In this work, by virtue of the properties of weakly almost periodic points of a dynamical system （X, T） with at least two points, the authors prove that, if the measure center M（T） of T is the whole space, that is...In this work, by virtue of the properties of weakly almost periodic points of a dynamical system （X, T） with at least two points, the authors prove that, if the measure center M（T） of T is the whole space, that is, M（T） = X, then the following statements are equivalent： （1） （X, T） is ergodic mixing; （2） （X, T） is topologically double ergodic; （3） （X, T） is weak mixing; （4） （X, T） is extremely scattering; （5） （X, T） is strong scattering; （6） （X × X, T × T） is strong scattering; （7） （X × X, T × T） is extremely scattering; （8） For any subset S of N with upper density 1, there is a c-dense Fα-chaotic set with respect to S. As an application, the authors show that, for the sub-shift aA of finite type determined by a k × k-（0, 1） matrix A, erA is strong mixing if and only if aA is totally transitive.展开更多
The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity sys...The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity system is investigated with computational fluid dynamics. A total variation diminishing scheme is employed to solve the unsteady, two-dimensional, compressible, Navier-Stokes equations. The Mach number of an initial shock wave is changed in the range from 1.02 to 1.12. Several different types of porous wall/cavity systems are tested to investigate the passive control effects. The results show that wall pressure strongly fluctuates due to diffraction and reflection processes of the shock waves behind the incident shock wave. From the results, it is understood that for effective alleviation of tunnel impulse waves, the length of the perforated region should be sufficiently long.展开更多
基金supported by the National Natural Science Foundation of China (No. 10971236)the Foundation of Jiangxi Provincial Education Department (No. GJJ11295)the Jiangxi Provincial Natural Science Foundation of China (No. 20114BAB201006)
文摘In this work, by virtue of the properties of weakly almost periodic points of a dynamical system （X, T） with at least two points, the authors prove that, if the measure center M（T） of T is the whole space, that is, M（T） = X, then the following statements are equivalent： （1） （X, T） is ergodic mixing; （2） （X, T） is topologically double ergodic; （3） （X, T） is weak mixing; （4） （X, T） is extremely scattering; （5） （X, T） is strong scattering; （6） （X × X, T × T） is strong scattering; （7） （X × X, T × T） is extremely scattering; （8） For any subset S of N with upper density 1, there is a c-dense Fα-chaotic set with respect to S. As an application, the authors show that, for the sub-shift aA of finite type determined by a k × k-（0, 1） matrix A, erA is strong mixing if and only if aA is totally transitive.
文摘The present computational study addresses the attenuation of the shock wave propagating in a duct, using a porous wall/cavity system. In the present study, a weak shock wave propagating over the porous wall/cavity system is investigated with computational fluid dynamics. A total variation diminishing scheme is employed to solve the unsteady, two-dimensional, compressible, Navier-Stokes equations. The Mach number of an initial shock wave is changed in the range from 1.02 to 1.12. Several different types of porous wall/cavity systems are tested to investigate the passive control effects. The results show that wall pressure strongly fluctuates due to diffraction and reflection processes of the shock waves behind the incident shock wave. From the results, it is understood that for effective alleviation of tunnel impulse waves, the length of the perforated region should be sufficiently long.
