25,330 research outputs found
A new fractional derivative involving the normalized sinc function without singular kernel
In this paper, a new fractional derivative involving the normalized sinc
function without singular kernel is proposed. The Laplace transform is used to
find the analytical solution of the anomalous heat-diffusion problems. The
comparative results between classical and fractional-order operators are
presented. The results are significant in the analysis of one-dimensional
anomalous heat-transfer problems.Comment: Keywords: Fractional derivative, anomalous heat diffusion, integral
transform, analytical solutio
Caustic graphene plasmons with Kelvin angle
A century-long argument made by Lord Kelvin that all swimming objects have an
effective Mach number of 3, corresponding to the Kelvin angle of 19.5 degree
for ship waves, has been recently challenged with the conclusion that the
Kelvin angle should gradually transit to the Mach angle as the ship velocity
increases. Here we show that a similar phenomenon can happen for graphene
plasmons. By analyzing the caustic wave pattern of graphene plasmons stimulated
by a swift charged particle moving uniformly above graphene, we show that at
low velocities of the charged particle, the caustics of graphene plasmons form
the Kelvin angle. At large velocities of the particle, the caustics disappear
and the effective semi-angle of the wave pattern approaches the Mach angle. Our
study introduces caustic wave theory to the field of graphene plasmonics, and
reveals a novel physical picture of graphene plasmon excitation during electron
energy-loss spectroscopy measurement.Comment: 15 pages, 4 figure
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