p-systems in local Noether lattices
Directory of Open Access Journals (Sweden)
E. W. Johnson
1994-01-01
Full Text Available In this paper we introduce the concept of a p-system in a local Noether lattice and obtain several characterizations of these elements. We first obtain a topological characterization and then a characterization in terms of the existence of a certain type of decreasing sequence of elements. In addition, p-systems are characterized in quotient lattices and completions.
Localized structures in Kagome lattices
Energy Technology Data Exchange (ETDEWEB)
Saxena, Avadh B [Los Alamos National Laboratory; Bishop, Alan R [Los Alamos National Laboratory; Law, K J H [UNIV OF MASSACHUSETTS; Kevrekidis, P G [UNIV OF MASSACHUSETTS
2009-01-01
We investigate the existence and stability of gap vortices and multi-pole gap solitons in a Kagome lattice with a defocusing nonlinearity both in a discrete case and in a continuum one with periodic external modulation. In particular, predictions are made based on expansion around a simple and analytically tractable anti-continuum (zero coupling) limit. These predictions are then confirmed for a continuum model of an optically-induced Kagome lattice in a photorefractive crystal obtained by a continuous transformation of a honeycomb lattice.
A measure of localization properties of one-dimensional single electron lattice systems
Energy Technology Data Exchange (ETDEWEB)
Gong, Longyan, E-mail: lygong@njupt.edu.cn [Information Physics Research Center and Department of Applied Physics, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Li, Wenjia [Information Physics Research Center and Department of Applied Physics, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); Zhao, Shengmei, E-mail: zhaosm@njupt.edu.cn [Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); Cheng, Weiwen, E-mail: wwcheng@njupt.edu.cn [Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)
2016-01-08
We propose a novel quantity to measure the degree of localization properties of various types of one-dimension single electron states. The quantity includes information about the spatial variation of probability density of quantum states. Numerical results show that it can distinguish localized states from delocalized ones, so it can be used as a fruitful index to monitor the localization–delocalization transition. Comparing with existing measures, such as geometric average density of states, inverse participation ratio, and quantum information entropies, our proposed quantity has some advantages over them. - Highlights: • A novel quantity is proposed to measure the degree of localization. • It includes information about the spatial variation of probability density. • It is a fruitful index to monitor the localization–delocalization transition.
Locality properties of Neuberger's lattice Dirac operator
Hernández, Pilar; Jansen, Karl; Lüscher, Martin
1999-07-01
The gauge covariant lattice Dirac operator D which has recently been proposed by Neuberger satisfies the Ginsparg-Wilson relation and thus preserves chiral symmetry. The operator also avoids a doubling of fermion species, but its locality properties are not obvious. We now prove that D is local (with exponentially decaying tails) if the gauge field is sufficiently smooth at the scale of the cutoff. Further analytic and numerical studies moreover suggest that the locality of the operator is in fact guaranteed under far more general conditions.
Local Scale Transformations on the Lattice with Tensor Network Renormalization
Evenbly, G.; Vidal, G.
2016-01-01
Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.
Local Scale Transformations on the Lattice with Tensor Network Renormalization.
Evenbly, G; Vidal, G
2016-01-29
Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.
Fast simulation of lattice systems
DEFF Research Database (Denmark)
Bohr, H.; Kaznelson, E.; Hansen, Frank;
1983-01-01
A new computer system with an entirely new processor design is described and demonstrated on a very small trial lattice. The new computer simulates systems of differential equations of the order of 104 times faster than present day computers and we describe how the machine can be applied to lattice...
Lattice models of ionic systems
Kobelev, Vladimir; Kolomeisky, Anatoly B.; Fisher, Michael E.
2002-05-01
A theoretical analysis of Coulomb systems on lattices in general dimensions is presented. The thermodynamics is developed using Debye-Hückel theory with ion-pairing and dipole-ion solvation, specific calculations being performed for three-dimensional lattices. As for continuum electrolytes, low-density results for simple cubic (sc), body-centered cubic (bcc), and face-centered cubic (fcc) lattices indicate the existence of gas-liquid phase separation. The predicted critical densities have values comparable to those of continuum ionic systems, while the critical temperatures are 60%-70% higher. However, when the possibility of sublattice ordering as well as Debye screening is taken into account systematically, order-disorder transitions and a tricritical point are found on sc and bcc lattices, and gas-liquid coexistence is suppressed. Our results agree with recent Monte Carlo simulations of lattice electrolytes.
Entropy of Open Lattice Systems
Derrida, B.; Lebowitz, J. L.; Speer, E. R.
2007-03-01
We investigate the behavior of the Gibbs-Shannon entropy of the stationary nonequilibrium measure describing a one-dimensional lattice gas, of L sites, with symmetric exclusion dynamics and in contact with particle reservoirs at different densities. In the hydrodynamic scaling limit, L → ∞, the leading order ( O( L)) behavior of this entropy has been shown by Bahadoran to be that of a product measure corresponding to strict local equilibrium; we compute the first correction, which is O(1). The computation uses a formal expansion of the entropy in terms of truncated correlation functions; for this system the k th such correlation is shown to be O( L - k+1). This entropy correction depends only on the scaled truncated pair correlation, which describes the covariance of the density field. It coincides, in the large L limit, with the corresponding correction obtained from a Gaussian measure with the same covariance.
Entanglement scaling in lattice systems
Energy Technology Data Exchange (ETDEWEB)
Audenaert, K M R [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom); Cramer, M [QOLS, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Eisert, J [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom); Plenio, M B [Institute for Mathematical Sciences, Imperial College London, 53 Prince' s Gate, Exhibition Road, London SW7 2PG (United Kingdom)
2007-05-15
We review some recent rigorous results on scaling laws of entanglement properties in quantum many body systems. More specifically, we study the entanglement of a region with its surrounding and determine its scaling behaviour with its size for systems in the ground and thermal states of bosonic and fermionic lattice systems. A theorem connecting entanglement between a region and the rest of the lattice with the surface area of the boundary between the two regions is presented for non-critical systems in arbitrary spatial dimensions. The entanglement scaling in the field limit exhibits a peculiar difference between fermionic and bosonic systems. In one-spatial dimension a logarithmic divergence is recovered for both bosonic and fermionic systems. In two spatial dimensions in the setting of half-spaces however we observe strict area scaling for bosonic systems and a multiplicative logarithmic correction to such an area scaling in fermionic systems. Similar questions may be posed and answered in classical systems.
Diffusion and transport in locally disordered driven lattices
Wulf, Thomas; Schmelcher, Peter
2016-01-01
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non Gaussian particle density evolution. As the key underlying mechanism we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of transport for global disorder.
Diffusion and transport in locally disordered driven lattices
Wulf, Thomas; Okupnik, Alexander; Schmelcher, Peter
2016-09-01
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.
Diffusion and transport in locally disordered driven lattices.
Wulf, Thomas; Okupnik, Alexander; Schmelcher, Peter
2016-09-01
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.
Diffusion and transport in locally disordered driven lattices
Energy Technology Data Exchange (ETDEWEB)
Wulf, Thomas, E-mail: Thomas.Wulf@physnet.uni-hamburg.de; Okupnik, Alexander [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Schmelcher, Peter, E-mail: Peter.Schmelcher@physnet.uni-hamburg.de [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)
2016-09-15
We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.
Local dimension and finite time prediction in coupled map lattices
Indian Academy of Sciences (India)
P Muruganandam; G Francisco
2005-03-01
Forecasting, for obvious reasons, often become the most important goal to be achieved. For spatially extended systems (e.g. atmospheric system) where the local nonlinearities lead to the most unpredictable chaotic evolution, it is highly desirable to have a simple diagnostic tool to identify regions of predictable behaviour. In this paper, we discuss the use of the bred vector (BV) dimension, a recently introduced statistics, to identify the regimes where a finite time forecast is feasible. Using the tools from dynamical systems theory and Bayesian modelling, we show the finite time predictability in two-dimensional coupled map lattices in the regions of low BV dimension.
On the existence of localized excitations in nonlinear hamiltonian lattices
Flach, S
1994-01-01
We consider time-periodic nonlinear localized excitations (NLEs) on one-dimensional translationally invariant Hamiltonian lattices with arbitrary finite interaction range and arbitrary finite number of degrees of freedom per unit cell. We analyse a mapping of the Fourier coefficients of the NLE solution. NLEs correspond to homoclinic points in the phase space of this map. Using dimensionality properties of separatrix manifolds of the mapping we show the persistence of NLE solutions under perturbations of the system, provided NLEs exist for the given system. For a class of nonintegrable Fermi-Pasta-Ulam chains we rigorously prove the existence of NLE solutions.
Local gauge symmetry on optical lattices?
Liu, Yuzhi; Tsai, Shan-Wen
2012-01-01
The versatile technology of cold atoms confined in optical lattices allows the creation of a vast number of lattice geometries and interactions, providing a promising platform for emulating various lattice models. This opens the possibility of letting nature take care of sign problems and real time evolution in carefully prepared situations. Up to now, experimentalists have succeeded to implement several types of Hubbard models considered by condensed matter theorists. In this proceeding, we discuss the possibility of extending this effort to lattice gauge theory. We report recent efforts to establish the strong coupling equivalence between the Fermi Hubbard model and SU(2) pure gauge theory in 2+1 dimensions by standard determinantal methods developed by Robert Sugar and collaborators. We discuss the possibility of using dipolar molecules and external fields to build models where the equivalence holds beyond the leading order in the strong coupling expansion.
Equilibration via Gaussification in Fermionic Lattice Systems
Gluza, M.; Krumnow, C.; Friesdorf, M.; Gogolin, C.; Eisert, J.
2016-11-01
In this Letter, we present a result on the nonequilibrium dynamics causing equilibration and Gaussification of quadratic noninteracting fermionic Hamiltonians. Specifically, based on two basic assumptions—clustering of correlations in the initial state and the Hamiltonian exhibiting delocalizing transport—we prove that non-Gaussian initial states become locally indistinguishable from fermionic Gaussian states after a short and well controlled time. This relaxation dynamics is governed by a power-law independent of the system size. Our argument is general enough to allow for pure and mixed initial states, including thermal and ground states of interacting Hamiltonians on large classes of lattices as well as certain spin systems. The argument gives rise to rigorously proven instances of a convergence to a generalized Gibbs ensemble. Our results allow us to develop an intuition of equilibration that is expected to be more generally valid and relates to current experiments of cold atoms in optical lattices.
Localized Basis for Effective Lattice Hamiltonians Lattice Wannier Functions
Rabe, K M
1994-01-01
A systematic method is presented for constructing effective Hamiltonians for general phonon-related structural transitions. The key feature is the application of group theoretical methods to identify the subspace in which the effective Hamiltonian acts and construct for it localized basis vectors, which are the analogue of electronic Wannier functions. The results of the symmetry analysis for the perovskite, rocksalt, fluorite and A15 structures and the forms of effective Hamiltonians for the ferroelectric transition in $PbTiO_3$ and $BaTiO_3$, the oxygen-octahedron rotation transition in $SrTiO_3$, the Jahn-Teller instability in $La_{1-x}(Ca,Sr,Ba)_xMnO_3$ and the antiferroelectric transition in $PbZrO_3$ are discussed. For the oxygen- octahedron rotation transition in $SrTiO_3$, this method provides an alternative to the rotational variable approach which is well behaved throughout the Brillouin zone. The parameters appearing in the Wannier basis vectors and in the effective Hamiltonian, given by the corres...
Intrinsic Localized Modes in Optical Photonic Lattices and Arrays
Christodoulides, Demetrios
Discretizing light behavior requires optical elements that can confine optical energy at distinct sites. One possible scenario in implementing such arrangements is to store energy within low loss high Q-microcavities and then allow photon exchange between such components in time. This scheme requires high-contrast dielectric elements that became available with the advent of photonic crystal technologies. Another possible avenue where such light discretization can be directly observed and studied is that based on evanescently coupled waveguide arrays. As indicated in several studies, discrete systems open up whole new directions in terms of modifying light transport properties. One such example is that of discrete solitons. By nature, discrete solitons represent self-trapped wavepackets in nonlinear periodic structures and result from the interplay between lattice diffraction (or dispersion) and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one- and two-dimensional nonlinear waveguide arrays. In recent years such photonic lattices have been implemented or induced in a variety of material systems, including those with cubic (Kerr), quadratic, photorefractive, and liquid-crystal nonlinearities. In all cases the underlying periodicity or discreteness can lead to new families of optical solitons that have no counterpart whatsoever in continuous systems. Interestingly, these results paved the way for observations in other physical systems obeying similar evolution equations like Bose-Einstein condensates. New developments in laser writing ultrashort femtosecond laser pulses, now allow the realization of all-optical switching networks in fully 3D environments using nonlinear discrete optics. Using this approach all-optical routing can be achieved using blocking operations. The spatio-temporal evolution of optical pulses in both normally and anomalously dispersive arrays can lead to novel schemes for mode
Quantum Entanglement in Optical Lattice Systems
2015-02-18
SECURITY CLASSIFICATION OF: Optical lattice systems provide an ideal platform for investigating entanglement because of their unprecedented level of...ABSTRACT Final report for ARO grant entitled "Quantum Entanglement in Optical Lattice Systems" Report Title Optical lattice systems provide an ideal ...2010): 0. doi: 10.1103/PhysRevA.82.063612 D. Blume, K. Daily. Breakdown of Universality for Unequal-Mass Fermi Gases with Infinite Scattering Length
LocalMove: computing on-lattice fits for biopolymers
Ponty, Y.; Istrate, R.; Porcelli, E.; Clote, P.
2008-01-01
Given an input Protein Data Bank file (PDB) for a protein or RNA molecule, LocalMove is a web server that determines an on-lattice representation for the input biomolecule. The web server implements a Markov Chain Monte-Carlo algorithm with simulated annealing to compute an approximate fit for either the coarse-grain model or backbone model on either the cubic or face-centered cubic lattice. LocalMove returns a PDB file as output, as well as dynamic movie of 3D images of intermediate conformations during the computation. The LocalMove server is publicly available at http://bioinformatics.bc.edu/clotelab/localmove/. PMID:18556754
Anderson localization in optical lattices with speckle disorder
Energy Technology Data Exchange (ETDEWEB)
Sucu, Serpil; Aktas, Saban; Okan, S. Erol [Department of Physics, Trakya University, 22030 Edirne (Turkey); Akdeniz, Zehra [Piri Reis University, 34940 Tuzla-Istanbul (Turkey); Vignolo, Patrizia [Universite de Nice-Sophia Antipolis, Institut non Lineaire de Nice, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France)
2011-12-15
We study the localization properties of noninteracting waves propagating in a speckle-like potential superposed on a one-dimensional lattice. Using a combined decimation-renormalization procedure, we estimate the localization length for a tight-binding Hamiltonian where site energies are square-sinc-correlated random variables. By decreasing the width of the correlation function, the disorder patterns approach a {delta}-correlated disorder, and the localization length becomes almost energy independent in the strong disorder limit. We show that this regime can be reached for a size of the speckle grains on the order of (lower than) four lattice steps.
Excitation Thresholds for Nonlinear Localized Modes on Lattices
Weinstein, M I
1999-01-01
Breathers are spatially localized and time periodic solutions of extended Hamiltonian dynamical systems. In this paper we study excitation thresholds for (nonlinearly dynamically stable) ground state breather or standing wave solutions for networks of coupled nonlinear oscillators and wave equations of nonlinear Schrödinger (NLS) type. Excitation thresholds are rigorously characterized by variational methods. The excitation threshold is related to the optimal (best) constant in a class of discr ete interpolation inequalities related to the Hamiltonian energy. We establish a precise connection among $d$, the dimensionality of the lattice, $2\\sigma+1$, the degree of the nonlinearity and the existence of an excitation threshold for discrete nonlinear Schrödinger systems (DNLS). We prove that if $\\sigma\\ge 2/d$, then ground state standing waves exist if and only if the total power is larger than some strictly positive threshold, the context of DNLS. We also discuss upper and lower bounds for excitation threshol...
Measurement-Induced Localization of an Ultracold Lattice Gas
Patil, Y. S.; Chakram, S.; Vengalattore, M.
2015-10-01
The process of measurement can modify the state of a quantum system and its subsequent evolution. Here, we demonstrate the control of quantum tunneling in an ultracold lattice gas by the measurement backaction imposed by the act of imaging the atoms, i.e., light scattering. By varying the rate of light scattering from the atomic ensemble, we show the crossover from the weak measurement regime, where position measurements have little influence on tunneling dynamics, to the strong measurement regime, where measurement-induced localization causes a large suppression of tunneling—a manifestation of the quantum Zeno effect. Our study realizes an experimental demonstration of the paradigmatic Heisenberg microscope and sheds light on the implications of measurement on the coherent evolution of a quantum system.
Localization phenomena in interacting Rydberg lattice gases with position disorder
Marcuzzi, Matteo; Barredo, Daniel; de Léséleuc, Sylvain; Labuhn, Henning; Lahaye, Thierry; Browaeys, Antoine; Levi, Emanuele; Lesanovsky, Igor
2016-01-01
Disordered systems provide paradigmatic instances of ergodicity breaking and localization phenomena. Here we explore the dynamics of excitations in a system of Rydberg atoms held in optical tweezers. The finite temperature produces an intrinsic uncertainty in the atomic positions, which translates into quenched correlated disorder in the interatomic interaction strengths. In a simple approach, the dynamics in the many-body Hilbert space can be understood in terms of a one-dimensional Anderson-like model with disorder on every other site, featuring both localized and delocalized states. We conduct an experiment on an eight-atom chain and observe a clear suppression of excitation transfer. Our experiment accesses a regime which is described by a two-dimensional Anderson model on a "trimmed" square lattice. Our results thus provide a concrete example in which the absence of excitation propagation in a many-body system is directly related to Anderson-like localization in the Hilbert space, which is believed to be...
Quasilocal charges in integrable lattice systems
Ilievski, Enej; Medenjak, Marko; Prosen, Tomaž; Zadnik, Lenart
2016-06-01
We review recent progress in understanding the notion of locality in integrable quantum lattice systems. The central concept concerns the so-called quasilocal conserved quantities, which go beyond the standard perception of locality. Two systematic procedures to rigorously construct families of quasilocal conserved operators based on quantum transfer matrices are outlined, specializing on anisotropic Heisenberg XXZ spin-1/2 chain. Quasilocal conserved operators stem from two distinct classes of representations of the auxiliary space algebra, comprised of unitary (compact) representations, which can be naturally linked to the fusion algebra and quasiparticle content of the model, and non-unitary (non-compact) representations giving rise to charges, manifestly orthogonal to the unitary ones. Various condensed matter applications in which quasilocal conservation laws play an essential role are presented, with special emphasis on their implications for anomalous transport properties (finite Drude weight) and relaxation to non-thermal steady states in the quantum quench scenario.
Many body localization in two dimensional square and triangular lattices
Gonzalez-Garcia, L; Paredes, R
2016-01-01
Ultracold interacting Bose atoms placed in disordered two dimensional optical lattices with square and triangular symmetries are found to be localized above a certain disorder strength amplitude. From a Gross-Pitaevskii mean analysis we determine the localization length as a function of the disorder strength and investigate the energy spectrum in terms of the disorder magnitude. We found that the localization length is observed to decrease faster in triangular geometries than in square ones. In the presence of a harmonic confinement localization is observed at the center of the trap. The analysis of the energy spectrum reveals that discrete energy levels acquire a finite width that is always smaller than the distance among energy levels.
Localized modes in dissipative lattice media: an overview.
He, Yingji; Malomed, Boris A; Mihalache, Dumitru
2014-10-28
We give an overview of recent theoretical studies of the dynamics of one- and two-dimensional spatial dissipative solitons in models based on the complex Ginzburg-Landau equations with the cubic-quintic combination of loss and gain terms, which include imaginary, real or complex spatially periodic potentials. The imaginary potential represents periodic modulation of the local loss and gain. It is shown that the effective gradient force, induced by the inhomogeneous loss distribution, gives rise to three generic propagation scenarios for one-dimensional dissipative solitons: transverse drift, persistent swing motion, and damped oscillations. When the lattice-average loss/gain value is zero, and the real potential has spatial parity opposite to that of the imaginary component, the respective complex potential is a realization of the parity-time symmetry. Under the action of lattice potentials of the latter type, one-dimensional solitons feature motion regimes in the form of the transverse drift and persistent swing. In the two-dimensional geometry, three types of axisymmetric radial lattices are considered, namely those based solely on the refractive-index modulation, or solely on the linear-loss modulation, or on a combination of both. The rotary motion of solitons in such axisymmetric potentials can be effectively controlled by varying the strength of the initial tangential kick. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Super-honeycomb lattice: A hybrid fermionic and bosonic system
Zhong, Hua; Zhu, Yi; Zhang, Da; Li, Changbiao; Zhang, Yanpeng; Li, Fuli; Belić, Milivoj R; Xiao, Min
2016-01-01
We report on transport properties of the super-honeycomb lattice, the band structure of which possesses a flat band and Dirac cones, according to the tight-binding approximation. This super-honeycomb model combines the honeycomb lattice and the Lieb lattice and displays the properties of both. The super-honeycomb lattice also represents a hybrid fermionic and bosonic system, which is rarely seen in nature. By choosing the phases of input beams properly, the flat-band mode of the super-honeycomb will be excited and the input beams will exhibit a strong localization during propagation. On the other hand, if the modes of Dirac cones of the super-honeycomb lattice are excited, one will observe conical diffraction. Furthermore, if the input beam is properly chosen to excite a sublattice of the super-honeycomb lattice and the modes of Dirac cones with different pseudospins, e.g., the three-beam interference pattern, the pseudospin-mediated vortices will be observed.
Localization Spectroscopy of a Single Ion in an Optical Lattice
DEFF Research Database (Denmark)
Legrand, Olivier Philippe Alexandre
2015-01-01
The work reported in this thesis primarily focuses on studies of the dynamics of a single laser-cooled ion, simultaneously confined in the harmonic potential of a linear Paul trap and a rapidly varying periodic potential – a so-called optical lattice – generated from an optical standing-wave. Bes......The work reported in this thesis primarily focuses on studies of the dynamics of a single laser-cooled ion, simultaneously confined in the harmonic potential of a linear Paul trap and a rapidly varying periodic potential – a so-called optical lattice – generated from an optical standing...... calibration and analysis of the detection system, several theoretical simulations of the expected dynamics and associated optical response of the ion were undertaken. Finally, a new laser source based on second harmonic generation was developed in order to perform laser-cooling of Ca+ ions, and to serve...
Probabilistic representation of fermionic lattice systems
Energy Technology Data Exchange (ETDEWEB)
Beccaria, Matteo; Presilla, Carlo; De Angelis, Gian Fabrizio; Jona-Lasinio, Giovanni
2000-03-01
We describe an exact Feynman-Kac type formula to represent the dynamics of fermionic lattice systems. In this approach the real time or Euclidean time dynamics is expressed in terms of the stochastic evolution of a collection of Poisson processes. From this formula we derive a family of algorithms for Monte Carlo simulations, parametrized by the jump rates of the Poisson processes.
Kartashov, Yaroslav V; Konotop, Vladimir V; Torner, Lluis
2016-01-01
We address the propagation of light beams in longitudinally modulated PT-symmetric lattices, built as arrays of couplers with periodically varying separation between their channels, and show a number of possibilities for efficient diffraction control available in such non-conservative structures. The dynamics of light in such lattices crucially depends on the ratio of the switching length for the straight segments of each coupler and the longitudinal lattice period. Depending on the longitudinal period, one can achieve either beam rectification, when the input light propagates at a fixed angle across the structure without diffractive broadening, or dynamic localization, when the initial intensity distribution is periodically restored after each longitudinal period. Importantly, the transition between these two different propagation regimes can be achieved by tuning only gain and losses acting in the system, provided that the PT-symmetry remains unbroken. The impact of Kerr nonlinearity is also discussed.
Localized modes in dissipative lattice media: An overview
He, Yingji; Mihalache, Dumitru
2014-01-01
We overview recent theoretical studies of the dynamics of one- and two-dimensional spatial dissipative solitons in models based on the complex Ginzburg-Landau equations with the cubic-quintic combination of loss and gain terms, which include imaginary, real, or complex spatially periodic potentials. The imaginary potential represents periodic modulation of the local loss and gain. It is shown that the effective gradient force, induced by the inhomogeneous loss distribution, gives rise to three generic propagation scenarios for one-dimensional (1D) dissipative solitons: transverse drift, persistent swing motion, and damped oscillations. When the lattice-average loss/gain value is zero, and the real potential has spatial parity opposite to that of the imaginary component, the respective complex potential is a realization of the parity-time symmetry. Under the action of lattice potentials of the latter type, 1D solitons feature unique motion regimes in the form of transverse drift and persistent swing. In the 2D...
Evolution of localized states in Lieb lattices under time-dependent magnetic fields
Gouveia, J. D.; Maceira, I. A.; Dias, R. G.
2016-11-01
We study the slow time evolution of localized states of the open-boundary Lieb lattice when a magnetic flux is applied perpendicularly to the lattice and increased linearly in time. In this system, Dirac cones periodically disappear, reappear, and touch the flat band as the flux increases. We show that the slow time evolution of a localized state in this system is analogous to that of a zero-energy state in a three-level system whose energy levels intersect periodically and that this evolution can be mapped into a classical precession motion with a precession axis that rotates as times evolves. Beginning with a localized state of the Lieb lattice, as the magnetic flux is increased linearly and slowly, the evolving state precesses around a state with a small itinerant component and the amplitude of its localized component oscillates around a constant value (below but close to 1), except at multiples of the flux quantum where it may vary sharply. This behavior reflects the existence of an electric field (generated by the time-dependent magnetic field) which breaks the C4 symmetry of the constant flux Hamiltonian.
Institute of Scientific and Technical Information of China (English)
LI De-Jun; MI Xian-Wu; DENG Ke; TANG Yi
2006-01-01
In the classical lattice theory, solitons and locaLized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solitons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.
A local factorization of the fermion determinant in lattice QCD
Cè, Marco; Schaefer, Stefan
2016-01-01
We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action local in the block fields. The interaction among gauge fields on distant blocks is mediated by multiboson fields located on the boundaries of the blocks. The resultant multiboson domain-decomposed hybrid Monte Carlo passes extensive numerical tests carried out by measuring standard gluonic observables. The combination of the determinant factorization and of the one of the propagator, that we put forward recently, paves the way for multilevel Monte Carlo integration in presence of fermions. We test this possibility by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and we observe a significant increase of the signal-to-noise ratio due to a two-level integration.
A local factorization of the fermion determinant in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Ce, Marco [Scuola Normale Superiore, Pisa (Italy); INFN, Pisa (Italy); Giusti, Leonardo [Milano-Bicocca Univ. (Italy). Dipartimento di Fisica; INFN, Milano-Bicocca (Italy); Schaefer, Stefan [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2016-09-15
We introduce a factorization of the fermion determinant in lattice QCD with Wilson-type fermions that leads to a bosonic action which is local in the block fields. The interaction among gauge fields on distant blocks is mediated by multiboson fields located on the boundaries of the blocks. The resultant multiboson domain-decomposed hybrid Monte Carlo passes extensive numerical tests carried out by measuring standard gluonic observables. The combination of the determinant factorization and of the one of the propagator, that we put forward recently, paves the way for multilevel Monte Carlo integration in the presence of fermions. We test this possibility by computing the disconnected correlator of two flavor-diagonal pseudoscalar densities, and we observe a significant increase of the signal-to-noise ratio due to a two-level integration.
Obtaining local reciprocal lattice vectors from finite-element analysis.
Sutter, John P; Connolley, Thomas; Hill, Tim P; Huang, Houcheng; Sharp, Doug W; Drakopoulos, Michael
2008-11-01
Finite-element analysis is frequently used by engineers at synchrotron beamlines to calculate the elastic deformation of a single crystal undergoing mechanical bending or thermal load. ANSYS Workbench software is widely used for such simulations. However, although ANSYS Workbench software provides useful information on the displacements, strains and stresses within the crystal, it does not yield the local reciprocal lattice vectors that would be required for X-ray diffraction calculations. To bridge this gap, a method based on the shape functions and interpolation procedures of the software itself has been developed. An application to the double-crystal bent Laue monochromator being designed for the I12 (JEEP) wiggler beamline at the Diamond Light Source is presented.
Local probe studies on lattice distortions and electronic correlations in manganites
lopes, Armandina; Correia, João Guilherme
This thesis presents an experimental study on lattice distortions and electronic correlations in colossal magnetoresistive magnetic oxides. The Perturbed Angular Correlation local probe technique is used to study selected manganite systems in order to obtain relevant insight into microscopic phenomena responsible for their macroscopic pr operties. Complementary structural, magnetic and electric characterization was performed. The work is focused on the following aspects: \\\\Lattice distortions and polaron clusters in LaMnO$_{3+ \\Delta}$ system. A study of the electric field gradi ent and magnetic hyperfine field was performed in representative samples of the LaMnO$_{3+ \\Delta}$ system, and correlated with macroscopic information obtained in the same samples. Particular attention was given to the LaMnO$_{3.12}$ sample since this compound is a prototype of a ferromagnetic-insulat or manganite, presenting a rhombohedric- orthorhombic structural phase transition near room temperature. We found that random distribu...
SQUID metamaterials on a Lieb lattice: From flat-band to nonlinear localization
Lazarides, N.; Tsironis, G. P.
2017-08-01
The dynamic equations for the fluxes through the superconducting quantum interference devices (SQUIDs) that form a two-dimensional metamaterial on a Lieb lattice are derived and then linearized around zero flux to obtain the linear frequency spectrum according to the standard procedure. That spectrum due to the Lieb lattice geometry possesses a frequency band structure exhibiting two characteristic features: two dispersive bands, which form a Dirac cone at the corners of the first Brillouin zone and a flat band crossing the Dirac points. It is demonstrated numerically that localized states can be excited in the system when it is initialized with single-site excitations; depending on the amplitude of those initial states, the localization is either due to the flat-band or to nonlinear effects. Flat-band localized states are formed in the nearly linear regime, whereas localized excitations of the discrete breather type are formed in the nonlinear regime. These two regimes are separated by an intermediate turbulent regime for which no localization is observed. Notably, initial single-site excitations of only edge SQUIDs of a unit cell may end up in flat-band localized states; no such states are formed for initial single-site excitations of a corner SQUID of a unit cell. The degree of localization of the resulting states is in any case quantified using well-established measures, such as the energetic participation ratio and the second moment.
Exposing local symmetries in distorted driven lattices via time-averaged invariants
Wulf, T.; Morfonios, C. V.; Diakonos, F. K.; Schmelcher, P.
2016-05-01
Time-averaged two-point currents are derived and shown to be spatially invariant within domains of local translation or inversion symmetry for arbitrary time-periodic quantum systems in one dimension. These currents are shown to provide a valuable tool for detecting deformations of a spatial symmetry in static and driven lattices. In the static case the invariance of the two-point currents is related to the presence of time-reversal invariance and/or probability current conservation. The obtained insights into the wave functions are further exploited for a symmetry-based convergence check which is applicable for globally broken but locally retained potential symmetries.
Exposing local symmetries in distorted driven lattices via time-averaged invariants.
Wulf, T; Morfonios, C V; Diakonos, F K; Schmelcher, P
2016-05-01
Time-averaged two-point currents are derived and shown to be spatially invariant within domains of local translation or inversion symmetry for arbitrary time-periodic quantum systems in one dimension. These currents are shown to provide a valuable tool for detecting deformations of a spatial symmetry in static and driven lattices. In the static case the invariance of the two-point currents is related to the presence of time-reversal invariance and/or probability current conservation. The obtained insights into the wave functions are further exploited for a symmetry-based convergence check which is applicable for globally broken but locally retained potential symmetries.
Shinaoka, Hiroshi; Tomita, Yusuke; Motome, Yukitoshi
2011-07-22
Motivated by puzzling characteristics of spin-glass transitions widely observed in pyrochlore-based frustrated materials, we investigate the effects of coupling to local lattice distortions in a bond-disordered antiferromagnet on the pyrochlore lattice by extensive Monte Carlo simulations. We show that the spin-glass transition temperature T(f) is largely enhanced by the spin-lattice coupling and, furthermore, becomes almost independent of Δ in a wide range of the disorder strength Δ. The critical property of the spin-glass transition is indistinguishable from that of the canonical Heisenberg spin glass in the entire range of Δ. These peculiar behaviors are ascribed to a modification of the degenerate manifold from a continuous to semidiscrete one by spin-lattice coupling.
Absence of Anderson localization in certain random lattices
Choi, Wonjun; Hooper, Ian R; Bernes, William L; Bertolotti, Jacopo
2016-01-01
We report on the transition between an Anderson localized regime and a conductive regime in a 1D scattering system with correlated disorder. We show experimentally that when long-range correlations, in the form of a power-law spectral density with power larger than 2, are introduced the localization length becomes much bigger than the sample size and the transmission peaks typical of an Anderson localized system merge into a pass band. As other forms of long-range correlations are known to have the opposite effect, i.e. to enhance localization, our results show that care is needed when discussing the effects of correlations, as different kinds of long-range correlations can give rise to very different behavior.
Ultracold Quantum Gases and Lattice Systems: Quantum Simulation of Lattice Gauge Theories
Wiese, U -J
2013-01-01
Abelian and non-Abelian gauge theories are of central importance in many areas of physics. In condensed matter physics, Abelian U(1) lattice gauge theories arise in the description of certain quantum spin liquids. In quantum information theory, Kitaev's toric code is a Z(2) lattice gauge theory. In particle physics, Quantum Chromodynamics (QCD), the non-Abelian SU(3) gauge theory of the strong interactions between quarks and gluons, is non-perturbatively regularized on a lattice. Quantum link models extend the concept of lattice gauge theories beyond the Wilson formulation, and are well suited for both digital and analog quantum simulation using ultracold atomic gases in optical lattices. Since quantum simulators do not suffer from the notorious sign problem, they open the door to studies of the real-time evolution of strongly coupled quantum systems, which are impossible with classical simulation methods. A plethora of interesting lattice gauge theories suggests itself for quantum simulation, which should al...
Universality in Nonequilibrium Lattice Systems Theoretical Foundations
Ódor, Géza
2008-01-01
Universal scaling behavior is an attractive feature in statistical physics because a wide range of models can be classified purely in terms of their collective behavior due to a diverging correlation length. This book provides a comprehensive overview of dynamical universality classes occurring in nonequilibrium systems defined on regular lattices. The factors determining these diverse universality classes have yet to be fully understood, but the book attempts to summarize our present knowledge, taking them into account systematically.The book helps the reader to navigate in the zoo of basic m
Generation of localized modes in an electrical lattice using subharmonic driving.
English, L Q; Palmero, F; Candiani, P; Cuevas, J; Carretero-González, R; Kevrekidis, P G; Sievers, A J
2012-02-24
We show experimentally and numerically that an intrinsic localized mode (ILM) can be stably produced (and experimentally observed) via subharmonic, spatially homogeneous driving in the context of a nonlinear electrical lattice. The precise nonlinear spatial response of the system has been seen to depend on the relative location in frequency between the driver frequency, ω(d), and the bottom of the linear dispersion curve, ω(0). If ω(d)/2 lies just below ω(0), then a single ILM can be generated in a 32-node lattice, whereas, when ω(d)/2 lies within the dispersion band, a spatially extended waveform resembling a train of ILMs results. To our knowledge, and despite its apparently broad relevance, such an experimental observation of subharmonically driven ILMs has not been previously reported.
Light propagation and localization in modulated photonic lattices and waveguides
Garanovich, Ivan L; Sukhorukov, Andrey A; Kivshar, Yuri S
2011-01-01
We review both theoretical and experimental advances in the recently emerged physics of modulated photonic lattices. Artificial periodic dielectric media, such as photonic crystals and photonic lattices, provide a powerful tool for the control of the fundamental properties of light propagation in photonic structures. Photonic lattices are arrays of coupled optical waveguides, where the light propagation becomes effectively discretized. Such photonic structures allow one to study many useful optical analogies with other fields, such as the physics of solid state and electron theory. In particular, the light propagation in periodic photonic structures resembles the motion of electrons in a crystalline lattice of semiconductor materials. The discretized nature of light propagation gives rise to many new phenomena which are not possible in homogeneous bulk media, such as discrete diffraction and diffraction management, discrete and gap solitons, and discrete surface waves. Recently, it was discovered that applyin...
Stochastic Lattice Gas Model for a Predator-Prey System
Satulovsky, J E; Satulovsky, Javier; Tome, Tania
1994-01-01
We propose a stochastic lattice gas model to describe the dynamics of two animal species population, one being a predator and the other a prey. This model comprehends the mechanisms of the Lotka-Volterra model. Our analysis was performed by using a dynamical mean-field approximation and computer simulations. Our results show that the system exhibits an oscillatory behavior of the population densities of prey and predators. For the sets of parameters used in our computer simulations, these oscillations occur at a local level. Mean-field results predict synchronized collective oscillations.
Spin-flux phase in the Kondo lattice model with classical localized spins
Agterberg, DF; Yunoki, S
2000-01-01
We provide numerical evidence that a spin-flux phase exists as a ground state of the Kondo lattice model with classical local spins on a square lattice. This state manifests itself as a double-e magnetic order in the classical spins with spin density at both (0, pi) and (pi ,0) and further exhibits
DEFF Research Database (Denmark)
Ruban, Andrei; Simak, S.I.; Shallcross, S.;
2003-01-01
We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au...
Observation of localized flat-band states in Kagome photonic lattices.
Zong, Yuanyuan; Xia, Shiqiang; Tang, Liqin; Song, Daohong; Hu, Yi; Pei, Yumiao; Su, Jing; Li, Yigang; Chen, Zhigang
2016-04-18
We report the first experimental demonstration of localized flat-band states in optically induced Kagome photonic lattices. Such lattices exhibit a unique band structure with the lowest band being completely flat (diffractionless) in the tight-binding approximation. By taking the advantage of linear superposition of the flat-band eigenmodes of the Kagome lattices, we demonstrate a high-fidelity transmission of complex patterns in such two-dimensional pyrochlore-like photonic structures. Our numerical simulations find good agreement with experimental observations, upholding the belief that flat-band lattices can support distortion-free image transmission.
Archer, Charles Jens; Musselman, Roy Glenn; Peters, Amanda; Pinnow, Kurt Walter; Swartz, Brent Allen; Wallenfelt, Brian Paul
2010-03-16
A massively parallel computer system contains an inter-nodal communications network of node-to-node links. Each node implements a respective routing strategy for routing data through the network, the routing strategies not necessarily being the same in every node. The routing strategies implemented in the nodes are dynamically adjusted during application execution to shift network workload as required. Preferably, adjustment of routing policies in selective nodes is performed at synchronization points. The network may be dynamically monitored, and routing strategies adjusted according to detected network conditions.
Charukhchyan, M. V.; Sedov, E. S.; Arakelian, S. M.; Alodjants, A. P.
2014-06-01
We consider the problem of formation of small-amplitude spatially localized oscillatory structures for atomic Bose-Einstein condensates confined in two- and three-dimensional optical lattices, respectively. Our approach is based on applying the regions with different signs of atomic effective masses where an atomic system exhibits effective hyperbolic dispersion within the first Brillouin zone. By using the kp method we have demonstrated mapping of the initial Gross-Pitaevskii equation on nonlinear Klein-Gordon and/or Ginzburg-Landau-Higgs equations, which is inherent in matter fields within ϕ4-field theories. Formation of breatherlike oscillating localized states—atomic oscillons—as well as kink-shaped states have been predicted in this case. Apart from classical field theories atomic field oscillons occurring in finite lattice structures possess a critical number of particles for their formation. The obtained results pave the way to simulating some analogues of fundamental cosmological processes occurring during our Universe's evolution and to modeling nonlinear hyperbolic metamaterials with condensed matter (atomic) systems.
Numerical Studies of Localized Vibrating Structures in Nonlinear Lattices
1991-03-01
lattice, from Denardo [19901. 11 strings which supported adjacent elements , and was assumed to be approximately linear. For our purposes, we will assume a...City, State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNIT ELEMENT NO NO NO ACCESSION NO 11 TITLE (Include Security...art in cosmology , particle physics, condensed matter physics, and hydrodynamics, to name but a few. Most of the soliton work performed to date has
Two-Dimensional Lattice Gravity as a Spin System
Beirl, W; Riedler, J
1994-01-01
Quantum gravity is studied in the path integral formulation applying the Regge calculus. Restricting the quadratic link lengths of the originally triangular lattice the path integral can be transformed to the partition function of a spin system with higher couplings on a Kagome lattice. Various measures acting as external field are considered. Extensions to matter fields and higher dimensions are discussed.
Facilitation Dynamics and Localization Phenomena in Rydberg Lattice Gases with Position Disorder
Marcuzzi, Matteo; Minář, Jiří; Barredo, Daniel; de Léséleuc, Sylvain; Labuhn, Henning; Lahaye, Thierry; Browaeys, Antoine; Levi, Emanuele; Lesanovsky, Igor
2017-02-01
We explore the dynamics of Rydberg excitations in an optical tweezer array under antiblockade (or facilitation) conditions. Because of the finite temperature the atomic positions are randomly spread, an effect that leads to quenched correlated disorder in the interatomic interaction strengths. This drastically affects the facilitation dynamics as we demonstrate experimentally on the elementary example of two atoms. To shed light on the role of disorder in a many-body setting we show that here the dynamics is governed by an Anderson-Fock model, i.e., an Anderson model formulated on a lattice with sites corresponding to many-body Fock states. We first consider a one-dimensional atom chain in a limit that is described by a one-dimensional Anderson-Fock model with disorder on every other site, featuring both localized and delocalized states. We then illustrate the effect of disorder experimentally in a situation in which the system maps on a two-dimensional Anderson-Fock model on a trimmed square lattice. We observe a clear suppression of excitation propagation, which we ascribe to the localization of the many-body wave functions in Hilbert space.
Stochastic locality and master-field simulations of very large lattices arXiv
Lüscher, Martin
In lattice QCD and other field theories with a mass gap, the field variables in distant regions of a physically large lattice are only weakly correlated. Accurate stochastic estimates of the expectation values of local observables may therefore be obtained from a single representative field. Such master-field simulations potentially allow very large lattices to be simulated, but require various conceptual and technical issues to be addressed. In this talk, an introduction to the subject is provided and some encouraging results of master-field simulations of the SU(3) gauge theory are reported.
Wang, Da-Wei; Zhu, Shi-Yao; Scully, Marlan O
2014-01-01
We show that the timed Dicke states of a collection of three-level atoms can form a tight-binding lattice in the momentum space. This lattice, coined the superradiance lattice (SL), can be constructed based on an electromagnetically induced transparency (EIT) system. For a one-dimensional SL, we need the coupling field of the EIT system to be a standing wave. The detuning between the two components of the standing wave introduces an effective electric field. The quantum behaviours of electrons in lattices, such as Bloch oscillations, Wannier-Stark ladders, Bloch band collapsing and dynamic localization can be observed in the SL. The SL can be extended to two, three and even higher dimensions where no analogous real space lattices exist and new physics are waiting to be explored.
Dynamic behavior of multirobot systems using lattice gas automata
Stantz, Keith M.; Cameron, Stewart M.; Robinett, Rush D., III; Trahan, Michael W.; Wagner, John S.
1999-07-01
Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems (or swarms). Our group has been studying the collective, autonomous behavior of these such systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi- agents architectures. Our goal is to coordinate a constellation of point sensors using unmanned robotic vehicles (e.g., RATLERs, Robotic All-Terrain Lunar Exploration Rover- class vehicles) that optimizes spatial coverage and multivariate signal analysis. An overall design methodology evolves complex collective behaviors realized through local interaction (kinetic) physics and artificial intelligence. Learning objectives incorporate real-time operational responses to environmental changes. This paper focuses on our recent work understanding the dynamics of many-body systems according to the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's rate of deformation, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent nonlinearity of the dynamical equations describing large ensembles, stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots maneuvering past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with
Nguyen, Ba Phi
2016-01-01
We study numerically the transport and localization properties of waves in ordered and disordered ladder-shaped lattices with local $\\mathcal{PT}$ symmetry. Using a transfer matrix method, we calculate the transmittance and the reflectance for the individual channels and the Lyapunov exponent for the whole system. In the absence of disorder, we find that when the gain/loss parameter $\\rho$ is smaller than the interchain coupling parameter $t_{v}$, the transmittance and the reflectance are periodic functions of the system size, whereas when $\\rho$ is larger than $t_{v}$, the transmittance is found to be an exponentially-decaying function while the reflectance attains a saturation value in the thermodynamic limit. For a fixed system size, there appear perfect transmission resonances in each individual channel at several values of the gain/loss strength smaller than $t_{v}$. A singular behavior of the transmittance is also found to appear at various values of $\\rho$ for a given system size. When disorder is inse...
Nonlinear localized modes in dipolar Bose–Einstein condensates in two-dimensional optical lattices
Energy Technology Data Exchange (ETDEWEB)
Rojas-Rojas, Santiago, E-mail: srojas@cefop.cl [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Naether, Uta [Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Delgado, Aldo [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Vicencio, Rodrigo A. [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile)
2016-09-16
Highlights: • We study discrete two-dimensional breathers in dipolar Bose–Einstein Condensates. • Important differences in the properties of three fundamental modes are found. • Norm threshold for existence of 2D breathers varies with dipolar interaction. • The Effective Potential Method is implemented for stability analysis. • Uncommon mobility of 2D discrete solitons is observed. - Abstract: We analyze the existence and properties of discrete localized excitations in a Bose–Einstein condensate loaded into a periodic two-dimensional optical lattice, when a dipolar interaction between atoms is present. The dependence of the Number of Atoms (Norm) on the energy of solutions is studied, along with their stability. Two important features of the system are shown, namely, the absence of the Norm threshold required for localized solutions to exist in finite 2D systems, and the existence of regions in the parameter space where two fundamental solutions are simultaneously unstable. This feature enables mobility of localized solutions, which is an uncommon feature in 2D discrete nonlinear systems. With attractive dipolar interaction, a non-trivial behavior of the Norm dependence is obtained, which is well described by an analytical model.
Local non-Calderbank-Shor-Steane quantum error-correcting code on a three-dimensional lattice
Kim, Isaac H.
2011-05-01
We present a family of non-Calderbank-Shor-Steane quantum error-correcting code consisting of geometrically local stabilizer generators on a 3D lattice. We study the Hamiltonian constructed from ferromagnetic interaction of overcomplete set of local stabilizer generators. The degenerate ground state of the system is characterized by a quantum error-correcting code whose number of encoded qubits are equal to the second Betti number of the manifold. These models (i) have solely local interactions; (ii) admit a strong-weak duality relation with an Ising model on a dual lattice; (iii) have topological order in the ground state, some of which survive at finite temperature; and (iv) behave as classical memory at finite temperature.
Discrete Multiscale Analysis: A Biatomic Lattice System
Contra, G A Cassatella; 10.1142/S1402925110000957
2010-01-01
We discuss a discrete approach to the multiscale reductive perturbative method and apply it to a biatomic chain with a nonlinear interaction between the atoms. This system is important to describe the time evolution of localized solitonic excitations. We require that also the reduced equation be discrete. To do so coherently we need to discretize the time variable to be able to get asymptotic discrete waves and carry out a discrete multiscale expansion around them. Our resulting nonlinear equation will be a kind of discrete Nonlinear Schr\\"odinger equation. If we make its continuum limit, we obtain the standard Nonlinear Schr\\"odinger differential equation.
Synchronization and suppression of chaos in non-locally coupled map lattices
Indian Academy of Sciences (India)
R M Szmoski; S E De S Pinto; M T Van Kan; A M Batista; R L Viana; S R Lopes
2009-12-01
We considered coupled map lattices with long-range interactions to study the spatiotemporal behaviour of spatially extended dynamical systems. Coupled map lattices have been intensively investigated as models to understand many spatiotemporal phenomena observed in extended system, and consequently spatiotemporal chaos. We used the complex order parameter to quantify chaos synchronization for a one-dimensional chain of coupled logistic maps with a coupling strength which varies with the lattice in a power-law fashion. Depending on the range of the interactions, complete chaos synchronization and chaos suppression may be attained. Furthermore, we also calculated the Lyapunov dimension and the transversal distance to the synchronization manifold.
New non-local lattice models for the description of wave dispersion in concrete
Iliopoulos, Sokratis N.; Polyzos, Demosthenes; Aggelis, Dimitrios G.
2015-03-01
The propagation of longitudinal waves through concrete materials is strongly affected by dispersion. This is clearly indicated experimentally from the increase of phase velocity at low frequencies whereas many attempts have been made to explain this behavior analytically. Since the classical elastic theory for bulk media is by default non-dispersive, enhanced theories have been developed. The most commonly used higher order theory is the dipolar gradient elastic theory which takes into account the microstructural effects in heterogeneous media like concrete. The microstructural effects are described by two internal length scale parameters (g and h) which correspond to the micro-stiffness and micro-inertia respectively. In the current paper, this simplest possible version of the general gradient elastic theory proposed by Mindlin is reproduced through non-local lattice models consisting of discrete springs and masses. The masses simulate the aggregates of the concrete specimen whereas the springs are the mechanical similitude of the concrete matrix. The springs in these models are connecting the closest masses between them as well as the second or third closest to each other masses creating a non-local system of links. These non-neighboring interactions are represented by massless springs of constant stiffness while on the other hand one cannot neglect the significant mass of the springs connecting neighboring masses as this is responsible for the micro-inertia term. The major advantage of the presented lattice models is the fact that the considered microstructural effects can be accurately expressed as a function of the size and the mechanical properties of the microstructure.
Directory of Open Access Journals (Sweden)
Daohong Song
2012-01-01
Full Text Available We provide a brief overview on our recent experimental work on linear and nonlinear localization of singly charged vortices (SCVs and doubly charged vortices (DCVs in two-dimensional optically induced photonic lattices. In the nonlinear case, vortex propagation at the lattice surface as well as inside the uniform square-shaped photonic lattices is considered. It is shown that, apart from the fundamental (semi-infinite gap discrete vortex solitons demonstrated earlier, the SCVs can self-trap into stable gap vortex solitons under the normal four-site excitation with a self-defocusing nonlinearity, while the DCVs can be stable only under an eight-site excitation inside the photonic lattices. Moreover, the SCVs can also turn into stable surface vortex solitons under the four-site excitation at the surface of a semi-infinite photonics lattice with a self-focusing nonlinearity. In the linear case, bandgap guidance of both SCVs and DCVs in photonic lattices with a tunable negative defect is investigated. It is found that the SCVs can be guided at the negative defect as linear vortex defect modes, while the DCVs tend to turn into quadrupole-like defect modes provided that the defect strength is not too strong.
Formal Developments for Lattice QCD with Applications to Hadronic Systems
Davoudi, Zohreh
2014-01-01
Lattice quantum chromodynamics (QCD) will soon become the primary theoretical tool in rigorous studies of single- and multi-hadron sectors of QCD. It is truly ab initio meaning that its only parameters are those of standard model. The result of a lattice QCD calculation corresponds to that of nature only in the limit when the volume of spacetime is taken to infinity and the spacing between discretized points on the lattice is taken to zero. A better understanding of these discretization and volume effects not only provides the connection to the infinite-volume continuum observables, but also leads to optimized calculations that can be performed with available computational resources. This thesis includes various formal developments in this direction, along with proposals for improvements, to be applied to the upcoming lattice QCD studies of nuclear and hadronic systems. Among these developments are i) an analytical investigation of the recovery of rotational symmetry with the use of suitably-formed smeared op...
Three-state Potts model on non-local directed small-world lattices
Ferraz, Carlos Handrey Araujo; Lima, José Luiz Sousa
2017-10-01
In this paper, we study the non-local directed Small-World (NLDSW) disorder effects in the three-state Potts model as a form to capture the essential features shared by real complex systems where non-locality effects play a important role in the behavior of these systems. Using Monte Carlo techniques and finite-size scaling analysis, we estimate the infinite lattice critical temperatures and the leading critical exponents in this model. In particular, we investigate the first- to second-order phase transition crossover when NLDSW links are inserted. A cluster-flip algorithm was used to reduce the critical slowing down effect in our simulations. We find that for a NLDSW disorder densities p
Probing Local Lattice Fluctautions in Cuprates and Manganites by High k-Resolution EXAFS
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
X-ray absorption fine structure has been exploited as a tool tostudy local lattice distortions in the perovskite cuperates and manganites, showing novel phenomena as high temperature superconductivity and colossal magneto-resistance. Temperature dependent Cu K-edge and Mn K-edge EXAFS have been used to investigate the local lattice distortions associated with the doped charge at metallic densities in these materials. Temperature dependent correlated Debye-Waller factors of the Cu-O in the cuprates shows an upturn at the stripe formation temperature Tso. Capabilities of the EXAFS technique have been further demonstrated for the case of the manganites, revealing key information on their metal-insulator transition. The EXAFS has been shown to be capable of providing quantitative local distortions that are closely associated with the characteristic properties of these complex materials.
Localized and systemic scleroderma.
Hawk, A; English, J C
2001-03-01
Scleroderma is a broad term encompassing both localized and systemic sclerosis. Localized scleroderma is a cutaneous limited fibrosis that manifests as plaque morphea, generalized morphea, linear scleroderma, and deep morphea. Systemic scleroderma (sclerosis) can manifest as either limited or diffuse disease. Limited systemic sclerosis is typically preceded by Raynaud's phenomenon, involves cutaneous sclerosis distal to the elbows, with gastrointestinal and pulmonary fibrosis, and anticentromere antibody positivity. Diffuse systemic scleroderma is characterized by simultaneous Raynaud's phenomenon, cutaneous skin involvement proximal to the elbow with gastrointestinal, pulmonary, renal and cardiac fibrosis, and positive serology for antitopoisomerase and anti-RNAP III antibodies. This article discusses the classification, epidemiology, pathogenesis, clinical manifestations, treatment, and prognosis of the scleroderma.
Hérisson, Benjamin; Challamel, Noël; Picandet, Vincent; Perrot, Arnaud
2016-09-01
The static behavior of the Fermi-Pasta-Ulam (FPU) axial chain under distributed loading is examined. The FPU system examined in the paper is a nonlinear elastic lattice with linear and quadratic spring interaction. A dimensionless parameter controls the possible loss of convexity of the associated quadratic and cubic energy. Exact analytical solutions based on Hurwitz zeta functions are developed in presence of linear static loading. It is shown that this nonlinear lattice possesses scale effects and possible localization properties in the absence of energy convexity. A continuous approach is then developed to capture the main phenomena observed regarding the discrete axial problem. The associated continuum is built from a continualization procedure that is mainly based on the asymptotic expansion of the difference operators involved in the lattice problem. This associated continuum is an enriched gradient-based or nonlocal axial medium. A Taylor-based and a rational differential method are both considered in the continualization procedures to approximate the FPU lattice response. The Padé approximant used in the continualization procedure fits the response of the discrete system efficiently, even in the vicinity of the limit load when the non-convex FPU energy is examined. It is concluded that the FPU lattice system behaves as a nonlocal axial system in dynamic but also static loading.
Self-localization of Bose–Einstein condensates in optical lattices
Kruse, Johannes; Fleischmann, Ragnar
2017-03-01
Mean field and beyond mean field model calculations of Bose–Einstein condensates trapped in optical lattices have shown that initially homogeneous condensates can evolve into self-trapped, strongly localized states in the presence of weak boundary dissipation, a phenomenon called self-localization. A dynamical phase transition from extended to localized states can be observed when the effective nonlinearity exceeds a critical threshold {{{Λ }}}{eff}{{c}}. We investigate this phase transition to self-localization in the mean field approximation of the discrete nonlinear Schrödinger equation. We quantitatively characterize the properties of the discrete breathers, i.e. the nonlinear localized solutions, at the phase transition. This leads us to propose and numerically verify an analytical lower bound {{{Λ }}}{eff}{{L}} for the critical nonlinearity based on the idea of self-induced Anderson localization.
Anderson localization and saturable nonlinearity in one-dimensional disordered lattices
Nguyen, Ba Phi
2016-01-01
We investigate numerically the propagation and the Anderson localization of plane waves in a one-dimensional lattice chain, where disorder and saturable nonlinearity are simultaneously present. Using a calculation scheme for solving the stationary discrete nonlinear Schr\\"{o}dinger equation in the fixed input case, the disorder-averaged logarithmic transmittance and the localization length are calculated in a numerically precise manner. The localization length is found to be a nonmonotonic function of the incident wave intensity, acquiring a minimum value at a certain finite intensity, due to saturation effects. For low incident intensities where the saturation effect is ineffective, the enhancement of localization due to Kerr-type nonlinearity occurs in a way similar to the case without saturation. For sufficiently high incident intensities, we find that the localization length is an increasing function of the incident wave intensity, which implies that localization is suppressed for stronger input intensiti...
Slip systems, dislocation boundaries and lattice rotations in deformed metals
DEFF Research Database (Denmark)
Winther, Grethe
2009-01-01
strains at room temperature are analysed. A major result is that, by contrast to previous beliefs, the boundaries align with specific crystallographic planes, which depend on the crystallographic grain orientation. This grain orientation dependence originates from an underlying dependence of the active...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...
Applications of X-ray fluorescence holography to determine local lattice distortions
Energy Technology Data Exchange (ETDEWEB)
Hayashi, Kouichi, E-mail: khayashi@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Happo, Naohisa [Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Hosokawa, Shinya [Department of Physics, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan)
2014-08-15
Highlights: • We summarized topics of X-ray fluorescence holography focused on the local lattice distortions. • We found details of behaviors of nearest neighbor atoms around dopants. • We found the average distributions of the atoms at the individual sites in mixed crystals. • Distorted and undistorted sires sometimes coexist in a same mixed crystal. - Abstract: X-ray fluorescence holography (XFH) is a method for investigating atomic order up to the medium ranges, and can provide 3D atomic images around specific elements within a radius of nm order. In addition to these characteristics, XFH is sensitive to positional fluctuations of atoms, and therefore it is useful for characterizing the local lattice distortions around specific elements. We have applied XFH to dopants and mixed crystals. We found interesting features in local lattice distortions, such as the displacements of first-neighbor atoms around dopants, far-sighted views of the atomistic fluctuations in mixed crystals, and the coexistence of distorted/undistorted sites in the same material.
Low-dimensional q-Tori in FPU Lattices: Dynamics and Localization Properties
Christodoulidi, Helen
2012-01-01
This is a continuation of our study concerning q-tori, i.e. tori of low dimensionality in the phase space of nonlinear lattice models like the Fermi-Pasta-Ulam (FPU) model. In our previous work we focused on the beta FPU system, and we showed that the dynamical features of the q-tori serve as an interpretational tool to understand phenomena of energy localization in the FPU space of linear normal modes. In the present paper i) we employ the method of Poincare - Lindstedt series, for a fixed set of frequencies, in order to compute an explicit quasi-periodic representation of the trajectories lying on q-tori in the alpha model, and ii) we consider more general types of initial excitations in both the alpha and beta models. Furthermore we turn into questions of physical interest related to the dynamical features of the q-tori. We focus on particular q-tori solutions describing low-frequency `packets' of modes, and excitations of a small set of modes with an arbitrary distribution in q-space. In the former case, ...
Superconductivity on a quasiperiodic lattice: Extended-to-localized crossover of Cooper pairs
Sakai, Shiro; Takemori, Nayuta; Koga, Akihisa; Arita, Ryotaro
2017-01-01
We study a possible superconductivity in quasiperiodic systems by portraying the issue within the attractive Hubbard model on a Penrose lattice. Applying a real-space dynamical mean-field theory to the model consisting of 4181 sites, we find a superconducting phase at low temperatures. Reflecting the nonperiodicity of the Penrose lattice, the superconducting state exhibits an inhomogeneity. According to the type of the inhomogeneity, the superconducting phase is categorized into three different regions which cross over each other. Among them, the weak-coupling region exhibits spatially extended Cooper pairs, which are nevertheless distinct from the conventional pairing of two electrons with opposite momenta.
Energy Technology Data Exchange (ETDEWEB)
Kyker, R.
1995-07-25
Navigation systems have been vital to transportation ever since man took to the air and sea. Early navigation systems utilized the sextant to navigate by starlight as well as the magnetic needle compass. As electronics and communication technologies improved, inertial navigation systems were developed for use in ships and missile delivery. These systems consisted of electronic compasses, gyro-compasses, accelerometers, and various other sensors. Recently, systems such as LORAN and the Global Positioning System (GPS) have utilized the properties of radio wave propagation to triangulate position. The Local Positioning System (LPS), described in this paper, is an implementation of a limited inertial navigation system designed to be used on a bicycle. LPS displays a cyclist`s current position relative to a starting location. This information is displayed in Cartesian-like coordinates. To accomplish this, LPS relies upon two sensors, an electronic compass sensor and a distance sensor. The compass sensor provides directional information while the distance sensor provides the distance traveled. This information yields a distance vector for each point in time which when summed produces the cyclist`s current position. LPS is microprocessor controlled and is designed for a range of less than 90 miles.
DEFF Research Database (Denmark)
Friis, Cecilie; Reenberg, Anette; Heinimann, Andreas
2016-01-01
This paper investigates the direct and cascading land system consequences of a Chinese company's land acquisition for rubber cultivation in northern Laos. Transnational land acquisitions are increasingly acknowledged as an important driver of direct land use conversion with implications for local....... Combining the conceptual lenses of land systems and livelihood approaches, this paper demonstrates how the land use system has changed substantially because of the establishment of the rubber plantation by the company, notably in the linkages between livestock rearing, upland shifting cultivation...... and lowland paddy rice cultivation. The changes go beyond the immediate competition for land caused by the rubber plantation: a penalty scheme introduced by the rubber company for damage to rubber trees caused by browsing animals has led the villagers to abandon livestock rearing, causing a cascade...
Dynamical Systems On Weighted Lattices: General Theory
Maragos, Petros
2016-01-01
In this work a theory is developed for unifying large classes of nonlinear discrete-time dy- namical systems obeying a superposition of a weighted maximum or minimum type. The state vectors and input-output signals evolve on nonlinear spaces which we call complete weighted lat- tices and include as special cases the nonlinear vector spaces of minimax algebra. Their algebraic structure has a polygonal geometry. Some of the special cases unified include max-plus, max- product, and probabilistic...
Locality and Efficient Evaluation of Lattice Composite Fields: Overlap-Based Gauge Operators
Alexandru, Andrei
2016-01-01
We propose a novel general approach to locality of lattice composite fields, which in case of QCD involves locality in both quark and gauge degrees of freedom. The method is applied to gauge operators based on the overlap Dirac matrix elements, showing for the first time their local nature on realistic path-integral backgrounds. The framework entails a method for efficient evaluation of such non-ultralocal operators, whose computational cost is volume-indepenent at fixed accuracy, and only grows logarithmically as this accuracy approaches zero. This makes computation of useful operators, such as overlap-based topological density, practical. The key notion underlying these features is that of exponential insensitivity to distant fields, made rigorous by introducing the procedure of statistical regularization. The scales associated with insensitivity property are useful characteristics of non-local continuum operators.
Lattice specific heat and local density of states of Ni-based dilute alloys at low temperature
Indian Academy of Sciences (India)
P D Semlaty; Kapil Dev; P N Ram
2006-06-01
A detailed theoretical study of the low-temperature lattice specific heat of Ni-based dilute alloys has been carried out. Lattice Green's function method has been used to calculate the local density of states of substitutional impurities and lattice specific heat in different alloys. The resonance condition has been investigated for possible occurrence of resonance modes. Except in NiCr and NiMn, low-frequency resonance modes have been obtained in all the alloys. However, no localized mode was obtained. The impurity-induced increase in lattice specific heat is explained on the basis of the obtained resonance modes. The calculation shows an excellent agreement with the measured lattice specific heat in these alloys
Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures
Lotnyk, Andriy; Ross, Ulrich; Bernütz, Sabine; Thelander, Erik; Rauschenbach, Bernd
2016-05-01
Insights into the local atomic arrangements of layered Ge-Sb-Te compounds are of particular importance from a fundamental point of view and for data storage applications. In this view, a detailed knowledge of the atomic structure in such alloys is central to understanding the functional properties both in the more commonly utilized amorphous-crystalline transition and in recently proposed interfacial phase change memory based on the transition between two crystalline structures. Aberration-corrected scanning transmission electron microscopy allows direct imaging of local arrangement in the crystalline lattice with atomic resolution. However, due to the non-trivial influence of thermal diffuse scattering on the high-angle scattering signal, a detailed examination of the image contrast requires comparison with theoretical image simulations. This work reveals the local atomic structure of trigonal Ge-Sb-Te thin films by using a combination of direct imaging of the atomic columns and theoretical image simulation approaches. The results show that the thin films are prone to the formation of stacking disorder with individual building blocks of the Ge2Sb2Te5, Ge1Sb2Te4 and Ge3Sb2Te6 crystal structures intercalated within randomly oriented grains. The comparison with image simulations based on various theoretical models reveals intermixed cation layers with pronounced local lattice distortions, exceeding those reported in literature.
Applications of lattice QCD techniques for condensed matter systems
Buividovich, P. V.; Ulybyshev, M. V.
2016-08-01
We review the application of lattice QCD techniques, most notably the Hybrid Monte Carlo (HMC) simulations, to first-principle study of tight-binding models of crystalline solids with strong inter-electron interactions. After providing a basic introduction into the HMC algorithm as applied to condensed matter systems, we review HMC simulations of graphene, which in the recent years have helped to understand the semimetal behavior of clean suspended graphene at the quantitative level. We also briefly summarize other novel physical results obtained in these simulations. Then we comment on the applicability of hybrid Monte Carlo to topological insulators and Dirac and Weyl semimetals and highlight some of the relevant open physical problems. Finally, we also touch upon the lattice strong-coupling expansion technique as applied to condensed matter systems.
Impurity-induced localization of Bose-Einstein condensates in one-dimensional optical lattices
Institute of Scientific and Technical Information of China (English)
Wang Jian-Jun; Zhang Ai-Xia; Xue Ju-Kui
2011-01-01
The impurity-induced localization of two-component Bose-Einstein condensates loaded into deep one-dimensional optical lattices is studied both analytically and numerically.It is shown that,the analytical criteria for self-trapping and moving soliton/breather of the primary-component condensate are modified significantly by an admixture of an impurity component(the second component).The realization of the self-trapped state and the moving soliton/breather states of the primary-component becomes more easy with the minor admixture of the impurity-component,even if the two components are partly overlapped.
Exact treatment of interacting bosons in rotating systems and lattices
DEFF Research Database (Denmark)
Sørensen, Ole Søe
Quantum systems of ultra-cold particles constitute a unique tool for studying the fundamental phenomena of physics in their purest and most isolated forms. Complicated dynamics are found even for few particles and to comprehend the features of systems with many particles, we must first understand...... mechanical nature of particles dominate, resulting in a behavior fundamentally different from that of classical particles. In rotating systems this causes quantization of angular momentum which can lead to macroscopic vortices in rotating Bose-Einstein condensates. In optical lattices the atom becomes...
Kasamatsu, Kenichi; Ichinose, Ikuo; Matsui, Tetsuo
2013-09-13
Recently, the possibility of quantum simulation of dynamical gauge fields was pointed out by using a system of cold atoms trapped on each link in an optical lattice. However, to implement exact local gauge invariance, fine-tuning the interaction parameters among atoms is necessary. In the present Letter, we study the effect of violation of the U(1) local gauge invariance by relaxing the fine-tuning of the parameters and showing that a wide variety of cold atoms is still a faithful quantum simulator for a U(1) gauge-Higgs model containing a Higgs field sitting on sites. The clarification of the dynamics of this gauge-Higgs model sheds some light upon various unsolved problems, including the inflation process of the early Universe. We study the phase structure of this model by Monte Carlo simulation and also discuss the atomic characteristics of the Higgs phase in each simulator.
Application of Lattice Boltzmann Methods in Complex Mass Transfer Systems
Sun, Ning
Lattice Boltzmann Method (LBM) is a novel computational fluid dynamics method that can easily handle complex and dynamic boundaries, couple local or interfacial interactions/reactions, and be easily parallelized allowing for simulation of large systems. While most of the current studies in LBM mainly focus on fluid dynamics, however, the inherent power of this method makes it an ideal candidate for the study of mass transfer systems involving complex/dynamic microstructures and local reactions. In this thesis, LBM is introduced to be an alternative computational method for the study of electrochemical energy storage systems (Li-ion batteries (LIBs) and electric double layer capacitors (EDLCs)) and transdermal drug design on mesoscopic scale. Based on traditional LBM, the following in-depth studies have been carried out: (1) For EDLCs, the simulation of diffuse charge dynamics is carried out for both the charge and the discharge processes on 2D systems of complex random electrode geometries (pure random, random spheres and random fibers). Steric effect of concentrated solutions is considered by using modified Poisson-Nernst-Plank (MPNP) equations and compared with regular Poisson-Nernst-Plank (PNP) systems. The effects of electrode microstructures (electrode density, electrode filler morphology, filler size, etc.) on the net charge distribution and charge/discharge time are studied in detail. The influence of applied potential during discharging process is also discussed. (2) For the study of dendrite formation on the anode of LIBs, it is shown that the Lattice Boltzmann model can capture all the experimentally observed features of microstructure evolution at the anode, from smooth to mossy to dendritic. The mechanism of dendrite formation process in mesoscopic scale is discussed in detail and compared with the traditional Sand's time theories. It shows that dendrite formation is closely related to the inhomogeneous reactively at the electrode-electrolyte interface
Fuel lattice design in a boiling water reactor using an ant-colony-based system
Energy Technology Data Exchange (ETDEWEB)
Montes, Jose Luis, E-mail: joseluis.montes@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, La Marquesa, Ocoyoacac, Estado de Mexico, CP 52750 (Mexico); Facultad de Ciencias, Universidad Autonoma del Estado de Mexico (Mexico); Francois, Juan-Luis, E-mail: juan.luis.francois@gmail.com [Departamento de Sistemas Energeticos, Facultad de Ingenieria, Universidad Nacional Autonoma de Mexico, Paseo Cuauhnahuac 8532, Jiutepec, Mor., CP 62550 (Mexico); Ortiz, Juan Jose, E-mail: juanjose.ortiz@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, La Marquesa, Ocoyoacac, Estado de Mexico, CP 52750 (Mexico); Martin-del-Campo, Cecilia, E-mail: cecilia.martin.del.campo@gmail.com [Departamento de Sistemas Energeticos, Facultad de Ingenieria, Universidad Nacional Autonoma de Mexico, Paseo Cuauhnahuac 8532, Jiutepec, Mor., CP 62550 (Mexico); Perusquia, Raul, E-mail: raul.perusquia@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carr. Mexico-Toluca S/N, La Marquesa, Ocoyoacac, Estado de Mexico, CP 52750 (Mexico)
2011-06-15
Research highlights: > We present an ant-colony-based system for BWR fuel lattice design and optimization. > Assessment of candidate solutions at 0.0 MWd/kg {sup 235}U seems to have a limited scope. > Suitable heuristic rules enable more realistic fuel lattice designs. > The election of the objective has a large impact in CPU time. > ACS enables an important decrease of the initial average U-235 enrichment. - Abstract: This paper presents a new approach to deal with the boiling water reactor radial fuel lattice design. The goal is to optimize the distribution of both, the fissionable material, and the reactivity control poison material inside the fuel lattice at the beginning of its life. An ant-colony-based system was used to search for either: the optimum location of the poisoned pin inside the lattice, or the U{sup 235} enrichment and Gd{sub 2}O{sub 3} concentrations. In the optimization process, in order to know the parameters of the candidate solutions, the neutronic simulator CASMO-4 transport code was used. A typical 10 x 10 BWR fuel lattice with an initial average U{sup 235} enrichment of 4.1%, used in the current operation of Laguna Verde Nuclear Power Plant was taken as a reference. With respect to that reference lattice, it was possible to decrease the average U{sup 235} enrichment up to 3.949%, this obtained value represents a decrease of 3.84% with respect to the reference U{sup 235} enrichment; whereas, the k-infinity was inside the {+-}100 pcm's range, and there was a difference of 0.94% between the local power peaking factor and the lattice reference value. Particular emphasis was made on defining the objective function which is used for making the assessment of candidate solutions. In a typical desktop personal computer, about four hours of CPU time were necessary for the algorithm to fulfill the goals of the optimization process. The results obtained with the application of the implemented system showed that the proposed approach represents a
The Syntax of Lattice-Valued Propositional Logic System lp(X)
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Lattice-valued logic plays an important role in multi-valued logic systems. A lattice valued logic system lp(X) is constructed. The syntax of lp(X) is discussed. It may be more convenient in application and study especially in the case that the valuation domain is finite lattice implication algebra.
Zhang, Yufeng; Zhang, Xiangzhi; Wang, Yan; Liu, Jiangen
2017-01-01
With the help of R-matrix approach, we present the Toda lattice systems that have extensive applications in statistical physics and quantum physics. By constructing a new discrete integrable formula by R-matrix, the discrete expanding integrable models of the Toda lattice systems and their Lax pairs are generated, respectively. By following the constructing formula again, we obtain the corresponding (2+1)-dimensional Toda lattice systems and their Lax pairs, as well as their (2+1)-dimensional discrete expanding integrable models. Finally, some conservation laws of a (1+1)-dimensional generalised Toda lattice system and a new (2+1)-dimensional lattice system are generated, respectively.
Using Superconducting Qubit Circuits to Engineer Exotic Lattice Systems
Tsomokos, Dimitris; Ashhab, Sahel; Nori, Franco
2011-03-01
We propose an architecture based on superconducting qubits and resonators for the implementation of a variety of exotic lattice systems, such as spin and Hubbard models in higher or fractal dimensions and higher-genus topologies. Spin systems are realized naturally using qubits, while superconducting resonators can be used for the realization of Bose-Hubbard models. Fundamental requirements for these designs, such as controllable interactions between arbitrary qubit pairs, have recently been implemented in the laboratory, rendering our proposals feasible with current technology.
Nonlinear nano-scale localized breather modes in a discrete weak ferromagnetic spin lattice
Energy Technology Data Exchange (ETDEWEB)
Kavitha, L., E-mail: louiskavitha@yahoo.co.in [Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu (CUTN), Thiruvarur 610 101, Tamil Nadu (India); Max-Planck Institute for the Physics of Complex Systems, Dresden (Germany); The Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Parasuraman, E. [Department of Physics, Periyar University, Salem 636 011, Tamil Nadu (India); Center for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamil Nadu (India); Gopi, D. [Department of Chemistry, Periyar University, Salem 636 011, Tamil Nadu (India); Center for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamil Nadu (India); Prabhu, A. [Department of Physics, Periyar University, Salem 636 011, Tamil Nadu (India); Vicencio, Rodrigo A. [Departamento de Física and MSI-Nucleus on Advanced Optics, Center for Optics and Photonics (CEFOP), Facultad de Ciencias, Universidad de Chile, Santiago 7800003 (Chile); Max-Planck Institute for the Physics of Complex Systems, Dresden (Germany)
2016-03-01
We investigate the propagation dynamics of highly localized discrete breather modes in a weak ferromagnetic spin lattice with on-site easy axis anisotropy due to crystal field effect. We derive the discrete nonlinear equation of motion by employing boson mappings and p-representation. We explore the onset of modulational instability both analytically in the framework of linear stability analysis and numerically by means of molecular dynamics (MD) simulations, and a perfect agreement was demonstrated. It is also explored that how the antisymmetric nature of the canted ferromagnetic lattice supports highly localized discrete breather (DBs) modes as shown in the stability/instability windows. The energy exchange between low amplitude discrete breathers favours the growth of higher amplitude DBs, resulting eventually in the formation of few long-lived high amplitude DBs. - Highlights: • The effects of DM and anisotropy interaction on the DB modes are studied. • The antisymmetric nature of the canted ferromagnetic medium supports the DB modes. • Dynamics of ferromagnetic chain is governed by boson mappings and p-representation.
On Lattice Sequential Decoding for Large MIMO Systems
Ali, Konpal S.
2014-04-01
Due to their ability to provide high data rates, Multiple-Input Multiple-Output (MIMO) wireless communication systems have become increasingly popular. Decoding of these systems with acceptable error performance is computationally very demanding. In the case of large overdetermined MIMO systems, we employ the Sequential Decoder using the Fano Algorithm. A parameter called the bias is varied to attain different performance-complexity trade-offs. Low values of the bias result in excellent performance but at the expense of high complexity and vice versa for higher bias values. We attempt to bound the error by bounding the bias, using the minimum distance of a lattice. Also, a particular trend is observed with increasing SNR: a region of low complexity and high error, followed by a region of high complexity and error falling, and finally a region of low complexity and low error. For lower bias values, the stages of the trend are incurred at lower SNR than for higher bias values. This has the important implication that a low enough bias value, at low to moderate SNR, can result in low error and low complexity even for large MIMO systems. Our work is compared against Lattice Reduction (LR) aided Linear Decoders (LDs). Another impressive observation for low bias values that satisfy the error bound is that the Sequential Decoder\\'s error is seen to fall with increasing system size, while it grows for the LR-aided LDs. For the case of large underdetermined MIMO systems, Sequential Decoding with two preprocessing schemes is proposed – 1) Minimum Mean Square Error Generalized Decision Feedback Equalization (MMSE-GDFE) preprocessing 2) MMSE-GDFE preprocessing, followed by Lattice Reduction and Greedy Ordering. Our work is compared against previous work which employs Sphere Decoding preprocessed using MMSE-GDFE, Lattice Reduction and Greedy Ordering. For the case of large systems, this results in high complexity and difficulty in choosing the sphere radius. Our schemes
Hedayatrasa, Saeid; Uddin, Mohammad
2016-01-01
Optimized topology of bi-material acoustic metamaterial lattice plates is studied for maximized locally resonant bandgap of flexural guided waves. Optimized layout of the two relatively stiff and compliant material phases in the design domain is explored, free from any restrictions on the topology and shape of the relevant domains. Multiobjective optimization is performed through which maximized effective stiffness or minimized overall mass of the bandgap topology is additionally ensured. Extreme and selected intermediate optimized topologies of Pareto fronts are presented and their bandgap efficiencies and effective stiffness are compared. The bi-material constitution of selected topologies are further altered and modal band structure of resultant multilateral and porous designs are evaluated. Novel, core-shell like, locally resonant bandgaps are introduced. It is shown that how the bandgap efficiency and structural mass and/or stiffness can be optimized through optimized microstructural design of the matrix...
Chien, Chihchun; Metcalf, Mekena; Lai, Chenyen
2016-05-01
Memory effects are observable in magnetization, rechargeable batteries, and many systems exhibiting history-dependent states. Quantum memory effects are observable, for instance, in atomic superfluids. A counter-intuitive question is whether quantum memory effects can exist in noninteracting systems. Here we present two examples of cold-atom systems demonstrating memory effects in noninteracting systems. The first example is a ring-shaped potential loaded with noninteracting fermions. An artificial vector potential drives a current and with a tunable dissipative background, the current lags behind the driving and exhibits hysteresis loops. The dissipative energy can be controlled by the coupling between the fermions and the background. In the second example, cold atoms loaded in a tunable optical lattice transformed from the triangular to the kagome geometry. The kagome lattice supports a flat-band consisting of degenerate localized states. Quantum memory effects are observable after a lattice transformation as the steady-state density depends on the rate of the transformation. The versatility of memory effects in cold-atom systems promises novel applications in atomtronics.
Lie algebraic similarity transformed Hamiltonians for lattice model systems
Wahlen-Strothman, Jacob M.; Jiménez-Hoyos, Carlos A.; Henderson, Thomas M.; Scuseria, Gustavo E.
2015-01-01
We present a class of Lie algebraic similarity transformations generated by exponentials of two-body on-site Hermitian operators whose Hausdorff series can be summed exactly without truncation. The correlators are defined over the entire lattice and include the Gutzwiller factor ni ↑ni ↓ , and two-site products of density (ni ↑+ni ↓) and spin (ni ↑-ni ↓) operators. The resulting non-Hermitian many-body Hamiltonian can be solved in a biorthogonal mean-field approach with polynomial computational cost. The proposed similarity transformation generates locally weighted orbital transformations of the reference determinant. Although the energy of the model is unbound, projective equations in the spirit of coupled cluster theory lead to well-defined solutions. The theory is tested on the one- and two-dimensional repulsive Hubbard model where it yields accurate results for small and medium sized interaction strengths.
Harter, Andrew K; Joglekar, Yogesh N
2016-01-01
Open, non-equilibrium systems with balanced gain and loss, known as parity-time ($\\mathcal{PT}$)-symmetric systems, exhibit properties that are absent in closed, isolated systems. A key property is the $\\mathcal{PT}$-symmetry breaking transition, which occurs when the gain-loss strength, a measure of the openness of the system, exceeds the intrinsic energy-scale of the system. We analyze the fate of this transition in disordered lattices with non-Hermitian gain and loss potentials $\\pm i\\gamma$ at reflection-symmetric sites. Contrary to the popular belief, we show that the $\\mathcal{PT}$-symmetric phase is protected in the presence of a correlated (periodic) disorder which leads to a positive $\\mathcal{PT}$-symmetry breaking threshold. We uncover a veiled symmetry of such disordered systems that is instrumental for the said protection, and show that this symmetry leads to new localization behavior across the $\\mathcal{PT}$-symmetry breaking transition. We elucidate the interplay between such localization and ...
Morency, Eric; Anguish, Lynne; Coonrod, Scott
2011-02-16
We and others have recently demonstrated by immuno-EM and mutation analysis that two oocyte-restricted maternal effect genes, PADI6 and MATER, localize, in part, to the oocyte cytoplasmic lattices (CPLs). During these ongoing studies, however, we found that the localization of these factors by confocal immunofluorescence (IF) analysis can vary dramatically depending upon how the oocytes and embryos are processed, with the localization pattern sometimes appearing more uniformly cytoplasmic while at other times appearing to be primarily cortical. We set out to better understand this differential staining pattern by testing a range of IF protocol parameters, changing mainly time and temperature conditions of the primary antibody solution incubation, as well as fixation methods. We found by confocal IF whole mount analysis that PADI6 and MATER localization in germinal vesicle stage oocytes is mainly cytoplasmic when the oocytes are fixed and then incubated with primary antibodies at room temperature for 1 hour, while the localization of these factors is largely limited to the cortex when the oocytes are fixed and incubated in primary antibody at 4 °C overnight. We then probed sections of fixed/embedded ovaries and isolated two-cell embryos with specific antibodies and found that, under these conditions, PADI6 and MATER were again primarily cytoplasmically localized, although the staining for these factors is slightly more cortical at the two-cell stage. Taken together, our results suggest that the localization of CPL-associated proteins by confocal IF is particularly affected by processing conditions. Further, based on our current observations, it appears that PADI6 and MATER are primarily distributed throughout the cytoplasm as opposed to the oocyte subcortex.
Locally self-similar phase diagram of the disordered Potts model on the hierarchical lattice.
Anglès d'Auriac, J-Ch; Iglói, Ferenc
2013-02-01
We study the critical behavior of the random q-state Potts model in the large-q limit on the diamond hierarchical lattice with an effective dimensionality d(eff)>2. By varying the temperature and the strength of the frustration the system has a phase transition line between the paramagnetic and the ferromagnetic phases which is controlled by four different fixed points. According to our renormalization group study the phase boundary in the vicinity of the multicritical point is self-similar; it is well represented by a logarithmic spiral. We expect an infinite number of reentrances in the thermodynamic limit; consequently one cannot define standard thermodynamic phases in this region.
Lattice Based Mix Network for Location Privacy in Mobile System
Directory of Open Access Journals (Sweden)
Kunwar Singh
2015-01-01
Full Text Available In 1981, David Chaum proposed a cryptographic primitive for privacy called mix network (Mixnet. A mixnet is cryptographic construction that establishes anonymous communication channel through a set of servers. In 2004, Golle et al. proposed a new cryptographic primitive called universal reencryption which takes the input as encrypted messages under the public key of the recipients not the public key of the universal mixnet. In Eurocrypt 2010, Gentry, Halevi, and Vaikunthanathan presented a cryptosystem which is an additive homomorphic and a multiplicative homomorphic for only one multiplication. In MIST 2013, Singh et al. presented a lattice based universal reencryption scheme under learning with error (LWE assumption. In this paper, we have improved Singh et al.’s scheme using Fairbrother’s idea. LWE is a lattice hard problem for which till now there is no polynomial time quantum algorithm. Wiangsripanawan et al. proposed a protocol for location privacy in mobile system using universal reencryption whose security is reducible to Decision Diffie-Hellman assumption. Once quantum computer becomes a reality, universal reencryption can be broken in polynomial time by Shor’s algorithm. In postquantum cryptography, our scheme can replace universal reencryption scheme used in Wiangsripanawan et al. scheme for location privacy in mobile system.
Sharing lattice QCD data over a widely distributed file system
Amagasa, T.; Aoki, S.; Aoki, Y.; Aoyama, T.; Doi, T.; Fukumura, K.; Ishii, N.; Ishikawa, K.-I.; Jitsumoto, H.; Kamano, H.; Konno, Y.; Matsufuru, H.; Mikami, Y.; Miura, K.; Sato, M.; Takeda, S.; Tatebe, O.; Togawa, H.; Ukawa, A.; Ukita, N.; Watanabe, Y.; Yamazaki, T.; Yoshie, T.
2015-12-01
JLDG is a data-grid for the lattice QCD (LQCD) community in Japan. Several large research groups in Japan have been working on lattice QCD simulations using supercomputers distributed over distant sites. The JLDG provides such collaborations with an efficient method of data management and sharing. File servers installed on 9 sites are connected to the NII SINET VPN and are bound into a single file system with the GFarm. The file system looks the same from any sites, so that users can do analyses on a supercomputer on a site, using data generated and stored in the JLDG at a different site. We present a brief description of hardware and software of the JLDG, including a recently developed subsystem for cooperating with the HPCI shared storage, and report performance and statistics of the JLDG. As of April 2015, 15 research groups (61 users) store their daily research data of 4.7PB including replica and 68 million files in total. Number of publications for works which used the JLDG is 98. The large number of publications and recent rapid increase of disk usage convince us that the JLDG has grown up into a useful infrastructure for LQCD community in Japan.
Variable-lattice model of multi-component systems. 1. General consideration
Zakharov, A. Yu.; Schneider, A. A.; Udovsky, A. L.
2010-01-01
The paper contains a development of the previously proposed generalized lattice model (GLM). In contrast to usual lattice models, the difference of the specific atomic volumes of the components is taken in account in GLM. In addition to GLM, the dependence of the specific atomic volumes on local atomic environments taken into account in new variable-lattice model (VLM). Thermodynamic functions of multi-component homogeneous phases in the VLM are obtained. Equations of equilibrium between gase...
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Ba Phi [Central University of Construction, Tuy Hoa (Viet Nam); Kim, Ki Hong [Ajou University, Suwon (Korea, Republic of)
2014-02-15
We study numerically the dynamics of an initially localized wave packet in one-dimensional nonlinear Schroedinger lattices with both local and nonlocal nonlinearities. Using the discrete nonlinear Schroedinger equation generalized by including a nonlocal nonlinear term, we calculate four different physical quantities as a function of time, which are the return probability to the initial excitation site, the participation number, the root-mean-square displacement from the excitation site and the spatial probability distribution. We investigate the influence of the nonlocal nonlinearity on the delocalization to self-trapping transition induced by the local nonlinearity. In the non-self-trapping region, we find that the nonlocal nonlinearity compresses the soliton width and slows down the spreading of the wave packet. In the vicinity of the delocalization to self-trapping transition point and inside the self-trapping region, we find that a new kind of self-trapping phenomenon, which we call partial self-trapping, takes place when the nonlocal nonlinearity is sufficiently strong.
Applicability of Quasi-Monte Carlo for lattice systems
Ammon, Andreas; Jansen, Karl; Leovey, Hernan; Griewank, Andreas; Müller-Preussker, Micheal
2013-01-01
This project investigates the applicability of quasi-Monte Carlo methods to Euclidean lattice systems in order to improve the asymptotic error scaling of observables for such theories. The error of an observable calculated by averaging over random observations generated from ordinary Monte Carlo simulations scales like $N^{-1/2}$, where $N$ is the number of observations. By means of quasi-Monte Carlo methods it is possible to improve this scaling for certain problems to $N^{-1}$, or even further if the problems are regular enough. We adapted and applied this approach to simple systems like the quantum harmonic and anharmonic oscillator and verified an improved error scaling of all investigated observables in both cases.
Farzanehpour, Mehdi; Tokatly, Ilya; Nano-Bio Spectroscopy Group; ETSF Scientific Development Centre Team
2015-03-01
We present a rigorous formulation of the time-dependent density functional theory for interacting lattice electrons strongly coupled to cavity photons. We start with an example of one particle on a Hubbard dimer coupled to a single photonic mode, which is equivalent to the single mode spin-boson model or the quantum Rabi model. For this system we prove that the electron-photon wave function is a unique functional of the electronic density and the expectation value of the photonic coordinate, provided the initial state and the density satisfy a set of well defined conditions. Then we generalize the formalism to many interacting electrons on a lattice coupled to multiple photonic modes and prove the general mapping theorem. We also show that for a system evolving from the ground state of a lattice Hamiltonian any density with a continuous second time derivative is locally v-representable. Spanish Ministry of Economy and Competitiveness (Grant No. FIS2013-46159-C3-1-P), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), COST Actions CM1204 (XLIC) and MP1306 (EUSpec).
Moving and Interaction of Compact-like Pulses in Klein-Gordon Lattice System
Institute of Scientific and Technical Information of China (English)
XIA Qing-Lin; YI Jian-Hong; YE Tu-Ming; DU Juan
2005-01-01
We study the moving and interaction of the compact-like pulses in the system of an anharmonic lattice with a double well on-site potential by a direct algebraic method and numerical experiments. It is found that the localization of the compact-like pulse is related to the nonlinear coupling parameter Cnl and the potential barrier height V0 of the double well potential. The velocity of the moving compact-like pulse is determined by the linear coupling parameter Cl, the localization parameter q (the nonlinear coupling parameter Cnl) and the potential barrier height Vo.Numerical experiments demonstrate that appropriate Cl is not detrimental to a stable moving of the compact-like pulse.However, the head on interaction of two compact-like pulses in the lattice system with comparatively small Cl leads to the appearance of a discrete stationary localized mode and small amplitude nonlinear oscillation background, while moderate Cl results in the emergence of two moving deformed pulses with damping amplitude and decay velocity and radiating oscillations, and biggish Cl brings on the appearing of four deformed kinks with radiating oscillations and different moving velocities.
Moving and Interaction of Compact-like Pulses in Klein-Gordon Lattice System
Institute of Scientific and Technical Information of China (English)
XIAQing-Lin; YIJian-Hong; YETu-Ming; DUJuan
2005-01-01
We study the moving and interaction of the compact-like pulses in the system of an anharmonlc lattice with a double well on-site potential by a direct algebraic method and numerical experiments. It is found that the localization of the compact-like pulse is rClated to the nonlinear coupling parameter Cnl and the potential barrier height Vo of the double well potential. The velocity of the moving compact-like pulse is determined by the linear coupling parameter Cl, the localization parameter q (the nonlinear coupling parameter Cnl) and the potential barrier height Vo.Numerical experiments demonstrate that appropriate Cl is not detrimental to a stable moving of the compact-like pulse.However, the head on interaction of two compact-like pulses in the lattice system with comparatively small Cl leads to the appearance of a discrete stationary localized mode and small amplitude nonlinear oscillation background, while moderate Cl results in the emergence of two moving deformed pulses with damping amplitude and decay velocity and radiating oscillations, and biggish Cl brings on the appearing of four deformed kinks with radiating oscillations and different moving velocities.
Sato, M; Imai, S; Fujita, N; Shi, W; Takao, Y; Sada, Y; Hubbard, B E; Ilic, B; Sievers, A J
2013-01-01
An intrinsic localized mode (ILM) represents a localized vibrational excitation in a nonlinear lattice. Such a mode will stay in resonance as the driver frequency is changed adiabatically until a bifurcation point is reached, at which point the ILM switches and disappears. The dynamics behind switching in such a many body system is examined here through experimental measurements and numerical simulations. Linear response spectra of a driven micromechanical array containing an ILM were measured in the frequency region between two fundamentally different kinds of bifurcation points that separate the large amplitude ILM state from the two low amplitude vibrational states. Just as a natural frequency can be associated with a driven harmonic oscillator, a similar natural frequency has been found for a driven ILM via the beat frequency between it and a weak, tunable probe. This finding has been confirmed using numerical simulations. The behavior of this nonlinear natural frequency plays important but different roles as the two bifurcation points are approached. At the upper transition its frequency coalesces with the driver and the resulting bifurcation is very similar to the saddle-node bifurcation of a single driven Duffing oscillator, which is treated in an Appendix. The lower transition occurs when the four-wave mixing partner of the natural frequency of the ILM intersects the topmost extended band mode of the same symmetry. The properties of linear local modes associated with the driven ILM are also identified experimentally for the first time and numerically but play no role in these transitions.
Sato, M.; Imai, S.; Fujita, N.; Shi, W.; Takao, Y.; Sada, Y.; Hubbard, B. E.; Ilic, B.; Sievers, A. J.
2013-01-01
An intrinsic localized mode (ILM) represents a localized vibrational excitation in a nonlinear lattice. Such a mode will stay in resonance as the driver frequency is changed adiabatically until a bifurcation point is reached, at which point the ILM switches and disappears. The dynamics behind switching in such a many body system is examined here through experimental measurements and numerical simulations. Linear response spectra of a driven micromechanical array containing an ILM were measured in the frequency region between two fundamentally different kinds of bifurcation points that separate the large amplitude ILM state from the two low amplitude vibrational states. Just as a natural frequency can be associated with a driven harmonic oscillator, a similar natural frequency has been found for a driven ILM via the beat frequency between it and a weak, tunable probe. This finding has been confirmed using numerical simulations. The behavior of this nonlinear natural frequency plays important but different roles as the two bifurcation points are approached. At the upper transition its frequency coalesces with the driver and the resulting bifurcation is very similar to the saddle-node bifurcation of a single driven Duffing oscillator, which is treated in an Appendix. The lower transition occurs when the four-wave mixing partner of the natural frequency of the ILM intersects the topmost extended band mode of the same symmetry. The properties of linear local modes associated with the driven ILM are also identified experimentally for the first time and numerically but play no role in these transitions.
Systemic and localized scleroderma.
Chung, Lorinda; Lin, Jan; Furst, Daniel E; Fiorentino, David
2006-01-01
Sclerosing conditions of the skin are manifested by a full spectrum of presentations that includes skin-limited forms as well as those which can involve internal organs and result in death. At this point, we are just beginning to understand the mechanisms of tissue fibrosis, and it is likely that the fibrotic processes are a heterogeneous group of disorders in which perturbation of multiple molecular pathways, including vascular and immunologically mediated pathways, can lead to fibrosis. We now have some moderately effective therapies for vascular aspects of systemic sclerosis (eg, bosentan for pulmonary arterial hypertension, calcium-channel blockers for Raynaud's, or angiotensin-converting enzyme inhibitors for renal crisis). We also are beginning to find treatments interrupting the immunologic pathways that manifest as systemic sclerosis (eg, methotrexate for the skin or cyclophosphamide for the lungs). The basic process of fibrosis, however, awaits proven, effective therapy.
Lattice Statistical Models for the Nematic Transitions in Liquid-Crystalline Systems
Nascimento, E. S.; Vieira, A. P.; Salinas, S. R.
2016-12-01
We investigate the connections between some simple Maier-Saupe lattice models, with a discrete choice of orientations of the microscopic directors, and a recent proposal of a two-tensor formalism to describe the phase diagrams of nematic liquid-crystalline systems. This two-tensor proposal is used to formulate the statistical problem in terms of fully connected lattice Hamiltonians, with the local nematic directors restricted to the Cartesian axes. Depending on the choice of interaction parameters, we regain all of the main features of the original mean-field two-tensor calculations. With a standard choice of parameters, we obtain the well-known sequence of isotropic, uniaxial, and biaxial nematic structures, with a Landau multicritical point. With another suitably chosen set of parameters, we obtain two tricritical points, according to some recent predictions of the two-tensor calculations. The simple statistical lattice models are quite easy to work with, for all values of parameters, and the present calculations can be carried out beyond the mean-field level.
Kondo Destruction in RKKY-Coupled Kondo Lattice and Multi-Impurity Systems
Nejati, Ammar; Ballmann, Katinka; Kroha, Johann
2017-03-01
In a Kondo lattice, the spin exchange coupling between a local spin and the conduction electrons acquires nonlocal contributions due to conduction electron scattering from surrounding local spins and the subsequent RKKY interaction. It leads to a hitherto unrecognized interference of Kondo screening and the RKKY interaction beyond the Doniach scenario. We develop a renormalization group theory for the RKKY-modified Kondo vertex. The Kondo temperature TK(y ) is suppressed in a universal way, controlled by the dimensionless RKKY coupling parameter y . Complete spin screening ceases to exist beyond a critical RKKY strength yc even in the absence of magnetic ordering. At this breakdown point, TK(y ) remains nonzero and is not defined for larger RKKY couplings y >yc. The results are in quantitative agreement with STM spectroscopy experiments on tunable two-impurity Kondo systems. The possible implications for quantum critical scenarios in heavy-fermion systems are discussed.
Observation of localized flat-band modes in a one-dimensional photonic rhombic lattice
Mukherjee, Sebabrata
2015-01-01
We experimentally demonstrate the photonic realization of a dispersionless flat-band in a one-dimensional photonic rhombic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation the lattice supports two dispersive and a non-dispersive (flat) band. We experimentally excite a superposition of flat-band eigen modes at the input of the photonic lattice and show the diffractionless propagation of the input modes due to their infinite effective mass.
Dynamics of a lattice gas system of three species
Wang, Yuanshi; Wu, Hong; Liang, Junhao
2016-10-01
This paper considers a mutualism system of three species in which each species provides resource for the next one in a one-directional loop, while there exists spatial competition among them. The system is characterized by a lattice gas model and the cases of obligate mutualisms, obligate-facultative mutualisms and facultative mutualisms are considered. Using dynamical systems theory, it is shown that (i) the mutualisms can lead to coexistence of species; (ii) A weak mutualism or an extremely strong mutualism will result in extinction of species, while even the superior facultative species will be driven into extinction by its over-strong mutualism on the next one; (iii) Initial population density plays a role in the coexistence of species. It is also shown that when there exists weak mutualism, an obligate species can survive by providing more benefit to the next one, and the inferior facultative species will not be driven into extinction if it can strengthen its mutualism on the next species. Moreover, Hopf bifurcation, saddle-node bifurcation and bifurcation of heteroclinic cycles are shown in the system. Projection method is extended to exhibit bistability in the three-dimensional model: when saddle-node bifurcation occurs, stable manifold of the saddle-node point divides intR+3 into two basins of attraction of two equilibria. Furthermore, Lyapunov method is applied to exhibit unstability of heteroclinic cycles. Numerical simulations confirm and extend our results.
Observation of localized flat-band modes in a quasi-one-dimensional photonic rhombic lattice.
Mukherjee, Sebabrata; Thomson, Robert R
2015-12-01
We experimentally demonstrate the photonic realization of a dispersionless flat band in a quasi-one-dimensional photonic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation, the lattice supports two dispersive and one nondispersive (flat) band. We experimentally excite superpositions of flat-band eigenmodes at the input of the photonic lattice and show the diffractionless propagation of the input states due to their infinite effective mass. In the future, the use of photonic rhombic lattices, together with the successful implementation of a synthetic gauge field, will enable the observation of Aharonov-Bohm photonic caging.
Lunar Localization System (LLS) Project
National Aeronautics and Space Administration — In support of NASA's vision for space, the goal of this project is to research and prototype a multi-component localization system which uses radiometry and vision...
Fault Self-Diagnosis for Modular Robotic Systems Using M-Lattice Modules
Directory of Open Access Journals (Sweden)
Enguang Guan
2015-04-01
Full Text Available In the domain of modular robotic systems, self-configuration, self-diagnosis and self-repair are known to be highly challenging tasks. This paper presents a novel fault self-diagnosis strategy which consists of two parts: fault detection and fault message transmission. In fault detection, a bionic synchronization ‘healthy heartbeat’ method is used to guarantee the high efficiency of the exogenous detection strategy. For fault message transmission, the Dijkstra method is modified to be capable of guiding the passage of fault messages along the optimal path. In a modular robotic system, fault message transmission depends mainly on local communications between adjacent modules, so there is no need for global broadcast information. Computational simulations of one system form, M-Lattice, have demonstrated the practical effectiveness of the proposed strategy. The strategy should be applicable in modular robotic systems in general.
Lattice Boltzmann models for the grain growth in polycrystalline systems
Directory of Open Access Journals (Sweden)
Yonggang Zheng
2016-08-01
Full Text Available In the present work, lattice Boltzmann models are proposed for the computer simulation of normal grain growth in two-dimensional systems with/without immobile dispersed second-phase particles and involving the temperature gradient effect. These models are demonstrated theoretically to be equivalent to the phase field models based on the multiscale expansion. Simulation results of several representative examples show that the proposed models can effectively and accurately simulate the grain growth in various single- and two-phase systems. It is found that the grain growth in single-phase polycrystalline materials follows the power-law kinetics and the immobile second-phase particles can inhibit the grain growth in two-phase systems. It is further demonstrated that the grain growth can be tuned by the second-phase particles and the introduction of temperature gradient is also an effective way for the fabrication of polycrystalline materials with grained gradient microstructures. The proposed models are useful for the numerical design of the microstructure of materials and provide effective tools to guide the experiments. Moreover, these models can be easily extended to simulate two- and three-dimensional grain growth with considering the mobile second-phase particles, transient heat transfer, melt convection, etc.
Lattice Boltzmann models for the grain growth in polycrystalline systems
Zheng, Yonggang; Chen, Cen; Ye, Hongfei; Zhang, Hongwu
2016-08-01
In the present work, lattice Boltzmann models are proposed for the computer simulation of normal grain growth in two-dimensional systems with/without immobile dispersed second-phase particles and involving the temperature gradient effect. These models are demonstrated theoretically to be equivalent to the phase field models based on the multiscale expansion. Simulation results of several representative examples show that the proposed models can effectively and accurately simulate the grain growth in various single- and two-phase systems. It is found that the grain growth in single-phase polycrystalline materials follows the power-law kinetics and the immobile second-phase particles can inhibit the grain growth in two-phase systems. It is further demonstrated that the grain growth can be tuned by the second-phase particles and the introduction of temperature gradient is also an effective way for the fabrication of polycrystalline materials with grained gradient microstructures. The proposed models are useful for the numerical design of the microstructure of materials and provide effective tools to guide the experiments. Moreover, these models can be easily extended to simulate two- and three-dimensional grain growth with considering the mobile second-phase particles, transient heat transfer, melt convection, etc.
Directory of Open Access Journals (Sweden)
H. Oyanagi
2010-01-01
Full Text Available Carrier-induced lattice distortion (signature of polaron in oxypnictide superconductors is found by an instantaneous local probe, extended X-ray absorption fine structure (EXAFS. Polaron formation is detected as two distinct nearest neighbor distances (Fe-As, implying an incoherent local mode that develops coherence at the critical temperature. Comparing the results with the unusual lattice response in cuprate superconductors, intimate correlation between evolution of local lattice mode and superconductivity is revealed. The results suggest that strong electron-lattice interaction is present as a common ingredient in the microscopic mechanism of superconducting transition. The effect of magnetic impurity atoms in cuprates further indicates that magnetic scattering becomes diluted as long as polaron formation is conserved. We argue that polaron coherence dominates electrical conduction and magnetic interaction in oxypnictide and cuprate superconductors.
An integrable coupling system of lattice hierarchy and its continuous limits
Energy Technology Data Exchange (ETDEWEB)
Yu Fajun [College of Maths and Systematic Science, Shenyang Normal University, Shenyang 110034 (China)], E-mail: yfajun@163.com; Li Li [College of Maths and Systematic Science, Shenyang Normal University, Shenyang 110034 (China)
2009-04-13
In [E.G. Fan, Phys. Lett. A 372 (2008) 6368], Fan present a lattice hierarchy and its continuous limits. In this Letter, we extend this method, by introducing a complex discrete spectral problem, a coupling lattice hierarchy is derived. It is shown that a new sequence of combinations of complex lattice spectral problem converges to the integrable coupling couplings of soliton equation hierarchy, which has the integrable coupling system of AKNS hierarchy as a continuous limit.
Population dynamics of intraguild predation in a lattice gas system.
Wang, Yuanshi; Wu, Hong
2015-01-01
In the system of intraguild predation (IGP) we are concerned with, species that are in a predator-prey relationship, also compete for shared resources (space or food). While several models have been established to characterize IGP, mechanisms by which IG prey and IG predator can coexist in IGP systems with spatial competition, have not been shown. This paper considers an IGP model, which is derived from reactions on lattice and has a form similar to that of Lotka-Volterra equations. Dynamics of the model demonstrate properties of IGP and mechanisms by which the IGP leads to coexistence of species and occurrence of alternative states. Intermediate predation is shown to lead to persistence of the predator, while extremely big predation can lead to extinction of one/both species and extremely small predation can lead to extinction of the predator. Numerical computations confirm and extend our results. While empirical observations typically exhibit coexistence of IG predator and IG prey, theoretical analysis in this work demonstrates exact conditions under which this coexistence can occur. Copyright © 2014 Elsevier Inc. All rights reserved.
Fuel lattice design in a boiling water reactor using a knowledge-based automation system
Energy Technology Data Exchange (ETDEWEB)
Tung, Wu-Hsiung, E-mail: wstong@iner.gov.tw; Lee, Tien-Tso; Kuo, Weng-Sheng; Yaur, Shung-Jung
2015-11-15
Highlights: • An automation system was developed for the fuel lattice radial design of BWRs. • An enrichment group peaking equalizing method is applied to optimize the design. • Several heuristic rules and restrictions are incorporated to facilitate the design. • The CPU time for the system to design a 10x10 lattice was less than 1.2 h. • The beginning-of-life LPF was improved from 1.319 to 1.272 for one of the cases. - Abstract: A knowledge-based fuel lattice design automation system for BWRs is developed and applied to the design of 10 × 10 fuel lattices. The knowledge implemented in this fuel lattice design automation system includes the determination of gadolinium fuel pin location, the determination of fuel pin enrichment and enrichment distribution. The optimization process starts by determining the gadolinium distribution based on the pin power distribution of a flat enrichment lattice and some heuristic rules. Next, a pin power distribution flattening and an enrichment grouping process are introduced to determine the enrichment of each fuel pin enrichment type and the initial enrichment distribution of a fuel lattice design. Finally, enrichment group peaking equalizing processes are performed to achieve lower lattice peaking. Several fuel lattice design constraints are also incorporated in the automation system such that the system can accomplish a design which meets the requirements of practical use. Depending on the axial position of the lattice, a different method is applied in the design of the fuel lattice. Two typical fuel lattices with U{sup 235} enrichment of 4.471% and 4.386% were taken as references. Application of the method demonstrates that improved lattice designs can be achieved through the enrichment grouping and the enrichment group peaking equalizing method. It takes about 11 min and 1 h 11 min of CPU time for the automation system to accomplish two design cases on an HP-8000 workstation, including the execution of CASMO-4
Design of a lattice-based faceted classification system
Eichmann, David A.; Atkins, John
1992-01-01
We describe a software reuse architecture supporting component retrieval by facet classes. The facets are organized into a lattice of facet sets and facet n-tuples. The query mechanism supports precise retrieval and flexible browsing.
Lattice hydrodynamic model based traffic control: A transportation cyber-physical system approach
Liu, Hui; Sun, Dihua; Liu, Weining
2016-11-01
Lattice hydrodynamic model is a typical continuum traffic flow model, which describes the jamming transition of traffic flow properly. Previous studies in lattice hydrodynamic model have shown that the use of control method has the potential to improve traffic conditions. In this paper, a new control method is applied in lattice hydrodynamic model from a transportation cyber-physical system approach, in which only one lattice site needs to be controlled in this control scheme. The simulation verifies the feasibility and validity of this method, which can ensure the efficient and smooth operation of the traffic flow.
Thermalization and Canonical Typicality in Translation-Invariant Quantum Lattice Systems
Müller, Markus P.; Adlam, Emily; Masanes, Lluís; Wiebe, Nathan
2015-12-01
It has previously been suggested that small subsystems of closed quantum systems thermalize under some assumptions; however, this has been rigorously shown so far only for systems with very weak interaction between subsystems. In this work, we give rigorous analytic results on thermalization for translation-invariant quantum lattice systems with finite-range interaction of arbitrary strength, in all cases where there is a unique equilibrium state at the corresponding temperature. We clarify the physical picture by showing that subsystems relax towards the reduction of the global Gibbs state, not the local Gibbs state, if the initial state has close to maximal population entropy and certain non-degeneracy conditions on the spectrumare satisfied.Moreover,we showthat almost all pure states with support on a small energy window are locally thermal in the sense of canonical typicality. We derive our results from a statement on equivalence of ensembles, generalizing earlier results by Lima, and give numerical and analytic finite size bounds, relating the Ising model to the finite de Finetti theorem. Furthermore, we prove that global energy eigenstates are locally close to diagonal in the local energy eigenbasis, which constitutes a part of the eigenstate thermalization hypothesis that is valid regardless of the integrability of the model.
Wing, Waylin J.; Sadeghi, Seyed M.; Gutha, Rithvik R.
2016-12-01
We experimentally investigate plasmonic lattice modes of gold nanoantenna arrays that occur in asymmetric structures containing a silica substrate and either air or a thin layer of a high-index dielectric. Very distinct polarization switching is observed in the nanoantenna arrays wherein by rotating the incident light polarization by ninety degrees, the array can exhibit either a plasmonic lattice mode or a multipolar localized surface plasmon resonance of varying nature. A large range of nanoantenna lengths are studied, and since the length of the nanoantennas dictates the multipolar localized surface plasmon resonance, we find that the characteristics of the polarization switching are affected accordingly. We also investigate how the thin layer of the high-index dielectric on top of the nanoantenna arrays, in conjunction with varying nanoantenna length, impacts the generation of plasmonic lattice modes and the polarization switching in the arrays. The high-index dielectric is found to assist in the generation and optical coupling of the plasmonic lattice modes. By altering the angle of incidence, the polarization switching can become very large, and the arrays can be made to selectively transmit light of certain wavelengths.
Observation of a Localized Flat-Band State in a Photonic Lieb Lattice.
Mukherjee, Sebabrata; Spracklen, Alexander; Choudhury, Debaditya; Goldman, Nathan; Öhberg, Patrik; Andersson, Erika; Thomson, Robert R
2015-06-19
We demonstrate the first experimental realization of a dispersionless state, in a photonic Lieb lattice formed by an array of optical waveguides. This engineered lattice supports three energy bands, including a perfectly flat middle band with an infinite effective mass. We analyze, both experimentally and theoretically, the evolution of well-prepared flat-band states, and show their remarkable robustness, even in the presence of disorder. The realization of flat-band states in photonic lattices opens an exciting door towards quantum simulation of flat-band models in a highly controllable environment.
Nonabelian Duality and Solvable Large N Lattice Systems
Dubin, A Yu
2000-01-01
We introduce the basics of the nonabelian duality transformation of SU(N) or U(N) vector-field models defined on a lattice. The dual degrees of freedom are certain species of the integer-valued fields complemented by the symmetric groups' øtimes_{n} S(n) variables. While the former parametrize relevant irreducible representations, the latter play the role of the Lagrange multipliers facilitating the fusion rules involved. As an application, I construct a novel solvable family of SU(N) D-matrix systems graded by the rank Their large N solvability is due to a hidden invariance (explicit in the dual formulation) which allows for a mapping onto the recently proposed eigenvalue-models \\cite{Dub1} with the largest k=D symmetry. Extending energy given (modulo the volume factor) by the free energy of a given proposed formalism provides with the basis for higher-dimensional generalizations of the Gross-Taylor stringy representation of strongly coupled 2d gauge theories.
Negative Dispersion of Lattice Waves in a Two-Dimensional Yukawa System
Institute of Scientific and Technical Information of China (English)
刘艳红; 刘斌; 杨思泽; 王龙
2002-01-01
Collective motion modes existing in a two-dimensional Yukawa system are investigated by molecular dynamics simulation. The dispersion relations of transverse and longitudinal lattice waves obtained for hexagonal lattice are in agreement with the theoretical results. The negative dispersion of the parallel longitudinal wave is demonstrated by the simulation, and is explained by a physical model.
Institute of Scientific and Technical Information of China (English)
杨世平; 田钢; 屈进禄; 徐树山
1999-01-01
One-way coupled optical bnstability lattice (OCBL) system for open flow is investigated. By using numerical simulations spatiotemporal quasiperiodicity is found. A rough phase diagram indicating the main spatiotemporal dynamic behavior in weakly coupled lattice is given. The transitions between spatiotemporal quasiperiodicity and chaos are observed. This result is important for the understanding of turbulence.
Quantum spin systems on infinite lattices a concise introduction
Naaijkens, Pieter
2017-01-01
This course-based primer offers readers a concise introduction to the description of quantum mechanical systems with infinitely many degrees of freedom – and quantum spin systems in particular – using the operator algebraic approach. Here, the observables are modeled using elements of some operator algebra, usually a C*-algebra. This text introduces readers to the framework and the necessary mathematical tools without assuming much mathematical background, making it more accessible than advanced monographs. The book also highlights the usefulness of the so-called thermodynamic limit of quantum spin systems, which is the limit of infinite system size. For example, this makes it possible to clearly distinguish between local and global properties, without having to keep track of the system size. Together with Lieb-Robinson bounds, which play a similar role in quantum spin systems to that of the speed of light in relativistic theories, this approach allows ideas from relativistic field theories to be implemen...
Synchronization in lattices of coupled non-autonomous Chen system via Lyapunov function
Institute of Scientific and Technical Information of China (English)
CHEN tao; ZHOU Sheng-fan
2009-01-01
This paper consider the synchronization of solutions for lattices of the coupled non-autonomous Chen system. By using the Lyapunov function, we show that when the second coupled operator is negative definite self-adjoint and its coefficient is suitable large, the Chen coupled lattice system is bounded dissipative (In particular, the solutions for lattices of the coupled autonomous Chen system converge to zero as t→∞). The synchronization between any two solutions of the coupled Chen system can be slaved only by coefficients in the x- or y-component for the suitably large second coupled coefficient. Finally,some numerical simulations are given.
Local-Global Interactions in the Transient Response of Lattice-Truss Plates.
1984-08-01
plate model subjected to an initial out-of-plane impulse at the lower left corner. The color scale at the right of each frame represents variations of...Fiur 4. RepneapeLoain (Core ~ ~ ~ \\ and uppe sufc ebr emvdfrcaiy 23 TETRA 11 - Tranwlezt nleporave fLvtorvy 0.003 - Mrst Uccde Ix3ltial Impulse ...vidual lattice members dynamic characteristics influence the transient response charac- teristics. When the lattice members are modeled as bars. the
Energy Technology Data Exchange (ETDEWEB)
Kaczmarczyk, G.
2006-07-01
The group III-nitrides and zinc oxide are in the focus of material research because of their high application potential. The presentation of the first UV laser diode as well as blue light emitting diodes were the preliminary highlights. Although of all technological progress many physical questions are still open. In this work some of these questions are examined experimentally with Raman-scattering and theoretically with valence-force calculations. Many physical properties such as strain and doping concentration affect the lattice dynamics. As a start the phonons of the center of the Brillouin-zone in GaN, AlN, InN and ZnO are studied with first-order Raman-scattering. These results are the basis for advanced investigations. The acoustical and optical modes at the zone boundary and their combinations and overtones are determinated from the second-order Raman-scattering. Using the valence-force calculations the experimental frequencies are assigned to particular phonon branches or points of the Brillouin zone. The second part of this work treats systematically the physics of local vibrational modes. They occur due to intrinsic defects or impurities in the semiconductors. They are investigated with respect to the vibrational properties of the unperturbed crystals. In order to assign new experimentally found structures, calculations of local vibrational modes in GaN:Mg, GaN:As and ZnO:N systems were carried out. Furthermore, the calculations in Si- and C-doped hexagonal GaN suggest the frequency range for local vibrational modes. In the last section the influence of external parameters such as temperature or strain on the phonon frequency is analyzed. It is shown, that the influence on the temperature dependence of host phonons and local vibrational modes are dominated through different effects. In case of the host phonons it is mainly due to the volume effect whereas the local modes are highly affected by the anharmonic decay. Moreover, the calculations verified
Energy Technology Data Exchange (ETDEWEB)
Gong, Longyan, E-mail: lygong@njupt.edu.cn [Information Physics Research Center and Department of Applied Physics, Nanjing University of Posts and Telecommunications, Nanjing, 210003 (China); Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing, 210003 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Feng, Yan; Ding, Yougen [Information Physics Research Center and Department of Applied Physics, Nanjing University of Posts and Telecommunications, Nanjing, 210003 (China); Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing, 210003 (China)
2017-02-12
Highlights: • Quasiperiodic lattice models with next-nearest-neighbor hopping are studied. • Shannon information entropies are used to reflect state localization properties. • Phase diagrams are obtained for the inverse bronze and golden means, respectively. • Our studies present a more complete picture than existing works. - Abstract: We explore the reduced relative Shannon information entropies SR for a quasiperiodic lattice model with nearest- and next-nearest-neighbor hopping, where an irrational number is in the mathematical expression of incommensurate on-site potentials. Based on SR, we respectively unveil the phase diagrams for two irrationalities, i.e., the inverse bronze mean and the inverse golden mean. The corresponding phase diagrams include regions of purely localized phase, purely delocalized phase, pure critical phase, and regions with mobility edges. The boundaries of different regions depend on the values of irrational number. These studies present a more complete picture than existing works.
Baskaran, G.
1989-01-01
Using a nonmean-field approach the triangular-lattice S = 1/2 Heisenberg antiferromagnet with nearest- and next-nearest-neighbor couplings is shown undergo an Ising-type phase transition into a chiral-symmetry-broken phase (Kalmeyer-Laughlin-like state) at small T. Removal of next-nearest-neighbor coupling introduces a local Z2 symmetry, thereby suppressing any finite-T chiral order.
Directory of Open Access Journals (Sweden)
J.-M. Caillol
2013-01-01
Full Text Available We establish the critical line of the one-component Φ4 (or Landau-Ginzburg model on a simple four dimensional cubic lattice. Our study is performed in the framework of the non-perturbative renormalization group in the local potential approximation with a soft infra-red regulator. The transition is found to be of second order even in the Gaussian limit where first order would be expected according to some recent theoretical predictions.
Persistence of locality in systems with power-law interactions
Gong, Zhe-Xuan; Michalakis, Spyridon; Gorshkov, Alexey V
2014-01-01
Motivated by recent experiments with ultra-cold matter, we derive a new bound on the propagation of information in $D$-dimensional lattice models exhibiting $1/r^{\\alpha}$ interactions with $\\alpha>D$. The bound contains two terms: One accounts for the short-ranged part of the interactions, giving rise to a bounded velocity and reflecting the persistence of locality out to intermediate distances, while the other contributes a power-law decay at longer distances. We demonstrate that these two contributions not only bound but $qualitatively~reproduce$ the short- and long-distance dynamical behavior following a local quench in an $XY$ chain and a transverse-field Ising chain. In addition to describing dynamics in numerous intractable long-range interacting lattice models, our results can be experimentally verified in a variety of ultracold-atomic and solid-state systems.
Teherani, James T
2013-01-01
We have developed a physically-intuitive method to calculate the local lattice constant as a function of position in a high-resolution transmission electron microscopy image by performing a two-dimensional fast Fourier transform. We apply a Gaussian filter with appropriate spatial full-width-half-max (FWHM) bandwidth to the image centered at the desired location to calculate the local lattice constant (as opposed to the average lattice constant). Fourier analysis of the filtered image yields the vertical and horizontal lattice constants at this location. The process is repeated by stepping the Gaussian filter across the image to produce a set of local lattice constants in the vertical and horizontal direction as a function of position in the image. The method has been implemented in a freely available tool on nanoHUB.
Local lattice distortions vs. structural phase transition in NdFeAsO1-xFx
Calamiotou, M.; Lampakis, D.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Fitch, A.; Tsiaklagkanos, P.; Liarokapis, E.
2016-08-01
The lattice properties at low temperatures of two samples of NdFeAsO1-xFx (x = 0.05 and 0.25) have been examined in order to investigate possible structural phase transition that may occur in the optimally doped superconducting sample with respect to the non-superconducting low-F concentration compound. In order to detect small modifications in the ion displacements with temperature micro-Raman and high resolution synchrotron powder diffraction measurements were carried out. No increase of the width of the (2 2 0) or (3 2 2) tetragonal diffraction peaks and microstrains could be found in the superconducting sample from synchrotron XRD measurements. On the other hand, the atomic displacement parameters deviate from the expected behavior, in agreement with modifications in the phonon width, as obtained by Raman scattering. These deviations occur around 150 K for both F dopings, with distinct differences among the two compounds, i.e., they decrease at low doping and increase for the superconducting sample. The data do not support a hidden phase transition to an orthorhombic phase in the superconducting compound, but point to an isostructural lattice deformation. Based on the absence of magnetic effects in this temperature range for the superconducting sample, we attribute the observed lattice anomalies to the formation of local lattice distortions that, being screened by the carriers, can only acquire long-range coherence by means of a structural phase transition at low doping levels.
Mazzucchi, Gabriel; Caballero-Benitez, Santiago F; Elliott, Thomas J; Mekhov, Igor B
2015-01-01
Trapping ultracold atoms in optical lattices enabled numerous breakthroughs uniting several disciplines. Although the light is a key ingredient in such systems, its quantum properties are typically neglected, reducing the role of light to a classical tool for atom manipulation. Here we show how elevating light to the quantum level leads to novel phenomena, inaccessible in setups based on classical optics. Interfacing a many-body atomic system with quantum light opens it to the environment in an essentially nonlocal way, where spatial coupling can be carefully designed. The competition between typical processes in strongly correlated systems (local tunnelling and interaction) with global measurement backaction leads to novel multimode dynamics and the appearance of long-range correlated tunnelling capable of entangling distant lattices sites, even when tunnelling between neighbouring sites is suppressed by the quantum Zeno effect. We demonstrate both the break-up and protection of strongly interacting fermion ...
Gap solitons in periodic Schrodinger lattice system with nonlinear hopping
Directory of Open Access Journals (Sweden)
Ming Cheng
2016-10-01
Full Text Available This article concerns the periodic discrete Schrodinger equation with nonlinear hopping on the infinite integer lattice. We obtain the existence of gap solitons by the linking theorem and concentration compactness method together with a periodic approximation technique. In addition, the behavior of such solutions is studied as $\\alpha\\to 0$. Notice that the nonlinear hopping can be sign changing.
Attractors for stochastic lattice dynamical systems with a multiplicative noise
Institute of Scientific and Technical Information of China (English)
Tomás CARABALLO; Kening LU
2008-01-01
In this paper,we consider a stochastic lattice differential equation with diffusive nearest neighbor interaction,a dissipative nonlinear reaction term,and multiplicative white noise at each node.We prove the existence of a compact global random attractor which,pulled back,attracts tempered random bounded sets.
Local lattice distortions vs. structural phase transition in NdFeAsO{sub 1−x}F{sub x}
Energy Technology Data Exchange (ETDEWEB)
Calamiotou, M., E-mail: mcalam@phys.uoa.gr [Solid State Physics Department, Faculty of Physics, University of Athens, GR-15784 Athens (Greece); Lampakis, D. [TEI Larissa, GR 41334 Larissa (Greece); Zhigadlo, N.D.; Katrych, S.; Karpinski, J. [Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich (Switzerland); Fitch, A. [ESRF, The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble (France); Tsiaklagkanos, P.; Liarokapis, E. [Department of Physics, National Technical University of Athens, GR15780, Athens (Greece)
2016-08-15
Highlights: • We studied two concentrations, representatives of the superconducting and the non-superconducting regions of the phase diagram of NdFeAsO{sub 1−x}F{sub x} system, by combining high resolution high statistics synchrotron diffraction with micro-Raman data as a function of temperature. • The evolution of the atomic displacement parameters, which agree with modifications in the phonon spectra, point to an isostructural disorded phase in the superconducting sample, in contrast to a tetragonal to orthorhombic long range phase transition that occurs at low doping. • Based on the absence of magnetic effects in this temperature range for the superconducting sample, we attribute the observed lattice anomalies to the formation of local lattice distortions that, being screened by the carriers, can only acquire long-range coherence by means of a structural phase transition at low doping levels. - Abstract: The lattice properties at low temperatures of two samples of NdFeAsO{sub 1−x}F{sub x} (x = 0.05 and 0.25) have been examined in order to investigate possible structural phase transition that may occur in the optimally doped superconducting sample with respect to the non-superconducting low-F concentration compound. In order to detect small modifications in the ion displacements with temperature micro-Raman and high resolution synchrotron powder diffraction measurements were carried out. No increase of the width of the (2 2 0) or (3 2 2) tetragonal diffraction peaks and microstrains could be found in the superconducting sample from synchrotron XRD measurements. On the other hand, the atomic displacement parameters deviate from the expected behavior, in agreement with modifications in the phonon width, as obtained by Raman scattering. These deviations occur around 150 K for both F dopings, with distinct differences among the two compounds, i.e., they decrease at low doping and increase for the superconducting sample. The data do not support a hidden
Energy Technology Data Exchange (ETDEWEB)
Strečka, Jozef, E-mail: jozef.strecka@upjs.sk [Department of Theoretical Physics and Astrophysics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 040 01 Košice (Slovakia); Čenčariková, Hana [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice (Slovakia); Lyra, Marcelo L. [Instituto de Fisica, Universidade Federal de Alagoas, 57072-970 Maceió, AL (Brazil)
2015-12-04
Phase diagrams and thermodynamic properties of a correlated spin–electron system considering localized Ising spins on nodal sites and mobile electrons on decorating sites of doubly decorated planar lattices are rigorously examined with the help of generalized decoration–iteration transformation. The investigated model defined on loose-packed (honeycomb and square) lattices exhibits the phase diagram including a spontaneous ferromagnetic and antiferromagnetic order in a vicinity of quarter and half-filling, respectively, while the same model on close-packed (triangular and kagome) lattices only shows a spontaneous ferromagnetic order due to a kinetically-driven spin frustration at high electron concentrations. The lower critical concentration, at which the ferromagnetic order appears, is remarkably close to a bond percolation threshold in spite of the annealed character of the developed procedure. The specific heat exhibits at the critical temperature either a logarithmic divergence for integer-valued electron concentrations or it shows a finite-cusp for any non-integer electron concentration due to the annealed bond disorder. - Highlights: • Correlated spin–electron system on decorated 2D lattices is exactly solved. • Phase diagrams involve ferro- and antiferromagnetic order near 1/4 and 1/2 filling. • Magnetization is not saturated at zero temperature due to the annealed disorder. • Specific heat displays a finite cusp at the critical temperature.
Institute of Scientific and Technical Information of China (English)
Zhao Gang-Ling; Chen Li-Qun; Fu Jing-Li; Hong Fang-Yu
2013-01-01
In this paper,Noether symmetry and Mei symmetry of discrete nonholonomic dynamical systems with regular and the irregular lattices are investigated.Firstly,the equations of motion of discrete nonholonomic systems are introduced for regular and irregular lattices.Secondly,for cases of the two lattices,based on the invariance of the Hamiltomian functional under the infinitesimal transformation of time and generalized coordinates,we present the quasi-extremal equation,the discrete analogues of Noether identity,Noether theorems,and the Noether conservation laws of the systems.Thirdly,in cases of the two lattices,we study the Mei symmetry in which we give the discrete analogues of the criterion,the theorem,and the conservative laws of Mei symmetry for the systems.Finally,an example is discussed for the application of the results.
Spatiotemporal dynamics of a digital phase-locked loop based coupled map lattice system
Banerjee, Tanmoy; Paul, Bishwajit; Sarkar, B. C.
2014-03-01
We explore the spatiotemporal dynamics of a coupled map lattice (CML) system, which is realized with a one dimensional array of locally coupled digital phase-locked loops (DPLLs). DPLL is a nonlinear feedback-controlled system widely used as an important building block of electronic communication systems. We derive the phase-error equation of the spatially extended system of coupled DPLLs, which resembles a form of the equation of a CML system. We carry out stability analysis for the synchronized homogeneous solutions using the circulant matrix formalism. It is shown through extensive numerical simulations that with the variation of nonlinearity parameter and coupling strength the system shows transitions among several generic features of spatiotemporal dynamics, viz., synchronized fixed point solution, frozen random pattern, pattern selection, spatiotemporal intermittency, and fully developed spatiotemporal chaos. We quantify the spatiotemporal dynamics using quantitative measures like average quadratic deviation and spatial correlation function. We emphasize that instead of using an idealized model of CML, which is usually employed to observe the spatiotemporal behaviors, we consider a real world physical system and establish the existence of spatiotemporal chaos and other patterns in this system. We also discuss the importance of the present study in engineering application like removal of clock-skew in parallel processors.
Some properties of correlations of quantum lattice systems in thermal equilibrium
Energy Technology Data Exchange (ETDEWEB)
Fröhlich, Jürg, E-mail: juerg@phys.ethz.ch [Institut für Theoretische Physik, ETH Zürich (Switzerland); Ueltschi, Daniel, E-mail: daniel@ueltschi.org [Department of Mathematics, University of Warwick, Coventry CV4 7AL (United Kingdom)
2015-05-15
Simple proofs of uniqueness of the thermodynamic limit of KMS states and of the decay of equilibrium correlations are presented for a large class of quantum lattice systems at high temperatures. New quantum correlation inequalities for general Heisenberg models are described. Finally, a simplified derivation of a general result on power-law decay of correlations in 2D quantum lattice systems with continuous symmetries is given, extending results of McBryan and Spencer for the 2D classical XY model.
Energy Technology Data Exchange (ETDEWEB)
Elton, A.B.H.
1990-09-24
A numerical theory for the massively parallel lattice gas and lattice Boltzmann methods for computing solutions to nonlinear advective-diffusive systems is introduced. The convergence theory is based on consistency and stability arguments that are supported by the discrete Chapman-Enskog expansion (for consistency) and conditions of monotonicity (in establishing stability). The theory is applied to four lattice methods: Two of the methods are for some two-dimensional nonlinear diffusion equations. One of the methods is for the one-dimensional lattice method for the one-dimensional viscous Burgers equation. And one of the methods is for a two-dimensional nonlinear advection-diffusion equation. Convergence is formally proven in the L{sub 1}-norm for the first three methods, revealing that they are second-order, conservative, conditionally monotone finite difference methods. Computational results which support the theory for lattice methods are presented. In addition, a domain decomposition strategy using mesh refinement techniques is presented for lattice gas and lattice Boltzmann methods. The strategy allows concentration of computational resources on regions of high activity. Computational evidence is reported for the strategy applied to the lattice gas method for the one-dimensional viscous Burgers equation. 72 refs., 19 figs., 28 tabs.
A Few Discrete Lattice Systems and Their Hamiltonian Structures, Conservation Laws
Guo, Xiu-Rong; Zhang, Yu-Feng; Zhang, Xiang-Zhi; Yue, Rong
2017-04-01
With the help of three shift operators and r-matrix theory, a few discrete lattice systems are obtained which can be reduced to the well-known Toda lattice equation with a constraint whose Hamiltonian structures are generated by Poisson tensors of some induced Lie-Poisson bracket. The recursion operators of these lattice systems are constructed starting from Lax representations. Finally, reducing the given shift operators to get a simpler one and its expanding shift operators, we produce a lattice system with three vector fields whose recursion operator is given. Furthermore, we reduce the lattice system with three vector fields to get a lattice system whose Lax pair and conservation laws are obtained, respectively. Supported by the National Natural Science Foundation of China under Grant No. 11371361, the Innovation Team of Jiangsu Province Hosted by China University of Mining and Technology (2014), the the Key Discipline Construction by China University of Mining and Technology under Grant No. XZD201602, the Shandong Provincial Natural Science Foundation, China under Grant Nos. ZR2016AM31, ZR2016AQ19, ZR2015EM042, the Development of Science and Technology Plan Projects of TaiAn City under Grant No. 2015NS1048, National Social Science Foundation of China under Grant No. 13BJY026, and A Project of Shandong Province Higher Educational Science and Technology Program under Grant No. J14LI58
Dynamical Behavior of Multi-Robot Systems Using Lattice Gas Automata
Energy Technology Data Exchange (ETDEWEB)
Cameron, S.M.; Robinett, R.; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.
1999-03-11
Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems. Our group has been studying the collective behavior of autonomous, multi-agent systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi-robotic and multi-agents architectures. Our goal is to coordinate a constellation of point sensors that optimizes spatial coverage and multivariate signal analysis using unmanned robotic vehicles (e.g., RATLERs, Robotic All-ten-sin Lunar Exploration Rover-class vehicles). Overall design methodology is to evolve complex collective behaviors realized through simple interaction (kinetic) physics and artificial intelligence to enable real-time operational responses to emerging threats. This paper focuses on our recent work understanding the dynamics of many-body systems using the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's deformation rate, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent non-linearity of the dynamical equations describing large ensembles, development of stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots that maneuvers past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with
The mean field study of phase transitions in two dimensional Kagome lattice under local anisotropy
Directory of Open Access Journals (Sweden)
S. Mortezapour
2007-06-01
Full Text Available In this work we investigated the critical properties of the anti-ferromagnetic XY model on a two dimensional Kagome lattice under single-ion easy-axes anisotropy. Employing the mean field theory, we found that this model shows a second order phase transition from disordered to all-in all-out state for any value of anisotropy.
Gong, Longyan; Feng, Yan; Ding, Yougen
2017-02-01
We explore the reduced relative Shannon information entropies SR for a quasiperiodic lattice model with nearest- and next-nearest-neighbor hopping, where an irrational number is in the mathematical expression of incommensurate on-site potentials. Based on SR, we respectively unveil the phase diagrams for two irrationalities, i.e., the inverse bronze mean and the inverse golden mean. The corresponding phase diagrams include regions of purely localized phase, purely delocalized phase, pure critical phase, and regions with mobility edges. The boundaries of different regions depend on the values of irrational number. These studies present a more complete picture than existing works.
DEFF Research Database (Denmark)
Eskildsen, M.R.; Fisher, I.R.; Gammel, P.L.
2000-01-01
Using small angle neutron scattering we have studied the square to hexagonal flux line lattice symmetry transition in different members of the borocarbide superconductors. The studies were performed using samples of ErNi2B2C, Lu(Ni1-xCox)(2)B2C with cobalt doping levels x = 1.5-9% and Y0.64Lu0.36...... that the transition onset follows a model by V. Kogan et nl., which includes non-local corrections to the London model due to the Fermi surface anisotropy of the borocarbides. (C) 2000 Elsevier Science B.V. All rights reserved....
Temperature-dependent EXAFS study of the local structure and lattice dynamics in cubic Y₂O₃.
Jonane, Inga; Lazdins, Karlis; Timoshenko, Janis; Kuzmin, Alexei; Purans, Juris; Vladimirov, Pavel; Gräning, Tim; Hoffmann, Jan
2016-03-01
The local structure and lattice dynamics in cubic Y2O3 were studied at the Y K-edge by X-ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X-ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ∼6 Å and to validate two force-field models.
Lattice gas automata for flow and transport in geochemical systems
Energy Technology Data Exchange (ETDEWEB)
Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.
1992-05-01
Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.
Lattice gas automata for flow and transport in geochemical systems
Energy Technology Data Exchange (ETDEWEB)
Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.
1992-01-01
Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.
Local renormalization method for random systems
Gittsovich O.; Hubener R.; Rico E.; Briegel H.J.
2010-01-01
In this paper, we introduce a real-space renormalization transformation for random spin systems on 2D lattices. The general method is formulated for random systems and results from merging two well known real space renormalization techniques, namely the strong disorder renormalization technique (SDRT) and the contractor renormalization (CORE). We analyze the performance of the method on the 2D random transverse field Ising model (RTFIM).
Shahzad, Munir; Sengupta, Pinaki
2017-08-01
We study the Shastry-Sutherland Kondo lattice model with additional Dzyaloshinskii-Moriya (DM) interactions, exploring the possible magnetic phases in its multi-dimensional parameter space. Treating the local moments as classical spins and using a variational ansatz, we identify the parameter ranges over which various common magnetic orderings are potentially stabilized. Our results reveal that the competing interactions result in a heightened susceptibility towards a wide range of spin configurations including longitudinal ferromagnetic and antiferromagnetic order, coplanar flux configurations and most interestingly, multiple non-coplanar configurations including a novel canted-flux state as the different Hamiltonian parameters like electron density, interaction strengths and degree of frustration are varied. The non-coplanar and non-collinear magnetic ordering of localized spins behave like emergent electromagnetic fields and drive unusual transport and electronic phenomena.
Evolution of soliton-like train in Klein-Gordon lattice system
Institute of Scientific and Technical Information of China (English)
Xia Qing-Lin; Yi Jian-Hong; Peng Yuan-Dong; Ye Tu-Ming; Li Li-Ya; Wang Hong-Zhong
2007-01-01
This paper studies the evolution of wave in the system of a pure anharmonic lattice with a double well on-site potential by numerical calculation. It finds that an initial distribution of static or moving wave can evolve into two travelling soliton-like trains with contrary directions and a region of oscillation in this lattice system. It presents that some cases with cosine-square-shape and Gaussian-shape initial distribution of static or moving wave will produce ordered soliton-like train. Careful numerical observation shows that the centre oscillation region in this system may act as a resource of generating soliton-like train.
Institute of Scientific and Technical Information of China (English)
Xu Quan; Tian Qiang
2009-01-01
This paper discusses the two-dimensional discrete monatomic Fermi-Pasta-Ulam lattice, by using the method of multiple-scale and the quasi-discreteness approach. By taking into account the interaction between the atoms in the lattice and their nearest neighbours, it obtains some classes of two-dimensional local models as follows: two-dimensional bright and dark discrete soliton trains, two-dimensional bright and dark line discrete breathers, and two-dimensional bright and dark discrete breather.
Interplay of Anderson localization and strong interaction in disordered systems
Energy Technology Data Exchange (ETDEWEB)
Henseler, Peter
2010-01-15
We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length {xi}, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of {xi} for small and intermediate disorders and a strong reduction of {xi} due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of {xi} as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)
Properties of localization in silicon-based lattice periodicity breaking photonic crystal waveguides
Energy Technology Data Exchange (ETDEWEB)
Wu, Yuquan; Wang, Xiaofei; Wang, Yufang; Zhang, Guoquan; Fan, Wande; Cao, Xuewei, E-mail: xwcao@nankai.edu.cn [School of Physics, Nankai University, Tianjin, 300071 (China); Wu, Yuanbin [School of Physics, Nankai University, Tianjin, 300071 (China); Dip. di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, I-00185 Roma (Italy); EDSFA, Université de Nice Sophia Antipolis, 06103 Nice (France)
2013-11-15
The light localization effects in silicon photonic crystal cavities at different disorder degrees have been studied using the finite difference time domain (FDTD) method in this paper. Numerical results showed that localization occurs and enhancement can be gained in the region of the cavity under certain conditions. The stabilities of the localization effects due to the structural perturbations have been investigated too. Detailed studies showed that when the degree of structural disorder is small(about 10%), the localization effects are stable, the maximum enhancement factor can reach 16.5 for incident wavelength of 785 nm and 23 for 850 nm in the cavity, with the degree of disorder about 8%. The equivalent diameter of the localized spot is almost constant at different disorder degrees, approximating to λ/7, which turned out to be independent on the structural perturbation.
Toda Lattice Solutions of Differential-Difference Equations for Dissipative Systems
Igarashi, Y; Nakanishi, K; Igarashi, Yuji; Itoh, Katsumi; Nakanishi, Ken
1998-01-01
In a certain class of differential-difference equations for dissipative systems, we show that hyperbolic tangent model is the only the nonlinear system of equations which can admit some particular solutions of the Toda lattice. We give one parameter family of exact solutions, which include as special cases the Toda lattice solutions as well as the Whitham's solutions in the Newell's model. Our solutions can be used to describe temporal-spatial density patterns observed in the optimal velocity model for traffic flow.
Fang, Wen; Wang, Jun
2013-09-01
We develop a financial market model using an Ising spin system on a Sierpinski carpet lattice that breaks the equal status of each spin. To study the fluctuation behavior of the financial model, we present numerical research based on Monte Carlo simulation in conjunction with the statistical analysis and multifractal analysis of the financial time series. We extract the multifractal spectra by selecting various lattice size values of the Sierpinski carpet, and the inverse temperature of the Ising dynamic system. We also investigate the statistical fluctuation behavior, the time-varying volatility clustering, and the multifractality of returns for the indices SSE, SZSE, DJIA, IXIC, S&P500, HSI, N225, and for the simulation data derived from the Ising model on the Sierpinski carpet lattice. A numerical study of the model’s dynamical properties reveals that this financial model reproduces important features of the empirical data.
Directory of Open Access Journals (Sweden)
David Bruce Borenstein
Full Text Available Many cellular populations cooperate through the secretion of diffusible extracellular resources, such as digestive enzymes or virulence factors. Diffusion of these resources leads to long-range intercellular interactions, creating the possibility of cooperation but also the risk of exploitation by non-producing neighbors. In the past, considerable attention has been given to game-theoretic lattice models of intercellular cooperation. In these models, coexistence is commonly observed between cooperators (corresponding to resource producers and cheaters (corresponding to nonproducers. However, these models consider only interactions between direct competitors. We find that when individuals are allowed to interact non-locally through the diffusion of a shared resource coexistence between cooperators and cheaters is lost. Instead, we find population dynamics similar to simple competition, either neutral or biased, with no balancing selection that would favor coexistence. Our results highlight the importance of an accurate treatment of diffusion of shared resources and argue against the generality of the conclusions of game-theoretic lattice models.
Energy Technology Data Exchange (ETDEWEB)
Karlin, I.; Frouzakis, Ch.; Boulouchos, K.
2007-07-01
This final report for the Swiss Federal Office of Energy (SFOE) reports on work done in 2007 at the Swiss Federal Institute of Technology ETH in Zurich on simulation methods for chemically reactive systems at the micrometer scale. The Lattice-Boltzmann method using lattice models is examined and the results obtained are discussed. A three-dimensional thermal model was developed and used to analyse flows with considerable temperature and density variations. The model was also used for the analysis of flows in diluted gases. A method for the reduction of complex reaction mechanisms was developed and tested for future combustion applications. 30 publications are noted and new possibilities for the analysis of flows in micro-channels and porous media - as used in reformers, catalyzers and fuel cells - are discussed.
Synthetic Dimensions with Magnetic Fields and Local Interactions in Photonic Lattices.
Ozawa, Tomoki; Carusotto, Iacopo
2017-01-06
We discuss how one can realize a photonic device that combines synthetic dimensions and synthetic magnetic fields with spatially local interactions. Using an array of ring cavities, the angular coordinate around each cavity spans the synthetic dimension. The synthetic magnetic field arises as the intercavity photon hopping is associated with a change of angular momentum. Photon-photon interactions are local in the periodic angular coordinate around each cavity. Experimentally observable consequences of the synthetic magnetic field and of the local interactions are pointed out.
Synthetic dimensions with magnetic fields and local interactions in photonic lattices
Ozawa, Tomoki
2016-01-01
We discuss how one can realize a photonic device that combines synthetic dimensions and synthetic magnetic fields with spatially local interactions. Using an array of ring resonators, the angular coordinate around each resonator spans the synthetic dimension and the synthetic magnetic field arises as the inter-cavity photon hopping is associated to a change of angular momentum. Photon-photon interactions due to the non-linearity of the cavity material are local in the periodic angular coordinate around each ring resonator. Experimentally observable consequences of the synthetic magnetic field and of the local interactions are pointed out.
Marikhin, V. G.
2016-12-01
We construct a three-dimensional octahedral lattice of Bäcklund transformations of integrable cases of the Davey-Stewartson system. At the lattice sites, we arrange functions, which, on one hand, are used to define the dynamical variables of the Davey-Stewartson system and, on the other hand, are connected by bilinear relations of the Hirota type. One of the lattice equations is a purely discrete six-point equation that coincides with the famous Hirota equation.
Local entropy of a nonequilibrium fermion system
Stafford, Charles A.; Shastry, Abhay
2017-03-01
The local entropy of a nonequilibrium system of independent fermions is investigated and analyzed in the context of the laws of thermodynamics. It is shown that the local temperature and chemical potential can only be expressed in terms of derivatives of the local entropy for linear deviations from local equilibrium. The first law of thermodynamics is shown to lead to an inequality, not equality, for the change in the local entropy as the nonequilibrium state of the system is changed. The maximum entropy principle (second law of thermodynamics) is proven: a nonequilibrium distribution has a local entropy less than or equal to a local equilibrium distribution satisfying the same constraints. It is shown that the local entropy of the system tends to zero when the local temperature tends to zero, consistent with the third law of thermodynamics.
Dobrokhotov, S. Yu.; Nazaikinskii, V. E.
2017-01-01
The following results are obtained for the Cauchy problem with localized initial data for the crystal lattice vibration equations with continuous and discrete time: (i) the asymptotics of the solution is determined by Lagrangian manifolds with singularities ("punctured" Lagrangian manifolds); (ii) Maslov's canonical operator is defined on such manifolds as a modification of a new representation recently obtained for the canonical operator by the present authors together with A. I. Shafarevich (Dokl. Ross. Akad. Nauk 46 (6), 641-644 (2016)); (iii) the projection of the Lagrangian manifold onto the configuration plane specifies a bounded oscillation region, whose boundary (which is naturally referred to as the leading edge front) is determined by the Hamiltonians corresponding to the limit wave equations; (iv) the leading edge front is a special caustic, which possibly contains stronger focal points. These observations, together with earlier results, lead to efficient formulas for the wave field in a neighborhood of the leading edge front.
Energy Technology Data Exchange (ETDEWEB)
Xi, Kui-Tian, E-mail: kuitianxi@gmail.com; Li, Jinbin, E-mail: jinbin@nuaa.edu.cn; Shi, Da-Ning, E-mail: shi@nuaa.edu.cn
2014-03-01
We consider a weakly interacting two-component Bose–Einstein condensate (BEC) in a two-dimensional (2D) quasi-periodic bichromatic optical lattice (BOL). The problem is studied by means of split-step Crank–Nicolson method. The effects of weak intra- and inter-component interactions on localization of a two-component BEC are investigated. It is shown that in the quasi-2D regime, due to the enhanced disorder, there is no symmetry breaking like that in the one-dimensional (1D) case under a sine-typed potential, while configurations of density profiles are also quite different from that in the 1D case. By modulating interactions, the interplay of disorder and weak repulsive or attractive interactions is studied in detail. The cases with sine- and cosine-typed potentials acting on components 1 and 2 respectively are also discussed.
Dual Lattice of ℤ-module Lattice
Directory of Open Access Journals (Sweden)
Futa Yuichi
2017-07-01
Full Text Available In this article, we formalize in Mizar [5] the definition of dual lattice and their properties. We formally prove that a set of all dual vectors in a rational lattice has the construction of a lattice. We show that a dual basis can be calculated by elements of an inverse of the Gram Matrix. We also formalize a summation of inner products and their properties. Lattice of ℤ-module is necessary for lattice problems, LLL(Lenstra, Lenstra and Lovász base reduction algorithm and cryptographic systems with lattice [20], [10] and [19].
Propagation and collision of compacton-like kinks in Klein-Gordon lattice system
Institute of Scientific and Technical Information of China (English)
Xia Qing-Lin; Yi Jina-Hong; Li Li-Ya; Peng Yuan-Dong
2005-01-01
We study the propagation and collision of the compacton-like kinks in the system of an anharmoniclattice with a double well on -site potential by a direc algebraic method and numerical experiments. It is found that the localiazation of the compacton-like kinks is related to the nonlinear coupling parameter Cnl and the potetial barrier height v0 of the double well potential. The velocity of the propagation of the compacton like kinks is determined by the linear coupling parameter cl, the nlonlinear coupling parameter Cnl and the localization paratmeter q. Numerical experiments demonstrate that appropriate Cl is not detrimental to a stable propagation of the compacton-like kinks. However, the collision of compacton-like kiks and anti-kinds in the lattice with comparatively smallCl leads to the emergence of a discrete stationary breather and small amplitude nonlinear oscillation bacdground ,while moderate Cl results in the emergence of two deformed kinds with raditing oscillations and lower propagation velocities.
Bender, N; Ellis, F M; Kottos, T
2015-01-01
We propose a family of {\\it local} $\\cal{PT}$-symmetric photonic lattices with transverse index gradient $\\omega$, where the emergence of {\\it stable} Bloch-Zener oscillations are controlled by the degree of non-Hermiticity $\\gamma$ of the lattice. In the exact $\\cal{PT}$-symmetric phase we identify a condition between $\\omega$ and $\\gamma$ for which a wavepacket self -imaging together with a cascade of splittings and giant recombinations occurs at various propagation distances. The giant wavepacket recombination is further enhanced by introducing local impurities.
Colour Fields Computed in SU(3) Lattice QCD for the Static Tetraquark System
Cardoso, N; Bicudo, P
2011-01-01
The colour fields created by the static tetraquark system are computed in quenched SU(3) lattice QCD, in a $24^3\\times 48$ lattice at $\\beta=6.2$ corresponding to a lattice spacing $a=0.07261(85)$ fm. We find that the tetraquark colour fields are well described by a double-Y, or butterfly, shaped flux tube. The two flux tube junction points are compatible with Fermat points minimizing the total flux tube length. We also compare the diquark-diantiquark central flux tube profile in the tetraquark with the quark-antiquark fundamental flux tube profile in the meson, and they match, thus showing that the tetraquark flux tubes are composed of fundamental flux tubes.
Novotny, M.A.
2010-02-01
The efficiency of dynamic Monte Carlo algorithms for off-lattice systems composed of particles is studied for the case of a single impurity particle. The theoretical efficiencies of the rejection-free method and of the Monte Carlo with Absorbing Markov Chains method are given. Simulation results are presented to confirm the theoretical efficiencies. © 2010.
System Identification of a Vortex Lattice Aerodynamic Model
Juang, Jer-Nan; Kholodar, Denis; Dowell, Earl H.
2001-01-01
The state-space presentation of an aerodynamic vortex model is considered from a classical and system identification perspective. Using an aerodynamic vortex model as a numerical simulator of a wing tunnel experiment, both full state and limited state data or measurements are considered. Two possible approaches for system identification are presented and modal controllability and observability are also considered. The theory then is applied to the system identification of a flow over an aerodynamic delta wing and typical results are presented.
Noether-type theorem for discrete nonconservative dynamical systems with nonregular lattices
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
We investigate Noether symmetries and conservation laws of the discrete nonconserved systems with nonregular lattices. The operators of discrete transformation and discrete differentiation to the right and left are introduced for the systems. Based on the invariance of discrete Hamilton action on nonregular lattices of the systems with the nonconserved forces under the infinitesimal transformations with respect to the time and generalized coordinates, we give the discrete analog of generalized variational formula. From this formula we derive the discrete analog of generalized Noether-type identity, and then we present the generalized quasi-extremal equations and properties of these equations for the systems. We also obtain the discrete analog of Noether-type conserved laws and the discrete analog of generalized Noether theorems for the systems. We discuss an example to illustrate these results.
Noether-type theory for discrete mechanico-electrical dynamical systems with nonregular lattices
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
We investigate Noether symmetries and conservation laws of the discrete mechanico-electrical systems with nonregular lattices.The operators of discrete transformation and discrete differentiation to the right and left are introduced for the systems.Based on the invariance of discrete Hamilton action on nonregular lattices of the systems with the dissipation forces under the infinitesimal transformations with respect to the time,generalized coordinates and generalized charge quantities,we work out the discrete analog of the generalized variational formula.From this formula we derive the discrete analog of generalized Noether-type identity,and then we present the generalized quasi-extremal equations and properties of these equations for the systems.We also obtain the discrete analog of Noether-type conserved laws and the discrete analog of generalized Noether theorems for the systems.Finally we use an example to illustrate these results.
Xu, Cenke
Several examples of quantum spin systems and pseudo spin systems have been studied, and unconventional states of matters and phase transitions have been realized in all these systems under consideration. In the p +/- ip superconductor Josephson lattice and the p--band cold atomic system trapped in optical lattices, novel phases which behave similarly to 1+1 dimensional systems are realized, despite the fact that the real physical systems are in two or three dimensional spaces. For instance, by employing a spin-wave analysis together with a new duality transformation, we establish the existence and stability of a novel gapless "critical phase", which we refer to as a "bond algebraic liquid". This novel critical phase is analogous to the 1+1 dimensional algebraic boson liquid phase. The reason for the novel physics is that there is a quasilocal gauge symmetry in the effective low energy Hamiltonian. In a spin-1 system on the kagome lattice, and a hard-core boson system on the honeycomb lattice, the low energy physics is controlled by two components of compact U(1) gauge symmetries that emerge at low energy. Making use of the confinement nature of the 2+1 dimensional compact gauge theories and the powerful duality between gauge theories and height field theories, the crystalline phase diagrams are studied for both systems, and the transitions to other phases are also considered. These phase diagrams might be accessible in strongly correlated materials, or atomic systems in optical lattices. A novel quantum ground state of matter is realized in a bosonic model on three dimensional fcc lattice with emergent low energy excitations. The novel phase obtained is a stable gapless boson liquid phase, with algebraic boson density correlations. The stability of this phase is protected against the instanton effect and superfluidity by self-duality and large gauge symmetries on both sides of the duality. The gapless collective excitations of this phase closely resemble the
Sober Topological Molecular Lattices
Institute of Scientific and Technical Information of China (English)
张德学; 李永明
2003-01-01
A topological molecular lattice (TML) is a pair (L, T), where L is a completely distributive lattice and r is a subframe of L. There is an obvious forgetful functor from the category TML of TML's to the category Loc of locales. In this note,it is showed that this forgetful functor has a right adjoint. Then, by this adjunction,a special kind of topological molecular lattices called sober topological molecular lattices is introduced and investigated.
Fahrenberger, Florian
2013-01-01
The local approach to computing electrostatic interactions proposed by Maggs and adapted by Pasichnyk for molecular dynamics simulations is extended to situations where the dielectric background medium is inhomogeneous. We furthermore correct a problem of the original algorithm related to the correct treatment of the global dipole moment, provide an error estimate for the accuracy of the algorithm, and suggest a different form of the treatment of the self-energy problem. Our implementation is highly scalable on many cores, and we have validated and compared its performance against theoretical predictions and simulation data obtained by other algorithmic approaches.
Kim, Wookrae; Kim, Jung-Ryul; Lee, Yea-Lee; Ihm, Jisoon; An, Kyungwon
2010-01-01
Supplementary information is presented on the recent work by W. Kim et al. on the matter-wave-tunneling-induced broadening in the near-resonant spectra of a single rubidium atom localized in a three-dimensional optical lattice in a strong Lamb-Dicke regime.
Spin Relaxation in Kondo Lattice Systems with Anisotropic Kondo Interaction
Belov, S. I.; Kutuzov, A. S.
2016-12-01
We study the influence of the Kondo effect on the spin relaxation in systems with anisotropic Kondo interaction at temperatures both high and low as compared with the static magnetic field. In the absence of the Kondo effect, the electron spin resonance linewidth is not narrowed in the whole temperature range due to the high anisotropy of the Kondo interaction. The Kondo effect leads to the universal energy scale, which regulates the temperature and magnetic field dependence of different kinetic coefficients and results in a mutual cancelation of their singular parts in a collective spin mode.
Enhanced local lattice distortions with the antiferromagnetic transition in the multiferroic LuMnO3
Louca, Despina; Proffen, Thomas; Lee, Seung-Hun; Cheong, Sang-Wook
2009-03-01
The ferroelectric hexagonal manganite, LuMnO3, has been investigated via neutron scattering and the pair density function analysis to determine the nature of the local atomic distortions with the antiferromagnetic transition, TN, of the Mn ions. While in previously reported neutron diffraction data, it was shown that all atomic coordinates changed based on symmetry considerations with TN, we hereby show that it is the ferroelectric motion of the Lu ions coupled with O distortions that exhibits a strong temperature dependence below TN as reflected in the Lu-O bonds. This suggests an enhancement of the net electric polarization below TN. At the same time, the motion of the apical O1 and O2 ions distorts the MnO5 bipyramids, leading to more buckling of the ab-layers. However, the Mn ions do not appear to distort significantly away from their equilibrium position. The oxygen distortions induced with the spin reorientations below TN may be the cause for the Lu ion displacements through electrostatic interactions and this in turn produces coupling to the electric dipole moments.
Fluctuations in an ordered c (2×2) two-dimensional lattice-gas system with repulsive interactions
Argyrakis, P.; Chumak, A. A.; Maragakis, M.
2005-06-01
Fluctuations of the particle density in an ordered c(2×2) two-dimensional lattice-gas system are studied both analytically and by means of Monte Carlo simulations. The ordering is caused by a strong interparticle repulsive interaction resulting in the second order phase transition. The lattice of adsorption sites is divided into two sublattices (almost filled and almost empty sublattices) each of which contains a small number of structural “defects,” i.e., vacancies and excess particles. The relaxation of the correlation function of fluctuations turns out to be governed by two different functions. This peculiarity is to be contrasted with the traditional fluctuation theory which predicts the existence of a single damping constant, determined by the collective diffusion coefficient. A specific thesis of the proposed approach is that transport phenomena in ordered systems may be described in terms of both displacements and generation-recombination of structural defects. Accordingly, the correlation function of fluctuations depends on diffusion coefficients of two defect species as well as on the generation-recombination frequency. Our theory reduces to the usual one when fluctuations occur under local equilibrium conditions, i.e., for a sufficiently large size of probe areas and not too great values of interaction parameter. The analytical results agree well with those obtained in the Monte Carlo framework.
Integrable Nonlinear Schrödinger System on a Triangular-Lattice Ribbon
Vakhnenko, Oleksiy O.
2015-01-01
An integrable nonlinear Schrödinger system on a triangular-lattice ribbon, whose geometric configuration is similar to that of (1,1) armchair boron nanotube, is studied in detail. The system Hamiltonian formulation is shown to underline an essentially nontrivial Poisson structure associated with four basic field variables appearing as nearly amplitudes of the probability to find the lattice sites being excited and with two concomitant field variables maintaining the finite background. The coupling parameters of the system are allowed to be complex-valued ones thus permitting to model external magnetic fluxes threading the elementary plackets of a lattice in terms of Peierls phases. An alternative version of zero-curvature representation given in terms of 2 × 2 auxiliary spectral and evolution matrices is proved to support the constructive integrability of the system by means of Darboux-Bäcklund dressing method. In the framework of Darboux approach the one-soliton solution is found explicitly and analyzed with special attention to the principal differences between the bare and physical soliton parameters.
Universal threshold for the dynamical behavior of lattice systems with long-range interactions.
Bachelard, Romain; Kastner, Michael
2013-04-26
Dynamical properties of lattice systems with long-range pair interactions, decaying like 1/r(α) with the distance r, are investigated, in particular the time scales governing the relaxation to equilibrium. Upon varying the interaction range α, we find evidence for the existence of a threshold at α=d/2, dependent on the spatial dimension d, at which the relaxation behavior changes qualitatively and the corresponding scaling exponents switch to a different regime. Based on analytical as well as numerical observations in systems of vastly differing nature, ranging from quantum to classical, from ferromagnetic to antiferromagnetic, and including a variety of lattice structures, we conjecture this threshold and some of its characteristic properties to be universal.
Energy Technology Data Exchange (ETDEWEB)
Li, Chao-Ying; Liu, Shi-Fei; Fu, Jin-Xian [Shangrao Normal University, Jiangxi (China). School of Physics and Electronic Information
2016-07-01
The electron paramagnetic resonance (EPR) parameters [i.e. g factors g{sub i} (i=x, y, z) and hyperfine structure constants A{sub i}] and the local lattice structure for the Cu{sup 2+} centre in Tl{sub 2}Zn(SO{sub 4}){sub 2}.6H{sub 2}O (TZSH) crystal were theoretically investigated by utilising the perturbation formulae of these parameters for a 3d{sup 9} ion under rhombically elongated octahedra. In the calculations, the admixture of d orbitals in the ground state and the ligand orbital and spin-orbit coupling interactions are taken into account based on the cluster approach. The theoretical EPR parameters show good agreement with the observed values, and the Cu{sup 2+}-H{sub 2}O bond lengths are obtained as follows: R{sub x}∼1.98 Aa, R{sub y}∼2.09 Aa, R{sub z}∼2.32 Aa. The results are discussed.
On the lattice dynamics of metallic hydrogen and other Coulomb systems
Beck, H.; Straus, D.
1975-01-01
Numerical results for the phonon spectra of metallic hydrogen and other Coulomb systems in cubic lattices are presented. In second order in the electron-ion interaction, the behavior of the dielectric function of the interacting electron gas for arguments around the seond Fermi harmonic leads to drastic Kohn anomalies and even to imaginary phonon frequencies. Third-order band-structure corrections are also calculated. Properties of self-consistent phonons and the validity of the adiabatic approximation are discussed.
Yoshida, Hiroaki; Kinjo, Tomoyuki; Washizu, Hitoshi
2014-10-01
We present a coupled lattice Boltzmann method (LBM) to solve a set of model equations for electrokinetic flows in micro-/nano-channels. The model consists of the Poisson equation for the electrical potential, the Nernst-Planck equation for the ion concentration, and the Navier-Stokes equation for the flows of the electrolyte solution. In the proposed LBM, the electrochemical migration and the convection of the electrolyte solution contributing to the ion flux are incorporated into the collision operator, which maintains the locality of the algorithm inherent to the original LBM. Furthermore, the Neumann-type boundary condition at the solid/liquid interface is then correctly imposed. In order to validate the present LBM, we consider an electro-osmotic flow in a slit between two charged infinite parallel plates, and the results of LBM computation are compared to the analytical solutions. Good agreement is obtained in the parameter range considered herein, including the case in which the nonlinearity of the Poisson equation due to the large potential variation manifests itself. We also apply the method to a two-dimensional problem of a finite-length microchannel with an entry and an exit. The steady state, as well as the transient behavior, of the electro-osmotic flow induced in the microchannel is investigated. It is shown that, although no external pressure difference is imposed, the presence of the entry and exit results in the occurrence of the local pressure gradient that causes a flow resistance reducing the magnitude of the electro-osmotic flow.
Ye, Jian
In Part I, we first study an iso-spectral deformation of general matrix which is a natural generalization of the nonperiodic Toda lattice equation. This deformation is equivalent to the Cholesky flow. We prove the integrability of the deformation, and give an explicit formula for the solution to the initial value problem. The formula is obtained by generalizing the orthogonalization procedure of Szego. Using the formula, the solution to the LU factorization can be constructed explicitly. Based on the root spaces for simple Lie algebras, we consider several reductions of the equation. This leads to generalized Toda equations related to other classical semi-simple Lie algebra which include the integrable systems studied by Bogoyavlensky and Kostant. We show these systems can be solved explicitly in a unified way. Based on the explicit solutions, we then consider the iso-spectral real manifolds of tridiagonal Hessenberg matrices with distinct real eigenvalues. The manifolds are described by the iso-spectral flows of indefinite Toda lattice equations introduced by Kodama and Ye. These Toda lattices consist of 2N-1 different systems with hamiltonians H = [[1]/over[2
Localization in physical systems described by discrete nonlinear Schrodinger-type equations.
Bishop, A R; Kalosakas, G; Rasmussen, K O; Kevrekidis, P G
2003-06-01
Following a short introduction on localized modes in a model system, namely the discrete nonlinear Schrodinger equation, we present explicit results pertaining to three different physical systems described by similar equations. The applications range from the Raman scattering spectra of a complex electronic material through intrinsic localized vibrational modes, to the manifestation of an abrupt and irreversible delocalizing transition of Bose-Einstein condensates trapped in two-dimensional optical lattices, and to the instabilities of localized modes in coupled arrays of optical waveguides.
Local equations of state in nonequilibrium heterogeneous physicochemical systems
Tovbin, Yu. K.
2017-03-01
Equations describing local thermal and caloric equations of state in heterogeneous systems at any degree of their states' deviation from equilibrium are derived. The state of a system is described by equations of the transfer of mixture components; these generalize the equations of classical non-equilibrium thermodynamics for strongly nonequilibrium processes. The contributions from reactions and external fields are taken into account. The equations are derived using the lattice gas model with discrete molecular distributions in space (on a scale comparable to molecular dimensions) and continuous molecular distributions (at short distances inside cells) during their translational and vibrational motions. For simplicity, it is assumed that distinctions between the sizes of mixture components are small. Contributions from potential functions of intermolecular interaction (of the Lennard-Jones type) to some coordination spheres are considered. The theory provides a unified description of the dynamics of distributions of concentrations and pair functions of mixture components in three aggregate states, and at their interfaces. Universal expressions for the local components of the pressure tensor and internal energy inside multicomponent bulk phases and at their interfaces are obtained. Local components of the pressure tensor and the internal energy are universally expressed through local unary and pair distribution functions (DFs) in any nonequilibrium state. The time evolution of the unary and pair DFs themselves is determined from the derived system of equations of mass, momentum, and energy transfer that ensure the transition of the system from a strongly nonequilibrium state to both the local equilibrium state described within traditional nonequilibrium thermodynamics and the complete thermodynamic equilibrium state postulated by classical thermodynamics.
Entropy-driven phase transition in a system of long rods on a square lattice
Linares, D. H.; Roma, F.; Ramirez-Pastor, A. J.
2007-01-01
The isotropic-nematic (I-N) phase transition in a system of long straight rigid rods of length k on square lattices is studied by combining Monte Carlo simulations and theoretical analysis. The process is analyzed by comparing the configurational entropy of the system with the corresponding to a fully aligned system, whose calculation reduces to the 1D case. The results obtained (1) allow to estimate the minimum value of k which leads to the formation of a nematic phase and provide an interes...
High Statistics Analysis using Anisotropic Clover Lattices: (II) Three-Baryon Systems
2009-01-01
We present the results of an exploratory Lattice QCD calculation of three-baryon systems through a high-statistics study of one ensemble of anisotropic clover gauge-field configurations with a pion mass of m_\\pi ~ 390 MeV. Because of the computational cost of the necessary contractions, we focus on correlation functions generated by interpolating-operators with the quantum numbers of the $\\Xi^0\\Xi^0 n$ system, one of the least demanding three baryon systems in terms of the number of contracti...
Critical slowing down of the Gaussian spin system on diamond—type hierarchical lattices
Institute of Scientific and Technical Information of China (English)
朱建阳; 朱涵
2003-01-01
Based on the single-spin transition critical dynamics,we have investigated the critical slowing down of the Gaussian spin model situated on the fractal family of diamond-type hierarchical lattices.We calculate the dynamical critical exponent z and the correlation-length critical exponent v using the dynamical decimation renormalization-group technique.The result,together with some earlier ones,suggests us to conclude that on a wide range of geometries,zv=1 is the general relationship,while the two exponents depend on the specific structure,However,we have investigated for various lattices in an earlier paper,the system studied in this paper shows highly universal z=1/v=2 independent of the structure and the dimensionality.
Critical slowing down of the Gaussian spin system on diamond-type hierarchical lattices
Institute of Scientific and Technical Information of China (English)
朱建阳; 朱涵
2003-01-01
Based on the single-spin transition critical dynamics, we have investigated the critical slowing down of the Gaussian spin model situated on the fractal family of diamond-type hierarchical lattices. We calculate the dynamical critical exponent z and the correlation-length critical exponent v using the dynamical decimation renormalization-group technique. The result, together with some earlier ones, suggests us to conclude that on a wide range of geometries, zv = 1is the general relationship, while the two exponents depend on the specific structure. However, we have investigated for various lattices in an earlier paper, the system studied in this paper shows highly universal z = 1/v = 2 independent of the structure and the dimensionality.
Local food systems: a sustainability review
Kwong, Edwin
2011-01-01
The evolution of global food systems has led to industrial food production processes that have environmental and social external costs. Consumer awareness about sustainability issues brings a heightened awareness of general consumption impacts in our food choices. This paper explores sustainability factors within local food systems in order to understand the impact on sustainability issues within the local food economy. A review of environmental, economic, and social issues within a sustai...
Three-Dimensional Lattice Structure Formed in a Binary System with DNA Nanoparticles
Kawasaki, Keno; Katsuno, Hiroyasu; Sato, Masahide
2017-06-01
Keeping the formation of lattice structures by nanoparticles covered with DNA in mind, we carry out Brownian dynamics simulations and study three-dimensional lattice structures formed by two species of particles. In our previous study [H. Katsuno, Y. Maegawa, and M. Sato, https://doi.org/10.7566/JPSJ.85.074605" xlink:type="simple">J. Phys. Soc. Jpn. 85, 074605 (2016)], we used the Lennard-Jones potential and studied two-dimensional structures formed in a binary system. When the interaction length between the different species, σ', is shorter than that between the same species, σ, the lattice structure changes with the ratio σ'/σ. In this paper, we use the same potential and study the formation of three-dimensional structures. With decreasing ratio σ'/σ, the mixture of the face-centered-cubic (fcc) structure and hexagonal-close-packed (hcp) structure is changed to the body-centered-cubic (bcc) structure and the NaCl structure.
Globalization and localization of Management Control Systems
DEFF Research Database (Denmark)
Toldbod, Thomas; Israelsen, Poul
2014-01-01
have more particular characteristics. Specifically, this study finds that cybernetic controls and administrative controls are designed as global management control systems. Planning controls are glocal systems and reward & compensation controls assume local characteristics. The finding leads......Through an empirical case study this article examines the operation of multiple management control systems as a package in a Danish manufacturing company. The analysis focuses on four different management control systems; cybernetic controls, planning controls, reward controls, and administrative...... controls, through the theoretical lens of globalization, localization, and glocalization. The analysis documents that these different management control systems are affected differently by the processes of globalization and localization, whereby some are universal throughout the organization and others...
Lower bounds for the ground-state degeneracies of frustrated systems on fractal lattices
Curado; Nobre
2000-12-01
The total number of ground states for nearest-neighbor-interaction Ising systems with frustrations, defined on hierarchical lattices, is investigated. A simple method is presented, which allows one to factorize the ground-state degeneracy, at a given hierarchy level n, in terms of contributions due to all hierarchy levels. Such a method may yield the exact ground-state degeneracy of uniformly frustrated systems, whereas it works as an approximation for randomly frustrated models. In the latter cases, it is demonstrated that such an approximation yields lower-bound estimates for the ground-state degeneracies.
Many-body position operator in lattice fermionic systems with periodic boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Hetenyi, Balazs [Institut fuer Theoretische Physik, Technische Universitaet Graz, Petersgasse 16, A-8010 Graz (Austria); Mathematisches Institut, Fakultaet fuer Mathematik, Informatik und Statistik, Ludwig Maximilians Universitaet, Theresienstrasse 39, Muenchen 80333 (Germany)], E-mail: hetenyi@itp.tugraz.at
2009-10-16
A total position operator X in the position representation is derived for lattice fermionic systems with periodic boundary conditions. The operator is shown to be Hermitian, the generator of translations in momentum space, and its time derivative is shown to correspond to the total current operator in a periodic system. The operator is such that its moments can be calculated up to any order. To demonstrate its utility finite size scaling is applied to the Brinkman-Rice transition as well as to metallic and insulating Gutzwiller wavefunctions. (fast track communication)
Non-equilibrium Phenomenon between Electron and Lattice Systems Induced by the Peltier Effect
Iwasaki, Hideo; Hori, Hidenobu; Sasaki, Shosuke
2005-08-01
Temperature distributions of the electron and lattice systems induced by the Peltier effect have been precisely measured by improved Harman method, where the temperature differences (Δ Tel and Δ Tla) have been independently evaluated for several terminal lengths (LV) in thermoelectric materials (Bi,Sb)2Te3. Both temperature distributions have different behaviors in the stationary state, that is, the LV dependences of Δ Tel and Δ Tla show positive and negative curvatures, respectively. It is also indicated that the temperature difference has a linear relation to LV in the whole system and the observed non-equilibrium phenomenon is consistent with a law of the conservation of heat quantity.
Quasi-Monte Carlo methods for lattice systems: a first look
Jansen, K; Nube, A; Griewank, A; Müller-Preussker, M
2013-01-01
We investigate the applicability of Quasi-Monte Carlo methods to Euclidean lattice systems for quantum mechanics in order to improve the asymptotic error behavior of observables for such theories. In most cases the error of an observable calculated by averaging over random observations generated from an ordinary Markov chain Monte Carlo simulation behaves like 1/Sqrt(N), where N is the number of observations. By means of Quasi-Monte Carlo methods it is possible to improve this behavior for certain problems up to 1/N. We adapted and applied this approach to simple systems like the quantum harmonic and anharmonic oscillator and verified an improved error scaling.
Richoux, Olivier; Hardy, Jean
2009-01-01
This paper presents an application of time-frequency methods to characterize the dispersion of acoustic waves travelling in a one-dimensional periodic or disordered lattice made up of Helmholtz resonators connected to a cylindrical tube. These methods allow (1) to evaluate the velocity of the wave energy when the input signal is an acoustic pulse ; (2) to display the evolution of the spectral content of the transient signal ; (3) to show the role of the localized nonlinearities on the propagation .i.e the emergence of higher harmonics. The main result of this paper is that the time-frequency methods point out how the nonlinearities break the localization of the waves and/or the filter effects of the lattice.
Solitons in nonlinear lattices
Kartashov, Yaroslav V; Torner, Lluis
2010-01-01
This article offers a comprehensive survey of results obtained for solitons and complex nonlinear wave patterns supported by purely nonlinear lattices (NLs), which represent a spatially periodic modulation of the local strength and sign of the nonlinearity, and their combinations with linear lattices. A majority of the results obtained, thus far, in this field and reviewed in this article are theoretical. Nevertheless, relevant experimental settings are surveyed too, with emphasis on perspectives for implementation of the theoretical predictions in the experiment. Physical systems discussed in the review belong to the realms of nonlinear optics (including artificial optical media, such as photonic crystals, and plasmonics) and Bose-Einstein condensation (BEC). The solitons are considered in one, two, and three dimensions (1D, 2D, and 3D). Basic properties of the solitons presented in the review are their existence, stability, and mobility. Although the field is still far from completion, general conclusions c...
Environmentally-adapted local energy systems
Energy Technology Data Exchange (ETDEWEB)
Moe, N.; Oefverholm, E. [NUTEK, Stockholm (Sweden); Andersson, Owe [EKAN Gruppen (Sweden); Froste, H. [Swedish Environmental Protection Agency, Stockholm (Sweden)
1997-10-01
Energy companies, municipalities, property companies, firms of consultants, environmental groups and individuals are examples of players working locally to shape environmentally adapted energy systems. These players have needed information making them better able to make decisions on cost-efficient, environmentally-adapted energy systems. This book answers many of the questions they have put. The volume is mainly based on Swedish handbooks produced by the Swedish National Board for Industrial and Technical Development, NUTEK, together with the Swedish Environmental Protection Agency. These handbooks have been used in conjunction with municipal energy planning, local Agenda 21 work, to provide a basis for deciding on concrete local energy systems. The contents in brief: -The book throws new light on the concept of energy efficiency; -A section on the environment compares how air-polluting emissions vary with different methods of energy production; -A section contains more than 40 ideas for measures which can be profitable, reduce energy consumption and the impact on the environment all at the same time; -The book gives concrete examples of new, alternative and environmentally-adapted local energy systems. More efficient use of energy is included as a possible change of energy system; -The greatest emphasis is laid upon alternative energy systems for heating. It may be heating in a house, block of flats, office building or school; -Finally, there are examples of environmentally-adapted local energy planning.
Advanced design of local ventilation systems
Energy Technology Data Exchange (ETDEWEB)
Kulmala, I. [VTT Manufacturing Technology, Espoo (Finland). Safety Technology
1997-12-31
Local ventilation is widely used in industry for controlling airborne contaminants. However, the present design practices of local ventilation systems are mainly based on empirical equations and do not take quantitatively into account the various factors affecting the performance of these systems. The aim of this study was to determine the applicability and limitations of more advanced fluid mechanical methods to the design and development of local ventilation systems. The most important factors affecting the performance of local ventilation systems were determined and their effect was studied in a systematic manner. The numerical calculations were made with the FLUENT computer code and they were verified by laboratory experiments, previous measurements or analytical solutions. The results proved that the numerical calculations can provide a realistic simulation of exhaust openings, effects of ambient air flows and wake regions. The experiences with the low-velocity local supply air showed that these systems can also be modelled fairly well. The results were used to improve the efficiency and thermal comfort of a local ventilation unit and to increase the effective control range of exhaust hoods. In the simulation of the interaction of a hot buoyant source and local exhaust, the predicted capture efficiencies were clearly higher than those observed experimentally. The deviations between measurements and non-isothermal flow calculations may have partly been caused by the inability to achieve grid independent solutions. CFD simulations is an advanced and flexible tool for designing and developing local ventilation. The simulations can provide insight into the time-averaged flow field which may assist us in understanding the observed phenomena and to explain experimental results. However, for successful calculations the applicability and limitations of the models must be known. (orig.) 78 refs.
New real-space renormalization-group calculation for the critical properties of lattice spin systems
Hecht, Charles E.; Kikuchi, Ryoichi
1982-05-01
In evaluating the critical properties of lattice spin systems in the real-space renormalization-group theory we use the cluster variation method. A configuration in the transformed system is constrained and the probability of occurrence of this configuration is calculated both in the transformed system and in the original system. By equating the two probabilities and forming ratios of two such equalities (for two or more constrained configurations) the fixed point of the renormalization transformation is evaluated. The method can avoid the trouble due to different singularities in the original and transformed systems, and hence can obviate the possible development of spurious singularities in the transformation at low temperatures. The two-dimensional triangular Ising model is treated with numerical results comparable with those obtained by the cluster treatment of Niemeijer and van Leeuwen who used more and larger cluster types than those we introduce.
Ultracold atoms in optical lattices simulating quantum many-body systems
Lewenstein, Maciej; Ahufinger, Verònica
2012-01-01
Quantum computers, though not yet available on the market, will revolutionize the future of information processing. Quantum computers for special purposes like quantum simulators are already within reach. The physics of ultracold atoms, ions and molecules offer unprecedented possibilities of control of quantum many body systems and novel possibilities of applications to quantum information processing and quantum metrology. Particularly fascinating is the possibility of usingultracold atoms in lattices to simulate condensed matter or even high energy physics.This book provides a complete and co
Energy Technology Data Exchange (ETDEWEB)
Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2015-05-03
I describe a generic formulation for the evolution of emittances and lattice functions under arbitrary, possibly non-Hamiltonian, linear equations of motion. The average effect of stochastic processes, which would include ionization interactions and synchrotron radiation, is also included. I first compute the evolution of the covariance matrix, then the evolution of emittances and lattice functions from that. I examine the particular case of a cylindrically symmetric system, which is of particular interest for ionization cooling.
Stability of mutualisms in a lattice gas system of two species
Directory of Open Access Journals (Sweden)
Yuanshi Wang
2015-01-01
Full Text Available This article considers mutualisms in a lattice gas system of two species. The species are mutualistic since each one can provide resources to the other. They are also competitive since they compete for empty sites on the same lattice. The mutualisms are assumed to have a saturated response, and the intraspecific competition is considered because of self-limitation. The mutualism system is characterized by differential equations, which are derived from reactions on lattice and are extension of a previous model. Global stability analysis demonstrates that (i When neither species can survive alone, they can coexist if mutualisms between them are strong and population densities are large, which exhibits the Allee effect in obligate mutualism; (ii When one species can survive alone but the other cannot, the latter one will survive if the mutualistic effect from the former is strong. Even if the effect is intermediate, the latter species can survive by strengthening its mutualistic effect on the former and enhancing its population density; (iii When either species can survive alone, a weak mutualism will lead to extinction of one species. When in coexistence, intermediate strength of mutualism is shown to be beneficial under certain parameter range, while over- or under- mutualism is not good. Furthermore, extremely strong/weak mutualism is exhibited to result in extinction of one/both species. While seven typical dynamics are displayed by numerical simulation in a previous work, they are proved in this work and the eighth one is exhibited. Numerical simul ations validate and extend our conclusions.
Lattice Boltzmann simulation for the energy and entropy of excitable systems
Institute of Scientific and Technical Information of China (English)
Deng Min-Yi; Tang Guo-Ning; Kong Ling-Jiang; Liu Mu-Ren
2011-01-01
The internal energy and the spatiotemporal entropy of excitable systems are investigated with the lattice Boltzmann method. The numerical results show that the breakup of spiral wave is attributed to the inadequate supply of energy, i.e., the internal energy of system is smaller than the energy of self-sustained spiral wave. It is observed that the average internal energy of a regular wave state reduces with its spatiotemporal entropy decreasing. Interestingly, although the energy difference between two regular wave states is very small, the different states can be distinguished obviously due to the large difference between their spatiotemporal entropies. In addition, when the unstable spiral wave converts into the spatiotemporal chaos, the internal energy of system decreases, while the spatiotemporal entropy increases, which behaves as the thermodynamic entropy in an isolated system.
Dielectric-barrier discharges in two-dimensional lattice potentials
Sinclair, Josiah
2011-01-01
We use a pin-grid electrode to introduce a corrugated electrical potential into a planar dielectric-barrier discharge (DBD) system, so that the amplitude of the applied electric field has the profile of a two-dimensional square lattice. The lattice potential provides a template for the spatial distribution of plasma filaments in the system and has pronounced effects on the patterns that can form. The positions at which filaments become localized within the lattice unit cell vary with the width of the discharge gap. The patterns that appear when filaments either overfill or under-fill the lattice are reminiscent of those observed in other physical systems involving 2d lattices. We suggest that the connection between lattice-driven DBDs and other areas of physics may benefit from the further development of models that treat plasma filaments as interacting particles.
High Statistics Analysis using Anisotropic Clover Lattices: (II) Three-Baryon Systems
Energy Technology Data Exchange (ETDEWEB)
Beane, S; Detmold, W; Luu, T; Orginos, K; Parreno, A; Savage, M; Torok, A; Walker-Loud, A
2009-05-05
We present the results of an exploratory Lattice QCD calculation of three-baryon systems through a high-statistics study of one ensemble of anisotropic clover gauge-field configurations with a pion mass of m{sub {pi}} {approx} 390 MeV. Because of the computational cost of the necessary contractions, we focus on correlation functions generated by interpolating-operators with the quantum numbers of the {Xi}{sup 0}{Xi}{sup 0}n system, one of the least demanding three baryon systems in terms of the number of contractions. We find that the ground state of this system has an energy of E{sub {Xi}{sup 0}{Xi}{sup 0}n} = 3877.9 {+-} 6.9 {+-} 9.2 {+-} 3.3 MeV corresponding to an energy-shift due to interactions of {delta}E{sub {Xi}{sup 0}{Xi}{sup 0}n} = E{sub {Xi}{sup 0}{Xi}{sup 0}n} - 2M{sub {Xi}{sup 0}} - M{sub n} = 4.6 {+-} 5.0 {+-} 7.9 {+-} 4.2 MeV. There are a significant number of time-slices in the three-baryon correlation function for which the signal-to-noise ratio is only slowly degrading with time. This is in contrast to the exponential degradation of the signal-to-noise ratio that is observed at larger times, and is due to the suppressed overlap of the source and sink interpolating-operators that are associated with the variance of the three-baryon correlation function onto the lightest eigenstates in the lattice volume (mesonic systems). As one of the motivations for this area of exploration is the calculation of the structure and reactions of light nuclei, we also present initial results for a system with the quantum numbers of the triton (pnn). This present work establishes a path to multi-baryon systems, and shows that Lattice QCD calculations of the properties and interactions of systems containing four and five baryons are now within sight.
High Statistics Analysis using Anisotropic Clover Lattices: (II) Three-Baryon Systems
Energy Technology Data Exchange (ETDEWEB)
Andre Walker-Loud, Will Detmold, William Detmold, Aaron Torok, Konstantinos Orginos, Silas Beane, Tom Luu, Martin Savage, Assumpta Parreno
2009-10-01
We present the results of an exploratory Lattice QCD calculation of three-baryon systems through a high-statistics study of one ensemble of anisotropic clover gauge-field configurations with a pion mass of m_\\pi ~ 390 MeV. Because of the computational cost of the necessary contractions, we focus on correlation functions generated by interpolating-operators with the quantum numbers of the $\\Xi^0\\Xi^0 n$ system, one of the least demanding three baryon systems in terms of the number of contractions. We find that the ground state of this system has an energy of E_{\\Xi^0\\Xi^0n}= 3877.9\\pm 6.9\\pm 9.2\\pm3.3 MeV corresponding to an energy-shift due to interactions of \\delta E_{\\Xi^0\\Xi^0n}=E_{\\Xi^0\\Xi^0n}-2M_{\\Xi^0} -M_n=4.6\\pm 5.0\\pm 7.9\\pm 4.2 MeV. There are a significant number of time-slices in the three-baryon correlation function for which the signal-to-noise ratio is only slowly degrading with time. This is in contrast to the exponential degradation of the signal-to-noise ratio that is observed at larger times, and is due to the suppressed overlap of the source and sink interpolating-operators that are associated with the variance of the three-baryon correlation function onto the lightest eigenstates in the lattice volume (mesonic systems). As one of the motivations for this area of exploration is the calculation of the structure and reactions of light nuclei, we also present initial results for a system with the quantum numbers of the triton (pnn). This present work establishes a path to multi-baryon systems, and shows that Lattice QCD calculations of the properties and interactions of systems containing four and five baryons are now within sight.
Magnetic phase transition in coupled spin-lattice systems: A replica-exchange Wang-Landau study.
Perera, Dilina; Vogel, Thomas; Landau, David P
2016-10-01
Coupled, dynamical spin-lattice models provide a unique test ground for simulations investigating the finite-temperature magnetic properties of materials under the direct influence of the lattice vibrations. These models are constructed by combining a coordinate-dependent interatomic potential with a Heisenberg-like spin Hamiltonian, facilitating the treatment of both the atomic coordinates and the spins as explicit phase variables. Using a model parameterized for bcc iron, we study the magnetic phase transition in these complex systems via the recently introduced, massively parallel replica-exchange Wang-Landau Monte Carlo method. Comparison with the results obtained from rigid lattice (spin-only) simulations shows that the transition temperature as well as the amplitude of the peak in the specific heat curve is marginally affected by the lattice vibrations. Moreover, the results were found to be sensitive to the particular choice of interatomic potential.
Magnetic phase transition in coupled spin-lattice systems: A replica-exchange Wang-Landau study
Perera, Dilina; Vogel, Thomas; Landau, David P.
2016-10-01
Coupled, dynamical spin-lattice models provide a unique test ground for simulations investigating the finite-temperature magnetic properties of materials under the direct influence of the lattice vibrations. These models are constructed by combining a coordinate-dependent interatomic potential with a Heisenberg-like spin Hamiltonian, facilitating the treatment of both the atomic coordinates and the spins as explicit phase variables. Using a model parameterized for bcc iron, we study the magnetic phase transition in these complex systems via the recently introduced, massively parallel replica-exchange Wang-Landau Monte Carlo method. Comparison with the results obtained from rigid lattice (spin-only) simulations shows that the transition temperature as well as the amplitude of the peak in the specific heat curve is marginally affected by the lattice vibrations. Moreover, the results were found to be sensitive to the particular choice of interatomic potential.
SYSTEMIC TOXIC REACTIONS TO LOCAL ANESTHETICS
Moore, Daniel C.; Green, John
1956-01-01
The topical use of anesthetic agents involves an element of risk. Systemic toxic reactions are rare, but they do occur and may result in death. When a reaction occurs from a topical application, it usually progresses rapidly to respiratory and cardiovascular collapse, and thus therapy must be instituted with more haste to avoid deaths. Fatal systemic toxic reactions from topically administered anesthetic drugs are, in effect, usually not due to well informed use of the drug but to misuse owing to less than complete understanding of absorption. Emphasis is placed on the causes, prophylaxis and treatment of severe systemic toxic reactions which follow the topical application of local anesthetic drugs. If systemic toxic reactions resulting from a safe dose of a local anesthetic agent are correctly treated, there will usually follow an uneventful recovery rather than a catastrophe. PMID:13343009
Energy Technology Data Exchange (ETDEWEB)
Shindler, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2007-07-15
I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the effects of these discretization errors on the phase structure for Wilson-like fermions in the chiral limit. The possibility to use in lattice simulations different lattice actions for sea and valence quarks to ease the renormalization patterns of phenomenologically relevant local operators, is also discussed. (orig.)
Wei, Hua-Liang; Billings, Stephen A; Zhao, Yifan; Guo, Lingzhong
2009-01-01
In this brief, by combining an efficient wavelet representation with a coupled map lattice model, a new family of adaptive wavelet neural networks, called lattice dynamical wavelet neural networks (LDWNNs), is introduced for spatio-temporal system identification. A new orthogonal projection pursuit (OPP) method, coupled with a particle swarm optimization (PSO) algorithm, is proposed for augmenting the proposed network. A novel two-stage hybrid training scheme is developed for constructing a parsimonious network model. In the first stage, by applying the OPP algorithm, significant wavelet neurons are adaptively and successively recruited into the network, where adjustable parameters of the associated wavelet neurons are optimized using a particle swarm optimizer. The resultant network model, obtained in the first stage, however, may be redundant. In the second stage, an orthogonal least squares algorithm is then applied to refine and improve the initially trained network by removing redundant wavelet neurons from the network. An example for a real spatio-temporal system identification problem is presented to demonstrate the performance of the proposed new modeling framework.
Directory of Open Access Journals (Sweden)
Yamin Wang
2014-01-01
Full Text Available This paper is concerned with the random attractors for a class of second-order stochastic lattice dynamical systems. We first prove the uniqueness and existence of the solutions of second-order stochastic lattice dynamical systems in the space F=lλ2×l2. Then, by proving the asymptotic compactness of the random dynamical systems, we establish the existence of the global random attractor. The system under consideration is quite general, and many existing results can be regarded as the special case of our results.
Institute of Scientific and Technical Information of China (English)
FANG Jian-Ping; FEI Jin-Xi; ZHENG Chun-Long
2006-01-01
In this paper, the extended projective approach, which was recently presented and successfully used in some continuous nonlinear physical systems, is generalized to nonlinear partial differential-difference systems (DDEs).As a concrete example, new families of exact solutions to the (2+1)-dimensional Toda lattice system are obtained by the extended projective approach.
On Locality in Distributed Storage Systems
Rawat, Ankit Singh
2012-01-01
This paper studies the design of codes for distributed storage systems (DSS) that enable local repair in the event of node failure. This paper presents locally repairable codes based on low degree multivariate polynomials. Its code construction mechanism extends work on Noisy Interpolating Set by Dvir et al. \\cite{dvir2011}. The paper presents two classes of codes that allow node repair to be performed by contacting 2 and 3 surviving nodes respectively. It further shows that both classes are good in terms of their rate and minimum distance, and allow their rate to be bartered for greater flexibility in the repair process.
Quasi-Monte Carlo methods for lattice systems. A first look
Energy Technology Data Exchange (ETDEWEB)
Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Leovey, H.; Griewank, A. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Nube, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Mueller-Preussker, M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik
2013-02-15
We investigate the applicability of Quasi-Monte Carlo methods to Euclidean lattice systems for quantum mechanics in order to improve the asymptotic error behavior of observables for such theories. In most cases the error of an observable calculated by averaging over random observations generated from an ordinary Markov chain Monte Carlo simulation behaves like N{sup -1/2}, where N is the number of observations. By means of Quasi-Monte Carlo methods it is possible to improve this behavior for certain problems up to N{sup -1}. We adapted and applied this approach to simple systems like the quantum harmonic and anharmonic oscillator and verified an improved error scaling.
Batrouni, George
2011-03-01
I will discuss pairing in fermionic systems in one- and two-dimensional optical lattices with population imbalance. This will be done in the context of the attractive fermionic Hubbard model using the Stochastic Green Function algorithm in d=1 while for d=2 we use Determinant Quantum Monte Carlo. This is the first exact QMC study examining the effects of finite temperature which is very important in experiments on ultra-cold atoms. Our results show that, in the ground state, the dominant pairing mechanism is at nonzero center of mass momentum, i.e. FFLO. I will then discuss the effect of finite temperature in the uniform and confined systems and present finite temperature phase diagrams. The numerical results will be compared with experiments. With M. J. Wolak (CQT, National University of Singapore) and V. G. Rousseau (Department of Physics and Astronomy, Louisiana State University).
Coarse-grained stochastic processes and Monte Carlo simulations in lattice systems
Katsoulakis, M A; Vlachos, D G
2003-01-01
In this paper we present a new class of coarse-grained stochastic processes and Monte Carlo simulations, derived directly from microscopic lattice systems and describing mesoscopic length scales. As our primary example, we mainly focus on a microscopic spin-flip model for the adsorption and desorption of molecules between a surface adjacent to a gas phase, although a similar analysis carries over to other processes. The new model can capture large scale structures, while retaining microscopic information on intermolecular forces and particle fluctuations. The requirement of detailed balance is utilized as a systematic design principle to guarantee correct noise fluctuations for the coarse-grained model. We carry out a rigorous asymptotic analysis of the new system using techniques from large deviations and present detailed numerical comparisons of coarse-grained and microscopic Monte Carlo simulations. The coarse-grained stochastic algorithms provide large computational savings without increasing programming ...
Spin qubits in antidot lattices
DEFF Research Database (Denmark)
Pedersen, Jesper Goor; Flindt, Christian; Mortensen, Niels Asger;
2008-01-01
and density of states for a periodic potential modulation, referred to as an antidot lattice, and find that localized states appear, when designed defects are introduced in the lattice. Such defect states may form the building blocks for quantum computing in a large antidot lattice, allowing for coherent...
Halliday, I; Lishchuk, S V; Spencer, T J; Pontrelli, G; Evans, P C
2016-08-01
We present a method for applying a class of velocity-dependent forces within a multicomponent lattice Boltzmann equation simulation that is designed to recover continuum regime incompressible hydrodynamics. This method is applied to the problem, in two dimensions, of constraining to uniformity the tangential velocity of a vesicle membrane implemented within a recent multicomponent lattice Boltzmann simulation method, which avoids the use of Lagrangian boundary tracers. The constraint of uniform tangential velocity is carried by an additional contribution to an immersed boundary force, which we derive here from physical arguments. The result of this enhanced immersed boundary force is to apply a physically appropriate boundary condition at the interface between separated lattice fluids, defined as that region over which the phase-field varies most rapidly. Data from this enhanced vesicle boundary method are in agreement with other data obtained using related methods [e.g., T. Krüger, S. Frijters, F. Günther, B. Kaoui, and J. Harting, Eur. Phys. J. 222, 177 (2013)10.1140/epjst/e2013-01834-y] and underscore the importance of a correct vesicle membrane condition.
INDUSTRIAL DISTRICTS AS LOCAL SYSTEMS OF INNOVATION
Giancarlo Cor�; Stefano Micelli
2007-01-01
This essay examines the situation and the lines of development of industrial districts from the point of view of local systems of innovation. First of all, this article points out to the modernity factors of the district model � which are ascribable to the supply chain economy, to entrepreneurial dynamics and to the importance of geography as a competitive resource � through the analysis of recent contributions of economic literature that examined the emerging organizational models in knowled...
HAIM OMLET: An Expert System For Research In Orthomodular Lattices And Related Structures
Dankel, D. D.; Rodriguez, R. V.; Anger, F. D.
1986-03-01
This paper describes research towards the construction of an expert system combining the brute force power of algorithmic computation and the inductive reasoning power of a rule-based inference engine in the mathematical area of discrete structures. Little research has been conducted on extending existing expert systems' technology to computationally complex areas. This research addresses the extension of expert systems into areas such as these, where the process of inference by itself will not produce the proper results. Additionally, the research will demonstrate the benefits of combining inference engines and mathematical algorithms to attack computationally complex problems. The specific aim is to produce an expert system which embodies expert level knowledge of orthomodular lattices, graphs, structure spaces, boolean algebras, incidence relations, and projective configurations. The resulting system, implemented on a micro-computer, will provide researchers a powerful and accessible tool for exploring these discrete structures. The system's "shell" will provide a structure for developing other expert systems with similar capabilities in such related areas as coding theory, categories, monoids, automata theory, and non-standard logics.
Energy Technology Data Exchange (ETDEWEB)
Calamiotou, M., E-mail: mcalam@phys.uoa.gr [Solid State Physics Department, Faculty of Physics, National and Kapodistrian University of Athens, GR-15784 Athens (Greece); Liarokapis, E. [Department of Physics, National Technical University of Athens, GR15780, Athens (Greece)
2017-01-15
Highlights: • A reply to comment by A. Martinelli (PHYSC-D-15-00255) on: “Local lattice distortions vs. structural phase transition in NdFeAsO{sub 1-x}F{sub x}” is presented. • The main conclusions drawn in the commented paper are based on the distinct different temperature evolution for T < 150 K among the superconducting and non-superconducting NdFeAsO{sub 1-x}F{sub x} compounds of both, atomic displacement parameters and Raman mode widths, rather than only on line broadening analysis or the detection of any symmetry breaking in the Raman spectra.
Integrated energy systems and local energy markets
DEFF Research Database (Denmark)
Lund, Henrik; Münster, Ebbe
2006-01-01
Significant benefits are connected with an increase in the flexibility of the Danish energy system. On the one hand, it is possible to benefit from trading electricity with neighbouring countries, and on the other, Denmark will be able to make better use of wind power and other types of renewable...... energy in the future. This paper presents the analysis of different ways of increasing flexibility in the Danish energy system by the use of local regulation mechanisms. This strategy is compared with the opposite extreme, i.e. trying to solve all balancing problems via electricity trade...
Local spacetime effects on gyroscope systems
Wohlfarth, Mattias N R
2012-01-01
We give a precise theoretical description of initially aligned sets of orthogonal gyroscopes which are transported along different paths from some initial point to the same final point in spacetime. These gyroscope systems can be used to synchronize separated observers' spatial frames by free fall along timelike geodesics. We find that initially aligned gyroscope systems, or spatial frames, lose their synchronization due to the curvature of spacetime and their relative motion. On the basis of our results we propose a simple experiment which enables observers to determine locally whether their spacetime is described by a rotating Kerr or a non-rotating Schwarzschild metric.
Local spacetime effects on gyroscope systems
Wohlfarth, Mattias N. R.; Pfeifer, Christian
2013-01-01
We give a precise theoretical description of initially aligned sets of orthogonal gyroscopes which are transported along different paths from some initial point to the same final point in spacetime. These gyroscope systems can be used to synchronize separated observers’ spatial frames by free fall along timelike geodesics. We find that initially aligned gyroscope systems, or spatial frames, lose their synchronization due to the curvature of spacetime and their relative motion. On the basis of our results we propose a simple experiment that enables observers to determine locally whether their spacetime is described by a rotating Kerr or a nonrotating Schwarzschild metric.
Local density approximations from finite systems
Entwistle, Mike; Wetherell, Jack; Longstaff, Bradley; Ramsden, James; Godby, Rex
2016-01-01
The local density approximation (LDA) constructed through quantum Monte Carlo calculations of the homogeneous electron gas (HEG) is the most common approximation to the exchange-correlation functional in density functional theory. We introduce an alternative set of LDAs constructed from slab-like systems of one, two and three electrons that resemble the HEG within a finite region, and illustrate the concept in one dimension. Comparing with the exact densities and Kohn-Sham potentials for various test systems, we find that the LDAs give a good account of the self-interaction correction, but are less reliable when correlation is stronger or currents flow.
Large-scale calculation of ferromagnetic spin systems on the pyrochlore lattice
Soldatov, Konstantin; Nefedev, Konstantin; Komura, Yukihiro; Okabe, Yutaka
2017-02-01
We perform the high-performance computation of the ferromagnetic Ising model on the pyrochlore lattice. We determine the critical temperature accurately based on the finite-size scaling of the Binder ratio. Comparing with the data on the simple cubic lattice, we argue the universal finite-size scaling. We also calculate the classical XY model and the classical Heisenberg model on the pyrochlore lattice.
Locally converging algorithms for determining the critical temperature in Ising systems
Faraggi, Eshel; Robb, Daniel T.
2008-10-01
We introduce a class of algorithms that converge to criticality automatically, in a way similar to the invaded cluster algorithm. Unlike the invaded cluster algorithm which uses global percolation as a test for criticality, these local algorithms use an average over local observables, specifically the number of satisfied bonds, in a feedback loop which drives the system toward criticality. Two specific algorithms are introduced, the average algorithm and the locally converging Wolff algorithm. We apply these algorithms to study the Ising square lattice and the Ising Bethe lattice. We find reasonable convergence to the critical temperature for both systems under the locally converging Wolff algorithm. We also re-examine the phase diagram of the dilute two-dimensional (2D) Ising model and find results supporting our previously reported conclusions regarding the existence of a local regime of magnetization below the percolations threshold. In addition, the presented algorithms are computationally more efficient than the invaded cluster algorithm, requiring less CPU time and memory.
The square lattice Ising model on the rectangle I: Finite systems
Hucht, Alfred
2016-01-01
The partition function of the square lattice Ising model on the rectangle is calculated exactly for arbitrary system size $L\\times M$ and temperature. We start with the dimer method of Kasteleyn, McCoy & Wu, construct a highly symmetric block transfer matrix and derive a factorization of the involved determinant, effectively decomposing the free energy into two parts, $F(L,M)=F_{\\infty}^{\\leftrightarrow}(L,M)+F_\\mathrm{res}^{\\leftrightarrow}(L,M)$. The residual part $F_\\mathrm{res}^{\\leftrightarrow}(L,M)$ contains the nontrivial finite-size contributions and becomes exponentially small for large $L/M$ and off-critical temperatures. It is given by the determinant of a $\\frac{M}{2}\\times\\frac{M}{2}$ matrix and can be mapped onto an effective spin model with $M$ spins and long-range interactions. The relations to the Casimir potential and the Casimir force scaling functions are discussed.
Carlström, Johan
2017-09-01
I derive a dual description of lattice fermions, specifically focusing on the t-J and Hubbard models, that allow diagrammatic techniques to be employed efficiently in the strongly correlated regime, as well as for systems with a restricted Hilbert space. These constructions are based on spin-charge transformation, where the lattice fermions of the original model are mapped onto spins and spin-less fermions. This mapping can then be combined with Popov-Fedotov fermionisation, where the spins are mapped onto lattice fermions with imaginary chemical potential. The resulting models do not contain any large expansion parameters, even for strongly correlated systems. Also, they exhibit dramatically smaller corrections to the density matrix from nonlinear terms in the Hamiltonian. The combination of these two properties means that they can be addressed with diagrammatic methods, including simulation techniques based on stochastic sampling of diagrammatic expansions.
Local operation on identical particles systems
Rendón, O
2011-01-01
We describe identical particles through their extrinsic physical properties and operationally with an operator of selective measure Mm. The operator Mm is formed through non-symmetrized tensor product of one-particle measurement operators, so that it does not commute with the permutation operator P. This operator of selective measure Mm is a local operation (LO) if it acts on physical systems of distinguishable particles, but when Mm acts on the Hilbert sub-space of a system with a constant number of indistinguishable particles this can generate entanglement in the system. We will call entanglement by measurement (EbM), this way of producing entanglement. In this framework, we show entangle production examples for systems of two fermions (or bosons) when the operator Mm has two-particle events that are not mutually exclusive.
IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM
Directory of Open Access Journals (Sweden)
Stojce Ilcev
2011-03-01
Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.
Randrianandrasana, Michel; Wei, Xueyong; Lowe, David
2010-01-01
The global and local synchronisation of a square lattice composed of alternating Duffing resonators and van der Pol oscillators coupled through displacement is studied. The lattice acts as a sensing device in which the input signal is characterised by an external driving force that is injected into the system through a subset of the Duffing resonators. The parameters of the system are taken from MEMS devices. The effects of the system parameters, the lattice architecture and size are discussed.
Arta Musaraj
2010-01-01
Facing turmoil and continuous stunning, local governing bodies, decision makers and local actors, in most of cases found the most stable solution has been the regional cooperation and particularly that of increasing and strengthening local human resources capacities at a regional level. Trying to increase competiveness, local systems understand more and more the importance of being flexible, on the frame of a sustainable strategic planning. Local infrastructure and interaction of all local fa...
Bioinspired sensory systems for local flow characterization
Colvert, Brendan; Chen, Kevin; Kanso, Eva
2016-11-01
Empirical evidence suggests that many aquatic organisms sense differential hydrodynamic signals.This sensory information is decoded to extract relevant flow properties. This task is challenging because it relies on local and partial measurements, whereas classical flow characterization methods depend on an external observer to reconstruct global flow fields. Here, we introduce a mathematical model in which a bioinspired sensory array measuring differences in local flow velocities characterizes the flow type and intensity. We linearize the flow field around the sensory array and express the velocity gradient tensor in terms of frame-independent parameters. We develop decoding algorithms that allow the sensory system to characterize the local flow and discuss the conditions under which this is possible. We apply this framework to the canonical problem of a circular cylinder in uniform flow, finding excellent agreement between sensed and actual properties. Our results imply that combining suitable velocity sensors with physics-based methods for decoding sensory measurements leads to a powerful approach for understanding and developing underwater sensory systems.
Jammed lattice sphere packings
Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore
2013-01-01
We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a...
Imaging Photon Lattice States by Scanning Defect Microscopy
Underwood, D. L.; Shanks, W. E.; Li, Andy C. Y.; Ateshian, Lamia; Koch, Jens; Houck, A. A.
2016-04-01
Microwave photons inside lattices of coupled resonators and superconducting qubits can exhibit surprising matterlike behavior. Realizing such open-system quantum simulators presents an experimental challenge and requires new tools and measurement techniques. Here, we introduce scanning defect microscopy as one such tool and illustrate its use in mapping the normal-mode structure of microwave photons inside a 49-site kagome lattice of coplanar waveguide resonators. Scanning is accomplished by moving a probe equipped with a sapphire tip across the lattice. This locally perturbs resonator frequencies and induces shifts of the lattice resonance frequencies, which we determine by measuring the transmission spectrum. From the magnitude of mode shifts, we can reconstruct photon field amplitudes at each lattice site and thus create spatial images of the photon-lattice normal modes.
Smile (System/Machine-Independent Local Environment)
Energy Technology Data Exchange (ETDEWEB)
Fletcher, J.G.
1988-04-01
This document defines the characteristics of Smile, a System/machine-independent local environment. This environment consists primarily of a number of primitives (types, macros, procedure calls, and variables) that a program may use; these primitives provide facilities, such as memory allocation, timing, tasking and synchronization beyond those typically provided by a programming language. The intent is that a program will be portable from system to system and from machine to machine if it relies only on the portable aspects of its programming language and on the Smile primitives. For this to be so, Smile itself must be implemented on each system and machine, most likely using non-portable constructions; that is, while the environment provided by Smile is intended to be portable, the implementation of Smile is not necessarily so. In order to make the implementation of Smile as easy as possible and thereby expedite the porting of programs to a new system or a new machine, Smile has been defined to provide a minimal portable environment; that is, simple primitives are defined, out of which more complex facilities may be constructed using portable procedures. The implementation of Smile can be as any of the following: the underlying software environment for the operating system of an otherwise {open_quotes}bare{close_quotes} machine, a {open_quotes}guest{close_quotes} system environment built upon a preexisting operating system, an environment within a {open_quotes}user{close_quotes} process run by an operating system, or a single environment for an entire machine, encompassing both system and {open_quotes}user{close_quotes} processes. In the first three of these cases the tasks provided by Smile are {open_quotes}lightweight processes{close_quotes} multiplexed within preexisting processes or the system, while in the last case they also include the system processes themselves.
TREES AND SEMI-LATTICES: ANALYSING SPACE CONFIGURATION OF TWO URBAN SYSTEMS IN LISBON REGI
Directory of Open Access Journals (Sweden)
Israel Guarda
2016-09-01
Full Text Available This study examines patterns of order and structure in street networks and its relationships with spatial life of two urban neighborhoods (housing estates. It explores the concepts of “tree” and “semi-lattice” as two different ways of looking and thinking about the structure of cities, each one generating a different form of life and community place (Alexander, 1965. The authors propose a configurational analysis of street networks of two urban plans designed according to different city ideologies and historical background. Based on space syntax methodology the street network was represented both as convex spaces and axial lines as nodes of a graph. The network was then analyzed in terms of the mathematical properties of the graph. The objective was to address a comparative study of structural properties of the urban street networks in order to speculate some implications on social life of each neighborhood. Syntactic measures have shown that conceptual designs have different spatial and social patterns both at global and local scales. It was corroborated that the difference between the characteristics of topological properties which reflects the mathematical principle of tree and semi-lattice is responsible for the different character of public life we found in each urban area.
Institute of Scientific and Technical Information of China (English)
Mona Khare; Shraddha Roy
2008-01-01
The purpose of the present paper is to study the entropy hs(Φ) of a quantum dynamical systems Φ= (L,s,φ),where s is a bayessian state on an orthomodular lattice L.Having introduced the notion of entropy hs(φ,)of partition of a Boolean algebra B with respect to a state s and a state preserving homomorphism φ,we prove a few results on that,define the entropy of a dynamical system hs(Φ),and show its invariance.The concept of sufficient families is also given and we establish that hs(Φ) comes out to be equal to the supremum of hs(φ,),where varies over any sufficient family.The present theory has then been extended to the quantum dynamical system ( L,s,φ),which as an effect of the theory of commutators and Bell inequalities can equivalently be replaced by the dynamical system (B,s0,φ),where B is a Boolean algebra and so is a state on B.
Zeng, Jianhua
2013-01-01
It is commonly known that stable bright solitons in periodic potentials, which represent gratings in photonics/plasmonics, or optical lattices in quantum gases, exist either in the spectral semi-infinite gap (SIG) or in finite bandgaps. Using numerical methods, we demonstrate that, under the action of the cubic self-focusing nonlinearity, defects in the form of "holes" in two-dimensional (2D) lattices support continuous families of 2D solitons \\textit{embedded} into the first two Bloch bands of the respective linear spectrum, where solitons normally do not exist. The two families of the \\textit{embedded defect solitons} (EDSs) are found to be continuously linked by the branch of \\textit{gap defect solitons} (GDSs) populating the first finite bandgap. Further, the EDS branch traversing the first band links the GDS family with the branch of regular defect-supported solitons populating the SIG. Thus, we construct a continuous chain of regular, embedded, and gap-mode solitons ("superfamily") threading the entire ...
Chakrabarti, J; Bagchi, B; Chakrabarti, Jayprokas; Basu, Asis; Bagchi, Bijon
2000-01-01
Fermions on the lattice have bosonic excitations generated from the underlying periodic background. These, the lattice bosons, arise near the empty band or when the bands are nearly full. They do not depend on the nature of the interactions and exist for any fermion-fermion coupling. We discuss these lattice boson solutions for the Dirac Hamiltonian.
Directory of Open Access Journals (Sweden)
Futa Yuichi
2016-03-01
Full Text Available In this article, we formalize the definition of lattice of ℤ-module and its properties in the Mizar system [5].We formally prove that scalar products in lattices are bilinear forms over the field of real numbers ℝ. We also formalize the definitions of positive definite and integral lattices and their properties. Lattice of ℤ-module is necessary for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [14], and cryptographic systems with lattices [15] and coding theory [9].
Pediatric scleroderma: systemic or localized forms.
Torok, Kathryn S
2012-04-01
Pediatric scleroderma includes 2 major groups of clinical entities, systemic sclerosis (SSc) and localized scleroderma (LS). Although both share a common pathophysiology, their clinical manifestations differ. LS is typically confined to the skin and underlying subcutis, with up to a quarter of patients showing extracutaneous disease manifestations such as arthritis and uveitis. Vascular, cutaneous, gastrointestinal, pulmonary, and musculoskeletal involvement are most commonly seen in children with SSc. Treatment of both forms targets the active inflammatory stage and halts disease progression; however, progress needs to be made toward the development of more effective antifibrotic therapy to help reverse disease damage.
Barcode based localization system in indoor environment
Directory of Open Access Journals (Sweden)
Ľubica Ilkovičová
2014-12-01
Full Text Available Nowadays, in the era of intelligent buildings, there is a need to create indoornavigation systems, what is steadily a challenge. QR (Quick Response codesprovide accurate localization also in indoor environment, where other navigationtechniques (e.g. GPS are not available. The paper deals with the issues of posi-tioning using QR codes, solved at the Department of Surveying, Faculty of CivilEngineering SUT in Bratislava. Operating principle of QR codes, description ofthe application for positioning in indoor environment based on OS Android forsmartphones are described.
Quasi-Monte Carlo methods for lattice systems: A first look
Jansen, K.; Leovey, H.; Ammon, A.; Griewank, A.; Müller-Preussker, M.
2014-03-01
We investigate the applicability of quasi-Monte Carlo methods to Euclidean lattice systems for quantum mechanics in order to improve the asymptotic error behavior of observables for such theories. In most cases the error of an observable calculated by averaging over random observations generated from an ordinary Markov chain Monte Carlo simulation behaves like N, where N is the number of observations. By means of quasi-Monte Carlo methods it is possible to improve this behavior for certain problems to N-1, or even further if the problems are regular enough. We adapted and applied this approach to simple systems like the quantum harmonic and anharmonic oscillator and verified an improved error scaling. Catalogue identifier: AERJ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERJ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence version 3 No. of lines in distributed program, including test data, etc.: 67759 No. of bytes in distributed program, including test data, etc.: 2165365 Distribution format: tar.gz Programming language: C and C++. Computer: PC. Operating system: Tested on GNU/Linux, should be portable to other operating systems with minimal efforts. Has the code been vectorized or parallelized?: No RAM: The memory usage directly scales with the number of samples and dimensions: Bytes used = “number of samples” × “number of dimensions” × 8 Bytes (double precision). Classification: 4.13, 11.5, 23. External routines: FFTW 3 library (http://www.fftw.org) Nature of problem: Certain physical models formulated as a quantum field theory through the Feynman path integral, such as quantum chromodynamics, require a non-perturbative treatment of the path integral. The only known approach that achieves this is the lattice regularization. In this formulation the path integral is discretized to a finite, but very high dimensional integral. So far only Monte
Breakdown localization in the fixed gap system
Rajamaki, Robin; Wuensch, Walter
2014-01-01
Accurate localization of breakdowns in vacuum could help shed light on breakdown related processes that are not yet fully understood. At the DC spark lab at CERN, an instrument called the Fixed Gap System (FGS) has been developed partially for this purpose. Among other things, the FGS has four built-in antennas, which are intended for breakdown localization. The capability of this aspect of the FGS was explored in this report. Specifically, the feasibility of using a method similar to that which is used in cavity Beam Position Monitors (BPMs) was investigated. The usable frequency range of the current experimental setup was also studied. Firstly, a modal analysis of the inner geometry of the FGS was done in HFSS. This showed that the two first modes to be expected in the spark gap quite differ from those of the ideal pillbox – both in field pattern and in frequency ( 4 and 6 GHz vs. 0.2 and 3 GHz). Secondly, S-parameters of the system were measured. These showed that the coupling between antennas is weak...
Charged Local Defects in Extended Systems
Energy Technology Data Exchange (ETDEWEB)
Schultz, Peter A.
1999-05-25
The conventional approach to treating charged defects in extended systems in first principles calculations is via the supercell approximation using a neutralizing jellium background charge. I explicitly demonstrate shortcomings of this standard approach and discuss the consequences. Errors in the electrostatic potential surface over the volume of a supercell are shown to be comparable to a band gap energy in semiconductor materials, for cell sizes typically used in first principles simulations. I present an alternate method for eliminating the divergence of the Coulomb potential in supercell calculations of charged defects in extended systems that embodies a correct treatment of the electrostatic potential in the local viciniq of the a charged defect, via a mixed boundary condition approach. I present results of first principles calculations of charged vacancies in NaCl that illustrate the importance of polarization effects once an accurate representation of the local potential is obtained. These polarization effects, poorly captured in small supercells, also impact the energetic on the scale of typical band gap energies.
Filippov, A. V.
2016-10-01
The interaction of two charged point macroparticles located in Wigner-Seitz cells of simple cubic (SC), body-centered cubic (BCC), or face-centered cubic (FCC) lattices in an equilibrium plasma has been studied within the Debye approximation or, more specifically, based on the linearized Poisson-Boltzmann model. The shape of the outer boundary is shown to exert a strong influence on the pattern of electrostatic interaction between the two macroparticles, which transforms from repulsion at small interparticle distances to attraction as the interparticle distance approaches half the length of the computational cell. The macroparticle pair interaction potential in an equilibrium plasma is shown to be nevertheless the Debye one and purely repulsive for likely charged macroparticles.
Lunar rovers and local positioning system
Avery, James; Su, Renjeng
1991-11-01
Telerobotic rovers equipped with adequate actuators and sensors are clearly necessary for extraterrestrial construction. They will be employed as substitutes for humans, to perform jobs like surveying, sensing, signaling, manipulating, and the handling of small materials. Important design criteria for these rovers include versatility and robustness. They must be easily programmed and reprogrammed to perform a wide variety of different functions, and they must be robust so that construction work will not be jeopardized by parts failures. The key qualities and functions necessary for these rovers to achieve the required versatility and robustness are modularity, redundancy, and coordination. Three robotic rovers are being built by CSC as a test bed to implement the concepts of modularity and coordination. The specific goal of the design and construction of these robots is to demonstrate the software modularity and multirobot control algorithms required for the physical manipulation of constructible elements. Each rover consists of a transporter platform, bus manager, simple manipulator, and positioning receivers. These robots will be controlled from a central control console via a radio-frequency local area network (LAN). To date, one prototype transporter platform frame was built with batteries, motors, a prototype single-motor controller, and two prototype internal LAN boards. Software modules were developed in C language for monitor functions, i/o, and parallel port usage in each computer board. Also completed are the fabrication of half of the required number of computer boards, the procurement of 19.2 Kbaud RF modems for inter-robot communications, and the simulation of processing requirements for positioning receivers. In addition to the robotic platform, the fabrication of a local positioning system based on infrared signals is nearly completed. This positioning system will make the rovers into a moving reference system capable of performing site surveys. In
Local chemical potentials and pressures in heterogeneous systems: Adsorptive, absorptive, interfaces
Tovbin, Yu. K.
2016-07-01
Equations self-consistently describing chemical and mechanical equilibria in heterogeneous systems are derived. The equations are based on the lattice gas model using discrete distributions of molecules in space (on a scale comparable to molecular size) and continuum distributions of molecules (at short distances inside the cells) during their translational and vibrational motions. It is shown that the theory provides a unified description of the equilibrium distributions of molecules in three aggregate states and at their interfaces. Potential functions of intermolecular interactions (such as Mie pair potentials) in several coordination spheres that determine the compressibility of the lattice structure are considered. For simplicity, it is assumed that differences between the sizes of mixture components are small. Expressions for the local components of the pressure tensor inside multicomponent solid phases and heterogeneous systems (adsorptive, absorptive, and interfaces) are obtained. It is established that they can be used to calculate the lattice parameters of deforming phases and the thermodynamic characteristics of interfaces, including surface tension. The tensor nature of the chemical potential in heterogeneous systems is discussed.
Shavykin, Oleg V; Neelov, Igor M; Darinskii, Anatolii A
2016-09-21
The effect of excluded volume (EV) interactions on the manifestation of the local dynamics in the spin-lattice NMR relaxation in dendrimers has been studied by using Brownian dynamics simulations. The study was motivated by the theory developed by Markelov et al., [J. Chem. Phys., 2014, 140, 244904] for a Gaussian dendrimer model without EV interactions. The theory connects the experimentally observed dependence of the spin-lattice relaxation rate 1/T(1)H on the location of NMR active groups with the restricted flexibility (semiflexibility) of dendrimers. Semiflexibility was introduced through the correlations between the orientations of different segments. However, these correlations exist even in flexible dendrimer models with EV interactions. We have simulated coarse-grained flexible and semiflexible dendrimer models with and without EV interactions. Every dendrimer segment consisted of two rigid bonds. Semiflexibility was introduced through a potential which restricts the fluctuations of angles between neighboring bonds but does not change orientational correlations in the EV model as compared to the flexible case. The frequency dependence of the reduced 1/T(1)H(ωH) for segments and bonds belonging to different dendrimer shells was calculated. It was shown that the main effect of EV interactions consists of a much stronger contribution of the overall dendrimer rotation to the dynamics of dendrimer segments as compared to phantom models. After the exclusion of this contribution the manifestation of internal dynamics in spin-lattice NMR relaxation appears to be practically insensitive to EV interactions. For the flexible models, the position ωmax of the peak of the modified 1/T(1)H(ωH) does not depend on the shell number. For semiflexible models, the maximum of 1/T(1)H(ωH) for internal segments or bonds shifts to lower frequencies as compared to outer ones. The dependence of ωmax on the number of dendrimer shells appears to be universal for segments and
LOCAL ENTROPY FUNCTION OF DYNAMICAL SYSTEM
Directory of Open Access Journals (Sweden)
İsmail TOK
2013-05-01
Full Text Available In this work, we first,define the entropy function of the topological dynamical system and investigate basic properties of this function without going into details. Let (X,A,T be a probability measure space and consider P = { pl5p2,...,pn} a finite measurable partition of all sub-sets of topological dynamical system (X,T.Then,the quantity H (P = ^ zpt is called the i=1 entropy function of finite measurable partition P.Where f-1 log t if 0 0.If diam(P < s,then the quantity L^ (T = h^ (T - h^ (T,P is called a local entropy function of topological dynamical system (X,T . In conclusion, Let (X,T and (Y,S be two topological dynamical system. If TxS is a transformation defined on the product space (XxY,TxS with (TxS(x , y = (Tx,Sy for all (x,y X x Y.Then L ^^ (TxS = L^d(T + L (S .and, we prove some fundamental properties of this function.
Model reduction of systems with localized nonlinearities.
Energy Technology Data Exchange (ETDEWEB)
Segalman, Daniel Joseph
2006-03-01
An LDRD funded approach to development of reduced order models for systems with local nonlinearities is presented. This method is particularly useful for problems of structural dynamics, but has potential application in other fields. The key elements of this approach are (1) employment of eigen modes of a reference linear system, (2) incorporation of basis functions with an appropriate discontinuity at the location of the nonlinearity. Galerkin solution using the above combination of basis functions appears to capture the dynamics of the system with a small basis set. For problems involving small amplitude dynamics, the addition of discontinuous (joint) modes appears to capture the nonlinear mechanics correctly while preserving the modal form of the predictions. For problems involving large amplitude dynamics of realistic joint models (macro-slip), the use of appropriate joint modes along with sufficient basis eigen modes to capture the frequencies of the system greatly enhances convergence, though the modal nature the result is lost. Also observed is that when joint modes are used in conjunction with a small number of elastic eigen modes in problems of macro-slip of realistic joint models, the resulting predictions are very similar to those of the full solution when seen through a low pass filter. This has significance both in terms of greatly reducing the number of degrees of freedom of the problem and in terms of facilitating the use of much larger time steps.
Receiving Assistance and Local Food System Participation
Directory of Open Access Journals (Sweden)
Rebecca L. Som Castellano
2017-02-01
Full Text Available A body of literature has noted that local food systems (LFSs may not involve active participation by individuals with lower incomes. This is, in part, a function of racial and class hegemony, as well as physical and financial accessibility of LFSs. LFS institutions, such as farmers’ markets, have been working to facilitate receipt of food assistance programs, such as the Supplemental Nutrition Assistance Program (SNAP. Charitable assistance programs, such as food banks, have also been actively working to engage in LFSs, for example, by making local foods available. However, little research has explored the role that receiving public or charitable assistance can play in influencing LFS participation. In this article, I utilize quantitative and qualitative data collected from across the state of Ohio to examine the relationship between receiving assistance and LFS participation for women, who remain predominately responsible for food provisioning in the U.S., including among those who participate in LFSs. Quantitative results suggest that receiving assistance can increase participation in LFSs. Qualitative data provides more nuanced information about the importance of food assistance for women who want to participate in LFSs, and suggest that it is essential that food cooperatives and farmers’ markets are equipped to receive food assistance programs, such as SNAP, in order for women with lower incomes to participate in LFSs.
Liu, Q
2016-01-01
In this paper, a multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is proposed for convection heat transfer in porous media under local thermal non-equilibrium (LTNE) condition. The model is constructed within the framework of the three-distribution-function approach: two temperature-based MRT-LB equations are proposed for the temperature fields of fluid and solid phases in addition to the MRT-LB equation of a density distribution function for the velocity field described by the generalized non-Darcy model. The thermal non-equilibrium effects are incorporated into the model by adding source terms into the temperature-based MRT-LB equations. Moreover, the discrete lattice effects are considered in the introduction of source terms into the temperature-based MRT-LB equations. The source terms accounting for the thermal non-equilibrium effects are simple and the model retains the inherent features of the standard LB method. Numerical results demonstrate that the proposed model can be served as an accura...
Existence of lattice solutions to semilinear elliptic systems with periodic potential
Directory of Open Access Journals (Sweden)
Nicholas D. Alikakos
2012-01-01
Full Text Available Under the assumption that the potential W is invariant under a general discrete reflection group $G'=TG$ acting on $mathbb{R}^n$, we establish existence of G'-equivariant solutions to $Delta u - W_u(u = 0$, and find an estimate. By taking the size of the cell of the lattice in space domain to infinity, we obtain that these solutions converge to G-equivariant solutions connecting the minima of the potential W along certain directions at infinity. When particularized to the nonlinear harmonic oscillator $u''+alpha sin u=0$, $alpha>0$, the solutions correspond to those in the phase plane above and below the heteroclinic connections, while the G-equivariant solutions captured in the limit correspond to the heteroclinic connections themselves. Our main tool is the G'-positivity of the parabolic semigroup associated with the elliptic system which requires only the hypothesis of symmetry for W. The constructed solutions are positive in the sense that as maps from $mathbb{R}^n$ into itself leave the closure of the fundamental alcove (region invariant.
Numerical study of a three-state host-parasite system on the square lattice
Hasegawa, Takehisa; Konno, Norio; Masuda, Naoki
2011-04-01
We numerically study the phase diagram of a three-state host-parasite model on the square lattice motivated by population biology. The model is an extension of the contact process, and the three states correspond to an empty site, a host, and a parasite. We determine the phase diagram of the model by scaling analysis. In agreement with previous results, three phases are identified: the phase in which both hosts and parasites are extinct (S0), the phase in which hosts survive but parasites are extinct (S01), and the phase in which both hosts and parasites survive (S012). We argue that both the S0-S01 and S01-S012 boundaries belong to the directed percolation class. In this model, it has been suggested that an excessively large reproduction rate of parasites paradoxically extinguishes hosts and parasites and results in S0. We show that this paradoxical extinction is a finite size effect; the corresponding parameter region is likely to disappear in the limit of infinite system size.
Machine-learning approach for local classification of crystalline structures in multiphase systems
Dietz, C.; Kretz, T.; Thoma, M. H.
2017-07-01
Machine learning is one of the most popular fields in computer science and has a vast number of applications. In this work we will propose a method that will use a neural network to locally identify crystal structures in a mixed phase Yukawa system consisting of fcc, hcp, and bcc clusters and disordered particles similar to plasma crystals. We compare our approach to already used methods and show that the quality of identification increases significantly. The technique works very well for highly disturbed lattices and shows a flexible and robust way to classify crystalline structures that can be used by only providing particle positions. This leads to insights into highly disturbed crystalline structures.
Koda, Daniel S.; Bechstedt, Friedhelm; Marques, Marcelo; Teles, Lara K.
2017-07-01
Van der Waals heterostructures have great potential in large-scale integration devices and exploration of new physics. Experimental investigations allow flexible combinations of two-dimensional crystals in device fabrications. Theory, however, has limitations of supercell sizes and commensurability, translated into computational effort. In this work, we demonstrate the application of the coincidence lattice method to simulate two \\hbox {hBN/MoSe}_2 heterobilayers taking interlayer twist effects into account. We predict that both systems are stable upon contact and interact via van der Waals dispersions. We found that electronic properties of \\hbox {MoSe}_2 are preserved for both simulated systems, but hBN suffers from the increase of interface interactions, as evidenced by band structures and density of states calculations. Finally, band discontinuities are obtained and charge transfer arguments explain small shifts in band offsets with respect to natural alignments. We conclude that hBN is a reasonable substrate for preserving useful properties of \\hbox {MoSe}_2 for application in electronic and optoelectronic devices, and that interlayer twist angles play a significant role in the physics of van der Waals heterostructures.
Energy Technology Data Exchange (ETDEWEB)
Vakhnenko, Oleksiy O., E-mail: vakhnenko@bitp.kiev.ua
2016-05-27
Highlights: • The integrable nonlinear Schrödinger system on a triangular-lattice ribbon is inclined to metamorphoses. • The system under study is capable to incorporate the effect of external linear potential. • The system criticality against the background parameter reduces the number of independent field variables. • At critical point the system Poisson structure becomes degenerate. • The effect of criticality is elucidated by the system one-soliton solution. - Abstract: The variativity of governing coupling parameters in the integrable nonlinear Schrödinger system on a triangular-lattice ribbon is shown to ensure the important qualitative rearrangements in the system dynamics. There are at least the two types of system crucial modifications stipulated by the two types of governing parameters. Thus the longitudinal coupling parameters regulated mainly by the background values of concomitant field variables are responsible for the bifurcation of primary integrable nonlinear system into the integrable nonlinear system of Ablowitz–Ladik type. As a consequence in a critical point the number of independent field variables is reduced by a half and the system Poisson structure turns out to be degenerate. On the other hand the transverse coupling parameters regulated basically by the choice of their a priori arbitrary dependencies on time are capable to incorporate the effect of external linear potential. As a consequence the primary integrable nonlinear system with appropriately adjusted parametrical driving becomes isomorphic to the system modeling the Bloch oscillations of charged nonlinear carriers in an electrically biased ribbon of triangular lattice. The multi-component structure of basic integrable system alongside with the attractive character of system nonlinearities has predetermined the logic of whole consideration.
Indian Academy of Sciences (India)
Y J Jeon; M Jamil; Hyo-Dong Lee; J T Rhee
2008-09-01
This article reports a comparative study of the phase separation process in a polymer-dispersed liquid crystal, based on a Metropolis Monte Carlo simulation study of three lattice systems. We propose a model for the different processes occurring in the formation of polymer-dispersed liquid crystals (PDLCs). The mechanism of PDLC is studied as a function of quench temperature, concentration and degree of polymerization of liquid crystals and polymers. The obtained resultant phase diagrams of the three systems are approximated and compared with the Flory–Huggins theory, and show a good agreement. It has been observed in the simulation results that among all the three systems, the 40 × 40 × 40 lattice showed the most accurate, reliable and stable results.
Butera, Paolo; Pernici, Mario
2013-01-01
Recently an expansion as a power series in 1/d has been presented for the specific entropy of a complete dimer covering of a d-dimensional hypercubic lattice. This paper extends from 3 to 10 the number of terms known in the series. Likewise an expansion for the entropy, dependent on the dimer-density p, of a monomer-dimer system, involving a sum sum_k a_k(d) p^k, has been recently offered. We herein extend the number of the known expansion coefficients from 6 to 20 for the hyper-cubic lattices of general dimension d and from 6 to 24 for the hyper-cubic lattices of dimensions d 2. The computations of this paper have led us to make the following marvelous conjecture: "In the case of the hyper-cubic lattices, all the expansion coefficients, a_k(d), are positive"! This paper results from a simple melding of two disparate research programs: one computing to high orders the Mayer series coefficients of a dimer gas, the other studying the development of entropy from these coefficients. An effort is made to make thi...
Open quantum spin systems in semiconductor quantum dots and atoms in optical lattices
Energy Technology Data Exchange (ETDEWEB)
Schwager, Heike
2012-07-04
In this Thesis, we study open quantum spin systems from different perspectives. The first part is motivated by technological challenges of quantum computation. An important building block for quantum computation and quantum communication networks is an interface between material qubits for storage and data processing and travelling photonic qubits for communication. We propose the realisation of a quantum interface between a travelling-wave light field and the nuclear spins in a quantum dot strongly coupled to a cavity. Our scheme is robust against cavity decay as it uses the decay of the cavity to achieve the coupling between nuclear spins and the travelling-wave light fields. A prerequiste for such a quantum interface is a highly polarized ensemble of nuclear spins. High polarization of the nuclear spin ensemble is moreover highly desirable as it protects the potential electron spin qubit from decoherence. Here we present the theoretical description of an experiment in which highly asymmetric dynamic nuclear spin pumping is observed in a single self-assembled InGaAs quantum dot. The second part of this Thesis is devoted to fundamental studies of dissipative spin systems. We study general one-dimensional spin chains under dissipation and propose a scheme to realize a quantum spin system using ultracold atoms in an optical lattice in which both coherent interaction and dissipation can be engineered and controlled. This system enables the study of non-equilibrium and steady state physics of open and driven spin systems. We find, that the steady state expectation values of different spin models exhibit discontinuous behaviour at degeneracy points of the Hamiltonian in the limit of weak dissipation. This effect can be used to dissipatively probe the spectrum of the Hamiltonian. We moreover study spin models under the aspect of state preparation and show that dissipation drives certain spin models into highly entangled state. Finally, we study a spin chain with
Development of a Prototype Lattice Boltzmann Code for CFD of Fusion Systems.
Energy Technology Data Exchange (ETDEWEB)
Pattison, Martin J; Premnath, Kannan N; Banerjee, Sanjoy; Dwivedi, Vinay
2007-02-26
Designs of proposed fusion reactors, such as the ITER project, typically involve the use of liquid metals as coolants in components such as heat exchangers, which are generally subjected to strong magnetic fields. These fields induce electric currents in the fluids, resulting in magnetohydrodynamic (MHD) forces which have important effects on the flow. The objective of this SBIR project was to develop computational techniques based on recently developed lattice Boltzmann techniques for the simulation of these MHD flows and implement them in a computational fluid dynamics (CFD) code for the study of fluid flow systems encountered in fusion engineering. The code developed during this project, solves the lattice Boltzmann equation, which is a kinetic equation whose behaviour represents fluid motion. This is in contrast to most CFD codes which are based on finite difference/finite volume based solvers. The lattice Boltzmann method (LBM) is a relatively new approach which has a number of advantages compared with more conventional methods such as the SIMPLE or projection method algorithms that involve direct solution of the Navier-Stokes equations. These are that the LBM is very well suited to parallel processing, with almost linear scaling even for very large numbers of processors. Unlike other methods, the LBM does not require solution of a Poisson pressure equation leading to a relatively fast execution time. A particularly attractive property of the LBM is that it can handle flows in complex geometries very easily. It can use simple rectangular grids throughout the computational domain -- generation of a body-fitted grid is not required. A recent advance in the LBM is the introduction of the multiple relaxation time (MRT) model; the implementation of this model greatly enhanced the numerical stability when used in lieu of the single relaxation time model, with only a small increase in computer time. Parallel processing was implemented using MPI and demonstrated the
Local rollback for fault-tolerance in parallel computing systems
Blumrich, Matthias A [Yorktown Heights, NY; Chen, Dong [Yorktown Heights, NY; Gara, Alan [Yorktown Heights, NY; Giampapa, Mark E [Yorktown Heights, NY; Heidelberger, Philip [Yorktown Heights, NY; Ohmacht, Martin [Yorktown Heights, NY; Steinmacher-Burow, Burkhard [Boeblingen, DE; Sugavanam, Krishnan [Yorktown Heights, NY
2012-01-24
A control logic device performs a local rollback in a parallel super computing system. The super computing system includes at least one cache memory device. The control logic device determines a local rollback interval. The control logic device runs at least one instruction in the local rollback interval. The control logic device evaluates whether an unrecoverable condition occurs while running the at least one instruction during the local rollback interval. The control logic device checks whether an error occurs during the local rollback. The control logic device restarts the local rollback interval if the error occurs and the unrecoverable condition does not occur during the local rollback interval.
Mapping how local perturbations influence systems-level brain dynamics
Gollo, Leonardo L.; James A. Roberts; Cocchi, Luca
2016-01-01
The human brain exhibits a relatively stable spatiotemporal organization that supports brain function and can be manipulated via local brain stimulation. Such perturbations to local cortical dynamics are globally integrated by distinct neural systems. However, it remains unclear how and why local changes in neural activity affect large-scale system dynamics. Here, we briefly review empirical and computational studies addressing how localized perturbations affect brain activity. We then system...
Basic Mars Navigation System For Local Areas
Petitfils, E.-A.; Boche-Sauvan, L.; Foing, B. H.; Monaghan, E.; Crews, Eurogeomars
2009-04-01
Introduction: This project has been first set up as a basic solution in navigation during EVA (extra-vehicular activities) in the Mars Society Desert Research Station in the desert of Utah. The main idea is to keep the system as simple as possible so that it can be easily adaptable and portable. The purpose of such a device is to tell the astronauts in EVA where they roughly are and then letting them reaching different points in avoiding any risky way. Thus the precision needed has not to be really high: even if it is about 50m, every astronaut can then look on a map and be able to design a way to another point. This navigation system will improve the safety of the EVA as it is an added reliable orientating tool. Concept: To look at a simple way to localize oneself, one should have a look at what has been done by mankind on Earth. Today, everyone can think of the GPS because it's simple and very reliable. However the infrastructure for such a system is huge and will not be for sure available during the first missions. We can think of course of a basic GPS using the satellites being in orbit but this approach is not yet as simple as we would like. If we want to keep the sky in sight, we can use the stars and the moons of Mars. Yet this would be a good solution and we can even have a star tracker that would give a good position according to the time of the picture. This solution has to be kept in mind but a star tracker is quite big for an astronaut without any rover nearby and using the sky may not be as precise as one should expect. Another useful tool is the compass. It has been used for centuries by sailors but on Mars, without a good magnetic field for this purpose. But sailors also use lighthouses and some placemarks on the land to localize themselves. This is done with a compass, measuring the angle between a placemark and the magnetic North. With two angles, we can then have the position of the boat. The idea here is the same: measuring the angles between
Discrete breathers in hexagonal dusty plasma lattices.
Koukouloyannis, V; Kourakis, I
2009-08-01
The occurrence of single-site or multisite localized vibrational modes, also called discrete breathers, in two-dimensional hexagonal dusty plasma lattices is investigated. The system is described by a Klein-Gordon hexagonal lattice characterized by a negative coupling parameter epsilon in account of its inverse dispersive behavior. A theoretical analysis is performed in order to establish the possibility of existence of single as well as three-site discrete breathers in such systems. The study is complemented by a numerical investigation based on experimentally provided potential forms. This investigation shows that a dusty plasma lattice can support single-site discrete breathers, while three-site in phase breathers could exist if specific conditions, about the intergrain interaction strength, would hold. On the other hand, out of phase and vortex three-site breathers cannot be supported since they are highly unstable.
β-Cu2V2O7 : A spin- (1)/(2) honeycomb lattice system
Tsirlin, Alexander A.; Janson, Oleg; Rosner, Helge
2010-10-01
We report on band-structure calculations and a microscopic model of the low-dimensional magnet β-Cu2V2O7 . Magnetic properties of this compound can be described by a spin- (1)/(2) anisotropic honeycomb lattice model with the averaged coupling J¯1=60-66K . The low symmetry of the crystal structure leads to two inequivalent couplings J1 and J1' but this weak spatial anisotropy does not affect the essential physics of the honeycomb spin lattice. The structural realization of the honeycomb lattice is highly nontrivial: the leading interactions J1 and J1' run via double bridges of VO4 tetrahedra between spatially separated Cu atoms while the interactions between structural nearest neighbors are negligible. The non-negligible interplane coupling J⊥≃15K gives rise to the long-range magnetic ordering at TN≃26K . Our model simulations improve the fit of the magnetic susceptibility data, compared to the previously assumed spin-chain models. Additionally, the simulated ordering temperature of 27 K is in remarkable agreement with the experiment. Our study evaluates β-Cu2V2O7 as the best available experimental realization of the spin- (1)/(2) Heisenberg model on the honeycomb lattice. We also provide an instructive comparison of different band-structure codes and computational approaches to the evaluation of exchange couplings in magnetic insulators.
The behavior of the lattice parameters in the Bi-Sn-Zn system
Directory of Open Access Journals (Sweden)
Braga Helena M.
2007-01-01
Full Text Available Lattice parameters, coefficients of thermal expansion and mass density were determined by means of X-ray powder diffraction between 30 and 180ºC (or 240ºC - depending on samples' composition. Rietveld refinement was performed in order to obtain phases' lattice parameters at each temperature. The Panalytical X' Pert Pro MPD was used for room temperature X-ray diffraction experiments (RTXRD with bulk samples. The aim was to identify the phases that were present in the sample, as well as, their lattice parameters. For some samples, powder high temperature X-ray diffraction measurements (HT-XRD were also performed, under a vacuum of 10-5 mbar or an argon atmosphere. It was found that the lattice parameters of (Bi, (Sn and (Zn don't change with the composition, at room temperature, as expected since all samples belong to the three phase region. It was also concluded that (Bi behaves like an isometric crystalline solid on the contrary of (Zn that has different expansion coefficients for different crystallographic directions a (= b and c.
Logarithmic entanglement lightcone in many-body localized systems
Deng, Dong-Ling; Li, Xiaopeng; Pixley, J. H.; Wu, Yang-Le; Das Sarma, S.
2017-01-01
We theoretically study the response of a many-body localized system to a local quench from a quantum information perspective. We find that the local quench triggers entanglement growth throughout the whole system, giving rise to a logarithmic lightcone. This saturates the modified Lieb-Robinson bound for quantum information propagation in many-body localized systems previously conjectured based on the existence of local integrals of motion. In addition, near the localization-delocalization transition, we find that the final states after the local quench exhibit volume-law entanglement. We also show that the local quench induces a deterministic orthogonality catastrophe for highly excited eigenstates, where the typical wave-function overlap between the pre- and postquench eigenstates decays exponentially with the system size.
Hackmann, Andreas; Ailion, David C.; Ganesan, Krishnamurthy; Laicher, Gernot; Goodrich, K. Craig; Cutillo, Antonio G.
1996-02-01
The water-biopolymer cross-relaxation model, proposed by H. E. Rorschach and C. F. Hazlewood (RH) [J. Magn. Reson.70,79 (1986)], explains the Larmor frequency dependence ofT1in many biological systems. However, the RH theory fails at low Larmor frequencies. In this paper, a more general version of the RH theory has been developed. This theory is valid at all frequencies. Use of the new expression for the spin-lattice relaxation rate (1/T1), earlier published experimental data in H2O/D2O bovine serum albumin, which had been measured over a wide frequency range (10 kHz to 100 MHz), were fitted over the entire frequency range. The agreement between theory and the experimental data is excellent. Theoretical expressions for the rotating-frame spin-lattice relaxation rate (1/T1ρ) were also obtained.
Dellar, Paul
2016-11-01
We present discrete kinetic and lattice Boltzmann formulations for reaction cross-diffusion systems, as commonly used to model microbiological chemotaxis and macroscopic predator-prey interactions, and their hyperbolic extensions with fluid-like persistence terms. For example, the canonical Patlak-Keller-Segal model for chemotaxis involves a flux of cells up the gradient of a chemical secreted by the cells, in addition to the usual down-gradient diffusive fluxes. Existing lattice Boltzmann approaches for such systems use finite difference approximations to compute the flux of cells due to the chemical gradient. The resulting coupling between, and necessary synchronisation of the evolution of, adjacent grid points greatly complicates boundary conditions, and efficient implementation on graphical processing units (GPUs). We present a kinetic formulation using cross-collisions between bases of moments for the two sets of distribution functions to couple the fluxes of the two species, from which we construct lattice Boltzmann algorithms using second-order Strang splitting. We demonstrate an efficient GPU implementation, and verify second-order spatial convergence towards spectral solutions for benchmark problems such as the finite-time blow-up in the Patlak-Keller-Segal model.
Jammed lattice sphere packings.
Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore
2013-12-01
We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.
Jammed lattice sphere packings
Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore
2013-12-01
We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.
Graphene antidot lattice waveguides
DEFF Research Database (Denmark)
Pedersen, Jesper Goor; Gunst, Tue; Markussen, Troels
2012-01-01
We introduce graphene antidot lattice waveguides: nanostructured graphene where a region of pristine graphene is sandwiched between regions of graphene antidot lattices. The band gaps in the surrounding antidot lattices enable localized states to emerge in the central waveguide region. We model...... the waveguides via a position-dependent mass term in the Dirac approximation of graphene and arrive at analytical results for the dispersion relation and spinor eigenstates of the localized waveguide modes. To include atomistic details we also use a tight-binding model, which is in excellent agreement...... with the analytical results. The waveguides resemble graphene nanoribbons, but without the particular properties of ribbons that emerge due to the details of the edge. We show that electrons can be guided through kinks without additional resistance and that transport through the waveguides is robust against...
On Discrete Painlevé Equations Associated with the Lattice KdV Systems and the Painlevé VI Equation
Nijhoff, F W; Grammaticos, B; Ohta, Y
1998-01-01
A new integrable nonautonomous nonlinear ordinary difference equation is presented which can be considered to be a discrete analogue of the Painleve V equation. Its derivation is based on the similarity reduction on the two-dimensional lattice of integrable partial difference equations of KdV type. The new equation which is referred to as GDP (generalised discrete Painleve equation) contains various ``discrete Painleve equations'' as subcases for special values/limits of the parameters, some of which were already given before in the literature. The general solution of the GDP can be expressed in terms of Painleve VI (PVI) transcendents. In fact, continuous PVI emerges as the equation obeyed by the solutions of the discrete equation in terms of the lattice parameters rather than the lattice variables that label the lattice sites. We show that the bilinear form of PVI is embedded naturally in the lattice systems leading to the GDP. Further results include the establishment of Baecklund and Schlesinger transform...
Non-local currents and the structure of eigenstates in planar discrete systems with local symmetries
Energy Technology Data Exchange (ETDEWEB)
Röntgen, M., E-mail: mroentge@physnet.uni-hamburg.de [Zentrum für optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Morfonios, C.V., E-mail: christian.morfonios@physnet.uni-hamburg.de [Zentrum für optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Diakonos, F.K., E-mail: fdiakono@phys.uoa.gr [Department of Physics, University of Athens, GR-15771 Athens (Greece); Schmelcher, P., E-mail: pschmelc@physnet.uni-hamburg.de [Zentrum für optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)
2017-05-15
Local symmetries are spatial symmetries present in a subdomain of a complex system. By using and extending a framework of so-called non-local currents that has been established recently, we show that one can gain knowledge about the structure of eigenstates in locally symmetric setups through a Kirchhoff-type law for the non-local currents. The framework is applicable to all discrete planar Schrödinger setups, including those with non-uniform connectivity. Conditions for spatially constant non-local currents are derived and we explore two types of locally symmetric subsystems in detail, closed-loops and one-dimensional open ended chains. We find these systems to support locally similar or even locally symmetric eigenstates. - Highlights: • We extend the framework of non-local currents to discrete planar systems. • Structural information about the eigenstates is gained. • Conditions for the constancy of non-local currents are derived. • We use the framework to design two types of example systems featuring locally symmetric eigenstates.
PT-symmetric phase in kagome photonic lattices
Chern, Gia-Wei
2015-01-01
Kagome lattice is a two-dimensional network of corner-sharing triangles and is often associated with geometrical frustration. In particular, the frustrated coupling between waveguide modes in a kagome array leads to a dispersionless flat band consisting of spatially localized modes. Here we propose a complex photonic lattice by placing $\\mathcal{PT}$-symmetric dimers at the kagome lattice points. Each dimer corresponds to a pair of strongly coupled waveguides. With balanced arrangement of gain and loss on individual dimers, the system exhibits a $\\mathcal{PT}$-symmetric phase for finite gain/loss parameter up to a critical value. The beam evolution in this complex kagome waveguide array exhibits a novel oscillatory rotation of optical power along the propagation distance. Long-lived local chiral structures originating from the nearly flat bands of the kagome structure are observed when the lattice is subject to a narrow beam excitation.
PT-symmetric phase in kagome-based photonic lattices.
Chern, Gia-Wei; Saxena, Avadh
2015-12-15
The kagome lattice is a two-dimensional network of corner-sharing triangles and is often associated with geometrical frustration. In particular, the frustrated coupling between waveguide modes in a kagome array leads to a dispersionless flat band consisting of spatially localized modes. Here we propose a complex photonic lattice by placing PT-symmetric dimers at the kagome lattice points. Each dimer corresponds to a pair of strongly coupled waveguides. With balanced arrangement of gain and loss on individual dimers, the system exhibits a PT-symmetric phase for finite gain/loss parameter up to a critical value. The beam evolution in this complex kagome waveguide array exhibits a novel oscillatory rotation of optical power along the propagation distance. Long-lived local chiral structures originating from the nearly flat bands of the kagome structure are observed when the lattice is subject to a narrow beam excitation.
You, Yi-Zhuang; Qi, Xiao-Liang; Xu, Cenke
We introduce the spectrum bifurcation renormalization group (SBRG) as a generalization of the real-space renormalization group for the many-body localized (MBL) system without truncating the Hilbert space. Starting from a disordered many-body Hamiltonian in the full MBL phase, the SBRG flows to the MBL fixed-point Hamiltonian, and generates the local conserved quantities and the matrix product state representations for all eigenstates. The method is applicable to both spin and fermion models with arbitrary interaction strength on any lattice in all dimensions, as long as the models are in the MBL phase. In particular, we focus on the 1 d interacting Majorana chain with strong disorder, and map out its phase diagram using the entanglement entropy. The SBRG flow also generates an entanglement holographic mapping, which duals the MBL state to a fragmented holographic space decorated with small blackholes.
Introduction: Dissipative localized structures in extended systems
Tlidi, Mustapha; Taki, Majid; Kolokolnikov, Theodore
2007-09-01
Localized structures belong to the class of dissipative structures found far from equilibrium. Contributions from the most representative groups working on a various fields of natural science such as biology, chemistry, plant ecology, mathematics, optics, and laser physics are presented. The aim of this issue is to gather specialists from these fields towards a cross-fertilization among these active areas of research and thereby to present an overview of the state of art in the formation and the characterization of dissipative localized structures. Nonlinear optics and laser physics have an important part in this issue because of potential applications in information technology. In particular, localized structures could be used as "bits" for parallel information storage and processing.
Solving Lattice QCD systems of equations using mixed precision solvers on GPUs
Clark, M A; Barros, K; Brower, R C; Rebbi, C
2009-01-01
Modern graphics hardware is designed for highly parallel numerical tasks and promises significant cost and performance benefits for many scientific applications. One such application is lattice quantum chromodyamics (lattice QCD), where the main computational challenge is to efficiently solve the discretized Dirac equation in the presence of an SU(3) gauge field. Using NVIDIA's CUDA platform we have implemented a Wilson-Dirac sparse matrix-vector product that performs at up to 36 Gflops, 135 Gflops and 205 Gflops for double, single and half precision respectively on NVIDIA's GeForce GTX 280 GPU. We have developed a new mixed precision approach for Krylov solvers using reliable updates which allows for full double precision accuracy while using only single or half precision arithmetic for the bulk of the computation. The resulting BiCGstab and CG solvers run in excess of 100 Gflops and, in terms of iterations until convergence, perform better than the usual defect-correction approach for mixed precision.
Tremblay, A.-M. S.; Breton, P.
1984-03-01
The application of exact and approximate position-space renormalization group techniques to the calculation of densities of states for problems with Gaussian generating functions (such as free tight-binding electrons, harmonic vibrations, spin waves, or random walks on Euclidian or 'fractal' lattices) is briefly reviewed. It is also shown that for one-dimensional Gaussian theories with disorder, the approximate recursion relations proposed by Goncalves da Silva and Koiller (GK) are exact for problems formulated on Berker-Ostlund lattices. A generalization of the GK scheme which allows one to calculate the optical zone-center density of states is formulated and then applied to the study of oneand two-mode behavior in mixed diatomic crystals.
An integrated localization system for robots in underground environments
Energy Technology Data Exchange (ETDEWEB)
Xiong, C.H.; Han, D.G.; Xiong, Y.L. [Huazhong University of Science & Technology, Wuhan (China)
2009-07-01
An integrated localization system mainly based on a strap-down inertial measurement unit and a digital compass is designed for exploring and rescuing task in coal mines and tunnels. After a system model was founded, a filtering algorithm combining a wavelet-based pre-filter with unscented Kalman filters was developed for reckoning tracks of robots and localizing it. Based on this research, an integrated localization system for robots in underground environments can be developed to explore some regions and rescue people. Although errors of localization exist, performance of the integrated system should be improved if some sensors and landmarks or maps of tunnels are introduced.
Local distinguishability of quantum states in infinite dimensional systems
Ogata, Y
2005-01-01
We investigate local distinguishability of quantum states by use of the convex analysis about joint numerical range of operators on a Hilbert space. We show that any two orthogonal pure states are distinguishable by local operations and classical communications, even for infinite dimensional systems. An estimate of the local discrimination probability is also given for some family of more than two pure states.
Membrane indentation triggers clathrin lattice reorganization and fluidization.
Cordella, Nicholas; Lampo, Thomas J; Melosh, Nicholas; Spakowitz, Andrew J
2015-01-21
Clathrin-mediated endocytosis involves the coordinated assembly of clathrin cages around membrane indentations, necessitating fluid-like reorganization followed by solid-like stabilization. This apparent duality in clathrin's in vivo behavior provides some indication that the physical interactions between clathrin triskelia and the membrane effect a local response that triggers fluid-solid transformations within the clathrin lattice. We develop a computational model to study the response of clathrin protein lattices to spherical deformations of the underlying flexible membrane. These deformations are similar to the shapes assumed during intracellular trafficking of nanoparticles. Through Monte Carlo simulations of clathrin-on-membrane systems, we observe that these membrane indentations give rise to a greater than normal defect density within the overlaid clathrin lattice. In many cases, the bulk surrounding lattice remains in a crystalline phase, and the extra defects are localized to the regions of large curvature. This can be explained by the fact that the in-plane elastic stress in the clathrin lattice are reduced by coupling defects to highly curved regions. The presence of defects brought about by indentation can result in the fluidization of a lattice that would otherwise be crystalline, resulting in an indentation-driven, defect-mediated phase transition. Altering subunit elasticity or membrane properties is shown to drive a similar transition, and we present phase diagrams that map out the combined effects of these parameters on clathrin lattice properties.
Kenneth Wilson and lattice QCD
Ukawa, Akira
2015-01-01
We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward b...
Exponential Orthogonality Catastrophe in Single-Particle and Many-Body Localized Systems
Deng, Dong-Ling; Pixley, J. H.; Li, Xiaopeng
We investigate the statistical orthogonality catastrophe (StOC) in single-particle and many-body localized systems by studying the response of the many-body ground state to a local quench. Using scaling arguments and exact numerical calculations, we establish that the StOC gives rise to a wave function overlap between the pre- and post-quench ground states that has an exponential decay with the system size, in sharp contrast to the well-known power law Anderson orthogonality catastrophe in metallic systems. This exponential decay arises from a statistical charge transfer process where a particle can be effectively ``transported'' to an arbitrary lattice site. We show that in a many-body localized phase, this non-local transport and the associated exponential StOC phenomenon persist in the presence of interactions. We study the possible experimental consequences of the exponential StOC on the Loschmidt echo and spectral function, establishing that this phenomenon might be observable in cold atomic experiments through Ramsey interference and radio-frequency spectroscopy. We thank S.-T. Wang, Z.-X. Gong, Y.-L. Wu, J. D. Sau, and Z. Ovadyahu for discussions. This work is supported by LPS-MPO-CMTC, JQI-NSF-PFC, and ARO-Atomtronics-MURI. The authors acknowledge the University of Maryland supercomputing resources.
Chaos and Exponentially Localized Eigenstates in Smooth Hamiltonian Systems
Santhanam, M S; Lakshminarayan, A
1998-01-01
We present numerical evidence to show that the wavefunctions of smooth classically chaotic Hamiltonian systems scarred by certain simple periodic orbits are exponentially localized in the space of unperturbed basis states. The degree of localization, as measured by the information entropy, is shown to be correlated with the local phase space structure around the scarring orbit; indicating sharp localization when the orbit undergoes a pitchfork bifurcation and loses stability.
New design competences for localized production systems
DEFF Research Database (Denmark)
Eriksen, Kaare Riise; Morelli, Nicola
2005-01-01
This paper discusses the current development in production culture, based on local production networks. The role of the designer is put in perspective and outlined through a research project, Den Grønne Møbel (DGM), where different design areas were coordinated in a business concept...... and an organization involving different stakeholders. For several years now, DGM has been producing furniture from local materials, hereby aiming to create a new culture for well designed and environmentally sound furniture with a ‘story’. Although not totally new, this organizational model is particularly innovative...... in fully industrialized countries such as Denmark and represents an interesting alternative to globalized industrial production. Furthermore this case is an interesting opportunity to re-discuss the role and competences of designers in such new models. Tools and methods of the design profession...
Localized Knowledge based System for Human Disease Diagnosis
Directory of Open Access Journals (Sweden)
Adane Nega Tarekegn
2016-03-01
Full Text Available —Knowledge based system can be designed to solve complex medical problems. It incorporates the expert‟s knowledge that has been coded into facts, rules, heuristics and procedures. Incorporation of local languages with the knowledge based system allows endusers communicate with the system in a simpler and easier way. In this study a localized knowledge based system is developed for TB disease diagnosis using Ethiopian national language. To develop the localized knowledge based system, tacit knowledge is acquired from domain experts using interviewing techniques and explicit knowledge is captured from documented sources using relevant documents analysis method. Then the acquired knowledge is modeled using decision tree structure that represents concepts and procedures involved in diagnosis of disease. Production rules are used to represent domain knowledge. The localized knowledge based system is developed using SWI Prolog version 6.4.1 programming language. Prolog supports natural language processing feature to localize the system. As a result, the system is implemented using Amharic language (the national language of Ethiopia user interface. With Localization, users at remote areas and users who are not good in foreign languages are benefited enormously. The system is tested and evaluated to ensure that whether the performance of the system is accurate and the system is usable by physicians and patients. The average performance of the localized knowledge based system has registered 81.5%.
Peierls ground state and excitations in the electron-lattice correlated system (EDO-TTF)2X
Tsuchiizu, M.; Suzumura, Y.
2008-05-01
We investigate the exotic Peierls state in the one-dimensional organic compound (EDO-TTF)2X , wherein the Peierls transition is accompanied by the bending of molecules and also by a fourfold periodic array of charge disproportionation along the one-dimensional chain. Such a Peierls state, wherein the interplay between the electron correlation and the electron-phonon interaction takes an important role, is examined based on an extended Peierls Holstein Hubbard model that includes the alternation of the elastic energies for both the lattice distortion and the molecular deformation. The model reproduces the experimentally observed pattern of the charge disproportionation and there exists a metastable state wherein the energy takes a local minimum with respect to the lattice distortion and/or molecular deformation. Furthermore, we investigate the excited states for both the Peierls ground state and the metastable state by considering the soliton formation of electrons. It is shown that the soliton excitation from the metastable state costs energy that is much smaller than that of the Peierls state, where the former is followed only by the charge degree of freedom and the latter is followed by that of spin and charge. Based on these results, we discuss the exotic photoinduced phase found in (EDO-TTF)2PF6 .
DEFF Research Database (Denmark)
Fajstrup, Lisbeth
The set of d-structures on a topological space form a lattice and in fact a locale. There is a Galois connection between the lattice of subsets of the space and the lattice of d-structures. Variation of the d-structures induces change in the spaces of directed paths. Hence variation of d...
Automated Bilingual Circulation System Using PC Local Area Networks.
Iskanderani, A. I.; Anwar, M. A.
1992-01-01
Describes a local automated bilingual circulation system using personal computers in a local area network that was developed at King Abdulaziz University (Saudi Arabia) for Arabic and English materials. Topics addressed include the system structure, hardware, major features, storage requirements, and costs. (nine references) (LRW)
Minimality of hyperplane arrangements and basis of local system cohomology
Yoshinaga, Masahiko
2010-01-01
The purpose of this paper is applying minimality of hyperplane arrangements to local system cohomology groups. It is well known that twisted cohomology groups with coefficients in a generic rank one local system vanish except in the top degree, and bounded chambers form a basis of the remaining cohomology group. We determine precisely when this phenomenon happens for two dimensional arrangements.
USER-ORIENTED INFORMATION SYSTEMS FOR STATE AND LOCAL GOVERNMENT
Potential state and local government users of information systems are classified in terms of categories of activities and levels of organizational...situation in state and local government information systems is then described, indicating a need for more advanced, user-oriented techniques. Such methods and
Developing Local Career Information Systems for Middle and Secondary Schools.
Campbell, Hartley B.; King, Catherine C.
This guidance support systems handbook was designed to assist local, regional, or State guidance personnel who wish to develop locally-relevant career information materials. These materials may serve as a career information system or may be used to supplement commercial materials which are national in scope. Sections of the handbook cover…
Finding local order in cellular systems
Schneck, Emanuel; Wagermaier, Wolfgang
2017-01-01
Specific local arrangements of molecules are the structural fingerprints of important biological processes in cells and tissues but difficult to access experimentally. In the recent work by Bernhardt et al (2017 New J. Phys. 19 013012) such order on the nanometer scale has been investigated by in situ correlation of fluorescence-based cell visualization and nano-focused x-ray diffraction. This approach enables selective diffraction analysis guided by fluorescence imaging and opens new perspectives for the investigation of ordered nanostructures in living matter such as fiber bundles, membrane architectures, and newly-formed biominerals.
Fractal properties of the lattice Lotka-Volterra model.
Tsekouras, G A; Provata, A
2002-01-01
The lattice Lotka-Volterra (LLV) model is studied using mean-field analysis and Monte Carlo simulations. While the mean-field phase portrait consists of a center surrounded by an infinity of closed trajectories, when the process is restricted to a two-dimensional (2D) square lattice, local inhomogeneities/fluctuations appear. Spontaneous local clustering is observed on lattice and homogeneous initial distributions turn into clustered structures. Reactions take place only at the interfaces between different species and the borders adopt locally fractal structure. Intercluster surface reactions are responsible for the formation of local fluctuations of the species concentrations. The box-counting fractal dimension of the LLV dynamics on a 2D support is found to depend on the reaction constants while the upper bound of fractality determines the size of the local oscillators. Lacunarity analysis is used to determine the degree of clustering of homologous species. Besides the spontaneous clustering that takes place on a regular 2D lattice, the effects of fractal supports on the dynamics of the LLV are studied. For supports of dimensionality D(s)<2 the lattice can, for certain domains of the reaction constants, adopt a poisoned state where only one of the species survives. By appropriately selecting the fractal dimension of the substrate, it is possible to direct the system into a poisoned or oscillatory steady state at will.
Embedded Lattice and Properties of Gram Matrix
Directory of Open Access Journals (Sweden)
Futa Yuichi
2017-03-01
Full Text Available In this article, we formalize in Mizar [14] the definition of embedding of lattice and its properties. We formally define an inner product on an embedded module. We also formalize properties of Gram matrix. We formally prove that an inverse of Gram matrix for a rational lattice exists. Lattice of Z-module is necessary for lattice problems, LLL (Lenstra, Lenstra and Lov´asz base reduction algorithm [16] and cryptographic systems with lattice [17].
The Correlated Kondo-lattice Model
Kienert, J.; Santos, C.; Nolting, W.
2003-01-01
We investigate the ferromagnetic Kondo-lattice model (FKLM) with a correlated conduction band. A moment conserving approach is proposed to determine the electronic self-energy. Mapping the interaction onto an effective Heisenberg model we calculate the ordering of the localized spin system self-consistently. Quasiparticle densities of states (QDOS) and the Curie temperature are calculated. The band interaction leads to an upper Hubbard peak and modifies the magnetic stability of the FKLM.
Güven, Can; Hinczewski, Michael; Berker, A. Nihat
2011-03-01
The tensor renormalization-group method, developed by Levin and Nave, brings systematic improvability to the position-space renormalization-group method and yields essentially exact results for phase diagrams and entire thermodynamic functions. The method, previously used on systems with no quenched randomness, is extended in this study to systems with quenched randomness. Local magnetizations and correlation functions as a function of spin separation are calculated as tensor products subject to renormalization-group transformation. Phase diagrams are extracted from the long-distance behavior of the correlation functions. The approach is illustrated with the quenched bond-diluted Ising model on the triangular lattice. An accurate phase diagram is obtained in temperature and bond-dilution probability for the entire temperature range down to the percolation threshold at zero temperature. This research was supported by the Alexander von Humboldt Foundation, the Scientific and Technological Research Council of Turkey (TÜBITAK), and the Academy of Sciences of Turkey.
Güven, Can; Hinczewski, Michael; Berker, A Nihat
2010-11-01
The tensor renormalization-group method, developed by Levin and Nave, brings systematic improvability to the position-space renormalization-group method and yields essentially exact results for phase diagrams and entire thermodynamic functions. The method, previously used on systems with no quenched randomness, is extended in this study to systems with quenched randomness. Local magnetizations and correlation functions as a function of spin separation are calculated as tensor products subject to renormalization-group transformation. Phase diagrams are extracted from the long-distance behavior of the correlation functions. The approach is illustrated with the quenched bond-diluted Ising model on the triangular lattice. An accurate phase diagram is obtained in temperature and bond-dilution probability for the entire temperature range down to the percolation threshold at zero temperature.
Donnellan, Thomas; Maxwell, E A; Plumpton, C
1968-01-01
Lattice Theory presents an elementary account of a significant branch of contemporary mathematics concerning lattice theory. This book discusses the unusual features, which include the presentation and exploitation of partitions of a finite set. Organized into six chapters, this book begins with an overview of the concept of several topics, including sets in general, the relations and operations, the relation of equivalence, and the relation of congruence. This text then defines the relation of partial order and then partially ordered sets, including chains. Other chapters examine the properti
Local Observability of Systems on Time Scales
Directory of Open Access Journals (Sweden)
Zbigniew Bartosiewicz
2013-01-01
unified way using the language of real analytic geometry, ideals of germs of analytic functions, and their real radicals. It is shown that some properties related to observability are preserved under various discretizations of continuous-time systems.
Analysis of the crystal lattice instability for cage–cluster systems using the superatom model
Energy Technology Data Exchange (ETDEWEB)
Serebrennikov, D. A., E-mail: dserebrennikov@innopark.kantiana.ru, E-mail: dimafania@mail.ru; Clementyev, E. S. [I. Kant Baltic Federal University, “Functional Nanomaterials” Scientific–Educational Center (Russian Federation); Alekseev, P. A. [“Kurchatov Institute” National Research Center (Russian Federation)
2016-09-15
We have investigated the lattice dynamics for a number of rare-earth hexaborides based on the superatom model within which the boron octahedron is substituted by one superatom with a mass equal to the mass of six boron atoms. Phenomenological models have been constructed for the acoustic and lowenergy optical phonon modes in RB{sub 6} (R = La, Gd, Tb, Dy) compounds. Using DyB{sub 6} as an example, we have studied the anomalous softening of longitudinal acoustic phonons in several crystallographic directions, an effect that is also typical of GdB{sub 6} and TbB{sub 6}. The softening of the acoustic branches is shown to be achieved through the introduction of negative interatomic force constants between rare-earth ions. We discuss the structural instability of hexaborides based on 4f elements, the role of valence instability in the lattice dynamics, and the influence of the number of f electrons on the degree of softening of phonon modes.
Extreme lattices: symmetries and decorrelation
Andreanov, A.; Scardicchio, A.; Torquato, S.
2016-11-01
We study statistical and structural properties of extreme lattices, which are the local minima in the density landscape of lattice sphere packings in d-dimensional Euclidean space {{{R}}d} . Specifically, we ascertain statistics of the densities and kissing numbers as well as the numbers of distinct symmetries of the packings for dimensions 8 through 13 using the stochastic Voronoi algorithm. The extreme lattices in a fixed dimension of space d (d≥slant 8 ) are dominated by typical lattices that have similar packing properties, such as packing densities and kissing numbers, while the best and the worst packers are in the long tails of the distribution of the extreme lattices. We also study the validity of the recently proposed decorrelation principle, which has important implications for sphere packings in general. The degree to which extreme-lattice packings decorrelate as well as how decorrelation is related to the packing density and symmetry of the lattices as the space dimension increases is also investigated. We find that the extreme lattices decorrelate with increasing dimension, while the least symmetric lattices decorrelate faster.
LOCAL ANAESTHETIC SYSTEMIC TOXICITY: CURRENT CONCEPTS AND MANAGEMENT
Directory of Open Access Journals (Sweden)
Lakshmi
2014-03-01
Full Text Available Local anesthetics are one of the most commonly used drugs in the field of medicine. Local anesthetics are widely used to induce anesthesia and analgesia for surgical procedures and pain management. Local an aesthetic systemic toxicity (LAST is a rare but potentially fatal complication of regional anesthesia and has been recognized and reported since the late1800s. This narrative review summarizes the pharmacology of local anesthetics, clinical manifestations of systemic toxicity associated with these agents, necessary preventive measures and recent treatment strategies
Masrour, R.; Jabar, A.
2016-07-01
Mixed-spin-1 and spin-3/2 Ising model on the decorated triangular lattice is studied by the use of Monte Carlo simulation. Within this approach, the results for the ground-state of the antiferromagnetic and ferromagnetic of decorated triangular lattice are obtained. The reduced transition temperature of each sublattice are obtained. The reduced temperature of compensation is also obtained. The thermal total ratio of magnetic susceptibilities of sublattices is given. The effect of crystal field and exchange interactions on the magnetization of the system are detailed. The magnetic hysteresis cycles are found for different values of exchanges interactions between the same lattice and the two sublattices different, for different crystal filed and temperatures. In addition, very weak exchange interactions and for a higher temperatures and a higher crystal filed values the decorated triangular lattice has been exhibited the superparamagnetic behavior.
Recent Advances in Wireless Indoor Localization Techniques and System
Directory of Open Access Journals (Sweden)
Zahid Farid
2013-01-01
Full Text Available The advances in localization based technologies and the increasing importance of ubiquitous computing and context-dependent information have led to a growing business interest in location-based applications and services. Today, most application requirements are locating or real-time tracking of physical belongings inside buildings accurately; thus, the demand for indoor localization services has become a key prerequisite in some markets. Moreover, indoor localization technologies address the inadequacy of global positioning system inside a closed environment, like buildings. Based on this, though, this paper aims to provide the reader with a review of the recent advances in wireless indoor localization techniques and system to deliver a better understanding of state-of-the-art technologies and motivate new research efforts in this promising field. For this purpose, existing wireless localization position system and location estimation schemes are reviewed, as we also compare the related techniques and systems along with a conclusion and future trends.
AROMA: Automatic Generation of Radio Maps for Localization Systems
Eleryan, Ahmed; Youssef, Moustafa
2010-01-01
WLAN localization has become an active research field recently. Due to the wide WLAN deployment, WLAN localization provides ubiquitous coverage and adds to the value of the wireless network by providing the location of its users without using any additional hardware. However, WLAN localization systems usually require constructing a radio map, which is a major barrier of WLAN localization systems' deployment. The radio map stores information about the signal strength from different signal strength streams at selected locations in the site of interest. Typical construction of a radio map involves measurements and calibrations making it a tedious and time-consuming operation. In this paper, we present the AROMA system that automatically constructs accurate active and passive radio maps for both device-based and device-free WLAN localization systems. AROMA has three main goals: high accuracy, low computational requirements, and minimum user overhead. To achieve high accuracy, AROMA uses 3D ray tracing enhanced wi...
A Three-Dimensional Wireless Indoor Localization System
Directory of Open Access Journals (Sweden)
Ping Yi
2014-01-01
Full Text Available Indoor localization, an emerging technology in location based service (LBS, is now playing a more and more important role both in commercial and in civilian industry. Global position system (GPS is the most popular solution in outdoor localization field, and the accuracy is around 10 meter error in positioning. However, with complex obstacles in buildings, problems rise in the “last mile” of localization field, which encourage a momentum of indoor localization. The traditional indoor localization system is either range-based or fingerprinting-based, which requires a lot of time and efforts to do the predeployment. In this paper, we present a 3-dimensional on-demand indoor localization system (3D-ODIL, which can be fingerprint-free and deployed rapidly in a multistorey building. The 3D-ODIL consists of two phases, vertical localization and horizontal localization. On vertical direction, we propose multistorey differential (MSD algorithm and implement it to fulfill the vertical localization, which can greatly reduce the number of anchors deployed. We use enhanced field division (EFD algorithm to conduct the horizontal localization. EFD algorithm is a range-free algorithm, the main idea of which is to dynamically divide the field within different signature area and position the target. The accuracy and performance have been validated through our extensive analysis and systematic experiments.
Directory of Open Access Journals (Sweden)
Fuchun Ren
2015-01-01
Full Text Available Risk and resilience are important and challenging issues in complex network systems since a single failure may trigger a whole collapse of the systems due to cascading effect. New theories, models, and methods are urgently demanded to deal with this challenge. In this paper, a coupled map lattices (CML based approach is adopted to analyze the risk of cascading process in Watts-Strogatz (WS small-world network and Barabási and Albert (BA scale-free network, respectively. Then, to achieve an effective and robust system and provide guidance in countering the cascading failure, a modified CML model with recovery strategy factor is proposed. Numerical simulations are put forward based on small-world CML and scale-free CML. The simulation results reveal that appropriate recovery strategies would significantly improve the resilience of networks.
Localization of Compact Invariant Sets of the Lorenz'1984 System
Directory of Open Access Journals (Sweden)
Kh. M. Ramazanova
2015-01-01
Full Text Available Localization of compact invariant sets of a dynamical system is one way to conduct a qualitative analysis of dynamical system. The localization task is aimed at evaluating the location of invariant compact sets of systems, which are equilibrium, periodic trajectories, attractors and repellers, and invariant tori. Such sets and their properties largely determine the structure of the phase portrait of the system. For this purpose, one can use a localization set, i.e. a set in the phase space of the system that contains all invariant compact sets.This article considers the problem of localization of invariant compact sets of an Autonomous version of the Lorenz-84 system. The system represents a simple model of the General circulation of the atmosphere in middle latitudes. The model was used in various climatological studies. To build localization set of the system the so-called functional localization method is applied. The article describes the main provisions of this method, lists the main properties of the localization sets. The simplest version of the Lorenz-84 system when there are no thermal loads is analyzed, and a common variant of the Autonomous Lorenz-84 system, in which for some values of system parameters chaotic dynamics occurs is investigated. In the first case it is shown that the only invariant compact set of the system is its equilibrium position, and localization function turned out to be a Lyapunov function of the system. For the General version of the system a family of localization sets is built and the intersection of this family is described. Graphical illustration for the localization set at fixed values of the parameters is shown. The result of the study partially overlaps with the result of K.E. Starkov on the subject, but provides additional information.The theme of localization of invariant compact sets is discussed quite actively in the literature. Research focuses both on the development of the method and its
Object Management in Local Distributed Systems
1985-11-01
Theory, Vol. 2, Jack Minker et a.l. editors, Plenum Press, New York, IQ84. / A3/ Gottlob , G., P. Paolini, and R. Zicari, "Properties and Update Semantics...February 1980. /D3/ Enslow, P., "What is a ’distributed’ data processing system?" IEEE Computer, 11, 1, January 1978. /D4/ Gottlob , G. and R. Zicari
Seed regulations and local seed systems
Louwaars, N.
2000-01-01
Seed regulations have been introduced in most countries based on the development of formal seed production. Concerns about seed quality and about the varietal identity of the seeds have commonly led to seed laws. However, formal regulations are often inappropriate for informal seed systems, which
Localization in disordered systems with interactions
Indian Academy of Sciences (India)
Angus MacKinnon
2008-02-01
We present an improved numerical approach to the study of disorder and interactions in quasi-1D systems which combines aspects of the transfer matrix method and the density matrix renormalization group which have been successfully applied to disorder and interacting problems respectively. The method is applied to spinless fermions in 1D and a generalization to finite cross-sections is outlined.
Topological states in engineered atomic lattices
Drost, Robert; Ojanen, Teemu; Harju, Ari; Liljeroth, Peter
2017-07-01
Topological materials exhibit protected edge modes that have been proposed for applications in, for example, spintronics and quantum computation. Although a number of such systems exist, it would be desirable to be able to test theoretical proposals in an artificial system that allows precise control over the key parameters of the model. The essential physics of several topological systems can be captured by tight-binding models, which can also be implemented in artificial lattices. Here, we show that this method can be realized in a vacancy lattice in a chlorine monolayer on a Cu(100) surface. We use low-temperature scanning tunnelling microscopy (STM) to fabricate such lattices with atomic precision and probe the resulting local density of states (LDOS) with scanning tunnelling spectroscopy (STS). We create analogues of two tight-binding models of fundamental importance: the polyacetylene (dimer) chain with topological domain-wall states, and the Lieb lattice with a flat electron band. These results provide an important step forward in the ongoing effort to realize designer quantum materials with tailored properties.
Roberts, Daniel A; Susskind, Leonard
2014-01-01
We study products of precursors of spatially local operators, $W_{x_{n}}(t_{n}) ... W_{x_1}(t_1)$, where $W_x(t) = e^{-iHt} W_x e^{iHt}$. Using chaotic spin-chain numerics and gauge/gravity duality, we show that a single precursor fills a spatial region that grows linearly in $t$. In a lattice system, products of such operators can be represented using tensor networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges supported by localized shock waves. We find a geometrical correspondence between these two descriptions, generalizing earlier work in the spatially homogeneous case.
kmos: A lattice kinetic Monte Carlo framework
Hoffmann, Max J.; Matera, Sebastian; Reuter, Karsten
2014-07-01
Kinetic Monte Carlo (kMC) simulations have emerged as a key tool for microkinetic modeling in heterogeneous catalysis and other materials applications. Systems, where site-specificity of all elementary reactions allows a mapping onto a lattice of discrete active sites, can be addressed within the particularly efficient lattice kMC approach. To this end we describe the versatile kmos software package, which offers a most user-friendly implementation, execution, and evaluation of lattice kMC models of arbitrary complexity in one- to three-dimensional lattice systems, involving multiple active sites in periodic or aperiodic arrangements, as well as site-resolved pairwise and higher-order lateral interactions. Conceptually, kmos achieves a maximum runtime performance which is essentially independent of lattice size by generating code for the efficiency-determining local update of available events that is optimized for a defined kMC model. For this model definition and the control of all runtime and evaluation aspects kmos offers a high-level application programming interface. Usage proceeds interactively, via scripts, or a graphical user interface, which visualizes the model geometry, the lattice occupations and rates of selected elementary reactions, while allowing on-the-fly changes of simulation parameters. We demonstrate the performance and scaling of kmos with the application to kMC models for surface catalytic processes, where for given operation conditions (temperature and partial pressures of all reactants) central simulation outcomes are catalytic activity and selectivities, surface composition, and mechanistic insight into the occurrence of individual elementary processes in the reaction network.
Local positioning systems in (game) sports.
Leser, Roland; Baca, Arnold; Ogris, Georg
2011-01-01
Position data of players and athletes are widely used in sports performance analysis for measuring the amounts of physical activities as well as for tactical assessments in game sports. However, positioning sensing systems are applied in sports as tools to gain objective information of sports behavior rather than as components of intelligent spaces (IS). The paper outlines the idea of IS for the sports context with special focus to game sports and how intelligent sports feedback systems can benefit from IS. Henceforth, the most common location sensing techniques used in sports and their practical application are reviewed, as location is among the most important enabling techniques for IS. Furthermore, the article exemplifies the idea of IS in sports on two applications.
Local Positioning Systems in (Game Sports
Directory of Open Access Journals (Sweden)
Roland Leser
2011-10-01
Full Text Available Position data of players and athletes are widely used in sports performance analysis for measuring the amounts of physical activities as well as for tactical assessments in game sports. However, positioning sensing systems are applied in sports as tools to gain objective information of sports behavior rather than as components of intelligent spaces (IS. The paper outlines the idea of IS for the sports context with special focus to game sports and how intelligent sports feedback systems can benefit from IS. Henceforth, the most common location sensing techniques used in sports and their practical application are reviewed, as location is among the most important enabling techniques for IS. Furthermore, the article exemplifies the idea of IS in sports on two applications.
Local and systemic effects of unpolymerised monomers
Directory of Open Access Journals (Sweden)
Sulekha Siddharth Gosavi
2010-01-01
Full Text Available Methyl methacrylate (MMA, a widely used monomer in dentistry and medicine has been reported to cause abnormalities or lesions in several organs. Experimental and clinical studies have documented that monomers may cause a wide range of adverse health effects such as irritation to skin, eyes, and mucous membranes, allergic dermatitis, stomatitis, asthma, neuropathy, disturbances of the central nervous system, liver toxicity, and fertility disturbances.
Lattice Boltzmann simulations of incompressible liquid-gas systems on partial wetting surfaces.
Shih, Ching-Hsiang; Wu, Cheng-Long; Chang, Li-Chen; Lin, Chao-An
2011-06-28
A three-dimensional Lattice Boltzmann two-phase model capable of dealing with large liquid and gas density ratios and with a partial wetting surface is introduced. This is based on a high density ratio model combined with a partial wetting boundary method. The predicted three-dimensional droplets at different partial wetting conditions at equilibrium are in good agreement with analytical solutions. Despite the large density ratio, the spurious velocity around the interface is not substantial, and is rather insensitive to the examined liquid and gas density and viscosity ratios. The influence of the gravitational force on the droplet shape is also examined through the variations of the Bond number, where the droplet shape migrates from spherical to flattened interface in tandem with the increase of the Bond number. The predicted interfaces under constant Bond number are also validated against measurements with good agreements.
High Power Spark Delivery System Using Hollow Core Kagome Lattice Fibers
Directory of Open Access Journals (Sweden)
Ciprian Dumitrache
2014-08-01
Full Text Available This study examines the use of the recently developed hollow core kagome lattice fibers for delivery of high power laser pulses. Compared to other photonic crystal fibers (PCFs, the hollow core kagome fibers have larger core diameter (~50 µm, which allows for higher energy coupling in the fiber while also maintaining high beam quality at the output (M2 = 1.25. We have conducted a study of the maximum deliverable energy versus laser pulse duration using a Nd:YAG laser at 1064 nm. Pulse energies as high as 30 mJ were transmitted for 30 ns pulse durations. This represents, to our knowledge; the highest laser pulse energy delivered using PCFs. Two fiber damage mechanisms were identified as damage at the fiber input and damage within the bulk of the fiber. Finally, we have demonstrated fiber delivered laser ignition on a single-cylinder gasoline direct injection engine.
Electron-Lattice Systems in Weak Gravitation: The Schiff Dessler Problem
Datta, Timir; Yin, Ming
2009-01-01
The behavior of composite matter in external fields can be very reveling. The quantum mechanical problem of a material object (test mass) placed in a uniform (weak) gravitational field, g, was considered by many authors starting with Schiff [Phys. Rev. 151, 1067 (1966)]. Depending on the theoretical treatment opposing results of gravity induced (electric) field have been reported. In the Schiff model [L.I. Schiff, PRB, 1, 4649 (1970)] the field is predicted to be oriented anti-parallel (with reference to g). On the other hand it is found to be parallel in the elastic lattice model [A. J. Dessler et al, Phys.Rev, 168, 737, (1968); Edward Teller, PNAS, 74, 2664 (1977)]. Surprisingly, modern researchers have largely overlooked this interesting contradiction. Here an experimental test is suggested. We also reason that advanced density functional type calculations can provide valuable guidance.
Noise-Induced Subdiffusion in Strongly Localized Quantum Systems
Gopalakrishnan, Sarang; Islam, K. Ranjibul; Knap, Michael
2017-07-01
We consider the dynamics of strongly localized systems subject to dephasing noise with arbitrary correlation time. Although noise inevitably induces delocalization, transport in the noise-induced delocalized phase is subdiffusive in a parametrically large intermediate-time window. We argue for this intermediate-time subdiffusive regime both analytically and using numerical simulations on single-particle localized systems. Furthermore, we show that normal diffusion is restored in the long-time limit, through processes analogous to variable-range hopping. With numerical simulations based on Lanczos exact diagonalization, we demonstrate that our qualitative conclusions are also valid for interacting systems in the many-body localized phase.
A simple method to construct Flat Band lattices
Morales-Inostroza, Luis
2016-01-01
We develop a simple and general method to construct arbitrary Flat Band lattices. We identify the basic ingredients behind zero-dispersion bands and develop a method to construct extended lattices based on a consecutive repetition of a given mini-array. The number of degenerated localized states is defined by the number of connected mini-arrays times the number of modes preserving the symmetry at a given connector site. In this way, we create one or more (depending on the lattice geometry) complete degenerated Flat Bands for quasi-one and two-dimensional systems. We probe our method by studying several examples, and discuss the effect of additional interactions like anisotropy or nonlinearity. At the end, we test our method by studying numerically a ribbon lattice using a continuous description.
A Systems-Theoretical Generalization of Non-Local Correlations
von Stillfried, Nikolaus
Non-local correlations between quantum events are not due to a causal interaction in the sense of one being the cause for the other. In principle, the correlated events can thus occur simultaneously. Generalized Quantum Theory (GQT) formalizes the idea that non-local phenomena are not exclusive to quantum mechanics, e.g. due to some specific properties of (sub)atomic particles, but that they instead arise as a consequence of the way such particles are arranged into systems. Non-local phenomena should hence occur in any system which fulfils the necessary systems-theoretical parameters. The two most important parameters with respect to non-local correlations seem to be a conserved global property of the system as a whole and sufficient degrees of freedom of the corresponding property of its subsystems. Both factors place severe limitations on experimental observability of the phenomena, especially in terms of replicability. It has been suggested that reported phenomena of a so-called synchronistic, parapsychological or paranormal kind could be understood as instances of systems-inherent non-local correlations. From a systems-theoretical perspective, their phenomenology (including the favorable conditions for their occurrence and their lack of replicability) displays substantial similarities to non-local correlations in quantum systems and matches well with systems-theoretical parameters, thus providing circumstantial evidence for this hypothesis.
Semifolded Localized Structures in Three-Dimensional Soliton Systems
Institute of Scientific and Technical Information of China (English)
FANG Jian-Ping; ZHENG Chun-Long; CHEN Li-Qun
2004-01-01
By means ora Painlevé-Backlund transformation and a multi-linear variable separation approach, abundant localized coherent excitations of the three-dimensional Broer-Kaup-Kupershmidt system with variable coefficients are derived. There are possible phase shifts for the interactions of the three-dimensional novel localized structures discussed in this paper.
Semifolded Localized Structures in Three-Dimensional Soliton Systems
Institute of Scientific and Technical Information of China (English)
FANGJian-Ping; ZHENGChun-Long; CHENLi-Qun
2004-01-01
By means ofa Painlev6 Backlund transformation and a multi-linear variable separation approach, abundant localized coherent excitations of the three-dimensional Broer Kaup Kupershmidt system with variable coeft~cients are derived. There are possible phase shifts for the interactions of the three-dimensional novel localized structures discussed in this paper.
Justice Delivered Locally : Systems, Challenges, and Innovations in Solomon Islands
2013-01-01
This report presents the research findings of the Justice Delivered Locally (JDL) initiative of Solomon Islands' Ministry of Justice and Legal Affairs, which was supported by the World Bank's Justice for the Poor (J4P) program. JDL supports the Solomon Islands Government (SIG) policy of reinvigorating local-level justice systems. This is based on an understanding that developmentally impor...
LOCAL EXACT BOUNDARY CONTROLLABILITY FOR A CLASS OFQUASILINEAR HYPERBOLIC SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
For a class of mixed initial-boundary value problem for general quasilinear hyperbolic systems, this paper establishes the local exact boundary controllability with boundary controls only acting on one end. As an application, the authors show the local exact boundary controllability for a kind of nonlinear vibrating string problem.
Ising Model on an Infinite Ladder Lattice
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper we propose an Ising model on an infinite ladder lattice, which is made of two infinite Ising spin chains with interactions. It is essentially a quasi-one-dimessional Ising model because the length of the ladder lattice is infinite, while its width is finite. We investigate the phase transition and dynamic behavior of Ising model on this quasi-one-dimessional system. We use the generalized transfer matrix method to investigate the phase transition of the system. It is found that there is no nonzero temperature phase transition in this system. At the same time, we are interested in Glauber dynamics. Based on that, we obtain the time evolution of the local spin magnetization by exactly solving a set of master equations.
Decay of density waves in coupled one-dimensional many-body-localized systems
Prelovšek, Peter
2016-10-01
This work analyzes the behavior of coupled disordered one-dimensional systems as modelled by identical fermionic Hubbard chains with the on-site potential disorder and coupling emerging through the interchain hopping t'. The study is motivated by the experiment on fermionic cold atoms on a disordered lattice, where a decay rate of the quenched density wave was measured. We present a derivation of the decay rate Γ within perturbation theory and show that, even at large disorder along the chains, the interaction leads to finite Γ >0 , the mechanism being the interaction-induced coupling of in-chain localized and interchain extended single-fermion states. Explicit expressions for Γ are presented for a weak interaction U U >t' . It is shown that, in both regimes, Γ increases with the interchain hopping t', as well as decreases with increasing disorder.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
In this paper, two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM), i.e., the dynamics SGS model and the dynamical system SGS model, and applied to numerically solving three-dimensional high Re turbulent cavity flows. Results are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same cases. It is shown that the method with LBM dynamics SGS model has advantages of fast computation speed, suitable to simulate high Re turbulent flows. In addition, it can capture detailed fine structures of turbulent flow fields. The method with LBM dynamical system SGS model dose not contain any adjustable parameters, and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field, such as the backscatter of energy transportation between large and small scales. A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.
Zhang, Xue-Feng; Eggert, Sebastian
2013-10-01
We consider the extended hard-core Bose-Hubbard model on a kagome lattice with boundary conditions on two edges. We find that the sharp edges lift the degeneracy and freeze the system into a striped order at 1/3 and 2/3 filling for zero hopping. At small hopping strengths, holes spontaneously appear and separate into fractional charges which move to the edges of the system. This leads to a novel edge liquid phase, which is characterized by fractional charges near the edges and a finite edge compressibility but no superfluid density. The compressibility is due to excitations on the edge which display a chiral symmetry breaking that is reminiscent of the quantum Hall effect and topological insulators. Large scale Monte Carlo simulations confirm the analytical considerations.
How Media Systems Shape the Localization of TV Formats
DEFF Research Database (Denmark)
Jensen, Pia Majbritt
2009-01-01
, in this case, television system is understood as the positions (penetration, diversity, concentration) of the different broadcasters and their relations (responsibility, accountability, ownership, funding) with agents such as businesses, politicians, citizens and organizations. Also, any media system must......Variations in local media systems have a high explanation value when it comes to trans-national differences between local adaptations of international formats. On the basis of four case studies of the local adaptations of the formats Ground Force, The Block, Nerds FC and Idol in Denmark...... and Australia, I will give concrete examples of media systemic explanations for some rather significant differences between the adaptations of the two countries, which may kick-start a discussion of what levels of a given local culture have more/most weight in the so-called "glocalisation" processes taking...
380 Work Ethics and Productivity in Local Government System in ...
African Journals Online (AJOL)
User
2012-01-24
Jan 24, 2012 ... absenteeism and dereliction of duty which hinders efficient service delivery ... negative work ethics in the Nigeria local government system which makes .... business, though many reasons have been given by such official ...
Periodically driven ergodic and many-body localized quantum systems
Energy Technology Data Exchange (ETDEWEB)
Ponte, Pedro [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo, ON N2L 3G1 (Canada); Chandran, Anushya [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Papić, Z., E-mail: zpapic@perimeterinstitute.ca [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Institute for Quantum Computing, Waterloo, ON N2L 3G1 (Canada); Abanin, Dmitry A. [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Institute for Quantum Computing, Waterloo, ON N2L 3G1 (Canada)
2015-02-15
We study dynamics of isolated quantum many-body systems whose Hamiltonian is switched between two different operators periodically in time. The eigenvalue problem of the associated Floquet operator maps onto an effective hopping problem. Using the effective model, we establish conditions on the spectral properties of the two Hamiltonians for the system to localize in energy space. We find that ergodic systems always delocalize in energy space and heat up to infinite temperature, for both local and global driving. In contrast, many-body localized systems with quenched disorder remain localized at finite energy. We support our conclusions by numerical simulations of disordered spin chains. We argue that our results hold for general driving protocols, and discuss their experimental implications.
A mobile console for local access to accelerator control systems.
1981-01-01
Microprocessors were installed as auxiliary crate controllers (ACCs) in the CAMAC interface of control systems for various accelerators. The same ACC was also at the hearth of a stand-alone system in the form of a mobile console. This was also used for local access to the control systems for tests and development work (Annual Report 1981, p. 80, Fig. 10).
An expert system for a local planning environment
Meester, G.J.; Meester, G.J.
1993-01-01
In this paper, we discuss the design of an Expert System (ES) that supports decision making in a Local Planning System (LPS) environment. The LPS provides the link between a high level factory planning system (rough cut capacity planning and material coordination) and the actual execution of jobs on
New Fractal Localized Structures in Boiti-Leon-Pempinelli System
Institute of Scientific and Technical Information of China (English)
MAZheng-Yi; ZHUJia-Min; ZHENGChun-Long
2004-01-01
A novel phenomenon that the localized coherent structures of a (2+1)-dimensional physical model possess fractal behaviors is revealed. To clarify the interesting phenomenon, we take the (2+1)-dimensional Boiti Leon-Pempinelli system as a concrete example. Starting from an extended homogeneous balance approach, a general solution of the system is derived. From which some special localized excitations with fractal behaviors are obtained by introducin gsome types of lower-dimensional fractal patterns.
Cluster-based localization and tracking in ubiquitous computing systems
Martínez-de Dios, José Ramiro; Torres-González, Arturo; Ollero, Anibal
2017-01-01
Localization and tracking are key functionalities in ubiquitous computing systems and techniques. In recent years a very high variety of approaches, sensors and techniques for indoor and GPS-denied environments have been developed. This book briefly summarizes the current state of the art in localization and tracking in ubiquitous computing systems focusing on cluster-based schemes. Additionally, existing techniques for measurement integration, node inclusion/exclusion and cluster head selection are also described in this book.
Energy Technology Data Exchange (ETDEWEB)
Mandal, R.; Barman, S.; Saha, S.; Barman, A., E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Otani, Y. [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
2015-08-07
Ferromagnetic antidot lattices are important systems for magnetic data storage and magnonic devices, and understanding their magnetization dynamics by varying their structural parameters is an important problems in magnetism. Here, we investigate the variation in spin wave spectrum in two-dimensional nanoscale Ni{sub 80}Fe{sub 20} antidot lattices with lattice symmetry. By varying the bias magnetic field values in a broadband ferromagnetic resonance spectrometer, we observed a stark variation in the spin wave spectrum with the variation of lattice symmetry. The simulated mode profiles showed further difference in the spatial nature of the modes between different lattices. While for square and rectangular lattices extended modes are observed in addition to standing spin wave modes, all modes in the hexagonal, honeycomb, and octagonal lattices are either localized or standing waves. In addition, the honeycomb and octagonal lattices showed two different types of modes confined within the honeycomb (octagonal) units and between two such consecutive units. Simulated internal magnetic fields confirm the origin of such a wide variation in the frequency and spatial nature of the spin wave modes. The tunability of spin waves with the variation of lattice symmetry is important for the design of future magnetic data storage and magnonic devices.
Localized motion in random matrix decomposition of complex financial systems
Jiang, Xiong-Fei; Zheng, Bo; Ren, Fei; Qiu, Tian
2017-04-01
With the random matrix theory, we decompose the multi-dimensional time series of complex financial systems into a set of orthogonal eigenmode functions, which are classified into the market mode, sector mode, and random mode. In particular, the localized motion generated by the business sectors, plays an important role in financial systems. Both the business sectors and their impact on the stock market are identified from the localized motion. We clarify that the localized motion induces different characteristics of the time correlations for the stock-market index and individual stocks. With a variation of a two-factor model, we reproduce the return-volatility correlations of the eigenmodes.
Lattice-Boltzmann modeling of micromodel experiments representing a CO2-brine system
Energy Technology Data Exchange (ETDEWEB)
Porter, Mark L [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory; Tarimala, Sowmitri [Los Alamos National Laboratory; Abdel - Fattah, Amr I [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory; Carey, James W [Los Alamos National Laboratory
2010-12-21
Successful sequestration of CO{sub 2} into deep saline aquifers presents an enormous challenge that requires fundamental understanding of reactive-multi phase flow and transport across many temporal and spatial scales. Of critical importance is accurately predicting the efficiency of CO{sub 2} trapping mechanisms. At the pore scale (e.g., microns to millimeters) the interfacial area between CO{sub 2} and brine, as well as CO{sub 2} and the solid phase, directly influences the amount of CO{sub 2} trapped due to capillary forces, dissolution and mineral precipitation. In this work, we model immiscible displacement micromodel experiments using the lattice-Boltzmann (LB) method. We focus on quantifying interfacial area as a function of capillary numbers and viscosity ratios typically encountered in CO{sub 2} sequestration operations. We show that the LB model adequately predicts the steady-state experimental flow patterns and interfacial area measurements. Based on the steady-state agreement, we use the LB model to investigate interfacial dynamics (e.g., fluid-fluid interfacial velocity and the rate of production of fluid-fluid interfacial area). In addition, we quantify the amount of interfacial area and the interfacial dynamics associated with the capillary trapped nonwetting phase. This is expected to be important for predicting the amount of nonwetting phase subsequently trapped due to dissolution and mineral precipitation.
Lattice-Boltzmann modeling of micromodel experiments representing a CO2-brine system
Energy Technology Data Exchange (ETDEWEB)
Porter, Mark L [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory; Tarimala, Sowmitri [Los Alamos National Laboratory; Abdel - Fattah, Amr I [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory; Carey, James W [Los Alamos National Laboratory
2010-12-21
Successful sequestration of CO{sub 2} into deep saline aquifers presents an enormous challenge that requires fundamental understanding of reactive-multi phase flow and transport across many temporal and spatial scales. Of critical importance is accurately predicting the efficiency of CO{sub 2} trapping mechanisms. At the pore scale (e.g., microns to millimeters) the interfacial area between CO{sub 2} and brine, as well as CO{sub 2} and the solid phase, directly influences the amount of CO{sub 2} trapped due to capillary forces, dissolution and mineral precipitation. In this work, we model immiscible displacement micromodel experiments using the lattice-Boltzmann (LB) method. We focus on quantifying interfacial area as a function of capillary numbers and viscosity ratios typically encountered in CO{sub 2} sequestration operations. We show that the LB model adequately predicts the steady-state experimental flow patterns and interfacial area measurements. Based on the steady-state agreement, we use the LB model to investigate interfacial dynamics (e.g., fluid-fluid interfacial velocity and the rate of production of fluid-fluid interfacial area). In addition, we quantify the amount of interfacial area and the interfacial dynamics associated with the capillary trapped nonwetting phase. This is expected to be important for predicting the amount of nonwetting phase subsequently trapped due to dissolution and mineral precipitation.
Transport in Sawtooth photonic lattices
Weimann, Steffen; Real, Bastián; Cantillano, Camilo; Szameit, Alexander; Vicencio, Rodrigo A
2016-01-01
We investigate, theoretically and experimentally, a photonic realization of a Sawtooth lattice. This special lattice exhibits two spectral bands, with one of them experiencing a complete collapse to a highly degenerate flat band for a special set of inter-site coupling constants. We report the ob- servation of different transport regimes, including strong transport inhibition due to the appearance of the non-diffractive flat band. Moreover, we excite localized Shockley surfaces states, residing in the gap between the two linear bands.
Implementation of Computer Assisted Test Selection System in Local Governments
Directory of Open Access Journals (Sweden)
Abdul Azis Basri
2016-05-01
Full Text Available As an evaluative way of selection of civil servant system in all government areas, Computer Assisted Test selection system was started to apply in 2013. In phase of implementation for first time in all areas in 2014, this system selection had trouble in several areas, such as registration procedure and passing grade. The main objective of this essay was to describe implementation of new selection system for civil servants in the local governments and to seek level of effectiveness of this selection system. This essay used combination of study literature and field survey which data collection was made by interviews, observations, and documentations from various sources, and to analyze the collected data, this essay used reduction, display data and verification for made the conclusion. The result of this essay showed, despite there a few parts that be problem of this system such as in the registration phase but almost all phases of implementation of CAT selection system in local government areas can be said was working clearly likes in preparation, implementation and result processing phase. And also this system was fulfilled two of three criterias of effectiveness for selection system, they were accuracy and trusty. Therefore, this selection system can be said as an effective way to select new civil servant. As suggestion, local governments have to make prime preparation in all phases of test and make a good feedback as evaluation mechanism and together with central government to seek, fix and improve infrastructures as supporting tool and competency of local residents.
A Malaysian Vehicle License Plate Localization and Recognition System
Directory of Open Access Journals (Sweden)
Ganapathy Velappa
2008-02-01
Full Text Available Technological intelligence is a highly sought after commodity even in traffic-based systems. These intelligent systems do not only help in traffic monitoring but also in commuter safety, law enforcement and commercial applications. In this paper, a license plate localization and recognition system for vehicles in Malaysia is proposed. This system is developed based on digital images and can be easily applied to commercial car park systems for the use of documenting access of parking services, secure usage of parking houses and also to prevent car theft issues. The proposed license plate localization algorithm is based on a combination of morphological processes with a modified Hough Transform approach and the recognition of the license plates is achieved by the implementation of the feed-forward backpropagation artificial neural network. Experimental results show an average of 95% successful license plate localization and recognition in a total of 589 images captured from a complex outdoor environment.
Dawkins, S T; Petersen, M; Millo, J; Magalhães, D V; Mandache, C; Coq, Y Le; Bize, S
2010-01-01
We have developed an ultra-stable source in the deep ultraviolet, suitable to fulfill the interrogation requirements of a future fully-operational lattice clock based on neutral mercury. At the core of the system is a Fabry-P\\'erot cavity which is highly impervious to temperature and vibrational perturbations. The mirror substrate is made of fused silica in order to exploit the comparatively low thermal noise limits associated with this material. By stabilizing the frequency of a 1062.6 nm Yb-doped fiber laser to the cavity, and including an additional link to LNE-SYRTE's fountain primary frequency standards via an optical frequency comb, we produce a signal which is both stable at the 1E-15 level in fractional terms and referenced to primary frequency standards. The signal is subsequently amplified and frequency-doubled twice to produce several milliwatts of interrogation signal at 265.6 nm in the deep ultraviolet.
Energy Technology Data Exchange (ETDEWEB)
Moriarty, K.J.M. (Royal Holloway Coll., Englefield Green (UK). Dept. of Mathematics); Blackshaw, J.E. (Floating Point Systems UK Ltd., Bracknell)
1983-04-01
The computer program calculates the average action per plaquette for SU(6)/Z/sub 6/ lattice gauge theory. By considering quantum field theory on a space-time lattice, the ultraviolet divergences of the theory are regulated through the finite lattice spacing. The continuum theory results can be obtained by a renormalization group procedure. Making use of the FPS Mathematics Library (MATHLIB), we are able to generate an efficient code for the Monte Carlo algorithm for lattice gauge theory calculations which compares favourably with the performance of the CDC 7600.
Development of Citizens’ Political Participation in Local Administration System
Directory of Open Access Journals (Sweden)
Mehmet Akif Çukurçayır
2016-05-01
Full Text Available The foundation of modern local governments in Turkey was laid with an imperial edict in 1839. This reform also called Gulhane Hatt-i Hümayunu or Tanzimat Edict, paved the way for local and regional councils. Since the 1850s, the municipalities have been established. However, it is not possible to talk about the functionality of these municipalities in current terms. Since the proclamation of the Turkish Republic, modern laws regulating local governments were issued. Village Law and Municipal Law are the first examples of these reformations. With the 1961 Constitution, modern participatory local government approach was adopted and mayors began to be elected directly by people for the first time. From 1960 to present, many local government reforms were made, but none of them were so fundamental as in 2012. With this reform, local government system has completely changed. Aim of this study is investigation of results of this reform and find out needs for a new wave of reform. New Metropolitan Municipalities Law is problematic in terms of local governance and local participation. Although European Charter of Local Self-Government and the European Urban Charter paying special importance to citizen’s participation, last developments in Turkey as a European Union candidate continues in the opposite direction. Therefore, it is necessary to discuss all aspects of the new regulation. So that, field researches will be analyzed and recommendations will be presented in the light of these field studies relevant to the reforms.
Energy Technology Data Exchange (ETDEWEB)
Schaefer, Stefan [DESY (Germany). Neumann Inst. for Computing
2016-11-01
These configurations are currently in use in many on-going projects carried out by researchers throughout Europe. In particular this data will serve as an essential input into the computation of the coupling constant of QCD, where some of the simulations are still on-going. But also projects computing the masses of hadrons and investigating their structure are underway as well as activities in the physics of heavy quarks. As this initial project of gauge field generation has been successful, it is worthwhile to extend the currently available ensembles with further points in parameter space. These will allow to further study and control systematic effects like the ones introduced by the finite volume, the non-physical quark masses and the finite lattice spacing. In particular certain compromises have still been made in the region where pion masses and lattice spacing are both small. This is because physical pion masses require larger lattices to keep the effects of the finite volume under control. At light pion masses, a precise control of the continuum extrapolation is therefore difficult, but certainly a main goal of future simulations. To reach this goal, algorithmic developments as well as faster hardware will be needed.
Probing into the local structure of quadrupolar spin systems with MRFM
Verhagen, Rieko; Hilbers, Cees; Kentgens, Arno; van Kempen, Herman
2001-03-01
Magnetic Resonance Force Microscopy is a method to enhance the sensitivity of conventional inductive Nuclear Magnetic Resonance. It combines the advantages of Atomic Force Microscopy with those of NMR, resulting in a method that has both high spatial resolution and sub-surface sensitivity. This gives the capability of 3D imaging and/or spectral characterization of nanoscale structures. We have adapted a conventional MRFM probe to observe nuclei other than protons. The objective of this modification lays in the possibility to observe nuclear spins with spin quantum numbers other than 1/2. In an external magnetic field (Zeeman interaction), these nuclei have multiple spin-transitions with equal energy differences, causing a single spectral line. However, the nuclei have a quadrupole moment and therefore interact with the electrical field gradient caused by charge distributions in the local environment. This shifts the spin energy levels differently so that several transitions occur at different NMR frequencies. The quadrupolar interaction can be used as a probe for obtaining information on the local structure. Since the quadrupolar splitting can be large compared to the spectral resolution of the MRFM detection method it may be imaged using MRFM. We present some methods and first results of MRFM on quadrupolar spin systems, specifically ^23Na (S=3/2) at 4.2T. It is shown that the method is capable of observing the splitting and may obtain local disorders in the lattice structure by scanning the sample.
PT-symmetry and kagome lattices (Conference Presentation)
Saxena, Avadh; Chern, Gia-Wei
2016-09-01
We consider a complex photonic lattice by placing PT-symmetric dimers at the Kagome lattice points. This lattice is a two-dimensional network of corner-sharing triangles. Each dimer represents a pair of strongly coupled waveguides. The frustrated coupling between waveguide modes results in a dispersionless flat band comprising spatially localized modes. For a balanced arrangement of gain and loss on each dimer, up to a critical value of the gain/loss parameter the system exhibits a PT-symmetric phase. The beam evolution in the waveguide array leads to an oscillatory rotation of the optical power. We observe local chiral structures with a narrow beam excitation. We also study nonlinearity and disorder in this set up.
Energy Technology Data Exchange (ETDEWEB)
Guengerich, M.
2007-12-18
This thesis gives an overview of these influences for Ga-V semiconductors (V=P,As,Sb). Lattice vibrations of the ternary alloys Ga(N,P), Ga(N,As) und Ga(N,Sb) are studied and analyzed with respect to the local binding of the N atoms in the host lattices. For the first time, pressure coefficients of the extended host phonons as well as of the N local vibrational modes in Ga(N,As) und Ga(N,P) are determined by Raman spectroscopy under hydrostatic pressure. The relationship between the force constant of the Ga-N bond and the bond length is determined. A central aspect of the thesis is the concentration dependence of optical transitions in Ga(N,P) and Ga(N,As), studied by spectroscopic methods. The impurity levels in both materials are determined by the spatial statistics of the N atoms. (orig.)
Computational methods and destruction of the Fermi liquid in systems of correlated lattice electrons
Tremblay, A.-M. S.
2004-03-01
One of the most striking phenonema observed in the normal state of high-temperature superconductors is the replacement of Landau quasiparticles by a pseudogap in specific regions of the Brillouin zone. It is believed that this phenomenon can be described by the Hubbard Hamiltonian, that models electrons moving on a lattice and interacting through a short-range potential. Because of the theoretical difficulties involved in the solution of the Hubbard model, computational methods have played a key role in proving that the pseudogap phenomenon is indeed a property of the Hubbard model. In so doing, they also allowed physical understanding of the phenomenon. In this talk, the contributions of Cluster Perturbation Theory [1] and auxiliary field Quantum Monte Carlo will be the main focus. At strong coupling, the pseudogap phenomenon will be contrasted with the Mott gap. [2] At weak to intermediate coupling, the importance of antiferromagnetic fluctuations will be demonstrated through a combination of Quantum Monte Carlo and Two-Particle Self-Consistent calculations.[3] More generally, the strengths and limitations of different methods will be discussed along with the role of numerical solutions as benchmarks for non-perturbative approaches. I will also make a few remarks on the Beowulf cluster used for these calculations. Work done in collaboration with D. Sénéchal, B. Kyung and V. Hankevych. [1] D. Sénéchal et al. Phys. Rev. Lett. 84, 522 (2000); Phys. Rev. B 66, 075129 (2002). [2] D. Sénéchal et al. cond-mat/0308625. [3] B. Kyung et al. Phys. Rev. B 68, 174502/1-5 (2003); S. Moukouri, et al. Phys. Rev. B 61, 7887 (2000).
Local Dynamic Reactive Power for Correction of System Voltage Problems
Energy Technology Data Exchange (ETDEWEB)
Kueck, John D [ORNL; Rizy, D Tom [ORNL; Li, Fangxing [ORNL; Xu, Yan [ORNL; Li, Huijuan [University of Tennessee, Knoxville (UTK); Adhikari, Sarina [ORNL; Irminger, Philip [ORNL
2008-12-01
Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results
A Tagless Indoor Localization System Based on Capacitive Sensing Technology
Directory of Open Access Journals (Sweden)
Alireza Ramezani Akhmareh
2016-09-01
Full Text Available Accurate indoor person localization is essential for several services, such as assisted living. We introduce a tagless indoor person localization system based on capacitive sensing and localization algorithms that can determine the location with less than 0.2 m average error in a 3 m × 3 m room and has recall and precision better than 70%. We also discuss the effects of various noise types on the measurements and ways to reduce them using filters suitable for on-sensor implementation to lower communication energy consumption. We also compare the performance of several standard localization algorithms in terms of localization error, recall, precision, and accuracy of detection of the movement trajectory.
Two-dimensional localized structures in harmonically forced oscillatory systems
Ma, Y.-P.; Knobloch, E.
2016-12-01
Two-dimensional spatially localized structures in the complex Ginzburg-Landau equation with 1:1 resonance are studied near the simultaneous presence of a steady front between two spatially homogeneous equilibria and a supercritical Turing bifurcation on one of them. The bifurcation structures of steady circular fronts and localized target patterns are computed in the Turing-stable and Turing-unstable regimes. In particular, localized target patterns grow along the solution branch via ring insertion at the core in a process reminiscent of defect-mediated snaking in one spatial dimension. Stability of axisymmetric solutions on these branches with respect to axisymmetric and nonaxisymmetric perturbations is determined, and parameter regimes with stable axisymmetric oscillons are identified. Direct numerical simulations reveal novel depinning dynamics of localized target patterns in the radial direction, and of circular and planar localized hexagonal patterns in the fully two-dimensional system.
Risteiu, M.; Dobra, R.; Andras, I.; Roventa, M.; Lorincz, A.
2017-06-01
The paper shows the results of a lab model for strain gauges based measuring system for multiple measuring heads of the mechanical stress in lattice structures of the bucket wheel excavator for open pit mines-harsh environment. The system is designed around a microcontroller system. Because of specific working conditions, the measuring system sends data to a processing system (a PC with Matlab software), we have implemented a secure communication solution based on ISM standard, by using NRF24L01 module. The transceiver contains a fully integrated frequency synthesizer based on crystal oscillator, and a Enhanced ShockBurst™ protocol engine. The proposed solution has a current consumption around 9.0 mA at an output power of -6dBm and 12.3mA in RX mode. Built-in Power Down and Standby modes makes power saving easily realizable for our solution battery powered. The stress from structures is taken by specific strain gauges adapted to low frequency vibrations. We are using a precision 24-bit analog-to-digital converter (ADC) designed for weigh scales and industrial control applications to interface directly with a bridge sensor-instrumentation device, with low drift voltage, low noise, common mode rejection signal, frequency and temperature stability. As backup implementation for measurements a high speed storage implementation is used.
General theory of many body localized systems coupled to baths
Nandkishore, Rahul; Gopalakrishnan, Sarang
2016-01-01
We consider what happens when a many body localized system is coupled to a heat bath. Unlike previous works, we do not restrict ourselves to the limit where the bath is large and effectively Markovian, nor to the limit where back action on the bath is negligible. We identify limits where the effect of the bath can be captured by classical noise, and limits where it cannot. We also identify limits in which the bath delocalizes the system, as well as limits in which the system localizes the bat...
Indirect linear locally distributed damping of coupled systems
Directory of Open Access Journals (Sweden)
Annick BEYRATH
2004-11-01
Full Text Available The aim of this paper is to prove indirect internal stabilization results for diﬀerent coupled systems with linear locally distributed damping (coupled wave equations, wave equations with diﬀerent speeds of propagation. In our case, a linear local damping term appears only in the ﬁrst equation whereas no damping term is applied to the second one (this is indirect stabilization, see [11]. Using thepiecewise multiplier method we prove that the full system is stabilized and that the total energy of the solution of this system decays polynomially.
Direction finding antenna system for spark detection and localization
Topor, Raluca E.; Bucuci, Stefania C.; Tamas, Razvan D.; Danisor, Alin; Dumitrascu, Ana; Berescu, Serban
2015-02-01
This paper proposes a novel UWB antenna system for spark detection and localization by using the amplitude comparison direction finding (DF) method. The proposed design consists of two identical axially crossed "padlock" shaped UWB antennas, with unbalanced feeding. Simulation results show that such radiating systems can be used for assessing the direction of arrival for short pulses.
Challenging obduracy : How local communities transform the energy system
Van Der Schoor, Tineke; Van Lente, Harro; Scholtens, Bert; Peine, Alex|info:eu-repo/dai/nl/314407243
2016-01-01
The transformation from the current energy system to a decentralized renewable energy system requires the transformation of communities into energy neutral or even energy producing communities. Increasingly, citizens become 'prosumers' and pool their resources to start a local energy initiative. In
Localized Structures Embedded in the Eigenfunctions of Chaotic Hamiltonian Systems
Vergini, E G
1998-01-01
We study quantum localization phenomena in chaotic systems with a parameter. The parametric motion of energy levels proceeds without crossing any other and the defined avoided crossings quantify the interaction between states. We propose the elimination of avoided crossings as the natural mechanism to uncover localized structures. We describe an efficient method for the elimination of avoided crossings in chaotic billiards and apply it to the stadium billiard. We find many scars of short periodic orbits revealing the skeleton on which quantum mechanics is built. Moreover, we have observed strong interaction between similar localized structures.
Distributed Mobile Robot Localization and Communication System for Special Interventions
Sales Gil, Jorge
2011-01-01
This thesis focuses on the development of a distributed mobile robot localization and communication system for special interventions like those carried out by fire-fighters in fire ground search and rescue. The use case scenario is related to the one described for the GUARDIANS EU project, where a swarm formation of mobile robots accompany a fire fighter during a rescue intervention in a warehouse. In this line, localizing the robots and the fire fighter during an indoor intervention with the...
Governance and Territorial Development. System Actions for Local Authority
Fundación Canadiense para las Américas, (FOCAL)
2003-01-01
This volume presents three papers discussing new models of governance, system abilities and learning within the Territorial Integrated Design (PTI). In particular, the papers analyze: the evolution from Territorial Pacts to Territorial Integrated Pacts; territorial governance and integrated design; and local development and governance. They emphasize those significant innovations concerning these three areas which have proved to be decisive to engender and implement local development projects...
Positioning via Direct Localization in C-RAN Systems
Jeong, Seongah; Simeone, Osvaldo; Haimovich, Alexander; Kang, Joonhyuk
2015-01-01
Cloud Radio Access Network (C-RAN) is a prominent architecture for 5G wireless cellular system that is based on the centralization of baseband processing for multiple distributed radio units (RUs) at a control unit (CU). In this work, it is proposed to leverage the C-RAN architecture to enable the implementation of direct localization of the position of mobile devices from the received signals at distributed RUs. With ideal connections between the CU and the RUs, direct localization is known ...
Entangling gates in even Euclidean lattices such as Leech lattice
Planat, Michel
2010-01-01
We point out a organic relationship between real entangling n-qubit gates of quantum computation and the group of automorphisms of even Euclidean lattices of the corresponding dimension 2n. The type of entanglement that is found in the gates/generators of Aut() depends on the lattice. In particular, we investigate Zn lattices, Barnes-Wall lattices D4, E8, 16 (associated to n = 2, 3 and 4 qubits), and the Leech lattices h24 and 24 (associated to a 3-qubit/qutrit system). Balanced tripartite entanglement is found to be a basic feature of Aut(), a nding that bears out our recent work related to the Weyl group of E8 [1, 2].
System-wide immunohistochemical analysis of protein co-localization.
Directory of Open Access Journals (Sweden)
Minjung Kim
Full Text Available The analysis of co-localized protein expression in a tissue section is often conducted with immunofluorescence histochemical staining which is typically visualized in localized regions. On the other hand, chromogenic immunohistochemical staining, in general, is not suitable for the detection of protein co-localization. Here, we developed a new protocol, based on chromogenic immunohistochemical stain, for system-wide detection of protein co-localization and differential expression.In combination with a removable chromogenic stain, an efficient antibody stripping method was developed to enable sequential immunostaining with different primary antibodies regardless of antibody's host species. Sections were scanned after each staining, and the images were superimposed together for the detection of protein co-localization and differential expression. As a proof of principle, differential expression and co-localization of glutamic acid decarboxylase67 (GAD67 and parvalbumin proteins was examined in mouse cortex.All parvalbumin-containing neurons express GAD67 protein, and GAD67-positive neurons that do not express parvalbumin were readily visualized from thousands of other neurons across mouse cortex. The method provided a global view of protein co-localization as well as differential expression across an entire tissue section. Repeated use of the same section could combine assessments of co-localization and differential expression of multiple proteins.
Elimination of spurious lattice fermion solutions and noncompact lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Lee, T.D.
1997-09-22
It is well known that the Dirac equation on a discrete hyper-cubic lattice in D dimension has 2{sup D} degenerate solutions. The usual method of removing these spurious solutions encounters difficulties with chiral symmetry when the lattice spacing l {ne} 0, as exemplified by the persistent problem of the pion mass. On the other hand, we recall that in any crystal in nature, all the electrons do move in a lattice and satisfy the Dirac equation; yet there is not a single physical result that has ever been entangled with a spurious fermion solution. Therefore it should not be difficult to eliminate these unphysical elements. On a discrete lattice, particle hop from point to point, whereas in a real crystal the lattice structure in embedded in a continuum and electrons move continuously from lattice cell to lattice cell. In a discrete system, the lattice functions are defined only on individual points (or links as in the case of gauge fields). However, in a crystal the electron state vector is represented by the Bloch wave functions which are continuous functions in {rvec {gamma}}, and herein lies one of the essential differences.
Spatiotemporal surface solitons in two-dimensional photonic lattices.
Mihalache, Dumitru; Mazilu, Dumitru; Lederer, Falk; Kivshar, Yuri S
2007-11-01
We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.
Energy Technology Data Exchange (ETDEWEB)
Chulaevsky, Victor, E-mail: victor.tchoulaevski@univ-reims.fr [Universite de Reims, Departement de Mathematiques (France)
2012-12-15
We propose a simplified version of the Multi-Scale Analysis of Anderson models on a lattice and, more generally, on a countable graph with polynomially bounded growth of balls, with diagonal disorder represented by an IID or strongly mixing correlated potential. We apply the new scaling procedure to discrete Schroedinger operators and obtain localization bounds on eigenfunctions and eigenfunction correlators in arbitrarily large finite subsets of the graph which imply the spectral and strong dynamical localization in the entire graph.
Local bifurcation analysis of a four-dimensional hyperchaotic system
Institute of Scientific and Technical Information of China (English)
Wu Wen-Juan; Chen Zeng-Qiang; Yuan Zhu-Zhi
2008-01-01
Local bifurcation phenomena in a four-dimensional continuous hyperchaotic system, which has rich and complex dynamical behaviours, are analysed. The local bifurcations of the system are investigated by utilizing the bifurcation theory and the centre manifold theorem, and thus the conditions of the existence of pitchfork bifurcation and Hopf bifurcation are derived in detail. Numerical simulations are presented to verify the theoretical analysis, and they show some interesting dynamics, including stable periodic orbits emerging from the new fixed points generated by pitchfork bifurcation, coexistence of a stable limit cycle and a chaotic attractor, as well as chaos within quite a wide parameter region.
[Localized bacterial skin infections and dermatologic manifestations of systemic infections].
Zimmerli, W; Itin, P
1992-04-01
Localized bacterial skin infections are frequent. In furunculosis, a local treatment is usually sufficient. In case of frequent recurrence a possible staphylococcus aureus colonization should be looked for and eliminated. Erysipela is treated by systemic antibiotics in order to avoid complications such as streptococcal gangrena or parainfectious glomerulonephritis. Anaerobic cellulitis and gas gangrena are postoperative or posttraumatic infections of the soft tissues which require a combined surgical and antibiotic treatment. Systemic infections may be recognized by characteristic skin lesions. These skin lesions are the consequence of bacterial emboli, vasculitis, intravascular coagulation or toxins, respectively. Examples for such manifestations are lesions in endocarditis, purpura fulminans, ekthyma gangrenosum, disseminated candidemia and toxic shock syndrome.
Bourahla, Boualem; Nafa, Ouahiba
2016-07-01
A model calculation is presented for the coherent magnon transmission and thermal transport at ferromagnetic nanojunction boundaries. The system consists of a Gd ultrathin film sandwiched between two Fe semi-infinite ferromagnetically ordered crystals. The dynamic of the system is analyzed using the equations of motion for the spin precession amplitudes on the lattice sites, valid for the range of temperatures of interest. The coherent transmission and reflection cross sections at the nanojunction boundary are calculated using the matching method. These calculations are presented for arbitrary directions on the boundary, for all accessible frequencies in the propagating bands, at variable temperatures and for a given thicknesses of the ultrathin nanojunction, with no externally applied magnetic field. The model is applied in particular to the Fe/Gd(5)/Fe system with a ferromagnetic Gd nanojunction. Our model yields the total integrated coherent thermal conductivity due to coherent magnons transmission via the sandwiched five Gd spin layers of the nanojunction. It elucidates, in particular, the dependence of the coherent magnons transmission and thermal transport in relation to the spatially inhomogeneous magnetic order of the atomic planes of the nanojunction for a given thickness.
Nonlinear system identification with global and local soft computing methods
Energy Technology Data Exchange (ETDEWEB)
Runkler, T.A. [Siemens AG, Muenchen (Germany). Zentralabt. Technik Information und Kommunikation
2000-10-01
An important step in the design of control systems is system identification. Data driven system identification finds functional models for the system's input output behavior. Regression methods are simple and effective, but may cause overshoots for complicated characteristics. Neural network approaches such as the multilayer perceptron yield very accurate models, but are black box approaches which leads to problems in system and stability analysis. In contrast to these global modeling methods crisp and fuzzy rule bases represent local models that can be extracted from data by clustering methods. Depending on the type and number of models different degrees of model accuracy can be achieved. (orig.)
Globalization and Localization of the Management Control System package
DEFF Research Database (Denmark)
Toldbod, Thomas; Israelsen, Poul
2015-01-01
the organization and others have more particular characteristics. Specifically, this study finds that cybernetic controls and administrative controls are designed as global management control systems. Planning controls and reward and compensation controls are glocal systems. The finding leads to the conclusion......Through an empirical case study, this article examines the operation of multiple management control systems as a package in a Danish manufacturing company. The analysis focuses on four different management control systems – cybernetic controls, planning controls, reward controls, and administrative...... controls – through the theoretical lens of globalization, localization, and glocalization. Based on a single-case study, the analysis documents that these different management control systems are affected differently by the processes of globalization and localization, some of which are universal throughout...
A Robust Crowdsourcing-Based Indoor Localization System.
Zhou, Baoding; Li, Qingquan; Mao, Qingzhou; Tu, Wei
2017-04-14
WiFi fingerprinting-based indoor localization has been widely used due to its simplicity and can be implemented on the smartphones. The major drawback of WiFi fingerprinting is that the radio map construction is very labor-intensive and time-consuming. Another drawback of WiFi fingerprinting is the Received Signal Strength (RSS) variance problem, caused by environmental changes and device diversity. RSS variance severely degrades the localization accuracy. In this paper, we propose a robust crowdsourcing-based indoor localization system (RCILS). RCILS can automatically construct the radio map using crowdsourcing data collected by smartphones. RCILS abstracts the indoor map as the semantics graph in which the edges are the possible user paths and the vertexes are the location where users may take special activities. RCILS extracts the activity sequence contained in the trajectories by activity detection and pedestrian dead-reckoning. Based on the semantics graph and activity sequence, crowdsourcing trajectories can be located and a radio map is constructed based on the localization results. For the RSS variance problem, RCILS uses the trajectory fingerprint model for indoor localization. During online localization, RCILS obtains an RSS sequence and realizes localization by matching the RSS sequence with the radio map. To evaluate RCILS, we apply RCILS in an office building. Experiment results demonstrate the efficiency and robustness of RCILS.
New Delivery Systems for Local Anaesthetics—Part 2
Directory of Open Access Journals (Sweden)
Edward A. Shipton
2012-01-01
Full Text Available Part 2 of this paper deals with the techniques for drug delivery of topical and injectable local anaesthetics. The various routes of local anaesthetic delivery (epidural, peripheral, wound catheters, intra-nasal, intra-vesical, intra-articular, intra-osseous are explored. To enhance transdermal local anaesthetic permeation, additional methods to the use of an eutectic mixture of local anaesthetics and the use of controlled heat can be used. These methods include iontophoresis, electroporation, sonophoresis, and magnetophoresis. The potential clinical uses of topical local anaesthetics are elucidated. Iontophoresis, the active transportation of a drug into the skin using a constant low-voltage direct current is discussed. It is desirable to prolong local anaesthetic blockade by extending its sensory component only. The optimal release and safety of the encapsulated local anaesthetic agents still need to be determined. The use of different delivery systems should provide the clinician with both an extended range and choice in the degree of prolongation of action of each agent.
Localization of pallets in warehouses using passive RFID system
Institute of Scientific and Technical Information of China (English)
周俊儒; 张宏建; 周洪亮
2015-01-01
Warehouse operation has become a critical activity in supply chain. Position information of pallets is important in warehouse management which can enhance the efficiency of pallets picking and sortation. Radio frequency identification (RFID) has been widely used in warehouse for item identifying. Meanwhile, RFID technology also has great potential for pallets localization which is underutilized in warehouse management. RFID-based checking-in and inventory systems have been applied in warehouse management by many enterprises. Localization approach is studied, which is compatible with existing RFID checking-in and inventory systems. A novel RFID localization approach is proposed for pallets checking-in. Phase variation of nearby tags was utilized to estimate the position of added pallets. A novel inventory localization approach combing angle of arrival (AOA) measurement and received signal strength (RSS) is also proposed for pallets inventory. Experiments were carried out using standard UHF passive RFID system. Experimental results show an acceptable localization accuracy which can satisfy the requirement of warehouse management.
New statistical lattice model with double honeycomb symmetry
Naji, S.; Belhaj, A.; Labrim, H.; Bhihi, M.; Benyoussef, A.; El Kenz, A.
2014-04-01
Inspired from the connection between Lie symmetries and two-dimensional materials, we propose a new statistical lattice model based on a double hexagonal structure appearing in the G2 symmetry. We first construct an Ising-1/2 model, with spin values σ = ±1, exhibiting such a symmetry. The corresponding ground state shows the ferromagnetic, the antiferromagnetic, the partial ferrimagnetic and the topological ferrimagnetic phases depending on the exchange couplings. Then, we examine the phase diagrams and the magnetization using the mean field approximation (MFA). Among others, it has been suggested that the present model could be localized between systems involving the triangular and the single hexagonal lattice geometries.
Spin-Lattice Order in One-Dimensional Conductors: Beyond the RKKY Effect
Schecter, Michael; Rudner, Mark S.; Flensberg, Karsten
2015-06-01
We investigate magnetic order in a lattice of classical spins coupled to an isotropic gas of one-dimensional conduction electrons via local exchange interactions. The frequently discussed Ruderman-Kittel-Kasuya-Yosida effective exchange model for this system predicts that spiral order is always preferred. Here we consider the problem nonperturbatively, and find that such order vanishes above a critical value of the exchange coupling that depends strongly on the lattice spacing. The critical coupling tends to zero as the lattice spacing becomes commensurate with the Fermi wave vector, signaling the breakdown of the perturbative Ruderman-Kittel-Kasuya-Yosida picture, and spiral order, even at weak coupling. We provide the exact phase diagram for arbitrary exchange coupling and lattice spacing, and discuss its stability. Our results shed new light on the problem of utilizing a spiral spin-lattice state to drive a one-dimensional superconductor into a topological phase.
Bartmann, W
2009-01-01
The CERN Proton Synchrotron PS2 is one of the foreseen accelerators for the LHC injector upgrade. This upgrade aims first at increasing the instantaneous luminosity of LHC and second at providing a reliable beam for the CERN accelerator complex. From this aspect, the main characteristics of the PS2 are high reliability for high intensity beams. The goal of this thesis was the design of the machine’s lattice and injection/extraction systems meeting the constraints coming mainly from the LHC beam type but also from beam requirements of experiments at PS2 and the SPS. In the design, the given energy range together with filling schemes for different beam types and RF cogging were first used to define the circumference of the machine. Estimates on the space requirements of injection/extraction systems were made in order to divide the total machine length between arc and long straight section. Existing tunnels for transfer lines together with the minimisation of the total transfer line length favoured a race trac...
Locality and the classical limit of quantum systems
Banks, T
2009-01-01
I argue that conventional estimates of the criterion for classical behavior of a macroscopic body are incorrect in most circumstances,because they do not take into account the locality of interactions, which characterizes the behavior of all systems described approximately by local quantum field theory. The deviations from classical behavior of a macroscopic body, except for those that can be described as classical uncertainties in the initial values of macroscopic variables,are {\\it exponentially} small as a function of the volume of the macro-system in microscopic units. Conventional estimates are correct only when the internal degrees of freedom of the macrosystem are in their ground state, and the classical motion of collective coordinates is adiabatic. Otherwise, the system acts as its own environment and washes out quantum phase correlations between different classical states of its collective coordinates. I suggest that it is likely that we can only achieve meso-scopic superpositions, for systems which...
Long term structural dynamics of mechanical systems with local nonlinearities
Fey, R.H.B.; Campen, D.H. van; Kraker, A. de
1996-01-01
This paper deals with the long term behavior of periodically excited mechanical systems consisting of linear components and local nonlinearities. The number of degrees of freedom of the linear components is reduced by applying a component mode synthesis technique. Lyapunov exponents are used to iden
Automated Fault Localization for Service-Oriented Software Systems
Chen, C.
2015-01-01
In this thesis, we have focused on applying Spectrum-based Fault Localization (SFL) to diagnose Service-Oriented Systems at runtime. We reused a framework-based online monitoring technique to obtain the service transaction information. We devised a three-phased oracle and combined this with monitori
A geographic information system for local public health policy
J.A. van Oers (Johannes Anna Maria)
1993-01-01
textabstractThis book deals with the development and use of a geographic information system for local public health policy. Health differences between populations in different geographical areas, large (countries) or small (city-neighbourhoods) have always been a challenge to epidemiologists and pol
Global and local sensitivity analysis methods for a physical system
Energy Technology Data Exchange (ETDEWEB)
Morio, Jerome, E-mail: jerome.morio@onera.fr [Onera-The French Aerospace Lab, F-91761, Palaiseau Cedex (France)
2011-11-15
Sensitivity analysis is the study of how the different input variations of a mathematical model influence the variability of its output. In this paper, we review the principle of global and local sensitivity analyses of a complex black-box system. A simulated case of application is given at the end of this paper to compare both approaches.
Global and Local Sensitivity Analysis Methods for a Physical System
Morio, Jerome
2011-01-01
Sensitivity analysis is the study of how the different input variations of a mathematical model influence the variability of its output. In this paper, we review the principle of global and local sensitivity analyses of a complex black-box system. A simulated case of application is given at the end of this paper to compare both approaches.…
Omnidirectional beacon-localization using a catadioptric system.
Shen, Thomas C; Drost, Robert J; Sadler, Brian M; Rzasa, John R; Davis, Christopher C
2016-04-01
We present a catadioptric beacon localization system that can provide mobile network nodes with omnidirectional situational awareness of neighboring nodes. In this system, a receiver composed of a hyperboloidal mirror and camera is used to estimate the azimuth, elevation, and range of an LED beacon. We provide a general framework for understanding the propagation of error in the angle-of-arrival estimation and then present an experimental realization of such a system. The situational awareness provided by the proposed system can enable the alignment of communication nodes in an optical wireless network, which may be particularly useful in addressing RF-denied environments.
Intruder localization and identification in fiber optic systems
Zyczkowski, M.
2008-10-01
The ultimate goal in all fiber optic systems is to extract information about the mechanical perturbations. For example, this information may be the frequency dependent index of perturbation. For security systems we desire to detect and differentiate between different intruders based on the mechanical response. This article shows experimental investigation of ideal intruder classifier. We considered demodulation, denoising, deconvolution and normalisation. We present additionally possible configuration of fiber optic sensor to localizing perturbation place.
Localization of periodic orbits of polynomial systems by ellipsoidal estimates
Energy Technology Data Exchange (ETDEWEB)
Starkov, Konstantin E. [CITEDI-IPN, Avenue del Parque 1310, Mesa de Otay, Tijuana, BC (Mexico)]. E-mail: konst@citedi.mx; Krishchenko, Alexander P. [Bauman Moscow State Technical University, 2nd Baumanskaya Street, 5, Moscow 105005 (Russian Federation)]. E-mail: apkri@999.ru
2005-02-01
In this paper we study the localization problem of periodic orbits of multidimensional continuous-time systems in the global setting. Our results are based on the solution of the conditional extremum problem and using sign-definite quadratic and quartic forms. As examples, the Rikitake system and the Lamb's equations for a three-mode operating cavity in a laser are considered.
Decentralized Cooperative Localization Approach for Autonomous Multirobot Systems
Directory of Open Access Journals (Sweden)
Thumeera R. Wanasinghe
2016-01-01
Full Text Available This study proposes the use of a split covariance intersection algorithm (Split-CI for decentralized multirobot cooperative localization. In the proposed method, each robot maintains a local cubature Kalman filter to estimate its own pose in a predefined coordinate frame. When a robot receives pose information from neighbouring robots, it employs a Split-CI based approach to fuse this received measurement with its local belief. The computational and communicative complexities of the proposed algorithm increase linearly with the number of robots in the multirobot systems (MRS. The proposed method does not require fully connected synchronous communication channels between robots; in fact, it is applicable for MRS with asynchronous and partially connected communication networks. The pose estimation error of the proposed method is bounded. As the proposed method is capable of handling independent and interdependent information of the estimations separately, it does not generate overconfidence state estimations. The performance of the proposed method is compared with several multirobot localization approaches. The simulation and experiment results demonstrate that the proposed algorithm outperforms the single-robot localization algorithms and achieves approximately the same estimation accuracy as the centralized cooperative localization approach, but with reduced computational and communicative cost.
Random perfect lattices and the sphere packing problem.
Andreanov, A; Scardicchio, A
2012-10-01
Motivated by the search for best lattice sphere packings in Euclidean spaces of large dimensions we study randomly generated perfect lattices in moderately large dimensions (up to d=19 included). Perfect lattices are relevant in the solution of the problem of lattice sphere packing, because the best lattice packing is a perfect lattice and because they can be generated easily. Their number, however, grows superexponentially with the dimension, so to get an idea of their properties we propose to study a randomized version of the generating algorithm and to define a random ensemble with an effective temperature in a way reminiscent of a Monte Carlo simulation. We therefore study the distribution of packing fractions and kissing numbers of these ensembles and show how as the temperature is decreased the best known packers are easily recovered. We find that, even at infinite temperature, the typical perfect lattices are considerably denser than known families (like A(d) and D(d)), and we propose two hypotheses between which we cannot distinguish in this paper: one in which they improve the Minkowsky bound φ~2(-(0.84±0.06)d), and a competitor in which their packing fraction decreases superexponentially, namely, φ~d(-ad) but with a very small coefficient a=0.06±0.04. We also find properties of the random walk which are suggestive of a glassy system already for moderately small dimensions. We also analyze local structure of network of perfect lattices conjecturing that this is a scale-free network in all dimensions with constant scaling exponent 2.6±0.1.
Lattices of dielectric resonators
Trubin, Alexander
2016-01-01
This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas and lattices of d...
Local Food Systems Supported by Communities Nationally and Internationally
Directory of Open Access Journals (Sweden)
Izabella Mária Bakos
2017-06-01
Full Text Available Due to the concerns about the long-term sustainability of globalized retail trade as well as the more and more determining health-conscious food-consuming attitude the systems of government respectively the groups of conscious consumers all over the world put emphasis on the popularization and development of local food chains and small-scale supply chains simultaneously they connect the retailers producing highquality, local foods with the direct markets. In my study, I would like to present an overview of the development and current state of community supported agricultural systems on the international and Hungarian level and on the basis of the results of my questionnaire survey. I will indicate whether there are any demand for local food in Hungary and about how much the population of the six investigated settlements are familiar with it. Within this type of alternative local food systems, farmers and their buyers form a community based on social capital (co-operation, mutual trust and mutual responsibility, a direct sales channel, in such a way that cooperation is also beneficial to the producer and the consumer. The producer is in an advantageous position as he can form a direct and long-term relationship with his consumers selling his high-quality products locally consequently he can work in a cost-effective and optimal way. However, the advantage of the consumer is that he can obtain healthy foods from reliable sources contributing to the maintenance of his health respectively to the development of local economy.
Fourier's law on a one-dimensional optical random lattice
Energy Technology Data Exchange (ETDEWEB)
Platini, T [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Harris, R J [School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom); Karevski, D [Institut Jean Lamour, Departement Physique de la Matiere et des Materiaux, Groupe de Physique Statistique, Nancy-Universite CNRS, BP 70239, F-54506 Vandoeuvre les Nancy Cedex (France)
2010-04-02
We study the transport properties of a one-dimensional hard-core bosonic lattice gas coupled to two particle reservoirs at different chemical potentials which generate a current flow through the system. In particular, the influence of random fluctuations of the underlying lattice on the stationary-state properties is investigated. We show analytically that the steady-state density presents a linear profile. The local steady-state current obeys the Fourier law j = -{kappa}({tau}){nabla}n where {tau} is a typical timescale of the lattice fluctuations and {nabla}n is the density gradient imposed by the reservoirs.
Integration of Science, Local Systems of Innovation and Local Management of Quality of Life
Directory of Open Access Journals (Sweden)
Nelson Arsenio Castro Perdomo
2013-06-01
Full Text Available An explanatory research was conducted in order to analyze the results of adopting the integration of science as a working instrument for managing the quality of life in the municipality of Cumanayagua, in the province of Cienfuegos. The methodological procedures included the Delphi method, the implementation of indicators derived from the Branch Program of the Ministry of Higher Education to assess university management of knowledge and innovation, as well as the correlation among variables, together with the documentary review of the locality. Multivariate statistical methods were conducted for analyzing the data. Thus, we could assess the importance of the local development management through the performance of the sectors or areas resulting from this analysis, which were correlated with the concrete expression of the management of projects aimed at achieving a better quality of life. Consequently, it could be confirmed that the integration of science, technology, innovation and environment management urged by the local system of innovation facilitates the management of quality of life and, in turn, the local govern performance.
Character algebras of decorated SL_2(C)-local systems
Muller, Greg
2011-01-01
Let S be a path-connected, locally-compact CW-complex, and let M be a subcomplex with finitely-many components. A `decorated SL_2(C)-local system' is an SL_2(C)-local system on S, together with a choice of `decoration' at each component of M (a section of the stalk of an associated vector bundle). We study the (decorated SL_2(C)-)character algebra of (S,M), those functions on the space of decorated SL_2(C)-local systems on (S,M) which are regular with respect to the monodromy. The character algebra is presented explicitly. The character algebra is then shown to correspond to the algebra spanned by collections of oriented curves in S modulo simple graphical rules. As an intermediate step, we obtain an invariant-theory result of independent interest: a presentation of the algebra of SL_2(C)-invariant functions on End(V)^m + V^n, where V is the tautological representation of SL_2(C).
Lattice Boltzmann model for nanofluids
Energy Technology Data Exchange (ETDEWEB)
Xuan Yimin; Yao Zhengping [Nanjing University of Science and Technology, School of Power Engineering, Nanjing (China)
2005-01-01
A nanofluid is a particle suspension that consists of base liquids and nanoparticles and has great potential for heat transfer enhancement. By accounting for the external and internal forces acting on the suspended nanoparticles and interactions among the nanoparticles and fluid particles, a lattice Boltzmann model is proposed for simulating flow and energy transport processes inside the nanofluids. First, we briefly introduce the conventional lattice Boltzmann model for multicomponent systems. Then, we discuss the irregular motion of the nanoparticles and inherent dynamic behavior of nanofluids and describe a lattice Boltzmann model for simulating nanofluids. Finally, we conduct some calculations for the distribution of the suspended nanoparticles. (orig.)
Weakly deformed soliton lattices
Energy Technology Data Exchange (ETDEWEB)
Dubrovin, B. (Moskovskij Gosudarstvennyj Univ., Moscow (USSR). Dept. of Mechanics and Mathematics)
1990-12-01
In this lecture the author discusses periodic and quasiperiodic solutions of nonlinear evolution equations of phi{sub t}=K (phi, phi{sub x},..., phi{sup (n)}), the so-called soliton lattices. After introducing the theory of integrable systems of hydrodynamic type he discusses their Hamiltonian formalism, i.e. the theory of Poisson brackets of hydrodynamic type. Then he describes the application of algebraic geometry to the effective integration of such equations. (HSI).
Dynamics of Localized Structures in Systems with Broken Parity Symmetry
Javaloyes, J; Marconi, M; Giudici, M
2016-01-01
A great variety of nonlinear dissipative systems are known to host structures having a correlation range much shorter than the size of the system. The dynamics of these Localized Structures (LSs) have been investigated so far in situations featuring parity symmetry. In this letter we extend this analysis to systems lacking of this property. We show that the LS drifting speed in a parameter varying landscape is not simply proportional to the parameter gradient, as found in parity preserving situations. The symmetry breaking implies a new contribution to the velocity field which is a function of the parameter value, thus leading to a new paradigm for LSs manipulation. We illustrate this general concept by studying the trajectories of the LSs found in a passively mode-locked laser operated in the localization regime. Moreover, the lack of parity affects significantly LSs interactions which are governed by asymmetrical repulsive forces.
Regional Innovation System And Local Economic Development In Indonesia
Directory of Open Access Journals (Sweden)
Adiwan F Aritenang
2013-08-01
Full Text Available In Indonesia, decentralization and globalization has introduced a new spirit for localism. Since decentralisation, regions have been motivated to accelerate economic development through local endowment and resources. The democratic Indonesia government has been interested to follow economy theories and case studies develop in the advance countries. Over the years, government policies have supported and strengthen technology development through industrial clusters and national and regional innovation systems. This research aims to explore current progress of Indonesia innovation system through industrial clusters. The research found the presence of industry clustering and very limited innovation system in Indonesia. The research argues that these activities has significant impact on employment growth, but does not increase the industry's value added.
A quantum many-body spin system in an optical lattice clock
Martin, M J; Swallows, M D; Zhang, X; Benko, C; von-Stecher, J; Gorshkov, A V; Rey, A M; Ye, Jun
2013-01-01
Strongly interacting quantum many-body systems are fundamentally compelling and ubiquitous in science. However, their complexity generally prevents exact solutions of their dynamics. Precisely engineered ultracold atomic gases are emerging as a powerful tool to unravel these challenging physical problems. Here we present a new laboratory for the study of many-body effects: strongly interacting two-level systems formed by the clock states in ${}^{87}$Sr, which are used to realize a neutral atom optical clock that performs at the highest level of optical-atomic coherence and with precision near the limit set by quantum fluctuations. Our measurements of the collective spin evolution reveal signatures of many-body dynamics, including beyond-mean-field effects. We derive a many-body Hamiltonian that describes the experimental observation of severely distorted lineshapes, atomic spin coherence decay, density-dependent frequency shifts, and correlated quantum spin noise. These investigations open the door to explori...
Datta, Nilanjana; Pautrat, Yan; Rouzé, Cambyse
2016-06-01
Quantum Stein's lemma is a cornerstone of quantum statistics and concerns the problem of correctly identifying a quantum state, given the knowledge that it is one of two specific states (ρ or σ). It was originally derived in the asymptotic i.i.d. setting, in which arbitrarily many (say, n) identical copies of the state (ρ⊗n or σ⊗n) are considered to be available. In this setting, the lemma states that, for any given upper bound on the probability αn of erroneously inferring the state to be σ, the probability βn of erroneously inferring the state to be ρ decays exponentially in n, with the rate of decay converging to the relative entropy of the two states. The second order asymptotics for quantum hypothesis testing, which establishes the speed of convergence of this rate of decay to its limiting value, was derived in the i.i.d. setting independently by Tomamichel and Hayashi, and Li. We extend this result to settings beyond i.i.d. Examples of these include Gibbs states of quantum spin systems (with finite-range, translation-invariant interactions) at high temperatures, and quasi-free states of fermionic lattice gases.
Limits of localized control in extended nonlinear systems
Handel, Andreas
We investigate the limits of localized linear control in spatially extended, nonlinear systems. Spatially extended, nonlinear systems can be found in virtually every field of engineering and science. An important category of such systems are fluid flows. Fluid flows play an important role in many commercial applications, for instance in the chemical, pharmaceutical and food-processing industries. Other important fluid flows include air- or water flows around cars, planes or ships. In all these systems, it is highly desirable to control the flow of the respective fluid. For instance control of the air flow around an airplane or car leads to better fuel-economy and reduced noise production. Usually, it is impossible to apply control everywhere. Consider an airplane: It would not be feasibly to cover the whole body of the plane with control units. Instead, one can place the control units at localized regions, such as points along the edge of the wings, spaced as far apart from each other as possible. These considerations lead to an important question: For a given system, what is the minimum number of localized controllers that still ensures successful control? Too few controllers will not achieve control, while using too many leads to unnecessary expenses and wastes resources. To answer this question, we study localized control in a class of model equations. These model equations are good representations of many real fluid flows. Using these equations, we show how one can design localized control that renders the system stable. We study the properties of the control and derive several expressions that allow us to determine the limits of successful control. We show how the number of controllers that are needed for successful control depends on the size and type of the system, as well as the way control is implemented. We find that especially the nonlinearities and the amount of noise present in the system play a crucial role. This analysis allows us to determine under
An active UHF RFID localization system for fawn saving
Eberhardt, M.; Lehner, M.; Ascher, A.; Allwang, M.; Biebl, E. M.
2015-11-01
We present a localization concept for active UHF RFID transponders which enables mowing machine drivers to detect and localize marked fawns. The whole system design and experimental results with transponders located near the ground in random orientations in a meadow area are shown. The communication flow between reader and transponders is realized as a dynamic master-slave concept. Multiple marked fawns will be localized by processing detected transponders sequentially. With an eight-channel-receiver with integrated calibration method one can estimate the direction-of-arrival by measuring the phases of the transponder signals up to a range of 50 m in all directions. For further troubleshooting array manifolds have been measured. An additional hand-held receiver with a two-channel receiver allows a guided approaching search without endangering the fawn by the mowing machine.
Quasi-Many-Body Localization in Translation-Invariant Systems
Yao, N. Y.; Laumann, C. R.; Cirac, J. I.; Lukin, M. D.; Moore, J. E.
2016-12-01
We examine localization phenomena associated with generic, high entropy, states of a translation-invariant, one-dimensional spin ladder. At early times, we find slow growth of entanglement entropy consistent with the known phenomenology of many-body localization in disordered, interacting systems. At intermediate times, however, anomalous diffusion sets in, leading to full spin polarization decay on an exponentially activated time scale. We identify a single length scale which parametrically controls both the spin transport times and the apparent divergence of the susceptibility to spin glass ordering. Ultimately, at the latest times, the exponentially slow anomalous diffusion gives way to diffusive thermal behavior. We dub the intermediate dynamical behavior, which persists over many orders of magnitude in time, quasi-many-body localization.
Boson spectra and correlations for thermal locally equilibrium systems
Sinyukov, Yu M
1999-01-01
The single- and multi- particle inclusive spectra for strongly inhomogeneous thermal boson systems are studied using the method of statistical operator. The thermal Wick's theorem is generalized and the analytical solution of the problem for an boost-invariant expanding boson gas is found. The results demonstrate the effects of inhomogeneity for such a system: the spectra and correlations for particles with wave-lengths larger than the system's homogeneity lengths change essentially as compared with the results based on the local Bose-Einstein thermal distributions. The effects noticeable grow for overpopulated media, where the chemical potential associated with violation of chemical equilibrium is large enough.
Berim, Gersh O.; Ruckenstein, Eli
2003-11-01
A generalized kinetic Ising model is applied to the description of phase transformations in lattice systems. A procedure, based on the conjecture that the probability distribution function of the states of the system is similar to the equilibrium one, is used for closing the infinite chain of kinetic equations. The method is illustrated by treating as an example the one-dimensional Ising model. The predicted rate of phase transformation (RPT) demonstrates various time behaviors dependent upon the details of the interactions between spins and a heat bath. If the parameters W0 and W the reciprocals of which characterize, respectively, the time scales of growth (decay) and splitting (coagulation) of clusters have the same order of magnitude, then the RPT is constant during almost the entire transformation process. For the case W=0, which corresponds to the absence of splitting and coagulation of clusters, the phase transformation follows an exponential law in the final stage and is linear with respect to time during the initial one. It has a similar behavior for W0≫W≠0; however, the RPT in the final stage is much smaller in the last case than for W=0. In the absence of supersaturation, RPT decreases to zero as T→Tc, where Tc(=0 K) is the phase transition temperature for a one-dimensional model. The time-dependent size distribution of clusters is for all times exponential with respect to the cluster size. The average size of the cluster far from both equilibrium and initial state grows linearly in time. Both the above quantities behave in a manner similar to those obtained by Monte Carlo simulations for systems of higher dimension.
Contrasting Ocular Effects of Local versus Systemic Endotoxin
Woods, April; Kezic, Jelena; Planck, Stephen R.; Rosenzweig, Holly L.
2011-01-01
Purpose. A marked cellular infiltrate has been observed when endotoxin (lipopolysaccharide [LPS]) is injected into the mouse eye, but systemically injected LPS does not produce a comparable effect. Several hypotheses were tested to reconcile this discordance. Methods. BALB/c mice were injected intravitreally (ivt) or intraperitoneally (ip) with Escherichia coli LPS. Uveitis was assessed by traditional and intravital microscopy. Cytokine levels in the eye, plasma, or spleen were measured by single or multiplex ELISA assays. Results. The eye's higher sensitivity was confirmed to local LPS exposure, as 250 ng ivt LPS produced a brisk leukocytic infiltrate whereas ip injection of 100 μg LPS did not. The hypothesis was tested that the lack of a cellular infiltrate after ip LPS is explained by less induction of cytokines in the eye, but surprisingly, ip LPS resulted in comparable cytokine levels to ivt LPS. The hypothesis was disproved that the eye's sensitivity to local LPS is due to lack of expression of intracellular inhibitors of LPS such as A20, IRAK-M, or SARM. Finally, the hypothesis that systemic LPS inhibits diapedesis was tested by injection of LPS ip and ivt simultaneously, a strategy that did not significantly reduce leukocyte rolling or sticking in iris vessels but blocked the cellular infiltrate normally seen with ivt LPS. Conclusions. Systemic and local LPS exposures produce discordant effects within the murine eye. The hypothesis that systemic LPS desensitizes leukocytes to the stimuli responsible for transmigration offers a plausible explanation for this discordance. PMID:21757585
Commensal Microbiome Promotes Resistance to Local and Systemic Infections
Institute of Scientific and Technical Information of China (English)
Nan Zhang; Qiu-Shui He
2015-01-01
Objective:In this review,to illustrate the resistance mechanism for pathogen insult,we discussed the role of the intestinal microbiome in promoting resistance to local gastrointestinal tract infections and to respiratory tract infections.Data Sources:The review was based on data obtained from the published research articles.Study Selection:A total of 49 original articles were selected in accordance with our main objective to illustrate the resistance mechanism(s) by which commensal microbiota can contribute to host defense against local and systemic infections.Results:Diverse microorganisms colonize human environmentally exposed surfaces such as skin,respiratory tract,and gastrointestinal tract.Co-evolution has resulted in these microbes with extensive and diverse impacts on multiple aspects of host biological functions.During the last decade,high-throughput sequencing technology developed has been applied to study commensal microbiota and their impact on host biological functions.By using pathogen recognition receptors pathway and nucleotide binding oligomerization domain-like receptors pathway,the commensal microbiome promotes resistance to local and systemic infections,respectively.To protect against the local infections,the microbiome functions contain the following:the competing for sites of colonization,direct production of inhibition molecules or depletion of nutrients needed for pathogens,and priming immune defenses against pathogen insult.At the same time,with the purpose to maintain homeostasis,the commensal bacteria can program systemic signals toward not only local tissue but also distal tissue to modify their function for infections accordingly.Conclusions:Commensal bacteria play an essential role in protecting against infections,shaping and regulating immune responses,and maintaining host immune homeostasis.
Assessing youth policies. A system of indicators for local government.
Planas, Anna; Soler, Pere; Vilà, Montserrat
2014-08-01
In the current European climate of economic, financial and political crisis and the questioning of the welfare state, assessing public policies assume a primary and strategic relevance in clarifying the results and contributions of policy actions. In this article, we aim to present the current situation in relation to youth policy assessment so as to formulate a system of assessment indicators in the sphere of Spanish local government youth policy. A review is conducted of some of the principal contributions in the field of constructing indicators for evaluating youth policies. We have found that most of these evaluation tools exist on a national or state level and that there is a dearth of local or municipal tools. The article concludes with a concrete proposal for an assessment tool: the SIAPJove (Sistema d'Indicadors d'Avaluació per a les Polítiques Municipals de Joventut or System of Assessment Indicators for Local Government Youth Policies) (web page: http://siapjove.udg.edu/). It provides both quantitative and qualitative indicators for local youth policy managers to obtain assessment reports with relative ease in 12 possible areas for assessment within youth policy.
Holographic Lattices Give the Graviton a Mass
Blake, Mike; Vegh, David
2014-01-01
We discuss the DC conductivity of holographic theories with translational invariance broken by a background lattice. We show that the presence of the lattice induces an effective mass for the graviton via a gravitational version of the Higgs mechanism. This allows us to obtain, at leading order in the lattice strength, an analytic expression for the DC conductivity in terms of the size of the lattice at the horizon. In locally critical theories this leads to a power law resistivity that is in agreement with an earlier field theory analysis of Hartnoll and Hofman.
A fractional generalization of the classical lattice dynamics approach
Michelitsch, T M; Riascos, A P; Nowakowski, A F; Nicolleau, F C G A
2016-01-01
We develop physically admissible lattice models in the harmonic approximation which define by Hamilton's variational principle fractional Laplacian matrices of the forms of power law matrix functions on the n -dimensional periodic and infinite lattice in n=1,2,3,..n=1,2,3,.. dimensions. The present model which is based on Hamilton's variational principle is confined to conservative non-dissipative isolated systems. The present approach yields the discrete analogue of the continuous space fractional Laplacian kernel. As continuous fractional calculus generalizes differential operators such as the Laplacian to non-integer powers of Laplacian operators, the fractional lattice approach developed in this paper generalized difference operators such as second difference operators to their fractional (non-integer) powers. Whereas differential operators and difference operators constitute local operations, their fractional generalizations introduce nonlocal long-range features. This is true for discrete and continuous...
Spin-Lattice-Coupled Order in Heisenberg Antiferromagnets on the Pyrochlore Lattice
Aoyama, Kazushi; Kawamura, Hikaru
2016-06-01
Effects of local lattice distortions on the spin ordering are investigated for the antiferromagnetic classical Heisenberg model on the pyrochlore lattice. It is found by Monte Carlo simulations that the spin-lattice coupling (SLC) originating from site phonons induces a first-order transition into two different types of collinear magnetic ordered states. The state realized at the stronger SLC is cubic symmetric characterized by the magnetic (1/2 ,1/2 ,1/2 ) Bragg peaks, while that at the weaker SLC is tetragonal symmetric characterized by the (1,1,0) ones, each accompanied by the commensurate local lattice distortions. Experimental implications to chromium spinels are discussed.
Spin-Lattice-Coupled Order in Heisenberg Antiferromagnets on the Pyrochlore Lattice.
Aoyama, Kazushi; Kawamura, Hikaru
2016-06-24
Effects of local lattice distortions on the spin ordering are investigated for the antiferromagnetic classical Heisenberg model on the pyrochlore lattice. It is found by Monte Carlo simulations that the spin-lattice coupling (SLC) originating from site phonons induces a first-order transition into two different types of collinear magnetic ordered states. The state realized at the stronger SLC is cubic symmetric characterized by the magnetic (1/2,1/2,1/2) Bragg peaks, while that at the weaker SLC is tetragonal symmetric characterized by the (1,1,0) ones, each accompanied by the commensurate local lattice distortions. Experimental implications to chromium spinels are discussed.
Intrinsically localized chaos in discrete nonlinear extended systems
Martínez, P J; Falo, F; Mazo, J J
1999-01-01
The phenomenon of intrinsic localization in discrete nonlinear extended systems, i.e. the (generic) existence of discrete breathers, is shown to be not restricted to periodic solutions but it also extends to more complex (chaotic) dynamical behaviour. We illustrate this with two different forced and damped systems exhibiting this type of solutions: In an anisotropic Josephson junction ladder, we obtain intrinsically localized chaotic solutions by following periodic rotobreather solutions through a cascade of period-doubling bifurcations. In an array of forced and damped van der Pol oscillators, they are obtained by numerical continuation (path-following) methods from the uncoupled limit, where its existence is trivially ascertained, following the ideas of the anticontinuum limit.
Localization System for a Mobile Robot Using Computer Vision Techniques
Directory of Open Access Journals (Sweden)
Rony Cruz Ramírez
2012-05-01
Full Text Available Mobile Robotics is a subject with multiple fields of action hence studies in this area are of vital importance. This paper describes the development of localization system for a mobile robot using Computer Vision. A webcam is placed at a height where the navigation environment can be seen. A LEGO NXT kit is used to build a wheeled mobile robot of differential drive configuration. The software is programmed in C++ using the functions library Open CV 2.0. this software then soft handles the webcam, does the processing of captured images, the calculation of the location, controls and communicates via Bluetooth. Also it implements a kinematic position control and performs several experiments to verify the reliability of the localization system. The results of one such experiment are described here.
New quantum-critical-point-related effects in Ce lattice systems
Energy Technology Data Exchange (ETDEWEB)
Sereni, J.G. [Division Bajas Temperaturas, Centro Atomico Bariloche (CNEA), 8400 S.C. de Bariloche (Argentina)]. E-mail: jsereni@cab.cnea.gov.ar
2004-12-31
Anomalous physical properties related to quantum critical points are investigated in Ce-systems whose magnetic phase boundaries, TN,C(x,p), can be traced for at least one decade of temperature. A change from the usual negative curvature to a linear concentration, x, dependence of TN,C(x) is observed at x*>=xcr/2 (xcr being the critical concentration). Within the x*xxcr region, the usual specific heat temperature dependence Cm/T{proportional_to}Ln(1/T) develops above TN,C, while a nearly constant value of Cm/T maximum is observed besides a scaling of Cm/T(T) with {delta}T=T-TN,C. Coincidentally, a significant increase of the zero-point entropy S0(x)(=RLn2-Sm(x,T)) occurs. Dimensionality and dynamics of the spin fluctuations can be analyzed computing the internal energy and entropy for T>=TN and AC-susceptibility results. Consequences for the free-energy evolution within this region and implications of the S0(x) increase are discussed.
Adamatzky, Andrew
2015-01-01
The book gives a comprehensive overview of the state-of-the-art research and engineering in theory and application of Lattice Automata in design and control of autonomous Robots. Automata and robots share the same notional meaning. Automata (originated from the latinization of the Greek word “αυτόματον”) as self-operating autonomous machines invented from ancient years can be easily considered the first steps of robotic-like efforts. Automata are mathematical models of Robots and also they are integral parts of robotic control systems. A Lattice Automaton is a regular array or a collective of finite state machines, or automata. The Automata update their states by the same rules depending on states of their immediate neighbours. In the context of this book, Lattice Automata are used in developing modular reconfigurable robotic systems, path planning and map exploration for robots, as robot controllers, synchronisation of robot collectives, robot vision, parallel robotic actuators. All chapters are...
Accurate Localization of Communicant Vehicles using GPS and Vision Systems
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Georges CHALLITA
2009-07-01
Full Text Available The new generation of ADAS systems based on cooperation between vehicles can offer serious perspectives to the road security. The inter-vehicle cooperation is made possible thanks to the revolution in the wireless mobile ad hoc network. In this paper, we will develop a system that will minimize the imprecision of the GPS used to car tracking, based on the data given by the GPS which means the coordinates and speed in addition to the use of the vision data that will be collected from the loading system in the vehicle (camera and processor. Localization information can be exchanged between the vehicles through a wireless communication device. The creation of the system must adopt the Monte Carlo Method or what we call a particle filter for the treatment of the GPS data and vision data. An experimental study of this system is performed on our fleet of experimental communicating vehicles.
Localization Capability of Cooperative Anti-Intruder Radar Systems
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Mauro Montanari
2008-06-01
Full Text Available System aspects of an anti-intruder multistatic radar based on impulse radio ultrawideband (UWB technology are addressed. The investigated system is composed of one transmitting node and at least three receiving nodes, positioned in the surveillance area with the aim of detecting and locating a human intruder (target that moves inside the area. Such systems, referred to also as UWB radar sensor networks, must satisfy severe power constraints worldwide imposed by, for example, the Federal Communications Commission (FCC and by the European Commission (EC power spectral density masks. A single transmitter-receiver pair (bistatic radar is considered at first. Given the available transmitted power and the capability of the receiving node to resolve the UWB pulses in the time domain, the surveillance area regions where the target is detectable, and those where it is not, are obtained. Moreover, the range estimation error for the transmitter-receiver pair is discussed. By employing this analysis, a multistatic system is then considered, composed of one transmitter and three or four cooperating receivers. For this multistatic system, the impact of the nodes location on area coverage, necessary transmitted power and localization uncertainty is studied, assuming a circular surveillance area. It is highlighted how area coverage and transmitted power, on one side, and localization uncertainty, on the other side, require opposite criteria of nodes placement. Consequently, the need for a system compromising between these factors is shown. Finally, a simple and effective criterion for placing the transmitter and the receivers is drawn.
Focusing of the Flow Capture for Local Exhaust Ventilation Systems
S. Y. Spotar; Sorokin, A. L.
2010-01-01
Problem statement: The extraction hoods commonly used as inlet element of the local ventilation systems exhibit limited emission capture over moderate distances from the source of the hazardous emissions. Proposed inclusion of a swirling peripheral jet was found to increase the effective length over which the extraction hood successfully captures harmful fumes. However information on a detailed pattern field of the vortex focused inflow was insufficient thus restricting the potential applicat...
Developing a Micropayments System in Local Area Networks
Directory of Open Access Journals (Sweden)
Cristian GEORGESCU
2011-11-01
Full Text Available Starting from the solution of aggregating micropayments in a local area network that operates with reduced costs, with simple and easy to use equipments, with security procedures that are not so complicated, based on the rapport between the cost of fraud and the expected value obtained through fraud, a first stage of developing this system has been accomplished and materialized in the analysis stage by using some of the diagrams put to use by UML.
Transport for Stochastic System with Infinite Locally Coupled Oscillators
Institute of Scientific and Technical Information of China (English)
ZHAO Ying-Kui; LI Jing-Hui; ZHAO Xian-Geng
2003-01-01
We consider the transport of particles for spatially periodic system with infinite locally coupled oscillatorsdriven by additive and multiplicative noises. A formula of the probability current derived by us shows that the couplingamong the infinite oscillators is an ingredient for transport. This coupling of the oscillators can induce transport ofparticles in the absence of the correlation of the additive and multiplicative noises, even without the multiplicative noise.
DEFF Research Database (Denmark)
Santocanale, Luigi
2002-01-01
A μ-lattice is a lattice with the property that every unary polynomial has both a least and a greatest fix-point. In this paper we define the quasivariety of μ-lattices and, for a given partially ordered set P, we construct a μ-lattice JP whose elements are equivalence classes of games in a preor...
Biologically Inspired Object Localization for a Modular Mobile Robotic System
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Zlatogor Minchev
2005-12-01
Full Text Available The paper considers a general model of real biological creatures' antennae, which is practically implemented and tested, over a real element of a mobile modular robotic system - the robot MR1. The last could be utilized in solving of the most classical problem in Robotics - Object Localization. The functionality of the represented sensor system is described in a new and original manner by utilizing the tool of Generalized Nets - a new likelihood for description, modelling and simulation of different objects from the Artificial Intelligence area including Robotics.
Kureta, Masatoshi
A neutron radiography three-dimensional computed tomography (NR3DCT) system was developed to visualize the void fraction distribution of boiling flow in tight lattice heated-rod bundles. This paper chiefly reports on the data processing and the error estimation method of NR3DCT. Practical γ-ray noise reduction and image correction techniques were studied to improve the reliability of the experimental data. Using the system and a directly heated 14-rod bundle test section, the behavior of boiling flow in a tight lattice rod bundle was clearly visualized. The effect of each data processing step on the result was also discussed. By this development, the three-dimensional vapor distribution of boiling flow in a heated bundle is made clear, and void fraction databases can be provided for verification of a thermal-hydraulic simulation code.
Manipulation and control of a bichromatic lattice
Thomas, Claire; Barter, Thomas; Daiss, Severin; Leung, Zephy; Stamper-Kurn, Dan
2015-05-01
Recent experiments with ultracold atoms in optical lattices have had great success emulating the simple models of condensed matter systems. These experiments are typically performed with a single site per unit cell. We realize a lattice with up to four sites per unit cell by overlaying an attractive triangular lattice with a repulsive one at twice the wavelength. The relative displacement of the two lattices determines the particular structure. One available configuration is the kagome lattice, which has a flat energy band. In the flat band all kinetic energy states are degenerate, so we have the opportunity to explore a regime where interactions dominate. This bichromatic lattice requires careful stabilization, but offers an opportunity to manipulate the unit cell and band structure by perturbing the lattices relative to one another. I will discuss recent progress.
Cluster-in-molecule local correlation method for large systems
Institute of Scientific and Technical Information of China (English)
LI Wei; LI ShuHua
2014-01-01
A linear scaling local correlation method,cluster-in-molecule（CIM）method,was developed in the last decade for large systems.The basic idea of the CIM method is that the electron correlation energy of a large system,within the M ller-Plesset perturbation theory（MP）or coupled cluster（CC）theory,can be approximately obtained from solving the corresponding MP or CC equations of various clusters.Each of such clusters consists of a subset of localized molecular orbitals（LMOs）of the target system,and can be treated independently at various theory levels.In the present article,the main idea of the CIM method is reviewed,followed by brief descriptions of some recent developments,including its multilevel extension and different ways of constructing clusters.Then,some applications for large systems are illustrated.The CIM method is shown to be an efficient and reliable method for electron correlation calculations of large systems,including biomolecules and supramolecular complexes.
Local spatio-temporal analysis in vision systems
Geisler, Wilson S.; Bovik, Alan; Cormack, Lawrence; Ghosh, Joydeep; Gildeen, David
1994-07-01
The aims of this project are the following: (1) develop a physiologically and psychophysically based model of low-level human visual processing (a key component of which are local frequency coding mechanisms); (2) develop image models and image-processing methods based upon local frequency coding; (3) develop algorithms for performing certain complex visual tasks based upon local frequency representations, (4) develop models of human performance in certain complex tasks based upon our understanding of low-level processing; and (5) develop a computational testbed for implementing, evaluating and visualizing the proposed models and algorithms, using a massively parallel computer. Progress has been substantial on all aims. The highlights include the following: (1) completion of a number of psychophysical and physiological experiments revealing new, systematic and exciting properties of the primate (human and monkey) visual system; (2) further development of image models that can accurately represent the local frequency structure in complex images; (3) near completion in the construction of the Texas Active Vision Testbed; (4) development and testing of several new computer vision algorithms dealing with shape-from-texture, shape-from-stereo, and depth-from-focus; (5) implementation and evaluation of several new models of human visual performance; and (6) evaluation, purchase and installation of a MasPar parallel computer.
López, L. G.; Linares, D. H.; Ramirez-Pastor, A. J.
2009-01-01
Monte Carlo simulations have been carried out for a system of monomers on square lattices that, by decreasing temperature or increasing density, polymerize reversibly into chains with two allowed directions and, at the same time, undergo a continuous isotropic-nematic (I-N) transition. The results show that the self-assembly process affects the nature of the transition. Thus, the determination of the critical exponents indicates that the universality class of the I-N transition changes from t...
Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity.
Henry, Elizabeth; Yadeta, Koste A; Coaker, Gitta
2013-09-01
Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of molecular interactions responsible for coordinating defense responses and ultimately resistance.
THEORY METODOLOGICAL BASIS OF LOCAL SYSTEMS OF CORPORATIVE ENTERPRISE MANAGEMENT
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N.A. Pytkin
2007-03-01
Full Text Available The urgency of corporate governance systems research is caused by apparently not complete realization of these systems in the modern practice as only in an insignificant degree considers peculiarities of each single company and relies, first of all, on the experience of base systems of corporate governance in general. Such approach results in a bunch of negative effects, including formal realization of requirements of "corporate governance codes" and other similar documents. In this connection we offer the approach to designing effective local systems of corporate governance (LSCG which would consider not only the existing recommendations on corporate governance, but also the greatest possible set of external and internal factors for every separate company. This article is devoted to theoretical bases of LSCG.
Adaptive chaos control and synchronization in only locally Lipschitz systems
Energy Technology Data Exchange (ETDEWEB)
Lin Wei [Key Laboratory of Mathematics for Nonlinear Sciences (Fudan University), Ministry of Education, School of Mathematical Sciences, Fudan University, Shanghai 200433 (China); CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences (China)], E-mail: wlin@fudan.edu.cn
2008-04-28
In the existing results on chaos control and synchronization based on the adaptive controlling technique (ACT), a uniform Lipschitz condition on a given dynamical system is always assumed in advance. However, without this uniform Lipschitz condition, the ACT might be failed in both theoretical analysis and in numerical experiment. This Letter shows how to utilize the ACT to get a rigorous control for the system which is not uniformly Lipschitz but only locally Lipschitz, and even for the system which has unbounded trajectories. In fact, the ACT is proved to possess some limitation, which is actually induced by the nonlinear degree of the original system. Consequently, a piecewise ACT is proposed so as to improve the performance of the existing techniques.
BIRCH: A user-oriented, locally-customizable, bioinformatics system
Directory of Open Access Journals (Sweden)
Fristensky Brian
2007-02-01
Full Text Available Abstract Background Molecular biologists need sophisticated analytical tools which often demand extensive computational resources. While finding, installing, and using these tools can be challenging, pipelining data from one program to the next is particularly awkward, especially when using web-based programs. At the same time, system administrators tasked with maintaining these tools do not always appreciate the needs of research biologists. Results BIRCH (Biological Research Computing Hierarchy is an organizational framework for delivering bioinformatics resources to a user group, scaling from a single lab to a large institution. The BIRCH core distribution includes many popular bioinformatics programs, unified within the GDE (Genetic Data Environment graphic interface. Of equal importance, BIRCH provides the system administrator with tools that simplify the job of managing a multiuser bioinformatics system across different platforms and operating systems. These include tools for integrating locally-installed programs and databases into BIRCH, and for customizing the local BIRCH system to meet the needs of the user base. BIRCH can also act as a front end to provide a unified view of already-existing collections of bioinformatics software. Documentation for the BIRCH and locally-added programs is merged in a hierarchical set of web pages. In addition to manual pages for individual programs, BIRCH tutorials employ step by step examples, with screen shots and sample files, to illustrate both the important theoretical and practical considerations behind complex analytical tasks. Conclusion BIRCH provides a versatile organizational framework for managing software and databases, and making these accessible to a user base. Because of its network-centric design, BIRCH makes it possible for any user to do any task from anywhere.
Influence of disorder on generation and probability of extreme events in Salerno lattices
Mančić, A.; Maluckov, A.; Hadžievski, Lj.
2017-03-01
Extreme events (EEs) in nonlinear and/or disordered one-dimensional photonic lattice systems described by the Salerno model with on-site disorder are studied. The goal is to explain particular properties of these phenomena, essentially related to localization of light in the presence of nonlinear and/or nonlocal couplings in the considered systems. Combining statistical and nonlinear dynamical methods and measures developed in the framework of the theory of localization phenomena in disordered and nonlinear systems, particularities of EEs are qualitatively clarified. Findings presented here indicate that the best environment for EEs' creation are disordered near-integrable Salerno lattices. In addition, it is been shown that the leading role in the generation and dynamical properties of EEs in the considered model is played by modulation instability, i.e., by nonlinearities in the system, although EEs can be induced in linear lattices with on-site disorder too.
Optoelectronic scanning system upgrade by energy center localization methods
Flores-Fuentes, W.; Sergiyenko, O.; Rodriguez-Quiñonez, J. C.; Rivas-López, M.; Hernández-Balbuena, D.; Básaca-Preciado, L. C.; Lindner, L.; González-Navarro, F. F.
2016-11-01
A problem of upgrading an optoelectronic scanning system with digital post-processing of the signal based on adequate methods of energy center localization is considered. An improved dynamic triangulation analysis technique is proposed by an example of industrial infrastructure damage detection. A modification of our previously published method aimed at searching for the energy center of an optoelectronic signal is described. Application of the artificial intelligence algorithm of compensation for the error of determining the angular coordinate in calculating the spatial coordinate through dynamic triangulation is demonstrated. Five energy center localization methods are developed and tested to select the best method. After implementation of these methods, digital compensation for the measurement error, and statistical data analysis, a non-parametric behavior of the data is identified. The Wilcoxon signed rank test is applied to improve the result further. For optical scanning systems, it is necessary to detect a light emitter mounted on the infrastructure being investigated to calculate its spatial coordinate by the energy center localization method.
Light-induced electron localization in a quantum Hall system
Arikawa, T.; Hyodo, K.; Kadoya, Y.; Tanaka, K.
2017-07-01
An insulating bulk state is a prerequisite for the protection of topological edge states. In quantum Hall systems, the thermal excitation of delocalized electrons is the main route to breaking bulk insulation. In equilibrium, the only way to achieve a clear bulk gap is to use a high-quality crystal under high magnetic field at low temperature. However, bulk conduction could also be suppressed in a system driven out of equilibrium such that localized states in the Landau levels are selectively occupied. Here we report a transient suppression of bulk conduction induced by terahertz wave excitation between the Landau levels in a GaAs quantum Hall system. Strikingly, the Hall resistivity almost reaches the quantized value at a temperature where the exact quantization is normally disrupted by thermal fluctuations. The electron localization is realized by the long-range potential fluctuations, which are a unique and inherent feature of quantum Hall systems. Our results demonstrate a new means of effecting dynamical control of topology by manipulating bulk conduction using light.
Perfect Lattice Actions for Staggered Fermions
Bietenholz, W; Chandrasekharan, S; Wiese, U J
1996-01-01
We construct a perfect lattice action for staggered fermions by blocking from the continuum. The locality, spectrum and pressure of such perfect staggered fermions are discussed. We also derive a consistent fixed point action for free gauge fields and discuss its locality as well as the resulting static quark-antiquark potential. This provides a basis for the construction of (classically) perfect lattice actions for QCD using staggered fermions.
Mean ergodic operators and reflexive Fréchet lattices
Bonet, J.; De Pagter, B.; Ricker, W.J.
2011-01-01
Connections between (positive) mean ergodic operators acting in Banach lattices and properties of the underlying lattice itself are well understood (see the works of Emel'yanov, Wolff and Zaharopol). For Fréchet lattices (or more general locally convex solid Riesz spaces) there is virtually no infor
Weak localization of light in superdiffusive random systems
Burresi, Matteo; Savo, Romolo; Bertolotti, Jacopo; Vynck, Kevin; Wiersma, Diederik S
2011-01-01
L\\'evy flights constitute a broad class of random walks that occur in many fields of research, from animal foraging in biology, to economy to geophysics. The recent advent of L\\'evy glasses allows to study L\\'evy flights in controlled way using light waves. This raises several questions about the influence of superdiffusion on optical interference effects like weak and strong localization. Super diffusive structures have the extraordinary property that all points are connected via direct jumps, meaning that finite-size effects become an essential part of the physical problem. Here we report on the experimental observation of weak localization in L\\'evy glasses and compare results with recently developed optical transport theory in the superdiffusive regime. Experimental results are in good agreement with theory and allow to unveil how light propagates inside a finite-size superdiffusive system.
Localization in chaotic systems with a single-channel opening.
Lippolis, Domenico; Ryu, Jung-Wan; Kim, Sang Wook
2015-07-01
We introduce a single-channel opening in a random Hamiltonian and a quantized chaotic map: localization on the opening occurs as a sensible deviation of the wave-function statistics from the predictions of random matrix theory, even in the semiclassical limit. Increasing the coupling to the open channel in the quantum model, we observe a similar picture to resonance trapping, made of a few fast-decaying states, whose left (right) eigenfunctions are entirely localized on the (preimage of the) opening, and plentiful long-lived states, whose probability density is instead suppressed at the opening. For the latter, we derive and test a linear relation between the wave-function intensities and the decay rates, similar to the Breit-Wigner law. We then analyze the statistics of the eigenfunctions of the corresponding (discretized) classical propagator, finding a similar behavior to the quantum system only in the weak-coupling regime.
Local fluctuations in the relaxation rate in a glassy system
Pandit, Rajib; Flenner, Elijah; Castillo, Horacio E.
We numerically study the equilibrium dynamics of a glass-forming binary hard-sphere mixture, for different packing fractions. We extract a correlator that probes the integrated fluctuations in the local relaxation rate in the system. We find that the strength of this correlator at t =τα (the α-relaxation time) grows with packing fraction approximately as a power of τα. We also find that for a fixed packing fraction, the correlator grows as a power of time, for very long times, with an exponent that depends on the packing fraction. This exponent probes the time correlations of the relaxation rate fluctuations. We find that the exponent is around 3 for very low packing fractions, and gradually decreases to a value below 2 as the glass transition is approached. We conclude that a description of fluctuations in terms of local relaxation rates is only applicable at long times and for packing fractions close to the glass transition.
Directory of Open Access Journals (Sweden)
Abílio Amiguinho
2005-01-01
Full Text Available The process of socio-educational territorialisation in rural contexts is the topic of this text. The theme corresponds to a challenge to address it having as main axis of discussion either the problem of social exclusion or that of local development. The reasons to locate the discussion in this last field of analysis are discussed in the first part of the text. Theoretical and political reasons are there articulated because the question is about projects whose intentions and practices call for the political both in the theoretical debate and in the choices that anticipate intervention. From research conducted for several years, I use contributions that aim at discuss and enlighten how school can be a potential locus of local development. Its identification and recognition as local institution (either because of those that work and live in it or because of those that act in the surrounding context are crucial steps to progressively constitute school as a partner for development. The promotion of the local values and roots, the reconstruction of socio-personal and local identities, the production of sociabilities and the equation and solution of shared problems were the dimensions of a socio-educative intervention, markedly globalising. This scenario, as it is argued, was also, intentionally, one of transformation and of deliberate change of school and of the administration of the educative territoires.
Ground-state phase diagram of the Kondo lattice model on triangular-to-kagome lattices
Akagi, Yutaka; Motome, Yukitoshi
2012-01-01
We investigate the ground-state phase diagram of the Kondo lattice model with classical localized spins on triangular-to-kagome lattices by using a variational calculation. We identify the parameter regions where a four-sublattice noncoplanar order is stable with a finite spin scalar chirality while changing the lattice structure from triangular to kagome continuously. Although the noncoplanar spin states appear in a wide range of parameters, the spin configurations on the kagome network beco...
Breakdown of the classical description of a local system
DEFF Research Database (Denmark)
Eran, Kot; Grønbech-Jensen, Niels; Nielsen, Bo Melholt
2012-01-01
We provide a straightforward demonstration of a fundamental difference between classical and quantum mechanics for a single local system: namely, the absence of a joint probability distribution of the position x and momentum p. Elaborating on a recently reported criterion by Bednorz and Belzig...... of the breakdown of a classical description of the underlying state. Most importantly, the criterion used does not rely on quantum mechanics and can thus be used to demonstrate nonclassicality of systems not immediately apparent to exhibit quantum behavior. The criterion is directly applicable to any system...... [ Phys. Rev. A 83 052113 (2011)] we derive a simple criterion that must be fulfilled for any joint probability distribution in classical physics. We demonstrate the violation of this criterion using the homodyne measurement of a single photon state, thus proving a straightforward signature...
Breakdown of the classical description of a local system
DEFF Research Database (Denmark)
Eran, Kot; Grønbech-Jensen, Niels; Nielsen, Bo Melholt
2012-01-01
We provide a straightforward demonstration of a fundamental difference between classical and quantum mechanics for a single local system: namely, the absence of a joint probability distribution of the position x and momentum p. Elaborating on a recently reported criterion by Bednorz and Belzig...... of the breakdown of a classical description of the underlying state. Most importantly, the criterion used does not rely on quantum mechanics and can thus be used to demonstrate nonclassicality of systems not immediately apparent to exhibit quantum behavior. The criterion is directly applicable to any system...... [ Phys. Rev. A 83 052113 (2011)] we derive a simple criterion that must be fulfilled for any joint probability distribution in classical physics. We demonstrate the violation of this criterion using the homodyne measurement of a single photon state, thus proving a straightforward signature...
Reconstructing Concept Lattices Usingnth-Order Context Kernels
Institute of Scientific and Technical Information of China (English)
SHEN Xiajiong; XU Bin; LIU Zongtian
2006-01-01
To be different from traditional algorithms for concept lattice constructing, a method based on nth-order context kernel is suggested in this paper.The context kernels support generating small lattices for sub-contexts split by a given context.The final concept lattice is reconstructed by combining these small lattices.All relevant algorithms are implemented in a system IsoFCA.Test shows that the method yields concept lattices in lower time complexity than Godin algorithm in practical case.
Ripesi, P; Schifano, S F; Tripiccione, R
2014-01-01
We study the turbulent evolution originated from a system subjected to a Rayleigh-Taylor instability with a double density at high resolution in a 2 dimensional geometry using a highly optimized thermal Lattice Boltzmann code for GPUs. The novelty of our investigation stems from the initial condition, given by the superposition of three layers with three different densities, leading to the development of two Rayleigh-Taylor fronts that expand upward and downward and collide in the middle of the cell. By using high resolution numerical data we highlight the effects induced by the collision of the two turbulent fronts in the long time asymptotic regime. We also provide details on the optimized Lattice-Boltzmann code that we have run on a cluster of GPUs
Efficient construction of nonorthogonal localized molecular orbitals in large systems.
Cui, Ganglong; Fang, Weihai; Yang, Weitao
2010-08-26
Localized molecular orbitals (LMOs) are much more compact representations of electronic degrees of freedom than canonical molecular orbitals (CMOs). The most compact representation is provided by nonorthogonal localized molecular orbitals (NOLMOs), which are linearly independent but are not orthogonal. Both LMOs and NOLMOs are thus useful for linear-scaling calculations of electronic structures for large systems. Recently, NOLMOs have been successfully applied to linear-scaling calculations with density functional theory (DFT) and to reformulating time-dependent density functional theory (TDDFT) for calculations of excited states and spectroscopy. However, a challenge remains as NOLMO construction from CMOs is still inefficient for large systems. In this work, we develop an efficient method to accelerate the NOLMO construction by using predefined centroids of the NOLMO and thereby removing the nonlinear equality constraints in the original method ( J. Chem. Phys. 2004 , 120 , 9458 and J. Chem. Phys. 2000 , 112 , 4 ). Thus, NOLMO construction becomes an unconstrained optimization. Its efficiency is demonstrated for the selected saturated and conjugated molecules. Our method for fast NOLMO construction should lead to efficient DFT and NOLMO-TDDFT applications to large systems.
Local factorisation of the dynamics of quantum spin systems
Bachmann, Sven; Bluhm, Andreas
2017-07-01
Motivated by the study of area laws for the entanglement entropy of gapped ground states of quantum spin systems and their stability, we prove that the unitary cocycle generated by a local time-dependent Hamiltonian can be approximated, for any finite set X, by a tensor product of the corresponding unitaries in X and its complement, multiplied by a dynamics strictly supported in the neighbourhood of the surface ∂ X . The error decays almost exponentially in the size of the neighbourhood and grows with the square of the area |∂ X |2.
On porous-elastic system with localized damping
Santos, M. L.; Almeida Júnior, D. S.
2016-06-01
In this article, we are considering the one-dimensional equations of an homogeneous and isotropic porous elastic solid, where the localized damping involves the sum of displacement velocity of a solid elastic material and the volume fraction velocity. First we show, using a result due to Benchimol (SIAM J Control Optim 16:373-379, 1978), that the semigroup associated with the system is strongly stable if and only if the boundary of the support of feedback control intersects that of the interval under consideration. Then we use the frequency domain method combined with careful inequalities obtained using multiplicative techniques to prove that the semigroup under consideration is exponentially stable.
Joint system quantum descriptions arising from local quantumness
Cooney, Tom; Navascues, Miguel; Perez-Garcia, David; Villanueva, Ignacio
2012-01-01
Bipartite correlations generated by non-signalling physical systems that admit a finite-dimensional local quantum description cannot exceed the quantum limits, i.e., they can always be interpreted as distant measurements of a bipartite quantum state. Here we consider the effect of dropping the assumption of finite dimensionality. Remarkably, we find that the same result holds provided that we relax the tensor structure of space-like separated measurements to mere commutativity. We argue why an extension of this result to tensor representations seems unlikely.
Local decoherence-resistant quantum states of large systems
Energy Technology Data Exchange (ETDEWEB)
Mishra, Utkarsh; Sen, Aditi; Sen, Ujjwal, E-mail: ujjwal@hri.res.in
2015-02-06
We identify an effectively decoherence-free class of quantum states, each of which consists of a “minuscule” and a “large” sector, against local noise. In particular, the content of entanglement and other quantum correlations in the minuscule to large partition is independent of the number of particles in their large sectors, when all the particles suffer passage through local amplitude and phase damping channels. The states of the large sectors are distinct in terms of markedly different amounts of violation of Bell inequality. In case the large sector is macroscopic, such states are akin to the Schrödinger cat. - Highlights: • We identify an effectively decoherence-free class of quantum states of large systems. • We work with local noise models. • Decay of entanglement as well as information-theoretic quantum correlations considered. • The states are of the form of the Schrödinger cats, with minuscule and large sectors. • The states of the large sector are distinguishable by their violation of Bell inequality.
Hurricanes and Climate Change: Global Systems and Local Impacts
Santer, J.
2011-12-01
With funding from NOAA, the Miami Science Museum has been working with exhibit software developer Ideum to create an interactive exhibit exploring the global dimensions and local impacts of climate change. A particular focus is on climate-related impacts on coastal communities, including the potential effects on South Florida of ocean acidification, rising sea level, and the possibility of more intense hurricanes. The exhibit is using a 4-foot spherical display system in conjunction with a series of touchscreen kiosks and accompanying flat screens to create a user-controlled, multi-user interface that lets visitors control the sphere and choose from a range of global and local content they wish to explore. The exhibit has been designed to promote engagement of diverse, multigenerational audiences through development of a fully bilingual user interface that promotes social interaction and conversation among visitors as they trade off control of global content on the sphere and related local content on the flat screens. The open-source learning module will be adaptable by other museums, to explore climate impacts specific to their region.
Axial Anomaly in Lattice Abelian Gauge Theory in Arbitrary Dimensions
Fujiwara, T; Wu, K; Fujiwara, Takanori; Suzuki, Hiroshi; Wu, Ke
1999-01-01
Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative constant for finite lattice spacing and can be interpreted as the Chern character of the abelian lattice gauge theory.
Sober Topological Molecular Lattices%Sober拓扑分子格
Institute of Scientific and Technical Information of China (English)
张德学; 李永明
2003-01-01
A topological molecular lattice (TML) is a pair (L,τ), where L is a completely distributive lattice and τ is a subframe of L. There is an obvious forgetful functor from the category TML of TML's to the category Loc of locales. In this note,it is showed that this forgetful functor has a right adjoint. Then, bythis adjunction,a special kind of topological molecular lattices called sober topological molecular lattices is introduced and investigated.
Polarization response of RHIC electron lens lattices
Directory of Open Access Journals (Sweden)
V. H. Ranjbar
2016-10-01
Full Text Available Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. In particular we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. These results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. Finally we consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.
Importance of concomitant local and systemic eosinophilia in uncontrolled asthma.
Schleich, Florence Nicole; Chevremont, Anne; Paulus, Virginie; Henket, Monique; Manise, Maité; Seidel, Laurence; Louis, Renaud
2014-07-01
Systemic and airway eosinophilia are recognised features of asthma. There are, however, patients who exhibit discordance between local and systemic eosinophilia. In this study, we sought to determine the prevalence and characteristics of patients with concordant and discordant systemic and bronchial eosinophilia. We conducted a retrospective study on 508 asthmatics with successful sputum induction. We assessed the relationship between blood and sputum eosinophils by breaking down the population into four groups according to blood (≥400 cells per mm3) and sputum (≥3%) eosinophils. Then, we prospectively reassessed the link between eosinophils and asthma control (Asthma Control Questionnaire (ACQ)) and exacerbation rate in a new cohort of 250 matched asthmatics. In our retrospective cohort, asthmatics without eosinophilic inflammation were the largest group (49%). The group with isolated sputum eosinophilia (25%) was, compared with noneosinophilic asthma, associated with lower forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity ratio and higher bronchial hyperresponsiveness and exhaled nitric oxide fraction (FeNO). Asthmatics exhibiting isolated systemic eosinophilia (7%) had similar characteristics as noneosinophilic asthmatics. The group with concordant systemic and airway eosinophilia (19%) showed remarkable male predominance, and had the lowest airway calibre, asthma control and quality of life, and the highest bronchial hyperresponsiveness, FeNO and exacerbation rate. The prospective cohort confirmed the different subgroup proportions and the higher ACQ and exacerbation rates in cases of diffuse eosinophilia compared with noneosinophilic asthmatics. Concomitant systemic and bronchial eosinophilic inflammation contribute to poor asthma control. © ERS 2014.
A criterion for lattice supersymmetry: cyclic Leibniz rule
Kato, Mitsuhiro; So, Hiroto
2013-01-01
It is old folklore that the violation of Leibniz rule on a lattice is an obstruction for constructing a lattice supersymmetric model. While it is still true for full supersymmetry, we show that a slightly modified form of the Leibniz rule, which we call cyclic Leibniz rule (CLR), is actually a criterion for the existence of partial lattice supersymmetry. In one dimension, we find sets of lattice difference operator and field multiplication smeared over lattice which satisfy the CLR under some natural assumptions such as translational invariance and locality. Thereby we construct a model of supersymmetric lattice quantum mechanics without spoiling locality. The CLR relation is coincident with the condition that the vanishing of the so-called surface term in the construction by lattice Nicolai map. We can construct superfield formalism with arbitrary superpotential. This also enables us to apply safely a localization technique to our model, because the kinetic term and the interaction terms of our model are ind...
Topological Representations of Distributive Hypercontinuous Lattices
Institute of Scientific and Technical Information of China (English)
Xiaoquan XU; Jinbo YANG
2009-01-01
The concept of locally strong compactness on domains is generalized to general topological spaces.It is proved that for each distributive hypercontinuous lattice L,the space SpecL of nonunit prime elements endowed with the hull-kernel topology is locally strongly compact,and for each locally strongly compact space X,the complete lattice of all open sets (9(X) is distributive hypercontinuous.For the case of distributive hyperalgebraic lattices,the similar result is given.For a sober space X,it is shown that there is an order reversing isomorphism between the set of upper-open filters of the lattice (.9(X) of open subsets of X and the set of strongly compact saturated subsets of X,which is analogous to the well-known Hofmann-Mislove Theorem.
Supersymmetry protected topological phases of isostatic lattices and kagome antiferromagnets
Lawler, Michael J.
2016-10-01
I generalize the theory of phonon topological band structures of isostatic lattices to frustrated antiferromagnets. I achieve this with a discovery of a many-body supersymmetry (SUSY) in the phonon problem of balls and springs and its connection to local constraints satisfied by ground states. The Witten index of the SUSY model demands the Maxwell-Calladine index of mechanical structures. "Spontaneous supersymmetry breaking" is identified as the need to gap all modes in the bulk to create the topological isostatic lattice state. Since ground states of magnetic systems also satisfy local constraint conditions (such as the vanishing of the total spin on a triangle), I identify a similar SUSY structure for many common models of antiferromagnets including the square, triangluar, kagome, pyrochlore nearest-neighbor antiferromagnets, and the J2=J1/2 square-lattice antiferromagnet. Remarkably, the kagome family of antiferromagnets is the analog of topological isostatic lattices among this collection of models. Thus, a solid-state realization of the theory of phonon topological band structure may be found in frustrated magnetic materials.
Localized and systemic forms of scleroderma in adults and children .
Atzeni, F; Bardoni, A; Cutolo, M; Hunzelmann, N; Krieg, T; Martini, G; Montecucco, C; Olski, T M; Secchi, M E; Valentini, G; Zulian, F; Sarzi-Puttini, P
2006-01-01
Systemic sclerosis (SSc) presents a great deal of variability in the extent and severity of skin and internal organ involvement. The diagnostic and prognostic significance of autoantibodies in SSc is undisputed and the patient's autoantibody profile represents a fundamental tool for clinicians. Scleroderma is a rare condition in children. Unlike adults, localized scleroderma is more frequent than the systemic sclerosis, nevertheless it represents a disabling condition. In both conditions, no validated outcome measures and proven effective treatment is available to date.Raynaud's phenomenon (RP) is one the most common and significant clinical symptoms of SSc and therefore in patients with RP a capillaroscopic analysis should be carried out as soon as possible. The actual and select advantage of the early nailfold videocapillaroscopic (NVC) analysis is to distinguish between the primary RP and the secondary RP and to allow the early detection of SSc.
[Participation of dental auxiliary personnel in local health systems].
Frazão, P; Castellanos, R A
1999-02-01
Though numerous local health systems (sistemas locales de salud, or SILOS) in Brazil employ dental assistants, there is little information on the contributions these workers make to oral health programs. The purpose of this study was to examine the role of such workers in 10 SILOS in five municipalities in the state of São Paulo. Of the 325 dental assistants and dental hygienists employed in those systems, 245 (75.4%) answered a questionnaire that had been prepared. The results showed variations in the degree to which dental assistants participated in oral health promotion activities in the SILOS studied. In some SILOS, these workers devoted more time to dental health promotion activities than to helping perform dental tasks with individual patients. The most frequent oral health promotion activities were fluoride rinses, plaque detection followed by supervised brushing, and educational activities at basic health units and schools. In all cases, dental assistants working in the SILOS played a significant role in helping transform the practice of dentistry within the sphere of public health.
Fluoroscopic image-guided intervention system for transbronchial localization
Rai, Lav; Keast, Thomas M.; Wibowo, Henky; Yu, Kun-Chang; Draper, Jeffrey W.; Gibbs, Jason D.
2012-02-01
Reliable transbronchial access of peripheral lung lesions is desirable for the diagnosis and potential treatment of lung cancer. This procedure can be difficult, however, because accessory devices (e.g., needle or forceps) cannot be reliably localized while deployed. We present a fluoroscopic image-guided intervention (IGI) system for tracking such bronchoscopic accessories. Fluoroscopy, an imaging technology currently utilized by many bronchoscopists, has a fundamental shortcoming - many lung lesions are invisible in its images. Our IGI system aligns a digitally reconstructed radiograph (DRR) defined from a pre-operative computed tomography (CT) scan with live fluoroscopic images. Radiopaque accessory devices are readily apparent in fluoroscopic video, while lesions lacking a fluoroscopic signature but identifiable in the CT scan are superimposed in the scene. The IGI system processing steps consist of: (1) calibrating the fluoroscopic imaging system; (2) registering the CT anatomy with its depiction in the fluoroscopic scene; (3) optical tracking to continually update the DRR and target positions as the fluoroscope is moved about the patient. The end result is a continuous correlation of the DRR and projected targets with the anatomy depicted in the live fluoroscopic video feed. Because both targets and bronchoscopic devices are readily apparent in arbitrary fluoroscopic orientations, multiplane guidance is straightforward. The system tracks in real-time with no computational lag. We have measured a mean projected tracking accuracy of 1.0 mm in a phantom and present results from an in vivo animal study.
Transport in nanoscale systems: hydrodynamics, turbulence, and local electron heating
di Ventra, Massimiliano
2007-03-01
Transport in nanoscale systems is usually described as an open-boundary scattering problem. This picture, however, says nothing about the dynamical onset of steady states, their microscopic nature, or their dependence on initial conditions [1]. In order to address these issues, I will first describe the dynamical many-particle state via an effective quantum hydrodynamic theory [2]. This approach allows us to predict a series of novel phenomena like turbulence of the electron liquid [2], local electron heating in nanostructures [3], and the effect of electron viscosity on resistance [4]. I will provide both analytical results and numerical examples of first-principles electron dynamics in nanostructures using the above approach. I will also discuss possible experimental tests of our predictions. Work supported in part by NSF and DOE. [1] N. Bushong, N. Sai and M. Di Ventra, ``Approach to steady-state transport in nanoscale systems'' Nano Letters, 5 2569 (2005); M. Di Ventra and T.N. Todorov, ``Transport in nanoscale systems: the microcanonical versus grand-canonical picture,'' J. Phys. Cond. Matt. 16, 8025 (2004). [2] R. D'Agosta and M. Di Ventra, ``Hydrodynamic approach to transport and turbulence in nanoscale conductors,'' cond-mat/05123326; J. Phys. Cond. Matt., in press. [3] R. D'Agosta, N. Sai and M. Di Ventra, ``Local electron heating in nanoscale conductors,'' cond-mat/0605312; Nano Letters, in press. [4] N. Sai, M. Zwolak, G. Vignale and M. Di Ventra, ``Dynamical corrections to the DFT-LDA electron conductance in nanoscale systems,'' Phys. Rev. Lett. 94, 186810 (2005).
Anisotropic dissipation in lattice metamaterials
Directory of Open Access Journals (Sweden)
Dimitri Krattiger
2016-12-01
Full Text Available Plane wave propagation in an elastic lattice material follows regular patterns as dictated by the nature of the lattice symmetry and the mechanical configuration of the unit cell. A unique feature pertains to the loss of elastodynamic isotropy at frequencies where the wavelength is on the order of the lattice spacing or shorter. Anisotropy may also be realized at lower frequencies with the inclusion of local resonators, especially when designed to exhibit directionally non-uniform connectivity and/or cross-sectional geometry. In this paper, we consider free and driven waves within a plate-like lattice−with and without local resonators−and examine the effects of damping on the isofrequency dispersion curves. We also examine, for free waves, the effects of damping on the frequency-dependent anisotropy of dissipation. Furthermore, we investigate the possibility of engineering the dissipation anisotropy by tuning the directional properties of the prescribed damping. The results demonstrate that uniformly applied damping tends to reduce the intensity of anisotropy in the isofrequency dispersion curves. On the other hand, lattice crystals and metamaterials are shown to provide an excellent platform for direction-dependent dissipation engineering which may be realized by simple changes in the spatial distribution of the damping elements.
On the number of eigenvalues of a model operator related to a system of three particles on lattices
Energy Technology Data Exchange (ETDEWEB)
Dell' Antonio, G F [SISSA-ISAS, Via Bonomea 265, 34136, Trieste (Italy); Muminov, Z I; Shermatova, Y M, E-mail: gianfa@sissa.it, E-mail: zimuminov@mail.ru [Samarkand State University, University Boulevard 15, 703004, Samarkand (Uzbekistan)
2011-08-05
We consider a quantum mechanical system on a lattice Z{sup 3} in which three particles, two of them being identical, interact through a zero-range potential. We admit a very general form for the 'kinetic' part H{sup 0}{sub {gamma}} of the Hamiltonian, which contains a parameter {gamma} to distinguish the two identical particles from the third one (in the continuum case this parameter would be the inverse of the mass). We prove that there is a value {gamma}* of the parameter such that only for {gamma} < {gamma}* the Efimov effect (infinite number of bound states if the two-body interactions have a resonance) is absent for the sector of the Hilbert space which contains functions which are antisymmetric with respect to the two identical particles, while it is present for all values of {gamma} on the symmetric sector. We comment briefly on the relation of this result with previous investigations on the Thomas effect. We also establish the following asymptotics for the number N(z) of eigenvalues z below E{sub min}, the lower limit of the essential spectrum of H{sub 0}. In the symmetric subspace lim{sub z{yields}Emin'}-(N's(z))/(log E{sub min}-z) = U{sub 0}'s({gamma}), for all {gamma}, whereas in the antisymmetric subspace lim{sub z{yields}Emin'}- (N'a's(z))/(log E{sub min}-z) = U{sub 0}'a's({gamma}), for all {gamma}>{gamma}'*, where U{sub 0}{sup as}({gamma}), U{sub 0}{sup s} ({gamma}) are written explicitly as a function of the integral kernel of operators acting on L{sup 2}((0,r)x(L{sup 2} (S{sup 2})xL{sup 2} (S{sup 2})) (S{sup 2} is the unit sphere in R{sup 3}).
Institute of Scientific and Technical Information of China (English)
Fu-qi Yin; Sheng-fan Zhou
2006-01-01
In this paper, we establish the existence of a global attractor for a coupled k-dimensional lattice dynamical system governed by a discrete version of the Klein-Gordon-Schrodinger Equation. An estimate of the upper bound of the Kolmogorov ε-entropy of the global attractor is made by a method of element decomposition and the covering property of a polyhedron by balls of radii ε in a finite dimensional space. Finally, a scheme to approximate the global attractor by the global attractors of finite-dimensional ordinary differential systems is presented .
Hamiltonian monodromy as lattice defect
Zhilinskii, B.
2003-01-01
The analogy between monodromy in dynamical (Hamiltonian) systems and defects in crystal lattices is used in order to formulate some general conjectures about possible types of qualitative features of quantum systems which can be interpreted as a manifestation of classical monodromy in quantum finite particle (molecular) problems.
Pseudo-two-dimensional random dimer lattices
Energy Technology Data Exchange (ETDEWEB)
Naether, U., E-mail: naether@unizar.es [Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC – Universidad de Zaragoza, 50009 Zaragoza (Spain); Mejía-Cortés, C.; Vicencio, R.A. [Departamento de Física and MSI – Nucleus for Advanced Optics, Center for Optics and Photonics (CEFOP), Facultad de Ciencias, Universidad de Chile, Santiago (Chile)
2015-06-05
We study the long-time wave transport in correlated and uncorrelated disordered 2D arrays. When a separation of dimensions is applied to the model, we find that the previously predicted 1D random dimer phenomenology also appears in so-called pseudo-2D arrays. Therefore, a threshold behavior is observed in terms of the effective size for eigenmodes, as well as in long-time dynamics. A minimum system size is required to observe this threshold, which is very important when considering a possible experimental realization. For the long-time evolution, we find that for correlated lattices a super-diffusive long-range transport is observed. For completely uncorrelated disorder 2D transport becomes sub-diffusive within the localization length and for random binary pseudo-2D arrays localization is observed.
Fan, W. J.; Bose, Sumanta; Zhang, D. H.
2016-09-01
Dilute nitride bismide GaNBiAs is a potential semiconductor alloy for near- and mid-infrared applications, particularly in 1.55 μm optical communication systems. Incorporating dilute amounts of bismuth (Bi) into GaAs reduces the effective bandgap rapidly, while significantly increasing the spin-orbit-splitting energy. Additional incorporation of dilute amounts of nitrogen (N) helps to attain lattice matching with GaAs, while providing a route for flexible bandgap tuning. Here we present a study of the electronic bandstructure and optical gain of the lattice matched GaNxBiy As1 -x -y /GaAs quaternary alloy quantum well (QW) based on the 16-band k .p model. We have taken into consideration the interactions between the N and Bi impurity states with the host material based on the band anticrossing and valence band anticrossing model. The optical gain calculation is based on the density matrix theory. We have considered different lattice matched GaNBiAs QW cases and studied their energy dispersion curves, optical gain spectrum, maximum optical gain, and differential gain and compared their performances based on these factors. The thickness and composition of these QWs were varied in order to keep the emission peak fixed at 1.55 μm. The well thickness has an effect on the spectral width of the gain curves. On the other hand, a variation in the injection carrier density has different effects on the maximum gain and differential gain of QWs of varying thicknesses. Among the cases studied, we found that the 6.3 nm thick GaN3 Bi5.17 As91.83 lattice matched QW was most suited for 1.55 μm (0.8 eV) GaAs-based photonic applications.
Moving charged particles in lattice Boltzmann-based electrokinetics.
Kuron, Michael; Rempfer, Georg; Schornbaum, Florian; Bauer, Martin; Godenschwager, Christian; Holm, Christian; de Graaf, Joost
2016-12-07
The motion of ionic solutes and charged particles under the influence of an electric field and the ensuing hydrodynamic flow of the underlying solvent is ubiquitous in aqueous colloidal suspensions. The physics of such systems is described by a coupled set of differential equations, along with boundary conditions, collectively referred to as the electrokinetic equations. Capuani et al. [J. Chem. Phys. 121, 973 (2004)] introduced a lattice-based method for solving this system of equations, which builds upon the lattice Boltzmann algorithm for the simulation of hydrodynamic flow and exploits computational locality. However, thus far, a description of how to incorporate moving boundary conditions into the Capuani scheme has been lacking. Moving boundary conditions are needed to simulate multiple arbitrarily moving colloids. In this paper, we detail how to introduce such a particle coupling scheme, based on an analogue to the moving boundary method for the pure lattice Boltzmann solver. The key ingredients in our method are mass and charge conservation for the solute species and a partial-volume smoothing of the solute fluxes to minimize discretization artifacts. We demonstrate our algorithm's effectiveness by simulating the electrophoresis of charged spheres in an external field; for a single sphere we compare to the equivalent electro-osmotic (co-moving) problem. Our method's efficiency and ease of implementation should prove beneficial to future simulations of the dynamics in a wide range of complex nanoscopic and colloidal systems that were previously inaccessible to lattice-based continuum algorithms.
Sim, Hasung; Lee, Seongsu; Hong, Kun-Pyo; Jeong, Jaehong; Zhang, J. R.; Kamiyama, T.; Adroja, D. T.; Murray, C. A.; Thompson, S. P.; Iga, F.; Ji, S.; Khomskii, D.; Park, Je-Geun
2016-11-01
Dy B4 has a two-dimensional Shastry-Sutherland (Sh-S) lattice with strong Ising character of the Dy ions. Despite the intrinsic frustrations, it undergoes two successive transitions: a magnetic ordering at TN=20 K and a quadrupole ordering at TQ=12.5 K . From high-resolution neutron and synchrotron x-ray powder diffraction studies, we have obtained full structural information on this material in all phases and demonstrate that structural modifications occurring at quadrupolar transition lead to the lifting of frustrations inherent in the Sh-S model. Our paper thus provides a complete experimental picture of how the intrinsic frustration of the Sh-S lattice can be lifted by the coupling to quadrupole moments. We show that two other factors, i.e., strong spin-orbit coupling and long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in metallic Dy B4 , play an important role in this behavior.
Campos, R G; Campos, Rafael G.; Tututi, Eduardo S.
2002-01-01
It is shown that the nonlocal Dirac operator yielded by a lattice model that preserves chiral symmetry and uniqueness of fields, approaches to an ultralocal and invariant under translations operator when the size of the lattice tends to zero.