The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. ...The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. In order to reduce the level of noise in the SO index, this paper introduces a fully data-adaptive filter based on singular spectrum analysis. Another interesting aspect of the filter is that it can be used to fill data gaps of the SO index by an iterative process. Eventually, a noiseless long-period data series without any gaps is obtained.展开更多
Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing dat...Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing data,an improved random forest filling algorithm is proposed.As a result of the horizontal and vertical directions of the electric power data are based on the characteristics of time series.Therefore,the method of improved random forest filling missing data combines the methods of linear interpolation,matrix combination and matrix transposition to solve the problem of filling large amount of electric power missing data.The filling results show that the improved random forest filling algorithm is applicable to filling electric power data in various missing forms.What’s more,the accuracy of the filling results is high and the stability of the model is strong,which is beneficial in improving the quality of electric power data.展开更多
The accuracy of target threat estimation has a great impact on command decision-making.The Bayesian network,as an effective way to deal with the problem of uncertainty,can be used to track the change of the target thr...The accuracy of target threat estimation has a great impact on command decision-making.The Bayesian network,as an effective way to deal with the problem of uncertainty,can be used to track the change of the target threat level.Unfortunately,the traditional discrete dynamic Bayesian network(DDBN)has the problems of poor parameter learning and poor reasoning accuracy in a small sample environment with partial prior information missing.Considering the finiteness and discreteness of DDBN parameters,a fuzzy k-nearest neighbor(KNN)algorithm based on correlation of feature quantities(CF-FKNN)is proposed for DDBN parameter learning.Firstly,the correlation between feature quantities is calculated,and then the KNN algorithm with fuzzy weight is introduced to fill the missing data.On this basis,a reasonable DDBN structure is constructed by using expert experience to complete DDBN parameter learning and reasoning.Simulation results show that the CF-FKNN algorithm can accurately fill in the data when the samples are seriously missing,and improve the effect of DDBN parameter learning in the case of serious sample missing.With the proposed method,the final target threat assessment results are reasonable,which meets the needs of engineering applications.展开更多
文摘The Tahiti-Darwin Southern Oscillation index provided by Climate Analysis Center of USA has been used in numerous studies. But, it has some deficiency. It contains noise mainly due to high month-to-month variability. In order to reduce the level of noise in the SO index, this paper introduces a fully data-adaptive filter based on singular spectrum analysis. Another interesting aspect of the filter is that it can be used to fill data gaps of the SO index by an iterative process. Eventually, a noiseless long-period data series without any gaps is obtained.
基金Supported by the State Grid Power Company of Hunan Province Science and Technology Project(No.5216A517000U).
文摘Missing data filling is a key step in power big data preprocessing,which helps to improve the quality and the utilization of electric power data.Due to the limitations of the traditional methods of filling missing data,an improved random forest filling algorithm is proposed.As a result of the horizontal and vertical directions of the electric power data are based on the characteristics of time series.Therefore,the method of improved random forest filling missing data combines the methods of linear interpolation,matrix combination and matrix transposition to solve the problem of filling large amount of electric power missing data.The filling results show that the improved random forest filling algorithm is applicable to filling electric power data in various missing forms.What’s more,the accuracy of the filling results is high and the stability of the model is strong,which is beneficial in improving the quality of electric power data.
基金supported by the Fundamental Scientific Research Business Expenses for Central Universities(3072021CFJ0803)the Advanced Marine Communication and Information Technology Ministry of Industry and Information Technology Key Laboratory Project(AMCIT21V3).
文摘The accuracy of target threat estimation has a great impact on command decision-making.The Bayesian network,as an effective way to deal with the problem of uncertainty,can be used to track the change of the target threat level.Unfortunately,the traditional discrete dynamic Bayesian network(DDBN)has the problems of poor parameter learning and poor reasoning accuracy in a small sample environment with partial prior information missing.Considering the finiteness and discreteness of DDBN parameters,a fuzzy k-nearest neighbor(KNN)algorithm based on correlation of feature quantities(CF-FKNN)is proposed for DDBN parameter learning.Firstly,the correlation between feature quantities is calculated,and then the KNN algorithm with fuzzy weight is introduced to fill the missing data.On this basis,a reasonable DDBN structure is constructed by using expert experience to complete DDBN parameter learning and reasoning.Simulation results show that the CF-FKNN algorithm can accurately fill in the data when the samples are seriously missing,and improve the effect of DDBN parameter learning in the case of serious sample missing.With the proposed method,the final target threat assessment results are reasonable,which meets the needs of engineering applications.
