One‐dimensional consolidation with a threshold gradient: a Stefan problem with rate‐dependent latent heat     

Yang Zhou  Wan‐kui Bu  Meng‐meng Lu 《国际地质力学数值与分析法杂志》2013,37(16):2825-2832

During the process of one‐dimensional consolidation with a threshold gradient, the seepage front moves downward gradually, and the problem is indicated as a Stefan problem. The novel feature in this Stefan problem is a latent heat that varies inversely with the rate of the moving boundary. An exact solution for the external load that increases in proportion to the square root of time is constructed using the similarity transformation technique. Computational examples concerning the effect of different parameters on the motion of the seepage front are presented. The exact solution provides a worthwhile benchmark for verifying the accuracy of numerical and approximate methods. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Application of the threshold method to air quality data     

G. R. Dargahi-Noubary 《Natural Hazards》1988,1(3):227-233

A new threshold method is explained in a manner suitable for workers in the general scientific area. Its application to the prediction of extreme pollutant concentrations is described and the results are compared with those of a conventional procedure, using a set of published data. A discussion concerning the difficulties of the presently used statistical technique is also included.  相似文献   

序贯一维型边缘检测新算法     

吕言 《武汉大学学报(信息科学版)》1988,(4)

本文提出一种既可用于从图象上提取具有某种用途的一维边缘,又可用于提取具有多种用途的二维边缘的序贯一维型边缘检测新算法。由于构成该算法重要组成部分的基础算子的作用,以及将二维问题化为一维问题求解而使其明显具有简单,快速、有效的特点。该算法还具有Abdou等所建议的边缘检测算子应具有的两个特性。  相似文献   

Nonlinear chemical couplings in the tropospheric NO x -HO x gas phase chemistry     

J. Zimmermann  D. Poppe 《Journal of Atmospheric Chemistry》1993,17(2):141-155

A bifurcation phenomenon with relevance to atmospheric chemistry is discussed. The gasphase reactions in the troposphere exhibit two types of temporal evolution which are controlled by the strength of the source,Q, of nitric oxide, NO, via the nonlinear chemical coupling between the hydrogen oxides and nitrogen oxides chemistry. IfQ remains below a threshold value, all short-lived species, including NO, approach steady-state concentrations, while above the threshold bifurcation to another state with increasing (nonstationary) NO concentrations accompanied by a depletion of the OH and HO₂ abundances takes place.  相似文献   

船舶气象导航随船验证     

杨良华 《气象》1993,19(9):52-55

通过横流太平洋往返两个航次随船调查，研究了采用气象导航对减少燃油消耗和保证船舶安全、班期等，不但有定的经济效益，而且是一种非常有效的航运管理方法。  相似文献   

The first and the second e of the extreme value distribution,EV1     

M. A. J. van Montfort  A. Otten 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(1):69-76

In the peak over threshold model resulting in the Extreme-value distribution, type I, (EV1) the firste of the distribution function is based on the Poisson number of exceedances, and the seconde arises from the Exponentially distributed magnitudes.This paper, on the one hand, generalises the Poisson model to the (positive and negative) Binomial distribution, and, on the other hand, the Exponential distribution is generalised to the Generalised Pareto distribution. Lack of fit with respect to the Poisson and Exponential distribution is measured by statistics derived from those which would be locally most powerful if the estimates of the location and scale parameter were equal to the true parameter values. Ways of combining both statistics are discussed.  相似文献   

多元门限回归模型的一种建模方法   总被引：12，自引：0，他引：12  

严华生  曹杰 《大气科学》1994,18(2):194-199

本文根据门限自回归模型的基本思想[1]，提出一种多元门限回归模型的建模方法。其特点是充分考虑了预报系统中某些特殊预报因子突变点对预报关系的改变作用。数值实例表明，该模型在模拟和预报精度上比一般线性逐步回归模型有一定程度的提高。  相似文献   

影响生油门限深度的地质因素     

Chen Jianyu Wang Qijun 《地球科学》1986,(3)

本文根据三水盆地下第三系心组有机地化资料的分析,确定其生油门限深度为400米。进一步讨论了影响我国东部第三系含油气盆地成油门限值的几种地质因素。提出这些年青的盆地只要具有高地温梯度、高沉降速度、埋深大、剥蚀少就能在较短时间中形成油气。  相似文献   

横向沙丘背风侧沙粒风蚀起动的风洞模拟   总被引：1，自引：1，他引：1  

钱广强  董治宝  罗万银  王洪涛 《干旱区地理》2007,30(1):66-70

通过风洞实验,探讨了横向沙丘背风侧“二次流”的沉积学和形态-动力学意义。在不同迎风坡坡度的横向沙丘模型背风侧,我们观测了不同位置沙粒的起动风速以及在临界状态下沙粒的运动特征。结果表明,沙丘背风侧的颗粒起动风速不仅与其距沙丘顶部的距离有关,也与沙丘迎风坡坡度有密切关系。根据沙丘背风侧颗粒运动特征,可以将其划分为向后运动区域、晃动或摆动区域以及向前运动区域,产生这一现象的原因是在沙丘背风坡气流分离、反向涡和气流重新辐合共同作用的结果。在所有的观测结果中,迎风坡坡度为15°的沙丘具有最大的沙粒起动风速和最远的气流重新辐合距离,其原因尚需进一步研究。  相似文献   

南方海相地震资料脊波非线性阈值去噪方法   总被引：2，自引：0，他引：2  

张恒磊  宋双  刘天佑 《应用地球物理》2007,4(4):271-275

小波分析方法在数据处理中已得到成功广泛的应用,这主要得益于它的局部时频分析能力,但是小波分析对方向的表征能力有限。脊波变换具备优越的方向选择性能,能更好地处理含有线状变化特征的信号。本文针对低信噪比地震记录,尝试研究利用脊波变换方法对其进行处理,提高剖面资料信噪比,突出同相轴信息。在对南方某油田的实际地震资料的处理中,可以发现处理后的地震剖面同相轴品质及连续性有了明显改善,信噪比增强,分辨率相应提高,体现出了该方法相对常规小波分析方法的优越性。  相似文献