Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2019-01-03 Cooperative journals: 《计算机应用研究》
Abstract： The density peak clustering algorithm was a new density-based clustering algorithm, the algorithm requires only one input parameter and does not require frequent iterative processes. However, the original algorithm only considers the global structure of the data, and the effect is not ideal when clustering data sets with uneven distribution. Moreover, the original algorithm only selects the cluster center according to the distribution of points on the decision graph, which is not reliable. Aiming at the above problems, an improved density peak clustering algorithm based on weighted K-nearest neighbor is proposed. The idea of nearest neighbor algorithm is introduced into the density peak clustering algorithm, the local density of each data point is redefined and calculated, and determine the critical point of the cluster center by the trend of the slope of the weight. The improved algorithm is compared with the original density peak clustering algorithm, K-MEANS algorithm and DBSCAN algorithm by experiments on the artificial dataset and UCI real dataset. It is proved that the improved algorithm can deal with the density uneven dataset and find clusters of arbitrary shapes. On the three cluster performance indicators, the improved algorithm is generally higher than the other three algorithms.
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： In sky coverage analysis, we present an efficient algorithm based on a coordinate transformation method to calculate the points on the boundary of detection field. In this method, the complexity of coordinates transformation is reduced by building a new Celestial Coordinates. Based on this algorithm, QTM, a coding method that has many advantages can be used to manage the data calculated. The main contents of this topic include: to build the quantitative calculation model for sky coverage; to establish the rasterized expression method of sky coverage analysis results; and to verify the method, analyse the accuracy of the method, compare the efficiency with the attitude-matrix transformation method and analytical method.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： So far the analysis method of detective coverage in multipoint coupling plasma detective missions on space processes is still at the stage of qualitative analysis. Statistical analysis of a certain space region for the satellites also cannot undergo further quantitative analysis. To meet the needs of fast development of space science missions, on the basis of correlation function and space processes analysis, a coverage analysis method based on theta-tR coverage diagram is proposed. By analysis of theta-tR coverage diagram in accumulative time period of various design alternative, the appropriate design can be chosen according to the characteristics of coverage range. Then quantitative analysis is made on multipoint coupling detective processes of two coplanar elliptic orbits, with which the method is verified.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： In sky coverage analysis, we present an efficient algorithm based on a coordinate transformation method to calculate the points on the boundary of detection field. In this method, the complexity of coordinates transformation is reduced by building a new Celestial Coordinates. Based on this algorithm, QTM, a coding method that has many advantages can be used to manage the data calculated. The main contents of this topic include: to build the quantitative calculation model for sky coverage;to establish the rasterized expression method of sky coverage analysis results;and to verify the method, analyse the accuracy of the method, compare the efficiency with the attitude-matrix transformation method and analytical method.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： In order to choose the best detection efficiency of different formations, quantitative evaluation of different formations shall be employed. In this paper, the existing evaluation parameters of four-point cooperative detection are analyzed and summarized and then based on the definition of volumetric tensor, the five-point formation is divided into five tetrahedrons and one main tetrahedron plus a fifth point to evaluate the detection efficiency. Finally, orbit data of five-spacecraft in one orbit period is used to simulate and analyze the two methods, and result shows that the method works well in evaluating five-point formation.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-04
Abstract： Adjacency effect of the optical remote sensing could be regarded as the convolution of the atmospheric point spread function(PSF) and the surface-leaving radiance. By simulating the atmospheric PSF with backward Monte Carlo method and calculating the surface-leaving radiance with MODTRAN model,the at-sensor radiance was obtained. The adjacency effects for different target and background under different propagation conditions were simulated and analyzed. The results show that target and background reflectivity affect adjacency effect significantly and the percentage of the radiance caused by the adjacency effect in the total radiance increases with the increase of the background reflectivity. Adjacency effect for dark target under bright background is more obvious than that for bright target under dark background. Given imaging height and area, the higher the imaging space resolution, the stronger the adjacency effect is. Effect of the surface meteorological range on adjacency effect is of high importance. The larger the surface meteorological range, the bigger the sun zenith angle, the weaker the adjacency effect is. These results could provide the basis for modeling the optical remote sensing imaging system with high precision and exploring the correction algorithm of the adjacency effect.
Peer Review Status:Awaiting Review
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