1949年前中国的两个地震研究系统   总被引：1，自引：0，他引：1  

吴瑾冰 《山西地震》1997,(3):24-28

叙述了１９４９年前中国从事地震研究工作的２个系统。主要介绍了在蒋丙燃和竺可桢２位先生先后领导下由王应伟和金咏深等所做的工作。着重介绍了《近世地震学》和这一论著的主要观点。第２个是地质系统，介绍了翁文灏先生以及他在《锥指集》中对地震发生和预测方面的各种论点。  相似文献   

香港降水的短期气候预测   总被引：1，自引：0，他引：1  

简裕庚  周文  陈创买  温之平 《热带地理》2001,21(2):125-130

利用正规化周期回归分析方法和门限自回归理论对香港1853-1995年月降水资料进行了建模和拟合，并对1996年进行了预报试验，正规化周期回归拟合效果较好，对香港7个时距的试报准确率为71%，建立了7个时距的10年滑动平均序列的门限自回归模型，模型对序列拟合效果较理想，预报误差较小，试报准确率主国100%。  相似文献   

一非线性统计－动力气候模式及其降水预报试验     

郑建萌  曹杰  李敏  王宇 《高原气象》1996,(3)

在带有线性反馈的统计－动力气候模式的基础上，提出了一种非线性统计－动力气候模式。该模式的实质是用逐段线性化的统计－动力气候模式来描述气候系统的总体非线性变化特征。试验结果表明，该模式能更客观地预测气候变化  相似文献   

不同温度作用下砂岩热开裂的实验研究   总被引：16，自引：0，他引：16       下载免费PDF全文

左建平  谢和平  周宏伟  彭苏萍 《地球物理学报》2007,50(4):1150-1155

砂岩的热开裂研究具有广泛的工程背景，本文实时在线观察和研究了不同温度作用下平顶山砂岩的热开裂：温度低于150℃时，砂岩几乎不发生热开裂；温度从150℃升高到300℃过程中大量的热开裂发生.而不同的矿物成分发生热开裂的阈值温度不完全相同，因此热开裂的阈值温度或者阈值温度范围只具有统计意义.砂岩热开裂主要与矿物成分的热学与力学性质有关，除了受到矿物热膨胀不匹配及热膨胀各向异性的影响，更重要的还受到矿物颗粒形状的影响，如热开裂多发生在矿物颗粒的短轴方向、优势结晶取向、颗粒奇异界面等，且热开裂的分布具有随机性.实验还观察到砂岩表面微缺陷发生闭合的全过程，在冷却过程也有微裂纹形成等现象.  相似文献   

Multi-step SETARMA predictors in the analysis of hydrological time series   总被引：1，自引：0，他引：1  

Alessandra Amendola  Marcella Niglio 《Physics and Chemistry of the Earth》2006,31(18):1118-1126

The performance of the self-exciting threshold autoregressive moving average model in forecasting river flow data is investigated. Multi-step forecasts of two daily time series are generated through three different nonlinear predictors. The model adequacy to capture the main features of the data under study and its forecasting performance are analysed and discussed.  相似文献   

Using Chlorine Dioxide for Drinking Water Disinfection by the Application of the Chlorite/Chlorine Process     

Wido Schmidt 《洁净——土壤、空气、水》2004,32(1):48-60

Chlorine dioxide stock solutions for the disinfection of drinking water are made by the application of chlorite/chlorine process in many waterworks. In such cases the stock solution is always characterised by a mixture of chlorine and chlorine dioxide. The disinfection of waters of different origin with a mixture of chlorine dioxide and chlorine showed the formation of odours of different intensity. The reasons are the re‐formation of chlorine dioxide and the formation of odorous disinfection by‐products. Applying the chlorine dioxide for disinfection, its re‐formation caused by the reaction of chlorite with chlorine is the dominant reason of odour formation. When chlorine is used, the formation of odorous by‐products becomes more relevant. In order to quantify the sensitivity of water concerning odour, the odour indicator coefficient OI was defined. The decreased demand of chlorine dioxide by applying chlorine and chlorine dioxide in combination is recognised to be the key in order to avoid the formation of odour after the disinfection of drinking water with chlorine dioxide.  相似文献   

Double-thresholds in scour–fill processes and some implications in channel adjustment     

Jiongxin Xu 《Geomorphology》2004,57(3-4):321-330

Through an analysis of data collected from the Yellow River and its tributaries on the Loess Plateau of China, the phenomenon of double-thresholds in scour–fill processes of wide-range water-sediment two-phase flows has been shown. Thresholds located in non-hyperconcentrated flows may be called the lower threshold, and that in hyperconcentrated flows the upper threshold. This double-threshold phenomenon leads to complicated sediment transport behavior of heavily sediment-laden rivers. With an increase in suspended sediment concentration, the channel sediment delivery ratio increases initially and becomes higher than 1, followed by a decrease and finally becomes lower than 1 again.Controlled by the double-thresholds in the scour–fill processes, channel adjustment of the lower Yellow River is non-linear and complex. When the suspended concentrations were lower than the lower threshold or higher than the upper threshold, scour or bed downcutting was the dominant channel-forming process. Channel shape tends to be narrower and deeper, and the channel thalweg became more sinuous. When the suspended concentrations lay between the lower and upper thresholds, deposition of sediment was the dominant channel-forming process; channel shape tended to be shallower and wider, and channel thalweg became less sinuous.  相似文献   

INITIATION OF SHELL MOTION ON SAND BEDS: AN EXPERIMENTAL STUDY     

Subhasish DEY  Alok KUMAR 《国际泥沙研究》2002,17(4)

1 INTRODUCTION Bivalve shells are found in biologically productive coastal regions encompassing the surf zone, tidal entrance and estuarine waters near the entrances. An example of a beach composed exclusively of shells (about 97% of the surficial sedimentary material) is the beach at John o'Groats in Scotland (Raymond and Hutchins, 1932; Komar, 1976). Southern Gulf Coast of Florida in USA (Runsak et al., 1966; Austin, 1971) and the banks of Lower Medway estuary in England (Kirby,…  相似文献   

油页岩热破裂规律显微CT实验研究   总被引：12，自引：1，他引：11       下载免费PDF全文

康志勤  赵阳升  孟巧荣  杨栋  郤保平 《地球物理学报》2009,52(3):842-848

利用太原理工大学和中国工程物理研究院应用电子学研究所最新共同研制的μCT225kVFCB型高精度（μm级）CT试验分析系统,对油页岩从常温到600 ℃高温下的热破裂过程进行了显微观测和分析,揭示了抚顺油页岩的热破裂阈值温度为300 ℃附近.当温度低于300 ℃时,已可见到极少数较小的微裂隙出现,裂隙多发育于原生层理面以及硬质矿物颗粒的周围,形成的破裂面基本上都与层理面互相平行.当温度超过300 ℃,由于受到热分解化学反应的控制,裂隙的数量、长度和宽度剧烈增加,呈现广泛发育、集中爆发的特点,并使原有裂隙迅速延展和贯通,且裂隙面仍具有与层理面平行的特点,这是油页岩热破裂的典型特征;同时,也形成了许许多多垂直于层理方向的微小裂隙,小裂隙与大裂隙的搭接连通,形成了一个庞大的连通网络结构,从根本上提高了油页岩的渗流能力.  相似文献   

Effects of micro-topography on surface–subsurface exchange and runoff generation in a virtual riparian wetland — A modeling study     

S. Frei  G. Lischeid  J.H. Fleckenstein 《Advances in water resources》2010

In humid upland catchments wetlands are often a prominent feature in the vicinity of streams and have potential implications for runoff generation and nutrient export. Wetland surfaces are often characterized by distinct micro-topography (hollows and hummocks). The effects of such micro-topography on surface–subsurface exchange and runoff generation for a 10 by 20 m synthetic section of a riparian wetland were investigated in a virtual modeling experiment. A reference model with a planar surface was run for comparison. The geostatistically simulated structure of the micro-topography replicates the topography of a peat-forming riparian wetland in a small mountainous catchment in South-East Germany (Lehstenbach). Flow was modeled with the fully-integrated surface–subsurface code HydroGeoSphere. Simulation results showed that the specific structure of the wetland surface resulted in distinct shifts between surface and subsurface flow dominance. Surface depressions filled and started to drain via connected channel networks in a threshold controlled process, when groundwater levels intersected the land surface. These networks expanded and shrunk in a spill and fill mechanism when the shallow water table fluctuated around the mean surface elevation under variable rainfall inputs. The micro-topography efficiently buffered rainfall inputs and produced a hydrograph that was characterized by subsurface flow during most of the year and only temporarily shifted to surface flow dominance (> 80% of total discharge) during intense rainstorms. In contrast the hydrograph in the planar reference model was much “flashier” and more controlled by surface runoff. A non-linear, hysteretic relationship between groundwater level and discharge observed at the study site was reproduced with the micro-topography model. Hysteresis was also observed in the relationship between surface water storage and discharge, but over a relatively narrow range of surface water storage values. Therefore it was concluded that surface water storage was a better predictor for the occurrence of surface runoff than groundwater levels.  相似文献