Mid-Late Neoproterozoic rift-related volcanic rocks in China: Geological records of rifting and break-up of Rodinia

Early Cambrian and Mid-Late Neoproterozoic volcanic rocks in China are widespread on several Precambrian continental blocks,which had aggregated to form part of the Rodinia supercontinent by ca.900 Ma....     

Chaba (0417) 台风变性前后热力结构特征

运用美国NOAA-15极轨气象卫星高分辨率的AMSU探测资料, 结合NCEP/NCAR再分析资料和GMS-5气象卫星红外云顶亮温(TBB)资料, 对2004年Chaba(0417)台风(TC)变性前后的热力结构特征进行分析。发现变性前TC暖核结构呈对称分布, 在高空存在一强暖心; 变性后原TC对称暖心结构消失, 存在于温带气旋上空的相对暖区呈现出倾斜的非对称分布, 在高、低层各形成一弱的暖区中心, 锋面的斜压特性显著。通过热力结构对比, 进一步揭示出TC在向高纬度方向移动时, 与中纬度系统相互作用发生变性, 实质上是两个相继过程, 即热带气旋的消亡和温带气旋的生成发展。TC西侧高空干冷空气的入侵下沉, 破坏了其发展所需的水汽条件, 造成TC对称暖核结构的削弱和损毁。与此同时, 在TC残留区域, 由于空气较暖且存在气旋式环流, 暖空气在东侧呈气旋式上升, 与西侧高空入侵下沉的干冷空气形成偶极, TC暖气团与冷空气相交发展形成斜压的结果, 则为温带气旋的生成和发展创造了有利条件。     

环境干扰事件引起的“形变异常变化”

通过对山东泰安台形变观测受抽水、灌溉影响及烟台台形变观测受载荷影响的分析,认为同一台站的多套形变固体潮仪器"同步异常"的出现应成为判定异常发生的重要准则;对同一应变过程不同形变仪器的响应量级会有所不同,分量式应变仪对异常反映最有效,其次是伸缩仪。对几次"干扰异常"所揭示的问题进行了初步讨论,并在形变异常判定科学思路方面提出了一些建议。     

基于VAD技术的迭代法在实测多普勒速度缺测区域的填补研究

多普勒天气雷达径向速度场缺测区域的存在是影响速度二次产品算法精确度的重要因素,在实际风场为线性分布的假设条件下,文中详细介绍了一种基于VAD技术的迭代填补技术.在合理考虑迭代约束条件的情况下,应用实测多普勒速度数据,根据缺测区域类型随机制造非连续累积10°-180°缺口的缺测区域和连续累积10°-180°缺口的缺测区域...     

A new method of testing pile using dynamic P-S-curve made by amplitude of wave train

A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve. Foundation item: Key projects of the tenth Five-year Plan of Yunnan Province (documented Yunnan district [2002]54-02-02) and Geophysical Society of Yunnan Province.     

中国大陆1998～1999年地壳运动观测结果

介绍了中国地壳运动观测网络1998～1999年基准站GPS观测概况,简要介绍了用伯尔尼（Bernese）软件对GPS观测数据的处理结果,详细介绍了所获取的1998年９月初～1999年７月初基准网地壳运动,包括各基准站位移与网内各部分的应变．在所述观测期间,我国东部地区较为稳定．相对东部地区,西南部地区以向北运动为主,位移量约17ｍｍ,受北北东向挤压为主;西北部地区以北西向运动为主,位移量约11ｍｍ;而云南地区以向南运动为主,位移量约14ｍｍ．我国中部南北地震带则是一强烈的剪切变形带．网内最大主应变量为2.910-8．观测结果表明,印度板块向北挤压依然是影响我国地壳运动的主要因素．      

中国北方砂栖纤毛虫的空间分布及其驱动因素

为深入了解不同地理尺度因素对驱动微型生物群落空间结构的相对影响,本研究于2020年10月调查了中国北方14个砂质潮间带的砂栖纤毛虫群落。研究结果如下：（1）检获纤毛虫105种,隶属26目65属,按丰度优势依次为帆口目、小胸目和环毛目;（2）黄海、渤海两区域的环境因子存在显著差异,但纤毛虫群落组成趋于相似;（3）偏Mental分析显示,环境条件较空间距离在纤毛虫群落组成的驱动中更为重要,其中盐度、粒度和海滩坡度是解释纤毛虫空间分布的最优环境因子组合,而潮差和溶解无机氮含量是次要影响因子;（4）沿海区域微型生物的强扩散效应在一定程度上掩盖了环境异质性影响。综上,由于沿海生态系统中微型生物受到更少扩散限制,在空间分布格局的形成上,环境条件的影响比空间距离更重要。本研究为海洋微型生物地理学提供了基础数据,有助于在全球变化背景下制定沙滩管理和保护规划。     

Study of the Earth’s free core nutation by tidal gravity data recorded with international superconducting gravimeters

By stacking high-precision tidal gravity observations obtained with superconducting gravimeters at six stations in China, Japan, Belgium, France, Germany and Finland, the local systematical discrepancies in the parameter fitting, caused by atmospheric, oceanic tidal loading and the other local environmental perturbations, are eliminated effectively. As a result, the resonance parameters of the Earth’s free core nutation are accurately determined. In this study, the eigenperiod of free core nutation is given as 429.0 sidereal days, which is in agreement with those published in the previous studies. It is about 30 sidereal days less than those calculated in theoretical models (about 460 sidereal days), which confirms the real ellipticity of the fluid core of the Earth to be about 5% larger than the one expected in assumption of hydrostatic equilibrium. The quality factor (Q value) of free core nutation is given as about 9543, which, compared with those determined before based on the body tide observations, is much larger, but more close to those obtained using the VLBI observations. The complex resonance strength is also determined as (−6.10×10⁻⁴, −0.01 ×10⁻⁴)°/h, which can principally describe the deformation characteristics of an anelastic mantle.     

Experimental research on physical properties of saline soil subgrade filler in Chaerhan region

In order to improve the engineering stability of saline soil of high chloride content in the Chaerhan salt lake region, six typical characteristics saline soil samples were selected, and tests on their...     

Approximation approach to the SRM based on root decomposition in the simulation of spatially varying ground motions

The spectral representation method(SRM) is widely used to simulate spatially varying ground motions.This study focuses on the approximation approach to the SRM based on root decomposition,which can improve the efficiency of the simulation.The accuracy of the approximation approach may be affected by three factors: matrix for decomposition,distribution of frequency interpolation nodes and elements for interpolation.The influence of these factors on the accuracy of this approach is examined and the following conclusions are drawn.The SRM based on the root decomposition of the lagged coherency matrix exhibits greater accuracy than the SRM based on the root decomposition of the cross spectral matrix.The equal energy distribution of frequency interpolation nodes proposed in this study is more effective than the counter pith with an equal spacing.Elements for interpolation do not have much of an effect on the accuracy,so interpolation of the elements of the decomposed matrix is recommended because it is less complicated from a computational efficiency perspective.