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961.
山东数字地震台网定位子台网 选取对定位结果的影响 总被引:1,自引:1,他引:1
选取山东及邻区4个不同区域的地震,分析“定位子台网”分布对地震定位精度的影响,研究“定位子台网”的选取规则.探讨两种台站分布情况下定位偏差、水平误差、拟合残差随空隙角、近台距离、远台距离的变化;定位偏差及水平误差与拟合残差的关系.结果显示,速报时选择4-9个分布相对合理的“定位子台网”参加定位,结果较好,使用水平误差估... 相似文献
962.
水轮机流道压力脉动诱发厂房振动分析 总被引:2,自引:0,他引:2
水轮机压力脉动是引起厂房内源振动的主要诱因,如何在振动系统中合理、准确地施加水力荷载的振源特性,是目前机组振动分析的主要难点.文中将压力脉动假定为简谐荷载,通过跟踪楼板的振动变化和共振校核确定机组的振源特性,采用有限元法精细模拟了水轮机流道压力脉动诱发的厂房振动问题,并结合电站特点提出振动控制标准的建议值,由此对振动进... 相似文献
963.
The temporal variability of 210Po and 210Pb was examined in the overlying water of the Zhubi Coral Reef flat to detect nutrient-like behavior of 210Po. Different mechanisms influencing their geochemical behaviors were observed. Excess 210Po relative to 210Pb revealed an additional input of 210Po other than in situ production from 210Pb. The 210Po input comes from the reef flat sediment through diffusion. The diffusion contributes 62% of the total 210Po. This diffusion of 210Po directly highlights its nutrient-like behavior. No input, but the slight removal, of 210Pb was observed. Fractionation factors indicate that particulate matter prefers to adsorb 210Po rather than 210Pb. In combination with particulate composition, 210Po diffusion was closely related to organic matter. These results reveal that 210Po might be a potential tracer for quantifying nutrient recycling in the Coral Reef system. 相似文献
964.
We propose a new quantitative determination of shear wave velocities for distinct geological units in the Bohemian Massif,
Czech Republic (Central Europe). The phase velocities of fundamental Love wave modes are measured along two long profiles
(~200 km) crossing three major geological units and one rift-like structure of the studied region. We have developed a modified
version of the classical multiple filtering technique for the frequency-time analysis and we apply it to two-station phase
velocity estimation. Tests of both the analysis and inversion are provided. Seismograms of three Aegean Sea earthquakes are
analyzed. One of the two profiles is further divided into four shorter sub-profiles. The long profiles yield smooth dispersion
curves; while the curves of the sub-profiles have complicated shapes. Dispersion curve undulations are interpreted as period-dependent
apparent velocity anomalies caused both by different backazimuths of surface wave propagation and by surface wave mode coupling.
An appropriate backazimuth of propagation is found for each period, and the dispersion curves are corrected for this true
propagation direction. Both the curves for the long and short profiles are inverted for a 1D shear wave velocity model of
the crust. Subsurface shear wave velocities are found to be around 2.9 km/s for all four studied sub-profiles. Two of the
profiles crossing the older Moldanubian and Teplá-Barrandian units are characterized by higher velocities of 3.8 km/s in the
upper crust while for the Saxothuringian unit we find the velocity slightly lower, around 3.6 km/s at the same depths. We
obtain an indication of a shear wave low velocity zone above Moho in the Moldanubian and Teplá-Barrandian units. The area
of the Eger Rift (Teplá-Barrandian–Saxothuringian unit contact) is significantly different from all other three units. Low
upper crust velocities suggest sedimentary and volcanic filling of the rift as well as fluid activity causing the earthquake
swarms. Higher velocities in the lower crust together with weak or even missing Moho implies the upper mantle updoming. 相似文献
965.
Regional climate change and local urbanization effects on weather variables in Southeast China 总被引:2,自引:0,他引:2
Ji Chen Qinglan Li Jun Niu Liqun Sun 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):555-565
This paper presents the analyses of regional climate change features and the local urbanization effects on different weather
variables over Southeast China. The weather variables considered are: daily mean (Tm), minimum (Tmin), and maximum (Tmax) near surface air temperature, diurnal temperature range (DTR), relative humidity (RH), and precipitation (P). With analysis
of two datasets (a station dataset for the period from 1960 to 2005 that is mainly used and a grid dataset for the period
1960–2000), this study reveals that the trends in the variations of these weather variables can be separated into two periods,
before and after 1984. Before 1984, there were no significant urbanization effects, and Tmin, RH, and P steadily increased but Tmax decreased, resulting in a considerable decrease in DTR and a slight decrease in Tm. After 1984, Tmin and Tmax increased considerably, and the urbanization influence on Tmin, but not Tmax, is observable. The urbanization effect causes an extra increasing trend in Tmin with a rate of about 0.6°C/decade and, accordingly, extra decreasing trends in DTR and RH. The analysis of the seasonal trends
reveals that the urbanization influence results in a near-uniform increase of Tmin for all four seasons and a strong decrease of RH in summer and autumn. Moreover, there is no significant change in P at the
annual scale and an increasing rate of 11.8%/decade in summer. With the urbanization influence, a considerable increase in
P is noticeable at the annual scale; specifically, the increasing rates of 18.6%/decade in summer and 13.5%/decade in autumn
are observed. 相似文献
966.
967.
分析认为宁波台ZK03井动水位与VS垂直摆倾斜仪出现的异常可能是印尼8.9和日本9.0级地震的同震响应.印尼8.9级地震后,动水位表现为地震波引起的脉冲和阶跃变化并抬高水位.垂直摆表现为形变波引起的脉冲和阶跃变化,EW向最大幅度约为408.328×10-3"的脉冲式向E振荡波,并向W出现阶跃变化;NS向最大幅度约为29... 相似文献
968.
Automatic phase picking is a critical procedure for seismic data processing, especially for a huge amount of seismic data recorded by a large-scale portable seismic array. In this study is presented a new method used for automatic accurate onset phase picking based on the proporty of dense seismic array observations. In our method, the Akaike's information criterion (AIC) for the single channel observation and the least-squares cross-correlation for the multi-channel observation are combined together. The tests by the seismic array observation data after triggering with the short-term average/long-term average (STA/LTA) technique show that the phase picking error is less than 0.3 s for local events by using the single channel AIC algorithm. In terms of multi-channel least-squares cross-correlation technique, the clear teleseismic P onset can be detected reliably. Even for the teleseismic records with high noise level, our algorithm is also able to effectually avoid manual misdetections. 相似文献
969.
AN Zhisheng WANG Ping SHEN Ji ZHANG Yixiang ZHANG Peizhen WANG Sumin LI Xiaoqiang SUN Qianli SONG Yougui AI Li ZHANG Yechun JIANG Shaoren LIU Xingqi WANG Yong 《中国科学D辑(英文版)》2006,49(8):851-861
1 Introduction in China, with an area of 4400 km2 and a drainage area With the advancement of global change study, peo- of nearly 29,660 km2[2]. Occurring at a “climatic triple ple are paying more and more attention to the conti- junction” among the East Asian monsoon, Indian nental environment (in which we reside), its evolution Monsoon and the Westerly Jet Stream, it lies in the and its future tendency. As a component of the global transitional belt of the east monsoonal humid areas sys… 相似文献