Long radial coherence of electron temperature fluctuations in non-local transport in HL-2A plasmas

The dynamics of long-wavelength(kθ<1.4 cm^(-1)),broadband(20 kHz–200 kHz)electron temperature fluctuations(Te/Te)of plasmas in gas-puff experiments are observed for the first time in HL-2A tokamak.In a relatively low density(ne(0)■0.91×10^(19)m^(-3)–1.20×10^(19)m^(-3))scenario,after gas-puffing the core temperature increases and the edge temperature drops.On the contrary,temperature fluctuation drops at the core and increases at the edge.Analyses show the non-local emergence is accompanied with a long radial coherent length of turbulent fluctuations.While in a higher density(ne(0)?1.83×10^(19)m^(-3)–2.02×10^(19)m^(-3))scenario,the phenomena are not observed.Furthermore,compelling evidence indicates that E×B shear serves as a substantial contributor to this extensive radial interaction.This finding offers a direct explanatory link to the intriguing core-heating phenomenon witnessed within the realm of non-local transport.

Fresnel Equations Derived Using a Non-Local Hidden-Variable Particle Theory

Problem: The Fresnel equations describe the proportions of reflected and transmitted light from a surface, and are conventionally derived from wave theory continuum mechanics. Particle-based derivations of the Fresnel equations appear not to exist. Approach: The objective of this work was to derive the basic optical laws from first principles from a particle basis. The particle model used was the Cordus theory, a type of non-local hidden-variable (NLHV) theory that predicts specific substructures to the photon and other particles. Findings: The theory explains the origin of the orthogonal electrostatic and magnetic fields, and re-derives the refraction and reflection laws including Snell’s law and critical angle, and the Fresnel equations for s and p-polarisation. These formulations are identical to those produced by electromagnetic wave theory. Contribution: The work provides a comprehensive derivation and physical explanation of the basic optical laws, which appears not to have previously been shown from a particle basis. Implications: The primary implications are for suggesting routes for the theoretical advancement of fundamental physics. The Cordus NLHV particle theory explains optical phenomena, yet it also explains other physical phenomena including some otherwise only accessible through quantum mechanics (such as the electron spin g-factor) and general relativity (including the Lorentz and relativistic Doppler). It also provides solutions for phenomena of unknown causation, such as asymmetrical baryogenesis, unification of the interactions, and reasons for nuclide stability/instability. Consequently, the implication is that NLHV theories have the potential to represent a deeper physics that may underpin and unify quantum mechanics, general relativity, and wave theory.

High performance“non-local”generic face reconstruction model using the lightweight Speckle-Transformer(SpT)UNet

Significant progress has been made in computational imaging(CI),in which deep convolutional neural networks(CNNs)have demonstrated that sparse speckle patterns can be reconstructed.However,due to the limited“local”kernel size of the convolutional operator,for the spatially dense patterns,such as the generic face images,the performance of CNNs is limited.Here,we propose a“non-local”model,termed the Speckle-Transformer(SpT)UNet,for speckle feature extraction of generic face images.It is worth noting that the lightweight SpT UNet reveals a high efficiency and strong comparative performance with Pearson Correlation Coefficient(PCC),and structural similarity measure(SSIM)exceeding 0.989,and 0.950,respectively.

Validity of non-local mean filter and novel denoising method

Background Image denoising is an important topic in the digital image processing field.This study theoretically investigates the validity of the classical nonlocal mean filter(NLM)for removing Gaussian noise from a novel statistical perspective.Method By considering the restored image as an estimator of the clear image from a statistical perspective,we gradually analyze the unbiasedness and effectiveness of the restored value obtained by the NLM filter.Subsequently,we propose an improved NLM algorithm called the clustering-based NLM filter that is derived from the conditions obtained through the theoretical analysis.The proposed filter attempts to restore an ideal value using the approximately constant intensities obtained by the image clustering process.In this study,we adopt a mixed probability model on a prefiltered image to generate an estimator of the ideal clustered components.Result The experiment yields improved peak signal-to-noise ratio values and visual results upon the removal of Gaussian noise.Conclusion However,the considerable practical performance of our filter demonstrates that our method is theoretically acceptable as it can effectively estimate ideal images.

基于Non-local的腰椎间盘突出患者多裂肌分割方法

为实现腰椎间盘突出患者多裂肌病灶部位的精确分割,提出了一种基于Non-local的腰椎间盘突出患者多裂肌分割方法。以U-Net网络为基础,通过构造混合池化卷积来代替编码器传统的卷积模块,以提高全局特征与局部特征之间的相关性并融合网络高低维特征,增强了网络提取多裂肌特征的能力。然后,在网络的中间部署了一个由2个级联卷积组成的卷积模块。最后,经过由Non-local模块和3×3的卷积构成的解码器,通过引入注意力机制来更加关注目标的特征并抑制不必要的特征和噪音,从而提高模型的性能。实验结果表明,本方法与经典U-Net算法相比,Dice系数提升了9.5%,Jaccard相似系数提升了11.3%,Hausdorff Distance下降了74.6%。该方法提高了多裂肌脂肪浸润部位的分割精度,为腰椎间盘突出患者多裂肌病灶部位的分割提供了一种有效的方法。

基于Non-Local means滤波的雾天降质图像恢复算法

针对目前去雾算法易导致边缘晕环效应、边缘轮廓及景物特征比较模糊问题,提出了一种景深等先验信息未知条件下基于Non-Local means滤波的雾天降质图像恢复算法。首先,根据大气散射模型将经典的场景深度估计转化为大气面纱以及天空亮度估计,避免难求的场景深度图;然后,对雾天降质图像进行雾气平均化预处理,经过预处理图像平均亮度变小;其次,依据大气面纱的边缘跟雾天图像的低频具有大的相似性,采用Non-Localmeans滤波算法估计大气面纱模型;最后,为了使恢复图像的亮度跟色度都更加接近晴天图像,进行防止对比度放大的平滑与色度调整处理。通过与已有实验结果对比表明,提出的算法可以获得更精确的大气面纱,恢复图像不但边缘轮廓及景物特征都比较清楚,而且可有效抑制边缘晕环效应。

On the non-local priors for sparsity selection in high-dimensional Gaussian DAG models

We consider sparsity selection for the Cholesky factor L of the inverse covariance matrix in high-dimensional Gaussian DAG models.The sparsity is induced over the space of L via non-local priors,namely the product moment(pMOM)prior[Johnson,V.,&Rossell,D.(2012).Bayesian model selection in high-dimensional settings.Journal of the American Statistical Asso-ciation,107(498),649-660.https://doi.org/10.1080/01621459.2012.682536]and the hierarchi-cal hyper-pMOM prior[Cao,X.,Khare,K.,&Ghosh,M.(2020).High-dimensional posterior consistency for hierarchical non-local priors in regression.Bayesian Analysis,15(1),241-262.https://doi.org/10.1214/19-BA1154].We establish model selection consistency for Cholesky fac-tor under more relaxed conditions compared to those in the literature and implement an efficient MCMC algorithm for parallel selecting the sparsity pattern for each column of L.We demonstrate the validity of our theoretical results via numerical simulations,and also use further simulations to demonstrate that our sparsity selection approach is competitive with existing methods.

基于non-local先验的贝叶斯变量选择方法及其在高维数据分析中的应用

目的对高维数据进行变量筛选并构建预测模型是组学数据分析的研究热点之一。本研究旨在为结局为二分类变量的高维组学数据筛选自变量并构建预测结局的稀疏统计模型。方法本研究通过模拟研究和实例分析阐释基于non-local先验的贝叶斯变量选择方法--乘积逆矩先验(product inverse moment,piMOM)相较于惩罚类方法ISIS-光滑平切绝对偏差(iterative sure independence screening-smoothly clipped absolute deviation,ISIS-SCAD)和ISIS-最小最大凹惩罚(iterative sure independence screening-minimax concave penalty,ISIS-MCP)在高维数据中变量筛选及其预测效果的性能优劣。结果模拟研究发现:在高维的情况下,经piMOM、ISIS-SCAD和ISIS-MCP方法筛选所得变量的平均真阳性数和受试者工作特征曲线下面积(AUC,area under curve)基本相等,ISIS-SCAD、ISIS-MCP的平均假阳性数、回归系数均方误差以及预测均方误差明显高于基于non-local先验的贝叶斯变量方法所获得的对应值。piMOM方法分析弥漫大B细胞淋巴瘤实例数据共识别5个有意义的基因,AUC为0.996;ISIS-SCAD识别7个基因,AUC为0.975;ISIS-MCP识别7个基因,AUC为0.968。结论在模型选择相合性和预测准确性方面,piMOM方法与ISIS-SCAD和ISIS-MCP相比,具有优势,在一定意义上可有效控制假阳性率。

GURTIN-TYPE VARIATIONAL PRINCIPLES FOR DYNAMICS OF A NON-LOCAL THERMAL EQUILIBRIUM SATURATED POROUS MEDIUM

Based on the porous media theory and by taking into account the efects of the pore fuid viscidity, energy exchanges due to the additional thermal conduction and convection between solid and fuid phases, a mathematical model for the dynamic-thermo-hydro-mechanical coupling of a non-local thermal equilibrium fuid-saturated porous medium, in which the two constituents are assumed to be incompressible and immiscible, is established under the assumption of small de- formation of the solid phase, small velocity of the fuid phase and small temperature changes of the two constituents. The mathematical model of a local thermal equilibrium fuid-saturated porous medium can be obtained directly from the above one. Several Gurtin-type variational principles, especially Hu-Washizu type variational principles, for the initial boundary value problems of dy- namic and quasi-static responses are presented. It should be pointed out that these variational principles can be degenerated easily into the case of isothermal incompressible fuid-saturated elastic porous media, which have been discussed previously.

Surface effect and non-local elasticity in wave propagation of functionally graded piezoelectric nano-rod excited to applied voltage

A non-local solution for a functionally graded piezoelectric nano-rod is pre- sented by accounting the surface effect. This solution is used to evaluate the charac- teristics of the wave propagation in the rod structure. The model is loaded under a two-dimensional （2D） electric potential and an initially applied voltage at the top of the rod. The mechanical and electrical properties are assumed to be variable along the thick- ness direction of the rod according to the power law. The Hamilton principle is used to derive the governing differential equations of the electromechanical system. The effects of some important parameters such as the applied voltage and gradation of the material properties on the wave characteristics of the rod are studied.

Random noise suppression for seismic data using a non-local Bayes algorithm

For random noise suppression of seismic data, we present a non-local Bayes （NL- Bayes） filtering algorithm. The NL-Bayes algorithm uses the Gaussian model instead of the weighted average of all similar patches in the NL-means algorithm to reduce the fuzzy of structural details, thereby improving the denoising performance. In the denoising process of seismic data, the size and the number of patches in the Gaussian model are adaptively calculated according to the standard deviation of noise. The NL-Bayes algorithm requires two iterations to complete seismic data denoising, but the second iteration makes use of denoised seismic data from the first iteration to calculate the better mean and covariance of the patch Gaussian model for improving the similarity of patches and achieving the purpose of denoising. Tests with synthetic and real data sets demonstrate that the NL-Bayes algorithm can effectively improve the SNR and preserve the fidelity of seismic data.

NON-LOCAL MODELING ON MACROSCOPIC DOMAIN PATTERNS IN PHASE TRANSFORMATION OF NiTi TUBES

Recent experiments revealed many new phenomena of the macroscopic domain patterns in the stress-induced phase transformation of a superelastic polycrystalline NiTi tube during tensile loading. The new phenomena include deformation instability with the formation of a helical domain, domain topology transition from helix to cylinder, domain-front branching and loading-path dependence of domain patterns. In this paper, we model the polycrystal as an elastic continuum with nonconvex strain energy and adopt the non-local strain gradient energy to account for the energy of the diffusive domain front. We simulate the equilibrium domain patterns and their evolution in the tubes under tensile loading by a non-local Finite Element Method （FEM）. It is revealed that the observed loading-path dependence and topology transition of do- main patterns are due to the thermodynamic metastability of the tube system. The computation also shows that the tube-wall thickness has a significant effect on the domain patterns： with fixed material properties and interfacial energy density, a large tube-wall thickness leads to a long and slim helical domain and a severe branching of the cylindrical-domain front.

ANALYSIS OF THE DYNAMIC BEHAVIOR OF A GRIFFITH PERMEABLE CRACK IN PIEZOELECTRIC MATERIALS WITH THE NON-LOCAL THEORY

The dynamic behavior of a Griffith permeable crack under harmonic anti-plane shear waves in the piezoelectric materials is investigated by use of the non-local theory. To overcome the mathematical difficulties, a one-dimensional non-local kernel is used instead of a two-dimensional one for the anti-plane dynamic problem to obtain the stress and the electric displacement near the crack tips. By means of Fourier transform, the problem can be solved with a pair of dual integral equations that the unknown variable is the jump of the displacement across the crack surfaces. These equations are solved with the Schmidt method and numerical examples are provided. Contrary to the previous results, it is found that no stress and electric displacement singularities are present at the crack tip. The finite hoop stress and the electric displacement depend on the crack length, the lattice parameter of the materials and the circle frequency of the incident waves. This enables us to employ the maximum stress hypothesis to deal with fracture problems in a natural way.

Fast Non-Local Means Algorithm Based on Krawtchouk Moments

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 Euclidean 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 antinoise 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.

Investigation of the crack problem in non-local piezoelectric materials under combined electromechanical loadings

The present investigation of the crack problem in piezoelectric materials is performed based on the non-local theory. After some manipulations, the impermeable crack, the permeable crack （the crack gap is full of NaCI solution）, and the semi-permeable crack （the crack gap is full of air or silicon oil） are reduced to a uniform formulation by assuming the normal electric displacement on the crack surfaces to be an unknown variable. Thus, a triple integral equation with the unknown normal electric displacement is established. By using the Newton iterative method and solving the triple integral equation, it is found that the normal electric displacement on the crack surfaces is no longer a constant as determined by previous studies, rather, it depends upon the remote combined electromechanical loadings. Numerical results of the stresses and electric displacement fields show that there are no singularities at the crack tips so that the stresses remain finite. It is of great significance that the concrete electric boundary condition on the crack surfaces exerts significant influence on the near-tip fields and in this way plays an important role in evaluating the crack stability in the non-local piezoelectric materials. More specifically, the impermeable crack model always overestimates the finite stresses at the crack tips, whereas the permeable crack model always underestimates them.

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

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-Harm （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.

Improved Non-Local Means Algorithm for Image Denoising

Image denoising technology is one of the forelands in the field of computer graphic and computer vision. Non-local means method is one of the great performing methods which arouse tremendous research. In this paper, an improved weighted non-local means algorithm for image denoising is proposed. The non-local means denoising method replaces each pixel by the weighted average of pixels with the surrounding neighborhoods. The proposed method evaluates on testing images with various levels noise. Experimental results show that the algorithm improves the denoising performance.

Dynamic behavior of rectangular crack in three-dimensional orthotropic elastic medium by means of non-local theory

The dynamic behavior of a rectangular crack in a three-dimensional （3D） orthotropic elastic medium is investigated under a harmonic stress wave based on the non-local theory. The two-dimensional （2D） Fourier transform is applied, and the mixed- boundary value problems are converted into three pairs of dual integral equations with the unknown variables being the displacement jumps across the crack surfaces. The effects of the geometric shape of the rectangular crack, the circular frequency of the incident waves, and the lattice parameter of the orthotropic elastic medium on the dynamic stress field near the crack edges are analyzed. The present solution exhibits no stress singularity at the rectangular crack edges, and the dynamic stress field near the rectangular crack edges is finite.

INVESTIGATION OF THE SCATTERING OF ANTI-PLANE SHEAR WAVES BY TWO GRIFFITH CRACKS USING THE NON-LOCAL THEORY

In this paper, the scattering of harmonic antiplane shear waves bytwo finite cracks is studied using the non-local theory. The Fouriertransform is applied and a mixed boundary value prob- lem isformulated. Then a set of triple integral equations is solved using anew method, namely Schimidt's method. This method is more exact andmore reasonable than Erigen's for solving this Kind of problem. Theresult of the stress near the crack tip was obtained. Contrary to theclassical elas- Ticity solution, it is found that no stresssingularity is present at the crack tip, which can explain theProblem of macroscopic and microscopic mechanics.

Local edge direction based non-local means for image denoising

Classic non-local means (CNLM) algorithm uses the inherent self-similarity in images for noise removal. The denoised pixel value is estimated through the weighted average of all the pixels in its non-local neighborhood. In the CNLM algorithm, the differences between the pixel value and the distance of the pixel to the center are both taken into consideration to calculate the weighting coefficients. However, the Gaussian kernel cannot reflect the information of edge and structure due to its isotropy, and it has poor performance in flat regions. In this paper, an improved non-local means algorithm based on local edge direction is presented for image denoising. In edge and structure regions, the steering kernel regression (SKR) coefficients are used to calculate the weights, and in flat regions the average kernel is used. Experiments show that the proposed algorithm can effectively protect edge and structure while removing noises better when compared with the CNLM algorithm.