Research on Chaotic Time Series Prediction Based on K-entropy and RBF Neural Networks

In this paper, a method of direct multi-step prediction of chaotic time series is proposed, which is based on Kolmogorov entropy and radial basis functions neural networks. This is done first by reconstructing a phase space using chaotic time series, then using K-entropy as a quantitative parameter to obtain the maximum predictability time of chaotic time series, finally the predicted chaotic time series data can be acquired by using RBFNN. The application considered is Lorenz system. Simulation results for direct multi-step prediction method are compared with recurrence multi-step prediction method. The results indicate that the direct multi-step prediction is more accurate and rapid than the recurrence multi-step prediction within the maximum predictability time of chaotic time series. So, it is convenient to forecast and control with real time using the method of direct multi-step prediction.     

shall和will,should和would 的分类及其它——读书札记

一、关于 shall 和 will,should 和 would 的分类问题shall 和 will,should 和 would 除了象传统做法那样分为助动词和情态助动词外,也有把它们划为助动词一类的。比如:旅美教授钱歌川在他的《英文疑难详解》(1976年)一书中,在答疑 shall 和will 的用法时,就是在助动词一类下来解释它们的情态意义和时间功能这两个不同用法的。又如:浙江大学外语教研室1977年在原有教学用书的基础上修改编写的《实用科技英语语法》(1979年)的动词分类中,也是在助动词(the Auxiliary Verb)这一分类下从功能上概述 shall 和 will 帮助构成各种将来时态和分别表达说话人的意志及     

对《定冠词“the”的基本用法》一文的看法

学报1979年第一期发表了米景沅同志的《定冠词“the”的基本用法》一文。该论文叙述的语法基本规则及例句,多半取材于当前在我国外语教育界最流行的一些语法著作及有关辞书和材料。该文行文较长,谈得较细,并且列举了不少搜集来的例句进行说明解释,费了一定的功夫,是值得称许的。但读后觉得存在一些问题,特提出来和作者研讨。(1) 论文(54页)有这样一个句子:“He made a comparison between the English and German language.”我们查问了张道真的《实用英语语法》,该书39页上写着:He made a comparison between the English and the German languages.论文作者把German之前的定冠词“the”去掉,似乎欠妥;张道真在同一页上说:“当并列两个名词前都应有定冠词时,一般不能省略。”language一词如用单数,那么并列的English和German前一般应有各自的定冠词,因为在这种情况     

Effects of H content on the tensile properties and fracture behavior of SA508-III steel

SA508-Ⅲ steel was charged with different hydrogen (H) contents using a high-pressure thermal charging method to study the effects of H content on the tensile properties and evaluate the H embrittlement behavior of the steel. The results indicate that the ultimate tensile strength remains nearly unchanged with the addition of H. In contrast, the yielding strength slightly increases, and the elongation significantly decreases with increasing H content, especially at concentrations exceeding 5.6×10-6. On the basis of fractographic analysis, it is clear that the addition of H changes the fracture mode from microvoid coalescence to a mixture of river patterns and dimples. Carbides are strong traps for H; thus, the H atoms easily migrate in the form of Cottrell atmosphere toward the carbides following moving dislocations during tensile deformation. In addition, stress-induced H atoms accumulate at the interface between carbides and the matrix after necking under three-dimensional stress, which weakens the interfacial bonding force. Consequently, when the local H concentration reaches a critical value, microcracks occur at the interface, resulting in fracture.     

S同位素示踪热液矿床成矿物质来源综述

具有明显分馏效应的硫同位素以各种含硫物种广泛赋存于热液成矿作用过程中,因此硫同位素成为示踪热液矿床成矿物质来源的主要方法之一。本文在总结前人研究基础上,综述了应用硫同位素在研究热液矿床成矿物质来源问题上的多解性,认为硫同位素示踪应用须在了解热液矿床地质前提下,准确区分成矿期次,判别硫同位素分馏平衡状态,结合Ohmoto模式才可以准确赋予同位素的地质意义。     

STUDY OF KINETIC ANALYTICAL METHOD BASED ON CATALYTIC REACTIONS

In this thesis a reviwe is presented for the advances of catalytic spec trophotometric method, three new catalytic reaction systems were presented, and its rela live catalytic spectrophotometric methods have been established by flow injection tech nique. Particulary the relative chemometric methods and theories were used in the field of kinetic - catalytic analysis, in order to solve the problems of multicomponents analysis.     

受阻胺光稳定剂的热失重分析

使用热失重分析仪对ＴＭＰ,ＰＭＰ,ＴＭＰＭ,ＧＷ５４０,Ｔｉｎｕｖｉｎ７７０等小分子型受阻胺光稳定剂、ＴＭＰＭ的均聚物ＰＴＭＰＭ和ＰＭＰＭ的均聚物ＰＰＭＰＭ、一系列具有不同单体配比的ＰＤＳ,ＴＭＰＭ和ＰＭＰＭ分别与ＭＭＡ,Ｓｔ,ＭＡＡ,ＡＡ共聚得到的共聚物等受阻胺类光稳定剂进行了热失重分析（ＴＧ）。实验发现小分子型的受阻胺光稳定剂的热稳定性均较差,它们的热稳定顺序是ＴＭＰ〈ＰＭＰ〈ＴＭＰＭ〈ＧＷ５     

Fuzzy optimization of space frame

Fuzzy concepts are introduced into structural optimization to solve fuzzy optimization problems with a crisp objective function and fuzzy constraints, also a non-membership function is used to convert fuzzy constrains into crisp constrains. Two models are discussed where the objective function considered is the volume of space frame and the fuzzy constrains are design limits by the axial strength, slenderness, deflection, thickness and diameter of space frame member.     

Fracture toughness and fracture behavior of SA508-III steel at different temperatures

The fracture toughness of SA508-III steel was studied in the temperature range from room temperature to 320°C using the J-integral method. The fracture behavior of the steel was also investigated. It was found that the conditional fracture toughness (J_Q) of the steel first decreased and then increased with increasing test temperature. The maximum and minimum values of J_Q were 517.4 kJ/m2 at 25°C and 304.5 kJ/m2 at 180°C, respectively. Dynamic strain aging (DSA) was also observed to occur when the temperature exceeded 260°C with a certain strain rate. Both the dislocation density and the number of small dislocation cells effectively increased because of the occurrence of DSA; as a consequence, crack propagation was more strongly inhibited in the steel. Simultaneously, an increasing number of fine carbides precipitated under high stress at temperatures greater than 260°C. Thus, the deformation resistance of the steel was improved and the J_Q was enhanced.