We experimentally investigate the transparent-liquid/solid （water/aluminum or steel） interface waves generated by laser pulses and detected by the Mirage effect, it is shown that nearly all kinds of liquid/solid int...We experimentally investigate the transparent-liquid/solid （water/aluminum or steel） interface waves generated by laser pulses and detected by the Mirage effect, it is shown that nearly all kinds of liquid/solid interface waves in water are detected, both their measured wave velocities and characteristic of shape are in good agreement with theoretical predictions.展开更多
Transient thermal grating method is used to measure the thermal diffusivity of absorbing films deposited on transparent substrates. According to periodically modulated dielectric constant variations and thermoelastic ...Transient thermal grating method is used to measure the thermal diffusivity of absorbing films deposited on transparent substrates. According to periodically modulated dielectric constant variations and thermoelastic deformations of the thin films caused by the transient thermal gratings, an improved optical diffraction theory is presented. In the experiment, the probing laser beam reflectively diffracted by the thermal grating is measured by a photomultiplier at different grating fringe spaces. The thermal diffusivity of the film can be evaluated by fitting the theoretical calculations of diffraction signals to the experimental measured data. The validity of the method is tested by measuring the thermal diffusivities of absorbing ZnO films deposited on glass substrates.展开更多
We develop an approach to homogenize three-dimensional periodic solid-solid elastic composites with cubic lattice at low frequencies, by using plane wave expansion and perturbation theory with respect to the long wave...We develop an approach to homogenize three-dimensional periodic solid-solid elastic composites with cubic lattice at low frequencies, by using plane wave expansion and perturbation theory with respect to the long wavelength limit. Based on the fact that the two shear waves propagating along lattice axis are degenerated, we derive formulae for effective velocities parallel and normal to the lattice axis, from which three independent effective elastic moduli are calculated, respectively. Theoretical results, which take into account the multiple scattering and the structure of the periodic medium, are in good agreement with the previous isotropic theory at high-symmetry directions.展开更多
Effective velocities of elastic waves propagating in two-dimensional phononic crystal at low frequencies are analysed theoretically, and exact analytical formulas for effective velocities of elastic waves are derived ...Effective velocities of elastic waves propagating in two-dimensional phononic crystal at low frequencies are analysed theoretically, and exact analytical formulas for effective velocities of elastic waves are derived according to the method presented by Krokhin et al. [Phys. Rev. Lett. 91 （2003） 264302]. Numerical calculations for phononic crystals consisted of array of Pb cylinders emSedded in epoxy show that the composites have distinct anisotropy at low filling fraction. The anisotropy increases as the filling fraction increases, while as the filling fraction closes to the limitation, the anisotropy decreases.展开更多
The dust acoustic solitary waves propagating in two different directions in two-dimensional dusty plasma are investigated. In order to study the soliton interactions in multi-dimensional systems, we extend the reducti...The dust acoustic solitary waves propagating in two different directions in two-dimensional dusty plasma are investigated. In order to study the soliton interactions in multi-dimensional systems, we extend the reductive perturbation method and obtain two Kortewe-de Vries equations for nonlinear waves in both the ξ and 77 directions, respectively. The phase shifts after collision of two solitons with arbitrary angle are given. Finally, the solution of na up to O（ε^4） order is obtained.展开更多
基金Support by the National Natural Science Foundation under Grant Nos 10234060 and 10134020.
文摘We experimentally investigate the transparent-liquid/solid （water/aluminum or steel） interface waves generated by laser pulses and detected by the Mirage effect, it is shown that nearly all kinds of liquid/solid interface waves in water are detected, both their measured wave velocities and characteristic of shape are in good agreement with theoretical predictions.
基金Supported by the National Natural Science Foundation of China under Grant No 10574073.
文摘Transient thermal grating method is used to measure the thermal diffusivity of absorbing films deposited on transparent substrates. According to periodically modulated dielectric constant variations and thermoelastic deformations of the thin films caused by the transient thermal gratings, an improved optical diffraction theory is presented. In the experiment, the probing laser beam reflectively diffracted by the thermal grating is measured by a photomultiplier at different grating fringe spaces. The thermal diffusivity of the film can be evaluated by fitting the theoretical calculations of diffraction signals to the experimental measured data. The validity of the method is tested by measuring the thermal diffusivities of absorbing ZnO films deposited on glass substrates.
基金Supported by the Ministry of Education of China under Grant Nos 705017 and 20060284035, the Excellent Youth Science Foundation of China under Grant No 10125417, and the State Key Basic Research and Development Programme of China under Grant No 51315.
文摘We develop an approach to homogenize three-dimensional periodic solid-solid elastic composites with cubic lattice at low frequencies, by using plane wave expansion and perturbation theory with respect to the long wavelength limit. Based on the fact that the two shear waves propagating along lattice axis are degenerated, we derive formulae for effective velocities parallel and normal to the lattice axis, from which three independent effective elastic moduli are calculated, respectively. Theoretical results, which take into account the multiple scattering and the structure of the periodic medium, are in good agreement with the previous isotropic theory at high-symmetry directions.
基金Supported by the Excellent Youth Science Foundation of China under Grant No 10125417 and the State Key Development Program of Basic Research under Grant No 51307.
文摘Effective velocities of elastic waves propagating in two-dimensional phononic crystal at low frequencies are analysed theoretically, and exact analytical formulas for effective velocities of elastic waves are derived according to the method presented by Krokhin et al. [Phys. Rev. Lett. 91 （2003） 264302]. Numerical calculations for phononic crystals consisted of array of Pb cylinders emSedded in epoxy show that the composites have distinct anisotropy at low filling fraction. The anisotropy increases as the filling fraction increases, while as the filling fraction closes to the limitation, the anisotropy decreases.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10575082 and 10247008, the Scientific Research Foundation （SRF） for the Returned 0verseas Chinese Scholars （R0CF）, State Education Ministry （SEM）.
文摘The dust acoustic solitary waves propagating in two different directions in two-dimensional dusty plasma are investigated. In order to study the soliton interactions in multi-dimensional systems, we extend the reductive perturbation method and obtain two Kortewe-de Vries equations for nonlinear waves in both the ξ and 77 directions, respectively. The phase shifts after collision of two solitons with arbitrary angle are given. Finally, the solution of na up to O（ε^4） order is obtained.
