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The 3D Attenuation Structure of Deception Island (Antarctica)
Peer reviewedPostprin
Water wave transmission by an array of floating disks
An experimental validation of theoretical models of transmission of regular
water waves by large arrays of floating disks is presented. The experiments are
conducted in a wave basin. The models are based on combined potential-flow and
thin-plate theories, and the assumption of linear motions. A low-concentration
array, in which disks are separated by approximately a disk diameter in
equilibrium, and a high-concentration array, in which adjacent disks are almost
touching in equilibrium, are used for the experiments. The proportion of
incident wave energy transmitted by the disks is presented as a function of
wave period, and for different wave amplitudes. Results indicate that the
models predict wave energy transmission accurately for small-amplitude waves
and low-concentration arrays. Discrepancies for large-amplitude waves and
high-concentration arrays are attributed to wave overwash of the disks and
collisions between disks. Validation of model predictions of rigid-body motions
of a solitary disk are also presented
Force, Torque, Linear Momentum, and Angular Momentum in Classical Electrodynamics
The classical theory of electrodynamics is built upon Maxwell's equations and
the concepts of electromagnetic (EM) field, force, energy, and momentum, which
are intimately tied together by Poynting's theorem and by the Lorentz force
law. Whereas Maxwell's equations relate the fields to their material sources,
Poynting's theorem governs the flow of EM energy and its exchange between
fields and material media, while the Lorentz law regulates the back-and-forth
transfer of momentum between the media and the fields. An alternative force
law, first proposed by Einstein and Laub, exists that is consistent with
Maxwell's equations and complies with the conservation laws as well as with the
requirements of special relativity. While the Lorentz law requires the
introduction of hidden energy and hidden momentum in situations where an
electric field acts on a magnetized medium, the Einstein-Laub (E-L) formulation
of EM force and torque does not invoke hidden entities under such
circumstances. Moreover, total force/torque exerted by EM fields on any given
object turns out to be independent of whether the density of force/torque is
evaluated using the law of Lorentz or that of Einstein and Laub. Hidden
entities aside, the two formulations differ only in their predicted force and
torque distributions inside matter. Such differences in distribution are
occasionally measurable, and could serve as a guide in deciding which
formulation, if either, corresponds to physical reality.Comment: 15 pages, 35 equations, 75 references. Significant overlap with
arXiv:1312.3262, which is the conference proceedings version of this paper.
The conference paper, entitled "The Force Law of Classical Electrodynamics:
Lorentz versus Einstein and Laub," was published in the Proceedings of SPIE
8810, 88100K-1:18 (2013). arXiv admin note: text overlap with arXiv:1409.479
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