利用CEEMD分析中国沿海GNSS站高程时序变化     

刘豪  周东旭  王盼龙  张化疑  王永康  姜传苓 《测绘通报》2020,(3):39-43,77

利用完备经验模态分解方法（CEEMD）对我国沿海地区6个GNSS基准站（2010—2018）的高程时序数据进行了处理分析。结果表明：CEEMD在高程时间序列分析中具有一定的优越性，可准确分解出各GNSS站高程时序中存在的周、月、季节、年等变化周期项，其中周年运动是主要贡献项，各站高程时间序列的短周期变化与潮汐变化周期具有密切关联性；沿海GNSS站的地面沉降既具有区域的一致性，又存在区域间差异性，其中D区DBJO、DZJJ站呈现先下降后上升的趋势，N区NZUH、NWZU站呈下降趋势，B区的BZMW呈上升趋势，而同海区的BLHT站则呈显著的下降趋势。  相似文献   

爆破荷载作用下露天矿边坡稳定性的突变研究     

周子涵  陈忠辉  王建明  张凌凡  年庚乾 《岩土力学》2020,41(3):849-857

基于二维斜坡平面滑动失稳力学模型，引入爆破荷载因素，建立了露天爆破荷载作用下岩质边坡失稳的尖点突变理论模型。根据建立的突变模型，探讨了爆破荷载幅值和爆破荷载频率对边坡稳定性的影响规律，导出了边坡的动态自稳临界高度，并提出了失稳的判据条件，结果表明：爆破荷载幅值越大，爆破荷载频率越小，后缘裂缝深度越大，边坡失稳的可能性越高；在爆破荷载作用下，边坡的稳定程度是动态变化的，且随着应力波入射角的增大，边坡失稳破坏的可能性不断提高。以大孤山露天矿内的两处边坡为例，计算了边坡的动安全系数及动态自稳临界高度，利用边坡当前实际的稳定情况验证了提出的边坡失稳判据的合理性，为预防露天矿爆破在开挖过程中边坡岩体的动力失稳提供了一定的理论支持。  相似文献   

Stochastic bivariate time series models of waves in the North Sea and their application in simulation-based design     

《Applied Ocean Research》2019

In this paper, we present and evaluate three long-term wave models for application in simulation-based design of ships and marine structures. Designers and researchers often rely on historical weather data as a source for ocean area characteristics based on hindcast datasets or in-situ measurements. The limited access and size of historical datasets reduces repeatability of simulations and analyses, making it difficult to assess the sampling variability of performance and loads on marine vessels and structures. Markov, VAR and VARMA wave models, producing independent long-term time series of significant wave height (H_s) and spectral peak period (T_p), is presented as possible solutions to this problem. The models are tested and compared by addressing how the models affect interpretation of design concepts and the ability to replicate statistical and physical characteristics of the wave process. Our results show that the VAR and VARMA models perform sufficiently in describing design performance, but does not capture the physical process fully. The Markov model is found to perform worst of the tested models in the applied tests, especially for measures covering several consecutive sea states.  相似文献   

一种利用浮标站资料改进海浪模式有效波高预报的方法     

龚 《海洋预报》2020,37(1):50-54

基于浮标站海浪历史数据,利用回归分析方法建立了海浪数值模式有效波高预报产品的一元二次回归方程订正统计模型。通过2017年7月1日-2018年10月10日期间业务试运行结果发现:订正方程能有效改善有效波高数值预报产品的预报精度,且预报时效越短订正效果越显著。其中,第6~11 h预报时效内的订正前后平均绝对误差值减小0.17~0. 241 m,第6~18 h预报时效内订正前后均方根误差减小幅度为0.103~0. 28 m。这说明应用订正统计模型对海浪模式输出产品进行订正,也是改进海浪模式预报准确率的一种有效途径。  相似文献   

Severity of killer whale behavioral responses to ship noise: A dose–response study     

《Marine pollution bulletin》2014,80(1-2):254-260

Critical habitats of at-risk populations of northeast Pacific “resident” killer whales can be heavily trafficked by large ships, with transits occurring on average once every hour in busy shipping lanes. We modeled behavioral responses of killer whales to ship transits during 35 “natural experiments” as a dose–response function of estimated received noise levels in both broadband and audiogram-weighted terms. Interpreting effects is contingent on a subjective and seemingly arbitrary decision about severity threshold indicating a response. Subtle responses were observed around broadband received levels of 130 dB re 1 μPa (rms); more severe responses are hypothesized to occur at received levels beyond 150 dB re 1 μPa, where our study lacked data. Avoidance responses are expected to carry minor energetic costs in terms of increased energy expenditure, but future research must assess the potential for reduced prey acquisition, and potential population consequences, under these noise levels.  相似文献   

径向基神经网络GPS高程转换方法     

杨金玲  曹先革  曹先密 《地理空间信息》2010,8(6):65-66,70

针对GPS高程转换问题,给出了基于径向基神经网络转换GPS高程的模型。用实际观测数据对该模型进行了试验,结果表明,用径向基神经网络转换GPS高程精度高于二次拟合法和BP神经网络法。径向基神经网络能够有效克服BP神经网络局部极小值的缺点,并且具有较高的收敛速度,在GPS高程转换方面具有广阔应用前景。  相似文献   

全站仪三维坐标法在桥梁施工测量中的应用   总被引：1，自引：0，他引：1  

田林亚  王进锋  武东辉 《测绘科学》2010,35(3):198-199,202

尽管全站仪三维坐标法已在工程测量领域得到广泛采用,但其测量精度及其影响因素还需要深入分析,使之能合理地应用于具体工程。推导了三维坐标的精度计算公式,分析了测量精度的影响因素,针对特定的测量仪器、测量条件和大气折光误差,计算和分析了测点所能达到的精度,阐明了控制和提高测量精度的措施。将该方法应用于苏通大桥墩塔基础施工测量,根据具体的测量仪器和环境条件等,计算测点的点位中误差和高程中误差分别为±5.9mm和±6.9mm,其精度完全满足施工测量的限差要求,表明测量结果具有较高的精度和可信度。  相似文献   

A joint distribution of significant wave height and characteristic surf parameter     

Dag Myrhaug  Sébastien Fouques 《Coastal Engineering》2010

The paper provides a joint distribution of significant wave height and characteristic surf parameter. The characteristic surf parameter is given by the ratio between the slope of a beach or a structure and the square root of the characteristic wave steepness in deep water defined in terms of the significant wave height and the spectral peak period. The characteristic surf parameter is used to characterize surf zone processes and is relevant for e.g. wave run-up on beaches and coastal structures. The paper presents statistical properties of the wave parameters as well as an example of results corresponding to typical field conditions.  相似文献   

Study on Flow Field Around Vertical Breakwater Under Different Overtopping Conditions Based on Numerical Simulation     

蒋学炼  吴米玲  李炎保 《中国海洋工程》2010,(4)

A numerical wave flume is constructed based on the Reynolds Averaged Navier-Stokes (RANS) equations with turbulence closure by a modified k-ε model to study the viscous interactions of waves with vertical breakwaters for different overtopping cases. The governing equations,the turbulence model,boundary conditions,and solution method for the numerical wave flume are introduced briefly. The reliability of the numerical wave flume is examined by comparing the numerical results with the experimental measurement...  相似文献   

Parameter analysis for gate metal—oxide—semiconductor structures of ion-implanted 4H silicon carbide metal—semiconductor field-effect transistors     

王守国  张义门  张玉明 《海洋学报(英文版)》2010,29(9)

From the theoretical analysis of the thermionic emission model of current--voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal--semiconductor field-effect transistors (sample A and sample B for three and four times multiple ion-implantation channel region respectively) fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.  相似文献