In order to know the regularity of the noise effect of Hainan Eastern Ring Railway, the field measurement of Haikou section was performed. The main conclusions included that the noise increase curve of the train operation period doesn’t present the sound source attenuation characteristic. In the urban area, through monitoring noise of running trains with the different number of the roadside trees, the noise of railway traffic could be reduced. Around the train running line, monitoring indoor noise at different floors, the different regularity of the noise effects was obtained. At the same time, the level of noise when increasing the number of trains per hour in the future was predicted.

In this paper, the discontinuous element is employed for separating the Helmholtz boundary integral equation. The polar coordinate transformation in discontinuous element is employed to eliminate the singularity in the integrals. Meanwhile, the CHIEF method in addition to the Lagrange multiplier is applied to deal with the non-uniqueness at the characteristic frequencyies. On this basis, the expressions for acoustic radiation power and radiation efficiency are derived by the discontinuous element. Taking the spherical radiation and cubical radiation as numerical examples, the radiation power, radiation efficiency, radiation modes and modal radiation efficiency are computed. The results are compared with those of the existing solutions based on linear continuous element. Both simulation results are in good consistency.

To solve the problem of corner point in surface in BEM, discontinuous element is employed for the discretization of Helmholtz boundary integral equation. The polar coordinate transformation in discontinuous element is presented so as to eliminate the singularity in the integration. Meanwhile, the CHIEF method and the Lagrange multiplier are applied to deal with the non-unique solutions. The value of acoustic pressures at the nodes can be acquired by solving a set of linear algebraic equations, acoustic pressure in grid points are obtained by taking the node average values or element average values. In order to demonstrate the robustness and accuracy of the proposed method, two numerical examples of sound radiation from a pulsating sphere and a cube are presented. The results calculated by discontinuous element are compared with the results determined by continuous element. The results have verified the efficiency and adaptability of the proposed method.

A novel threshold function is constructed based on the wavelet threshold denoising method presented by D.L. Donoho and I.M. Johnstone. This new threshold function has many advantages over the traditional soft/hard threshold functions. It is simple in expression, as continuous as the softthreshold function, and highorder differentiable. Thus, it is convenient for mathematical processing. This new threshold function also overcomes the shortcoming that there is an invariable difference between the estimated wavelet coefficients and the decomposed wavelet coefficients in the soft threshold function. Meanwhile, the new threshold function is more flexible than the soft/hardthreshold function. All these advantages make it possible to construct an adaptive denoising algorithm. Simulation results indicate that the new denoising method adopting the new threshold function can suppress the PseudoGibbs phenomena near the singularities of the signal effectively. And the numerical results also show that the new method gives better MSE performance and SNR gains than the traditional hard/softthreshold methods. This method is applied to the vibration signal denoising of a bridge, and the result shows that it can eliminate the noise effectively.

A new method of fault diagnosis of in-situ sampled vibration signals is introduced for the non-stationery signals of rotating machines by using the harmonic wavelet filtering. Based on the nice box-shaped characteristic of spectrum of harmonic wavelet, the components in prescribed frequency region and other frequency components are decomposed to independent frequency bands without any overlapping or leaking. Then the frequency components in the prescribed region can be extracted by data reconstruction. Simulation results and practical examples show that this method has good filtering effect. It can extract the valuable frequency components for elementary fault diagnosis. This method has the merits of simple algorithm and computer-time saving.