Purpose–The study aims to provide a basis for the effective use of safety-related information data and a quantitative assessment way for the occurrence probability of the safety risk such as the fatigue fracture of t...Purpose–The study aims to provide a basis for the effective use of safety-related information data and a quantitative assessment way for the occurrence probability of the safety risk such as the fatigue fracture of the key components.Design/methodology/approach–The fatigue crack growth rate is of dispersion,which is often used to accurately describe with probability density.In view of the external dispersion caused by the load,a simple and applicable probability expression of fatigue crack growth rate is adopted based on the fatigue growth theory.Considering the isolation among the pairs of crack length a and crack formation time t(a∼t data)obtained from same kind of structural parts,a statistical analysis approach of t distribution is proposed,which divides the crack length in several segments.Furthermore,according to the compatibility criterion of crack growth,that is,there is statistical development correspondence among a∼t data,the probability model of crack growth rate is established.Findings–The results show that the crack growth rate in the stable growth stage can be approximately expressed by the crack growth control curve da/dt=5 Q•a,and the probability density of the crack growth parameter Q represents the external dispersion;t follows two-parameter Weibull distribution in certain a values.Originality/value–The probability density f(Q)can be estimated by using the probability model of crack growth rate,and a calculation example shows that the estimation method is effective and practical.展开更多
This paper proposes an effective method for reducing test data volume undermultiple scan chain designs. The proposed method is based on reduction of distinct scan vectorsusing selective don't-care identification. ...This paper proposes an effective method for reducing test data volume undermultiple scan chain designs. The proposed method is based on reduction of distinct scan vectorsusing selective don't-care identification. Selective don't-care identification is repeatedlyexecuted under condition that each bit of frequent scan vectors is fixed to binary values (0 or 1).Besides, a code extension technique is adopted for improving compression efficiency with keepingdecompressor circuits simple in the manner that the code length for infrequent scan vectors isdesigned as double of that for frequent ones. The effectiveness of the proposed method is shownthrough experiments for ISCAS'89 and ITC'99 benchmark circuits.展开更多
Based on TBB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the tr...Based on TBB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the transition begins as early as in April, followed by abrupt change in May-June; the Asian summer monsoon situation is fully established in June. The winter convective center in Sumatra moved steadily northwestward across the "land bridge" of the maritime continent and the Indo-China Peninsula as time goes from winter to summer, thus giving rise to the change in large scale circulations that is responsible for the summer monsoon establishment over SE Asia and India; the South China Sea to the western Pacific summer monsoon onset bears a close relation to the active convection in the Indo China Peninsula and steady eastward retreat of the subtropical TBB high-value band,corresponding to the western Pacific subtropical high.展开更多
In this paper the fault tolerant synchronization of two chaotic systems based on fuzzy model and sample data is investigated. The problem of fault tolerant synchronization is formulated to study the global asymptotica...In this paper the fault tolerant synchronization of two chaotic systems based on fuzzy model and sample data is investigated. The problem of fault tolerant synchronization is formulated to study the global asymptotical stability of the error system with the fuzzy sampled-data controller which contains a state feedback controller and a fault compensator. The synchronization can be achieved no matter whether the fault occurs or not. To investigate the stability of the error system and facilitate the design of the fuzzy sampled-data controller, a Takagi Sugeno （T-S） fuzzy model is employed to represent the chaotic system dynamics. To acquire good performance and produce a less conservative analysis result, a new parameter-dependent Lyapunov-Krasovksii functional and a relaxed stabilization technique are considered. The stability conditions based on linear matrix inequality are obtained to achieve the fault tolerant synchronization of the chaotic systems. Finally, a numerical simulation is shown to verify the results.展开更多
The increasing volume of data in the area of environmental sciences needs analysis and interpretation. Among the challenges generated by this “data deluge”, the development of efficient strategies for the knowledge ...The increasing volume of data in the area of environmental sciences needs analysis and interpretation. Among the challenges generated by this “data deluge”, the development of efficient strategies for the knowledge discovery is an important issue. Here, statistical and tools from computational intelligence are applied to analyze large data sets from meteorology and climate sciences. Our approach allows a geographical mapping of the statistical property to be easily interpreted by meteorologists. Our data analysis comprises two main steps of knowledge extraction, applied successively in order to reduce the complexity from the original data set. The goal is to identify a much smaller subset of climatic variables that might still be able to describe or even predict the probability of occurrence of an extreme event. The first step applies a class comparison technique: p-value estimation. The second step consists of a decision tree (DT) configured from the data available and the p-value analysis. The DT is used as a predictive model, identifying the most statistically significant climate variables of the precipitation intensity. The methodology is employed to the study the climatic causes of an extreme precipitation events occurred in Alagoas and Pernambuco States (Brazil) at June/2010.展开更多
A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP sh...A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP ship system to a fuzzy system with time-varying delay. Adequate conditions are derived to determine the system's asymptotical stability and achieve H∞performance via Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analyzing the stabilization condition. Simulation result shows that the proposed method and the designed controller for a DP ship are effective so that the DP ship can maintain the desired position, heading and velocities in the existence of varying environment disturbances.展开更多
基金This research was supported by the China National Railway Group Co.,Ltd.Research and Development Project(N2022T008).
文摘Purpose–The study aims to provide a basis for the effective use of safety-related information data and a quantitative assessment way for the occurrence probability of the safety risk such as the fatigue fracture of the key components.Design/methodology/approach–The fatigue crack growth rate is of dispersion,which is often used to accurately describe with probability density.In view of the external dispersion caused by the load,a simple and applicable probability expression of fatigue crack growth rate is adopted based on the fatigue growth theory.Considering the isolation among the pairs of crack length a and crack formation time t(a∼t data)obtained from same kind of structural parts,a statistical analysis approach of t distribution is proposed,which divides the crack length in several segments.Furthermore,according to the compatibility criterion of crack growth,that is,there is statistical development correspondence among a∼t data,the probability model of crack growth rate is established.Findings–The results show that the crack growth rate in the stable growth stage can be approximately expressed by the crack growth control curve da/dt=5 Q•a,and the probability density of the crack growth parameter Q represents the external dispersion;t follows two-parameter Weibull distribution in certain a values.Originality/value–The probability density f(Q)can be estimated by using the probability model of crack growth rate,and a calculation example shows that the estimation method is effective and practical.
文摘This paper proposes an effective method for reducing test data volume undermultiple scan chain designs. The proposed method is based on reduction of distinct scan vectorsusing selective don't-care identification. Selective don't-care identification is repeatedlyexecuted under condition that each bit of frequent scan vectors is fixed to binary values (0 or 1).Besides, a code extension technique is adopted for improving compression efficiency with keepingdecompressor circuits simple in the manner that the code length for infrequent scan vectors isdesigned as double of that for frequent ones. The effectiveness of the proposed method is shownthrough experiments for ISCAS'89 and ITC'99 benchmark circuits.
文摘Based on TBB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the transition begins as early as in April, followed by abrupt change in May-June; the Asian summer monsoon situation is fully established in June. The winter convective center in Sumatra moved steadily northwestward across the "land bridge" of the maritime continent and the Indo-China Peninsula as time goes from winter to summer, thus giving rise to the change in large scale circulations that is responsible for the summer monsoon establishment over SE Asia and India; the South China Sea to the western Pacific summer monsoon onset bears a close relation to the active convection in the Indo China Peninsula and steady eastward retreat of the subtropical TBB high-value band,corresponding to the western Pacific subtropical high.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50977008,60774048,and 60774093)the National High Technology Research and Development Program of China (Grant No. 2009AA04Z127)+1 种基金the Special Grant of Financial Support from China Postdoctoral Science Foundation (Grant No. 200902547)Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200801451096)
文摘In this paper the fault tolerant synchronization of two chaotic systems based on fuzzy model and sample data is investigated. The problem of fault tolerant synchronization is formulated to study the global asymptotical stability of the error system with the fuzzy sampled-data controller which contains a state feedback controller and a fault compensator. The synchronization can be achieved no matter whether the fault occurs or not. To investigate the stability of the error system and facilitate the design of the fuzzy sampled-data controller, a Takagi Sugeno （T-S） fuzzy model is employed to represent the chaotic system dynamics. To acquire good performance and produce a less conservative analysis result, a new parameter-dependent Lyapunov-Krasovksii functional and a relaxed stabilization technique are considered. The stability conditions based on linear matrix inequality are obtained to achieve the fault tolerant synchronization of the chaotic systems. Finally, a numerical simulation is shown to verify the results.
文摘The increasing volume of data in the area of environmental sciences needs analysis and interpretation. Among the challenges generated by this “data deluge”, the development of efficient strategies for the knowledge discovery is an important issue. Here, statistical and tools from computational intelligence are applied to analyze large data sets from meteorology and climate sciences. Our approach allows a geographical mapping of the statistical property to be easily interpreted by meteorologists. Our data analysis comprises two main steps of knowledge extraction, applied successively in order to reduce the complexity from the original data set. The goal is to identify a much smaller subset of climatic variables that might still be able to describe or even predict the probability of occurrence of an extreme event. The first step applies a class comparison technique: p-value estimation. The second step consists of a decision tree (DT) configured from the data available and the p-value analysis. The DT is used as a predictive model, identifying the most statistically significant climate variables of the precipitation intensity. The methodology is employed to the study the climatic causes of an extreme precipitation events occurred in Alagoas and Pernambuco States (Brazil) at June/2010.
基金the National Natural Science Foundation of China(No.51579114)the Project of New Century Excellent Talents of Colleges and Universities of Fujian Province(No.JA12181)the Project of Young and Middle-Aged Teacher Education of Fujian Province(No.JAT170309)
文摘A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP ship system to a fuzzy system with time-varying delay. Adequate conditions are derived to determine the system's asymptotical stability and achieve H∞performance via Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analyzing the stabilization condition. Simulation result shows that the proposed method and the designed controller for a DP ship are effective so that the DP ship can maintain the desired position, heading and velocities in the existence of varying environment disturbances.
