Z

319

Sensitivity of nuclear stopping towards density dependent symmetry energy  

E-Print Network (OSTI)

The effect of density dependent symmetry energy on nuclear-stopping is studied using isospin-dependent quantum molecular dynamics model(IQMD). We have used the reduced isospin-dependent cross-section with soft(S) equation of state for the systems having different isostopic content, to explore the various aspects of nuclear stopping. The aim is to pin down the nature of the nuclear stopping with density dependent symmetry energy. Nuclear stopping is found to be sensitive towards the various forms of the density dependent symmetry energy. The nuclear stopping tends to decrease for the stiffer equation of state (EOS), i.e. larger values of gamma.

Vinayak, Karan Singh

2011-01-01T23:59:59.000Z

320

Excitation energy dependence of symmetry energy of finite nuclei  

E-Print Network (OSTI)

A finite range density and momentum dependent effective interaction is used to calculate the density and temperature dependence of the symmetry energy coefficient Csym(rho,T) of infinite nuclear matter. This symmetry energy is then used in the local density approximation to evaluate the excitation energy dependence of the symmetry energy coefficient of finite nuclei in a microcanonical formulation that accounts for thermal and expansion effects. The results are in good harmony with the recently reported experimental data from energetic nucleus-nucleus collisions.

S. K. Samaddar; J. N. De; X. Vinas; M. Centelles

2007-06-22T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Grand Symmetry, Spectral Action, and the Higgs mass  

E-Print Network (OSTI)

In the context of the spectral action and the noncommutative geometry approach to the standard model, we build a model based on a larger symmetry. The latter satisfies all the requirements to have a noncommutative manifold, and mixes gauge and spin degrees of freedom without introducing extra fermions. With this "grand symmetry" it is natural to have the scalar field necessary to obtain the Higgs mass in the vicinity of 126 GeV. Requiring the noncommutative space to be an almost commutative geometry (i.e. the product of manifold by a finite dimensional internal space) gives conditions for the breaking of this grand symmetry to the standard model.

Agostino Devastato; Fedele Lizzi; Pierre Martinetti

2013-04-01T23:59:59.000Z

322

Constrained Interpolation Remap of Discrete Divergence Free Fields  

National Nuclear Security Administration (NNSA)

Shashkov M. 1 Shashkov M. 1 Constrained Interpolation Remap of Discrete Divergence Free Fields P.B. Bochev, * M. Shashkov † * Sandia National Laboratories, Org. 9214, Albuquerque, NM 87185 † Los Alamos National Laboratory, T-7, Los Alamos, NM 87545 We present a constrained interpolation (CI) algorithm for remapping of divergence free vector fields encoded as 2-cochains on a two-dimensional cell complex. On contractible domains discrete divergence free fields are 2-coboundaries and so they have potentials represented by 1-cochains. The algorithm takes advantage of this fact by using the discrete potential to effect the remapping of the divergence free field. The discrete potential is reconstructed and interpolated to the new cell complex. Application of

323

Applications of Algebraic Topology to Compatible Spatial Discretizations  

National Nuclear Security Administration (NNSA)

Hyman J. 1 Hyman J. 1 Applications of Algebraic Topology to Compatible Spatial Discretizations P. B. Bochev, * J. M. Hyman † * Sandia National Laboratories, Org. 9214, Albuquerque, NM 87185 † Los Alamos National Laboratory, T-7, Los Alamos, NM 87545 We provide a common framework for compatible discretizations using algebraic topology to guide our analysis. The main concept is the natural inner product on cochains, which induces a combinatorial Hodge theory. The framework comprises of mutually consistent operations of differentiation and integration, has a discrete Stokes theorem, and preserves the invariants of the DeRham cohomology groups. The latter allows for an elementary calculation of the kernel of the discrete Laplacian. Our framework provides an abstraction that includes examples

324

Diabatically Driven Discrete Propagation of Surface Fronts: A Numerical Analysis  

Science Conference Proceedings (OSTI)

Discrete frontal propagation has been identified as a process whereby a surface front discontinuously moves forward, without evidence of frontal passage across a mesoscale region. Numerical simulations are employed to examine the upper-level ...

George H. Bryan; J. Michael Fritsch

2000-07-01T23:59:59.000Z

325

A discrete model of energy-conserved wavefunction collapse  

E-Print Network (OSTI)

Energy nonconservation is a serious problem of dynamical collapse theories. In this paper, we propose a discrete model of energy-conserved wavefunction collapse. It is shown that the model is consistent with existing experiments and our macroscopic experience.

Gao, Shan

2013-01-01T23:59:59.000Z

326

Discrete Feature Approach for Heterogeneous Reservoir Production Enhancement  

Science Conference Proceedings (OSTI)

The report presents summaries of technology development for discrete feature modeling in support of the improved oil recovery (IOR) for heterogeneous reservoirs. In addition, the report describes the demonstration of these technologies at project study sites.

Dershowitz, William S.; Curran, Brendan; Einstein, Herbert; LaPointe, Paul; Shuttle, Dawn; Klise, Kate

2002-07-26T23:59:59.000Z

327

The cost of conservative synchronization in parallel discrete event simulations  

Science Conference Proceedings (OSTI)

This paper analytically studies the performance of a synchronous conservative parallel discrete-event simulation protocol. The class of models considered simulates activity in a physical domain, and possesses a limited ability to predict future behavior. ... Keywords: conservative synchronization

David M. Nicol

1993-04-01T23:59:59.000Z

328

Discrete multi-material interface reconstruction for volume fraction data  

Science Conference Proceedings (OSTI)

Material interface reconstruction (MIR) is the task of constructing boundary interfaces between regions of homogeneous material, while satisfying volume constraints, over a structured or unstructured spatial domain. In this paper, we present a discrete ...

J. C. Anderson; C. Garth; M. A. Duchaineau; K. I. Joy

2008-05-01T23:59:59.000Z

329

RFIDSim : a discrete event simulator for Radio Frequency Identification systems  

E-Print Network (OSTI)

This thesis presents RFIDSim, a discrete event process-oriented simulator designed to model Radio Frequency Identification (RFID) communication. The simulator focuses on the discovery and identification process of passive ...

Yu, Kenneth Kwan-Wai, 1979-

2003-01-01T23:59:59.000Z

330

AC transmission system planning choosing lines from a discrete set  

E-Print Network (OSTI)

Transmission system planning (TSP) is a difficult nonlinear optimization problem involving non-convex quadratic terms, as well as discrete variables. We extend prior results for linear relaxations, drawing on a preliminary ...

Gilbertson, Eric W.

2013-04-24T23:59:59.000Z

331

Rapid modeling of field maintenance using discrete event simulation  

Science Conference Proceedings (OSTI)

Discrete event simulation has been applied to a wide range of applications areas due to its ability to represent stochastic systems over time. Maintenance, particularly field maintenance, is complex due to the interaction of different sub-systems of ...

Abdullah A. Alabdulkarim; Peter D. Ball; Ashutosh Tiwari

2011-12-01T23:59:59.000Z

332

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

333

Discrete Propagation in Numerically Simulated Nocturnal Squall Lines  

Science Conference Proceedings (OSTI)

Simulations of a typical midlatitude squall line were used to investigate a mechanism for discrete propagation, defined as convective initiation ahead of an existing squall line leading to a faster propagation speed for the storm complex. Radar ...

Robert G. Fovell; Gretchen L. Mullendore; Seung-Hee Kim

2006-12-01T23:59:59.000Z

334

Continuous-Time Distributed Observers with Discrete Communication  

E-Print Network (OSTI)

computation. Distributed estimation problems arise, for instance, in sensor networks, electric power grids data, and rely upon distributed mechanisms to merge local computations, such as intermediate dataContinuous-Time Distributed Observers with Discrete Communication Florian D¨orfler, Fabio

Bullo, Francesco

335

Lossless compression using the adaptive discrete cosine transform  

Science Conference Proceedings (OSTI)

This paper describes a technique using the adaptive discrete cosine transform for lossless waveform data compression. The technique is a variation on a two-stage lossless method that was developed by one of the authors. The earlier work employed an adaptive ... Keywords: ADPCM scheme, adaptive differential pulse code modulation-type, adaptive discrete cosine transform, data compression, encoding, integer residual sequence, lossless successive difference operation, lossless waveform data compression, storage, transmission, two-stage lossless method

L. Gerhardt; M. Fargues; G. Coutu

1995-10-01T23:59:59.000Z

336

Symmetry Breaking of H2 Dissociation by a Single Photon  

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

Symmetry Breaking of H2 Symmetry Breaking of H2 Dissociation by a Single Photon Symmetry Breaking of H2 Dissociation by a Single Photon Print Wednesday, 25 July 2007 00:00 A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

337

Dimensions of symmetry in syntax : agreement and clausal architecture  

E-Print Network (OSTI)

(cont.) are, then, determined at phase levels by late insertion of categorial features. One crucial aspect of the proposed theory of structural symmetry involves interweaving effects, which emerge as categorial determination ...

Hiraiwa, Ken, 1974-

2005-01-01T23:59:59.000Z

338

Symmetry Methods for a Geophysical Mass Flow Model  

Science Conference Proceedings (OSTI)

In the framework of symmetry analysis, the class of 2 x 2 PDE systems to whom belong the Savage and Hutter model and the Iverson model is considered. New classes of exact solutions are found.

Torrisi, Mariano; Tracina, Rita [Dipartimento di Matematica e Informatica, Viale A. Doria 6, Catania (Italy)

2011-09-14T23:59:59.000Z

339

FASTEST MIXING MARKOV CHAIN ON GRAPHS WITH SYMMETRIES  

E-Print Network (OSTI)

We show how to exploit symmetries of a graph to efficiently compute the fastest mixing Markov chain on the graph (i.e., find the transition probabilities on the edges to minimize the second-largest eigenvalue modulus of ...

Xiao, Lin

340

Extending 2-D Smoothed Local Symmetries to 3-D  

E-Print Network (OSTI)

3-D Smoothed Local Symmetries (3-D SLS's) are presented as a representation for three-dimensional shapes. 3-D SLS's make explicit the perceptually salient features of 3-D objects and are especially suited to representing ...

Braunegg, David J.

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Anatomy of symmetry energy of dilute nuclear matter  

E-Print Network (OSTI)

The symmetry energy coefficients of dilute clusterized nuclear matter are evaluated in the $S$-matrix framework. Employing a few different definitions commonly used in the literature for uniform nuclear matter, it is seen that the different definitions lead to perceptibly different results for the symmetry coefficients for dilute nuclear matter. They are found to be higher compared to those obtained for uniform matter in the low density domain. The calculated results are in reasonable consonance with those extracted recently from experimental data.

J. N. De; S. K. Samaddar; B. K. Agrawal

2010-09-23T23:59:59.000Z

342

Supercharge Operator of Hidden Symmetry in the Dirac Equation  

SciTech Connect

We require that there exist some additional symmetry of the Dirac Hamiltonian in an arbitrary central potential which describes the degeneracy of spectrum with respect to the two signs of eigenvalues of famous Dirac's K operator. It is proved that this happens only for the Coulomb potential. In this particular case symmetry operator reduces to the well-known Johnson-Lippmann operator, which plays a role of supercharge in the Dirac-Coulomb problem and generates a Witten's superalgebra.

Khachidze, Tamari T.; Khelashvili, Anzor A. [Department of Theoretical Physics, Ivane Javakhishvili Tbilisi State University, I.Chavchavadze ave. 3, 0128, Tbilisi (Georgia)

2007-01-12T23:59:59.000Z

343

Density dependence of symmetry free energy of hot nuclei  

E-Print Network (OSTI)

The density and excitation energy dependence of symmetry energy and symmetry free energy for finite nuclei are calculated microscopically in a microcanonical framework taking into account thermal and expansion effects. A finite-range momentum and density dependent two-body effective interaction is employed for this purpose. The role of mass, isospin and equation of state (EoS) on these quantities is also investigated; our calculated results are in consonance with the available experimental data.

S. K. Samaddar; J. N. De; X. Vinas; M. Centelles

2008-04-15T23:59:59.000Z

344

Current Densities in speed analyzer with different symmetries  

Science Conference Proceedings (OSTI)

A comparative analysis of the currents in speed analyzer of speeds is made with different symmetries. Three kinds of symmetries are considered; plane, cylindrical and spherical. The analyzers considered are formed by threes electrodes, the selector grid, the discriminator and the collector. The selector grid has a negative potential and for the coulombian effect the space charge is formed with the ionic thermal bath. Using kinetic theory a strongly non linear differential equation is obtained which is solved by numerical calculation.

Valdeblanquez, E. [Ciclo Basico, Departamento de Fisica, Apartado 4011- A 526, Universidad del Zulia, Facultad de Ingenieria, Maracaibo, Edo. Zulia (Venezuela); Centro de Investigacion de Matematicas Aplicadas, CIMA, Apartado 10486, Universidad del Zulia, Facultad de Ingenieria, Maracaibo, Edo. Zulia (Venezuela)

2006-12-04T23:59:59.000Z

345

What Have Spacetime, Shape and Symmetry to Do with Thermodynamics?  

E-Print Network (OSTI)

Some highly speculative and serendipitous ideas that might relate thermodynamics, spacetime, shape and symmetry are brought together. A hypothetical spacetime comprising a pointwise lattice with a fixed metric is considered. If there were absolute symmetry between displacement and time it is suggested that the velocity of light would be an integer conversion factor between the units of these quantities. In the context of such outlandish hypotheses the answer to the question posed would be 'everything'.

Jim McGovern

2007-10-05T23:59:59.000Z

346

Conservation Laws and Potential Symmetries of Linear Parabolic Equations  

E-Print Network (OSTI)

We carry out an extensive investigation of conservation laws and potential symmetries for the class of linear (1+1)-dimensional second-order parabolic equations. The group classification of this class is revised by employing admissible transformations, the notion of normalized classes of differential equations and the adjoint variational principle. All possible potential conservation laws are described completely. They are in fact exhausted by local conservation laws. For any equation from the above class the characteristic space of local conservation laws is isomorphic to the solution set of the adjoint equation. Effective criteria for the existence of potential symmetries are proposed. Their proofs involve a rather intricate interplay between different representations of potential systems, the notion of a potential equation associated with a tuple of characteristics, prolongation of the equivalence group to the whole potential frame and application of multiple dual Darboux transformations. Based on the tools developed, a preliminary analysis of generalized potential symmetries is carried out and then applied to substantiate our construction of potential systems. The simplest potential symmetries of the linear heat equation, which are associated with single conservation laws, are classified with respect to its point symmetry group. Equations possessing infinite series of potential symmetry algebras are studied in detail.

Roman O. Popovych; Michael Kunzinger; Nataliya M. Ivanova

2007-06-04T23:59:59.000Z

347

An SQP-type solution method for constrained discrete-time optimal control problems  

Science Conference Proceedings (OSTI)

Keywords: constrained optimal control, discrete-time systems, hydroelectric power-station systems, structured nonlinear programming

E. Arnold; H. Puta

1994-03-01T23:59:59.000Z

348

SymChaff: exploiting symmetry in a structure-aware satisfiability solver  

Science Conference Proceedings (OSTI)

This article presents a new low-overhead framework for representing and utilizing problem symmetry in propositional satisfiability algorithms. While many previous approaches have focused on symmetry extraction as a key component, the novelty in the proposed ... Keywords: Boolean satisfiability, Complete multi-class symmetry, Global symmetry, High-level representation, Planning, SAT, SymChaff

Ashish Sabharwal

2009-12-01T23:59:59.000Z

349

A three-level BDDC algorithm for Mortar discretizations  

SciTech Connect

In this paper, a three-level BDDC algorithm is developed for the solutions of large sparse algebraic linear systems arising from the mortar discretization of elliptic boundary value problems. The mortar discretization is considered on geometrically non-conforming subdomain partitions. In two-level BDDC algorithms, the coarse problem needs to be solved exactly. However, its size will increase with the increase of the number of the subdomains. To overcome this limitation, the three-level algorithm solves the coarse problem inexactly while a good rate of convergence is maintained. This is an extension of previous work, the three-level BDDC algorithms for standard finite element discretization. Estimates of the condition numbers are provided for the three-level BDDC method and numerical experiments are also discussed.

Kim, H.; Tu, X.

2007-12-09T23:59:59.000Z

350

Aggregationn of Space-Time Processes  

E-Print Network (OSTI)

irfxvrq LhihiUi? |_tU ttL? t@? _@TT*U@|L? tLu| i5T@UiA4i -i|@*i_hiuihi? Uit@? _@_tU ttL? Lui} |4@|h tTiU€ U@|L? U@?i? |% | uhL4| i5T@UiA4i tTL? |i_L |M)`i@? _ -@hiM@ti_L? |

Giacomini, Raffaella; Granger, Clive W.J.

2001-01-01T23:59:59.000Z

351

Space–Time Correlations of Lightning Distributions  

Science Conference Proceedings (OSTI)

Lightning location data are used to calculate the autocorrelation function of lightning distributions, which is a function of distances and time intervals between the single lightning events. This function is utilized for the characterization of ...

Ulli Finke

1999-08-01T23:59:59.000Z

352

Space-time orientations and Maxwell's equations  

E-Print Network (OSTI)

An analysis of the concept of orientation used in electrodynamics is presented. At least two different versions are encountered in the literature. Both are clearly identified and comparisons are made.

Giuseppe Marmo; Emanuele Parasecoli; Wlodzimierz M. Tulczyjew

2007-08-27T23:59:59.000Z

353

Methodology for characterizing modeling and discretization uncertainties in computational simulation  

SciTech Connect

This research effort focuses on methodology for quantifying the effects of model uncertainty and discretization error on computational modeling and simulation. The work is directed towards developing methodologies which treat model form assumptions within an overall framework for uncertainty quantification, for the purpose of developing estimates of total prediction uncertainty. The present effort consists of work in three areas: framework development for sources of uncertainty and error in the modeling and simulation process which impact model structure; model uncertainty assessment and propagation through Bayesian inference methods; and discretization error estimation within the context of non-deterministic analysis.

ALVIN,KENNETH F.; OBERKAMPF,WILLIAM L.; RUTHERFORD,BRIAN M.; DIEGERT,KATHLEEN V.

2000-03-01T23:59:59.000Z

354

Role of density dependent symmetry energy in nuclear stopping  

E-Print Network (OSTI)

Information about the nuclear matter under the extreme conditions of temperature and density and the role of symmetry energy under these conditions is still a topic of crucial importance in the present day nuclear physics research. The multifragmentation, collective flow and the nuclear stopping is among the various rare phenomenon which can be observed in heavy-ion collisions at intermediate energies. The nuclear stopping, which is sensitive towards the symmetry energy has gained a lot of interest because it provides the possibility to examine the degree of thermalization or equilibration in the matter. Aim of the present study is to pin down the nuclear stopping for the different forms of density dependent symmetry energy

Vinayak, Karan Singh

2011-01-01T23:59:59.000Z

355

Role of density dependent symmetry energy in nuclear stopping  

E-Print Network (OSTI)

Information about the nuclear matter under the extreme conditions of temperature and density and the role of symmetry energy under these conditions is still a topic of crucial importance in the present day nuclear physics research. The multifragmentation, collective flow and the nuclear stopping is among the various rare phenomenon which can be observed in heavy-ion collisions at intermediate energies. The nuclear stopping, which is sensitive towards the symmetry energy has gained a lot of interest because it provides the possibility to examine the degree of thermalization or equilibration in the matter. Aim of the present study is to pin down the nuclear stopping for the different forms of density dependent symmetry energy

Karan Singh Vinayak; Suneel Kumar

2011-07-27T23:59:59.000Z

356

Symmetry Breaking of H2 Dissociation by a Single Photon  

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

Symmetry Breaking of H2 Dissociation by a Single Photon Print Symmetry Breaking of H2 Dissociation by a Single Photon Print A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

357

Symmetry Breaking of H2 Dissociation by a Single Photon  

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

Symmetry Breaking of H2 Dissociation by a Single Photon Print Symmetry Breaking of H2 Dissociation by a Single Photon Print A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

358

Extended-Lorentz Quantum-Cosmology Symmetry Group  

E-Print Network (OSTI)

Unitarily representable by transformations of Milne quantum-universe (MQU) Hilbert-space vectors is a 9-parameter 'extended-Lorentz' Lie group whose algebra comprises 9 conserved MQU-constituent ('quc') attributes: electric charge, energy, spirality, 3-vector momentum and 3-vector angular momentum. Commutation with the full symmetry algebra by the 3-element Lorentz-extending sub-algebra identifies any quc by its (permanent) trio of charge, spirality and energy integers. Milne's redshift-specifying 'universe age' is invariant under the MQU symmetry group. Also invariant is the (elsewhere specified) universe hamiltonian--a self-adjoint age-dependent Hilbert-space operator (not a symmetry-algebra member) that generates universe evolution with increasing age through a 'Schrodinger' (first-order) differential equation.

Chew, Geoffrey F

2013-01-01T23:59:59.000Z

359

Extended-Lorentz Quantum-Cosmology Symmetry Group  

E-Print Network (OSTI)

Unitarily representable by transformations of Milne quantum-universe (MQU) Hilbert-space vectors is a 9-parameter 'extended-Lorentz' Lie group whose algebra comprises 9 conserved MQU-constituent ('quc') attributes: electric charge, energy, spirality, 3-vector momentum and 3-vector angular momentum. Commutation with the full symmetry algebra by the 3-element Lorentz-extending sub-algebra identifies any quc by its (permanent) trio of charge, spirality and energy integers. Milne's redshift-specifying 'universe age' is invariant under the MQU symmetry group. Also invariant is the (elsewhere specified) universe hamiltonian--a self-adjoint age-dependent Hilbert-space operator (not a symmetry-algebra member) that generates universe evolution with increasing age through a 'Schrodinger' (first-order) differential equation.

Geoffrey F. Chew

2013-08-17T23:59:59.000Z

360

Form invariance and symmetry in the neutrino mass matrix  

SciTech Connect

We present the general form of the unitary matrices keeping invariant the Majorana neutrino mass matrix of specific texture suitable for explaining oscillation data. In the case of the tri-bimaximal pattern with two degenerate masses, we give a specific realization of the underlying U(1) symmetry which can be uplifted to a symmetry in a complete theory including charged leptons. For this, we present a model with three light SM-like Higgs doublets and one heavy Higgs triplet and find that one can accommodate the hierarchy of the charged-lepton masses. The lepton mass spectrum can also be achieved in another model extending the SM with three SM-singlet scalars transforming nontrivially under the flavor symmetry. We discuss how such a model has room for generating enough baryon asymmetry through leptogenesis in the framework of type-I and -II seesaw mechanisms.

Lashin, E. I. [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh (Saudi Arabia); Ain Shams University, Faculty of Science, Cairo 11566 (Egypt); Nasri, S.; Malkawi, E. [Department of Physics, UAE University, P.O. Box 17551, Al-Ain (United Arab Emirates); Chamoun, N. [Physics Department, HIAST, P.O. Box 31983, Damascus (Syrian Arab Republic)

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Molecular quantum mechanical observers, symmetry, and string theory  

E-Print Network (OSTI)

The paper \\cite{Dance0601} tentatively suggested a physical picture that might underlie string theories. The string parameters $\\tau $ and $\\sigma_i $ were interpreted as spacetime dimensions which a simple quantum mechanical observer can observe, while symmetries of the relevant observer states could limit the observability of other dimensions. An atomic observer was the focus of the discussion. The present paper extends the discussion of\\cite{Dance0601} to molecular observers, including the nature of some common molecular bonds and their symmetries.

M. Dance

2010-11-29T23:59:59.000Z

362

Constraint on the (GUT) symmetry breaking scale and topological defects  

Science Conference Proceedings (OSTI)

In F-term supergravity inflation models, scalar fields other than the inflaton generically receive a Hubble induced mass, which may restore gauge symmetries during inflation and phase transitions may occur during or after inflation as the Hubble parameter decreases. We study topological defect formation associated with such a phase transition in chaotic inflation in supergravity and obtain a severe constraint on the symmetry breaking scale which is related with the tensor-to-scalar ratio. This talk is based on the paper [1].

Kamada, Kohei; Nakayama, Kazunori; Yokoyama, Jun'ichi [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Department of Physics, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan); Research Center for the Early Universe (RESCEU), Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan) and Kavli institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwa, Chiba, 277-8568 (Japan)

2012-07-27T23:59:59.000Z

363

Solving Elliptic Curve Discrete Logarithm Problems Using Weil Descent  

E-Print Network (OSTI)

We provide the first cryptographically interesting instance of the elliptic curve discrete logarithm problem which resists all previously known attacks, but which can be solved with modest computer resources using the Weil descent attack methodology of Frey. We report on our implementation of index-calculus methods for hyperelliptic curves over characteristic two finite fields, and discuss the cryptographic implications of our results.

Michael Jacobson; Alfred Menezes; Andreas Stein

2001-01-01T23:59:59.000Z

364

Simulation of mobile networks using discrete event system specification theory  

Science Conference Proceedings (OSTI)

The fourth generation (4G) of mobile telecommunication technology provides ultra-band internet access for mobile devices such as smartphones, tablets, and laptops. One of the challenges in the Long Term Evolution (LTE) 4G networks is the low data rate ... Keywords: DEVS, discrete event system specification, mobile networks

Mohammad Moallemi, Gabriel Wainer, Shafagh Jafer, Gary Boudreau, Ronald Casselman

2013-04-01T23:59:59.000Z

365

Discreteness and the transmission of light from distant sources  

SciTech Connect

We model the classical transmission of a massless scalar field from a source to a detector on a background causal set. The predictions do not differ significantly from those of the continuum. Thus, introducing an intrinsic inexactitude to lengths and durations--or more specifically, replacing the Lorentzian manifold with an underlying discrete structure--need not disrupt the usual dynamics of propagation.

Dowker, Fay [Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); Henson, Joe; Sorkin, Rafael D. [Perimeter Institute, 31 Caroline Street N., Waterloo, N2L 2Y5 (Canada)

2010-11-15T23:59:59.000Z

366

Optimization strategies for discrete multi-material stiffness optimization  

Science Conference Proceedings (OSTI)

Design of composite laminated lay-ups are formulated as discrete multi-material selection problems. The design problem can be modeled as a non-convex mixed-integer optimization problem. Such problems are in general only solvable to global optimality ... Keywords: Integer optimization, Laminated composite materials, Optimal design, Sensitivity analysis, Solution strategies

Christian Frier Hvejsel; Erik Lund; Mathias Stolpe

2011-08-01T23:59:59.000Z

367

DISPERSION AND DISSIPATION ERRORS OF TWO FULLY DISCRETE DISCONTINUOUS GALERKIN  

E-Print Network (OSTI)

-dimensional Euler equations in gas dynamics. There has been abundant study on the dispersion analysis of many nuDISPERSION AND DISSIPATION ERRORS OF TWO FULLY DISCRETE DISCONTINUOUS GALERKIN METHODS HE YANG, FENGYAN LI, AND JIANXIAN QIU Abstract. The dispersion and dissipation properties of numerical meth- ods

Li, Fengyan

368

Power system failure analysis by using the discrete wavelet transform  

Science Conference Proceedings (OSTI)

Voltage variations are the most common power quality events that may result in corruption of different industrial processes. The electric power utility industry requires significant improvement in the quality of power provided to customers during faults ... Keywords: discrete wavelet transform, power system failure, wavelet entropy

Ismail Yilmazlar; Gulden Kokturk

2010-05-01T23:59:59.000Z

369

Discrete-event simulation in Java: a practitioner's experience  

Science Conference Proceedings (OSTI)

The experience of a simulation practitioner with development of a new Java simulation engine and its application to a large simulation model is described. Our simulation engine is implemented as a simple extension of the Java programming language and ... Keywords: Java, discrete-event simulation, parallel processing, practitioner, supply chain

D. H. King; Harvey S. Harrison

2010-07-01T23:59:59.000Z

370

First–Order Representations of Discrete Linear MultidimensionalSystems  

Science Conference Proceedings (OSTI)

The classical local state–space models for discrete multidimensional linear systems, as proposed by Roesser or Fornasini and Marchesini, require causality of the resulting transfer matrices. We consider a generalization comprising non-causal ... Keywords: (Laurent) polynomial matrices, behavior, first–, input–, kernel and image representation, linear fractional transformation, minimality, order representation, output structure, properness

Eva Zerz

2000-10-01T23:59:59.000Z

371

Bounds for the price of discrete arithmetic Asian options  

Science Conference Proceedings (OSTI)

In this paper the pricing of European-style discrete arithmetic Asian options with fixed and floating strike is studied by deriving analytical lower and upper bounds. In our approach we use a general technique for deriving upper (and lower) bounds for ... Keywords: Asian option, Black and Scholes setting, analytical bounds, comonotonicity

M. Vanmaele; G. Deelstra; J. Liinev; J. Dhaene; M. J. Goovaerts

2006-01-01T23:59:59.000Z

372

Bounds for the price of discrete arithmetic Asian options  

Science Conference Proceedings (OSTI)

In this paper the pricing of European-style discrete arithmetic Asian options with fixed and floating strike is studied by deriving analytical lower and upper bounds. In our approach we use a general technique for deriving upper (and lower) bounds for ... Keywords: Analytical bounds, Asian option, Black and Scholes setting, Comonotonicity

M. Vanmaele; G. Deelstra; J. Liinev; J. Dhaene; M. J. Goovaerts

2006-01-01T23:59:59.000Z

373

Hidden maintenance opportunities in discrete and complex production lines  

Science Conference Proceedings (OSTI)

In manufacturing systems, many maintenance tasks require equipment to be stopped in order to safely perform them. However, such stoppage cannot last for too long since it might directly result in short-term production losses. In this paper, we investigate ... Keywords: Complex manufacturing systems, Discrete production, Maintenance opportunity windows

Xi Gu; Seungchul Lee; Xinran Liang; Mark Garcellano; Mark Diederichs; Jun Ni

2013-09-01T23:59:59.000Z

374

Specification of Discrete Event Models for Fire Spreading  

Science Conference Proceedings (OSTI)

The fire-spreading phenomenon is highly complex, and existing mathematical models of fire are so complex themselves that any possibility of analytical solution is precluded. Instead, there has been some success when studying fire spread by means of simulation. ... Keywords: Cell-DEVS, Cellular Automata, DEVS, Discrete event simulation, fire spread

Alexandre Muzy; Eric Innocenti; Antoine Aiello; Jean-François Santucci; Gabriel Wainer

2005-02-01T23:59:59.000Z

375

Sparse image representation by discrete cosine/spline based dictionaries  

E-Print Network (OSTI)

Mixed dictionaries generated by cosine and B-spline functions are considered. It is shown that, by highly nonlinear approaches such as Orthogonal Matching Pursuit, the discrete version of the proposed dictionaries yields a significant gain in the sparsity of an image representation.

Bowley, James

2009-01-01T23:59:59.000Z

376

Numerical Discretization of Rotated Diffusion Operators in Ocean Models  

Science Conference Proceedings (OSTI)

A method to improve the behavior of the numerical discretization of a rotated diffusion operator such as, for example, the isopycnal diffusion parameterization used in large-scale ocean models based on the so-called z-coordinate system is ...

J-M. Beckers; H. Burchard; E. Deleersnijder; P. P. Mathieu

2000-08-01T23:59:59.000Z

377

Estimating discrete Markov models from various incomplete data schemes  

Science Conference Proceedings (OSTI)

The parameters of a discrete stationary Markov model are transition probabilities between states. Traditionally, data consist in sequences of observed states for a given number of individuals over the whole observation period. In such a case, the estimation ... Keywords: Adaptive MCMC, Bayesian inference, Gaussian copulas, Industrial reliability, Markov models, Missing data

Alberto Pasanisi; Shuai Fu; Nicolas Bousquet

2012-09-01T23:59:59.000Z

378

Discrete-element modeling of particulate aerosol flows  

Science Conference Proceedings (OSTI)

A multiple-time step computational approach is presented for efficient discrete-element modeling of aerosol flows containing adhesive solid particles. Adhesive aerosol particulates are found in numerous dust and smoke contamination problems, including ... Keywords: Aerosols, Aggregation, Particle adhesion, Particulate flow

J. S. Marshall

2009-03-01T23:59:59.000Z

379

Concept inventories in computer science for the topic discrete mathematics  

Science Conference Proceedings (OSTI)

This report describes concept inventories, specialized assessment instruments that enable educational researchers to investigate student (mis)understandings of concepts in a particular domain. While students experience a concept inventory as a set of ... Keywords: assessment, assessment tools, concept inventory, discrete mathematics, distractors, misconceptions

Vicki L. Almstrum; Peter B. Henderson; Valerie Harvey; Cinda Heeren; William Marion; Charles Riedesel; Leen-Kiat Soh; Allison Elliott Tew

2006-12-01T23:59:59.000Z

380

Optimisation-based scheduling: A discrete manufacturing case study  

Science Conference Proceedings (OSTI)

This work presents the development and implementation of a production scheduling system for an electrical appliance manufacturer. Based on recent advances in optimisation-based scheduling approaches, two different software architectures based on two ... Keywords: Discrete manufacturing, Electrical appliances, Mixed-integer linear programming, Optimization-based scheduling

Michael C. Georgiadis; Aaron A. Levis; Panagiotis Tsiakis; Ioannis Sanidiotis; Constantinos C. Pantelides; Lazaros G. Papageorgiou

2005-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Frame sequential interpolation for discrete level-of-detail rendering  

Science Conference Proceedings (OSTI)

In this paper we present a method for automatic interpolation between adjacent discrete levels of detail to achieve smooth LOD changes in image space. We achieve this by breaking the problem into two passes: We render the two LOD levels individually ...

Daniel Scherzer; Michael Wimmer

2008-06-01T23:59:59.000Z

382

The theory of deadlock avoidance via discrete control  

Science Conference Proceedings (OSTI)

Deadlock in multithreaded programs is an increasingly important problem as ubiquitous multicore architectures force parallelization upon an ever wider range of software. This paper presents a theoretical foundation for dynamic deadlock avoidance in concurrent ... Keywords: concurrent programming, discrete control theory, dynamic deadlock avoidance, multicore processors, multithreaded programming, parallel programming

Yin Wang; Stéphane Lafortune; Terence Kelly; Manjunath Kudlur; Scott Mahlke

2009-01-01T23:59:59.000Z

383

Static, cylindrical symmetry in general relativity and vacuum energy  

E-Print Network (OSTI)

In the first section of my research, in analogy with the standard derivation of the spherically symmetric Schwarzschild solution of the Einstein field equations, I find all static, cylindrically symmetric solutions of the Einstein equations for vacuum. These include not only the well known cone solution, which is locally flat, but others in which the metric coefficients are powers of the radial coordinate and the space-time is curved. These solutions appear in the literature, but in different forms, corresponding to different definitions of the radial coordinate. I find expressions for transforming between these different metric forms and examine some special points of interest. I then examine some special cases of non-vacuum solutions of the equations as well. Because all the vacuum solutions are singular on the axis, I match them to interior solutions with nonvanishing energy density and pressure. In addition to the well known cosmic string solution joining on to the cone, we find some numerical solutions that join on to the other exterior solutions. I then consider only a static, flat, cylindrically symmetric space-time. I calculate the components of the stress-energy tensor in terms of the cylinder kernel and its derivatives. The cylinder kernel in cylindrical coordinates has been previously calculated and can be used to find the energy density and pressure on various cylindrical boundaries; future work will include finding these quantities for various cylindrically symmetric geometries.

Trendafilova, Cynthia

2011-05-01T23:59:59.000Z

384

Convergence of normal form transformations: The role of symmetries  

E-Print Network (OSTI)

We discuss the convergence problem for coordinate transformations which take a given vector field into Poincar\\'e-Dulac normal form. We show that the presence of linear or nonlinear Lie point symmetries can guaranteee convergence of these normalizing transformations, in a number of scenarios. As an application, we consider a class of bifurcation problems.

G. Cicogna; S. Walcher

2013-09-17T23:59:59.000Z

385

Addendum: Symmetries of the energy-momentum tensor  

E-Print Network (OSTI)

In recent papers [1-3], we have discussed matter symmetries of non-static spherically symmetric spacetimes, static plane symmetric spacetimes and cylindrically symmetric static spacetimes. These have been classified for both cases when the energy-momentum tensor is non-degenerate and also when it is degenerate. Here we add up some consequences and the missing references about the Ricci tensor.

M. Sharif

2004-10-28T23:59:59.000Z

386

Nuclear Symmetry Energy in Relativistic Mean Field Theory  

E-Print Network (OSTI)

The Physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we conform earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing $\\epsilon (A)$ and an effective mean isovector potential strength $\\kappa (A)$. A detaied analysis of isospin dependence of the two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, $\\sim\\epsilon T^2$, and, completely unexpectedly, the presence of a strong linear component $\\sim\\kappa T(T+1+\\epsilon/\\kappa)$ in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to $E_{sym}\\sim T(T+1)$ at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.

Shufang Ban; Jie Meng; Wojciech Satula; Ramon A. Wyss

2005-09-12T23:59:59.000Z

387

Compact Einstein-Weyl Manifolds With Large Symmetry Group  

E-Print Network (OSTI)

A geometric classification of the compact four-dimensional Einstein-Weyl manifolds with at least four-dimensional symmetry group is given. Our results also sharpen previous results on four-dimensional Einstein metrics and correct Parker's topological classification of cohomogeneity-one four-manifolds.

Anders Bisbjerg Madsen; Henrik Pedersen; Yat Sun Poon; Andrew Swann

1995-01-01T23:59:59.000Z

388

Particle-hole symmetry broken pseudogap in high temperature superconductors  

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

Particle-hole symmetry broken pseudogap in Particle-hole symmetry broken pseudogap in high temperature superconductors High-temperature (Tc) superconductivity is one of the most important topics in condensed matter physics. Despite extensive studies over more than two decades, the microscopic mechanism of high temperature superconductivity still remains elusive due to many unconventional properties that are not well understood. Among them, the most mysterious behavior of high-Tc superconductor is the nature of so called "pseudogap", which has been a focus of the field for many years. In conventional superconductors, a gap exists in the energy absorption spectrum only below Tc, corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-Tc cuprate superconductors, an energy gap called the pseudogap exists above Tc but below T*, and is controversially attributed either to pre-formed superconducting pairs or to competing phases. Recently, by carefully studying the "symmetry" of the gap, researchers Makoto Hashimoto and Rui-Hua He, along with their co-workers in Prof. Zhi-Xun Shen's group at Stanford University, have found crucial evidence suggesting that the particle-hole symmetry required by superconductivity is broken in the pseudogap state.

389

Final Report Fermionic Symmetries and Self consistent Shell Model  

SciTech Connect

In this final report in the field of theoretical nuclear physics we note important accomplishments.We were confronted with "anomoulous" magnetic moments by the experimetalists and were able to expain them. We found unexpected partial dynamical symmetries--completely unknown before, and were able to a large extent to expain them.The importance of a self consistent shell model was emphasized.

Larry Zamick

2008-11-07T23:59:59.000Z

390

Higgs algebraic symmetry in the two-dimensional Dirac equation  

E-Print Network (OSTI)

The dynamical symmetry algebra of the two-dimensional Dirac Hamiltonian with equal scalar and vector Smorodinsky-Winternitz potentials is constructed. It is the Higgs algebra, a cubic polynomial generalization of SU(2). With the help of the Casimir operators, the energy levels are derived algebraically.

Fu-Lin Zhang; Bo Fu; Jing-Ling Chen

2009-07-04T23:59:59.000Z

391

Models and Symmetry Breaking for `Peaceable Armies of Queens'  

E-Print Network (OSTI)

to address in implementation. We added constraints so that a square being unattacked by a white queen problem on a chess-board, requiring equal numbers of black and white queens to be placed on the board so that the white queens cannot attack the black queens. We show how the symmetry of the problem can

Smith, Barbara M.

392

Using symmetry and evolutionary search to minimize sorting networks  

Science Conference Proceedings (OSTI)

Sorting networks are an interesting class of parallel sorting algorithms with applications in multiprocessor computers and switching networks. They are built by cascading a series of comparison-exchange units called comparators. Minimizing the number ... Keywords: combinatorial optimization, estimation of distribution algorithms, evolution, sorting networks, symmetry

Vinod K. Valsalam, Risto Miikkulainen

2013-01-01T23:59:59.000Z

393

The Eightfold Way: A Theory of Strong Interaction Symmetry  

DOE R&D Accomplishments (OSTI)

A new model of the higher symmetry of elementary particles is introduced ln which the eight known baryons are treated as a supermultiplet, degenerate in the limit of unitary symmetry but split into isotopic spin multiplets by a symmetry-breaking term. The symmetry violation is ascribed phenomenologically to the mass differences. The baryons correspond to an eight-dimensional irreducible representation of the unitary group. The pion and K meson fit into a similar set of eight particles along with a predicted pseudoscalar meson X {sup o} having I = 0. A ninth vector meson coupled to the baryon current can be accommodated naturally in the scheme. It is predicted that the eight baryons should all have the same spin and parity and that pseudoscalar and vector mesons should form octets with possible additional singlets. The mathematics of the unitary group is described by considering three fictitious leptons, nu , e {sup -}, and mu {sup -}, which may throw light on the structure of weak interactions. (D. L.C.)

Gell-Mann, M.

1961-03-15T23:59:59.000Z

394

Quantified Symmetry for Entorhinal Spatial Maps Erick Chastain  

E-Print Network (OSTI)

Quantified Symmetry for Entorhinal Spatial Maps Erick Chastain , Yanxi Liu February 6, 2006 spatial map (see also Chastain & Liu 2006 [2]). We show that the geometric and algebraic invariant, 4th edn. (Springer-Verlag, New York, 1980). [2] Chastain, E., and Liu, Y. Firing Fields

395

Three fluid cosmological model using Lie and Noether symmetries  

E-Print Network (OSTI)

We employ a three fluid model in order to construct a cosmological model in the Friedmann Robertson Walker flat spacetime, which contains three types of matter dark energy, dark matter and a perfect fluid with a linear equation of state. Dark matter is described by dust and dark energy with a scalar field with potential V({\\phi}). In order to fix the scalar field potential we demand Lie symmetry invariance of the field equations, which is a model-independent assumption. The requirement of an extra Lie symmetry selects the exponential scalar field potential. The further requirement that the analytic solution is invariant under the point transformation generated by the Lie symmetry eliminates dark matter and leads to a quintessence and a phantom cosmological model containing a perfect fluid and a scalar field. Next we assume that the Lagrangian of the system admits an extra Noether symmetry. This new assumption selects the scalar field potential to be exponential and forces the perfect fluid to be stiff. Furthermore the existence of the Noether integral allows for the integration of the dynamical equations. We find new analytic solutions to quintessence and phantom cosmologies which contain all three fluids. Using these solutions one is able to compute analytically all main cosmological functions, such as the scale factor, the scalar field, the Hubble expansion rate, the deceleration parameter etc.

Michael Tsamparlis; Andronikos Paliathanasis

2011-11-23T23:59:59.000Z

396

Symmetry, Optical Properties and Thermodynamics of Neptunium(V) Complexes  

SciTech Connect

Recent results on the optical absorption and symmetry of the Np(V) complexes with dicarboxylate and diamide ligands are reviewed. The importance of recognizing the 'silent' feature of centrosymmetric Np(V) species in analyzing the absorption spectra and calculating the thermodynamic constants of Np(V) complexes is emphasized.

Rao, Linfeng; Tian, Guoxin

2009-12-21T23:59:59.000Z

397

A note on conformal symmetry in projective superspace  

E-Print Network (OSTI)

We describe a sufficient condition for actions constructed in projective superspace to possess an SU(2) R-symmetry. We check directly that this condition implies that the corresponding hyperkahler varieties, constructed by means of the generalized Legendre transform, have a Swann bundle structure.

Radu A. Ionas; Andrew Neitzke

2008-11-13T23:59:59.000Z

398

Quadratic Galerkin Finite Element Schemes for the Vertical Discretization of Numerical Forecast Models  

Science Conference Proceedings (OSTI)

A finite element scheme with second-order basis functions is introduced for vertical discretization using a spectral model for horizontal discretization. The basis functions are required to be continuous, and no assumption is made concerning the ...

J. Steppeler

1987-08-01T23:59:59.000Z

399

Bounded skew high-order resolution schemes for the discrete ordinates method  

Science Conference Proceedings (OSTI)

The discrete ordinates method for the solution of the radiative heat transfer equation suffers from two main shortcomings, namely ray effects and numerical smearing. Spatial discretization, which is the cause of numerical smearing, constitutes the subject ...

P. J. Coelho

2002-01-01T23:59:59.000Z

400

An Unsuspected Boundary-Induced Temporal Computational Mode in a Two-Time-Level Discretization  

Science Conference Proceedings (OSTI)

Normal-mode analyses are applied to various discrete forms of the one-dimensional, linearized, vertical acoustic equations in a height-based coordinate. First, the temporally discrete, spatially continuous equations are considered and the normal ...

Andrew Staniforth; Nigel Wood

2005-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Discreteness of spectrum and positivity criteria for Schrödinger operators  

E-Print Network (OSTI)

We provide a class of necessary and sufficient conditions for the discreteness of spectrum of Schr\\"odinger operators with scalar potentials which are semibounded below. The classical discreteness of spectrum criterion by A.M.Molchanov (1953) uses a notion of negligible set in a cube as a set whose Wiener's capacity is less than a small constant times the capacity of the cube. We prove that this constant can be taken arbitrarily between 0 and 1. This solves a problem formulated by I.M.Gelfand in 1953. Moreover, we extend the notion of negligibility by allowing the constant to depend on the size of the cube. We give a complete description of all negligibility conditions of this kind. The a priori equivalence of our conditions involving different negligibility classes is a non-trivial property of the capacity. We also establish similar strict positivity criteria for the Schr\\"odinger operators with non-negative potentials.

Vladimir Maz'ya; Mikhail Shubin

2003-05-19T23:59:59.000Z

402

An adaptive synchronization protocol for parallel discrete event simulation  

SciTech Connect

Simulation, especially discrete event simulation (DES), is used in a variety of disciplines where numerical methods are difficult or impossible to apply. One problem with this method is that a sufficiently detailed simulation may take hours or days to execute, and multiple runs may be needed in order to generate the desired results. Parallel discrete event simulation (PDES) has been explored for many years as a method to decrease the time taken to execute a simulation. Many protocols have been developed which work well for particular types of simulations, but perform poorly when used for other types of simulations. Often it is difficult to know a priori whether a particular protocol is appropriate for a given problem. In this work, an adaptive synchronization method (ASM) is developed which works well on an entire spectrum of problems. The ASM determines, using an artificial neural network (ANN), the likelihood that a particular event is safe to process.

Bisset, K.R.

1998-12-01T23:59:59.000Z

403

Four-body continuum-discretized coupled-channels calculations  

SciTech Connect

The development of a continuum-bin scheme of discretization for three-body projectiles is necessary for studies of reactions of Borromean nuclei such as {sup 6}He within the continuum-discretized coupled-channels approach. Such a procedure, for constructing bin states on selected continuum energy intervals, is formulated and applied for the first time to reactions of a three-body projectile. The continuum representation uses the eigenchannel expansion of the three-body S matrix. The method is applied to the challenging case of the {sup 6}He+{sup 208}Pb reaction at 22 MeV, where an accurate treatment of both the Coulomb and the nuclear interactions with the target is necessary.

Rodriguez-Gallardo, M. [Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla (Spain); Centro de Fisica Nuclear, Universidade de Lisboa, Avenida Prof. Gama Pinto 2, P-1649-003 Lisboa (Portugal); Arias, J. M.; Moro, A. M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla (Spain); Gomez-Camacho, J. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla (Spain); Centro Nacional de Aceleradores, Avenida Thomas A. Edison, E-41092 Sevilla (Spain); Thompson, I. J. [Lawrence Livermore National Laboratory, Physical Science Directorate, P. O. Box 808, L-414, Livermore, California 94551 (United States); Tostevin, J. A. [Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2009-11-15T23:59:59.000Z

404

The discrete Kalman filtering approach for seismic signals deconvolution  

SciTech Connect

Seismic signals are a convolution of reflectivity and seismic wavelet. One of the most important stages in seismic data processing is deconvolution process; the process of deconvolution is inverse filters based on Wiener filter theory. This theory is limited by certain modelling assumptions, which may not always valid. The discrete form of the Kalman filter is then used to generate an estimate of the reflectivity function. The main advantage of Kalman filtering is capability of technique to handling continually time varying models and has high resolution capabilities. In this work, we use discrete Kalman filter that it was combined with primitive deconvolution. Filtering process works on reflectivity function, hence the work flow of filtering is started with primitive deconvolution using inverse of wavelet. The seismic signals then are obtained by convoluting of filtered reflectivity function with energy waveform which is referred to as the seismic wavelet. The higher frequency of wavelet gives smaller wave length, the graphs of these results are presented.

Kurniadi, Rizal; Nurhandoko, Bagus Endar B. [Departement of Physics Intitut Teknologi Bandung, Jl. Ganesha 10 Bandung (Indonesia)

2012-06-20T23:59:59.000Z

405

Relative Fisher information of discrete classical orthogonal polynomials  

E-Print Network (OSTI)

The analytic information theory of discrete distributions was initiated in 1998 by C. Knessl, P. Jacquet and S. Szpankowski who addressed the precise evaluation of the Renyi and Shannon entropies of the Poisson, Pascal (or negative binomial) and binomial distributions. They were able to derive various asymptotic approximations and, at times, lower and upper bounds for these quantities. Here we extend these investigations in a twofold way. First, we consider a much larger class of distributions, the Rakhmanov distributions $\\rho_n(x)=\\omega(x)y_n^2(x)$, where $\\{y_n(x)\\}$ denote the sequences of discrete hypergeometric-type polynomials which are orthogonal with respect to the weight function $\\omega(x)$ of Poisson, Pascal, binomial and hypergeometric types; that is the polynomials of Charlier, Meixner, Kravchuk and Hahn. Second, we obtain the explicit expressions for the relative Fisher information of these four families of Rakhmanov distributions with respect to their respective weight functions.

Jesus S. Dehesa; Pablo Sánchez-Moreno; Rafael J. Yáñez

2013-05-20T23:59:59.000Z

406

A study of discrete and continuum joint modeling techniques  

SciTech Connect

This paper presents the results of a numerical and experimental study in which finite element and discrete element techniques were used to analyze a layered polycarbonate plate model subjected to uniaxial compression. Also, the two analysis techniques were used to compute the response of an eight meter diameter drift in jointed-rock. The drift was subjected to in-situ and far-field induced thermal stresses. The finite element analyses used a continuum rock model to represent the jointed-rock. A comparison of the analyses showed that the finite element continuum joint model consistently predicted less joint slippage than did the discrete element analyses, although far-field displacements compared well.

Jung, J.; Brown, S.R.

1992-05-01T23:59:59.000Z

407

Test Map and Discreteness Criteria for Subgroups in PU(1,n;C)  

E-Print Network (OSTI)

We study the discreteness for non-elementary subgroup G in PU(1, n;C), under the assumption that G satisfies Condition A. Mainly, we present that one can use a test map, which need not to be in G, to examine the discreteness of G, and also show that G is discrete, if every two-loxodromic-generator subgroup of G is discrete.

Li, ChangJun

2011-01-01T23:59:59.000Z

408

Biometric cryptosystem based on discretized fingerprint texture descriptors  

Science Conference Proceedings (OSTI)

This paper focuses on a biometric cryptosystem implementation and evaluation based on a number of fingerprint texture descriptors. The texture descriptors, namely, the Gabor filter-based FingerCode, a local binary pattern (LBP), and a local direction ... Keywords: BCH, BPA, Biometric discretization, DROBA, ECC, EER, Error-correcting code, FAR, FCS, FRR, Fingerprint texture descriptors, Fuzzy commitment scheme, GAR, LBP, LCM, LDP, LDPC, LDerivP, Local binary pattern, MPA, PEG, ROI, SPA

Yadigar Imamverdiyev; Andrew Beng Jin Teoh; Jaihie Kim

2013-04-01T23:59:59.000Z

409

Discrete diffusion Monte Carlo for frequency-dependent radiative transfer  

SciTech Connect

Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.

Densmore, Jeffrey D [Los Alamos National Laboratory; Kelly, Thompson G [Los Alamos National Laboratory; Urbatish, Todd J [Los Alamos National Laboratory

2010-11-17T23:59:59.000Z

410

gxxx005-conlaw.dvi  

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

7 7 Page 1 TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CONLAW=C PAR=S009;DESIG=4 Γ(π 0 → 3γ)/Γ total <3.1 × 10 -8 , CL = 90% η C-nonconserving decay parameters NODE=S014230 NODE=S014A1 π + π - π 0 left-right asymmetry (0.09 + 0.11 - 0.12 ) × 10 -2 NODE=S014AS π + π - π 0 sextant asymmetry (0.12 + 0.10 - 0.11 ) × 10 -2 NODE=S014AQ π + π - π 0 quadrant asymmetry (- 0.09 ± 0.09) × 10 -2 NODE=S014A2 π + π - γ left-right asymmetry (0.9 ± 0.4) × 10 -2 NODE=S014BET π + π - γ parameter β (D-wave) - 0.02 ± 0.07 (S = 1.3) PAR=S014;DESIG=104 Γ(η → π 0 γ)/Γ total <9 × 10 -5 , CL = 90% PAR=S014;DESIG=103 Γ(η → 2π 0 γ)/Γ

411

Connecting Blackbody Radiation, Relativity, and Discrete Charge in Classical Electrodynamics  

E-Print Network (OSTI)

It is suggested that an understanding of blackbody radiation within classical physics requires the presence of classical electromagnetic zero-point radiation, the restriction to relativistic (Coulomb) scattering systems, and the use of discrete charge. The contrasting scaling properties of nonrelativistic classical mechanics and classical electrodynamics are noted, and it is emphasized that the solutions of classical electrodynamics found in nature involve constants which connect together the scales of length, time, and energy. Indeed, there are analogies between the electrostatic forces for groups of particles of discrete charge and the van der Waals forces in equilibrium thermal radiation. The differing Lorentz- or Galilean-transformation properties of the zero-point radiation spectrum and the Rayleigh-Jeans spectrum are noted in connection with their scaling properties. Also, the thermal effects of acceleration within classical electromagnetism are related to the existence of thermal equilibrium within a gravitational field. The unique scaling and phase-space properties of a discrete charge in the Coulomb potential suggest the possibility of an equilibrium between the zero-point radiation spectrum and matter which is universal (independent of the particle mass), and an equilibrium between a universal thermal radiation spectrum and matter where the matter phase space depends only upon the ratio mc^2/kT. The observations and qualitative suggestions made here run counter to the ideas of currently accepted quantum physics.

Timothy H. Boyer

2006-04-28T23:59:59.000Z

412

Geo-MHYDAS: A landscape discretization tool for distributed hydrological modeling of cultivated areas  

Science Conference Proceedings (OSTI)

The representation of landscape variabilities by means of an adequate landscape discretization is of major importance in distributed hydrological modeling. In this paper, we present Geo-MHYDAS, a landscape discretization tool that allows explicit representation ... Keywords: Cultivated catchment, Discretization, GIS, Hydrology, Landscape, Topology

P. Lagacherie; M. Rabotin; F. Colin; R. Moussa; M. Voltz

2010-08-01T23:59:59.000Z

413

A Bootstrap Method for Software Reliability Assessment Based on a Discretized NHPP Model  

Science Conference Proceedings (OSTI)

We discuss a bootstrap method for software reliability assessment based on a discretized no homogeneous Poisson process (NHPP) model. Ordinarily, model parameters of the discretized NHPP model are estimated by using the regression analysis based on the ... Keywords: Software reliability assessment, Discretized NHPP model, Regression analysis, Bootstrap method

Shinji Inoue; Shigeru Yamada

2012-11-01T23:59:59.000Z

414

Continuous vs. discrete models for the quantum harmonic oscillator and the hydrogen atom  

E-Print Network (OSTI)

The Kravchuk and Meixner polynomials of discrete variable are introduced for the discrete models of the harmonic oscillator and hydrogen atom. Starting from Rodrigues formula we construct raising and lowering operators, commutation and anticommutation relations. The physical properties of discrete models are figured out through the equivalence with the continuous models obtained by limit process.

M. Lorente

2004-01-15T23:59:59.000Z

415

Determining the adaptive decision zone of discrete lot sizing model with changes of total cost  

Science Conference Proceedings (OSTI)

The Economic Order Quantity (EOQ) zone is beneficial for giving some latitude in picking the lot sizes in a continuous time inventory problem, but it is not suitable for a discrete time inventory problem, the discrete lot sizing (DLS) problem. In this ... Keywords: Alternative solutions, Decision making, Discrete lot sizing, EOQ zone

Dong-Shang Chang; Fu-Chiao Chyr; Fu-Chiang Yang

2010-10-01T23:59:59.000Z

416

The quadratic-form identity for constructing the Hamiltonian structures of the discrete integrable systems  

Science Conference Proceedings (OSTI)

The quadratic-form identity is extended to the discrete version which can be used to construct the Hamiltonian structures of the discrete integrable systems associated with the Lie algebra possessing degenerate Killing forms. Especially, it can be used ... Keywords: Discrete quadratic-form identity, Hamiltonian structure, Integrable couplings, Liouville integrability, Toda hierarchy

Yuqin Yao; Jie Ji; Dengyuan Chen; Yunbo Zeng

2008-12-01T23:59:59.000Z

417

Phenomenons and Methods: Uncertainty in Internal Symmetry Nets with Backpropagation in Image Processing  

Science Conference Proceedings (OSTI)

Internal Symmetry Nets are a new developed class of cellular neural networks. It originated from internal symmetry quantum physics, and noted by five irreducible representations from group theory. In this paper, uncertainty of the nets in a series of ... Keywords: internal symmetry, back propagation, momentum and learning rate, overfitting, recurrent cycles

Guanzhong Li

2009-05-01T23:59:59.000Z

418

Symmetry energy and nucleon-nucleon cross sections  

E-Print Network (OSTI)

The extension of the Boltzmann-Uehling-Uhlenbeck model of nucleus-nucleus collision is presented. The isospin-dependent nucleon-nucleon cross sections are estimated using the proper volume extracted from the equation of state of the nuclear matter transformed into the form of the Van der Waals equation of state. The results of such simulations demonstrate the dependence on symmetry energy which typically varies strongly from the results obtained using only the isospin-dependent mean-field. The evolution of the n/p multiplicity ratio with angle and kinetic energy, in combination with the elliptic flow of neutrons and protons, provides a suitable set of observables for determination of the density dependence of the symmetry energy. The model thus provides an environment for testing of equations of state, used for various applications in nuclear physics and astrophysics.

Martin Veselsky; Yu-Gang Ma

2013-03-11T23:59:59.000Z

419

Yoichiro Nambu and the Mechanism of Spontaneous Broken Symmetries in  

Office of Scientific and Technical Information (OSTI)

Yoichiro Nambu and the Mechanism of Yoichiro Nambu and the Mechanism of Spontaneous Broken Symmetries in Subatomic Physics Resources with Additional Information · Awards Yoichiro Nambu Credit: University of Chicago Yoichiro Nambu was awarded the 2008 Nobel Prize in Physics "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics". Nambu 'has revolutionized modern scientific ideas about the nature of the most fundamental particles and the space through which they move. His theories form an essential cornerstone of what physicists call the Standard Model, which explains in a unified way three of the four fundamental forces of nature: strong, weak and electromagnetic. He also has significantly influenced the development of quantum chromodynamics, a theory that describes certain interactions between quarks and between protons and neutrons.' 1

420

Spinor Bose gases: Explorations of symmetries, magnetism and quantum dynamics  

E-Print Network (OSTI)

Spinor Bose gases form a family of quantum fluids manifesting both magnetic order and superfluidity. This article reviews experimental and theoretical progress in understanding the static and dynamic properties of these fluids. The connection between system properties and the rotational symmetry properties of the atomic states and their interactions are investigated. Following a review of the experimental techniques used for characterizing spinor gases, their mean-field and many-body ground states, both in isolation and under the application of symmetry-breaking external fields, are discussed. These states serve as the starting point for understanding low-energy dynamics, spin textures and topological defects, effects of magnetic dipole interactions, and various non-equilibrium collective spin-mixing phenomena. The paper aims to form connections and establish coherence among the vast range of works on spinor Bose gases, so as to point to open questions and future research opportunities.

Stamper-Kurn, Dan M

2012-01-01T23:59:59.000Z

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421

Symmetries and exact solutions of the BPS Skyrme model  

E-Print Network (OSTI)

The BPS Skyrme model is a specific subclass of Skyrme-type field theories which possesses both a BPS bound and infinitely many soliton solutions (skyrmions) saturating that bound, a property that makes the model a very convenient first approximation to the study of some properties of nuclei and hadrons. A related property, the existence of a large group of symmetry transformations, allows for solutions of rather general shapes, among which some of them will be relevant to the description of physical nuclei. We study here the classical symmetries of the BPS Skyrme model, applying them to construct soliton solutions with some prescribed shapes, what constitutes a further important step for the reliable application of the model to strong interaction physics.

Adam, C; Queiruga, J M; Sanchez-Guillen, J; Wereszczynski, A

2012-01-01T23:59:59.000Z

422

Acceleration of the cosmic expansion induced by symmetry breaking  

E-Print Network (OSTI)

It is proved that in order to obtain a model of the accelerated cosmic expansion the thing one only need to do is to add a perturbation term to the Einstein-Hilbert Lagrangian. This term leads to some symmetry breaking terms in the fields equation, which makes the cosmic expansion accelerating. A vacuum de Sitter solution is obtained. A new explanation of the acceleration of the cosmic expansion is presented. In this model the changing of the expansion from decelerating to accelerating is an intrinsic property of the universe without need of an exotic dark energy. The acceleration of the cosmic expansion is induced by the symmetry breaking perturbation of the gravitational energy. The cosmological constant problem, the coincidence problem and the problem of phantom divide line crossing are naturally solved. The results of the model are roughly consistent with the observations.

G. Y. Chee

2013-01-21T23:59:59.000Z

423

The Exact Superconformal R-symmetry Minimizes $?_{RR}$  

E-Print Network (OSTI)

We present a new, general constraint which, in principle, determines the superconformal $U(1)_R$ symmetry of 4d $\\N =1$ SCFTs, and also 3d $\\N =2$ SCFTs. Among all possibilities, the superconformal $U(1)_R$ is that which minimizes the coefficient, $\\tau_{RR}$, of its two-point function. Equivalently, the superconformal $U(1)_R$ is the unique one with vanishing two-point function with every non-R flavor symmetry. For 4d $\\N =1$ SCFTs, $\\tau_{RR}$ minimization gives an alternative to a-maximization. $\\tau_{RR}$ minimization also applies in 3d, where no condition for determining the superconformal $U(1)_R$ had been previously known. Unfortunately, this constraint seems impractical to implement for interacting field theories. But it can be readily implemented in the AdS geometry for SCFTs with AdS duals.

Edwin Barnes; Elie Gorbatov; Ken Intriligator; Matt Sudano; Jason Wright

2005-07-14T23:59:59.000Z

424

Search for gauge symmetry generators of singular Lagrangian theory  

E-Print Network (OSTI)

We propose a procedure which allows one to construct local symmetry generators of general quadratic Lagrangian theory. Manifest recurrence relations for generators in terms of so-called structure matrices of the Dirac formalism are obtained. The procedure fulfilled in terms of initial variables of the theory, and do not implies either separation of constraints on first and second class subsets or any other choice of basis for constraints.

A. A. Deriglazov

2005-09-29T23:59:59.000Z

425

On Geometric Symmetry and New Rich Physics in Particle Mixing  

E-Print Network (OSTI)

As known from general relativity, particle mass and energy create the geometry of macroscopic space. Since the concept of particle mass matrix is a generalization of mass concept in physics with extra flavor generation, the particle mixing angles may be related to the geometry of space. In this paper geometric symmetry of neutrino mixing angles is identified with the outer macroscopic space symmetry. Though it is not a common idea, together with color symmetry it predicts two large and one relatively small theta_13 neutrino mixing angles in agreement with data, equal numbers of space dimensions and particle flavors and colors, and leads naturally to united bimaximal neutrino and zero quark mixing patterns at benchmark point. A formal analogy of neutrino and quark benchmark mixing patterns with two kinds of inertial motion in Newton's classical mechanics is observed. It conforms to the fact of two very different types of particle mixing patterns - neutrino mixing conforms to point particle inertial motion, while white color quark mixing conforms to inertial solid body rotation with the strong QCD bond of quark colors being analogous to the strong bond of point particles in solid body. The discussed semi-empirical flavor mixing phenomenology indicates inert stable dark matter candidate as complete copy of the visible matter with hypothetical advanced observable dark matter civilization.

E. M. Lipmanov

2012-12-05T23:59:59.000Z

426

Phenomenological constraints on broken R parity symmetry in supersymmetry models  

E-Print Network (OSTI)

The R parity odd renormalizable Yukawa interactions of quarks and leptons with the scalar superpartners have the ability to violate the baryon and lepton numbers, change the hadron and lepton flavors and make the lightest supersymmetric particle unstable. The existence of an approximate R parity symmetry would thus affect in a deep way the conventional framework of the Minimal Supersymmetric Standard Model where an exact R parity symmetry is built-in by assumption. The purpose of the present review is to survey in a systematic way the direct experimental constraints set on the R parity violating couplings by the low and intermediate energy physics processes. We consider first the option of bilinear R parity violation and spontaneously broken R parity symmetry and proceed next to the trilinear R parity violating interactions. The discussion aims at surveying the indirect coupling constant bounds derived from fundamental tests of the Standard Model and the variety of scattering and rare decay processes. We also discuss the constraints imposed by the renormalization group scale evolution and the cosmological and astrophysical phenomenology.

Marc Chemtob

2004-06-02T23:59:59.000Z

427

Symmetry Energy Constraints from Giant Resonances: A Theoretical Overview  

E-Print Network (OSTI)

Giant resonances encapsulate the dynamic response of the nuclear ground state to external perturbations. As such, they offer a unique view of the nucleus that is often not accessible otherwise. Although interesting in their own right, giant resonances are also enormously valuable in providing stringent constraints on the equation of state of asymmetric matter. We this view in mind, we focus on two modes of excitation that are essential in reaching this goal: the isoscalar giant monopole resonance (GMR) and the isovector giant dipole resonance (GDR). GMR energies in heavy nuclei are sensitive to the symmetry energy because they probe the incompressibility of neutron-rich matter. Unfortunately, access to the symmetry energy is hindered by the relatively low neutron-proton asymmetry of stable nuclei. Thus, the measurement of GMR energies in exotic nuclei is strongly encouraged. In the case of the GDR, we find the electric dipole polarizability of paramount importance. Indeed, the electric dipole polarizability appears as one of two laboratory observables -- with the neutron-skin thickness being the other -- that are highly sensitive to the density dependence of the symmetry energy. Finally, we identify the softness of skin and the nature of the pygmy resonance as important unsolved problems in nuclear structure.

J. Piekarewicz

2013-07-29T23:59:59.000Z

428

Central symmetry and antisymmetry of the microwave background inhomogeneities on Wilkinson Microwave Anisotropy Probe maps  

E-Print Network (OSTI)

We performed a visual and numeric analysis of the deviation of the microwave background temperature on WMAP maps. We proved that the microwave background inhomogeneities possess the property of the central symmetry resulting from the two kinds of central symmetry of the opposite signs. After the computer modeling we have established the relation between the coefficient of the central symmetry and the values of the symmetrical and antisymmetrical components of the deviation of the temperature. The obtained distribution of the symmetry coefficient on the map of the celestial sphere in Mollweide projection testifies on a contribution of both kinds of central symmetry which is approximately equal on the average in absolute magnitude but opposite by sign and where one kind of the central symmetry prevails on some sections of the celestial sphere and another kind - on the others. The average resulting value of the symmetry coefficient on the sections with angular measures less than 15-200 varies within the range fr...

Kudriavtcev, Iurii

2010-01-01T23:59:59.000Z

429

A concurrent, multigroup, discrete ordinates model of neutron transport  

SciTech Connect

The authors present an algorithm for the concurrent solution of the linear system arising from a multigroup, discrete ordinates model of neutron transport. The target architectures consist of distributed memory computers ranging from workstation clusters to massively parallel computers. Based on an analysis of the memory requirement and floating point complexity of matrix-vector multiplication in the iterative solution of the linear system, the authors propose a data layout and communication strategy designed to achieve scalability with respect to all phase space variables. Numerical results are presented to demonstrate the performance of the algorithm on the nCUBE/2.

Dorr, M.R.; Still, C.H.

1993-10-22T23:59:59.000Z

430

From continuum Fokker-Planck models to discrete kinetic models  

E-Print Network (OSTI)

ABSTRACT Two theoretical formalisms are widely used in modeling mechanochemical systems such as protein motors: continuum Fokker-Planck models and discrete kinetic models. Both have advantages and disadvantages. Here we present a ‘‘finite volume’ ’ procedure to solve Fokker-Planck equations. The procedure relates the continuum equations to a discrete mechanochemical kinetic model while retaining many of the features of the continuum formulation. The resulting numerical algorithm is a generalization of the algorithm developed previously by Fricks, Wang, and Elston through relaxing the local linearization approximation of the potential functions, and a more accurate treatment of chemical transitions. The new algorithm dramatically reduces the number of numerical cells required for a prescribed accuracy. The kinetic models constructed in this fashion retain some features of the continuum potentials, so that the algorithm provides a systematic and consistent treatment of mechanical-chemical responses such as load-velocity relations, which are difficult to capture with a priori kinetic models. Several numerical examples are given to illustrate the performance of the method.

Jianhua Xing; Hongyun Wang; George Oster

2005-01-01T23:59:59.000Z

431

Discrete-element modeling of particulate aerosol flows  

Science Conference Proceedings (OSTI)

A multiple-time step computational approach is presented for efficient discrete-element modeling of aerosol flows containing adhesive solid particles. Adhesive aerosol particulates are found in numerous dust and smoke contamination problems, including smoke particle transport in the lungs, particle clogging of heat exchangers in construction vehicles, industrial nanoparticle transport and filtration systems, and dust fouling of electronic systems and MEMS components. Dust fouling of equipment is of particular concern for potential human occupation on dusty planets, such as Mars. The discrete-element method presented in this paper can be used for prediction of aggregate structure and breakup, for prediction of the effect of aggregate formation on the bulk fluid flow, and for prediction of the effects of small-scale flow features (e.g., due to surface roughness or MEMS patterning) on the aggregate formation. After presentation of the overall computational structure, the forces and torques acting on the particles resulting from fluid motion, particle-particle collision, and adhesion under van der Waals forces are reviewed. The effect of various parameters of normal collision and adhesion of two particles are examined in detail. The method is then used to examine aggregate formation and particle clogging in pipe and channel flow.

Marshall, J.S. [School of Engineering, University of Vermont, 33 Colchecter Avenue, Burlington, Vermont 05405 (United States)], E-mail: jeffm@cems.uvm.edu

2009-03-20T23:59:59.000Z

432

Group and renormgroup symmetry of a simple model for nonlinear phenomena in optics, gas dynamics, and plasma theory  

Science Conference Proceedings (OSTI)

Lie-Backlund symmetries of the quasi-Chaplygin system of equations are found as linear forms in hodograph variables. These symmetries are used to obtain invariant solutions and to construct a symmetry group of a boundary value problem (renormgroup). ... Keywords: Boundary value problem, Invariant solution, Lie-Bäcklund symmetry, Quasi-Chaplygin media, Renormgroup operator

V.F Kovalev; V.V Pustovalov

1997-04-01T23:59:59.000Z

433

Wigner surmise for mixed symmetry classes in random matrix theory  

E-Print Network (OSTI)

We consider the nearest-neighbor spacing distributions of mixed random matrix ensembles interpolating between different symmetry classes, or between integrable and non-integrable systems. We derive analytical formulas for the spacing distributions of 2x2 or 4x4 matrices and show numerically that they provide very good approximations for those of random matrices with large dimension. This generalizes the Wigner surmise, which is valid for pure ensembles that are recovered as limits of the mixed ensembles. We show how the coupling parameters of small and large matrices must be matched depending on the local eigenvalue density.

Sebastian Schierenberg; Falk Bruckmann; Tilo Wettig

2012-02-16T23:59:59.000Z

434

Chiral symmetry breaking revisited: the gap equation with lattice ingredients  

Science Conference Proceedings (OSTI)

We study chiral symmetry breaking in QCD, using as ingredients in the quark gap equation recent lattice results for the gluon and ghost propagators. The Ansatz employed for the quark-gluon vertex is purely non-Abelian, introducing a crucial dependence on the ghost dressing function and the quark-ghost scattering amplitude. The numerical impact of these quantities is considerable: the need to invoke confinement explicitly is avoided, and the dynamical quark masses generated are of the order of 300 MeV. In addition, the pion decay constant and the quark condensate are computed, and are found to be in good agreement with phenomenology.

Aguilar, Arlene C. [Federal University of ABC, CCNH, Rua Santa Adelia 166, CEP 09210-170, Santo Andre (Brazil)

2011-05-23T23:59:59.000Z

435

Glass-like thermal transport in symmetry-broken clathrates.  

Science Conference Proceedings (OSTI)

We present the quantitative interpretation for the glass-like behavior of thermal conductivities {kappa}(T) for type-I clathrate compounds involving off-centered guest ions. It is shown that the dipole-dipole interaction generated in cage/guest-ion systems is crucial to reproduce the characteristics of thermal conductivities for these symmetry-broken clathrates. The above scenario also explains well the difference of {kappa}(T) between the p-type and the n-type {beta}-BGS found recently by K. Suekuni et al.

Kanashita, E.; Nakayama, T.; Toyota Phys. Chem. Res. Inst.

2009-01-01T23:59:59.000Z

436

Continuum discretization methods in a composite-particle scattering off a nucleus: the benchmark calculations  

E-Print Network (OSTI)

The direct comparison of two different continuum discretization methods towards the solution of a composite particle scattering off a nucleus is presented. The first approach -- the Continumm-Discretized Coupled Channel method -- is based on the differential equation formalism, while the second one -- the Wave-Packet Continuum Discretization method -- uses the integral equation formulation for the composite-particle scattering problem. As benchmark calculations we have chosen the deuteron off \

O. A. Rubtsova; V. I. Kukulin; A. M. Moro

2008-06-13T23:59:59.000Z

437

Fractured reservoir discrete feature network technologies. Final report, March 7, 1996 to September 30, 1998  

Science Conference Proceedings (OSTI)

This report summarizes research conducted for the Fractured Reservoir Discrete Feature Network Technologies Project. The five areas studied are development of hierarchical fracture models; fractured reservoir compartmentalization, block size, and tributary volume analysis; development and demonstration of fractured reservoir discrete feature data analysis tools; development of tools for data integration and reservoir simulation through application of discrete feature network technologies for tertiary oil production; quantitative evaluation of the economic value of this analysis approach.

Dershowitz, William S.; Einstein, Herbert H.; LaPoint, Paul R.; Eiben, Thorsten; Wadleigh, Eugene; Ivanova, Violeta

1998-12-01T23:59:59.000Z

438

Intrinsic transverse momentum and dynamical chiral symmetry breaking  

Science Conference Proceedings (OSTI)

We study the effect of QCD vacuum structure on the intrinsic transverse momentum distribution of partons in the nucleon at a low scale. The dynamical breaking of chiral symmetry is caused by non-perturbative interactions at distances of the order rho ~ 0.2 - 0.3 fm, much smaller than the typical nucleon size R ~ 1 fm, resulting in a two-scale picture of nucleon structure. Using an effective dynamical model based on chiral constituent quark degrees of freedom and the 1/N_c expansion (chiral quark-soliton model), we calculate the transverse momentum distribution of quarks and antiquarks at a low scale. The distribution of valence quarks is localized at p_T ~ 1/R. The distribution of flavor-singlet unpolarized sea quarks exhibits a power-like tail extending up to the chiral-symmetry-breaking scale 1/{rho}. A similar tail is present in the flavor-nonsinglet polarized sea. These features are model-independent and represent the imprint of the QCD vacuum on the nucleon's partonic structure. At the level of the nucleon's light-cone wave function, we show that sea quarks partly exist in correlated pairs of transverse size {rho} << R, analogous to short-range NN correlations in nuclei. We discuss the implications of our findings for the transverse momentum distributions in hard scattering processes (semi-inclusive DIS, Drell-Yan pair production) and possible experimental tests of the non-perturbative parton correlations induced by QCD vacuum structure.

Christian Weiss, Peter Schweitzer, Mark Strikman

2013-01-01T23:59:59.000Z

439

Conformal symmetry of gravity and the cosmological constant problem  

E-Print Network (OSTI)

In absence of matter Einstein gravity with a cosmological constant $\\La$ can be formulated as a scale-free theory depending only on the dimensionless coupling constant G \\Lambda where G is Newton constant. We derive the conformal field theory (CFT) and its improved stress-energy tensor that describe the dynamics of conformally flat perturbations of the metric. The CFT has the form of a constrained \\lambda \\phi^{4} field theory. In the cosmological framework the model describes the usual Friedmann-Robertson-Walker flat universe. The conformal symmetry of the gravity sector is broken by coupling with matter. The dimensional coupling constants G and \\Lambda are introduced by different terms in this coupling. If the vacuum of quantum matter fields respects the symmetry of the gravity sector, the vacuum energy has to be zero and the ``physical'' cosmological constant is generated by the coupling of gravity with matter. This could explain the tiny value of the observed energy density driving the accelerating expansion of the universe.

Mariano Cadoni

2006-06-29T23:59:59.000Z

440

The Lorentz extension as consequence of the family symmetry  

SciTech Connect

In this paper, we postulate an algebraic model to explain how the symmetry of three lepton species plays its role in the Lorentz extension. Inspired by the two-to-one mapping between the SL(2,C) group and the Lorentz group, we design a mapping between the SL(3,C) group, which displays the family symmetry, and a generalized Lorentz group. Following the conventional method, we apply the mapping results to the Dirac equation to discuss its transformation invariance, and it turns out that only when the vertex matrix {gamma}{sub {mu}} is extended to the combination c{sub 1}{gamma}{sub {mu}}+c{sub 2}{gamma}{sub 5}{gamma}{sub {mu}} can the Dirac-equation form be reserved. At the same time, we find that the Lorentz group has to be extended with an additional generator {gamma}{sub 5}. The generalized vertex matrix is helpful in understanding the axial-like form of weak interaction and the neutrino oscillations.

Wang Haijun [Center for Theoretical Physics and School of Physics, Jilin University, Changchun 130023 (China)

2008-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

Spin-Torsion, Braneworlds and Changing Symmetry in the Universe  

E-Print Network (OSTI)

In this thesis, we explore three phenomenological alternatives to the current paradigm of the standard inflationary big bang scenario. The three alternative themes are spin torsion (or Einstein-Cartan-Kibble-Sciama) theories, extra dimensions (braneworld cosmology) and changing global symmetry. In the spin torsion theories, we found new cosmological solutions with a cosmological constant as alternative to the standard scalar field driven inflationary scenario and we conclude that these toy models do not exhibit an inflationary phase. In the theme of extra dimensions, we discuss the dynamics of linearized scalar and tensor perturbations in an almost Friedmann-Robertson-Walker braneworld cosmology of Randall-Sundrum type II using the 1+3 covariant approach. We derive a complete set of frame-independent equations for the total matter variables, and a partial set of equations for the non-local variables, which arise from the projection of the Weyl tensor in the bulk. The latter equations are incomplete since there is no propagation equation for the non-local anisotropic stress. In the simplest approximation, we show the braneworld imprint as a correction to the power spectra for standard temperature and polarization anisotropies and similarly show that the tensor anisotropies are also insensitive to the high energy effects. Finally in the theme of changing global symmetry, we constructed a bounded isothermal solution embedded in an expanding Einstein de Sitter universe and showed that there is a possible phase transition in the far future.

Bernard Leong

2003-11-05T23:59:59.000Z

442

SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS  

Science Conference Proceedings (OSTI)

We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

2010-12-20T23:59:59.000Z

443

Graph-Theoretic Analysis of Discrete-Phase-Space States for ...  

Graph-Theoretic Analysis of Discrete-Phase-Space States for ... Data collected from devices and human condition may be used to forewarn of critical events such as

444

DISCRETE-FREQUENCY AND BROADBAND NOISE RADIATION FROM DIESEL ENGINE COOLING FANS.  

E-Print Network (OSTI)

??This effort focuses on measuring and predicting the discrete-frequency and broadband noise radiated by diesel engine cooling fans. Unsteady forces developed by the interaction of… (more)

Kim, Geon-Seok

2007-01-01T23:59:59.000Z

445

A discrete variable representation for electron-hydrogen atom scattering  

DOE Green Energy (OSTI)

A discrete variable representation (DVR) suitable for treating the quantum scattering of a low energy electron from a hydrogen atom is presented. The benefits of DVR techniques (e.g. the removal of the requirement of calculating multidimensional potential energy matrix elements and the availability of iterative sparse matrix diagonalization/inversion algorithms) have for many years been applied successfully to studies of quantum molecular scattering. Unfortunately, the presence of a Coulomb singularity at the electrically unshielded center of a hydrogen atom requires high radial grid point densities in this region of the scattering coordinate, while the presence of finite kinetic energy in the asymptotic scattering electron also requires a sufficiently large radial grid point density at moderate distances from the nucleus. The constraints imposed by these two length scales have made application of current DVR methods to this scattering event difficult.

Gaucher, L.F.

1994-08-01T23:59:59.000Z

446

Compression algorithm for discrete light-cone quantization  

E-Print Network (OSTI)

We adapt the compression algorithm of Weinstein, Auerbach, and Chandra from eigenvectors of spin lattice Hamiltonians to eigenvectors of light-front field-theoretic Hamiltonians. The latter are approximated by the standard discrete light-cone quantization technique, which provides a matrix representation of the Hamiltonian eigenvalue problem. The eigenvectors are represented as singular value decompositions of two-dimensional arrays, indexed by transverse and longitudinal momenta, and compressed by truncation of the decomposition. The Hamiltonian is represented by a rank-four tensor that is decomposed as a sum of contributions factorized into direct products of separate matrices for transverse and longitudinal interactions. The algorithm is applied to a model theory, to illustrate its use.

Xiao Pu; Sophia S. Chabysheva; John R. Hiller

2013-08-22T23:59:59.000Z

447

Public key Steganography Using Discrete Cross-Coupled Chaotic Maps  

E-Print Network (OSTI)

By cross-coupling two logistic maps a novel method is proposed for the public key steganography in JPEG image. Chaotic maps entail high complexity in the used algorithm for embedding secret data in a medium. In this paper, discrete cross- coupled chaotic maps are used to specifying the location of the different parts of the secret data in the image. Modifying JPEG format during compressing and decompressing, and also using public key enhanced difficulty of the algorithm. Simulation results show that in addition to excessive capacity, this method has high robustness and resistance against hackers and can be applicable in secret communication. Also the PSNR value is high compared to the other works.

Sodeif Ahadpour; Mahdiyeh Majidpour; Yaser Sadra

2012-11-01T23:59:59.000Z

448

Derivation of new 3D discrete ordinate equations  

Science Conference Proceedings (OSTI)

The Sn equations have been the workhorse of deterministic radiation transport calculations for many years. Here we derive two new angular discretizations of the 3D transport equation. The first set of equations, derived using Lagrange interpolation and collocation, retains the classical Sn structure, with the main difference being how the scattering source is calculated. Because of the formal similarity with the classical S n equations, it should be possible to modify existing computer codes to take advantage of the new formulation. In addition, the new S n-like equations correctly capture delta function scattering. The second set of equations, derived using a Galerkin technique, does not retain the classical Sn structure because the streaming term is not diagonal. However, these equations can be cast into a form similar to existing methods developed to reduce ray effects. Numerical investigation of both sets of equations is under way. (authors)

Ahrens, C. D. [Colorado School of Mines, Dept. of Applied Mathematics and Statistics, Program in Nuclear Science and Engineering, Golden, CO 80401-1887 (United States)

2012-07-01T23:59:59.000Z

449

Discrete pulse modulation strategies for high-frequency inverter systems  

SciTech Connect

High-performance high-frequency inverter systems for UPS applications represent a demanding application that cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant dc link inverter require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. This paper presents a controller that utilizes load current feed-forward strategy with a cost function current regulator to achieve excellent transient performance characteristics. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this paper focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well.

Venkataramanan, G. (Montana State Univ., Bozeman, MT (United States). Dept. of Electrical Engineering); Divan, D.M. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Electrical and Computer Engineering); Jahns, T.M. (General Electric Co., Schenectady, NY (United States))

1993-07-01T23:59:59.000Z

450

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

451

Symmetries and Conservation Laws for the 2D Ricci Flow Model  

E-Print Network (OSTI)

The paper aims to study the connection between symmetries and conservation laws for the 2D Ricci flow model. The procedure starts by obtaining a set of multipliers which generates conservation laws. Then, using a general relation which connects symmetries and conservation laws for whatever dynamical system, one determines symmetries related to a chosen multiplier. On this basis, new similarity solutions of the model, not yet discussed in literature, are highlighted.

Rodica Cimpoiasu

2011-08-27T23:59:59.000Z

452

Symmetries and Conservation Laws for the 2D Ricci Flow Model  

E-Print Network (OSTI)

The paper aims to study the connection between symmetries and conservation laws for the 2D Ricci flow model. The procedure starts by obtaining a set of multipliers which generates conservation laws. Then, using a general relation which connects symmetries and conservation laws for whatever dynamical system, one determines symmetries related to a chosen multiplier. On this basis, new similarity solutions of the model, not yet discussed in literature, are highlighted.

Cimpoiasu, Rodica

2011-01-01T23:59:59.000Z

453

Ramifications of the Nuclear Symmetry Energy for Neutron Stars, Nuclei, and Heavy-Ion Collisions  

E-Print Network (OSTI)

The pervasive role of the nuclear symmetry energy in establishing some nuclear static and dynamical properties, and in governing some attributes of neutron star properties is highlighted.

Andrew W. Steiner; Bao-An Li; Madappa Prakash

2007-11-29T23:59:59.000Z

454

Nuclear symmetry energy effects on liquid-gas phase transition in hot asymmetric nuclear matter  

E-Print Network (OSTI)

The liquid-gas phase transition in hot asymmetric nuclear matter is investigated within relativistic mean-field model using the density dependence of nuclear symmetry energy constrained from the measured neutron skin thickness of finite nuclei. We find symmetry energy has a significant influence on several features of liquid-gas phase transition. The boundary and area of the liquid-gas coexistence region, the maximal isospin asymmetry and the critical values of pressure and isospin asymmetry all of which systematically increase with increasing softness in the density dependence of symmetry energy. The critical temperature below which the liquid-gas mixed phase exists is found higher for a softer symmetry energy.

Bharat K. Sharma; Subrata Pal

2010-01-14T23:59:59.000Z

455

Ramifications of the Nuclear Symmetry Energy for Neutron Stars, Nuclei, and Heavy-Ion Collisions  

E-Print Network (OSTI)

The pervasive role of the nuclear symmetry energy in establishing some nuclear static and dynamical properties, and in governing some attributes of neutron star properties is highlighted.

Steiner, Andrew W; Prakash, Madappa

2007-01-01T23:59:59.000Z

456

An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System  

SciTech Connect

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.

Bernevig, B.A.; /Stanford U., Phys. Dept. /Santa Barbara, KITP; Orenstein, J.; /LBL, Berkeley /UC, Berkeley; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2007-01-22T23:59:59.000Z

457

An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System  

SciTech Connect

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.

Bernevig, Andrei

2010-02-10T23:59:59.000Z

458

Multicritical Symmetry Breaking and Naturalness of Slow Nambu-Goldstone Bosons  

E-Print Network (OSTI)

We investigate spontaneous global symmetry breaking in the absence of Lorentz invariance, and study technical Naturalness of Nambu-Goldstone (NG) modes whose dispersion relation exhibits a hierarchy of multicritical phenomena with Lifshitz scaling and dynamical exponents $z>1$. For example, we find NG modes with a technically natural quadratic dispersion relation which do not break time reversal symmetry and are associated with a single broken symmetry generator, not a pair. The mechanism is protected by an enhanced `polynomial shift' symmetry in the free-field limit.

Tom Griffin; Kevin T. Grosvenor; Petr Horava; Ziqi Yan

2013-08-27T23:59:59.000Z

459

Long distance symmetries for nuclear forces and the similarity renormalization group  

Science Conference Proceedings (OSTI)

In this work we study the emergence of long distance symmetries for nuclear forces within the framework of the similarity renormalization group approach.

Szpigel, S. [Faculdade de Computacao e Informatica, Universidade Presbiteriana Mackenzie, 01302-907, Sao Paulo - SP (Brazil); Timoteo, V. S. [Faculdade de Tecnologia, Universidade Estadual de Campinas, 13484-332, Limeira - SP (Brazil); Arriola, E. R. [Departamento de Fisica Atomica, Molecular y Nuclear and Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, E-18071, Granada (Spain)

2013-03-25T23:59:59.000Z

460

Central symmetry and antisymmetry of the microwave background inhomogeneities on Wilkinson Microwave Anisotropy Probe maps  

E-Print Network (OSTI)

We performed a visual and numeric analysis of the deviation of the microwave background temperature on WMAP maps. We proved that the microwave background inhomogeneities possess the property of the central symmetry resulting from the two kinds of central symmetry of the opposite signs. After the computer modeling we have established the relation between the coefficient of the central symmetry and the values of the symmetrical and antisymmetrical components of the deviation of the temperature. The obtained distribution of the symmetry coefficient on the map of the celestial sphere in Mollweide projection testifies on a contribution of both kinds of central symmetry which is approximately equal on the average in absolute magnitude but opposite by sign and where one kind of the central symmetry prevails on some sections of the celestial sphere and another kind - on the others. The average resulting value of the symmetry coefficient on the sections with angular measures less than 15-200 varies within the range from -50% to +50% with some prevalence of the antisymmetry - the average coefficient of the central symmetry for the whole celestial sphere is -4 +/- 1%. (antisymmetry 4%). Small scale structure of the distribution indicates that it is the result of the combined action of the mechanisms of the central symmetry and central antisymmetry, close to 100%.

Iurii Kudriavtcev; Dmitry A. Semenov

2010-08-24T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" 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

A Symmetry Breaking Model for X Chromosome Inactivation  

E-Print Network (OSTI)

In mammals, dosage compensation of X linked genes in female cells is achieved by inactivation of one of their two X chromosomes which is randomly chosen. The earliest steps in X-inactivation (XCI), namely the mechanism whereby cells count their X chromosomes and choose between two equivalent X, remain mysterious. Starting from the recent discovery of X chromosome colocalization at the onset of X-inactivation, we propose a Statistical Mechanics model of XCI, which is investigated by computer simulations and checked against experimental data. Our model describes how a `blocking factor' complex is self-assembled and why only one is formed out of many diffusible molecules, resulting in a spontaneous symmetry breaking (SB) in the binding to two identical chromosomes. These results are used to derive a scenario of biological implications describing all current experimental evidences, e.g., the importance of colocalization.

M. Nicodemi; A. Prisco

2008-01-17T23:59:59.000Z

462

Sneutrino dark matter: Symmetry protection and cosmic ray anomalies  

SciTech Connect

We present an R-parity conserving model of sneutrino dark matter within a Higgsphilic U(1){sup '} extension of the minimal supersymmetric standard model. In this theory, the {mu} parameter and light Dirac neutrino masses are generated naturally upon the breaking of the U(1){sup '} gauge symmetry. One of the right-handed sneutrinos is the lightest supersymmetric particle. The leptonic and hadronic decays of another sneutrino, taken to be the next-to-lightest superpartner, allow for a natural fit to the recent results reported by the PAMELA experiment. We perform a detailed calculation of the dark matter relic density in this scenario, and show that the model is consistent with the ATIC and Fermi LAT experiments.

Demir, Durmus A. [Department of Physics, Izmir Institute of Technology, IZTECH, TR35430 Izmir (Turkey); Everett, Lisa L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Frank, Mariana [Department of Physics, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6, (Canada); Selbuz, Levent [Department of Physics, Izmir Institute of Technology, IZTECH, TR35430 Izmir (Turkey); Department of Engineering Physics, Ankara University, TR06100 Ankara (Turkey); Turan, Ismail [Department of Physics, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6, (Canada); Ottawa-Carleton Institute of Physics, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6. (Canada)

2010-02-01T23:59:59.000Z

463

On symmetry and topological origin of Weyl particles  

E-Print Network (OSTI)

We suggest that the Weil spinors originate from the multi - component fermion fields. Those fields belong to the unusual theory that, presumably, exists at extremely high energies. In this theory there is no Lorentz symmetry. Moreover, complex numbers are not used in the description of its dynamics. Namely, the one - particle wave functions are real - valued, the functional integral that describes the second - quantised theory does not contain the imaginary unit as well. In the low energy effective theory the two - component Weil spinors appear. Their appearance is related to the Atiyah-Bott-Shapiro construction and to the expansion of the real matrix near the topologically protected nodes in three dimensional momentum space. The complex numbers entering ordinary quantum mechanics emerge together with the Weil fermions. In this pattern gauge fields and gravitational fields appear as certain collective excitations (of the original theory) experienced by the low - energy Weil fermions.

G. E. Volovik; M. A. Zubkov

2013-12-04T23:59:59.000Z

464

Dirty black holes: Symmetries at stationary non-static horizons  

E-Print Network (OSTI)

We establish that the Einstein tensor takes on a highly symmetric form near the Killing horizon of any stationary but non-static (and non-extremal) black hole spacetime. [This follows up on a recent article by the current authors, gr-qc/0402069, which considered static black holes.] Specifically, at any such Killing horizon -- irrespective of the horizon geometry -- the Einstein tensor block-diagonalizes into ``transverse'' and ``parallel'' blocks, and its transverse components are proportional to the transverse metric. Our findings are supported by two independent procedures; one based on the regularity of the on-horizon geometry and another that directly utilizes the elegant nature of a bifurcate Killing horizon. It is then argued that geometrical symmetries will severely constrain the matter near any Killing horizon. We also speculate on how this may be relevant to certain calculations of the black hole entropy.

A J M Medved; Damien Martin; Matt Visser

2004-03-05T23:59:59.000Z

465

The application of discrete event simulation and system dynamics in the logistics and supply chain context  

Science Conference Proceedings (OSTI)

Discrete event simulation (DES) and system dynamics (SD) are two modelling approaches widely used as decision support tools in logistics and supply chain management (LSCM). A widely held belief exists that SD is mostly used to model problems at a strategic ... Keywords: Comparison of methods, Discrete-event simulation, Logistics and supply chain management, Simulation modelling, System dynamics

Antuela A. Tako; Stewart Robinson

2012-03-01T23:59:59.000Z

466

The Discrete Event Concept as a Paradigm for the “Perception-Based Diagnosis” of Sachem  

Science Conference Proceedings (OSTI)

Sachem is an extensive large-scale real time knowledge-based system designed to monitor and diagnose blast furnaces. This paper aims at illustrating the way the concept of discrete event allowed the definition of a “perception-based diagnosis” ... Keywords: artificial intelligence, discrete event systems, fault diagnosis, knowledge-based systems, monitored control systems

Marc Le Goc; Claudia Frydman

2004-06-01T23:59:59.000Z

467

Rapid gravity and gravity gradiometry terrain corrections via an adaptive quadtree mesh discretization  

E-Print Network (OSTI)

Rapid gravity and gravity gradiometry terrain corrections via an adaptive quadtree mesh discretization Kristofer Davis1,2 M. Andy Kass1 Yaoguo Li1 1 Center for Gravity, Electrical, and Magnetic Studies of gravity gradiometry surveys utilising an adaptive quadtree mesh discretization. The data- and terrain

468

Utilization of Discretization method on the diagnosis of optic nerve disease  

Science Conference Proceedings (OSTI)

The optic nerve disease is an important disease that appears commonly in public. In this paper, we propose a hybrid diagnostic system based on discretization (quantization) method and classification algorithms including C4.5 decision tree classifier, ... Keywords: Artificial neural network, C4.5 decision tree classifier, Discretization method, Hybrid systems, Least square support vector machine, Optic nerve disease, VEP signals

Kemal Polat; Sad?k Kara; Ay?egül Güven; Salih Güne?

2008-09-01T23:59:59.000Z

469

Non-Abelian Groups in Optimization of Decision Diagrams Representations of Discrete Functions  

Science Conference Proceedings (OSTI)

This paper is devoted to the reduction of decision diagram (DD) representations of discrete functions by using the non-Abelian groups and Fourier DDs on these groups. The number of levels in a DD can be reduced through decomposition of the domain group ... Keywords: Fourier transform, decision diagrams, discrete functions, non-Abelian groups

Radomir S. Stankovi?

2001-05-01T23:59:59.000Z

470

Discrete spectrum distribution of the Landau Operator Perturbed by an Expanding Electric Potential  

E-Print Network (OSTI)

Under a perturbation by a decaying electric potential, the Landau Hamiltonian acquires some discrete eigenvalues between the Landau levels. We study the perturbation by an "expanding" electric potential $V(t^{-1}x)$, $t>0$, and derive a quasi-classical formula for the counting function of the discrete spectrum as $t\\to \\infty$.

Grigori Rozenblum; Alexander V. Sobolev

2007-11-14T23:59:59.000Z

471

Discrete spectrum distribution of the Landau Operator Perturbed by an Expanding Electric Potential  

E-Print Network (OSTI)

Under a perturbation by a decaying electric potential, the Landau Hamiltonian acquires some discrete eigenvalues between the Landau levels. We study the perturbation by an "expanding" electric potential $V(t^{-1}x)$, $t>0$, and derive a quasi-classical formula for the counting function of the discrete spectrum as $t\\to \\infty$.

Rozenblum, Grigori

2007-01-01T23:59:59.000Z

472

Verification of initial-state opacity in security applications of discrete event systems  

Science Conference Proceedings (OSTI)

In this paper, we formulate and analyze methodologies for verifying the notion of initial-state opacity in discrete event systems that are modeled as non-deterministic finite automata with partial observation on their transitions. A system is initial-state ... Keywords: Discrete event system, Formal methods in security analysis, Initial state estimation, Initial state estimator, Tracking in sensor network

Anooshiravan Saboori, Christoforos N. Hadjicostis

2013-10-01T23:59:59.000Z

473

Translation-invariant two-dimensional discrete wavelet transform on graphics processing units  

Science Conference Proceedings (OSTI)

The Discrete Wavelet Transform (DWT) is used in several signal and image processing applications. Due to the computational expense various approaches have been proposed. One approach is using graphics processing units (GPUs) as stream processors to speed ... Keywords: GPU, algorithme à trous, image processing, parallel discrete wavelet transform, shader

Dietmar Wippig; Bernd Klauer

2010-11-01T23:59:59.000Z

474

Discrete event modeling through a multi-formalism approach, from a user-oriented perspective  

Science Conference Proceedings (OSTI)

The hierarchy of formalism presented in this paper is part of an on going work in the development of a broad hierarchy of DEVS based formalisms. We introduce a hierarchy of formalisms with different temporal restrictions targeted to the discrete event ... Keywords: DEVS modeling methodology, discrete event modeling, multi-formalisms approach

Hernán P. Dacharry; Norbert Giambiasi

2007-03-01T23:59:59.000Z

475

Empirical evaluation of conservative and optimistic discrete event execution on cloud and VM platforms  

Science Conference Proceedings (OSTI)

Virtual machine (VM) technologies, especially those offered via Cloud platforms, present new dimensions with respect to performance and cost in executing parallel discrete event simulation (PDES) applications. Due to the introduction of overall cost ... Keywords: cloud computing, conservative simulation, optimistic simulation, parallel discrete event simulation, performance study, virtual machine

Srikanth B. Yoginath, Kalyan S. Perumalla

2013-05-01T23:59:59.000Z

476

On fluidization of discrete event models: observation and control of continuous Petri nets  

Science Conference Proceedings (OSTI)

As a preliminary overview, this work provides first a broad tutorial on the fluidization of discrete event dynamic models, an efficient technique for dealing with the classical state explosion problem. Even if named as continuous or fluid, the ... Keywords: Discrete event systems, Fluidization, Petri nets, Piecewise affine systems, System theory, Untimed and timed models

Manuel Silva; Jorge Júlvez; Cristian Mahulea; C. Renato Vázquez

2011-12-01T23:59:59.000Z

477

Well Posedness of the Initial Value Problem for Vertically Discretized Hydrostatic Equations  

Science Conference Proceedings (OSTI)

Vertically discretized linearized hydrostatic equations in hybrid coordinates are considered. The matrix of vertical structure, which depends on vertical discretization and determines the classification of the obtained system of time-dependent partial ... Keywords: initial value problems, numerical weather prediction, oscillatory matrices, well posedness

Andrei Bourchtein; Vladimir Kadychnikov

2003-01-01T23:59:59.000Z

478

Matching pursuit by undecimated discrete wavelet transform for non-stationary time series of arbitrary length  

Science Conference Proceedings (OSTI)

We describe how to formulate a matching pursuit algorithm which successively approximates a periodic non-stationary time series with orthogonal projections onto elements of a suitable dictionary. We discuss how to construct such dictionaries derived ... Keywords: Discrete wavelet transform, matching pursuit, undecimated discrete wavelet transform

A. T. Walden; A. Contreras Cristan

1998-08-01T23:59:59.000Z

479

Predictability of event occurrences in partially-observed discrete-event systems  

Science Conference Proceedings (OSTI)

This paper studies the problem of predicting occurrences of a significant event in a partially-observed discrete-event system. The predictability of occurrences of an event in a system is defined in the context of formal languages. The predictability ... Keywords: Diagnosis, Discrete-event systems, Prediction

Sahika Genc; Stéphane Lafortune

2009-02-01T23:59:59.000Z

480

Modeling and simulation of crowd using cellular discrete event systems theory  

Science Conference Proceedings (OSTI)

In this paper, we discuss how Cellular Discrete Event System Specification (Cell-DEVS) theory can be used in modeling and simulation of the crowd. We will show that the efficient cell update mechanism of Cell-DEVS allows for more efficient entity-based ... Keywords: cellular discrete event systems, crowd, pedestrian

Ronnie Farrell, Mohammad Moallemi, Sixuan Wang, Wang Xiang, Gabriel Wainer

2013-05-01T23:59:59.000Z

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481

Timed Discrete Event Control of Parallel Production Lines with Continuous Outputs  

Science Conference Proceedings (OSTI)

In this contribution we present an approach to formulate and solve certain scheduling tasks for hybrid systems using timed discrete event control methods. To demonstrate our approach, we consider a cyclically operated plant with parallel reactors using ... Keywords: Discrete event control, Hybrid systems, Multirate timed automata, Parallel production lines, Scheduling, Verification

Stephanie Geist; Dmitry Gromov; Jörg Raisch

2008-06-01T23:59:59.000Z

482

An algorithm for discrete booleans with applications to finite element modeling of complex systems  

Science Conference Proceedings (OSTI)

In this paper we describe a robust algorithm for three-dimensional boolean operations between boundary representation objects whose geometry is given by discrete (faceted) data. The algorithm presents a new approach for computing the intersection graph ... Keywords: Boolean, Discrete, Mesh, Remeshing, Sizing sources, Triangulation

B. Kaan Karamete; Saikat Dey; Eric L. Mestreau; Romain Aubry; Felipe A. Bulat-Jara

2013-06-01T23:59:59.000Z

483

Simulation on Discrete Fracture Network Using Flexible Voronoi Gridding  

E-Print Network (OSTI)

Fractured reservoirs are generally simulated using Warren and Root26 dual-porosity (DP) approach. The main assumption of this approach is that the geometry of fractures are uniformly distributed and interconnected in reservoirs. This may be true for many cases of naturally fractured reservoirs. However, for a large scale and disconnected fractured reservoirs, DP is often not applicable. Due to the latter case, it is necessary to have more sophisticated simulation studies which allow the fracture to be geometry explicitly represented into the static model using Discrete Fracture Network (DFN) approach. Most work on DFN grid model up to recently has been done with Delaunay tessellations. This research proposes an alternative technique to discretize the two-dimensional DFN using Voronoi diagrams, nevertheless applying the same DFN principles outlined in previous work. Through complicated procedures to generate DFN model, grid system based on Voronoi polygons has been developed. The procedure will force Voronoi edges follow the exact geometry of fractures. Furthermore, implementing the Voronoi diagrams allows the use of fewer polygons than the traditional Local Grid Refinement (LGR). And most importantly, due to the nature of the Voronoi polygons or locally orthogonal grids, the transmissibility calculations can be simplified and are more accurate than corner point formulation for non-square grid blocks. Finally, the main and most important goal of this study is to develop a black-oil Control Volume Finite Difference (CVFD) reservoir simulator that allows us to model DFN more realistically. One of the features of the developed simulator is the capability to model individual fractures with non-uniform aperture distribution, such as log-normally distributed apertures as shown using X-Ray CT scanner measurements. Prior to using the DFN simulator to model reservoirs with fractures and their apertures distribution, the simulator was validated against commercial simulators. The simulator provides results in close agreement with those of a reference finite-difference simulator in cases where direct comparisons are possible. Several simulations of synthetic DFN were presented to demonstrate the robustness of the Voronoi diagrams to represent fracture networks and its aperture distributions. In summary, the simulation of the DFN using the proposed approaches is capable to model both fractured and unfractured systems. However, the DFN model with Voronoi grids requires more efforts on building the grid model compared to other methods. Numerically, simulations of fractured systems are very challenging.

Syihab, Zuher

2009-12-01T23:59:59.000Z

484

The nuclear symmetry energy and stability of matter in neutron star  

E-Print Network (OSTI)

It is shown that behavior of the nuclear symmetry energy is the key quantity in the stability consideration in neutron star matter. The symmetry energy controls the position of crust-core transition and also may lead to new effects in the inner core of neutron star.

Sebastian Kubis

2006-11-23T23:59:59.000Z

485

Examining custodial symmetry in the Higgs sector of Georgi-Machacek model  

E-Print Network (OSTI)

We study consequences of custodial symmetry in the Higgs sector of the Georgi-Machacek (GM) model. We discuss how the 5-plet and 3-plet Higgs bosons classified under the custodial SU(2) symmetry are produced and decay at the CERN Large Hadron Collider. By determining their masses through proposed channels, we can test the mass degeneracy in each Higgs multiplet.

Chiang, Cheng-Wei

2013-01-01T23:59:59.000Z

486

Examining custodial symmetry in the Higgs sector of Georgi-Machacek model  

E-Print Network (OSTI)

We study consequences of custodial symmetry in the Higgs sector of the Georgi-Machacek (GM) model. We discuss how the 5-plet and 3-plet Higgs bosons classified under the custodial SU(2) symmetry are produced and decay at the CERN Large Hadron Collider. By determining their masses through proposed channels, we can test the mass degeneracy in each Higgs multiplet.

Cheng-Wei Chiang

2013-05-05T23:59:59.000Z

487

Nuclear Physics A 781 (2007) 317341 Symmetry energies, pairing energies, and mass  

E-Print Network (OSTI)

Nuclear Physics A 781 (2007) 317­341 Symmetry energies, pairing energies, and mass equations J of the respective mass equation since symmetry energies are related to the curvature of the nuclear mass surface.10.Dr; 21.10.Hw; 21.30.Fe; 21.60.-n Keywords: NUCLEAR STRUCTURE Z = 1­118; analyzed isobaric analog

O'Donnell, Tom

488

Metrics for Availability Analysis Using a Discrete Event Simulation Method  

Science Conference Proceedings (OSTI)

The system performance metric 'availability' is a central concept with respect to the concerns of a plant's operators and owners, yet it can be abstract enough to resist explanation at system levels. Hence, there is a need for a system-level metric more closely aligned with a plant's (or, more generally, a system's) raison d'etre. Historically, availability of repairable systems - intrinsic, operational, or otherwise - has been defined as a ratio of times. This paper introduces a new concept of availability, called endogenous availability, defined in terms of a ratio of quantities of product yield. Endogenous availability can be evaluated using a discrete event simulation analysis methodology. A simulation example shows that endogenous availability reduces to conventional availability in a simple series system with different processing rates and without intermediate storage capacity, but diverges from conventional availability when storage capacity is progressively increased. It is shown that conventional availability tends to be conservative when a design includes features, such as in - process storage, that partially decouple the components of a larger system.

Schryver, Jack C [ORNL; Nutaro, James J [ORNL; Haire, Marvin Jonathan [ORNL

2012-01-01T23:59:59.000Z

489

Discrete Momentum Mechanics and Faster Than Light Transition  

E-Print Network (OSTI)

In this work a new mechanics will be studied which is based on the hypothesis that the change of linear momentum of a particle happens as a discrete pulses. By using this hypothesis and by considering Newton's relation between energy and momentum, and the law of mass and energy conservation as a priori, the Einstein dispersion relation can be derived as a zero approximation without using Lorentz transformations. Other terms will be derived as a corrections to this relation. It will be shown that the effect of the corrections will be smaller and smaller with the increase of momentum. The work will offer an explanation of why the velocity of light seems to be constant regardless of the velocity of the source, and under which condition this will be changed. Also a prediction is made that faster than light transition could happen theoretically under certain conditions, and a nonzero mass photon can exist in nature. The work is purely classical in the sense that it doesn't involve any uncertainty relations.

Munir Al-Hashimi

2004-12-02T23:59:59.000Z

490

Wave-function entropy and dynamical-symmetry breaking in the interacting boson model  

E-Print Network (OSTI)

The degree of chaos in the Interacting Boson Model (IBM-1) is compared with what we call the "dynamical-symmetry content" of the system. The latter is represented by the information entropy of the eigenfunctions with respect to bases associated with dynamical symmetries of the IBM-1, and expresses thus the localization of actual eigenfunctions in these symmetry bases. The wave-function entropy is shown to be a sensitive tool for monitoring the processes of a single dynamical-symmetry breaking or transitions between two and more symmetries. For the IBM-1 hamiltonians studied here, the known features related to chaos, namely the dependence of chaotic measures on the hamiltonian parameters (position in the Casten triangle) and on the angular momentum, turn out to be correlated with the behaviour of the wave-function entropy. PACs 21.60.Fw; 05.45.+b

Pavel Cejnar; Jan Jolie

1998-02-25T23:59:59.000Z

491

Reaction-diffusion systems with constant diffusivities: conditional symmetries and form-preserving transformations  

E-Print Network (OSTI)

Q-conditional symmetries (nonclassical symmetries) for a general class of two-component reaction-diffusion systems with constant diffusivities are studied. Using the recently introduced notion of Q-conditional symmetries of the first type (R. Cherniha J. Phys. A: Math. Theor., 2010. vol. 43., 405207), an exhaustive list of reaction-diffusion systems admitting such symmetry is derived. The form-preserving transformations for this class of systems are constructed and it is shown that this list contains only non-equivalent systems. The obtained symmetries permit to reduce the reaction-diffusion systems under study to two-dimensional systems of ordinary differential equations and to find exact solutions. As a non-trivial example, multiparameter families of exact solutions are explicitly constructed for two nonlinear reaction-diffusion systems. A possible interpretation to a biologically motivated model is presented.

Roman Cherniha; Vasyl' Davydovych

2013-04-24T23:59:59.000Z

492

Discrete Ordinate Quadrature Selection for Reactor-based Eigenvalue Problems  

Science Conference Proceedings (OSTI)

In this paper we analyze the effect of various quadrature sets on the eigenvalues of several reactor-based problems, including a two-dimensional (2D) fuel pin, a 2D lattice of fuel pins, and a three-dimensional (3D) reactor core problem. While many quadrature sets have been applied to neutral particle discrete ordinate transport calculations, the Level Symmetric (LS) and the Gauss-Chebyshev product (GC) sets are the most widely used in production-level reactor simulations. Other quadrature sets, such as Quadruple Range (QR) sets, have been shown to be more accurate in shielding applications. In this paper, we compare the LS, GC, QR, and the recently developed linear-discontinuous finite element (LDFE) sets, as well as give a brief overview of other proposed quadrature sets. We show that, for a given number of angles, the QR sets are more accurate than the LS and GC in all types of reactor problems analyzed (2D and 3D). We also show that the LDFE sets are more accurate than the LS and GC sets for these problems. We conclude that, for problems where tens to hundreds of quadrature points (directions) per octant are appropriate, QR sets should regularly be used because they have similar integration properties as the LS and GC sets, have no noticeable impact on the speed of convergence of the solution when compared with other quadrature sets, and yield more accurate results. We note that, for very high-order scattering problems, the QR sets exactly integrate fewer angular flux moments over the unit sphere than the GC sets. The effects of those inexact integrations have yet to be analyzed. We also note that the LDFE sets only exactly integrate the zeroth and first angular flux moments. Pin power comparisons and analyses are not included in this paper and are left for future work.

Jarrell, Joshua J [ORNL; Evans, Thomas M [ORNL; Davidson, Gregory G [ORNL

2013-01-01T23:59:59.000Z

493

A covariant causal set approach to discrete quantum gravity  

E-Print Network (OSTI)

A covariant causal set (c-causet) is a causal set that is invariant under labeling. Such causets are well-behaved and have a rigid geometry that is determined by a sequence of positive integers called the shell sequence. We first consider the microscopic picture. In this picture, the vertices of a c-causet have integer labels that are unique up to a label isomorphism. This labeling enables us to define a natural metric $d(a,b)$ between time-like separated vertices $a$ and $b$. The time metric $d(a,b)$ results in a natural definition of a geodesic from $a$ to $b$. It turns out that there can be $n\\ge 1$ such geodesics. Letting $a$ be the origin (the big bang), we define the curvature $K(b)$ of $b$ to be $n-1$. Assuming that particles tend to move along geodesics, $K(b)$ gives the tendency that vertex $b$ is occupied. In this way, the mass distribution is determined by the geometry of the c-causet. We next consider the macroscopic picture which describes the growth process of c-causets. We propose that this process is governed by a quantum dynamics given by complex amplitudes. At present, these amplitudes are unknown. But if they can be found, they will determine the (approximate) geometry of the c-causet describing our particular universe. As an illustration, we present a simple example of an amplitude process that may have physical relevance. We also give a discrete analogue of Einstein's field equations.

Stan Gudder

2013-11-15T23:59:59.000Z

494

Dense Packings of Superdisks and the Role of Symmetry  

E-Print Network (OSTI)

We construct the densest known two-dimensional packings of superdisks in the plane whose shapes are defined by |x^(2p) + y^(2p)| 0.5, with the circular-disk case p = 1) and concave-shaped particles (0 Donev, Torquato and Stillinger, J. Comput. Phys. 202 (2005) 737] suggest exact constructions of the densest known packings. We find that the packing density (covering fraction of the particles) increases dramatically as the particle shape moves away from the "circular-disk" point (p = 1). In particular, we find that the maximal packing densities of superdisks for certain p 6 = 1 are achieved by one of the two families of Bravais lattice packings, which provides additional numerical evidence for Minkowski's conjecture concerning the critical determinant of the region occupied by a superdisk. Moreover, our analysis on the generated packings reveals that the broken rotational symmetry of superdisks influences the packing characteristics in a non-trivial way. We also propose an analytical method to construct dense packings of concave superdisks based on our observations of the structural properties of packings of convex superdisks.

Y. Jiao; F. H. Stillinger; S. Torquato

2007-12-04T23:59:59.000Z

495

Large N Volume Independence and an Emergent Fermionic Symmetry  

E-Print Network (OSTI)

Large-N volume independence in circle-compactified QCD with N_f \\geq 1 adjoint Weyl fermions implies the absence of any phase transitions as the radius is dialed to arbitrarily small values. This class of theories are believed to possess a Hagedorn density of hadronic states. It turns out that these properties are in apparent tension with each other, because a Hagedorn density of states typically implies a phase transition at some finite radius. This tension is resolved if there are degeneracies between the spectra of bosonic and fermionic states, as happens in the N_f=1 supersymmetric case. Resolution of the tension for N_f>1 then suggests the emergence of a fermionic symmetry at large N, where there is no supersymmetry. We can escape the Coleman-Mandula theorem since the N=\\infty theory is free, with a trivial S-matrix. We show an example of such a spectral degeneracy in a non-supersymmetric toy example which has a Hagedorn spectrum.

Basar, Gokce; Dorigoni, Daniele; Unsal, Mithat

2013-01-01T23:59:59.000Z

496

Flavor symmetry in the large N{sub c} limit  

SciTech Connect

An essential difference between two-flavor and three-flavor descriptions of baryons in large N{sub c} QCD is discussed in detail. For N{sub c}{ge}3 a state with the SU(3) flavor quantum numbers of the proton must contain a number of strange quarks n{sub s}{ge}(N{sub c}{minus}3)/3, while a state with no strange quarks must have extra hypercharge Y{minus}1 = 3/N{sub c}{minus}1. The extra strangeness or extra hypercharge which vanishes for N{sub c} = 3 is spurious for the physical proton. This problem does not arise in two-flavor QCD, where the flavor-SU(2) Skyrmion may give a good approximation for nucleon-pion physics at low energies below strangeness threshold. But any nucleon model with SU(3) flavor symmetry which is interpreted as arising from the large N{sub c} limit in QCD can lead to erroneous conclusions about the spin and flavor structure of the proton. 12 refs.

Karl, G. [Guelph Univ., ON (Canada). Dept. of Physics]|[Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory; Lipkin, H.J. [Weizmann Inst. of Science, Rehovoth (Israel). Dept. of Physics]|[Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory

1991-12-31T23:59:59.000Z

497

Positive and Negative Energy Symmetry and the Cosmological Constant Problem  

E-Print Network (OSTI)

The action for gravity and the standard model includes, as well as the positive energy fermion and boson fields, negative energy fields. The Hamiltonian for the action leads through a positive and negative energy symmetry of the vacuum to a cancellation of the zero-point vacuum energy and a vanishing cosmological constant in the presence of a gravitational field solving the cosmological constant problem. To guarantee the quasi-stability of the vacuum, we postulate a positive energy sector and a negative energy sector in the universe which are identical copies of the standard model. They interact only weakly through gravity. As in the case of antimatter, the negative energy matter is not found naturally on Earth or in the universe. A positive energy spectrum and a consistent unitary field theory for a pseudo-Hermitian Hamiltonian is obtained by demanding that the pseudo-Hamiltonian is ${\\cal P}{\\cal T}$ symmetric. The quadratic divergences in the two-point vacuum fluctuations and the self-energy of a scalar field are removed. The finite scalar field self-energy can avoid the Higgs hierarchy problem in the standard model.

J. W. Moffat

2006-10-13T23:59:59.000Z

498

Multipole expansions and Fock symmetry of the Hydrogen atom  

E-Print Network (OSTI)

The main difficulty in utilizing the O(4) symmetry of the Hydrogen atom in practical calculations is the dependence of the Fock stereographic projection on energy. This is due to the fact that the wave functions of the states with different energies are proportional to the hyperspherical harmonics (HSH) corresponding to different points on the hypersphere. Thus, the calculation of the matrix elements reduces to the problem of re-expanding HSH in terms of HSH depending on different points on the hypersphere. We solve this problem by applying the technique of multipole expansions for four-dimensional HSH. As a result, we obtain the multipole expansions whose coefficients are the matrix elements of the boost operator taken between hydrogen wave functions (i.e. hydrogen form-factors). The explicit expressions for those coefficients are derived. It is shown that the hydrogen matrix elements can be presented as derivatives of an elementary function. Such an operator representation is convenient for the derivation of recurrency relations connecting matrix elements between states corresponding to different values of the quantum numbers $n$ and $l$.

A. V. Meremianin; J-M. Rost

2006-06-27T23:59:59.000Z

499

Results from a discrete fracture network model of a Hot Dry Rock system  

Science Conference Proceedings (OSTI)

The work described represents a move towards better representations of the natural fracture system. The discrete fracture network model used during the study was the NAPSAC code (Grindrod et al, 1992). The goals of the work were to investigate the application of discrete fracture network models to Hot Dry Rock systems, increase the understanding of the basic thermal extraction process and more specifically the understanding of the Rosemanowes Phase 2B system. The aim in applying the work to the Rosemanowes site was to use the discrete fracture network approach to integrate a diverse set of field measurements into as simple a model as possible.

Lanyon, G.W.; Batchelor, A.S.; Ledingham, P.

1993-01-28T23:59:59.000Z

500

Discrete-time GeoX/G/1 queue with unreliable server and multiple adaptive delayed vacations  

Science Conference Proceedings (OSTI)

In this paper we consider a discrete-time Geo^X/G/1 queue with unreliable server and multiple adaptive delayed vacations policy in which the vacation time, service time, repair time and the delayed time all follow arbitrary discrete distribution. By ... Keywords: Discrete-time queueing model, Multiple adaptive delayed vacation, Stochastic decomposition, Transient and steady-state distributions, Unreliable, primary, secondary

Yinghui Tang; Xi Yun; Shujuan Huang

2008-10-01T23:59:59.000Z