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Wang H.,Zhengzhou University | Chai H.,Zhengzhou University | Chai H.,Naval Institute of Hydrographic Surveying and Charting | Wang M.,Zhengzhou University
Acta Geodaetica et Cartographica Sinica | Year: 2011

Ln view of the fact that the Ordinary Kriging algorithm will be influenced by outliers while processing multibeam bathymetry data, The calculating formula of sample variogram is deduced based on robust estimation, and the influence of outliers in fitting variogram function is controlled. The superiority of the algorithm in exactitude estimating and detecting outliers is proved by real data experiments. The regular square grids of multibeam data are also constructed by the algorithm. The grids values are compared with those which are calculated by manual processing, and they are consistent. It is proved that the seabed terrain grids can be constructed by the proposed algorithm in high precision and outliers can be detected automatically. Source


Sun X.,CAS Institute of Remote Sensing | Yang L.,CAS Institute of Remote Sensing | Zhang B.,CAS Institute of Remote Sensing | Gao L.,CAS Institute of Remote Sensing | Zhang L.,Naval Institute of Hydrographic Surveying and Charting
2013 6th International Conference on Advanced Computational Intelligence, ICACI 2013 - Proceedings | Year: 2013

Pixel clustering is a common hyperspectral image processing technique. Its process is to find the appropriate cluster centers and assign each pixel to a center according to a certain metric. Artificial Bee Colony (ABC) algorithm based pattern clustering is proved to have better performance than traditional clustering methods such as K-means. Therefore, studies on hyperspectral image clustering method based on ABC algorithm are done. The target function and feasible solution space are determined, and the complete process is given. The proposed algorithm and other algorithms are compared and analyzed with the use of two sets of real hyperspectral remote sensing data and ground survey results. © 2013 IEEE. Source


Liu M.,Binzhou University | Chang G.,Naval Institute of Hydrographic Surveying and Charting
Mathematical Problems in Engineering | Year: 2015

This paper is concerned with the topic of gravity matching aided inertial navigation technology using Kalman filter. The dynamic state space model for Kalman filter is constructed as follows: the error equation of the inertial navigation system is employed as the process equation while the local gravity model based on 9-point surface interpolation is employed as the observation equation. The unscented Kalman filter is employed to address the nonlinearity of the observation equation. The filter is refined in two ways as follows. The marginalization technique is employed to explore the conditionally linear substructure to reduce the computational load; specifically, the number of the needed sigma points is reduced from 15 to 5 after this technique is used. A robust technique based on Chi-square test is employed to make the filter insensitive to the uncertainties in the above constructed observation model. Numerical simulation is carried out, and the efficacy of the proposed method is validated by the simulation results. © 2015 Ming Liu and Guobin Chang. Source


Zheng S.,CAS South China Sea Institute of Oceanology | Du Y.,CAS South China Sea Institute of Oceanology | Li J.,Naval Institute of Hydrographic Surveying and Charting | Cheng X.,CAS South China Sea Institute of Oceanology
Ocean Science | Year: 2015

Using a geometric eddy identification method, cyclonic and anticyclonic eddies from submesoscale to mesoscale in the South Indian Ocean (SIO) have been statistically investigated based on 2082 surface drifters from 1979 to 2013. A total of 19 252 eddies are identified, 60% of them anticyclonic eddies. For the submesoscale eddies (radius r<10 km), the ratio of cyclonic eddies (3183) to anticyclonic eddies (7182) is 1 to 2. In contrast, the number of anticyclonic and cyclonic eddies with radius rge;10 km is almost equal. Mesoscale and submesoscale eddies show different spatial distributions. Eddies with radius rge;100 km mainly appear in the Leeuwin Current, a band along 25\S, Mozambique Channel, and Agulhas Current, areas characterized by large eddy kinetic energy. The submesoscale anticyclonic eddies are densely distributed in the subtropical basin in the central SIO. The number of mesoscale eddies shows statistically significant seasonal variability, reaching a maximum in October and minimum in February. © Author(s) 2015. Source


Fan L.,Naval Institute of Hydrographic Surveying and Charting | Zhai G.,Naval Institute of Hydrographic Surveying and Charting | Chai H.,Zhengzhou University
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2014

Since the round-off error affects the effect and the success rate of the down correlation along with the increase of the matrix's dimension, the idea of block Gram-Schmidt orthogonalization is introduced, and the integer block Gram-Schmidt orthogonalization algorithm is designed, meanwhile, the IBGS-LLL decorrelation algorithm is proposed combined with the LLL algorithm. The decorrelation effect of different block style is analyzed with different dimension by using the random simulation method. It is confirmed the block manner of different measuring mode. Comparison of the IBGS-LLL algorithm with the improved LLL algorithm based on simulated and measured data shows that the IBGS-LLL decorrelation algorithm possessing has better effect and higher success rate of ambiguity decorrelation. Source

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