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Developing an Instantaneous Response Surface Method t-IRS for time-dependent Reliability Analysis

Acta Mechanica Solida Sinica 2019年第4期32卷 446-462页

作者： Junxiang Li Jianqiao Chen Junhong Wei Xiaosheng Zhang Ben Han Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

In practical engineering, many uncertain factors in loading or degradation of material properties may vary with time. Stochastic process modeling constitutes a suitable approach for describing these time-dependent uncertainties. By adopting this approach, however, the timedependent reliability calculation is a great challenge owing to the complexity and the huge computational burden. This paper presents a new instantaneous response surface method t-IRS for time-dependent reliability analysis. Different from the adaptive extreme response surface approach, the proposed method does not need to build and update surrogate models separately at each time node. It first uses the expansion optimal linear estimation method to discretize the stochastic processes into a set of independent standard normal variables together with some deterministic functions of time. time is then treated as an independent one-dimensional variable. Next, initial samples are generated by Latin hypercube sampling, and the corresponding response values are calculated and utilized to construct an instantaneous response surrogate model of the Kriging type. The active learning method is applied to update the Kriging surrogate model until satisfactory accuracy is achieved. Finally, the instantaneous response surrogate model is used to compute the time-dependent reliability via Monte Carlo simulation. Four case studies are utilized to demonstrate the effectiveness of the ^-IRS method for time-dependent reliability analysis.

关键词： time-dependent reliability Stochastic process Instantaneous response surface method i-IRS Expansion optimal linear estimation method Kriging surrogate model

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Nonlinear time-dependent simulation of helix traveling wave tubes

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Chinese Physics B 2011年第7期20卷 483-489页

作者：彭维峰杨中海胡玉禄李建清陆麒如李斌 Vacuum Electronics National Laboratory University of Electronic Science and Technology of China

A one-dimensional nonlinear time-dependent theory for helix traveling wave tubes is studied. A generalized electromagnetic field is applied to the expression of the radio frequency field. To simulate the variations of the high frequency structure, such as the pitch taper and the effect of harmonics, the spatial average over a wavelength is substituted by a time average over a wave period in the equation of the radio frequency field. Under this assumption, the space charge field of the electron beam can be treated by a space charge wave model along with the space charge coefficient. The effects of the radio frequency and the space charge fields on the electrons are presented by the equations of the electron energy and the electron phase. The time-dependent simulation is compared with the frequency-domain simulation for a helix TWT, which validates the availability of this theory.

关键词： helix traveling wave tubes time-dependent harmonics helix pitch taper

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Establishing time-dependent model of deformation modulus caused by bedrock excavation rebound by inverse analysis method

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Science China(Technological Sciences) 2008年第S2期51卷 1-7页

作者： WU ZhongRu1,2,GU YanChang1,3,GU ChongShi1,2,GUO HaiQing1 & SU HuaiZhi1,2 1 Hohai University,Nanjing 210098,China 2 National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Nanjing 210098,China 3 Nanjing Hydraulic Research Institute,Nanjing 210029,China Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing China Nanjing Hydraulic Research Institute Nanjing China

Rock rebound relaxation deformation,or even rock burst,caused by the excavation of dam base and abutment or high rock slope affects their stability and results in the fall of mechanical properties of the rock.So an inverse analysis method was proposed in this paper to establish the time-dependent model of deformation modulus caused by excavation rebound.The basic principle is based on the combination of observed data of the excavation rebound deformation of dam abutment or rock slope,and the calculated rebound deformation by FEM under ground stress at the corresponding time in the excavation process.The norm of the residuals of observed data and calculated data are taken as the objective function.Accordingly,the time-dependent model of bedrock deformation modulus can be established.The method displays its significance in the design of excavation,construction and operation management of dam base and high slope.

关键词： dam base rebound deformation modulus inverse analysis method time-dependent model Xiaowan Hydropower Station

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Dynamic simulation of the effect of time-dependent variation of pH on response variable of the tailing thickener of coal washing plant

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International Journal of Coal Science & Technology 2019年第1期6卷 127-137页

作者： Mehdi Rahimi Ali Akbar Abdollahzadeh Bahram Rezai Department of Mining and Metallurgical Engineering Amirkabir University of Technology TehranIran Department of Mining Engineering University of KashanKashanIran

Dynamic simulation approach can be used for understanding the nonlinear behavior in mineral processing circuits. In this study, the gel point, the main parameters of batch flux density function and the main parameters of effective solid stress were determined at different conditions (pH, flocculant dosage and particle size). Therefore, the main parameters of phenome no logical model of sedimentation and thickening were determined as a functio n of particle size, pH and flocculant dosages using the result of experimental tests and Curve expert professional software. Then, the dynamic simulation was carried out for the industrial thickener of coal washing plant and the time-dependent variation of response variables was investigated by time-dependent variation of pH of input feed to thickener using the obtained equations. It was observed that it is possible to predict the thickener behavior as a function of time for time dependent variation of pH of input feed to the thickener of coal washing plant using obtained equations that it was not possible using phenomenological model of thickener alone.

关键词： Dynamic simulation Dewatering Ideal continuous thickener Thickener behavior time-dependent variation of pH

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time-dependent density-functional theory for open electronic systems

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Science China Chemistry 2014年第1期57卷 26-35页

作者： ZHENG Xiao WANG RuLin Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Department of Physics University of Science and Technology of China

time-dependent density-functional theory(TDDFT)has been successfully applied to predict excited-state properties of isolated and periodic systems.However,it cannot address a system coupled to an environment or whose number of electrons is not conserved.To tackle these problems,TDDFT needs to be extended to accommodate open systems.This paper provides a comprehensive account of the recent developments of TDDFT for open systems(TDDFT-OS),including both theoretical and practical aspects.The practicality and accuracy of a latest TDDFT-OS method is demonstrated with two numerical examples:the time-dependent electron transport through a series of quasi-one-dimensional atomic chains,and the real-time electronic dynamics on a two-dimensional graphene surface.The advancement of TDDFT-OS may lead to promising applications in various fields of chemistry,including energy conversion and heterogeneous catalysis.

关键词： time-dependent density functional theory,real-time electronic dynamics,hierarchical equations of motion

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An extended time-dependent numerical model of the mild-slope equation with weakly nonlinear amplitude dispersion

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Acta Oceanologica Sinica 2010年第2期29卷 5-13页

作者： ZHAO Hongjun SONG Zhiyao XU Fumin LI Ruijie Key Laboratory of Coastal Disasters and Defence Ministry of Education Hohai University Nanjing 210098 China Ocean College Hohai University Nanjing 210098 China Key Laboratory of Virtual Geographic Environment Ministry of Education Nanjing Normal University Nanjing 210097 China

In the present paper, by introducing the effective wave elevation, we transform the extended elliptic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. （2003）, the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. （2007）＇s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly varying topography and wave breaking, the present model is applied to study：（1） wave refraction and diffraction over a submerged elliptic shoal on a slope （Berkhoff et al., 1982）; （2） Bragg reflection of monochromatic waves from the sinusoidal ripples （Davies and Heathershaw, 1985）; （3） wave transformation near a shore attached breakwater （Watanabe and Maruyama, 1986）. Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models （REF/DIF model and FUNWAVE model） show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.

关键词： time-dependent mild-slope equation varying topography bottom friction nonlinear amplitude dispersion steep or rapidly wave breaking

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Experimental study on time-dependent stress and strain of in-plane shear(ModeⅡ) fracture process of rock

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Journal of Central South University 2008年第S1期15卷 496-499页

作者：王志饶秋华谢海峰 School of Civil and Architectural Engineering Central South University

Shear-box test with strain measurement was used to study time-dependent stress and strain of in-plane shear(Mode Ⅱ) fracture process of rock and to reveal the mechanism of Mode Ⅱ fracture.Numerical results show that the maximum shear stress τmax at the crack tip is much larger than the maximum tensile stress σ1 and the ratio of τmax/σ1 is about 5,which favors Mode Ⅱ fracture of rock.Test results indicate that the strain-time curve comprises three stages:the linear deformation stage,the micro-cracking stage and the macroscopic crack propagation.The strain in the direction of the original notch plane is negative,due to restraining effect of compressive loading applied to the original notch plane.Both σ1 and τmax are increased as the load increases,but the slope of τmax is larger than that of σ1 and the value of τmax is always larger than that of σ1.Therefore,τmax reaches its limited value at peak load before σ1 and results in Mode Ⅱ fracture of rock.Shear-box(i.***.compression-shear) test becomes a potential standard method for achieving the true Mode Ⅱ fracture and determining Mode Ⅱ fracture toughness of rock.

关键词： time-dependent stress and strain Mode Ⅱ fracture strain measurement fracture mechanism finite element method rock

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time-dependent behaviour of the Callovo-Oxfordian claystone-concrete interface

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 89-101页

作者： Eleni Stavropoulou Matthieu Briffaut Frédéric Dufour Guillaume Camps Univ.Grenoble Alpes CNRSGrenoble INP3SRF-38000GrenobleFrance Agence Nationale pour la gestion des Déchets Radioactifs(Andra) Chatenay-MalabryFrance

In the context of the Cigeo project,the French National Radioactive Waste Management Agency(Andra)is studying the behaviour of a deep geological facility for radioactive waste deposit in the CallovoOxfordian(COx)claystone.The assessment of durability of this project requires the prediction of irreversible strain over a large time scale.The mechanical interaction of the host rock and the concrete support of tunnels must be investigated to ensure the long-term sustainability of the structure.The instantaneous and time-dependent behaviour of the claystone-concrete interface is experimentally investigated with direct shear tests and long-duration shear tests of a few months.The mechanical and structural state of the claystone which is affected after interaction with concrete reflects to the response of the claystone-concrete interface,and thus different types of COx claystone-concrete interfaces are tested.The delayed deformation of the interface is found to be linked to the level of the normal loading and the loading history while a different response of the interface was observed from the short-and long-duration tests,indicating a possible progressive modification of interface under long-duration loadings.

关键词： Callovo-Oxfordian(COx)claystone Interfaces time-dependent behaviour

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time-dependent treatment of intramolecular energy transfer for HeICl complex

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Chinese Journal of Chemistry 1997年第3期15卷 218-224页

作者： Zhao, X Bu, YX Wu, AL Guan, DR SHANDONG NORMAL UNIV DEPT PHYSJINAN 250014SHANDONGPEOPLES R CHINA

The time-dependent golden wave packet method has been used for calculating the decay widths of vibrational predissociation for HeICl complex in the B state with total angular momentum J=0. This is a good example of intramolecular energy transfer, We examine the dependence of the final rotational distribution (partial decay width) of ICI fragment an the stretching excitation. It is found that computed final rotational distributions are weakly dependent on the vibrational level being excited. Unlike the smoothly varying rotational distribution for lower initial vibrational levels, for higher initial vibrational levels the rotational distribution indicates the very pronounced oscillatory structure. The analysis of the rotational distribution as a function of propagation time reveals the predominant role of the final states interaction in determining the final rotational distribution.

关键词： vibrational predissociation time-dependent wave-packet propagation

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Even and Odd Coherent States for time-dependent Harmonic Oscillator

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Communications in Theoretical Physics 2002年第7期38卷 25-30页

作者： WEI Lian-Fu YANG Qing-Yi WANG Shun-Jin Department of Physics Shanghai Jiao Tong University Shanghai 200030 China Department of Physics Guangxi University Nanning 530003 China Institute of Physics Southwest Jiao Tong University Chengdu 610031 China Department of Modern Physics Lanzhou University Lanzhou 730000 China

The dynamical invariant for a general time-dependent harmonic oscillator is constructed by making use of two linearly independent solutions to the classical equation of motion. In terms of this dynamical invariant we define the time-dependent creation and annihilation operators and relevantly introduce even and odd coherent states for time dependent harmonic oscillator. The mathematical and quantum statistical properties of these states are discussed in detail. The harmonic oscillator with periodically varying frequency is treated as a demonstration of our general approach.

关键词： even and odd coherent states, time-dependent harmonic oscillator, dynamical invariant

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