动态地理现象的地图表示   总被引：2，自引：0，他引：2  

苗蕾  李霖 《测绘信息与工程》2004,29(3):20-22

就制图中表示动态现象的表达方法进行了总结,并指出应结合具体条件和用图目的来选择合适的表达方式.  相似文献   

Compositional Continuity and Discontinuity in the Horoman Peridotite, Japan, and its Implication for Melt Extraction Processes in Partially Molten Upper Mantle     

OBATA  MASAAKI; TAKAZAWA  EIICHI 《Journal of Petrology》2004,45(2):223-234

A hypothetical model is proposed to explain the origin of compositionaldiscontinuities in the layering observed in orogenic lherzolites.The observed collinearity of the whole-rock peridotite compositionsis best explained in terms of partial melting and melt segregation.The presence of chemical discontinuities implies that melt segregationincludes an abrupt and discontinuous process. A key conceptin the model is the topological transformation of melt geometryin partially molten rocks responding to the equality and inequalityof the fluid pressure and solid pressure, which may be realizedin a gravitational field. It is emphasized that the percolationthreshold is a critical boundary, beyond which a rapid microstructuralchange occurs in response to the change of local fluid pressure,thus causing a rapid increase of permeability. The model impliesthat the mode of melting is closer to batch melting than tofractional melting in the upper mantle. KEY WORDS: critical phenomenon; partial melting; percolation threshold; Horoman peridotite; melt segregation  相似文献   

自组织临界现象在地震空间演化特征上的应用研究          下载免费PDF全文

兰从欣  郭大庆  石特临  杨立明 《地震工程学报》1998,20(4):18-26,34

将自组织临界现象理论在地震预报领域作深入的应用研究,根据各量的物理含义重新讨论了在地震科学中的应用,并用重整化群方法对强震前中小地震强现象的临界点问题进行研究。  相似文献   

Double-thresholds in scour–fill processes and some implications in channel adjustment     

Jiongxin Xu 《Geomorphology》2004,57(3-4):321-330

Through an analysis of data collected from the Yellow River and its tributaries on the Loess Plateau of China, the phenomenon of double-thresholds in scour–fill processes of wide-range water-sediment two-phase flows has been shown. Thresholds located in non-hyperconcentrated flows may be called the lower threshold, and that in hyperconcentrated flows the upper threshold. This double-threshold phenomenon leads to complicated sediment transport behavior of heavily sediment-laden rivers. With an increase in suspended sediment concentration, the channel sediment delivery ratio increases initially and becomes higher than 1, followed by a decrease and finally becomes lower than 1 again.Controlled by the double-thresholds in the scour–fill processes, channel adjustment of the lower Yellow River is non-linear and complex. When the suspended concentrations were lower than the lower threshold or higher than the upper threshold, scour or bed downcutting was the dominant channel-forming process. Channel shape tends to be narrower and deeper, and the channel thalweg became more sinuous. When the suspended concentrations lay between the lower and upper thresholds, deposition of sediment was the dominant channel-forming process; channel shape tended to be shallower and wider, and channel thalweg became less sinuous.  相似文献   

雨滴谱式降水现象仪与人工观测结果的一致性分析     

吴宜  刘西川  孙宇  张军 《气象科技》2021,49(1):32-39

为验证雨滴谱式降水现象仪的测量性能,利用南京市气象局在江宁布设的PARSIVEL型雨滴谱式降水现象仪2018年1—11月期间的天气现象观测资料,重点分析了雨滴谱式降水现象仪对不同类型降水的测量性能。结果表明:①总体而言,雨滴谱式降水现象仪与人工观测具有良好的一致性,但是在降水时间、降水类型方面存在一定差异。②白天,人工观测的总降水时间明显高于仪器观测结果,主要原因在于人工观测有时会忽略降水间隙,而仪器可能会漏掉极微量降雨;人工观测的降水现象分类较粗,有时会忽略降水的精细变化,而仪器能够灵敏检测到降雨的短时变化、毛毛雨和雨的转换、降雨和降雪的转换等。③夜间,人工观测有时会忽略个别时次的毛毛雨或雨,而仪器容易漏测微量降水,大雨强条件下有时会把降雨误判为霰或雪,降水现象的判别算法仍需改进。  相似文献   

全数字摄影测量系统VirtuoZo的常见问题及其处理     

张秦罡  杨正银 《四川测绘》2009,32(5):210-212

本文通过对VirtuoZo系统使用过程中常见问题的分析，归纳、总结了问题出现的原因，并给出相应的解决方法，为今后更加及时、有效地处理VirtuoZo及其他全数字摄影测量系统出现的问题提供参考。  相似文献   

雅丹共基座现象对雅丹形态测量的影响   总被引：1，自引：0，他引：1       下载免费PDF全文

宋昊泽  穆桂金  林永崇  李文  唐自华  秦小光  赵雪  张磊  李康康 《干旱区地理》2020,43(1):48-55

雅丹形态特征吸引人们的长期关注，对其形态的定量描述至今仍讨论热烈且众说纷纭。通过对罗布泊地区风蚀地貌的野外调查和无人机测量，发现普遍存在雅丹共基座现象。分布在同一个基座体上的风蚀残丘称之为共基座雅丹，属于雅丹与基座体的复合。对共基座雅丹和基座体开展雅丹形态参数的测量及分析，结果表明：共基座雅丹长宽比比值集中分布于3∶1~5∶1区间，与鲸背状等流线型雅丹形态表现相似，显示单一风向侵蚀残留特征；雅丹共基座现象是风蚀切穿深一层抗风蚀相对较强的地层形成的风蚀垄岗现象，厚度不等的不同抗风蚀强度地层在垂向上交替出现和受单一风向的风蚀作用是形成该现象的重要因素；通过对雅丹共基座现象的阐释和定量分析，对完善雅丹形态测量、深化雅丹形态变化的理解以及认识差异性风蚀过程具有重要意义。  相似文献   

平原水库防渗膜下气胀现象产生机制现场试验研究   总被引：1，自引：0，他引：1  

袁俊平  曹雪山  和桂玲  王豹  刘英豪  殷宗泽 《岩土力学》2014,35(1):67-73

对库盘铺膜平原水库的气胀现象产生机制进行了理论探讨和现场试验研究。分析指出围坝填筑、库水位快速下降及地下水位上升等因素是导致膜下产生气胀的主要原因。在德州大屯水库进行了现场试验,模拟了不同膜上荷重、不同地下水位上升幅度和速率等试验工况,对膜下地层不同埋深处孔隙压力和膜下气胀现象进行了观测,分析了各因素对膜下气胀变化规律影响。试验结果表明,地下水位快速上升能够引起膜下气胀压力加大,地下水位上升幅度影响膜下气胀压力的大小;不同地下水位上升速率对膜下气场影响较小,在膜上设置一定荷载可较好地防止膜顶托或胀破。  相似文献   

Experimental evaluation of dynamic characteristics of seesaw energy dissipation system for vibration control of structures          下载免费PDF全文

Jae‐Do Kang  Hiroshi Tagawa 《地震工程与结构动力学》2014,43(12):1889-1895

Seesaw energy dissipation system (SEDS), a vibration control system used to provide enhanced seismic protection, has been proposed and investigated numerically. Because of its complicated arrangement, verification experiments are necessary to demonstrate the SEDS damping capacity. This paper presents the results of experimental investigation of the SEDS using fluid viscous dampers. Free vibration tests are conducted to demonstrate the SEDS damping capacity. Results of the free vibration test show that the SEDS has sufficient damping capacity for reduction of the seismic response of the frames. Parametric experimental investigations of the SEDS were conducted, the results of which demonstrate the effects of the system parameter on the damping capacity. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Spherical pattern of tide-isostasy model and its application     

YANG Dong-hong  WANG Ye  YANG Xue-xiang 《世界地质(英文版)》2004,7(2)

In this paper, a calculation formula on spherical pattern of tide-isostasy model is established. The calculation indicated that for the oceanic crust plate which central angle is over 90°, a huge value (its equivalence is 108 N) of accumulative force moment in the crustal isostatic movement caused by tide can trigger off relative motion of plate,resulting in earthquake and volcanic eruption. The seismic wave features during the year 2001-2004 is an obvious example. The paracycles, i.e. 4, 12, 60, 36, 243, 372 and 396 years of tidal fluctuation can provide an explanation for some respective natural disasters. For example, La Madre paracycle about 60 years corresponds to the global disasters,earthquake and typhoon disasters.  相似文献