水库突发事件应急预案研究现状与关键技术初探

水库突发事件应急预案是大坝风险管理中非常重要的一个环节,是降低水库大坝风险的非工程措施.本文总结了国内水库突发事件应急预案的研究现状,并结合我国实际国情,初步提出了开展应急预案的关键技术,供大坝安全管理及科研人员参考.     

新型香料苹果酯-B的合成

以硫酸高铈为催化剂,通过乙酰乙酸乙酯和1,2-丙二醇反应合成了苹果酯-B,研究了各有关因素对产品收率的影响。实验表明,硫酸高铈是合成苹果酯-B的良好催化剂,在酯醇物质的量比为1∶1.25、催化剂用量为0.3g/0.1mol乙酰乙酸乙酯、环己烷10mL、反应时间2h的条件下,苹果酯-B的收率可达91.5%。     

Fixed point theorem-based iterative learning control for LTV systems with input singularity

In this paper, we address a challenging and open problem: how to design a suitable iterative learning control (ILC) system in the presence of input singularity, which is incurred by the singularities of the system direct feed-through term. Considering two typical types of input singularities, we first revise the ILC operators accordingly by adding a forgetting factor and incorporating a time-varying learning gain, in the sequel guarantee ILC operators to be contractible. Next, using the Banach fixed-point theorem, we demonstrate that the output sequence can either enter and remains ultimately in a designated neighborhood of the target trajectory, or is bounded by a class K function. Finally, an illustrative example is presented.     

溶剂萃取分离锂同位素研究Ⅱ.苏丹Ⅰ-中性配位体协萃体系萃取分离锂同位素效应探讨

文章讨论了苏丹I-中性配位体协萃体系萃取分离锂同位素中螯合剂和协萃剂的结构效应。为了获得高的同位素分离效应,螯合剂必须是弱酸性的(PK_α>11),具有强的分子内氢键及易于形成六元螯合环。协萃剂结构不仅要求无空间位阻,而且具有强的配位基。α随配位基的碱性增大而相应提高。萃取络合物中螯合环的增多亦有利于体系α的提高。此外本文还讨论了一些萃取体系的同位素富集方向和萃锂体系用于分离同位素的前景。     

Analysis of the pullout of single fibers from low-density polyethylene

In the present work, a single-fiber pullout test was used to study the interface/interphase between various fibers and low-density polyethylene (LDPE) and between glass fibers and a range of other thermoplastic matrices. For well-bonded fibers, experimental evidence suggests the involvement of plastic deformation and strain-hardening prior to debonding and pullout. The interfacial shear strength was determined to be the ultimate shear strength of the matrix and was found to be insensitive to the fiber surface structure. A new theoretical model was developed to predict the relationship between the debonding force and the embedded length. The contribution of friction to the debonding force was found to be insignificant when compared with the contribution of plastic deformation. © 1994 John Wiley & Sons, Inc.     

关于内流式锥阀稳态液动力方向的探讨——与有关液压传动教科书作者们商榷

多本液压传动教科书认为内流式锥阀的稳态液动力是使阀芯打开方向。作者用伯努利方程压力能与动能转换的原理和动量定理进行分析，认为内流式锥阀的稳态液动力与外流式锥阀以及滑阀一样，也是使阀芯关闭方向。     

强流质子直线加速器中束晕现象研究

从束流包络方程与单粒子运动方程联立模型出发，考虑了纵向能量方程的耦合，研究了强流质子直线加速器中的束晕现象。采用相交间的Ｐｏｉｎｃａｒｅ截面方法和实空间Ｐｏｉｎｃａｒｅ截面方法，研究了周期聚焦系统失配的情况下束晕的形成以及加速对束晕形成的影响。     

基于Matlab的线性规划问题求解

线性规划是运筹学中研究较早、发展较快、应用广泛、方法成熟的一个重要分支,它是辅助人们进行科学管理的一种重要的数学方法.文章首先介绍了线性规划的基本概念及标准形式,着重讨论了线性规划问题的三种常用解法:单纯形法、直接搜索法以及遗传算法,最后在Matlab R2009a环境下进行了仿真.通过结果可以看出,用Matlab求解线性规划问题,可以避免手工的烦琐计算,大大地提高工作效率和结果的准确性.