双水平井SAGD 循环预热连通判断新解析

注蒸汽循环预热对转SAGD 生产阶段蒸汽腔的上升速度、SAGD 上产速度、水平段蒸汽腔的发育程度与动用 率、以及SAGD 最终采收率等均有重要影响。而SAGD 注采井水平段之间的储层温度是评判预热连通是否达到要求、 以及合理转SAGD 生产的关键参数。针对前人传热解析模型未分别考虑实际储层多孔介质中岩石、原油、地层水传热 与热扩散性能等问题,建立了考虑油水岩石的多介质多相流体综合传热解析新模型,并以国内某油区典型SAGD 井 组为例,利用井下测温数据、油水岩石热物性参数等为数据,进行了SAGD 注蒸汽循环预热阶段注采井水平段之间温 度变化测算,并与数值模拟计算结果进行了对比,计算结果表明,提出的新型解析模型与数值模拟结果符合率达到了 95% 以上,可方便快捷对预热连通情况进行速判,对现场SAGD 成功实施具有重要意义。     

Bayesian meta-analysis using skewed elliptical distributions

Meta-analysis refers to a quantitative method for combining results from independent studies in order to draw overall conclusions. We consider hierarchical models including selection models under a skewed heavy tailed error distribution proposed originally by Chen, Dey, and Shao [M. H. Chen, D. K. Dey, Q. M. Shao, A new skewed link model for dichotomous quantal response data, J. Amer. Statist. Assoc. 94 (1983), pp. 1172–1186.] and Branco and Dey [D. Branco and D.K. Dey, A general class of multivariate skew-elliptical distributions, J. Multivariate Anal. 79, pp. 99–113.]. These rich classes of models combine the information of independent studies, allowing investigation of variability both between and within studies and incorporating weight functions. We constructed a detailed computational scheme under skewed normal and skewed Student's t distribution using the MCMC method. Bayesian model selection was conducted by Bayes factor under a different skewed error. Finally, we illustrated our methodology using a real data example taken from Johnson [M.F. Johnson, Comparative efficacy of Naf and SMFP dentifrices in caries prevention: a meta-analysis overview, J Eur. Organ. Caries Res. 27 (1993), pp. 328–336.].     

A multiple stream generator based on de Bruijn digraph homomorphisms

We propose a method to obtain several streams of pseudorandom numbers based on a backbone generator of the generalized shift register type. The method is based on inverting one cycle in a de Bruijn digraph into many sequences in a higher-order de Bruijn graph via an appropriate graph homomorphism. We apply this technique to twisted generalized feedback shift register generators and to the Mersenne Twister MT19937. Positive results of statistical testing are reported.     

Generating random numbers of prescribed distribution using physical sources

When constructing uniform random numbers in [0, 1] from the output of a physical device, usually n independent and unbiased bits B _j are extracted and combined into the machine number . In order to reduce the number of data used to build one real number, we observe that for independent and exponentially distributed random variables X _n (which arise for example as waiting times between two consecutive impulses of a Geiger counter) the variable U _n : = X _{2n – 1}/(X _{2n – 1} + X _2n ) is uniform in [0, 1]. In the practical application X _n can only be measured up to a given precision (in terms of the expectation of the X _n ); it is shown that the distribution function obtained by calculating U _n from these measurements differs from the uniform by less than /2.We compare this deviation with the error resulting from the use of biased bits B _j with P {B _j = 1{ = (where ] – [) in the construction of Y above. The influence of a bias is given by the estimate that in the p-total variation norm Q ^TV _p = ( |Q()| ^p )^1/p (p 1) we have P _Y – P ⁰ _Y ^TV _p (c _n · )^1/p with c _n p for n . For the distribution function F _Y – F ⁰ _Y 2(1 – 2^–n )|| holds.     

数字彩色电視同步机时序邏輯設計

电视同步信号发生器(简称同步机)是稳定、准确传输图像的关键.本文讨论数字集成化彩色同步机的总体方案设计和用“时钟分频-逻辑归纳法”设计同步机各脉冲定时和形成部分的方法.根据设计电路制作了样机,具有定时准确性高,性能稳定的特点.     

语言学中的优选论

介绍优选论的理论框架,运用优选论层级排列的限制条件解释语言现象的方法,回顾优选论在句法、音系等领域中所取得的成就,并简要介绍优选论在语义学、语用学研究领域中的研究成果及最新发展。优选论在汉语语言学研究方面也有一定的应用和发展,并有很好的发展前景。     

燃气轮机故障诊断专家系统的设计与实现

建立了一个适用于燃气轮机的故障诊断专家系统。介绍了该系统的结构、功能、自学能力和知识库的建立及推理机的实现。知识库采用产生式表示法,其组织结构分为三级：大范围经验知识、小范围经验知识和参考解决方案。系统采用双推理机机制,逆向精确推理用于教学和演示,能够查看和解释系统的推理过程;逆向不精确推理用于实际工作场合,提供具有较高可信度的推理结果。     

汽轮机事故工况的压差分析

应用振荡流体力学理论,对某事故工况下中低压缸内的振荡流场进行了理论计算,通过对计算结果的分析,证实了事故专家组关于隔板是在巨大的压差作用下损坏的结论。     

Americans are more exposed to difference than we think: Capturing hidden exposure to political and racial difference

Use of name generators (NG) in assessing exposure to political difference has led to the conclusion that disagreement is uncommon. Data from two representative surveys tested a NG modification to probe for exposure to difference. Over half for whom NG results suggest no exposure to difference were able to name an alter who supported an alternative candidate. Over a quarter whose NG results indicate no exposure to a racial difference were able to name someone of the opposite race with whom they’d talked politics. These findings demonstrate that mixed or diverse networks are more common than prior NG research suggests.