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The measurement of the Sun's surface motions with a high spatial and temporal resolution is still a challenge. We wish to validate horizontal velocity measurements all over the visible disk of the Sun from Solar Dynamics Observatory/…

Solar and Stellar Astrophysics · Physics 2015-06-15 Th. Roudier , M. Rieutord , V. Prat , J. M. Malherbe , N. Renon , Z. Frank , M. Svanda , T. Berger , R. Burston , L. Gizon

Helioseismic signatures of dynamo waves have recently been discovered in variations of the solar differential rotation, offering valuable insights into the type of dynamo mechanism operating in the solar convection zone. To characterize…

Solar and Stellar Astrophysics · Physics 2025-05-19 Krishnendu Mandal , Alexander G. Kosovichev , Valery V. Pipin , Sylvain G. Korzennik

We present the identification of very low frequency g modes in the asymptotic regime and two important parameters that have long been waited for: the core rotation rate, and the asymptotic equidistant period spacing of these g modes. The…

Aims. We show how the build-up of magnetic gradients in the Sun's corona may be inferred directly from photospheric velocity data. This enables computation of magnetic connectivity measures such as the squashing factor without recourse to…

Solar and Stellar Astrophysics · Physics 2015-05-30 A. R. Yeates , G. Hornig , B. T. Welsch

Solar supergranulation remains a mystery in spite of decades of intensive studies. Most of the papers about supergranulation deal with its surface properties. Local helioseismology provides an opportunity to look below the surface and see…

Solar and Stellar Astrophysics · Physics 2015-05-19 Radek Zlebcik , Michal Svanda , Mirek Klvana

Time-distance helioseismology is a set of powerful tools to study features below the Sun's surface. Inverse methods are needed to interpret time-distance measurements, with many examples in the literature. However, techniques that utilize a…

Solar and Stellar Astrophysics · Physics 2020-10-14 Jason Jackiewicz

Quantum magnetometers based on spin defects in solids enable sensitive imaging of various magnetic phenomena, such as ferro- and antiferromagnetism, superconductivity, and current-induced fields. Existing protocols primarily focus on static…

We propose a kinematic wave-based Deep Convolutional Neural Network (Deep CNN) to estimate high-resolution traffic speed fields from sparse probe vehicle trajectories. We introduce two key approaches that allow us to incorporate kinematic…

Machine Learning · Computer Science 2022-04-12 Bilal Thonnam Thodi , Zaid Saeed Khan , Saif Eddin Jabari , Monica Menendez

Over the past 15 years, our knowledge of the interior of the Sun has tremendously progressed by the use of helioseismic measurements. However, to go further in our understanding of the solar core, we need to measure gravity (g) modes.…

In this paper we introduce an efficient method to unwrap multi-frequency phase estimates for time-of-flight ranging. The algorithm generates multiple depth hypotheses and uses a spatial kernel density estimate (KDE) to rank them. The…

Computer Vision and Pattern Recognition · Computer Science 2016-08-19 Felix Järemo Lawin , Per-Erik Forssén , Hannes Ovrén

We have developed an algorithm dedicated to timing reconstruction in highly granular calorimeters(HGC). The performance of this algorithm is evaluated on an electromagnetic calorimeter (ECAL) with geometries comparable to the…

Instrumentation and Detectors · Physics 2024-09-09 Yuzhi Che , Vincent Boudry , Henri Videau , Muchen He , Manqi Ruan

A helioseismic statistical waveform analysis of subsurface flow was performed on two 720-day time series of SOHO/MDI Medium-l spherical-harmonic coefficients. The time series coincide with epochs of high and low solar activity.…

Solar and Stellar Astrophysics · Physics 2016-05-23 M. F. Woodard

Anomalous behavior is ubiquitous in subsurface solute transport due to the presence of high degrees of heterogeneity at different scales in the media. Although fractional models have been extensively used to describe the anomalous transport…

Numerical Analysis · Mathematics 2022-02-01 Xiao Xu , Marta D'Elia , Christian Glusa , John T. Foster

We explicitly calculate the Green functions describing quantum changes of topology in Friedman-Lemaitre-Robertson-Walker Universes whose spacelike sections are compact but endowed with distinct topologies. The calculations are performed…

General Relativity and Quantum Cosmology · Physics 2010-02-03 Jerome Martin , Nelson Pinto-Neto , Ivano Damiao Soares

Time-distance helioseismology is one of the primary tools for studying the solar meridional circulation. However, travel-time measurements of the subsurface meridional flow suffer from a variety of systematic errors, such as a…

Solar and Stellar Astrophysics · Physics 2017-04-26 Zhi-Chao Liang , Aaron C. Birch , Thomas L. Duvall , Laurent Gizon , Jesper Schou

In the paper we suggest a new construction of stochastic flows of kernels in a locally compact separable metric space $M$. Starting from a consistent sequence of Feller transtition function $(\mathsf{P}^{(n)}: n\geq 1)$ on $M$ we prove…

Probability · Mathematics 2025-01-07 Georgii Riabov

Limit cycle oscillations are phenomena arising in nonlinear dynamical systems and characterized by periodic, locally-stable, and self-sustained state trajectories. Systems controlled in a closed loop along a periodic trajectory can also be…

Systems and Control · Electrical Eng. & Systems 2023-03-20 Defne E. Ozan , Mingzhou Yin , Andrea Iannelli , Roy S. Smith

Long-lived rotational and meridional flows are important ingredients of the solar cycle. Magnetic field images have typically been used to measure these flows on the solar surface by cross-correlating thin longitudinal strips or square…

Solar and Stellar Astrophysics · Physics 2017-02-15 Derek A. Lamb

A time-distance measurement technique is derived to isolate phase travel time anisotropy caused by subsurface horizontal magnetic fields, and a method which uses the measured anisotropy to estimate the field's orientation is also derived. A…

Solar and Stellar Astrophysics · Physics 2022-05-11 John T. Stefan , Alexander G. Kosovichev

We introduce an experimental technique for complete phase-sensitive characterization of arbitrary unitary spectral-temporal transformations of optical modes. Our method recovers the complex spectral transfer function, or Green's function,…