基于PSR-WSVM模型的边坡位移预测     

李建新  刘小生  肖钢  周文  刘仁志 《大地测量与地球动力学》2020,40(6):577-580

为建立高精度的边坡位移预测模型，采用相空间重构（PSR）将边坡位移时间序列数据转换为多维数据，同时构造小波核函数改进的支持向量机模型，建立PSR-WSVM模型并应用于边坡位移预测。将PSR-WSVM模型预测结果与传统支持向量机（SVM）模型、小波支持向量机（WSVM）模型和基于相空间重构的支持向量机（PSR-SVM）模型预测结果进行对比，通过平均绝对误差（MAE）、平均绝对误差百分比（MAPE）和均方根误差（RMSE）3个精度评价指标验证PSR-WSVM模型的可行性。工程实例结果表明，PSR-WSVM模型预测结果的3个精度评价指标都优于另外3种模型，边坡位移预测的精度明显提升。  相似文献   

A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation     

Wei Wen  YuanMing Lai  ZheMin You 《寒旱区科学》2020,12(3):125-133

Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.  相似文献   

First evidence of IMF control of Jovian magnetospheric boundary locations: Cassini and Galileo magnetic field measurements compared     

Margaret G. Kivelson  David J. Southwood 《Planetary and Space Science》2003,51(13):891-898

The Cassini spacecraft, en route to Saturn, passed close to Jupiter while the Galileo spacecraft was completing its 28th and 29th orbits of Jupiter, thus offering a unique opportunity for direct study of the solar wind-Jovian interaction. Here evidence is given of response of the Jovian magnetopause and bow shock positions to changes of the north-south component of the solar wind magnetic field, a phenomenon long known to occur in equivalent circumstances at Earth. The period analyzed starts with the passage over Cassini of an interplanetary shock far upstream of Jupiter. The shock's arrival at Galileo on the dusk-flank of the magnetosphere caused Galileo to exit into the solar wind. Using inter-spacecraft timing based on the time delay established from the shock arrival at each spacecraft, we point out that Galileo's position with respect to the Jovian bow shock appears to correlate with changes in the disturbed north-south reversing field seen behind the shock. We specifically rule out the alternative of changes in the shape of the bow shock with rotations of the interplanetary magnetic field as the cause.  相似文献   

Stochastic modelling of groundwater flow and solute transport in aquifers     

T.-C. Jim Yeh 《水文研究》1992,6(4):369-395

This paper presents an introductory overview of recently developed stochastic theories for tackling spatial variability problems in predicting groundwater flow and solute transport. Advantages and limitations of the theories are discussed. Lastly, strategies based on the stochastic approaches to predict solute transport in aquifers are recommended.  相似文献   

小波分析理论在GPS技术中的应用     

ZHENG Zuoya HUANG Cheng LU Xiushan 《中国科学院上海天文台年刊》2003,(1)

在GPS数据处理中 ,存在着误差影响、影响波的干扰、周跳和数据量大等问题。误差影响和影响波的干扰实质是在接收卫星信号时受到其它因素的影响 ;周跳是由于卫星信号的失锁而造成信号的不连续 ;数据量大是因为GPS观测需要采样间隔小又连续观测所致。由于小波理论具有时频分析、波形分解、特征提取和快速小波变换等特性 ,应用小波变换和波形分解可以解决误差影响和影响波的干扰的问题 ;应用特征提取可以解决周跳检测问题 ;应用快速小波变换可进行数据压缩  相似文献   

Wavelet Analysis of Space Solar Telescope Images   总被引：1，自引：0，他引：1  

Xi-An Zhu  Sheng-Zhen Jin  Jing-Yu Wang  Shu-Nian NingNational Astronomical Observatories  Chinese Academy of Science  Beijing  Department of Mechanical  Electric Engineering  China College of Mining  Technology  Beijing 《中国天文和天体物理学报》2003,3(6):587-596

The scientific satellite SST (Space Solar Telescope) is an important research project strongly supported by the Chinese Academy of Sciences. Every day, SST acquires 50 GB of data (after processing) but only 10GB can be transmitted to the ground because of limited time of satellite passage and limited channel volume. Therefore, the data must be compressed before transmission. Wavelets analysis is a new technique developed over the last 10 years, with great potential of application. We start with a brief introduction to the essential principles of wavelet analysis, and then describe the main idea of embedded zerotree wavelet coding, used for compressing the SST images. The results show that this coding is adequate for the job.  相似文献   

A Simulating Experiment in the Process of Soil Erosion on Bare Land in Mt. Tanakami     

ZHAO Wei  HU Ke  Wang Xikui  Akitsu Kimoto  Takahisa MIZUYAMA 《世界地质(英文版)》2001,4(2)

In order to understand the process of surface erosion and acquire basic data of conditions on hillslope without vege tation, a sprinkling experiment is conducted on a bare slope in Mt. Tanakami in the central part of Japan. Based on the mea surements of runoff, mean soil erosion depth, and sediment yield, etc. , the results suggest the following characteristics in the process of surface erosion in the experimental area. (1) The occurrence of sediment discharge is interrupted; (2) Surface runoff is a saturated overland flow; (3) The mean soil erosion depth is thick compared with other areas in Mt. Tanakami;(4) Sediment discharge process is detachment- limited.  相似文献   

复杂模型重力位场快速正反演方法及应用     

李庆春  潘作枢 《地球科学与环境学报》1990,(4)

提要 本文详细讨论了一种三维重力位场快速正反演方法。作者在前人工作的基础上,对算法作了行之有效的改进,通过对反演中的不稳定因素进行各种理论模型试算,得出保证迭代反演稳定收敛的准则,编制出可在微型机IBM—PC上运行的人机对话式自动正反演程序。本文还对各种不均质模型进行了模似计算并将该方法应用于某含油气沉积盆地的双层界面构造研究,揭示出了储油有利地段。  相似文献   

运输系统的区域效应研究   总被引：1，自引：0，他引：1  

高小真 《地理学报》1991,46(1):93-102

运输系统改进—运距缩短—产业布局调整这一空间过程对不同的区域可能具有完全不同的意义。本文通过对一个两区域—两部门经济模型的研究得出结论:当较落后的资源产区与经济中心之间的距离由于运输系统的改进而缩短时,资源产区的经济结构向单一化转变,初级产品的生产和输出在经济建设中逐渐占主导地位,加工工业逐渐萎缩,地方经济发展受到阻碍,而且这种变化是在距离的某一特定值处突然出现的,带有跃变的性质。这一研究结果表明,对区域运输系统的任何改进措施都应该慎而行之,以免造成与本来目标相悖的区域效应。  相似文献   

THE CONSTRUCTION AND ITS DEVELOPMENT OFTHE OVERSEAS TRANSPORT SYSTEM IN NORTHEAST CHINA     

高莎丽  刘宁  孙丽华 《中国地理科学(英文版)》1994,4(1):19-30

ＴＨＥＣＯＮＳＴＲＵＣＴＩＯＮＡＮＤＩＴＳＤＥＶＥＬＯＰＭＥＮＴＯＦＴＨＥＯＶＥＲＳＥＡＳＴＲＡＮＳＰＯＲＴＳＹＳＴＥＭＩＮＮＯＲＴＨＥＡＳＴＣＨＩＮＡＧａｏＳｈａｌｉ（高莎丽）（ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇｒａｐｈｙ，ＮｏｒｔｈｅａｓｔＮｏｒｍ...  相似文献