A Knowledge-Based Computerized Approach to the Development of a Sinkhole Database

This study proposes a knowledge-based, computerized method to develop an initial sinkhole database as a basis for subsequent field investigation to improve on the established database. The knowledge-based data analysis represents sinks (i.e., topographic depressions) as isolines and associates them with contextual land use, land cover, and hydrologic information relevant to potential sinkhole hazard. Sinks of high priority for subsequent field investigation are identified based on combinations of contextual attributes. The proposed methodology for knowledge-based development of a preliminary sinkhole database is valuable for hazard planning and management.     

采煤沉陷区输电铁塔复合防护板基础抗变形性能及其板厚取值研究

以某采煤沉陷区内的典型输电铁塔及其复合防护板基础工程为背景,考虑地基-基础-上部铁塔结构的共同作用,对不同板厚复合防护板基础的抗采动变形性能进行了研究,并引入＂保护作用＂的概念,对独立基础和复合防护板基础的抗变形性能进行了分析。研究表明,设置复合防护板后,与独立基础相比,可明显减少铁塔支座的水平位移及上部结构的应力,支座位移与结构应力随着复合大板厚度的增大而减小,其减小的幅度随着板厚的增大而趋缓,当板厚达到一定数值以后几乎不再减小。提出的复合防护板的厚度可取铁塔基础长向根开的1/45～1/35的建议,以供采煤沉陷区内复合防护板基础的设计参考。     

不同气温与土壤湿度条件下籽蒿幼苗的表型可塑性

  植物表型可塑性是其适应环境的结果。为了探讨构件水平和全株水平表型可塑性的差异,我们选择籽蒿进行了双因素(气温:35 ℃、30 ℃、20 ℃; 土壤水分:对照、轻度、中度、重度胁迫)随机化区组实验以分析不同环境条件下植物的表型可塑性。结果表明,气温对籽蒿株高生长率有显著影响,土壤水分胁迫对籽蒿株高生长率无显著影响; 气温和土壤水分胁迫对籽蒿地上部生物量和根重生长率均无显著影响; 土壤水分胁迫对籽蒿幼苗根冠比有显著影响,而气温对其则无显著影响。这说明气温和土壤水分胁迫对籽蒿幼苗构件表型可塑性和全株表型可塑性的影响是有差异的。进一步分析表明,气温对籽蒿幼苗的叶含水量有显著影响,而对籽蒿幼苗的叶饱和亏无显著影响,这说明气温对籽蒿幼苗株高生长率的影响是通过影响其叶含水量来实现。     

Deep Structure and Dynamics of Passive Continental Margin from Shelf to Ocean of the Northern South China Sea

To study the deep dynamic mechanism leading to the difference in rifting pattern and basin structure from shelf to oceanic basin in passive continental margin,we constructed long geological sections across the shelf,slope and oceanic basin using new seismic data.Integrated gravity-magnetic inversion and interpretation of these sections were made with the advanced dissection method.Results show that the basement composition changes from intermediate-acid intrusive rocks in the sheff to intermediate-basic rocks in the slope.The Moho surface shoals gradually from 31 km in the sheff to 22.5 km in the uplift and then 19 km in the slope and finally to 13 km in the oceanic basin.The crust thickness also decreases gradually from 30 km in the northern fault belt to 9 km in the oceanic basin.The crustal stretching factor increases from the shelf toward the oceanic basin,with the strongest extension under the sags and the oceanic basin.The intensity of mantle upwelling controlled the style of basin structures from sheff to oceanic basin.In the Zhu 1 depression on the shelf,the crust is nearly normal,the brittle and cold upper crust mainly controlled the fault development;so the combinative grabens with single symmetric graben are characteristic.In the slope,the crust thinned with a large stretching factor,affected by the mantle upwelling.The ductile deformation controlled the faults,so there developed an asymmetric complex graben in the Baiyun (白云) sag.     

基于损伤部位向量法的钢框架损伤识别研究

对损伤部位向量(DLV)法作了简单介绍,并用该方法对钢框架进行了损伤识别和损伤定位。该方法假定结构损伤前后为线性,对结构损伤前后柔度矩阵差进行奇异值分解,将奇异值为零所对应的向量,作为静荷载施加在无损结构的测点位置,则应力为零的单元为可能损伤的单元。对3种不同工况的钢框架进行了振动模态试验,用前3阶模态参数构造框架的柔度矩阵,按照DLV法对其进行了损伤识别,识别结果与已知损伤情况相一致。从测试自由度不完备、噪声和振型质量归一化系数这3个方面对识别效果进行了分析,结果表明:当损伤使结构动力特性有微小改变时,使用该方法不易定位损伤,应结合局部损伤识别方法进行判定;当损伤使结构动力特性有较大改变时,该方法能有效识别损伤的单元。DLV方法概念简单,理论明确,不受结构类型的限制,不需要结构的数学模型和模型缩聚或扩展技术,只需获得结构损伤前后的前几个低阶模态参数,即可识别结构一处或多处损伤,实际应用时可操作性强。     

我国省域工业主导产业的遴选与发展

工业主导产业在国民经济发展中起着决定性和指向性的作用.主导产业的选择是经济发展阶段的重要课题.依据6个量化指标,从4个维度对“十一五”期间主导产业进行遴选,发现以能源及相关产业为代表的重化工业是各省的重点,高新技术产业成为主导产业的省份较少,劳动密集型产业依然是东部发达省市的重点,预期中的产业转移并未实现;以行业为变量对各省份的主导产业进行聚类分析,可将31个省份划分为5类,反映了我国各省份主导产业布局特点;在此基础上,依据产业生命周期理论和各地区“十二五”发展趋势,提出了相应的对策建议.     

Evaluation of water quality of the lower Mississippi River

Using the most recent hydrologic and water quality data issued by U.S. Geological Survey, this paper deals with the pollution of the lower Mississippi River for the 1978–1981 water years and compares the water pollution of this period with that of the 1973–1977 water years. The water quality of the lower Mississippi River has not been evaluated comprehensively. This paper utilizes the Cartesian coordinates approach in an appraisal of water quality of the Mississippi River for the first time. Thus, it provides a foundation for the further comprehensive evaluation of environmental quality and research of water resources.     

Reflection and transmission of seismic waves at an interface betwen two saturated soils

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Origin and diagenesis of Quaternary travertine shrub fabrics, Rapolano Terme, central Italy

Millimetre to centimetre sized arborescent shrub-like calcite precipitates are common constituents of hot water travertine shallow pool deposits of Quaternary age at Rapolano Terme, Tuscany, Italy. In the presently forming travertines, the shrubs consist of apparently random associations of (i) micrite aggregates and (ii) subhedral to euhedral rhombic spar crystal aggregates. In thin section, the micrite aggregates appear dark and the spar-rhomb aggregates light, giving the shrubs a mottled appearance. Travertines are basically produced by CaCO₃ precipitation due to degassing and evaporation of the spring waters, although biological influence may also stimulate precipitation. The formation of masses of erect shrubs, rather than dense crystal crusts that form on slopes, is probably due to limited water flow in the pool environments. Microbes, including bacteria and diatoms, are important influences on shrub microfabric and external shape. The micrite aggregates are associated with bacteriform bodies, seen as tiny rods and spheres. The micrite precipitates around these bodies and in adjacent biofilm. Spar-rhomb precipitation appears to be external to the biofilm, and may be related to the presence of diatoms which are locally closely associated with the spar-rhombs, although an essentially inorganic origin, particularly for the more euhedral rhombs, cannot be ruled out. In the older Quaternary travertines, the original microfabric of the shrubs has been diagenetically altered. The original mottled appearance of the shrubs has become uniformly dark and micritic, and the evidence for the dual micritic and spar-rhomb origin of the shrubs is obscured or destroyed. Spar-micritization of the shrubs is probably due to abiotic, and locally biotic, dissolution. Previous studies did not recognize the diagenetic micritization and attributed shrub formation entirely to bacterial activity.     

浅谈城市高层建筑施工的沉降观测

目前城市高层建筑越来越多,它的使用安全性也随之受到人们的关注。对城市高层建筑垂直沉降观测进行了详尽的阐述,介绍了沉降基准点、观测点的布设与设计原则,沉降观测的方法与施测精度,建筑物的沉降趋势以及观测成果的整理与分析,并进行了实例分析,对实际工作应用具有一定的参考价值。