基于增量段式的地形数据存储模型设计及算法实现

在研究地形多分辨率细节层次模型构建理论的基础上,提出了结合地形特征的模型细节层次的细分过程,改进了基于外存的数据存储设计方法。设计了基于增量段式存储的数据组织方式,研究了地形数据绘制过程中的裂缝现象,引入模型高度损失误差计算方法,通过采用增删高程点的办法,消除了绘制图形中的裂缝。以某地区的DEM数据为实验数据,采用C++和OpenGL编程实现了地形的绘制。结果表明：本存储策略优于传统存储策略,通过增量段式的形式存储不同分辨率的高程点,重叠的高程值不再重复存储,以节约外存空间,减少了数据冗余度,I/O操作时间提高率为25%。且随着数据量增加,I/O操作时间提高效率更为显著。该存储设计将物理分块、逻辑分层、索引检索方法结合在一起使用,在减少外存占用率、降低数据量加载的同时,也提高了数据扩展的灵活性。当增加地形分块时,不会影响原有分块和存储结构。实验效果与原始地形非常相似,保证了生成的细节层次模型的真实性。此外,针对DEM实验数据,在加载非相邻分辨率等级层次的数据时,地形绘制过程出现裂缝的问题,通过删除高程点的办法来消除裂缝,取得了很好的实验效果。     

The importance of crustal structure in explaining the observed uncertainties in ground motion estimation

In this short article, the possible reduction in the standard deviation of empirical ground motion estimation equations through the modelling of the effect of crustal structure is assessed through the use of ground-motion simulations. Simulations are computed for different source-to-site distances, focal depths, focal mechanisms and for crustal models of the Pyrenees, the western Alps and the upper Rhine Graben. Through the method of equivalent hypocentral distance introduced by Douglas et al. [(2004) Bull Earthquake Eng 2(1): 75–99] to model the effect of crustal structure in empirical equations, the scatter associated with such equations derived using these simulated data could be reduced to zero if real-to-equivalent hypocentral distance mapping functions were derived for every combination of mechanism, depth and crustal structure present in the simulated dataset. This is, obviously, impractical. The relative importance of each parameter in affecting the decay of ground motions is assessed here. It is found that variation in focal depth is generally more important than the effect of crustal structure when deriving the real-to-equivalent hypocentral distance mapping functions. In addition, mechanism and magnitude do not have an important impact on the decay rate.     

Vertical Crustal Motion along the Mediterranean and Black Sea Coast Derived from Ocean Altimetry and Tide Gauge Data

Tide gauge (TG) data along the northern Mediterranean and Black Sea coasts are compared to the sea-surface height (SSH) anomaly obtained from ocean altimetry (TOPEX/Poseidon and ERS-1/2) for a period of nine years (1993–2001). The TG measures the SSH relative to the ground whereas the altimetry does so with respect to the geocentric reference frame; therefore their difference would be in principle a vertical ground motion of the TG sites, though there are different error sources for this estimate as is discussed in the paper. In this study we estimate such vertical ground motion, for each TG site, from the slope of the SSH time series of the (non-seasonal) difference between the TG record and the altimetry measurement at a point closest to the TG. Where possible, these estimates are further compared with those derived from nearby continuous Global Positioning System (GPS) data series. These results on vertical ground motion along the Mediterranean and Black Sea coasts provide useful source data for studying, contrasting, and constraining tectonic models of the region. For example, in the eastern coast of the Adriatic Sea and in the western coast of Greece, a general subsidence is observed which may be related to the Adriatic lithosphere subducting beneath the Eurasian plate along the Dinarides fault.     

New discoveries in dynamics of an M8 earthquake-phenomena and their implications from the 2003 Tokachi-oki earthquake using a long term monitoring cabled observatory

At the 2003 Tokachi-oki earthquake of M8, seafloor phenomena such as a generation process of tsunami, seafloor uplifts, turbidity current, etc., were observed using a cabled observatory installed on the seafloor. The turbidity current was observed as a benthic storm caused presumably by the mainshock. The seafloor uplifts were observed at the mainshock and continuously after the mainshock. The uplifts were 0.35, 0.37, and 0.12 m for epicentral distances of 25.5, 31.4, and 81.7 km, respectively. After the mainshock, a continuous uplift of the seafloor is observed at all three pressure gauge locations indicating that there was a change in the state of friction on the plate boundary interface by the mainshock. In this paper, we first show what was observed using the cabled observatory installed right above the focal area of the earthquake, and then we discuss to summarize these phenomena associated with the earthquake, its possible causes, and future directions in long term monitoring of seismogenic processes.     

淮南矿业集团丁集煤矿风井预注浆工程施工工艺

淮南矿业集团丁集煤矿风井井筒区地层软、硬互层频繁,岩层倾角23°左右,可钻性差,为防止钻孔施工中发生偏斜,采用了满眼钻具组合和主、副支点扶正器的钻进方法,达到了终孔井底落点允许最大偏斜率5‰,固管段允许最大偏斜率2‰要求,保证了地面预注浆工程的质量。     

不对称鱼嘴构造研究

比较对称型鱼嘴构造和不对称鱼嘴构造的形成机制，建立鱼嘴构造类型与剪切作用方式之间的关系，认识到剪切作用方式是产生对称和不对称鱼嘴香构造的外在原因。运用应变分解的原则，提出计算不对称鱼嘴构造纯剪切应变和简单剪切应变的方法，在此基础上提出了计算不对称鱼嘴构造的剪切应变计；并在前人研究基础上，分析了不对称鱼嘴构造的应变折射现象，认识到基质与能干层的粘性差异是产生不对称鱼嘴构造的内在动因，提出了计算相邻介质的粘度比的新方法，在此基础上提出了不对称鱼嘴构造的应变折射流变计。     

井底钻具组合纠偏技术在新疆YX-1油井的应用

在易斜地层中钻进，降斜保直一直是一个重要的研究课题。介绍了井底钻具组合纠偏技术及其在新疆YX-1油井中的应用。     

油气地表化探指标的统计分类和优选

本文研究了影响趋势面拟合度的主要因素，提出了由参与趋势分析的数据个数n、数据的标准偏差σ和所期望的拟合度c估计最佳趋势面次数k的统计方法。同时还给出了多化探指标下，综合选择趋势面次数的五、c图法。按上述方法，选择趋势面，对我国东部几个地区化探资料处理效果良好，这对于多指标，大数量化探异常的研究有一定的参考价值。