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Research on forecasting model of sandstone deformation rate during sine wave loading segment under the lag effect

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Science China(Technological Sciences) 2010年第5期53卷 1442-1449页

作者： LIU Jie1,2,LI JianLin1,2,QU JianJun1,ZHOU JiFang3.ZHANG ChaoFeng3.& LI JianWu1 1Key Laboratory of Geological Hazards on three gorges Reservoir Area,Ministry of Education,China three gorges university,yichang 443.02,China 2College of Civil and Hydropower Engineering,China three gorges university,yichang 443.02,China 3.r’tan Hydropower Development Company,Ltd.Chengdu 61000,China Key Laboratory of Geological Hazards on three gorges Reservoir Area Ministry of Education China Three Gorges University College of Civil and Hydropower Engineering China Three Gorges University

To reduce data variance caused by individual differences of different samples,a new experimental method is proposed by loading and unloading the axial forces with different frequencies and different waves of a certain load amplitude to the same rock sample without damaging *** time segments are defined and fractionized into segments I and Ⅱ.Criterions for seg-mentation,definitions of relevant parameters and empirical analysis are also offered *** the course of sinusoidal loading,the serious peak value dislocation of the displacement variation rate and the loading rate is defined as peak ***,the definition of the apparent tangent modulus is put forward and the linear relation between it and the vertical force in the frequency of 0.1,0.2,0.5 Hz sinusoidal loading segment is confirmed to be ever-present on the basis of the test *** the calculating formula of the deformation rate in non-lag time is *** is thus suggested that the deformation rate should be codetermined by the loading rate df/dt and instant load f(t),which well explains the peak dislocation of the time-variable curve peak value of dl/dt and deformation rate of df/*** the lag time derivation model is established and by comparing the calculated values with the measured ones,it is demonstrated that the above formula offers a better simulation of the sandstone deformation rate in the sinusoidal loading segment,with the load amplitude being 96 kN and the frequency ranging from 0.1 Hz to 0.5 Hz.

关键词： lag time segments peak shifting phenomenon apparent tangent modulus deformation rate

Anisotropic damage coupled modeling of saturated porous rock

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Science China(Technological Sciences) 2010年第10期53卷 2681-2690页

作者： LU YingFa1,2, WU XinXing1,2 & SHAO JianFu3.1 Key Laboratory of Geological Hazards on three gorges Reservoir Area, Ministry of Education, China three gorges university, yichang 443.02, China 2 School of Civil Engineering, Wuhan university, Wuhan 43.071, China 3.university of Sciences and Technologies of Lille, Lille 59655, France Key Laboratory of Geological Hazards on three gorges Reservoir Area Ministry of Education China Three Gorges University School of Civil Engineering Wuhan University university of Sciences and Technologies of Lille

It is widely acknowledged that the natural rock mass is anisotropic and its failing type is also non-isotropic. An orthotropic elastic damaged model has been proposed in which the elastic deformation,the damaged deformation and irreversible deformation can be identified respectively. A second rank damage tensor is employed to characterize the induced damage and damage evolution related to the propagation conditions of microcracks. A specific form of the Gibbs free energy function is used to obtain the effective elastic stiffness and the limited scopes of damage parameters are suggested. The model’s parameter determination is proposed by virtue of conventional tri-axial test. Then,the proposed model is developed to simulate the coupled hydraulic mechanical responses and traction behaviors in different loading paths of porous media.

关键词： anisotropy damage modeling saturated rock tensile failure

Study on the two and three-parameter working stability regions of 3.-TZP suspension

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Science China(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2, ZHANG Xinni3. CHEN Sha’ou3.& QI Ping3.1. Department of Chemistry, Qingdao university, Qingdao 266071, China 2. Department of Chemistry, Tsinghua university, Beijing 100084, China 3. Department of Physics, Qingdao university, Qingdao 266071, China Department of Physics Qingdao University

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3.-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3.-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3.-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3.-TZP, suspension, stability, DLVO theory, interparticle potential energy.

The feature study on the π and proton rapidity distributions at AGS, SPS and RHIC

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 198-206页

作者： FENG ShengQin1,2 & YUAN XianBao1,3.1 College of Science, China three gorges university, {3., China 2 School of Physics and Technology, Wuhan university, Wuhan 43.072, China 3.Institute of Particle Physics, Central China Normal university, Wuhan 43.070, China College of Science China Three Gorges University Yichang China School of Physics and Technology Wuhan University Wuhan China Institute of Particle Physics Central China Normal University Wuhan China

The features of nuclear stopping power and multi-hadron production systematically are studied by making an analysis of rapidity distributions of pion and proton at AGS, SPS and RHIC in this work. It is found that nuclear stopping power increases linearly with project rapidity yp at AGS and SPS, but that is not liner at RHIC. It is argued that the average rapidity loss is saturated at central rapidity region at RHIC. For pion distribution, it is found that the phase space of pion distribution distributes uniformly in the longitudinal direction,and a linear relationship of L with log s is given at AGS and SPS. Non-uniform flow model may explain the features of the distribution at AGS and SPS, but may not ex- plain those of at RHIC.

关键词： non-uniform flow model average rapidity loss baryon number density nuclear stopping power

Minimum Exact Cover Problem of Group Key Distribution

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Wuhan university Journal of Natural Sciences 2009年第2期14卷 137-142页

作者： FU Xiong1,2, XU Shouzhi3.1. School of Law ,Wuhan university, Wuhan 43.072, Hubei, China 2. Department of Technology, Guangzhou Luogang District People’s Court, Guangzhou 51073., Guangdong, China 3. College of Electronic Engineering and Information Technology, China three gorges university, yichang 443.02, Hubei, China School of Law Wuhan University Wuhan China Department of Technology Guangzhou Luogang District People’s Court Guangzhou China College of Electronic Engineering and Information Technology China Three Gorges University Yichang China

Secure group communications are restrained by the number of the group size, number of changes and their distribution, all existing works do not meet the commands of applications with large group size and high dynamic members. In this paper, minimum exact cover problem for group key distribution （GMECP） is presented, and a heuristic solution is testified. Then an algorithm of batch rekeying with renewing cost tending to zero is illustrated, which can process any large number of change requests with best security guaranteed. Efficiency analysis and simulation test show that the achievement can improve the efficiency of any tree-based group key management.

关键词： minimum exact cover problem group key distribution secure multicast group key management

Fault diagnosis based on high-gain observer with an update law for a class of nonlinear systems

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控制理论与应用（英文版） 2010年第4期8卷 447-452页

作者： Yanjun SHEN (College of Science,China three gorges university,{3. Hubei 443.02,China) College of Science China Three Gorges University Yichang Hubei China

In this paper,by using the well-known high-gain observer design,an update law for the gain and an adaptive estimation of parameters,a new method of fault diagnosis for a class of nonlinear systems is *** resort to any transformation for the parameters,the estimation errors of the states and the parameters are guaranteed to be globally exponentially convergent by a persistent excitation *** to the existing results,it can be applied to nonlinear systems with nonlinear terms admitting an incremental rate depending on the measured output.A case study further verifies the validity of the proposed research.

关键词： Fault diagnosis Adaptive estimation High-gain observer Nonlinear systems

Global analysis on slope stability and its engineering application

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Science China(Technological Sciences) 2009年第2期52卷 507-512页

作者： ZHENG Hong1,2 & ZHOU ChuangBing3.1 State Key Laboratory of Geomechanics and Geotechnical Engineering, Wuhan 43.071, China 2 China three gorges university, Key Laboratory of Geological Hazards on three gorges Reservoir Area, Ministry of Education, Yi Chang 443.02, China 3.School of Civil Engineering, Wuhan university, Wuhan 43.072, China State Key Laboratory of Geomechanics and Geotechnical Engineering China three gorges university Key Laboratory of Geological Hazards on Three Gorges Reservoir Area Ministry of Education School of Civil Engineering Wuhan University

In hydraulic engineering, sometimes it is necessary to consider the stability of sliding bodies with lateral frictional boundaries. Neither the existing three dimensional limit equilibrium methods nor the commercial software products are able to treat such situations. The three dimensional factor of safety is accordingly underestimated; while the shearing strength based on the three dimensional back analysis is overestimated. In this study, the lateral boundaries are regarded as the part of the slip surface. Based on the expression of the normal pressure on the slip surface and the patch interpolation, a rigorous solution for the three dimensional limit equilibrium analysis is realized. Meanwhile, the proposed procedure is applied to the stability analysis of the slope with a cable platform on the right bank in Da Gang Shan hydraulic project under construction.

关键词： slope stability the limit equilibrium methods three dimensional problems

Coupling analysis of unsteady seepage and stress fields in discrete fractures network of rock mass in dam foundation

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Science China(Technological Sciences) 2011年第S1期54卷 133-139页

作者： CHAI JunRui 1,2 & XU WeiSheng 2 1 College of Hydraulic and Environmental Engineering,China three gorges university,{3.,China 2 College of Hydropower Engineering,Xi’an university of Technology,Xi’an 710048,China College of Hydraulic and Environmental Engineering China Three Gorges University College of Hydropower Engineering Xi"an University of Technology

The drag force of water flow through single fracture and the coupling characteristics of seepage and stress in single fracture surface are analyzed,and a three dimensional model of coupled unsteady seepage and stress fields is *** model is used to the analysis of foundation rock mass of a high *** the coupling effects are considered,the changes of boundary heads have less influence on the inner head of rock mass,and the strong permeability of main fractures *** the coupling effects are not considered,the fractures distribution affects the inner head more *** the upstream water head declines,the inner head of dam foundation slightly declines and the hydraulic gradient distribution becomes smoother.A bigger upstream water level declining velocity has a stronger lag effect,meanwhile the values of stress components change more *** the upstream water level declining velocity directly affects the stability of rock mass in dam foundation and we should take into account the above factors to make sure the safety of the dam during reservoir level fluctuation period.

关键词： hydraulic engineering unsteady seepage stress coupling fractures network rock mass

Ecological hydrograph based on Schizothorax chongi habitat conservation in the dewatered river channel between Jinping cascaded dams

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Science China(Technological Sciences) 2011年第S1期54卷 54-63页

作者： LI RuoNan 1,CHEN QiuWen 1,2 & Duan Chen 1,3.1 Research Center for Eco-environmental Science,Chinese Academy of Sciences,Beijing 100085,China 2 China three gorges university,{3.,China 3.Hydraulics Department,Changjiang River Scientific Research Institute,Wuhan 43.010,China Research Center for Eco-environmental Science Chinese Academy of Sciences China three gorges university Hydraulics Department Changjiang River Scientific Research Institute

Hydropower development changes the river hydrological regime,thereby altering river ecosystem *** important measure for reducing degradation of ecosystem is to determine ecological flow and implement it by reservoir *** paper described a method to calculate river ecological flow based on fish habitat conservation and applied it to Jinping River Bend of Yalong *** chongi was selected as target species,and the fish habitat model coupling with water environmental model was developed according to the relationship between fish and water environment ***,improved hydraulic habitat suitability index(IHHS) and habitat fragment index(HFI) varying with discharge were discussed in this *** area representing average annual flow was taken as a reference,and then ecological hydrographs under different habitat conservation levels were calculated considering season variation and life stages of *** to the natural condition,the model results indicated that the reservoir operation clearly influenced the habitat of the target *** was proposed to ensure flow releases to maintain 70%-90% habitat in section after joint while about 60% before joint.

关键词： river habitat habitat assessment ecological flow ecological hydrograph