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By means of three dimensional high-resolution hybrid simulations we study the properties of the magnetic field spectral anisotropies near and beyond ion kinetic scales. By using both a Fourier analysis and a local analysis based on…

Solar and Stellar Astrophysics · Physics 2019-04-18 Simone Landi , Luca Franci , Emanuele Papini , Andrea Verdini , Lorenzo Matteini , Petr Hellinger

We investigate the relationship between ergodicity and asymptotic Gaussianity of isotropic spherical random fields, in the high-resolution (or high-frequency) limit. In particular, our results suggest that under a wide variety of…

Probability · Mathematics 2015-05-14 Domenico Marinucci , Giovanni Peccati

We propose a nonlinear ocean forecasting technique based on a combination of genetic algorithms and empirical orthogonal function (EOF) analysis. The method is used to forecast the space-time variability of the sea surface temperature (SST)…

A challenge in multivariate problems with discrete structures is the inclusion of prior information that may differ in each separate structure. A particular example of this is seismic amplitude versus angle (AVA) inversion to elastic…

Methodology · Statistics 2012-08-09 Erlend Aune , Daniel Simpson

We construct time dependent random fields on the sphere through coordinates change and subordination and we study the associated angular power spectrum. Some of this random fields arise naturally as solutions of partial differential…

Probability · Mathematics 2012-12-12 Mirko D'Ovidio

A higher-order multiscale analysis of spatial anisotropy in inertial range magnetohydrodynamic turbulence is presented using measurements from the STEREO spacecraft in fast ambient solar wind. We show for the first time that, when measuring…

Space Physics · Physics 2014-03-05 K. T. Osman , K. H. Kiyani , S. C. Chapman , B. Hnat

The problem of constructing flexible stochastic models to describe the variability in shape of solid particles is challenging. Natural objects often exhibit mono- or multi-fractal features, i.e. irregular shapes and self-similar patterns.…

Statistics Theory · Mathematics 2019-01-24 Alfredo Alegría

In many structured prediction problems, complex relationships between variables are compactly defined using graphical structures. The most prevalent graphical prediction methods---probabilistic graphical models and large margin…

Machine Learning · Statistics 2018-11-08 Rizal Fathony , Ashkan Rezaei , Mohammad Ali Bashiri , Xinhua Zhang , Brian D. Ziebart

We measure the local anisotropy of numerically simulated strong Alfv\'enic turbulence with respect to two local, physically relevant directions: along the local mean magnetic field and along the local direction of one of the fluctuating…

Solar and Stellar Astrophysics · Physics 2016-04-20 A. Mallet , A. A. Schekochihin , B. D. G. Chandran , C. H. K. Chen , T. S. Horbury , R. T. Wicks , C. C. Greenan

We construct general anisotropic cosmological scenarios governed by an $f(R)$ gravitational sector. Focusing then on Kantowski-Sachs geometries in the case of $R^n$-gravity, and modelling the matter content as a perfect fluid, we perform a…

General Relativity and Quantum Cosmology · Physics 2011-08-19 Genly Leon , Emmanuel N. Saridakis

Gaussian Conditional Random Fields (GCRF), as a structured regression model, is designed to achieve higher regression accuracy than unstructured predictors at the expense of execution time, taking into account the objects similarities and…

Machine Learning · Computer Science 2019-09-04 Milan Bašić , Branko Arsić , Zoran Obradović

High resolution maps of the anisotropy of the microwave sky will yield invaluable clues as to the mechanisms involved in cosmic structure formation. One fundamental question they should answer is whether the fluctuations were Gaussian…

High Energy Physics - Phenomenology · Physics 2009-10-22 David Coulson , Pedro Ferreira , Paul Graham , Neil Turok

A model of the passive vector quantity advected by a Gaussian time-decorrelated self-similar velocity field is studied; the effects of pressure and large-scale anisotropy are discussed. The inertial-range behavior of the pair correlation…

Chaotic Dynamics · Physics 2009-11-07 L. Ts. Adzhemyan , N. V. Antonov , A. V. Runov

Identifying the anisotropies in a cosmologically sourced stochastic gravitational wave background (SGWB) would be of significance in shedding light on the nature of primordial inhomogeneities. For example, if SGWB carries isocurvature…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-18 Yanou Cui , Soubhik Kumar , Raman Sundrum , Yuhsin Tsai

The variance reduction speed of physically-based rendering is heavily affected by the adopted importance sampling technique. In this paper we propose a novel online framework to learn the spatial-varying density model with a single small…

Computer Vision and Pattern Recognition · Computer Science 2024-02-28 Jiawei Huang , Akito Iizuka , Hajime Tanaka , Taku Komura , Yoshifumi Kitamura

Gaussian processes (GPs) are commonplace in spatial statistics. Although many non-stationary models have been developed, there is arguably a lack of flexibility compared to equipping each location with its own parameters. However, the…

Machine Learning · Statistics 2018-07-19 Leo L. Duan , Xia Wang , Rhonda D. Szczesniak

Autoencoders and generative neural network models have recently gained popularity in fluid mechanics due to their spontaneity and low processing time instead of high fidelity CFD simulations. Auto encoders are used as model order reduction…

Fluid Dynamics · Physics 2022-03-04 Kanishk , Tanishk Nandal , Prince Tyagi , Raj Kumar Singh

Observations of seabed texture with synthetic aperture sonar are dependent upon several factors. In this work, we focus on collection geometry with respect to isotropic and anisotropic textures. The low grazing angle of the collection…

Computer Vision and Pattern Recognition · Computer Science 2021-12-14 Dylan Stewart , Shawn Johnson , Alina Zare

Stochastic and conditional simulation methods have been effective towards producing realistic realizations and simulations of spatial numerical models that share equal probability of occurrence. Application of these methods are valuable…

We investigate an electromagnetic instability in two-dimensional materials arising from an anisotropy of the Fermi surface, utilizing a kinetic model accounting for the effects of the values of temperature, chemical potential and anisotropy…

Materials Science · Physics 2025-06-27 Diogo Simões , Hugo Terças , Jorge Ferreira