Applied Mechanics and Materials Vols. 530-531

Abstract: Measured data of hydrophone array could be interfered by underwater noise,so its essential to enhance the performance of suppressing interference for adaptive array processing. How to improve the performance of Double Stages Wiener Filter was discussed based on configuration principles. The influences of interference angle, array unit number and interference-to-noise ratio (INR) to suppressing interference have been analyzed through principle analysis and simulation experiments under different circumstances, including single or multiple disturb signals. Experiments show that the performance of suppressing interference depends on interference angle and INR more and array unit sum a little.

Abstract: The time delay estimation (TDE) is one of the most important techniques of characterization signal parameter. Delay parameter estimation is active in the field of signal processing. In this paper, On the basis of the basic theory method of time delay, the correlated time delay estimation, mutual-cumulants estimation and bispectrum estimation are analysed and discussed. Theoretical analysis and experimental results show that three methods is effectively used in time delay test, but higher order statistics (HOS) method can achieve the best effect. The HOS estimation method has many advantages, such as time delay estimation accuracy, high relative error small for Gaussian noise elimination ability.

Abstract: In systematic measurement and control mode composed of optics, radar and telemetry, trajectory measurement is in need of high precision. So, based on exterior trajectory parameter expressed by Hermite function, this paper proposes a multi-structure data fusion method with multisource heterogeneous measuring elements, which is called function restraint EMBET method. Based on the fusion simulation calculation and analysis of the same data of multisource heterogeneous measuring elements both using general EMBET method and function restraint EMBET method, it is proved that function restraint EMBET method is sensitive to errors, besides, it have the advantage of strong practicability and high precision.

Abstract: Volterra series take important role in nonlinear vibration analysis. For material hysteresis, it is proposed Bouc-Wen model to estimate frequency response function by using Volterra series in this paper: first, the component of hysteretic linear parameters was identified, then complex function was calculated, finally the differential equation of hysteretic systems was solved based on Harmonic detection method. It is not only for fast-identifying system parameters, but also providing for nonlinear seismic response.

Abstract: In underwater detection, a single image from the image sonar doesnt have the capacity to fully describe the surface of the interested target. In practice, a target is usually detected from various views, and similar contours and textures in a series of multi-view images can be employed. This work offers a novel technique for the fusion of a series of sonar images in multi-view detection of the same target, to improve the quality of images and repair the regions of target. The method takes advantage of Nonsubsampled Contourlet Transform (NSCT) to acquire coefficient matrixes of different resolutions and directions. Besides, a framework for sonar image fusion is set up based on morphology modification. The coefficient matrixes in NSCT domain are fused in the multi-scale framework and revised in decision-making. Experimental results show that target regions in the fused sonar images are effectively repaired and image quality also get improved evidently.

Abstract: Remote sensing image registration system has been widely applied for agriculture, forestry, geology, ocean, meteorology, hydrology and military field, which studies image correction, enhancement and registration based on digital image processing technology. This paper presents system design and realization of registration technology for remote sensing image. Remote sensing image has geometric distortion and needs digital correction by adopting polynomial method at first. Then five kinds of technology are offered to enhance the contrast of remote sensing image including histogram enhancement, grey level transformation enhancement, image smoothing, image sharpening and pseudo color enhancement. Image geometric registration algorithm is carried out to fuse images of the same area acquired at different times on different wave band at last. Test result shows that the method presented has good accuracy and quick speed for realtime application.

Abstract: ECG signal is affected by many factors such as noise and interference in the process of acquisition, which make it difficult for clinicians to interpret the ECG signal precisely and effectively. In order to detect whether an ECG signal is worthy to be interpreted by clinicians, an algorithm was proposed to assess the quality of ECG signal based on wavelet energy ratio and wavelet energy entropy. After wavelet decomposition, the ECG signals wavelet energy ratio and wavelet energy entropy were calculated in three different frequency bands, and we defined them as the quality indices to evaluate the quality of ECG signal. Experimental results show that we can achieve an accuracyof 95.2%.

Abstract: In this letter, we put forward a novel tensor-based Multiple Signal Classification (TB-MUSIC) applicable to a vector hydrophone array. For this purpose, the signal subspace is derived from the higher order singular value decomposition (HOSVD) of the third order tensor of the output model. Then the proposed method is achieved by signal subspace projection weighted with the reciprocal of principal singular values multiplying by the spatial spectrum based on TB-MUSIC. The synthetic spatial spectrum shows higher resolution and robustness under no-ideal scenarios. Monte Carlo experimental results are provided to illustrate the better performance of the proposed method.

Abstract: The hydrological processes are becoming more and more complex. Fractal dimension is one of the important measurements of complexity. This paper utilizes wavelets transform technique to calculate the fractal dimension of rainfall in July for eight stations (Yushu, Xichang, Pingshan, Lijiang, Kunming, Huili, Deqin, Lnage ) in the Jinsha River Basin. The results show: the rainfall series in the Jinsha River Basin is fractal; the approach for estimating the fractal dimension by using wavelet transform coefficients is feasible and effective; the fractal dimension of rainfall reflect the influence of factors on the rainfall.

Abstract: This paper, the problems of mathematical characteristics and measurements for three kind of uncertainty information are descussed by means of the logical analysis method. Firstly, By virtue of the analysis for the importance of uncertain information research in scientific development, a research chain: uncertainty informationinformation theorycomplexity is presented. Secondly, the mathematical characterization and measurements for three kind of uncertainty information are obtained in terms of the characteristic analysis for uncertain information .