A FINITE ELEMENT MODEL FOR SEISMICITY INDUCED BY FAULT INTERACTION     

Chen Huaran )  Li Yiqun )  He Qiaoyun )  Zhang Jieqing )  Ma Hongsheng )  Li Li ) Earthquake Administration of Tianjin Municipality  Tianjin  China Center for analysis  prediction  CEA  Beijng  China 《大地测量与地球动力学》2003,23(Z1)

1　IntroductionInsouthwestregionofChina ,strongearth quakesarefrequentandinteractional.This paperpersentsafiniteelementmodelforstrongearth quakesinthisregion ,whichmayprovideatheoreti calbasisforearthquakesprediction .Amongstudiesonsimplifiedmodelthatsimu latedseismicactivities,thestudiesonspringslipmassandautomaticmachinemodelarethemostrep resentative .Althoughthiskindofcalculationissim pleandhasconsideredthecrucialfactors,thusithelpsunderstandcomplexphysicalprocessofseismicactivities,itisov…  相似文献   

Shifting from homogeneous to heterogeneous surfaces in estimating terrestrial evapotranspiration: Review and perspectives     

Yuanbo LIU  Guoyu QIU  Hongsheng ZHANG  Yonghui YANG  Yinsheng ZHANG  Quan WANG  Wenzhi ZHAO  Li JIA  Xibin JI  Yujiu XIONG  Chunhua YAN  Ning MA  Shumin HAN  Yifan CUI 《中国科学:地球科学(英文版)》2022,65(2):197-214

Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation.  相似文献   

Effects of surface source/sink distributions on the flux–gradient similarity in the unstable surface layer     

Qing Huo  Xuhui Cai  Ling Kang  Hongsheng Zhang  Yu Song 《Theoretical and Applied Climatology》2015,119(1-2):313-322

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液舱三维晃荡运动二阶共振理论解及特性分析     

杨小岩  张洪生  吴鹏飞 《海洋工程》2015,33(3):71-79

从无旋运动的理论出发,并利用微扰法,推导了液舱三维晃荡运动二阶共振问题的理论解。考虑纵荡和横荡运动情况,对液舱三维晃荡二阶共振问题进行了分析。当两个晃荡方向的和频(即其外部激发频率的和)或差频(即其外部激发频率的差值)等于液舱固有频率时,二阶共振发生;当某一晃荡方向(横荡或纵荡)外部激发频率与另一晃荡方向(纵荡或横荡方向)液舱某一固有频率的和或差值等于液舱另一固有频率时,二阶共振也会发生。进一步研究了各个二阶共振激发频率下水深变化对晃荡振幅的影响。结果表明,对于两个晃荡方向外部激发频率的和频和单一晃荡方向(纵荡或横荡)某一个激发频率与另一晃荡方向(横荡或纵荡)某一个属于奇模的固有频率的和频所引发的共振情况,水深变化对共振振幅大小的影响比较大;而对于相应差频所引发的共振情况,水深变化对共振振幅大小的影响比较小。  相似文献   

云南地区强震前孕震系统的非线性阶段   总被引：6，自引：4，他引：2  

蔡静观  许昭永 《地震研究》1993,16(4):329-337

本文以降维减熵增能的地震学方法，讨论了强震前复杂孕震系统的非线性阶段，云南地区１９７６年以来６级以上的强震震例表明，强震前复杂孕需系统的非线性阶段是普通存在的。但从不同震例。不同方法反映出来的非线性阶段起始时间是有差异的，本文进行了综合判断的尝试，得出孕震系统在强震前１－３年进入非线性阶段。结果还表明，蠕变曲线和累计频度的速率增加比具有普适的特点，前者为２．４左右，后者为１．７左右。  相似文献   

沙尘天气过程起沙特征的观测试验和参数化研究进展   总被引：3，自引：0，他引：3  

张宏升  李晓岚 《气象学报》2014,72(5):987-1000

沙尘天气过程研究中,起沙过程是沙尘传输和沉降的基础,沙尘模式中的起沙参数化方案决定了能否准确模拟和预报沙尘天气。试验观测和数值模拟是研究起沙过程的重要途径。基于风蚀起沙的物理机制,总结了起沙机制和起沙特征的研究成果,介绍了风蚀起沙的主要影响因子,回顾了起沙关键参数（临界起沙摩擦速度（u*t ）或临界起沙风速（Ut ）、水平跃移沙尘通量（Q）和起沙通量（F））的试验观测及其沙尘模式应用中的参数化方案,并讨论了不同起沙参数化方案的应用与校验。同时,针对目前研究中存在的问题和今后可能的研究方向提出建议。  相似文献   

山东省平邑左庄石膏矿区非采空致塌机理与治理方法     

王祥永  赵宏生  李文君  许艳娟  方传昌  王德鹏 《山东地质》2012,(6):20-24

平邑左庄石膏矿区曾发生过3次地面塌陷,但井下实地调查发现,该矿区地面塌陷并非地下采空塌陷波及地表后而引发的地面塌陷。根据矿区地质环境条件、采矿方法及井巷工程布置等因素,分析认为地面塌陷原因是矿山布置的第一开采中段未预留出足够的顶柱厚度,致使井下回采时揭穿矿房顶柱接触到上覆第四纪松散盖层,第四纪孔隙水携带泥砂泄入矿坑发生潜蚀作用,在矿房顶柱与第四纪松散盖层之间形成“天窗式”砂漏,第四纪松散盖层中逐渐形成土洞,土洞扩大并塌陷后引发地面塌陷。  相似文献   

Soil Moisture Effects on Sand Saltation and Dust Emission Observed over the Horqin Sandy Land Area in China          下载免费PDF全文

LI Xiaolan  ZHANG Hongsheng 《Acta Meteorologica Sinica》2014,28(1):444-452

In this study, the effects of soil moisture on the processes of sand saltation and dust emission are investigated using observations from three dust events in 2010 over Horqin Sandy Land area. The minimum friction velocity initiating the motion of surface particles, namely threshold friction velocity, is estimated to be 0.34, 0.40 and 0.50 m s^-1, under the very dry, dry and wet soil conditions, respectively. In comparison with the observations during the dust events under the very dry and dry soil conditions, the dust emission flux during the wet event is smaller, but the saltation activities of sand particles (d ≥ 50 μm) are stronger. The size distributions of airborne dust particles (0.1 ≤ d ≤ 20 μm) show that the finer dust particles (0.1 ≤ d ≤ 0.3 μm) have a secondary peak under dry soil conditions, while they are absent under wet soil conditions. This suggests that the surface soil particle size distribution can be changed by soil moisture. Under wet soil conditions, the particles appear to have larger size, and hence more potential saltating particles are available. This explains the phenomena of stronger saltation processes observed under wet soil conditions.  相似文献   

新疆西天山霍尔果斯岩浆岩带成矿地质条件分析          下载免费PDF全文

张全  高洪生  胡醒民 《地质找矿论丛》2014,29(3):336-343

新疆霍尔果斯岩浆岩带广泛出露晚石炭世—早白垩世侵入岩,文章通过对岩带中晚石炭世混源序列含斑含黑云母二长花岗岩的岩石学、岩石化学、岩石地球化学等特征进行分析与对比研究,并结合其成矿构造背景、地质建造、岩浆活动、岩石类型、蚀变矿化等特征,确定了霍尔果斯岩带内的找矿靶区。  相似文献   

1998年夏季青藏高原辐射平衡分量特征   总被引：49，自引：1，他引：48  

卞林根  陆龙骅  逯昌贵  陈彦杰  高志球  刘辉志  张宏升  陈家宜 《大气科学》2001,25(5):577-588

利用1998年夏季第二次青藏高原气象科学试验(TIPEX)获得的改则、当雄和昌都三个热源观测站的数据和相关资料,统计和分析了高原夏季辐射平衡分量和热源强度的变化特征.结果表明高原地面总辐射平均强度以西部最强,中部次之,东部最小.6月中旬后随着雨季到来,地表反射率均有所降低,中部和东部的辐射强度明显减弱,西部雨季降水和云量都比较少,辐射强度变化不明显.高原中部和东部的净辐射在6月中旬有明显的突变现象,西部突变期出现在7月上旬,以中部的辐射加热强度最大,东部次之,西部最小.湿期随着地面长波辐射的减少,热源强度明显增大.  相似文献