A polarization-insensitive unidirectional spoof surface plasmon polariton（SPP） coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs ar...A polarization-insensitive unidirectional spoof surface plasmon polariton（SPP） coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs are analyzed. The simulated and experimental results support the theoretical analysis and indicate that the designed gradient metasurface can couple both the parallel-polarized and normally-polarized incident waves to the spoof SPPs propagating in the same direction at about 5 GHz.展开更多
In this article,we consider the entropy-expansiveness of geodesic flows on closed Riemannian manifolds without conjugate points.We prove that,if the manifold has no focal points,or if the manifold is bounded asymptote...In this article,we consider the entropy-expansiveness of geodesic flows on closed Riemannian manifolds without conjugate points.We prove that,if the manifold has no focal points,or if the manifold is bounded asymptote,then the geodesic flow is entropy-expansive.Moreover,for the compact oriented surfaces without conjugate points,we prove that the geodesic flows are entropy-expansive.We also give an estimation of distance between two positively asymptotic geodesics of an uniform visibility manifold.展开更多
In this paper, we study the optimal time decay rate of isentropic Navier-Stokes equations under the low regularity assumptions about initial data. In the previous works about optimal time decay rate, the initial data ...In this paper, we study the optimal time decay rate of isentropic Navier-Stokes equations under the low regularity assumptions about initial data. In the previous works about optimal time decay rate, the initial data need to be small in H^[N/2]＋2（R^N）. Our work combined negative Besov space estimates and the conventional energy estimates in Besov space framework which is developed by Danchim Through our methods, we can get optimal time decay rate with initial data just small in B^N/2-1,N/2＋1∩^N/2-1,N/2 and belong to some negative Besov space （need not to be small）. Finally, combining the recent results in [25] with our methods, we only need the initial data to be small in homogeneous Besov space B^N/2-2,N/2 ∩B^N/2-1 to get the optimal time decay rate in space L2.展开更多
基金Project supported by the China Postdoctoral Science Foundation(Grant No.2015M580849)the National Natural Science Foundation of China(Grant Nos.61471292,61501365,61471388,6133100541404095,and 41390454)
文摘A polarization-insensitive unidirectional spoof surface plasmon polariton（SPP） coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs are analyzed. The simulated and experimental results support the theoretical analysis and indicate that the designed gradient metasurface can couple both the parallel-polarized and normally-polarized incident waves to the spoof SPPs propagating in the same direction at about 5 GHz.
基金supported by NSFC(Grant Nos.11301305 and 11571207)the grant "2012KYTD" from Shandong University of Science and Technology+2 种基金supported by NSFC(Grant No.11101294)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20111108120001)the grant of"Youxiu Rencai Peiyang Zizhu"(Class A)from the Beijing City
文摘In this article,we consider the entropy-expansiveness of geodesic flows on closed Riemannian manifolds without conjugate points.We prove that,if the manifold has no focal points,or if the manifold is bounded asymptote,then the geodesic flow is entropy-expansive.Moreover,for the compact oriented surfaces without conjugate points,we prove that the geodesic flows are entropy-expansive.We also give an estimation of distance between two positively asymptotic geodesics of an uniform visibility manifold.
基金Supported by the National Natural Science Foundation of China(Grant No.11501439)the Postdoctoral Science Foundation Pro ject of China(Grant No.2017T100733)
文摘In this paper, we study the optimal time decay rate of isentropic Navier-Stokes equations under the low regularity assumptions about initial data. In the previous works about optimal time decay rate, the initial data need to be small in H^[N/2]＋2（R^N）. Our work combined negative Besov space estimates and the conventional energy estimates in Besov space framework which is developed by Danchim Through our methods, we can get optimal time decay rate with initial data just small in B^N/2-1,N/2＋1∩^N/2-1,N/2 and belong to some negative Besov space （need not to be small）. Finally, combining the recent results in [25] with our methods, we only need the initial data to be small in homogeneous Besov space B^N/2-2,N/2 ∩B^N/2-1 to get the optimal time decay rate in space L2.
