This paper applies the fractal dimension as a characteristic to describe the engine抯 operating condition and its developmental trend. A correlation dimension is one of the quantities that are usually used to characte...This paper applies the fractal dimension as a characteristic to describe the engine抯 operating condition and its developmental trend. A correlation dimension is one of the quantities that are usually used to characterize a strange attractor. With the operation of the phase space reconstruction, respective correlation dimensions of a series of vibration signals obtained under different conditions are calculated to find the intrinsic relationship between the indicator and the operating condition. The experiment result shows that the correlation dimension is sensitive to the condition evolution and convenient for the identification of abnormal operational states. In advanced prognostic algorithm based on the BP neural network is then applied on the correlation dimensions to predict the short-term running conditions in order to avoid severe faults and realize in-time maintenance. Experimental results are presented to illustrate the proposed methodology.展开更多
In this paper, a low-dimensional multiple-input and multiple-output (MIMO) model predictive control (MPC) configuration is presented for partial differential equation (PDE) unknown spatially-distributed systems ...In this paper, a low-dimensional multiple-input and multiple-output (MIMO) model predictive control (MPC) configuration is presented for partial differential equation (PDE) unknown spatially-distributed systems (SDSs). First, the dimension reduction with principal component analysis (PCA) is used to transform the high-dimensional spatio-temporal data into a low-dimensional time domain. The MPC strategy is proposed based on the online correction low-dimensional models, where the state of the system at a previous time is used to correct the output of low-dimensional models. Sufficient conditions for closed-loop stability are presented and proven. Simulations demonstrate the accuracy and efficiency of the proposed methodologies.展开更多
The dynamic research of landslide is one of the key Points in landslidology. In the paper,from the view point of nonlinear dynamic theory. some features of Xintan landslide, such as the distribution regularities of sp...The dynamic research of landslide is one of the key Points in landslidology. In the paper,from the view point of nonlinear dynamic theory. some features of Xintan landslide, such as the distribution regularities of spatial and temporal fractal dimensions and their corresponding relationships to landslide occurring are researched. The accumulative principles of fractal dimension reduction is exploratively pointed out. The nonlinear dynamic equation of the landslide is built by analyzing the relationship between the correlation dimension and the phase space. Finally, the forecasted results and error analysis are listed. The research results are satisfactory.展开更多
For summer monsoon rainfall purpose India is divided into 35 subdivisions. The daily rainfall series of one such subdivision (Konkan) has been analysed using the phase space approach. Fifteen years (1959-1973) of dail...For summer monsoon rainfall purpose India is divided into 35 subdivisions. The daily rainfall series of one such subdivision (Konkan) has been analysed using the phase space approach. Fifteen years (1959-1973) of daily rainfall data have been utilised in this study. The .analysis shows that the variability is due to the existing of strange attractor of dimension about 3.8. The predictability is estimated by computing the Lyapunov characteristic exponent. The computations show that the predictability is about 8 days.展开更多
An improved model for numerically predicting nonlinear wave forces exerted on an offshore structure is pro- posed.In a previous work[9],the authors presented a model for the same purpose with an open boundary condi- t...An improved model for numerically predicting nonlinear wave forces exerted on an offshore structure is pro- posed.In a previous work[9],the authors presented a model for the same purpose with an open boundary condi- tion imposed,where the wave celerity has been defined constant.Generally,the value of wave celerity is time-de- pendent and varying with spatial location.With the present model the wave celerity is evaluated by an upwind dif- ference scheme,which enables the method to be extended to conditions of variable finite water depth,where the value of wave celerity varies with time as the wave approaches the offshore structure.The finite difference method incorporated with the time-stepping technique in time domain developed here makes the numerical evolution effec- tive and stable.Computational examples on interactions between a surface-piercing vertical cylinder and a solitary wave or a cnoidal wave train demonstrates the validity of this program.展开更多
文摘This paper applies the fractal dimension as a characteristic to describe the engine抯 operating condition and its developmental trend. A correlation dimension is one of the quantities that are usually used to characterize a strange attractor. With the operation of the phase space reconstruction, respective correlation dimensions of a series of vibration signals obtained under different conditions are calculated to find the intrinsic relationship between the indicator and the operating condition. The experiment result shows that the correlation dimension is sensitive to the condition evolution and convenient for the identification of abnormal operational states. In advanced prognostic algorithm based on the BP neural network is then applied on the correlation dimensions to predict the short-term running conditions in order to avoid severe faults and realize in-time maintenance. Experimental results are presented to illustrate the proposed methodology.
基金supported by National High Technology Research and Development Program of China (863 Program)(No. 2009AA04Z162)National Nature Science Foundation of China(No. 60825302, No. 60934007, No. 61074061)+1 种基金Program of Shanghai Subject Chief Scientist,"Shu Guang" project supported by Shang-hai Municipal Education Commission and Shanghai Education Development FoundationKey Project of Shanghai Science and Technology Commission, China (No. 10JC1403400)
文摘In this paper, a low-dimensional multiple-input and multiple-output (MIMO) model predictive control (MPC) configuration is presented for partial differential equation (PDE) unknown spatially-distributed systems (SDSs). First, the dimension reduction with principal component analysis (PCA) is used to transform the high-dimensional spatio-temporal data into a low-dimensional time domain. The MPC strategy is proposed based on the online correction low-dimensional models, where the state of the system at a previous time is used to correct the output of low-dimensional models. Sufficient conditions for closed-loop stability are presented and proven. Simulations demonstrate the accuracy and efficiency of the proposed methodologies.
文摘The dynamic research of landslide is one of the key Points in landslidology. In the paper,from the view point of nonlinear dynamic theory. some features of Xintan landslide, such as the distribution regularities of spatial and temporal fractal dimensions and their corresponding relationships to landslide occurring are researched. The accumulative principles of fractal dimension reduction is exploratively pointed out. The nonlinear dynamic equation of the landslide is built by analyzing the relationship between the correlation dimension and the phase space. Finally, the forecasted results and error analysis are listed. The research results are satisfactory.
文摘For summer monsoon rainfall purpose India is divided into 35 subdivisions. The daily rainfall series of one such subdivision (Konkan) has been analysed using the phase space approach. Fifteen years (1959-1973) of daily rainfall data have been utilised in this study. The .analysis shows that the variability is due to the existing of strange attractor of dimension about 3.8. The predictability is estimated by computing the Lyapunov characteristic exponent. The computations show that the predictability is about 8 days.
基金China National Sicence Foundation with Grant No.91870003
文摘An improved model for numerically predicting nonlinear wave forces exerted on an offshore structure is pro- posed.In a previous work[9],the authors presented a model for the same purpose with an open boundary condi- tion imposed,where the wave celerity has been defined constant.Generally,the value of wave celerity is time-de- pendent and varying with spatial location.With the present model the wave celerity is evaluated by an upwind dif- ference scheme,which enables the method to be extended to conditions of variable finite water depth,where the value of wave celerity varies with time as the wave approaches the offshore structure.The finite difference method incorporated with the time-stepping technique in time domain developed here makes the numerical evolution effec- tive and stable.Computational examples on interactions between a surface-piercing vertical cylinder and a solitary wave or a cnoidal wave train demonstrates the validity of this program.