An object-oriented knowledge representation structure for exploration data integration

Knowledge representation structure and reasoning processes are very important issues in the knowledge-based approach of integrating multiple spatial data sets for resource exploration. An object-oriented knowledge representation structure and corresponding reasoning processes are formulated and tested in this research on the knowledge-based approach of integrating spatial exploration data. The map-based prototype expert system developed in this study has self-contained knowledge representation structure and inference mechanisms. It is important to distinguish between lack of information and information providing negative evidence for a map-based system because the spatial distribution of data sets are uneven in most cases. Error and uncertainty estimation is also an important component of any production expert system. The uncertainty propagation mechanisms developed here work well for this type of integrated exploration problem. Evidential bellef function theory provides a natural theoretical basis for representing and integrating spatially uneven geophysical and geological information. The prototype system is tested using real mineral exploration data sets from the Snow Lake area, northern Manitoba, Canada. The test results outline the favorable exploration areas successfully and show the effectiveness of the knowledge representation structure and inference mechanisms for the knowledge-based approach.     

Rangeland production: use of models incorporating aggregated knowledge and fuzzy construction

This work reports on a method using fuzzy membership functions to construct an aggregated interaction matrix in which the summation of variables is scaled according to the way rainfall and soil variables affect water availability to plants and hence influence rangeland productivity. Aggregation of the variables gives a comprehensive value which can be used to predict production. The model increases the predicability of production to 81% compared to models using rainfall alone and a multiplicative parametric one which give predictibilities of 61 and 76% respectively. The results showed that (1) the importance of rainfall in determining production was most important at lower rainfalls i.e. <350 mm; (2) soil texture and particularly slope were important through out the rainfall range (149–700 mm) investigated; and (3) soil depth was only important at the higher >350 mm rainfalls. The aggregated interaction matrix gives a measure of land productive capability.     

华南春季强风暴背景流场的若干特征

本文利用常规探测资料,分析了1983年3月25日发生在珠江三角洲地区的一次强对流天气过程背景流场的几个重要特征,如高空急流的结构与变化、辐散风场及与之相联系的背景次级环流、风场垂直切变和水平切变等.     

雷州半岛局部地热异常及其形成机制

雷州半岛地热场主要受基底构造格局的控制和地下水活动的影响,隐伏花岗岩体放射性元素生热对盖层地温的贡献不可忽视,第四纪更新世火山喷发活动的岩浆余热已几乎完全散失,岩浆体和围岩温度已趋于平衡。由火山喷发而形成的雷北螺岗岭和雷南石峁岭两个玄武岩台地,为半岛地下水的主要补给区,由于冷水流下渗的地温效应,新生界盖层浅部地温梯度<3℃/100m,呈现地热负异常。在以传导传热为主的区域,地热场特点与华北盆地相似,新生界盖层地温梯度与基底岩面的埋深密切相关。由于地壳深部较均一的热流在地壳表部再分配的结果,若干凸起区盖层地温梯度为4—5℃/100m,呈现地热正异常。某些控制凸起区的边界断裂,当深层热水沿其上涌,造成附加热源,和传导传热相叠加,盖层地温梯度可高达5—8℃/100m,形成更鲜明的地热正异常。     

Inversion of arrival-times in a region of dilatancy anisotropy

Shear-wave splitting has been identified in many three-component seismograms from two separate field experiments on a section of the North Anatolian Fault in North-West Turkey. These observations are consistent with shear-wave propagation through a zone of extensive-dilitancy anisotropy. A preliminary attempt has been made to confirm this interpretation by simultaneously inverting suites of arrival-times for hypocentral locations and for parameters describing an anisotropic halfspace. Although the inversion procedure is not globally convergent, it is possible to recognize the true solution by systematically varying the initial conditions. Applied to selected data sets, the inversion defines several anisotropic models that fit the data significantly better than a simple isotropic model, and display the anisotropy required by the shear-wave splitting. However, most of these anisotropic models are not superior when they are used to individually locate events in a much larger data set. However, for each experiment, there is a single model that produces clearly superior locations for the larger data sets than those of other anisotropic or simple isotropic models. Both models display similar velocity variations which are characteristic of propagation through distributions of biplanar cracks displaying orthorhombic symmetry. The principal axes of the two models are oriented in similar directions and are within 20° of the principal axis of regional stress derived from fault-plane solutions. The solutions indicate low velocities close to the tensional axis, as would be expected in extensive-dilatancy anisotropy.     

混沌系统的局域特征与可预报性

讨论了混沌系统的时间和空间的局域特征。首先分析了研究时间和空间局域特征的必要性。接着引进了有限时间不稳定和局域时间不稳定的概念，并对有关的计算问题进行了研究。对Ｌｏｒｅｎｚ系统的具体计算表明，随着轨线在混沌吸引子上的演变，局域不稳定特征有很大的变化，相应误差增长也有很大的变化。相应于误差迅速增长的轨线部分局限于很有限的相空间范围内，而且同误差增长缓慢的轨线部分占据的相空间区域截然可分。每一个例的可预报性依赖于轨线在相空间中所处的区域。混沌系统的这种局域特征可以是导致个例业务预报技巧之间有很大差别的主要原因。     

台风影响期间珠江三角洲局地强风暴和大暴雨发生的环境条件

采用１９７６－１９８３年６－８月珠江三角洲地区受台风影响期间区内各站逐日的强风暴和降水资料以及广泛站的探空资料，用相关对比度分析方法，对台风环流中的珠江三角洲局地强风暴和大暴雨发生的环境条件进行统计诊断，得出台风影响珠江三角洲时这两种强天气发生的有利的环境条件，并发现二者在气压、风速、层结稳定度和中下层位势不稳定等方面显著不同。     

Selection of regional historical rainfall time series as input to urban drainage simulations at ungauged locations

It has become established practice during the past 20 years to use high-resolution historical rainfall time series as input to hydrological model packages for detailed simulation of urban drainage systems. However, sufficiently long rain series are rarely available from the exact catchment in question and simulations are hence often based on available rain series from other locations. Extreme rainfall properties of importance to the performance of urban storm drainage systems vary significantly even in regions with only minor physiographic differences. Part of this variation can be explained by regional variations of the mean annual rainfall and the remaining statistical residue can be interpreted as statistical uncertainty.In Denmark, more than 75 high-resolution rain gauges are installed across a total area of 43,000 m. About 40 gauges had sufficiently long records to be included in a comprehensive national investigation where newly developed statistical regionalisation procedures were used to model the regional variation of extreme rainfalls. On this basis, a spreadsheet model was made available for estimation of extreme design rainfalls and the associated uncertainty at any location in the country. Statistics were furthermore computed to classify historical rainfall time series according to the developed regional model, and this makes it possible to assess the uncertainty related with using different historical rain series for simulations at ungauged locations.This research indicates that use of historical point rainfall data at ungauged locations introduces a significant uncertainty that is largely overlooked in today's practice. The engineering recommendation is to select historical rain series based on an evaluation of the local physiographic characteristics (e.g., the mean annual rainfall) and a (pre-defined) desired safety level of the simulations.