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991.
992.
根据前人对唐山地震破裂分布、地壳波速和粘性结构的研究,考虑局部应力场、孔隙流体压力和断层附近软介质的影响,计算了唐山地震产生的,投影到后续大余震断层面和滑动方向上的库仑破裂应力变化。结果表明,随后发生的滦县地震和宁河地震均发生在唐山地震产生的库仑破裂应力变化为正的区域。为研究唐山地震、滦县地震和宁河地震对后续小震的触发作用,根据前人对该地区构造应力场和地震破裂分布的研究,假定构造应力量值为10 MPa,求得了震源附近各处可能的小震震源机制。将上述3次地震产生的应力变化投影到可能的小震破裂面和滑动方向上,发现唐山地震、滦县地震和宁河地震产生的正库仑破裂应力变化的ldquo;蝴蝶rdquo;形分布与后续小震发生的空间分布具有较好的一致性,95%的余震发生在库仑破裂应力变化增加的区域,说明唐山地震序列中前面的大震对后续小震的发生起到了调制作用。该研究结果对大震后余震的危险性快速评估具有一定意义。如果大地震发生后能够快速确定详细的破裂分布和震源区域详细断层及滑动特性资料,本文方法可用来预测未来大余震的发震位置。 相似文献
993.
994.
基于TC35T模块在无人值守地震台站遥控电源开关的应用 总被引:1,自引:1,他引:0
雷击是造成地震台站观测仪器损坏、影响观测数据连续率和可靠性的重要因素。基于应用TC35T手机模块的遥控电源开关可实现对市电电源遥控“拉闸”和开启,以起到对无人地震监测点的防雷作用。介绍了TC35T模块的应用工作方式,遥控电源开关的硬件组成、程序设计思路,以及该遥控装置在无人值守台站四川攀枝花川-05井水化观测站的应用情况。认为,该遥控装置对地震台站,特别是无人值守台站的地震观测仪器,及其他领域带电工作的仪器设备免遭雷击,减少损失,提高运转连续率和工作质量,具有较高的实用价值和推广前景。 相似文献
995.
Zeng ZhiGang Wang XiaoYuan Zhang GuoLiang Yin XueBo Chen DaiGeng Wang XiaoMei 《中国科学D辑(英文版)》2008,51(2):206-215
The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48′W, lat.
12°42.30′N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides
are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges
in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%,
and 1.59%, respectively; they have high Cu (0.88%–1.85%) and Co (65×10−6−704×10−6) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al,
Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that
this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples
from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10−6–17.01×10−6), with a distinct negative Ce anomaly (0.12–0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element
(REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume
particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the
Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the
lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater
by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation
in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of
hydrothermal sulfide samples from the East Pacific Rise near 13°N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are
lower, and their Fe, Co, and Cu contents are higher.
Supported in part by the Pilot Project of Knowledge Innovation Project, Chinese Academy of Sciences (Grant No. KZCX3-SW-223),
and the Special Foundation for the Tenth Five Plan of COMRA (Grant No. DY105-01-03-1) 相似文献
996.
The bacterial community in deep subseafloor sediments at a depth of 230 cm from the western Pacific “warm pool” is studied
by construction of 16S rDNA clone library and PCR-RFLP (Restriction Fragment Length Polymorphism) analysis. The results indicate
that the bacterial community in these sediments is mainly composed of five groups: α-Proteobacteria, β-Proteobacteria, CFB group (Cytophaga / Flexibacteria / Bacteroides), Acidobacteria and gram positive bacteria, with a few genera detected in each group. The most abundant bacteria group is α-Proteobacteria, and the next is β-Proteobacteria. The dominant species in α-and β-Proteobacteria are Sphingomonas paucimobilis and Pseudomonas alcaligenes respectively. The CFB group is simply composed of members belonging to Flavobacterium. The gram positive bacteria are rich, and mainly consists of the genus Geobacillus. The analysis of bacterial community indicates that organic matter is still abundant in the subseafloor sediments at the
depth of 230 cm in the western Pacific “warm pool”. These bacteria in this deep biosphere may play an important role in the
nitrogen cycle of deep sea sediments at “warm pool”.
Supported by the National Key Basic Research Support Foundation of China (Grant No. G2000078500) and China Ocean Mineral Resources
R&D Association Project (Grant No. DY105-4-2-4) 相似文献
997.
The abundance curves derived from area proportions of brachiopods and Girvanella in the thin sections from the Yangdi section, South China, exhibits complex relationships during the Late Devonian Frasnian-Famennian
transition. The living activity of brachiopods such as grazing and borrowing did great damage to the growth of Girvanella. However, there was more to just a mere a survival competing relationship between them, Girvanella actually improved marine environments by oxygenating the dysoxic ambient sea-water through photosynthesis in the lower Kellwasser
Horizon. Profited from this improvement brachiopods’ abundance increased subsequently and suppressed Girvanella again. Nonetheless, without Girvanella’s photosynthesis, brachiopods were wiped out by the farther anoxic environments in the upper Kellwasser Horizon. The complex
relationships between Girvanella and brachiopods may be a key to unlocking the relationships between geomicrobes and metazoans in the geological overturn
periods.
Supported by NSFC Innovation Research Group Program (Grant No. 40621002), MOE Innovative Research Team Program (Grant No.
IRT0546), the National Natural Science Foundation of China (Grant Nos. 40472020, 40730209, 40802005 and 40872001) and SINOPEC
Project (Grant No. G0800-06-ZS-319) 相似文献
998.
999.
一个新的季风指数及其年际变化和与雨量的关系 总被引:46,自引:5,他引:41
作者按曾庆存等所定义的标准化风场季节变率(和利用新的资料重新作了计算,为与国外传统的和至今大多数学者的定义一致,取δ*=δ-2>0(即冬、夏风向差大于π/2)作为季风区,结果涵盖了迄今国内外所指出的全球所有季风区(但比曾庆存等算得的区域略为小些),尤其是热带季风区正处于冬季和夏季赤道幅合带(ITCZ)位置所夹的范围内.其后,用李建平和曾庆存建议的动态风场标准化季节变率δ*m=δm-2(δm形式上与δ相似,但依赖于年份m)作为各年季风指数,计算了各主要季风区区域平均的δ*m的年际变化,得到南亚夏季风和东亚夏季风自20世纪70年代中期起、南海夏季风自20世纪80年代起和西非夏季风自1967年起都有不同程度的长期减弱趋势,尤其以西非夏季风减弱最明显.西非夏季风指数和南亚夏季风指数与当地夏季雨量呈显著正相关,东亚夏季风指数与中国和东亚夏季雨量的空间分布有一定的统计相关结构,而南海夏季风指数则与全球各海区夏季降水和海平面气压异常有较好的大范围统计相关. 相似文献
1000.
不同平面直角坐标系的转换包括平移、旋转和尺度因子4个参数,当转换系数矩阵严重病态时,参数解不可靠。考虑到自由网平差中的重心基准条件与转换模型的相关性,通过附加重心基准条件消去两个平移参数来解决转换矩阵严重病态的问题,从而求出正确的坐标转换参数。用实例对该方法进行了验证。 相似文献