17,331 research outputs found
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
Strategic Remanufacturing Decision in a Supply Chain with an External Local Remanufacturer
This paper develops a model for remanufacturing decisions in a two-stage supply chain with one manufacturer, one retailer and one external local remanufacturer, who collects used products and then reproduces them into a new one if the manufacturer does not join in remanufacturing process. This paper is different from most of the extant studies about remanufacturing because they consider decisions of firms rather than supply chains. We mainly focus on the remanufacturing strategy of the manufacturer when there is a local remanufacturer. We derive the equilibrium results for all players and do some comparative studies under different cases. We find that product substitutability can invert the effect of manufacturer’s extension decision on the retailer’s profit. We also consider the effect of channel structure by comparing the decentralized channel with the centralized channel. We find that the manufacturer has a higher incentive to extend its product line in the centralized channel than the decentralized channel; and the competition can strengthen its motivation to extend the line
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