土石坝地震响应的非线性剪切条模型与对比分析     

李湛  栾茂田 《地震工程与工程振动》2005,25(5):41-49

对一维剪切条计算模型进行改进,提出了土石坝非线性地震反应的简化计算方法。首先将坝体沿坝高离散为一系列的具有不同剪切刚度与阻尼比等参数特性的层状体系,建立了各层的振动控制方程及其边值条件,进而采用数学物理方程方法进行了求解,确定了体系的振动特性,并根据振型叠加原理和Duhamel积分确定了坝体地震反应的线弹性解。采用等价线性化方法考虑坝料的动力非线性性质,通过对线弹性地震响应的反复迭代计算,使得各层土的模量和阻尼比与其相应的剪应变水平相协调,确定出与非线性坝体系统相等效的线性解答,并将所得到的地震响应作为非线性地震响应的近似解。最后,以均质坝和心墙坝作为算例进行了具体的数值计算,将所得结果与有限元数值解进行对比分析,论证了所提方法的适用性和合理性。  相似文献   

地震预测中的电磁卫星   总被引：7，自引：0，他引：7  

卓贤军  赵国泽  王继军  汤吉  詹艳 《大地测量与地球动力学》2005,25(2):1-5

地震孕育和发生过程中往往会产生低频电磁波(300kHz以下)。监测低频电磁信号异常,已成为一种重要的地震短临预测方法。简要介绍了卫星观测到的震前电磁信号异常现象,分析了在地面进行电磁观测存在的局限性和通过地震电磁卫星进行电磁观测的优势。同时。通过比较已有的电磁卫星。提出了发展中国地震电磁卫星的一些基本设想。  相似文献   

Groundwater response to dual tidal fluctuations in a peninsula or an elongated island     

Quanrong Wang  Hongbin Zhan  Zhonghua Tang 《国际地质力学数值与分析法杂志》2013,37(15):2456-2470

Groundwater flow in a peninsula or an elongated island is influenced by tidal fluctuations on both sides of the peninsula or island, which is named as dual tidal fluctuations. In this study, semianalytical solutions of transient groundwater flow in response to dual tidal fluctuations in an aquifer–aquitard system were presented for cases with and without the aquitard storage. These solutions were first derived using the Laplace transform and subsequently computed by the Fourier series numerical inverse Laplace transform. The derived solutions were found to agree very well with the results of numerical simulations by MODFLOW. The solution ignoring the aquitard storage approached the quasi‐steady state solution quickly when the mean sea level initial condition was used. The solutions with and without the aquitard storage were nearly the same at the early time and were separated from each other during the intermediate time, and the difference of solutions became constant at late time for small aquifer/aquitard storativity ratio and large tidal frequency. The propagation bias, which is the departure from the theoretical ratio of tidal attenuation to tidal lag, was enhanced not only with increase of the dimensionless specific leakage (aquitard/aquifer hydraulic conductance ratio) but also with decrease of the aquifer/aquitard storativity ratio and with the increase of the dimensionless tidal frequency. The solution with the aquitard storage was more sensitive to these three parameters. The newly developed solutions were capable of handling realistic initial conditions that might be approximated by piecewise linear functions. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Early Silurian ‘algal meadows’ of Anticosti Island,eastern Canada: an analogue to modern sea grass meadows?     

Yi Wang  Jisuo Jin  Renbin Zhan  Paul Copper 《Geology Today》2014,30(2):67-70

In modern marine ecosystems, sea‐grass and chlorophyte meadows play an important ecological role by serving as a carbon sink. Despite their generally limited areal distribution, the high productivity of sea‐grass meadows makes them an efficient assimilator of CO₂. During the early Palaeozoic, complex life was virtually confined to the marine environment, with algae being one of the common carbon‐fixers, alongside abundant calcifying cyanobacteria, rhodophytes, chlorophytes and charophytes, as well as non‐skeletal dinoflagellates and acritarchs. Fossil and molecular data indicate that marine thallophytic algae first appeared in the Early Proterozoic and became widespread in the Palaeozoic, although their fossil record is sporadic because of their soft‐bodied nature; in the absence of angiosperm sea grass and mangroves and poorly understood phytoplankton biomass, thallophytic algae were probably major primary producers. In this article, we suggest that thallophytic algae may have played a significant role as a carbon sink in the Early Silurian, analogous to modern sea‐grass meadows or kelp forests, based on the well‐preserved Early Silurian thallophytic algal meadow from Anticosti Island, eastern Canada.  相似文献   

1965-2010年7-9月影响中国的热带气旋降水变化趋势分析   总被引：2，自引：2，他引：0  

刘通易  吴立广  张娇艳  任福民 《气象学报》2013,71(1):63-75

利用中国气象局逐日台站降水和上海台风研究所最佳台风路径等资料,对1965—2010年夏季(7—9月)影响中国热带气旋降水的变化趋势及影响机制进行了分析。热带气旋降水主要影响中国东部和南部,夏季平均的热带气旋降水由沿海向内陆,由东南向西北递减。自1965年以来,夏季影响中国的热带气旋降水呈现华东及东南沿海增多,华南沿海、海南岛以及西南地区减少的变化趋势。分析发现,一方面夏季西北太平洋副热带高压加强西伸,导致同期中国东部地区上空水汽辐合增强;另一方面热带气旋的引导气流发生变化,使夏季热带气旋盛行路径由南海向东亚沿岸偏移,这两个因子的共同作用致使影响中国的热带气旋降水发生变化。  相似文献   

广西气象业务传输质量统计及查询系统的设计与实现     

黄志  詹利群 《广西气象》2013,(4):101-102

采用IIS和基于Visual studio.Net建站模式,辅以Linux＋MySql数据库作为后台支撑,嵌入功能强大的FusionCharts图片显示控件兼以JavaScript实现界面特效,使得网站显示独具特色,有效减轻了日常值班的传输监控负担,实现各项气象实时资料传输完成实效的统计汇总分析.  相似文献   

Cloning, expressing, and hemolysis of tdh, trh and tlh genes of Vibrio parahaemolyticus   总被引：1，自引：0，他引：1  

Yonggang Zhao  Xiaoqian Tang  Wenbin Zhan 《中国海洋大学学报(英文版)》2011,10(3):275-279

Vibrio parahaemolyticus (VP) is one of the pathogenic vibrios endangering net-cage cultured Pseudosciaena crocea,Fennerpenaeus chinensis, and shellfish in coastal areas of China. Several types of hemolysins produced by Vp have been characterized as major virulence factors.They are thermostable direct hemolysin (TDH),TDH-related hemolysin (TRH) and thermolabile hemolysin (TLH). In this study, we cloned tdh, trh, and tlh genes from the genome DNA of VP by polymerase chain reaction (PCR).We ligated the three genes into prokaryotic expression vector pET-28a (+),and transformed the recombinant plasmids into Es-cherichia coli BL21 (DE3). The expression of recombinant proteins was induced by isopropyl-β-D-thiogalacto-pyranoside (IPTG). The recombinant proteins were expressed in a form of inclusion bodies and thus purified with Ni-NTA affinity chromatography. Western blotting results showed that recombinant proteins,TDH, TRH and TLH, could be recognized by rabbit anti-VP serum. The three purified proteins were renatured by gradient dialysis.The renatured proteins exhibited hemolytic activity except for TLH in the presence of phosphatidylcholine. These results not only are helpful for better understanding these genes’ functions under a single factor level, but also provide evidence for VP vaccine engineering.  相似文献   

德州市建设用地节约集约度定量分析          下载免费PDF全文

唐丽静  李贻学  王新志  杨文治 《山东国土资源》2011,27(6):44-47

为新一轮土地利用总体规划修编中制定合理的城乡建设用地统筹政策措施,在建设用地现状分析的基础上,利用因子分析方法,对德州市建设用地节约集约度进行了定量分析。  相似文献   

古文献在江西省气候变化研究中的运用          下载免费PDF全文

辛佳洁  占明锦  胡菊芳  赵冠男  王怀清 《气象与减灾研究》2021,44(3):159-163

中国五千年悠久历史文化孕育出了全球独有的古文献资料,而江西自古以来就是文化和农业大省,有关气象灾害的古文献记录较为丰富.江西省气象局搜集省内地方古文献资料,整理得到了《江西省地方志气象资料集》和《江西省地方志气象灾害记载翻译资料汇编》,为进行江西省气候变化研究打下了良好基础,并较好地解决了古文献中未对气象灾害进行定量的问题.目前对鄱阳湖流域千年旱涝序列的研究已经取得一系列成果,说明运用地方古文献研究江西省气候变化是可行的.  相似文献   

赣州、吉安综合防灾减灾能力现状及对策建议   总被引：1，自引：0，他引：1       下载免费PDF全文

詹丰兴  唐春燕  单九生  殷剑敏  许彬  陈庭甫 《气象与减灾研究》2017,40(2):153-158

在对赣州、吉安两市进行充分调研的基础上,较为全面地概括了两市"十二五"期间综合减灾工作在领导机制和工作机制构建、机构设置和人员配备、监测预警能力和救援抢险能力建设、防灾工程设施建设以及灾害救助和科普宣教等方面取得的成效,分析了存在的主要问题。立足于保障经济社会可持续发展全局,从工作层面提出了完善防灾减灾体制机制、加强专业救援队伍和基层信息员队伍建设、强化防灾减灾工程性措施、进一步加大防灾减灾科普知识宣传和加强综合减灾"十三五"规划编制等建议;从技术层面提出了加强灾害监测预报预警和信息发布能力建设、加快灾情统计指标研制及加大现代科技手段在灾情调查和统计中的运用等对策。  相似文献