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Preliminary study on interaction between plant frictional root and rock-soil mass

science china(Technological sciences) 2010年第7期53卷 1938-1942页

作者： YAN ZhiXin1’2. SONG Yun3, JIANG Ping1’2.& WANG HouYu4 1 Key Laboratory of Mechanics on Disaster and Environment in Western china (lanzhou {2.), Ministry of Education, lanzhou 730000, china 2.school of Civil Engineering and Mechanics, lanzhou university, lanzhou 730000, china 3 College of Civil Engineering and Mechanics, Central South {2. of Forestry and technology, Changsha 410004, china 4 Air Force Engineering Design & Research Bureau, Beijing 100077, china Key Laboratory of Mechanics on Disaster and Environment in Western china (lanzhou {2.) Ministry of Education Lanzhou China school of Civil Engineering and Mechanics Lanzhou University Lanzhou China College of Civil Engineering and Mechanics Central South University of Forestry and Technology Changsha China Air Force Engineering Design & Research Bureau Beijing China

The interaction between lateral root system of woody plant and soil mass is similar to the one between shrub, herbage and soil mass, and has the effect of frictional reinforcement on slope soil. It plays an important role in reinforcing soil strength in shallow slope. Therefore, slope soil mass can be considered as a composite of soil and plant roots and the soil strength and stability of shallow slope soil mass are improved. However, current researches still remain on the level of qualitatively analyzing the relation between root and soil mass. In this paper, some exploratory researches on quantitative analysis of the interaction mechanism between root and soil mass are conducted. With the study of interaction between herbage root system (lateral root system of woody plants) and soil mass, the mechanical model of interaction between frictional root and soil mass is established. The accuracy of the model is verified by field experiments of Pinus Yunnanensis. The mechanical model provides a crucial theoretical guidance to quantitatively analyzing the interaction between plant root and soil mass; it also has certain values in application.

关键词： plant slope protection vegetation for slope protection mechanical model frictional root

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MULTISCALE MECHANICAL BEHAVIORS IN DISCRETE MATERIALS: A REVIEW

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Acta Mechanica Solida Sinica 2010年第6期23卷 579-591页

作者： Xiaojing Zheng Dengming Wang (Key Laboratory of Mechanics on Western Disaster and Environment,the Ministry of Education of china,lanzhou {2.,lanzhou 730000,china) Key Laboratory of Mechanics on Western Disaster and Environment the Ministry of Education of China Lanzhou University Lanzhou China

The discrete material, which belongs to the category of soft materials, is one of the most prevalent forms of matter in nature and engineering fields. These materials often exhibit abundant and complex mechanical properties which are still far from being perfectly understood. From the view of multi-scale framework concentrated on the ＇bridge＇ role in the macro-micro relation, this review mainly introduces some theoretical investigations of mechanical behaviors in discrete materials, including the continuum constitutive model based on the macroscopic phenomenological approach and coupled micro-macro approach, the statistical analysis of some microscopic physical quantities involved contacted forces between particles and its transmission within the whole system, and the statistical analysis for some microscopic processes in aeolian landform systems involving the grain-bed impact, the transportation and sedimentation of wind-blown sand flux, et al. Finally, some further worthwhile challenges in these fields are suggested.

关键词： discrete material multiple space and time scales trans-scales correlation sanddune statistical analysis

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Photocatalytic performance of TiO_2.immobilized on polystyrene (PS) thin film for mineralization of pollutants

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Rare Metals 2003年第2期22卷 137-143页

作者： GAO Yuan, YU Wei, CHEN Baohua, MA Yongxiang, and LI HulinDepartment of Chemistry, lanzhou university, lanzhou 730000,{2. (Receeived 2.02.02.2.) Department of Chemistry Lanzhou University Lanzhou 730000

A new photocatalyst, TiO_2.powder immobilized on polystyrene (PS) thin films,was prepared using a novel method and its photocatalytic activity on the photodegradation ofacridine dye in aqueous solution was tested. By this method, the crystal form and grain size of theimmobilized TiO_2.were well maintained. Compared with TiO_2.powder, the photocatalytic activity ofTiO_2.PS thin films was not significantly reduced. The catalyst is stable and can be reused severaltimes without the loss of activity, which makes wastewater treatment using this photocatalyticdegradation technique of this way possible in the practical application.

关键词： physical chemistry loaded photocatalyst TiO_2 acridine dye fluidifying sedimentation container

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Preparation and particle size characterization of Cu nanoparticles prepared by anodic arc plasma

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Rare Metals 2006年第2期25卷 172-176页

作者： WEI Zhiqiang XIA Tiandong FENG Wangjun DAI Jianfeng WANG Qing LI Weixue YAN Pengxun school of sciences Lanzhou University of Technology Lanzhou 730050 China College of Materials science and Engineering Lanzhou University of Technology Lanzhou 730050 China Institute of Plasma and Metal Materials Lanzhou University Lanzhou 730000 China

Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2.g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

关键词： metal materials Cu nanoparticles anodic arc plasma particle size structure

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Shell effect and capture cross sections in the synthesis of superheavy nuclei

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1489-1493页

作者： DU SaiSai1,2.BIAN BaoAn1,2.3,LIU Min1,2.4,FENG ZhaoQing5,6 & ZHANG FengShou1,2.6 1 Key Laboratory of Beam technology and Material Modification of Ministry of Education,College of Nuclear science and technology,Beijing Normal university,Beijing 100875,china 2.Beijing Radiation Center,Beijing 100875,china 3 school of science,Jiangnan university,Wuxi 2.412.,china 4 College of Physics and technology,Guangxi Normal university,Guilin 541004,china 5 Institute of Modern Physics,Chinese Academy of sciences,lanzhou 730000,china 6 Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of lanzhou,lanzhou 730000,china Key Laboratory of Beam technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing China Beijing Radiation Center Beijing China school of science Jiangnan University Wuxi China College of Physics and technology Guangxi Normal University Guilin China Institute of Modern Physics Chinese Academy of Sciences Lanzhou China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction 35 80 Br + 82.2.8 Pb → 117 2.8 X are also calculated and discussed.

关键词： superheavy nuclei transport theory shell effect cross sections

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Multifield coupling model and its applications for pile foundation in permafrost

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science china Earth sciences 2005年第7期48卷 968-977页

作者： WU Yaping1,2. ZHU Yuanlin2. GUO Chunxiang1, SU Qiang1 & MA Wei2.1. school of Civil Engineering, lanzhou Jiaotong {2., lanzhou 730070, china 2. State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of sciences, lanzhou 730000, china school of Civil Engineering Lanzhou Jiaotong University Lanzhou 730070 China State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Importing the interface element which links the frozen soil base with concrete piles and considering the couplings of stress field, temperature field and moisture field, this paper es- tablishes the nonlinear visco-elastic plastic finite element model of pile-soil. For a practical bridge structure the stress field and displacement field of single pile in freezing process are calculated. This paper emphatically studies the process of the tangential frost heave stress field, freezing stress field and displacement field varying with time, and ulteriorly studies time variation process of single pile carrying capacity in freezing process.

关键词： permafrost pile foundation freezing process multifield coupling analysis model.

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Carbon isotopic characteristics and their genetic relationships for individual lipids in plants and sediments from a marsh sedimentary environment

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science china Earth sciences 2005年第8期48卷 1203-1210页

作者： DUAN Yi1, ZHANG Hui1, ZHENG Chaoyang1, WU Baoxiang1 & ZHENG Guodong2.1. lanzhou Institute of Geology, Chinese Academy of sciences,{2., china 2. Department of Earth & Planetary System science, Graduate school of science, Hiroshima university, Higashi-Hiroshima 739-85Japan lanzhou Institute of Geology Chinese Academy of Sciences Lanzhou China Department of Earth & Planetary System science Graduate School of Science Hiroshima University Higashi-Hiroshima Japan

The carbon isotopes of individual lipids in herbaceous plants and tree leaves in Ruoergai marsh were measured by the GC-IRMS analytical technique in order to understand the inherent relationships of carbon isotopes between sedimentary and plant lipids from typical marsh environment. The analytical results show that the carbon isotopic compositions of n-alkanes in different kinds of plants differ significantly. Mean δ 13C values of n-alkanes in her-baceous plants (?32.2.―?36.9‰) are 3.3‰ lower than those in woody plant (?2..2.― ?35.0‰). The carbon isotopic compositions of fatty acids in organisms (?30.3‰― ?36.2.) are very similar to those of n-alkanes and the δ 13C values for unsaturated fatty acids are within the range of those for saturated fatty acids. The differences in δ 13C values between plant lipids are obvious and range from 2.4‰ to 7.8‰. It is observed that the carbon isotopic compositions of sedimentary lipids are closely related to those of plant lipids. The carbon isotopic compositions (?2..0‰―?36.9‰) of n-alkanes, ≥C16 fatty acids, n-alkanols, sterols and n-alkanones in the sediments are similar to those of plant lipids and the carbon isotopic compositions of short-chain sedimentary lipids are similar to those of long-chain sedimentary homologues. These indicate that the sedimentary lipids are derived from high plants. However, the δ 13C values of C14:0 and C15:0 fatty acids in the sediments are lighter than those of the same carbon number saturated homologues in plants, reflecting the genetic features partially derived from bacteria. These data provide scientific evidence for carbon isotope-applied research of individual lipids.

关键词： marsh environment, plants, sediments, individual lipids, carbon isotopic compositions, genetic relationships.

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Holocene climate variation denoted by Barkol Lake sediments in northeastern Xinjiang and its possible linkage to the high and low latitude climates

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science china Earth sciences 2011年第4期54卷 603-614页

作者： XUE JiBin & ZHONG Wei 1 school of Geography,South china Normal {2.,Guangzhou 510631,china 2.Key Laboratory of Oasis Ecology(Ministry of Education) ,Xinjiang {2.,Urumqi 830046,china 3 Key Laboratory of Western china's Environmental Systems(Ministry of Education) ,lanzhou {2.,lanzhou 730000,china school of Geography South China Normal University Guangzhou China Key Laboratory of Oasis Ecology (Ministry of Education) Xinjiang University Urumqi China Key Laboratory of Western china’s Environmental Systems (Ministry of Education) Lanzhou University Lanzhou China

The climate over the closed inland Barkol Lake,which is located in northeastern Xinjiang Uygur Autonomous Region,is significantly influenced by westerly winds *** improve our understanding of past climate processes in westerly wind influenced regions in northwestern china,a 2.0-cm sediment section was retrieved from this *** taking the carbon reservoir effect into consideration,the chronological sequence of this section was reconstructed based on seven conventional radiocarbon dates of bulk samples,and the bottom age of this section was determined to be about 9400 cal a ***-proxy datasets,includingδ18O car,δ13C car of authigenic carbonate,and total organic carbon were examined using wavelet analysis and singular spectrum analysis *** show that the Holocene in the Barkol Lake region can be divided into four stages:(1) a cold and dry early stage before～8000 cal a BP;(2. a moderately warm and wet middle stage between～8000 and 6000 cal a BP;(3) a warm and dry stage,along with a cooling-wetting tendency from 6000 to 2.00 cal a BP;and(4) a fluctuating cooling and wet stage between 2.00-800 cal a BP,and a drier stage since 800 cal a *** general trend of Holocene climatic changes revealed by Barkol Lake sediments was in agreement with that of adjacent *** infer that climatic changes during the Holocene in the Barkol Lake region were influenced not only by high latitudes,especially the North Atlantic region climate,but also tropical low-latitude processes,such as the El Nio/La Nia-Southern *** study demonstrates that the enhanced activities of ENSO may have played an important role in climatic changes in northeastern Xinjiang during the *** results also suggest that climatic patterns may be temporally different in the northern Xinjiang area in response to the changing predominant control of either the Westerly or the Asian summer monsoon,depending on the contrast of their relative strengths.

关键词： Barkol Lake Holocene climate change tropical processes northern high-latitude climate

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Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory

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science china Mathematics 2005年第10期48卷 1379-1394页

作者： WANG Dingcheng~1 SU Chun~2.& ZENG Yong~1 1. school of Management and school of Applied Mathematics,{2. of Electronic science and technology of china,Chengdu 610054,china 2. Department of Statistics and Finance,{2. of science and technology of china,Hefei 2.002.,china school of Management and school of Applied Mathematics University of Electronic Science and Technology of China Chengdu China Department of Statistics and Finance University of Science and Technology of China Hefei China

This paper obtains the uniform estimate for maximum of sums of independent and heavy-tailed random variables with nonnegative random weights, which can be arbitrarily dependent of each other. Then the applications to ... 详细信息

关键词： dependent stochastic return, discount factor, heavy-tails, discrete time insurance risk model, maxima of randomly weighted sums, ruin probability, tail probabilities, uniformly asymptotic estimate.

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A constitutive model of frozen soil with damage and numerical simulation for the coupled problem

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science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 699-711页

作者： ZHU ZhiWu, NING JianGuo& MA Wei 1 school of Mechanics and Engineering, Southwest Jiaotong university, Chengdu 610031,{2. 2.State Key Laboratory of Explosion science and technology, Beijing Institute of technology, Beijing 100081,{2. 3 Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, lanzhou 730000,{2. school of Mechanics and Engineering Southwest Jiaotong University Chengdu China State Key Laboratory of Explosion science and technology Beijing Institute of Technology Beijing China Key Laboratory of Frozen Soil Engineering CAREERI CAS Lanzhou China

Based on the microcosmic mechanics of composite materials, an elastic constitutive model for frozen soil with damage is presented. For frozen sandy soil with a range of ice contents and under a range of temperature conditions, quantitative results determined by this constitutive model agree with practically measured stress-strain curves. After numerically simulating the coupled water, temperature and stress fields of channel frozen and frozen roadbed using a self-developed finite-element routine, more accurate and practical calculation results for the temperature field coupled with stress, displacement and strain fields are obtained; the results match predictions and tests undertaken by earlier researchers. Our results support the reliability of our routine for calculating interdependent physical quantities of frozen soil and for describing the relationships between them. Our program can offer necessary constraints for engineering design and construction in permafrost regions.

关键词： frozen soil microcosmic mechanics roadbed coupling stress field

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