基于DEM的河流多尺度显示研究

进行了基于DEM的河流多尺度显示方法的研究和试验。采用斯特拉勒算法对河流线进行分级,通过DEM提取河流的高差、集水面积等属性信息,并以此为基础提出了对河流的主支流的自动判别的方法,最终以国家基础地理信息的全国1∶25万数据库为数据源实现了实验区域河流的多尺度显示。     

不确定性选址问题探讨

阐述了GIS网络分析中不确定性选址问题的基本模型及特性。从问题的定义可知其为NP完备类问题。推导了最优解在紧条件的下界算法,并结合广义Powell算法及遗传算法,提出了不确定性选址问题的混合遗传算法,实验证明,在最优解的品质和收敛速度上都达到了比较好的效果。同时,实验的结果从另一个角度证明,如果兼顾收敛速度和解的品质这两个指标,单纯的遗传算法未必比其他搜索算法更优越,采用一些局部搜索性能较好的算法结合遗传算法,可以从两方面改善求解效果。     

POSITIVE INVERSION STRUCTURE OF THE CENTRAL STRUCTURE BELT IN TURPAN-HAMI BASIN

The central structure belt in Turpan-Hami basin is composed of the Huoyanshan structure and Qiketai structure formed in late Triassic-early Jurassic, and is characterized by extensional tectonics. The thickness of strata in the hanging wall of the growth fault is obviously larger than that in the footwall, and a deposition center was evolved in the Taibei sag where the hanging wall of the fault is located. In late Jurassic the collision between Lhasa block and Eurasia continent resulted in the transformation of the Turpan-Hami basin from an extensional structure into a compressional structure, and consequently in the tectonic inversion of the central structure belt of the Turpan-Hami basin from the extensional normal fault in the earlier stage to the compressive thrust fault in the later stage. The Tertiary collision between the Indian plate and the Eurasian plate occurred around 55Ma, and this Himalayan orogenic event has played a profound role in shaping the Tianshan area, only the effect of the collision to this area was delayed since it culminated here approximately in late Oligocene-early Miocene. The central structure belt was strongly deformed and thrusted above the ground as a result of this tectonic event.     

Geomechanical model for the post-Variscan evolution of the Permocarboniferous–Mesozoic basins in Northeast Germany

The Permocarboniferous basins in Northeast Germany formed on the heterogeneous and eroded parts of the Variscan orogene and its deformed northern foreland. Transtensional tectonic movements and thermal re-equilibration lead to medium-scale crustal fragmentation, fast subsidence rates and regional emplacement of large amounts of mostly acidic volcanics. The later basin formation and differentiation was triggered by reversals of the large-scale stress field and reactivation of prominent zones of weakness like the Elbe Fault System and the Rhenohercynian/Saxothuringian boundary that separate different Variscan basement domains in the area. The geomechanical behaviour of the latter plays an important role for the geodynamic evolution of the medium to large-scale structural units, which we can observe today in three dimensions on structural maps, geophysical recordings and digital models. This study concentrates on an area that comprises the southern Northeast German Basin, the Saale Basin, the Flechtingen High, the Harz Mountains High and the Subhercynian Basin. The presented data include re-evaluations of special geological and structural maps, the most recent interpretation of the DEKORP BASIN 9601 seismic profile and observations of exposed rock sections in Northeast Germany. On the basis of different structural inventories and different basement properties, we distinguish two structural units to the south and one structural unit to the north of the Elbe Fault System. For each unit, we propose a geomechanical model of basin formation and basin inversion, and show that the Rhenohercynian Fold and Thrust Belt domain is deformed in a thin-skinned manner, while the Mid-German Crystalline Rise Domain, which is the western part of the Saxothuringian Zone, rather shows a thick-skinned deformation pattern. The geomechanical model for the unit north to the Elbe Fault System takes account to the fact that the base of the Zechstein beneath the present Northeast German basin shows hardly any evidence for brittle deformation, which indicates a relative stable basement. Our geomechanical model suggests that the Permocarboniferous deposits may have contributed to the structural stiffness by covering small to medium scale structures of the upper parts of the brittle basement. It is further suggested that the pre-Zechstein successions underneath the present Northeast German basin were possibly strengthening during the Cretaceous basin inversion, which resulted in stress transfer to the long-lived master faults, as indicated for example by the shape of the salt domes in the vicinity of the latter faults. Contrary to this, post-Zechstein successions deformed in a different and rather complex way that was strongly biased by intensive salt tectonic movements.     

Numerical models of tectonic deformation at the Baltica–Avalonia transition zone during the Paleocene phase of inversion

Predictions from dynamic modelling of the lithospheric deformation are presented for Northern Europe, where several basins underwent inversion during the Late Cretaceous and Early Cenozoic and contemporary uplift and erosion of sediments occurred. In order to analyse the evolution of the continental lithosphere, the equations for the deformation of a continuum are solved numerically under thin sheet assumption for the lithosphere. The most important stress sources are assumed to be the Late Cretaceous Alpine tectonics; localized rheological heterogeneities can also affect local deformation and stress patterns. Present-day observations available in the studied region and coming from seismic structural interpretations and stress measurements have been used to constrain the model. Our modelling results show that lateral variation in lithospheric strength below the basin systems in Central Europe strongly controls the regional deformation and the stress regime. Furthermore, we have demonstrated that the geometry of the boundary between Baltica and Avalonia, together with different rheological characteristics of the two plates, had a crucial role on local crustal deformation and faulting regime resulting in the Baltica–Avalonia transition zone from the S–N Alpine convergence.     

震级加权四指标Blade算法及在地震带识别中的应用

Blade算法的产生是根据地震点的分布寻找地震断层，其优势在于能从较稀疏的点分布中找出线型条带模式，但不足的是完全不考虑地震的震级屑性。针对Blade算法的几个不足之处逐步改进，提出了震级加权四指标Blade算法。算法主要的改进体现在：①引入以震级为变量的权重函数，体现了高震级地震的控制作用，通过模拟与实例比较了三种权重函数的效果；②改进原方法中所挑出的Blade中心必须有地震点，引入四指标评价体系代替原方法的二指标评价体系，同时还根据指标值将挑选出的线型条带修正到更淮确的位置。将原算法与改进算法应用于华北地区4级以上的地震数据集以按寻地震带，结果表明，震级加权四指标Blade算法较Blade算法有显改进，取得了较好的应用效果。     

利用SV分量接收函数反演地壳横波速度结构

详细讨论了远震体波SV分量接收函数的特点及其在反演地壳S波速度结构中的优势．与径向接收函数类似，SV分量接收函数可通过对远震体波的SV分量直接反褶积P分量获得．研究分析表明:与径向接收函数相比，SV分量接收函数的振幅随震中距的变化更加稳定，波形简单且突出了对结构最敏感的PS转换波信息．理论数值实验显示:在反演地壳S波速度结构时，SV分量接收函数比径向接收函数具有更好的收敛性．作为实例，利用SV分量接收函数反演方法反演了海拉尔台下的S波速度结构．      

地震波研究://car

回顾了近4年来中国地球物理学家在地震波研究方面取得的主要进展. 分别简要地讨论了层状均匀介质、横向不均匀介质和多孔介质中的地震波传播，地震面波及波形反演，以及地震勘探、测井问题中的地震波研究方面取得的新成果. 指出当前地震波研究的重要课题是发展高效的数值方法，并利用该方法开展复杂介质中的地震波激发和传播，以及强地面运动的研究，为精细的地震危险分析与预测奠定基础.      

天然气水合物似海底反射层的全波形反演

建立了天然气水合物似海底反射层(BSR)研究的全波形反演方法. 这是一种将 水平层状弹性介质的反射共中心点道集转换为截距时间-水平慢度域的反演方法. 反演过程 中采用了全局搜索方法与非线性局部搜索方法. 分两步进行. 第一步是根据走时数据应用非 常快速模拟算法求得速度结构的长波长分量. 第二步，利用波形资料用共轭梯度法求得速度 的短波长扰动分量. 这样，最后反演得到的速度结构模型包含了长波长与短波长分量. 反演 中利用了多网格参数化技术. 日本东南海海槽双BSR的速度结构的反演表明，全波形反演是 天然气水合物BSR研究的重要手段之一.     

重磁遗传算法三维反演中高速计算及有效存储方法技术

将地下场源区域规则划分成很多小长方体单元，并且通过反演确定这些单元的物性变 化，勾画出场源的分布图像，这种方式逐步成为重磁反演，特别是三维反演的重要方向；遗 传算法等非线性技术进行该类反演将逐步成为发展趋势. 本文指出，在应用遗传算法进行该 类反演过程中，隐含着数据量较大时超常规的计算量，它已成为制约该类反演充分发挥作用 的瓶颈问题；同时，本文提出了针对性的分离并存储几何格架的计算策略、以及独特的几何 格架等效压缩存储技术，可以从根本上提高非线性反演计算速度，为该类反演的有效应用奠 定了坚实的基础.