化学教学的“设疑—研讨”模式

提出了“设疑—研讨”教学模式 ,并运用于中学化学教学中 ,通过设疑、讨论、总结和评价四步教学法 ,培养了学生思维能力和创新能力     

一个汉英机器翻译系统中的语义处理模型

简略阐述了三种语义分析理论 -配价语法 ,格语法 ,论旨理论后 ,重点介绍了机器翻译系统所采用的语义模型     

增长曲线模型非齐次线性估计的可容许性

讨论增长曲线模型Y =X1BX2 +ε中回归矩阵B的函数C1BC2 的估计L1YL2 +A ,在矩阵损失 (LT2 L1)Y +A - (ST2 XT2 S1X1)B (LT2 L1)Y +A - (ST2 XT2 S1X1)B T 下 ,我们得到了非齐次线性估计L1YL2 +A在非齐次线性估计类Г ={L1YL2 +A|L1:t×p ,L2 ;n×n ,A :t×s均为已知实阵 }中可容许的充要条件 :L1YL2在Г0 ={L1YL2 |L1:t×p ,L2 :n×s均为已知实阵 }中容许且当LT2 XT2 L1X1=ST2 XT2 S1X1时有A =0。     

构建电子政务系统的研究

文章介绍了电子政务的内涵及其基本内容 ,分析了实施电子政务的意义 ,指出了实施电子政务的基本原则 ,提出了构建电子政务系统的网络模型和层次模型。     

Empirical likelihood confidence intervals for the mean of a population containing many zero values

If a population contains many zero values and the sample size is not very large, the traditional normal approximation‐based confidence intervals for the population mean may have poor coverage probabilities. This problem is substantially reduced by constructing parametric likelihood ratio intervals when an appropriate mixture model can be found. In the context of survey sampling, however, there is a general preference for making minimal assumptions about the population under study. The authors have therefore investigated the coverage properties of nonparametric empirical likelihood confidence intervals for the population mean. They show that under a variety of hypothetical populations, these intervals often outperformed parametric likelihood intervals by having more balanced coverage rates and larger lower bounds. The authors illustrate their methodology using data from the Canadian Labour Force Survey for the year 2000.     

期权定价理论在技术商品定价中的应用探讨

技术商品不同于一般商品 ,具有报酬无限、风险有限的特性 ,尤其与支付红利的美式看涨期权特点极为相似。应用传统的资产评估方法为技术商品定价 ,其结果很难真实反映技术商品的价值。期权定价理论为技术商品的科学定价提供了一种新思路 ,特别是支付红利的美式看涨期权定价模型对解决技术商品价值评估有参考价值     

Bayesian analysis of mixture modelling using the multivariate t distribution

A finite mixture model using the multivariate t distribution has been shown as a robust extension of normal mixtures. In this paper, we present a Bayesian approach for inference about parameters of t-mixture models. The specifications of prior distributions are weakly informative to avoid causing nonintegrable posterior distributions. We present two efficient EM-type algorithms for computing the joint posterior mode with the observed data and an incomplete future vector as the sample. Markov chain Monte Carlo sampling schemes are also developed to obtain the target posterior distribution of parameters. The advantages of Bayesian approach over the maximum likelihood method are demonstrated via a set of real data.     

群体决策支持系统的模型库研究

通过对传统模型及模型库的分析,指出其在网络环境下具有难以实现共享的不足.从模型在网络上共享及其软件实现的角度,在分布式网络数据库环境下,利用分布式网络数据库技术,设计了模型库的结构和机理;提出了模型库的构造方法;对模型库的内部控制方式进行了设计;提出了模型库对群体决策的支持方式;客户端的决策成员对模型库的共享与访问方法.     

A Bayesian Adjustment for Covariate Misclassification with Correlated Binary Outcome Data

Estimated associations between an outcome variable and misclassified covariates tend to be biased when the methods of estimation that ignore the classification error are applied. Available methods to account for misclassification often require the use of a validation sample (i.e. a gold standard). In practice, however, such a gold standard may be unavailable or impractical. We propose a Bayesian approach to adjust for misclassification in a binary covariate in the random effect logistic model when a gold standard is not available. This Markov Chain Monte Carlo (MCMC) approach uses two imperfect measures of a dichotomous exposure under the assumptions of conditional independence and non-differential misclassification. A simulated numerical example and a real clinical example are given to illustrate the proposed approach. Our results suggest that the estimated log odds of inpatient care and the corresponding standard deviation are much larger in our proposed method compared with the models ignoring misclassification. Ignoring misclassification produces downwardly biased estimates and underestimate uncertainty.     

张掖市虚拟水投入产出分析

 虚拟水战略是水资源社会化管理的一个重要途径。本文应用地区水资源投入产出模型，剔出外地调入品影响，通过本地完全需水系数，以及完全需水量与直接用水量比较，计算了张掖市产业间虚拟水的净转移以及区域虚拟水的调入调出，进一步构造了产业间虚拟水转移矩阵，清晰量化各产业间虚拟水的转移去向。结果表明，种植业及其他农业是虚拟水最大的净转移和输出部门，利用的水实际向制造业和畜牧业大量转移, 畜牧业又将种植业转移来的水大部分输出外地。通过量化经济部门之间对水资源需求的数量关联效应，从投入产出分析视角为张掖市水需求管理提供新的参考。