基于ObjectARX技术的管道参数化建模

基于AutoCAD 2008,结合ObjectARX 2008软件包,在.NET 2005环境下开发了管道参数化建模系统。阐述了此系统的数据文件的组织,所采用的关键技术以及实现的基本功能。     

复杂系统理论与Agent模型在土地变化科学中的研究进展

基于复杂系统理论与Agent 模型,分别从理论与方法的角度梳理并总结了当前土地变化科学的研究进展。复杂系统理论为研究土地变化所处的“耦合的人类-自然系统”及其复杂性问题提供理论支撑;而基于Agent 的模拟作为研究复杂系统的重要工具,为传统土地变化模拟提供新的方法支持。当前,ABMs与土地变化模型相结合(ABM/LUCC),无论是模型构建还是模型应用均取得了显著进展。然而,其也存在诸多问题,尤其是理论与应用脱节,使很多建模者容易陷入“为建模而建模”的误区。此外,现有的ABM模型设计较为随意,模型间差异太大,不利于跨区域比较研究的开展。因此,虽然ABM是认识复杂系统的有效方法,但是建模之前离不开对系统复杂性的深入研究;基于Agent 的土地变化模拟的意义在于充分表达“人类-自然”系统的综合复杂关系,从而合理的预测土地变化(结构与功能) 的动态过程,解释并评价土地变化的可能影响。     

Fault type analysis along the San Andreas Fault zone: A numerical approach

Finite Element (FE) modeling under plane stress condition is used to analyze the fault type variation with depth along and around the San Andreas Fault (SAF) zone. In this simulation elastic rheology was used and was thought justifiable as the variation in depth from 0.5 km to 20 km was considered. Series of calculations were performed with the variation in domain properties. Three types of models were created based on simple geological map of California, namely, 1) single domain model considering whole California as one homogeneous domain, 2) three domains model including the North American plate, Pacific plate, and SAF zone as separate domains, and 3) Four domains model including the three above plus the Garlock Fault zone. Mohr-Coulomb failure criterion and Byerlee's law were used for the calculation of failure state. All the models were driven by displacement boundary condition imposing the fixed North American plate and Pacific plate motion along N34°W vector up to the northern terminus of SAF and N50°E vector motion for the subducting the Gorda and Juan de Fuca plates. Our simulated results revealed that as the depth increased, the fault types were generally normal, and at shallow depth greater strike slip and some thrust faults were formed. It is concluded that SAF may be terminated as normal fault at depth although the surface expression is clearly strike slip.     

金融危机下国家大规模投资政策模拟

构建了一个中国多区域可计算一般均衡模型(MReCGE-C),利用该模型分析了我国应对国际金融危机的大规模投资政策。MReCGE-C根据城乡属性和年龄结构对居民进行了分组,放松了要素流动的限制,使劳动力和资本可以同时跨区域跨部门流动,并设计了一种基于居民终生效用的区域均衡机制,通过区域差距变量可以调控和测度区域差距。最后利用MReCGE-C模型针对国家大规模投资计划下的3种典型投资方案进行了模拟。结果发现在等量新增投资下,针对中部地区投资方案的GDP增长率高于针对中西部和全国投资方案的GDP增长率,同时针对中部地区投资方案对于城乡就业的拉动也要优于其余两种投资方案,而且可以实现缩小区域差距的目标。综合比较,目前国家大规模投资的优势应该指向中部地区。     

Assessing the natural component of the external load due to organic matter and biogenic elements on the water bodies in Northwestern Russia

We suggest the method to calculate the natural component of the external loads due to organic matter and biogenic elements on the unexplored lakes using the removal rate moduli for these elements, and indices of the lakes’ specific catchments. The schematic map has been generated for the distribution of natural moduli of removal on the catchment of the Gulf of Finland. We calculated the external natural loads for 94 lakes in landscapes with a high percentage of lakes.     

基于实体建模的三维地层构造

以三维实体模型为基础,提出了三维地层实体模型,给出了三维实体地层模型的体系数据结构和几何拓扑结构,完整描述了三维地层模型。给出了地层模型的构造过程,并讨论了地层缺失、倒转等的特殊地质状况的构模处理方法。三维地层实体模型是完整,全面的地层模型,比基于多层网格和三棱柱体元的地层模型具有更多的优点。     

黄土高原丘陵沟壑区单元流域次暴雨输沙模型

黄土高原尤其是黄土丘陵沟壑区土壤侵蚀异常严重,在该区开展单元流域产沙模拟对于流域侵蚀产沙及沟道系统泥沙输移比研究有着重要的意义。本文选取陕北岔巴沟单元流域团山沟为研究对象,利用1961-1969年间水文泥沙资料,构建了流域产沙模型:以流域输沙关系表达式Ms=CsH为理论框架,经分析发现洪峰流量、最大含沙量、平均流量与次洪含沙量相关性显著,近而以洪峰流量、平均流量、最大含沙量及径流深为模型变量,通过模拟误差分析,构建并选取了以径流深和洪峰流量、径流深和最大含沙量为变量的经验模型:Ms=H(109.2ln(Qz)+546.1);Ms=H(Cz-141.2)。与目前已有模型相比,以上模型具有很好的模拟效果,尤其是在模拟小产沙事件时模拟效果较好,模型在临近流域水旺沟上的应用效果也较好。另据研究发现,高含沙水流的存在,使得在不同产沙模数水平下产沙模拟响应机制不同,对产沙模数小于300 t/km2次暴雨事件,流量的对数函数拟合效果明显优于幂函数拟合;对产沙模数大于1000 t/km2次暴雨事件,流量的幂函数拟合效果好于对数函数拟合,但差异不大。     

Quantifying the effect of in-stream rock clasts on the retardation of heat along a stream

With the introduction of Distributed Temperature Sensing (DTS) into the field of hydrology, temperature has become a powerful tracer in both space and time. However, the interpretation of the observed temperature signal is often not straightforward due to its non-conservative behavior. The objective of this research is to explore and quantify the retardation of heat along a small first order stream, with the long-term objective of identifying different runoff mechanisms by using heat as a tracer.     

Higher-order compositional modeling with Fickian diffusion in unstructured and anisotropic media

We present advances in compositional modeling of two-phase multi-component flow through highly complex porous media. Higher-order methods are used to approximate both mass transport and the velocity and pressure fields. We employ the Mixed Hybrid Finite Element (MHFE) method to simultaneously solve, to the same order, the pressure equation and Darcy's law for the velocity. The species balance equation is approximated by the discontinuous Galerkin (DG) approach, combined with a slope limiter. In this work we present an improved DG scheme where phase splitting is analyzed at all element vertices in the two-phase regions, rather than only as element averages. This approximation is higher-order than the commonly employed finite volume method and earlier DG approximations. The method reduces numerical dispersion, allowing for an accurate capture of shock fronts and lower dependence on mesh quality and orientation. Further new features are the extension to unstructured grids and support for arbitrary permeability tensors (allowing for both scalar heterogeneity, and shear anisotropy). The most important advancement in this work is the self-consistent modeling of two-phase multi-component Fickian diffusion. We present several numerical examples to illustrate the powerful features of our combined MHFE–dg method with respect to lower-order calculations, ranging from simple two component fluids to more challenging real problems regarding CO₂ injection into a vertical domain saturated with a multi-component petroleum fluid.     

汾渭地震带地震趋势数学建模分析

按照中国大陆及邻近地区活动地块和地震带的划分方案, 使用Mapsis软件选取了汾渭地震带1000年以来M_S4.7以上地震, 这样的地震资料应具有地质单元的统一性。 使用数学中19阶多项式模型, 对地震资料进行最佳逼近拟合, 并递推未来1—2年时间尺度预测。 模型中的参数用最小二乘法求取。 引用一种数学方法来描述汾渭地震带的地震趋势规律。