Trend,periodicity and abrupt change in streamflow of the East River,the Pearl River basin

The East River in the Pearl River basin, China, plays a vital role in the water supply for mega‐cities within and in the vicinity of the Pearl River Delta. Knowledge of statistical variability of streamflow is therefore important for water resources management in the basin. This study analyzed streamflow from four hydrological stations on the East River for a period of 1951–2009, using ensemble empirical mode decomposition (EEMD), continuous wavelet transform (CWT) technique, scanning t and F tests. Results indicated increasing/decreasing streamflow in the East River basin before/after the 1980s. After the early 1970s, the high/low flow components were decreasing/increasing. CWT‐based analysis demonstrates a significant impact of water reservoirs on the periodicity of streamflow. Scanning t and F test indicates that significantly abrupt changes in streamflow are largely influenced by both water reservoirs construction and precipitation changes. Thus, changes of streamflow, which are reflected by variations of trend, periodicity and abrupt change, are due to both water reservoir construction and precipitation changes. Further, the changes of volume of streamflow in the East River are in good agreement with precipitation changes. Copyright © 2012 John Wiley & Sons, Ltd.     

地震综合信息量S值在辽宁及邻近地区中强地震前变化特征研究

一个地震前兆观测异常所提供的地震信息一般由异常地点、异常变化量、异常持续时间以及异常完成后的延续有效时间等诸多因素所决定,因此提出了用于描述地震异常的前兆信息量S值。根据地震前兆异常信息量综合数学表达式为基础,充分结合平滑滤波、消周期及趋势项和从属函数等数据处理方法,对辽宁地区的22个前兆主要台项进行地震综合信息量S值的计算与提取。结果表明,S值综合时序曲线在辽宁及邻区(37°~44°N,117°~127°E)1980年以来的12次ML≥5.0地震震前均出现不同程度的高值异常(S值≥0.12),通常在高值异常出现后1~6个月内辽宁及邻近地区有发生ML≥5.0地震的可能;S值的空间扫描图像也在震中附近(约150 km范围内)出现高值异常集中区。     

Surface Microtextures of Slipping Zone Soil of Some Landslides in the Three Gorges Reservoir District and Their Significance

The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filam     

Nanotopography of synthetic and natural dolomite crystals

Examination with scanning electron microscopy (SEM) and scanning force microscopy (SFM) revealed etch pits, layers and islands on dolomite crystal faces synthesized from calcite in Ca‐Mg‐Cl solutions at 200 °C and a wide variety of natural dolomites. Layers are broad, flat structures bounded by steps less than 100 nm high and greater than 1 μm wide. Islands are rounded topographic highs <20 nm high and <200 nm wide. The nanotopography of synthetic dolomite changed from islands throughout most of the reaction to layers at 100% dolomite. Island nanotopography formed on both Ca‐rich and near‐stoichiometric dolomite. Analyses of reaction products from dolomite synthesis indicates that there are no SFM‐detectable products formed in <10 h. SEM‐detectable products formed in 15 h. X‐ray diffraction (XRD)‐detectable products formed in ≈18 h, and the reaction went to completion in ≈40 h. Based on SFM analyses, the induction period for dolomitization in these experiments accounts for ≈20% of the total reaction time necessary to dolomitize CaCO₃ completely under the experimental conditions used here. Island nano‐ topography is inferred to occur at higher degrees of supersaturation than layer nanotopography for three reasons. First, island nanotopography on synthetic calcite and gypsum forms at higher supersaturations than layer nanotopography. Secondly, island nanotopography formed in solutions with higher degrees of supersaturation with respect to dolomite. Thirdly, the greater surface roughness of a crystal face composed of islands compared with layers indicates that island surfaces have higher surface energy than layer surfaces. Therefore, the stability of island surfaces requires a higher degree of supersaturation. Because islands and layers form under a wide range of conditions, their presence provides broadly applicable criteria for evaluating relative degrees of supersaturation under which ancient dolomite formed. Comparison of synthetic dolomites with natural dolomites demonstrates (1) similar nanotopography on natural and synthetic dolomites and (2) both natural planar and non‐planar dolomite may have island nanotopography.     

太平洋牡蛎配子和精子入卵的扫描电镜观察及胚胎发育的初步研究

通过扫描电镜观察 ,太平洋牡蛎精子由头部、中段和尾段组成。精子全长约 2 1 .6μm ,尾段长约 1 8.2 μm ,末端观察到“针眼”样结构 ;头部最大处的直径约 2 .6μm ;中段直径约 1 .1 μm ;未成熟精子尾段中部出现膨大 ,该处直径约 0 .3μm。卵呈梨形 ;卵的直径约为 41 .9μm。卵表面有微绒毛组成的皱折结构 ,可见卵黄膜孔。卵质收回时 ,在卵表面卵柄处可见明显的树枝状结构。受精后 ,受精卵表面的卵黄膜剥离处可见较多数量的皮质小泡。在水温2 1 .2～ 2 3.5℃ ,精卵混合 34min时 ,释时出第 1极体 ;1h2 2min时 ,放出第 2极体 ;2 1h55min时 ,胚胎发育至初期D形幼虫。     

Dynamic Evolution of Precursory Field and Its Relation With the Group of Strong Earthquakes

Spatial scanning is done for two regions in Chinese Mainland,where displayed a denseprecursory network during 1994～1998.The two regions are the mid-southern segment of theNorth-south seismic belt(20°～35°N,95°～110°E)and North China(36°～42°N,110°～120°E).We took 0.5°×0.5°as a spatial window with a step of 0.25°and 4 months as atemporal window with a step of 1 month.For the two regions,the anomaly density is scannedfrom 1994 and 1995 respectively in the two regions.The precursory anomalies are all fromthe Division of Seismic Trend in China and the Division of Seismic Trend in the Capital Area,Center for Analysis and Prediction,China Seismological Bureau.A seismogenic tectonicmodel is introduced to explain the scanning results.In the model,the frictional strength ofthe focal sources is distributed randomly.After the boundary plate motion rate and all othergeological parameters are given,the stress of the sources in the system changesinhomogenously due to the variation of the frictional streng     

基于构造的地震活动参数扫描短期预测方法研究

应用山东省和江苏省地震局“九五”地质研究成果, 在华东地区共选择49条断裂和7个构造块体作为地震活动性研究的构造基础, 选用频度、 ΔT-T、 小震调制比3个参数, 对构造两侧各20 km宽度范围的地震资料进行参数时间扫描。 通过普查, 得到的构造优势映震距离为300 km; 得到了10个敏感构造及其映震特点。 通过对华东地区13个中强地震震例的构造异常的综合分析, 得到如下认识: ① 震前存在场的群体异常特征, 表明华东中强地震“前兆”是在构造应力作用下表现出的、 区域性的整体过程; ② 异常的构造常常分布在震中周围; ③ 地震常常发生在平静异常的构造附近; ④ 高频度异常常常发生在震中外围, 并常具有步进性; ⑤ 震中周围的构造在震前2～3年开始先后不断出现高频和平静异常, 平静后出现多处小震调制比高值是孕震中期向短期过渡的时间转折标志。     

河北地区中强震前异常演化特征分析

通过地震活动特征分析、 研究地震活动基本规律, 对于了解大地震的孕育过程及地震前兆有重要意义。 采用“RTL(Region-Time-Length)”算法和“区域网格点密集值”算法对河北地区中强震前的地震活动特征进行分析研究。 利用RTL算法对河北地区1970年以来的M_S5.0以上地震在时间和空间上进行回顾性检验, 以震例6年前地震目录为计算数据。 时间扫描结果显示, 4次地震震前地震活动平静, 1次地震震前地震活动增强。 空间扫描结果给出了震例震前三年以1年尺度滑动的扫描图像, 与时间结果对应相吻合。 区域网格点密集值算法所选资料与RTL算法相同, 对研究震例中的三次较大地震(M_L≥6.0)进行震前三年尺度滑动的空间扫描。 结果显示, 随着时间滑动, 截至发震前, 震中附近区域网格密集值逐渐减小, 趋于平静。 通过综合应用两种方法, 发现地震活动平静的低值点和地震活动增强的高值点对地震的发生有一定的指示意义。     

Topology of Rayleigh–Bénard convection and magnetoconvection in plane layer

ABSTRACT

The present study aims to link the dynamics of geophysical fluid flows with their vortical structures in physical space and to study the transition of these structures due to the control parameters. The simulations are carried in a rectangular box filled with liquid gallium for three different cases, namely, Rayleigh–Bénard convection (RBC), magnetoconvection (MC) and rotating magnetoconvection (RMC). The physical setup and material properties are similar to those considered by Aurnou and Olson in their experimental work. The simulated results are validated with theoretical results of Chandrasekhar and experimental results of Aurnou and Olson. The results are also topologically verified with the help of Euler number given by Ma and Wang. For RBC, the onset is obtained at Ra greater than 1708 and at this Ra, the symmetric rolls are orientated in/along a horizontal axis. As the value of Ra increases further, the width of the horizontal rolls starts to amplify. It is observed that these two-dimensional rolls are nothing but the cross-sections of three-dimensional (3D) cylindrical rolls with wave structures. When the vertically imposed magnetic field is added to RBC, the onset of convection is delayed due to the effect of Lorentz force on the thermal buoyancy force. The presence of 3D rectangular structures is highlighted and analysed. When the magnetically influenced rectangular box rotates about vertical axis at low rotation rates in magnetoconvection model, the onset of convection gets further delayed by magnetic field, which is in general agreement with the theoretical predictions. The critical Ra increases linearly with magnetic field intensity. Coherent thermal oscillations are detected near the onset of convection, at moderate rotation rates.     

皱纹盘鲍鳃的光镜和电镜研究

用光镜、扫描电镜和透射电镜观察了皱纹盘鲍鳃的组织学和超微结构.鳃叶上皮按结构与功能可区分为5个区带:前纤毛柱状上皮区、立方上皮区、侧纤毛柱状上皮区、呼吸上皮区及后纤毛柱状上皮区.侧纤毛是产生呼吸水流的重要动力来源.呼吸上皮区具大小不等的褶皱,上皮细胞高度仅约为～8 μm,具密集的微绒毛,其结构有助于气体交换.