地震荷载作用下高速公路挖方高边坡稳定性研究

考虑到地震边坡破坏的机制，以京化高速公路挖方高边坡为研究背景，对地震荷载下的边坡稳定性进行了分析研究。详细分析了边坡的工程地质条件，结合实地采样试验，确定了边坡岩体的工程力学参数。利用有限元软件ABAQUS，建立了三维数值仿真模型，在试验区地震特征研究的基础上，采用拟静力法+强度折减的方法，分别模拟了地震力作用下边坡的位移变形及主应力分布规律，计算了边坡的安全系数，为边坡的加固提供了依据。     

Error-rate estimation in two-group discriminant analysis using the linear discriminant function

Fisher's linear discriminant function, adapted by Anderson for allocating new observations into one of two existing groups, is considered in this paper. Methods of estimating the misclassification error rates are reviewed and evaluated by Monte Carlo simulations. The investigation is carried out under both ideal (Multivariate Normal data) and non-ideal (Multivariate Binary data) conditions. The assessment is based on the usual mean square error (MSE) criterion and also on a new criterion of optimism. The results show that although there is a common cluster of good estimators for both ideal and non-ideal conditions, the single best estimators vary with respect to the different criteria     

Ridge regression from principal component point of view

Ridge regression is often discussed as an estimation procedure for producing estimators which are biased but with a smaller mean squared error than the usual least square estimators. In this paper we show that this procedure can also be used to reflect the nature of dependency among a set of highly collinear regressor variables. In particular, we prove that, when data are severely multicollinear, the ridge estimators can be made very close to the principal component estimators. Examples are given to illustrate the point.     

On the estimates of the parameters of the first order autoregressive process

Two methods of estimation for the parameters of an AR(1) process which are based on a non-linear least-squares approach are presented. On the basis of some simulation results they are compared with two maximum likelihood estimates and their relative merits are discussed.     

PROGRESSIVE INTERVAL CENSORING: SOME MATHEMATICAL RESULTS WITH APPLICATIONS TO INFERENCE

In this paper, we will introduce a union of two methods of collecting Type-I censored data, namely interval censoring and progressive censoring. We will call the resulting sample a progressively Type-I interval censored sample.We will discuss likelihood point and interval estimation, and simulation of such a censored sample from a random sample of units put on test whose lifetime distribution is continuous. An illustrative example will also be presented.

     

Solving For the parameters of a beta a distribution under two quantile constraints

It will be shown that a solution exists for the parameters of a beta distribution given any combination of a lower quantile and upper quantile constraint. A numerical procedure is developed to solve for the parameters of the beta distribution given these quantile constraints. Example solutions are provided.     

Estimation and test of several multivariate normal means under an order restriction when the dimension is larger than two

Suppose that an order restriction is imposed among several p-variate normal mean vectors. We are interested in the problems of estimating these mean vectors and testing their homogeneity under this restriction. These problems are multivariate extensions of Bartholomew's (1959) ones. For the bivariate case, these problems have been studied by Sasabuchi et al. (1983) and (1998) and some others. In the present paper we examine the convergence of an iterative algorithm for computing the maximum likelihood estimator when p is larger than two. We also study some test procedures for testing homogeneity when p is larger than two.     

黄龙场构造长兴组裂缝预测

四川盆地黄龙场构造长兴组主要为生物礁储层， 裂缝是影响单井产量的主要因素。通过分析研究区构造成因及动力来源， 总结了研究区构造形成模式。结合石油地质学、 构造地质学、 岩石力学和各种生产资料， 利用古构造应力场二维数值模拟， 对研究区岩体的破裂程度进行预测， 然后计算出研究区岩体的破裂接近程度， 确定岩体破裂程度与裂缝发育的关系， 确定裂缝发育级别， 对裂缝发育程度、 裂缝类型和产状进行综合预测。得到了黄龙场地区早晚期主应力的矢量方向， 并把裂缝发育分为 2 期、 4 级和 6 类。     

地铁火灾数值模拟研究综述

由于运行、安全等因素的限制，以及技术手段的局限，地铁隧道与车站的火灾预测更多地借助数值模拟结果而制定．本文从火灾模拟新近发展、建模、边界条件、火灾荷载及应用软件等关键点综述最新火灾模拟技术的发展，汲取有益经验，为地铁火灾有效防控提供更为准确的技术手段．