分布式地震应急救援态势标绘系统

地震现场救援要素众多,部署分散,为了统一管理救援要素,综合展示救援态势,设计一种基于B/S架构的地震应急救援态势标绘系统,采用Google Maps API v3实现前端Web GIS功能,加载谷歌地图,标绘震情灾情和救援要素信息,通过AJAX方式与服务器端进行数据交互,保存要素信息或者获取服务器端数据,系统设计聊天室功能,登录用户可以在线实时交流。本系统对使用环境要求低,支持多种移动终端,适合地震现场人员使用,实现了分布式要素标绘功能,是地震现场救援行动的有效辅助决策工具。     

Levels and distribution of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes in surface sediments from the Yellow River Delta wetland of China

The levels and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) of surface sediments in the Yellow River Delta wetland had been investigated. The concentrations of TBC and ∑ HBCDs ranged from 0.20 to 29.03 ng·g^? 1 dw and below limits of detections (LODs) to 20.25 ng·g^? 1 dw. The average composition profile of three HBCDs isomers were 10.1%, 6.1% and 83.8% for α-, β- and γ-HBCD, respectively. Moreover, correlation analysis indicated there are similar sources among three isomers and positive correlations between total organic carbon (TOC) content and concentrations of TBC and HBCDs. The mass inventory of TBC,α-, β-, γ-HBCD, ΣHBCDs in surface sediments of Yellow River Delta wetland were estimated about 725.50, 72.76, 44.29, 548.34, 665.39 kg. Therefore, further investigations on potential human health and environmental risk assessments of TBC and HBCDs were needed.     

垂距法与道格拉斯-普克法删除冗余顶点效率的比较

在计算机地图制图和地理信息工程等领域,通常要对线要素和面要素边界几何数据中所包含的冗余顶点进行删除,以达到减少存储开销、提高处理效率和改善图形可视化效果等目的。为了满足人们选择一种快速删除线要素冗余顶点算法的需要,在简要介绍目前常用的两种线要素压缩算法——垂距法和道格拉斯-普克法的原理及特点的基础上,对利用这两种算法实施冗余顶点删除处理的效率进行实例测试与比较。     

A modified domain reduction method for numerical simulation of wave propagation in localized regions

A modified domain reduction method(MDRM) that introduces damping terms to the original DRM is presented in this paper. To verify the proposed MDRM and compare the computational accuracy of these two methods, a numerical test is designed. The numerical results of the MDRM and DRM are compared using an extended meshed model. The results show that the MDRM significantly improved the computational accuracy of the DRM. Then, the MDRM is compared with two existing conventional methods, namely Liao's transmitting boundary and viscous-spring boundary with Liu's method. The MDRM shows its great advancement in computational accuracy, stability and range of applications. This paper also discusses the influence of boundary location on computational accuracy. It can be concluded that smaller models tend to have larger errors. By introducing two dimensionless parameters, φ_1 and φ_2, the rational distance between the observation point and the MDRM boundary is suggested. When φ_1 2 or φ_213, the relative PGA error can be limited to 5%. In practice, the appropriate model size can be chosen based on these two parameters to achieve desired computational accuracy.     

Seismic effectiveness of tuned mass dampers considering soil–structure interaction

This paper presents how soil–structure interaction affects the seismic performance of Tuned Mass Dampers (TMD) when installed on flexibly based structures. Previous studies on this subject have led to inconsistent conclusions since the soil and structure models employed considerably differ from each other. A generic frequency-independent model is used in this paper to represent a general soil–structure system, whose parameters cover a wide spectrum of soil and structural characteristics. The model structure is subjected to a stationary random excitation and the root-mean-square responses of engineering interest are used to measure the TMD's performance. Extensive parametric studies have shown that strong soil–structure interaction significantly defeats the seismic effectiveness of TMD systems. As the soil shear wave velocity decreases, TMD systems become less effective in reducing the maximum response of structures. For a structure resting on soft soil, the TMD system can hardly reduce the structural seismic response due to the high damping characteristics of soil–structure systems. The model structure is further subjected to the NS component of the 1940 El Centro, California earthquake to confirm the TMD's performance in a more realistic environment. Copyright © 1999 John Wiley & Sons Ltd.     

乌江磷浓度与通量变化及来源解析

磷(P)是长江流域备受关注的污染物。乌江是长江八大支流之一,位于三峡水库近库尾江段。武隆断面是乌江入长江控制断面。对1998—2019时期武隆断面径流量、悬浮泥沙浓度(SS)与输沙量、磷浓度与通量(包括总磷(TP)、溶解态磷(DP)和颗粒态磷(PP))年际变化及季节特征进行研究,并基于河流基流分割原理对磷的来源进行了解析。结果表明,(1)1998—2019年,乌江武隆断面径流量在一定幅度内上下波动,而悬浮泥沙浓度和输沙量下降剧烈。(2)22年来,乌江TP和DP浓度与通量总体上呈先升高后下降的趋势,2009—2013年为磷污染峰值期,TP和DP浓度与通量远高于其它时期。(3)2007年是一个重要的时间节点,该节点前,TP的赋存形态以颗粒态为主,颗粒态磷在总磷中的占比均值为65%;该节点后,TP的赋存形态转变为以溶解态为主,颗粒态磷占比均值下降为16%,相应地,溶解态磷占比由35%上升为84%。水沙条件改变是磷形态发生显著变化的主要驱动力,磷污染程度亦是磷形态变化的重要影响因素。(4)磷通量在年内的季节分布发生了显著变化,丰水期磷通量减少,枯水期磷通量增加。(5)1998—2012、2009—2013和2014—2019年3个时期点源负荷占比分别为23.5%、36.8%和62.1%,呈增加趋势。(6)建议制定适宜的总磷控制目标,结合目前所存在的磷污染风险点,进一步强化监管,侧重源头治理。     

川滇地区重力异常的小波分解与解释

利用小波变换方法对四川云南及周围地区的布格重力异常进行分解. 在计算中选用具有正交完备性并有较好对称性及较高消失矩的小波函数把重力异常分解为两部分. 用功率谱方法对分解后异常进行分析,可知其分别表示地壳内部和更深部的密度变化. 两部分异常显示出川滇地区深部与浅部的构造差异. 浅层重力异常的密度填图表明:① 四川盆地地壳密度较高,松潘——甘孜造山带密度较低;② 康滇菱形块体的密度是不均匀的;③ 康滇菱形块体的边界断裂具有不同的密度特征,显示出不同的构造性质. 深部重力异常的密度填图显示出与浅部相似而又不同的密度分布特征,表明川滇地区浅部与深部构造作用有所不同,两者之间可能是不完全解耦关系. 本文结果还表明,地震分布不仅受断裂构造控制,也与深部密度变化有关.      

俄、蒙、中交界7.9级地震

2003年9月27日19时33分,在俄、蒙、中边界地区发生了Ms7．9地震,新疆阿尔泰地区强烈有感,地震造成经济损失7600万元人民币。文章对此次地震的基本参数、震源机制作了概述,并用遥感资料对地震的构造环境和破裂过程进行了初步分析。     

亚洲大陆主要活动块体的现今构造应力数值模拟

亚洲大陆晚新生代和现代构造变形以活动地块为主要特征,表现为在统一构造格局下不同地块间具有不同的运动方式和速度。为了研究这些具有不同运动学性质块体间的相互作用以及构造变形特征,基于亚洲大陆的总体构造格局构建了二维有限元模型。根据模拟结果,对比已知GPS数据、震源机制解以及地质调查数据等,定量分析了大陆内部主要活动地块构造应力场的分布特征,并探讨了影响亚洲大陆现今构造变形特征的主要因素。结果表明：在我国的西部陆块内,由于周边一系列近EW向弧形活动构造带的存在,导致其内部次级块体运动速率的衰减,从而进一步导致应力环境的变化,由青藏中部的挤压-拉张环境逐渐转变为塔里木、天山地区的完全挤压环境;在西伯利亚地块和印度板块的联合挤压作用下,华北地块上地壳的应力表现为较弱的挤压环境,而在该种应力环境下块体内部伸展构造的成因很可能与其深部的动力学环境有关;华南地块的运动方向与台湾造山带相反,从而形成一个秦岭-大别造山带以南的较强烈的挤压-拉张区;在印度-澳大利亚板块和菲律宾俯冲板块的联合挤压作用下,巽他地块作为华南地块和印支地块的逃逸窗口,表现出以婆罗洲、南海为中心近圆弧形的弱挤压区以及环绕挤压区外缘挤压-拉张区的应力分布特征。     

Genetic diversity and population structure of Eleutheronema rhadinum in the East and South China Seas revealed in mitochondrial COI sequences

Eleutheronema rhadinum is a potential commercial fisheries species and is subject to intense exploitation in China. Knowledge on the population structure of E. rhadinum in Chinese coastal waters, which is important for sustainable exploitation and proper resource management, is lacking. In the present study, the genetic diversity and population structure of E. rhadinum were evaluated using a 564-base pair fragment of the mitochondrial cytochrome c oxidase subunit I （COl） gene. A total of 76 specimens were collected from three localities around the East （Qidong and Zhoushan） and South China Seas （Zhuhai）. Among these individuals, nine polymorphic sites were detected and 1 l distinct haplotypes were defined. High levels ofhaplotype diversity （h=0.759i0.035） and low levels of nucleotide diversity （re=0.001 98i0.003 26） were observed in these populations, Hierarchical analysis of molecular variance （AMOVA） indicated that 96.72% of the genetic variation occurred within the populations, whereas 3.28% occurred among populations. No significant genealogical branches or clusters were recognized on the neighbor-joining tree. Intra-group variation among populations was significant （~0~t=0.032 85, P〈0.01）. These results suggest that E. rhadinum populations in the East and South China Seas have developed divergent genetic structures. Tests of neutral evolution and mismatch distribution suggest that E. rhadinum may have experienced a population expansion. The present study provides basic information for the conservation and sustainable exploitation of this species.