Applied Mechanics and Materials Vols. 687-691

Abstract: With the rapid development of the network, a new public welfare communication way has risen, that is micro-blog public welfare communication. The micro-blog reduces the threshold of the public participating the public welfare activities. Thus, everyone can take part in the public welfare communication.

Abstract: Compressed sensing theory is a new signal processing theory in recent years, which is the birth of the signal processing field. Compared to the traditional Nyquist sampling rate, with little sample data quantity, compressed sensing theory saves subsequent processing time and storage space, making it a broad application prospect in the signal processing field. This paper first discuss the three key problems of the application of the compressed perception theory: signal sparse representation, machine measurement matrix design and signal reconstruction algorithm, preliminarily study the application of the compression perception theory in image compression technology, and giving the reconstructed image under different compression rate and PSNR. Computer simulation results show the feasibility of theory.

Abstract: Mutation point feature of power quality (PQ) disturbance signals are very conducive to the wavelet-based detection and localization of PQ events, but the PQ signals are often disturbed by noise. In order to suppress noise and keep mutation points, an improved threshold function was proposed. According to the fact that the wavelet coefficients of signal and noise distributed on different scale, the threshold σj2lnk amended by to calculate threshold value for each scale adaptively. (k is the number of wavelet coefficients at level j). In simulation, four type of PQ signals and three degrading degrees are testing; meanwhile, four existing algorithm with wavelet shrinkage are performed for comparison. Results reveal that the proposed scheme not only suppresses noise of PQ signal well but also keeps the mutation points nicely.

Abstract: Aiming at the weak noise signals the existence of plant diseases and insect pest images, pathological activity regulation of identification of the plant, so that between the signal molecules exist in plants can regulate mutually, collaborative work. Therefore, identification of weak signal molecules in plants is significant to the study of plant life activities. Taking corn pest images as the research object, using the identification method of lifting wavelet transform, combined with image identification technology, calculated the original plant diseases and insect pest images by not detect the break point of signal. Simulation results show that, the analysis of lifting wavelet of plant disease image identification technology reliability is about 71.65%; the accuracy of edge detection is about 76.21%. The operation speed of this algorithm is fast, easy for hardware implementation, provides an effective method for plant disease images identification.

Abstract: Hyperspectral image classification is difficult due to the high dimensional features but limited training samples. Tri-training learning is a widely used semi-supervised classification method that addresses the problem of lacking of labeled examples. In this paper, a novel semi-supervised learning algorithm based on tri-training method is proposed. The proposed algorithm combines margin sampling (MS) technique and differential evolution (DE) algorithm to select the most informative samples and perturb them randomly. Then the samples we obtained, which can fulfill the labeled data distribution and introduce diversity to multiple classifiers, are added to training set to train base classifiers for tri-training. The proposed algorithm is experimentally validated using real hyperspectral data sets, indicating that the combination of MS and DE can significantly reduce the need of labeled samples while achieving high accuracy compared with state-of-the-art algorithms.

Abstract: An important requirement for assessing technology for wireless applications is to have an accurate description of the wireless channel. Rayleigh and Rice are the most popular models for wireless channels. In this paper, we simulation study the most important statistical properties, such as PDF and CDF, of Rayleigh and Rice channels, we also simulate the outputs of complex signals which passed the Rayleigh and Rice channels, and give some useful results.

Abstract: Segmentation of noisy images is one of the most challenging problems in image analysis. It hasn’t yet been solved very well. In this paper, we propose a new method for image segmentation, which is able to segment two kinds of noisy images. The experimental results prove that Artificial Bee Colony Algorithm performs better for two types of noisy images.

Abstract: Because of the limit of the optical lens’s depth, the objects of different distance usually cannot be at the same focus in the same picture, but multi-focus image fusion can obtain fusion image with all goals clear, improving the utilization rate of the image information ,which is helpful to further computer processing. According to the imaging characteristics of multi-focus image, a multi-focus image fusion algorithm based on redundant wavelet transform is proposed in this paper. For different frequency domain of redundant wavelet decomposition, the selection principle of high-frequency coefficients and low-frequency coefficients is respectively discussed .The fusion rule is that,the selection of low frequency coefficient is based on the local area energy, and the high frequency coefficient is based on local variance combining with matching threshold. As can be seen from the simulation results, the method given in the paper is a good way to retain more useful information from the source image , getting a fusion image with all goals clear.

Abstract: Synthetic Aperture Radar (SAR) is generally considered as an all-time and all-weather system. However, weather conditions will sometimes still affect the SAR imaging, especially when rain rate or operating frequencies are increased. In this paper, the influence of rainfall attenuation in multi-band 3-D complex target SAR imaging is investigated. As SAR echo can be considered as scattering from the target illuminated by incident wave, physical optics (PO) method is used to compute the scattered data because of its good balance between efficiency and accuracy in high frequency band. Numerical results demonstrate the rain attenuation impact on SAR image, when the relationship between rain rate and precipitation attenuation in multi-frequency band are quantitative analyzed.

Abstract: As human society to the information in the process of moving and growing demand for bandwidth communications capacity, the optical of new modulation formats increasingly attention and quickly play an important role in optical communications. How can the system bit error rate within a certain degree of stability while still maintaining high-speed long-distance dispersal system, has been a popular issue is the optical communications industry. Starting from the optical modulation format herein, the generation process of the system introduced various optical signal modulation format, the optical signal through the optical fiber was studied and the performance of the simulation, on the basis of the design of advanced optical modulation formats in an optical fiber communication system .