4,623 research outputs found
Band structure of honeycomb photonic crystal slabs
Two-dimensional (2D) honeycomb photonic crystals with cylinders and
connecting walls have the potential to have a large full band gap. In
experiments, 2D photonic crystals do not have an infinite height, and
therefore, we investigate the effects of the thickness of the walls, the height
of the slabs and the type of the substrates on the photonic bands and gap maps
of 2D honeycomb photonic crystal slabs. The band structures are calculated by
the plane wave expansion method and the supercell approach. We find that the
slab thickness is a key parameter affecting the band gap size while on the
other hand the wall thickness hardly affact the gap size. For symmetric
photonic crystal slabs with lower dielectric claddings, the height of the slabs
needs to be sufficiently large to maintain a band gap. For asymmetric
claddings, the projected band diagrams are similar to that of symmetric slabs
as long as the dielectric constants of the claddings do not differ greatly.Comment: Accepted for publication in Journal of Applied Physic
Enhanced Gas-Flow-Induced Voltage in Graphene
We show by systemically experimental investigation that gas-flow-induced
voltage in monolayer graphene is more than twenty times of that in bulk
graphite. Examination over samples with sheet resistances ranging from 307 to
1600 {\Omega}/sq shows that the induced voltage increase with the resistance
and can be further improved by controlling the quality and doping level of
graphene. The induced voltage is nearly independent of the substrate materials
and can be well explained by the interplay of Bernoulli's principle and the
carrier density dependent Seebeck coefficient. The results demonstrate that
graphene has great potential for flow sensors and energy conversion devices
Top quark decays with flavor violation in the B-LSSM
The decays of top quark are extremely rare processes in the
standard model (SM). The predictions on the corresponding branching ratios in
the SM are too small to be detected in the future, hence any measurable signal
for the processes at the LHC is a smoking gun for new physics. In the extension
of minimal supersymmetric standard model with an additional local
gauge symmetry (B-LSSM), new gauge interaction and new flavor changing
interaction affect the theoretical evaluations on corresponding branching
ratios of those processes. In this work, we analyze those processes in the
B-LSSM, under a minimal flavor violating assumption for the soft breaking
terms. Considering the constraints from updated experimental data, the
numerical results imply ,
, and in our
chosen parameter space. Simultaneously, new gauge coupling constants
in the B-LSSM can also affect the numerical results of
.Comment: 20 pages, 4 figures, published in EPJC. arXiv admin note: substantial
text overlap with arXiv:1803.0990
Influence of support stiffness on aero-engine coupling vibration quantitative analysis
This paper investigates the whole aero-engine coupling vibration, as a rotor tester to be the research object. The rotor tester system is composed of two mountings, stator system, support structures and the rotor system. The modal experiment of the whole tester under the condition of mounting in the test room is carried out. The finite element (FE) model of the rotor tester is built, and the model was modified and validated according to the modal test results. A rotor-stator coupling factor and a section rotor-stator rubbing risk coefficient are proposed, the influence of the support stiffness values on the engine vibration characteristics, such as natural frequencies, modal shapes, rotor-stator coupling degree, and stator-rotor rubbing risk degree at compressor and turbine section is quantitative studied. Results show that the support stiffness contributes to the rigid body modal shapes greatly and to the rotor bending ones slightly. The factor and coefficient defined in this study are both reasonable, and they can reflect the corresponding characteristics exactly. Moreover, the effect of the supports stiffness values on the rotor-stator coupling degree and the rotor-stator rubbing risk degree is nonlinear. The rotor-stator coupling factor and the section stator-rotor rubbing risk coefficient proposed in this study provide a new way to quantitatively research the whole engine coupling vibration
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