基于对称性的委内瑞拉及周边地区M_W≥6.0地震趋势判断及与地球自转关系分析          下载免费PDF全文

孟庆彬  延军平  芦佳玉 《地震工程学报》2018,40(5):1061-1067

在全球化的大背景下,重大自然灾害发生的频率不断加快,其危害对人们的生产生活造成了严重的威胁。地震灾害是重大自然灾害之一,发生的频率虽然不高,但造成的人员伤亡和经济损失十分巨大。对地震进行趋势判断,其理论和现实意义重大。文章运用三元、四元、五元可公度计算来预测委内瑞拉及周边地区近30多年M_W ≥ 6.0地震信号的强弱,利用蝴蝶结构图和可公度结构系加强对时间对称性的分析,再通过震源的经纬度迁移和空间迁移规律,本文创造性地分析了该地地震与地球自转加速度的关系。结果得出：（1）委内瑞拉及周边地区发生M_W ≥ 6.0地震的时间上在 2018年信号最强,2017和2019年较强。（2）空间上在10°N—11°N,63°W—65°W之间地震可能性最强。（3）委内瑞拉及其周边地区M_W ≥ 6.0地震与地球自转速度的转折变化有密切关系,未来可通过其变化规律帮助分析地震发生趋势。本文可为地震灾害的趋势判断研究提供一定的参考,为后续研究工作带来一些启示。  相似文献   

Symmetry distribution of cities in China   总被引：1，自引：0，他引：1  

YE Danian  XU Wendong  HE Wei  LI Zhe 《中国科学D辑(英文版)》2001,44(8):716-725

The authors of this paper induced five principles of geographical symmetry based on the space distributions of cities and towns in China. There is a symmetry distribution of cities and towns. The symmetry characteristics are the following: (i) the average coordination number of the cities (including large cities, medium cities and county towns) is 6 (i.g. rotation symmetry); (ii) the distribution of large and medium cities are shown to be the latticework in which two directions are parallel to two main tectonic ones in China, respectively; (iii) the distribution of county towns of a province is also shown to be the latticework in which two directions are parallel to two tectonic ones in this province (i. g. two-dimensional translation) and (iv) the concentric circle distribution of cities (CCDC) is centered round a large city (i. g. rotation symmetry).  相似文献   

用球函数展开法求解轴对称稳恒磁场     

丁世荣 《地球科学与环境学报》1997,(4)

本文用球函数展开法推导出计算轴对称三维稳恒磁场矢势的公式，应用该公式既能计算电流分布区域外部的磁场，又能计算电流分布区域内部的磁场。最后给出了应用文中公式求解轴对称稳恒磁场的具体例子。  相似文献   

赣湘两省区域发展的地理不对称研究     

万炜  ;叶大年 《云南地理环境研究》2014,(3):46-50

根据地理对称原理分析了江西、湖南两省在各自然地理要素以及城市分布方面的对称性,并在此基础上研究评价两省在区位条件以及区域发展方面的非对称性。最后首次就两省地理环境对称性及区域发展非对称性的原因进行探究。研究结果表明：江西与湖南在相同区域地质构造的背景下引发了两省在地质、矿产、地貌、水文等自然地理要素对称;自然地理要素的对称导致了两省城市、铁路分布的对称;而历史时期不同的发展机遇引起两省在人才地理方面的不对称、不同的发展环境引起两省在文化地理方面的不对称、人为的政治经济活动引起两省在经济地理方面的不对称。以上三个因素是最终导致赣湘两省区域发展差异的主要原因。  相似文献   

有向加权型城市网络的探索性分析   总被引：4，自引：1，他引：3  

刘铮  王世福  赵渺希  吴康 《地理研究》2013,32(7):1253-1268

鉴于城市网络已成为城市与区域研究中的学术热点,研究引介了城市联系中无向加权网络的概念、特征、计算方法,在此基础上与无向加权网络进行比较,并以中国36 座副省级以上城市的城市间网络地图关注度为研究素材,从实证案例的角度分析无向加权网络与有向加权网络在城市网络分析方面的差别。实证研究结果显示：在网络的结节性方面,互联网异地城市之间关注度与航空流量结节性具有强相关性,异地之间的城市地图查询在一定程度上表征了城市间出行期望,互联网关注中部分城市成为典型的流入地,而华北、西北等地省会城市成为典型的流出地;在多值网络的链接方面,研究对城市网络这一复杂结构系统的流,实现了“流向”与“流量”的同步分析,互联网中城市间关注强度的“出”“入”反映了城市间吸引力系的非均衡性特征。总体而言,从互联网地理学的角度为城市网络分析方法提供一个新的切入点与数据来源,实现对有向加权网络的探索性分析,在计算方法上有向加权网络在分析城市体系中节点城市的职能与节点间的相互关系方面有更大的优势。  相似文献   

THE STABILITY OF THREE CLASSES OF STEADY BASIC STATES IN THE TWO-DIMENSIONAL COMPRESSIBLE ATMOSPHERE^*          下载免费PDF全文

Zhou Jiangxing  Ding Yihui  Liu Yimin 《Acta Meteorologica Sinica》1998,12(3):321-333

In this paper,the stability of three classes of steady basic states in the two-dimensional compressible adiabatic and non-dissipation atmosphere is discussed,and the following property is exactly demonstrated that the stability of these basic states is decided by their engine matrix A in two ways:(a)the basic states are stable if A is positively definite in set,and (b) the basic states are unstable if A is negatively definite in set.  相似文献   

Neotectonic evolution of the northern Laborec drainage basin (northeastern part of Slovakia)   总被引：1，自引：0，他引：1  

Rastislav Vojtko  L'ubomír PetroAlexandra Benová  Ján BónaJozef Hók 《Geomorphology》2012,138(1):276-294

This study investigates the influence of neotectonic activity on river and basin patterns in a mountainous area located in the northeastern part of the Carpathian Belt (the Laborecká vrchovina and Bukovské vrchy Mts. in eastern Slovakia). This area evolved within the accretionary wedge of the Carpathians during the Neogene, and it was alsowas affected by Middle to Late Miocene thrusting of the External Carpathians. Morphometric analysis, longitudinal and transverse river valley profiles, analysis of basin and valley symmetries, and investigation of alluvial terraces were carried out on the northern Laborec River and its tributaries. This was done to detect a possible relationship between their river courses and any ongoing neotectonic activity, which is otherwise difficult to detect by methods of structural geology because of the poorly exposed area.The general topography of the basin is characterized by a stepwise inclination to the SW as a result of differential uplift and subsidence. The reorganization of the river network in the Laborec drainage basin was influenced by tectonic activity along the NE-SW up to N-S fault structures during the neotectonic phase (Pliocene-Quaternary). The movement along these fault structures is predominantly normal to transtensive. The obtained data assumes that the region is under approximately NE-SW oriented S_H compression and NW-SE trending S_h tension. The Laborec drainage basin is characterized by a very high degree of asymmetry that sharply increases from the upper to the lower courses of the river. The right-bank tributaries of the Laborec River are < 12 km in length; however, the left-bank tributaries such as Vydraňka, Ol'šava, Výrava, Udava, and Cirocha Streams are up to 50 km long with a high potential of headward erosion and capturing. The valley asymmetry is also very variable in the upper and lower portions of the basin. Based on these presented results, the ancient river thalweg was located along the axis of the Hostovice-Habura depression, and it was captured by the Ol'šava, Výrava, and Udava Streams. The asymmetric pattern of the drainage basin is the result of active tectonics, the continual subsidence of the Transcarpathian Basin, and by the uplift of the Laborecká vrchovina and Bukovské vrchy Mts. These events caused rejuvenation of the headward erosion of streams in the southern part. Favorable lithology was also essential in the process of river capture.  相似文献   

基于梯度对称性的无人机影像电力线自动提取方法     

杨亮  李辉芳  江万寿  谭波  周伟才  刘丙财 《地理信息世界》2017,24(2)

针对航空影像电力线提取过程中,背景线特征(电力杆塔、道路和植被等)干扰问题和电力线提取准确性问题,提出一种基于梯度对称性的电力线特征判别方法。采用Line Segment Detector(LSD)算法,对航空影像进行线特征提取;基于电力线附近梯度的对称性特征,实现从大量线段中准确筛选电力线段;采用缓冲区序列化线段连接算法,实现了电力线的自动连接。通过实验证明,提出的方法能够排除背景干扰并准确、完整地提取整条电力线。  相似文献   

Seismic waves in stratified anisotropic media - II. Elastodynamic eigensolutions for some anisotropic systems   总被引：2，自引：0，他引：2  

Gerard J. Fryer  L. Neil Frazer 《Geophysical Journal International》1987,91(1):73-101

  相似文献   

The Lissajous transformation III. Parametric bifurcations     

Bruce R. Miller 《Celestial Mechanics and Dynamical Astronomy》1991,51(3):251-270

We examine a parametric family of cubic perturbed 1-1 resonant harmonic oscillators with an aim to understanding the phase flows of the reduced system. Variation of the parameters leads the system through five bifurcations of different types. Some bifurcations are due to passage through cases of discrete symmetry or integrability. A conjecture correlating degenerate equilibria in reduced systems with integrability is modified and reinforced.  相似文献