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Hao H.D.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Bai T.Y.,QingDao Geotechnical Investigation and Surveying Research Institute | Liu G.L.,Shandong University of Science and Technology
Advanced Materials Research | Year: 2013

Phase Unwrapping (PU) is the key step in the image processing for Interferometric Synthetic Aperture Radar (InSAR). In the Extended Kalman Filter (EKF) model of PU, due to the state space model is not taken into account the terrain factors, it is often resulted in unwrapping error delivery as the pixel to the next when the state changes rapidly in steep terrain. The observation equation is nonlinear and usually applied in PU through linear processing, requiring the system model and noise statistics known. But in fact the mathematical model or statistical noise is completely or partially unknown; the results have been inevitably lead to the declining of valuation accuracy and filter divergence. If directly applied in phase unwrapping, it is made impossible to retrieve surface deformation. In order to solve this problem and fully consider the terrain effect and model error, an adaptive EKF PU algorithm (AEKFPU) for InSAR is presented. On the one hand, it is achieved local adaptive estimation of image fringe frequency through 2D FFT and Chirp-Z Transform (CZT) joint method, by considering the impact of terrain factors on unwrapping results; On the one hand, the fading factor is calculated by innovation covariance and adaptively adjusted with the error covariance so as to suppress the memory length of the filter, compensating the effect of incomplete information on unwrapping. The experimental results are proved the proposed method is effective, it can be dealt with phase unwrapping and filtering simultaneously, and can be adaptively considered terrain factors in state space model and compensated for model error in observation equation model, ultimately improving the accuracy of phase unwrapping. © (2013) Trans Tech Publications, Switzerland. Source


Meng F.,Chongqing University of Technology | Meng F.,Chinese Academy of Sciences | Zhang X.,Chongqing University of Technology | Zhang Y.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | And 3 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2013

Two different grain-size alumina materials (average grain sizes: 0.6 μm fine-grained alumina and 2 μm coarser-grained alumina) were prepared by spark plasma sintering technique. Tribological behavior and wear mechanisms of both alumina ceramics under articular biomimetic synovial fluid environment were investigated using a reciprocating friction test system. The results show that the friction coefficients of fine-grained and coarser-grained alumina under the same friction conditions (loading pressure 60 N and sliding time 30 min) are 0.245 and 0.250, respectively. The wear resistance of the fine-grained alumina is greatly improved, and the wear loss volume for the samples with finer grain is only a half lower (20 × 10-3 mm3) than that for the samples with the coarser grain. Both the fine-grained and coarser-grained alumina materials have the similar wear mechanism. In the initial wear-in period, the grain pull-out and brittle fracture caused by microcrack are the dominant wear mechanisms; When the sliding time increases, plastic deformation mechanism governs the wear characteristics. Source


Zhang Y.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Chen A.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Liu C.,Chongqing University of Technology | Wang H.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Li Z.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision
Key Engineering Materials | Year: 2012

In this study, nano ZrO 2 powders were incorporated into Al-5 wt% Zn sacrificial anode and the effect of ZrO 2 contents (wt% =0.1, 0.2) on microstructures and electrochemical properties were investigated. The results show that the addition of nano ZrO 2 was effective on improving metallurgical and electrochemical properties. With the increase of ZrO 2 content, the dendritic structure is fined gradually and the corrosion current density values is also increased. The incorporation of ZrO 2 also can result in a moderate efficiency value. When the ZrO 2 content in the alloy was 0.2 wt%, the optimal microstructure, electrochemical properties and as high as 70% the efficiency value was obtained. © (2012) Trans Tech Publications, Switzerland. Source


Zhang Y.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Chen A.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Wang H.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Li Z.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Shen Y.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision
Advanced Materials Research | Year: 2012

The present article reports the results of studies related to the synthesis of nano-crystalline ceria powder by combustion process using salt combustion aid. Cerium nitrate as oxidant and urea as fuel were used as reagents, Sodium Chloride was compared as combustion aid. The phase analysis and particle size were compared. The product was characterized by X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy. The results showed that employment of starting fuel with combustion aid resulted in synthesizing nano-crystalline ceria powder with fine agglomerates. By using combustion aid, the energetics of the combustion reaction and particle characteristics have been changed. Source


Chen A.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Zhang Y.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | Meng F.,Chongqing University of Technology | Wang H.,Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision | And 2 more authors.
Journal Wuhan University of Technology, Materials Science Edition | Year: 2011

The ZnO powder with hexagonal-pyramids structure was prepared by the low-temperature combustion process. Ammonium acetate was used as the fuels, whereas zinc nitrate acted as the oxidant. The effect of different ration between fuel and oxidant on the morphology and photoluminescence (PL) characteristic was studied. The formation of hexagonal-pyramids structure was discussed. The optimum preparing parameter for fi ne morphology is that the ratio of zinc nitrate and ammonium acetate is 1:5, and ignition temperature is 500 °C The PL measurement indicates all samples have the strong blue and yellow emission peak. The changes of surface energy of the polar surfaces result in the formation of micro-pyramids structure. © 2011 Wuhan University of Technology and Springer Verlag Berlin Heidelberg. Source

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