N阶幻体及其初等性质

幻方和幻立方是组合数学中古老问题,它们体现了数字间关系的优美性与和谐性.本文基于幻方和幻立方的理论引入了幻体,给出了其存在性定理的证明,并进一步讨论了幻体的初等性质.     

煤炭燃前脱硫技术评价体系

煤炭脱硫为洁净煤技术的优先发展技术.通过对影响燃前脱硫技术的诸因素分析和项目技术经济比较,构筑了煤炭燃前脱硫技术评价体系.评价体系中采用模糊数学等有关理论提出了模糊综合评价法.评价示例表明在采用多种燃前技术脱硫时,综合评价指数最高的方法为重介旋流器脱硫法.     

对当前建设单位在招投标阶段进行造价控制的思考

指出了当前建设单位在招投标阶段的管理现状及存在的问题,并通过分析这些问题,提出了相应的解决对策。     

对英语专业八级口语口译考试评分的探讨

本文通过对英语专业八级口语口译考试的评分标准的考察，指出八级口语口译考试评分中两个突出的特点，即突出口语考试和口译考试评分“信息单元化”，从而影响口译质量评估的有效性。适当改变评分比例和口译评分标准的改进将有助于改善测评效果。     

判别线性不等式组相容性的ALN法

本文将ＡＢＳ算法应用到线性不等式组上．给出了一种判别ＡＸ＜０的相容性的方法．     

真分数表成单位分数和的一类特解

用初等的方法研究了m/n表法，并给出了真分数表成单位分数和的一类特解。     

Unit roots versus other types of time heterogeneity,parameter time dependence and superexogeneity

This paper stresses the restrictive nature of the standard unit root/cointegration assumptions and examines a more general type of time heterogeneity, which might characterize a number of economic variables, and which results in parameter time dependence and misleading statistical inference. We show that in such cases ‘operational’ models cannot be obtained, and the estimation of time‐varying parameter models becomes necessary. For instance, economic processes subject to endemic change can only be adequately modelled in a state space form. This is a very important point, because unstable models will break down when used for forecasting purposes. We also discuss a new test for the null of cointegration developed by Quintos and Phillips (1993), which is based on parameter constancy in cointegrating regressions. Finally, we point out that, if it is possible to condition on a subset of superexogenous variables, parameter instability can be handled by estimating a restricted system. Copyright © 2002 John Wiley & Sons, Ltd.     

The Experimental and Theoretical Research of “Local Resonance“ in Ultrasonic Honing System

In 1982, Professor Fang Guoliang found the “Non full resonance“ phenomenon in a tool system while he use the thin-long tool ultrasonically machining deep-small hole. He called it as “local resonance“. Also this “Non full resonance“ phenomenon was discovered in the ultrasonic drilling and the ultrasonic honing system later. To its mechanism, professor Fang thought that the coupling of long-thin tool bar and driving system is weak, so the tool bar can vibrate independently, but the quantitative relation betwe...     

多个矩阵之和与积的特征值关系问题

给出了3个以上矩阵之和与积的特征值之间的若干等价关系.     

奇异矩阵的Krylov方法的误差分析比较

Krylov方法是求解线性方程组Ax=b,A∈CN×N,b∈CN的一种迭代方法,当A非奇异时,已有很好研究.而当A奇异或接近奇异阵时,在一定的假定条件下,Krylov方法的解与范教最小的最小二乘解A+b之间的差是可以估计出来的.