A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.F...A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.First,finite element analysis with a smeared cracking approach is implemented.The time-dependent bond-slip relationship between steel and concrete,and the stress-strain relationship of corroded steel bars are considered.Secondly,a stochastic finite element-based computational framework for reliability assessment of deteriorating RC bridges is proposed.The spatial and temporal variability of several parameters affecting the reliability of RC bridges is considered.Based on the data reported by several researchers and from field investigations,the Monte Carlo simulation is used to account for the uncertainties in various parameters,including local and general corrosion in rebars,concrete cover depth,surface chloride concentration,chloride diffusion coefficient,and corrosion rate.Finally,the proposed probabilistic durability assessment approach and framework are applied to evaluate the time-dependent reliability of a girder of a RC bridge located on the Tianjin Binhai New Area in China.展开更多
A numerical model for steady state analysis and analytical expressions for the AM and FM modulation responses of DFB lasers are presented.The small signal modulation responses of 3 phase shift(PS) DFB is investigate...A numerical model for steady state analysis and analytical expressions for the AM and FM modulation responses of DFB lasers are presented.The small signal modulation responses of 3 phase shift(PS) DFB is investigated for the first time.A new method(Vector Newton method) to obtain multiple longitudinal mode of DFB lasers is used.It is demonstrated that this method is suitable for obtaining multiple solution of high nonlinear equations.Longitudinal photon density distribution and multiple longitudinal mode of 3PS DFB and simple DFB lasers are analyzed.The results show that modulation response characteristics of 3PS DFB laser is as good as that of DFB,and PS can weaken the longitudinal spatial hole burning (LHSB) effect and is in favor of single longitudinal mode operating of lasers.展开更多
This paper presents a new depth migration method, adaptive spatial-division split-step Fourier （ASDSSF） migration. In this method we introduce the idea of a stratified phase shift migration into the split-step Fouri...This paper presents a new depth migration method, adaptive spatial-division split-step Fourier （ASDSSF） migration. In this method we introduce the idea of a stratified phase shift migration into the split-step Fourier （SSF） migration to make an accurate and efficient wave field image when sharp discontinuities appear in the velocity field. In principle, the ASDSSF migration is a multi-reference slowness （reciprocal of velocity） （MRS） migration. Compared to previous MRS migration methods, this method uses fewer reference slowness values without accuracy loss. The reference slowness is determined in this paper according to an error-control parameter of the perturbation term in the SSF operator and the variation of the complet velocity field. The velocity corresponded to reference slowness can define a spatial division. Each division can also be divided into several discontinuous spatial subdivisions to effectively reduce the number of reference slowness values needed. The choice of reference slowness, including the number of reference slowness values needed and how to construct the spatial divisions, is adaptive and reasonable at each extrapolation step （depth step）. A simple and economical smoothing filter in the wave number-frequency domain is designed to avoid artifacts in the wave field extrapolation due to the presence of sharp discontinuities in the velocity field. For comparable conditions the present approach to migration is expected to be computationally more efficient and accurate than other MRS migration methods. The performance of the method is demonstrated on a simple 2D prestack model and the prestack SEG/EAEG salt dataset.展开更多
This paper summarizes a few spatial statistical analysis methods for to measuring spatial autocorrelation and spatial association, discusses the criteria for the identification of spatial association by the use of glo...This paper summarizes a few spatial statistical analysis methods for to measuring spatial autocorrelation and spatial association, discusses the criteria for the identification of spatial association by the use of global Moran Coefficient, Local Moran and Local Geary. Furthermore, a user-friendly statistical module, combining spatial statistical analysis methods with GIS visual techniques, is developed in Arcview using Avenue. An example is also given to show the usefulness of this module in identifying and quantifying the underlying spatial association patterns between economic units.展开更多
Painleve property of the （2＋1）-dimensional multi-component Broer-Kaup （BK） system is considered by using the standard Weiss Kruskal approaches. Applying the Clarkson and Kruskal （CK） direct method to the （2＋1...Painleve property of the （2＋1）-dimensional multi-component Broer-Kaup （BK） system is considered by using the standard Weiss Kruskal approaches. Applying the Clarkson and Kruskal （CK） direct method to the （2＋1）- dimensional multi-component BK system, some types of similarity reductions are obtained. By solving the reductions, one can get the solutions of the （2＋1）-dimensional multi-component BK system.展开更多
The bound-state solution of the position dependent mass Klein-Gordon equation including inversely linear potential is obtained within the framework of the asymptotic iteration method. The relation between the scalar a...The bound-state solution of the position dependent mass Klein-Gordon equation including inversely linear potential is obtained within the framework of the asymptotic iteration method. The relation between the scalar and vector potentials is considered to S（x） = V（x）（β - 1）. In particular, it is shown that the corresponding method exactly reproduces the spectrum of linearly inversely potentials with spatially dependent mass.展开更多
This article uses the phase space path integral method to find the propagator for a particle with a force quadratic in velocity. Two specific canonical transformations has been used for this purpose.
基金The National Natural Science Foundation of China (No.50708065)the National High Technology Research and Development Program of China (863 Program) (No. 2007AA11Z113)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20070056125)
文摘A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.First,finite element analysis with a smeared cracking approach is implemented.The time-dependent bond-slip relationship between steel and concrete,and the stress-strain relationship of corroded steel bars are considered.Secondly,a stochastic finite element-based computational framework for reliability assessment of deteriorating RC bridges is proposed.The spatial and temporal variability of several parameters affecting the reliability of RC bridges is considered.Based on the data reported by several researchers and from field investigations,the Monte Carlo simulation is used to account for the uncertainties in various parameters,including local and general corrosion in rebars,concrete cover depth,surface chloride concentration,chloride diffusion coefficient,and corrosion rate.Finally,the proposed probabilistic durability assessment approach and framework are applied to evaluate the time-dependent reliability of a girder of a RC bridge located on the Tianjin Binhai New Area in China.
文摘A numerical model for steady state analysis and analytical expressions for the AM and FM modulation responses of DFB lasers are presented.The small signal modulation responses of 3 phase shift(PS) DFB is investigated for the first time.A new method(Vector Newton method) to obtain multiple longitudinal mode of DFB lasers is used.It is demonstrated that this method is suitable for obtaining multiple solution of high nonlinear equations.Longitudinal photon density distribution and multiple longitudinal mode of 3PS DFB and simple DFB lasers are analyzed.The results show that modulation response characteristics of 3PS DFB laser is as good as that of DFB,and PS can weaken the longitudinal spatial hole burning (LHSB) effect and is in favor of single longitudinal mode operating of lasers.
文摘This paper presents a new depth migration method, adaptive spatial-division split-step Fourier （ASDSSF） migration. In this method we introduce the idea of a stratified phase shift migration into the split-step Fourier （SSF） migration to make an accurate and efficient wave field image when sharp discontinuities appear in the velocity field. In principle, the ASDSSF migration is a multi-reference slowness （reciprocal of velocity） （MRS） migration. Compared to previous MRS migration methods, this method uses fewer reference slowness values without accuracy loss. The reference slowness is determined in this paper according to an error-control parameter of the perturbation term in the SSF operator and the variation of the complet velocity field. The velocity corresponded to reference slowness can define a spatial division. Each division can also be divided into several discontinuous spatial subdivisions to effectively reduce the number of reference slowness values needed. The choice of reference slowness, including the number of reference slowness values needed and how to construct the spatial divisions, is adaptive and reasonable at each extrapolation step （depth step）. A simple and economical smoothing filter in the wave number-frequency domain is designed to avoid artifacts in the wave field extrapolation due to the presence of sharp discontinuities in the velocity field. For comparable conditions the present approach to migration is expected to be computationally more efficient and accurate than other MRS migration methods. The performance of the method is demonstrated on a simple 2D prestack model and the prestack SEG/EAEG salt dataset.
文摘This paper summarizes a few spatial statistical analysis methods for to measuring spatial autocorrelation and spatial association, discusses the criteria for the identification of spatial association by the use of global Moran Coefficient, Local Moran and Local Geary. Furthermore, a user-friendly statistical module, combining spatial statistical analysis methods with GIS visual techniques, is developed in Arcview using Avenue. An example is also given to show the usefulness of this module in identifying and quantifying the underlying spatial association patterns between economic units.
基金National Natural Science Foundation of China under Grant No.10735030Shanghai Leading Academic Discipline Project under Grant No.B412+1 种基金Natural Science Foundation of Zhejiang Province of China under Grant No.Y604056the Doctoral Foundation of Ningbo City under Grant No.2005A61030
文摘Painleve property of the （2＋1）-dimensional multi-component Broer-Kaup （BK） system is considered by using the standard Weiss Kruskal approaches. Applying the Clarkson and Kruskal （CK） direct method to the （2＋1）- dimensional multi-component BK system, some types of similarity reductions are obtained. By solving the reductions, one can get the solutions of the （2＋1）-dimensional multi-component BK system.
基金supported by the Research Fund of Gaziantep University and the Scientific and Technological Research Council of Turkey (TUBITAK).
文摘The bound-state solution of the position dependent mass Klein-Gordon equation including inversely linear potential is obtained within the framework of the asymptotic iteration method. The relation between the scalar and vector potentials is considered to S（x） = V（x）（β - 1）. In particular, it is shown that the corresponding method exactly reproduces the spectrum of linearly inversely potentials with spatially dependent mass.
文摘This article uses the phase space path integral method to find the propagator for a particle with a force quadratic in velocity. Two specific canonical transformations has been used for this purpose.
