Applied Mechanics and Materials Vols. 182-183

Abstract: Coefficients of most existing wavelets are irrational, and it costs much hardware resources when implementing on FPGA, which is inefficient especially in embedded system. Some rational wavelets can overcome this deficiency by elaborate design. Motivated by previous works on rational wavelets, we establish a hardware structure for rational 1-D symmetric biorthogonal 11-9 wavelet and implement it on Xilinx FPGA XC3S500E. The experiment reveals that the area in slices of rational 1-D 11-9 wavelet is less than 1/2 of the pipelined 9-7 wavelet when implementing on FPGA.

Abstract: It has been found that there is a very complex and chaotic phenomena in the power system and other nonlinear system. Chaos is a very complex phenomenon caused by the interaction of the parameters in nonlinear systems, its appearance will accompany the non-periodic、seems to be without rules、sudden or paroxysmal mechanical and electrical oscillation of the system, which will cause widespread blackout and disintegration of the system when the oscillation becomes serious. Therefore, due to the wind power system is a typical large-scale complex non-linear system, so that chaotic phenomena will also occur under certain conditions and chaos will influence the stable operation of the wind power system, so the chaotic research are particularly important along with the fast development of grid-connected wind power technology.

Abstract: In this paper, a chaos-based image encryption scheme with stream cipher structure is proposed. The key component of the encryption system is a pseudo-random bit generator (PRBG) based on a chaotic map and a linear feedback shift register. The proposed PRBG is not only passes the statistical tests, but also improve the security. The overall design of the image encryption scheme is to be explained while detail cryptanalysis is given.

Abstract: The fault diagnosis method based on qualitative SDG deep knowledge model has better completeness, but lower resolution. Because it ignores the fact that the effect is different between different nodes in a SDG graph. To solve this problem, a method which added the quantitative information of the effect between nodes into the qualitative SDG reasoning by granularity entropy was proposed, according to which the priority could be given to the multi-potential fault origin and the resolution could be improved. In this method, the value of the effect can be obtained by calculation of attribute state values in fault diagnosis decision table. The shortcoming of the previous fuzzy SDG fault diagnosis method can be avoided.

Abstract: A novel decision-directed Modified Constant Modulus Algorithm (DD-MCMA) was proposed firstly. Then a constellation matched error (CME) function was added to the cost function of DD-MCMA and CME-DD-MCMA algorithm was presented. Furthermore, we improve the CME-DD-MCMA by replacing the fixed step with variable step size, that is VSS-CME-DD-MCMA algorithm. The simulation results show that the proposed new blind equalization algorithms can tremendously accelerate the convergence speed and achieve lower residual inter-symbol interference (ISI) than MCMA, and among the three proposed algorithms, VSS-CME-DD-MCMA has the fastest convergence speed and the lowest residual ISI, but it has the largest computation complexity.

Abstract: This paper proposed a new image de-noising algorithm based on wavelet transform. Firstly, the algorithm made wavelet transform on the image, and then using the GGD described the wavelet coefficients of each sub band. Calculate the similarity of direction of horizontal, vertical and diagonal. Then adjust the coefficients according to similarity function. The experiment results showed that the algorithm not only remove the noise from the image but can protect the edge information of the image. The processing result had better visual effect and high signal to noise ratio.

Abstract: This paper applies a Cut-and-Sew algorithm extracting feature line of the mountain based on laser 3D scanning. The mountain is cut at the direction of contour lines. Point cloud data of the cut surface fits curve that project the same plane. Feature points find the curve corresponding to match. Through the connection of feature points, then returning the 3D space to achieve feature line, and the establishment of the formation of the triangular feature line is reconstructed on the mountain.

Abstract: A real-time sea-sky-line detection method under complicated sea-sky background is presented. Firstly, a black-white template is constructed and used for fast correlation matching in several searching regions which are predefined in input image, position of maximal correlation coefficient in each predefined region is hunt out, and coordinates of several candidate sea-sky-line points are made certain according to the position. Then, RANSAC algorithm is applied to preserve interior points which are really on the sea-sky-line and eliminate exterior points which are not. Finally, line parameters of the sea-sky-line can be gained by applying least squares line fitting for all interior points. The pixels of several regions in the image instead of the whole image need to be considered, so computational cost can be reduced dramatically. The experimental results show that the proposed method can detect out sea-sky-line under complicated sea-sky background effectively and has many advantages such as strong robustness and speedy calculation.

Abstract: Aiming at problems of poor contrast and blurred edges in degraded images, a novel enhancement algorithm is proposed in present research. The algorithm utilizes wavelet-based image fusion to accomplish the duplex enhancement task. Experiment results prove that the proposed enhancement algorithm can efficiently combine the merits of histogram equalization and sharpening, improving both the contrast and sharpness of the degraded image at the same time.

Abstract: Based on the theory that a color image can be decomposed into three primary components and each one can be seen as a gray image, we propose a color image encryption method with multiple-order discrete fractional cosine transform (MODFrCT), which is a kind of encryption with the secrecy of pixel value and pixel position simultaneously. The complex number mode that has a real part and an imaginary one is used in this encryption method to save the transmission channel. Human vision is more sensitive to the Y component than to other two components in YCbCr color space and this color format is used for encrypting the color image. Chaos is introduced to scramble the image phases both in spatial and transformation domains. The numerical simulations demonstrate the validity and efficiency of this scheme and the robustness of the method against occlusion attack is examined.