Numerical simulation of the steam-water flow instability as a mechanism of long-period ground vibrations at geothermal areas   总被引：1，自引：0，他引：1  

Kota Iwamura  Satoshi Kaneshima 《Geophysical Journal International》2005,163(2):833-851

  相似文献   

Atmospheric Free Modes and Subtropical High     

TAO Li  LU Weisong 《Acta Meteorologica Sinica》2005,19(1):44-51

1. IntroductionSubtropical highs are the warm systems over bi-hemispheric subtropics, exerting great effect on theoccurrence of the rainy reason, flood-drought, heavyrain, etc. in China through the changes in positionand intensity. In recent years, in particular, the per-sistent anomaly of the high has resulted in frequenthappening of severe meteorological disasters, so thatit has become one of the leading topics of atmosphericsciences. Over the past decades scientists have madea lot of effort…  相似文献   

中国北方岩溶区含水岩溶裂隙介质的序列指示模拟研究     

陈鸿汉  朱远峰等 《地球科学》2002,27(2):168-172

针对当前岩溶学研究领域中空隙位置定量预测和数学描述的难题，选择研究程度高、资料丰富、具有典型代表性的山东济南泉域的含水岩裂隙介质，运用序列指示条件模拟方法研究空隙间的连通性能，预测岩溶裂隙密集带和强径流带的位置。研究表明，它既可给出其模拟数值的波动区间，朋不同分位数值模拟图均能明显一致地指示出岩溶裂隙密集带和强径流带位置，尤其是当样本点较少时，也可获得几乎与样本点较多时的一致成果，从而为该方法的推广应用提供了广阔的领域。  相似文献   

垂直切变基流中非地转涡旋波的不稳定   总被引：10，自引：6，他引：10       下载免费PDF全文

张立凤  王丽琼  张铭 《大气科学》2001,25(3):391-400

利用Boussinesq方程研究了扰动传播方向与垂直切变基流有一夹角时的不稳定问 题，即斜交型不稳定问题。当Richardson数不大时，在α中尺度波段其增长率最大，此时该斜交型不稳定的性质既不同于重力惯性波的对称不稳定，也与Rossby波的斜压不稳定有差异，而是非地转涡旋波的不稳定。  相似文献   

二维非静力平衡深厚湿倾斜对流数值模式设计与条件性对称不稳定数值试验   总被引：2，自引：0，他引：2       下载免费PDF全文

宋晓亮  陆汉城 《大气科学》2001,25(4):503-514

设计了一个宜于研究深厚湿倾斜对流运动的二维非弹性非静力平衡数值模式.模式采用非静力平衡条件、非常值湍流扩散系数,并具有最优协调分辨率,弥补了以往条件性对称不稳定数值研究中的诸多缺陷.数值试验表明:模式运行稳定可信且对深厚湿倾斜对流运动有较强的描述能力.在条件性对称不稳定条件下,扰动发展呈现为强倾斜环流特征,垂直速度场有狭窄的强倾斜上升运动,与倾斜上升运动相伴有倾斜云带发展.诊断分析表明:在扰动发展演化过程中,条件性对称不稳定演化为一种混合不稳定的形式存在.  相似文献   

斜压大气亚临界不稳定的数值试验     

陆维松  江敦双  张惠莲 《南京气象学院学报》2001,24(3):299-307

利用一个由表面摩擦和辐射线弛强迫驱动的斜压准地转两层模式作数值试验，来研究斜压大气中的亚临界不稳定现象。试验结果表明，当无量纲量β≥0.25时，斜压两层大气中能够发生亚临界不稳定现象。亚临界不稳定现象的发生与初始扰动的选择有关。科氏参数的经向梯度的大小又是影响斜压稳定性强度的一个重要因素，其值越大，斜压稳定性强度越小。  相似文献   

Simulating earthquake ground motion at a site, for given intensity and uncertain source location     

J. Alamilla  L. Esteva  J. García-Pérez  O. Díaz-López 《Journal of Seismology》2001,5(4):475-485

Following a companion article, ground motion acceleration time historiesduring earthquakes can be described as realizations of non-stationarystochastic processes with evolutionary frequency content and instantaneousintensity. The parameters characterizing those processes can be handled asuncertain variables with probabilistic distributions that depend on themagnitude of each seismic event and the corresponding source-to-sitedistance. Accordingly, the generation of finite samples of artificial groundmotion acceleration time histories for earthquakes of given intensities isformulated as a two-stage Monte Carlo simulation process. The first stageincludes the simulation of samples of sets of the parameters of thestochastic process models of earthquake ground motion. The second stageincludes the simulation of the time histories themselves, given theparameters of the associated stochastic process model. In order to accountfor the dependence of the probability distribution of the latter parameterson magnitude and source-to-site distance, the joint conditional probabilitydistribution of these variables must be obtained for a given value of theground motion intensity. This is achieved by resorting to Bayes Theoremabout the probabilities of alternate assumptions.Two options for the conditional simulation of ground motion time historiesare presented. The more refined option makes use of all the informationabout the conditional distribution of magnitude and distance for thepurpose of simulating values of the statistical parameters of the groundmotion stochastic process models. The second option considers allprobabilities concentrated at the most likely combination of magnitude anddistance for each of the seismic sources that contribute significantly to theseismic hazard at the site of interest.  相似文献   

煤柱冲击地压的解析分析   总被引：5，自引：0，他引：5  

李忠华  潘一山 《地质灾害与环境保护》2001,12(2):62-65

提出应用煤层塑性软化理论和材料失稳的动力判别准则，对煤柱冲击地压进行的解析分析方法。计算顶板变形和煤柱应力分布规律，探讨有关参数对煤柱产生冲击地压的影响、临界载荷随煤的强度σe、E/λ的变化规律，得到煤柱发生冲击地压现象的临界点。  相似文献   

低空急流形成发展的一种可能机制——重力波的惯性不稳定   总被引：5，自引：0，他引：5  

林永辉  廖清海  王鹏云 《气象学报》2003,61(3):374-378

当斜压大气在高空急流轴附近满足条件f(f-/y)＜0时,非地转运动激发出的重力惯性波将得到进一步的发展.此时,斜压大气的地转适应过程无法实现,非热成风和垂直环流之间将发生正反馈作用, 负的非热成风将激发并加强南部上升北部下沉的垂直环流,垂直上升流的加强将导致低层低压系统的发展和低层流场的辐合,使得低层低压系统南侧的气压梯度力增大,结果在辐合区南侧形成低空急流.此外,非热成风的分布对垂直环流和低空急流的形成发展也具有非常重要的作用.  相似文献   

Using Bayesian belief networks to analyse the stochastic dependence between interevent time and size of earthquakes     

C. Agostinelli  R. Rotondi 《Journal of Seismology》2003,7(3):281-299

The purpose of this article is to show how Bayesian belief networks can beused in analysis of the sequence of the earthquakes which have occurred in a region, to study the interaction among the variables characterizing eachevent. These relationships can be represented by means of graphs consistingof vertices and edges; the vertices correspond to random variables, whilethe edges express properties of conditional independence. We have examinedItalian seismicity as reported in two data bases, the NT4.1.1 catalogue and the ZS.4 zonation, and taken into account three variables: the size of thequake, the time elapsed since the previous event, and the time before the subsequent one. Assigning different independence relationships among these variables, first two couples of bivariate models, and then eight trivariatemodels have been defined. After presenting the main elements constituting a Bayesian belief network, we introduce the principal methodological aspects concerning estimation and model comparison. Following a fully Bayesian approach, prior distributions are assigned on both parameters and structuresby combining domain knowledge and available information on homogeneous seismogenic zones. Two case studies are used to illustrate in detail the procedure followed to evaluate the fitting of each model to the data sets andcompare the performance of alternative models. All eighty Italian seismogenic zones have been analysed in the same way; the results obtained are reportedbriefly. We also show how to account for model uncertainty in predicting a quantity of interest, such as the time of the next event.  相似文献