高Si/C高强度铸铁中C、Si、Si/C的作用及其选择

本文叙述了高Si/C高强度灰铸铁中碳、硅元素存在的形式及其对结晶过程的影响。试验表明,当碳当量一定时,随着Si/C的升高,初生奥氏体枝晶数量增多并且细化和强化,从而构成了强度的基础。该铸铁的强度模式应为“初生奥氏+共晶团”。本文对E型石墨存在的必然性和合理性也进行了讨论。     

Any complete preference structure without circuit admits an interval representation

This article proves that all complete preference structures where the strict preference relation (P) has no circuit admit a representation by intervals of the real line; the rule for deciding whether an interval is indifferent or preferred to another is less straightforward than for interval orders: strict preference is indeed compatible with a certain degree of overlapping of intervals, the allowed degree being specified by means of a so-called tolerance function.     

De minimis and equity in risk

Indices and orderings are developed for evaluating alternative strategies in the management of risk. They reflect the goals of reducing individual and collective risks, of increasing equity, and of assigning priority to the reduction and to the equity of high risks. Individual risk is defined as the (random or non-random) level of exposure to a danger. In particular the role of a lower negligibility level is investigated. A class of indices is proposed which involves two parameters, a negligibility level and a parameter of inequality aversion, and several interpretations of the indices are discussed. We provide a set of eight axioms which are necessary and sufficient for this class of indices, and we present an approach to deal with partial information on the parameters.     

A fast splitting procedure for classification trees

This paper provides a faster method to find the best split at each node when using the CART methodology. The predictability index is proposed as a splitting rule for growing the same classification tree as CART does when using the Gini index of heterogeneity as an impurity measure. A theorem is introduced to show a new property of the index : the for a given predictor has a value not lower than the for any split generated by the predictor. This property is used to make a substantial saving in the time required to generate a classification tree. Three simulation studies are presented in order to show the computational gain in terms of both the number of splits analysed at each node and the CPU time. The proposed splitting algorithm can prove computational efficiency in real data sets as shown in an example.     

Early experiences of mentoring: Design and use of multimedia materials for teaching OR/MS

The MENTOR project, based at the University of Strathclyde, is producing multimedia computer based learning materials with the aim of improving both the effectiveness and the efficiency of teaching Operational Research/Management Science in higher education. The process of development has been carefully designed to encourage ownership of and commitment to the materials amongst lecturing staff in Universities, with the aim of ensuring widespread use. The paper outlines this process of development and design of materials. Experiences in introducing students to the use of these materials as an integrated part of a Management Science class are reported. Feedback from students has been very positive but also indicates the need for ongoing support and direction.     

SO42-/TiO2催化合成乙酸乙酯的实验设计

SO4^2-／TiO2固体超强酸薄膜化催化剂能完全代替浓硫酸作催化剂,用乙酸、乙醇来合成乙酸乙酯。在膜催化器上,考察了薄膜化催化剂对乙醇和乙酸合成乙酸乙酯的催化性能。结果表明,薄膜化催化剂显著提高了催化活性;当n（乙醇）：n（乙酸）=1．5：1,原料流量3．0mL／h,在反应温度为110℃时,乙酸乙酯产率可达94．8％,且薄膜催化剂的处理很方便,催化剂再生后可重复使用,不污染环境。     

论海事英语中英文翻译

针对船员汉译英所遇到的关于翻译方法或翻译技巧的困惑,分析汉英双语特征,探讨翻译标准,并提出在文体和文法方面的翻译原则以及使译文“忠实、通顺”的翻译技巧。     

人民币实际汇率波动与中国对美出口

运用协整方法对人民币实际汇率波动与中国对美出口的关系进行实证研究。结果表明：中国对美出口收入效应极强,中国对美出口汇率波动效应较弱,中国对美出口的价格效应不存在。在美国经济可能陷入衰退的情况下,中国政府应暂缓人民币升值和人民币汇率形成机制改革的步伐。     

氧化石墨的合成及其结构研究

在Hummer法的基础上合成了氧化石墨、对氧化石墨的组成、分子结构及其还原性进行了测试与分析,结果表明,氧化石墨结构中含有大量的极性基因,这些基因的存在赋予了氧化石墨在极性溶剂中有良好的溶剂化能力。     

在电磁场中巧用数学之浅析

电磁场理论与数学紧密相关,在电磁场中巧用数学能使物理概念、规律和物理过程册繁就简,便于记忆和理解。抓住事物和物理过程的对称性,巧用数学解决电磁场中的类似问题,培养学生灵活运用数学处理问题的能力。