Aiming at the difficulty of accurately constructing the dynamic model of subtropical high, based on the potential height field time series over 500 hPa layer of T106 numerical forecast products, by using EOF（empirica...Aiming at the difficulty of accurately constructing the dynamic model of subtropical high, based on the potential height field time series over 500 hPa layer of T106 numerical forecast products, by using EOF（empirical orthogonal function） temporal-spatial separation technique, the disassembled EOF time coefficients series were regarded as dynamical model variables, and dynamic system retrieval idea as well as genetic algorithm were introduced to make dynamical model parameters optimization search, then, a reasonable non-linear dynamic model of EOF time-coefficients was established. By dynamic model integral and EOF temporal-spatial components assembly, a mid-/long-term forecast of subtropical high was carried out. The experimental results show that the forecast results of dynamic model are superior to that of general numerical model forecast results. A new modeling idea and forecast technique is presented for diagnosing and forecasting such complicated weathers as subtropical high.展开更多
Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter ...Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter frequency distributions. The focus of this study is on predicting accuracy of stem number in the larger diameter classes, which is much more important than that of the smaller trees, from the view of forest management, and must be adequately considered in the modelling and estimate. There exist 3 traditional ways of modelling the diameter frequency distribution: the negative exponential function model, limiting line function model, and Weibull distribution model. In this study, a new model, named as the logarithmic J-shape function, together with the others, was experimented and was found as a more suitable model for modelling works in the tropical forests.展开更多
本文基于Brown语料库的100万词的数据,考察科技英语的篇际词汇增长模型,以篇章为计量单位,描述科技英语文本中词汇量V(N)与累积文本容量N之间的函数关系。通过对幂函数和对数函数的比较分析,构建了新的词汇增长模型,并应用此模型推导出...本文基于Brown语料库的100万词的数据,考察科技英语的篇际词汇增长模型,以篇章为计量单位,描述科技英语文本中词汇量V(N)与累积文本容量N之间的函数关系。通过对幂函数和对数函数的比较分析,构建了新的词汇增长模型,并应用此模型推导出科技英语的理论词汇增长曲线及其95%双向置信区间。本研究属于计算语言学的基础理论研究,反映了语言的经济律,有深刻的理论价值;另外,本文对英语作为外语的教学(English as Foreign Language,简称EFL),特别是词汇教学和教材编写,也有一定的指导意义。展开更多
基金Project supported by the National Natural Science Foundation of China (No.40375019) the Tropical Marine and Meteorology Science Foundation (No.200609) the Jiangsu Key Laboratory of Meteorological Disaster Foundation (No.KLME0507)
文摘Aiming at the difficulty of accurately constructing the dynamic model of subtropical high, based on the potential height field time series over 500 hPa layer of T106 numerical forecast products, by using EOF（empirical orthogonal function） temporal-spatial separation technique, the disassembled EOF time coefficients series were regarded as dynamical model variables, and dynamic system retrieval idea as well as genetic algorithm were introduced to make dynamical model parameters optimization search, then, a reasonable non-linear dynamic model of EOF time-coefficients was established. By dynamic model integral and EOF temporal-spatial components assembly, a mid-/long-term forecast of subtropical high was carried out. The experimental results show that the forecast results of dynamic model are superior to that of general numerical model forecast results. A new modeling idea and forecast technique is presented for diagnosing and forecasting such complicated weathers as subtropical high.
文摘Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter frequency distributions. The focus of this study is on predicting accuracy of stem number in the larger diameter classes, which is much more important than that of the smaller trees, from the view of forest management, and must be adequately considered in the modelling and estimate. There exist 3 traditional ways of modelling the diameter frequency distribution: the negative exponential function model, limiting line function model, and Weibull distribution model. In this study, a new model, named as the logarithmic J-shape function, together with the others, was experimented and was found as a more suitable model for modelling works in the tropical forests.
文摘本文基于Brown语料库的100万词的数据,考察科技英语的篇际词汇增长模型,以篇章为计量单位,描述科技英语文本中词汇量V(N)与累积文本容量N之间的函数关系。通过对幂函数和对数函数的比较分析,构建了新的词汇增长模型,并应用此模型推导出科技英语的理论词汇增长曲线及其95%双向置信区间。本研究属于计算语言学的基础理论研究,反映了语言的经济律,有深刻的理论价值;另外,本文对英语作为外语的教学(English as Foreign Language,简称EFL),特别是词汇教学和教材编写,也有一定的指导意义。
