Shaking Table Test Study on Dynamic Characteristics of Bridge Foundation Reinforcement on Slopes   总被引：3，自引：3，他引：0  

Lei D  Qi Zhihui  Jiang Guanlu  Wang Zhimeng  Li Anhong 《中国地震研究》2017,31(3):403-413

With the fast development of bridge construction in mountainous and seismic areas, it is necessary to conduct related research. Based on the design of a shaking table model test, here are the following test results:the filtering effect exists in soil and is affected by the dynamic constraint conditions, the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface, the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.  相似文献   

On the spectral consistency of the altimetric ocean and geoid surface: a one-dimensional example     

Alberta Albertella  Reiner Rummel 《Journal of Geodesy》2009,83(9):805-815

Geoid models from the new generation of satellite gravity missions, such as GRACE and GOCE, in combination with sea surface from satellite altimetry allow to obtain absolute dynamic ocean topography with rather high spatial resolution and accuracy. However, this implies combination of data with fundamentally different characteristics and different spatial resolutions. Spectral consistency would imply the removal of the short-scale features of the altimetric sea surface height by filtering, to provide altimetric data consistent with the resolution of the geoid field. The goal must be to lose as little as possible from the high precision of the altimetric signal. Using a one-dimensional example we show how the spectrum is changing when a function defined only on a limited domain (ocean in the real case) is extended or not as to cover the complete domain (the whole sphere in the real case). The results depend on the spectral characteristics of the altimetric signal and of the applied filter. Referring to the periodicity condition, as it is requested in the case of Fourier analysis, the action of the two classical filters (Ideal Low Pass and Gauss filter) and of two alternative procedures (wavelets and Slepian) is studied.  相似文献   

智能优化方法与粒子滤波技术融合的分析与展望   总被引：1，自引：0，他引：1       下载免费PDF全文

宫轶松  归庆明  孙付平  李保利 《海洋测绘》2009,29(2):74-77

智能优化算法通过模拟自然生态系统机制以解决复杂优化问题,粒子滤波成为解决非线性及非高斯动态系统最优估计问题的研究热点。若将多种优化算法结合使用,设计更好的滤波器参数寻优步骤,将会极大改善现有非线性滤波的估计性能。介绍了几种智能计算方法和粒子滤波方法,在此基础上,对智能优化方法与粒子滤波技术的融合进行了分析和讨论,并加以总结和展望。  相似文献   

一种改进的线性预测滤波算法     

张靖  张晓君  江万寿  王建超  郭大海 《国土资源遥感》2011,22(1):52-56

对传统的线性预测算法进行改进,通过粗差剔除、初始点选取、特殊地形分析及光滑度检验等步骤提高了滤波精度.利用ISPRS发布的6组标准测试数据与原方法进行实验比较,结果证明,改进后的算法提高了滤波总精度以及地面点分类精度.  相似文献   

基于相干系数指导的自适应均值、中值滤波     

张鲜妮  王磊 《北京测绘》2013,(3):5-9

基于复数干涉质量与相干系数之间的关系,本文提出了一种基于相干系数指导的自适应滤波新方法。通过实验表明,相干系数指导的自适应滤波方法,在数据一致性、细节信息保持和边缘信息保持方面明显优于传统方法,相比之下去除噪声能力有所下降,残差点数目相对于固定窗口(大窗口)滤波较多,但是由于这种方法考虑了干涉噪声与相干系数之间的关系,所以滤波更符合实际,滤波综合性能较好。  相似文献   

Smoothing and gap-filling of high resolution multi-spectral time series: Example of Landsat data     

《International Journal of Applied Earth Observation and Geoinformation》2017

This paper introduces a novel methodology for generating 15-day, smoothed and gap-filled time series of high spatial resolution data. The approach is based on templates from high quality observations to fill data gaps that are subsequently filtered. We tested our method for one large contiguous area (Bavaria, Germany) and for nine smaller test sites in different ecoregions of Europe using Landsat data. Overall, our results match the validation dataset to a high degree of accuracy with a mean absolute error (MAE) of 0.01 for visible bands, 0.03 for near-infrared and 0.02 for short-wave-infrared. Occasionally, the reconstructed time series are affected by artefacts due to undetected clouds. Less frequently, larger uncertainties occur as a result of extended periods of missing data. Reliable cloud masks are highly warranted for making full use of time series.  相似文献   

A relational database of global U-Pb ages     

Stephen J.Puetz 《地学前缘(英文版)》2018,9(3):877-891

Enhanced understanding of how sampling techniques affect estimates of the global U-Pb age-distribution have, in turn, constrained U-Pb database design. Recent studies indicate that each continent has a unique age-distribution, as determined by zircon ages dated by the U-Pb isotope method. Likewise, broad regions within a continent also exhibit diverse age-distributions. To achieve a reliable estimate of the global distribution, the heterogenous composition of the continental crust requires sampling as many regions as feasibly possible. To attain this goal, and to provide a method for calculating age histograms, the records from a recent global U-Pb compilation are supplemented with 281,631 new records. These additions increase the database size to 700,598 records. In addition, the data are now restructured and made available as a relational database. After filtering the records by the six age-models included with the database, the results reveal two problems that might generally be unrecognized. First, an abrupt switch in the best-age at any given point(such as 1000 Ma) from ~(206)Pb/~(238)U ages to ~(207)Pb/~(206)Pb ages artificially depresses the age-distribution at the cutoff point. Second, rejecting analyses based on either absolute discordance or the magnitude of 2σ precision errors artificially depresses the age-distribution between 900 Ma and 2000 Ma. The results indicate that, when estimating the global U-Pb age-distribution, the methods for determining best-age and for rejecting records both require some attention. Possible solutions include using either an Accuracy Model or a Precision Model for estimating best-age, and then including all U-Pb records in the estimate, rather than rejecting any of them.  相似文献   

几个试验因子对细巧华哲水蚤清滤率和滤食率的影响   总被引：6，自引：0，他引：6  

陆开宏  吕耀平  林霞  郑祯  姚国琴 《海洋科学》2001,25(4):44-47

以象山港浮游桡足类优势种细巧华哲水蚤（Sinocalanus tenellus) 成体为试验动物投喂以大溪地等鞭金藻（Isochrysis galbona)，对其清滤率F（ml/个.h)和滤食率G（细胞／个.h)进行了实验测定，结果表明，温度，海水比重，食物浓度及试验动物密度的变化对细巧华哲水蚤清滤率和滤食率均有显著影响，水温15度，比重1．－1－，食物浓度150000个细胞／ml和试验动物密度．25个／ml的条件下，细巧华哲水蚤滤食率达到最大。  相似文献   

Elimination of effects of earthquake in monitoring crustal movement     

C. T. Celik  W. Chen  R. M. Bingley 《Studia Geophysica et Geodaetica》2007,51(2):207-219

Monitoring crustal movements is important in understanding the earth surface and in developing theories about plate tectonics. Plate tectonics describes earth crust which consists of a number of plates moving relative to one another. Global plate models suggest that plate movements are constant due to the fact that relative movements of plates were represented by averaged plate motion. However, if an earthquake occurs, the uniform movement of related plates does not follow the regular trend. In analysis by Kalman Filter, the effects of an earthquake occured within crustal movement monitoring period by geodetic method have been eliminated by a proposed approach, Fading Memory Filter. The proposed method was tested using a real/simulated data. The results of the test showed that the effect of a strong earthquake (M_w = 7.1) which had occurred in the Gulf of Eilat/Aqaba was eliminated. Consequently, the proposed method is capable of removing or eliminating a suddan effect in monitoring crustal movements in the analysis by using the Kalman Filter.  相似文献   

2004—07—28新乡市大暴雨成因分析   总被引：5，自引：0，他引：5  

刘朝亮王新红  钟兴华马月枝 王金兰 《河南气象》2006,(1):28-30

从环流形势、单站气象要素及中尺度滤波分析等几方面对2004年7月28日新乡市大暴雨过程进行分析,结果表明:这次暴雨、大暴雨天气过程是副热带高压西伸北抬和西风槽东移及北方南下冷空气的共同影响造成的,副高西伸北抬的“突变”过程,是造成大暴雨的直接原因;中低层切变线的生成,为强对流天气的产生提供了动力条件;低空西南急流不仅输送暖湿空气,增强层结的不稳定性,而且可以产生低层扰动,触发不稳定能量的释放,新乡地区东南部位于深厚急流区入口处的左侧,是暴雨、大暴雨产生的关键部位;用T213的初始流场经滤波分析后,能清晰显示出形成大暴雨的中尺度辐合系统,对暴雨、大暴雨预报有一定的指示意义。  相似文献