Results 151 to 160 of about 8,865 (256)

Compact Manifolds With Unbounded Nilpotent Fundamental Groups and Positive Ricci Curvature

open access: yesCommunications 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

Stopping Power of Electron Liquid for Slow Quantum Projectiles

open access: yesContributions to Plasma Physics, EarlyView.
ABSTRACT We revisit the problem of the deceleration of a charge moving in a medium. In the low‐velocity limit of the projectile, we construct the fully nonlinear (in the charge–target interaction) theory of the stopping power (SP), which goes beyond the classical Ehrenfest dynamics.
Vladimir U. Nazarov, E. K. U. Gross
wiley   +1 more source

Advancing mine pillar design: Evaluating traditional methods and integrating AI for enhanced stability of pillars in the Great Dyke, Zimbabwe

open access: yesDeep Underground Science and Engineering, EarlyView.
B1 is bord width 1, B2 is bord width 2, L is the pillar length, W is the pillar width, red color and letter A represent the pillars, and white color and number 1 represent excavated areas. Pstress is the average pillar stress; σv is the vertical component of the virgin stress, MPa; and e is the areal extraction ratio. e = B o B o + B P ${\rm{e}}=\frac{{
Tawanda Zvarivadza   +4 more
wiley   +1 more source

Fracture evolution of a thick soft protection layer and the water inrush mechanism in overburden under longwall mining

open access: yesDeep Underground Science and Engineering, EarlyView.
Through shear–tensile creep tests and viscoelastic modeling, the fracture evolution of thick soft protective layers is clarified. Results show thickness‐dependent rheological failure modes that govern four types of roof water inrush, providing a mechanism‐based framework for hazard prediction and control. Abstract In the Jurassic coal‐bearing strata of
Mengnan Liu   +4 more
wiley   +1 more source

Research progress and current status of dynamic wave propagation characteristics in rock mass: A review

open access: yesDeep Underground Science and Engineering, EarlyView.
This review elucidates the velocity–dispersion–attenuation coupling mechanisms of wave propagation in rock masses, compares six representative models, and reveals how pressure, temperature, mineral composition, and anisotropy jointly control dynamic responses in complex geological media.
Jiajun Shu   +8 more
wiley   +1 more source

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