基于? -SVR算法的隧道围岩位移演化规律预测   总被引：3，自引：0，他引：3  

陈秋南  张永兴  赵明华  刘新荣 《岩土力学》2006,27(4):591-593

针对目前广泛应用的灰色理论、遗传算法(GA)和人工神经网络(ANN)等方法预测隧道稳定性的缺陷，提出应用稳健性能较好的? -SVR（support vector machine）算法对非对称连拱隧道围岩位移演化规律进行预测研究。应用加速混合遗传算法搜索? -SVR最优参数，以提高? -SVR的预测能力。将预测结果与灰色理论、BP神经网络预测结果进行比较，显示? -SVR算法学习和预测精度高。  相似文献   

中国东北松嫩平原地下水水化学特征与演变规律   总被引：32，自引：0，他引：32       下载免费PDF全文

章光新  邓伟  何岩  Ramsis Salama 《水科学进展》2006,17(1):20-28

在全球气候变化和高强度人类活动的影响下,松嫩平原地下水环境日益恶化,已成为制约生态环境建设和经济社会发展的重要因素。选取具有典型代表意义的洮儿河流域作为研究区,对地下水进行系统取样分析,综合运用描述性统计、相关性分析、离子比例系数和Piper三角图示法,全面系统地研究地下水水化学的时空变异特征与演变规律,揭示了风化溶滤、蒸发浓缩、阳离子交换和人为混合是控制地下水质演变的主要水文化学过程,从而为流域乃至松嫩平原盐渍土区水资源可持续开发利用和管理提供科学依据。  相似文献   

基于空间曲面拟合的自适应阈值选取方法   总被引：1，自引：1，他引：1  

张孟君  舒红  刘艳  王涛 《武汉大学学报(信息科学版)》2006,31(5):395-398

提出了一种基于空间多项式曲面拟合的自适应阈值选取方法，该方法初步考虑了图像上空间目标、背景及像素的空间分布特征，拟合了图像及其空间分布结构。  相似文献   

主动变刚度阻尼多振型半主动控制研究     

李静斌  赵林  张猛 《世界地震工程》2006,22(3):105-110

探讨了开关型半主动控制算法的研究现状,基于单步状态预测控制律,提出了针对高层建筑多自由度结构体系AVS/D(主动变刚度阻尼)多振型开关控制律。通过算例仿真分析与其它开关控制律作了比较,结果表明这种开关控制律是可行的、有效的。特别是在多自由度结构体系振动过程中有多个振型同时在受控结构的反应中起主要作用时,本文提出的开关控制律比其它振型开关控制律有更好的控制效果。  相似文献   

气象因子对金花梨生长发育的影响     

刘晓天  杨全勇 《河南气象》2006,(4):52-53

通过试验研究,探讨主要气象因子在唐河县的变化规律和对金花梨生长发育的影响,研究金花梨在遭受灾害性天气影响时,采取相应的技术措施,确保金花梨的高产、稳产。  相似文献   

试论如何依法管理地震科技档案     

贺建平 《山西地震》2007,(2):47-48

对地震科技档案目前在收集、接收等常规管理中存在的问题和如何解决这些问题进行了详细论述。认为,只有实现了档案材料形成积累和收集整理过程的一体化,才可保障档案材料的齐全完整,实现依法管理。  相似文献   

Time domain method for calculating free field motion of a layered half-space subjected to obliquely incident body waves     

李山有  朱海燕  高淑芳 《地震工程与工程振动(英文版)》2007,6(2):191-196

In numerical simulation of wave scattering under oblique incident body waves using the finite element method, the free field motion at the incident lateral boundary induced by the background layered half-space complicates the computational area. In order to replace the complex frequency domain method, a time-domain method to calculate the free field motion of a layered half-space subjected to oblique incident body waves is developed in this paper. The new method decouples the equations of motion used in the finite element method and offers an interpolation formula of the free field motion. This formula is based on the fact that the apparent horizontal velocity of the free field motion is constant and can be calculated exactly. Both the theoretical analysis and numerical results demonstrate that the proposed method offers a high degree of accuracy.  相似文献   

Turbidite bed thickness distributions: methods and pitfalls of analysis and modelling     

ZOLTÁN SYLVESTER 《Sedimentology》2007,54(4):847-870

Turbidite bed thickness distributions are often interpreted in terms of power laws, even when there are significant departures from a single straight line on a log–log exceedence probability plot. Alternatively, these distributions have been described by a lognormal mixture model. Statistical methods used to analyse and distinguish the two models (power law and lognormal mixture) are presented here. In addition, the shortcomings of some frequently applied techniques are discussed, using a new data set from the Tarcău Sandstone of the East Carpathians, Romania, and published data from the Marnoso‐Arenacea Formation of Italy. Log–log exceedence plots and least squares fitting by themselves are inappropriate tools for the analysis of bed thickness distributions; they must be accompanied by the assessment of other types of diagrams (cumulative probability, histogram of log‐transformed values, q–q plots) and the use of a measure of goodness‐of‐fit other than R², such as the chi‐square or the Kolmogorov–Smirnov statistics. When interpreting data that do not follow a single straight line on a log–log exceedence plot, it is important to take into account that ‘segmented’ power laws are not simple mixtures of power law populations with arbitrary parameters. Although a simple model of flow confinement does result in segmented plots at the centre of a basin, the segmented shape of the exceedence curve breaks down as the sampling location moves away from the basin centre. The lognormal mixture model is a sedimentologically intuitive alternative to the power law distribution. The expectation–maximization algorithm can be used to estimate the parameters and thus to model lognormal bed thickness mixtures. Taking into account these observations, the bed thickness data from the Tarcău Sandstone are best described by a lognormal mixture model with two components. Compared with the Marnoso‐Arenacea Formation, in which bed thicknesses of thin beds have a larger variability than thicknesses of the thicker beds, the thinner‐bedded population of the Tarcău Sandstone has a lower variability than the thicker‐bedded population. Such differences might reflect contrasting depositional settings, such as the difference between channel levées and basin plains.  相似文献   

浙东南火山银矿成矿规律     

邱鸿坤  梁修睦 《浙江国土资源》1998,(1)

本文综合了以往有关勘查和研究成果,总结浙江省江山—绍兴深断裂以南中生代火山岩区火山银矿床、点的时空分布、中型银矿床定位、成矿物质来源、成矿温度、矿石有用组分的垂直分带、矿物垂直分带、近矿围岩蚀变分带、矿体原生晕、稳定同位素、火山岩下的基本底物质组成差异与银矿的成矿关系等统计规律与成矿系列,认为浙东南火山岩区仍有良好的火山银（金、铅锌）矿找矿远景。  相似文献   

Land rights in conservation areas in Tanzania     

Ulrike Wanitzek  Harald Sippel 《GeoJournal》1998,46(2):113-128

Conflicts arise increasingly in Tanzania which involve claims in land located in conservation areas. These conflicts arise, in many cases, between members of the local communities and the state authorities in charge of the conservation areas. They concern customary land rights both of pastoral and of agricultural communities, a topic which also touches upon their identities. The article investigates the legal dimension of these disputes by discussing the law governing conservation areas in the wider context of land tenure legislation. Within this context, the legal framework of conservation areas is discussed from both historical and contemporary perspectives. Nature conservation must respect the needs of the local population affected. It is therefore argued that concepts of community-based conservation should be developed further to work towards the goal of integrating nature conservation and the sustainable use of natural resources. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献