Advanced Materials Research Vols. 518-523

Abstract: A model of BP neural network for road traffic noise prediction was established by using some road traffic parameters in this paper. Then use this model to predict equivalent continual sound level of road traffic noise, After an overview about the neural approach, the learning; and production phase results are shown and contrasted with the measured data. They point out how good is the approach proposed to model noise pollution in urban areas.

Abstract: According to the problem of the identification and localization of a known object in a scene, satisfied detection results can not be achieved using traditional detectors for images in photon-limited noise, an algorithm named Generalized Likelihood Ratio Test (GLRT) was derived for detecting known objects in a noisy scene. We used this algorithm to evaluate the existence of tiger in photons-limited images. Results show that the GLRT algorithm is effectiveness in detecting and localizing a known object embedded in a background image from photon-limited observations.

Abstract: In order to solve the endpoint effect and modal aliasing phenomenon in EMD and EEMD,Improved EEMD is put forward, and the application in signal singularity detection is researched in this paper. The improved EEMD will signal drops down into a series of different IMF to highlight the different local characteristics of original data, and then calculate Hilbert marginal spectrum and time-frequency spectrum to determine the frequency of these mutations and mutations position. To compared with FT, STFT, WVD,WT, EMD and EEMD etc, No cross-terms and no false IMF components are produced in the Hilbert time-frequency spectrum of the improved EEMD. Different frequency components and frequency mutations position are clearly distinguished at the same time. The Hilbert time-frequency spectrum of the improved EEMD has more superior detection signal singularity ability.

Abstract: The response characteristics to the seismic action of displacement for abutment are the important part of security evaluation, earthquake resistance and disaster mitigation in the seismic region. This paper decomposes the displacement of abutment into the slip displacement and rotation displacement two parts, respectively proposes the translational and rotational displacement model of abutment and establishes the corresponding calculation formulas. The case analysis indicates that the response characteristics of abutment displacement to the seismic action are comparatively sensitive, in which the translational displacement appears positive response relationship with the acceleration of seismic, while the rotational displacement appears negative response relationship. However, it holds significant mutation from 0.5g to 0.6g for both of the translational displacement and rotational displacement. In other words, the seismic acceleration from 0.5g to 0.6g should be paid highly attention in doing seismic resistance design in the seismic region.

Abstract: Free damping treatment for a marine life hoist of the helicopter is analyzed in this paper. Based on the pipe structure used in actual life hoist bracket, the complex rigidity method is used to analyze the damping loss factor of the pipe structure. When the temperature is 30°C and the thickness of the damping material is 2.5mm, the damping loss factor of the structure increases by 9.83 times. The damping ratio of the first mode reaches 11.61%. The results indicate that the free damping treatment can obviously increase the damping loss factor and the modal damping ratio of the structure, which can mitigate structural vibration and reduce noise induced by the vibration.

Abstract: A calculation method of lowest band gap starting frequency corresponding to filling fraction of fixed periodic size one dimension phononic crystals are given, found the filling fraction only correlation with the density of two materials, but no correlation with elastic modulus, furthermore found no correlation with periodic size.

Abstract: A power system on hybrid electric vehicle (HEV) was chosen for research. On the basis of analysis of characteristic parameters of motor on system, the hybrid system’ dynamics characteristic under electro-mechanical coupling was completely studied. The vibration of hybrid power system was qualitatively studied on theory and experiments when motor were under two different kinds of mode from electricity to push, and two results were consistent with each other well.

Abstract: A rule of response of an infinite viscous-elastic half-space stimulated by the moving loads of different speeds is outlined in this paper. In order to obtain a three-dimensional analytical solution of the Viscous-elastic half-space with the moving loads of different speeds, the Laplace transform and relative coordinate transformation in cylindrical coordinates are used. Then, the IFFT and relative coordinate transformation are used to solve two-dimensional infinite integration which can greatly improve the operational efficiency. The rules of responses of different velocities from the results by using the principle of dynamics and energy dissipation are also analyzed and induced in this paper, and obtain the incentives of displacement distortion by the super-Rayleigh wave velocity at surface. The results could be referred in improving the practical security in the project.

Abstract: The dynamic response of double cantilever vibro-impact system such as the stability of periodic motion, bifurcation etc., is an extremely important research content. However, the system dynamic characteristics are often influenced by the system parameters. Therefore, the theoretical modal of a double cantilevers vibro-impact system was established in this work, and the influence of clearance, damping and cubic nonlinear item on the dynamic characteristics of double cantilever vibro-impact system is detailedly analyzed through the numerical method .The results is helpful to analyze the practical engineering and to explore the nonlinear phenomena and the instability mechanism of the vibro-impact system such as milling process.

Abstract: This paper presents a random noise reduction method based on ensemble empirical mode decomposition (EEMD) and wavelet threshold filtering. Firstly, we have conducted spectrum analysis and analyzed the frequency band range of effective signals and noise. Secondly, we make use of EEMD method on seismic signals to obtain intrinsic mode functions (IMFs) of each trace. Then, wavelet threshold noise reduction method is used on the high frequency IMFs of each trace to obtain new high frequency IMFs. Finally, reconstruct the desired signal by adding the new high frequency IMFs on the low frequency IMFs and the trend item together. When applying our method on synthetic seismic record and field data we can get good results.