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61.
地震预报是具高度复杂性的世界科学难题。以我国50余年实践中的问题为导向,以其揭示的自然现象为依托,从科学哲学及方法论视角,回顾经验归纳、还原论动力学、归纳-演绎和复杂动力系统等方法。通过汶川、唐山等震例探讨认识论因素在预测预报中的重要作用。进入地球系统科学新时期,建议以大陆变形复杂动力系统演化及其地震行为、经验与数值预测桥梁的图像(斑图)动力学作为地震预报的自然观和方法论。它们虽不完善,但更贴近大自然的整体性、进化性和非线性本质,又能包容连接多种思路与方法;既具前瞻性,又具可操作性;地震具可预测性,又具预测的不完全确定性;预测→预报→减轻灾害尚存在颇大的可创新空间。  相似文献   
62.
一种新的DEM填洼处理算法   总被引:5,自引:0,他引:5  
原利用DEM对洼地填充的算法处理,往往存在时效率低、计算耗时长等问题,本文拟介绍一种新的算法: 首先用一极大高程水面数据将原始地面DEM数据表面淹没,然后移除DEM上多余的水,最后得到的高程就是填洼处理的高程数据。通过时间复杂度和不同分辨率DEM数据洼地处理执行效率的度量和比较,结果发现这种新算法易于理解和实现,而且比原来的方法更快、更通用。  相似文献   
63.
在工程施工中,通常使用的是地方独立坐标系,各类工程施工图、成果图都要求使用地方平面坐标。如何实现GPS测量坐标到地方坐标的转换,一直是工程施工中的热点问题。本文介绍了从GPS定位坐标至平面坐标的两种转换模型,其中坐标网格法采用格网内插,算法设计简单,计算复杂度低,但精度会受内插网点的影响。在海南岛范围内精度较高,但沿海区域因无差值节点,需将格网外推。克里金内插法计算复杂度较高,但利用变形区域附近的点内插出畸变趋势,转换效果较好。通过对全岛范围约200个静态GPS点位、水准点位的转换结果进行比较,克里金转换算法可以满足一般工程测量的要求。  相似文献   
64.
Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour.  相似文献   
65.
The property of NP-completeness of topologic spatial reasoning problem has been proved. According to the similarity of uncertainty with topologic spatial reasoning, the problem of directional spatial reasoning should be also an NP-complete problem. The proof for the property of NP-completeness in directional spatial reasoning problem is based on two important transformations. After these transformations, a spatial configuration has been constructed based on directional constraints, and the property of NP-completeness in directional spatial reasoning has been proved with the help of the consistency of the constraints in the configuration.  相似文献   
66.
ABSTRACT

We compared the ability of two legend designs on a soil-landscape map to efficiently and effectively support map reading tasks with the goal of better understanding how the design choices affect user performance. Developing such knowledge is essential to design effective interfaces for digital earth systems. One of the two legends contained an alphabetical ordering of categories, while the other used a perceptual grouping based on the Munsell color space. We tested the two legends for 4 tasks with 20 experts (in geography-related domains). We analyzed traditional usability metrics and participants’ eye movements to identify the possible reasons behind their success and failure in the experimental tasks. Surprisingly, an overwhelming majority of the participants failed to arrive at the correct responses for two of the four tasks, irrespective of the legend design. Furthermore, participants’ prior knowledge of soils and map interpretation abilities led to interesting performance differences between the two legend types. We discuss how participant background might have played a role in performance and why some tasks were particularly hard to solve despite participants’ relatively high levels of experience in map reading. Based on our observations, we caution soil cartographers to be aware of the perceptual complexity of soil-landscape maps.  相似文献   
67.
According to Christopher Alexander’s theory of centers, a whole comprises numerous, recursively defined centers for things or spaces surrounding us. Wholeness is a type of global structure or life-giving order emerging from the whole as a field of the centers. The wholeness is an essential part of any complex system and exists, to some degree or other, in spaces. This paper defines wholeness as a hierarchical graph, in which individual centers are represented as the nodes and their relationships as the directed links. The hierarchical graph gets its name from the inherent scaling hierarchy revealed by the head/tail breaks, which is a classification scheme and visualization tool for data with a heavy-tailed distribution. We suggest that (1) the degrees of wholeness for individual centers should be measured by PageRank (PR) scores based on the notion that high-degree-of-life centers are those to which many high-degree-of-life centers point, and (2) that the hierarchical levels, or the ht-index of the PR scores induced by the head/tail breaks, can characterize the degree of wholeness for the whole: the higher the ht-index, the more life or wholeness in the whole. Three case studies applied to the Alhambra building complex and the street networks of Manhattan and Sweden illustrate that the defined wholeness captures fairly well human intuitions on the degree of life for the geographic spaces. We further suggest that the mathematical model of wholeness be an important model of geographic representation, because it is topological oriented, which enables us to see the underlying scaling structure. The model can guide geodesign, which should be considered as the wholeness-extending transformations that are essentially like the unfolding processes of seeds or embryos, for creating built and natural environments of beauty or with a high degree of wholeness.  相似文献   
68.
侯贵廷 《地学前缘》2005,12(4):347-351
根据Ramberg的纵弯褶皱粘性力学实验,在褶皱形态的分形分析基础上,利用分形理论和褶皱的流变学理论导出了褶皱的分数维(D)与岩层厚度(h)和粘度(μ)间的关系式,并探讨了褶皱复杂性对褶皱分数维的影响,从中获得有关复杂褶皱的流变学信息。影响分形褶皱复杂程度的因素很多,主要因素包括岩层的厚度和粘度。因此,对褶皱的分形测量和岩层厚度及粘度的分析,可以定量分析分形褶皱形成的流变机理。这一研究是褶皱的非线性流变学理论研究的一个尝试。  相似文献   
69.
干旱区绿洲景观尺度稳定性初步分析   总被引:14,自引:7,他引:7  
在景观尺度上,从绿洲景观多样性、景观廊道的复杂性以及土地利用及其生态环境效应等方面探讨了绿洲景观稳定性的内涵,并对新疆三工河流域绿洲进行实例分析和应用。结果表明:(1)人工绿洲景观的稳定需要绿洲景观的多样性逐渐降低和景观廊道的复杂性增加;但天然绿洲的稳定需要增加景观的多样性和景观廊道的复杂性。(2)人工绿洲景观稳定性还可从绿洲土地利用变化方面分析,绿洲土地利用变化是人类投入大量负熵的结果,投入的负熵越多,绿洲土地利用程度越高,越有利于绿洲从低级的亚稳定状态不断向高级稳定态发展,从而实现绿洲可持续发展。但人类的投入并不总是有利于绿洲的稳定,可用土地废弃比例的变化,说明人类投入对绿洲生态环境和稳定性造成的影响,土地废弃的比例越高,绿洲生态环境的质量也就越低,绿洲的稳定性也就越低。(3)通过绿洲景观多样性、景观廊道的复杂性和土地利用状况综合评判,1978~1998期间三工河流域绿洲景观及其各部分的稳定性逐步提高。  相似文献   
70.
简要介绍地震与爆炸的震源物理性质及地震波激发机制特征。利用地震观测波形直达纵横波震相能量释放的差异,在时间域引进标志事件震源性质的参量a。132个台站记录的22个不同震源类型事件的计算结果表明,a值具有震源性质依附效应,展现出在事件识别领域的应用前景。  相似文献   
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