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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 university), 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 university 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 university) 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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DYNAMIC BEHAVIORS OF CONDUCTIVE CIRCULAR PLATE IN TIME-VARYING MAGNETIC FIELDS

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Acta Mechanica Solida Sinica 2010年第1期23卷 66-76页

作者： Yuanwen Gao1 Bang Xu(Key Laboratory of mechanics on Western Disaster and Environment,College of civil engineering and mechanics,lanzhou university,lanzhou 730000,china) Key Laboratory of mechanics on Western Disaster and Environment College of Civil Engineering and Mechanics Lanzhou University Lanzhou China

In this study, we proposed an analytical solution for eddy currents as well as electromagnetic forces of a conductive circular plate in a time varying magnetic field. Specifically, an analytical series solution for eddy currents in a circular plate subjected to an axisymmetrie time varying magnetic field has been proposed based on the T-method that has been widely used in the eddy current analysis of conductive and superconductive structures. Accordingly, the dynamic response, the dynamic instability and the magnetic damping of a circular plate in a transverse transient magnetic field as well as a stationary in-plane magnetic field have also been obtained. The analytical series solution proposed in this work as well as the subsequent numerical analysis not only confirmed the emergence of dynamic instability of a circular plate in a strong transverse magnetic field, but also demonstrated the existence of magneto-damping of a circular conductive plate in an in-plane magnetic field. The method developed in this paper provides a potential new possible way by which the analysis of the electromagnetic coupling problems of conductive structures can be simplified.

关键词： dynamic response circular conductive plate series solution for eddy current Bessel function

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Guided wave propagation in multilayered piezoelectric structures

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Science china(Physics,mechanics & Astronomy) 2009年第7期52卷 1094-1104页

作者： GUO YongQiang1, CHEN WeiQiu2,3 & ZHANG YongLiang4 1 Key Laboratory of mechanics on Disaster and Environment in Western china, Ministry of Education, and school of civil engineering and mechanics, lanzhou university, lanzhou 730000, china 2 Key Laboratory of Soft Soils and Geoenvironmental engineering, Ministry of Education, and Department of civil engineering, Zhejiang university, Hangzhou 310058, china 3 Department of engineering mechanics, Zhejiang university, Hangzhou 310027, china 4 school of civil engineering, lanzhou Jiaotong university, lanzhou 730070, china Key Laboratory of mechanics on Disaster and Environment in Western china Ministry of Education and School of Civil Engineering and Mechanics Lanzhou University Lanzhou China Key Laboratory of Soft Soils and Geoenvironmental engineering Ministry of Education and Department of Civil Engineering Zhejiang University Hangzhou China Department of engineering mechanics Zhejiang University Hangzhou China school of civil engineering Lanzhou Jiaotong University Lanzhou China

A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.

关键词： multilayered piezoelectric structures the method of reverberation-ray matrix guided waves dispersion characteristic

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A computer simulation of nucleation and growth of thin films

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Science china(Physics,mechanics & Astronomy) 2004年第4期47卷 442-451页

作者： ZHENG Xiaoping1,ZHANG Peifeng2,HE Deyan2,LIU Jun2& MA Jiantai3 1. Key Laboratory of Opto-Electronic Technology and Intelligent Control, Ministry of Education, lanzhou Jiaotong university, lanzhou 730070, china 2. school of Physical Science and Technology, lanzhou university, lanzhou 730000, china 3. school of Chemistry and Chemistry engineering, lanzhou university, lanzhou 730000, china Key Laboratory of Opto-Electronic Technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University Lanzhou China school of Physical Science and Technology Lanzhou University Lanzhou China school of Chemistry and Chemistry engineering Lanzhou University Lanzhou China

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. This model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. It takes some new effects into account, such as a significant improvement in calculation of activation energy for the atom diffusion, which renders the model more reasonable. In addition three optimum temperatures and the consistency of their dependence on deposition rate have been found out; the dependence of the surface roughness and relative density on the deposition rate has been discussed; and the approximation of freezing neighbour atoms and periodic boundary conditions has been applied.

关键词： Monte Carlo, thin film, nucleation, surface roughness, relative density.

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SINGULAR BEHAVIORS OF INTERFACIAL CRACKS IN 2D MAGNETOELECTROELASTIC BIMATERIALS

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Acta Mechanica Solida Sinica 2009年第3期22卷 232-239页

作者： Cuiying Fan1 Youhe Zhou1 Han Wang2 Minghao Zhao1,2(1Key Laboratory of mechanics on Disaster and Environment in Western china,the Ministry of Education of china,and Department of mechanics and engineering Science,College of civil engineering and mechanics,lanzhou university,lanzhou 730000,china)(2school of Mechanical engineering,Zhengzhou university,Zhengzhou 450001,china) Key Laboratory of mechanics on Disaster and Environment in Western china the Ministry of Education of China and Department of Mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou China school of Mechanical engineering Zhengzhou University Zhengzhou China

The singular characteristics of stress,electric displacement and magnetic induction fields near the tip of impermeable interfacial cracks in two-dimensional magnetoelectroelastic bimaterials are studied using the generalized Stroh *** types of singularities are ob-tained:one is the oscillating singularity 1/2±iε,the other is the non-oscillating singularity 1/2±κ.It is found that the non-zero parameters ε and κ cannot coexist for one transversely isotropic MEE bimaterial,a similar result is obtained for transversely isotropic piezoelectric bimaterials.

关键词： generalized Stroh formalism magnetoelectroelastic bimaterial interfacial crack singularity index

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Vicissitude of Sogo Nur and environmental-climatic change during last 1500 years

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Science china Earth Sciences 2004年第Z1期47卷 61-70页

作者： JIN Heling, XIAO Honglang, SUN Liangying, ZHANG Hong, SUN Zhong & LI XiaozeKey Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and engineering Research Institute, Chinese Academy of Sciences, lanzhou 730000, china school of Resources and Environment, lanzhou university, lanzhou 730000, china Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China school of Resources and Environment Lanzhou University Lanzhou China

Lakes in arid zone are sensitive to climatic changes. The lacustrine sediment sequence in Sogo Nur has well and truly recorded climatic events such as the Sui-Tang Dynasty Warm Period, the Song-Liao Dynasty Cold Period, the Medieval Warm Period, the Little Ice Age and the 20th Century Warm Period. Commonly, the climate in warm Periods was relatively humid,accordingly the lake area extended and water level rose, and vice versa. Apart from climatic change, human activity is also an important factor of influencing lake vicissitude, and they played the dominant role alternatively during different periods; the factor of climatic change predominated in historical period, while since the beginning of the 20th century the utilization of water resources by human has became decisive.

关键词： granularity, soluble salt, lake vicissitude, climatic change, Sogo Nur.

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A theoretical model of collision between soft-spheres with Hertz elastic loading and nonlinear plastic unloading

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Theoretical & Applied mechanics Letters 2011年第4期1卷 34-39页

作者： Youhe Zhou 1,2,a) 1) Key Laboratory of mechanics on Disaster and Environment in Western china,the Ministry of Education of china 2)Department of mechanics and engineering Science,College of civil engineering and mechanics,lanzhou university,lanzhou 730000,china Key Laboratory of mechanics on Disaster and Environment in Western china the Ministry of Education of China China Department of mechanics and engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

This paper presents a theoretical model on the normal(head-on) collision between soft-spheres on the basis of elastic loading of the Hertz contact for compression process and a nonlinear plastic unloading for restitution one,in which the parameters all are determined in terms of the material and geometric ones of the spheres,and the behaviors of perfect elastic,inelastic,and perfect plastic collisions appeared in the classical mechanics are fully described once a value of coefficient of restitution is specified in the region of 0 ≤ ε ≤ *** an empirical formula of the coefficient of restitution dependent on the impact velocity is suggested to fit the existing experimental measurements by means of the least square method,the predictions of the dependency and the collision duration are in well quantitative agreement with their experimental *** is found that the measurable quantities are dependent on both the impact velocity and the parameters of *** this model,finally,an approach to determine the spring coefficient in the linear viscoelastic model of the collision is also *** results obtained here will be significantly beneficial for the applications where a collision model is requested in the simulations of relevant grain flows and impact dynamics etc..

关键词： normal collision of soft-spheres theoretical model residual displacement restitution coefficient collision duration

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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 university, 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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Improvements on radiation-hardened performance of static induction transistor

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Science china(Information Sciences) 2010年第5期53卷 1089-1096页

作者： WANG YongShun 1 , LUO XianLiang 1 , LI HaiRong 2 , WANG ZiTing 1 , WU Rong 1 , ZHANG CaiZhen 2 & LI SiYuan 2 1 school of Electronic and Information engineering, lanzhou Jiaotong university, lanzhou 730070, china 2 Institute of Microelectronics, school of Physical Science and Technology, lanzhou university, lanzhou 730000, china school of Electronic and Information engineering Lanzhou Jiaotong University Lanzhou China Institute of Microelectronics School of Physical Science and Technology Lanzhou University Lanzhou China

The radiation-hardened performances of static induction transistor (SIT) have been studied in depth in this paper. The effects of radiation of electron beam on the I-V characteristics, carrier distribution and potential distribution in the channel of SIT have been represented. A large number of electron-hole pairs are generated in the depletion region of reversely biased gate-channel PN junction. The radiation-generated electrons drift towards the drain region at high positive potential, while generated holes flow into gate region biased to the lowest potential. With the accumulation of holes in gate region, the gate potential is boosted, resulting in a decrease in the height of potential barrier in channel, and an increase in drain current. I-V characteristics of SIT in the presence of radiation have been theoretically derived, and compared with experimental results. With the increase in thickness of epitaxial layer, the radiation-hardened capability of SIT is continuously improved until the optimum thickness of 26 μm is reached. The optimum matching relationship among geometric, material and technological parameters has been represented to acquire excellent radiation-hardened performances of SIT.

关键词： static induction transistor radiation-resistant potential barrier electron beam radiationgenerated carriers

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Effects of sunspot cycle length and CO_2 on air temperature along Qinghai-Xizang railway and air temperature's trend prediction

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Science china Earth Sciences 2004年第Z1期47卷 131-141页

作者： LI Dongliang, QUO Hui, WANG Wen & WEI LiCold & Arid Regions Environmental and engineering Research Institute, Chinese Academy of Science, lanzhou 730000, china Department of Atmospheric Sciences, lanzhou university, lanzhou 730000, china Cold & Arid Regions Environmental and engineering Research Institute Chinese Academy of Science Lanzhou China Department of Atmospheric Sciences Lanzhou University Lanzhou China

There are well coherences between annual averaged air temperatures at every meteorological station along the Qinghai-Xizang railway, and its 10-year moving average correlation coefficient is 0.92. Thus, the regional averaged annual mean temperature series along the Qinghai-Xizang railway (Trw) from 1935 to 2000 are constructed. The investigation is suggested that: Trw had significant responses to the 5-year lagged sunspot cycle length (SCL) and 15-year lagged concentration of atmospheric carbon dioxide (CO2), and the correlation coefficients between them are -0.76 (SCL) and 0.88 (CO2), respectively. The future SCL is predicted by the model of average generated function constructed with its main cycles of 76a, 93a, 108a, 205a and 275a. The result shows that the SCL would be becoming longer in the first half of the 21st century, and then it could be becoming shorter in the second half of the 21st century. Based on the natural change of SCL and the effect of double CO2 concentration, Trw in the 21st century is forecasted. It could warm up about 0.50℃ in the first half of the 21st century compared with the last decade of last century. The mean maximum air temperature could be likely about 0.20℃ in July and from 0.40℃ to 1.10℃ in January. The annual air temperature difference would likely reduce 0.3-1.00℃. The probability of above predictions ranges from 0.64 to 0.73.

关键词： Qinghai-Xizang railway, annual mean air temperature, sunspot cycle length (SCL), atmospheric carbon dioxide concentration (CO2), prediction.

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