四川盆地云和降水观测科学试验设计与实践

2014—2017年四川地区开展了大范围云系观测科学试验。观测对象以盆地层状云系和积层混合云系为主,积状云(对流云)为辅。本文围绕试验目标、区域、观测要素、观测布局设计、观测方案设计、设备技术参数和典型个例等7个方面进行介绍,根据不同类型云系和降水变化特征,设计有针对性的观测方案,获得了不同类型云系和降水的多尺度连续性观测数据,为四川地区开展云和降水关系研究提供详实的综合型外场观测数据。层状降水云典型个例云高可达8km,云强核心部位的云雷达反射率可达28dBz,径向速度可达-6m·s~(-1),在0℃附近,反射率和退偏振因子LDR上有一条明显的亮带,表现为极大值,液态水主要集中于4.5km以下,随着雨强增大,液水含量增加,降水滴谱分布较窄,随着雨强减小,雨滴谱和速度谱变窄,但小粒径数浓度增加,说明对层状云雨强起主导作用的是雨滴直径,而不是数浓度;无降水层状云典型个例云层厚度为3.2km,云顶约为4km,云雷达反射率不超过0dBz,径向速度不超过5m·s~(-1),层状云内整层水汽含量和液水含量较为稳定,云中主要为液态粒子且粒径偏小、小粒径数浓度较高。     

基于位置微博的大风信息提取及应用

利用广东省广州市2017年1月1日至5月30日的大风信息和灾情数据,分析了大城市位置微博的时空特征,在此基础上采用关键词语意分析、风险等级映射、灾情权重值结合GIS热点分析的方法构建基于位置微博的大风信息提取架构,实现大风信息的提取,并利用个例进行验证。研究表明:本文提出基于位置微博的大风信息提取架构,对收集大风信息和灾情具有一定的实用价值。而位置微博信息本身具有及时性强、成本低、数据量大的优势,能作为一种大风信息提取的有效补充手段。     

Geochemical characteristics of Early Cretaceous source rocks in Boli Basin

The Early Cretaceous deposits are composed of important source rocks in Boli Basin. The types of the source rocks include black mudstones and coal (with carbonaceous mudstone). By the organic geochemical analysis methods, the authors discussed the organic petrological characters, abundance of organic matter, degree of maturity and the type of source rocks. The main micro-component of black mudstone is exinite or vitrinite, and the content of vitrinite is high in coal. The weathering of the outcrop is very serious. The abundance of organic matter in source rock reaches the poor to better rank. The major kerogens in mudstone are type-Ⅲ, type-Ⅱ2 and some type-Ⅱ1; the organic type of coal is type-Ⅲ. The thermal evolution of the source rocks in every structural unit is very different, from low-maturity to over-maturity. The depositional environment is reductive, which is good for the preservation of organic matter. The organic matter in source rocks is mainly from aquatic organisms and terrigenous input.     

福建及沿海地区地震活动力源探讨

综合地震震源机制解和地壳形变观测资料的研究, 求得福建及其沿海地区现代震源应力场, 认为这与台湾地区、 台湾海峡应力场相互衔接, 主压应力轴优势方位为NW-SE向, 力轴仰角较小, 应力场近于水平挤压, 形变场反映近期福建沿海亦受北西方向, 接近与海岸垂直的挤压力。 进一步分析该区域内的断裂构造特征和地震活动强度由东至西逐渐减弱的规律, 认为菲律宾海板块与欧亚板块的相互作用力不仅是台湾强震力源所在, 而且其影响向西扩展, 福建及其沿海地区地震活动主要力源仍然是来自这两大板块的相互作用力。     

中更新世气候转型时期南海生态环境的南北差异

中更新世气候转型在南海浮游有孔虫、氧同位素和其它生物记录上主要反映在900 ka BP前后发生高频率变化,特别是指示表层水骤然降温。北部冬季表层水温从24~25℃降至17~28℃,而南部也从26~27℃降至23~24℃。总的降温趋势与开放西太平洋一致,直接反映了西太平洋暖池在900 ka BP之后MIS22期间有明显的减弱。表层水大幅度降温还发生在后继的MIS 20、18、16几大冰期,说明主要冰期旋回周期由41 ka转变为100 ka经历了长达400 ka的过渡时期,并且冬季风增强也在过渡时期的后半段最明显。南海南北生物组合和δ18O值的差异,突出了中更新世气候转型期边缘海区南北气候梯度反差和冬季风在冰期增强的讯号。结论是：生态环境系统反应总体表现与冰期旋回一致的同时,还包含了独特的地区性系统演变特征。但是,南海—西太平洋地区在0.9 Ma BP前后表层海水盐度因东亚冬季风和海平面下降的定量变化,以及这些变化对气候转型时期海—气耦合过程和生态环境系统的影响,尚缺乏足够的资料和证据。     

Intraseasonal oscillation intensity over the western North Pacific:Projected changes under global warming

本文利用8个CMIP5模式的日资料,预估了RCP4.5和RCP8.5情景下全球增温达1.5℃和2.0℃时西北太平洋夏季30～60天和10～20天季节内振荡(ISO)强度的变化情况.大多数模式都认为,无论增温水平或情景如何,预估结果均显示从中南半岛南部到菲律宾以东的带状区域内ISO强度增加,并且关键气象要素背景的变化会对...     

A comparative study between China and U.S. on seismic design philosophy and practice of a long span arch bridge

This paper presents the first of a series of case studies on the seismic design of long span bridges （cable-stayed bridges, suspension bridges and arch bridges） under a cooperative research project on seismic behavior and design of highway bridges between the State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University and the Multidisciplinary Center for Earthquake Engineering Research, University at Buffalo. The objective of this series of case studies is to examine the differences and similarities on the seismic design practice of long span bridges in China and the U.S., to identify research needs and to develop design guidelines beneficial to bridge engineers in both countries. Unlike short to medium span bridges, long span bridges are not included in most seismic design specifications, mainly because they are location dependent and structurally unique. In this paper, an available model of a steel tied half through arch bridge with a main span of 550m in China is discussed. Analysis is focused on comparisons of the seismic responses due to different ground motions. Seismic design criteria and seismic performance requirements for long span bridges in both countries were first introduced and compared, and then three near field earthquake records with large vertical components were selected as the excitations to examine the seismic behavior and seismic vulnerability of the bridge. Results show that （1） the selected near field ground motions cause larger responses to key components （critical sections） of the bridge （such as arch rib ends） with a maximum increase of more than twice those caused by the site specific ground motions; （2） piers, longitudinal girders and arch crowns are more vulnerable to vertical motions, especially their axial forces; and （3） large vertical components of near field ground motions may not significantly affect the bridge＇s internal forces provided that their peak acceleration spectra ordinates only appear at periods of less than 0.2s. However, they may have more influence on the longitudinal displacements of sliding bearings due to their large displacement spectra ordinates at the fundamental period of the bridge.     

Report on 34 Ga SHRIMP Zircon Age from the Yuntaishan Geopark in Jiaozuo, Henan Province

1 Introduction According to recent researches, the North China Craton consists of three parts: the eastern block, western block and central zone (Zhao, 2001; Wilde et al., 2002). Paleoarchean continental blocks and zircon residuals have only been found in a few regions, such as Anshan, East Liaoning (Liu et al., 1992; Song et al., 1996; Wan et al., 2002, 2005), Caozhuang, East Hebei (Liu et al., 1992) and Xinyang, West Henan (Zheng et al., 2004), which are mainly distributed in the east…     

广州城区晚全新世环境变迁与人类活动

对广州市越秀区解放中路考古遗址剖面进行了年代学、岩性、硅藻和软体动物鉴定等研究,发现广州珠江北岸古城区南部在先秦时期为河道及河口湾湿地/洼地;因河流-河涌的淡水注入使河口盐度降低,故而沉积物中未见较高盐度的微体生物,仅发现了河口型咸水-半咸水硅藻;此时堆积的贝壳大多为淡水种,半咸水种少见,表明先秦(东周)时期,广州地区...     

面向野外地质调查工作的道路提取方法研究

为弥补传统的依靠管理组织、法律、经济、教育等进行对野外地质工作安全管理工作的不足,通过百度SDK采集GPS步行轨迹数据,基于单向GPS轨迹数据的特点,进行轨迹的分割分段处理.最后利用BP神经网络算法拟合道路,通过反复实验确定BP网络的参数配置信息.并以中国地质大学西区为研究区域,提取路网信息,验证算法的有效性和实用性....