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The influence of impurity on the critical thickness of the CeO_2 buffer layer for coated conductors

science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 993-996页

作者： PAN Min1, HUANG Zheng2, MA HuanFeng2, QIANG WeiRong2, WEI LianFu1, WANG Long2 & ZHAO Yong1,3 1 Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of china), Superconductivity R&D Center (SRDC), southwest jiaotong university, chengdu 610031, china 2 school of physical science and technology, southwest jiaotong university, chengdu 610031, china 3 Superconductivity Research Group, school of Materials science and Engineering, university of New South Wale, Sydney, 2052 NSW, Australia Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of china) Superconductivity R&D Center (SRDC) Southwest Jiaotong University Chengdu 610031 China school of physical science and technology Southwest Jiaotong University Chengdu 610031 China Superconductivity Research Group School of Materials Science and Engineering University of New South Wale Sydney 2052 NSW Australia

The lattice parameters, band structure, density of state and elastic constant of RE-doped CeO2 (RE=Sm, Gd, Dy), the buffer material for coated HTS conductors, are calculated using the plane-wave method with pseudopotentials based on the density functional theory (DFT) of first-principle. The rule and mechanism of the effect of rare earth impurity on the critical thickness of the CeO2 buffer layer are investigated. It is found that, in the range of the calculation, the changes of the lattice volume V and elastic constant E of CeO2 with the impurity are mainly determined by the increased electrons ne of the system. The relationship of the elastic constant E and increased electrons ne is established. It is indicated that the critical thickness of the CeO2 single buffer layer doped with Sm, Gd, and Dy may be enhanced by 22%, 43% and 33%, respectively.

关键词： CeO2 first principle critical thickness elastic constants

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Centroid-based semi-fragile audio watermarking in hybrid domain

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science china(Information sciences) 2010年第3期53卷 619-633页

作者： WANG HongXia & FAN MingQuan school of Information science and technology, southwest jiaotong university, chengdu 610031, china 1. school of Information science and technology Southwest Jiaotong University Chengdu 610031 China

Many previous (semi-) fragile audio watermarking schemes adopt binary images as watermarks, which reduce the security of watermarking systems. On the other hand, the content-based or feature-based second generation digital watermarking has limited applicability, and its partial feature points may be damaged by watermarking operations and various common signal processing. To overcome these problems, in this paper, a novel centroid-based semi-fragile audio watermarking scheme in hybrid domain is proposed. The theoretical lower limit of signal to noise ratio (SNR) for objective evaluation of the imperceptibility of watermarked audio signal is deduced, and the watermark embedding capacity and the tamper detection ability are theoretically analyzed. In the proposed scheme, first, the centroid of each audio frame is computed, then Hash function is performed on the obtained centroid to get the watermark, after that, the audio sub-band which carries centroid of audio frame is performed with discrete wavelet transform (DWT) and discrete cosine transform (DCT), and finally the encrypted watermark bits are embedded into the hybrid domain. Theoretical analysis and experimental results show that the proposed scheme is inaudible and applicable to different types of audio signals. Furthermore, its ability of tamper detection and tolerance against common signal processing operations are excellent. Comparing with the existing schemes, the proposed scheme can effectively authenticate the veracity and integrity of audio content, and greatly expand the applicability of the content-based audio watermarking scheme.

关键词： semi-fragile audio watermarking centroid inaudibility tamper detection

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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 1. school of Maths Southwest Jiaotong University Chengdu 610031 China2. Intelligent Control Development Center Southwest Jiaotong University Chengdu 610031 China

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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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 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

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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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 1. school of Civil Engineering Southwest Jiaotong University Chengdu 610031 China

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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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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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, china 2 State Key Laboratory of Explosion science and technology, Beijing Institute of technology, Beijing 100081, china 3 Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, Lanzhou 730000, china 1. school of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China2. State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China3. Key Laboratory of Frozen Soil Engineering CAREERI CAS Lanzhou 730000 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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Effects of viscosity on shock-induced damping of an initial sinusoidal disturbance

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science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 802-806页

作者： MA XiaoJuan1,LIU FuSheng1 & JING FuQian2 1 College of physical science and technology,southwest jiaotong university,chengdu 610031,china 2 Laboratory for Shock Wave and Detonation Physics Research,Institute of Fluid Physics,Chinese Academy of Engineering Physics,Mianyang 621900,china 1. College of physical science and technology Southwest Jiaotong University Chengdu 610031 China2. Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics Mianyang 621900 China

A lack of reliable data treatment method has been for several decades the bottleneck of viscosity measurement by disturbance amplitude damping method of shock *** this work the finite difference method is firstly applied to obtain the numerical solutions for disturbance amplitude damping behavior of sinusoidal shock front in inviscid and viscous *** water shocked to 15 GPa is taken as an example,the main results are as follows:(1) For inviscid and lower viscous flows the numerical method gives results in good agreement with the analytic solutions under the condition of small disturbance(a0/λ=0.02);(2) For the flow of viscosity beyond 200 Pa s(η=κ) the analytic solution is found to overestimate obviously the effects of *** is attributed to the unreal pre-conditions of analytic solution by Miller and Ahrens;(3) The present numerical method provides an effective tool with more confidence to overcome the bottleneck of data treatment when the effects of higher viscosity in experiments of Sakharov and flyer impact are expected to be analyzed,because it can in principle simulate the development of shock waves in flows with larger disturbance amplitude,higher viscosity,and complicated initial flow.

关键词： viscosity coefficient two-dimensional Eulerian flow shock front sinusoidal disturbance

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Analysis of Earthquake-Triggered Failure Mechanisms of Slopes and Sliding Surfaces

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Journal of Mountain science 2010年第3期7卷 282-290页

作者： WANG Jian YAO Lingkan Arshad Hussain school of Civil Engineering Southwest Jiaotong University Chengdu 610031 China MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong University Chengdu 610031 China Road and Railway Engineering Research Institute Sichuan Key Laboratory of Aseismic Engineering and Technology Chengdu 610031 China National university of sciences and technology (NUST) Islamabad 44000 Pakistan

Earthquake-induced landslides along the Dujiangyan-Yingxiu highway after the Ms 8.0 Wenchuan earthquake in 2008 were investigated. It was found that：（1） slopes were shattered and damaged during the earthquake and open tension cracks formed on the tops of the slopes; （2） the upper parts of slopes collapsed and slid, while the lower parts remained basically intact, indicating that the upper parts of slopes would be damaged more heavily than the lower parts during an earthquake. Large-scale shaking table model tests were conducted to study failure behavior of slopes under the Wenchuan seismic wave, which reproduced the process of deformation and failure of slopes. Tension cracks emerged at the top and upper part of model, while the bottom of the model remained intact, consistent with field investigations. Depth of the tension crack at the top of model is 32 cm, i.e., 3.2 m compared to the prototype natural slope with a height of 14 m when the length scale ratio （proto/model） is lo. Acceleration at the top of the slope was almost twice as large as that at the toe when the measured accelerations on shaking table are 4.85 m/s2 and 6.49 m/s2, which means that seismic force at the top of the slope is twice the magnitude of that at the toe. By use of the dynamic-strength-reduction method, numerical simulation was conducted to explore the process and mechanism of formation of the sliding surface, with other quantified information. The earthquake-induced failure surfaces commonly consist of tension cracks and shear zones. Within 5 mfrom the top of the slope, the dynamic sliding surface will be about 1 m shallower than the pseudo-static sliding surface in a horizontal direction when the peak ground acceleration （PGA） is 1 m/s2; the dynamic sliding surface will be about 2 m deeper than the pseudo-static sliding surface in a horizontal direction when the PGA is lo m/sL and the depths of the dynamic sliding surface and the pseudo-static sliding surface will be almost the sam

关键词： Subgrade engineering slope failuremechanism shaking table model test: seismicsliding surface Wenchuan earthquake

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