湿大气中低涡暴雨系统发展东移的初步分析     

阮水根  程新田 《气象学报》1986,44(4):488-494

七十年代,谢义炳教授指出:湿大气动力学和干大气动力学特征有明显差异。结合我们的天气实践,注意到经常造成鄂北强降水的西南低涡处于对流层低层,在这一层次内不仅流场辐合明显,而且水汽丰沛,空气为强烈的对流性不稳定,这些因子对低涡的生消移动必然有较大的影响。本文的目的是,引入水汽因子后,通过简化涡度方程在湿斜压大气中的应用,并考虑湿静力稳定度σ_m既为P的函  相似文献   

云南地区上地幔各向异性研究   总被引：12，自引：3，他引：12  

阮爱国  王椿镛 《地震学报》2002,24(3):260-267

对云南23个数字地震台11次地震的SKS记录，采用理论切向分量与实测切向分量拟合的方法，确定了快S波的偏振方向和快、慢波之间的时间延迟．结果表明，除鹤庆台外，在各台都观测到了S波分裂现象；云南地区的快方向总体特征是北北东向，时间延迟变化范围为0.5～2.0ｓ．在地质构造复杂地区断层对分析的影响很大．分析表明，作为青藏高原与华南块体之间的过渡带，云南地区的S波快方向反映了印度板块向欧亚板块俯冲是该地区地球动力学的基本背景，而由于青藏高原隆起造成的康滇菱形块体的南东-南南东向运动是造成复杂构造、应力环境的重要因素．快方向与上地幔运动的方向存在差异，说明在云南地区低速层或者软流层的运动与地壳块体的运动之间存在着复杂的耦合作用，构造驱动力如同向北东方向张开的手掌．从时间延迟出发，推断各向异性层的厚度为60～225ｋｍ．其变化范围与低速层埋深的变化范围（104～260ｋｍ）相当，认为各向异性层顶面可能在地壳底部，也可能在低速层，且在不同地点是不相同的，这与云南及周边地区莫霍面变化剧烈有因果关系．进一步推断出上地幔的各向异性主要存在于岩石圈而不是整个上地幔．   相似文献   

城市社区中心空间特征及其影响要素研究——以杭州市西湖区为例     

阮一晨  刘声  李王鸣  章明宇 《地理科学》2021,41(1):74-82

以杭州市西湖区为实证,采用高德地图POI数据,通过DBSCAN聚类识别459个社区中心,从空间布局、组织形式、空间关联3方面入手刻画其空间特征,在此基础上通过Logistic回归判断中心数量、能级的影响因素,研究表明:① 社区中心分布呈现空间集聚性和“一区多片”的整体结构,具有圈层分布和道路亲缘性特征。② 社区中心存在“强-弱”的中心网络结构,在小尺度上则由强弱中心互补形成团簇,并在社区层面形成功能较为完整的网络结构。③ 社区中心内公共服务有引领性作用,能促进社区中心形成,且中心内设施具有同类集聚的特征。④ 常住人口总量是最主要的影响要素,道路分割、户籍比、平均高程、社区组织类型对中心的形成有显著意义,人口密度、公司企业数等对中心数量与能级有重要影响。  相似文献   

The Temporal Evolution of Shear wave Splitting and Geoelectrical Anisotropy During Yongdeng Earthquake     

Ruan Aiguo  Li Qinghe  Rong Dailu  Zhao Heyun 《中国地震研究》2001,15(2):134-145

Volume 15,Number 235INTRODUCTIONEddhquake PrePrecursors and study dthelr卜atures filedsignificance to eal’thqu让e prediction．heanlsotroPyPyfeature Is one dthe nPnPortant aspects dprecursors,while its study Isdbenefit totheunderstandingdthe evolutiondstressfield andtothe deterrmnatlonJthe selsmopnlc fanfaut．S、wavespitting based on the EDA model Is。e Of the most popular。thods to study the preen。cry vanatlonof stress ield before earthquake and has made gnat。hleve。ms(Crampin,e…  相似文献   

鸟类乐园——河南省罗山县董寨鸟类自然保护区     

阮祥峰 《湿地科学与管理》2000,(4):46-47

<正> 董寨鸟类自然保护区地处豫鄂两省交界的大别山北坡,罗山县最南部,总面积4.68万公顷。保护区内群山连绵起伏,地形复杂多变,地势南高北低,平均坡高15°,海拔从100米至840米,以主峰王坟顶(840米),灵山金顶(827米)为中心形成的两大山体群系构成了保护区的核心。 保护区在气候带上属暖温带向北亚热带过渡地带,具有典型的过渡性气候特征,其特点为:气候温和,雨量充沛,夏无酷署,冬无严寒。全年无霜期227天,年降水量1100—  相似文献   

Molecular cloning and characterization of a threonine/serine protein kinase lvakt from Litopenaeus vannamei     

阮灵伟  刘荣雕  徐洵  施泓 《中国海洋湖沼学报》2014,32(4):792-798

  相似文献   

基于自适应阈值的云团识别与追踪方法及个例试验   总被引：2，自引：0，他引：2  

蔡叔梅  阮征  陈钟荣 《气象科技》2011,39(3):332-338

利用FY-2系列静止气象卫星的IR1通道资料,开展对快速发展云团的识别与追踪研究.通过建立自适应亮温阈值的云团识别方法,获取云团的发生、发展、消亡的完整生命过程;基于两个连续红外图像的面积重叠法,处理云团追踪过程中的分裂和合并现象;提取有关云团的温度阈值、面积大小、移动速度、亮度温度、温度梯度等特征量,为开展云团演变的...  相似文献   

汶川8.0级地震前区域应力场动态研究   总被引：1，自引：0，他引：1  

程万正  张永久  阮祥  乔慧珍  张致伟 《中国地震》2011,27(3):215-225

利用成都、昆明遥测数字地震波形记录资料,研究大量小震震源机制解和视应力值,分析了区域应力场动态和视应力值的时-空分布.给出川青地块平均应力场方位的时间变化.川青地块平均主应力场的方位在汶川8.0级地震前出现明显扰动,同时,地块力轴张量的倾角变化也很明显.得出2006～2007年川青块体逆冲型地震比例偏高,汶川8.0级地震前区域中小地震震源错动类型发生变化的结果,与区域地形变的分析结果是一致的.根据地震波形全波段计算辐射能量,求得的视应力σapp值揭示区域视应力值的微动态起伏过程与区域主压应力场方位的转折类似,可用于地块蕴震物理过程的探索.从汶川8.0级地震前的中短期视应力σapp值的空间分布看,震中所在的龙门山断裂带是低应力分布区,而相对高视应力则分布在外围地区.这些图像可能揭示了汶川8.0级地震前中短期发震构造附近呈现的闭锁现象.  相似文献   

Selection of emergency shelter sites for seismic disasters in mountainous regions: Lessons from the 2008 Wenchuan Ms 8.0 Earthquake,China     

Qiang Liu  Xuejing Ruan  Pilong Shi 《Journal of Asian Earth Sciences》2011,40(4):926-934

In this paper, we use the 12 May 2008 Wenchuan Earthquake as a background event for analyzing and applying the principles of site selection of emergency shelters for a disastrous earthquake. Based on field investigations and analyses of remote sensing imagery, we identified the distribution of active faults and the locations of co-seismic surface rupture zones—areas in which buildings are at risk of intensive damage. It is important that emergency shelters are located outside of such vulnerable areas. One of the lessons learned from the Wenchuan Earthquake is that high fatality rates occur in areas without life-saving shelters. The principles that underlie the selection of emergency shelter sites are as follows: (1) keep far away from active fault zones, with the distance depending on the characteristics of the fault, including the nature of hangingwall and footwall structures; (2) disaster-mitigation strategies should be developed as a multi-dimensional system for the management of natural hazards, human activities, and urban expansion, involving keeping away from vulnerable slopes and establishing an early-warning system; (3) the accessibility of mountainous regions must be considered, including establishing small emergency shelters that house large numbers of people and covering regions with an uneven distribution of villages; and (4) government and law-making agencies in China must establish new earthquake design codes for buildings, emphasizing the importance of public facilities (including schools, collective welfare institutions, and medical facilities) as emergency shelters during disastrous earthquakes. The site-selection process requires an interdisciplinary approach involving seismologists, engineers, environmental and social scientists, emergency management personnel, and government officials. The parameters upon which the above principles are based can be qualitatively determined, thereby providing a valuable initial database for further quantitative analysis. The preliminary results and knowledge gained in the present paper can be used as a decision-making tool to support the government in earthquake-recovery and reconstruction programs. We also discuss practical examples of site evaluation in regions that suffered heavy damage during the Wenchuan Earthquake.  相似文献   

Biocarbonation of reactive magnesia for soil improvement     

Yang  Yang  Ruan  Shaoqin  Wu  Shifan  Chu  Jian  Unluer  Cise  Liu  Hanlong  Cheng  Liang 《Acta Geotechnica》2021,16(4):1113-1125

Acta Geotechnica - This paper presents a new microbial technique for soil improvement through microbially induced carbonate precipitation (MICP) incorporating with reactive magnesia cement (RMC)....  相似文献