Transverse Correlation Coefficient Research Articles

浅海水平相关系数的频率特性研究

It was observed in a shallow water experiment that the horizontal correlation coefficients oscillated with frequency. The relationship among the longitudinal correlation, the intensity and frequency is given according to the normal mode theory and verified by the experimental data. The transverse correlation was also studied. In theory, the relationship among the transverse correlation coefficient, the intensity and frequency is obtained from the sound speed fluctuation.

Frequency Dependence of Transverse Correlation Coefficient in the Yellow Sea

Horizontal correlation is one of the most important characteristic parameters in ocean acoustics. In a shallow water acoustic experiment, we observed that the transverse correlation coefficient is an oscillation function of frequency. A model based on adiabatic normal mode theory in a random inhomogeneous waveguide which is statistically isotropic in a horizontal plane is developed. The theory indicates that the oscillation of the transverse correlation coefficient is mainly due to the normal mode interference.

Anisotropy in a stratified shear layer

The dynamics and turbulent evolution of a stratified shear layer are explored through direct numerical simulation. Turbulence is instigated through the most unstable asymptotic linear Kelvin-Helmholtz (KH) eigenmode at Richardson number Ri = 0.05 and Reynolds number Re = 2000 (Ri and Re are defined below). The primary 2D KH vortex succumbs to 3D motions in a manner consistent with earlier findings. The shear-layer Reynolds number ReL (defined below) grows to ReL ≈ 2.4 × 104 as the layer expands and small length-scale motions develop. Large- and small-scale anisotropy are examined by comparing 1) spectra for the longitudinal and transverse correlation coefficients, 2) RMS velocity components and 3) velocity and temperature derivatives during the time when turbulence is most intense. The mean shear produces a tendency toward streamwise axisymmetric, as opposed to isotropic, turbulent flow; however, departures from streamwise axisymmetry due to stratification are evident in the dissipation fields (i.e., at small scales).

Statistical electron correlation ? coefficients and ? holes in molecules

Electron correlation in the H2, LiH and BH molecules has been analyzed in terms of the statistical correlation coefficients introduced by Kutzelnigg, Del Re, and Berthier. Angular, radial (in-out), longitudinal (left-right) and transverse correlation coefficients have been evaluated from both self-consistent-field (SCF) and configuration interaction (CI) wave functions. It has been found that these coefficients reflect fairly well the correlation behavior in the molecular system. The lack of spherical symmetry in molecular densities adds new features to these correlation coefficients and this information can be useful for the study of electronic structure in molecules. The correlation hole function, Fermi and Coulomb holes in these systems have also been calculated and discussed.

Random vibrations of orthotropic plates clamped or simply supported all round

An approximate method is presented for determining the probabilistic response of rectangular orthotropic plates clamped all round. For solving the stochastic boundary value problem, the probabilistically given and sought functions are expressed in terms of series of approximate modes of vibration, which satisfy the boundary conditions but not the field equation. Galerkin's procedure then yields a set of linear equations for the cross-spectral densities of the displacements. The cross-spectral density of the external pressure is taken to be a product of longitudinal and transverse correlation coefficients which depend on frequency and separation distance.

Random vibrations of orthotropic plates clamped or simply supported all round

An approximate method is presented for determining the probabilistic response of rectangular orthotropic plates clamped all round. For solving the stochastic boundary value problem, the probabilistically given and sought functions are expressed in terms of series of approximate modes of vibration, which satisfy the boundary conditions but not the field equation. Galerkin's procedure then yields a set of linear equations for the cross-spectral densities of the displacements. The cross-spectral density of the external pressure is taken to be a product of longitudinal and transverse correlation coefficients which depend on frequency and separation distance. When the approximate method presented here is applied to cases capable of closed solutions (i.e. plates having a pair of opposite edges simply supported), the result coincides with that obtained by the classical normal-mode approach.

The influence of drag-reducing polymers on turbulence in the viscous sublayer

The influence of drag-reducing polymers on the time-averaged velocity gradient . Therefore all turbulence measurements have been normalized with wall parameters. On this basis we find that the changes in the intensity of sx, and in the shape of the spectral density functions for sx and sz are not as striking as the decrease in pressure drop caused by the addition of a polymer. The root-mean-square value of sz shows a significant decrease with an increase in drag reduction but the most spectacular change in turbulence structure seems to be associated with the transverse correlation coefficient. We conclude that the increase in drag reduction is accompanied by an increase of the size of longitudinally oriented eddies in the viscous sublayer. One possible explanation for this increase in size is that the influence of the polymer additives is such as to increase the viscous resistance in the transverse direction more than in the direction of mean flow.