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Physical mechanisms of plant roots affecting weathering and leaching of loess soil

Science china Earth sciences 2006年第9期49卷 1002-1008页

作者： LI Yong1,2, ZHANG Qingwen1,2, WAN Guojiang3. HUANG Ronggui3. PIAO Hechun3. BAI Lingyu2 & LI Lu2 1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, institute of Soil and Water Conservation, chinese academy of {3., Yangling 712100, china 2. institute of Agro-Environment and Sustainable Development, chinese academy of Agricultural {3., beijing 100081, china 3. institute of Geochemistry, chinese academy of {3., Guiyang 550002, china 1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling 712100 China 2. institute of Agro-Environment and Sustainable Development Chinese Academy of Agricultural Sciences Beijing 100081 China 3. institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

Plant roots have potential impacts on soil mineral weathering and *** objective is to understand the physical mechanisms of plant roots affecting weathering andleaching of loess soil. Root densities were measured through the method of a large-size dug profile,and transport fluxes of soil elements were determined using an undisturbed monolith soilinfiltration device on the hilly and gully regions of the chinese Loess Plateau. The results showthat the improvement effects of soil environment by plant roots are mainly controlled by the densityand weight of the fibrous roots with the diameters less than 1 mm. Plant roots have the strongereffects on soil physical properties than chemical properties. The principal components analysis(PCA) indicates that soil physical properties by plant roots account for 56.7% of variations in soilenvironment whereas soil chemical properties and pH contribute about 24.2% of the soil *** roles of plant roots in controlling soil weathering and leaching increased in the followingorder: infiltration enhancement > increase of bio-active substance > stabilization of soilstructure. The effects of plant roots on soil mineral weathering and leaching can be quantifiedusing the multiple regression models with the high prediction accuracies developed in this study.

关键词： plant roots, soil weathering and leaching rates, soil environment field, principal components analysis (PCA), chinese Loess Plateau.

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Effect of rock mass structure and block size on the slope stability——Physical modeling and discrete element simulation

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Science china(Technological sciences) 2005年第z1期48卷 1-17页

作者： LI Shihai1, LIAN Zhenzhong1,2 & J. G. Wang3.1. institute of Mechanics, chinese academy of {3., beijing 100080, china 2. Graduate School, chinese academy of {3., beijing 100060, china 3. Tropical Marine Science institute, National University of Singapore, Singapore 119260 chinese Acad Sci Inst Mech Beijing 100080 Peoples R China chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ Singapore Trop Marine Sci Inst Singapore 119260 Singapore

This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

关键词： rock masses, slope stability, DEM simulation, block size effect, joints configuration effect, limit equilibrium method.

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PGE patterns of ores of Dajing Cu-polymetallic deposit in Linxi County, Inner Mongolia:Indicator to source of metallogenic elements

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chinese Science Bulletin 2002年第13期47卷 1119-1124页

作者： CHU Xuelei, SUN Min & ZHOU Meifuinstitute of Geology and Geophysics, chinese academy of {3., beijing 100029, china Key Laboratory of mineral resources, institute of Geology and Geophysics, chinese academy of {3., beijing 100101, china Department institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Key Laboratory of mineral resources Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Department of Earth sciences The University of Hong Kong Hong Kong China

By comparing PGE patterns of sulfide ores with that of basic-ultrabasic dikes occurring in the Dajing Cu-polymetallic deposit, we discover that there are similar positive slopes between the basic-ultrabasic dikes and the black ores composed mainly of sphalerite and galena, reflecting affinity of their source. The PGE patterns of the yellow ores composed basically of chalcopyrite, arsenopyrite and pyrite are actually different. One is close to the pattern of the mantle 1herzolite, and others resemble the pattern of the basic rocks. However, the concentrations of Ru are higher in the yellow ores, reflecting that sulfur attains or approaches saturation in their parent magma. The PGE characteristics of ores and dikes show that the magmas derived from the deep of crust and the metallogenic elements were supplied mainly by growth material of the crust. In addition, the mantle-derived magma also offered some elements.

关键词： Da Hinggan area polymetallic deposit PGE pattern hypomagma.

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Modeling of elastic wave propagation on a curved free surface using an improved finite-difference algorithm

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 633-648页

作者： WANG Xiuming1,3.& ZHANG Hailan2 1. CSIRO Petroleum, ARRC, PO BOX 113., Technology Park, Bentley, WA 6102, Australia 2. institute of Acoustics, chinese academy of {3., beijing 100080, china 3. Present address: institute of Acoustics, chinese academy of {3., beijing 100080, china 1. CSIRO Petroleum ARRC Technology Park PO BOX 1130 6102 Bentley WA Australia 2. institute of Acoustics Chinese Academy of Sciences 100080 Beijing China

Based on existing direct and imaging methods of a staggered finite-difference scheme, an improved algorithm for staggered finite-difference is proposed to implement rugged topographic free boundary conditions. This method assumes that the free surface can be implemented with horizontal and vertical free surface segments and their corners; the free surface passes through the grid points of shear stress components, instead of the normal stress components. Imaging is carried out for stress components in both horizontal and vertical directions, thus increasing the accuracy. To update particle- velocities, imaging and updating are first performed in the horizontal direction, and then in the vertical direction. The numerical results for elastic flat horizontal free surface with the imaging method and those for flat free surfaces of various slope angles with the proposed method are compared, and are shown to be in good agreement. The advantage of the proposed method is that only the stresses are dealt with in implementing the free surface into the staggered algorithm, which improves computation efficiency.

关键词： elastic wave simulation, curved free surface, staggered finite-difference, algorithm stability.

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Studies on BEPC upgrade from pretzel to double-ring

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2084-2089页

作者： ZHANG Chuang institute of High Energy Physics,chinese academy of {3.,beijing 100049,china 1. institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

Physics opportunity in the charm and τ energy region calls for higher luminosity of the beijing Electron-Positron Collider (BEPC).The BEPC has experienced continuous improvement since its completion in ***,as a major upgrading project of the BEPC,aims at enhancing its luminosity of factor 3.–100,following the principle of "one machine,two purposes" as adopted in BEPC,so that both high energy physics and synchrotron radiation experiments can be carried out with *** the BEPC to BEPCII,the double-ring scheme with multi-bunch e +-e-collision in the large crossing angle was studied in comparison with the single-ring pretzel *** the dedicated synchrotron radiation operation,artful "bridges" are designed to connect two halves of the outer ring in both the southern and the northern crossing *** paper reviews the studies on the BEPC upgrade from pretzel to double-ring structure of BEPCII.

关键词： collider storage ring high energy physics synchrotron radiation

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Ambient noise near the sea-route

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 40-45页

作者： HE Li1,2, LI ZhengLin1,3.& PENG ZhaoHui1 1 National Laboratory of Acoustics, institute of Acoustics, chinese academy of {3., beijing 100190, china 2 institute of Geology and Geophysics, chinese academy of {3., beijing 100029, china 3.NanHai Laboratory of Acoustics, institute of Acoustics, chinese academy of {3., Haikou 570206, china National Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China NanHai Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Haikou 570206 China

Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

关键词： ambient noise model horizontal correlation discrete ships

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Carbon and Oxygen Stable Isotope Values and Microfossils at 41.4-4.5ka BP in Tai Co,Tibet,china,and Their Paleoclimatic Significance

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Acta Geologica Sinica(English Edition) 2011年第5期85卷 1036-1050+1052-1056+1051页

作者： ZHENG Mianping~(1,2,*),LIU Junying~(1,3.,MA Zhibang~(1,4),WANG Hailei~(1,2) and MA Nina~(1,2) 1 MLR Key Laboratory of Saline Lake resources and Environment,institute of mineral resources,CAGS, beijing 10003.,china 2 Research and Development Center for Saline Lakes and Epithermal Deposits,chinese academy of geological sciences,beijing 10003.,china 3.institute of Geology,chinese academy of geological sciences,beijing 10003.,china 4 Key Laboratory of Cenozoic Geology and Environment,chinese academy of sciences,beijing 100029, china MLR Key Laboratory of Saline Lake resources and Environment Institute of Mineral Resources CAGS Beijing 100037 China Research and Development Center for Saline Lakes and Epithermal Deposits Chinese Academy of Geological Sciences Beijing 100037 China institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Key Laboratory of Cenozoic Geology and Environment Chinese Academy of Sciences Beijing 100029 China *Correspondence: Mianping ZHENG *Correspondence: Corresponding author. E-mail: zhengmp2010@***

Two sedimentary sections were measured at Tai Co(Co means lake in Tibetan) in western Tibet,*** two sections are almost all composed of clay carbonate beds except in their lower parts where there are carbonized plants at>10 cm depths and dark-colored carbonate clay and clay at 50-70 cm depths,yielding abundant gastropods,ostracods,and *** carbon and oxygen stable isotope values of carbonate,ostracods,and charophytes and ecological features of microfossil communities indicate the following climatic change in the area from 41.4 to 4.5 ka BP:at 41.4-26.2 ka BP,the climate was relatively wet;at 26.2-25.5 ka BP,it was slightly warm-dry;at 25.5-22.5 ka BP,it was warm-wet;at 22.5-21.0 ka BP,it was slightly cold-wet;at 20.5-17.5 ka BP,it became cold abruptly and slightly wet,implying the climate of the last glacial maximum;at 17.5-16.0 ka BP,it was slightly cold-dry;at 16.0-11.8 ka BP,it was slightly warm-wet;at 11.8-10.4 ka BP,it was relatively cold-dry, roughly equivalent to the climate of the Younger Dryas,and at 10.4 ka BP,the temperatures began to rise again;at 10.4-9.4 ka BP,it was slightly warm-wet;at 9.4-8.5 ka BP,there occurred short warm-wet oscillations;at 8.5-7.9 ka BP,it was slightly dry-cold,representing a strong temperature-lowering and drying event in the postglacial stage;at 7.8-6.3.ka BP,it was slightly warm-wet;at 6.3.4.5 ka BP,the climate tended to be cold-dry.4.5 ka BP recorded the maximum aridity since the late part of the late Pleistocene.

关键词： sedimentary environment index paleoclimatic changes late Pleistocene-Holocene(41.4-4.5 ka BP) Tai Co Tibet

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Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) bulk metallic glass up to 24 GPa

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Science china(Physics,Mechanics & Astronomy) 2005年第3期48卷 319-324页

作者： LI Gong 1, 2 , ZHAN Zaiji 2 , LIU Jing 3., YUN Jinku 1 , SUN Liling 2 , LIU Riping 1 , ZHANG Jun 2 & WANG Wenkui 1, 2 1. Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. Center for Condensed Matter Physics, institute of Physics, chinese {3. of sciences, beijing 100080, china 3. BSRF, institute of High Energy Physics, chinese {3. of sciences, beijing 10003., china 1. Key Laboratory of Metastable Materials Science and Technology Yanshan University 066004 Qinhuangdao China 2. Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 3. BSRF Institute of High Energy Physics Chinese Academy of Sciences 100039 Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

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Modeling on runoff concentration caused by rainfall on hillslopes and application in Maoping slope

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Progress in Natural Science:Materials International 2006年第10期16卷 1056-1065页

作者： LIU Qingquan and LI Jiachun (institute of Mechanics, chinese academy of {3., beijing 100080, china) [a]chinese academy of sciences' Institute of Mechanics' Beijing China

Based on the fact that the concentration flowlines of overland flow depend on the surface landform of hillslope, a kinematic wave model was developed for simulating runoff generation and flow concentration caused by rainfall on hillslopes. The model-simulated results agree well with the experimental observations. Applying the model to the practical case of Maoping slope, we obtained the characteristics of runoff generation and infiltration on the slope. Especially, the simulated results adequately reflected the confluent pattern of surface runoff, which offers a scientific foundation for designing the drainage engineering on the Maoping slope.

关键词： complex hillslope rainfall infiltration overland flow runoff concentration Maoping slope.

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Some problems on the studies of the late Pleistocene human evolution and formation of modern human populations

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Progress in Natural Science:Materials International 2006年第12期16卷 1233-1241页

作者： LIU Wu(institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of {3., beijing 100044, china) [a]institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China

For the past two decades, studies and debates on the modern human origins around the world have attracted attentions to the late Pleistocene human evolution and formation of modern human populations, and some controversial hypotheses and problems have been proposed. In the present paper, some problems on the late Pleistocene human evolution, and the formation and differentiations of modern human populations in china are studied with a brief description and comments on the research advances in this field.

关键词： late Pleistocene human evolution formation and differentiation of modern human population paleoanthropology.

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