太湖水体理化指标在夏季短时间尺度上的分层及其控制因素   总被引：5，自引：4，他引：1  

赵林林  朱梦圆  冯龙庆  刘笑菡  朱广伟  陈元芳  秦伯强 《湖泊科学》2011,23(4):649-656

通过连续9d(2010年7月24日至2010年8月1日)对太湖水体理化指标垂向分层的高频率观测,揭示太湖多指标垂向分层规律.观测表明:(1)太湖中各水质指标频繁出现分层现象,但不稳定;(2)分层的主要控制因素包含气温的日变化、蓝藻水华堆积与风浪扰动等;(3)气温和太阳辐射日变化影响水温分层,水温垂向变幅可达3.94℃,...  相似文献   

基于GPS-RTK技术的波浪能发电装置结构动态位移监测及滤波方法          下载免费PDF全文

郭欣然  陶涛  杨毅  刘石 《海洋技术学报》2023,(4):51-59

利用全球定位系统实时差分技术（Global Positioning System Real-Time Kinematic,GPS-RTK）对波浪能发电装置进行结构变形监测得到的信号会存在噪声。针对这个问题,本文提出一种结合巴特沃斯（Butterworth）滤波器和自相关函数经验模态分解（Empirical Mode Decomposition,EMD）的滤波降噪算法,利用动态位移仿真信号进行了实验验证。结果表明：该滤波算法能够有效降低装置动态位移监测数据中噪声的影响,利用滤波算法对仿真信号进行降噪处理之后,可以提取出信号中包含的结构固有频率。  相似文献   

波浪作用下斜坡上单桩周围海床孔隙水压力响应特性试验研究     

郑余伟  程永舟  李典麒  黄筱云  吕行 《海洋通报》2023,(3):343-351

单桩基础周围斜坡海床中的波致孔隙水压力响应与纯斜坡海床存在较大差异。为了解不同波高、波周期条件下,单桩基础周围波浪传播变形及其对斜坡海床孔压振荡响应的影响,在波浪水槽末端铺设了长6 m、坡度1∶16的斜坡砂床进行试验。通过改变桩身位置和波浪参数,测量斜坡段各处波面形态,采集单桩周围孔隙水压力,分析了桩身位置及波浪参数对斜坡海床孔压响应的影响。结果表明：相同入射波条件下,随距坡脚水平距离增加,波高、近底流速和桩周孔隙水压力幅值都随之增大;桩周孔隙水压力幅值分布规律为：桩前孔压幅值明显大于桩侧与桩后孔压幅值。当Keulegan-Carpenter数大于6时,随着波高和波周期增大,马蹄涡产生的负压区使得桩侧海床孔隙水压力与纯斜坡海床孔隙水压力差值迅速增加。  相似文献   

瑞利波"之"字形频散的正演及实践对比   总被引：3，自引：1，他引：2  

杨天春  易伟建  吴奇 《煤田地质与勘探》2005,33(3):71-73

瑞利导波一般存在多个模式。假定检波器在各频率上接收到的信号为位移最大的那个导波模式,由此可得到一条理论频散曲线。将理论曲线与实测成果进行对比,其吻合程度很好。由此可说明,所用正演方法是正确可行的。  相似文献   

Reduction of pounding effects in elevated bridges during earthquakes     

Robert Jankowski  Krzysztof Wilde  Yozo Fujino 《地震工程与结构动力学》2000,29(2):195-212

Pounding of adjacent superstructure segments in elevated bridges during severe earthquakes can result in significant structural damage. The aim of this paper is to analyse several methods of reduction of the negative effects of collisions induced by the seismic wave propagation effect. The analysis is conducted on a detailed three‐dimensional structural component model of an isolated highway bridge. The results show that the influence of pounding on the structural response is significant in the longitudinal direction of the bridge and significantly depends on the gap size between superstructure segments. The smallest response can be obtained for very small gap sizes and for gap sizes large enough to prevent pounding. Further analysis indicates that the bridge behaviour can be effectively improved by placing hard rubber bumpers between segments and by stiff linking the segments one with another. The experimental results show that, for the practical application of such connectors, shock transmission units can be used. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

A rational method for development of limit state for liquefaction evaluation based on shear wave velocity measurements     

C. Hsein Juang  Caroline J. Chen 《国际地质力学数值与分析法杂志》2000,24(1):1-27

This papers presents a new approach for developing a limit state for liquefaction evaluation based on field performance data. As an example to illustrate the new approach, a database that consists of, among many other features, in situ shear wave velocity measurements and field observations of liquefaction/non‐liquefaction in historic earthquakes is analysed. This database is first used to train a neural network to classify liquefaction/non‐liquefaction based on soil resistance parameters and load parameters. The successfully trained and tested neural network is then used to establish a limit state, a multiple dimension boundary that separates ‘zone’ of liquefaction from ‘zone’ of non‐liquefaction. The limit state yields cyclic resistance ratio for a given set of soil resistance parameters. Examination of all cases in the database show that the developed limit state has a high degree of accuracy in predicting the occurrence of liquefaction/non‐liquefaction. The developed neural network model can accurately predict the cyclic resistance ratio of soils. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

IMPROVED FORECASTING OF COLD AIR OUTBREAKS OVER SOUTHERN CHINA THROUGH OROGRAPHIC GRAVITY WAVE DRAG PARAMETERIZATION     

钟水新  陈子通  王刚  蒙伟光  黄荣 《热带气象学报(英文版)》2016,22(4):522-534

The parameterization of gravity wave drag induced by sub-grid scale orography(GWDO), which has been used in the regional model based on the Global/Regional Assimilation and Prediction System for Tropical Mesoscale Model(GRAPES_TMM), is extended to include the effect of mountain flow blocking drag(MBD). The extended scheme is evaluated against non-GWDO parameterization, including a cold air outbreak over southern China and a monthly verification in February 2012. The experiment results show that the GWDO and MBD parameterization both improves the forecasting of the cold air outbreaks over southern China, as well as alleviations of system bias of GRAPES_TMM.(1) The extended scheme alleviates the strong southerly wind and high surface temperature simulation during the cold air outbreak, especially over northern Guangxi and Guangdong(NGG) province, where local high surface temperature simulation reduces nearly 5 degree.(2) The MBD parameterization improves southerly wind simulations over NGG, as well as surface temperature forecasts improvement over Guangxi, Guizhou province and southern Yunnan-Guizhou plateau(YUP), and low level southerly wind simulation improvement over intertidal zone over south China.(3) The formation of MBD is mainly in the mountain area(Wuyi, Daba mountain, east of YUP) and coastal area. The MBD over plateau, which is mainly formed at the west of 105°E, is stronger and thicker than that over Nanling mountain.(4) The improvement of GWDO and MBD parameterization is stable in model physics. MBD parameterization demonstrates more overall improvements in the forecasts than GWDO, and the larger of the model forecast error is, the greater improvements of MBD contribute to. Overall, the extended GWDO scheme successfully improves the simulations of meteorological elements forecasting during cold air outbreaks.  相似文献   

回填土不确定性对场地地震反应的影响          下载免费PDF全文

张海  陈贺  尤红兵  李克强 《地震工程学报》2019,41(2):370-377

选取某核电场地控制性钻孔的厚度、剪切波速、密度等实际勘探数据,通过改变回填土剪切波速,分析了回填土不确定性对场地地震动参数的影响。研究结果表明:在回填土层厚度不变和模型总厚度不变的情况下,地表的水平向峰值加速度随着回填土剪切波速的增大而减小,但水平向峰值加速度增幅逐渐减小;回填土剪切波速到达一定的波速就不再影响地表水平峰值加速度;随着回填土剪切波速的增加,整个反应谱的谱值都普遍减小。  相似文献   

太湖波浪数值模拟   总被引：8，自引：7，他引：1  

李一平  逄勇  刘兴平  罗潋葱  徐秋霞 《湖泊科学》2008,20(1):117-122

在太湖实际波浪观测的基础上,采用率定验证后的第三代动谱平衡方程,考虑实际水底地形、波浪折射、浅化、反射、破碎、湖流等条件下,对太湖波浪进行数值模拟,研究太湖波浪的主要影响因素.结果表明:SWAN模型可以较好地模拟风作用下太湖风浪的生成和传播过程,模型在太湖应用是合适的;波高、波长、波周期等波浪参数在太湖的分布与风速、风向、水深等因素密切相关;在相同风向、不同风速情况下,太湖波浪发展至稳定状态的时间不一样;在不同风向,相同风速持续作用下,有效波高达到稳定的时间差不多,变化趋势也比较相同.说明波浪的发展不光取决于风速的大小,还同风的持续吹的时间和风区长度有关.  相似文献   

M_(S(BB))、M、M_(S7)震级对比     

尹战军  王石磊  王树波 《地震地磁观测与研究》2017,38(6):17-20

选取2009—2015年内蒙古测震台网速报的46个M≥4.1地震,依据《地震震级的规定》(GB17740—2016)中关于量取地震宽频带面波震级M_(S(BB))的各项条款,重新量取M_(S(BB)),与中国地震台网中心编目结果产出的M震级和M_(S7)震级进行对比分析,结果显示:M_(S(BB))震级与M_(S7)震级的一致性较好。  相似文献