1958-2007年海河流域降水时空变异(英文)     

禇健婷  夏军  许崇育  李璐  王中根 《地理学报(英文版)》2010,20(2):248-260

The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events.The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention.However,in China,the precipita- tion data are measured by weather stations(WS)of China Meteorological Administration and hydrological rain gauges(RG)of national and local hydrology bureau.The WS data usually have long record with fewer stations,while the RG data usually hav...  相似文献   

内蒙古杭锦旗气田区地下水化学特征及其形成机制     

吴初  武雄  钱程  朱阁 《现代地质》2017,31(3):629

对内蒙古杭锦旗气田区浅层地下水运用Piper三线图、Gibbs图、氯碱指数图等方法进行水化学特征及其形成作用分析研究,结果表明：杭锦旗气田区浅层地下水具有较高的矿化度,偏碱性,硬度较大,枯水期TDS浓度和总硬度高于丰水期;研究区浅层地下水化学组分在小范围内具有一定的空间变异性,地下水阳离子以Na+、Ca2+为主,阴离子以HCO3-为主,水化学类型主要有HCO3 Ca型、HCO3 Na型和SO4·Cl Na型;研究区浅层地下水化学组分来源于碳酸盐矿物、硅铝酸盐矿物和蒸发岩的风化溶解,且丰水期和枯水期水化学组分有微弱变化,地下水化学特征的形成以岩石风化溶解作用为主。  相似文献   

Simplified methods to analyze geosynthetic mattress resting on deformable foundation soil     

Wei Guo  Hailei Kou  Bo Zhou  Jian Chu 《Marine Georesources & Geotechnology》2017,35(3):339-345

A special case of geosynthetic tubes is the geosynthetic mattress characterized by its larger width-to-height ratio and higher lateral-force-resisting capacity. When the geosynthetic mattresses are adopted for dike or breakwater construction in coastal engineering projects, they are often laid on deformable foundation soil. The induced ground settlement will influence the cross-sections and tensile forces of the geosynthetic mattresses. Two analytical methods, called the Winkler foundation method and the e–log p method, are proposed in this paper to analyze the geosynthetic mattresses resting on deformable foundation soil. For the Winkler foundation method, the subgrade soil is assumed as a Winkler elastic foundation represented by the modulus of subgrade reaction, K_f. For the e–log p method, the 1D consolidation relationship (e–log p curve) is adopted to describe the behavior of the subgrade soil within which the distribution of vertical surcharge is calculated using Boussinesq equation. The numerical analyses using FLAC are also conducted to evaluate the accuracy of the proposed methods. The differences between the analytical and numerical solutions are also discussed. It is found from this paper that the proposed e–log p method is more suitable than the Winkler foundation method for the calculation of the geosynthetic mattress resting on deformable foundation soil.  相似文献   

Anti-Phase Relationship Between the East Asian Winter Monsoon and Summer Monsoon During the Holocene?     

Qian Ge  Zuo Xue  Zhigang Yao  Zhengchen Zang  Fengyou Chu 《中国海洋大学学报(英文版)》2017,16(2):175-183

The relationship between the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM) during the Holocene is complicated and remains controversial. In this study, analysis of grain size and benthic foraminiferal oxygen isotope, as well as accelerator mass spectrometry ¹⁴C dating was performed on a sediment core retrieved from the newly revealed muddy deposit on the northern South China Sea continental shelf. The history of the EAWM and EASM were reconstructed for the last 8200 a BP. Further analysis in conjunction with previously published paleo-climate proxies revealed that the relationship between the EAWM and EASM during the Holocene is more complex than a simple and strict anti-phase one-both negative and positive correlations were identified. The EAWM and EASM are negatively correlated around 7500, 4800, 4200, 3200, and 300 a BP (cooling periods), while positively correlated around 7100, 3700, and 2100 a BP (warm periods). In particular, both the EAWM and EASM intensified during the three positive correlation periods. However, we also found that the relationship between these two sub-monsoons is anti-phase during the final phase of particularly hot periods like Holocene Optimum and Medieval warm period. The possible impact from variations of solar irradiance on the relationship between the EAWM and EASM was also discussed.  相似文献   

Predicting Scalar Source-Sink and Flux Distributions Within a Forest Canopy Using a 2-D Lagrangian Stochastic Dispersion Model     

Cheng-I Hsieh  Mario Siqueira  Gabriel Katul  Chia-Ren Chu 《Boundary-Layer Meteorology》2003,109(2):113-138

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Evidence for evolution in the clustering of quasars     

Zhu Xing-fen  Chu Yao-quan 《Chinese Astronomy and Astrophysics》1990,14(4):371-380

We discuss the changes in the amplitude of the correlation function of quasar clustering with the redshift. Using the new Hewitt-Burbidge QSO catalogue, we find from a statistical analysis of the quasar pairs that the positive results of quasar clustering are mainly contributed by low-redshift quasars. There is an obvious change in the quasar distribution at z = 2. There is no clustering for z > 2. The difference in clustering is not due to any selection effect on the brightness. The evidence is that quasar clustering evolved with cosmological time.  相似文献   

西昆仑库地韧性剪切带的⁴⁰Ar/³⁹Ar年龄   总被引：16，自引：4，他引：12       下载免费PDF全文

周辉  储著银  李继亮  侯泉林  王志洪  方爱民 《地质科学》2000,35(2):233-239

西昆仑库地以南有一套变质变形较强的岩系,前人依照区域对比关系将其划为前寒武的古老基底。对西昆仑早期构造演化的论述均基于该观点,但没有提供确凿的同位素年代学证据。笔者通过野外观察、室内研究,确认库地以南的变质变形岩系是大型韧性推覆剪切作用的产物。通过对新生变质矿物角闪石和黑云母单矿物的⁴⁰Ar/³⁹Ar年龄分析,确定剪切变质年龄为426-451Ma,说明库地的变质变形岩系是形成于早古生代晚期的一条大型韧性剪切带,这对于解释西昆仑的早期构造演化具有重要意义。  相似文献   

Statistical analysis of correlation between the positions of quasars and the uppsala galaxies     

Zhu Xing-fen  Chu Yao-quan 《Chinese Astronomy and Astrophysics》1983,7(4):245-250

The question of the association of quasars with galaxies is re-examined using 785 quasars at |b| 30, δ − 02°30′ in the new Hewitt and Burbidge Catalog (1980) and all galaxies in the “Uppsala General Catalogue of Galaxies” (Nilson, 1973). The results of the two-point cross-correlation function are presented and they show that there are on the average 0.153 ± 0.011 more galaxies within 10'.0 of a QSO than would be expected if the QSOs were distributed randomly. We find the marginal significance of the tendency for correlation between QSOs and galaxies to increase with increasing redshifts z or apparent magnitudes V. The nearest neighbor test has also been taken to analyse the same data as well as get further evidence for the apparent association between QSOs and galaxies.  相似文献   

Periodic redshift distribution of quasars associated with low — redshift galaxies     

Zhu Xing-fen  Chu Yao-quan 《Chinese Astronomy and Astrophysics》1990,14(4):429-436

We applied power spectral analysis to the redshift distribution of the quasars associated with low-redshift galaxies. Periodicity is confirmed at a level of confidence >99%, with a period of Δln(1+z) = 0.206. This result is exactly the same as previously found for different quasar samples. The periodicity is not caused by any selection effect in the emission lines. The two phenomena, the periodicity in the redhsift distribution and the association of quasars with low-redhsift galaxies can both be rather well explained by a multiply-connected model of the universe.  相似文献   

旅游地开发评价研究   总被引：50，自引：0，他引：50  

楚义芳 《地理学报》1991,46(4):396-404

旅游地开发评价是旅游开发中的一个重要课题,也是旅游地理学的重要研究内容之一。本文初步探讨了旅游地开发评价的方法论,并尝试建立中国旅游地开发评价系统。  相似文献