Advanced Materials Research Vols. 546-547

Abstract: The influence of frequency synchronization error on SAR imaging and moving target detection using Along-Track Interferometry (ATI) is researched. The expression of frequency synchronization error and its influence on SAR imaging is analyzed in detail firstly. Then, the basic theory of ATI to detect moving targets is introduced in brief, the ATI in range-Doppler domain is given and the influence of frequency synchronization error on the interferometric phase in range-Doppler domain is analyzed. The influence of three kinds of frequency synchronization error is given: the main lobe shift from the inherent frequency error, the main lobe expansion from the linear frequency error, and the sidelobe rise from the sinusoidal frequency error. Simulation is used to confirm the analysis.

Abstract: A kind of novel subspace pursuit method is proposed to reduce the complexity of subspace pursuit. The modified differential evolution algorithm (MDEA) is applied to the modified subspace pursuit (MSP) by choosing chirplet function as match atoms. A steel pipe with holes is detected by guided wave and the measured signal is decomposed and reconstructed by MSP. The matched result is compared to the process result from MP with DEA. The SNR of the processed signal is improved obviously, and the defect echo can be identified easily. The matched parameters get by MSP and MP are compared and analyzed. The Wigner-Ville distribution (WVD) of the detection signal and its matched result are computed and compared. The WVD of the detection signal is enhanced after processed by MSP. The defect locations and the center frequency of the excitation signal are more exactly get from MSP than from MP. The computation time by MSP is a little longer than by MP. Therefore, MSP is a useful signal recognition and defect location approach for pipes guided wave NDT.

Abstract: This paper integrates the sensing technology, information science, artificial intelligence theory, computer technology and traditional structures safety monitoring theory, gives out a comprehensive system of the Tunnel engineering structure safety monitoring which integrated with the safety of the structure information extraction, comprehensive processing and analysis, structure diagnosis and safety evaluation process. Established a set of scientific and reasonable theory and method of structure safety monitoring of tunnel project.

Abstract: A detection method which selective fuses the nine detection results of RGB, YCbCr and HSI color space according to the image color space relative independence of each component and complementarities is approached in order to improve vehicle video detection accuracy. The method fuses three different detection results in nine components by the value of H when the value of both S and I are higher and does another three detection results when the value of both S and I are smaller. Experiments show that the method compared to the traditional method using only the detection results of the brightness component improved substantial, reduced empty of the detected vehicle a large extent and increased traffic information data accuracy depending on the detection result.

Abstract: Energy holes problem is one of key issues for wireless sensor networks (WSN). At present, the resolved strategies mainly focus on non-uniform node distribution and adjusting transmission power. However, some costs are incurred by non-uniform node distribution. With the number of nodes increasing, the total number of nodes grows exponentially, and there is a need to improve physical conditions when we increase transmission power significantly in large class of network model; To overcome the limitation, we propose the strategy of data fusion, whose reason is that it is not limited to the size of network, and does not need complicated physical conditions. In this paper, we first establish a network model Multiple-Layer and Multiple-Clusters in corona model (MLMC) to analyze the loading energy consumption. What’s more, we consider energy consumption when network is constructed. Furthermore, we fully introduce our strategy of data fusion, and prove two theorems to balance energy consumption for resolving energy holes problem. Finally, we compare and analyze the total energy consumption and network lifetime between before and after data fusion. The experimental results demonstrate the performance advantages of our approach. The best is to read these instructions and follow the outline of this text.

Abstract: In this paper, we present a stereo matching algorithm based on planar surface hypothesis. It improves the results of low texture regions and mixed pixels on object boundaries. First, regions are segmented by applying the mean-shift segmentation method. Then we propose a coarse-to-fine algorithm to increase the reliable correspondences in low texture regions. Third, the Belief Propagation algorithm is used to optimize disparity plane labeling. Finally, for a mixed pixel, we utilize the results of the depth plane and the local region of it to regulate its disparity. Experimental results using the Middlebury stereo test show that the performance of our method is high.

Abstract: Direct Sequence Spread Spectrum (DSSS) Communication has been widely applied in Personal communications network, WLAN, the third-generation mobile communications, satellite communications systems, military tactics communications and etc, thanks to the DSSS signals’ strong anti-interference ability, low probability of being intercepted and outstanding multi-access communication ability. At the same time, the Problem of estimating Signals has been of great research interest with the development of wind-band weak signals processing and communication antagonism. A new effective detection method of DSSS is proposed, combined the method of wavelet transformation with cycle spectral correlation approach, from the perspective of jamming in non-cooperation condition, and a simulation result of signals--BPSK is given.

Abstract: As an essential branch of over the horizon radar (OTHR), ship borne OTHR contains several important issues, the most significant one of which is how to detect and resolve signal from the broadened first order Bragg lines of unexpected platform motion in the same Doppler resolution cell. In this paper, a theory is proved that the signal’s azimuth is different from the first order sea clutters’ in the same Doppler resolution cell, based on which the spatial super resolution could be used to detect and resolve signal from the first order sea clutters in the echo spatial spectrum. In the ocean, the environment is much more complicated, the signals are also coherent of the widespread multi path effects and the noises are spatial correlated between array elements. MUSIC is failed in this field. Symmetric forward and back spatial smoothing (SFBSS) algorithm is proposed in this paper. The correctness and efficiency are proved by our simulation. This method has a high accuracy and a certain actual value to detect and resolve signal in ship borne OTHR.

Abstract: Due to the affect of illumination conditions when taking face image, the traditional algorithm effect of face recognition in practice is unsatisfied. Thus, in order to reduce the affect of illumination conditions, the pretreatment of illumination compensation to face image is needed. The common illumination compensation algorithms have two kinds: linear compensation and nonlinear compensation, such as histogram equalization method, log algorithm, and so on, but those algorithms only perform localized enhancement for image and they cannot really reflect the original image. In this paper, a kind of illumination compensation algorithm based on color constant theory is put forward. An image is mainly made of reflection image and incident image convolution. With color constancy, the incident image is not subject to the influence of illumination conditions and reflection image weakens image effect. Thus, if the incident image is found, the image is enhanced. Firstly, the acquisition method of incident image is analyzed. By the decomposition of Gaussian function, the incident image can be obtained, which provides a theoretical basis for the obtainment of incident image. Then, the expression of Retinex is analyzed. Secondly, we analyze the algorithm based on Retinex. In the horizontal direction and vertical direction of image, compensation is performed and the image after compensation is expanded, so that the compensation image is obtained. Lastly, the illumination compensation results of face image by face image database CMU are given. Compared with the original image, the results show that there is obvious enhancement effect. The recognition rate of face image in complex illumination conditions is improved.

Abstract: Multi-stitching ballistic camera is the main optical instrument devices in the range instrumentation. Wide field of view and high precision are the main features of the ballistic camera. Due to the bad environment and transportation, there exists large impact on the precision of the devices. Under the condition of out-field, it is hard to re-modeling and re-calibration of the devices. In this paper, multi-region segmentation modeling synthesis calibration techniques based on star calibration is proposed. Experiment results show that the proposed algorithm can rectify the wide field of view optical distortion, the rotation of image surface and the center points and effectively improve the test precision of the ballistic camera.