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Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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Science China(Technological Sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1.2. CAI Hongnian1. ZHANG Xinming2. WANG Fuchi1.& TAN Chengwen1.3.1. School of Material Science and Engineering, beijing Institute of Technology, beijing 1.0081. China 2. School of Material Science and Engineering, Central South {2., Changsha 41.083. China 3. School of Material Science and Engineering, beijing {2. of Aeronautics and Astronautics, beijing 1.0083. China School of Material Science and Engineering Beijing Institute of Technology Beijing China School of Material Science and Engineering Central South University Changsha China School of Material Science and Engineering Beijing University of Aeronautics and Astronautics Beijing China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112.and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

A new method for multi-exponential inversion of NMR relaxation measurements

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Science China(Physics,Mechanics & Astronomy) 2004年第3期47卷 265-276页

作者： WANG Zhongdong1. 2. XIAO Lizhi1.& LIU Tangyan1.1. Petroleum {1., beijing 1.2.49, China 2. Liaohe Petroleum Administration, Panjin 1.0}01., China Petroleum university{1.China Liaohe Petroleum AdministrationPanjinChina

A new method for multi-exponential inversion to NMR T1.and T2.relaxation time distributions is suggested and tested. Inversion results are compared with MAP-II which is based on SVD algorithm and widely accepted in the industry. Inversed NMR relaxation spectra that have different pre-assigned relaxation times from echo trains with different SNR confirm that the new method with 1. to 64 equally spaced time constants in logarithm scale will ensure the relaxation distribution. Testing results show that the new inversion algorithm is a valuable tool for rock core NMR experimental analysis and NMR logging data process and interpretation.

关键词： NMR, inversion, relaxation, core analysis, well logging.

Density-functional formula for strongly correlated systems

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Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1.*, HAN Rushan2.and CHEN Nanxian1.1. Department of Physics, Tsinghua {1., beijing 1.0084, China 2. Department of Physics, Peking {1., beijing 1.0871. China) Dept. of Phys. Tsinghua Univ. Beijing 100084 China Dept. of Phys. Peking Univ. Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

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Science China Earth Sciences 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1. XIE Hongsen1. LIU Yonggang1. ZHENG Xiaogang1. ZHAO Zhidan2.& ZHOU Hui3.1. Laboratory of Material in the Earth’s Interior, Institute of {1.chemistry, Chinese Academy of Sciences, Guiyang 550002. China 2. Department of {1.logy, China {2. of {1.sciences, beijing {13. China 3. Department of {1.logy, Peking {2., beijing 1.0871. China Laboratory of Material in the Earth’s Interior Institute of Geochemistry Chinese Academy of Sciences Guiyang China Department of geology China University of Geosciences Beijing China Department of geology Peking University Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12.2.0 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12.h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12.2.0 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12.h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.

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 Sciences, {1. 1.0080, China 2. Graduate School, Chinese Academy of Sciences, {1. 1.0060, China 3. Tropical Marine Science Institute, National {2. of Singapore, Singapore 1.92.0 Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100060 China Tropical Marine Science Institute National University of Singapore 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.

The kink-soliton and antikink-soliton in quasi-one-dimensional nonlinear monoatomic lattice

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 150-157页

作者： XU Quan1.& TIAN Qiang2.1. Scientific and Technological Office, Daqing Teacher College, Daqing 1.3.1.0} China 2. Department of Physics , beijing Normal university, beijing 1.0875, China Scientific and Technological Office Daqing Teacher College Daqing China Department of Physics Beijing Normal University Beijing China

The quasi-one-dimensional nonlinear monoatomic lattice is analyzed. The kink-soliton and antikink-soliton are presented. When the interaction of the lattice is strong in the x-direction and weak in the y-direction, the two-dimensional (2.) lattice changes to a quasi-one-dimensional lattice. Taking nearest-neighbor interaction into account, the vibration equation can be transformed into the KPI, KPII and MKP equation. Considering the cubic nonlinear potential of the vibration in the lattice, the kink-soliton solution is presented. Considering the quartic nonlinear potential and the cubic interaction potential, the kink-soliton and antikink-soliton solutions are presented.

关键词： two-dimensional nonlinear lattice, quasi-one-dimensional nonlinear lattice, kink-soliton, antikink-soliton.

A numerical method for spherical particle motion in turbulent flow with large Reynolds number

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Journal of Environmental Sciences 1999年第4期11卷 407-414,442页

作者： ZHANG Yong\|ze\+1. LI Jia\+2. LI Ke feng\+2. WANG Xuan\+3.(1. Chinese Research Academy of Environmental Sciences, beijing 1.001.0} China 2. Sichuan university, Chengdu 61.065, China 3. beijing Normal university, beijing 1.0875, China) 中国环境科学院标准所北京四川大学高速水力学国家重点实验室四川成都北京师范大学环科所北京

A new mathematical model, fluctuation spectrum random trajectory model (FSRTM) for the particle motion in environmental fluid was developed using Lagrangian method, in which the time mean velocity of the fluid was calculated by a time mean velocity formula for two dimensional homogeneous shear turbulent flows in open channel, the velocity fluctuation of the fluid was determined by Fourier expansion and fluctuation spectrum, and the particle motion equation was solved using Ronge Kutta method. For comparison, the spherical cation exchange resins with a density of 1. 44 g/cm\+3.and diameters ranging from 0 50—0 60 mm, 0 60—0 70 mm and 0 80—0 90 mm were selected as the experimental solid particles, and their moving velocities and trajectories in shear turbulent flows with the flow Reynolds number of 471., 1.{3.0, 1.900 and {3.760 were investigated. The comparing analyses of the modeled results with the measured results have shown that the model developed in this paper can describe the motions of the particles in shear turbulent flow.

关键词： shear turbulent flow particle motion fluctuation spectrum random trajectory model

Discovery of Paleogene marine stratum along the southern side of Yarlung-Zangbo suture zone and its implications in tectonics

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Science China Earth Sciences 2005年第5期48卷 647-661页

作者： LI Guobiao 1., WAN Xiaoqiao 1., LIU Wencan 1., LIANG Dingyi 1.& Hyesu Yun 2.1. China {1. of geosciences, {2. 1.0083. China 2. Chungnam National {1., Daejon, 3.5-3.0, Korea China university of {1.sciences Beijing China Chungnam National university Daejon Korea

The Jiachala Formatiom is a new lithostratigraphic unit set up in this paper. This is the first report on the Paleogene marine sequences and microfaunas in Gyangze to the southern side of the Yarlung-Zangbo suture zone. On the basis of fossil abundance, species diversity, dominant species and first and last occurrences of key species, three dinoflagellate assemblages and three polynological assemblages were recognized in the Jiachala Formatiom. They are in ascending order as follows: Apectodinium quinquelatum-Apectodinium hyperacanthum, Cannin- gia chinensis-Palaeoperidinium pyrophorum and Cymatiosphaera reticulosa-Samlandia chla- mydophora dinoflagellate assemblages, and Arliaceoipollenites baculatus-Anacolosidites sub- trudens, Aglaoreidia cyclops-Pinuspollenites microinsigis, and Elaeangnacites asper-Ilexpol- lenites iliacus polynological Assemblages. According to the assemblages, the age of the Jiachala Formation is referred to Paleocene-early Eocene. The preliminary study on the Jiachala Forma- tion shows that this group of Paleogene deposits accumulated in an underfilled peripheral fore- land basin which was in response to the load of the crust thickening resulted from the Asia-India collision. The stratigraphic evidences provided by the evolution of foreland basin indicate that the India-Asia initional collision should occure near the Cretaceous/Paleogene boundary. The de- velopment and evolution of the southern Tibet foreland basin was under the control of the stress field from the subduct-collision between India and Asia and the structure pattern of the basement. The withering of Tethys Sea might occur after early Eocene in the Gyangze basin and should be after Priabonian of late Eocene in southern Tibet.

关键词： Paleogene marine strata, Jiachala Formation, microfossils, underfilled peripheral foreland basin, initional collision, Gyangze.

Some properties on multivariate filter banks with a matrix factorization

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Progress in Natural Science:Materials International 2005年第2期15卷 20-30页

作者： LIAN Qiaofang1. XIAO Hongying2. and CHEN Qiuhui3.1. Department of Mathematics, {1. Jiaotong university, {1. 1.0044, China 2. Institute of Mathematics, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, {1. 1.0080, China 3. Department of Scientific Computing and Computer Applications, Zhongshan university, Guangzhou 51.2.5, China) Dept. of Mathematics Beijing Jiaotong Univ. Beijing 100044 China Inst. of Mathematics Acad. of Math. and System Sci. Chinese Acad. of Sciences Beijing 100080 China Dept. of Scientific Computing Zhongshan Univ. Guangzhou 510275 China

A class of multivariate filter banks with a matrix factorization has been developed by Chen et al. The main purpose of this paper is to discuss some further properties of this kind of filter bank, such as the completeness, accuracy of the corresponding scaling functions and the relationships with Daubechies' wavelets and the multi-wavelets provided by Chui and Lian. Moreover, some examples are given to show that this kind of filter bank has a higher accuracy for the scaling functions.

关键词： filter banks completeness accuracy matrix factorization