When linear regressive models such as AR or ARMA model are used for fitting and predicting climatic time series,results are often not sufficiently good because nonlinear variations in the time series.In this paper, a ...When linear regressive models such as AR or ARMA model are used for fitting and predicting climatic time series,results are often not sufficiently good because nonlinear variations in the time series.In this paper, a nonlinear self-exciting threshold autoregressive(SETAR)model is applied to modeling and predicting the time series of flood/drought runs in Beijing,which were derived from the graded historical flood/drought records in the last 511 years(1470—1980).The results show that the modeling and predicting with the SETAR model are much better than that of the AR model.The latter can predict the flood/drought runs with a length only less than two years,while the formal can predict more than three-year length runs.This may be due to the fact that the SETAR model can renew the model according to the run-turning points in the process of predic- tion,though the time series is nonstationary.展开更多
Functional knowledge integration is the initial and core phase of a design process. It is the key phase to ensure that the functional requirement of the design product can be appropriately complied with, and its resul...Functional knowledge integration is the initial and core phase of a design process. It is the key phase to ensure that the functional requirement of the design product can be appropriately complied with, and its result is also the rudiment of the subsequent detailed design work. If this important phase can be supported by an increasingly distributed resource environment, and be automated such that its completion requires less manual work, the efficiency of the design process would be largely improved and its ability to promote innovation would be enhanced. Therefore, this study involved a detailed analysis of the functional knowledge integration of the design process, as well as the proposal of a corresponding running model. Based on the model, a computational algorithm and an evaluating method were established to automate functional knowledge integration. A corresponding computer program was developed to prove the feasibility of this approach, and it was used to design a solarpowered wiper blade.展开更多
文摘When linear regressive models such as AR or ARMA model are used for fitting and predicting climatic time series,results are often not sufficiently good because nonlinear variations in the time series.In this paper, a nonlinear self-exciting threshold autoregressive(SETAR)model is applied to modeling and predicting the time series of flood/drought runs in Beijing,which were derived from the graded historical flood/drought records in the last 511 years(1470—1980).The results show that the modeling and predicting with the SETAR model are much better than that of the AR model.The latter can predict the flood/drought runs with a length only less than two years,while the formal can predict more than three-year length runs.This may be due to the fact that the SETAR model can renew the model according to the run-turning points in the process of predic- tion,though the time series is nonstationary.
基金supported by the National Natural Science Foundation of China(Grant No.51575342)
文摘Functional knowledge integration is the initial and core phase of a design process. It is the key phase to ensure that the functional requirement of the design product can be appropriately complied with, and its result is also the rudiment of the subsequent detailed design work. If this important phase can be supported by an increasingly distributed resource environment, and be automated such that its completion requires less manual work, the efficiency of the design process would be largely improved and its ability to promote innovation would be enhanced. Therefore, this study involved a detailed analysis of the functional knowledge integration of the design process, as well as the proposal of a corresponding running model. Based on the model, a computational algorithm and an evaluating method were established to automate functional knowledge integration. A corresponding computer program was developed to prove the feasibility of this approach, and it was used to design a solarpowered wiper blade.
