Results 121 to 130 of about 3,460 (267)

The SIR Model in a Moving Population: Propagation of Infection and Herd Immunity

Communications on Pure and Applied Mathematics, EarlyView.
ABSTRACT In a collection of particles performing independent random walks on Zd$\mathbb {Z}^d$ we study the spread of an infection with SIR dynamics. Susceptible particles become infected when they meet an infected particle. Infected particles heal and are removed at rate ν$\nu$.
Duncan Dauvergne, Allan Sly
wiley   +1 more source

Stochastic Gradient Descent in High Dimensions for Multi‐Spiked Tensor PCA

Communications on Pure and Applied Mathematics, EarlyView.
ABSTRACT We study the high‐dimensional dynamics of online stochastic gradient descent (SGD) for the multi‐spiked tensor model. This multi‐index model arises from the tensor principal component analysis (PCA) problem with multiple spikes, where the goal is to estimate the unknown signal vectors within the N$N$‐dimensional unit sphere through maximum ...
Gérard Ben Arous, Cédric Gerbelot, Vanessa Piccolo   +2 more
wiley   +1 more source

Compact Manifolds With Unbounded Nilpotent Fundamental Groups and Positive Ricci Curvature

Communications on Pure and Applied Mathematics, EarlyView.
ABSTRACT It follows from the work of Kapovitch and Wilking that a closed manifold with nonnegative Ricci curvature has a uniformly almost nilpotent fundamental group. Leftover questions and conjectures, have asked if in this context the fundamental group is actually uniformly almost abelian. The main goal of this work is to construct examples (Mk9,gk)$(
Elia Bruè, Aaron Naber, Daniele Semola
wiley   +1 more source

Photometric Diagnostic of the Sheath Dynamics and Electron Density Trends in Single and Dual Frequency CCRF Argon Plasmas

Contributions to Plasma Physics, EarlyView.
ABSTRACT A methodological study is presented on a noninvasive photometric diagnostic for determining trends in electron density and sheath dynamics in single (1f) and a dual (2f) radio frequency capacitively coupled (CCRF) argon plasmas. The 1f discharges are operated at 13.56 and 27.12 MHz, respectively, while the 2f discharge is driven by both ...
Daniel Zuhayra, Jessica Niemann, Viktor Schneider, Holger Kersten   +3 more
wiley   +1 more source

Kinetic Contribution to the Arbitrary Order Odd Frequency Moments of the Dynamic Structure Factor

Contributions to Plasma Physics, EarlyView.
ABSTRACT An exact expression is derived for the kinetic contribution to the odd (arbitrary order) frequency moments of the dynamic structure factor via a finite summation that features averages of even (all lower orders) powers of the momentum over the exact momentum distribution.
Panagiotis Tolias, Tobias Dornheim, Jan Vorberger   +2 more
wiley   +1 more source

Review and prospects of shear test of bolted rock joints

Deep Underground Science and Engineering, EarlyView.
The laboratory shear test equipment, test method, and numerical simulation of bolted rock joints were summarized. The shortcomings and limitations of the current research were analyzed, and the research prospects were proposed. Abstract Rock bolting is a critical approach in geotechnical engineering for supporting weak rocks.
Shulin Ren, Fan Yang, Manchao He, Yong Yuan, Zhigang Tao   +4 more
wiley   +1 more source

Latitudinal effect on the structure of snake–prey interaction networks is mediated by snake species richness

Ecography, EarlyView.
Despite the growing number of studies on trophic networks in recent decades, there are still important gaps in our understanding of how these networks are structured across broad environmental gradients. These gaps are even greater in some groups of terrestrial vertebrates, such as snakes, requiring a cohesive synthesis of their broader trophic ...
Daniela Pinto‐Coelho, Kate P. Maia, Laura R. V. Alencar, Marcio Martins, Paulo R. Guimarães   +4 more
wiley   +1 more source

Machine Learning Unveils Isolated‐Surrounded Pt Motifs in High‐Entropy Alloys for Superior Low‐Temperature Ammonia Oxidation

ENERGY &ENVIRONMENTAL MATERIALS, EarlyView.
A physics‐informed machine learning approach successfully decodes the complex catalytic activity of high‐entropy alloys for ammonia oxidation. By revealing a synergistic mechanism involving lattice and electronic couplings, the study identifies a superior “isolated‐surrounded” platinum motif.
Shangfeng Jiang, Ting Tao, Kexiang Guo, Xinyu Fan, Xu Zhang, Zhen Zhou   +5 more
wiley   +1 more source

Influence of Structural and Environmental Parameters on Solar Air Collector Performance

Energy Science &Engineering, EarlyView.
Increasing air gap depth and mass flow rate significantly enhances the thermal performance of solar air collectors, with optimal performance achieved at an 8.5 cm air gap and 0.01318 kg/s mass flow rate. Air gap depth is identified as the dominant factor influencing system efficiency.
Quankun Zhu, István Farkas, János Buzas   +2 more
wiley   +1 more source

Edge‐Based Discretizations on Triangulations in Any Dimension, With Special Attention to Four‐Dimensional Space

International Journal for Numerical Methods in Fluids, EarlyView.
This article provides important geometric formulas for node‐centered, edge‐based schemes in any number of dimensions. These formulas are noteworthy, as they do not require the explicit formation of dual regions. We prove several key geometric results, with a particular focus on the four‐dimensional case, due to potential space‐time applications ...
Nicholas Tufillaro, David M. Williams, Hiroaki Nishikawa   +2 more
wiley   +1 more source