环境地质学的现状及发展方向展望

环境地质学是一门应用地质学科,是地质科学和环境科学两者相互渗透、重新交叉组合而形成的一门新的边缘学科。它以人-地质环境系统为对象,研究地质环境和人类工程经济活动的相互作用及其发展、演化趋势,重点是地质灾害和环境地质问题的产生和发展,在此基础上提出合理协调人-地质环境关系,有效地预防地质灾害和环境地质问题的对策和措施。     

我国城市地质研究的历史演化与发展前景的认识

城市地质以调查研究和解决与城市建设及发展有关的各种资源、环境等地质问题为其基本任务。它随时代发展和国家需要侧重点有所不同。 2 1世纪是人类共同追求可持续发展的世纪 ,保护和合理利用资源环境已成为我国的一个重大战略问题。     

徐州市城市生态系统与环境的相互作用

本文研究了徐州市城市生态系统与自然环境之间的相互作用。自然环境限制了城市生态系统的功能类型、布局及运营方式,城市生态系统则以取出、输入和综合作用三种方式改造环境,并诱发了一些城市病害,导致城市生态系统暂时局部的运营紊乱。     

山西清徐县地裂缝灾害现状及类型分析

研究了山西省清徐县平泉村—武家坡村地裂缝地质灾害的现状和主要特征。清徐县平泉村至武家坡村等7个村庄自2002年春天出现地裂缝以来,其灾害呈现日趋加重的趋势,给当地村民的生产及生活带来了极大影响。经过对平泉村至武家坡村地裂缝的现场实地调查,认为清徐县平泉村-武家坡村地裂缝的分布情况复杂,影响带的宽度从3m左右到100多米不等,凡位于地裂缝带内的大部分建筑物都遭到了破坏。地裂缝带内的地面变形形式有陡降型和缓降型两类,其中位于陡降型变形带上的建筑物破坏最为严重。地裂缝引起建筑物的破坏主要有墙体开裂、地面倾斜、地基下沉、楼梯断裂、门窗变形等多种形式。清徐地裂缝目前仍处于活动阶段,这种活动趋势还将持续一段时间,建议地裂缝带内的村民应尽快搬迁,并限制其在地裂缝带内的工程活动,以免造成更大的损失。     

多级多层复合滑坡工程病害的试验研究

张家坪滑坡具有多级多层的复杂滑体结构,本文选取最典型的断面开展了大型地质力学模型试验,模拟了边坡的开挖过程,并采用均匀毛细浸润技术研究雨水作用下的坡体稳定性,通过有无支挡的两阶段试验对比,分析了多级多层复合滑坡的变形失稳机制和工程病害,以及相应抗滑支挡结构的加固效果。     

区域地质灾害趋势预测理论与方法

区域地质灾害趋势预测对于国家土地资源的合理开发利用和制定减灾防治对策具有重要意义。本文总结了区域地质灾害三个层次评估的理论与方法, 即基于自然属性的地质灾害研究、基于风险分析的地质灾害研究和基于信息-决策支持系统的地质灾害研究。作者认为, 运用GIS技术, 将这三层次的评价方法结合起来, 是进行区域地质灾害趋势预测的有效途径。本文最后介绍了1∶600万全国地质灾害趋势预测图编制的思路与成果。     

An Algorithm for Robust Inference for the Cox Model with Frailties

Abstract

This article proposes a robust method of statistical inference for the Cox's proportional hazards model with frailties. We use the Metropolis—Hastings algorithm and the bootstrap method. We present a computationally efficient algorithm with a customized data structure to implement this method and demonstrate this technique with real data.     

Flammability studies of benzene and methanol with different vapor mixing ratios under various initial conditions

This research investigated the influence of binary solutions of benzene and methanol for their vapor flammability characteristics. The different mixing ratios (100/0, 75/25, 50/50, 25/75 and 0/100 vol%) samples were injected into a 20-liter spherical explosion vessel under various initial temperatures (100, 150 and 200°C) to study their flammability behaviors. According to the experimental results, the flammability diagram of mixtures can be completely illustrated and combined with specific safety-related properties such as lower explosion limit (LEL), upper explosion limit (UEL), minimum oxygen concentration (MOC), maximum explosion overpressure (P_max), and gas or vapor deflagration index (K_g). The experimental results showed that the UEL, P_max and K_g all increased with the temperature, pressure and oxygen concentration, whereas there was no significant variation on the part of LEL. The results can provide specific information on fire and explosion hazards for related industries.     

Risk measures, distortion parameters, and their empirical estimation

Risk measures are of considerable current interest. Among other uses, they allow an insurer to calculate a risk-loaded premium for a random loss. However, the premium principle in use by the insurer may be, at least in part, based on considerations other than risk. It is then important to quantify the degree to which the premium compensates the insurer for the risk associated with the loss. This can be done by choosing a suitable risk measure and solving for the parameter that leads to the insurer’s premium. When the loss distribution is unknown, this becomes a statistical estimation problem.In this paper, we investigate the nonparametric estimation of the parameter associated with a distortion-based risk measure. It is assumed that the premium principle is known, but no information is assumed about the loss distribution, and therefore empirical estimators are used. We explore the asymptotic properties of the resulting estimator of the risk measure parameter in general and for three well-known risk measures in particular: the proportional hazards transform, the Wang transform, and the conditional tail expectation.     

基于生存数据的半参数变换的删失回归估计

生存数据经过未知的单调变换后等于协变量的线性函数加上随机误差, 随机误差的分布函数已知或是带未知参数的已知函数\bd 本文先给出未知单调变换的一个相合估计, 再对删失数据做变换, 在此基础上给出了协变量系数的最小二乘估计, 并讨论它的大样本性质.