应用新安江-海河模型研究下垫面变化对设计洪水的影响   总被引：1，自引：1，他引：0  

钟栗  姚成  李致家  黄鹏年 《湖泊科学》2015,27(5):975-982

为了探明流域产汇流参数变化特征及其演变机理,分析流域下垫面条件变化对设计洪水的影响.通过新安江海河模型研究卫河流域代表区下垫面变化情况,采用综合线性权重法对元村集站设计洪水资料系列进行一致性修正.结果表明:自由水蓄水容量、河网水流退水系数、地表填洼蓄水能力和地下水库出流初始水深这4个参数在1980年后都变大,可见代表区下垫面1980年前、后发生了明显的变化,导致流域内径流量大幅减少;合河—新村—五陵区间在1980年前15场洪水和1980年后32场洪水的预报径流深合格率都超过80%,达到乙等精度;元村集站最大5日洪量修正后比修正前平均减小27.1%;最大15日洪量修正后比修正前平均减小25.4%;最大30日洪量修正后比修正前平均减小23.0%.本研究可为水利工程的建设规模的确定提供科学依据,保障地区的防洪安全,满足人民生活和生产用水需求.  相似文献   

地磁绝对子夜均值年变化量空间分布特征     

孙贵成  胡秀娟  丁成  李文军  孙澎涛  张玉林  相传芳 《地震地磁观测与研究》2017,38(5):62-65

选用中国21个地磁基准台站2011年的绝对子夜均值数据,分析D、H、Z分量年变化量空间分布特征。结果显示,各分量年变化量等值线分布比较均匀,其中:D分量年变化量等值线大致沿南北向分布,零经线附近台站年变化量较小;H分量年变化量等值线大致呈U型分布,且中心点位于甘肃省;Z分量年变化量等值线沿纬线方向,随纬度减小而增大。  相似文献   

Difference between static and dynamic angle of repose of uniform sediment grains     

Nian-Sheng Cheng  Kuifeng Zhao 《国际泥沙研究》2017,32(2)

In the investigation of sediment transport, it is necessary to differentiate various definitions of angle of repose (AoR) available in the literature. The static AoR, composed of upper and lower angle of slope, forms just before and after slope instability, while the dynamic AoR can be observed when sediment grains are moving continuously down an inclined plane. In the present study, a series of laboratory experiments was conducted to measure static and dynamic angle of repose for uniform natural sedi-ments with median diameter of 0.28–4.38 mm. The results show that the different slope angles have different characteristics. The upper and dynamic AoR increase slightly with increasing grain diameter, while the lower AoR is not sensitive to changes in sediment size and may assume a constant value. The average of the upper and lower AoR is equivalent to the dynamic AoR, and the difference between them increases with increasing grain diameter. The present study suggests that the different angles of repose should be treated with caution when applying in investigations of bedload transport, dune migration and local scour development.  相似文献   

利用模拟退火法反演大陆地震位置     

窦立婷  成诚  李云  胡代明 《地震地磁观测与研究》2017,39(1):31-35

为了精确得到大陆地震震源位置,利用模拟退火法对大陆地震参数进行反演,并对改变算法中相关参数后的反演结果进行分析,表明反演精度受降温速度和收敛阈值的影响较大,初始温度只影响迭代次数,模拟退火法在对模型参数进行全局搜索情况下能获得质量较好的最优解。  相似文献   

吉林松原5.8级震群震相特征     

卢燕红  张洪艳  刘轶男  陈聪  陈闯  蔡宏雷 《地震地磁观测与研究》2017,39(1):67-72

选取2013年松原5.8级震群23个M_S≥3.0地震事件,通过地震波的振动持续时间、速度、周期、振幅等,进行震相识别,综合分析发现：该区域土层较厚,且震源相对较浅,面波较发育,波列的振动持续时间较长;地震震相主要以Pn、Sn、Pg、Sg、PmP、SmS为主：其中PmP、SmS震相在震中距70—110 km范围内较易识别;Pn、Sn震相在震中距150 km以上可较清晰的识别,随着震中距增大,Sn震相在震中距350 km以上将不易识别。  相似文献   

Study of a smart platform based on backstepping control method     

Luyu Li  Baowei Cheng  Yu Zhang  Han Qin 《地震工程与工程振动(英文版)》2017,16(3):599-608

A structural model is significant for the verification of structural control algorithms. However, for nonlinear behavior, experiments are mostly destructive tests that are costly, and conducting repetitive structural experiments is difficult. Therefore, a repetitive structural vibration model is important for structural vibration control. In this study, a smart platform to realize different structural behaviors is developed based on the backstepping control algorithm. Lyapunov functions are used to derive the control law. Simulations show that the designed model can track the structural responses of different arbitrary linear structures very well. In addition, the proposed platform can track responses of different piecewise linear structures and desired models with various hysteresis very well. Numerical results verify the effectiveness of the proposed tracking controller through the backstepping method for the established platform.  相似文献   

Field testing of the surface electromagnetic prospecting system     

Qing-Yun Di  Chang-Min Fu  Zhi-Guo An  Cheng Xu  Ya-Lu Wang  Zhong-Xing Wang 《应用地球物理》2017,14(3):449-458

To test the performance of the Chinese whole-surface electromagnetic prospecting (SEP) system, system integrations, instrument performances, and large-scale production viabilities in Liaoning province and Inner Mongolia were measured via extensive field tests. Resultant electric fields, magnetic fields, apparent resistivities, impedance phases, and inversion profiles compared favorably with results of commercial equipment from other countries. The inversion results agreed well with the geologic information from boreholes. Field tests showed that the SEP system is stable, reliable, lightweight, and easy to operate, making it suitable and ready for real-field exploration.  相似文献   

The effect of seafloor topography in the Southern Ocean on tabular iceberg drifting and grounding     

Tian Li  Yan Liu  Xiao Cheng  LunXi Ouyang  XinQing Li  JiPing Liu  Mohammed Shokr  FengMing Hui  Jing Zhang  JiaHong Wen 《中国科学:地球科学(英文版)》2017,60(4):697-706

Antarctic tabular icebergs are important active components in the ice sheet-ice shelf-ocean system. Seafloor topography is the key factor that affects the drifting and grounding of icebergs, but it has not been fully investigated. This study analyzes the impact of seafloor topography on the drifting and grounding of Antarctic tabular icebergs using Bedmap-2 datasets and iceberg route tracking data from Brigham Young University. The results highlight the following points. (1) The quantitative distributions of iceberg grounding events and the tracking points of grounded icebergs are mainly affected by iceberg draft and reach their peak values in sea water with depths between 200 m and 300 m. The peak tracking point number and linear velocity of free-drifting icebergs are found in the Antarctic Slope Front (water depth of approximately 500 m). (2) The area of possible grounding regions of small-scale icebergs calved from ice shelf fronts accounts for 28% of the sea area at water depths less than 2000 m outside the Antarctic coastline periphery (3.62 million km²). Their spatial distribution is mainly around East Antarctica and the Antarctic Peninsula. The area of possible grounding regions of large tabular icebergs with long axes larger than 18.5 km (in water depths of less than 800 m) accounts for 74% of the sea area. (3) The iceberg drifting velocity is positively correlated with ocean depth in areas where the depth is less than 2000 m (R=0.85, P<0.01). This result confirms the effect of water depth variations induced by seafloor topography fluctuations on iceberg drifting velocity.  相似文献   

Paleomagnetic results from Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane,Tibet, China,and their tectonic implications     

XingFeng Yang  Xin Cheng  YaNan Zhou  Lun Ma  XiaoDong Zhang  ZhaoSheng Yan  XiMing Peng  HaiLun Su  HanNing Wu 《中国科学:地球科学(英文版)》2017,60(1):124-134

Results of a systematic paleomagnetic study are reported based on Late Carboniferous to Early Permian sedimentary rocks on the north slope of the Tanggula Mountains,in the northern Qiangtang terrane(NQT),Tibet,China.Data revealed that magnetic minerals in limestone samples from the Zarigen Formation(CP^z)are primarily composed of magnetite,while those in sandstone samples from the Nuoribagaribao Formation(Pnr)are dominated by hematite alone,or hematite and magnetite in combination.Progressive thermal,or alternating field,demagnetization allowed us to isolate a stable high temperature component(HTC)in 127 specimens from 16 sites which successfully passed the conglomerate test,consistent with primary remnance.The tilt-corrected mean direction for Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane is D_s=30.2°,I_s=-40.9°,k_s=269.0,a_(95)=2.3°,N=16,which yields a corresponding paleomagnetic pole at 25.7°N,241.5°E(dp/dm=2.8°/1.7°),and a paleolatitude of 23.4°S.Our results,together with previously reported paleomagnetic data,indicate that:(1)the NQT in Tibet,China,was located at a low latitude in the southern hemisphere,and may have belonged to the northern margin of Gondwana during the Late Carboniferous to Early Permian;(2)the Paleo-Tethys Ocean was large during the Late Carboniferous to Early Permian,and(3)the NQT subsequently moved rapidly northwards,perhaps related to the fact that the Paleo-Tethys Ocean was rapidly contracting from the Late Permian to Late Triassic while the Bangong Lake-Nujiang Ocean,the northern branch of the Neo-Tethys Ocean,expanded rapidly during this time.  相似文献   

利用小半径粉晶相机测定钙镁碳酸盐矿物的含镁量          下载免费PDF全文

陈友明  王秀兰 《地质科学》1978,13(2):189-193

白云石和方解石是分布很普遍的造岩矿物,尤其在沉积地层中更属常见。镁方解石是现代碳酸盐沉积物和某些海洋生物介壳的一种常见矿物。一般说来,区分白云石与方解石是比较容易做到的。但是,要确切地回答一块白云岩样品是由典型的白云石(Ca/Mg克分子比值接近于1)还是由富钙白云石矿物(Ca/Mg克分子比值大于1)构成的,则比较困难。  相似文献