44,788 research outputs found
A quadratic bound on the number of boundary slopes of essential surfaces with bounded genus
Let be an orientable 3-manifold with a single torus. We show
that the number of boundary slopes of immersed essential surfaces with genus at
most is bounded by a quadratic function of . In the hyperbolic case,
this was proved earlier by Hass, Rubinstein and Wang.Comment: 11 pages, 1 figur
Algorithms to test open set condition for self-similar set related to P.V. numbers
Fix a P.V. number Given
,
\mathbf{b}=(b_{1},\cdots,b_{m})\in \mathbb{Q^{m}, for the self-similar set
we find an efficient algorithm to
test whether satisfies the open set condition
(strong separation condition) or not
Circulator based on spoof surface plasmon polaritons
Circulators based on spoof surface plasmon polaritons are designed and
analyzed. In the letter, we use blade structure to realize the propagation of
SSPPs wave and a matching transition is used to feed energy from coplanar
waveguide to the SSPPs. And the circulator shows good nonreciprocal
transmission characteristics. The simulation results indicate that in the
frequency band from 5 to 6.6 GHz, the isolation degree and return loss
basically reaches 15dB and the insertion loss is less than 0.5dB. Moreover, the
use of confinement electromagnetic waves can decrease the size of the ferrite
and show a broadband characteristic.Comment: 3 pages, 6 figures, submitted to IEEE antennas and wireless
propagation letters on 27-Mar-201
A stability condition for turbulence model: From EMMS model to EMMS-based turbulence model
The closure problem of turbulence is still a challenging issue in turbulence
modeling. In this work, a stability condition is used to close turbulence.
Specifically, we regard single-phase flow as a mixture of turbulent and
non-turbulent fluids, separating the structure of turbulence. Subsequently,
according to the picture of the turbulent eddy cascade, the energy contained in
turbulent flow is decomposed into different parts and then quantified. A
turbulence stability condition, similar to the principle of the
energy-minimization multi-scale (EMMS) model for gas-solid systems, is
formulated to close the dynamic constraint equations of turbulence, allowing
the heterogeneous structural parameters of turbulence to be optimized. We call
this model the `EMMS-based turbulence model', and use it to construct the
corresponding turbulent viscosity coefficient. To validate the EMMS-based
turbulence model, it is used to simulate two classical benchmark problems,
lid-driven cavity flow and turbulent flow with forced convection in an empty
room. The numerical results show that the EMMS-based turbulence model improves
the accuracy of turbulence modeling due to it considers the principle of
compromise in competition between viscosity and inertia.Comment: 26 pages, 13 figures, 2 table
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