In recent years, the disparity of Chinese people's income has been unsteadily expanding. The reasons lie in many aspects, among which there are mainly income disparity between the rural and the urban and the disparit...In recent years, the disparity of Chinese people's income has been unsteadily expanding. The reasons lie in many aspects, among which there are mainly income disparity between the rural and the urban and the disparity between regions, including the disparity between people both in the city and in the countryside. Therefore the corresponding strategies should be put into effect .展开更多
In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation...In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation of the mechanic and electric fields as well as the Bloch-Floquet theorem. The band structures of both the in-plane and anti-plane modes are calculated for a rectangular lattice by the planewave expansion method. The effects of the lattice constant ratio and the piezoelectricity with different filling fractions are analyzed. The results show that the largest gap width is not always obtained for a square lattice. In some situations, a rectangular lattice may generate larger gaps. The band gap characteristics are influenced obviously by the piezoelectricity with the larger lattice constant ratios and the filling fractions.展开更多
文摘In recent years, the disparity of Chinese people's income has been unsteadily expanding. The reasons lie in many aspects, among which there are mainly income disparity between the rural and the urban and the disparity between regions, including the disparity between people both in the city and in the countryside. Therefore the corresponding strategies should be put into effect .
基金the National Natural Science Foundation of China (10672017 and 10632020)
文摘In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation of the mechanic and electric fields as well as the Bloch-Floquet theorem. The band structures of both the in-plane and anti-plane modes are calculated for a rectangular lattice by the planewave expansion method. The effects of the lattice constant ratio and the piezoelectricity with different filling fractions are analyzed. The results show that the largest gap width is not always obtained for a square lattice. In some situations, a rectangular lattice may generate larger gaps. The band gap characteristics are influenced obviously by the piezoelectricity with the larger lattice constant ratios and the filling fractions.