Ou Y.-L.,Texas A&M University-Commerce |
Wang Z.-P.,Wenshan University
Journal of Geometry and Physics | Year: 2011
We prove that a totally umbilical biharmonic surface in any 3-dimensional Riemannian manifold has constant mean curvature. We use this to show that a totally umbilical surface in Thurston's 3-dimensional geometries is proper biharmonic if and only if it is a part of S2(1/2) in S3. We also give complete classifications of constant mean curvature proper biharmonic surfaces in Thurston's 3-dimensional geometries and in 3-dimensional Bianchi-Cartan-Vranceanu spaces, and a complete classification of proper biharmonic Hopf cylinders in 3-dimensional Bianchi-Cartan-Vranceanu spaces. © 2011 Elsevier B.V.
Kao S.-P.,National Chung Hsing University |
Chen Y.-C.,National Chung Hsing University |
Ning F.-S.,Wenshan University
Advances in Space Research | Year: 2014
The geometry-free linear combination of dual-frequency GNSS reference station ground observations are currently used to build the Vertical Total Electron Content (VTEC) model of the ionosphere. As it is known, besides ionospheric delays, there are differential code bias (DCB) of satellite (SDCB) and receiver (RDCB) in the geometry-free observation equation. The SDCB can be obtained using the International GNSS Service (IGS) analysis centers, but the RDCB for regional and local network receivers are not provided. Therefore, estimating the RDCB and VTEC model accurately and simultaneously is a critical factor investigated by researchers. This study uses Multivariate Adaptive Regression Splines (MARS) to estimate the VTEC approximate model and then substitutes this model in the observation equation to form the normal equation. The least squares method is used to solve the RDCB and VTEC model together. The research findings show that this method has good modeling effectiveness and the estimated RDCB has good reliability. The estimated VTEC model applied to GPS single-frequency precise point positioning has better positioning accuracy in comparison to the IGS global ionosphere map (GIM). © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.
Hu J.-G.,Wenshan University |
Hu J.-G.,Yunnan University |
Xu W.,Yunnan University
Physica B: Condensed Matter | Year: 2014
With a square lattice mercury and water system being as the model, the band structures of nesting and compound phononic crystals with two different lattice constants were investigated using the method of the supercell plane wave expansion. It was observed that large band gaps can be achieved in low frequency regions by adjusting one of the lattice constants. Meanwhile, effects similar to interstitial impurity defects can be achieved with the increase of lattice constant of the phononic crystal. The corresponding defect modes can be stimulated in band gaps. The larger the lattice constant, the stronger the localization effect of defect modes on the wave. In addition, the change of the filling fraction of impurity exerts great influence on the frequency and localization of defect modes. Furthermore, the change of the position of impurity has notable influence on the frequency of defect modes and their localization. However, the geometry structure and orientation of impurity have little effect on the frequency of defect modes and their localization in the band gap. © 2014 Elsevier B.V. All rights reserved.
Wang C.,Kunming University of Science and Technology |
Dai Z.,Yunnan University |
Liu C.,Wenshan University
Physica Scripta | Year: 2014
In this paper, two types of multi-parameter breather homoclinic wave solutions - including breather homoclinic wave and rational homoclinic wave solutions - are obtained by using the Hirota technique and ansätz with complexity of parameter for the coupled Schrödinger-Boussinesq equation. Rogue waves in the form of the rational homoclinic solution are derived when the periods of breather homoclinic wave go to infinite. Some novel features of homoclinic wave solutions are discussed and presented. In contrast to the normal bright rogue wave structure, a structure like a four-petaled flower in temporal-spatial distribution is exhibited. Further with the change of the wave number of the plane wave, the bright and dark rogue wave structures may change into each other. The bright rogue wave structure results from the full merger of two nearby peaks, and the dark rogue wave structure results from the full merger of two nearby holes. The dark rogue wave for the uncoupled Boussinesq equation is finally obtained. Its structural properties show that it never takes on bright rogue wave features with the change of parameter. It is hoped that these results might provide us with useful information on the dynamics of the relevant fields in physics. © 2014 The Royal Swedish Academy of Sciences.
Yang M.,Nanjing Southeast University |
Huang Q.,Nanjing Southeast University |
Jin X.,Wenshan University
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2012
ZnGaNO solid solution-C 3N 4 composite photocatalyst with visible light response was synthesized through polymerization of melamine in the presence of ZnGaNO solid solution. The composite photocatalyst was characterized by X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy (XPS), Energy dispersed spectrometer (EDS) and BET surface area measurements. The activity of composite photocatalyst g-C 3N 4-ZnGaNO for photodegradation of methyl orange (MO) is higher than that of either single-phase g-C 3N 4 or ZnGaNO solid solution. The as-prepared composite photocatalyst exhibits an improved photocatalytic activity due to enhancement of electron-hole separations at the interface. © 2012 Elsevier B.V. All rights reserved.