柴达木盆地昆特依盐湖的地球化学演化与古气候变化

１９９０年用铀系年代学及古地磁对昆特依盐湖沉积物进行年代测定，探讨该湖区地球化学演化与古气候变化关系。结果表明，该区最老的盐层形成于早更新世晚期（大于７３０ｋａ），大量的盐类沉积则始于３００ｋａ左右；盐湖沉积物中元素含量变化主要受古盐度、矿物、类质同象和吸附控制；沉积物水溶Ｆ／Ｃｌ比值与古盐度成反比关系；该湖２０００ｋａ以来的古环境演变：盐层形成于干冷、偏酸性的氧化环境，泥岩层形成于湿暖、偏碱性的     

基于形态学和DNA条形码探讨“南鲳”物种有效性

众所周知鲳科鱼类均为重要的经济种类,在中国沿海仅见鲳属(Pampus)鱼类分布,而低鳍鲳属(Peprilus)和真鲳属(Stromateus)则分布于大西洋和东太平洋。本研究采用形态学和DNA条形码技术对海南、广西和广东水产品市场上出现的“南鲳”进行物种鉴定,同时下载该物种的COⅠ基因同源序列进行比较分析,并纠正GenBank中的错误序列。研究结果显示“南鲳”学名实为中间低鳍鲳(Peprilus medius),为冰冻进口货品,在我国沿海无该物种的分布报道,其与国内已知的6种鲳属鱼类在鳃耙、背鳍、臀鳍等外部形态上存在明显的差异,在COⅠ基因水平上与鲳属鱼类遗传距离为0.138,分化于中新世晚期。本研究可为水产品市场种类鉴定提供借鉴,也为鲳科鱼类的研究和海洋鱼类分类学提供基础数据和参考。     

Liquefaction macrophenomena in the great Wenchuan earthquake

On May 12, 2008 at 14:28, a catastrophic magnitude M 8.0 earthquake struck the Sichuan Province of China.The epicenter was located at Wenchuan (31.00°N, 103.40°E). Liquefaction macrophenomena and corresponding destruction was observed throughout a vast area of 500 km long and 200 km wide following the earthquake. This paper illustrates the geographic distribution of the liquefaction and the relationship between liquefaction behavior and seismic intensity, and summarizes the liquefaction macrophenomena, including sandboils and waterspouts, ground subsidence, ground fissures etc., and relevant liquefaction features. A brief summary of the structural damage caused by liquefaction is presented and discussed. Based on comparisons with liquefaction phenomena observed in the 1976 Tangshan and 1975 Haicheng earthquakes, preliminary analyses were performed, which revealed some new features of liquefaction behavior and associated issues arising from this event. The site investigation indicated that the spatial non-uniformity of liquefaction distribution was obvious and most of the liquefied sites were located in regions of seismic intensity Ⅷ. However, liquefaction phenomena at ten different sites in regions of seismic intensity Ⅵ were also observed for the first time in China mainland. Sandboils and waterspouts ranged from centimeters to tens of meters, with most between 1 m to 3 m. Dramatically high water/sand ejections,e.g., more than 10 m, were observed at four different sites. The sand ejections included silty sand, fine sand, medium sand,course sand and gravel, but the ejected sand amount was less than that in the 1976 Tangshan earthquake. Possible liquefaction of natural gravel soils was observed for the first time in China mainland.     

Ekman动量近似下中间边界层模式中的风场结构

发展了一个准三维的、中等复杂的边界层动力学模式，该模式包含了EKman动量近似下的惯性加速度和Blackadar的非线性湍流粘性系数，它进一步改进了Tan和Wu(1993）提出的边界层理论模型。该模型在数值计算复杂性上与经典Ekman模式相类似，但由于包含了Ekman动量近似下的惯性项，使得该模式比传统Ekman模式更近于实际过程。中详细地比较了该模式与其他简化边界层模式在动力学上的差异，结果表明：在经典的Ekman模式中，由于忽略了流动的惯性项作用，导致在气旋性切变气流（反气旋性切变气流）中风速和边界层顶部的垂直速度的高估（低估），而在半地转边界层模式中，由于高估了流动惯性项的作用，结果与经典Ekman模式相反。同样，该模式可以应用于斜压边界层，对于Ekman动量下的斜压边界层风场同时具有经典斜压边界层和Ekman动量近似边界层的特征。     

基于ACE的海量三维空间数据通信研究

三维可视化已成GIS发展的潮流,这必然会导致空间数据量的激增,通过集群系统和并行数据库系统可以很方便地解决海量数据的存储管理问题。但是,在海量环境下,一般数据库管理系统提供的查询接口,仍然难以满足实时三维场景可视化的速度需求。因此研究C/S模式下海量三维空间数据的高效调度成为三维GIS发展亟须突破的难点。在数据库服务器端和客户端之间加上应用服务器端,提供数据缓存、预调度等功能,减少服务器端磁盘I/O所带来的时间消耗,可以明显加速数据调度。本文系统分析了这种客户端/应用服务器端/数据服务器端模式下三维空间数据通信的难点和主要设计挑战,并针对三维GIS的数据访问特征,设计了一套能满足三维GIS实时调度的通信应用层协议。以ACE中前摄器框架为基础,结合线程池技术提出分层策略,搭建了海量三维空间数据的通信架构,它是一种面向对象的构架,可以方便地进行功能的定制和扩展。     

短脉冲激光在实验室天体物理方面的研究进展

随着啁啾脉冲放大技术(Chirped Pulse Amplification,CPA)的飞速发展,激光功率密度实现了飞跃式的提升,利用短脉冲激光开展实验室天体物理研究的条件日趋成熟.短脉冲激光与靶相互作用可以产生相对论粒子(正负电子、质子、中子等)和高能电磁辐射(X射线、γ射线),这些粒子和辐射的产生过程与天体中的某些...     

2000—2021 年影响山东的北上台风分类及降水落区分析

将2000—2021年影响山东的15个台风,按大尺度环流形势进行分类,以台风登陆之后500 hPa中纬度是否存在槽进行分类,可以分为3类：（1）中纬度有槽且形成闭合中心,台风与槽结合,在山东产生暴雨以上量级的降水;（2）中纬度只有高空槽,降水范围最大;（3）中纬度无明显槽脊,降水量和降水范围最小。以西太平洋副热带高压（简称“副高”）的位置分类,可分为3类：（1）副高西伸脊点过120°E且北部边缘过40°N,台风沿副高外围移动,降水最少;（2）副高西伸脊点不过120°E且北部边缘过40°N,高空槽与副高在中国沿海交汇,降水范围广,山东降水与台风位置有关。位置偏西,降水范围大;位置偏东,降水主要集中在山东半岛地区;（3）副高西伸脊点不过120°E且北部边缘不过40°N,台风环流中心较强,降水最强。以700 hPa环流形势分类,分为3类：（1）700 hPa有高压坝,降水范围最小;（2）700 hPa无高压坝,东北地区有冷涡,山东降水量和降水范围最大;（3）700 hPa无高压坝,中纬度存在大槽,降水量均可达大暴雨量级。     

1981—2013年四川省视程障碍类天气现象分析

利用四川省1981—2013年雾、轻雾、吹雪、雪暴、烟幕、霾、沙尘暴、扬沙和浮尘9种视程障碍天气现象资料,对其发生日数、发生概率和分布特征进行统计。结果表明:(1)各天气现象发生日数排序为:轻雾>雾>浮尘>霾>烟幕>扬沙>沙尘暴>吹雪>雪暴。(2)轻雾和雾年发生日数为分别为176d/a和29d/a,日发生概率分别为48%和8%,远高出其他天气现象。(3)季节变化方面,雾和轻雾主要出现在秋季和冬季;霾、吹雪和雪暴集中出现在冬季;浮尘发生春季;扬沙多发生在冬季和春季;而沙尘暴、烟幕主要发生在春季和秋季。(4)变化趋势上轻雾基本保持平稳;烟幕呈增加趋势;而雾、霾、沙尘暴、扬沙和浮尘呈下降趋势。(5)大气层结稳定、水汽充足、风速较小、人口集中和排放量较大,易于盆地雾、轻雾、霾和烟幕的形成;不合理利用水和土地资源,北方地区沙尘天气随冷空气南下,是沙尘天气发生的重要原因;而吹雪和雪暴均发生在冬季降雪量大且风速较大的川西高原。     

Vertical amplitude reduction of Rayleigh waves by a row of piles in a poroelastic half‐space

A row of rigid piles is addressed as the countermeasures for isolating Rayleigh waves in a poroelastic half‐space. The complex characteristic equations for Rayleigh waves are derived via Biot's theory and their existence conditions are given. The piles are modeled as Euler–Bernoulli beams with longitudinal displacements and the diffracted field by each pile is constructed only with Rayleigh waves. Six infinite linear systems of algebraic equations are obtained in terms of the equilibrium of forces and continuity of displacements at the pile–soil interfaces. The systems are subsequently solved in the complex least‐squares sense. The influence of certain pile and soil characteristics such as the permeability of poroelastic soil, spacing between the piles and length of the piles on the isolating performance of a pile barrier is investigated. Computed results show that the permeability of poroelastic soil displays a significant effect on the vertical amplitude reduction of Rayleigh waves. Copyright © 2009 John Wiley & Sons, Ltd.     

A unified linear theory of wavelike perturbations under general ocean conditions

A linearized instability analysis model with five unknowns was proposed to describe disturbance motions under general oceanic background conditions, including large-scale current shear, density stratification, frontal zone, and arbitrary topography. A unified linear theory of wavelike perturbations for surface gravity waves, internal gravity waves and inertial gravity waves was derived for the adiabatic case, and the solution was then found using Fourier integrals. In this theory, we discarded the assumptions widely accepted in the literature concerning derivations of wave motions such as the irrotationality assumption for surface gravity waves, the rigid-lid approximation for internal gravity waves, and the long-wave approximation for inertial gravity waves. Analytical solutions based on this theory indicate that the complex dispersion relationships between frequency and wave-number describing the propagation and development of the three types of wavelike perturbation motions include three components: complex dispersion relationships at the sea surface; vertical invariance of the complex frequency; and expressions of the vertical wave-number (phase). Classical results of both surface waves and internal waves were reproduced from the unified theory under idealized conditions. The unified wave theory can be applied in the dynamical explanation of the generation and propagation properties of internal waves that are visible in the satellite SAR images in the southern part of the China Seas. It can also serve as the theoretical basis for both a numerical internal-wave model and analytical estimation of the ocean fluxes transported by wavelike perturbations.