GM(1,1)最佳维数建模法在露天矿边坡变形预测中的应用

露天矿边坡变形是一个复杂的系统,许多影响边坡变形的因素具有灰色信息性质,因此应用灰色模型对边坡变形进行预测是一种很好的研究手段。在灰色模型预测实践中,发现建模数据的维数对模型预测精度有较大影响。从变形预测精度研究入手,提出最佳维数建模法。通过实例应用证明,该法具有较高的预测精度和可信度。     

轨道交通下立交区间基坑降水技术

根据下立交区间基坑特点,合理制定基坑工程降水方案。经工程实践证明,通过疏干井、混合井、降压井的合理设置,联合使用,科学有效地治理了地下水,较好地控制了因降水产生的工程风险。     

云南兰坪-思茅盆地生物地球化学找钾技术方法研究初探

在生物地球化学和“深穿透”理论的指导下,在兰坪-思茅盆地勐野井钾盐矿区及周边开展了生物地球化学找钾技术方法的探索性研究。沿江城县勐野井钾盐矿区及周边一线,对乔木类植物叶子进行了取样,分析,数据处理,特征指标筛选,获得了研究区植物样品主量和微量组分含量背景值,初步圈定了异常区,与以往圈定的找钾远景区较吻合。该区生物地球化学找钾技术取得较好的效果,今后还需扩大采样区域,获得更多样本数据,将找钾特征指标及其异常值的阈值进一步补充完善。     

Neotectonics, sea-level changes and biological evolution in the Fennoscandian Border Zone of the southern Kattegat Sea

Shallow seismic data and vibrocore information, sequence stratigraphic and faunal evidence have been used for documentation of Late Weichselian reactivation of faulting in the south central Kattegat, southern Scandinavia. The study area is situated on the Fennoscandian Border Zone, where tectonic activity has been recurrent since Early Palaeozoic time and still occurs, as shown by present earthquake activity. New data from the area south of the island of Anholt show that after deglaciation fast isostatic rebound resulted in reactivation of a NW-SE striking normal fault system. This tectonic episode is dated to a period starting shortly before 15.0 cal. ka BP and ending around 13.5 cal. ka BP, after regression had already reached a level of about 30 m b.s.l. The vertical displacement associated with the faulting was in the order of 20 m. More generally, the results support the previously reported late Weichselian sea-level highstand, which was followed by forced regression until the eustatic sea-level rise surpassed the rate of glacio-isostatic rebound in early Preboreal. Our findings further imply that drainage of the Baltic Ice Lake through the Øresund at c. 15 cal. ka BP (Bergsten & Nordberg 1992) may have been triggered by tectonic activity in this region.     

Late- and postglacial history of the Great Belt, Denmark

On the basis of shallow seismic records, vibrocoring, macrofossil analyses and AMS radiocarbon-dating, five stratigraphical units have been distinguished from the deepest parts of the central Great Belt (Storebælt) in southern Scandinavia. Widespread glacial deposits are followed by two lateglacial units confined to deeply incised channels and separated by an erosional boundary. Lateglacial Unit I dates from the time interval from the last deglaciation to the Allerød; lateglacial Unit II is of Younger Dryas age. Early Holocene deposits show a development from river deposits and lake-shore deposits to large lake deposits, corresponding to a rising shore level. Lake deposits are found up to 20 m below the sea floor, and the lake extended over some 200–300 km2. The early Holocene freshwater deposits are dated to the time interval c. 10900 to c. 8800 cal. yr BP and the oldest shells of marine molluscs from the Great Belt are dated to c. 8100 cal. yr BP.     

信号传输的屏蔽措施与研究

为了保证信息的正常传输,当布线环境有电磁干扰时,要相应地采用屏蔽系统。为了保证电子设备的正常工作,采用适当的屏蔽措施来阻挡或衰减电磁干扰。本文阐述了在现阶段雷灾中屏蔽的重要性以及屏蔽的具体施工,并对屏蔽的检验提出了一定的见解。     

基于VisIt的全球科学数据并行可视化——以大气温度场为例

针对当前大规模全球科学数据可视化中存在的单机可视化数据量有限、从底层开发并行可视化系统难度大等问题,该文基于分布式环境和VisIt,提出了一种简便、开放而又有效的大规模全球科学数据可视化方法。介绍了VisIt的体系结构及运行机制,给出了自定义数据的并行可视化方法;并基于NCEP数据集及全球空间格网,在小规模集群环境下实现了小粒度适应性球体退化八叉树格网(SDOG)下的全球大气温度场的并行可视化。VisIt的并行可视化性能测试结果表明:通过增加计算节点,VisIt能有效摆脱传统单机可视化对数据量的限制,可实现大规模全球科学数据的并行可视化。     

三种土层结构反应谱平台值的统计分析

本文以建筑抗震设计规范规定的反应谱为目标谱,通过调整加速度峰值和特征周期来人工合成数百条加速度时程曲线,并将其作为土层地震反应分析的地震动输入。在若干有工程意义的场地剖面中,选取和构造了部分软弱土层分别在底部、中部和顶部的三种土层剖面,利用土层地震反应分析的一维等效线性化波动方法,计算了不同土层剖面在不同地震动输入下的地表加速度反应谱的平台值。在统计分析的基础上,给出了不同场地三种土层结构的反应谱平台值的平均值。通过与正常剖面的反应谱平台值比较,给出了三种土层结构的反应谱平台值的影响系数。本文的研究获得了一些有意义的成果。     

汶川地震不同场地反应谱平台值统计分析

加速度反应谱平台值表征地震动的强度特性,场地条件是影响反应谱平台值的一个重要因素.本文选取6组同一地区断层距相近而场地条件不同的强震记录,对其标准化的加速度反应谱形状及平台值进行分析;并以汶川地震中173个有详细地勘场地上的强震记录为基础,统计分析了不同场地类别和断层距区间内的加速度反应谱平台值.本文研究结果显示,场地条件对加速度反应谱平台值有较大影响,随着场地变软,加速度反应谱平台值增大.本文定义了场地影响系数,计算并给出了不同地面峰值加速度对应的场地影响系数.