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3D thermo-hydro-mechanical-migratory coupling model and FEM analyses for dual-porosity medium

Science china(Technological Sciences) 2010年第8期53卷 2172-2182页

作者： ZHANG YuJun 1&ZHANG WeiQing 2 1 State Key Laboratory of Geomechanics and Geotechnical engineering,Institute of Rock and Soil Mechanics, Chinese Academy of Sciences,Wuhan 430071,china 2school of civil engineering,southwest jiaotong university,chengdu 610031,china State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences school of civil engineering Southwest Jiaotong University

One kind of 3D coupled thermo-hydro-mechanical-migratory model for saturated-unsaturated dual-porosity medium was established,in which the stress field and the temperature field are single,but the seepage field and the concentration field are double,and the influences of sets,spaces,angles,continuity ratios,stiffness of fractures on the constitutive relationship of the medium can be *** relative three-dimensional program of finite element method was also *** comparing with the existing computation example,reliability of the model and the program were *** a hypothetical nuclear waste repository as a calculation example,the radioactive nuclide leak was simulated numerically with both the rock mass and the buffer being unsaturated media,and the temperatures,negative pore pressures,flow velocities,nuclide concentrations and normal stresses in the rock mass were *** results showed that the temperatures,negative pore pressures and nuclide concentrations in the buffer all present nonlinear changes and distributions that even though the saturation degree in porosity is only about 1/9 of that in fracture,the flow velocity of underground water in fracture is about 6 times of that in porosity because the permeability coefficient of fracture is almost four orders higher than that of porosity,and that the regions of stress concentration occur at the vicinity of two sides of the boundary between buffer and disposal pit wall.

关键词： dual-porosity medium thermo-hydro-mechanical-migratory coupling three-dimensional model FEM analysis

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Experimental study of CT test on the failure of acrylate spray-applied waterproof layer in the groundwater environment

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Science china(Technological Sciences) 2010年第2期53卷 512-518页

作者： YANG QiXin, XU Peng & ZHENG ShangFeng 1 school of civil engineering, southwest jiaotong university, chengdu 610031, china school of civil engineering Southwest Jiaotong University

In this study the computerized tomography (CT) was first used to quantitatively analyze the failure of acrylate spray-applied waterproof membrane in the groundwater environment. The results of the CT tests show that it is feasible to use the CT to quantitatively analyze the failure of the waterproof membrane and the CT method has the advantages of speediness and accuracy that can eliminate the fussy operation process in routine tests. The main conclusions summarized from the study are as follows. First, there are two combined-indexes that can be used to decide the failure of the spray-on waterproof layer: one is that the reduced percentage of the CT number of the spray-on waterproof layer is less than 40.0% and the other is that the variance of the CT number decreases first and then increases. Second, the applicability for the spray-on waterproof layer in the groundwater environment is the SO 24-concentration ≤ 1%, the Cl-concentration ≤ 7.5% and the pH value ≤ 12.0 of the groundwater, respectively.

关键词： spray-on waterproof layer scan CT number failure groundwater environment

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Semantic theory of finite lattice-valued propositional logic

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Science china(Information Sciences) 2010年第10期53卷 2022-2031页

作者： PAN XiaoDong 1,2 & XU Yang 2 1 school of Maths, southwest jiaotong university, chengdu 610031, china 2 Intelligent Control Development Center, southwest jiaotong university, chengdu 610031, china school of Maths Southwest Jiaotong University Intelligent Control Development Center Southwest Jiaotong University

Based on the methodology of Pavelka’s fuzzy propositional logic, in this paper, by combining L-fuzzy set and classical two-value propositional logic theory, a kind of graded semantic theory in lattice-valued propositional logic based on finite lattice implication algebras is established. The notions of L-tautology and L-contradiction are introduced, and several theorems about the relations among different kinds of L-tautologies are given. From the viewpoint of uncertainty reasoning, the notion of satisfiability with certain level for a set of formulas is also defined. On this basis, the semantic consequence operation concerning a set of formulas is proposed, and the properties of semantic consequence operation and the consistency of fuzzy information are discussed.

关键词： lattice-valued propositional logic semantic theory L-tautology consistency lattice implication algebra

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Strengths and Fracture Mechanisms of Al_2O_3 Short Fiber Reinforced Al-Mg Alloy Matrix Composite at Elevated Temperatures

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Journal of Materials Science & Technology 2002年第3期18卷 257-260页

作者： Guozheng KANGDepartment of Applied Mechanics and engineering, southwest jiaotong university, chengdu 610031, chinaChuan YANG and Jixi ZHANGDepartment of Materials engineering, southwest jiaotong university, chengdu 610031, china [ Manuscript received Janu Dept. of Appl. Mech. and Eng. Southwest Jiaotong Univ. Chengdu 610031 China

Using the experimental and theoretical methods, the tensile strengths and fracture mechanisms of AI2O3 short fiber reinforced AI-Mg alloy matrix composite at elevated temperatures were researched. The interfacial microstructural characteristics and the fracture surfaces of the composite at different temperatures were observed by transmission electron microscope (TEM) and by scanning electron microscope (SEM), respectively. Then, from the results of microscopic observation, the fracture mechanisms of the composite at different temperatures are discussed. Finally, the tensile strengths of the composite at elevated temperatures were predicted by statistical integration average (SIA) method with the consideration of various fracture mechanisms. It was shown that the strengths and fracture mechanisms of the composite at elevated temperature (300℃) were significantly different from those at room temperature due to the variations of interfacial bonding states. The tensile strengths predicted by the SIA method at elevated temperatures agreed well with the experimental results.

关键词： Fracture A12O3 Al-Mg alloy Composite

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Self-organized criticality and its application in the slope disasters under gravity

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Science china(Technological Sciences) 2003年第Z1期46卷 20-30页

作者： YAO Lingkan, HUANG Yuan & LU Yang school of civil engineering, southwest jiaotong university, chengdu 610031, china southwestern Institute of Physics, chengdu 610031, china SW jiaotong Univ Sch Civil Engn Chengdu 610031 Peoples R China SW Inst Phys Chengdu 610031 Peoples R China

Firstly, three kinds of sand pile experiments which reflect the universal process of energy dissipation within the slope accumulation under the self-organized action are reviewed. They all show that self-organized criticality (SOC) is related to granular non-uniform. The experiment of Tokamak plasma system is introduced, which shows some of SOC properties of Tokamak plasmas in Ohmic region or L-mode. Secondly, material tests in geotechnical engineering and numerical simulations of micro-structure of sand piles indicate that SOC is determined by the structural characteristics. Finally, according to the principle of SOC, the behavior of slope disasters under gravity and its forecast as well as the design of protection engineering are discussed.

关键词： SOC, sand pile experiment, experiment of Tokamak plasma system, slope disasters under gravitation force.

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Experimental Study of Tunnel Fire with Natural Ventilation

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湖南大学学报（自然科学版） 2009年第S1期36卷 23-25页

作者： YUAN Zhong-yuan,LEI Bo,CHEN Peng-yun(school of Mechanical engineering,southwest jiaotong university,chengdu,Sichuan 610031,china) school of Mechanical engineering Southwest Jiaotong University Chengdu 610031 China

The 1/15 reduced-scale experiments using Froude scaling were designed to study the effect on the smoke control efficiency for subway tunnel fires with natural ventilation *** propane gas fires with heat release rate 11.48 kW was used,which corresponds to the heat release rate 10 MW in the full-scale *** temperature distributions under the ceiling were measured by K-type thermocouples to investigate smoke movement,and the velocity of smoke in shafts was measured by hot-wire anemometer to obtain the smoke extract amount of ventilation *** results show that the smoke temperature under the ceiling varies with the longitudinal different distance from fire *** results also show that the smoke temperature distributions and the smoke control efficiency in tunnel vary with the space between ventilation shafts and vary with the area and the height of ventilation shaft.

关键词： natural ventilation mode metro tunnel fire reduced-scale experiments froude scaling

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A new real-time eye tracking based on nonlinear unscented Kalman filter for monitoring driver fatigue

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控制理论与应用（英文版） 2010年第2期8卷 181-188页

作者： Zutao ZHANG 1 , 2 , Jiashu ZHANG 2 (1.school of Mechanical engineering, southwest jiaotong university, chengdu Sichuan 610031, china 2.Sichuan Key Lab of Signal and Information Processing, southwest jiaotong university, chengdu Sichuan 610031, china) school of Mechanical engineering Southwest Jiaotong University Chengdu Sichuan China Sichuan Key Lab of Signal and Information Processing Southwest Jiaotong University Chengdu Sichuan China

A new scheme for driver fatigue detection is presented, which is based on the nonlinear unscented Kalman filter and eye tracking. Assuming a probability distribution than to approximate an arbitrary nonlinear function or transformation, eye nonlinear tracking can be achieved using an unscented transformation (UT), which adopts a set of deterministic sigma points to match the posterior probability density function of the eye movement. Driver fatigue can be detected using the percentage of eye closure (PERCLOS) framework in a realistic driving condition after the eye nonlinear tracking. This system was tested adequately in realistic driving environments with subjects of different genders, with/without glasses, in day/night driving, being commercial/noncommercial drivers, in continuous driving time, and under different road conditions. The last experimental results show that the proposed method not only improves the robustness for nonlinear eye tracking, but also can provide more accurate estimation than the traditional Kalman filter.

关键词： Eye tracking Unscented Kalman filter (UKF) Fatigue detection PERCLOS

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Frequency/time hopping sequence sets with optimal partial Hamming correlation properties

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Science china(Information Sciences) 2012年第10期55卷 2207-2215页

作者： NIU XianHua 1,2,PENG DaiYuan 1 & ZHOU ZhengChun 3 1 The Provincial Key Laboratory of Information Coding and Transmission,Institute of Mobile Communications,southwest jiaotong university,chengdu 610031,china 2 The school of Mathematics and Computer engineering,Xihua university,chengdu 610039,china 3 The College of Maths,southwest jiaotong university,chengdu 610031,china The Provincial Key Laboratory of Information Coding and Transmission Institute of Mobile Communications Southwest Jiaotong University Chengdu China The school of Mathematics and Computer engineering Xihua University Chengdu China The College of Maths Southwest Jiaotong University Chengdu China

Frequency hopping/time hopping(FH/TH) sequences have found wide applications in various modern FH/TH spread spectrum communications,such as digital cellular mobile communication,short-range wireless communication,personal communication,and multi-user radar,sonar *** order to evaluate the goodness of FH/TH sequences design,the periodic Hamming correlation function is used as an important ***,the length of correlation window is shorter than the period of the chosen FH/TH sequence,so the study of the partial Hamming correlation of FH/TH sequence is particularly *** this paper,a new class of FH/TH sequence sets with good partial Hamming correlation properties is proposed and *** construction of new FH/TH sequence sets is based upon the generalized m-sequence and generalized Gordon-Mills-Welch sequence over a polynomial residue class *** is shown that new FH/TH sequence sets are optimal with respect to the partial Hamming correlation bound.

关键词： frequency hopping/time hopping(FH/TH) sequence partial Hamming correlation optimal FH/TH sequence set

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Tensile Elastic Modulus, Strength and Fracture of δ-Al_2O_(3f)/Al Alloy Composites

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Journal of Materials Science & Technology 2000年第5期16卷 475-480页

作者： GuoZheng KANG+, Qing GAO and Jixi ZHANG (Department of Applied Mechanics and engineering, southwest jiaotong university, chengdu 610031, china) Department of Applied Mechanics and engineering Southwest Jiaotong University Chengdu 610031 China

Based on the experimental and theoretical analysis, the tensile elastic modulus, strength and fracture characteristics of squeeze casting δ-Al2O3/Al alloy composites were studied. The fracture characteristics of composites were observed by SEM. The elastic modulus was predicted by the finite element method based on the energy equivalence principle, and the strength was predicted by the statistical integration average method using the maximum energy criterion of composite strength. In the prediction, the distribution density functions of the fiber's. orientation and length were considered. These functions were gained by experimental measurement. It is shown that the predicted results are in agreement with the experimental values well and the microstructure feature of composites controls the fracture characteristics.

关键词： Tensile Elastic Modulus Al2O

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Roadbed Subsidence Prediction and Its Security Evaluation

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岩石力学与工程学报 2002年第9期21卷 1368-1371页

作者： Li Yongshu 1,Han Liping 2 (1 school of civil Eng.,southwest jiaotong university,chengdu 610031 china) (2 school of Computer and Comm. Eng.,southwest jiaotong university,chengdu 610031 china) school of civil Eng. Southwest Jiaotong University Chengdu 610031 school of Computer and Comm. Eng. Southwest Jiaotong Uiversity Chengdu 610031

A roadbed subsidence pattern for predicting the security of roadbed in ground subsidence area with complicated structure strata and any shape of excavations is proposed in this paper. The methods for computing the values of the movements and deformations of the roadbed characteristic points are investigated. The calculating formulae for predicting the roadbed subsidence,inclined deformation,curvature deformation,horizontal displacement and horizontal deformation are provided. The methods for evaluating roadbed security and predicting disastrous accidents of roadbed in ground subsidence area are also discussed. Finally,a practical example is given for applying the method to evaluate roadbed security.

关键词： roadbed subsidence prediction

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