变量聚类—全局主成分分析在我国普通高等教育发展水平评价中的应用

本文根据1997年~2003年共同构成的关于我国普通高等教育发展水平的时序立体数据表,对各地区高等教育发展整体状况的各项指标进行变量聚类,以区分对我国高教发展背景与现状分别产生影响的各项指标,然后对每一类作主成分分析,选出能够代表该类的主成分。在此基础上,计算出各地区各年度主成分的增长度;再对各年度主成分的增长度作主成分分析,以期对我国高教发展背景与现状的总体变化趋势做出综合评价。     

Rough集中不一致决策表的一种处理方法

Rough集理论在对不一致决策表的处理上一直是较为困难的问题。给出一种处理不一定决策表的方法，可将原决策表加工成为人们决策时满意的决策表。     

Dynamic modelling of life table data

In this paper we formulate a dynamic model expressing the human life table data by using the first-passage-time theory for a stochastic process. The model is derived analytically and then is applied to the mortality data in Belgium and France. A stochastic simulation is also performed for the ‘health state function’ proposed and the related stochastic paths. Furthermore the implications of the proposed model and the results derived for pension funds and option theory are discussed.     

关于激光等离子体声波的数学模型

根据激光等离子体冲击波的传播规律,利用数学方法和物理知识解释了激光等离子体冲击波转化为激光等离子体声波的原理.     

Substitution symmetry

Pólya's enumeration theory and its generalizations are refined to count derivatives of symmetrical parent compounds with any specified subsymmetry. Equivalently, enumeration of orbits of mappings, upon which a group acts by acting on their domain and their range, is refined to count orbits with stabilizers in any specified conjugacy class of subgroups.     

气态环己烷催化氧化制丁二酸酐的研究- TiO2-Al2O3纳米复合载体对目标反应的影响

采用溶胶-凝胶法,在γ-A l2O3载体上负载纳米TiO2,制得一系列纳米复合载体.用正交实验法对催化剂载体进行优化筛选,借助DTA-TG、IR、TEM等表征手段研究了催化剂载体的晶型结构转变,表面形貌及纳米复合载体粒径.结果表明:在实验条件下,复合载体的晶型结构、粒径大小、TiO2的负载量、乙醇与钛酸丁酯的物质的量之比、焙烧温度等对催化性能均有不同程度的影响.     

Negative binomial version of the Lee–Carter model for mortality forecasting

Mortality improvements pose a challenge for the planning of public retirement systems as well as for the private life annuities business. For public policy, as well as for the management of financial institutions, it is important to forecast future mortality rates. Standard models for mortality forecasting assume that the force of mortality at age x in calendar year t is of the form exp(α_x + β_xκ_t). The log of the time series of age-specific death rates is thus expressed as the sum of an age-specific component α_x that is independent of time and another component that is the product of a time-varying parameter κ_t reflecting the general level of mortality, and an age-specific component β_x that represents how rapidly or slowly mortality at each age varies when the general level of mortality changes. The parameters are usually estimated via singular value decomposition or via maximum likelihood in a binomial or Poisson regression model. This paper demonstrates that it is possible to take into account the overdispersion present in the mortality data by estimating the parameter in a negative binomial regression model. Copyright © 2007 John Wiley & Sons, Ltd.