Primary component analysis method and reduction of seismicity parameters

In the paper, the primary component analysis is made using 8 seismicity parameters of earthquake frequency N (ML≥3.0), b-value, η-value, A(b)-value, Mf-value, Ac-value, C-value and D-value that reflect the characteristics of magnitude, time and space distribution of seismicity from different respects. By using the primary component analysis method, the synthesis parameter W reflecting the anomalous features of earthquake magnitude, time and space distribution can be gained. Generally, there is some relativity among the 8 parameters, but their variations are different in different periods. The earthquake prediction based on these parameters is not very well. However, the synthesis parameter W showed obvious anomalies before 13 earthquakes (MS≥5.8) occurred in North China, which indicates that the synthesis parameter W can reflect the anomalous characteristics of magnitude, time and space distribution of seismicity better. Other problems related to the conclusions drawn by the primary component analysis method are also discussed.

Air Traffic Operation Complexity Analysis Based on Metrics System

In order to quantitatively analyze air traffic operation complexity,multidimensional metrics were selected based on the operational characteristics of traffic flow.The kernel principal component analysis method was utilized to reduce the dimensionality of metrics,therefore to extract crucial information in the metrics.The hierarchical clustering method was used to analyze the complexity of different airspace.Fourteen sectors of Guangzhou Area Control Center were taken as samples.The operation complexity of traffic situation in each sector was calculated based on real flight radar data.Clustering analysis verified the feasibility and rationality of the method,and provided a reference for airspace operation and management.

Classification of Principal Wood Species in China Based on the Physiomechanical Properties

Many tree species are planted in China with variable properties and usage.Toward exploring the structure-properties relationships of wood and classifying the species more reasonably,the physiomechanical properties of the domestic wood species in China were analyzed statistically.According to the correlation analysis,the mechanical properties were closely related to the wood density.Except impact toughness and cleavage strength,the correlation coefficients between mechanical properties and densities were more than 0.8.However,shrinkage properties showed fewer correlations with densities,and the coefficient was no more than 0.7.Primary component analysis was proved to be feasible to explore the information of the physiomechanical properties.Two principal components(PC1 and PC2)could account for most of the information.PC1 and PC2 were designated as density-dominated and shrinkage-associated factors,respectively.The domestic wood species in China could be classified into 4 clusters based on their physiomechanical properties.According to the cluster results,reasonable grading was proposed for air-dried density,volume shrinkage,modulus of rupture,compression strength parallel to grain and hardness in cross section.The statistical results brought insights into analyzing the physiomechanical properties of domestic Chinese wood species,which was helpful for developing strategies of tree breeding and technologies of wood processing.