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排序方式: 共有3813条查询结果,搜索用时 62 毫秒
61.
SMA-MR复合型阻尼器 总被引:5,自引:0,他引:5
利用形状记忆合金超弹性、形状记忆特性和MR液的材料特性,提出了SMA-MR复合阻尼器,建立了阻尼器的理论模型。通过输入正弦波得到小震、大震时相应的滞回曲线,并对一单层框架进行输入El Centro地震波下的减震效果分析,比较了SMA-MR阻尼器、仅有SMA和仅有MR作用下的减震效果。结果表明,所设计的SMA-MR阻尼器具有卓越的阻尼性能,对大震、小震的控制实现了自适应的智能性。 相似文献
62.
63.
2001年四川雅江6.0级地震序列的破裂特征及发震构造 总被引:1,自引:0,他引:1
2001年雅江地震序列(主要地震是2月14日的Ms5.1和2月23日的Ms6.0地震)是四川地区近13年来的重要地震。选择2001年1月1日~6月30日期间,四川地震台网至少5个清晰的初动到时所记录的雅江地震序列中88次地震,并对其作了重新定位,对其中较大的13次地震用四川地区地震台网P波初动资料作了震源机制解。88次地震震源深度分布在2~16km,优势深度为9~llkm。前震、5.1级地震及其余震、6.0级地震及余震都紧邻孜河断裂分布,且按时段划分的震中优势分布方位与孜河断裂走向都是北西向。根据雅江地区近期大地形变场物质运移方向,选定了震源机制解的破裂面。13次较大地震震源机制解的主压应力P轴具有较大的垂向分量,水平投影方向为南东;地震类型都是左旋、走滑一正断型或正断一走滑型;大部分地震破裂面走向为北西一南东,倾向南西。根据前震、5.1级地震及其余震、6.0级地震及其余震震中优势分布方位,以及大多数较大地震破裂面走向和倾向,认为穿过震区的走向北西、倾向南西的孜河断裂是这次雅江地震序列的发震断裂。 相似文献
64.
本文通过联剖、电测深、磁法和测温法等综合工作成果,分析、推断出汤上屯热水构造的产状、性质和热水出露条件,圈定出了热水分布范围. 相似文献
65.
Yong-Fei Zheng Yuan-Bao Wu Fu-Kun Chen Long Li 《Geochimica et cosmochimica acta》2004,68(20):4145-4165
Oxygen isotope analysis and U-Pb dating were carried out on zircons from granite, granitic gneiss and eclogite in the Dabie-Sulu orogenic belt of east-central China. The results show a wide variation in zircon δ18O values from −10.9 to 8.5‰. Most of the values are lower than normal mantle zircon and almost half have prominently negative values. The low δ18O zircons have protolith ages of 700 to 800 Ma and metamorphic ages of 205 to 250 Ma, respectively. Fluid availability within the metaigneous rocks dictates the extent of metamorphic recrystallization and overgrowth. The igneous zircons have preserved their magmatic zoning and middle Neoproterozoic U-Pb age during the Triassic metamorphism, indicating low fluid availability. Widespread low δ18O values are identified in the magmatic zircons of middle Neoproterozoic age, within an outcrop area of over 20,000 km2 along the northern edge of the South China Block. The low δ18O zircons record the presence of large volumes of low δ18O igneous rocks that were derived from remelting of meteoric-hydrothermally altered rocks at some time between 700 and 800 Ma.The U-Pb ages for metaigneous protoliths and granites are correlated not only with the timing of rifting accompanying the breakup of Rodinia, but also with contemporary glacial deposits in the South China Block at paleolatitudes of 30 to 40°N. Melting of glacial ice and snow is suggested, instead of the direct involvement of meteoric water, to produce the low δ18O fluid with oxygen isotopic signatures like the cold-climate meteoric water. The rifting created conditions favorable to anatexis of meteoric-hydrothermally altered rocks. Glaciated regions supplied copious water for the water-rock interaction during magma emplacement along rifting zones. Both rifting and glaciation favored the generation of the low δ18O magmas in the region. The low δ18O zircons are thus interpreted to have crystallized from the low δ18O magmas of middle Neoproterozoic age, and onset of the generation of low δ18O magmas in the northern margin of the South China Block is estimated to occur at about 758 ± 15 Ma. The large-scale remelting of hydrothermally altered crust not only results from repetitive emplacement of mafic magmas along the rifting zones with protracted episodes of water-rock interaction, but also involves rift systems that rapidly introduce large volumes of fluid through confined pathways and traps in a short space of time in response to tectonic triggers. Occurrence of the large-scale 18O depletion during the middle Neoproterozoic may be a manifestation of the cold paleoclimate related to the snowball Earth event. 相似文献
66.
论数字城市工程及其技术体系 总被引:16,自引:0,他引:16
分析了数字城市的内涵 ,基于数字工程思想 ,总结了数字城市的工程结构与技术体系 ,进而阐述了数字城市的意义与建设策略。 相似文献
67.
提出了符合OpenGIS规范的二维地理信息系统组件软件MapManager的设计思想 ,介绍了MapManager的设计过程 ,并对其不足和进一步研究方向进行了讨论。 相似文献
68.
以《全国小震目录》(1965年1月1日~2002年lO月31日)和《四川地震台网快报目录》(2002年11月1日~2003年9月30日)为基础资料,研究了川滇地区地震活动性发展变化的主要特征,并提出“单断裂强震区”和“多断裂强震区”概念。发现川滇地区主要单断裂强震区在发生一些强震之后,已经陆续进入地震平静时段,近期发生强震的能力明显减弱。与此同时,“滇西南”、“龙陵-腾冲”、“丽江-武定”地区分别在较短时段内发生多次强震,表明这几个多断裂强震区陆续进入活跃时段,成为1984年以来川滇地区的地震主体活动区域。多断裂强震区具有区内中小断裂汇集、地质构造复杂、地震活跃时段多次出现、在同一活跃时段内又具有活跃小段与小段间距的小段组合形式等特征。对已有的和可能新生的多断裂强震区进行早期判定,以及对活跃时段、小段组合进行动态跟踪,对于川滇地区地震预报具有重要意义。 相似文献
69.
A precise monitoring of snow surface height in the region of Lambert Glacier basin-Amery Ice Shelf,East Antarctica 总被引:2,自引:0,他引:2
I.Allison 《中国科学D辑(英文版)》2005,48(1):100-111
The net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a one-year record of hourly snow-height measurements at LGB69 (70°50'S, 77°04'E, 1850 m a.s.l.). east side of Lambert Glacier basin (LGB), and 4 year record at G3 (70°53'S, 69°52'E, 84 m a.s.l.), Amery Ice Shelf (AIS). The measurements were made with ultrasonic sensors mounted on automatic weather stations installed at two sites. The snow accumulation at LGB69 is approximately 70 cm. Throughout the winter, between April and September, there was little change in surface snow height (SSH) at the two sites. The negative SSH change is due to densification at LGB69, and is due to both ablation and densification at G3. The strongest accumulation at two sites occurred during the period between October and March (accounting for 101.6% at LGB69), with four episodic increasing events occurring during 2002 for LGB69, and eight events during 1999-2002 for G 相似文献
70.
The seasonal and interannual variations of Beijing urban heat island (UHI) are investigated in this paper using the temperature data from 1960 to 2000 at 20 meteorological stations in the Beijing region, and then the relationship between the intensity and spatial scale of UHI and Beijing urbanization indices is analyzed and discussed. Main conclusions are the followings. First, Beijing UHI shows obvious seasonal variations, and it is strongest in winter, next in spring and autumn, and least in summer. The seasonal variation of the UHI mainly occurs in the urban area. The UHI intensity at the center of Beijing is more than 0.8℃ in winter, and only 0.5℃ in summer. Second, the intensity of Beijing HUI exhibits a clear interannual warming trend with its mean growth rate (MGR) being 0.3088℃/10 a. The MGR of HUI is largest in winter, next in spring and autumn, and least in summer, and the urban temperature increase makes a major contribution to the growth of HUI intensity. Third, since the Reform and Opening, the urbanization indices have grown several ten times or even one hundred times, the intensity of HUI has increased dramatically, and its spatial scale also expanded distinctively along with the expansion of urban architectural complexes. Fourth, the interannual variation of urbanization indices is very similar with that of HUI intensity, and their linear correlation coefficients are significant at a more than 0.001 confidence level. 相似文献