WorldWideScience

Sample records for nonlocal terms based

  1. Non-local gravity with a Weyl-square term

    CERN Document Server

    Cusin, Giulia; Maggiore, Michele; Mancarella, Michele

    2016-01-01

    Recent work has shown that modifications of General Relativity based on the addition of a non-local term $R\\,\\Box^{-2}R$ produce a dynamical model of dark energy, which is cosmologically viable both at the background level and at the level of cosmological perturbations. We explore a more general class of models based on the addition of terms proportional to $R_{\\mu\

  2. Explaination of nonlocal granular fluidity in terms of microscopic fluctuations

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    A recently proposed granular constitutive law has shown capability to predict nonlocal granular rheology using a variable denoted ``granular fluidity''. This work is aimed at finding the microscopic physical meaning of fluidity in terms of fluctuations such as fluctuation of normalized shear stress and fluctuation of velocity. We try to predict the fluidity as a function of the fluctuation of normalized shear stress, and also test Eyring equation and kinetic theory based on the theoretical prediction proposed in other work. We find a consistent definition for the fluidity to be proportional to the product of the velocity fluctuations and some function of packing fraction divided by the average diameter of the grains. This definition shows predictive ability in multiple geometries for which flow behavior is nonlocal. It is notable that the fluidity is well-defined as a function of kinematic state variables, as one would hope for a quantity of this nature.

  3. Sparse representation based image interpolation with nonlocal autoregressive modeling.

    Science.gov (United States)

    Dong, Weisheng; Zhang, Lei; Lukac, Rastislav; Shi, Guangming

    2013-04-01

    Sparse representation is proven to be a promising approach to image super-resolution, where the low-resolution (LR) image is usually modeled as the down-sampled version of its high-resolution (HR) counterpart after blurring. When the blurring kernel is the Dirac delta function, i.e., the LR image is directly down-sampled from its HR counterpart without blurring, the super-resolution problem becomes an image interpolation problem. In such cases, however, the conventional sparse representation models (SRM) become less effective, because the data fidelity term fails to constrain the image local structures. In natural images, fortunately, many nonlocal similar patches to a given patch could provide nonlocal constraint to the local structure. In this paper, we incorporate the image nonlocal self-similarity into SRM for image interpolation. More specifically, a nonlocal autoregressive model (NARM) is proposed and taken as the data fidelity term in SRM. We show that the NARM-induced sampling matrix is less coherent with the representation dictionary, and consequently makes SRM more effective for image interpolation. Our extensive experimental results demonstrate that the proposed NARM-based image interpolation method can effectively reconstruct the edge structures and suppress the jaggy/ringing artifacts, achieving the best image interpolation results so far in terms of PSNR as well as perceptual quality metrics such as SSIM and FSIM.

  4. Learning-Based Video Superresolution Reconstruction Using Spatiotemporal Nonlocal Similarity

    Directory of Open Access Journals (Sweden)

    Meiyu Liang

    2015-01-01

    Full Text Available Aiming at improving the video visual resolution quality and details clarity, a novel learning-based video superresolution reconstruction algorithm using spatiotemporal nonlocal similarity is proposed in this paper. Objective high-resolution (HR estimations of low-resolution (LR video frames can be obtained by learning LR-HR correlation mapping and fusing spatiotemporal nonlocal similarities between video frames. With the objective of improving algorithm efficiency while guaranteeing superresolution quality, a novel visual saliency-based LR-HR correlation mapping strategy between LR and HR patches is proposed based on semicoupled dictionary learning. Moreover, aiming at improving performance and efficiency of spatiotemporal similarity matching and fusion, an improved spatiotemporal nonlocal fuzzy registration scheme is established using the similarity weighting strategy based on pseudo-Zernike moment feature similarity and structural similarity, and the self-adaptive regional correlation evaluation strategy. The proposed spatiotemporal fuzzy registration scheme does not rely on accurate estimation of subpixel motion, and therefore it can be adapted to complex motion patterns and is robust to noise and rotation. Experimental results demonstrate that the proposed algorithm achieves competitive superresolution quality compared to other state-of-the-art algorithms in terms of both subjective and objective evaluations.

  5. Nonlocal means filter-based speckle tracking.

    Science.gov (United States)

    Afsham, Narges; Rasoulian, Abtin; Najafi, Mohammad; Abolmaesumi, Purang; Rohling, Robert

    2015-08-01

    The objective of sensorless freehand 3-D ultrasound imaging is to eliminate the need for additional tracking hardware and reduce cost and complexity. However, the accuracy of current out-of-plane pose estimation is main obstacle for full 6-degree-of-freedom (DoF) tracking. We propose a new filter-based speckle tracking framework to increase the accuracy of out-of-plane displacement estimation. In this framework, we use the displacement estimation not only for the specific speckle pattern, but for the entire image. We develop a nonlocal means (NLM) filter based on a probabilistic normal variance mixture model of ultrasound, known as Rician-inverse Gaussian (RiIG). To aggregate the local displacement estimations, Stein's unbiased risk estimate (SURE) is used as a quality measure of the estimations. We derive an explicit analytical form of SURE for the RiIG model and use it as a weight factor. The proposed filter-based speckle tracking framework is formulated and evaluated for three commonly used noise models, including the RiIG model. The out-of-plane estimations are compared with our previously proposed model-based algorithm in a set of ex vivo experiments for different tissue types. We show that the proposed RiIG filter-based method is more accurate and less tissue-dependent than the other methods. The proposed method is also evaluated in vivo on the spines of five different subjects to assess the feasibility of a clinical application. The 6-DoF transform parameters are estimated and compared with the electromagnetic tracker measurements. The results show higher tracking accuracy for typical small lateral displacements and tilt rotations between image pairs.

  6. Tensor decomposition and nonlocal means based spectral CT reconstruction

    Science.gov (United States)

    Zhang, Yanbo; Yu, Hengyong

    2016-10-01

    As one of the state-of-the-art detectors, photon counting detector is used in spectral CT to classify the received photons into several energy channels and generate multichannel projection simultaneously. However, the projection always contains severe noise due to the low counts in each energy channel. How to reconstruct high-quality images from photon counting detector based spectral CT is a challenging problem. It is widely accepted that there exists self-similarity over the spatial domain in a CT image. Moreover, because a multichannel CT image is obtained from the same object at different energy, images among channels are highly correlated. Motivated by these two characteristics of the spectral CT, we employ tensor decomposition and nonlocal means methods for spectral CT iterative reconstruction. Our method includes three basic steps. First, each channel image is updated by using the OS-SART. Second, small 3D volumetric patches (tensor) are extracted from the multichannel image, and higher-order singular value decomposition (HOSVD) is performed on each tensor, which can help to enhance the spatial sparsity and spectral correlation. Third, in order to employ the self-similarity in CT images, similar patches are grouped to reduce noise using the nonlocal means method. These three steps are repeated alternatively till the stopping criteria are met. The effectiveness of the developed algorithm is validated on both numerically simulated and realistic preclinical datasets. Our results show that the proposed method achieves promising performance in terms of noise reduction and fine structures preservation.

  7. Nonlocal gravity

    CERN Document Server

    Mashhoon, Bahram

    2017-01-01

    Relativity theory is based on a postulate of locality, which means that the past history of the observer is not directly taken into account. This book argues that the past history should be taken into account. In this way, nonlocality---in the sense of history dependence---is introduced into relativity theory. The deep connection between inertia and gravitation suggests that gravity could be nonlocal, and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein's theory of gravitation has recently been developed. A significant consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. According to nonlocal gravity theory, what astronomers attribute to dark matter should instead be due to the nonlocality of gravitation. Nonlocality dominates on the scale of galaxies and beyond. Memory fades with time; therefore, the nonlocal aspect of gravity becomes wea...

  8. A note on analytical solutions of nonlinear fractional 2D heat equation with non-local integral terms

    Indian Academy of Sciences (India)

    O S IYIOLA; F D ZAMAN

    2016-10-01

    In this paper, we consider the (2+1) nonlinear fractional heat equation with non-local integral terms and investigate two different cases of such non-local integral terms. The first has to do with the time-dependent non-local integral term and the second is the space-dependent non-local integral term. Apart from the nonlinear nature of these formulations, the complexity due to the presence of the non-local integral terms impelled us to use a relatively new analytical technique called q-homotopy analysis method to obtain analytical solutions to both cases in the form of convergent series with easily computable components. Our numerical analysis enables us to show the effects of non-local terms and the fractional-order derivative on the solutions obtained by this method.

  9. Magnified imaging based on non-Hermitian nonlocal cylindrical metasurfaces

    Science.gov (United States)

    Savoia, Silvio; Valagiannopoulos, Constantinos A.; Monticone, Francesco; Castaldi, Giuseppe; Galdi, Vincenzo; Alà, Andrea

    2017-03-01

    We show that a cylindrical lensing system composed of two metasurfaces with suitably tailored non-Hermitian (i.e., with distributed gain and loss) and nonlocal (i.e., spatially dispersive) properties can perform magnified imaging with reduced aberrations. More specifically, we analytically derive the idealized surface-impedance values that are required for "perfect" magnification and imaging and elucidate the role and implications of non-Hermiticity and nonlocality in terms of spatial resolution and practical implementation. For a basic demonstration, we explore some proof-of-principle quasilocal and multilayered implementations and independently validate the outcomes via full-wave numerical simulations. We also show that the metasurface frequency-dispersion laws can be chosen so as to ensure unconditional stability with respect to arbitrary temporal excitations. These results, which extend previous studies on planar configurations, may open intriguing venues in the design of metastructures for field imaging and processing.

  10. Nonlocality without inequality for almost all two-qubit entangled states based on Cabello's nonlocality argument

    Science.gov (United States)

    Kunkri, Samir; Choudhary, Sujit K.; Ahanj, Ali; Joag, Pramod

    2006-02-01

    Here we deal with a nonlocality argument proposed by Cabello, which is more general than Hardy’s nonlocality argument, but still maximally entangled states do not respond. However, for most of the other entangled states, maximum probability of success of this argument is more than that of the Hardy’s argument.

  11. Generalized non-local responses and higher harmonic retention in non-local polymerization driven diffusion model based simulations

    Science.gov (United States)

    Sheridan, J. T.; Kelly, J. V.; O'Brien, G.; Gleeson, M. R.; O'Neill, F. T.

    2004-12-01

    Non-local and non-linear models of photopolymer materials, which include diffusion effects, have recently received much attention in the literature. The material response is described as non-local as it is assumed that monomers are polymerized to form polymer chains and that these chains grow away from a point of initiation. The non-locality is defined in terms of a spatial non-local material response function. The material model is non-linear as a general non-linear material response to the incident light is included. Typically the numerical method of solution has involved retaining only up to four harmonics of the Fourier series of monomer concentration in the calculations. In this paper a general set of coupled first-order differential equations is derived which allow the inclusion of a higher number of harmonics. The resulting effect on the convergence of the algorithm, as the number of harmonics retained is increased, is investigated. Special care is taken to note the effect of physical parameters, i.e. the non-local material variance σ, the power-law degree k, and the rates of diffusion, D, and polymerization, F0.

  12. Axial vibration analysis of nanocones based on nonlocal elasticity theory

    Institute of Scientific and Technical Information of China (English)

    Shu-Qi Guo; Shao-Pu Yang

    2012-01-01

    Carbon nanocones have quite fascinating electronic and structural properties,whose axial vibration is seldom investigated in previous studies.In this paper,based on a nonlocal elasticity theory,a nonuniform rod model is applied to investigate the small-scale effect and the nonuniform effect on axial vibration of nanocones.Using the modified Wentzel-Brillouin-Kramers (WBK) method,an asymptotic solution is obtained for the axial vibration of general nonuniform nanorods.Then,using similar procedure,the axial vibration of nanocones is analyzed for nonuniform parameters,mode number and nonlocal parameters.Explicit expressions are derived for mode frequencies of clamped-clamped and clamped-free boundary conditions.It is found that axial vibration frequencies are highly overestimated by the classical rod model because of ignorance of the effect of small length scale.

  13. Nonlocality without inequalities for two-qubit mixed states based on Cabello's nonlocality [rapid communication

    Science.gov (United States)

    Liang, Lin-mei; Li, Cheng-zu

    2005-02-01

    This Letter presents nonlocality without inequalities for two-qubit mixed states. This Letter was mainly sparked by Cabello's work [Phys. Rev. A 65 (2003) 032108] and is an extension of our recent work [Phys. Lett. A 318 (2003) 300].

  14. Non-local potentials with LS terms in algebraic scattering theory

    Energy Technology Data Exchange (ETDEWEB)

    Levay, Peter [Department of Theoretical Physics, Institute of Physics, Technical University of Budapest, Budapest (Hungary)

    1997-10-21

    The group theoretical analysis of Coulomb scattering based on the SO(3,1) group is revisited. Using matrix-valued differential operators, modifying the angular momentum and the Runge-Lenz vector used hitherto for the realization of the so(3,1) (Lorentz) algebra, we obtain a three-dimensional solvable two-channel scattering problem. The interaction term besides the Coulomb potential contains a non-local potential of LS-type. Using the momentum representation the S-matrix can be calculated analytically. By employing a canonical transformation, another solvable three-dimensional scattering problem is found, in agreement with the expectations of algebraic scattering theory. The potential in this case is of Poeschl-Teller type with an LS term. It is also pointed out that our matrix-valued realization of the so(3,1) algebra can be cast to an instructive form with the help of su(2) gauge fields. An interesting connection between gauge transformations and supersymmetry transformations of supersymmetric quantum mechanics is also observed. These results enable us to construct other solvable scattering problems by using su(2) gauge transformations. (author)

  15. Structure Group and Fermion-Mass-Term in General Nonlocality

    CERN Document Server

    Han, Lei

    2015-01-01

    In our previous work [J. Math. Phys. 49, 033513 (2008)] two problems remain to be resolved. One is that we lack a minimal group to replace GL(4,C), the other is that the Equation of Motion (EoM) for fermion has no mass term. After careful investigation we find these two problems are linked by conformal group, a subgroup of GL(4,C) group. The Weyl group, a subgroup of conformal group, can bring about the running of mass, charge etc. while making it responsible for the transformation of interaction vertex. However, once concerning the generation of the mass term in EoM, we have to resort to the whole conformal group, in which the generators $K_\\mu $ play a crucial role in making vacuum vary from space-like (or light-cone-like)to time-like. Physically the starting points are our previous conclusion, $\\vec E^2-\\vec B^2\

  16. A nonlocal, ordinary, state-based plasticity model for peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony

    2011-05-01

    An implicit time integration algorithm for a non-local, state-based, peridynamics plasticity model is developed. The flow rule was proposed in [3] without an integration strategy or yield criterion. This report addresses both of these issues and thus establishes the first ordinary, state-based peridynamics plasticity model. Integration of the flow rule follows along the lines of the classical theories of rate independent J{sub 2} plasticity. It uses elastic force state relations, an additive decomposition of the deformation state, an elastic force state domain, a flow rule, loading/un-loading conditions, and a consistency condition. Just as in local theories of plasticity (LTP), state variables are required. It is shown that the resulting constitutive model does not violate the 2nd law of thermodynamics. The report also develops a useful non-local yield criterion that depends upon the yield stress and horizon for the material. The modulus state for both the ordinary elastic material and aforementioned plasticity model is also developed and presented.

  17. Fast Non-Local Means Algorithm Based on Krawtchouk Moments

    Institute of Scientific and Technical Information of China (English)

    吴一全; 戴一冕; 殷骏; 吴健生

    2015-01-01

    Non-local means (NLM)method is a state-of-the-art denoising algorithm, which replaces each pixel with a weighted average of all the pixels in the image. However, the huge computational complexity makes it impractical for real applications. Thus, a fast non-local means algorithm based on Krawtchouk moments is proposed to improve the denoising performance and reduce the computing time. Krawtchouk moments of each image patch are calculated and used in the subsequent similarity measure in order to perform a weighted averaging. Instead of computing the Euclid-ean distance of two image patches, the similarity measure is obtained by low-order Krawtchouk moments, which can reduce a lot of computational complexity. Since Krawtchouk moments can extract local features and have a good anti-noise ability, they can classify the useful information out of noise and provide an accurate similarity measure. Detailed experiments demonstrate that the proposed method outperforms the original NLM method and other moment-based methods according to a comprehensive consideration on subjective visual quality, method noise, peak signal to noise ratio (PSNR), structural similarity (SSIM) index and computing time. Most importantly, the proposed method is around 35 times faster than the original NLM method.

  18. Small scale effects on the mechanical behaviors of protein microtubules based on the nonlocal elasticity theory

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yuanwen, E-mail: ywgao@lzu.edu.cn [Key Laboratory of Mechanics on Western Disaster and Environment, Ministry of Education, Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000 (China); Lei, Fang-Ming [Key Laboratory of Mechanics on Western Disaster and Environment, Ministry of Education, Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000 (China)

    2009-09-25

    Based on the nonlocal elastic theory, small scale effects are considered in the investigation of the mechanical properties of protein microtubules. A new prediction formula for the persistence lengths of microtubules with the consideration of the small scale effect is presented. Subsequently, the buckling of microtubules is studied based on a nonlocal elastic beam model. The predicted results of our model indicate that the length-dependence of persistence length is related not only to the shear terms, but also to the small scale effect. The Eular beam model, which is always considered unable to explain the length-dependence of microtubules, can capture the length-dependence of the persistence length of microtubules with the consideration of the small scale effect. The elastic buckling behaviors of microtubules in viscoelastic surrounding cytoplasm are also considered using the nonlocal Timoshenko beam model in this paper, and the results indicate that the small scale effect of microtubules also plays an important role in the buckling of microtubules.

  19. Resonance frequency and mass identification of zeptogram-scale nanosensor based on the nonlocal beam theory.

    Science.gov (United States)

    Li, Xian-Fang; Tang, Guo-Jin; Shen, Zhi-Bin; Lee, Kang Yong

    2015-01-01

    Free vibration and mass detection of carbon nanotube-based sensors are studied in this paper. Since the mechanical properties of carbon nanotubes possess a size effect, the nonlocal beam model is used to characterize flexural vibration of nanosensors carrying a concentrated nanoparticle, where the size effect is reflected by a nonlocal parameter. For nanocantilever or bridged sensor, frequency equations are derived when a nanoparticle is carried at the free end or the middle, respectively. Exact resonance frequencies are numerically determined for clamped-free, simply-supported, and clamped-clamped resonators. Alternative approximations of fundamental frequency are given in closed form within the relative error less than 0.4%, 0.6%, and 1.4% for cantilever, simply-supported, and bridged sensors, respectively. Mass identification formulae are derived in terms of the frequency shift. Identified masses via the present approach coincide with those using the molecular mechanics approach and reach as low as 10(-24)kg. The obtained results indicate that the nonlocal effect decreases the resonance frequency except for the fundamental frequency of nanocantilever sensor. These results are helpful to the design of micro/nanomechanical zeptogram-scale biosensor.

  20. Entanglement-based quantum communication secured by nonlocal dispersion cancellation

    Science.gov (United States)

    Lee, Catherine; Zhang, Zheshen; Steinbrecher, Gregory R.; Zhou, Hongchao; Mower, Jacob; Zhong, Tian; Wang, Ligong; Hu, Xiaolong; Horansky, Robert D.; Verma, Varun B.; Lita, Adriana E.; Mirin, Richard P.; Marsili, Francesco; Shaw, Matthew D.; Nam, Sae Woo; Wornell, Gregory W.; Wong, Franco N. C.; Shapiro, Jeffrey H.; Englund, Dirk

    2014-12-01

    Quantum key distribution (QKD) enables participants to exchange secret information over long distances with unconditional security. However, the performance of today's QKD systems is subject to hardware limitations, such as those of available nonclassical-light sources and single-photon detectors. By encoding photons in high-dimensional states, the rate of generating secure information under these technical constraints can be maximized. Here, we demonstrate a complete time-energy entanglement-based QKD system with proven security against the broad class of arbitrary collective attacks. The security of the system is based on nonlocal dispersion cancellation between two time-energy entangled photons. This resource-efficient QKD system is implemented at telecommunications wavelength, is suitable for optical fiber and free-space links, and is compatible with wavelength-division multiplexing.

  1. Surface effects on the vibration behavior of flexoelectric nanobeams based on nonlocal elasticity theory

    Science.gov (United States)

    Ebrahimi, Farzad; Reza Barati, Mohammad

    2017-01-01

    In this research, vibration characteristics of a flexoelectric nanobeam in contact with Winkler-Pasternak foundation is investigated based on the nonlocal elasticity theory considering surface effects. This nonclassical nanobeam model contains flexoelectric effect to capture coupling of strain gradients and electrical polarizations. Moreover, the nonlocal elasticity theory is employed to study the nonlocal and long-range interactions between the particles. The present model can degenerate into the classical model if the nonlocal parameter, flexoelectric and surface effects are omitted. Hamilton's principle is employed to derive the governing equations and the related boundary conditions which are solved applying a Galerkin-based solution. Natural frequencies are verified with those of previous papers on nanobeams. It is illustrated that flexoelectricity, nonlocality, surface stresses, elastic foundation and boundary conditions affects considerably the vibration frequencies of piezoelectric nanobeams.

  2. A Correlation Based Strategy for the Acceleration of Nonlocal Means Filtering Algorithm

    Directory of Open Access Journals (Sweden)

    Junfeng Zhang

    2016-01-01

    Full Text Available Although the nonlocal means (NLM algorithm takes a significant step forward in image filtering field, it suffers from a high computational complexity. To deal with this drawback, this paper proposes an acceleration strategy based on a correlation operation. Instead of per-pixel processing, this approach performs a simultaneous calculation of all the image pixels with the help of correlation operators. Complexity analysis and experimental results are reported and show the advantage of the proposed algorithm in terms of computation and time cost.

  3. Surface effects on static bending of nanowires based on non-local elasticity theory

    Directory of Open Access Journals (Sweden)

    Quan Wu

    2015-10-01

    Full Text Available The surface elasticity and non-local elasticity effects on the elastic behavior of statically bent nanowires are investigated in the present investigation. Explicit solutions are presented to evaluate the surface stress and non-local elasticity effects with various boundary conditions. Compared with the classical Euler beam, a nanowire with surface stress and/or non-local elasticity can be either stiffer or less stiff, depending on the boundary conditions. The concept of surface non-local elasticity was proposed and its physical interpretation discussed to explain the combined effect of surface elasticity and non-local elasticity. The effect of the nanowire size on its elastic bending behavior was investigated. The results obtained herein are helpful to characterize mechanical properties of nanowires and aid nanowire-based devices design.

  4. Shear deformable deformation of carbon nanotubes based on a new analytical nonlocal Timoshenko beam nodel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianming; Yang, Yang [Department of Engineering Mechanics, Kunming University of Science and Technology, Kunming 650051, Yunnan (China)

    2015-03-10

    According to Hamilton’s principle, a new mathematical model and analytical solutions for nonlocal Timoshenko beam model (ANT) is established based on nonlocal elastic continuum theory when shear deformation and nonlocal effect are considered. The new ANT equilibrium equations and boundary conditions are derived for bending analysis of carbon nanotubes (CNTs) with simply supported, clamped and cantilever. The ANT deflection solutions demonstrate that the CNT stiffness is enhanced by the presence of nonlocal stress effects. Furthermore, the new ANT model concluded verifiable bending behaviors for a cantilever CNT with point load at the free end, which depends on the strength of nonlocal stress. Therefore, this new model will gives a better prediction for mechanical behaviors of nanostructures.

  5. Nonlocal Means-Based Denoising for Medical Images

    Directory of Open Access Journals (Sweden)

    Ke Lu

    2012-01-01

    Full Text Available Medical images often consist of low-contrast objects corrupted by random noise arising in the image acquisition process. Thus, image denoising is one of the fundamental tasks required by medical imaging analysis. Nonlocal means (NL-means method provides a powerful framework for denoising. In this work, we investigate an adaptive denoising scheme based on the patch NL-means algorithm for medical imaging denoising. In contrast with the traditional NL-means algorithm, the proposed adaptive NL-means denoising scheme has three unique features. First, we use a restricted local neighbourhood where the true intensity for each noisy pixel is estimated from a set of selected neighbouring pixels to perform the denoising process. Second, the weights used are calculated thanks to the similarity between the patch to denoise and the other patches candidates. Finally, we apply the steering kernel to preserve the details of the images. The proposed method has been compared with similar state-of-art methods over synthetic and real clinical medical images showing an improved performance in all cases analyzed.

  6. Variational principles for transversely vibrating multiwalled carbon nanotubes based on nonlocal Euler-Bernoulli beam model.

    Science.gov (United States)

    Adali, Sarp

    2009-05-01

    Variational principles are derived for multiwalled carbon nanotubes undergoing vibrations. Derivations are based on the continuum modeling with the Euler-Bernoulli beam representing the nanotubes and small scale effects taken into account via the nonlocal elastic theory. Hamilton's principle for multiwalled nanotubes is given and Rayleigh's quotient for the frequencies is derived for nanotubes undergoing free vibrations. Natural and geometric boundary conditions are derived which lead to a set of coupled boundary conditions due to nonlocal effects.

  7. Frequency Shift of Carbon-Nanotube-Based Mass Sensor Using Nonlocal Elasticity Theory

    Directory of Open Access Journals (Sweden)

    Lee Haw-Long

    2010-01-01

    Full Text Available Abstract The frequency equation of carbon-nanotube-based cantilever sensor with an attached mass is derived analytically using nonlocal elasticity theory. According to the equation, the relationship between the frequency shift of the sensor and the attached mass can be obtained. When the nonlocal effect is not taken into account, the variation of frequency shift with the attached mass on the sensor is compared with the previous study. According to this study, the result shows that the frequency shift of the sensor increases with increasing the attached mass. When the attached mass is small compared with that of the sensor, the nonlocal effect is obvious and increasing nonlocal parameter decreases the frequency shift of the sensor. In addition, when the location of the attached mass is closer to the free end, the frequency shift is more significant and that makes the sensor reveal more sensitive. When the attached mass is small, a high sensitivity is obtained.

  8. A Sparsity-Based InSAR Phase Denoising Algorithm Using Nonlocal Wavelet Shrinkage

    Directory of Open Access Journals (Sweden)

    Dongsheng Fang

    2016-10-01

    Full Text Available An interferometric synthetic aperture radar (InSAR phase denoising algorithm using the local sparsity of wavelet coefficients and nonlocal similarity of grouped blocks was developed. From the Bayesian perspective, the double- l 1 norm regularization model that enforces the local and nonlocal sparsity constraints was used. Taking advantages of coefficients of the nonlocal similarity between group blocks for the wavelet shrinkage, the proposed algorithm effectively filtered the phase noise. Applying the method to simulated and acquired InSAR data, we obtained satisfactory results. In comparison, the algorithm outperformed several widely-used InSAR phase denoising approaches in terms of the number of residues, root-mean-square errors and other edge preservation indexes.

  9. Radial vibration of free anisotropic nanoparticles based on nonlocal continuum mechanics.

    Science.gov (United States)

    Ghavanloo, Esmaeal; Fazelzadeh, S Ahmad

    2013-02-22

    Radial vibration of spherical nanoparticles made of materials with anisotropic elasticity is theoretically investigated using nonlocal continuum mechanics. The anisotropic elastic model is reformulated using the nonlocal differential constitutive relations of Eringen. The nonlocal differential equation of radial motion is derived in terms of radial displacement. Cubic, hexagonal, trigonal and tetragonal symmetries of the elasticity are discussed. The suggested model is justified by a good agreement between the results given by the present model and available experimental data. Furthermore, the model is used to elucidate the effect of small scale on the vibration of several nanoparticles. Our results show that the small scale is essential for the radial vibration of the nanoparticles when the nanoparticle radius is smaller than 1.5 nm.

  10. Multi-atlas labeling with population-specific template and non-local patch-based label fusion

    DEFF Research Database (Denmark)

    Fonov, Vladimir; Coupé, Pierrick; Eskildsen, Simon Fristed;

    We propose a new method combining a population-specific nonlinear template atlas approach with non-local patch-based structure segmentation for whole brain segmentation into individual structures. This way, we benefit from the efficient intensity-driven segmentation of the non-local means framework...

  11. Nonlocal continuum-based modeling of mechanical characteristics of nanoscopic structures

    Energy Technology Data Exchange (ETDEWEB)

    Rafii-Tabar, Hashem, E-mail: rafii-tabar@nano.ipm.ac.ir [Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ghavanloo, Esmaeal, E-mail: ghavanloo@shirazu.ac.ir [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Fazelzadeh, S. Ahmad [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of)

    2016-06-06

    Insight into the mechanical characteristics of nanoscopic structures is of fundamental interest and indeed poses a great challenge to the research communities around the world. These structures are ultra fine in size and consequently performing standard experiments to measure their various properties is an extremely difficult and expensive endeavor. Hence, to predict the mechanical characteristics of the nanoscopic structures, different theoretical models, numerical modeling techniques, and computer-based simulation methods have been developed. Among several proposed approaches, the nonlocal continuum-based modeling is of particular significance because the results obtained from this modeling for different nanoscopic structures are in very good agreement with the data obtained from both experimental and atomistic-based studies. A review of the essentials of this model together with its applications is presented here. Our paper is a self contained presentation of the nonlocal elasticity theory and contains the analysis of the recent works employing this model within the field of nanoscopic structures. In this review, the concepts from both the classical (local) and the nonlocal elasticity theories are presented and their applications to static and dynamic behavior of nanoscopic structures with various morphologies are discussed. We first introduce the various nanoscopic structures, both carbon-based and non carbon-based types, and then after a brief review of the definitions and concepts from classical elasticity theory, and the basic assumptions underlying size-dependent continuum theories, the mathematical details of the nonlocal elasticity theory are presented. A comprehensive discussion on the nonlocal version of the beam, the plate and the shell theories that are employed in modeling of the mechanical properties and behavior of nanoscopic structures is then provided. Next, an overview of the current literature discussing the application of the nonlocal models

  12. Nonlocal continuum-based modeling of mechanical characteristics of nanoscopic structures

    Science.gov (United States)

    Rafii-Tabar, Hashem; Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad

    2016-06-01

    Insight into the mechanical characteristics of nanoscopic structures is of fundamental interest and indeed poses a great challenge to the research communities around the world. These structures are ultra fine in size and consequently performing standard experiments to measure their various properties is an extremely difficult and expensive endeavor. Hence, to predict the mechanical characteristics of the nanoscopic structures, different theoretical models, numerical modeling techniques, and computer-based simulation methods have been developed. Among several proposed approaches, the nonlocal continuum-based modeling is of particular significance because the results obtained from this modeling for different nanoscopic structures are in very good agreement with the data obtained from both experimental and atomistic-based studies. A review of the essentials of this model together with its applications is presented here. Our paper is a self contained presentation of the nonlocal elasticity theory and contains the analysis of the recent works employing this model within the field of nanoscopic structures. In this review, the concepts from both the classical (local) and the nonlocal elasticity theories are presented and their applications to static and dynamic behavior of nanoscopic structures with various morphologies are discussed. We first introduce the various nanoscopic structures, both carbon-based and non carbon-based types, and then after a brief review of the definitions and concepts from classical elasticity theory, and the basic assumptions underlying size-dependent continuum theories, the mathematical details of the nonlocal elasticity theory are presented. A comprehensive discussion on the nonlocal version of the beam, the plate and the shell theories that are employed in modeling of the mechanical properties and behavior of nanoscopic structures is then provided. Next, an overview of the current literature discussing the application of the nonlocal models

  13. Spiking cortical model based non-local means method for despeckling multiframe optical coherence tomography data

    Science.gov (United States)

    Gu, Yameng; Zhang, Xuming

    2017-05-01

    Optical coherence tomography (OCT) images are severely degraded by speckle noise. Existing methods for despeckling multiframe OCT data cannot deliver sufficient speckle suppression while preserving image details well. To address this problem, the spiking cortical model (SCM) based non-local means (NLM) method has been proposed in this letter. In the proposed method, the considered frame and two neighboring frames are input into three SCMs to generate the temporal series of pulse outputs. The normalized moment of inertia (NMI) of the considered patches in the pulse outputs is extracted to represent the rotational and scaling invariant features of the corresponding patches in each frame. The pixel similarity is computed based on the Euclidean distance between the NMI features and used as the weight. Each pixel in the considered frame is restored by the weighted averaging of all pixels in the pre-defined search window in the three frames. Experiments on the real multiframe OCT data of the pig eye demonstrate the advantage of the proposed method over the frame averaging method, the multiscale sparsity based tomographic denoising method, the wavelet-based method and the traditional NLM method in terms of visual inspection and objective metrics such as signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), equivalent number of looks (ENL) and cross-correlation (XCOR).

  14. Dynamic stability of functionally graded nanobeam based on nonlocal Timoshenko theory considering surface effects

    Science.gov (United States)

    Saffari, Shahab; Hashemian, Mohammad; Toghraie, Davood

    2017-09-01

    Based on nonlocal Timoshenko beam theory, dynamic stability of functionally graded (FG) nanobeam under axial and thermal loading was investigated. Surface stress effects were implemented according to Gurtin-Murdoch continuum theory. Using power law distribution for FGM and von Karman geometric nonlinearity, governing equations were derived based on Hamilton's principle. The developed nonlocal models have the capability of interpreting small scale effects. Pasternak elastic medium was employed to represent the interaction of the FG nanobeam and the surrounding elastic medium. A parametric study was conducted to focus influences of the static load factor, temperature change, gradient index, nonlocal parameter, slenderness ratio, surface effect and springs constants of the elastic medium on the dynamic instability region (DIR) of the FG beam with simply-supported boundary conditions. It was found that differences between DIRs predicted by local and nonlocal beam theories are significant for beams with lower aspect ratio. Moreover, it was observed that in contrast to high temperature environments, at low temperatures, increasing the temperature change moves the origin of the DIR to higher excitation frequency zone and leads to further stability. Considering surface stress effects shifts the DIR of FG beam to higher frequency zone, also increasing the gradient index enhances the frequency of DIR.

  15. Statistical image reconstruction for low-dose CT using nonlocal means-based regularization.

    Science.gov (United States)

    Zhang, Hao; Ma, Jianhua; Wang, Jing; Liu, Yan; Lu, Hongbing; Liang, Zhengrong

    2014-09-01

    Low-dose computed tomography (CT) imaging without sacrifice of clinical tasks is desirable due to the growing concerns about excessive radiation exposure to the patients. One common strategy to achieve low-dose CT imaging is to lower the milliampere-second (mAs) setting in data scanning protocol. However, the reconstructed CT images by the conventional filtered back-projection (FBP) method from the low-mAs acquisitions may be severely degraded due to the excessive noise. Statistical image reconstruction (SIR) methods have shown potentials to significantly improve the reconstructed image quality from the low-mAs acquisitions, wherein the regularization plays a critical role and an established family of regularizations is based on the Markov random field (MRF) model. Inspired by the success of nonlocal means (NLM) in image processing applications, in this work, we propose to explore the NLM-based regularization for SIR to reconstruct low-dose CT images from low-mAs acquisitions. Experimental results with both digital and physical phantoms consistently demonstrated that SIR with the NLM-based regularization can achieve more gains than SIR with the well-known Gaussian MRF regularization or the generalized Gaussian MRF regularization and the conventional FBP method, in terms of image noise reduction and resolution preservation.

  16. A Nonlocal TV-Based Variational Method for PolSAR Data Speckle Reduction.

    Science.gov (United States)

    Nie, Xiangli; Qiao, Hong; Zhang, Bo; Huang, Xiayuan

    2016-05-01

    In this paper, we propose a nonlocal total variation (NLTV)-based variational model for polarimetric synthetic aperture radar (PolSAR) data speckle reduction. This model, named WisNLTV, is obtained based on the Wishart fidelity term and the NLTV regularization defined for the complex-valued fourth-order tensor data. Since the proposed model is non-convex, an equivalent bi-convex model is obtained using the property of conjugate functions. Then, an efficient iteration algorithm is developed to solve the equivalent bi-convex model, based on the alternating minimization and the forward-backward operator splitting technique. The proposed iteration algorithm is proved to be convergent under certain conditions theoretically and numerically. Experimental results on both synthetic and real PolSAR data demonstrate that the proposed method can effectively reduce speckle noise and, meanwhile, better preserve the details and the repetitive structures such as textures and edges, and the polarimetric scattering characteristics, compared with the other methods.

  17. Seismic data filtering using non-local means algorithm based on structure tensor

    Science.gov (United States)

    Yang, Shuai; Chen, Anqing; Chen, Hongde

    2017-05-01

    Non-Local means algorithm is a new and effective filtering method. It calculates weights of all similar neighborhoods' center points relative to filtering point within searching range by Gaussian weighted Euclidean distance between neighborhoods, then gets filtering point's value by weighted average to complete the filtering operation. In this paper, geometric distance of neighborhood's center point is taken into account in the distance measure calculation, making the non-local means algorithm more reasonable. Furthermore, in order to better protect the geometry structure information of seismic data, we introduce structure tensor that can depict the local geometrical features of seismic data. The coherence measure, which reflects image local contrast, is extracted from the structure tensor, is integrated into the non-local means algorithm to participate in the weight calculation, the control factor of geometry structure similarity is added to form a non-local means filtering algorithm based on structure tensor. The experimental results prove that the algorithm can effectively restrain noise, with strong anti-noise and amplitude preservation effect, improving PSNR and protecting structure information of seismic image. The method has been successfully applied in seismic data processing, indicating that it is a new and effective technique to conduct the structure-preserved filtering of seismic data.

  18. Non-Local Fractional Differential-Based Approach for Image Enhancement

    Directory of Open Access Journals (Sweden)

    Da-Li Chen

    2013-09-01

    Full Text Available This study proposed an image enhancing method which is based on the non-local fractional order differential operator. In this method, a matrix form representation of discrete fractional order differentiation is introduced to enhance the digital image, which is effective to reduce the computation error caused by the traditional local approximate method of the fractional order differentiation. The proposed enhancing method is able to make effective use of the whole image information and improve the enhancing performance of the image enhancing algorithm based on the local mask. The color image enhancing strategy based on the non-local fractional differential also is given. A lot of experiments demonstrate that the proposed method is capable of enhancing gray and color image effectively.

  19. Retinal Image Graph-Cut Segmentation Algorithm Using Multiscale Hessian-Enhancement-Based Nonlocal Mean Filter

    OpenAIRE

    Jian Zheng; Pei-Rong Lu; Dehui Xiang; Ya-Kang Dai; Zhao-Bang Liu; Duo-Jie Kuai; Hui Xue; Yue-Tao Yang

    2013-01-01

    We propose a new method to enhance and extract the retinal vessels. First, we employ a multiscale Hessian-based filter to compute the maximum response of vessel likeness function for each pixel. By this step, blood vessels of different widths are significantly enhanced. Then, we adopt a nonlocal mean filter to suppress the noise of enhanced image and maintain the vessel information at the same time. After that, a radial gradient symmetry transformation is adopted to suppress the nonvessel str...

  20. Accurate and efficient computation of nonlocal potentials based on Gaussian-sum approximation

    OpenAIRE

    Exl, Lukas; Mauser, Norbert J.; Yong ZHANG

    2015-01-01

    We introduce an accurate and efficient method for a class of nonlocal potential evaluations with free boundary condition, including the 3D/2D Coulomb, 2D Poisson and 3D dipolar potentials. Our method is based on a Gaussian-sum approximation of the singular convolution kernel and Taylor expansion of the density. Starting from the convolution formulation, for smooth and fast decaying densities, we make a full use of the Fourier pseudospectral (plane wave) approximation of the density and a sepa...

  1. Static analysis of rectangular nanoplates using trigonometric shear deformation theory based on nonlocal elasticity theory.

    Science.gov (United States)

    Nami, Mohammad Rahim; Janghorban, Maziar

    2013-12-30

    In this article, a new higher order shear deformation theory based on trigonometric shear deformation theory is developed. In order to consider the size effects, the nonlocal elasticity theory is used. An analytical method is adopted to solve the governing equations for static analysis of simply supported nanoplates. In the present theory, the transverse shear stresses satisfy the traction free boundary conditions of the rectangular plates and these stresses can be calculated from the constitutive equations. The effects of different parameters such as nonlocal parameter and aspect ratio are investigated on both nondimensional deflections and deflection ratios. It may be important to mention that the present formulations are general and can be used for isotropic, orthotropic and anisotropic nanoplates.

  2. Static analysis of rectangular nanoplates using trigonometric shear deformation theory based on nonlocal elasticity theory

    Directory of Open Access Journals (Sweden)

    Mohammad Rahim Nami

    2013-12-01

    Full Text Available In this article, a new higher order shear deformation theory based on trigonometric shear deformation theory is developed. In order to consider the size effects, the nonlocal elasticity theory is used. An analytical method is adopted to solve the governing equations for static analysis of simply supported nanoplates. In the present theory, the transverse shear stresses satisfy the traction free boundary conditions of the rectangular plates and these stresses can be calculated from the constitutive equations. The effects of different parameters such as nonlocal parameter and aspect ratio are investigated on both nondimensional deflections and deflection ratios. It may be important to mention that the present formulations are general and can be used for isotropic, orthotropic and anisotropic nanoplates.

  3. Vibration analysis of single-walled carbon peapods based on nonlocal Timoshenko beam theory

    Science.gov (United States)

    Ghadiri, Majid; Hajbarati, Hamid; Safi, Mohsen

    2017-04-01

    In this article, vibration behavior of single-walled carbon nanotube encapsulating C60 molecules is studied using the Eringen's nonlocal elasticity theory within the frame work of Timoshenko beam theory. The governing equation and boundary conditions are derived using Hamilton's principle. It is considered that the nanopeapod is embedded in an elastic medium and the C60 molecules are modeled as lumped masses attached to the nanobeam. The Galerkin's method is applied to determine the natural frequency of the nanobeam with clamped-clamped boundary conditions. Effects of nonlocality, foundation stiffness, and ratio of the fullerenes' mass to the nanotube's mass on the natural frequencies are investigated. In addition, by vanishing effects of shear deformation and rotary inertia, the results based on Euler-Bernoulli beam theory are presented.

  4. Approximate Sparsity and Nonlocal Total Variation Based Compressive MR Image Reconstruction

    Directory of Open Access Journals (Sweden)

    Chengzhi Deng

    2014-01-01

    Full Text Available Recent developments in compressive sensing (CS show that it is possible to accurately reconstruct the magnetic resonance (MR image from undersampled k-space data by solving nonsmooth convex optimization problems, which therefore significantly reduce the scanning time. In this paper, we propose a new MR image reconstruction method based on a compound regularization model associated with the nonlocal total variation (NLTV and the wavelet approximate sparsity. Nonlocal total variation can restore periodic textures and local geometric information better than total variation. The wavelet approximate sparsity achieves more accurate sparse reconstruction than fixed wavelet l0 and l1 norm. Furthermore, a variable splitting and augmented Lagrangian algorithm is presented to solve the proposed minimization problem. Experimental results on MR image reconstruction demonstrate that the proposed method outperforms many existing MR image reconstruction methods both in quantitative and in visual quality assessment.

  5. Viscoelastic wave propagation in the viscoelastic single walled carbon nanotubes based on nonlocal strain gradient theory

    Science.gov (United States)

    Tang, Yugang; Liu, Ying; Zhao, Dong

    2016-10-01

    In this paper, the viscoelastic wave propagation in an embedded viscoelastic single-walled carbon nanotube (SWCNT) is studied based on the nonlocal strain gradient theory. The characteristic equation for the viscoelastic wave in SWCNTs is derived. The emphasis is placed on the influence of the tube diameter on the viscoelastic wave dispersion. A blocking diameter is observed, above which the wave could not propagate in SWCNTs. The results show that the blocking diameter is greatly dependent on the damping coefficient, the nonlocal and the strain gradient length scale parameters, as well as the Winkler modulus of the surrounding elastic medium. These findings may provide a prospective application of SWCNTs in nanodevices and nanocomposites.

  6. State space approach for the vibration of nanobeams based on the nonlocal thermoelasticity theory without energy dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Zenkour, A. M.; Alnefaie, K. A.; Abu-Hamdeh, N. H.; Aljinaid, A. A.; Aifanti, E. C. [King Abdulaziz University, Jeddah (Saudi Arabia); Abouelregal, A. E. [Mansoura University, Mansoura (Egypt)

    2015-07-15

    In this article, an Euler-Bernoulli beam model based upon nonlocal thermoelasticity theory without energy dissipation is used to study the vibration of a nanobeam subjected to ramp-type heating. Classical continuum theory is inherently size independent, while nonlocal elasticity exhibits size dependence. Among other things, this leads to a new expression for the effective nonlocal bending moment as contrasted to its classical counterpart. The thermal problem is addressed in the context of the Green-Naghdi (GN) theory of heat transport without energy dissipation. The governing partial differential equations are solved in the Laplace transform domain by the state space approach of modern control theory. Inverse of Laplace transforms are computed numerically using Fourier expansion techniques. The effects of nonlocality and ramping time parameters on the lateral vibration, temperature, displacement and bending moment are discussed.

  7. Profile of Blow-up Solution to Hyperbolic System with Nonlocal Term

    Institute of Scientific and Technical Information of China (English)

    Zhi Wen DUAN; Kwang Ik KIM

    2007-01-01

    This paper is concerned with a nonlocal hyperbolic system as follows:utt=△u+(∫Ωvdx)p for x∈RN,t>0, utt=△v+(∫Ωvdx)q for x∈RN,t>0,u(x,0)=u0(x),ut(x,0)=u01(x) for x∈RN,v(x,0)=u0(x),vt(x,0)=v01(x) for x∈RN,where 1 ≤ N ≤ 3, p ≥ 1, q ≥ 1 and pq > 1. Here the initial values are compactly supported andΩ(∈) RN is a bounded open region. The blow-up curve, blow-up rate and profile of the solution arediscussed.

  8. Thermo-Mechanical Vibration of Short Carbon Nanotubes Embedded in Pasternak Foundation Based on Nonlocal Elasticity Theory

    Directory of Open Access Journals (Sweden)

    B. Amirian

    2013-01-01

    Full Text Available This study is concerned with the thermal vibration analysis of a short single-walled carbon nanotube embedded in an elastic medium based on nonlocal Timoshenko beam model. A Winkler- and Pasternak-type elastic foundation is employed to model the interaction of short carbon nanotubes and the surrounding elastic medium. Influence of all parameters such as nonlocal small-scale effects, high temperature change, Winkler modulus parameter, Pasternak shear parameter, vibration mode and aspect ratio of short carbon nanotubes on the vibration frequency are analyzed and discussed. The present study shows that for high temperature changes, the effect of Winkler constant in different nonlocal parameters on nonlocal frequency is negligible. Furthermore, for all temperatures, the nonlocal frequencies are always smaller than the local frequencies in short carbon nanotubes. In addition, for high Pasternak modulus, by increasing the aspect ratio, the nonlocal frequency decreases. It is concluded that short carbon nanotubes have the higher frequencies as compared with long carbon nanotubes.

  9. Acausality in Nonlocal Gravity Theory

    CERN Document Server

    Zhang, Ying-li; Sasaki, Misao; Zhao, Gong-Bo

    2016-01-01

    We investigate the nonlocal gravity theory by deriving nonlocal equations of motion using the traditional variation principle in a homogeneous background. We focus on a class of models with a linear nonlocal modification term in the action. It is found that the resulting equations of motion contain the advanced Green's function, implying that there is an acausality problem. As a consequence, a divergence arises in the solutions due to contributions from the future infinity unless the Universe will go back to the radiation dominated era or become the Minkowski spacetime in the future. We also discuss the relation between the original nonlocal equations and its biscalar-tensor representation and identify the auxiliary fields with the corresponding original nonlocal terms. Finally, we show that the acusality problem cannot be avoided by any function of nonlocal terms in the action.

  10. Advanced numerical simulation based on a non-local micromorphic model for metal forming processes

    Directory of Open Access Journals (Sweden)

    Diamantopoulou Evangelia

    2016-01-01

    Full Text Available An advanced numerical methodology is developed for metal forming simulation based on thermodynamically-consistent nonlocal constitutive equations accounting for various fully coupled mechanical phenomena under finite strain in the framework of micromorphic continua. The numerical implementation into ABAQUS/Explicit is made for 2D quadrangular elements thanks to the VUEL users’ subroutine. Simple examples with presence of a damaged area are made in order to show the ability of the proposed methodology to describe the independence of the solution from the space discretization.

  11. GPU-based Low-dose 4DCT Reconstruction via Temporal Non-local Means

    CERN Document Server

    Tian, Zhen; Jiang, Steve B

    2010-01-01

    Four-dimensional computed tomography (4DCT) has been widely used in cancer radiotherapy for accurate target delineation and motion measurement for tumors in thorax and upper abdomen areas. However, 4DCT simulation is associated with much higher imaging dose than conventional CT simulation, which is a major concern in its clinical application. Conventionally, each phase of 4DCT is reconstructed independently using the filtered backprojection (FBP) algorithm. The basic idea of our new algorithm is that, by utilizing the common information among different phases, the input information required to reconstruct image of high quality, and thus the imaging dose, can be reduced. We proposed a temporal non-local means (TNLM) method to explore the inter-phase similarity. All phases of the 4DCT images are reconstructed simultaneously by minimizing a cost function consisting of a data fidelity term and a TNLM regularization term. We utilized a forward-backward splitting algorithm and a Gauss-Jacobi iteration method to eff...

  12. Imperfection Sensitivity of Nonlinear Vibration of Curved Single-Walled Carbon Nanotubes Based on Nonlocal Timoshenko Beam Theory

    Directory of Open Access Journals (Sweden)

    Iman Eshraghi

    2016-09-01

    Full Text Available Imperfection sensitivity of large amplitude vibration of curved single-walled carbon nanotubes (SWCNTs is considered in this study. The SWCNT is modeled as a Timoshenko nano-beam and its curved shape is included as an initial geometric imperfection term in the displacement field. Geometric nonlinearities of von Kármán type and nonlocal elasticity theory of Eringen are employed to derive governing equations of motion. Spatial discretization of governing equations and associated boundary conditions is performed using differential quadrature (DQ method and the corresponding nonlinear eigenvalue problem is iteratively solved. Effects of amplitude and location of the geometric imperfection, and the nonlocal small-scale parameter on the nonlinear frequency for various boundary conditions are investigated. The results show that the geometric imperfection and non-locality play a significant role in the nonlinear vibration characteristics of curved SWCNTs.

  13. Nonlocal continuum-based modeling of a nanoplate subjected to a moving nanoparticle. Part I: Theoretical formulations

    Science.gov (United States)

    Kiani, Keivan

    2011-10-01

    The potential applications of nanoplates in energy storage, chemical and biological sensors, solar cells, field emission, and transporting of nanocars have been attracted the attentions of the nanotechnology community to them during recent years. Herein, the later application of nanoplates from nonlocal elastodynamic point of view is of interest. To this end, dynamic response of a nanoplate subjected to a moving nanoparticle is examined within the context of nonlocal continuum theory of Eringen. The fully simply supported nanoplate is modeled based on the nonlocal Kirchhoff, Mindlin, and higher-order plate theories. The non-dimensional equations of motion of the nonlocal plate models are established. The effects of moving nanoparticle's weight and existing friction between the surfaces of the moving nanoparticle and nanoplate on the in-plane and out-of-plane vibrations of the nanoplate are incorporated into the formulations of the proposed models. The eigen function expansion and the Laplace transform methods are employed for discretization of the governing equations in the spatial and the time domains, respectively. The analytical expressions of the dynamic deformation field associated with each nonlocal plate theory are obtained when the moving nanoparticle traverses the nanoplate on an arbitrary straight path (an opened path) as well as an ellipse path (a closed path). The dynamic in-plane forces and moments of each nonlocal plate model are also derived. Furthermore, the critical velocity and the critical angular velocity of the moving nanoparticle for the proposed models are expressed analytically for the aforementioned paths. Part II of this work consists in a comprehensive parametric study where the effects of influential parameters on dynamic response of the proposed nonlocal plate models are scrutinized in some detail.

  14. Decoupling of constitutive equations for multi-layered nano-plates embedded in elastic matrix based on non-local elasticity theory using first and higher-order shear deformation theories

    Energy Technology Data Exchange (ETDEWEB)

    Dastjerdi, Shahriar; Aliabadi, Sharifeh; Jabbarzadeh Mehrdad [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-03-15

    The constitutive equations of nano-plates embedded in elastic matrix are derived based on Eringen non-local elasticity theory. Considering the non-local differential constitutive relations of Eringen theory in Cartesian and cylindrical coordinates system based on the first and higher order shear deformation theories and using the Von Karman strain field, the equilibrium differential equations are derived in terms of generalized displacements and rotations. In addition, the obtained governing equations for single layer nano plates are developed for multi-layer nano-plates. Rectangular, annular/circular and sectorial nano-plates are considered. In the most of the investigations in non-local elasticity theory, the classical plate theory (CLPT) is used, however in this paper, the governing equations are derived based on both FSDT and HSDT theories because of obtaining more accurate results.

  15. SPATIAL-VARIANT MORPHOLOGICAL FILTERS WITH NONLOCAL-PATCH-DISTANCE-BASED AMOEBA KERNEL FOR IMAGE DENOISING

    Directory of Open Access Journals (Sweden)

    Shuo Yang

    2015-01-01

    Full Text Available Filters of the Spatial-Variant amoeba morphology can preserve edges better, but with too much noise being left. For better denoising, this paper presents a new method to generate structuring elements for Spatially-Variant amoeba morphology.  The amoeba kernel in the proposed strategy is divided into two parts: one is the patch distance based amoeba center, and another is the geodesic distance based amoeba boundary, by which the nonlocal patch distance and local geodesic distance are both taken into consideration. Compared to traditional amoeba kernel, the new one has more stable center and its shape can be less influenced by noise in pilot image. What’s more important is that the nonlocal processing approach can induce a couple of adjoint dilation and erosion, and combinations of them can construct adaptive opening, closing, alternating sequential filters, etc. By designing the new amoeba kernel, a family of morphological filters therefore is derived. Finally, this paper presents a series of results on both synthetic and real images along with comparisons with current state-of-the-art techniques, including novel applications to medical image processing and noisy SAR image restoration.

  16. Accurate and efficient computation of nonlocal potentials based on Gaussian-sum approximation

    Science.gov (United States)

    Exl, Lukas; Mauser, Norbert J.; Zhang, Yong

    2016-12-01

    We introduce an accurate and efficient method for the numerical evaluation of nonlocal potentials, including the 3D/2D Coulomb, 2D Poisson and 3D dipole-dipole potentials. Our method is based on a Gaussian-sum approximation of the singular convolution kernel combined with a Taylor expansion of the density. Starting from the convolution formulation of the nonlocal potential, for smooth and fast decaying densities, we make a full use of the Fourier pseudospectral (plane wave) approximation of the density and a separable Gaussian-sum approximation of the kernel in an interval where the singularity (the origin) is excluded. The potential is separated into a regular integral and a near-field singular correction integral. The first is computed with the Fourier pseudospectral method, while the latter is well resolved utilizing a low-order Taylor expansion of the density. Both parts are accelerated by fast Fourier transforms (FFT). The method is accurate (14-16 digits), efficient (O (Nlog ⁡ N) complexity), low in storage, easily adaptable to other different kernels, applicable for anisotropic densities and highly parallelizable.

  17. Free vibrations analysis of carbon nanotubes resting on Winkler foundations based on nonlocal models

    Energy Technology Data Exchange (ETDEWEB)

    Rahmanian, M.; Torkaman-Asadi, M.A., E-mail: torkaman-asadi@ae.sharif.edu; Firouz-Abadi, R.D.; Kouchakzadeh, M.A.

    2016-03-01

    In the present study, free vibrations of single walled carbon nanotubes (SWCNT) on an elastic foundation is investigated by nonlocal theory of elasticity with both beam and shell models. The nonlocal boundary conditions are derived explicitly and effectiveness of nonlocal parameter appearing in nonlocal boundary conditions is studied. Also it is demonstrated that the beam model is comparatively incapable of capturing size effects while shell model captures size effects more precisely. Moreover, the effects of some parameters such as mechanical properties, foundation stiffness, length and radius ratios on the natural frequencies are studied and some conclusions are drawn.

  18. Parallel computing of patch-based nonlocal operator and its application in compressed sensing MRI.

    Science.gov (United States)

    Li, Qiyue; Qu, Xiaobo; Liu, Yunsong; Guo, Di; Ye, Jing; Zhan, Zhifang; Chen, Zhong

    2014-01-01

    Magnetic resonance imaging has been benefited from compressed sensing in improving imaging speed. But the computation time of compressed sensing magnetic resonance imaging (CS-MRI) is relatively long due to its iterative reconstruction process. Recently, a patch-based nonlocal operator (PANO) has been applied in CS-MRI to significantly reduce the reconstruction error by making use of self-similarity in images. But the two major steps in PANO, learning similarities and performing 3D wavelet transform, require extensive computations. In this paper, a parallel architecture based on multicore processors is proposed to accelerate computations of PANO. Simulation results demonstrate that the acceleration factor approaches the number of CPU cores and overall PANO-based CS-MRI reconstruction can be accomplished in several seconds.

  19. Rayleigh-Ritz Vibrational Analysis of Multiwalled Carbon Nanotubes Based on the Nonlocal Flügge Shell Theory

    Directory of Open Access Journals (Sweden)

    H. Rouhi

    2015-01-01

    Full Text Available A nonlocal elastic shell model considering the small scale effects is developed to study the free vibrations of multiwalled carbon nanotubes subject to different types of boundary conditions. Based on the nonlocal elasticity and the Flügge shell theory, the governing equations are derived which include the interaction of van der Waals forces between adjacent and nonadjacent layers. To analytically solve the problem, the Rayleigh-Ritz method is employed. In the present analysis, different combinations of layerwise boundary conditions are taken into account. Some new intertube resonant frequencies and the associated noncoaxial vibrational modes are identified owing to incorporating circumferential modes into the shell model.

  20. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16 dB with a small 5.4% loss of similarity.

  1. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images.

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16  dB with a small 5.4% loss of similarity.

  2. ON SOME MODEL DIFFUSION PROBLEMS WITH A NONLOCAL LOWER ORDER TERM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The authors consider a class of nonlinear parabolic problems where the lower order term isdepending on a weighted integral of the solution, and address the issues of existence, uniqueness,stationary solutions and in some cases asymptotic behaviour.

  3. Improved DCT-based nonlocal means filter for MR images denoising.

    Science.gov (United States)

    Hu, Jinrong; Pu, Yifei; Wu, Xi; Zhang, Yi; Zhou, Jiliu

    2012-01-01

    The nonlocal means (NLM) filter has been proven to be an efficient feature-preserved denoising method and can be applied to remove noise in the magnetic resonance (MR) images. To suppress noise more efficiently, we present a novel NLM filter based on the discrete cosine transform (DCT). Instead of computing similarity weights using the gray level information directly, the proposed method calculates similarity weights in the DCT subspace of neighborhood. Due to promising characteristics of DCT, such as low data correlation and high energy compaction, the proposed filter is naturally endowed with more accurate estimation of weights thus enhances denoising effectively. The performance of the proposed filter is evaluated qualitatively and quantitatively together with two other NLM filters, namely, the original NLM filter and the unbiased NLM (UNLM) filter. Experimental results demonstrate that the proposed filter achieves better denoising performance in MRI compared to the others.

  4. High-output tri-magnetic terminal-based non-local spin valves

    Science.gov (United States)

    Shirotori, Satoshi; Hashimoto, Susumu; Takagishi, Masayuki; Kamiguchi, Yuzo; Iwasaki, Hitoshi

    2015-12-01

    We propose tri-magnetic terminal-based non-local spin valves (TM-NLSVs) for lateral structures. A lateral structure has dual spin injector terminals with an anti-parallel spin configuration. The accumulated spin is detected as the voltage between the free layer and one side of the spin injector. Numerical investigation revealed that the output voltage of the TM-NLSV is 2.4-fold higher than that of the conventional four-terminal structure. A further 3.7-fold increase is expected by increasing the injector area by a factor of 9. These results indicate the possibility of obtaining an output voltage that is almost the same as that of conventional (non-lateral) spin valves.

  5. Retinal image graph-cut segmentation algorithm using multiscale Hessian-enhancement-based nonlocal mean filter.

    Science.gov (United States)

    Zheng, Jian; Lu, Pei-Rong; Xiang, Dehui; Dai, Ya-Kang; Liu, Zhao-Bang; Kuai, Duo-Jie; Xue, Hui; Yang, Yue-Tao

    2013-01-01

    We propose a new method to enhance and extract the retinal vessels. First, we employ a multiscale Hessian-based filter to compute the maximum response of vessel likeness function for each pixel. By this step, blood vessels of different widths are significantly enhanced. Then, we adopt a nonlocal mean filter to suppress the noise of enhanced image and maintain the vessel information at the same time. After that, a radial gradient symmetry transformation is adopted to suppress the nonvessel structures. Finally, an accurate graph-cut segmentation step is performed using the result of previous symmetry transformation as an initial. We test the proposed approach on the publicly available databases: DRIVE. The experimental results show that our method is quite effective.

  6. Causality, Nonlocality, and Negative Refraction.

    Science.gov (United States)

    Forcella, Davide; Prada, Claire; Carminati, Rémi

    2017-03-31

    The importance of spatial nonlocality in the description of negative refraction in electromagnetic materials has been put forward recently. We develop a theory of negative refraction in homogeneous and isotropic media, based on first principles, and that includes nonlocality in its full generality. The theory shows that both dissipation and spatial nonlocality are necessary conditions for the existence of negative refraction. It also provides a sufficient condition in materials with weak spatial nonlocality. These fundamental results should have broad implications in the theoretical and practical analyses of negative refraction of electromagnetic and other kinds of waves.

  7. Adaptive nonlocal means filtering based on local noise level for CT denoising

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhoubo; Trzasko, Joshua D.; Lake, David S.; Blezek, Daniel J.; Manduca, Armando, E-mail: manduca.armando@mayo.edu [Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota 55905 (United States); Yu, Lifeng; Fletcher, Joel G.; McCollough, Cynthia H. [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2014-01-15

    Purpose: To develop and evaluate an image-domain noise reduction method based on a modified nonlocal means (NLM) algorithm that is adaptive to local noise level of CT images and to implement this method in a time frame consistent with clinical workflow. Methods: A computationally efficient technique for local noise estimation directly from CT images was developed. A forward projection, based on a 2D fan-beam approximation, was used to generate the projection data, with a noise model incorporating the effects of the bowtie filter and automatic exposure control. The noise propagation from projection data to images was analytically derived. The analytical noise map was validated using repeated scans of a phantom. A 3D NLM denoising algorithm was modified to adapt its denoising strength locally based on this noise map. The performance of this adaptive NLM filter was evaluated in phantom studies in terms of in-plane and cross-plane high-contrast spatial resolution, noise power spectrum (NPS), subjective low-contrast spatial resolution using the American College of Radiology (ACR) accreditation phantom, and objective low-contrast spatial resolution using a channelized Hotelling model observer (CHO). Graphical processing units (GPU) implementation of this noise map calculation and the adaptive NLM filtering were developed to meet demands of clinical workflow. Adaptive NLM was piloted on lower dose scans in clinical practice. Results: The local noise level estimation matches the noise distribution determined from multiple repetitive scans of a phantom, demonstrated by small variations in the ratio map between the analytical noise map and the one calculated from repeated scans. The phantom studies demonstrated that the adaptive NLM filter can reduce noise substantially without degrading the high-contrast spatial resolution, as illustrated by modulation transfer function and slice sensitivity profile results. The NPS results show that adaptive NLM denoising preserves the

  8. Evaluation of non-local means based denoising filters for diffusion kurtosis imaging using a new phantom.

    Directory of Open Access Journals (Sweden)

    Min-Xiong Zhou

    Full Text Available Image denoising has a profound impact on the precision of estimated parameters in diffusion kurtosis imaging (DKI. This work first proposes an approach to constructing a DKI phantom that can be used to evaluate the performance of denoising algorithms in regard to their abilities of improving the reliability of DKI parameter estimation. The phantom was constructed from a real DKI dataset of a human brain, and the pipeline used to construct the phantom consists of diffusion-weighted (DW image filtering, diffusion and kurtosis tensor regularization, and DW image reconstruction. The phantom preserves the image structure while minimizing image noise, and thus can be used as ground truth in the evaluation. Second, we used the phantom to evaluate three representative algorithms of non-local means (NLM. Results showed that one scheme of vector-based NLM, which uses DWI data with redundant information acquired at different b-values, produced the most reliable estimation of DKI parameters in terms of Mean Square Error (MSE, Bias and standard deviation (Std. The result of the comparison based on the phantom was consistent with those based on real datasets.

  9. Spin transistor based on pure nonlocal Andreev reflection in EuO-graphene/superconductor/EuO-graphene nanostructure

    Science.gov (United States)

    Ang, Yee Sin; Ang, Lay Kee; Zhang, Chao; Ma, Zhongshui

    In graphene-magnetic-insulator hybrid structure such as graphene-Europium-oxide, proximity induced exchange interaction opens up a spin-dependent bandgap and spin splitting in the Dirac band. We show that such band topology allows pure crossed Andreev reflection to be generated exclusively without the parasitic local Andreev reflection and elastic cotunnelling over a wide range of bias and Fermi levels. We model the charge transport in an EuO-graphene/superconductor/EuO-graphene three-terminal device and found that the pure non-local conductance exhibits rapid on/off switching characteristic with a minimal subthreshold swing of ~ 20 mV. Non-local conductance oscillation is observed when the Fermi levels in the superconducting lead is varied. The oscillatory behavior is directly related to the quasiparticle propagation in the superconducting lead and hence can be used as a tool to probe the subgap quasiparticle mode in superconducting graphene. The non-local current is 100% spin-polarized and is highly tunable in our proposed device. This opens up the possibility of highly tunable graphene-based spin transistor that operates purely in the non-local transport regime.

  10. Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method.

    Science.gov (United States)

    Wang, Yu; Li, Feng-Ming; Wang, Yi-Ze

    2015-06-01

    The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two buckling cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.

  11. Pre-buckling responses of Timoshenko nanobeams based on the integral and differential models of nonlocal elasticity: an isogeometric approach

    Science.gov (United States)

    Norouzzadeh, A.; Ansari, R.; Rouhi, H.

    2017-05-01

    Differential form of Eringen's nonlocal elasticity theory is widely employed to capture the small-scale effects on the behavior of nanostructures. However, paradoxical results are obtained via the differential nonlocal constitutive relations in some cases such as in the vibration and bending analysis of cantilevers, and recourse must be made to the integral (original) form of Eringen's theory. Motivated by this consideration, a novel nonlocal formulation is developed herein based on the original formulation of Eringen's theory to study the buckling behavior of nanobeams. The governing equations are derived according to the Timoshenko beam theory, and are represented in a suitable vector-matrix form which is applicable to the finite-element analysis. In addition, an isogeometric analysis (IGA) is conducted for the solution of buckling problem. Construction of exact geometry using non-uniform rational B-splines and easy implementation of geometry refinement tools are the main advantages of IGA. A comparison study is performed between the predictions of integral and differential nonlocal models for nanobeams under different kinds of end conditions.

  12. Homoclinic behaviors and chaotic motions of double layered viscoelastic nanoplates based on nonlocal theory and extended Melnikov method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Wang, Yi-Ze [School of Astronautics, Harbin Institute of Technology, P. O. Box 137, Harbin 150001 (China); Li, Feng-Ming, E-mail: fmli@bjut.edu.cn [School of Astronautics, Harbin Institute of Technology, P. O. Box 137, Harbin 150001 (China); College of Mechanical Engineering, Beijing University of Technology, Beijing 100124 (China)

    2015-06-15

    The nonlinear dynamical equations are established for the double layered viscoelastic nanoplates (DLNP) subjected to in-plane excitation based on the nonlocal theory and von Kármán large deformation theory. The extended high dimensional homoclinic Melnikov method is employed to study the homoclinic phenomena and chaotic motions for the parametrically excited DLNP system. The criteria for the homoclinic transverse intersection for both the asynchronous and synchronous buckling cases are proposed. Lyapunov exponents and phase portraits are obtained to verify the Melnikov-type analysis. The influences of structural parameters on the transverse homoclinic orbits and homoclinic bifurcation sets are discussed for the two buckling cases. Some novel phenomena are observed in the investigation. It should be noticed that the nonlocal effect on the homoclinic behaviors and chaotic motions is quite remarkable. Hence, the small scale effect should be taken into account for homoclinic and chaotic analysis for nanostructures. It is significant that the nonlocal effect on the homoclinic phenomena for the asynchronous buckling case is quite different from that for the synchronous buckling case. Moreover, due to the van der Walls interaction between the layers, the nonlocal effect on the homoclinic behaviors and chaotic motions for high order mode is rather tiny under the asynchronous buckling condition.

  13. Nonlocal Inflation

    CERN Document Server

    Barnaby, Neil

    2008-01-01

    We consider the possibility of realizing inflation in nonlocal field theories containing infinitely many derivatives. Such constructions arise naturally in string field theory and also in a number of toy models, such as the p-adic string. After reviewing the complications (ghosts and instabilities) that arise when working with high derivative theories we discuss the initial value problem and perturbative stability of theories with infinitely many derivatives. Next, we examine the inflationary dynamics and phenomenology of such theories. Nonlocal inflation can proceed even when the potential is naively too steep and generically predicts large nongaussianity in the Cosmic Microwave Background.

  14. Static analysis of rectangular nanoplates using trigonometric shear deformation theory based on nonlocal elasticity theory

    National Research Council Canada - National Science Library

    Nami, Mohammad Rahim; Janghorban, Maziar

    2013-01-01

    .... In order to consider the size effects, the nonlocal elasticity theory is used. An analytical method is adopted to solve the governing equations for static analysis of simply supported nanoplates...

  15. DQ thermal buckling analysis of embedded curved carbon nanotubes based on nonlocal elasticity theory

    National Research Council Canada - National Science Library

    Setoodeh, AliReza; Derahaki, Morteza; Bavi, Navid

    2015-01-01

    Abstract To investigate the thermal buckling of curved carbon nanotubes (CCNTs) embedded in an elastic medium, nonlocal elasticity theory is employed in combination with the theory of thin curved beams...

  16. Retinal Image Graph-Cut Segmentation Algorithm Using Multiscale Hessian-Enhancement-Based Nonlocal Mean Filter

    National Research Council Canada - National Science Library

    Zheng, Jian; Lu, Pei-Rong; Xiang, Dehui; Dai, Ya-Kang; Liu, Zhao-Bang; Kuai, Duo-Jie; Xue, Hui; Yang, Yue-Tao

    2013-01-01

    .... By this step, blood vessels of different widths are significantly enhanced. Then, we adopt a nonlocal mean filter to suppress the noise of enhanced image and maintain the vessel information at the same time...

  17. Retinal image graph-cut segmentation algorithm using multiscale Hessian-enhancement-based nonlocal mean filter

    National Research Council Canada - National Science Library

    Zheng, Jian; Lu, Pei-Rong; Xiang, Dehui; Dai, Ya-Kang; Liu, Zhao-Bang; Kuai, Duo-Jie; Xue, Hui; Yang, Yue-Tao

    2013-01-01

    .... By this step, blood vessels of different widths are significantly enhanced. Then, we adopt a nonlocal mean filter to suppress the noise of enhanced image and maintain the vessel information at the same time...

  18. An operational framework for nonlocality

    CERN Document Server

    Gallego, Rodrigo; Acín, Antonio; Navascués, Miguel

    2011-01-01

    Due to the importance of entanglement for quantum information purposes, a framework has been developed for its characterization and quantification as a resource based on the following operational principle: entanglement among $N$ parties cannot be created by local operations and classical communication, even when $N-1$ parties collaborate. More recently, nonlocality has been identified as another resource, alternative to entanglement and necessary for device-independent quantum information protocols. We introduce an operational framework for nonlocality based on a similar principle: nonlocality among $N$ parties cannot be created by local operations and allowed classical communication even when $N-1$ parties collaborate. We then show that the standard definition of multipartite nonlocality, due to Svetlichny, is inconsistent with this operational approach: according to it, genuine tripartite nonlocality could be created by two collaborating parties. We finally discuss alternative definitions for which consist...

  19. Blind restoration for nonuniform aerial images using nonlocal Retinex model and shearlet-based higher-order regularization

    Science.gov (United States)

    Chen, Rui; Jia, Huizhu; Xie, Xiaodong; Gao, Wen

    2017-05-01

    Aerial images are often degraded by space-varying motion blurs and simultaneous uneven illumination. To recover a high-quality aerial image from its nonuniform version, we propose a patchwise restoration approach based on a key observation that the degree of blurring is inevitably affected by the illumination conditions. A nonlocal Retinex model is developed to accurately estimate the reflectance component from the degraded aerial image. Thereafter, the uneven illumination is corrected well. Then nonuniform coupled blurring in the enhanced reflectance image is alleviated and transformed toward uniform distribution, which will facilitate the subsequent deblurring. For constructing the multiscale sparsified regularization, the discrete shearlet transform is improved to better represent anisotropic image features in terms of directional sensitivity and selectivity. In addition, a new adaptive variant of total generalized variation is proposed to act as the structure-preserving regularizer. These complementary regularizers are elegantly integrated into an objective function. The final deblurred image with uniform illumination can be obtained by applying a fast alternating direction scheme to solve the derived function. The experimental results demonstrate that our algorithm can not only effectively remove both the space-varying illumination and motion blurs in aerial images, but also recover the abundant details of aerial scenes with top-level objective and subjective quality, and outperforms other state-of-the-art restoration methods.

  20. A non-local, ordinary-state-based viscoelasticity model for peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony

    2011-10-01

    A non-local, ordinary-state-based, peridynamics viscoelasticity model is developed. In this model, viscous effects are added to deviatoric deformations and the bulk response remains elastic. The model uses internal state variables and is conceptually similar to linearized isotropic viscolelasticity in the local theory. The modulus state, which is used to form the Jacobian matrix in Newton-Raphson algorithms, is presented. The model is shown to satisfy the 2nd law of thermodynamics and is applicable to problems in solid continuum mechanics where fracture and rate effects are important; it inherits all the advantages for modeling fracture associated with peridynamics. By combining this work with the previously published ordinary-state-based plasticity model, the model may be amenable to viscoplasticity problems where plasticity and rate effects are simultaneously important. Also, the model may be extended to include viscous effects for spherical deformations as well. The later two extensions are not presented and may be the subject of further work.

  1. Nonlocal-response diffusion model of holographic recording in photopolymer

    OpenAIRE

    Sheridan, John T.; Lawrence, Justin R.

    2000-01-01

    The standard one-dimensional diffusion equation is extended to include nonlocal temporal and spatial medium responses. How such nonlocal effects arise in a photopolymer is discussed. It is argued that assuming rapid polymer chain growth, any nonlocal temporal response can be dealt with so that the response can be completely understood in terms of a steady-state nonlocal spatial response. The resulting nonlocal diffusion equation is then solved numerically, in low-harmonic approximation, to de...

  2. Non-local means-based nonuniformity correction for infrared focal-plane array detectors

    Science.gov (United States)

    Yu, Hui; Zhang, Zhi-jie; Chen, Fu-sheng; Wang, Chen-sheng

    2014-11-01

    The infrared imaging systems are normally based on the infrared focal-plane array (IRFPA) which can be considered as an array of independent detectors aligned at the focal plane of the imaging system. Unfortunately, every detector on the IRFPA may have a different response to the same input infrared signal which is known as the nonuniformity problem. Then we can observe the fixed pattern noise (FPN) from the resulting images. Standard nonuniformity correction (NUC) methods need to be recalibrated after a short period of time due the temporal drift of the FPN. Scene-based nonuniformity correction (NUC) techniques eliminate the need for calibration by correction coefficients based on the scene being viewed. However, in the scene-based NUC method the problem of ghosting artifacts widely seriously decreases the image quality, which can degrade the performance of many applications such as target detection and track. This paper proposed an improved scene-based method based on the retina-like neural network approach. The method incorporates the use of non-local means (NLM) method into the estimation of the gain and the offset of each detector. This method can not only estimates the accurate correction coefficient but also restrict the ghosting artifacts efficiently. The proposed method relies on the use of NLM method which is a very successful image denoising method. And then the NLM used here can preserve the image edges efficiently and obtain a reliable spatial estimation. We tested the proposed NUC method by applying it to an IR sequence of frames. The performance of the proposed method was compared the other well-established adaptive NUC techniques.

  3. GPU-Based Block-Wise Nonlocal Means Denoising for 3D Ultrasound Images

    Directory of Open Access Journals (Sweden)

    Liu Li

    2013-01-01

    Full Text Available Speckle suppression plays an important role in improving ultrasound (US image quality. While lots of algorithms have been proposed for 2D US image denoising with remarkable filtering quality, there is relatively less work done on 3D ultrasound speckle suppression, where the whole volume data rather than just one frame needs to be considered. Then, the most crucial problem with 3D US denoising is that the computational complexity increases tremendously. The nonlocal means (NLM provides an effective method for speckle suppression in US images. In this paper, a programmable graphic-processor-unit- (GPU- based fast NLM filter is proposed for 3D ultrasound speckle reduction. A Gamma distribution noise model, which is able to reliably capture image statistics for Log-compressed ultrasound images, was used for the 3D block-wise NLM filter on basis of Bayesian framework. The most significant aspect of our method was the adopting of powerful data-parallel computing capability of GPU to improve the overall efficiency. Experimental results demonstrate that the proposed method can enormously accelerate the algorithm.

  4. Accurate and efficient computation of nonlocal potentials based on Gaussian-sum approximation

    CERN Document Server

    Exl, Lukas; Zhang, Yong

    2015-01-01

    We introduce an accurate and efficient method for a class of nonlocal potential evaluations with free boundary condition, including the 3D/2D Coulomb, 2D Poisson and 3D dipolar potentials. Our method is based on a Gaussian-sum approximation of the singular convolution kernel and Taylor expansion of the density. Starting from the convolution formulation, for smooth and fast decaying densities, we make a full use of the Fourier pseudospectral (plane wave) approximation of the density and a separable Gaussian-sum approximation of the kernel in an interval where the singularity (the origin) is excluded. Hence, the potential is separated into a regular integral and a near-field singular correction integral, where the first integral is computed with the Fourier pseudospectral method and the latter singular one can be well resolved utilizing a low-order Taylor expansion of the density. Both evaluations can be accelerated by fast Fourier transforms (FFT). The new method is accurate (14-16 digits), efficient ($O(N \\lo...

  5. Wave dispersion in viscoelastic single walled carbon nanotubes based on the nonlocal strain gradient Timoshenko beam model

    Science.gov (United States)

    Tang, Yugang; Liu, Ying; Zhao, Dong

    2017-03-01

    Based on the nonlocal strain gradient theory and Timoshenko beam model, the properties of wave propagation in a viscoelastic single-walled carbon nanotube (SWCNT) are investigated. The characteristic equations for flexural and shear waves in visco-SWCNTs are established. The influence of the tube size on the wave dispersion is clarified. For a low damping coefficient, threshold diameter for shear wave (SW) is observed, below which the phase velocity of SW is equal to zero, whilst flexural wave (FW) always exists. For a high damping coefficient, SW is absolutely constrained, and blocking diameter for FW is observed, above which the wave propagation is blocked. The effects of the wave number, nonlocal and strain gradient length scale parameters on the threshold and blocking diameters are discussed in detail.

  6. Nonlocal strain gradient theory calibration using molecular dynamics simulation based on small scale vibration of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mehralian, Fahimeh [Mechanical Engineering Department, Shahrekord University, Shahrekord (Iran, Islamic Republic of); Tadi Beni, Yaghoub, E-mail: tadi@eng.sku.ac.ir [Faculty of Engineering, Shahrekord University, Shahrekord (Iran, Islamic Republic of); Karimi Zeverdejani, Mehran [Mechanical Engineering Department, Shahrekord University, Shahrekord (Iran, Islamic Republic of)

    2017-06-01

    Featured by two small length scale parameters, nonlocal strain gradient theory is utilized to investigate the free vibration of nanotubes. A new size-dependent shell model formulation is developed by using the first order shear deformation theory. The governing equations and boundary conditions are obtained using Hamilton's principle and solved for simply supported boundary condition. As main purpose of this study, since the values of two small length scale parameters are still unknown, they are calibrated by the means of molecular dynamics simulations (MDs). Then, the influences of different parameters such as nonlocal parameter, scale factor, length and thickness on vibration characteristics of nanotubes are studied. It is also shown that increase in thickness and decrease in length parameters intensify the effect of nonlocal parameter and scale factor.

  7. Nonviolent nonlocality

    CERN Document Server

    Giddings, Steven B

    2012-01-01

    If quantum mechanics governs nature, black holes must evolve unitarily, providing a powerful constraint on the dynamics of quantum gravity. Such evolution apparently must in particular be nonlocal, when described from the usual semiclassical geometric picture, in order to transfer quantum information into the outgoing state. While such transfer from a disintegrating black hole has the dangerous potential to be violent to generic infalling observers, this paper proposes the existence of a more innocuous form of information transfer, to relatively soft modes in the black hole atmosphere. Simplified models for such nonlocal transfer are described and parameterized, within a possibly more basic framework of a Hilbert tensor network. Sufficiently sensitive measurements by infalling observers may detect departures from Hawking's predictions, and in generic models black holes decay more rapidly. Constraints of consistency -- internally and with known and expected features of physics -- restrict the form of informati...

  8. Nonlocal transformation optics

    CERN Document Server

    Castaldi, Giuseppe; Alu', Andrea; Engheta, Nader

    2011-01-01

    We show that the powerful framework of transformation optics may be exploited for engineering the nonlocal response of artificial electromagnetic materials. Relying on the form-invariant properties of coordinate-transformed Maxwell's equations in the spectral domain, we derive the general constitutive "blueprints" of transformation media yielding prescribed nonlocal field-manipulation effects, and provide a physically-incisive and powerful geometrical interpretation in terms of deformation of the equi-frequency contours. In order to illustrate the potentials of our approach, we present an example of application to a wave-splitting refraction scenario, which may be implemented via a simple class of artificial materials. Our results provide a systematic and versatile framework which may open intriguing venues in dispersion engineering of artificial materials.

  9. Nonlocality of quantum correlations

    CERN Document Server

    Streltsov, A; Roga, W; Bruß, D; Illuminati, F

    2012-01-01

    We show that only those composite quantum systems possessing nonvanishing quantum correlations have the property that any nontrivial local unitary evolution changes their global state. This type of nonlocality occurs also for states that do not violate a Bell inequality, such as, for instance, Werner states with a low degree of entanglement. We derive the exact relation between the global state change induced by local unitary evolutions and the amount of quantum correlations. We prove that the minimal change coincides with the geometric measure of discord, thus providing the latter with an operational interpretation in terms of the capability of a local unitary dynamics to modify a global state. We establish rigorously that Werner states are the maximally quantum correlated two-qubit states, and thus are the ones that maximize this novel type of nonlocality.

  10. Strong nonlocal coupling stabilizes localized structures: an analysis based on front dynamics.

    Science.gov (United States)

    Fernandez-Oto, C; Clerc, M G; Escaff, D; Tlidi, M

    2013-04-26

    We investigate the effect of strong nonlocal coupling in bistable spatially extended systems by using a Lorentzian-like kernel. This effect through front interaction drastically alters the space-time dynamics of bistable systems by stabilizing localized structures in one and two dimensions, and by affecting the kinetics law governing their behavior with respect to weak nonlocal and local coupling. We derive an analytical formula for the front interaction law and show that the kinetics governing the formation of localized structures obeys a law inversely proportional to their size to some power. To illustrate this mechanism, we consider two systems, the Nagumo model describing population dynamics and nonlinear optics model describing a ring cavity filled with a left-handed material. Numerical solutions of the governing equations are in close agreement with analytical predictions.

  11. Controllable soliton propagation based on phase-front curvature in asymmetrical nonlocal media

    Science.gov (United States)

    Zhang, Huafeng; Lü, Hua; Luo, Jianghua; Sun, Lihui

    2016-08-01

    The influence of phase-front curvature on the dynamical behavior of the fundamental mode soliton during its transmission in asymmetrical nonlocal media is studied in detail and the phase-front curvature can be imposed on the fundamental mode soliton by reshaping or phase imprinting technologies. By changing the phase-front curvature or its imposed position, controllable soliton propagation in asymmetrical nonlocal media can be achieved. Project supported by the National Natural Science Foundation of China (Grants Nos. 11547007 and 11304024), the Innovation Personnel Training Plan for Excellent Youth of Guangdong University Project (Grant No. 2013LYM_0023), and the Yangtze Fund for Youth Teams of Science and Technology Innovation (Grant No. 2015cqt03).

  12. An Inhomogeneous Space-Time Patching Model Based on a Nonlocal and Nonlinear Schrodinger Equation

    CERN Document Server

    Dantas, Christine C

    2016-01-01

    We consider an integrable, nonlocal and nonlinear, Schr\\"odinger equation (NNSE) as a model for building space-time patchings in inhomogeneous loop quantum cosmology (LQC). We briefly review exact solutions of the NNSE, specially those obtained through "geometric equivalence" methods. Furthemore, we argue that the integrability of the NNSE could be linked to consistency conditions derived from LQC, under the assumption that the patchwork dynamics behaves as an integrable many-body system.

  13. De-interlacing using nonlocal costs and Markov-chain-based estimation of interpolation methods.

    Science.gov (United States)

    Vedadi, Farhang; Shirani, Shahram

    2013-04-01

    A new method of de-interlacing is proposed. De-interlacing is revisited as the problem of assigning a sequence of interpolation methods (interpolators) to a sequence of missing pixels of an interlaced frame (field). With this assumption, our de-interlacing algorithm (de-interlacer), undergoes transitions from one interpolation method to another, as it moves from one missing pixel position to the horizontally adjacent missing pixel position in a missing row of a field. We assume a discrete countable-state Markov-chain model on the sequence of interpolators (Markov-chain states) which are selected from a user-defined set of candidate interpolators. An estimation of the optimum sequence of interpolators with the aforementioned Markov-chain model requires the definition of an efficient cost function as well as a global optimization technique. Our algorithm introduces for the first time using a nonlocal cost (NLC) scheme. The proposed algorithm uses the NLC to not only measure the fitness of an interpolator at a missing pixel position, but also to derive an approximation for transition matrix (TM) of the Markov-chain of interpolators. The TM in our algorithm is a frame-variate matrix, i.e., the algorithm updates the TM for each frame automatically. The algorithm finally uses a Viterbi algorithm to find the global optimum sequence of interpolators given the cost function defined and neighboring original pixels in hand. Next, we introduce a new MAP-based formulation for the estimation of the sequence of interpolators this time not by estimating the best sequence of interpolators but by successive estimations of the best interpolator at each missing pixel using Forward-Backward algorithm. Simulation results prove that, while competitive with each other on different test sequences, the proposed methods (one using Viterbi and the other Forward-Backward algorithm) are superior to state-of-the-art de-interlacing algorithms proposed recently. Finally, we propose motion

  14. Spontaneous Emission in Nonlocal Materials

    CERN Document Server

    Ginzburg, Pavel; Nasir, Mazhar E; Olvera, Paulina Segovia; Krasavin, Alexey V; Levitt, James; Hirvonen, Liisa M; Wells, Brian; Suhling, Klaus; Richards, David; Podolskiy, Viktor A; Zayats, Anatoly V

    2016-01-01

    Light-matter interactions can be dramatically modified by the surrounding environment. Here we report on the first experimental observation of molecular spontaneous emission inside a highly nonlocal metamaterial based on a plasmonic nanorod assembly. We show that the emission process is dominated not only by the topology of its local effective medium dispersion, but also by the nonlocal response of the composite, so that metamaterials with different geometric parameters but the same local effective medium properties exhibit different Purcell factors. A record-high enhancement of a decay rate is observed, in agreement with the developed quantitative description of the Purcell effect in a nonlocal medium. An engineered material nonlocality introduces an additional degree of freedom into quantum electrodynamics, enabling new applications in quantum information processing, photo-chemistry, imaging, and sensing.

  15. 非局部的变分正则化图像放大算法%Variational image zooming based on nonlocal total variation

    Institute of Scientific and Technical Information of China (English)

    姜东焕; 徐光宝; 东野长磊

    2012-01-01

    A regularized image zooming model based on nonlocal total variation was proposed, with regard to that the Chambolle image zooming model has blocky effects. It consisted of regular term and fidelity term. The zoomed image was obtained by minimizing the variational function which used the nonlocal total variation norm to measure the regularity of the image. Unlike the traditional image zooming by interpolation, the variational model was incorporated in the new zooming algorithm and the use of nonlocal operator made the algorithm not just use a single pixel of the image, or gray and gradient information in a neighborhood to amplify, but use the information of image content itself widely that will avoid blocky effects of Chambolle's model. The experimental results show that the new algorithm can preserve better the border and details. It achieves better effect than Chambolle's method and the interpolation by using spline.%针对Chambolle图像放大模型存在分块效应,提出一种非局部的变分正则化图像放大算法.该算法的思想是构造一个适用于图像放大的变分泛函,该泛函由正则项和数据保真项构成,其中图像的正则项是用非局部全变差范数进行估计,进而用迭代投影方法求泛函的最小解,即为放大后的图像.与传统的图像插值方法不同,该算法是用变分的思想进行图像放大,非局部全变差的引入更使得该算法不只是利用图像的单个像素点,或某一邻域内的灰度和梯度信息进行放大,而是更大范围地利用了图像本身的信息,这将更有效地保留图像特征,避免了Chambolle方法在图像放大时出现的分块效应.实验结果表明,该算法能更好地保留边缘和细节信息,放大图像的清晰度比Chambolle图像放大方法和样条插值的效果要好.

  16. Nonlocal Galileons and self-acceleration

    Science.gov (United States)

    Gabadadze, Gregory; Yu, Siqing

    2017-05-01

    A certain class of nonlocal theories eliminates an arbitrary cosmological constant (CC) from a universe that can be perceived as our world. Dark energy then cannot be explained by a CC; it could however be due to massive gravity. We calculate the new corrections, which originate from the nonlocal terms that eliminate the CC, to the decoupling limit Lagrangian of massive gravity. The new nonlocal terms also have internal field space Galilean symmetry and are referred here as ;nonlocal Galileons.; We then study a self-accelerated solution and show that the new nonlocal terms change the perturbative stability analysis. In particular, small fluctuations are now stable and non-superluminal for some simple parameter choices, whereas for the same choices the pure massive gravity fluctuations are unstable. We also study stable spherically symmetric solutions on this background.

  17. Nonlocal Galileons and self-acceleration

    Directory of Open Access Journals (Sweden)

    Gregory Gabadadze

    2017-05-01

    Full Text Available A certain class of nonlocal theories eliminates an arbitrary cosmological constant (CC from a universe that can be perceived as our world. Dark energy then cannot be explained by a CC; it could however be due to massive gravity. We calculate the new corrections, which originate from the nonlocal terms that eliminate the CC, to the decoupling limit Lagrangian of massive gravity. The new nonlocal terms also have internal field space Galilean symmetry and are referred here as “nonlocal Galileons.” We then study a self-accelerated solution and show that the new nonlocal terms change the perturbative stability analysis. In particular, small fluctuations are now stable and non-superluminal for some simple parameter choices, whereas for the same choices the pure massive gravity fluctuations are unstable. We also study stable spherically symmetric solutions on this background.

  18. A New Model of Nonlocal Modified Gravity

    CERN Document Server

    Dimitrijevic, Ivan; Grujic, Jelena; Rakic, Zoran

    2014-01-01

    We consider a new modified gravity model with nonlocal term of the form $R^{-1} \\mathcal{F}(\\Box) R. $ This kind of nonlocality is motivated by investigation of applicability of a few unusual ans\\"atze to obtain some exact cosmological solutions. In particular, we find attractive and useful quadratic ansatz $\\Box R = q R^{2}.$

  19. On instabilities in tensorial nonlocal gravity

    CERN Document Server

    Nersisyan, Henrik; Amendola, Luca; Koivisto, Tomi S; Rubio, Javier; Solomon, Adam R

    2016-01-01

    We discuss the cosmological implications of nonlocal modifications of general relativity containing tensorial structures. Assuming the presence of standard radiation- and matter-dominated eras, we show that, except in very particular cases, the nonlocal terms contribute a rapidly-growing energy density. These models therefore generically do not have a stable cosmological evolution.

  20. Dynamic instability of vibrating carbon nanotubes near small layers of graphite sheets based on nonlocal continuum elasticity

    Science.gov (United States)

    Sedighi, H. M.; Yaghootian, A.

    2016-01-01

    This article presents a new asymptotic method to predict dynamic pull-in instability of nonlocal clamped-clamped carbon nanotubes (CNTs) near graphite sheets. Nonlinear governing equations of carbon nanotubes actuated by an electric field are derived. With due allowance for the van der Waals effects, the pull-in instability and the natural frequency-amplitude relationship are investigated by a powerful analytical method, namely, the parameter expansion method. It is demonstrated that retaining two terms in series expansions is sufficient to produce an acceptable solution. The obtained results from numerical methods verify the strength of the analytical procedure. The qualitative analysis of system dynamics shows that the equilibrium points of the autonomous system include center points and unstable saddle points. The phase portraits of the carbon nanotube actuator exhibit periodic and homoclinic orbits.

  1. Quadratic solitons for negative effective second-harmonic diffraction as nonlocal solitons with periodic nonlocal response function

    DEFF Research Database (Denmark)

    Esbensen, B.K.; Bache, Morten; Krolikowski, W.;

    2012-01-01

    We employ the formal analogy between quadratic and nonlocal solitons to investigate analytically the properties of solitons and soliton bound states in second-harmonic generation in the regime of negative diffraction or dispersion of the second harmonic. We show that in the nonlocal description t...... this regime corresponds to a periodic nonlocal response function. We then use the strongly nonlocal approximation to find analytical solutions of the families of single bright solitons and their bound states in terms of Mathieu functions....

  2. Causality, Non-Locality and Negative Refraction

    CERN Document Server

    Forcella, Davide; Carminati, Rémi

    2016-01-01

    The importance of spatial non-locality in the description of negative refraction in electromagnetic materials has been put forward recently. We develop a theory of negative refraction in homogeneous and isotropic media, based on first principles, and that includes non-locality in its full generality. The theory shows that both dissipation and spatial non-locality are necessary conditions for the existence of negative refraction. It also provides a sufficient condition in materials with weak spatial non-locality. These fundamental results should have broad implications in the theoretical and practical analyses of negative refraction of electromagnetic and other kinds of waves.

  3. Origin of Dynamical Quantum Non-locality

    Science.gov (United States)

    Pachon, Cesar E.; Pachon, Leonardo A.

    2014-03-01

    Non-locality is one of the hallmarks of quantum mechanics and is responsible for paradigmatic features such as entanglement and the Aharonov-Bohm effect. Non-locality comes in two ``flavours'': a kinematic non-locality- arising from the structure of the Hilbert space- and a dynamical non-locality- arising from the quantum equations of motion-. Kinematic non-locality is unable to induce any change in the probability distributions, so that the ``action-at-a-distance'' cannot manifest. Conversely, dynamical non-locality does create explicit changes in probability, though in a ``causality-preserving'' manner. The origin of non-locality of quantum measurements and its relations to the fundamental postulates of quantum mechanics, such as the uncertainty principle, have been only recently elucidated. Here we trace the origin of dynamical non-locality to the superposition principle. This relation allows us to establish and identify how the uncertainty and the superposition principles determine the non-local character of the outcome of a quantum measurement. Being based on group theoretical and path integral formulations, our formulation admits immediate generalizations and extensions to to, e.g., quantum field theory. This work was supported by the Departamento Administrativo de Ciencia, Tecnologia e Innovacion -COLCIENCIAS- of Colombia under the grant number 111556934912.

  4. Temporal Non-locality

    Science.gov (United States)

    Filk, Thomas

    2013-04-01

    In this article I investigate several possibilities to define the concept of "temporal non-locality" within the standard framework of quantum theory. In particular, I analyze the notions of "temporally non-local states", "temporally non-local events" and "temporally non-local observables". The idea of temporally non-local events is already inherent in the standard formalism of quantum mechanics, and Basil Hiley recently defined an operator in order to measure the degree of such a temporal non-locality. The concept of temporally non-local states enters as soon as "clock-representing states" are introduced in the context of special and general relativity. It is discussed in which way temporally non-local measurements may find an interesting application for experiments which test temporal versions of Bell inequalities.

  5. Aberration-Free Imaging Based on Parity-Time Symmetric Nonlocal Metasurfaces

    CERN Document Server

    Monticone, Francesco; Alu, Andrea

    2015-01-01

    Lens design for focusing and imaging has been optimized through centuries of developments; however, conventional lenses, even in their most ideal realizations, still suffer from fundamental limitations, such as limits in resolution and the presence of optical aberrations, which are inherent to the laws of refraction. Although some of these limitations have been at least theoretically relaxed with the advent of metamaterials, several challenges still stand in the path toward ideal aberration-free imaging. Here, we show that the concept of parity-time symmetry, combined with tailored nonlocal response, allows overcoming some of these challenges, and we demonstrate the design of a loss-immune, linear, transversely invariant, aberration-free planarized metamaterial lens.

  6. Nonlocal incoherent solitons

    DEFF Research Database (Denmark)

    Krolikowski, Wieslaw; Bang, Ole; Wyller, John

    2004-01-01

    We investigate the propagation of partially coherent beams in spatially nonlocal nonlinear media with a logarithmic type of nonlinearity. We derive analytical formulas for the evolution of the beam parameters and conditions for the formation of nonlocal incoherent solitons.......We investigate the propagation of partially coherent beams in spatially nonlocal nonlinear media with a logarithmic type of nonlinearity. We derive analytical formulas for the evolution of the beam parameters and conditions for the formation of nonlocal incoherent solitons....

  7. NONLOCAL SYMMETRIES AND NONLOCAL RECURSION OPERATORS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An expose about covering method on differential equations was given. The general formulae to determine nonlocal symmetries were derived which are analogous to the prolongation formulae of generalized symmetries. In addition, a new definition of nonlocal recursion operators was proposed, which gave a satisfactory explalnation in covering theory for the integro-differcntial recursion operators.

  8. Spectral Dimension from Causal Set Nonlocal Dynamics

    CERN Document Server

    Belenchia, Alessio; Marciano, Antonino; Modesto, Leonardo

    2015-01-01

    We investigate the spectral dimension obtained from non-local continuum d'Alembertians derived from causal sets. We find a universal dimensional reduction to 2 dimensions, in all dimensions. We conclude by discussing the validity and relevance of our results within the broader context of quantum field theories based on these nonlocal dynamics.

  9. Oracle inequalities and minimax rates for non-local means and related adaptive kernel-based methods

    CERN Document Server

    Arias-Castro, Ery; Willett, Rebecca

    2011-01-01

    This paper describes a novel theoretical characterization of the performance of non-local means (NLM) for noise removal. NLM has proven effective in a variety of empirical studies, but little is understood fundamentally about how it performs relative to classical methods based on wavelets or how various parameters (e.g., patch size) should be chosen. For cartoon images and images which may contain thin features and regular textures, the error decay rates of NLM are derived and compared with those of linear filtering, oracle estimators, variable-bandwidth kernel methods, Yaroslavsky's filter and wavelet thresholding estimators. The trade-off between global and local search for matching patches is examined, and the bias reduction associated with the local polynomial regression version of NLM is analyzed. The theoretical results are validated via simulations for 2D images corrupted by additive white Gaussian noise.

  10. Image Denoising Algorithm Based on Nonlocally Sparse Representation and Group%组约束与非局部稀疏的图像去噪算法

    Institute of Scientific and Technical Information of China (English)

    陈利霞; 赛朋飞

    2015-01-01

    The most existing denoising algorithms based on nonlocal sparse representation are strictly dependent on patch matching ,and the denoising performance is subject to the numbers of similar patches .So a image denoising algorithm based on nonlocally sparse representation and group is proposed . The group‐based constraints is introduced to the nonlocal sparse representation ,which can enhance the nonlocal similarity between image patches and the patch matching is more accurate .Experiments show that the model has a good performance in both visual effect and peak signal to noise ratio .%现有的非局部稀疏表示去噪算法大多严格依赖于块匹配,且其去噪性能受制于匹配的相似块的数量。鉴于此,提出了组约束与非局部稀疏的图像去噪模型。模型在非局部稀疏的基础上加入了分组约束,增强了图像块之间的非局部相似度,块匹配更加精确。实验表明,模型无论是在视觉效果还是峰值信噪比上均具有较好的性能。

  11. Free vibration analysis of a multiple rotating nano-beams system based on the Eringen nonlocal elasticity theory

    Energy Technology Data Exchange (ETDEWEB)

    Ghafarian, M.; Ariaei, A., E-mail: ariaei@eng.ui.ac.ir [Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of)

    2016-08-07

    The free vibration analysis of a multiple rotating nanobeams' system applying the nonlocal Eringen elasticity theory is presented. Multiple nanobeams' systems are of great importance in nano-optomechanical applications. At nanoscale, the nonlocal effects become non-negligible. According to the nonlocal Euler-Bernoulli beam theory, the governing partial differential equations are derived by incorporating the nonlocal scale effects. Assuming a structure of n parallel nanobeams, the vibration of the system is described by a coupled set of n partial differential equations. The method involves a change of variables to uncouple the equations and the differential transform method as an efficient mathematical technique to solve the nonlocal governing differential equations. Then a number of parametric studies are conducted to assess the effect of the nonlocal scaling parameter, rotational speed, boundary conditions, hub radius, and the stiffness coefficients of the elastic interlayer media on the vibration behavior of the coupled rotating multiple-carbon-nanotube-beam system. It is revealed that the bending vibration of the system is significantly influenced by the rotational speed, elastic mediums, and the nonlocal scaling parameters. This model is validated by comparing the results with those available in the literature. The natural frequencies are in a reasonably good agreement with the reported results.

  12. Totality of Subquantum Nonlocal Correlations

    CERN Document Server

    Khrennikov, Andrei

    2011-01-01

    In a series of previous papers we developed a purely field model of microphenomena, so called prequantum classical statistical field theory (PCSFT). This model not only reproduces important probabilistic predictions of QM including correlations for entangled systems, but it also gives a possibility to go beyond quantum mechanics (QM), i.e., to make predictions of phenomena which could be observed at the subquantum level. In this paper we discuss one of such predictions - existence of nonlocal correlations between prequantum random fields corresponding to {\\it all} quantum systems. (And by PCSFT quantum systems are represented by classical Gaussian random fields and quantum observables by quadratic forms of these fields.) The source of these correlations is the common background field. Thus all prequantum random fields are "entangled", but in the sense of classical signal theory. On one hand, PCSFT demystifies quantum nonlocality by reducing it to nonlocal classical correlations based on the common random back...

  13. Vibration analysis of orthotropic circular and elliptical nano-plates embedded in elastic medium based on nonlocal Mindlin plate theory and using Galerkin method

    Energy Technology Data Exchange (ETDEWEB)

    Anjomshoa, Amin; Tahani, Masoud [Ferdowsi University, Mashhad (Iran, Islamic Republic of)

    2016-06-15

    In the present study a continuum model based on the nonlocal elasticity theory is developed for free vibration analysis of embedded ortho tropic thick circular and elliptical nano-plates rested on an elastic foundation. The elastic foundation is considered to behave like a Pasternak type of foundations. Governing equations for vibrating nano-plate are derived according to the Mindlin plate theory in which the effects of shear deformations of nano-plate are also included. The Galerkin method is then employed to obtain the size dependent natural frequencies of nano-plate. The solution procedure considers the entire nano-plate as a single super-continuum element. Effect of nonlocal parameter, lengths of nano-plate, aspect ratio, mode number, material properties, thickness and foundation on circular frequencies are investigated. It is seen that the nonlocal frequencies of the nano-plate are smaller in comparison to those from the classical theory and this is more pronounced for small lengths and higher vibration modes. It is also found that as the aspect ratio increases or the nanoplate becomes more elliptical, the small scale effect on natural frequencies increases. Further, it is observed that the elastic foundation decreases the influence of nonlocal parameter on the results. Since the effect of shear deformations plays an important role in vibration analysis and design of nano-plates, by predicting smaller values for fundamental frequencies, the study of these nano-structures using thick plate theories such as Mindlin plate theory is essential.

  14. Strong Local-Nonlocal Coupling for Integrated Fracture Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silling, Stewart A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, John A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seleson, Pablo D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bond, Stephen D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parks, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, Daniel Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ostien, Jakob [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Gunzburger, Max [Florida State Univ., Tallahassee, FL (United States)

    2015-09-01

    Peridynamics, a nonlocal extension of continuum mechanics, is unique in its ability to capture pervasive material failure. Its use in the majority of system-level analyses carried out at Sandia, however, is severely limited, due in large part to computational expense and the challenge posed by the imposition of nonlocal boundary conditions. Combined analyses in which peridynamics is em- ployed only in regions susceptible to material failure are therefore highly desirable, yet available coupling strategies have remained severely limited. This report is a summary of the Laboratory Directed Research and Development (LDRD) project "Strong Local-Nonlocal Coupling for Inte- grated Fracture Modeling," completed within the Computing and Information Sciences (CIS) In- vestment Area at Sandia National Laboratories. A number of challenges inherent to coupling local and nonlocal models are addressed. A primary result is the extension of peridynamics to facilitate a variable nonlocal length scale. This approach, termed the peridynamic partial stress, can greatly reduce the mathematical incompatibility between local and nonlocal equations through reduction of the peridynamic horizon in the vicinity of a model interface. A second result is the formulation of a blending-based coupling approach that may be applied either as the primary coupling strategy, or in combination with the peridynamic partial stress. This blending-based approach is distinct from general blending methods, such as the Arlequin approach, in that it is specific to the coupling of peridynamics and classical continuum mechanics. Facilitating the coupling of peridynamics and classical continuum mechanics has also required innovations aimed directly at peridynamic models. Specifically, the properties of peridynamic constitutive models near domain boundaries and shortcomings in available discretization strategies have been addressed. The results are a class of position-aware peridynamic constitutive laws for

  15. Non-local parallel transport in BOUT++

    CERN Document Server

    Omotani, J T; Havlickova, E; Umansky, M

    2015-01-01

    Non-local closures allow kinetic effects on parallel transport to be included in fluid simulations. This is especially important in the scrape-off layer, but to be useful there the non-local model requires consistent kinetic boundary conditions at the sheath. A non-local closure scheme based on solution of a kinetic equation using a diagonalized moment expansion has been previously reported. We derive a method for imposing kinetic boundary conditions in this scheme and discuss their implementation in BOUT++. To make it feasible to implement the boundary conditions in the code, we are lead to transform the non-local model to a different moment basis, better adapted to describe parallel dynamics. The new basis has the additional benefit of enabling substantial optimization of the closure calculation, resulting in an O(10) speedup of the non-local code.

  16. Lorentz Invariant CPT Violating Effects for a Class of Gauge-invariant Nonlocal Thirring Models

    CERN Document Server

    Patra, Pinaki

    2013-01-01

    CPT violation and Lorentz invariance can coexist in the framework of non-local field theory. Local gauge-invariance may not hold for the few non-local interaction terms. However, the gauge-invariance for the non-local interaction term can be formulated by the inclusion of Swinger non-integrable phase factor. In this article we have proposed a class of CPT violating Lorentz invariant Nonlocal Gauge-invariant models which can be termed as non-local gauge-invariant Thirring models. The inclusion of non-locality will modify the current conservation laws. Also, the possible particle antiparticle mass-splitting in this respect is discussed.

  17. Nonlocal Response in Plasmonic Nanostructures

    DEFF Research Database (Denmark)

    Wubs, Martijn; Mortensen, N. Asger

    2016-01-01

    After a brief overview of nanoplasmonics experiments that defy explanation with classical electrodynamics, we introduce nonlocal response as a main reason for non-classical effects. This concept is first introduced phenomenologically, and afterwards based on the semi-classical hydrodynamic Drude ...

  18. Fully nonlocal quantum correlations

    CERN Document Server

    Aolita, Leandro; Acín, Antonio; Chiuri, Andrea; Vallone, Giuseppe; Mataloni, Paolo; Cabello, Adán

    2011-01-01

    Quantum mechanics is a nonlocal theory, but not as nonlocal as the no-signalling principle allows. However, there exist quantum correlations that exhibit maximal nonlocality: they are as nonlocal as any non-signalling correlations and thus have a local content, quantified by the fraction $p_L$ of events admitting a local description, equal to zero. Previous examples of maximal quantum nonlocality between two parties require an infinite number of measurements, and the corresponding Bell violation is not robust against noise. We show how every proof of the Kochen-Specker theorem gives rise to maximally nonlocal quantum correlations that involve a finite number of measurements and are robust against noise. We perform the experimental demonstration of a Bell test originating from the Peres-Mermin Kochen-Specker proof, providing an upper bound on the local content $p_L\\lesssim 0.22$.

  19. Optimization-based image reconstruction in x-ray computed tomography by sparsity exploitation of local continuity and nonlocal spatial self-similarity

    Science.gov (United States)

    Han-Ming, Zhang; Lin-Yuan, Wang; Lei, Li; Bin, Yan; Ai-Long, Cai; Guo-En, Hu

    2016-07-01

    The additional sparse prior of images has been the subject of much research in problems of sparse-view computed tomography (CT) reconstruction. A method employing the image gradient sparsity is often used to reduce the sampling rate and is shown to remove the unwanted artifacts while preserve sharp edges, but may cause blocky or patchy artifacts. To eliminate this drawback, we propose a novel sparsity exploitation-based model for CT image reconstruction. In the presented model, the sparse representation and sparsity exploitation of both gradient and nonlocal gradient are investigated. The new model is shown to offer the potential for better results by introducing a similarity prior information of the image structure. Then, an effective alternating direction minimization algorithm is developed to optimize the objective function with a robust convergence result. Qualitative and quantitative evaluations have been carried out both on the simulation and real data in terms of accuracy and resolution properties. The results indicate that the proposed method can be applied for achieving better image-quality potential with the theoretically expected detailed feature preservation. Project supported by the National Natural Science Foundation of China (Grant No. 61372172).

  20. Non-local model analysis of heat pulse propagation

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, Takuya [Interdisciplinary Graduate School of Engineering Sciences, Kyushu Univ., Kasuga, Fukuoka (Japan); Itoh, Sanae-I.; Yagi, Masatoshi

    1998-10-01

    A new theoretical model equation which includes the non-local effect in the heat flux is proposed to study the transient transport phenomena. A non-local heat flux, which is expressed in terms of the integral equation, is superimposed on the conventional form of the heat flux. This model is applied to describe the experimental results from the power switching [Stroth U, et al 1996 Plasma Phys. Control. Fusion 38 1087] and the power modulation experiments [Giannone L, et al 1992 Nucl. Fusion 32 1985] in the W7-AS stellarator. A small fraction of non-local component in the heat flux is found to be very effective in modifying the response against an external modulation. The transient feature of the transport property, which are observed in the response of heat pulse propagation, are qualitatively reproduced by the transport simulations based on this model. A possibility is discussed to determine the correlation length of the non-local effect experimentally by use of the results of transport simulations. (author)

  1. Nonlocal General Relativity

    CERN Document Server

    Mashhoon, B

    2014-01-01

    A brief account of the present status of the recent nonlocal generalization of Einstein's theory of gravitation is presented. The main physical assumptions that underlie this theory are described. We clarify the physical meaning and significance of Weitzenb\\"ock's torsion, and emphasize its intimate relationship with the gravitational field, characterized by the Riemannian curvature of spacetime. In this theory, nonlocality can simulate dark matter; in fact, in the Newtonian regime, we recover the phenomenological Tohline-Kuhn approach to modified gravity. To account for the observational data regarding dark matter, nonlocality is associated with a characteristic length scale of order 1 kpc. The confrontation of nonlocal gravity with observation is briefly discussed.

  2. Quantum Nonlocality and Reality

    Science.gov (United States)

    Bell, Mary; Gao, Shan

    2016-09-01

    Preface; Part I. John Stewart Bell: The Physicist: 1. John Bell: the Irish connection Andrew Whitaker; 2. Recollections of John Bell Michael Nauenberg; 3. John Bell: recollections of a great scientist and a great man Gian-Carlo Ghirardi; Part II. Bell's Theorem: 4. What did Bell really prove? Jean Bricmont; 5. The assumptions of Bell's proof Roderich Tumulka; 6. Bell on Bell's theorem: the changing face of nonlocality Harvey R. Brown and Christopher G. Timpson; 7. Experimental tests of Bell inequalities Marco Genovese; 8. Bell's theorem without inequalities: on the inception and scope of the GHZ theorem Olival Freire, Jr and Osvaldo Pessoa, Jr; 9. Strengthening Bell's theorem: removing the hidden-variable assumption Henry P. Stapp; Part III. Nonlocality: Illusions or Reality?: 10. Is any theory compatible with the quantum predictions necessarily nonlocal? Bernard d'Espagnat; 11. Local causality, probability and explanation Richard A. Healey; 12. Bell inequality and many-worlds interpretation Lev Vaidman; 13. Quantum solipsism and non-locality Travis Norsen; 14. Lessons of Bell's theorem: nonlocality, yes; action at a distance, not necessarily Wayne C. Myrvold; 15. Bell non-locality, Hardy's paradox and hyperplane dependence Gordon N. Fleming; 16. Some thoughts on quantum nonlocality and its apparent incompatibility with relativity Shan Gao; 17. A reasonable thing that just might work Daniel Rohrlich; 18. Weak values and quantum nonlocality Yakir Aharonov and Eliahu Cohen; Part IV. Nonlocal Realistic Theories: 19. Local beables and the foundations of physics Tim Maudlin; 20. John Bell's varying interpretations of quantum mechanics: memories and comments H. Dieter Zeh; 21. Some personal reflections on quantum non-locality and the contributions of John Bell Basil J. Hiley; 22. Bell on Bohm Sheldon Goldstein; 23. Interactions and inequality Philip Pearle; 24. Gravitation and the noise needed in objective reduction models Stephen L. Adler; 25. Towards an objective

  3. Quantum nonlocality does not exist.

    Science.gov (United States)

    Tipler, Frank J

    2014-08-05

    Quantum nonlocality is shown to be an artifact of the Copenhagen interpretation, in which each observed quantity has exactly one value at any instant. In reality, all physical systems obey quantum mechanics, which obeys no such rule. Locality is restored if observed and observer are both assumed to obey quantum mechanics, as in the many-worlds interpretation (MWI). Using the MWI, I show that the quantum side of Bell's inequality, generally believed nonlocal, is really due to a series of three measurements (not two as in the standard, oversimplified analysis), all three of which have only local effects. Thus, experiments confirming "nonlocality" are actually confirming the MWI. The mistaken interpretation of nonlocality experiments depends crucially on a question-begging version of the Born interpretation, which makes sense only in "collapse" versions of quantum theory, about the meaning of the modulus of the wave function, so I use the interpretation based on the MWI, namely that the wave function is a world density amplitude, not a probability amplitude. This view allows the Born interpretation to be derived directly from the Schrödinger equation, by applying the Schrödinger equation to both the observed and the observer.

  4. Electro-thermal vibration of a smart coupled nanobeam system with an internal flow based on nonlocal elasticity theory

    Energy Technology Data Exchange (ETDEWEB)

    Atabakhshian, V.; Shooshtari, A.; Karimi, M., E-mail: karimi_mh@yahoo.com

    2015-01-01

    In this study, nonlinear vibration and stability of a fluid-conveying nanotube (FCNT), elastically coupled to a smart piezoelectric polymeric beam (PPB) is investigated based on nonlocal elasticity theory, Euler–Bernoulli beam model and energy approach. In order to obtain an active instability control of FCNT, the PPB is longitudinally polarized as an actuator while in the absence of an imposed electric field it is also possible to be used as an alarm biosensor. Simulating the above smart coupled nanobeam system alike the double nanobeam systems (which are relatively developed by other authors) leads to obtain nonlinear differential equations of motion. The linear natural and damping frequencies are achieved by ignoring all the system nonlinearities which are then considered to obtain nonlinear frequencies using an iterative method. The effects of geometric nonlinearity, small scale parameter, coupled medium constants, Knudsen number, temperature change, aspect ratio and external applied voltage on critical flow velocity are studied in details. It is concluded that applying an electric voltage on PPB will increase the stability of FCNT. It is hoped that this research will provide a new approach to smart instability control of FCNTs which is no yet reported.

  5. Electro-thermal vibration of a smart coupled nanobeam system with an internal flow based on nonlocal elasticity theory

    Science.gov (United States)

    Atabakhshian, V.; Shooshtari, A.; Karimi, M.

    2015-01-01

    In this study, nonlinear vibration and stability of a fluid-conveying nanotube (FCNT), elastically coupled to a smart piezoelectric polymeric beam (PPB) is investigated based on nonlocal elasticity theory, Euler-Bernoulli beam model and energy approach. In order to obtain an active instability control of FCNT, the PPB is longitudinally polarized as an actuator while in the absence of an imposed electric field it is also possible to be used as an alarm biosensor. Simulating the above smart coupled nanobeam system alike the double nanobeam systems (which are relatively developed by other authors) leads to obtain nonlinear differential equations of motion. The linear natural and damping frequencies are achieved by ignoring all the system nonlinearities which are then considered to obtain nonlinear frequencies using an iterative method. The effects of geometric nonlinearity, small scale parameter, coupled medium constants, Knudsen number, temperature change, aspect ratio and external applied voltage on critical flow velocity are studied in details. It is concluded that applying an electric voltage on PPB will increase the stability of FCNT. It is hoped that this research will provide a new approach to smart instability control of FCNTs which is no yet reported.

  6. Buckling analysis and smart control of SLGS using elastically coupled PVDF nanoplate based on the nonlocal Mindlin plate theory

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Kolahchi, R.; Vossough, H. [Faculty of Mechanical Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2012-11-15

    This study presents an analytical approach for buckling analysis and smart control of a single layer graphene sheet (SLGS) using a coupled polyvinylidene fluoride (PVDF) nanoplate. The SLGS and PVDF nanoplate are considered to be coupled by an enclosing elastic medium which is simulated by the Pasternak foundation. The PVDF nanoplate is subjected to an applied voltage in the thickness direction which operates in control of critical load of the SLGS. In order to satisfy the Maxwell equation, electric potential distribution is assumed as a combination of a half-cosine and linear variation. The exact analysis is performed for the case when all four ends are simply supported and free electrical boundary condition. Adopting the nonlocal Mindlin plate theory, the governing equations are derived based on the energy method and Hamilton's principle. A detailed parametric study is conducted to elucidate the influences of the small scale coefficient, stiffness of the internal elastic medium, graphene length, mode number and external electric voltage on the buckling smart control of the SLGS. The results depict that the imposed external voltage is an effective controlling parameter for buckling of the SLGS. This study might be useful for the design and smart control of nano-devices.

  7. Experimental falsification of Leggett's nonlocal variable model.

    Science.gov (United States)

    Branciard, Cyril; Ling, Alexander; Gisin, Nicolas; Kurtsiefer, Christian; Lamas-Linares, Antia; Scarani, Valerio

    2007-11-23

    Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also, some models based on nonlocal variables, if subject to apparently "reasonable" constraints, may fail to reproduce quantum physics. In this Letter, we introduce a family of inequalities, which use a finite number of measurement settings, and which therefore allow testing Leggett's nonlocal model versus quantum physics. Our experimental data falsify Leggett's model and are in agreement with quantum predictions.

  8. A robust PDE appraoch to super resolution with nonlocal TV regularization term%带有非局部全变分正则项的鲁棒偏微分方程超分辨率方法

    Institute of Scientific and Technical Information of China (English)

    曾维理; 路小波

    2011-01-01

    超分辨率重建算法可以利用低分辨率图像之间的互补信息来重建一帧高分辨率图像。得到最近视频图像去噪问题的启发,本文提出一种基于偏微分方程的鲁棒超分辨率重建方法,该方法以非局部全变差正则项作为变分模型的限制项。此外,根据低分辨率图像的差别,对数据保证项目进行加权,提高重建方法的鲁棒性。实验表明所提方法的有效性和实用性。%Super resolution (SR) reconstruction algorithms make use of complimentary information among low resolution (LR) images to yield a high resolution (HR) image. Inspired by recent development on the video denosing problem, we propose a partial differential equation (PDE) model for SR based on a constrained variational model that use the nonlocal total variation (TV) as a regularization term. Experiments show the effectiveness and practicability of the proposed method.

  9. In-plane vibration of FG micro/nano-mass sensor based on nonlocal theory under various thermal loading via differential transformation method

    Science.gov (United States)

    Rahmani, O.; Mohammadi Niaei, A.; Hosseini, S. A. H.; Shojaei, M.

    2017-01-01

    In the present study, free vibration model of a cantilever functionally graded (FG) nanobeam with an attached mass at tip and under various thermal loading and two types of material distribution is introduced. The vibration performance is considered using nonlocal Euler-Bernoulli beam theory. Two types of thermal loading, namely, uniform and nonlinear temperature rises through the thickness direction are considered. Thermo-mechanical properties of FG nano mass sensor are supposed to vary smoothly and continuously throughout the thickness based on power-law and Mori Tanaka distributions of material properties. Eringen non-local elasticity theory is exploited to describe the size dependency of FG nanobeam. The governing equations of the system with both axial and transverse displacements are derived based on Hamilton's principle and solved utilizing the differential transformation method (DTM) to find the non-dimensional natural frequencies. The results have good agreements with those discussing in the literature. After validation of the present model, the effect of various parameters such as mass and position of the attached nano particle, FG power-law exponent, thermal load type, material distribution type and nonlocal parameter on the frequency of nano sensor are studied. It is shown that the present model produces results of high accuracy, and it can be used as a benchmark in future studies of the free vibration of FG Nano-Mass Sensors.

  10. Wave propagation analysis of quasi-3D FG nanobeams in thermal environment based on nonlocal strain gradient theory

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza

    2016-09-01

    This article examines the application of nonlocal strain gradient elasticity theory to wave dispersion behavior of a size-dependent functionally graded (FG) nanobeam in thermal environment. The theory contains two scale parameters corresponding to both nonlocal and strain gradient effects. A quasi-3D sinusoidal beam theory considering shear and normal deformations is employed to present the formulation. Mori-Tanaka micromechanical model is used to describe functionally graded material properties. Hamilton's principle is employed to obtain the governing equations of nanobeam accounting for thickness stretching effect. These equations are solved analytically to find the wave frequencies and phase velocities of the FG nanobeam. It is indicated that wave dispersion behavior of FG nanobeams is significantly affected by temperature rise, nonlocality, length scale parameter and material composition.

  11. Extreme nonlocality with one photon

    CERN Document Server

    Heaney, Libby; Santos, Marcelo F; Vedral, Vlatko

    2009-01-01

    The bizarre concept of nonlocality appears in quantum mechanics because the properties of two or more particles may be assigned globally and are not always pinned to each particle individually. Experiments using two, three, or more of these entangled particles have strongly rejected a local realist interpretation of nature. Nonlocality is also argued to be an intrinsic property of a quantum field, implying that just one excitation, a photon for instance, could also by itself violate local realism. Here we show that one photon superposed symmetrically over many distant sites (which in quantum information terms is a W-state) can give a stunning all-versus-nothing demolition of local realism in an identical manner to the GHZ class of states. The elegance of this result is that it is due solely to the wave-particle duality of light and matter. We present experimental implementations capable of testing our predictions.

  12. Non-local massive gravity

    CERN Document Server

    Modesto, Leonardo

    2013-01-01

    We present a general covariant action for massive gravity merging together a class of "non-polynomial" and super-renormalizable or finite theories of gravity with the non-local theory of gravity recently proposed by Jaccard, Maggiore and Mitsou (arXiv:1305.3034 [hep-th]). Our diffeomorphism invariant action gives rise to the equations of motion appearing in non-local massive massive gravity plus quadratic curvature terms. Not only the massive graviton propagator reduces smoothly to the massless one without a vDVZ discontinuity, but also our finite theory of gravity is unitary at tree level around the Minkowski background. We also show that, as long as the graviton mass $m$ is much smaller the today's Hubble parameter $H_0$, a late-time cosmic acceleration can be realized without a dark energy component due to the growth of a scalar degree of freedom. In the presence of the cosmological constant $\\Lambda$, the dominance of the non-local mass term leads to a kind of "degravitation" for $\\Lambda$ at the late cos...

  13. Study of the sensitivity and resonant frequency of the torsional modes of an AFM cantilever with a sidewall probe based on a nonlocal elasticity theory.

    Science.gov (United States)

    Abbasi, Mohammad; Karami Mohammadi, Ardeshir

    2015-05-01

    A relationship based on a nonlocal elasticity theory is developed to investigate the torsional sensitivity and resonant frequency of an atomic force microscope (AFM) with assembled cantilever probe (ACP). This ACP comprises a horizontal cantilever and a vertical extension, and a tip located at the free end of the extension, which makes the AFM capable of topography at sidewalls of microstructures. First, the governing differential equations of motion and boundary conditions for dynamic analysis are obtained by a combination of the basic equations of nonlocal elasticity theory and Hamilton's principle. Afterward, a closed-form expression for the sensitivity of vibration modes has been obtained using the relationship between the resonant frequency and contact stiffness of cantilever and sample. These analysis accounts for a better representation of the torsional behavior of an AFM with sidewall probe where the small-scale effect are significant. The results of the proposed model are compared with those of classical beam theory. The results show that the sensitivities and resonant frequencies of ACP predicted by the nonlocal elasticity theory are smaller than those obtained by the classical beam theory.

  14. Nonlocal Infrared Modifications of Gravity. A Review

    CERN Document Server

    Maggiore, Michele

    2016-01-01

    We review an approach developed in the last few years by our group in which GR is modified in the infrared, at an effective level, by nonlocal terms associated to a mass scale. We begin by recalling the notion of quantum effective action and its associated nonlocalities, illustrating some of their features with the anomaly-induced effective actions in $D=2$ and $D=4$. We examine conceptual issues of nonlocal theories such as causality, degrees of freedoms and ghosts, stressing the importance of the fact that these nonlocalities only emerge at the effective level. We discuss a particular class of nonlocal theories where the nonlocal operator is associated to a mass scale, and we show that they perform very well in the comparison with cosmological observations, to the extent that they fit CMB, supernovae, BAO and structure formation data at a level fully competitive with $\\Lambda$CDM, with the same number of free parameters. We explore some extensions of these `minimal' models, and we finally discuss some direc...

  15. Size-dependent geometrically nonlinear free vibration analysis of fractional viscoelastic nanobeams based on the nonlocal elasticity theory

    Science.gov (United States)

    Ansari, R.; Faraji Oskouie, M.; Gholami, R.

    2016-01-01

    In recent decades, mathematical modeling and engineering applications of fractional-order calculus have been extensively utilized to provide efficient simulation tools in the field of solid mechanics. In this paper, a nonlinear fractional nonlocal Euler-Bernoulli beam model is established using the concept of fractional derivative and nonlocal elasticity theory to investigate the size-dependent geometrically nonlinear free vibration of fractional viscoelastic nanobeams. The non-classical fractional integro-differential Euler-Bernoulli beam model contains the nonlocal parameter, viscoelasticity coefficient and order of the fractional derivative to interpret the size effect, viscoelastic material and fractional behavior in the nanoscale fractional viscoelastic structures, respectively. In the solution procedure, the Galerkin method is employed to reduce the fractional integro-partial differential governing equation to a fractional ordinary differential equation in the time domain. Afterwards, the predictor-corrector method is used to solve the nonlinear fractional time-dependent equation. Finally, the influences of nonlocal parameter, order of fractional derivative and viscoelasticity coefficient on the nonlinear time response of fractional viscoelastic nanobeams are discussed in detail. Moreover, comparisons are made between the time responses of linear and nonlinear models.

  16. Family of nonlocal bound entangled states

    Science.gov (United States)

    Yu, Sixia; Oh, C. H.

    2017-03-01

    Bound entanglement, being entangled yet not distillable, is essential to our understanding of the relations between nonlocality and entanglement besides its applications in certain quantum information tasks. Recently, bound entangled states that violate a Bell inequality have been constructed for a two-qutrit system, disproving a conjecture by Peres that bound entanglement is local. Here we construct this kind of nonlocal bound entangled state for all finite dimensions larger than two, making possible their experimental demonstration in most general systems. We propose a Bell inequality, based on a Hardy-type argument for nonlocality, and a steering inequality to identify their nonlocality. We also provide a family of entanglement witnesses to detect their entanglement beyond the Bell inequality and the steering inequality.

  17. Nonlocality from Local Contextuality

    Science.gov (United States)

    Liu, Bi-Heng; Hu, Xiao-Min; Chen, Jiang-Shan; Huang, Yun-Feng; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can; Cabello, Adán

    2016-11-01

    We experimentally show that nonlocality can be produced from single-particle contextuality by using two-particle correlations which do not violate any Bell inequality by themselves. This demonstrates that nonlocality can come from an a priori different simpler phenomenon, and connects contextuality and nonlocality, the two critical resources for, respectively, quantum computation and secure communication. From the perspective of quantum information, our experiment constitutes a proof of principle that quantum systems can be used simultaneously for both quantum computation and secure communication.

  18. Nonlocality from Local Contextuality.

    Science.gov (United States)

    Liu, Bi-Heng; Hu, Xiao-Min; Chen, Jiang-Shan; Huang, Yun-Feng; Han, Yong-Jian; Li, Chuan-Feng; Guo, Guang-Can; Cabello, Adán

    2016-11-25

    We experimentally show that nonlocality can be produced from single-particle contextuality by using two-particle correlations which do not violate any Bell inequality by themselves. This demonstrates that nonlocality can come from an a priori different simpler phenomenon, and connects contextuality and nonlocality, the two critical resources for, respectively, quantum computation and secure communication. From the perspective of quantum information, our experiment constitutes a proof of principle that quantum systems can be used simultaneously for both quantum computation and secure communication.

  19. Dynamic crack growth in a nonlocal progressively cavitating solid

    DEFF Research Database (Denmark)

    Needleman, A.; Tvergaard, Viggo

    1998-01-01

    Dynamic crack growth is analyzed numerically using a nonlocal constitutive formulation for a porous ductile material. The delocalization relates to the void growth and coalescence mechanism and is incorporated in terms of an integral condition on the rate of increase of the void volume fraction....... The material is modeled as elastic-viscoplastic with the thermal softening due to adiabatic heating accounted for. Finite element computations are carried our for edge cracked specimens subject to tensile impact loading. Two values of the material characteristic length and two finite-element discretizations...... to increase and the crack speed to decrease with increasing values of the material characteristic length. The crack growth predictions using the nonlocal constitutive model exhibit less mesh sensitivity than the corresponding ones based on the local constitutive relation. However, for the largest value...

  20. Nonlocal theory of curved rods. 2-D, high order, Timoshenko’s and Euler-Bernoulli models

    Directory of Open Access Journals (Sweden)

    Zozulya V.V.

    2017-09-01

    Full Text Available New models for plane curved rods based on linear nonlocal theory of elasticity have been developed. The 2-D theory is developed from general 2-D equations of linear nonlocal elasticity using a special curvilinear system of coordinates related to the middle line of the rod along with special hypothesis based on assumptions that take into account the fact that the rod is thin. High order theory is based on the expansion of the equations of the theory of elasticity into Fourier series in terms of Legendre polynomials. First, stress and strain tensors, vectors of displacements and body forces have been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate. Thereby, all equations of elasticity including nonlocal constitutive relations have been transformed to the corresponding equations for Fourier coefficients. Then, in the same way as in the theory of local elasticity, a system of differential equations in terms of displacements for Fourier coefficients has been obtained. First and second order approximations have been considered in detail. Timoshenko’s and Euler-Bernoulli theories are based on the classical hypothesis and the 2-D equations of linear nonlocal theory of elasticity which are considered in a special curvilinear system of coordinates related to the middle line of the rod. The obtained equations can be used to calculate stress-strain and to model thin walled structures in micro- and nanoscales when taking into account size dependent and nonlocal effects.

  1. Short Time Uniqueness Results for Solutions of Nonlocal and Non-monotone Geometric Equations

    CERN Document Server

    Barles, Guy; Mitake, Hiroyoshi

    2010-01-01

    We describe a method to show short time uniqueness results for viscosity solutions of general nonlocal and non-monotone second-order geometric equations arising in front propagation problems. Our method is based on some lower gradient bounds for the solution. These estimates are crucial to obtain regularity properties of the front, which allow to deal with nonlocal terms in the equations. Applications to short time uniqueness results for the initial value problems for dislocation type equations, asymptotic equations of a FitzHugh-Nagumo type system and equations depending on the Lebesgue measure of the fronts are presented.

  2. Solutions to nonlocal fractional differential equations using a noncompact semigroup

    Directory of Open Access Journals (Sweden)

    Shaochun Ji

    2013-10-01

    Full Text Available This article concerns the existence of solutions to nonlocal fractional differential equations in Banach spaces. By using a type of newly-defined measure of noncompactness, we discuss this problem in general Banach spaces without any compactness assumptions to the operator semigroup. Some existence results are obtained when the nonlocal term is compact and when is Lipschitz continuous.

  3. A Note on a Nonlocal Nonlinear Reaction-Diffusion Model

    OpenAIRE

    Walker, Christoph

    2011-01-01

    We give an application of the Crandall-Rabinowitz theorem on local bifurcation to a system of nonlinear parabolic equations with nonlocal reaction and cross-diffusion terms as well as nonlocal initial conditions. The system arises as steady-state equations of two interacting age-structured populations.

  4. Nonlocal effects on dynamic damage accumulation in brittle solids

    Energy Technology Data Exchange (ETDEWEB)

    Chen, E.P.

    1995-12-01

    This paper presents a nonlocal analysis of the dynamic damage accumulation processes in brittle solids. A nonlocal formulation of a microcrack based continuum damage model is developed and implemented into a transient dynamic finite element computer code. The code is then applied to the study of the damage accumulation process in a concrete plate with a central hole and subjected to the action of a step tensile pulse applied at opposite edges of the plate. Several finite element discretizations are used to examine the mesh size effect. Comparisons between calculated results based on local and nonlocal formulations are made and nonlocal effects are discussed.

  5. Making space for nonlocality

    Science.gov (United States)

    Millen, James

    2016-04-01

    George Musser's book Spooky Action at a Distance focuses on one of quantum physics' more challenging concepts, nonlocality, and its multitude of implications, particularly its assault on space itself.

  6. Nonlocal continuum field theories

    CERN Document Server

    2002-01-01

    Nonlocal continuum field theories are concerned with material bodies whose behavior at any interior point depends on the state of all other points in the body -- rather than only on an effective field resulting from these points -- in addition to its own state and the state of some calculable external field. Nonlocal field theory extends classical field theory by describing the responses of points within the medium by functionals rather than functions (the "constitutive relations" of classical field theory). Such considerations are already well known in solid-state physics, where the nonlocal interactions between the atoms are prevalent in determining the properties of the material. The tools developed for crystalline materials, however, do not lend themselves to analyzing amorphous materials, or materials in which imperfections are a major part of the structure. Nonlocal continuum theories, by contrast, can describe these materials faithfully at scales down to the lattice parameter. This book presents a unif...

  7. The frustrated Brownian motion of nonlocal solitary waves

    CERN Document Server

    Folli, Viola

    2010-01-01

    We investigate the evolution of solitary waves in a nonlocal medium in the presence of disorder. By using a perturbational approach, we show that an increasing degree of nonlocality may largely hamper the Brownian motion of self-trapped wave-packets. The result is valid for any kind of nonlocality and in the presence of non-paraxial effects. Analytical predictions are compared with numerical simulations based on stochastic partial differential equation

  8. A Nonlocal Model for Carbon Nanotubes under Axial Loads

    Directory of Open Access Journals (Sweden)

    Raffaele Barretta

    2013-01-01

    Full Text Available Various beam theories are formulated in literature using the nonlocal differential constitutive relation proposed by Eringen. A new variational framework is derived in the present paper by following a consistent thermodynamic approach based on a nonlocal constitutive law of gradient-type. Contrary to the results obtained by Eringen, the new model exhibits the nonlocality effect also for constant axial load distributions. The treatment can be adopted to get new benchmarks for numerical analyses.

  9. Buckling of Functionally Graded Nanobeams Based on the Nonlocal New First-Order Shear Deformation Beam Theory

    Directory of Open Access Journals (Sweden)

    Houari M.S.A.

    2014-04-01

    Full Text Available In this work, the size-dependent buckling behavior of functionally graded (FG nanobeams is investigated on the basis of the nonlocal continuum model. The material properties of FG nanobeams are assumed to vary through the thickness according to the power law. In addition, Poisson’s ratio is assumed constant in the current model. The nanobeams is modelled according to the new first order shear beam theory with small deformation and the equilibrium equations are derived using the Hamilton’s principle. The Naviertype solution is developed for simply-supported boundary conditions, and exact formulas are proposed for the buckling load. The effects of nonlocal parameter, aspect ratio, various material compositions on the stability responses of the FG nanobeams are discussed.

  10. Nonlocal optical properties in periodic lattice of graphene layers.

    Science.gov (United States)

    Chern, Ruey-Lin; Han, Dezhuan

    2014-02-24

    Based on the effective medium model, nonlocal optical properties in periodic lattice of graphene layers with the period much less than the wavelength are investigated. Strong nonlocal effects are found in a broad frequency range for TM polarization, where the effective permittivity tensor exhibits the Lorentzian resonance. The resonance frequency varies with the wave vector and coincides well with the polaritonic mode. Nonlocal features are manifest on the emergence of additional wave and the occurrence of negative refraction. By examining the characters of the eigenmode, the nonlocal optical properties are attributed to the excitation of plasmons on the graphene surfaces.

  11. Nonlocal Regularized Algebraic Reconstruction Techniques for MRI: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Xin Li

    2013-01-01

    Full Text Available We attempt to revitalize researchers' interest in algebraic reconstruction techniques (ART by expanding their capabilities and demonstrating their potential in speeding up the process of MRI acquisition. Using a continuous-to-discrete model, we experimentally study the application of ART into MRI reconstruction which unifies previous nonuniform-fast-Fourier-transform- (NUFFT- based and gridding-based approaches. Under the framework of ART, we advocate the use of nonlocal regularization techniques which are leveraged from our previous research on modeling photographic images. It is experimentally shown that nonlocal regularization ART (NR-ART can often outperform their local counterparts in terms of both subjective and objective qualities of reconstructed images. On one real-world k-space data set, we find that nonlocal regularization can achieve satisfactory reconstruction from as few as one-third of samples. We also address an issue related to image reconstruction from real-world k-space data but overlooked in the open literature: the consistency of reconstructed images across different resolutions. A resolution-consistent extension of NR-ART is developed and shown to effectively suppress the artifacts arising from frequency extrapolation. Both source codes and experimental results of this work are made fully reproducible.

  12. Nonlocal Anomalous Hall Effect

    Science.gov (United States)

    Zhang, Steven S.-L.; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect—the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt /YIG structures.

  13. Nonlocal Anomalous Hall Effect.

    Science.gov (United States)

    Zhang, Steven S-L; Vignale, Giovanni

    2016-04-01

    The anomalous Hall (AH) effect is deemed to be a unique transport property of ferromagnetic metals, caused by the concerted action of spin polarization and spin-orbit coupling. Nevertheless, recent experiments have shown that the effect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic insulator [yttrium iron garnet (YIG)], even when precautions are taken to ensure that there is no induced magnetization in the metal. We propose a theory of this effect based on the combined action of spin-dependent scattering from the magnetic interface and the spin-Hall effect in the bulk of the metal. At variance with previous theories, we predict the effect to be of first order in the spin-orbit coupling, just as the conventional anomalous Hall effect-the only difference being the spatial separation of the spin-orbit interaction and the magnetization. For this reason we name this effect the nonlocal anomalous Hall effect and predict that its sign will be determined by the sign of the spin-Hall angle in the metal. The AH conductivity that we calculate from our theory is in order of magnitude agreement with the measured values in Pt/YIG structures.

  14. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Science.gov (United States)

    Mohammadimehr, M.; Mohammadi-Dehabadi, A. A.; Maraghi, Z. Khoddami

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  15. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadimehr, M., E-mail: mmohammadimehr@kashanu.ac.ir [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Mohammadi-Dehabadi, A.A. [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Department of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Maraghi, Z. Khoddami [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of)

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  16. Pattern Based Term Extraction Using ACABIT System

    CERN Document Server

    Takeuchi, Koichi; Koyama, Teruo; Daille, Béatrice; Romary, Laurent

    2009-01-01

    In this paper, we propose a pattern-based term extraction approach for Japanese, applying ACABIT system originally developed for French. The proposed approach evaluates termhood using morphological patterns of basic terms and term variants. After extracting term candidates, ACABIT system filters out non-terms from the candidates based on log-likelihood. This approach is suitable for Japanese term extraction because most of Japanese terms are compound nouns or simple phrasal patterns.

  17. Nonlocal diffusion and applications

    CERN Document Server

    Bucur, Claudia

    2016-01-01

    Working in the fractional Laplace framework, this book provides models and theorems related to nonlocal diffusion phenomena. In addition to a simple probabilistic interpretation, some applications to water waves, crystal dislocations, nonlocal phase transitions, nonlocal minimal surfaces and Schrödinger equations are given. Furthermore, an example of an s-harmonic function, its harmonic extension and some insight into a fractional version of a classical conjecture due to De Giorgi are presented. Although the aim is primarily to gather some introductory material concerning applications of the fractional Laplacian, some of the proofs and results are new. The work is entirely self-contained, and readers who wish to pursue related subjects of interest are invited to consult the rich bibliography for guidance.

  18. Disentangling Nonlocality and Teleportation

    CERN Document Server

    Hardy, L

    1999-01-01

    Quantum entanglement can be used to demonstrate nonlocality and to teleport a quantum state from one place to another. The fact that entanglement can be used to do both these things has led people to believe that teleportation is a nonlocal effect. In this paper it is shown that teleportation is conceptually independent of nonlocality. This is done by constructing a toy local theory in which cloning is not possible (without a no-cloning theory teleportation makes limited sense) but teleportation is. Teleportation in this local theory is achieved in an analogous way to the way it is done with quantum theory. This work provides some insight into what type of process teleportation is.

  19. Notes on nonlocal projective measurements in relativistic systems

    CERN Document Server

    Lin, Shih-Yuin

    2013-01-01

    In quantum mechanical bipartite systems, naive extensions of von Neumann's projective measurement to nonlocal variables can produce superluminal signals and thus violate causality. We analyze the projective quantum nondemolition state-verification in a two-spin system and see how the projection introduces nonlocality without entanglement. For the ideal measurements of "R-nonlocal" variables, we argue that causality violation can be resolved by introducing further restrictions on the post-measurement states, which makes the measurement "Q-nonlocal". After we generalize these ideas to quantum mechanical harmonic oscillators, we look into the projective measurements of the particle number of a single mode or a wave-packet of a relativistic quantum field in Minkowski space. It turns out that the causality-violating terms in the expectation values of the local operators, generated either by the ideal measurement of the "R-nonlocal" variable or the quantum nondemolition verification of a Fock state, are all suppres...

  20. Nonlocal formalism for nanoplasmonics: Phenomenological and semi-classical considerations

    DEFF Research Database (Denmark)

    Mortensen, N. Asger

    2013-01-01

    The plasmon response of metallic nanostructures is anticipated to exhibit nonlocal dynamics of the electron gas when exploring the true nanoscale. We extend the local-response approximation (based on Ohm's law) to account for a general short-range nonlocal response of the homogeneous electron gas...

  1. Spectral dimension from nonlocal dynamics on causal sets

    Science.gov (United States)

    Belenchia, Alessio; Benincasa, Dionigi M. T.; Marcianò, Antonino; Modesto, Leonardo

    2016-02-01

    We investigate the spectral dimension obtained from nonlocal continuum d'Alembertians derived from causal sets. We find a universal dimensional reduction to two dimensions, in all dimensions. We conclude by discussing the validity and relevance of our results within the broader context of quantum field theories based on these nonlocal dynamics.

  2. Nonlocal N=1 Supersymmetry

    CERN Document Server

    Kimura, Tetsuji; Noumi, Toshifumi; Yamaguchi, Masahide

    2016-01-01

    We construct $\\mathcal{N}=1$ supersymmetric nonlocal theories in four dimension. We discuss higher derivative extensions of chiral and vector superfields, and write down generic forms of K\\"ahler potential and superpotential up to quadratic order. We derive the condition in which an auxiliary field remains non-dynamical, and the dynamical scalars and fermions are free from the ghost degrees of freedom. We also investigate the nonlocal effects on the supersymmetry breaking and find that supertrace (mass) formula is significantly modified even at the tree level.

  3. Nonlinear static analysis of single layer annular/circular graphene sheets embedded in Winkler–Pasternak elastic matrix based on non-local theory of Eringen

    Directory of Open Access Journals (Sweden)

    Shahriar Dastjerdi

    2016-06-01

    Full Text Available Nonlinear bending analysis of orthotropic annular/circular graphene sheets has been studied based on the non-local elasticity theory. The first order shear deformation theory (FSDT is applied in combination with the nonlinear Von-Karman strain field. The obtained differential equations are solved by using two methods, first the differential quadrature method (DQM and a new semi-analytical polynomial method (SAPM which is innovated by the authors. Applying the DQM or SAPM, the differential equations are transformed to nonlinear algebraic equations system. Then the Newton–Raphson iterative scheme is used. First, the obtained results from DQM and SAPM are compared and it is concluded that although the SAPM’s formulation is considerably simpler than DQM, however, the SAPM’s results are so close to DQM. The results are validated with available papers. Finally, the effects of small scale parameter on the results, the comparison between local and non-local theories, and linear to nonlinear analyses are investigated.

  4. Bending and Free Vibration Analysis of Nonlocal Functionally Graded Nanocomposite Timoshenko Beam Model Rreinforced by SWBNNT Based on Modified Coupled Stress Theory

    Directory of Open Access Journals (Sweden)

    M. Mohammadimehr

    2013-12-01

    Full Text Available In this article, the bending and free vibration analysis of functionally graded (FG nanocomposites Timoshenko beam model reinforced by single-walled boron nitride nanotube (SWBNNT using micro-mechanical approach embedded in an elastic medium is studied. The modified coupled stress (MCST and nonlocal elasticity theories are developed to take into account the size-dependent effect. The mechanical properties of FG boron nitride nanotube-reinforced composites are assumed to be graded in the thickness direction and estimated through the micro-mechanical approach. The governing equations of motion are obtained using Hamilton’s principle based on Timoshenko beam theory. The Navier's type solution is implemented to solve the equations that satisfy the simply supported boundary conditions. Furthermore, the influences of the slenderness ratio, length of nanocomposite beam, material length scale parameter, nonlocal parameter, power law index, axial wave number, and Winkler and Pasternak coefficients on the natural frequency of nanocomposite beam are investigated. Also, the effect of material length scale parameter on the dimensionless deflection of FG nanocomposite beam is studied.

  5. Free Vibration Analysis of DWCNTs Using CDM and Rayleigh-Schmidt Based on Nonlocal Euler-Bernoulli Beam Theory

    Directory of Open Access Journals (Sweden)

    Maria Anna De Rosa

    2014-01-01

    Full Text Available The free vibration response of double-walled carbon nanotubes (DWCNTs is investigated. The DWCNTs are modelled as two beams, interacting between them through the van der Waals forces, and the nonlocal Euler-Bernoulli beam theory is used. The governing equations of motion are derived using a variational approach and the free frequencies of vibrations are obtained employing two different approaches. In the first method, the two double-walled carbon nanotubes are discretized by means of the so-called “cell discretization method” (CDM in which each nanotube is reduced to a set of rigid bars linked together by elastic cells. The resulting discrete system takes into account nonlocal effects, constraint elasticities, and the van der Waals forces. The second proposed approach, belonging to the semianalytical methods, is an optimized version of the classical Rayleigh quotient, as proposed originally by Schmidt. The resulting conditions are solved numerically. Numerical examples end the paper, in which the two approaches give lower-upper bounds to the true values, and some comparisons with existing results are offered. Comparisons of the present numerical results with those from the open literature show an excellent agreement.

  6. Free vibration analysis of DWCNTs using CDM and Rayleigh-Schmidt based on Nonlocal Euler-Bernoulli beam theory.

    Science.gov (United States)

    De Rosa, Maria Anna; Lippiello, Maria

    2014-01-01

    The free vibration response of double-walled carbon nanotubes (DWCNTs) is investigated. The DWCNTs are modelled as two beams, interacting between them through the van der Waals forces, and the nonlocal Euler-Bernoulli beam theory is used. The governing equations of motion are derived using a variational approach and the free frequencies of vibrations are obtained employing two different approaches. In the first method, the two double-walled carbon nanotubes are discretized by means of the so-called "cell discretization method" (CDM) in which each nanotube is reduced to a set of rigid bars linked together by elastic cells. The resulting discrete system takes into account nonlocal effects, constraint elasticities, and the van der Waals forces. The second proposed approach, belonging to the semianalytical methods, is an optimized version of the classical Rayleigh quotient, as proposed originally by Schmidt. The resulting conditions are solved numerically. Numerical examples end the paper, in which the two approaches give lower-upper bounds to the true values, and some comparisons with existing results are offered. Comparisons of the present numerical results with those from the open literature show an excellent agreement.

  7. The Robin Hood method A novel numerical method for electrostatic problems based on a non-local charge transfer

    Science.gov (United States)

    Lazić, Predrag; Štefančić, Hrvoje; Abraham, Hrvoje

    2006-03-01

    We introduce a novel numerical method, named the Robin Hood method, of solving electrostatic problems. The approach of the method is closest to the boundary element methods, although significant conceptual differences exist with respect to this class of methods. The method achieves equipotentiality of conducting surfaces by iterative non-local charge transfer. For each of the conducting surfaces, non-local charge transfers are performed between surface elements, which differ the most from the targeted equipotentiality of the surface. The method is tested against analytical solutions and its wide range of application is demonstrated. The method has appealing technical characteristics. For the problem with N surface elements, the computational complexity of the method essentially scales with Nα, where α < 2, the required computer memory scales with N, while the error of the potential decreases exponentially with the number of iterations for many orders of magnitude of the error, without the presence of the Critical Slowing Down. The Robin Hood method could prove useful in other classical or even quantum problems. Some future development ideas for possible applications outside electrostatics are addressed.

  8. Non-Local Means Denoising

    Directory of Open Access Journals (Sweden)

    Antoni Buades

    2011-09-01

    Full Text Available We present in this paper a new denoising method called non-local means. The method is based on a simple principle: replacing the color of a pixel with an average of the colors of similar pixels. But the most similar pixels to a given pixel have no reason to be close at all. It is therefore licit to scan a vast portion of the image in search of all the pixels that really resemble the pixel one wants to denoise. The paper presents two implementations of the method and displays some results.

  9. Pattern formation in terms of semiclassically limited distribution on lower dimensional manifolds for the nonlocal Fisher-Kolmogorov-Petrovskii-Piskunov equation

    Science.gov (United States)

    Levchenko, E. A.; Shapovalov, A. V.; Trifonov, A. Yu

    2014-01-01

    We have investigated the pattern formation in systems described by the nonlocal Fisher-Kolmogorov-Petrovskii-Piskunov equation for the cases where the dimension of the pattern concentration domain is lower than that of the domain of independent variables. We have obtained a system of integro-differential equations which describe the dynamics of the concentration domain and the semiclassically limited density distribution for a pattern in the class of trajectory concentrated functions. Also, asymptotic large time solutions have been obtained that describe the semiclassically limited distribution for a quasi-steady-state pattern on the concentration manifold. The approach is illustrated by an example for which the analytical solution is in good agreement with the results of numerical calculations.

  10. Teaching Quantum Nonlocality

    Science.gov (United States)

    Hobson, Art

    2012-01-01

    Nonlocality arises from the unified "all or nothing" interactions of a spatially extended field quantum such as a photon or an electron. In the double-slit experiment with light, for example, each photon comes through both slits and arrives at the viewing screen as an extended but unified energy bundle or "field quantum." When the photon interacts…

  11. Teaching Quantum Nonlocality

    Science.gov (United States)

    Hobson, Art

    2012-01-01

    Nonlocality arises from the unified "all or nothing" interactions of a spatially extended field quantum such as a photon or an electron. In the double-slit experiment with light, for example, each photon comes through both slits and arrives at the viewing screen as an extended but unified energy bundle or "field quantum." When the photon interacts…

  12. Single photon and nonlocality

    Indian Academy of Sciences (India)

    Aurelien Drezet

    2007-03-01

    In a paper by Home and Agarwal [1], it is claimed that quantum nonlocality can be revealed in a simple interferometry experiment using only single particles. A critical analysis of the concept of hidden variable used by the authors of [1] shows that the reasoning is not correct.

  13. A Classical Framework for Nonlocality and Entanglement

    CERN Document Server

    Groessing, Gerhard; Pascasio, Johannes Mesa; Schwabl, Herbert

    2012-01-01

    Based on our model of quantum systems as emerging from the coupled dynamics between oscillating "bouncers" and the space-filling zero-point field, a sub-quantum account of nonlocal correlations is given. This is explicitly done for the example of the "double two-slit" variant of two-particle interferometry. However, it is also shown that the entanglement in two-particle interferometry is only a natural consequence of the fact that already a "single" two-slit experiment can be described on a sub-quantum level with the aid of "entangling currents" of a generally nonlocal nature.

  14. Compressive Sensing via Nonlocal Smoothed Rank Function.

    Science.gov (United States)

    Fan, Ya-Ru; Huang, Ting-Zhu; Liu, Jun; Zhao, Xi-Le

    2016-01-01

    Compressive sensing (CS) theory asserts that we can reconstruct signals and images with only a small number of samples or measurements. Recent works exploiting the nonlocal similarity have led to better results in various CS studies. To better exploit the nonlocal similarity, in this paper, we propose a non-convex smoothed rank function based model for CS image reconstruction. We also propose an efficient alternating minimization method to solve the proposed model, which reduces a difficult and coupled problem to two tractable subproblems. Experimental results have shown that the proposed method performs better than several existing state-of-the-art CS methods for image reconstruction.

  15. Geometric reduction of dynamical nonlocality in nanoscale quantum circuits

    Science.gov (United States)

    Strambini, E.; Makarenko, K. S.; Abulizi, G.; de Jong, M. P.; van der Wiel, W. G.

    2016-01-01

    Nonlocality is a key feature discriminating quantum and classical physics. Quantum-interference phenomena, such as Young’s double slit experiment, are one of the clearest manifestations of nonlocality, recently addressed as dynamical to specify its origin in the quantum equations of motion. It is well known that loss of dynamical nonlocality can occur due to (partial) collapse of the wavefunction due to a measurement, such as which-path detection. However, alternative mechanisms affecting dynamical nonlocality have hardly been considered, although of crucial importance in many schemes for quantum information processing. Here, we present a fundamentally different pathway of losing dynamical nonlocality, demonstrating that the detailed geometry of the detection scheme is crucial to preserve nonlocality. By means of a solid-state quantum-interference experiment we quantify this effect in a diffusive system. We show that interference is not only affected by decoherence, but also by a loss of dynamical nonlocality based on a local reduction of the number of quantum conduction channels of the interferometer. With our measurements and theoretical model we demonstrate that this mechanism is an intrinsic property of quantum dynamics. Understanding the geometrical constraints protecting nonlocality is crucial when designing quantum networks for quantum information processing.

  16. Geometric reduction of dynamical nonlocality in nanoscale quantum circuits

    Science.gov (United States)

    Strambini, E.; Makarenko, K. S.; Abulizi, G.; de Jong, M. P.; van der Wiel, W. G.

    2016-01-01

    Nonlocality is a key feature discriminating quantum and classical physics. Quantum-interference phenomena, such as Young’s double slit experiment, are one of the clearest manifestations of nonlocality, recently addressed as dynamical to specify its origin in the quantum equations of motion. It is well known that loss of dynamical nonlocality can occur due to (partial) collapse of the wavefunction due to a measurement, such as which-path detection. However, alternative mechanisms affecting dynamical nonlocality have hardly been considered, although of crucial importance in many schemes for quantum information processing. Here, we present a fundamentally different pathway of losing dynamical nonlocality, demonstrating that the detailed geometry of the detection scheme is crucial to preserve nonlocality. By means of a solid-state quantum-interference experiment we quantify this effect in a diffusive system. We show that interference is not only affected by decoherence, but also by a loss of dynamical nonlocality based on a local reduction of the number of quantum conduction channels of the interferometer. With our measurements and theoretical model we demonstrate that this mechanism is an intrinsic property of quantum dynamics. Understanding the geometrical constraints protecting nonlocality is crucial when designing quantum networks for quantum information processing. PMID:26732751

  17. Stochastic waves in a Brusselator model with nonlocal interaction.

    Science.gov (United States)

    Biancalani, Tommaso; Galla, Tobias; McKane, Alan J

    2011-08-01

    We show that intrinsic noise can induce spatiotemporal phenomena such as Turing patterns and traveling waves in a Brusselator model with nonlocal interaction terms. In order to predict and to characterize these stochastic waves we analyze the nonlocal model using a system-size expansion. The resulting theory is used to calculate the power spectra of the stochastic waves analytically and the outcome is tested successfully against simulations. We discuss the possibility that nonlocal models in other areas, such as epidemic spread or social dynamics, may contain similar stochastically induced patterns.

  18. Study the Surface Effect on the Buckling of Nanowires Embedded in Winkler–Pasternak Elastic Medium Based on a Nonlocal Theory

    Directory of Open Access Journals (Sweden)

    O. Rahmani

    2016-01-01

    Full Text Available Nano structures such as nanowires, nanobeams and nanoplates have been investigated widely for their innovative properties. In this paper the buckling of nanowires surrounded in a Winkler - Pasternak elastic medium has been examined based on the nonlocal Euler-Bernoully model with considering the surface effects. In the following a parametric study that explores the influence of numerous physical and geometrical parameters on the buckling of nanowires is presented.  It has been shown that by growing the ratio of surface area to bulk in nano-size structures, the effect of surface energy turn out to be important and should be taken into consideration. Moreover the results point out that surface elasticity and residual surface tension stimulus the buckling behavior of nanowires.

  19. Higher harmonic nonlocal polymerization driven diffusion model: generalized nonlinearities and nonlocal responses

    Science.gov (United States)

    Kelly, John V.; O'Brien, Jeff; O'Neill, Feidhlim T.; Gleeson, Michael R.; Sheridan, John T.

    2004-10-01

    Non-local and non-linear models of photopolymer materials, which include diffusion effects, have recently received much attention in the literature. The material response is non-local as it is assumed that monomers are polymerised to form polymer chains and that these chains grow away from a point of initiation. The non-locality is defined in terms of a spatial non-local material response function. The numerical method of solution typically involves retaining either two or four harmonics of the Fourier series of monomer concentration in the calculation. In this paper a general set of equations is derived which allows inclusion of higher number of harmonics for any response function. The numerical convergence for varying number of harmonics retained is investigated with special care being taken to note the effect of the; non-local material variance s, the power law degree k, and the rates of diffusion, D, and polymerisation F0. General non-linear material responses are also included.

  20. Entanglement without hidden nonlocality

    Science.gov (United States)

    Hirsch, Flavien; Túlio Quintino, Marco; Bowles, Joseph; Vértesi, Tamás; Brunner, Nicolas

    2016-11-01

    We consider Bell tests in which the distant observers can perform local filtering before testing a Bell inequality. Notably, in this setup, certain entangled states admitting a local hidden variable model in the standard Bell scenario can nevertheless violate a Bell inequality after filtering, displaying so-called hidden nonlocality. Here we ask whether all entangled states can violate a Bell inequality after well-chosen local filtering. We answer this question in the negative by showing that there exist entangled states without hidden nonlocality. Specifically, we prove that some two-qubit Werner states still admit a local hidden variable model after any possible local filtering on a single copy of the state.

  1. Nonlocal dynamics of dissipative phononic fluids

    Science.gov (United States)

    Nemati, Navid; Lee, Yoonkyung E.; Lafarge, Denis; Duclos, Aroune; Fang, Nicholas

    2017-06-01

    We describe the nonlocal effective properties of a two-dimensional dissipative phononic crystal made by periodic arrays of rigid and motionless cylinders embedded in a viscothermal fluid such as air. The description is based on a nonlocal theory of sound propagation in stationary random fluid/rigid media that was proposed by Lafarge and Nemati [Wave Motion 50, 1016 (2013), 10.1016/j.wavemoti.2013.04.007]. This scheme arises from a deep analogy with electromagnetism and a set of physics-based postulates including, particularly, the action-response procedures, whereby the effective density and bulk modulus are determined. Here, we revisit this approach, and clarify further its founding physical principles through presenting it in a unified formulation together with the two-scale asymptotic homogenization theory that is interpreted as the local limit. Strong evidence is provided to show that the validity of the principles and postulates within the nonlocal theory extends to high-frequency bands, well beyond the long-wavelength regime. In particular, we demonstrate that up to the third Brillouin zone including the Bragg scattering, the complex and dispersive phase velocity of the least-attenuated wave in the phononic crystal which is generated by our nonlocal scheme agrees exactly with that reproduced by a direct approach based on the Bloch theorem and multiple scattering method. In high frequencies, the effective wave and its associated parameters are analyzed by treating the phononic crystal as a random medium.

  2. Nonlocality in uniaxially polarizable media

    CERN Document Server

    Gorlach, Maxim A

    2015-01-01

    We reveal extraordinary electromagnetic properties for a general class of uniaxially polarizable media. Depending on parameters, such metamaterials may have wide range of nontrivial shapes of isofrequency contours including lemniscate, diamond and multiply connected curves with connectivity number reaching five. The possibility of the dispersion engineering paves a way to more flexible manipulation of electromagnetic waves. Employing first-principle considerations we prove that uniaxially polarizable media should be described in terms of the nonlocal permittivity tensor which by no means can be reduced to local permittivity and permeability even in the long-wavelength limit. We introduce an alternative set of local material parameters including quadrupole susceptibility capable to capture all of the second-order spatial dispersion effects.

  3. Experimental test of nonlocal causality.

    Science.gov (United States)

    Ringbauer, Martin; Giarmatzi, Christina; Chaves, Rafael; Costa, Fabio; White, Andrew G; Fedrizzi, Alessandro

    2016-08-01

    Explaining observations in terms of causes and effects is central to empirical science. However, correlations between entangled quantum particles seem to defy such an explanation. This implies that some of the fundamental assumptions of causal explanations have to give way. We consider a relaxation of one of these assumptions, Bell's local causality, by allowing outcome dependence: a direct causal influence between the outcomes of measurements of remote parties. We use interventional data from a photonic experiment to bound the strength of this causal influence in a two-party Bell scenario, and observational data from a Bell-type inequality test for the considered models. Our results demonstrate the incompatibility of quantum mechanics with a broad class of nonlocal causal models, which includes Bell-local models as a special case. Recovering a classical causal picture of quantum correlations thus requires an even more radical modification of our classical notion of cause and effect.

  4. Experimental test of nonlocal causality

    Science.gov (United States)

    Ringbauer, Martin; Giarmatzi, Christina; Chaves, Rafael; Costa, Fabio; White, Andrew G.; Fedrizzi, Alessandro

    2016-01-01

    Explaining observations in terms of causes and effects is central to empirical science. However, correlations between entangled quantum particles seem to defy such an explanation. This implies that some of the fundamental assumptions of causal explanations have to give way. We consider a relaxation of one of these assumptions, Bell’s local causality, by allowing outcome dependence: a direct causal influence between the outcomes of measurements of remote parties. We use interventional data from a photonic experiment to bound the strength of this causal influence in a two-party Bell scenario, and observational data from a Bell-type inequality test for the considered models. Our results demonstrate the incompatibility of quantum mechanics with a broad class of nonlocal causal models, which includes Bell-local models as a special case. Recovering a classical causal picture of quantum correlations thus requires an even more radical modification of our classical notion of cause and effect. PMID:27532045

  5. Degenerate-band-edge engineering inspired by nonlocal transformation optics

    Directory of Open Access Journals (Sweden)

    Moccia Massimo

    2016-01-01

    Full Text Available We address the engineering of degenerate-band-edge effects in nonlocal metamaterials. Our approach, inspired by nonlocal-transformation-optics concepts, is based on the approximation of analytically-derived nonlocal constitutive “blueprints”. We illustrate the synthesis procedure, and present and validate a possible implementation based on multilayered metamaterials featuring anisotropic constituents. We also elucidate the physical mechanisms underlying our approach and proposed configuration, and highlight the substantial differences with respect to other examples available in the topical literature.

  6. Degenerate-band-edge engineering inspired by nonlocal transformation optics

    Directory of Open Access Journals (Sweden)

    Moccia Massimo

    2016-01-01

    Full Text Available We address the engineering of degenerate-band-edge effects in nonlocal metamaterials. Our approach, inspired by nonlocal-transformation-optics concepts, is based on the approximation of analytically-derived nonlocal constitutive “blueprints”. We illustrate the synthesis procedure, and present and validate a possible implementation based on multilayered metamaterials featuring anisotropic constituents. We also elucidate the physical mechanisms underlying our approach and proposed configuration, and highlight the substantial differences with respect to other examples available in the topical literature.

  7. Nonlocal gravity: Conformally flat spacetimes

    CERN Document Server

    Bini, Donato

    2016-01-01

    The field equations of the recent nonlocal generalization of Einstein's theory of gravitation are presented in a form that is reminiscent of general relativity. The implications of the nonlocal field equations are studied in the case of conformally flat spacetimes. Even in this simple case, the field equations are intractable. Therefore, to gain insight into the nature of these equations, we investigate the structure of nonlocal gravity in two-dimensional spacetimes. While any smooth 2D spacetime is conformally flat and satisfies Einstein's field equations, only a subset containing either a Killing vector or a homothetic Killing vector can satisfy the field equations of nonlocal gravity.

  8. Analysis of slope stability of circular arc slip surface based on nonlocal elastic model%基于非局部弹性模型的圆弧滑裂面土坡稳定性分析

    Institute of Scientific and Technical Information of China (English)

    谢帮华; 扶名福; 李云生

    2015-01-01

    According to the proposed two kinds of nonlocal computing element,established two different nonlocal elastic model.Combining with the principle of minimum potential energy is studied based on the nonlocal elastic model of circular slip surface in slope stability,and the nonlocal material parameters are discussed and analyzed.Studied the influnce of material parameter on the stability safety factor of slope, from microscopic point analysis the action mechanism problems of the macro engineering,found the change of nonlocal material parameters which have the microscopic properties,the slope safety factor change obvi-ously.When discussing the influence of related parameters on the slope safety factor,the slope stability safety factor based on the nonlocal model is very sensitive on the internal friction angle.It is shown that u-sing the nonlocal elastic model analysis the slope stability is more reliable,this research can provide the ref-erence for engineering of soil management.%根据提出的两种非局部计算元件,建立两种非局部弹性模型。结合最小势能原理研究了基于非局部弹性模型下圆弧滑裂面土坡的稳定性,并对非局部材料参数进行了讨论与分析。研究了材料参数对土坡安全数的影响,从微观的角度分析了宏观工程的作用机理,发现带微观性质的非局部材料参数变化时,土坡安全系数变化很明显。当讨论土体相关参数对安全系数的影响时,基于非局部模型的土坡稳定安全系数对内摩擦角的变化比较敏感。结果表明,采用非局部弹性模型分析土坡的稳定性更可靠,该研究可为工程中土坡治理提供参考依据。

  9. A higher-order nonlocal elasticity and strain gradient theory and its applications in wave propagation

    Science.gov (United States)

    Lim, C. W.; Zhang, G.; Reddy, J. N.

    2015-05-01

    In recent years there have been many papers that considered the effects of material length scales in the study of mechanics of solids at micro- and/or nano-scales. There are a number of approaches and, among them, one set of papers deals with Eringen's differential nonlocal model and another deals with the strain gradient theories. The modified couple stress theory, which also accounts for a material length scale, is a form of a strain gradient theory. The large body of literature that has come into existence in the last several years has created significant confusion among researchers about the length scales that these various theories contain. The present paper has the objective of establishing the fact that the length scales present in nonlocal elasticity and strain gradient theory describe two entirely different physical characteristics of materials and structures at nanoscale. By using two principle kernel functions, the paper further presents a theory with application examples which relates the classical nonlocal elasticity and strain gradient theory and it results in a higher-order nonlocal strain gradient theory. In this theory, a higher-order nonlocal strain gradient elasticity system which considers higher-order stress gradients and strain gradient nonlocality is proposed. It is based on the nonlocal effects of the strain field and first gradient strain field. This theory intends to generalize the classical nonlocal elasticity theory by introducing a higher-order strain tensor with nonlocality into the stored energy function. The theory is distinctive because the classical nonlocal stress theory does not include nonlocality of higher-order stresses while the common strain gradient theory only considers local higher-order strain gradients without nonlocal effects in a global sense. By establishing the constitutive relation within the thermodynamic framework, the governing equations of equilibrium and all boundary conditions are derived via the variational

  10. Nonlocal Mumford-Shah regularizers for color image restoration.

    Science.gov (United States)

    Jung, Miyoun; Bresson, Xavier; Chan, Tony F; Vese, Luminita A

    2011-06-01

    We propose here a class of restoration algorithms for color images, based upon the Mumford-Shah (MS) model and nonlocal image information. The Ambrosio-Tortorelli and Shah elliptic approximations are defined to work in a small local neighborhood, which are sufficient to denoise smooth regions with sharp boundaries. However, texture is nonlocal in nature and requires semilocal/non-local information for efficient image denoising and restoration. Inspired from recent works (nonlocal means of Buades, Coll, Morel, and nonlocal total variation of Gilboa, Osher), we extend the local Ambrosio-Tortorelli and Shah approximations to MS functional (MS) to novel nonlocal formulations, for better restoration of fine structures and texture. We present several applications of the proposed nonlocal MS regularizers in image processing such as color image denoising, color image deblurring in the presence of Gaussian or impulse noise, color image inpainting, color image super-resolution, and color filter array demosaicing. In all the applications, the proposed nonlocal regularizers produce superior results over the local ones, especially in image inpainting with large missing regions. We also prove several characterizations of minimizers based upon dual norm formulations.

  11. Analytical theory of dark nonlocal solitons

    DEFF Research Database (Denmark)

    Kong, Qian; Wang, Qi; Bang, Ole;

    2010-01-01

    We investigate properties of dark solitons in nonlocal materials with an arbitrary degree of nonlocality. We employ the variational technique and describe dark solitons, for the first time to our knowledge, in the whole range of degree of nonlocality.......We investigate properties of dark solitons in nonlocal materials with an arbitrary degree of nonlocality. We employ the variational technique and describe dark solitons, for the first time to our knowledge, in the whole range of degree of nonlocality....

  12. Optical Beams in Nonlocal Nonlinear Media

    DEFF Research Database (Denmark)

    Królikowski, W.; Bang, Ole; Wyller, J.

    2003-01-01

    We discuss propagation of optical beams in nonlocal Kerr-like media with the nonlocality of general form. We study the effect of nonlocality on modulational instability of the plane wave fronts, collapse of finite beams and formation of spatial solitons.......We discuss propagation of optical beams in nonlocal Kerr-like media with the nonlocality of general form. We study the effect of nonlocality on modulational instability of the plane wave fronts, collapse of finite beams and formation of spatial solitons....

  13. On wave propagation characteristics in fluid saturated porous materials by a nonlocal Biot theory

    Science.gov (United States)

    Tong, Lihong; Yu, Yang; Hu, Wentao; Shi, Yufeng; Xu, Changjie

    2016-09-01

    A nonlocal Biot theory is developed by combing Biot theory and nonlocal elasticity theory for fluid saturated porous material. The nonlocal parameter is introduced as an independent variable for describing wave propagation characteristics in poroelastic material. A physical insight on nonlocal term demonstrates that the nonlocal term is a superposition of two effects, one is inertia force effect generated by fluctuation of porosity and the other is pore size effect inherited from nonlocal constitutive relation. Models for situations of excluding fluid nonlocal effect and including fluid nonlocal effect are proposed. Comparison with experiment confirms that model without fluid nonlocal effect is more reasonable for predicting wave characteristics in saturated porous materials. The negative dispersion is observed theoretically which agrees well with the published experimental data. Both wave velocities and quality factors as functions of frequency and nonlocal parameter are examined in practical cases. A few new physical phenomena such as backward propagation and disappearance of slow wave when exceeding critical frequency and disappearing shear wave in high frequency range, which were not predicted by Biot theory, are demonstrated.

  14. Dual-switching behavior of nonlocal interfaces

    Science.gov (United States)

    Sánchez-Curto, Julio; Chamorro-Posada, Pedro

    2017-05-01

    Nonlinear interfaces separating two diffusive Kerr-type media exhibit dual switching between total internal reflection and transmission. This property is found within a weakly nonlocal regime when both a nonparaxial treatment of the problem and a full two-dimensional model for carrier diffusion are assumed. The theoretical model is shown to predict an effective cubic-quintic nonlinearity with competing terms that produces such property. The validity of the analysis is contrasted with a full set of numerical simulations.

  15. Discrete model of dislocations in fractional nonlocal elasticity

    National Research Council Canada - National Science Library

    Tarasov, Vasily E

    2016-01-01

    Discrete models of dislocations in fractional nonlocal materials are suggested. The proposed models are based on fractional-order differences instead of finite differences of integer orders that are usually used...

  16. Causal Set theory, non-locality and phenomenology

    CERN Document Server

    Belenchia, Alessio

    2015-01-01

    This proceeding is based on a talk prepared for the XIV Marcel Grossmann meeting. We review some results on causal set inspired non-local theories as well as work in progress concerning their phenomenology.

  17. Strain analysis of nonlocal viscoelastic Kelvin bar in tension

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xue-chuan; LEI Yong-jun; ZHOU Jian-ping

    2008-01-01

    Based on viscoelastic Kelvin model and nonlocal relationship of strain and stress, a nonlocal constitutive relationship of viscoelasticity is obtained and the strain response of a bar in tension is studied. By transforming governing equation of the strain analysis into Volterra integration form and by choosing a symmetric exponential form of kernel function and adapting Neumann series, the closed-form solution of strain field of the bar is obtained. The creep process of the bar is presented. When time approaches infinite, the strain of bar is equal to the one of nonlocal elasticity.

  18. Nonlocal viscous transport and the effect on fluid stress.

    Science.gov (United States)

    Todd, B D; Hansen, J S

    2008-11-01

    We demonstrate that, in general, only for fluid flows in which the gradient of the strain rate is constant or zero can the classical Navier-Stokes equations with constant transport coefficients be considered exact. This is typical of two of the most common types of flow: Couette and Poiseuille. For more complicated flow fields in which the streaming velocity involves higher order nonlinear terms, the use of nonlocal constitutive equations gives an exact description of the flow. These constitutive equations involve nonlocal transport kernels. For momentum transport we demonstrate that nonlocality will be significant for any particular flow field if the even moments of the nonlocal viscosity kernel are non-negligible. This corresponds to the condition that the strain rate varies appreciably over the width of the kernel in real space. Such conditions are likely to be dominant for nanofluidic flows.

  19. Self-adjoint integral operator for bounded nonlocal transport

    Science.gov (United States)

    Maggs, J. E.; Morales, G. J.

    2016-11-01

    An integral operator is developed to describe nonlocal transport in a one-dimensional system bounded on both ends by material walls. The "jump" distributions associated with nonlocal transport are taken to be Lévy α -stable distributions, which become naturally truncated by the bounding walls. The truncation process results in the operator containing a self-consistent, convective inward transport term (pinch). The properties of the integral operator as functions of the Lévy distribution parameter set [α ,γ ] and the wall conductivity are presented. The integral operator continuously recovers the features of local transport when α =2 . The self-adjoint formulation allows for an accurate description of spatial variation in the Lévy parameters in the nonlocal system. Spatial variation in the Lévy parameters is shown to result in internally generated flows. Examples of cold-pulse propagation in nonlocal systems illustrate the capabilities of the methodology.

  20. Chinese Term Extraction Based on PAT Tree

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; FAN Xiao-zhong; XU Yun

    2006-01-01

    A new method of automatic Chinese term extraction is proposed based on Patricia (PAT) tree. Mutual information is calculated based on prefix searching in PAT tree of domain corpus to estimate the internal associative strength between Chinese characters in a string. It can improve the speed of term candidate extraction largely compared with methods based on domain corpus directly. Common collocation suffix, prefix bank are constructed and term part of speech (POS) composing rules are summarized to improve the precision of term extraction. Experiment results show that the F-measure is 74.97 %.

  1. Mixed noise removal by weighted encoding with sparse nonlocal regularization.

    Science.gov (United States)

    Jiang, Jielin; Zhang, Lei; Yang, Jian

    2014-06-01

    Mixed noise removal from natural images is a challenging task since the noise distribution usually does not have a parametric model and has a heavy tail. One typical kind of mixed noise is additive white Gaussian noise (AWGN) coupled with impulse noise (IN). Many mixed noise removal methods are detection based methods. They first detect the locations of IN pixels and then remove the mixed noise. However, such methods tend to generate many artifacts when the mixed noise is strong. In this paper, we propose a simple yet effective method, namely weighted encoding with sparse nonlocal regularization (WESNR), for mixed noise removal. In WESNR, there is not an explicit step of impulse pixel detection; instead, soft impulse pixel detection via weighted encoding is used to deal with IN and AWGN simultaneously. Meanwhile, the image sparsity prior and nonlocal self-similarity prior are integrated into a regularization term and introduced into the variational encoding framework. Experimental results show that the proposed WESNR method achieves leading mixed noise removal performance in terms of both quantitative measures and visual quality.

  2. Randomness and Non-Locality

    Science.gov (United States)

    Senno, Gabriel; Bendersky, Ariel; Figueira, Santiago

    2016-07-01

    The concepts of randomness and non-locality are intimately intertwined outcomes of randomly chosen measurements over entangled systems exhibiting non-local correlations are, if we preclude instantaneous influence between distant measurement choices and outcomes, random. In this paper, we survey some recent advances in the knowledge of the interplay between these two important notions from a quantum information science perspective.

  3. Observers in Spacetime and Nonlocality

    CERN Document Server

    Mashhoon, B

    2012-01-01

    Characteristics of observers in relativity theory are critically examined. For field measurements in Minkowski spacetime, the Bohr-Rosenfeld principle implies that the connection between actual (i.e., noninertial) and inertial observers must be nonlocal. Nonlocal electrodynamics of non-uniformly rotating observers is discussed and the consequences of this theory for the phenomenon of spin-rotation coupling are briefly explored.

  4. Quadratic solitons as nonlocal solitons

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov; Neshev, D.; Bang, Ole

    2003-01-01

    We show that quadratic solitons are equivalent to solitons of a nonlocal Kerr medium. This provides new physical insight into the properties of quadratic solitons, often believed to be equivalent to solitons of an effective saturable Kerr medium. The nonlocal analogy also allows for analytical...

  5. Nonlocal and quasilocal field theories

    Science.gov (United States)

    Tomboulis, E. T.

    2015-12-01

    We investigate nonlocal field theories, a subject that has attracted some renewed interest in connection with nonlocal gravity models. We study, in particular, scalar theories of interacting delocalized fields, the delocalization being specified by nonlocal integral kernels. We distinguish between strictly nonlocal and quasilocal (compact support) kernels and impose conditions on them to insure UV finiteness and unitarity of amplitudes. We study the classical initial value problem for the partial integro-differential equations of motion in detail. We give rigorous proofs of the existence but accompanying loss of uniqueness of solutions due to the presence of future, as well as past, "delays," a manifestation of acausality. In the quantum theory we derive a generalization of the Bogoliubov causality condition equation for amplitudes, which explicitly exhibits the corrections due to nonlocality. One finds that, remarkably, for quasilocal kernels all acausal effects are confined within the compact support regions. We briefly discuss the extension to other types of fields and prospects of such theories.

  6. Specific non-local interactions are not necessary for recovering native protein dynamics.

    Directory of Open Access Journals (Sweden)

    Bhaskar Dasgupta

    Full Text Available The elastic network model (ENM is a widely used method to study native protein dynamics by normal mode analysis (NMA. In ENM we need information about all pairwise distances, and the distance between contacting atoms is restrained to the native value. Therefore ENM requires O(N2 information to realize its dynamics for a protein consisting of N amino acid residues. To see if (or to what extent such a large amount of specific structural information is required to realize native protein dynamics, here we introduce a novel model based on only O(N restraints. This model, named the 'contact number diffusion' model (CND, includes specific distance restraints for only local (along the amino acid sequence atom pairs, and semi-specific non-local restraints imposed on each atom, rather than atom pairs. The semi-specific non-local restraints are defined in terms of the non-local contact numbers of atoms. The CND model exhibits the dynamic characteristics comparable to ENM and more correlated with the explicit-solvent molecular dynamics simulation than ENM. Moreover, unrealistic surface fluctuations often observed in ENM were suppressed in CND. On the other hand, in some ligand-bound structures CND showed larger fluctuations of buried protein atoms interacting with the ligand compared to ENM. In addition, fluctuations from CND and ENM show comparable correlations with the experimental B-factor. Although there are some indications of the importance of some specific non-local interactions, the semi-specific non-local interactions are mostly sufficient for reproducing the native protein dynamics.

  7. Specific non-local interactions are not necessary for recovering native protein dynamics.

    Science.gov (United States)

    Dasgupta, Bhaskar; Kasahara, Kota; Kamiya, Narutoshi; Nakamura, Haruki; Kinjo, Akira R

    2014-01-01

    The elastic network model (ENM) is a widely used method to study native protein dynamics by normal mode analysis (NMA). In ENM we need information about all pairwise distances, and the distance between contacting atoms is restrained to the native value. Therefore ENM requires O(N2) information to realize its dynamics for a protein consisting of N amino acid residues. To see if (or to what extent) such a large amount of specific structural information is required to realize native protein dynamics, here we introduce a novel model based on only O(N) restraints. This model, named the 'contact number diffusion' model (CND), includes specific distance restraints for only local (along the amino acid sequence) atom pairs, and semi-specific non-local restraints imposed on each atom, rather than atom pairs. The semi-specific non-local restraints are defined in terms of the non-local contact numbers of atoms. The CND model exhibits the dynamic characteristics comparable to ENM and more correlated with the explicit-solvent molecular dynamics simulation than ENM. Moreover, unrealistic surface fluctuations often observed in ENM were suppressed in CND. On the other hand, in some ligand-bound structures CND showed larger fluctuations of buried protein atoms interacting with the ligand compared to ENM. In addition, fluctuations from CND and ENM show comparable correlations with the experimental B-factor. Although there are some indications of the importance of some specific non-local interactions, the semi-specific non-local interactions are mostly sufficient for reproducing the native protein dynamics.

  8. Popescu-Rohrlich correlations imply efficient instantaneous nonlocal quantum computation

    Science.gov (United States)

    Broadbent, Anne

    2016-08-01

    In instantaneous nonlocal quantum computation, two parties cooperate in order to perform a quantum computation on their joint inputs, while being restricted to a single round of simultaneous communication. Previous results showed that instantaneous nonlocal quantum computation is possible, at the cost of an exponential amount of prior shared entanglement (in the size of the input). Here, we show that a linear amount of entanglement suffices, (in the size of the computation), as long as the parties share nonlocal correlations as given by the Popescu-Rohrlich box. This means that communication is not required for efficient instantaneous nonlocal quantum computation. Exploiting the well-known relation to position-based cryptography, our result also implies the impossibility of secure position-based cryptography against adversaries with nonsignaling correlations. Furthermore, our construction establishes a quantum analog of the classical communication complexity collapse under nonsignaling correlations.

  9. Nonlocal diffusion second order partial differential equations

    Science.gov (United States)

    Benedetti, I.; Loi, N. V.; Malaguti, L.; Taddei, V.

    2017-02-01

    The paper deals with a second order integro-partial differential equation in Rn with a nonlocal, degenerate diffusion term. Nonlocal conditions, such as the Cauchy multipoint and the weighted mean value problem, are investigated. The existence of periodic solutions is also studied. The dynamic is transformed into an abstract setting and the results come from an approximation solvability method. It combines a Schauder degree argument with an Hartman-type inequality and it involves a Scorza-Dragoni type result. The compact embedding of a suitable Sobolev space in the corresponding Lebesgue space is the unique amount of compactness which is needed in this discussion. The solutions are located in bounded sets and they are limits of functions with values in finitely dimensional spaces.

  10. Quantum Loops in Non-Local Gravity

    CERN Document Server

    Talaganis, Spyridon

    2015-01-01

    In this proceedings, I will consider quantum aspects of a non-local, infinite-derivative scalar field theory - a ${\\it toy \\, model}$ depiction of a covariant infinite-derivative, non-local extension of Einstein's general relativity which has previously been shown to be free from ghosts around the Minkowski background. The graviton propagator in this theory gets an exponential suppression making it ${\\it asymptotically \\, free}$, thus providing strong prospects of resolving various classical and quantum divergences. In particular, I will find that at $1$-loop, the $2$-point function is still divergent, but once this amplitude is renormalized by adding appropriate counter terms, the ultraviolet (UV) behavior of all other $1$-loop diagrams as well as the $2$-loop, $2$-point function remains well under control. I will go on to discuss how one may be able to generalize our computations and arguments to arbitrary loops.

  11. Non-linear non-local molecular electrodynamics with nano-optical fields.

    Science.gov (United States)

    Chernyak, Vladimir Y; Saurabh, Prasoon; Mukamel, Shaul

    2015-10-28

    The interaction of optical fields sculpted on the nano-scale with matter may not be described by the dipole approximation since the fields may vary appreciably across the molecular length scale. Rather than incrementally adding higher multipoles, it is advantageous and more physically transparent to describe the optical process using non-local response functions that intrinsically include all multipoles. We present a semi-classical approach for calculating non-local response functions based on the minimal coupling Hamiltonian. The first, second, and third order response functions are expressed in terms of correlation functions of the charge and the current densities. This approach is based on the gauge invariant current rather than the polarization, and on the vector potential rather than the electric and magnetic fields.

  12. The solutions of the strongly nonlocal spatial solitons with several types of nonlocal response functions

    Institute of Scientific and Technical Information of China (English)

    Ouyang Shi-Gen; Guo Qi; Lan Sheng; Wu Li-Jun

    2007-01-01

    The fundamental and second order strongly nonlocal solitons of the nonlocal nonlinear Schr(o)dinger equation for several types of nonlocal responses are calculated by Ritz's variational method.For a specific type of nonlocal response, the solutions of the strongly nonlocal solitons with the same beam width but difierent degrees of nonlocality are identical except for an amplitude factor.For a nonlocal case where the nonlocal response function decays in direct proportion to the ruth power of the distance near the source point,the power and the phase constant of the strongly nonlocal soliton are in inverse proportion to the(m+2)th power of its beam width.

  13. Nonlocal Problems for Fractional Differential Equations via Resolvent Operators

    Directory of Open Access Journals (Sweden)

    Zhenbin Fan

    2013-01-01

    Full Text Available We discuss the continuity of analytic resolvent in the uniform operator topology and then obtain the compactness of Cauchy operator by means of the analytic resolvent method. Based on this result, we derive the existence of mild solutions for nonlocal fractional differential equations when the nonlocal item is assumed to be Lipschitz continuous and neither Lipschitz nor compact, respectively. An example is also given to illustrate our theory.

  14. Application of nonlocal models to nano beams. Part II: Thickness length scale effect.

    Science.gov (United States)

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of the Eringen's nonlocal Euler-Bernoulli (EB) beam model. In literature, most work has taken the axial coordinate derivative in the Laplacian operator presented in nonlocal elasticity. This causes that the non-locality always makes the beam soften as compared to the local counterpart. In this paper, the thickness scale effect is solely considered to investigate if the nonlocal model can simulate stiffening effect. Taking the thickness derivative in the Laplacian operator leads to the presence of a surface stress state. The governing equation derived is compared to that of the EB model with the surface stress. The results obtained reveal that the nonlocality tends to decrease the bending moment stiffness whereas to increase the bending rigidity in the governing equation. This tendency also depends on the surface conditions.

  15. A Systems-Theoretical Generalization of Non-Local Correlations

    Science.gov (United States)

    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.

  16. Optimal measurements for nonlocal correlations

    Science.gov (United States)

    Schwarz, Sacha; Stefanov, André; Wolf, Stefan; Montina, Alberto

    2016-08-01

    A problem in quantum information theory is to find the experimental setup that maximizes the nonlocality of correlations with respect to some suitable measure such as the violation of Bell inequalities. There are however some complications with Bell inequalities. First and foremost it is unfeasible to determine the whole set of Bell inequalities already for a few measurements and thus unfeasible to find the experimental setup maximizing their violation. Second, the Bell violation suffers from an ambiguity stemming from the choice of the normalization of the Bell coefficients. An alternative measure of nonlocality with a direct information-theoretic interpretation is the minimal amount of classical communication required for simulating nonlocal correlations. In the case of many instances simulated in parallel, the minimal communication cost per instance is called nonlocal capacity, and its computation can be reduced to a convex-optimization problem. This quantity can be computed for a higher number of measurements and turns out to be useful for finding the optimal experimental setup. Focusing on the bipartite case, we present a simple method for maximizing the nonlocal capacity over a given configuration space and, in particular, over a set of possible measurements, yielding the corresponding optimal setup. Furthermore, we show that there is a functional relationship between Bell violation and nonlocal capacity. The method is illustrated with numerical tests and compared with the maximization of the violation of CGLMP-type Bell inequalities on the basis of entangled two-qubit as well as two-qutrit states. Remarkably, the anomaly of nonlocality displayed by qutrits turns out to be even stronger if the nonlocal capacity is employed as a measure of nonlocality.

  17. SEMANTIC TERM BASED INFORMATION RETRIEVAL USING ONTOLOGY

    OpenAIRE

    2014-01-01

    Information Searching and retrieval is a challenging task in the traditional keyword based textual information retrieval system. In the growing information age, adding huge data every day the searching problem also augmented. Keyword based retrieval system returns bulk of junk document irrelevant to query. To address the limitations, this paper proposed query terms along with semantic terms for information retrieval using multiple ontology reference. User query sometimes reflects multiple ...

  18. TICMR: Total Image Constrained Material Reconstruction via Nonlocal Total Variation Regularization for Spectral CT.

    Science.gov (United States)

    Liu, Jiulong; Ding, Huanjun; Molloi, Sabee; Zhang, Xiaoqun; Gao, Hao

    2016-12-01

    This work develops a material reconstruction method for spectral CT, namely Total Image Constrained Material Reconstruction (TICMR), to maximize the utility of projection data in terms of both spectral information and high signal-to-noise ratio (SNR). This is motivated by the following fact: when viewed as a spectrally-integrated measurement, the projection data can be used to reconstruct a total image without spectral information, which however has a relatively high SNR; when viewed as a spectrally-resolved measurement, the projection data can be utilized to reconstruct the material composition, which however has a relatively low SNR. The material reconstruction synergizes material decomposition and image reconstruction, i.e., the direct reconstruction of material compositions instead of a two-step procedure that first reconstructs images and then decomposes images. For material reconstruction with high SNR, we propose TICMR with nonlocal total variation (NLTV) regularization. That is, first we reconstruct a total image using spectrally-integrated measurement without spectral binning, and build the NLTV weights from this image that characterize nonlocal image features; then the NLTV weights are incorporated into a NLTV-based iterative material reconstruction scheme using spectrally-binned projection data, so that these weights serve as a high-SNR reference to regularize material reconstruction. Note that the nonlocal property of NLTV is essential for material reconstruction, since material compositions may have significant local intensity variations although their structural information is often similar. In terms of solution algorithm, TICMR is formulated as an iterative reconstruction method with the NLTV regularization, in which the nonlocal divergence is utilized based on the adjoint relationship. The alternating direction method of multipliers is developed to solve this sparsity optimization problem. The proposed TICMR method was validated using both simulated

  19. Towards LHC physics with nonlocal Standard Model

    OpenAIRE

    Tirthabir Biswas; Nobuchika Okada

    2015-01-01

    We take a few steps towards constructing a string-inspired nonlocal extension of the Standard Model. We start by illustrating how quantum loop calculations can be performed in nonlocal scalar field theory. In particular, we show the potential to address the hierarchy problem in the nonlocal framework. Next, we construct a nonlocal abelian gauge model and derive modifications of the gauge interaction vertex and field propagators. We apply the modifications to a toy version of the nonlocal Stan...

  20. Popper's experiment, Copenhagen Interpretation and Nonlocality

    CERN Document Server

    Qureshi, T

    2003-01-01

    A thought experiment, proposed by Karl Popper, which has been experimentally realized recently, is critically examined. A basic flaw in Popper's argument which has also been prevailing in subsequent debates, is pointed out. It is shown that Popper's experiment can be understood easily within the Copenhagen interpretation of quantum mechanics. An alternate experiment, based on discrete variables, is proposed, which constitutes Popper's test in a clearer way. It refutes the argument of absence of nonlocality in quantum mechanics.

  1. Shock Waves Propagation in Scope of the Nonlocal Theory of Dynamical Plasticity

    Science.gov (United States)

    Khantuleva, Tatyana A.

    2004-07-01

    From the point of view of the modern statistical mechanics the problems on shock compression of solids require a reformulation in terms of highly nonequilibrium effects arising inside the wave front. The self-organization during the multiscale and multistage momentum and energy exchange are originated by the correlation function. The theory of dynamic plasticity has been developed by the author on the base of the self-consistent nonlocal hydrodynamic approach had been applied to the shock wave propagation in solids. Nonlocal balance equations describe both the reversible wave type transport at the initial stage and the diffusive (dissipative) one in the end. The involved inverse influence of the mesoeffects on the wave propagation makes the formulation of problems self-consistent and involves a concept of the cybernetic control close-loop.

  2. A non-local non-autonomous diffusion problem: linear and sublinear cases

    Science.gov (United States)

    Figueiredo-Sousa, Tarcyana S.; Morales-Rodrigo, Cristian; Suárez, Antonio

    2017-10-01

    In this work we investigate an elliptic problem with a non-local non-autonomous diffusion coefficient. Mainly, we use bifurcation arguments to obtain existence of positive solutions. The structure of the set of positive solutions depends strongly on the balance between the non-local and the reaction terms.

  3. Dynamic analysis of isotropic nanoplates subjected to moving load using state-space method based on nonlocal second order plate theory

    Energy Technology Data Exchange (ETDEWEB)

    Nami, Mohammad Rahim [Shiraz University, Shiraz, Iran (Iran, Islamic Republic of); Janghorban, Maziar [Islamic Azad University, Marvdash (Iran, Islamic Republic of)

    2015-06-15

    In this work, dynamic analysis of rectangular nanoplates subjected to moving load is presented. In order to derive the governing equations of motion, second order plate theory is used. To capture the small scale effects, the nonlocal elasticity theory is adopted. It is assumed that the nanoplate is subjected to a moving concentrated load with the constant velocity V in the x direction. To solve the governing equations, state-space method is used to find the deflections of rectangular nanoplate under moving load. The results obtained here reveal that the nonlocality has significant effect on the deflection of rectangular nanoplate subjected to moving load.

  4. Solutions of Nonlocal -Laplacian Equations

    Directory of Open Access Journals (Sweden)

    Mustafa Avci

    2013-01-01

    Full Text Available In view of variational approach we discuss a nonlocal problem, that is, a Kirchhoff-type equation involving -Laplace operator. Establishing some suitable conditions, we prove the existence and multiplicity of solutions.

  5. Classical and Quantum Nonlocal Supergravity

    CERN Document Server

    Giaccari, Stefano

    2016-01-01

    We derive the N=1 supersymmetric extension for a class of weakly nonlocal four dimensional gravitational theories.The construction is explicitly done in the superspace and the tree-level perturbative unitarity is explicitly proved both in the superfield formalism and in field components. For the minimal nonlocal supergravity the spectrum is the same as in the local theory and in particular it is ghost-free. The supersymmetric extension of the super-renormalizable Starobinsky theory and of two alternative massive nonlocal supergravities are found as straightforward applications of the formalism. Power-counting arguments ensure super-renormalizability with milder requirement for the asymptotic behavior of form factors than in ordinary nonlocal gravity. The most noteworthy result, common to ordinary supergravity, is the absence of quantum corrections to the cosmological constant in any regularization procedure. We cannot exclude the usual one-loop quadratic divergences. However, local vertices in the superfields...

  6. An Adaptive Iterated Nonlocal Interferometry Filtering Method

    Directory of Open Access Journals (Sweden)

    Lin Xue

    2014-04-01

    Full Text Available Interferometry filtering is one of the key steps in obtain high-precision Digital Elevation Model (DEM and Digital Orthophoto Map (DOM. In the case of low-correlation or complicated topography, traditional phase filtering methods fail in balancing noise elimination and phase preservation, which leads to inaccurate interferometric phase. This paper proposed an adaptive iterated nonlocal interferometry filtering method to deal with the problem. Based on the thought of nonlocal filtering, the proposed method filters the image with utilization of the image redundancy information. The smoothing parameter of the method is adaptive to the interferometry, and automatic iteration, in which the window size is adjusted, is applied to improve the filtering precision. Validity of the proposed method is verified by simulated and real data. Comparison with existed methods is given at the same time.

  7. Non-local geometry inside Lifshitz horizon

    Science.gov (United States)

    Hu, Qi; Lee, Sung-Sik

    2017-07-01

    Based on the quantum renormalization group, we derive the bulk geometry that emerges in the holographic dual of the fermionic U( N ) vector model at a nonzero charge density. The obstruction that prohibits the metallic state from being smoothly deformable to the direct product state under the renormalization group flow gives rise to a horizon at a finite radial coordinate in the bulk. The region outside the horizon is described by the Lifshitz geometry with a higher-spin hair determined by microscopic details of the boundary theory. On the other hand, the interior of the horizon is not described by any Riemannian manifold, as it exhibits an algebraic non-locality. The non-local structure inside the horizon carries the information on the shape of the filled Fermi sea.

  8. Circular-Vector Based Non-Local SAR Image Denoising Algorithm%环形向量非局部SAR图像降噪算法

    Institute of Scientific and Technical Information of China (English)

    蔡雨辰; 赵保军; 唐林波

    2012-01-01

    提出一种基于环形向量的非局部SAR图像降噪算法.根据像素点的主方向提取环形向量,计算环形向量各自的特征向量.基于特征向量计算相似度权重,该方法的时间复杂度明显优于NL-Means的矩形模板匹配算法,且相似点匹配具有旋转不变性.通过仿真实验验证了该算法的计算速度和旋转不变性能,匹配效果明显优于NL-Means,降噪结果的峰值信噪比和结构相似度优于BM3D、BLS-GSM等主流降噪算法.%A circular-vector based non-local SAR image denoising algorithm was proposed. Circular vectors were abstracted according to the main direction of the central pixel. Feature vectors were then calculated and the weights of similarity were obtained based on these feature vectors. The execution time and quality of rotation invariance were tested. The results show that the time complexity is significantly lower than the patch-based similarity matching algorithm in NL-Means, and the rotation invariance is also maintained. Experiments have verified that the proposed algorithm shows better similarity matching results comparing to NL-Means and competitive denoising results on PSNR and SSIM against currently state-of-the-art denoising algorithms, such as BM3D, BLS-GSM.

  9. A Morphing framework to couple non-local and local anisotropic continua

    KAUST Repository

    Azdoud, Yan

    2013-05-01

    In this article, we develop a method to couple anisotropic local continua with anisotropic non-local continua with central long-range forces. First, we describe anisotropic non-local models based on spherical harmonic descriptions. We then derive compatible classic continuum models. Finally, we apply the morphing method to these anisotropic non-local models and present three-dimensional numerical examples to validate the efficiency of the technique. © 2013 Elsevier Ltd. All rights reserved.

  10. Study of Nonlocal Optical Potential

    Institute of Scientific and Technical Information of China (English)

    TIAN; Yuan

    2013-01-01

    It is generally known that nuclear optical potentials are theoretically expected to be non-local.The non-locality arises from the exchange of particles between the projectile and target and from coupling tonon-elastic channels.This non-locality was first introduced by Frahn and Lemmer,and developed further by Perey and Buck(PB).The kernel is of the form

  11. Post-Newtonian parameter γ in generalized non-local gravity

    Science.gov (United States)

    Zhang, Xue; Wu, YaBo; Yang, WeiQiang; Zhang, ChengYuan; Chen, BoHai; Zhang, Nan

    2017-10-01

    We investigate the post-Newtonian parameter γ and derive its formalism in generalized non-local (GNL) gravity, which is the modified theory of general relativity (GR) obtained by adding a term m 2 n-2 R☐-n R to the Einstein-Hilbert action. Concretely, based on parametrizing the generalized non-local action in which gravity is described by a series of dynamical scalar fields ϕ i in addition to the metric tensor g μν, the post-Newtonian limit is computed, and the effective gravitational constant as well as the post-Newtonian parameters are directly obtained from the generalized non-local gravity. Moreover, by discussing the values of the parametrized post-Newtonian parameters γ, we can compare our expressions and results with those in Hohmann and Järv et al. (2016), as well as current observational constraints on the values of γ in Will (2006). Hence, we draw restrictions on the nonminimal coupling terms F̅ around their background values.

  12. Coupling of nonlocal and local continuum models by the Arlequinapproach

    KAUST Repository

    Han, Fei

    2011-08-09

    The objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically-based model of nonlocal elasticity, which involves both contact and long-range forces, is used for the \\'fine scale\\' description in which nonlocal interactions are considered to have non-negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the \\'gluing area\\' in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two-dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. © 2011 John Wiley & Sons, Ltd.

  13. SEMANTIC TERM BASED INFORMATION RETRIEVAL USING ONTOLOGY

    Directory of Open Access Journals (Sweden)

    J. Mannar Mannan

    2014-01-01

    Full Text Available Information Searching and retrieval is a challenging task in the traditional keyword based textual information retrieval system. In the growing information age, adding huge data every day the searching problem also augmented. Keyword based retrieval system returns bulk of junk document irrelevant to query. To address the limitations, this paper proposed query terms along with semantic terms for information retrieval using multiple ontology reference. User query sometimes reflects multiple domain of interest that persist us to collect semantically related ontologies. If no related ontology exists then WordNet ontology used to retrieve semantic terms related to query term. In this approach, classes on the ontology derived as semantic related text keywords, these keywords considered for rank the documents.

  14. Analysis of a micro piezoelectric vibration energy harvester by nonlocal elasticity theory

    Directory of Open Access Journals (Sweden)

    Hao Chen

    2016-04-01

    Full Text Available A theoretical model of a micro piezoelectric energy harvester is proposed based on the nonlocal elasticity theory, which is operated in the flexural mode for scavenging ambient vibration energy. A nonlocal scale is defined as the product of internal characteristic length and a constant related to the material. The dependences of performance of the harvester upon the nonlocal scale and the scale ratio of the nonlocal scale to the external characteristic parameter are investigated in detail. Numerical results show that output power of the harvester decreases, and resonance frequency reduces gradually at first then increases rapidly when nonlocal scale increases. The results of nonlocal elasticity theory are compared with that of classic beam theory. All the results are helpful for material and structure design of the micro piezoelectric energy harvester.

  15. Numerical investigation of non-local electron transport in laser-produced plasmas

    Institute of Scientific and Technical Information of China (English)

    Dong Ya-Lin; Zhao Bin; Zheng Jian

    2007-01-01

    Non-local electron transport in laser-produced plasmas under inertial confinement fusion (ICF) conditions is studied based on Fokker-Planck (FP) and hydrodynamic simulations. A comparison between the classical Spitzer-H(a)rm (SH)transport model and non-local transport models has been made. The result shows that among those non-local models the Epperlein and Short (ES) model of heat flux is in reasonable agreement with the FP simulation in overdense region.However, the non-local models are invalid in the hot underdense plasmas. Hydrodynamic simulation is performed with the flux limiting model and the non-local model, separately. The simulation results show that in the underdense region of the laser-produced plasmas the temperature given by the flux limiting model is significantly higher than that given with the non-local model.

  16. Resonance measurement of nonlocal spin torque in a three-terminal magnetic device.

    Science.gov (United States)

    Xue, Lin; Wang, Chen; Cui, Yong-Tao; Liu, Luqiao; Swander, A; Sun, J Z; Buhrman, R A; Ralph, D C

    2012-04-06

    A pure spin current generated within a nonlocal spin valve can exert a spin-transfer torque on a nanomagnet. This nonlocal torque enables new design schemes for magnetic memory devices that do not require the application of large voltages across tunnel barriers that can suffer electrical breakdown. Here we report a quantitative measurement of this nonlocal spin torque using spin-torque-driven ferromagnetic resonance. Our measurement agrees well with the prediction of an effective circuit model for spin transport. Based on this model, we suggest strategies for optimizing the strength of nonlocal torque.

  17. Dynamical nonlocality of the entangled coherent state in the phase damping model

    Institute of Scientific and Technical Information of China (English)

    Lu Huai-Xin; Li Ying-De

    2009-01-01

    This paper studies the dynamics of nonlocality for a bosonic entangled coherent state in a phase damping model. The density operator of the system is solved by using a superoperator method. The dynamics of nonlocality for the bosonic entangled coherent state is uncovered by the Bell operator based on the pseudospin operator of a light field. The dynamics of the nonlocality for this state has also been studied by other Bell operators. The result of the numerical calculations of the Bell function shows that the quantum nonlocality heavily depends on the chosen Bell operator.

  18. Goos-Hänchen shifts of Helmholtz solitons at nonlocal nonlinear interfaces

    Science.gov (United States)

    Zhiwei, Shi; Jing, Xue; Jilong, Chen; Yang, Li; Huagang, Li

    2015-02-01

    We address the nonlinear Goos-Hänchen shift of Helmholtz solitons at a nonlocal nonlinear interface between a Kerr medium and a nonlocal nonlinear medium. Based on the framework of the Helmholtz theory, we have demonstrated that the Goos-Hänchen shift depends on the angle of the incidence, the linear and nonlinear refractive index mismatch at the interface, the nonparaxial parameter and the degree of nonlocality. Interestingly, internal and external refraction can be introduced when the nonlinear refractive index mismatch is greater than a threshold value. The total reflection will occur when the degree of nonlocality exceeds a value.

  19. Nonlocal optical response in metallic nanostructures.

    Science.gov (United States)

    Raza, Søren; Bozhevolnyi, Sergey I; Wubs, Martijn; Asger Mortensen, N

    2015-05-13

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response.

  20. Nonlocal optical response in metallic nanostructures

    DEFF Research Database (Denmark)

    Raza, Søren; Bozhevolnyi, Sergey I.; Wubs, Martijn

    2015-01-01

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response...... on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response....

  1. Nonlocal electrical diffusion equation

    Science.gov (United States)

    Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; Olivares-Peregrino, V. H.; Benavides-Cruz, M.; Calderón-Ramón, C.

    2016-07-01

    In this paper, we present an analysis and modeling of the electrical diffusion equation using the fractional calculus approach. This alternative representation for the current density is expressed in terms of the Caputo derivatives, the order for the space domain is 0numerical methods based on Fourier variable separation. The case with spatial fractional derivatives leads to Levy flight type phenomena, while the time fractional equation is related to sub- or super diffusion. We show that the mathematical concept of fractional derivatives can be useful to understand the behavior of semiconductors, the design of solar panels, electrochemical phenomena and the description of anomalous complex processes.

  2. Nonlocal Measurements via Quantum Erasure.

    Science.gov (United States)

    Brodutch, Aharon; Cohen, Eliahu

    2016-02-19

    Nonlocal observables play an important role in quantum theory, from Bell inequalities and various postselection paradoxes to quantum error correction codes. Instantaneous measurement of these observables is known to be a difficult problem, especially when the measurements are projective. The standard von Neumann Hamiltonian used to model projective measurements cannot be implemented directly in a nonlocal scenario and can, in some cases, violate causality. We present a scheme for effectively generating the von Neumann Hamiltonian for nonlocal observables without the need to communicate and adapt. The protocol can be used to perform weak and strong (projective) measurements, as well as measurements at any intermediate strength. It can also be used in practical situations beyond nonlocal measurements. We show how the protocol can be used to probe a version of Hardy's paradox with both weak and strong measurements. The outcomes of these measurements provide a nonintuitive picture of the pre- and postselected system. Our results shed new light on the interplay between quantum measurements, uncertainty, nonlocality, causality, and determinism.

  3. Near field radiative heat transfer between two nonlocal dielectrics

    CERN Document Server

    Singer, F; Joulain, Karl

    2015-01-01

    We explore in the present work the near-field radiative heat transfer between two semi-infinite parallel nonlocal dielectric planes by means of fluctuational electrodynamics. We use atheory for the nonlocal dielectric permittivityfunction proposed byHalevi and Fuchs. This theory has the advantage to includedifferent models performed in the literature. According to this theory, the nonlocal dielectric function is described by a Lorenz-Drude like single oscillator model, in which the spatial dispersion effects are represented by an additional term depending on the square of the total wavevector k. The theory takes into account the scattering of the electromagneticexcitation at the surface of the dielectric material, which leads to the need of additional boundary conditions in order to solve Maxwell's equations and treat the electromagnetic transmission problem. The additional boundary conditions appear as additional surface scattering parameters in the expressions of the surface impedances. It is shown that the...

  4. Generalized conservation laws in non-local field theories

    Science.gov (United States)

    Kegeles, Alexander; Oriti, Daniele

    2016-04-01

    We propose a geometrical treatment of symmetries in non-local field theories, where the non-locality is due to a lack of identification of field arguments in the action. We show that the existence of a symmetry of the action leads to a generalized conservation law, in which the usual conserved current acquires an additional non-local correction term, obtaining a generalization of the standard Noether theorem. We illustrate the general formalism by discussing the specific physical example of complex scalar field theory of the type describing the hydrodynamic approximation of Bose-Einstein condensates. We expect our analysis and results to be of particular interest for the group field theory formulation of quantum gravity.

  5. Generalised conservation laws in non-local field theories

    CERN Document Server

    Kegeles, Alexander

    2015-01-01

    We propose a geometrical treatment of symmetries in non-local field theories, where the non-locality is due to a lack of identification of field arguments in the action. We show that the existence of a symmetry of the action leads to a generalised conservation law, in which the usual conserved current acquires an additional non-local correction term, obtaining a generalisation of the standard Noether theorem. We illustrate the general formalism by discussing the specific physical example of complex scalar field theory of the type describing the hydrodynamic approximation of Bose-Einstein condensates. We expect our analysis and results to be of particular interest for the group field theory formulation of quantum gravity.

  6. Nonlocal quartic interactions and universality classes in perovskite manganites.

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K

    2015-07-01

    A modified Ginzburg-Landau model with a screened nonlocal interaction in the quartic term is treated via Wilson's renormalization-group scheme at one-loop order to explore the critical behavior of the paramagnetic-to-ferromagnetic phase transition in perovskite manganites. We find the Fisher exponent η to be O(ε) and the correlation exponent to be ν=1/2+O(ε) through epsilon expansion in the parameter ε=d(c)-d, where d is the space dimension, d(c)=4+2σ is the upper critical dimension, and σ is a parameter coming from the nonlocal interaction in the model Hamiltonian. The ensuing critical exponents in three dimensions for different values of σ compare well with various existing experimental estimates for perovskite manganites with various doping levels. This suggests that the nonlocal model Hamiltonian contains a wide variety of such universality classes.

  7. Effect of nonlocal dispersion on self-interacting excitations

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Rasmussen, Kim; Gaididei, Yu.B.

    1996-01-01

    The dynamics of self-interacting quasiparticles in 1Dsystems with long-range dispersive interactions isexpressed in terms of a nonlocal nonlinear Schrödingerequation. Two branches of stationary solutions are found.The new branch which contains a cusp soliton is shown to beunstable and blowup is o...

  8. Non-local common cause explanations for EPR

    CERN Document Server

    Egg, Matthias

    2013-01-01

    The paper argues that a causal explanation of the correlated outcomes of EPR-type experiments is desirable and possible. It shows how Bohmian mechanics and the GRW mass density theory offer such an explanation in terms of a non-local common cause.

  9. Nonlocal description of X waves in quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Larsen, Peter Ulrik Vingaard; Sørensen, Mads Peter; Bang, Ole

    2006-01-01

    We study localized light bullets and X-waves in quadratic media and show how the notion of nonlocality can provide an alternative simple physical picture of both types of multi-dimensional nonlinear waves. For X-waves we show that a local cascading limit in terms of a nonlinear Schrodinger equation...

  10. Effect of nonlocal dispersion on self-interacting excitations

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Rasmussen, Kim; Gaididei, Yu.B.

    1996-01-01

    The dynamics of self-interacting quasiparticles in 1Dsystems with long-range dispersive interactions isexpressed in terms of a nonlocal nonlinear Schrödingerequation. Two branches of stationary solutions are found.The new branch which contains a cusp soliton is shown to beunstable and blowup...

  11. A Derivation of the Nonlocal Volume-Averaged Equations for Two-Phase Flow Transport

    Directory of Open Access Journals (Sweden)

    Gilberto Espinosa-Paredes

    2012-01-01

    Full Text Available In this paper a detailed derivation of the general transport equations for two-phase systems using a method based on nonlocal volume averaging is presented. The local volume averaging equations are commonly applied in nuclear reactor system for optimal design and safe operation. Unfortunately, these equations are limited to length-scale restriction and according with the theory of the averaging volume method, these fail in transition of the flow patterns and boundaries between two-phase flow and solid, which produce rapid changes in the physical properties and void fraction. The non-local volume averaging equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection diffusion and transport properties for two-phase flow; for instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail.

  12. Non-Local Analysis of Forming Limits of Ductile Material Considering Void Growth

    Institute of Scientific and Technical Information of China (English)

    Youngsuk Kim

    2003-01-01

    The current study performed a finite element analysis of the strain localization behavior of a voided ductile material using a non-local plasticity formulation in which the yield strength depends on both an equivalent plastic strain measurement (hardening parameter) and Laplacian equivalent. The introduction of gradient terms to the yield function was found to play an important role in simulating the strain localization behavior of the voided ductile material. The effect of the mesh size and characteristic length on the strain localization were also investigated. An FEM simulation based on the proposed non-local plasticity revealed that the load-strain curves of the voided ductile material subjected to plane strain tension converged to one curve, regardless of the mesh size. In addition, the results using non-local plasticity also exhibited that the dependence of the deformation behavior of the material on the mesh size was much less sensitive than that with classical local plasticity and could be successfully eliminated through the introduction of a large value for the characteristic length.

  13. Nonlocal optical response in metallic nanostructures

    OpenAIRE

    Raza, Søren; Bozhevolnyi, Sergey I.; Wubs, Martijn; Mortensen, N. Asger

    2014-01-01

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future w...

  14. Nonlocal higher order evolution equations

    KAUST Repository

    Rossi, Julio D.

    2010-06-01

    In this article, we study the asymptotic behaviour of solutions to the nonlocal operator ut(x, t)1/4(-1)n-1 (J*Id -1)n (u(x, t)), x ∈ ℝN, which is the nonlocal analogous to the higher order local evolution equation vt(-1)n-1(Δ)nv. We prove that the solutions of the nonlocal problem converge to the solution of the higher order problem with the right-hand side given by powers of the Laplacian when the kernel J is rescaled in an appropriate way. Moreover, we prove that solutions to both equations have the same asymptotic decay rate as t goes to infinity. © 2010 Taylor & Francis.

  15. Nonlocal Total Variation Subpixel Mapping for Hyperspectral Remote Sensing Imagery

    Directory of Open Access Journals (Sweden)

    Ruyi Feng

    2016-03-01

    Full Text Available Subpixel mapping is a method of enhancing the spatial resolution of images, which involves dividing a mixed pixel into subpixels and assigning each subpixel to a definite land-cover class. Traditionally, subpixel mapping is based on the assumption of spatial dependence, and the spatial correlation information among pixels and subpixels is considered in the prediction of the spatial locations of land-cover classes within the mixed pixels. In this paper, a novel subpixel mapping method for hyperspectral remote sensing imagery based on a nonlocal method, namely nonlocal total variation subpixel mapping (NLTVSM, is proposed to use the nonlocal self-similarity prior to improve the performance of the subpixel mapping task. Differing from the existing spatial regularization subpixel mapping technique, in NLTVSM, the nonlocal total variation is used as a spatial regularizer to exploit the similar patterns and structures in the image. In this way, the proposed method can obtain an optimal subpixel mapping result and accuracy by considering the nonlocal spatial information. Compared with the classical and state-of-the-art subpixel mapping approaches, the experimental results using a simulated hyperspectral image, two synthetic hyperspectral remote sensing images, and a real hyperspectral image confirm that the proposed algorithm can obtain better results in both visual and quantitative evaluations.

  16. Decomposing cerebral blood flow MRI into functional and structural components: a non-local approach based on prediction.

    Science.gov (United States)

    Kandel, Benjamin M; Wang, Danny J J; Detre, John A; Gee, James C; Avants, Brian B

    2015-01-15

    We present RIPMMARC (Rotation Invariant Patch-based Multi-Modality Analysis aRChitecture), a flexible and widely applicable method for extracting information unique to a given modality from a multi-modal data set. We use RIPMMARC to improve the interpretation of arterial spin labeling (ASL) perfusion images by removing the component of perfusion that is predicted by the underlying anatomy. Using patch-based, rotation invariant descriptors derived from the anatomical image, we learn a predictive relationship between local neuroanatomical structure and the corresponding perfusion image. This relation allows us to produce an image of perfusion that would be predicted given only the underlying anatomy and a residual image that represents perfusion information that cannot be predicted by anatomical features. Our learned structural features are significantly better at predicting brain perfusion than tissue probability maps, which are the input to standard partial volume correction techniques. Studies in test-retest data show that both the anatomically predicted and residual perfusion signals are highly replicable for a given subject. In a pediatric population, both the raw perfusion and structurally predicted images are tightly linked to age throughout adolescence throughout the brain. Interestingly, the residual perfusion also shows a strong correlation with age in selected regions including the hippocampi (corr = 0.38, p-value <10(-6)), precuneus (corr = -0.44, p < 10(-5)), and combined default mode network regions (corr = -0.45, p < 10(-8)) that is independent of global anatomy-perfusion trends. This finding suggests that there is a regionally heterogeneous pattern of functional specialization that is distinct from that of cortical structural development.

  17. Anderson Localization in Nonlocal Nonlinear Media

    CERN Document Server

    Folli, Viola; 10.1364/OL.37.000332

    2012-01-01

    The effect of focusing and defocusing nonlinearities on Anderson localization in highly nonlocal media is theoretically and numerically investigated. A perturbative approach is developed to solve the nonlocal nonlinear Schroedinger equation in the presence of a random potential, showing that nonlocality stabilizes Anderson states.

  18. Solitons in nonlocal nonlinear media: Exact solutions

    DEFF Research Database (Denmark)

    Krolikowski, Wieslaw; Bang, Ole

    2001-01-01

    We investigate the propagation of one-dimensional bright and dark spatial solitons in a nonlocal Kerr-like media, in which the nonlocality is of general form. We find an exact analytical solution to the nonlinear propagation equation in the case of weak nonlocality. We study the properties...

  19. Exact Solutions in Nonlocal Linear Models

    OpenAIRE

    Vernov, S. Yu.

    2008-01-01

    A general class of cosmological models driven by a nonlocal scalar field inspired by the string field theory is studied. Using the fact that the considering linear nonlocal model is equivalent to an infinite number of local models we have found an exact special solution of the nonlocal Friedmann equations. This solution describes a monotonically increasing Universe with the phantom dark energy.

  20. Nonlocally Centralized Simultaneous Sparse Coding

    Institute of Scientific and Technical Information of China (English)

    雷阳; 宋占杰

    2016-01-01

    The concept of structured sparse coding noise is introduced to exploit the spatial correlations and nonlo-cal constraint of the local structure. Then the model of nonlocally centralized simultaneous sparse coding(NC-SSC)is proposed for reconstructing the original image, and an algorithm is proposed to transform the simultaneous sparse coding into reweighted low-rank approximation. Experimental results on image denoisng, deblurring and super-resolution demonstrate the advantage of the proposed NC-SSC method over the state-of-the-art image resto-ration methods.

  1. The non-local oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, A. [Istituto Tecnico `G. Cardano`, Monterotondo, Rome (Italy)

    1996-08-01

    The most important characteristics of the non-local oscillator, an oscillator subjected to an additional non-local force, are extensively studied by means of a new asymptotic perturbation method that is able to furnish an approximate solution of weakly non-linear differential equations. The resulting motion is doubly periodic, because a second little frequency appears, in addition to the fundamental harmonic frequency. Comparison with the numerical solution obtained by the Runge-Kitta method confirms the validity of the asymptotic perturbation method and its importance for the study of non-linear dynamical systems.

  2. 基于非局部TV正则化的波原子去噪算法%Denoising Algorithm with Wave Atoms Based on Nonlocal TV Regularization

    Institute of Scientific and Technical Information of China (English)

    吴玉莲; 冯象初

    2011-01-01

    结合新的多尺度几何分析工具波原子和非局部TV正则化提出了一种新的纹理图像去噪模型.该模型充分利用了波原子对振荡纹理图像的稀疏表示和非局部TV能较好地处理纹理图像的优点,使得新方法处理后的纹理图像避免了伪吉布斯振荡现象.实验结果表明,新方法的信噪比有一定提高,在保持图像的细节方面与单纯的波原子阈值和非局部TV比较也有明显的改善,取得了比较好的视觉效果.%A novel denoising model for texture images was proposed, which combines the new multiscale geometric analysis tool-wave atoms and nonlocal total variation regularization scheme. This model well considers the advantages:wave atoms which has the ability of sparse representation of the oscillatory texture images and nonlocal TV version has the ability to handle better textures. Numerical experiments show that the proposed model significantly improves the SNR, performance of preserving details is much better than both only wave atoms threshold and nonlocal TV, therefore together with better visual effects.

  3. Novel Single Hazy Image Restoration Method Based on Nonlocal Total Variation Regularization Optimization%基于非局部全变分正则化优化的单幅雾天图像恢复新方法

    Institute of Scientific and Technical Information of China (English)

    何人杰; 樊养余; WANG Zhiyong; FENG David

    2016-01-01

    Based on the property that the scene radiance is of high contrast and the atmospheric veil is locally smooth, a novel single hazy image restoration method based on nonlocal total variation regularization optimization is proposed in this paper. In order to obtain the atmospheric veil of a hazy image, a constrained nonlocal total variation regularization is firstly applied. Then, the accurate atmospheric veil is estimated using a nonlocal Rudin- Osher-Fatemi model, which is solved by a modified split Bregman method. Experimental results demonstrate that the proposed approach is capable of recovering the scene radiance from a single hazy image effectively, especially for the regions with multi-texture.%该文针对无雾图像具有高灰度对比度且大气遮罩局部平滑的特性,提出一种基于非局部全变分正则化优化的单幅雾天图像恢复新方法。先构建一种基于非局部全变分正则化的有约束优化算法对大气遮罩进行估计,然后通过优化Bregman分离迭代法求解非局部Rudin-Osher-Fatemi模型获得准确的大气遮罩,进而从雾天场景图像恢复出场景图像。实验结果表明,所提新方法可以有效地对雾天降质图像进行复原,对多纹理复杂区域的恢复效果也较好。

  4. Nonlocal calculation for nonstrange dibaryons and tribaryons

    CERN Document Server

    Mota, R D; Fernández, F; Entem, D R; Garcilazo, H

    2002-01-01

    We study the possible existence of nonstrange dibaryons and tribaryons by solving the bound-state problem of the two- and three-body systems composed of nucleons and deltas. The two-body systems are $NN$, $N\\Delta$, and $\\Delta\\Delta$, while the three-body systems are $NNN$, $NN\\Delta$, $N\\Delta\\Delta$, and $\\Delta\\Delta\\Delta$. We use as input the nonlocal $NN$, $N\\Delta$, and $\\Delta\\Delta$ potentials derived from the chiral quark cluster model by means of the resonating group method. We compare with previous results obtained from the local version based on the Born-Oppenheimer approximation.

  5. Atomically informed nonlocal semi-discrete variational Peierls-Nabarro model for planar core dislocations.

    Science.gov (United States)

    Liu, Guisen; Cheng, Xi; Wang, Jian; Chen, Kaiguo; Shen, Yao

    2017-03-02

    Prediction of Peierls stress associated with dislocation glide is of fundamental concern in understanding and designing the plasticity and mechanical properties of crystalline materials. Here, we develop a nonlocal semi-discrete variational Peierls-Nabarro (SVPN) model by incorporating the nonlocal atomic interactions into the semi-discrete variational Peierls framework. The nonlocal kernel is simplified by limiting the nonlocal atomic interaction in the nearest neighbor region, and the nonlocal coefficient is directly computed from the dislocation core structure. Our model is capable of accurately predicting the displacement profile, and the Peierls stress, of planar-extended core dislocations in face-centered cubic structures. Our model could be extended to study more complicated planar-extended core dislocations, such as {111} dislocations in Al-based and Ti-based intermetallic compounds.

  6. A nonlocal discretization of fields

    CERN Document Server

    Campos, R G; Pimentel, L O; Campos, Rafael G.; Tututi, Eduardo S.

    2001-01-01

    A nonlocal method to obtain discrete classical fields is presented. This technique relies on well-behaved matrix representations of the derivatives constructed on a non--equispaced lattice. The drawbacks of lattice theory like the fermion doubling or the breaking of chiral symmetry for the massless case, are absent in this method.

  7. Learning Non-Local Dependencies

    Science.gov (United States)

    Kuhn, Gustav; Dienes, Zoltan

    2008-01-01

    This paper addresses the nature of the temporary storage buffer used in implicit or statistical learning. Kuhn and Dienes [Kuhn, G., & Dienes, Z. (2005). Implicit learning of nonlocal musical rules: implicitly learning more than chunks. "Journal of Experimental Psychology-Learning Memory and Cognition," 31(6) 1417-1432] showed that people could…

  8. Learning Non-Local Dependencies

    Science.gov (United States)

    Kuhn, Gustav; Dienes, Zoltan

    2008-01-01

    This paper addresses the nature of the temporary storage buffer used in implicit or statistical learning. Kuhn and Dienes [Kuhn, G., & Dienes, Z. (2005). Implicit learning of nonlocal musical rules: implicitly learning more than chunks. "Journal of Experimental Psychology-Learning Memory and Cognition," 31(6) 1417-1432] showed that people could…

  9. Extreme nonlocality with one photon

    Energy Technology Data Exchange (ETDEWEB)

    Heaney, Libby; Vedral, Vlatko [Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU (United Kingdom); Cabello, Adan [Departamento de Fisica Aplicada II, Universidad de Sevilla, E-41012 Sevilla (Spain); Santos, Marcelo Franca, E-mail: l.heaney1@physics.ox.ac.uk, E-mail: adan@us.es [Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte, Caixa Postal 702, 30123-970, MG (Brazil)

    2011-05-15

    Quantum nonlocality is typically assigned to systems of two or more well-separated particles, but nonlocality can also exist in systems consisting of just a single particle when one considers the subsystems to be distant spatial field modes. Single particle nonlocality has been confirmed experimentally via a bipartite Bell inequality. In this paper, we introduce an N-party Hardy-like proof of the impossibility of local elements of reality and a Bell inequality for local realistic theories in the case of a single particle superposed symmetrically over N spatial field modes (i.e. N qubit W state). We show that, in the limit of large N, the Hardy-like proof effectively becomes an all-versus-nothing (or Greenberger-Horne-Zeilinger (GHZ)-like) proof, and the quantum-classical gap of the Bell inequality tends to be the same as that in a three-particle GHZ experiment. We describe how to test the nonlocality in realistic systems.

  10. Collapse arrest and soliton stabilization in nonlocal nonlinear media

    DEFF Research Database (Denmark)

    Bang, Ole; Krolikowski, Wieslaw; Wyller, John

    2002-01-01

    We investigate the properties of localized waves in cubic nonlinear materials with a symmetric nonlocal nonlinear response of arbitrary shape and degree of nonlocality, described by a general nonlocal nonlinear Schrodinger type equation. We prove rigorously by bounding the Hamiltonian that nonloc......We investigate the properties of localized waves in cubic nonlinear materials with a symmetric nonlocal nonlinear response of arbitrary shape and degree of nonlocality, described by a general nonlocal nonlinear Schrodinger type equation. We prove rigorously by bounding the Hamiltonian...

  11. Quantum theory is classical mechanics with non-local existence

    CERN Document Server

    Hegseth, John

    2009-01-01

    I propose a new and direct connection between classical mechanics and quantum mechanics where I derive the quantum mechanical propagator from a variational principle. This variational principle is Hamilton's modified principle generalized to allow many paths due to the non-local existence of particles in phase space. This principle allows a physical system to evolve non-locally in phase space while still allowing a representation that uses many classical paths. Whereas a point in phase space represents a classical system's state, I represent the state of a non-local system by a mixed trajectory. This formulation naturally leads to the transactional interpretation for resolving the paradoxes of the measurement problem. This principle also suggests a more flexible framework for formulating theories based on invariant actions and provides a single conceptual framework for discussing many areas of science.

  12. Image and video restorations via nonlocal kernel regression.

    Science.gov (United States)

    Zhang, Haichao; Yang, Jianchao; Zhang, Yanning; Huang, Thomas S

    2013-06-01

    A nonlocal kernel regression (NL-KR) model is presented in this paper for various image and video restoration tasks. The proposed method exploits both the nonlocal self-similarity and local structural regularity properties in natural images. The nonlocal self-similarity is based on the observation that image patches tend to repeat themselves in natural images and videos, and the local structural regularity observes that image patches have regular structures where accurate estimation of pixel values via regression is possible. By unifying both properties explicitly, the proposed NL-KR framework is more robust in image estimation, and the algorithm is applicable to various image and video restoration tasks. In this paper, we apply the proposed model to image and video denoising, deblurring, and superresolution reconstruction. Extensive experimental results on both single images and realistic video sequences demonstrate that the proposed framework performs favorably with previous works both qualitatively and quantitatively.

  13. Theory of genuine tripartite nonlocality of Gaussian states.

    Science.gov (United States)

    Adesso, Gerardo; Piano, Samanta

    2014-01-10

    We investigate the genuine multipartite nonlocality of three-mode Gaussian states of continuous variable systems. For pure states, we present a simplified procedure to obtain the maximum violation of the Svetlichny inequality based on displaced parity measurements, and we analyze its interplay with genuine tripartite entanglement measured via Rényi-2 entropy. The maximum Svetlichny violation admits tight upper and lower bounds at fixed tripartite entanglement. For mixed states, no violation is possible when the purity falls below 0.86. We also explore a set of recently derived weaker inequalities for three-way nonlocality, finding violations for all tested pure states. Our results provide a strong signature for the nonclassical and nonlocal nature of Gaussian states despite their positive Wigner function, and lead to precise recipes for its experimental verification.

  14. Structure of nonlocality of plasma turbulence

    Science.gov (United States)

    Gürcan, Ö. D.; Vermare, L.; Hennequin, P.; Berionni, V.; Diamond, P. H.; Dif-Pradalier, G.; Garbet, X.; Ghendrih, P.; Grandgirard, V.; McDevitt, C. J.; Morel, P.; Sarazin, Y.; Storelli, A.; Bourdelle, C.; the Tore Supra Team

    2013-07-01

    Various indications on the weakly nonlocal character of turbulent plasma transport both from experimental fluctuation measurements from Tore Supra and observations from the full-f, flux-driven gyrokinetic code GYSELA are reported. A simple Fisher equation model of this weakly nonlocal dynamics can be formulated in terms of an evolution equation for the turbulent entropy density, which contains the basic phenomenon of radial turbulence spreading in addition to avalanche-like dynamics via coupling to profile modulations. A derivation of this model, which contains the so-called beach effect, a diffusive and convective flux components for the flux of turbulence intensity, in addition to linear group propagation is given, starting from the drift-kinetic equation. The proposed model has the form of a transport equation for turbulence intensity, and may be considered as an addition to transport modelling. The kinetic fluxes given, can be computed using model closures, or local gyrokinetics. The model is also used in a particular setup that represents the near edge region as a relatively stable zone between the core and edge region where the energy injection is locally more substantial. It is observed that with constant, physical coefficients, the model gives a convincing qualitative profile of fluctuation intensity when the turbulence is coming from the core region with either a group velocity or a convective flux.

  15. Discrete model of dislocations in fractional nonlocal elasticity

    Directory of Open Access Journals (Sweden)

    Vasily E. Tarasov

    2016-01-01

    Full Text Available Discrete models of dislocations in fractional nonlocal materials are suggested. The proposed models are based on fractional-order differences instead of finite differences of integer orders that are usually used. The fractional differences allow us to describe long-range interactions in materials. In continuous limit the suggested discrete models give continuum models of dislocations in nonlocal continua. Fractional generalization of the Frenkel–Kontorova model by using long-range interactions is suggested. We also propose a fractional generalization of interacting atomic chains (IAC model of dislocations by considering long-range interacting chains.

  16. Nonlocal plasticity effects on interaction of different size voids

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Niordson, Christian Frithiof

    2004-01-01

    A nonlocal elastic-plastic material model is used to show that the rate of void growth is significantly reduced when the voids are small enough to be comparable with a characteristic material length. For a very small void in the material between much larger voids the competition between...... an increased growth rate due to the stress concentrations around the larger voids and a reduced growth rate due to the nonlocal effects is studied. The analyses are based on an axisymmetric unit cell model with special boundary conditions, which allow for a relatively simple investigation of a full three...

  17. Dynamical nonlocal coherent-potential approximation for itinerant electron magnetism.

    Science.gov (United States)

    Rowlands, D A; Zhang, Yu-Zhong

    2014-11-26

    A dynamical generalisation of the nonlocal coherent-potential approximation is derived based upon the functional integral approach to the interacting electron problem. The free energy is proven to be variational with respect to the self-energy provided a self-consistency condition on a cluster of sites is satisfied. In the present work, calculations are performed within the static approximation and the effect of the nonlocal physics on the formation of the local moment state in a simple model is investigated. The results reveal the importance of the dynamical correlations.

  18. Role of local and nonlocal interactions in folding and misfolding of globular proteins

    Science.gov (United States)

    Kumar, Adesh; Baruah, Anupaul; Biswas, Parbati

    2017-02-01

    A Monte Carlo simulation based sequence design method is proposed to study the role of the local and the nonlocal interactions with varying secondary structure content in protein folding, misfolding and unfolding. A statistical potential is developed from the compilation of a data set of proteins, which accounts for the respective contribution of local and the nonlocal interactions. Sequences are designed through a combination of positive and negative design by a Monte Carlo simulation in the sequence space. The weights of the local and the nonlocal interactions are tuned appropriately to study the role of the local and the nonlocal interactions in the folding, unfolding and misfolding of the designed sequences. Results suggest that the nonlocal interactions are the primary determinant of protein folding while the local interactions may be required but not always necessary. The nonlocal interactions mainly guide the polypeptide chain to form compact structures but do not differentiate between the native-like conformations, while the local interactions stabilize the target conformation against the native-like competing conformations. The study concludes that the local interactions govern the fold-misfold transition, while the nonlocal interactions regulate the fold-unfold transition of proteins. However, for proteins with predominantly β-sheet content, the nonlocal interactions control both fold-misfold and fold-unfold transitions.

  19. Nonlocal Optical Spatial Soliton with a Non-parabolic Symmetry and Real-valued Convolution Response Kernel

    Institute of Scientific and Technical Information of China (English)

    LI Ke-Ping; YU Chao-Fan; GAO Zi-You; LIANG Guo-Dong; YU Xiao-Min

    2008-01-01

    Based on the picture of nonlinear and non-parabolic symmetry response, I.e., △n2( I) ≈ p(αo -α1x- α2x2), we propose a model for the transversal beam intensity distribution of the nonlocal spatial soliton. In this model, as a convolution response with non-parabolic symmetry, △n2( I) ≈ p(b0+b1 f - b2 f2 with b2/b1 > 0 is assumed. Furthermore, instead of the wave function Ψ, the high-order nonlinear equation for the beam intensity distribution f has been derived and the bell-shaped soliton solution with the envelope form has been obtained. The results demonstrate that, since the existence of the terms of non-parabolic response, the nonlocal spatial soliton has the bistable state solution. If thefrequency shift of wave number β satisfies 0 0 has been demonstrated.

  20. Non-local means de-noising approach based on dictionary learning%基于字典学习的非局部均值去噪算法

    Institute of Scientific and Technical Information of China (English)

    崔学英; 张权; 桂志国

    2013-01-01

    Concerning the measurement of the similarity of non-local means, a method based on dictionary learning was presented. First, block matching based local pixel grouping was used to eliminate the interference by dissimilar image blocks. Then, the corrupted similar blocks were denoised by dictionary learning. As a further development of classical sparse representation model, the similar patches were unified for joint sparse representation and learning an efficient and compact dictionary by principal component analysis, so that the similar patches relevency could be well preserved. This similarity between the pixels was measured by the Euclidean distance of denoised image blocks, which can well show the similarity of the similar blocks. The experimental results show the modified algorithm has a superior denoising performance than the original one in terms of both Peak Signal-to-Noise Ratio (PSNR) and subjective visual quality. For some images whose structural similarity is large and with rich detail information, their structures and details are well preserved. The robustness of the presented method is superior to the original one.%针对非局部均值中相似度的衡量问题,提出了一种基于字典学习的度量算法.首先利用局部像素群块匹配方法消除不相似的图像块带来的干扰,然后对含有噪声的相似块采用字典学习的方法降噪.与经典的字典学习不同的是,对相似块采用联合稀疏编码的思想,利用主成分分析法学习一个高效紧字典,保留相似块间的相关性信息.采用降噪后的图像块间的欧氏距离计算像素间的相似度,能更好地反映相似块的相似性.实验结果表明,所提出的方法在峰值信噪比和视觉效果方面都优于传统算法,尤其对含有较多细节且结构相似性强的图像,细节和纹理部分的保持效果更好,算法的鲁棒性也优于传统算法.

  1. Characterizing 3-qubit UPB states: violations of LHV models, preparation via nonlocal unitaries and PPT entangled nonlocal orbits

    CERN Document Server

    Altafini, C

    2004-01-01

    For the 3-qubit UPB state, i.e., the bound entangled state constructed from an Unextendable Product Basis of Bennett et al. (Phys. Rev. Lett. 82:5385, 1999), we provide a set of violations of Local Hidden Variable (LHV) models based on the particular type of reflection symmetry encoded in this state. The explicit nonlocal unitary operation needed to prepare the state from its reflected separable mixture of pure states is given, as well as a nonlocal one-parameter orbit of states with Positive Partial Transpositions (PPT) which swaps the entanglement between a state and its reflection twice during a period.

  2. BSLIC: SLIC Superpixels Based on Boundary Term

    Directory of Open Access Journals (Sweden)

    Hai Wang

    2017-02-01

    Full Text Available A modified method for better superpixel generation based on simple linear iterative clustering (SLIC is presented and named BSLIC in this paper. By initializing cluster centers in hexagon distribution and performing k-means clustering in a limited region, the generated superpixels are shaped into regular and compact hexagons. The additional cluster centers are initialized as edge pixels to improve boundary adherence, which is further promoted by incorporating the boundary term into the distance calculation of the k-means clustering. Berkeley Segmentation Dataset BSDS500 is used to qualitatively and quantitatively evaluate the proposed BSLIC method. Experimental results show that BSLIC achieves an excellent compromise between boundary adherence and regularity of size and shape. In comparison with SLIC, the boundary adherence of BSLIC is increased by at most 12.43% for boundary recall and 3.51% for under segmentation error.

  3. Non-Local Euclidean Medians.

    Science.gov (United States)

    Chaudhury, Kunal N; Singer, Amit

    2012-11-01

    In this letter, we note that the denoising performance of Non-Local Means (NLM) can be improved at large noise levels by replacing the mean by the Euclidean median. We call this new denoising algorithm the Non-Local Euclidean Medians (NLEM). At the heart of NLEM is the observation that the median is more robust to outliers than the mean. In particular, we provide a simple geometric insight that explains why NLEM performs better than NLM in the vicinity of edges, particularly at large noise levels. NLEM can be efficiently implemented using iteratively reweighted least squares, and its computational complexity is comparable to that of NLM. We provide some preliminary results to study the proposed algorithm and to compare it with NLM.

  4. Percolation transitions with nonlocal constraint.

    Science.gov (United States)

    Shim, Pyoung-Seop; Lee, Hyun Keun; Noh, Jae Dong

    2012-09-01

    We investigate percolation transitions in a nonlocal network model numerically. In this model, each node has an exclusive partner and a link is forbidden between two nodes whose r-neighbors share any exclusive pair. The r-neighbor of a node x is defined as a set of at most N(r) neighbors of x, where N is the total number of nodes. The parameter r controls the strength of a nonlocal effect. The system is found to undergo a percolation transition belonging to the mean-field universality class for r1/2, the system undergoes a peculiar phase transition from a nonpercolating phase to a quasicritical phase where the largest cluster size G scales as G~N(α) with α=0.74(1). In the marginal case with r=1/2, the model displays a percolation transition that does not belong to the mean-field universality class.

  5. Rogue waves in nonlocal media

    CERN Document Server

    Horikis, Theodoros P

    2016-01-01

    The generation of rogue waves is investigated via a nonlocal nonlinear Schrodinger (NLS) equation. In this system, modulation instability is suppressed and is usually expected that rogue wave formation would also be limited. On the contrary, a parameter regime is identified where the instability is suppressed but nevertheless the number and amplitude of the rogue events increase, as compared to the standard NLS (which is a limit of the nonlocal system). Furthermore, the nature of these waves is investigated; while no analytical solutions are known to model these events, numerically it is shown that they differ significantly from either the rational (Peregrine) or soliton solution of the limiting NLS equation. As such, these findings may also help in rogue wave realization experimentally in these media.

  6. Nonlocal Quantum Effects in Cosmology

    CERN Document Server

    Dumin, Yurii V

    2014-01-01

    Since it is commonly believed that the observed large-scale structure of the Universe is an imprint of quantum fluctuations existing at the very early stage of its evolution, it is reasonable to pose the question: Do the effects of quantum nonlocality, which are well established now by the laboratory studies, manifest themselves also in the early Universe? We try to answer this question by utilizing the results of a few experiments, namely, with the superconducting multi-Josephson-junction loops and the ultracold gases in periodic potentials. Employing a close analogy between the above-mentioned setups and the simplest one-dimensional Friedmann-Robertson-Walker cosmological model, we show that the specific nonlocal correlations revealed in the laboratory studies might be of considerable importance also in treating the strongly-nonequilibrium phase transitions of Higgs fields in the early Universe. Particularly, they should substantially reduce the number of topological defects (e.g., domain walls) expected du...

  7. Nonlocal reflection by photonic barriers

    OpenAIRE

    Vetter, R. -M.; A. Haibel; Nimtz, G.

    2001-01-01

    The time behaviour of microwaves undergoing partial reflection by photonic barriers was measured in the time and in the frequency domain. It was observed that unlike the duration of partial reflection by dielectric layers, the measured reflection duration of barriers is independent of their length. The experimental results point to a nonlocal behaviour of evanescent modes at least over a distance of some ten wavelengths. Evanescent modes correspond to photonic tunnelling in quantum mechanics.

  8. Gravity and non-locality

    CERN Document Server

    Diaz, Pablo; Walton, Mark

    2016-01-01

    With the aim of investigating the relation between gravity and non-locality at the classical level, we study a bilocal scalar field model. Bilocality introduces new (internal) degrees of freedom that can potentially reproduce gravity. We show that the equations of motion of the massless branch of the free bilocal model match those of linearized gravity. We also discuss higher orders of perturbation theory, where there is self-interaction in both gravity and the bilocal field sectors.

  9. Boundary fluxes for nonlocal diffusion

    Science.gov (United States)

    Cortazar, Carmen; Elgueta, Manuel; Rossi, Julio D.; Wolanski, Noemi

    We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence, uniqueness and a comparison principle. Next, we study the behavior of solutions for some prescribed boundary data including blowing up ones. Finally, we look at a nonlinear flux boundary condition.

  10. Contact of boundary-value problems and nonlocal problems in mathematical models of heat transfer

    Science.gov (United States)

    Lyashenko, V.; Kobilskaya, O.

    2015-10-01

    In this paper the mathematical models in the form of nonlocal problems for the two-dimensional heat equation are considered. Relation of a nonlocal problem and a boundary value problem, which describe the same physical heating process, is investigated. These problems arise in the study of the temperature distribution during annealing of the movable wire and the strip by permanent or periodically operating internal and external heat sources. The first and the second nonlocal problems in the mobile area are considered. Stability and convergence of numerical algorithms for the solution of a nonlocal problem with piecewise monotone functions in the equations and boundary conditions are investigated. Piecewise monotone functions characterize the heat sources and heat transfer conditions at the boundaries of the area that is studied. Numerous experiments are conducted and temperature distributions are plotted under conditions of internal and external heat sources operation. These experiments confirm the effectiveness of attracting non-local terms to describe the thermal processes. Expediency of applying nonlocal problems containing nonlocal conditions - thermal balance conditions - to such models is shown. This allows you to define heat and mass transfer as the parameters of the process control, in particular heat source and concentration of the substance.

  11. Modulational instability in nonlocal nonlinear Kerr media

    DEFF Research Database (Denmark)

    Krolikowski, Wieslaw; Bang, Ole; Juul Rasmussen, Jens

    2001-01-01

    We study modulational instability (MI) of plane waves in nonlocal nonlinear Kerr media. For a focusing nonlinearity we show that, although the nonlocality tends to suppress MI, it can never remove it completely, irrespective of the particular profile of the nonlocal response function....... For a defocusing nonlinearity the stability properties depend sensitively on the response function profile: for a smooth profile (e.g., a Gaussian) plane waves are always stable, but MI may occur for a rectangular response. We also find that the reduced model for a weak nonlocality predicts MI in defocusing media...... for arbitrary response profiles, as long as the intensity exceeds a certain critical value. However, it appears that this regime of MI is beyond the validity of the reduced model, if it is to represent the weakly nonlocal limit of a general nonlocal nonlinearity, as in optics and the theory of Bose...

  12. Towards LHC physics with nonlocal Standard Model

    Directory of Open Access Journals (Sweden)

    Tirthabir Biswas

    2015-09-01

    Full Text Available We take a few steps towards constructing a string-inspired nonlocal extension of the Standard Model. We start by illustrating how quantum loop calculations can be performed in nonlocal scalar field theory. In particular, we show the potential to address the hierarchy problem in the nonlocal framework. Next, we construct a nonlocal abelian gauge model and derive modifications of the gauge interaction vertex and field propagators. We apply the modifications to a toy version of the nonlocal Standard Model and investigate collider phenomenology. We find the lower bound on the scale of nonlocality from the 8 TeV LHC data to be 2.5–3 TeV.

  13. Nonlocal transport in superconducting oxide nanostructures

    Science.gov (United States)

    Veazey, Joshua; Cheng, Guanglei; Lu, Shicheng; Tomczyk, Michelle; Irvin, Patrick; Huang, Mengchen; Wung Bark, Chung; Ryu, Sangwoo; Eom, Chang-Beom; Levy, Jeremy

    2013-03-01

    We report nonlocal transport signatures in the superconducting state of nanostructures formed[2] at the LaAlO3/SrTiO3 interface using conductive AFM lithography. Nonlocal resistances (nonlocal voltage divided by current) are as large as 200 Ω when 2-10 μm separate the current-carrying segments from the voltage-sensing leads. The nonlocal resistance reverses sign at the local critical current of the superconducting state. Features observed in the nonlocal V-I curves evolve with back gate voltage and magnetic field, and are correlated with the local four-terminal V-I curves. We discuss how nonlocal and local transport effects in LaAlO3/SrTiO3 nanostructures may result from the electronic phase separation and superconducting inhomogeneity reported by others in planar structures[3]. This work is supported by AFOSR (FA9550-10-1-0524) and NSF DMR-0906443

  14. Detrimental nonlocality in luminescence measurements

    Science.gov (United States)

    Pluska, Mariusz; Czerwinski, Andrzej

    2017-08-01

    Luminescence studies are used to investigate the local properties of various light-emitting materials. A critical issue of these studies is presented that the signals often lack all advantages of luminescence-studies of high locality, and may originate from an extended spatial region of even a few millimeters in size or the whole sample, i.e., places other than intended for investigation. This is a key problem for research and development in photonics. Due to this nonlocality, information indicating defects, irregularities, nonuniformities and inhomogeneities is lost. The issue refers to typical structures with a strong built-in electric field. Such fields exist intentionally in most photonic structures and occur unintentionally in many other materials investigated by applied physics. We reveal [using test samples prepared with focused ion beam (FIB) on an AlGaAs/GaAs laser heterostructure with an InGaAs quantum well (QW)] that nonlocality increases at low temperatures. This is contrary to the widely expected outcome, as low-temperature luminescence measurements are usually assumed to be free from disturbances. We explain many effects observed due to nonlocality in luminescence studies and prove that separation of the investigated area by focused ion beam milling is a practical solution enabling truly local luminescence measurements. All conclusions drawn using the example of cathodoluminescence are useful for other luminescence techniques.

  15. Nonlocal response of hyperbolic metasurfaces.

    Science.gov (United States)

    Correas-Serrano, D; Gomez-Diaz, J S; Tymchenko, M; Alù, A

    2015-11-16

    We analyze and model the nonlocal response of ultrathin hyperbolic metasurfaces (HMTSs) by applying an effective medium approach. We show that the intrinsic spatial dispersion in the materials employed to realize the metasurfaces imposes a wavenumber cutoff on the hyperbolic isofrequency contour, inversely proportional to the Fermi velocity, and we compare it with the cutoff arising from the structure granularity. In the particular case of HTMSs implemented by an array of graphene nanostrips, we find that graphene nonlocality can become the dominant mechanism that closes the hyperbolic contour - imposing a wavenumber cutoff at around 300k(0) - in realistic configurations with periodicity Lnonlocal response is mainly relevant in hyperbolic metasurfaces and metamaterials with periodicity below a few nm, being very weak in practical scenarios. In addition, we investigate how spatial dispersion affects the spontaneous emission rate of emitters located close to HMTSs. Our results establish an upper bound set by nonlocality to the maximum field confinement and light-matter interactions achievable in practical HMTSs, and may find application in the practical development of hyperlenses, sensors and on-chip networks.

  16. Nonlocalized cluster dynamics and nuclear molecular structure

    CERN Document Server

    Zhou, Bo; Horiuchi, Hisashi; Ren, Zhongzhou; Röpke, Gerd; Schuck, Peter; Tohsaki, Akihiro; Xu, Chang; Yamada, Taiichi

    2013-01-01

    A container picture is proposed for understanding cluster dynamics where the clusters make nonlocalized motion occupying the lowest orbit of the cluster mean-field potential characterized by the size parameter $``B"$ in the THSR (Tohsaki-Horiuchi-Schuck-R\\"{o}pke) wave function. The nonlocalized cluster aspects of the inversion-doublet bands in $^{20}$Ne which have been considered as a typical manifestation of localized clustering are discussed. So far unexplained puzzling features of the THSR wave function, namely that after angular-momentum projection for two cluster systems the prolate THSR wave function is almost 100$\\%$ equivalent to an oblate THSR wave function is clarified. It is shown that the true intrinsic two-cluster THSR configuration is nonetheless prolate. The proposal of the container picture is based on the fact that typical cluster systems, 2$\\alpha$, 3$\\alpha$, and $\\alpha$+$^{16}$O, are all well described by a single THSR wave function. It will be shown for the case of linear-chain states w...

  17. Non-local models for ductile failure

    Science.gov (United States)

    César de Sá, José; Azinpour, Erfan; Santos, Abel

    2016-08-01

    Ductile damage can be dealt with continuous descriptions of material, resorting, for example, to continuous damage mechanic descriptions or micromechanical constitutive models. When it comes to describe material behaviour near and beyond fracture these approaches are no longer sufficient or valid and continuous/discontinuous approaches can be adopted to track fracture initiation and propagation. Apart from more pragmatic solutions like element erosion or remeshing techniques more advanced approaches based on the X-FEM concept, in particular associated with non-local formulations, may be adopted to numerically model these problems. Nevertheless, very often, for practical reasons, some important aspects are somewhat left behind, specially energetic requirements to promote the necessary transition of energy release associated with material damage and fracture energy associated to a crack creation and evolution. Phase-field methods may combine advantages of regularised continuous models by providing a similar description to non-local thermodynamical continuous damage mechanics, as well as, a "continuous" approach to numerically follow crack evolution and branching

  18. A nonlocal spatial model for Lyme disease

    Science.gov (United States)

    Yu, Xiao; Zhao, Xiao-Qiang

    2016-07-01

    This paper is devoted to the study of a nonlocal and time-delayed reaction-diffusion model for Lyme disease with a spatially heterogeneous structure. In the case of a bounded domain, we first prove the existence of the positive steady state and a threshold type result for the disease-free system, and then establish the global dynamics for the model system in terms of the basic reproduction number. In the case of an unbound domain, we obtain the existence of the disease spreading speed and its coincidence with the minimal wave speed. At last, we use numerical simulations to verify our analytic results and investigate the influence of model parameters and spatial heterogeneity on the disease infection risk.

  19. Making nonlocal reality compatible with relativity

    OpenAIRE

    Nikolic, H.

    2010-01-01

    It is often argued that hypothetic nonlocal reality responsible for nonlocal quantum correlations between entangled particles cannot be consistent with relativity. I review the most frequent arguments of that sort, explain how they can all be circumvented, and present an explicit Bohmian model of nonlocal reality (compatible with quantum phenomena) that fully obeys the principle of relativistic covariance and does not involve a preferred Lorentz frame.

  20. Nonlocal Gravity in the Solar System

    CERN Document Server

    Chicone, C

    2015-01-01

    The implications of the recent classical nonlocal generalization of Einstein's theory of gravitation for gravitational physics in the Solar System are investigated. In this theory, the nonlocal character of gravity simulates dark matter. Nonlocal gravity in the Newtonian regime involves a reciprocal kernel with three spatial parameters, of which two have already been determined from the rotation curves of spiral galaxies and the internal dynamics of clusters of galaxies. However, the short-range parameter a_0 remains to be determined. In this connection, the nonlocal contribution to the perihelion precession of a planetary orbit is estimated and a preliminary lower limit on a_0 is determined.

  1. Nonlocal gravity in the solar system

    Science.gov (United States)

    Chicone, C.; Mashhoon, B.

    2016-04-01

    The implications of the recent classical nonlocal generalization of Einstein’s theory of gravitation for gravitational physics in the solar system are investigated. In this theory, the nonlocal character of gravity appears to simulate dark matter. Nonlocal gravity in the Newtonian regime involves a reciprocal kernel with three spatial parameters, of which two have already been determined from the rotation curves of spiral galaxies and the internal dynamics of clusters of galaxies. However, the short-range parameter a 0 remains to be determined. In this connection, the nonlocal contribution to the perihelion precession of a planetary orbit is estimated and a preliminary lower limit on a 0 is determined.

  2. Perturbative loop corrections and nonlocal gravity

    CERN Document Server

    Maggiore, Michele

    2016-01-01

    Nonlocal gravity has been shown to provide a phenomenologically viable infrared modification of GR. A natural question is whether the required nonlocality can emerge from perturbative quantum loop corrections due to light particles. We show that this is not the case. For the value of the mass scale of the non-local models required by cosmology, the perturbative form factors obtained from the loop corrections, in the present cosmological epoch, are in the regime where they are local. The mechanism behind the generation of the required nonlocality must be more complex, possibly related to strong infrared effects and non-perturbative mass generation for the conformal mode.

  3. Local and Nonlocal Regularization to Image Interpolation

    Directory of Open Access Journals (Sweden)

    Yi Zhan

    2014-01-01

    Full Text Available This paper presents an image interpolation model with local and nonlocal regularization. A nonlocal bounded variation (BV regularizer is formulated by an exponential function including gradient. It acts as the Perona-Malik equation. Thus our nonlocal BV regularizer possesses the properties of the anisotropic diffusion equation and nonlocal functional. The local total variation (TV regularizer dissipates image energy along the orthogonal direction to the gradient to avoid blurring image edges. The derived model efficiently reconstructs the real image, leading to a natural interpolation which reduces blurring and staircase artifacts. We present experimental results that prove the potential and efficacy of the method.

  4. Direct prediction of profiles of sequences compatible with a protein structure by neural networks with fragment-based local and energy-based nonlocal profiles.

    Science.gov (United States)

    Li, Zhixiu; Yang, Yuedong; Faraggi, Eshel; Zhan, Jian; Zhou, Yaoqi

    2014-10-01

    Locating sequences compatible with a protein structural fold is the well-known inverse protein-folding problem. While significant progress has been made, the success rate of protein design remains low. As a result, a library of designed sequences or profile of sequences is currently employed for guiding experimental screening or directed evolution. Sequence profiles can be computationally predicted by iterative mutations of a random sequence to produce energy-optimized sequences, or by combining sequences of structurally similar fragments in a template library. The latter approach is computationally more efficient but yields less accurate profiles than the former because of lacking tertiary structural information. Here we present a method called SPIN that predicts Sequence Profiles by Integrated Neural network based on fragment-derived sequence profiles and structure-derived energy profiles. SPIN improves over the fragment-derived profile by 6.7% (from 23.6 to 30.3%) in sequence identity between predicted and wild-type sequences. The method also reduces the number of residues in low complex regions by 15.7% and has a significantly better balance of hydrophilic and hydrophobic residues at protein surface. The accuracy of sequence profiles obtained is comparable to those generated from the protein design program RosettaDesign 3.5. This highly efficient method for predicting sequence profiles from structures will be useful as a single-body scoring term for improving scoring functions used in protein design and fold recognition. It also complements protein design programs in guiding experimental design of the sequence library for screening and directed evolution of designed sequences. The SPIN server is available at http://sparks-lab.org.

  5. Self-localized states for electron transfer in nonlocal continuum deformable media

    Energy Technology Data Exchange (ETDEWEB)

    Cisneros-Ake, Luis A., E-mail: cisneros@esfm.ipn.mx

    2016-08-19

    We consider the problem of electron transport in a deformable continuum medium subjected to an external harmonic substrate potential. We then consider the quasi-stationary state of the full problem to find a Gross–Pitaevskii type equation with a nonlocal external potential, which is solved by variational and numerical means (considered as the exact solution) to find the parameter conditions for the existence of self-localized solutions. The variational approach predicts a threshold on the on-site or nonlocality parameter where localized solutions cease to exist from the Non-Linear Schrödinger soliton limit. A numerical continuation of stationary state solutions in the corresponding discrete system is used to confirm the prediction of the turning value in the on-site term. We finally study the full stationary state and make use of an approximation, proposed by Briedis et al. [17], for the nonlocal term, corresponding to strong nonlocalities, to find analytic expressions for self-localized states in terms of the series solutions of a nonlinear modified Bessel equation. - Highlights: • Nonlocality overcomes nonlinearity at a threshold value to cease the existence of coherent solutions. • Variational and series expansion solutions predict the formation of coherent structures in nonlocal deformable media. • Full numerical solutions confirm the persistence of localized solutions.

  6. Combinatorics and quantum nonlocality.

    Science.gov (United States)

    Buhrman, Harry; Høyer, Peter; Massar, Serge; Röhrig, Hein

    2003-07-25

    We use techniques for lower bounds on communication to derive necessary conditions (in terms of detector efficiency or amount of superluminal communication) for being able to reproduce the quantum correlations occurring in Einstein-Podolsky-Rosen-type experiments with classical local hidden-variable theories. As an application, we consider n parties sharing a Greenberger-Horne-Zeilinger-type state and show that the amount of superluminal classical communication required to reproduce the correlations is at least n(log((2)n-3) bits and the maximum detector efficiency eta(*) for which the resulting correlations can still be reproduced by a local hidden-variable theory is upper bounded by eta(*)

  7. Nonlocal bottleneck effect in two-dimensional turbulence

    CERN Document Server

    Biskamp, D; Schwarz, E

    1998-01-01

    The bottleneck pileup in the energy spectrum is investigated for several two-dimensional (2D) turbulence systems by numerical simulation using high-order diffusion terms to amplify the effect, which is weak for normal diffusion. For 2D magnetohydrodynamic (MHD) turbulence, 2D electron MHD (EMHD) turbulence and 2D thermal convection, which all exhibit direct energy cascades, a nonlocal behavior is found resulting in a logarithmic enhancement of the spectrum.

  8. GAUSSIAN PRINCIPLE COMPONENTS FOR NONLOCAL MEANS IMAGE DENOISING

    Institute of Scientific and Technical Information of China (English)

    Li Xiangping; Wang Xiaotian; Shi Guangming

    2011-01-01

    NonLocal Means (NLM),taking fully advantage of image redundancy,has been proved to be very effective in noise removal.However,high computational load limits its wide application.Based on Principle Component Analysis (PCA),Principle Neighborhood Dictionary (PND) was proposed to reduce the computational load of NLM.Nevertheless,as the principle components in PND method are computed directly from noisy image neighborhoods,they are prone to be inaccurate due to the presence of noise.In this paper,an improved scheme for image denoising is proposed.This scheme is based on PND and uses preprocessing via Gaussian filter to eliminate the influence of noise.PCA is then used to project those filtered image neighborhood vectors onto a lower-dimensional space.With the preprocessing process,the principle components computed are more accurate resulting in an improved denoising performance.A comparison with some NLM based and state-of-art denoising methods shows that the proposed method performs well in terms of Peak Signal to Noise Ratio (PSNR) as well as image visual fidelity.The experimental results demonstrate that our method outperforms existing methods both subjectively and objectively.

  9. Theoretical Foundations of Incorporating Local Boundary Conditions into Nonlocal Problems

    Science.gov (United States)

    Aksoylu, Burak; Beyer, Horst Reinhard; Celiker, Fatih

    2017-08-01

    We study nonlocal equations from the area of peridynamics on bounded domains. We present four main results. In our recent paper, we have discovered that, on R, the governing operator in peridynamics, which involves a convolution, is a bounded function of the classical (local) governing operator. Building on this, as main result 1, we construct an abstract convolution operator on bounded domains which is a generalization of the standard convolution based on integrals. The abstract convolution operator is a function of the classical operator, defined by a Hilbert basis available due to the purely discrete spectrum of the latter. As governing operator of the nonlocal equation we use a function of the classical operator, this allows us to incorporate local boundary conditions into nonlocal theories. As main result 2, we prove that the solution operator can be uniquely decomposed into a Hilbert-Schmidt operator and a multiple of the identity operator. As main result 3, we prove that Hilbert-Schmidt operators provide a smoothing of the input data in the sense a square integrable function is mapped into a function that is smooth up to boundary of the domain. As main result 4, for the homogeneous nonlocal wave equation, we prove that continuity is preserved by time evolution. Namely, the solution is discontinuous if and only if the initial data is discontinuous. As a consequence, discontinuities remain stationary.

  10. Nonlocal effect in surface plasmon polariton of ultrathin metal films

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Hong-jie; Yu, Yabin, E-mail: apybyu@hnu.edu.cn; Wu, Reng-lai; Yu, Yan-qin; Wang, Ya-xin

    2015-09-01

    Using the nonlocal conductivity based on quantum response theory, we study the optical properties of p-polarized wave in quartz–metal–film–air structures, especially the influence of nonlocal effect on the surface plasmon polaritons (SPPs) resonance. In absorption spectrum, the resonant peak of SPP is found, and the dependence of the resonant peak on film thickness shows that nonlocal effect in the SPP resonance is enhanced significantly with the decrease of film-thickness, especially in the less than 20 nm metal film. We calculate the surface charge density as a function of frequency, and find that the frequencies at the charge and absorption peaks are the same. This clearly confirms that the absorption peak stems from SPP resonance excitation, and SPPs absorb the energy of the electromagnetic wave via charge oscillations. In the case of SPP resonance, the charge and electric field on the down-surface of thin film are always greater than that on the up-surface; however, the situation is just opposite in the case of no SPP resonance. This implies that the SPP resonance occurs near the down-surface of the film. Moreover, due to the nonlocal response of electric current to the electric field, the energy flow and electric current show anomalous oscillations, and with the increase of film thickness the anomalous oscillations exhibit obvious attenuation.

  11. Nonlocal response in thin-film waveguides: loss versus nonlocality and breaking of complementarity

    CERN Document Server

    Raza, Søren; Wubs, Martijn; Bozhevolnyi, Sergey I; Mortensen, N Asger

    2013-01-01

    We investigate the effects of nonlocal response on the surface-plasmon polariton guiding properties of the metal-insulator (MI), metal-insulator-metal (MIM), and insulator-metal-insulator (IMI) waveguides. The nonlocal effects are described by a linearized hydrodynamic model, which includes the Thomas-Fermi internal kinetic energy of the free electrons in the metal. We derive the nonlocal dispersion relations of the three waveguide structures taking into account also retardation and interband effects, and examine the delicate interplay between nonlocal response and absorption losses in the metal. We also show that nonlocality breaks the complementarity of the MIM and IMI waveguides found in the non-retarded limit.

  12. Non-locality in quantum field theory due to general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Calmet, Xavier; Croon, Djuna; Fritz, Christopher [University of Sussex, Physics and Astronomy, Brighton (United Kingdom)

    2015-12-15

    We show that general relativity coupled to a quantum field theory generically leads to non-local effects in the matter sector. These non-local effects can be described by non-local higher dimensional operators which remarkably have an approximate shift symmetry. When applied to inflationary models, our results imply that small non-Gaussianities are a generic feature of models based on general relativity coupled to matter fields. However, these effects are too small to be observable in the cosmic microwave background. (orig.)

  13. Nonlocal electron-phonon coupling: Consequences for the nature of polaron states

    Science.gov (United States)

    Stojanović, Vladimir M.; Bobbert, P. A.; Michels, M. A.

    2004-04-01

    We develop a variational approach to an extended Holstein model, comprising both local and nonlocal electron-phonon coupling. The approach is based on the minimization of a Bogoliubov bound to the Helmholtz free energy. The ambivalent character of nonlocal coupling, which both promotes and hinders transport, is clearly observed. Furthermore, a salient feature of our results is that the local and nonlocal couplings can compensate each other, leading to a reduction of polaronic effects and a quasi-free character of the excitation. Our findings have implications for organic crystals of π-conjugated molecules, where this electron-phonon coupling mechanism plays an important role.

  14. Nonlocal electron-phonon coupling: influence on the nature of polarons

    Science.gov (United States)

    Stojanovi, V. M.; Bobbert, P. A.; Michels, M. A. J.

    2004-01-01

    We present a variational approach to an extended Holstein model, comprising both local and nonlocal electron-phonon coupling. The approach is based on the minimization of a Bogoliubov bound to the free energy of the coupled electron-phonon system, and is implemented for a one-dimensional nearest-neighbor model, with Einstein phonons. The ambivalent character of nonlocal coupling, which both promotes and hinders transport, is clearly observed. A salient feature of our results is that the local and nonlocal couplings can compensate each other, leading to a supression of polaronic effects.

  15. Non-locality in quantum field theory due to general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Calmet, Xavier, E-mail: x.calmet@sussex.ac.uk; Croon, Djuna, E-mail: d.croon@sussex.ac.uk; Fritz, Christopher, E-mail: c.fritz@sussex.ac.uk [Physics and Astronomy, University of Sussex, Falmer, BN1 9QH, Brighton (United Kingdom)

    2015-12-19

    We show that general relativity coupled to a quantum field theory generically leads to non-local effects in the matter sector. These non-local effects can be described by non-local higher dimensional operators which remarkably have an approximate shift symmetry. When applied to inflationary models, our results imply that small non-Gaussianities are a generic feature of models based on general relativity coupled to matter fields. However, these effects are too small to be observable in the cosmic microwave background.

  16. On Bending of Bernoulli-Euler Nanobeams for Nonlocal Composite Materials

    Directory of Open Access Journals (Sweden)

    Luciano Feo

    2016-01-01

    Full Text Available Evaluation of size effects in functionally graded elastic nanobeams is carried out by making recourse to the nonlocal continuum mechanics. The Bernoulli-Euler kinematic assumption and the Eringen nonlocal constitutive law are assumed in the formulation of the elastic equilibrium problem. An innovative methodology, characterized by a lowering in the order of governing differential equation, is adopted in the present manuscript in order to solve the boundary value problem of a nanobeam under flexure. Unlike standard treatments, a second-order differential equation of nonlocal equilibrium elastic is integrated in terms of transverse displacements and equilibrated bending moments. Benchmark examples are developed, thus providing the nonlocality effect in nanocantilever and clampled-simply supported nanobeams for selected values of the Eringen scale parameter.

  17. Application of nonlocal models to nano beams. Part I: Axial length scale effect.

    Science.gov (United States)

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of physical implications via the similarity between a nonlocal Euler-Bernoulli (EB) beam theory and a classical Rankine-Timoshenko (RT) beam theory. The nonlocal EB beam model, Eringen's model, is briefly reviewed and the classical RT beam theory is recast by the primary variables of the EB model. A careful comparison of these two models reveals that the scale parameter used to the Eringen's model has a strike resemblance to the shear flexibility in the RT model. This implies that the nonlocal model employed in literature consider the axial length scale effect only. In addition, the paradox for a cantilevered nano-beam subjected to tip shear force is clearly explained by finding appropriate displacement prescribed boundary conditions.

  18. Image enlargement based on improved complex diffusion coupling to nonlocal means fitler%基于改进复扩散耦合非局部均值滤波器的图像放大

    Institute of Scientific and Technical Information of China (English)

    海涛; 席志红

    2016-01-01

    为了提高偏微分方程放大算法对纹理细节的放大效果,利用改进的复扩散模型耦合均值滤波器,提出了一种图像放大算法。改进的非线性复扩散模型能够很好的定位图像边缘,通过冲激滤波器对边缘进行锐化,同时耦合非局部均值滤波器,保持图像内部的自相似特性,利用非局部信息重建高分辨率图像,提高小边缘、细节放大效果。算法结合非局部信息和局部信息对图像进行放大,增强纹理细节,使图像更加自然,同时减弱对边缘的过度增强,具有较好的放大效果,仿真实验验证了算法的优良性能。%In order to improve the zoomed effect of the method based on partial differential equation,combi-ning the improved complex diffusion model and the nonlocal means filter,the image enlargement method is pro-posed.Having the advantage of precision location of the edges,with the edges sharpened by the shock filter, the improved anisotropic complex diffusion couples to the nonlocal means filter to keep with the similarity of the diffused image,the high resolution image is reconstructed.Not only using the local information of the image but the image’s nonlocal information,the method makes the zoomed image more natural,at the same time,attenu-ates the edge’s over-sharpen,therefore the enlarged image has better visual effective.The simulations prove the prominent performance of the proposed method.

  19. Fast and accurate implementation of Fourier spectral approximations of nonlocal diffusion operators and its applications

    Science.gov (United States)

    Du, Qiang; Yang, Jiang

    2017-03-01

    This work is concerned with the Fourier spectral approximation of various integral differential equations associated with some linear nonlocal diffusion and peridynamic operators under periodic boundary conditions. For radially symmetric kernels, the nonlocal operators under consideration are diagonalizable in the Fourier space so that the main computational challenge is on the accurate and fast evaluation of their eigenvalues or Fourier symbols consisting of possibly singular and highly oscillatory integrals. For a large class of fractional power-like kernels, we propose a new approach based on reformulating the Fourier symbols both as coefficients of a series expansion and solutions of some simple ODE models. We then propose a hybrid algorithm that utilizes both truncated series expansions and high order Runge-Kutta ODE solvers to provide fast evaluation of Fourier symbols in both one and higher dimensional spaces. It is shown that this hybrid algorithm is robust, efficient and accurate. As applications, we combine this hybrid spectral discretization in the spatial variables and the fourth-order exponential time differencing Runge-Kutta for temporal discretization to offer high order approximations of some nonlocal gradient dynamics including nonlocal Allen-Cahn equations, nonlocal Cahn-Hilliard equations, and nonlocal phase-field crystal models. Numerical results show the accuracy and effectiveness of the fully discrete scheme and illustrate some interesting phenomena associated with the nonlocal models.

  20. Fast and accurate implementation of Fourier spectral approximations of nonlocal diffusion operators and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Du, Qiang, E-mail: jyanghkbu@gmail.com; Yang, Jiang, E-mail: qd2125@columbia.edu

    2017-03-01

    This work is concerned with the Fourier spectral approximation of various integral differential equations associated with some linear nonlocal diffusion and peridynamic operators under periodic boundary conditions. For radially symmetric kernels, the nonlocal operators under consideration are diagonalizable in the Fourier space so that the main computational challenge is on the accurate and fast evaluation of their eigenvalues or Fourier symbols consisting of possibly singular and highly oscillatory integrals. For a large class of fractional power-like kernels, we propose a new approach based on reformulating the Fourier symbols both as coefficients of a series expansion and solutions of some simple ODE models. We then propose a hybrid algorithm that utilizes both truncated series expansions and high order Runge–Kutta ODE solvers to provide fast evaluation of Fourier symbols in both one and higher dimensional spaces. It is shown that this hybrid algorithm is robust, efficient and accurate. As applications, we combine this hybrid spectral discretization in the spatial variables and the fourth-order exponential time differencing Runge–Kutta for temporal discretization to offer high order approximations of some nonlocal gradient dynamics including nonlocal Allen–Cahn equations, nonlocal Cahn–Hilliard equations, and nonlocal phase-field crystal models. Numerical results show the accuracy and effectiveness of the fully discrete scheme and illustrate some interesting phenomena associated with the nonlocal models.

  1. A nonlocal shell model for mode transformation in single-walled carbon nanotubes.

    Science.gov (United States)

    Shi, M X; Li, Q M; Huang, Y

    2009-11-11

    A second-order strain gradient nonlocal shell model is established to study the mode transformation in single-walled carbon nanotubes (SWCNTs). Nonlocal length is calibrated carefully for SWCNTs in reference to molecular dynamics (MD) simulations through analysis of nonlocal length effects on the frequencies of the radial breathing mode (RBM) and circumferential flexural modes (CFMs) and its effects on mode transformation. All analyses show that only a negative second-order nonlocal shell model is appropriate to SWCNTs. Nonlocal length is evidently related to vibration modes and the radius-to-thickness ratio. It is found that a nonlocal length is approximately 0.1 nm in an average sense when RBM frequency is concerned. A nonlocal length of 0.122-0.259 nm is indicated for the mode transformation in a selected group of armchair SWCNTs. 2:1 and 1:1 internal resonances are found for the same SWCNT based on different models, which implies that the internal resonance mechanism depends on the model employed. Furthermore, it is shown that an effective thickness of approximately 0.1 nm is more appropriate to SWCNTs than 0.066 nm.

  2. A Fast Alternating Minimization Algorithm for Nonlocal Vectorial Total Variational Multichannel Image Denoising

    Directory of Open Access Journals (Sweden)

    Rubing Xi

    2014-01-01

    Full Text Available The variational models with nonlocal regularization offer superior image restoration quality over traditional method. But the processing speed remains a bottleneck due to the calculation quantity brought by the recent iterative algorithms. In this paper, a fast algorithm is proposed to restore the multichannel image in the presence of additive Gaussian noise by minimizing an energy function consisting of an l2-norm fidelity term and a nonlocal vectorial total variational regularization term. This algorithm is based on the variable splitting and penalty techniques in optimization. Following our previous work on the proof of the existence and the uniqueness of the solution of the model, we establish and prove the convergence properties of this algorithm, which are the finite convergence for some variables and the q-linear convergence for the rest. Experiments show that this model has a fabulous texture-preserving property in restoring color images. Both the theoretical derivation of the computation complexity analysis and the experimental results show that the proposed algorithm performs favorably in comparison to the widely used fixed point algorithm.

  3. Nonlocality of a single particle

    OpenAIRE

    Dunningham, Jacob; Vedral, Vlatko

    2007-01-01

    There has been a great deal of debate surrounding the issue of whether it is possible for a single photon to exhibit nonlocality. A number of schemes have been proposed that claim to demonstrate this effect, but each has been met with significant opposition. The objections hinge largely on the fact that these schemes use unobservable initial states and so, it is claimed, they do not represent experiments that could actually be performed. Here we show how it is possible to overcome these objec...

  4. Monotone method for nonlinear nonlocal hyperbolic problems

    Directory of Open Access Journals (Sweden)

    Azmy S. Ackleh

    2003-02-01

    Full Text Available We present recent results concerning the application of the monotone method for studying existence and uniqueness of solutions to general first-order nonlinear nonlocal hyperbolic problems. The limitations of comparison principles for such nonlocal problems are discussed. To overcome these limitations, we introduce new definitions for upper and lower solutions.

  5. Nonlocality as Evidence for a Multiverse Cosmology

    CERN Document Server

    Tipler, Frank J

    2010-01-01

    I show that observations of quantum nonlocality can be interpreted as purely local phenomena, provided one assumes that the cosmos is a multiverse. Conversely, the observation of quantum nonlocality can be interpreted as observation evidence for a multiverse cosmology, just as observation of the setting of the Sun can be interpreted as evidence for the Earth's rotation.

  6. Nonlocal study of ultimate plasmon hybridization

    DEFF Research Database (Denmark)

    Raza, Søren; Wubs, Martijn; Bozhevolnyi, Sergey I.

    2015-01-01

    Within our recently proposed generalized nonlocal optical response (GNOR) model, where nonlocal response is included by taking into account both convective and diffusive currents of the conduction electrons, we revisit the fundamental problem of an optically excited plasmonic dimer. We consider...

  7. Attraction of nonlocal dark optical solitons

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov; Neshev, Dragomir; Krolikowski, Wieslaw

    2004-01-01

    We study the formation and interaction of spatial dark optical solitons in materials with a nonlocal nonlinear response. We show that unlike in local materials, where dark solitons typically repel, the nonlocal nonlinearity leads to a long-range attraction and formation of stable bound states...... of dark solitons. (C) 2004 Optical Society of America...

  8. Multipole vector solitons in nonlocal nonlinear media.

    Science.gov (United States)

    Kartashov, Yaroslav V; Torner, Lluis; Vysloukh, Victor A; Mihalache, Dumitru

    2006-05-15

    We show that multipole solitons can be made stable via vectorial coupling in bulk nonlocal nonlinear media. Such vector solitons are composed of mutually incoherent nodeless and multipole components jointly inducing a nonlinear refractive index profile. We found that stabilization of the otherwise highly unstable multipoles occurs below certain maximum energy flow. Such a threshold is determined by the nonlocality degree.

  9. Creation of Entanglement with Nonlocal Operations

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; CAO Wan-Cang; LONG Gui-Lu

    2005-01-01

    We discuss how to create more entanglement with nonlocal operations acting on two-particle states. For a given nonlocal operation, we find that some input states cannot produce entanglement and some produce the maximal entanglement, and find that any initial entangled states can produce more entanglement than initial product states.

  10. Nonlocal and quasi-local field theories

    CERN Document Server

    Tomboulis, E T

    2015-01-01

    We investigate nonlocal field theories, a subject that has attracted some renewed interest in connection with nonlocal gravity models. We study, in particular, scalar theories of interacting delocalized fields, the delocalization being specified by nonlocal integral kernels. We distinguish between strictly nonlocal and quasi-local (compact support) kernels and impose conditions on them to insure UV finiteness and unitarity of amplitudes. We study the classical initial value problem for the partial integro-differential equations of motion in detail. We give rigorous proofs of the existence but accompanying loss of uniqueness of solutions due to the presence of future, as well as past, "delays," a manifestation of acausality. In the quantum theory we derive a generalization of the Bogoliubov causality condition equation for amplitudes, which explicitly exhibits the corrections due to nonlocality. One finds that, remarkably, for quasi-local kernels all acausal effects are confined within the compact support regi...

  11. Virial Theorem in Nonlocal Newtonian Gravity

    Directory of Open Access Journals (Sweden)

    Bahram Mashhoon

    2016-05-01

    Full Text Available Nonlocal gravity is the recent classical nonlocal generalization of Einstein’s theory of gravitation in which the past history of the gravitational field is taken into account. In this theory, nonlocality appears to simulate dark matter. The virial theorem for the Newtonian regime of nonlocal gravity theory is derived and its consequences for “isolated” astronomical systems in virial equilibrium at the present epoch are investigated. In particular, for a sufficiently isolated nearby galaxy in virial equilibrium, the galaxy’s baryonic diameter D 0 —namely, the diameter of the smallest sphere that completely surrounds the baryonic system at the present time—is predicted to be larger than the effective dark matter fraction f D M times a universal length that is the basic nonlocality length scale λ 0 ≈ 3 ± 2 kpc.

  12. Hyperbolic metamaterial lens with hydrodynamic nonlocal response

    DEFF Research Database (Denmark)

    Yan, Wei; Mortensen, N. Asger; Wubs, Martijn

    2013-01-01

    in the local-response approximation and in the hydrodynamic Drude model can differ considerably. In particular, the optimal frequency for imaging in the nonlocal theory is blueshifted with respect to that in the local theory. Thus, to detect whether nonlocal response is at work in a hyperbolic metamaterial, we......We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves...... of the free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens...

  13. Hyperbolic metamaterial lens with hydrodynamic nonlocal response.

    Science.gov (United States)

    Yan, Wei; Mortensen, N Asger; Wubs, Martijn

    2013-06-17

    We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves of the free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens in the local-response approximation and in the hydrodynamic Drude model can differ considerably. In particular, the optimal frequency for imaging in the nonlocal theory is blueshifted with respect to that in the local theory. Thus, to detect whether nonlocal response is at work in a hyperbolic metamaterial, we propose to measure the near-field distribution of a hyperbolic metamaterial lens.

  14. Nonlocal thermal transport in solar flares

    Science.gov (United States)

    Karpen, Judith T.; Devore, C. Richard

    1987-01-01

    A flaring solar atmosphere is modeled assuming classical thermal transport, locally limited thermal transport, and nonlocal thermal transport. The classical, local, and nonlocal expressions for the heat flux yield significantly different temperature, density, and velocity profiles throughout the rise phase of the flare. Evaporation of chromospheric material begins earlier in the nonlocal case than in the classical or local calculations, but reaches much lower upward velocities. Much higher coronal temperatures are achieved in the nonlocal calculations owing to the combined effects of delocalization and flux limiting. The peak velocity and momentum are roughly the same in all three cases. A more impulsive energy release influences the evolution of the nonlocal model more than the classical and locally limited cases.

  15. Virial Theorem in Nonlocal Newtonian Gravity

    CERN Document Server

    Mashhoon, B

    2015-01-01

    Nonlocal gravity is the recent classical nonlocal generalization of Einstein's theory of gravitation in which the past history of the gravitational field is taken into account. In this theory, nonlocality appears to simulate dark matter. The virial theorem for the Newtonian regime of nonlocal gravity theory is derived and its consequences for "isolated" astronomical systems in virial equilibrium at the present epoch are investigated. In particular, for a sufficiently isolated nearby galaxy in virial equilibrium, the galaxy's baryonic diameter---namely, the diameter of the smallest sphere that completely surrounds the baryonic system at the present time---is predicted to be larger than the effective dark matter fraction times a universal length that is the basic nonlocality length scale of about 3 kpc.

  16. Virial Theorem in Nonlocal Newtonian Gravity

    Science.gov (United States)

    Mashhoon, Bahram

    2016-05-01

    Nonlocal gravity is the recent classical nonlocal generalization of Einstein's theory of gravitation in which the past history of the gravitational field is taken into account. In this theory, nonlocality appears to simulate dark matter. The virial theorem for the Newtonian regime of nonlocal gravity theory is derived and its consequences for "isolated" astronomical systems in virial equilibrium at the present epoch are investigated. In particular, for a sufficiently isolated nearby galaxy in virial equilibrium, the galaxy's baryonic diameter---namely, the diameter of the smallest sphere that completely surrounds the baryonic system at the present time---is predicted to be larger than the effective dark matter fraction times a universal length that is the basic nonlocality length scale of about 3 kpc.

  17. Photonic multipartite entanglement conversion using nonlocal operations

    Science.gov (United States)

    Tashima, T.; Tame, M. S.; Özdemir, Ş. K.; Nori, F.; Koashi, M.; Weinfurter, H.

    2016-11-01

    We propose a simple setup for the conversion of multipartite entangled states in a quantum network with restricted access. The scheme uses nonlocal operations to enable the preparation of states that are inequivalent under local operations and classical communication, but most importantly does not require full access to the states. It is based on a flexible linear optical conversion gate that uses photons, which are ideally suited for distributed quantum computation and quantum communication in extended networks. In order to show the basic working principles of the gate, we focus on converting a four-qubit entangled cluster state to other locally inequivalent four-qubit states, such as the Greenberger-Horne-Zeilinger and symmetric Dicke states. We also show how the gate can be incorporated into extended graph state networks and can be used to generate variable entanglement and quantum correlations without entanglement but nonvanishing quantum discord.

  18. A quantum loophole to Bell nonlocality

    CERN Document Server

    Romero-Rochin, Victor

    2015-01-01

    We argue that the conclusion of Bell theorem, namely, that there must be spatial non-local correlations in certain experimental situations, does not apply to typical individual measurements performed on entangled EPR pairs. Our claim is based on three points, (i) on the notion of quantum {\\it complete measurements}; (ii) on Bell results on local yet distant measurements; and (iii) on the fact that perfect simultaneity is banned by the quantum mechanics. We show that quantum mechanics indicates that, while the measurements of the pair members are indeed space-like separated, the pair measurement is actually a sequence of two complete measurements, the first one terminating the entanglement and, therefore, the second one becoming unrelated to the initial preparation of the entangled pair. The outstanding feature of these measurements is that neither of them violates the principle of locality. We discuss that the present measurement viewpoint appears to run contrary to the usual interpretation of "superposition"...

  19. Construction of nonlocal multipartite quantum states

    Science.gov (United States)

    Zhang, Zhi-Chao; Zhang, Ke-Jia; Gao, Fei; Wen, Qiao-Yan; Oh, C. H.

    2017-05-01

    For general bipartite quantum systems, many sets of locally indistinguishable orthogonal product states have been constructed so far. Here, we first present a general method to construct multipartite orthogonal product states in d1⊗d2⊗⋯⊗dn(d1 ,2 ,⋯,n≥3 ,n ≥4 ) by using some locally indistinguishable bipartite orthogonal product states. And we prove that these multipartite orthogonal quantum states cannot be distinguished by local operations and classical communication. Furthermore, in d1⊗d2⊗⋯⊗dn(d1 ,2 ,⋯,n≥3 ,n ≥5 ) , we give a general method to construct a much smaller number of locally indistinguishable multipartite orthogonal product states for even and odd n separately. In addition, we also present a general method to construct complete orthogonal product bases for the multipartite quantum systems. Our results demonstrate the phenomenon of nonlocality without entanglement for the multipartite quantum systems.

  20. Projection-Based Image Restoration via Sparse Representation and Nonlocal Regularization%基于投影的稀疏表示与非局部正则化图像复原方法

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    提出一种基于投影的稀疏表示与非局部正则化相结合的图像去模糊、去噪图像复原方法。该方法结合了自适应构造字典的稀疏表示与非局部总变差,提出的正则化模型分解为三个投影子问题进行求解以提高求解效率。实验结果表明,本文所提出的图像复原方法能够有效地保持原图像的纹理细节信息,对于不同程度的退化图像上均有较好的复原结果,在视觉效果和客观评价指标上均优于相比较的现有方法。%This paper proposes a projection based sparse representation and nonlocal regularization deblurring and denoising image restoration algorithm .The algorithm combines sparse representation via adaptive learned dictionary and nonlocal total varia -tion ,and the proposed regularization model is divided into three projection sub problems to solve to improve the efficiency .Experi-mental results show that the proposed algorithm can preserve the detail information effectively ,and have nice restoration results for images with different degree of degradation .The proposed algorithm achieves improvement on both visual appearance and objective indices compared with state-of-the-art methods .

  1. Discrete Solitary Waves in Systems with Nonlocal Interactions and the Peierls-Nabarro Barrier

    Science.gov (United States)

    Jenkinson, M.; Weinstein, M. I.

    2017-04-01

    We study a class of discrete focusing nonlinear Schrödinger equations (DNLS) with general nonlocal interactions. We prove the existence of onsite and offsite discrete solitary waves, which bifurcate from the trivial solution at the endpoint frequency of the continuous spectrum of linear dispersive waves. We also prove exponential smallness, in the frequency-distance to the bifurcation point, of the Peierls-Nabarro energy barrier (PNB), as measured by the difference in Hamiltonian or mass functionals evaluated on the onsite and offsite states. These results extend those of the authors for the case of nearest neighbor interactions to a large class of nonlocal short-range and long-range interactions. The appearance of distinct onsite and offsite states is a consequence of the breaking of continuous spatial translation invariance. The PNB plays a role in the dynamics of energy transport in such nonlinear Hamiltonian lattice systems. Our class of nonlocal interactions is defined in terms of coupling coefficients, J m , where {min{Z}} is the lattice site index, with {J_m˜eq m^{-1-2s}, sin[1,∞)} and {J_m˜ e^{-γ|m|}, s=∞, γ > 0,} (Kac-Baker). For {s≥1}, the bifurcation is seeded by solutions of the (effective/homogenized) cubic focusing nonlinear Schrödinger equation (NLS). However, for {1/4 equation, FNLS, with {(-Δ)^s} replacing {-Δ}. The proof is based on a Lyapunov-Schmidt reduction strategy applied to a momentum space formulation. The PN barrier bounds require appropriate uniform decay estimates for the discrete Fourier transform of DNLS discrete solitary waves. A key role is also played by non-degeneracy of the ground state of FNLS, recently proved by Frank, Lenzmann and Silvestrie.

  2. Nonlocal Quantum Effects in Cosmology

    Directory of Open Access Journals (Sweden)

    Yurii V. Dumin

    2014-01-01

    Full Text Available Since it is commonly believed that the observed large-scale structure of the universe is an imprint of quantum fluctuations existing at the very early stage of its evolution, it is reasonable to pose the question: do the effects of quantum nonlocality, which are well established now by the laboratory studies, manifest themselves also in the early universe? We try to answer this question by utilizing the results of a few experiments, namely, with the superconducting multi-Josephson-junction loops and the ultracold gases in periodic potentials. Employing a close analogy between the above-mentioned setups and the simplest one-dimensional Friedmann-Robertson-Walker cosmological model, we show that the specific nonlocal correlations revealed in the laboratory studies might be of considerable importance also in treating the strongly nonequilibrium phase transitions of Higgs fields in the early universe. Particularly, they should substantially reduce the number of topological defects (e.g., domain walls expected due to independent establishment of the new phases in the remote spatial regions. This gives us a hint on resolving a long-standing problem of the excessive concentration of topological defects, inconsistent with observational constraints. The same effect may be also relevant to the recent problem of the anomalous behavior of cosmic microwave background fluctuations at large angular scales.

  3. Dynamics of atoms in strong laser fields I: A quasi analytical model in momentum space based on a Sturmian expansion of the interacting nonlocal Coulomb potential

    Energy Technology Data Exchange (ETDEWEB)

    Ongonwou, F., E-mail: fred.ongonwou@gmail.com [Département de Physique, Faculté des Sciences, Université des Sciences et Techniques de Masuku, B.P. 943 Franceville (Gabon); Tetchou Nganso, H.M., E-mail: htetchou@yahoo.com [Atoms and Molecules Laboratory, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, University of Douala, P.O. Box 8580, Douala (Cameroon); Ekogo, T.B., E-mail: tekogo@yahoo.fr [Département de Physique, Faculté des Sciences, Université des Sciences et Techniques de Masuku, B.P. 943 Franceville (Gabon); Kwato Njock, M.G., E-mail: mkwato@yahoo.com [Atoms and Molecules Laboratory, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, University of Douala, P.O. Box 8580, Douala (Cameroon)

    2016-12-15

    In this study we present a model that we have formulated in the momentum space to describe atoms interacting with intense laser fields. As a further step, it follows our recent theoretical approach in which the kernel of the reciprocal-space time-dependent Schrödinger equation (TDSE) is replaced by a finite sum of separable potentials, each of them supporting one bound state of atomic hydrogen (Tetchou Nganso et al. 2013). The key point of the model is that the nonlocal interacting Coulomb potential is expanded in a Coulomb Sturmian basis set derived itself from a Sturmian representation of Bessel functions of the first kind in the position space. As a result, this decomposition allows a simple spectral treatment of the TDSE in the momentum space. In order to illustrate the credibility of the model, we have considered the test case of atomic hydrogen driven by a linearly polarized laser pulse, and have evaluated analytically matrix elements of the atomic Hamiltonian and dipole coupling interaction. For various regimes of the laser parameters used in computations our results are in very good agreement with data obtained from other time-dependent calculations.

  4. The neglected nonlocal effects of deforestation

    Science.gov (United States)

    Winckler, Johannes; Reick, Christian; Pongratz, Julia

    2017-04-01

    Deforestation changes surface temperature locally via biogeophysical effects by changing the water, energy and momentum balance. Adding to these locally induced changes (local effects), deforestation at a given location can cause changes in temperature elsewhere (nonlocal effects). Most previous studies have not considered local and nonlocal effects separately, but investigated the total (local plus nonlocal) effects, for which global deforestation was found to cause a global mean cooling. Recent modeling and observational studies focused on the isolated local effects: The local effects are relevant for local living conditions, and they can be obtained from in-situ and satellite observations. Observational studies suggest that the local effects of potential deforestation cause a warming when averaged globally. This contrast between local warming and total cooling indicates that the nonlocal effects of deforestation are causing a cooling and thus counteract the local effects. It is still unclear how the nonlocal effects depend on the spatial scale of deforestation, and whether they still compensate the local warming in a more realistic spatial distribution of deforestation. To investigate this, we use a fully coupled climate model and separate local and nonlocal effects of deforestation in three steps: Starting from a forest world, we simulate deforestation in one out of four grid boxes using a regular spatial pattern and increase the number of deforestation grid boxes step-wise up to three out of four boxes in subsequent simulations. To compare these idealized spatial distributions of deforestation to a more realistic case, we separate local and nonlocal effects in a simulation where deforestation is applied in regions where it occurred historically. We find that the nonlocal effects scale nearly linearly with the number of deforested grid boxes, and the spatial distribution of the nonlocal effects is similar for the regular spatial distribution of deforestation

  5. Aspects of Nonlocality in Quantum Field Theory, Quantum Gravity and Cosmology

    OpenAIRE

    Barvinsky, A. O.

    2014-01-01

    This paper contains a collection of essays on nonlocal phenomena in quantum field theory, gravity and cosmology. Mechanisms of nonlocal contributions to the quantum effective action are discussed within the covariant perturbation expansion in field strengths and spacetime curvatures and the nonperturbative method based on the late time asymptotics of the heat kernel. Euclidean version of the Schwinger-Keldysh technique for quantum expectation values is presented as a special rule of obtaining...

  6. An adaptive nonlocal means scheme for medical image denoising

    Science.gov (United States)

    Thaipanich, Tanaphol; Kuo, C.-C. Jay

    2010-03-01

    Medical images often consist of low-contrast objects corrupted by random noise arising in the image acquisition process. Thus, image denoising is one of the fundamental tasks required by medical imaging analysis. In this work, we investigate an adaptive denoising scheme based on the nonlocal (NL)-means algorithm for medical imaging applications. In contrast with the traditional NL-means algorithm, the proposed adaptive NL-means (ANL-means) denoising scheme has three unique features. First, it employs the singular value decomposition (SVD) method and the K-means clustering (K-means) technique for robust classification of blocks in noisy images. Second, the local window is adaptively adjusted to match the local property of a block. Finally, a rotated block matching algorithm is adopted for better similarity matching. Experimental results from both additive white Gaussian noise (AWGN) and Rician noise are given to demonstrate the superior performance of the proposed ANL denoising technique over various image denoising benchmarks in term of both PSNR and perceptual quality comparison.

  7. Finite element analysis of nano-scale Timoshenko beams using the integral model of nonlocal elasticity

    Science.gov (United States)

    Norouzzadeh, A.; Ansari, R.

    2017-04-01

    Stress-strain relation in Eringen's nonlocal elasticity theory was originally formulated within the framework of an integral model. Due to difficulty of working with that integral model, the differential model of nonlocal constitutive equation is widely used for nanostructures. However, paradoxical results may be obtained by the differential model for some boundary and loading conditions. Presented in this article is a finite element analysis of Timoshenko nano-beams based on the integral model of nonlocal continuum theory without employing any simplification in the model. The entire procedure of deriving equations of motion is carried out in the matrix form of representation, and hence, they can be easily used in the finite element analysis. For comparison purpose, the differential counterparts of equations are also derived. To study the outcome of analysis based on the integral and differential models, some case studies are presented in which the influences of boundary conditions, nonlocal length scale parameter and loading factor are analyzed. It is concluded that, in contrast to the differential model, there is no paradox in the numerical results of developed integral model of nonlocal continuum theory for different situations of problem characteristics. So, resolving the mentioned paradoxes by means of a purely numerical approach based on the original integral form of nonlocal elasticity theory is the major contribution of present study.

  8. Flaw-tolerance of nonlocal discrete systems and interpretation according to network theory

    Directory of Open Access Journals (Sweden)

    A. Infuso

    2014-07-01

    Full Text Available Discrete systems are modeled as a network of nodes (particles, molecules, or atoms linked by nonlinear springs to simulate the action of van der Waals forces. Such systems are nonlocal if links connecting non-adjacent nodes are introduced. For their topological characterization, a nonlocality index (NLI inspired by network theory is proposed. The mechanical response of 1D and 2D nonlocal discrete systems is predicted according to finite element (FE simulations based on a nonlinear spring element for large displacements implemented in the FE programme FEAP. Uniaxial force-displacement responses of intact and defective systems (with links or nodes removed are numerically simulated. Strain localization phenomena, size-scale effects and the ability to tolerate defects are investigated by varying the degree of nonlocality.

  9. Continuous Time Random Walks for Non-Local Radial Solute Transport

    CERN Document Server

    Dentz, Marco; Borgne, Tanguy le

    2016-01-01

    This paper derives and analyzes continuous time random walk (CTRW) models in radial flow geometries for the quantification of non-local solute transport induced by heterogeneous flow distributions and by mobile-immobile mass transfer processes. To this end we derive a general CTRW framework in radial coordinates starting from the random walk equations for radial particle positions and times. The particle density, or solute concentration is governed by a non-local radial advection-dispersion equation (ADE). Unlike in CTRWs for uniform flow scenarios, particle transition times here depend on the radial particle position, which renders the CTRW non-stationary. As a consequence, the memory kernel characterizing the non-local ADE, is radially dependent. Based on this general formulation, we derive radial CTRW implementations that (i) emulate non-local radial transport due to heterogeneous advection, (ii) model multirate mass transfer (MRMT) between mobile and immobile continua, and (iii) quantify both heterogeneou...

  10. Can EPR non-locality be geometrical?

    Energy Technology Data Exchange (ETDEWEB)

    Ne`eman, Y. [Tel-Aviv Univ. (Israel). Raymond and Beverly Sackler Faculty of Exact Sciences]|[Univ. of Texas, Austin, TX (United States). Center for Particle Physics; Botero, A. [Texas Univ., Austin, TX (United States)

    1995-10-01

    The presence in Quantum Mechanics of non-local correlations is one of the two fundamentally non-intuitive features of that theory. The non-local correlations themselves fall into two classes: EPR and Geometrical. The non-local characteristics of the geometrical type are well-understood and are not suspected of possibly generating acausal features, such as faster-than-light propagation of information. This has especially become true since the emergence of a geometrical treatment for the relevant gauge theories, i.e. Fiber Bundle geometry, in which the quantum non-localities are seen to correspond to pure homotopy considerations. This aspect is reviewed in section 2. Contrary-wise, from its very conception, the EPR situation was felt to be paradoxical. It has been suggested that the non-local features of EPR might also derive from geometrical considerations, like all other non-local characteristics of QM. In[7], one of the authors was able to point out several plausibility arguments for this thesis, emphasizing in particular similarities between the non-local correlations provided by any gauge field theory and those required by the preservation of the quantum numbers of the original EPR state-vector, throughout its spatially-extended mode. The derivation was, however, somewhat incomplete, especially because of the apparent difference between, on the one hand, the closed spatial loops arising in the analysis of the geometrical non-localities, from Aharonov-Bohm and Berry phases to magnetic monopoles and instantons, and on the other hand, in the EPR case, the open line drawn by the positions of the two moving decay products of the disintegrating particle. In what follows, the authors endeavor to remove this obstacle and show that as in all other QM non-localities, EPR is somehow related to closed loops, almost involving homotopy considerations. They develop this view in section 3.

  11. Local, nonlocal quantumness and information theoretic measures

    Science.gov (United States)

    Agrawal, Pankaj; Sazim, Sk; Chakrabarty, Indranil; Pati, Arun K.

    2016-08-01

    It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by information theoretic quantities such as quantum discord, but not by the conventional measures of entanglement. We argue that a state displays quantumness, that can be of local and nonlocal origin. Information theoretic measures not only characterize the nonlocal quantumness, but also the local quantumness, such as the “local superposition”. This can be a reason, why such measures are nonzero, when there is no entanglement. We consider a generalized version of the Werner state to demonstrate the interplay of local quantumness, nonlocal quantumness and classical mixedness of a state.

  12. Nonlocal study of ultimate plasmon hybridization.

    Science.gov (United States)

    Raza, Søren; Wubs, Martijn; Bozhevolnyi, Sergey I; Mortensen, N Asger

    2015-03-01

    Within our recently proposed generalized nonlocal optical response (GNOR) model, where nonlocal response is included by taking into account both convective and diffusive currents of the conduction electrons, we revisit the fundamental problem of an optically excited plasmonic dimer. We consider the transition from separated dimers via touching dimers to finally overlapping dimers. In particular, we focus on the touching case, showing a fundamental limit on the hybridization of the bonding plasmon modes due to nonlocality. Using transformation optics, we determine a simple analytical equation for the resonance energies.

  13. Film edge nonlocal spin valves.

    Science.gov (United States)

    McCallum, Andrew T; Johnson, Mark

    2009-06-01

    Spintronics is a new paradigm for integrated digital electronics. Recently established as a niche for nonvolatile magnetic random access memory (MRAM), it offers new functionality while demonstrating low-power and high-speed performance. However, to reach high density spintronic technology must make a transition to the nanometer scale. Prototype devices are presently made using a planar geometry and have an area determined by the lithographic feature size, currently about 100 nm. Here we present a new nonplanar geometry in which one lateral dimension is given by a film thickness, on the order of 10 nm. With this new approach, cell sizes can shrink by an order of magnitude. The geometry is demonstrated with a nonlocal spin valve, where we study devices with an injector/detector separation much less than the spin diffusion length.

  14. Experimental many-pairs nonlocality

    Science.gov (United States)

    Poh, Hou Shun; Cerè, Alessandro; Bancal, Jean-Daniel; Cai, Yu; Sangouard, Nicolas; Scarani, Valerio; Kurtsiefer, Christian

    2017-08-01

    Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the Clauser-Horne-Shimony-Holt Bell inequality. In the presence of many entangled pairs, this violation decreases quickly with the number of pairs and vanishes for some critical pair number that is a function of the noise present in the system. Here we show that a different binning strategy can lead to a more substantial Bell violation when the noise is sufficiently small. Given the relation between the critical pair number and the source noise, we then present an experiment where the critical pair number is used to quantify the quality of a high visibility photon pair source. Our results demonstrate nonlocal correlations using collective measurements operating on clusters of more than 40 photon pairs.

  15. Nonlocal response in thin-film waveguides: Loss versus nonlocality and breaking of complementarity

    DEFF Research Database (Denmark)

    Raza, Søren; Christensen, Thomas; Wubs, Martijn

    2013-01-01

    We investigate the effects of nonlocal response on the surface-plasmon polariton guiding properties of the metal-insulator (MI), metal-insulator-metal (MIM), and insulator-metal-insulator (IMI) waveguides. The nonlocal effects are described by a linearized hydrodynamic model, which includes...... in the metal. We also show that nonlocality breaks the complementarity of the MIM and IMI waveguides found in the nonretarded limit....

  16. The averaging of nonlocal Hamiltonian structures in Whitham's method

    Directory of Open Access Journals (Sweden)

    Andrei Ya. Maltsev

    2002-01-01

    Full Text Available We consider the m-phase Whitham's averaging method and propose the procedure of “averaging” nonlocal Hamiltonian structures. The procedure is based on the existence of a sufficient number of local-commuting integrals of the system and gives the Poisson bracket of Ferapontov type for Whitham's system. The method can be considered as the generalization of the Dubrovin-Novikov procedure for the local field-theoretical brackets.

  17. Asymptotic behaviour for a diffusion equation governed by nonlocal interactions

    CERN Document Server

    Ovono, Armel Andami

    2010-01-01

    In this paper we study the asymptotic behaviour of a nonlocal nonlinear parabolic equation governed by a parameter. After giving the existence of unique branch of solutions composed by stable solutions in stationary case, we gives for the parabolic problem $L^\\infty $ estimates of solution based on using the Moser iterations and existence of global attractor. We finish our study by the issue of asymptotic behaviour in some cases when $t\\to \\infty$.

  18. Stability Analysis of Nonlocal Elastic Columns with Initial Imperfection

    Directory of Open Access Journals (Sweden)

    S. P. Xu

    2013-01-01

    Full Text Available Investigated herein is the postbuckling behavior of an initially imperfect nonlocal elastic column, which is simply supported at one end and subjected to an axial force at the other movable end. The governing nonlinear differential equation of the axially loaded nonlocal elastic column experiencing large deflection is first established within the framework of Eringen's nonlocal elasticity theory in order to embrace the size effect. Its semianalytical solutions by the virtue of homotopy perturbation method, as well as the successive approximation algorithm, are determined in an explicit form, through which the postbuckling equilibrium loads in terms of the end rotation angle and the deformed configuration of the column at this end rotation are predicted. By comparing the degenerated results with the exact solutions available in the literature, the validity and accuracy of the proposed methods are numerically substantiated. The size effect, as well as the initial imperfection, on the buckled configuration and the postbuckling equilibrium path is also thoroughly discussed through parametric studies.

  19. Spherical systems in models of nonlocally corrected gravity

    CERN Document Server

    Bronnikov, K A

    2009-01-01

    The properties of static, spherically symmetric configurations are considered in the framework of two models of nonlocally corrected gravity, suggested in S. Deser and R. Woodard., Phys. Rev. Lett. 663, 111301 (2007), and S. Capozziello et al., Phys. Lett. B 671, 193 (2009). For the first case, where the Lagrangian of nonlocal origin represents a scalar-tensor theory with two massless scalars, an explicit condition is found under which both scalars are canonical (non-phantom). If this condition does not hold, one of the fields exhibits a phantom behavior. Scalar-vacuum configurations then behave in a manner known for scalar-tensor theories. In the second case, the Lagrangian of nonlocal origin exhibits a scalar field interacting with the Gauss-Bonnet (GB) invariant and contains an arbitrary scalar field potential. It is found that the GB term, in general, leads to violation of the well-known no-go theorems valid for minimally coupled scalar fields in general relativity. It is shown, however, that some configu...

  20. Nonlocal wave turbulence in non-Abelian plasmas

    CERN Document Server

    Mehtar-Tani, Yacine

    2016-01-01

    We investigate driven wave turbulence in non-Abelian plasmas, in the framework of kinetic theory where both elastic and inelastic processes are considered in the small angle approximation. The gluon spectrum, that forms in the presence of a steady source, is shown to be controlled by nonlocal interactions in momentum space, in contrast to the universal Kolmogorov-Zakharov spectra. Assuming strongly nonlocal interactions, we show that inelastic processes are dominant in the IR and cause a thermal bath to form below the forcing scale, as a result of a detailed balance between radiation and absorption of soft gluons by the hard ones. Above the forcing scale, the inelastic collision term reduces to an inhomogeneous diffusion-like equation yielding a spectrum that spreads to the UV as $t^{1/2}$, similarly to elastic processes. Due to nonlocal interactions the non-universal turbulent spectrum is not steady and flattens when time goes on toward the thermal distribution. This analysis is complemented by numerical sim...

  1. Document Clustering Based on Semi-Supervised Term Clustering

    Directory of Open Access Journals (Sweden)

    Hamid Mahmoodi

    2012-05-01

    Full Text Available The study is conducted to propose a multi-step feature (term selection process and in semi-supervised fashion, provide initial centers for term clusters. Then utilize the fuzzy c-means (FCM clustering algorithm for clustering terms. Finally assign each of documents to closest associated term clusters. While most text clustering algorithms directly use documents for clustering, we propose to first group the terms using FCM algorithm and then cluster documents based on terms clusters. We evaluate effectiveness of our technique on several standard text collections and compare our results with the some classical text clustering algorithms.

  2. Some generalizations of the nonlocal transformations approach

    Directory of Open Access Journals (Sweden)

    V. A. Tychynin

    2015-02-01

    Full Text Available Some generalizations of a method of nonlocal transformations are proposed: a con­nection of given equations via prolonged nonlocal transformations and finding of an adjoint solution to the solutions of initial equation are considered. A concept of nonlocal transformation with additional variables is introduced, developed and used for searching symmetries of differential equations. A problem of inversion of the nonlocal transforma­tion with additional variables is investigated and in some cases solved. Several examples are presented. Derived technique is applied for construction of the algorithms and for­mulae of generation of solutions. The formulae derived are used for construction of exact solutions of some nonlinear equations.

  3. Dispersive shock waves with nonlocal nonlinearity

    CERN Document Server

    Barsi, Christopher; Sun, Can; Fleischer, Jason W

    2007-01-01

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  4. Dispersive shock waves with nonlocal nonlinearity.

    Science.gov (United States)

    Barsi, Christopher; Wan, Wenjie; Sun, Can; Fleischer, Jason W

    2007-10-15

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  5. Employee Travel Data (Non-Local)

    Data.gov (United States)

    Montgomery County of Maryland — ‘This dataset provides information regarding the total approved actual expenses incurred by Montgomery County government employees traveling non-locally (over 75...

  6. Wave propagation in nanostructures nonlocal continuum mechanics formulations

    CERN Document Server

    Gopalakrishnan, Srinivasan

    2013-01-01

    Wave Propagation in Nanostructures describes the fundamental and advanced concepts of waves propagating in structures that have dimensions of the order of nanometers. The book is fundamentally based on non-local elasticity theory, which includes scale effects in the continuum model. The book predominantly addresses wave behavior in carbon nanotubes and graphene structures, although the methods of analysis provided in this text are equally applicable to other nanostructures. The book takes the reader from the fundamentals of wave propagation in nanotubes to more advanced topics such as rotating nanotubes, coupled nanotubes, and nanotubes with magnetic field and surface effects. The first few chapters cover the basics of wave propagation, different modeling schemes for nanostructures and introduce non-local elasticity theories, which form the building blocks for understanding the material provided in later chapters. A number of interesting examples are provided to illustrate the important features of wave behav...

  7. Symmetry reduction related with nonlocal symmetry for Gardner equation

    Science.gov (United States)

    Ren, Bo

    2017-01-01

    Based on the truncated Painlevé method or the Möbious (conformal) invariant form, the nonlocal symmetry for the (1+1)-dimensional Gardner equation is derived. The nonlocal symmetry can be localized to the Lie point symmetry by introducing one new dependent variable. Thanks to the localization procedure, the finite symmetry transformations are obtained by solving the initial value problem of the prolonged systems. Furthermore, by using the symmetry reduction method to the enlarged systems, many explicit interaction solutions among different types of solutions such as solitary waves, rational solutions, Painlevé II solutions are given. Especially, some special concrete soliton-cnoidal interaction solutions are analyzed both in analytical and graphical ways.

  8. On the compatible weakly nonlocal Poisson brackets of hydrodynamic type

    Directory of Open Access Journals (Sweden)

    Andrei Ya. Maltsev

    2002-01-01

    of hydrodynamic type (Ferapontov brackets and the corresponding integrable hierarchies. We show that, under the requirement of the nondegeneracy of the corresponding “first” pseudo-Riemannian metric g(0 νμ and also some nondegeneracy requirement for the nonlocal part, it is possible to introduce a “canonical” set of “integrable hierarchies” based on the Casimirs, momentum functional and some “canonical Hamiltonian functions.” We prove also that all the “higher” “positive” Hamiltonian operators and the “negative” symplectic forms have the weakly nonlocal form in this case. The same result is also true for “negative” Hamiltonian operators and “positive” symplectic structures in the case when both pseudo-Riemannian metrics g(0 νμ and g(1 νμ are nondegenerate.

  9. Entropic Tests of Multipartite Nonlocality and State-Independent Contextuality

    Science.gov (United States)

    Raeisi, Sadegh; Kurzyński, Paweł; Kaszlikowski, Dagomir

    2015-05-01

    We introduce a multipartite extension of an information-theoretic distance introduced by Zurek [Nature (London) 341, 119 (1989)]. We use it to develop a new tool for studying quantum correlations from an information-theoretic perspective. In particular, we derive entropic tests of multipartite nonlocality for three qubits and for an arbitrary even number of qubits as well as a test of state-independent contextuality. In addition, we rederive the tripartite Mermin inequality and a state-independent noncontextuality inequality by Cabello [Phys. Rev. Lett. 101, 210401 (2008)]. This suggests that the information-theoretic distance approach to multipartite nonlocality and state-independent contextuality can provide a more general treatment of nonclassical correlations than the orthodox approach based on correlation functions.

  10. Symmetric states: Their nonlocality and entanglement

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zizhu; Markham, Damian [CNRS LTCI, Département Informatique et Réseaux, Telecom ParisTech, 23 avenue d' Italie, CS 51327, 75214 Paris CEDEX 13 (France)

    2014-12-04

    The nonlocality of permutation symmetric states of qubits is shown via an extension of the Hardy paradox and the extension of the associated inequality. This is achieved by using the Majorana representation, which is also a powerful tool in the study of entanglement properties of symmetric states. Through the Majorana representation, different nonlocal properties can be linked to different entanglement properties of a state, which is useful in determining the usefulness of different states in different quantum information processing tasks.

  11. On a Nonlocal Damping Model in Ferromagnetism

    Directory of Open Access Journals (Sweden)

    M. Moumni

    2015-01-01

    Full Text Available We consider a mathematical model describing nonlocal damping in magnetization dynamics. The model consists of a modified form of the Landau-Lifshitz-Gilbert (LLG equation for the evolution of the magnetization vector in a rigid ferromagnet. We give a global existence result and characterize the long time behaviour of the obtained solutions. The sensitivity of the model with respect to large and small nonlocal damping parameters is also discussed.

  12. Quantum theory of nonlocal nonlinear Schrodinger equation

    CERN Document Server

    Vyas, Vivek M

    2015-01-01

    Nonlocal nonlinear Schrodinger model is quantised and exactly solved using the canonical framework. It is found that the usual canonical quantisation of the model leads to a theory with pathological inner product. This problem is resolved by constructing another inner product over the vector space of the theory. The resultant theory is found to be identical to that of nonrelativistic bosons with delta function interaction potential, devoid of any nonlocality. The exact eigenstates are found using the Bethe ansatz technique.

  13. Analysis of Sigmoid Functionally Graded Material (S-FGM Nanoscale Plates Using the Nonlocal Elasticity Theory

    Directory of Open Access Journals (Sweden)

    Woo-Young Jung

    2013-01-01

    Full Text Available Based on a nonlocal elasticity theory, a model for sigmoid functionally graded material (S-FGM nanoscale plate with first-order shear deformation is studied. The material properties of S-FGM nanoscale plate are assumed to vary according to sigmoid function (two power law distribution of the volume fraction of the constituents. Elastic theory of the sigmoid FGM (S-FGM nanoscale plate is reformulated using the nonlocal differential constitutive relations of Eringen and first-order shear deformation theory. The equations of motion of the nonlocal theories are derived using Hamilton’s principle. The nonlocal elasticity of Eringen has the ability to capture the small scale effect. The solutions of S-FGM nanoscale plate are presented to illustrate the effect of nonlocal theory on bending and vibration response of the S-FGM nanoscale plates. The effects of nonlocal parameters, power law index, aspect ratio, elastic modulus ratio, side-to-thickness ratio, and loading type on bending and vibration response are investigated. Results of the present theory show a good agreement with the reference solutions. These results can be used for evaluating the reliability of size-dependent S-FGM nanoscale plate models developed in the future.

  14. Dynamics between the fishbone instability and nonlocal transient transport in HL-2A NBI plasmas

    Science.gov (United States)

    Chen, W.; Xu, Y.; Ding, X. T.; Shi, Z. B.; Jiang, M.; Zhong, W. L.; Ji, X. Q.; HL-2A Team

    2016-04-01

    Understanding of nonlocal electron heat transport is of key importance for current magnetic confinement fusion research. Global nonlocal response presents a fundamental challenge to the standard anomalous transport model based on local microinstabilities and turbulence. Here, we present for the first time a new nonlocal phenomenon triggered by the fishbone instability in HL-2A neutral beam injection plasmas. Rapid core heating leads to a simultaneous decrease in temperature at the plasma edge. The effect reveals fast anomalous transport of core heat pulses to the plasma edge, not compatible with diffusive time scales. More importantly, Δ {{T}\\text{e}}/text{e}}> variations at different locations are restricted by the intensity of magnetic fluctuations. The Δ {{T}\\text{e}}/text{e}}> and {{≤ft(δ {{B}θ}\\right)}\\text{rms}} form two types of hysteresis loops at two sides of the inversion radius. The ECEIs show that the 2D mode structure of the fishbone is intensive shearing/spiraling during the nonlocal transport. Experimental results suggest that magnetic perturbation, long-range correlation, mesoscale structure and E× B flow play crucial roles in the nonlocal response. The Hurst exponent and auto-correlation coefficient indicate that the nonlocal transport is potentially linked to the self-organized critical (SOC) dynamics. This work will be beneficial for understanding of the plasma dynamics in future fusion reactors.

  15. Critical thresholds in flocking hydrodynamics with non-local alignment.

    Science.gov (United States)

    Tadmor, Eitan; Tan, Changhui

    2014-11-13

    We study the large-time behaviour of Eulerian systems augmented with non-local alignment. Such systems arise as hydrodynamic descriptions of agent-based models for self-organized dynamics, e.g. Cucker & Smale (2007 IEEE Trans. Autom. Control 52, 852-862. (doi:10.1109/TAC.2007.895842)) and Motsch & Tadmor (2011 J. Stat. Phys. 144, 923-947. (doi:10.1007/s10955-011-0285-9)) models. We prove that, in analogy with the agent-based models, the presence of non-local alignment enforces strong solutions to self-organize into a macroscopic flock. This then raises the question of existence of such strong solutions. We address this question in one- and two-dimensional set-ups, proving global regularity for subcritical initial data. Indeed, we show that there exist critical thresholds in the phase space of the initial configuration which dictate the global regularity versus a finite-time blow-up. In particular, we explore the regularity of non-local alignment in the presence of vacuum.

  16. Robust non-local median filter

    Science.gov (United States)

    Matsuoka, Jyohei; Koga, Takanori; Suetake, Noriaki; Uchino, Eiji

    2017-04-01

    This paper describes a novel image filter with superior performance on detail-preserving removal of random-valued impulse noise superimposed on natural gray-scale images. The non-local means filter is in the limelight as a way of Gaussian noise removal with superior performance on detail preservation. By referring the fundamental concept of the non-local means, we had proposed a non-local median filter as a specialized way for random-valued impulse noise removal so far. In the non-local processing, the output of a filter is calculated from pixels in blocks which are similar to the block centered at a pixel of interest. As a result, aggressive noise removal is conducted without destroying the detailed structures in an original image. However, the performance of non-local processing decreases enormously in the case of high noise occurrence probability. A cause of this problem is that the superimposed noise disturbs accurate calculation of the similarity between the blocks. To cope with this problem, we propose an improved non-local median filter which is robust to the high level of corruption by introducing a new similarity measure considering possibility of being the original signal. The effectiveness and validity of the proposed method are verified in a series of experiments using natural gray-scale images.

  17. Effects of Nonlocality on Transfer Reactions

    CERN Document Server

    Titus, Luke J

    2016-01-01

    We solved the nonlocal scattering and bound state equations using the Perey-Buck type interaction, and compared to local equivalent calculations. Using the distorted wave Born approximation we construct the T-matrix for (p,d) transfer on 17O, 41Ca, 49Ca, 127Sn, 133Sn, and 209Pb at 20 and 50 MeV. Additionally we studied (p,d) reactions on 40Ca using the the nonlocal dispersive optical model. We have also included nonlocality consistently into the adiabatic distorted wave approximation and have investigated the effects of nonlocality on on (d,p) transfer reactions for deuterons impinged on 16O, 40Ca, 48Ca, 126Sn, 132Sn, 208Pb at 10, 20, and 50 MeV. We found that for bound states the Perry corrected wave functions resulting from the local equation agreed well with that from the nonlocal equation in the interior region, but discrepancies were found in the surface and peripheral regions. Overall, the Perey correction factor was adequate for scattering states, with the exception for a few partial waves. Nonlocality...

  18. Moving nonradiating kinks in nonlocal φ4 and φ4-φ6 models.

    Science.gov (United States)

    Alfimov, G L; Medvedeva, E V

    2011-11-01

    We explore the existence of moving nonradiating kinks in nonlocal generalizations of φ(4) and φ(4)-φ(6) models. These models are described by nonlocal nonlinear Klein-Gordon equation, u(tt)-Lu+F(u)=0, where L is a Fourier multiplier operator of a specific form and F(u) includes either just a cubic term (φ(4) case) or cubic and quintic (φ(4)-φ(6) case) terms. The general mechanism responsible for the discretization of kink velocities in the nonlocal model is discussed. We report numerical results obtained for these models. It is shown that, contrary to the traditional φ(4) model, the nonlocal φ(4) model does not admit moving nonradiating kinks but admits solitary waves that do not exist in the local model. At the same time the nonlocal φ(4)-φ(6) model describes moving nonradiating kinks. The set of velocities allowed for these kinks is discrete with the highest possible velocity c(1). This set of velocities is unambiguously determined by the parameters of the model. Numerical simulations show that a kink launched at the velocity c higher than c(1) starts to decelerate, and its velocity settles down to the highest value of the discrete spectrum c(1).

  19. Iterative reconstruction for dual energy CT with an average image-induced nonlocal means regularization

    Science.gov (United States)

    Zhang, Houjin; Zeng, Dong; Lin, Jiahui; Zhang, Hao; Bian, Zhaoying; Huang, Jing; Gao, Yuanyuan; Zhang, Shanli; Zhang, Hua; Feng, Qianjin; Liang, Zhengrong; Chen, Wufan; Ma, Jianhua

    2017-07-01

    Reducing radiation dose in dual energy computed tomography (DECT) is highly desirable but it may lead to excessive noise in the filtered backprojection (FBP) reconstructed DECT images, which can inevitably increase the diagnostic uncertainty. To obtain clinically acceptable DECT images from low-mAs acquisitions, in this work we develop a novel scheme based on measurement of DECT data. In this scheme, inspired by the success of edge-preserving non-local means (NLM) filtering in CT imaging and the intrinsic characteristics underlying DECT images, i.e. global correlation and non-local similarity, an averaged image induced NLM-based (aviNLM) regularization is incorporated into the penalized weighted least-squares (PWLS) framework. Specifically, the presented NLM-based regularization is designed by averaging the acquired DECT images, which takes the image similarity within the two energies into consideration. In addition, the weighted least-squares term takes into account DECT data-dependent variance. For simplicity, the presented scheme was termed as ‘PWLS-aviNLM’. The performance of the presented PWLS-aviNLM algorithm was validated and evaluated on digital phantom, physical phantom and patient data. The extensive experiments validated that the presented PWLS-aviNLM algorithm outperforms the FBP, PWLS-TV and PWLS-NLM algorithms quantitatively. More importantly, it delivers the best qualitative results with the finest details and the fewest noise-induced artifacts, due to the aviNLM regularization learned from DECT images. This study demonstrated the feasibility and efficacy of the presented PWLS-aviNLM algorithm to improve the DECT reconstruction and resulting material decomposition.

  20. Non-local flow effects on bedform dynamics

    Science.gov (United States)

    Perron, J. Taylor; Kao, Justin; Myrow, Paul

    2013-04-01

    Bedform patterns are sensitive recorders of feedbacks among bed topography, fluid flow, and sediment transport. Some of the most important feedbacks are local. For example, evolution models based on simple flow parameterizations that only incorporate local bed height can reproduce some of the essential features of bedform evolution, including bedform growth and migration. However, non-local effects can also be critically important. For example, field and laboratory measurements have shown that the spacing of most sand ripples generated by wave-driven oscillatory flows is linearly proportional to the amplitude of the flow oscillation, implying that fluid stress and sediment transport at a given location depend on upstream features that perturb the flow. A model that fully captures the coupling of flow and bedform evolution must include such effects, but it is not clear how detailed the description of the flow must be to reproduce the most important aspects of bedform evolution. To account for the most significant non-local flow effects without resorting to a coupled hydrodynamic model, we propose an approximation in which the bed shear stress is expressed as a convolution of the bed topography with a kernel that includes both local effects, such as acceleration over bumps, and non-local effects, such as flow separation and re-attachment. Two-dimensional flow simulations demonstrate that a single, generic kernel gives a good approximation of shear stress over a wide range of bed profiles under oscillatory and some combined flows. Incorporating this approximation into a simple bedform evolution model, we show that non-local effects are required to reproduce the characteristic transient patterns that emerge as wave ripples respond to changes in the flow, which we have documented with time-lapse imagery of laboratory wave tank experiments. We then show how this result informs interpretations of two-dimensional wave ripple patterns preserved in the geologic record.

  1. Conformal symmetry and nonlinear extensions of nonlocal gravity

    CERN Document Server

    Cusin, Giulia; Maggiore, Michele; Mancarella, Michele

    2016-01-01

    We study two nonlinear extensions of the nonlocal $R\\,\\Box^{-2}R$ gravity theory. We extend this theory in two different ways suggested by conformal symmetry, either replacing $\\Box^{-2}$ with $(-\\Box + R/6)^{-2}$, which is the operator that enters the action for a conformally-coupled scalar field, or replacing $\\Box^{-2}$ with the inverse of the Paneitz operator, which is a four-derivative operator that enters in the effective action induced by the conformal anomaly. We show that the former modification gives an interesting and viable cosmological model, with a dark energy equation of state today $w_{\\rm DE}\\simeq -1.01$, which very closely mimics $\\Lambda$CDM and evolves asymptotically into a de Sitter solution. The model based on the Paneitz operator seems instead excluded by the comparison with observations. We also review some issues about the causality of nonlocal theories, and we point out that these nonlocal models can be modified so to nicely interpolate between Starobinski inflation in the primordia...

  2. Subquantum nonlocal correlations induced by the background random field

    Science.gov (United States)

    Khrennikov, Andrei

    2011-10-01

    We developed a purely field model of microphenomena—prequantum classical statistical field theory (PCSFT). This model not only reproduces important probabilistic predictions of quantum mechanics (QM) including correlations for entangled systems, but also gives a possibility to go beyond QM, i.e. to make predictions of phenomena that could be observed at the subquantum level. In this paper, we discuss one such prediction—the existence of nonlocal correlations between prequantum random fields corresponding to all quantum systems. (And by PCSFT, quantum systems are represented by classical Gaussian random fields and quantum observables by quadratic forms of these fields.) The source of these correlations is the common background field. Thus all prequantum random fields are 'entangled', but in the sense of classical signal theory. On the one hand, PCSFT demystifies quantum nonlocality by reducing it to nonlocal classical correlations based on the common random background. On the other hand, it demonstrates total generality of such correlations. They exist even for distinguishable quantum systems in factorizable states (by PCSFT terminology—for Gaussian random fields with covariance operators corresponding to factorizable quantum states).

  3. Spiralling solitons and multipole localized modes in nonlocal nonlinear media

    DEFF Research Database (Denmark)

    Buccoliero, Daniel; Lopez-Aguayo, Servando; Skupin, Stefan

    2007-01-01

    We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two differe...... models of nonlocal nonlinearity and suggest that the stabilization mechanism is a generic property of a spatial nonlocal nonlinear response independent of its particular functional form.......We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two different...

  4. A non-local evolution equation model of cell-cell adhesion in higher dimensional space.

    Science.gov (United States)

    Dyson, Janet; Gourley, Stephen A; Webb, Glenn F

    2013-01-01

    A model for cell-cell adhesion, based on an equation originally proposed by Armstrong et al. [A continuum approach to modelling cell-cell adhesion, J. Theor. Biol. 243 (2006), pp. 98-113], is considered. The model consists of a nonlinear partial differential equation for the cell density in an N-dimensional infinite domain. It has a non-local flux term which models the component of cell motion attributable to cells having formed bonds with other nearby cells. Using the theory of fractional powers of analytic semigroup generators and working in spaces with bounded uniformly continuous derivatives, the local existence of classical solutions is proved. Positivity and boundedness of solutions is then established, leading to global existence of solutions. Finally, the asymptotic behaviour of solutions about the spatially uniform state is considered. The model is illustrated by simulations that can be applied to in vitro wound closure experiments.

  5. Non-local Optical Potentials

    Science.gov (United States)

    Thompson, Ian

    2010-11-01

    In all direct reactions to probe the structure of exotic nuclei at FRIB, optical potentials will be needed in the entrance and exit channels. At high energies Glauber approximations may be useful, but a low energies (5 to 20 MeV/nucleon) other approaches are required. Recent work of the UNEDF project [1] has shown that reaction cross sections at these energies can be accounted for by calculating all inelastic and transfer channels reachable by one particle-hole transitions from the elastic channel. In this model space, we may also calculate the two-step dynamic polarization potential (DPP) that adds to the bare folded potential to form the complex optical potential. Our calculations of the DPP, however, show that its non-localities are very significant, as well as the partial-wave dependence of both its real and imaginary components. The Perey factors (the wave function ratio to that from an equivalent local potential) are more than 20% different from unity, especially for partial waves inside grazing. These factors combine to suggest a reexamination of the validity of local and L-independent fitted optical potentials, especially for capture reactions that are dominated by low partial waves. Prepared by LLNL under Contract DE-AC52-07NA27344. [1] G.P.A. Nobre, F.S. Dietrich, J.E. Escher, I.J. Thompson, M. Dupuis, J. Terasaki and J. Engel, submitted to Phys. Rev. Letts., 2010.

  6. Diagnostics of nonlocal plasmas: advanced techniques

    Science.gov (United States)

    Mustafaev, Alexander; Grabovskiy, Artiom; Strakhova, Anastasiya; Soukhomlinov, Vladimir

    2014-10-01

    This talk generalizes our recent results, obtained in different directions of plasma diagnostics. First-method of flat single-sided probe, based on expansion of the electron velocity distribution function (EVDF) in series of Legendre polynomials. It will be demonstrated, that flat probe, oriented under different angles with respect to the discharge axis, allow to determine full EVDF in nonlocal plasmas. It is also shown, that cylindrical probe is unable to determine full EVDF. We propose the solution of this problem by combined using the kinetic Boltzmann equation and experimental probe data. Second-magnetic diagnostics. This method is implemented in knudsen diode with surface ionization of atoms (KDSI) and based on measurements of the magnetic characteristics of the KDSI in presence of transverse magnetic field. Using magnetic diagnostics we can investigate the wide range of plasma processes: from scattering cross-sections of electrons to plasma-surface interactions. Third-noncontact diagnostics method for direct measurements of EVDF in remote plasma objects by combination of the flat single-sided probe technique and magnetic polarization Hanley method.

  7. A Generalized Nonlocal Calculus with Application to the Peridynamics Model for Solid Mechanics

    OpenAIRE

    Alali, Bacim; Liu, Kuo; Gunzburger, Max

    2014-01-01

    A nonlocal vector calculus was introduced in [2] that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A generalization is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal...

  8. Determining Cosmology for a Nonlocal Realization of MOND

    CERN Document Server

    Kim, M; Sayeb, M; Tan, L; Woodard, R P; Xu, B

    2016-01-01

    We numerically determine the cosmological branch of the free function in a nonlocal metric-based modification of gravity which provides a relativistic generalization of Milgrom's Modified Newtonian Dynamics. Although we are not able to get exact agreement with $\\Lambda$CDM cosmology for the range $0 \\leq z < 0.0880$ the deviation is interesting in that it makes the current value of the Hubble parameter about 4.5% larger than in the $\\Lambda$CDM model. This may resolve the tension between inferences of $H_0$ which are based on data from large redshift and inferences based on Hubble plots.

  9. Solution of the three-dimensional Helmholtz equation with nonlocal boundary conditions

    Science.gov (United States)

    Hodge, Steve L.; Zorumski, William E.; Watson, Willie R.

    1995-01-01

    The Helmholtz equation is solved within a three-dimensional rectangular duct with a nonlocal radiation boundary condition at the duct exit plane. This condition accurately models the acoustic admittance at an arbitrarily-located computational boundary plane. A linear system of equations is constructed with second-order central differences for the Helmholtz operator and second-order backward differences for both local admittance conditions and the gradient term in the nonlocal radiation boundary condition. The resulting matrix equation is large, sparse, and non-Hermitian. The size and structure of the matrix makes direct solution techniques impractical; as a result, a nonstationary iterative technique is used for its solution. The theory behind the nonstationary technique is reviewed, and numerical results are presented for radiation from both a point source and a planar acoustic source. The solutions with the nonlocal boundary conditions are invariant to the location of the computational boundary, and the same nonlocal conditions are valid for all solutions. The nonlocal conditions thus provide a means of minimizing the size of three-dimensional computational domains.

  10. Wave-packet dynamics in one-dimensional nonlinear Schroedinger lattices: local vs. nonlocal nonlinear effects

    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.

  11. Rigidity of critical points for a nonlocal Ohta-Kawasaki energy

    Science.gov (United States)

    Dipierro, Serena; Novaga, Matteo; Valdinoci, Enrico

    2017-04-01

    We investigate the shape of critical points for a free energy consisting of a nonlocal perimeter plus a nonlocal repulsive term. In particular, we prove that a volume-constrained critical point is necessarily a ball if its volume is sufficiently small with respect to its isodiametric ratio, thus extending a result previously known only for global minimizers. We also show that, at least in one-dimension, there exist critical points with arbitrarily small volume and large isodiametric ratio. This example shows that a constraint on the diameter is, in general, necessary to establish the radial symmetry of the critical points.

  12. Existence of solutions for non-autonomous functional evolution equations with nonlocal conditions

    Directory of Open Access Journals (Sweden)

    Xianlong Fu

    2012-07-01

    Full Text Available In this work, we study the existence of mild solutions and strict solutions of semilinear functional evolution equations with nonlocal conditions, where the linear part is non-autonomous and generates a linear evolution system. The fraction power theory and alpha-norm are used to discuss the problems so that the obtained results can be applied to the equations in which the nonlinear terms involve spatial derivatives. In particular, the compactness condition or Lipschitz condition for the function g in the nonlocal conditions appearing in various literatures is not required here. An example is presented to show the applications of the obtained results

  13. Fragmentation functions of pions and kaons in the nonlocal chiral quark model

    Directory of Open Access Journals (Sweden)

    Kao Chung Wen

    2014-03-01

    Full Text Available We investigate the unpolarized pion and kaon fragmentation functions using the nonlocal chiral-quark model. In this model the interactions between the quarks and pseudoscalar mesons is manifested nonlocally. In addition, the explicit flavor SU(3 symmetry breaking effect is taken into account in terms of the current quark masses. The results of our model are evaluated to higher Q2 value Q2 = 4 GeV2 by the DGLAP evolution. Then we compare them with the empirical parametrizations. We find that our results are in relatively good agreement with the empirical parametrizations and the other theoretical estimations.

  14. Nonperturbative embedding for highly nonlocal Hamiltonians

    Science.gov (United States)

    Subaşı, Yiǧit; Jarzynski, Christopher

    2016-07-01

    The need for Hamiltonians with many-body interactions arises in various applications of quantum computing. However, interactions beyond two-body are difficult to realize experimentally. Perturbative gadgets were introduced to obtain arbitrary many-body effective interactions using Hamiltonians with at most two-body interactions. Although valid for arbitrary k -body interactions, their use is limited to small k because the strength of interaction is k th order in perturbation theory. In this paper we develop a nonperturbative technique for obtaining effective k -body interactions using Hamiltonians consisting of at most l -body interactions with l effect of this procedure is shown to be equivalent to evolving the system with the original nonlocal Hamiltonian. This technique does not suffer from the aforementioned shortcoming of perturbative methods and requires only one ancilla qubit for each k -body interaction irrespective of the value of k . It works best for Hamiltonians with a few many-body interactions involving a large number of qubits and can be used together with perturbative gadgets to embed Hamiltonians of considerable complexity in proper subspaces of two-local Hamiltonians. We describe how our technique can be implemented in a hybrid (gate-based and adiabatic) as well as solely adiabatic quantum computing scheme.

  15. Post Buckling Behaviour of a Nanobeam considering both the surface and nonlocal effects

    Science.gov (United States)

    Maitra, Rajarshi; Bose, Supratik

    2012-07-01

    Nano-scale beams and plates have been the key components of the sensor and actuator in nanoelectromechnical (NEMS) systems with wide applications in environmental monitoring, medical diagnostics, food processing, mining, bioengineering and defence. Nonlocal and surface effects have been incorporated to find critical load of a nano beam subjected to a transverse loading. The Nonlocal theory, expresses the stress field at a point in an elastic continuum in terms of not only strains at that point but also the strains throughout the body. The governing equation of a normal beam has been modified to achieve the governing differential equation of a nano beam. The post buckling behaviour of a nano beam has been tried to be assessed. The results showed that the surface effects try to delay the buckling process whereas the nonlocal effects contribute to the instability.

  16. Beyond the Dirac phase factor: Dynamical Quantum Phase-Nonlocalities in the Schroedinger Picture

    CERN Document Server

    Moulopoulos, Konstantinos

    2011-01-01

    Generalized solutions of the standard gauge transformation equations are presented and discussed in physical terms. They go beyond the usual Dirac phase factors and they exhibit nonlocal quantal behavior, with the well-known Relativistic Causality of classical fields affecting directly the phases of wavefunctions in the Schroedinger Picture. These nonlocal phase behaviors, apparently overlooked in path-integral approaches, give a natural account of the dynamical nonlocality character of the various (even static) Aharonov-Bohm phenomena, while at the same time they seem to respect Causality. Indeed, for particles passing through nonvanishing magnetic or electric fields they lead to cancellations of Aharonov-Bohm phases at the observation point, generalizing earlier semiclassical experimental observations (of Werner & Brill) to delocalized (spread-out) quantum states. This leads to a correction of previously unnoticed sign-errors in the literature, and to a natural explanation of the deeper reason why certa...

  17. Non-local two phase flow momentum transport in S BWR

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa P, G.; Salinas M, L.; Vazquez R, A., E-mail: gepe@xanum.uam.mx [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Apdo. Postal 55-535, 09340 Ciudad de Mexico (Mexico)

    2015-09-15

    The non-local momentum transport equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection, diffusion and transport properties for two-phase flow. For instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail. The S BWR was considered to study the non-local effects on the two-phase flow thermal-hydraulic core performance in steady-state, and the results were compared with the classical local averaging volume conservation equations. (Author)

  18. POSITIVE SOLUTIONS TO SYSTEMS OF SECOND ORDER NONLOCAL BOUNDARY VALUE PROBLEMS WITH FIRST ORDER DERIVATIVES

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper investigates the existence of positive solutions to systems of second order nonlocal boundary value problems with first order derivatives, in which the nonlinear term is not required to be continuous and involves first order derivatives. The main tool used in this paper is a fixed point index theory in a cone.

  19. Finite time blow-up for a wave equation with a nonlocal nonlinearity

    CERN Document Server

    Fino, Ahmad; Georgiev, Vladimir

    2010-01-01

    In this article, we study the local existence of solutions for a wave equation with a nonlocal in time nonlinearity. Moreover, a blow-up results are proved under some conditions on the dimensional space, the initial data and the nonlinear forcing term.

  20. Visualizing color term differences based on images from the web

    Directory of Open Access Journals (Sweden)

    Nobuyuki Umezu

    2017-01-01

    Full Text Available Color terms are used to express light spectrum characteristics captured by human vision, and color naming across languages partition color spaces differently. Such partition differences have been surveyed through several empirical experiments that employ Munsell color chips. We propose a novel visualization method for color terms based on thousands of images collected from query results provided by an image search engines such as Google. A series of experiments was conducted using eight basic color terms in seven languages. Pixel values in the images are counted to form color histograms according to the color pallet used in the world color survey. The visualization results can be summarized as follows: (1 Japanese and Korean color terms have wider distributions in the color space than terms in other languages do and (2 color visualizations for color terms pink and brown are affected by their links to proper nouns.

  1. Dynamics in Nonlocal Cosmological Models Derived from String Field Theory

    OpenAIRE

    Joukovskaya, Liudmila

    2007-01-01

    A general class of nonlocal cosmological models is considered. A new method for solving nonlocal Friedmann equations is proposed, and solutions of the Friedmann equations with nonlocal operator are presented. The cosmological properties of these solutions are discussed. Especially indicated is $p$-adic cosmological model in which we have obtained nonsingular bouncing solution and string field theory tachyon model in which we have obtained full solution of nonlocal Friedmann equations with $w=...

  2. Nonlocal Optics of Plasmonic Nanowire Metamaterials

    CERN Document Server

    Wells, Brian M; Podolskiy, Viktor A

    2014-01-01

    We present an analytical description of the nonlocal optical response of plasmonic nanowire metamaterials that enable negative refraction, subwavelength light manipulation, and emission lifetime engineering. We show that dispersion of optical waves propagating in nanowire media results from coupling of transverse and longitudinal electromagnetic modes supported by the composite and derive the nonlocal effective medium approximation for this dispersion. We derive the profiles of electric field across the unit cell, and use these expressions to solve the long-standing problem of additional boundary conditions in calculations of transmission and reflection of waves by nonlocal nanowire media. We verify our analytical results with numerical solutions of Maxwell's equations and discuss generalization of the developed formalism to other uniaxial metamaterials.

  3. Transfer reaction code with nonlocal interactions

    CERN Document Server

    Titus, L J; Nunes, F M

    2016-01-01

    We present a suite of codes (NLAT for nonlocal adiabatic transfer) to calculate the transfer cross section for single-nucleon transfer reactions, $(d,N)$ or $(N,d)$, including nonlocal nucleon-target interactions, within the adiabatic distorted wave approximation. For this purpose, we implement an iterative method for solving the second order nonlocal differential equation, for both scattering and bound states. The final observables that can be obtained with NLAT are differential angular distributions for the cross sections of $A(d,N)B$ or $B(N,d)A$. Details on the implementation of the T-matrix to obtain the final cross sections within the adiabatic distorted wave approximation method are also provided. This code is suitable to be applied for deuteron induced reactions in the range of $E_d=10-70$ MeV, and provides cross sections with $4\\%$ accuracy.

  4. Transfer reaction code with nonlocal interactions

    Science.gov (United States)

    Titus, L. J.; Ross, A.; Nunes, F. M.

    2016-10-01

    We present a suite of codes (NLAT for nonlocal adiabatic transfer) to calculate the transfer cross section for single-nucleon transfer reactions, (d , N) or (N , d) , including nonlocal nucleon-target interactions, within the adiabatic distorted wave approximation. For this purpose, we implement an iterative method for solving the second order nonlocal differential equation, for both scattering and bound states. The final observables that can be obtained with NLAT are differential angular distributions for the cross sections of A(d , N) B or B(N , d) A. Details on the implementation of the T-matrix to obtain the final cross sections within the adiabatic distorted wave approximation method are also provided. This code is suitable to be applied for deuteron induced reactions in the range of Ed =10-70 MeV, and provides cross sections with 4% accuracy.

  5. Towards an emerging understanding of non-locality phenomena and non-local transport

    Science.gov (United States)

    Ida, K.; Shi, Z.; Sun, H. J.; Inagaki, S.; Kamiya, K.; Rice, J. E.; Tamura, N.; Diamond, P. H.; Dif-Pradalier, G.; Zou, X. L.; Itoh, K.; Sugita, S.; Gürcan, O. D.; Estrada, T.; Hidalgo, C.; Hahm, T. S.; Field, A.; Ding, X. T.; Sakamoto, Y.; Oldenbürger, S.; Yoshinuma, M.; Kobayashi, T.; Jiang, M.; Hahn, S. H.; Jeon, Y. M.; Hong, S. H.; Kosuga, Y.; Dong, J.; Itoh, S.-I.

    2015-01-01

    In this paper, recent progress on experimental analysis and theoretical models for non-local transport (non-Fickian fluxes in real space) is reviewed. The non-locality in the heat and momentum transport observed in the plasma, the departures from linear flux-gradient proportionality, and externally triggered non-local transport phenomena are described in both L-mode and improved-mode plasmas. Ongoing evaluation of ‘fast front’ and ‘intrinsically non-local’ models, and their success in comparisons with experimental data, are discussed

  6. The effect of calibrated nonlocal constant on the modal parameters and stability of axially compressed CNTs

    Science.gov (United States)

    Fathi, Reza; Lotfan, Saeed

    2016-05-01

    Nowadays investigating the vibration behavior of carbon nanotubes (CNTs) has drawn considerable attention due to the superior mechanical properties of the CNTs. One of the powerful theoretical methods to study the vibration behavior of CNTs is implementing the nonlocal theory. Most of studies on the vibration behavior of CNTs have assumed a fixed value for small scale parameter for all vibration modes, however, this value is mode-dependent. Therefore, in this paper, the small scale parameter is calibrated for a single-walled carbon nanotube (SWCNT) with respect to each vibration mode. For this propose, the governing equation of motion based on the nonlocal beam theory is extracted by applying the Hamilton's principle. Then, by using the power series method, an eigenvalue problem is defined to derive the calibrated value of small scale constant and nonlocal mode shapes of the CNT. By using the expansion theory, the equation of motion is discretized, and the effect of nonlocality on the modal parameters and stability of the CNT under compressive force is investigated. Finally, the possibility of estimating nonlocal parameter based on simulated frequency domain response of the system by using modal analysis methods is studied. The results show that the calibration of small scale constant is important and the critical axial force is highly sensitive to this value.

  7. Classification of scalar and dyadic nonlocal optical response models

    DEFF Research Database (Denmark)

    Wubs, Martijn

    2015-01-01

    Nonlocal optical response is one of the emerging effects on the nanoscale for particles made of metals or doped semiconductors. Here we classify and compare both scalar and tensorial nonlocal response models. In the latter case the nonlocality can stem from either the longitudinal response...

  8. Nonlocal regularization of abelian models with spontaneous symmetry breaking

    OpenAIRE

    Clayton, M. A.

    2001-01-01

    We demonstrate how nonlocal regularization is applied to gauge invariant models with spontaneous symmetry breaking. Motivated by the ability to find a nonlocal BRST invariance that leads to the decoupling of longitudinal gauge bosons from physical amplitudes, we show that the original formulation of the method leads to a nontrivial relationship between the nonlocal form factors that can appear in the model.

  9. Nonlocality and entanglement as opposite properties

    CERN Document Server

    Vallone, G; Gómez, E S; Cañas, G; Larsson, J -A; Mataloni, P; Cabello, A

    2011-01-01

    We show that, for any chained Bell inequality with any number of settings, nonlocality and entanglement are not only essentially different properties but opposite ones. We first show that, in the absence of noise, the threshold detection efficiency for a loophole-free Bell test increases with the degree of entanglement, so that the closer the quantum states are to product states, the harder it is to reproduce the quantum predictions with local models. In the presence of white noise, we show that nonlocality and entanglement are simultaneously maximized only in the presence of extreme noise; in any other case, the lowest threshold detection efficiency is obtained by reducing the entanglement.

  10. Reversed rainbow with a nonlocal metamaterial

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Tiago A., E-mail: tiago.morgado@co.it.pt; Marcos, João S.; Silveirinha, Mário G., E-mail: mario.silveirinha@co.it.pt [Department of Electrical Engineering, Instituto de Telecomunicações, University of Coimbra, 3030 Coimbra (Portugal); Costa, João T. [CST AG, Bad Nauheimer Strasse 19, 64289 Darmstadt (Germany); Costa, Jorge R. [Instituto de Telecomunicações and Instituto Universitário de Lisboa (ISCTE-IUL), 1649-026 Lisboa (Portugal); Fernandes, Carlos A. [Instituto de Telecomunicações, and Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2014-12-29

    One of the intriguing potentials of metamaterials is the possibility to realize a nonlocal electromagnetic reaction, such that the effective medium response at a given point is fundamentally entangled with the macroscopic field distribution at long distances. Here, it is experimentally and numerically verified that a microwave nonlocal metamaterial formed by crossed metallic wires enables a low-loss broadband anomalous material response such that the refractive index decreases with frequency. Notably, it is shown that an electromagnetic beam refracted by our metamaterial prism creates a reversed microwave rainbow.

  11. Breather solitons in highly nonlocal media

    CERN Document Server

    Alberucci, Alessandro; Assanto, Gaetano

    2016-01-01

    We investigate the breathing of optical spatial solitons in highly nonlocal media. Generalizing the Ehrenfest theorem, we demonstrate that oscillations in beam width obey a fourth-order ordinary differential equation. Moreover, in actual highly nonlocal materials, the original accessible soliton model by Snyder and Mitchell [Science \\textbf{276}, 1538 (1997)] cannot accurately describe the dynamics of self-confined beams as the transverse size oscillations have a period which not only depends on power but also on the initial width. Modeling the nonlinear response by a Poisson equation driven by the beam intensity we verify the theoretical results against numerical simulations.

  12. Low energy signatures of nonlocal field theories

    Science.gov (United States)

    Belenchia, Alessio; Benincasa, Dionigi M. T.; Martín-Martínez, Eduardo; Saravani, Mehdi

    2016-09-01

    The response of inertial particle detectors coupled to a scalar field satisfying nonlocal dynamics described by nonanalytic functions of the d'Alembertian operator □ is studied. We show that spontaneous emission processes of a low energy particle detector are very sensitive to high-energy nonlocality scales. This allows us to suggest a nuclear physics experiment (˜MeV energy scales) that outperforms the sensitivity of LHC experiments by many orders of magnitude. This may have implications for the falsifiability of theoretical proposals of quantum gravity.

  13. Demystifying the GMAT: Computer-Based Testing Terms

    Science.gov (United States)

    Rudner, Lawrence M.

    2012-01-01

    Computer-based testing can be a powerful means to make all aspects of test administration not only faster and more efficient, but also more accurate and more secure. While the Graduate Management Admission Test (GMAT) exam is a computer adaptive test, there are other approaches. This installment presents a primer of computer-based testing terms.

  14. The charge-asymmetric nonlocally-determined local-electric (CANDLE) solvation model

    CERN Document Server

    Sundararaman, Ravishankar

    2014-01-01

    Many important applications of electronic structure methods involve molecules or solid surfaces in a solvent medium. Since explicit treatment of the solvent in such methods is usually not practical, calculations often employ continuum solvation models to approximate the effect of the solvent. Previous solvation models either involve a parametrization based on atomic radii, which limits the class of applicable solutes, or based on solute electron density, which is more general but less accurate, especially for charged systems. We develop an accurate and general solvation model that includes a cavity that is a nonlocal functional of both solute electron density and potential, local dielectric response on this nonlocally-determined cavity, and nonlocal approximations to the cavity-formation and dispersion energies. The dependence of the cavity on the solute potential enables an explicit treatment of the solvent charge asymmetry. With only three parameters per solvent, this `CANDLE' model simultaneously reproduce...

  15. [A fast non-local means algorithm for denoising of computed tomography images].

    Science.gov (United States)

    Kang, Changqing; Cao, Wenping; Fang, Lei; Hua, Li; Cheng, Hong

    2012-11-01

    A fast non-local means image denoising algorithm is presented based on the single motif of existing computed tomography images in medical archiving systems. The algorithm is carried out in two steps of prepossessing and actual possessing. The sample neighborhood database is created via the data structure of locality sensitive hashing in the prepossessing stage. The CT image noise is removed by non-local means algorithm based on the sample neighborhoods accessed fast by locality sensitive hashing. The experimental results showed that the proposed algorithm could greatly reduce the execution time, as compared to NLM, and effectively preserved the image edges and details.

  16. On the preservation of cooperation in two-strategy games with nonlocal interactions.

    Science.gov (United States)

    Aydogmus, Ozgur; Zhou, Wen; Kang, Yun

    2017-03-01

    Nonlocal interactions such as spatial interaction are ubiquitous in nature and may alter the equilibrium in evolutionary dynamics. Models including nonlocal spatial interactions can provide a further understanding on the preservation and emergence of cooperation in evolutionary dynamics. In this paper, we consider a variety of two-strategy evolutionary spatial games with nonlocal interactions based on an integro-differential replicator equation. By defining the invasion speed and minimal traveling wave speed for the derived model, we study the effects of the payoffs, the selection pressure and the spatial parameter on the preservation of cooperation. One of our most interesting findings is that, for the Prisoners Dilemma games in which the defection is the only evolutionary stable strategy for unstructured populations, analyses on its asymptotic speed of propagation suggest that, in contrast with spatially homogeneous games, the cooperators can invade the habitat under proper conditions. Other two-strategy evolutionary spatial games are also explored. Both our theoretical and numerical studies show that the nonlocal spatial interaction favors diversity in strategies in a population and is able to preserve cooperation in a competing environment. A real data application in a virus mutation study echoes our theoretical observations. In addition, we compare the results of our model to the partial differential equation approach to demonstrate the importance of including non-local interaction component in evolutionary game models.

  17. Interaction of Nonlocal Incoherent White-Light Solitons

    Institute of Scientific and Technical Information of China (English)

    HUANG Chun-Fu; GUO Qi

    2007-01-01

    The propagation and interaction of nonlocal incoherent white-light solitons in strongly nonlocal kerr media is investigated. Numerical simulations show that the interaction properties of nonlocal incoherent white-light solitons are different from the case in local media. The interactions of nonlocal incoherent white-light solitons are always attractive independent of their relative phase, while the other parameters such as the extent of nonlocality and the input power have a great impact on the soliton interactions. Pertinent numerical examples are presented to show their propagation and interaction behaviour further.

  18. Consequences and applications of the completeness of Hardy's nonlocality

    Science.gov (United States)

    Mansfield, Shane

    2017-02-01

    Logical nonlocality is completely characterized by Hardy's "paradox" in (2 ,2 ,l ) and (2 ,k ,2 ) scenarios. We consider a variety of consequences and applications of this fact. (i) Polynomial algorithms may be given for deciding logical nonlocality in these scenarios. (ii) Bell states are the only entangled two-qubit states which are not logically nonlocal under projective measurements. (iii) It is possible to witness Hardy nonlocality with certainty in a simple tripartite quantum system. (iv) Noncommutativity of observables is necessary and sufficient for enabling logical nonlocality.

  19. On nonlocal problems for ordinary differential equations and on a nonlocal parabolic transmission problem

    Directory of Open Access Journals (Sweden)

    M. Denche

    1999-01-01

    Full Text Available In the present paper we study nonlocal problems for ordinary differential equations with a discontinuous coefficient for the high order derivative. We establish sufficient conditions, known as regularity conditions, which guarantee the coerciveness for both the space variable and the spectral parameter, as well as guarantee the completeness of the system of root functions. The results obtained are then applied to the study of a nonlocal parabolic transmission problem.

  20. The Non-local Thermodynamical Equilibrium Effects on Opacity

    Institute of Scientific and Technical Information of China (English)

    WU Ze-Qing; ZHANG Ben-Ai; QIU Yu-Bo

    2001-01-01

    Based on the detailed configuration accounting (DCA) model, a method is developed to include the resonant photoionization and the excitation-autoionization in the non-local thermodynamical equilibrium (NLTE) average atom(AA) model. Using this new model, the mean charge states and the opacity are calculated for NLTE high-Z plasmas and compared with other results. The agreement w ith AA model is poor at low electron density. The present results agree well with those of DCA model within 10%. The calculations show that the NLTE effects on opacity are strong.

  1. Opacity Calculations for Non-Local Thermodynamic Equilibrium Mixtures

    Institute of Scientific and Technical Information of China (English)

    吴泽清; 韩国兴; 逄锦桥

    2002-01-01

    Based on the average atom model, a non-local thermodynamic equilibrium (non-LTE) model is developed to calculate opacity for mixtures. This model could be applied to high-Z problems. The mean ionization degrees of SiO2 of the present calculation are slightly higher compared with another model for mixtures. As an example, the opacity of Au and Nd mixture is calculated. The results show concrete non-LTE effects and the increase in opacity of the mixture is shown clearly.

  2. Long-term visual tracking based on correlation filters

    Science.gov (United States)

    Wei, Quanlu; Lao, Songyang; Bai, Liang

    2017-03-01

    In order to accomplish the long term visual tracking task in complex scenes, solve problems of scale variation, appearance variation and tracking failure, a long term tracking algorithm is given based on the framework of collaborative correlation tracking. Firstly, we integrate several powerful features to boost the represent ability based on the kernel correlation filter, and extend the filter by embedding a scale factor into the kernelized matrix to handle the scale variation. Then, we use the Peak-Sidelobe Ratio to decide whether the object is tracked successfully, and a CUR filter for re-detection the object in case of tracking failure is learnt with random sampling. Corresponding experiment is performed on 17 challenging benchmark video sequences. Compared with the 8 existing state-of-the-art algorithms based on discriminative learning method, the results show that the proposed algorithm improves the tracking performance on several indexes, and is robust to complex scenes for long term visual tracking.

  3. Non-local total variation speckle filtering based on region segmentation%基于区域分割的非局部全变差SAR相干斑滤波

    Institute of Scientific and Technical Information of China (English)

    范惠玲; 曲长文; 李健伟

    2016-01-01

    Due to the limit of imaging system, synthetic aperture radar images are often corrupted with non-Gaussian multiplicative speckle noise. For the purpose of noise suppression, an algorithm called NLM-TV is proposed, which integrates non-local means filter and total variation regularization. It involves three steps. First, convert the multiplicative noise into signal-dependent additive noise, dividing the image into three categories based on noise level, the edge, the strong scattering region and the weak scattering region. Non-local means filter was then applied. To maintain the edge structure effectively, the smooth parameter must be small. In the strong scattering region, TV regularization was used because of insufficient reduction of speckles. In this paper, several simulations were conducted in RADARSAT-2 and TerraSAR-X images, the results showed that compared to a variety of filtering algorithms, NLM-TV algorithm could significantly increase the equivalent number of looks both in the weak scattering area and strong scattering regions. At the same time, edge keeping index could be increased by more than 10%.%受成像体制影响,合成孔径雷达(Synthetic aperture radar,SAR)图像带有非高斯的乘性相干斑噪声。为有效抑制乘性相干斑噪声,提出一种融合非局部均值滤波(Non-local means filter, NLMF)与全变差(Total variation,TV)正则化的非局部均值-全变差(NLM-TV)降噪算法。首先将相干斑噪声转换为依赖于散射强度的加性噪声,将SAR图像分为边缘、强散射区、弱散射区。然后利用NLMF进行降斑,为有效的保持边缘结构, NLMF的平滑参数选取较小。在强散射区,为解决平滑参数较小所带来的降斑不充分问题,进一步使用TV正则化进行平滑处理,获得最终的降噪结果。使用RADARSAT-2,TerraSAR-X两景实测SAR图像仿真实验,结果表明:相比多种滤波算法, NLM-TV算法在弱散射区,强散

  4. Nonlocality as Evidence for a Multiverse Cosmology

    Science.gov (United States)

    Tipler, Frank J.

    We show that observations of quantum nonlocaltiy can be interpreted as purely local phenomena, provided one assumes that the cosmos is a multiverse. Conversely, the observation of quantum nonlocality can be interpreted as observation evidence for a multiverse cosmology, just as observation of the setting of the Sun can be interpreted as evidence for the Earth's rotation.

  5. Ring vortex solitons in nonlocal nonlinear media

    DEFF Research Database (Denmark)

    Briedis, D.; Petersen, D.E.; Edmundson, D.;

    2005-01-01

    or higher charge fundamental vortices as well as higher order (multiple ring) vortex solitons. Our results pave the way for experimental observation of stable vortex rings in other nonlocal nonlinear systems including Bose-Einstein condensates with pronounced long-range interparticle interaction....

  6. Nonlocality and discrete cellular methods in optics

    NARCIS (Netherlands)

    Wijers, C.M.J.; Boeij, de P.L.

    2001-01-01

    A subdivision of space into discrete cells underlies the traditional discrete dipole model. This model presumes that only nonlocal electric interactions between cells govern the electromagnetic response of a condensed matter system. Apart from the case of simple dielectrics, this is not realistic. C

  7. Circumferential nonlocal effect on the buckling and vibration of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng Yuan, E-mail: cywang@ujs.edu.cn; Li, Xiao Hu; Luo, Ying

    2016-04-01

    The nonlocal beam theories are widely used to study the mechanics of cylindrical nanotubes (NTs). The one-dimensional models however are unable to account for the nonlocal effect in the circumferential direction, which may substantially affect the applicability of the nonlocal beam models. To address the issue this letter examines the circumferential nonlocal effect (CNE) on the buckling and vibration of the NTs. Here the CNE is characterized by the difference between the nonlocal beam model considering the axial nonlocal effect only and the nonlocal shell model with both axial and circumferential nonlocal effects. The aspect ratio and radius-dependence of the CNE are calculated for the singlewall carbon NTs selected as a typical example. The results show that the CNE is substantial for the buckling and vibration of the NTs with small radius (e.g., <1 nm) and aspect ratio (e.g., <15). It however decreases with the rising radius and the aspect ratio, and turns out to be small for relatively wide and long NTs. The nonlocal beam theories thus may overestimate the buckling load and vibration frequency for the thin and short NTs. - Highlights: • First revealed the substantial circumferential nonlocal effect (CNE) on nanotube buckling. • Achieved radius/aspect ratio-dependence of CNE on nanotube buckling and vibration. • Located the range of applicability of the nonlocal beam theory without CNE.

  8. Results of the Baikal experiment on observations of macroscopic nonlocal correlations in reverse time

    CERN Document Server

    Korotaev, S M; Kiktenko, E O; Budnev, N M; Gorohov, J V

    2015-01-01

    Although the general theory macroscopic quantum entanglement of is still in its infancy, consideration of the matter in the framework of action-at-a distance electrodynamics predicts for the random dissipative processes observability of the advanced nonlocal correlations. These correlations were really revealed in our previous experiments with some large-scale heliogeophysical processes as the source ones and the lab detectors as the probe ones. Recently a new experiment has been performing on the base of Baikal Deep Water Neutrino Observatory. The thick water layer is an excellent shield against any local impacts on the detectors. The first annual series 2012/2013 has demonstrated that detector signals respond to the heliogeophysical processes and causal connection of the signals directed downwards: from the Earth surface to the Baikal floor. But this nonlocal connection proved to be in reverse time. In addition advanced nonlocal correlation of the detector signal with the regional source-process: the random...

  9. On nonlocal characteristics of curved inhomogeneous Euler-Bernoulli nanobeams under different temperature distributions

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza

    2016-10-01

    In this paper, thermo-mechanical buckling analysis of curved functionally graded (FG) nanobeams is carried out via an analytical solution method. Curved FG nanobeam is subjected to uniform, linear and nonlinear temperature distributions across the thickness. Three kinds of boundary condition namely, simply supported-simply supported, simply supported-clamped and clamped-clamped are investigated. Thermo-elastic properties of curved FG beam change in radial direction according to the power-law model. Nonlocal elasticity theory is adopted to capture the size effects. Nonlocal governing equations of curved FG nanobeam are obtained from Hamilton's principle based on Euler-Bernoulli beam model. Finally, the influences of thermal loadings, nonlocal parameter, opening angle, material composition, slenderness ratio and boundary conditions on the thermal buckling behavior of nanosize curved FG beams are explored.

  10. A Two-Step Regularization Framework for Non-Local Means

    Institute of Scientific and Technical Information of China (English)

    孙忠贵; 陈松灿; 乔立山

    2014-01-01

    As an effective patch-based denoising method, non-local means (NLM) method achieves favorable denoising performance over its local counterparts and has drawn wide attention in image processing community. The implementation of NLM can formally be decomposed into two sequential steps, i.e., computing the weights and using the weights to compute the weighted means. In the first step, the weights can be obtained by solving a regularized optimization. And in the second step, the means can be obtained by solving a weighted least squares problem. Motivated by such observations, we establish a two-step regularization framework for NLM in this paper. Meanwhile, using the framework, we reinterpret several non-local filters in the unified view. Further, taking the framework as a design platform, we develop a novel non-local median filter for removing salt-pepper noise with encouraging experimental results.

  11. Non-Local effective SU(2) Polyakov-loop models from inverse Monte-Carlo methods

    CERN Document Server

    Bahrampour, Bardiya; von Smekal, Lorenz

    2016-01-01

    The strong-coupling expansion of the lattice gauge action leads to Polyakov-loop models that effectively describe gluodynamics at low temperatures, and together with the hopping expansion of the fermion determinant provides insight into the QCD phase diagram at finite density and low temperatures, although for rather heavy quarks. At higher temperatures the strong-coupling expansion breaks down and it is expected that the interactions between Polyakov loops become non-local. Here, we therefore test how well pure SU(2) gluodynamics can be mapped onto different non-local Polyakov models with inverse Monte-Carlo methods. We take into account Polyakov loops in higher representations and gradually add interaction terms at larger distances. We are particularly interested in extrapolating the range of non-local terms in sufficiently large volumes and higher representations. We study the characteristic fall-off in strength of the non-local couplings with the interaction distance, and its dependence on the gauge coupl...

  12. Log-Gabor Feature-Based Nonlocal Means Denoising Algorithm and Its Acceleration Scheme%基于Log-Gabor特征的非局部均值去噪算法及其加速方案研究

    Institute of Scientific and Technical Information of China (English)

    张嵩; 景华炯

    2015-01-01

    非局部均值是一种基于像素长程相似性的图像空域去噪算法,它一般采用灰度块特征估计图像像素间的相似度。文中首先使用基于Log-Gabor特征的像素间相似度估计获得较好的去噪效果。然后将Log-Gabor几何特征与灰度特征相融合,所形成的混合相似度具有更佳的图像局部自适应性,去噪性能也得到进一步提升。最后基于Johnson-Lindenstrauss引理研究利用随机降维方法降低相似度计算的复杂度,并对该加速方案的效果,包括降维前后运行时间对比、降维程度以及随机矩阵生成方法对去噪性能的影响,进行详细试验分析,结果证明基于随机降维的加速方案的有效性。%The nonlocal means ( NLM) is a spatial domain image denoising method, and it exploits long range similarities between pixels of natural images. Notably, the similarity between true pixel values in original NLM is estimated based on patch information of noise-corrupted input image. In this paper, the pixel similarities in NLM are estimated based on Log-Gabor features to achieve good denoising results. Moreover, the mixed similarity combining the Log-Gabor features with intensity information is exploited to get better adaptivity to local image characteristics and further improve the denoising quality. In addition, the random projection-based NLM speed-up method is studied based on Johnson-Lindenstrauss lemma. Extensive tests including the running time comparison before and after dimensionality reduction, the impact of types of projection matrices and the extent of dimensionality reduction on final denoising performances are carried out. The experimental results confirm the effectiveness of the proposed acceleration scheme.

  13. Nonlocal impedances and the Casimir entropy at low temperatures

    CERN Document Server

    Svetovoy, V

    2005-01-01

    The problem with the temperature dependence of the Casimir force is investigated. Specifically, the entropy behavior in the low temperature limit, which caused debates in the literature, is analyzed. It is stressed that the behavior of the relaxation frequency in the $T\\to0$ limit does not play a physical role since the anomalous skin effect dominates in this range. In contrast with the previous works, where the approximate Leontovich impedance was used for analysis of nonlocal effects, we give description of the problem in terms of exact nonlocal impedances. It is found that the Casimir entropy is going to zero at $T\\to0$ only in the case when $s$ polarization does not contribute to the classical part of the Casimir force. However, the entropy approaching zero from the negative side that, in our opinion, cannot be considered as thermodynamically satisfactory. The resolution of the negative entropy problem proposed in the literature is analyzed and it is shown that it cannot be considered as complete. The cri...

  14. Bell's Nonlocality in a General Nonsignaling Case: Quantitatively and Conceptually

    Science.gov (United States)

    Loubenets, Elena R.

    2017-03-01

    Quantum violation of Bell inequalities is now used in many quantum information applications and it is important to analyze it both quantitatively and conceptually. In the present paper, we analyze violation of multipartite Bell inequalities via the local probability model—the LqHV (local quasi hidden variable) model (Loubenets in J Math Phys 53:022201, 2012), incorporating the LHV model only as a particular case and correctly reproducing the probabilistic description of every quantum correlation scenario, more generally, every nonsignaling scenario. The LqHV probability framework allows us to construct nonsignaling analogs of Bell inequalities and to specify parameters quantifying violation of Bell inequalities—Bell's nonlocality—in a general nonsignaling case. For quantum correlation scenarios on an N-qudit state, we evaluate these nonlocality parameters analytically in terms of dilation characteristics of an N-qudit state and also, numerically—in d and N. In view of our rigorous mathematical description of Bell's nonlocality in a general nonsignaling case via the local probability model, we argue that violation of Bell inequalities in a quantum case is not due to violation of the Einstein-Podolsky-Rosen (EPR) locality conjectured by Bell but due to the improper HV modelling of "quantum realism".

  15. Magnetic field effects on nonlocal wave dispersion characteristics of size-dependent nanobeams

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza

    2017-01-01

    In this paper, wave propagation analysis of functionally graded size-dependent nanobeams embedded in elastic foundation exposed to a longitudinal magnetic field is conducted based on nonlocal elasticity theory. Material properties of nanobeam change gradually according to the sigmoid function. Applying an analytical solution, the acoustical and optical dispersion relations are explored for various wave number, nonlocality parameter, material composition, elastic foundation constants and magnetic field intensity. It is found that frequency and phase velocity of waves propagating in S-FGM nanobeam are significantly affected by these parameters. Also the presence of cutoff and escape frequencies in wave propagation analysis of embedded S-FGM nanobeams is investigated.

  16. On the application of polynomial and NURBS functions for nonlocal response of low dimensional structures

    CERN Document Server

    Natarajan, S; Bordas, S; Mahapatra, D Roy

    2012-01-01

    In this paper, the axial vibration of cracked beams, the free flexural vibrations of nanobeams and plates based on Timoshenko beam theory and first-order shear deformable plate theory, respectively, using Eringen's nonlocal elasticity theory is numerically studied. The field variable is approximated by Lagrange polynomials and non-uniform rational B-splines. The influence of the nonlocal parameter, the beam and the plate aspect ratio and the boundary conditions on the natural frequency is numerically studied. The influence of a crack on axial vibration is also studied. The results obtained from this study are found to be in good agreement with those reported in the literature.

  17. General investigation for longitudinal wave propagation under magnetic field effect via nonlocal elasticity

    Institute of Scientific and Technical Information of China (English)

    U.GÜVEN

    2015-01-01

    In this paper, the propagation of longitudinal stress waves under a longitu-dinal magnetic field is addressed using a unified nonlocal elasticity model with two scale coefficients. The analysis of wave motion is mainly based on the Love rod model. The effect of shear is also taken into account in the framework of Bishop’s correction. This analysis shows that the classical theory is not sufficient for this subject. However, this unified nonlocal elasticity model solely used in the present study reflects in a manner fairly realistic for the effect of the longitudinal magnetic field on the longitudinal wave propagation.

  18. Chimera states and the interplay between initial conditions and non-local coupling

    Science.gov (United States)

    Kalle, Peter; Sawicki, Jakub; Zakharova, Anna; Schöll, Eckehard

    2017-03-01

    Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We study chimera states in a network of non-locally coupled Stuart-Landau oscillators. We investigate the impact of initial conditions in combination with non-local coupling. Based on an analytical argument, we show how the coupling phase and the coupling strength are linked to the occurrence of chimera states, flipped profiles of the mean phase velocity, and the transition from a phase- to an amplitude-mediated chimera state.

  19. Instantaneous equations for multiphase flow in porous media without length-scale restrictions using a non-local averaging volume

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.m [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Apartado Postal 55-535, Mexico D.F. 09340 (Mexico)

    2010-05-15

    The aim of this paper is to propose a framework to obtain a new formulation for multiphase flow conservation equations without length-scale restrictions, based on the non-local form of the averaged volume conservation equations. The simplification of the local averaging volume of the conservation equations to obtain practical equations is subject to the following length-scale restrictions: d << l << L, where d is the characteristic length of the dispersed phases, l is the characteristic length of the averaging volume, and L is the characteristic length of the physical system. If the foregoing inequality does not hold, or if the scale of the problem of interest is of the order of l, the averaging technique and therefore, the macroscopic theories of multiphase flow should be modified in order to include appropriate considerations and terms in the corresponding equations. In these cases the local form of the averaged volume conservation equations are not appropriate to describe the multiphase system. As an example of the conservation equations without length-scale restrictions, the natural circulation boiling water reactor was consider to study the non-local effects on the thermal-hydraulic core performance during steady-state and transient behaviors, and the results were compared with the classic local averaging volume conservation equations.

  20. Band structure calculation of SH waves in nanoscale multilayered piezoelectric phononic crystals using radial basis function method with consideration of nonlocal interface effects.

    Science.gov (United States)

    Yan, Zhizhong; Wei, Chunqiu; Zhang, Chuanzeng

    2017-01-01

    In this paper, the radial basis function (RBF) collocation method based on the nonlocal Eringen piezoelectricity theory is developed to compute the band structures of nanoscale multilayered piezoelectric phononic crystals taking account of nonlocal interface effects. Detailed calculations are performed for anti-plane transverse waves propagating obliquely or vertically in the system. The correctness of the present method is verified by comparing the numerical results with those obtained by applying the transfer matrix method in the case of nonlocal perfect interfaces. The effects of nonlocal interface imperfections are considered by comparing with the nonlocal perfect interfaces. In addition, the influences of the piezoelectric constant, the nanoscale size, the impedance ratio and the incidence angle on the cut-off frequency and band structures are investigated and discussed in detail. Numerical results show that the nonlocal interface discontinuity has more obvious effect on the low-frequency band structures at the microscopic scale than at the macroscopic scale. Furthermore, at the macroscopic scale, the nonlocal interface imperfection has an obvious effect on the high frequency waves, but the effect on the low frequency waves is not obvious, and the nonlocal interface imperfection has no effect on the cut-off frequency at the microscopic scale. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Algebraic and group structure for bipartite anisotropic Ising model on a non-local basis

    Science.gov (United States)

    Delgado, Francisco

    2015-01-01

    Entanglement is considered a basic physical resource for modern quantum applications as Quantum Information and Quantum Computation. Interactions based on specific physical systems able to generate and sustain entanglement are subject to deep research to get understanding and control on it. Atoms, ions or quantum dots are considered key pieces in quantum applications because they are elements in the development toward a scalable spin-based quantum computer through universal and basic quantum operations. Ising model is a type of interaction generating entanglement in quantum systems based on matter. In this work, a general bipartite anisotropic Ising model including an inhomogeneous magnetic field is analyzed in a non-local basis. This model summarizes several particular models presented in literature. When evolution is expressed in the Bell basis, it shows a regular block structure suggesting a SU(2) decomposition. Then, their algebraic properties are analyzed in terms of a set of physical parameters which define their group structure. In particular, finite products of pulses in this interaction are analyzed in terms of SU(4) covering. Thus, evolution denotes remarkable properties, in particular those related potentially with entanglement and control, which give a fruitful arena for further quantum developments and generalization.

  2. Incremental His-to-coronary sinus maneuver: a nonlocal electrogram-based technique to assess complete cavotricuspid isthmus block during typical flutter ablation.

    Science.gov (United States)

    Vallès, Ermengol; Bazán, Victor; Benito, Begoña; Jáuregui, Miguel Eduardo; Bruguera, Jordi; Guijo, Miguel Angel; Altaba, Carmen; Martí-Almor, Julio

    2013-08-01

    Achievement of complete cavotricuspid isthmus (CTI) conduction block reduces typical atrial flutter recurrences after ablation. The lack of increase in the His-to-coronary sinus ostium atrial interval during incremental pacing (IP) from the low lateral right atrium may distinguish slow conduction from complete CTI conduction block. Sixty-six consecutive patients (age, 65±13 years; 18% female) were prospectively included. A incremental His-to-coronary sinus ostium maneuver was consistent with functional CTI block during phase 1 in all cases and conclusive of complete CTI block in 98% of cases during phase 2. The incremental His-to-coronary sinus ostium maneuver is analogous to the IP maneuver in distinguishing complete CTI block from persistent CTI conduction. This maneuver may provide confirmation of CTI block in those patients in whom assessment of local electrogram-based criteria is not feasible because of inconclusive potentials in the CTI ablation line.

  3. Effects of Video Weather Training Products, Web-Based Preflight Weather Briefing, and Local Versus Non-Local Pilots on General Aviation Pilot Weather Knowledge and Flight Behavior, Phase 3

    Science.gov (United States)

    2010-11-01

    Weather Knowledge and Flight Behavior, Phase 3 DOT/FAA/AM-10/17 Office of Aerospace Medicine Washington, DC 20591 OK-11-0024-JAH Federal Aviation...Vs. Non-Local Pilots on General Aviation Pilot Weather Knowledge and Flight Behavior, Phase 3 6. Performing Organization Code 7. Author(s...behavior in Phase 2; (2) Whole-group (N=50) weather knowledge test scores were significantly lower (19%, p<.001) than average FAA certification exam

  4. Classification of scalar and dyadic nonlocal optical response models.

    Science.gov (United States)

    Wubs, M

    2015-11-30

    Nonlocal optical response is one of the emerging effects on the nanoscale for particles made of metals or doped semiconductors. Here we classify and compare both scalar and tensorial nonlocal response models. In the latter case the nonlocality can stem from either the longitudinal response, the transverse response, or both. In phenomenological scalar models the nonlocal response is described as a smearing out of the commonly assumed infinitely localized response, as characterized by a distribution with a finite width. Here we calculate explicitly whether and how tensorial models, such as the hydrodynamic Drude model and generalized nonlocal optical response theory, follow this phenomenological description. We find considerable differences, for example that nonlocal response functions, in contrast to simple distributions, assume negative and complex values. Moreover, nonlocal response regularizes some but not all diverging optical near fields. We identify the scalar model that comes closest to the hydrodynamic model. Interestingly, for the hydrodynamic Drude model we find that actually only one third (1/3) of the free-electron response is smeared out nonlocally. In that sense, nonlocal response is stronger for transverse and scalar nonlocal response models, where the smeared-out fractions are 2/3 and 3/3, respectively. The latter two models seem to predict novel plasmonic resonances also below the plasma frequency, in contrast to the hydrodynamic model that predicts standing pressure waves only above the plasma frequency.

  5. Applying activity-based costing in long-term care.

    Science.gov (United States)

    Wodchis, W P

    1998-01-01

    As greater numbers of the elderly use health services, and as health care costs climb, effective financial tracking is essential. Cost management in health care can benefit if costs are linked to the care activities where they are incurred. Activity-based costing (ABC) provides a useful approach. The framework aligns costs (inputs), through activities (process), to outputs and outcomes. It allocates costs based on client care needs rather than management structure. The ABC framework was tested in a residential care facility and in supportive housing apartments. The results demonstrate the feasibility and advantages of ABC for long term care agencies, including community-based care.

  6. On a Class of Multitime Evolution Equations with Nonlocal Initial Conditions

    Directory of Open Access Journals (Sweden)

    F. Zouyed

    2007-01-01

    Full Text Available The existence and uniqueness of the strong solution for a multitime evolution equation with nonlocal initial conditions are proved. The proof is essentially based on a priori estimates and on the density of the range of the operator generated by the considered problem.

  7. Parameter-Free Compressed Sensing Reconstruction using Statistical Non-Local Self-Similarity Filtering

    NARCIS (Netherlands)

    Doneva, M.; Nielsen, T.; Boernert, P.

    2012-01-01

    In this work, we present a CS reconstruction based on statistical non-local self-similarity filtering (STAINLeSS), in which the parameters are entirely determined by the noise estimation in the receive channels obtained from a standard noise measurement. The method achieves improved image quality co

  8. On Some Qualitative Properties of Mild Solutions of Nonlocal Semilinear Functional Differential Equations

    Directory of Open Access Journals (Sweden)

    Jain Rupali S.

    2014-12-01

    Full Text Available In the present paper, we investigate the qualitative properties such as existence, uniqueness and continuous dependence on initial data of mild solutions of first and second order nonlocal semilinear functional differential equations with delay in Banach spaces. Our analysis is based on semigroup theory and modified version of Banach contraction theorem.

  9. Existence and uniqueness of positive solutions for a nonlocal dispersal population model

    Directory of Open Access Journals (Sweden)

    Jian-Wen Sun

    2014-06-01

    Full Text Available In this article, we study the solutions of a nonlocal dispersal equation with a spatial weight representing competitions and aggregation. To overcome the limitations of comparison principles, we introduce new definitions of upper-lower solutions. The proof of existence and uniqueness of positive solutions is based on the method of monotone iteration sequences.

  10. Temporal sparsity exploiting nonlocal regularization for 4D computed tomography reconstruction.

    Science.gov (United States)

    Kazantsev, Daniil; Guo, Enyu; Kaestner, Anders; Lionheart, William R B; Bent, Julian; Withers, Philip J; Lee, Peter D

    2016-01-01

    X-ray imaging applications in medical and material sciences are frequently limited by the number of tomographic projections collected. The inversion of the limited projection data is an ill-posed problem and needs regularization. Traditional spatial regularization is not well adapted to the dynamic nature of time-lapse tomography since it discards the redundancy of the temporal information. In this paper, we propose a novel iterative reconstruction algorithm with a nonlocal regularization term to account for time-evolving datasets. The aim of the proposed nonlocal penalty is to collect the maximum relevant information in the spatial and temporal domains. With the proposed sparsity seeking approach in the temporal space, the computational complexity of the classical nonlocal regularizer is substantially reduced (at least by one order of magnitude). The presented reconstruction method can be directly applied to various big data 4D (x, y, z+time) tomographic experiments in many fields. We apply the proposed technique to modelled data and to real dynamic X-ray microtomography (XMT) data of high resolution. Compared to the classical spatio-temporal nonlocal regularization approach, the proposed method delivers reconstructed images of improved resolution and higher contrast while remaining significantly less computationally demanding.

  11. A Nagumo-type model for competing populations with nonlocal coupling.

    Science.gov (United States)

    Tanzy, M C; Volpert, V A; Bayliss, A; Nehrkorn, M E

    2015-05-01

    We consider a model of two competing species with nonlocal competition for resources. The net birthrate is cubic, so that the model allows simulation of the Allee effect, whereby extinction is stable and intermediate populations promote growth, while saturation occurs via cubic competition terms. The model includes both interspecies and intraspecies nonlocal competition which enters via convolution integrals with a specified asymmetric competition kernel function. We introduce two parameters, δ, describing the extent of the coupling, with δ = 0 corresponding to local coupling, and α, describing the extent of the asymmetry, with α = 0 corresponding to symmetric nonlocal interactions. We consider the case where the local model admits a stable coexistence (populations of both species positive) equilibrium solution. We perform a linear stability analysis and show that this solution can be destabilized by sufficient nonlocality, i.e., when δ increases beyond a critical value. We then consider nonlinear patterns, far from the stability boundary. We show that nonlinear patterns consist of arrays of islands, regions of nonzero population, separated by deadzones, where the populations are essentially extinct, (with the array propagating in the case α ≠ 0). The predominant effect of the cubic model is that the islands for the two species are disjoint, so that each species lives in the deadzone of the other species. In addition, some patterns involve both hospitable and inhospitable deadzones, so that islands form in only some of the deadzones.

  12. Microscopic formulation of nonlocal electrostatics in polar liquids embedding polarizable ions.

    Science.gov (United States)

    Buyukdagli, Sahin; Ala-Nissila, T

    2013-06-01

    Nonlocal electrostatic interactions associated with finite solvent size and ion polarizability are investigated within the mean-field linear response theory. To this end, we introduce a field-theoretic model of a polar liquid composed of linear multipole solvent molecules and embedding polarizable ions modeled as Drude oscillators. Unlike previous dipolar Poisson-Boltzmann formulations treating the solvent molecules as point dipoles, our model is able to qualitatively reproduce the non-local dielectric response behavior of polar liquids observed in molecular dynamics simulations and atomic force microscope experiments for water solvent at charged interfaces. The present theory explains the formation of the associated interfacial hydration layers in terms of a cooperative dipolar response mechanism driven by the reaction of the solvent molecules to their own polarization field. We also incorporate into the theory the relative multipole moments of water molecules obtained from quantum mechanical calculations and show that the multipolar contributions to the dielectric permittivity are largely dominated by the dipolar one. We find that this stems from the mutual cancellation of the first two interfacial hydration layers of opposite net charge for multipolar liquids. Within the same nonlocal dielectric response theory, we show that the induced ion polarizability reverses the interfacial ion density trends predicted by the Poisson-Boltzmann theory, resulting in a surface affinity of coions and exclusion of counterions. The results indicate that the consideration of the discrete charge composition of solvent molecules and ions is the key step towards a microscopic understanding of nonlocal electrostatic effects in polar solvents.

  13. Nonlocal Operational Calculi for Dunkl Operators

    Directory of Open Access Journals (Sweden)

    Ivan H. Dimovski

    2009-03-01

    Full Text Available The one-dimensional Dunkl operator $D_k$ with a non-negative parameter $k$, is considered under an arbitrary nonlocal boundary value condition. The right inverse operator of $D_k$, satisfying this condition is studied. An operational calculus of Mikusinski type is developed. In the frames of this operational calculi an extension of the Heaviside algorithm for solution of nonlocal Cauchy boundary value problems for Dunkl functional-differential equations $P(D_ku = f$ with a given polynomial $P$ is proposed. The solution of these equations in mean-periodic functions reduces to such problems. Necessary and sufficient condition for existence of unique solution in mean-periodic functions is found.

  14. Nonlocal Condensate Model for QCD Sum Rules

    CERN Document Server

    Hsieh, Ron-Chou

    2009-01-01

    We include effects of nonlocal quark condensates into QCD sum rules (QSR) via the K$\\ddot{\\mathrm{a}}$ll$\\acute{\\mathrm{e}}$n-Lehmann representation for a dressed fermion propagator, in which a negative spectral density function manifests their nonperturbative nature. Applying our formalism to the pion form factor as an example, QSR results are in good agreement with data for momentum transfer squared up to $Q^2 \\approx 10 $ GeV$^2$. It is observed that the nonlocal quark-condensate contribution descends like $1/Q^4$, different from the exponential decrease in $Q^2$ obtained in the literature, and contrary to the linear rise in the local-condensate approximation.

  15. Nonlocal inhomogeneous broadening in plasmonic nanoparticle ensembles

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Maack, Johan Rosenkrantz; Liu, Z.

    Nonclassical effects are increasingly more relevant in plasmonics as modern nanofabrication techniques rapidly approach the extreme nanoscale limits, for which departing from classical electrodynamics becomes important. One of the largest-scale necessary corrections towards this direction...... is to abandon the local response approximation (LRA) and take the nonlocal response of the metal into account, typically through the simple hydrodynamic Drude model (HDM), which predicts a sizedependent deviation of plasmon modes from the quasistatic (QS) limit. While this behaviour has been explored for simple...... averaging through both HDM and the recent Generalized Nonlocal Optical Response (GNOR) theory, which apart from the resonance frequency shifts accounts successfully for size-dependent damping as well. We examine NPs made of either ideal Drude-like metals [of plasmon frequency (wavelength) ωp (λp...

  16. Nonlocal neurology: beyond localization to holonomy.

    Science.gov (United States)

    Globus, G G; O'Carroll, C P

    2010-11-01

    The concept of local pathology has long served neurology admirably. Relevant models include self-organizing nonlinear brain dynamics, global workspace and dynamic core theories. However such models are inconsistent with certain clinical phenomena found in Charles Bonnet syndrome, disjunctive agnosia and schizophrenia, where there is disunity of content within the unity of consciousness. This is contrasted with the split-brain case where there is disunity of content and disunity of consciousnesses. The development of quantum brain theory with it nonlocal mechanisms under the law of the whole ("holonomy") offers new possibilities for explaining disintegration within unity. Dissipative quantum brain dynamics and its approach to the binding problem, memory and consciousness are presented. A nonlocal neurology armed with a holonomic understanding might see more deeply into what clinical neurology has always aspired to: the patient as a whole.

  17. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, S.; Xiao, Sanshui;

    2012-01-01

    Giant field enhancement and field singularities are a natural consequence of the commonly employed local-response framework. We show that a more general nonlocal treatment of the plasmonic response leads to new and possibly fundamental limitations on field enhancement with important consequences ...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (10(10)). (C) 2012 Optical Society of America...

  18. Structure of Nonlocal Vacuum Condensate of Quarks

    Institute of Scientific and Technical Information of China (English)

    周丽娟; 马维兴

    2003-01-01

    The Dyson-Schwinger formalism is used to derive a fully dressed quark propagator. By use of the derived form of the quark propagator, the structure of non-local quark vacuum condensate is studied, and the values of local quark vacuum condensate as well as quark gluon mixed condensate are calculated. The theoretical predictions are in good agreement with the empirical one used commonly in the literature.

  19. Nonlocal Optical Response of Plasmonic Nanowire Metamaterials

    Science.gov (United States)

    2014-01-01

    exceptional properties that are not readily found in nature. There are numerous applications in modern optics which can be realized through the study and...K., R. C. McPhedran, and Vladimir M. Shalaev. " Electrodynamics of metal-dielectric composites and electromagnetic crystals." Physical Review B 62.12...16.10 (2008): 7460-7470. [41] Pokrovsky, A. L., and A. L. Efros. "Nonlocal electrodynamics of two-dimensional wire mesh photonic crystals." Physical

  20. Fully nonlocal, monogamous and random genuinely multipartite quantum correlations

    CERN Document Server

    Aolita, Leandro; Cabello, Adán; Acín, Antonio

    2011-01-01

    Local measurements on bipartite maximally entangled states can yield correlations that are maximally nonlocal, monogamous, and associated to fully random outcomes. This makes these states ideal for bipartite cryptographic tasks. Genuine-multipartite nonlocality constitutes a stronger notion of nonlocality that appears in the multipartite case. Maximal genuine-multipartite nonlocality, monogamy and full random outcomes are thus highly desired properties for multipartite correlations in intrinsically genuine-multipartite cryptographic scenarios. We prove that local measurements on Greenberger-Horne-Zeilinger states, for all local dimension and number of parts, can produce correlations that are fully genuine-multipartite nonlocal, monogamous and with fully random outcomes. A key ingredient in our proof is a multipartite chained Bell inequality detecting genuine-multipartite nonlocality, which we introduce. Finally, we discuss the applications of our results for intrinsically genuine-multipartite cryptographic pr...

  1. FILAMENTATION INSTABILITY OF LASER BEAMS IN NONLOCAL NONLINEAR MEDIA

    Institute of Scientific and Technical Information of China (English)

    文双春; 范滇元

    2001-01-01

    The filamentation instability of laser beams propagating in nonlocal nonlinear media is investigated. It is shown that the filamentation instability can occur in weakly nonlocal self-focusing media for any degree of nonlocality, and in defocusing media for the input light intensity exceeding a threshold related to the degree of nonlocality. A linear stability analysis is used to predict the initial growth rate of the instability. It is found that the nonlocality tends to suppress filamentation instability in self-focusing media and to stimulate filamentation instability in self-defocusing media. Numerical simulations confirm the results of the linear stability analysis and disclose a recurrence phenomenon in nonlocal self-focusing media analogous to the Fermi-Pasta-Ulam problem.

  2. Maximum quantum nonlocality between systems that never interacted

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, Adán, E-mail: adan@us.es [Departamento de Física Aplicada II, Universidad de Sevilla, E-41012 Sevilla (Spain)

    2012-12-03

    We show that there is a stronger form of bipartite quantum nonlocality in which systems that never interacted are as nonlocal as allowed by no-signaling. For this purpose, we first show that nonlocal boxes, theoretical objects that violate a bipartite Bell inequality as much as the no-signaling principle allows and which are physically impossible for most scenarios, are feasible if the two parties have 3 measurements with 4 outputs. Then we show that, in this case, entanglement swapping allows us to prepare mixtures of nonlocal boxes using systems that never interacted. -- Highlights: ► We show quantum correlations as nonlocal as allowed by no-signaling between systems that never interacted. ► We show that nonlocal boxes are feasible if 2 parties have 3 measurements with 4 outputs. ► Experimental implementations of 1 and 2 are proposed.

  3. Nonlocal modeling of granular flows down inclines.

    Science.gov (United States)

    Kamrin, Ken; Henann, David L

    2015-01-07

    Flows of granular media down a rough inclined plane demonstrate a number of nonlocal phenomena. We apply the recently proposed nonlocal granular fluidity model to this geometry and find that the model captures many of these effects. Utilizing the model's dynamical form, we obtain a formula for the critical stopping height of a layer of grains on an inclined surface. Using an existing parameter calibration for glass beads, the theoretical result compares quantitatively to existing experimental data for glass beads. This provides a stringent test of the model, whose previous validations focused on driven steady-flow problems. For layers thicker than the stopping height, the theoretical flow profiles display a thickness-dependent shape whose features are in agreement with previous discrete particle simulations. We also address the issue of the Froude number of the flows, which has been shown experimentally to collapse as a function of the ratio of layer thickness to stopping height. While the collapse is not obvious, two explanations emerge leading to a revisiting of the history of inertial rheology, which the nonlocal model references for its homogeneous flow response.

  4. Relativistic three-partite non-locality

    CERN Document Server

    Montakhab, A

    2015-01-01

    Bell-like inequalities have been used in order to distinguish non-local quantum pure states by various authors. The behavior of such inequalities under Lorentz transformation has been a source of debate and controversies in the past. In this paper, we consider the two most commonly studied three-particle pure states, that of W and GHZ states which exhibit distinctly different type of entanglement. We discuss the various types of three-particle inequalities used in previous studies and point to their corresponding shortcomings and strengths. Our main result is that if one uses Svetlichny's inequality as the main measure of non-locality and uses the same angles in the rest frame ($S$) as well as the moving frame ($S^{\\prime}$), then maximally violated inequality in $S$ will decrease in the moving frame, and will eventually lead to lack of non-locality ( i.e. satisfaction of inequality) in the $v \\rightarrow c$ limit. This is shown for both GHZ and W states and in two different configurations which are commonly ...

  5. Nonlocal Gravity and Structure in the Universe

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, Scott [Chicago U., Astron. Astrophys. Ctr.; Park, Sohyun [Penn State U., University Park, IGC

    2014-08-26

    The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and examine the predictions of nonlocal gravity for the evolution of structure in the universe, confronting the model with three tests: gravitational lensing, redshift space distortions, and the estimator of gravity $E_G$. Current data favor general relativity (GR) over nonlocal gravity: fixing primordial cosmology with the best fit parameters from Planck leads to weak lensing results favoring GR by 5.9 sigma; redshift space distortions measurements of the growth rate preferring GR by 7.8 sigma; and the single measurement of $E_G$ favoring GR, but by less than 1-sigma. The significance holds up even after the parameters are allowed to vary within Planck limits. The larger lesson is that a successful modified gravity model will likely have to suppress the growth of structure compared to general relativity.

  6. Theory of Nonlocal Point Transformations in General Relativity

    Directory of Open Access Journals (Sweden)

    Massimo Tessarotto

    2016-01-01

    Full Text Available A discussion of the functional setting customarily adopted in General Relativity (GR is proposed. This is based on the introduction of the notion of nonlocal point transformations (NLPTs. While allowing the extension of the traditional concept of GR-reference frame, NLPTs are important because they permit the explicit determination of the map between intrinsically different and generally curved space-times expressed in arbitrary coordinate systems. For this purpose in the paper the mathematical foundations of NLPT-theory are laid down and basic physical implications are considered. In particular, explicit applications of the theory are proposed, which concern (1 a solution to the so-called Einstein teleparallel problem in the framework of NLPT-theory; (2 the determination of the tensor transformation laws holding for the acceleration 4-tensor with respect to the group of NLPTs and the identification of NLPT-acceleration effects, namely, the relationship established via general NLPT between particle 4-acceleration tensors existing in different curved space-times; (3 the construction of the nonlocal transformation law connecting different diagonal metric tensors solution to the Einstein field equations; and (4 the diagonalization of nondiagonal metric tensors.

  7. Entanglement and Nonlocality in Infinite 1D Systems

    Science.gov (United States)

    Wang, Zizhu; Singh, Sukhwinder; Navascués, Miguel

    2017-06-01

    We consider the problem of detecting entanglement and nonlocality in one-dimensional (1D) infinite, translation-invariant (TI) systems when just near-neighbor information is available. This issue is deeper than one might think a priori, since, as we show, there exist instances of local separable states (classical boxes) which admit only entangled (nonclassical) TI extensions. We provide a simple characterization of the set of local states of multiseparable TI spin chains and construct a family of linear witnesses which can detect entanglement in infinite TI states from the nearest-neighbor reduced density matrix. Similarly, we prove that the set of classical TI boxes forms a polytope and devise a general procedure to generate all Bell inequalities which characterize it. Using an algorithm based on matrix product states, we show how some of them can be violated by distant parties conducting identical measurements on an infinite TI quantum state. All our results can be easily adapted to detect entanglement and nonlocality in large (finite, not TI) 1D condensed matter systems.

  8. Nonlocal Drag of Magnons in a Ferromagnetic Bilayer

    Science.gov (United States)

    Liu, Tianyu; Vignale, G.; Flatté, Michael E.

    2016-06-01

    Quantized spin waves, or magnons, in a magnetic insulator are assumed to interact weakly with the surroundings, and to flow with little dissipation or drag, producing exceptionally long diffusion lengths and relaxation times. In analogy to Coulomb drag in bilayer two-dimensional electron gases, in which the contribution of the Coulomb interaction to the electric resistivity is studied by measuring the interlayer resistivity (transresistivity), we predict a nonlocal drag of magnons in a ferromagnetic bilayer structure based on semiclassical Boltzmann equations. Nonlocal magnon drag depends on magnetic dipolar interactions between the layers and manifests in the magnon current transresistivity and the magnon thermal transresistivity, whereby a magnon current in one layer induces a chemical potential gradient and/or a temperature gradient in the other layer. The largest drag effect occurs when the magnon current flows parallel to the magnetization; however, for oblique magnon currents a large transverse current of magnons emerges. We examine the effect for practical parameters, and find that the predicted induced temperature gradient is readily observable.

  9. Local and nonlocal advection of a passive scalar

    Science.gov (United States)

    Scott, R. K.

    2006-11-01

    Passive and active scalar mixing is examined in a simple one-parameter family of two-dimensional flows based on quasi-geostrophic dynamics, in which the active scalar, the quasi-geostrophic potential vorticity, is confined to a single horizontal surface (so-called surface quasi-geostrophic dynamics) and in which a passive scalar field is also advected by the (horizontal, two-dimensional) velocity field at a finite distance from the surface. At large distances from the surface the flow is determined by the largest horizontal scales, the flow is spectrally nonlocal, and a chaotic advection-type regime dominates. At small distances, z, scaling arguments suggest a transition wavenumber kc˜1/2z, where the slope of the passive scalar spectrum changes from k-5/3, determined by local dynamics, to k-1, determined by nonlocal dynamics, analogous to the transition to a k-1 slope in the Batchelor regime in three-dimensional turbulence. Direct numerical simulations reproduce the qualitative aspects of this transition. Other characteristics of the simulated scalar fields, such as the relative dominance of coherent or filamentary structures, are also shown to depend strongly on the degree of locality.

  10. Complementarity in Genuine Nonlocality: A device independent outlook

    CERN Document Server

    Sami, Sasha; Chakrabarty, Indranil

    2016-01-01

    The notion of complementarity or mutually exclusiveness of physical processes has always been of keen interest to the physicists whether it came from the realms of quantum mechanical processes or it arose from the information processing tasks associated with quantum information theory. In this work we show that there exists a complementary relationship in terms of the genuine non-locality as a principle between a system and its subsystems. Our approach to this problem is a device independent approach which works irrespective of any theoretical setting. We consider Svetlichny games in a multiparty binary input and output scenario with a threshold value of the winning probability as a signature of genuine multiparty non locality. We analytically show that, in the Svetlichny games setup, there exists complementary relations between Svetlichny correlations of $n$ party and Svetlichny correlations of $k\\leq n$ parties within the no-signaling framework. In other words, in general non local theories, the genuine mul...

  11. On non-local representations of the ageing algebra

    Energy Technology Data Exchange (ETDEWEB)

    Henkel, Malte, E-mail: henkel@lpm.u-nancy.f [Groupe de Physique Statistique, Departement de Physique de la Matiere et des Materiaux, Institut Jean Lamour, Nancy Universite (UMR 7198-CNRS-UHP-INPL-UPVM) B.P. 70239, F-54506 Vandoeuvre les Nancy Cedex (France); Stoimenov, Stoimen [Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tsarigradsko chaussee, Blvd., BG-1784 Sofia (Bulgaria)

    2011-06-21

    The ageing algebra is a local dynamical symmetry of many ageing systems, far from equilibrium, and with a dynamical exponent z=2. Here, new representations for an integer dynamical exponent z=n are constructed, which act non-locally on the physical scaling operators. The new mathematical mechanism which makes the infinitesimal generators of the ageing algebra dynamical symmetries, is explicitly discussed for an n-dependent family of linear equations of motion for the order-parameter. Finite transformations are derived through the exponentiation of the infinitesimal generators and it is proposed to interpret them in terms of the transformation of distributions of spatio-temporal coordinates. The two-point functions which transform co-variantly under the new representations are computed, which quite distinct forms for n even and n odd. Depending on the sign of the dimensionful mass parameter, the two-point scaling functions either decay monotonously or in an oscillatory way towards zero.

  12. Pattern formation and coexistence domains for a nonlocal population dynamics

    CERN Document Server

    da Cunha, J A R; Oliveira, F A

    2011-01-01

    In this communication we propose a most general equation to study pattern formation for one-species population and their limit domains in systems of length L. To accomplish this we include non-locality in the growth and competition terms where the integral kernels are now depend on characteristic length parameters alpha and beta. Therefore, we derived a parameter space (alpha,beta) where it is possible to analyze a coexistence curve alpha*=alpha*(\\beta) which delimits domains for the existence (or not) of pattern formation in population dynamics systems. We show that this curve has an analogy with coexistence curve in classical thermodynamics and critical phenomena physics. We have successfully compared this model with experimental data for diffusion of Escherichia coli populations.

  13. Nonlocal quantum gravity and the size of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Reuter, M. [Institute of Physics, University of Mainz, Staudingerweg 7, 55099 Mainz (Germany); Saueressig, F. [Institute of Theoretical Physics, University of Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2004-06-01

    Motivated by the conjecture that the cosmological constant problem is solved by strong quantum effects in the infrared we use the exact flow equation of Quantum Einstein Gravity to determine the renormalization group behavior of a class of nonlocal effective actions. They consist of the Einstein-Hilbert term and a general nonlinear function F{sub k}(V) of the Euclidean spacetime volume V. For the V+V ln V-invariant the renormalization group running enormously suppresses the value of the renormalized curvature which results from Planck-size parameters specified at the Planck scale. One obtains very large, i.e., almost flat universes without finetuning the cosmological constant. A critical infrared fixed point is found where gravity is scale invariant. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  14. The non-local content of quantum operations

    CERN Document Server

    Collins, D; Popescu, S; Collins, Daniel; Linden, Noah; Popescu, Sandu

    2000-01-01

    We show that quantum operations on multi-particle systems have a non-local content; this mirrors the non-local content of quantum states. We introduce a general framework for discussing the non-local content of quantum operations, and give a number of examples. Quantitative relations between quantum actions and the entanglement and classical communication resources needed to implement these actions are also described. We also show how entanglement can catalyse classical communication from a quantum action.

  15. Proposal for revealing quantum nonlocality via local contextuality.

    Science.gov (United States)

    Cabello, Adán

    2010-06-04

    Two distant systems can exhibit quantum nonlocality even though the correlations between them admit a local model. This nonlocality can be revealed by testing extra correlations between successive measurements on one of the systems which do not admit a noncontextual model whatever the reduced state of this system is. This shows that quantum contextuality plays a fundamental role in quantum nonlocality, and allows an experimental test of the Kochen-Specker with locality theorem.

  16. Survey on nonlocal games and operator space theory

    Energy Technology Data Exchange (ETDEWEB)

    Palazuelos, Carlos, E-mail: cpalazue@mat.ucm.es [Instituto de Ciencias Matemáticas (ICMAT), Facultad de Ciencias Matemáticas, Universidad Complutense de Madrid, Madrid (Spain); Vidick, Thomas, E-mail: vidick@cms.caltech.edu [Department of Computing and Mathematical Sciences, California Institute of Technology, Pasadena, California 91125 (United States)

    2016-01-15

    This review article is concerned with a recently uncovered connection between operator spaces, a noncommutative extension of Banach spaces, and quantum nonlocality, a striking phenomenon which underlies many of the applications of quantum mechanics to information theory, cryptography, and algorithms. Using the framework of nonlocal games, we relate measures of the nonlocality of quantum mechanics to certain norms in the Banach and operator space categories. We survey recent results that exploit this connection to derive large violations of Bell inequalities, study the complexity of the classical and quantum values of games and their relation to Grothendieck inequalities, and quantify the nonlocality of different classes of entangled states.

  17. Implementation of nonlocal quantum swap operation on two entangled pairs

    Institute of Scientific and Technical Information of China (English)

    郑亦庄; 顾永建; 陈立冰; 郭光灿

    2002-01-01

    We propose a scheme for the implementation of nonlocal quantum swap operation on two spatially separated entangled pairs and we show that the operation can swap two qubits of these entangled pairs. We discuss the resourcesof the entangled qubits and classical communication bits required for the optimal implementation of the nonlocal quantum swap operation. We also put forward a scheme for probabilistic implementation of nonlocal swap operation via a nonmaximally entangled quantum channel. The probability of a successful nonlocal swap operation is obtained by introducing a collective unitary transformation.

  18. Nonlocality Sudden Birth and Transfer in System and Environment

    Institute of Scientific and Technical Information of China (English)

    QIU Liang

    2011-01-01

    Dynamics of the nonlocality measured by the violation of Svetlichny's Bell-type inequality is investigated in the non-Markovian model. The phenomenon of nonlocality sudden birth for the atoms and the reservoirs is obtained.The evolution of the nonlocality among the atoms or the reservoirs depends on the choice of the atom detuning from the cavity pseudomode, the cavity pseudomode decay and the rotation angles. For the small pseudomode decay in the near-resonance regime, the initial atomic nonlocality is completely transferred to the reservoirs ultimately.

  19. On a Nonlocal Problem Modelling Ohmic Heating in Planar Domains

    Institute of Scientific and Technical Information of China (English)

    Fei LIANG; Qi Lin LIU; Yu Xiang LI

    2013-01-01

    In this paper, we consider the nonlocal problem of the form ut-△u=λe-u/(∫Ωe-udx)2,x∈Ω,t>0 and the associated nonlocal stationary problem -△v=λe-v/(∫Ωe-vdx)2,x∈Ω, where A is a positive parameter. For Ω to be an annulus, we prove that the nonlocal stationary problem has a unique solution if and only if λ < 2|(6)Ω|2, and for A = 2|(6)Ω|2, the solution of the nonlocal parabolic problem grows up globally to infinity as t → ∞.

  20. Vibration analysis of nonlocal beams made of functionally graded material in thermal environment

    Science.gov (United States)

    Ebrahimi, Farzad; Reza Barati, Mohammad

    2016-08-01

    In this paper, thermal vibration behavior of functionally graded (FG) nanobeams exposed to various kinds of thermo-mechanical loading including uniform, linear and non-linear temperature rise embedded in a two-parameter elastic foundation are investigated based on third-order shear deformation beam theory which considers the influence of shear deformation without the need to shear correction factors. Material properties of FG nanobeam are supposed to be temperature-dependent and vary gradually along the thickness according to the Mori-Tanaka homogenization scheme. The influence of small scale is captured based on nonlocal elasticity theory of Eringen. The nonlocal equations of motion are derived through Hamilton's principle and they are solved applying analytical solution. The comparison of the obtained results is conducted with those of nonlocal Euler-Bernoulli beam theory and it is demonstrated that the proposed modeling predicts correctly the vibration responses of FG nanobeams. The influences of some parameters including gradient index, nonlocal parameter, mode number, foundation parameters and thermal loading on the thermo-mechanical vibration characteristics of the FG nanobeams are presented.

  1. Non-local and nonlinear background suppression method controlled by multi-scale clutter metric

    Science.gov (United States)

    Gong, Jinnan; Hou, Qingyu; Zhang, Wei; Zhi, Xiyang

    2015-07-01

    To improve the detection performance for non-morphological multi-scale target in IR image containing complex cloud clutter, on basis of cloud scenario self-similarity feature, a non-local and nonlinear background suppression algorithm controlled by multi-scale clutter metric is presented. According to the classical achievements on cloud structure, self-similarity and relativity of cloud clutter on image for target detection is deeply analyzed by classical indicators firstly. Then we establish multi-scale clutter metric method based on LoG operator to describe scenes feature for controlled suppression method. After that, non-local means based on optimal strength similarity metric as non-local processing, and multi-scale median filter and on minimum gradient direction as local processing are set up. Finally linear fusing principle adopting clutter metric for local and non-local processing is put forward. Experimental results by two kinds of infrared imageries show that compared with classical and similar methods, the proposed method solves the existing problems of targets energy attenuation and suppression degradation in strongly evolving regions in previous methods. By evaluating indicators, the proposed method has a superior background suppression performance by increasing the BSF and ISCR 2 times at least.

  2. Nonlocal electron-phonon coupling in the pentacene crystal: Beyond the Γ-point approximation

    KAUST Repository

    Yi, Yuanping

    2012-01-01

    There is currently increasing interest in understanding the impact of the nonlocal (Peierls-type) electron-phonon mechanism on charge transport in organic molecular semiconductors. Most estimates of the non-local coupling constants reported in the literature are based on the Γ-point phonon modes. Here, the influence of phonon modes spanning the entire Brillouin zone (phonon dispersion) on the nonlocal electron-phonon couplings is investigated for the pentacene crystal. The phonon modes are obtained by using a supercell approach. The results underline that the overall nonlocal couplings are substantially underestimated by calculations taking sole account of the phonons at the Γ point of the unit cell. The variance of the transfer integrals based on Γ-point normal-mode calculations at room temperature is underestimated in some cases by 40% for herringbone-type dimers and by over 80% for cofacial dimers. Our calculations show that the overall coupling is somewhat larger for holes than for electrons. The results also suggest that the interactions of charge carriers (both electrons and holes) with acoustic and optical phonons are comparable. Therefore, an adequate description of the charge-transport properties in pentacene and similar systems requires that these two electron-phonon coupling mechanisms be treated on the same footing. © 2012 American Institute of Physics.

  3. Critical dynamics of a nonlocal model and critical behavior of perovskite manganites.

    Science.gov (United States)

    Singh, Rohit; Dutta, Kishore; Nandy, Malay K

    2016-05-01

    We investigate the nonconserved critical dynamics of a nonlocal model Hamiltonian incorporating screened long-range interactions in the quartic term. Employing dynamic renormalization group analysis at one-loop order, we calculate the dynamic critical exponent z=2+εf_{1}(σ,κ,n)+O(ε^{2}) and the linewidth exponent w=-σ+εf_{2}(σ,κ,n)+O(ε^{2}) in the leading order of ε, where ε=4-d+2σ, with d the space dimension, n the number of components in the order parameter, and σ and κ the parameters coming from the nonlocal interaction term. The resulting values of linewidth exponent w for a wide range of σ is found to be in good agreement with the existing experimental estimates from spin relaxation measurements in perovskite manganite samples.

  4. Blowup Analysis for a Nonlocal Diffusion Equation with Reaction and Absorption

    Directory of Open Access Journals (Sweden)

    Yulan Wang

    2012-01-01

    Full Text Available We investigate a nonlocal reaction diffusion equation with absorption under Neumann boundary. We obtain optimal conditions on the exponents of the reaction and absorption terms for the existence of solutions blowing up in finite time, or for the global existence and boundedness of all solutions. For the blowup solutions, we also study the blowup rate estimates and the localization of blowup set. Moreover, we show some numerical experiments which illustrate our results.

  5. On the nonlocal Fisher-KPP equation: steady states, spreading speed and global bounds

    Science.gov (United States)

    Hamel, François; Ryzhik, Lenya

    2014-11-01

    We consider the Fisher-KPP (for Kolmogorov-Petrovsky-Piskunov) equation with a nonlocal interaction term. We establish a condition on the interaction that allows for existence of non-constant periodic solutions, and prove uniform upper bounds for the solutions of the Cauchy problem, as well as upper and lower bounds on the spreading rate of the solutions with compactly supported initial data.

  6. A geometric theory of non-local two-qubit operations

    CERN Document Server

    Zhang, J; Whaley, K B; Sastry, S; Zhang, Jun; Vala, Jiri; Sastry, Shankar

    2003-01-01

    We study non-local two-qubit operations from a geometric perspective. By applying a Cartan decomposition to su(4), we find that the geometric structure of non-local gates is a 3-Torus. We derive the invariants for local transformations, and connect these local invariants to the coordinates of the 3-Torus. Since different points on the 3-Torus may correspond to the same local equivalence class, we use the Weyl group theory to reduce the symmetry. We show that the local equivalence classes of two-qubit gates are in one-to-one correspondence with the points in a tetrahedron except on the base. We then study the properties of perfect entanglers, that is, the two-qubit operations that can generate maximally entangled states from some initially separable states. We provide criteria to determine whether a given two-qubit gate is a perfect entangler and establish a geometric description of perfect entanglers by making use of the tetrahedral representation of non-local gates. We find that exactly half the non-local ga...

  7. Nonlocal entanglement and noise between spin qubits induced by Majorana bound states

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Sha-Sha [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Lü, Hai-Feng, E-mail: lvhf81@gmail.com [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Yang, Hua-Jun [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Guo, Yong [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Zhang, Huai-Wu [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-01-23

    We propose a scheme to create nonlocal entanglement between two spatially separated electron spin qubits by coupling them with a pair of Majorana bound states (MBSs). The spin qubits are based on the spins of electrons confined in quantum dots. It is shown that spin entanglement between two dots could be generated by the nonlocality of MBSs. We also demonstrate that in the transport regime, the current noise cross correlation can serve as a good indicator of spin entanglement. The Majorana-dot coupling not only induces an indirect interaction between qubits, but also produces spin localization in the strong coupling limit. These two competing effects lead to a nonmonotonic dependence of current cross-correlation and entanglement on the Majorana-qubit coupling strength. - Highlights: • We propose a scheme to create nonlocal entanglement between two spatially separated electron spin qubits by coupling them with a pair of Majorana bound states. • Spin entanglement between two dots could be generated by the nonlocality of MBSs. • The current noise cross correlation can serve as a good indicator of spin entanglement.

  8. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Duc; Moses, Gregory [University of Wisconsin—Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Delettrez, Jacques [Laboratory for Laser Energetics of the University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2015-08-15

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester.

  9. Influence of thermal and surface effects on vibration behavior of nonlocal rotating Timoshenko nanobeam

    Science.gov (United States)

    Ghadiri, Majid; Shafiei, Navvab; Akbarshahi, Amir

    2016-07-01

    This paper is proposed to study the free vibration of a rotating Timoshenko nanobeam based on the nonlocal theory considering thermal and surface elasticity effects. The governing equations and the related boundary conditions are derived using the Hamilton's principle. In order to solve the problem, generalized differential quadrature method is applied to discretize the governing differential equations corresponding to clamped-simply and clamped-free boundary conditions. In this article, the influences of some parameters such as nonlocal parameter, angular velocity, thickness of the nanobeam, and thermal and surface elasticity effects on the free vibration of the rotating nanobeam are investigated, and the results are compared for different boundary conditions. The results show that the surface effect and the nonlocal parameter and the temperature changes have significant roles, and they should not be ignored in the vibrational study of rotating nanobeams. Also, the angular velocity and the hub radius have more significant roles than temperature change effects on the nondimensional frequency. It is found that the nonlocal parameter behavior and the temperature change behavior on the frequency are different in the first mode for the rotating cantilever nanobeam.

  10. Local and Nonlocal Advected Invariants and Helicities in Magnetohydrodynamics and Gas Dynamics II: Noether's Theorems and Casimirs

    CERN Document Server

    Webb, G M; McKenzie, J F; Hu, Q; Zank, G P

    2013-01-01

    Conservation laws in ideal gas dynamics and magnetohydrodynamics (MHD) associated with fluid relabelling symmetries are derived using Noether's first and second theorems. Lie dragged invariants are discussed in terms of the MHD Casimirs. A nonlocal conservation law for fluid helicity applicable for a non-barotropic fluid involving Clebsch variables is derived using Noether's theorem, in conjunction with a fluid relabelling symmetry and a gauge transformation. A nonlocal cross helicity conservation law involving Clebsch potentials, and the MHD energy conservation law are derived by the same method. An Euler Poincar\\'e variational approach is also used to derive conservation laws associated with fluid relabelling symmetries using Noether's second theorem.

  11. Nonlocalization of Nonlocal Symmetry and Symmetry Reductions of the Burgers Equation

    Institute of Scientific and Technical Information of China (English)

    金艳; 贾曼; 楼森岳

    2012-01-01

    Symmetry reduction method is one of the best ways to find exact solutions. In this paper, we study the possibility of symmetry reductions of the well known Burgers equation including the nonlocal symmetry. The related new group Jnvariant solutions are obtained. Especially, the interactions among solitons, Airy waves, and Kummer waves are explicitly given.

  12. Existence and Uniqueness of Solutions for the System of Nonlinear Fractional Differential Equations with Nonlocal and Integral Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Allaberen Ashyralyev

    2012-01-01

    Full Text Available In the present study, the nonlocal and integral boundary value problems for the system of nonlinear fractional differential equations involving the Caputo fractional derivative are investigated. Theorems on existence and uniqueness of a solution are established under some sufficient conditions on nonlinear terms. A simple example of application of the main result of this paper is presented.

  13. Assimilation of GPS Refractivity from FORMOSAT-3/COSMIC Using a Nonlocal Operator with WRF 3DVAR and Its Impact on the Prediction of a Typhoon Event

    Directory of Open Access Journals (Sweden)

    Shu-Ya Chen

    2009-01-01

    Full Text Available A nonlocal observation operator has been developed to assimilate GPS radio occultation (RO refractivity with WRF 3DVAR. For simplicity, in the past GPS RO refractivity was often assimilated using a local observation operator with the assumption that the GPS RO observation was representative of amodel local point. Such an operator did not take into account the effects of horizontal inhomogeneity on the derived GPS RO refractivity. In order to more accurately model the observables, Sokolovskiy et al. (2005a developed a nonlocal observation operator, which would take into account the effects of horizontal inhomogeneity on GPS RO measurements. This nonlocal observation operator calculates the integrated amount of the model refractivity along the ray paths centered at the perigee points. For comparative purposes, the nonlocal observation operator can be simplified by limiting the length of integration near the RO point. This is called the "local operator variant", which is equivalent to the original local operator except that the original one is performed with fixed tangent points at observation levels. For computational efficiency, assimilation using both the nonlocal operator and local operator variant now is performed with smear tangent points at the mean height of each model vertical level. In this study, the statistics of observation errors using both local and nonlocal operators were estimated based on WRF simulations. The observation errors produced by the nonlocal operator are about two times smaller than those generated by the local operator and in agreement with Sokolovskiy et al. (2005b.

  14. AC-conductance of a non-local Thirring model

    Energy Technology Data Exchange (ETDEWEB)

    Trobo, Marta Liliana; Von Reichenbach, Maria Cecilia [Universidad Nacional de La Plata (UNLP) (Argentina); Barci, Daniel G. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)]|[Illinois Univ., Urbana, IL (United States); Medeiros Neto, J.F. de [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

    2000-07-01

    Full text follows: In recent years renewed interest has arisen in the study of low dimensional field theories. In particular, research on the one dimensional (1-d) fermionic gas has been very active, mainly due to the actual nano-fabrication of the so called quantum wires and their relevance for low dimensional condensed matter physics as, for instance, the quantum Hall effect and high-T{sub c} superconductivity. Experimental and theoretical investigations of the AC-transport phenomena in nano-structures are of profound scientific interest since they provide insight into the behavior of quantum systems. In this frame, we consider a field theoretical approach that can be used to describe a system of 1-d strongly correlated particles in the low transferred momentum limit. We study a non-local and non-covariant version of the Thirring model where the fermionic densities and currents are coupled through bilocal, distance-dependent potentials which describe the forward scattering processes. We apply the functional bosonization formalism, a very useful technique to understand the non-perturbative regime of strongly correlated one-dimensional fermionic systems, to this non local Thirring like model (NLTM). We are interesting in the transport properties of the system, in particular in the AC-conductance. To this end, we consider a NLTM in the presence of an external electromagnetic field. We obtain the AC-conductance of the model in terms of non-local potentials used to describe the interactions between fermionic currents. We also analyze the transport properties in the case in which weak couplings between fermionic currents and localized impurities are taken into account. (author)

  15. Global attractivity for nonlinear differential equations with a nonlocal term

    Directory of Open Access Journals (Sweden)

    Boumediene Abdellaoui

    2014-08-01

    Full Text Available In this article we analyze the dynamics of the problem $$\\displaylines{ x'(t=-(\\delta+\\beta(x(tx(t+\\theta\\int_{0}^{\\tau}f(ax(t-a\\beta(x(t-ada, \\quad t> \\tau, \\cr x(t=\\phi(t,\\quad 0 \\leq t\\leq \\tau, }$$ where $\\delta,\\theta$ are positive constants, and $\\beta, \\phi, f$ are positives continuous functions. The main results obtained in this paper are the following:

  16. Nonlocal Transport in the Reversed Field Pinch

    Energy Technology Data Exchange (ETDEWEB)

    Spizzo, G.; White, R. B.; Cappello, S.; Marrelli, L.

    2009-09-21

    Several heuristic models for nonlocal transport in plasmas have been developed, but they have had a limited possibility of detailed comparision with experimental data. Nonlocal aspects introduced by the existence of a known spectrum of relatively stable saturated tearing modes in a low current reversed field pinch offers a unique possibility for such a study. A numerical modelling of the magnetic structure and associated particle transport is carried out for the reversed-field pinch experiment at the Consorzio RFX, Padova, Italy. A reproduction of the tearing mode spectrum with a guiding center code1 reliably reproduces the observed soft X-ray tomography. Following particle trajectories in the stochastic magnetic field shows the transport across the unperturbed flux surfaces to be due to a spectrum of Levy flights, with the details of the spectrum position dependent. The resulting transport is subdiffusive, and cannot be described by Rechester-Rosenbluth diffusion, which depends on a random phase approximation. If one attempts to fit the local transport phenomenologically, the subdiffusion can be fit with a combination of diffusion and inward pinch2. It is found that whereas passing particles explore the stochastic field and hence participate in Levy flights, the trapped particles experience normal neoclassical diffusion. A two fluid nonlocal Montroll equation is used to model this transport, with a Levy flight defined as the motion of an ion during the period that the pitch has one sign. The necessary input to the Montroll equation consists of a time distribution for the Levy flights, given by the pitch angle scattering operator, and a distribution of the flight distances, determined numerically using a guiding center code. Results are compared to experiment. The relation of this formulation to fractional kinetics is also described.

  17. Nonlocal Crowd Dynamics Models for several Populations

    CERN Document Server

    Colombo, Rinaldo M

    2011-01-01

    This paper develops the basic analytical theory related to some recently introduced crowd dynamics models. Where well posedness was known only locally in time, it is here extended to all of $\\reali^+$. The results on the stability with respect to the equations are improved. Moreover, here the case of several populations is considered, obtaining the well posedness of systems of multi-D non-local conservation laws. The basic analytical tools are provided by the classical Kruzkov theory of scalar conservation laws in several space dimensions.

  18. The nonlocal elastomagnetoelectrostatics of disordered micropolar media

    Energy Technology Data Exchange (ETDEWEB)

    Kabychenkov, A. F.; Lisiovskii, F. V., E-mail: lisf@rambler.ru [Russian Academy of Sciences, Kotel’nikov Institute of Radio Engineering and Electronics (Fryazino Branch) (Russian Federation)

    2016-08-15

    The interactions of electric, magnetic, and elastic subsystems in nonlinear disordered micropolar media that possess a bending–torsion tensor and an nonsymmetric strain tensor have been studied in the framework of phenomenological elastomagnetoelectrostatics. A system of nonlinear equations for determining the ground state of these media has been obtained by the variational method. It is shown that nonuniform external and internal rotations not only create elastic stresses, but also generate additional electric and magnetic fields, while nonuniform elastic stresses and external fields induce internal rotations. The nonlocal character of the micropolar media significantly influences elementary excitations and nonlinear dynamic processes.

  19. Non-local modeling of materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2002-01-01

    Numerical studies of non-local plasticity effects on different materials and problems are carried out. Two different theories are used. One is of lower order in that it retains the structure of a conventional plasticity boundary value problem, while the other is of higher order and employs higher...... order stresses as work conjugates to higher order strains and uses higher order boundary conditions. The influence of internal material length parameters is studied, and the effects of higher order boundary conditions are analyzed. The focus of the thesis is on metal-matrix composites, and non...

  20. Uncertainty, non-locality and Bell's inequality

    CERN Document Server

    Pati, A K

    1998-01-01

    We derive a Bell-like inequality involving all correlations in local observables with uncertainty free states and show that the inequality is violated in quantum mechanics for EPR and GHZ states. If the uncertainties are allowed in local observables then the statistical predictions of hidden variable theory is well respected in quantum world. We argue that the uncertainties play a key role in understanding the non-locality issues in quantum world. Thus we can not rule out the possibility that a local, realistic hidden variable theory with statistical uncertainties in the observables might reproduce all the results of quantum theory.