基于马尔可夫链的多元指示地质统计模型

与传统基于交叉变差函数(cross variogram)的多元指示地质统计模型相比,基于马尔可夫链的多元指示地质统计模型采用转移概率(transition probability)来描述区域化变量的空间变化,可以很好地反映复杂空间的连续性,弥补了传统地质统计模型没有考虑地质体分布存在不对称性的缺陷,简化了各向异性的处理过程,且在建立模型的过程中,融入了地质类型分布的比例、平均长度和相互间的迁移转换趋势等地质统计信息,使建模过程更直观,更易于理解。用这种方法建立的模型在理论上有比较成熟的随机理论支持,在实际应用中能更准确地反映地质体的空间分布特征。由于该模型考虑了地质体空间分布的连续性、不对称性和各向异性等特征,因此将其用于模拟地下含水层的空间结构,可以真实反映实际含水层的空间分布,为进一步模拟地下水运动提供有力支持。     

河流污水非饱和入渗对沿岸地下水质的影响

在分析河流污水非饱和入渗过程和输移机理的基础上,建立了河流污水非饱和入渗对沿岸土壤及地下水质影响的预测预报模型。该模型将水力传导率分离为饱和水力传导率项和相对水力传导率项,并运用全隐式差分和时间中心差分格式分别离散,计算过程中根据土壤饱和度调用不同格式,克服真解波动和耗散现象。取得了良好效果。以江苏省徐州市奎河的徐村和黄桥河段污水中的保守性污染因子Cl-和非保守性污染因子氮为例,研究非饱和入渗污染物在土壤及地下水中迁移转化过程的模拟模型参数,运用所率定的参数进行预测计算,计算值与相关的实测值进行对比分析,结果表明,两者吻合良好。     

石河子市生命线工程系统震害预测(2)--交通工程系统

为了达到现代化城市交通系统的减灾目标，针对城市交通工程系统特点，从城市对外联络和对内救援系统两方面讨论了石河子市交通系统的可靠性。基于对可靠性分析所提供的系统震害预测，根据石河子市区道路网的现状，分析了石河子市日常交通运行中的道路病害多发路段。以历史地震交通系统出现的灾害为鉴，提出了现代化城市交通系统的灾害串。     

海洋沉积物热释光——潜在的天然气水合物找矿方法

概述了热释光的形成机理。从放射性方法探测油气藏的原理出发,提出了海洋沉积物热释光探测天然气水合物的可能性。对采自中国南海、东海的海底沉积物进行了有机烃、金属元素和热释光分析。结果表明,热释光与有机烃类呈正相关,天然气水合物形成和分解产生的碳酸钙、硫酸钙及硫酸钡沉淀是很好的热释光晶体,在矿物结晶过程中加入的微量金属元素对热释光起到调节作用。热释光不受有机污染的影响,灵敏度高,是很有前景的寻找天然气水合物的方法。     

TLD对海洋平台地震反应控制的简化计算方法

调频液体阻尼器（Tune Liquid Damper，简称TLD）对地面结构位移反应与加速度反应的较好控制作用已得到理论与试验的验证。本文在此基础上研究了TLD对海洋平台动力反应控制的简化计算方法。计算中，TLD中液体的控制力采用较精确的数值计算法和简化计算法两种方法，通过对海洋平台地震反应计算的结果表明，该简化计算方法具有很高的精度，其结果对海洋平台的抗震设计具有借鉴作用。     

From compassion to compliance? Trends in refugee and humanitarian migration in Australia

Australia has a long history of offering protection to refugees. In the post-World War II period it has predominantly been involved in an offshore refugee settlement program whereby it has assisted international efforts to assist refugees and resettled almost 600,000 refugees in Australia. In recent years, however, substantial numbers of asylum seekers have arrived on Australia's shores and this has seen the development of an onshore refugee program which is seen as quite separate from the offshore program. This has involved the detention of asylum seekers while their claims for protection are assessed and when they are assessed as being qualified for protection they are given different status to offshore determined refugee settlers. The paper summarises the development of refugee policy in Australia and the evolution of the offshore and onshore policies. This revised version was published online in August 2006 with corrections to the Cover Date.     

年调节平原型水库与地下水联合调蓄分析

本文以辽河石佛寺水库为例,介绍了年调节平原型水库与地下水联合调蓄的模拟分析方法,提出了为满足沈阳市城市供水,辽河应需保证的最少径流量。根据辽河石佛寺水文站的实测资料分析,辽河在枯水季节1～2月份径流量存在一定的风险,因此本文通过模糊带权马尔可夫链方法预测了未来19年1～2月份的径流量状态,并对其可靠性进行了分析,从而为水库地表水与地下水联合调蓄的供水规模及其运行方式提供了科学依据。     

黄土丘陵区土壤侵蚀链垂直带水沙流空间分布

采用多坡段组合模型、人工模拟降雨实验研究了土壤侵蚀链垂直带水沙流空间分布变化特征。结果表明:愈向下坡方向的坡段产流量愈大,单位面积、单位时间的产流量按坡段排列为:谷坡>梁峁坡下部>梁峁坡中部>梁峁坡上部。雨强为29.7mm/h时,坡面上没有沟蚀发育;雨强为60.5mm/h时,细沟主要分布在梁峁坡下部和谷坡处;雨强为90 2mm/h时,各种侵蚀形态在坡面均有较好发育,细沟的出现部位一直伸展到梁峁坡中部和上部之间。由于上坡来水来沙的作用,梁峁坡的产沙量增大了20.2%～63.5%,谷坡的产沙量增大了42.9%～74.5%。     

Bayesian Mixture Modelling in Geochronology via Markov Chain Monte Carlo

In this paper we develop a generalized statistical methodology for characterizing geochronological data, represented by a distribution of single mineral ages. The main characteristics of such data are the heterogeneity and error associated with its collection. The former property means that mixture models are often appropriate for their analysis, in order to identify discrete age components in the overall distribution. We demonstrate that current methods (e.g., Sambridge and Compston, 1994) for analyzing such problems are not always suitable due to the restriction of the class of component densities that may be fitted to the data. This is of importance, when modelling geochronological data, as it is often the case that skewed and heavy tailed distributions will fit the data well. We concentrate on developing (Bayesian) mixture models with flexibility in the class of component densities, using Markov chain Monte Carlo (MCMC) methods to fit the models. Our method allows us to use any component density to fit the data, as well as returning a probability distribution for the number of components. Furthermore, rather than dealing with the observed ages, as in previous approaches, we make the inferences of components from the “true” ages, i.e., the ages had we been able to observe them without measurement error. We demonstrate our approach on two data sets: uranium-lead (U-Pb) zircon ages from the Khorat basin of northern Thailand and the Carrickalinga Head formation of southern Australia.