Identification of non-linear and non-stationary soil properties during the 1995 Hyogoken-nanbu earthquake     

A. Mikami  T. Sawada  T. Ekawa 《Soil Dynamics and Earthquake Engineering》2003,23(4):279

An extended Kalman filter algorithm with local iteration is presented for the identification of non-linear and non-stationary soil properties. Borehole-array strong motions were recorded at a liquefied site during the 1995 Hyogoken-nanbu earthquake. In this study, a modified Kalman filtering method in which the extended Kalman filter is iteratively used at every local time-step to track rapid parameter changes is proposed. The method is then applied to the instrumented soil layer, which is modeled by an equivalent linear model. An identification of non-linear and non-stationary soil properties was conducted successfully; and non-linear restoring force–displacement relationships including progression with time were obtained.  相似文献   

Study on The Prediction Method of Characteristic Parameters of Solar X-ray Flares     

Guo Ce  Xue Bing-sen  Lin Zhao-xiang 《Chinese Astronomy and Astrophysics》2013

Solar ?ares are important events for the space weather. The predic- tion of relevant parameters of solar ?ares has practical signi?cance for evaluating the effect of sudden ionospheric disturbance (SID). The data of soft X-ray ?ux observed by the GOES-8 satellite in the 23th solar cycle are used to predict the peak intensities and ending times of X-class ?ares with the method of data ?t- ting. Using this method to analyze the X-class ?ares in the 23th solar cycle, it is possible to predict the peak ?ux of an X-class ?are 17 minutes in advance at most. And the ending time of an X-class ?are may be predicted about 60 minutes in advance at most. The predicted results indicate that the prediction method has certain effectiveness and applicability.  相似文献   

多核处理器的机载激光雷达点云并行三角网渐进加密滤波方法     

亢晓琛  刘纪平  林祥国 《测绘学报》2013,42(3):331-336

滤波是机载LiDAR点云数据处理的关键步骤之一,点云数据的海量化特性使得一般的串行化滤波处理方法无法满足快速成图的应用需求。提出一种基于多核计算技术的并行三角网渐进加密滤波方法,将串行方法中最耗时的三角网构建与脚点判别过程进行了并行化改造。三角网构建算法的并行化基于分治法实现,脚点判别算法的并行化采用一种随机分配策略将三角网划分为多个离散分布的三角形子集合来实现负载均衡。并行滤波方法在8核环境下多次渐进加密的实际加速比达到3.1左右。试验证明,该方法可以充分发挥多核计算优势,并且对不同分布形态点云数据具有良好的适应性。  相似文献   

R-T-S平滑算法在POS数据后处理中的应用     

郝万亮  孙付平 《测绘工程》2013,(6):65-67,80

高精度的定位定姿系统（POS,Position and Orientation System）在测绘领域发挥着重要的作用,为了提高数据的精度,将平滑技术应用于POS数据的后处理中.文中介绍POS数据后处理算法的流程,对平滑技术尤其是应用最为广泛的R-T-S平滑进行详细分析,并对该算法进行数值仿真.结果表明,与传统的卡尔曼滤波相比,R-T-S平滑不仅可以提高位置姿态精度,而且在卫星信号失锁的情况下精度也能得到大幅改善,是一种有效的数据处理算法.  相似文献   

自适应卡尔曼滤波在沉降预测中的应用     

孙连华  刘恒辉  徐久泰 《北京测绘》2013,(6):7-10

随着我国经济高速发展,对煤炭资源的需求与日俱增,矿山大量开采造成矿区地表大面积沉陷.对于地下采煤,地表点的移动经历一个由开始移动到剧烈移动,最后到停止移动的全过程.为了更好地掌握矿山开采地袁沉降移动规律,本文采用自适应卡尔曼滤波与标准卡尔曼滤波对其进行预测与分析.  相似文献   

基于GPS软件接收机的SINS／GPS紧组合系统仿真     

胡雯婷  王可东 《全球定位系统》2013,(5):27-33,39

为了系统验证SINS／GPS紧组合系统的性能,基于GPS软件接收机,进行了仿真系统构建。仿真系统由轨迹发生器、GPS中频信号模拟器、IMU信号模拟器、GPS软件接收机、SINS导航解算模块、组合滤波算法和导航性能分析模块等部分构成,其中详细设计了GPS软件接收机中的捕获和跟踪算法、SINS解算以及基于伪距和伪距率的组合滤波算法。仿真结果表明：紧组合导航系统收敛性较好,能够一定程度上抑制惯导系统误差的积累,有较好的导航性能。设计的该系统满足紧组合导航系统性能验证的需要,也为后续的超紧组合研究奠定了良好的基础。  相似文献   

结合卡尔曼滤波的城市路段速度估计   总被引：1，自引：0，他引：1  

曾伟良  何兆成  沙志仁  佘锡伟 《测绘科学》2013,38(1):96-99

本文以城市出租车为浮动车数据采集源,介绍了基于GPS数据的实时路段速度估计的基本方法。针对目标路段GPS数据样本量不足的情况,考虑邻近区域的路段速度、上周同日速度、前一时刻速度等与目标路段当前时刻速度等密切相关的变量,建立多元线性回归方程,利用卡尔曼滤波融合预测值和测量值,从而提高路段行驶速度的估计精度。选择广州市东风路作为测试实例,融合值比测量值误差降低9%,绝对相对误差变动系数减少4%,表明结合卡尔曼滤波技术的城市路段速度估计精度和稳定性均得到提高。  相似文献   

Generation of differential GPS corrections along with performance of quality control     

Jin Xinxiang 《地球空间信息科学学报》2013,16(2):65-73

The DGPS technique can provide considerably better relative positioning accuracy than the stand-alone GPS positioning, but the improvement depends on the distance between the user and the reference station (spatial correlation), the latency of differential corrections (temporal correlation), and the quality of differential corrections. Therefore, how to correctly generate differential corrections as well as their pricision is very important to the DGPS positioning technique. This paper presents a new algorithm for generating differential GPS corrections. This algorithm directly uses code and carrier observations in the measurement model of a Kalman filter, so that it is possible to use a simple stochastic model and to use the standard algorithm of the Kalman filter. The algorithm accounts for biases like multipath errors and instrumental delays in code observations and it shows how differential corrections are differently affected by code biases when dual or single frequency data is used. In addition, the algorithm can be integrated with a real time quality control procedure. As a result, the quality of differential corrections can be guaranteed with a certain probability.  相似文献   

Dual states estimation of a subsurface flow-transport coupled model using ensemble Kalman filtering     

《Advances in water resources》2013

Modeling the spread of subsurface contaminants requires coupling a groundwater flow model with a contaminant transport model. Such coupling may provide accurate estimates of future subsurface hydrologic states if essential flow and contaminant data are assimilated in the model. Assuming perfect flow, an ensemble Kalman filter (EnKF) can be used for direct data assimilation into the transport model. This is, however, a crude assumption as flow models can be subject to many sources of uncertainty. If the flow is not accurately simulated, contaminant predictions will likely be inaccurate even after successive Kalman updates of the contaminant model with the data. The problem is better handled when both flow and contaminant states are concurrently estimated using the traditional joint state augmentation approach. In this paper, we introduce a dual estimation strategy for data assimilation into a one-way coupled system by treating the flow and the contaminant models separately while intertwining a pair of distinct EnKFs, one for each model. The presented strategy only deals with the estimation of state variables but it can also be used for state and parameter estimation problems. This EnKF-based dual state-state estimation procedure presents a number of novel features: (i) it allows for simultaneous estimation of both flow and contaminant states in parallel; (ii) it provides a time consistent sequential updating scheme between the two models (first flow, then transport); (iii) it simplifies the implementation of the filtering system; and (iv) it yields more stable and accurate solutions than does the standard joint approach. We conducted synthetic numerical experiments based on various time stepping and observation strategies to evaluate the dual EnKF approach and compare its performance with the joint state augmentation approach. Experimental results show that on average, the dual strategy could reduce the estimation error of the coupled states by 15% compared with the joint approach. Furthermore, the dual estimation is proven to be very effective computationally, recovering accurate estimates at a reasonable cost.  相似文献   

Double deck bridge behavior and failure mechanism under seismic motions using nonlinear analyzes     

Shirin Alali  Li Jianzhong  Guo Guanzhong 《地震工程与工程振动(英文版)》2013,12(3):447-461

This paper investigates the behavior and the failure mechanism of a double deck bridge constructed in China through nonlinear time history analysis.A parametric study was conducted to evaluate the influence of different structural characteristics on the behavior of the double deck bridge under transverse seismic motions,and to detect the effect of bidirectional loading on the seismic response of this type of bridge.The results showed that some characteristics,such as the variable lateral stiffness,the foundation modelling,and the longitudinal reinforcement ratio of the upper and lower columns of the bridge pier bents have a major impact on the double deck bridge response and its failure mechanism under transverse seismic motions.It was found that the soft story failure mechanism is not unique to the double deck bridge and its occurrence is related to some conditions and structural characteristics of the bridge structure.The analysis also showed that the seismic vulnerability of the double deck bridge under bi-directional loading was severely increased compared to the bridge response under unidirectional transverse loading,and out-of-phase movements were triggered between adjacent girders.  相似文献