A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include:1) a prototype of the key...A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include:1) a prototype of the keyhole and the inverse Bremsstrahlung absorption coefficient in the keyhole plasma are obtained from the experiments;2) instead of using a parallel incident beam,a focused laser beam with real Gaussian intensity distribution is implemented;3) both Fresnel absorption and inverse Bremsstrahlung absorption during multiple reflections are considered.The calculation results show that the distribution of absorbed laser intensity by the keyhole wall is not uniform.The maximum laser energy is absorbed by the bottom of the keyhole,although no rays irradiate directly onto the bottom.According to analysis of beam focusing characteristics,the location of the focal plane plays a more important role in the laser energy absorption by the front wall than by the rear wall.展开更多
Through the analysis on the meanings and features as well as the ad- vantages of the third-party logistics for agricultural products, the quantization index system for the selection of third-party logistics providers ...Through the analysis on the meanings and features as well as the ad- vantages of the third-party logistics for agricultural products, the quantization index system for the selection of third-party logistics providers for agricultural products was constructed based on the system comprehensive evaluation theory. Analytic hierar- chy process (AHP) was used to determine the weight of the index system of each level, and AHP and fuzzy comprehensive evaluation method were used to determine the selection steps for the third-party logistics providers for agricultural products. The method was proved to be scientific and reasonable through calculation examples.展开更多
Currently, most of MT (magnetotelluric) data are still collected on sparse survey lines and interpreted using 2D inversion methods because of the field work cost, the work area environment, and so on. However, there...Currently, most of MT (magnetotelluric) data are still collected on sparse survey lines and interpreted using 2D inversion methods because of the field work cost, the work area environment, and so on. However, there are some 2D interpretation limitations of the MT data from 3D geoelectrical structures which always leads to wrong geological interpretations. In this paper, we used the 3D inversion method to interpret the MT sparse lines data. In model testing, the sparse lines data are the MT full information data generated from a test model and processed using the 3D conjugate gradients inversion code. The inversion results show that this inversion method is reasonable and effective. Meanwhile, we prove that for inversion results with different element parameters, the results by joint inversion of both the impedance tensor data and the tipper data are more accurate and closer to the test model.展开更多
The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the ...The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the turbulent coherent structure in the channel flow. Th is method contains three dimensional coupling difference scheme with high accur acy and high resolution, and the high order time splitting methods. Compared with the general spectral method, the method can be used to research turbule nt coherent structure under more general boundary conditions and in flow domains . In this paper, the generation and evolution of the turbulent coherent structur es ind uced by wall pulse in the channel flow are simulated, and the basic characterist ics and rules of the turbulent coherent structure are shown. Computational r esults indicate that a wall negative pulse is more convenient than the resonant three wave model.展开更多
Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condit...Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condition requires special treatment for the absorbing zone, and in three-dimensional (3D) modeling, it has to split each variable into three corresponding variables, which increases the computing time and memory storage. In contrast, the hybrid absorbing boundary condition (HABC) has the advantages such as ease of implementation, less computation time, and near-perfect absorption; it is thus able to enhance the computational efficiency of 3D elastic wave modeling. In this study, a HABC is developed from two-dimensional (2D) modeling into 3D modeling based on the I st Higdon one way wave equations, and a HABC is proposed that is suitable for a 3D elastic wave numerical simulation. Numerical simulation results for a homogenous model and a complex model indicate that the proposed HABC method is more effective and has better absorption than the traditional PML method.展开更多
The compound KdV-Burgers equation and combined KdV-mKdV equation are real physical models concerning many branches in physics.In this paper,applying the improved trigonometric function method to these equations,rich e...The compound KdV-Burgers equation and combined KdV-mKdV equation are real physical models concerning many branches in physics.In this paper,applying the improved trigonometric function method to these equations,rich explicit and exact travelling wave solutions,which contain solitary-wave solutions,periodic solutions,and combined formal solitary-wave solutions,are obtained.展开更多
In the design of chemical processes,such as catalytic cracking of bitumen and heavy oil,the knowledge of phase behavior at the critical endpoint is essential.Based on the PR equation of state,the algorithm developed b...In the design of chemical processes,such as catalytic cracking of bitumen and heavy oil,the knowledge of phase behavior at the critical endpoint is essential.Based on the PR equation of state,the algorithm developed by Heidemann and Khalil for calculating critical properties was used to compute critical points.An algorithm for determining the equilibrium phase of the critical point using the tangent plane criterion was developed,and was used to calculate the critical endpoints of different mixtures,including non-polar,polar and associating systems.The critical endpoint,representing the type of the phase behavior,was employed to fit the interaction parameter of mixtures in critical state at high pressure.Lines of critical endpoints for ternary mixtures were also determined with the algorithm.展开更多
In this note,by combining the nice numerical performance of PR and HS methods with the global convergence property of FR method,a class of new restarting three terms conjugate gradient methods is presented.Global conv...In this note,by combining the nice numerical performance of PR and HS methods with the global convergence property of FR method,a class of new restarting three terms conjugate gradient methods is presented.Global convergence properties of the new method with two kinds of common line searches are proved.展开更多
In this paper, we extend the mapping deformation method proposed by Lou. It is used to find new exacttravelling wave solutions of nonlinear partial differential equation or coupled nonlinear partial differential equat...In this paper, we extend the mapping deformation method proposed by Lou. It is used to find new exacttravelling wave solutions of nonlinear partial differential equation or coupled nonlinear partial differential equations(PDEs). Based on the idea of the homogeneous balance method, we construct the general mapping relation betweenthe solutions of the PDEs and those of the cubic nonlinear Klein-Gordon (NKG) equation. By using this relation andthe abundant solutions of the cubic NKG equation, many explicit and exact travelling wave solutions of three systemsof coupled PDEs, which contain solitary wave solutions, trigonometric function solutions, Jacobian elliptic functionsolutions, and rational solutions, are obtained.展开更多
This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field couple...This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field coupled media. This method was used to derive a series of exact three dimensional solutions which should be of great theoretical significance because most of them usually cannot be derived by other methods such as the transform method and the trial-and-error method. Further, many solutions are obtained in terms of elementary functions that enable us to treat more complicated problems easily. It is pointed out here that the method is usually only applicable to media characterizing transverse isotropy, from which, however, the results for the isotropic case can be readily obtained.展开更多
Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results r...Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results revealed the spatial structure,composition structure,hierarchical structure,group structure,and control structure of Chinese city network,as well as its dynamic factors.The major findings are:1) the spatial pattern presents a diamond structure,in which Wuhan is the central city;2) although the invention patent knowledge network is the main part of the broader inter-city innovative cooperation network,it is weaker than the utility model patent;3) as the senior level cities,Beijing,Shanghai and the cities in the Zhujiang(Pearl) River Delta Region show a strong capability of both spreading and controlling technological knowledge;4) whilst a national technology alliance has preliminarily formed,regional alliances have not been adequately established;5) even though the cooperation level amongst weak connection cities is not high,such cities still play an important role in the network as a result of their location within ′structural holes′ in the network;and 6) the major driving forces facilitating inter-city technological cooperation are geographical proximity,hierarchical proximity and technological proximity.展开更多
Proposed new cubic equation of state is more accurate than others in result and simple in form. The equation has been tried with 23 pure compounds including both polar and non-polar compounds. Experimental values of t...Proposed new cubic equation of state is more accurate than others in result and simple in form. The equation has been tried with 23 pure compounds including both polar and non-polar compounds. Experimental values of these compounds collected from various journals were compared with proposed model and found to be more accurate than other widely used cubic equations of state like SRK and Peng Robinson. The form of current EOS best suits to PVT data and total error is almost halved for a set of experimental data in the most cases.展开更多
In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic (where mastic is a kind of fine mixture composed of asphalt binder mixed with fi...In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic (where mastic is a kind of fine mixture composed of asphalt binder mixed with fines and fine aggregates) and air voids, based on three-dimensional (3D) heterogeneous specimen, X-ray computerized tomography (X-ray CT) was used to scan the asphalt specimens to obtain the real internal microstrnctures of asphalt mixture. CT images were reconstructed to build up 3D digital specimen, and the viscoelastic properties of mastic were described with Burgers model The uniaxial creep numerical simulations of three different levels of aggregate gradation were conducted. The simulation results agree well with the experimental results. The numerical simulation of asphalt mixture incorporated with real 3D microstructure based on finite element method is a promising application to conduct research of asphalt concrete. Additionally, this method can increase the mechanistic understanding of global viscoelastic properties of asphalt mixtures by linking the real 3D microstructure.展开更多
基金Projects (51175162, 50805045) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,China
文摘A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include:1) a prototype of the keyhole and the inverse Bremsstrahlung absorption coefficient in the keyhole plasma are obtained from the experiments;2) instead of using a parallel incident beam,a focused laser beam with real Gaussian intensity distribution is implemented;3) both Fresnel absorption and inverse Bremsstrahlung absorption during multiple reflections are considered.The calculation results show that the distribution of absorbed laser intensity by the keyhole wall is not uniform.The maximum laser energy is absorbed by the bottom of the keyhole,although no rays irradiate directly onto the bottom.According to analysis of beam focusing characteristics,the location of the focal plane plays a more important role in the laser energy absorption by the front wall than by the rear wall.
基金Supported by the Natural Science Foundation of Guangxi Province(2011GXNSFB018061)the High-grade Scientific Research(Cultivation)Program of Qinzhou University(2014PY-SJ03,2014PY-SJ01)~~
文摘Through the analysis on the meanings and features as well as the ad- vantages of the third-party logistics for agricultural products, the quantization index system for the selection of third-party logistics providers for agricultural products was constructed based on the system comprehensive evaluation theory. Analytic hierar- chy process (AHP) was used to determine the weight of the index system of each level, and AHP and fuzzy comprehensive evaluation method were used to determine the selection steps for the third-party logistics providers for agricultural products. The method was proved to be scientific and reasonable through calculation examples.
基金supported by the National Hi-Tech Research and Development Program of China (863 Program) (No. 2007AA09Z310)National Natural Science Foundation of China (No. 40677037, 40774029, 41004028)+1 种基金Fundamental Research Funds for the Central Universities (No. 2010ZY53) Program for New Century Excellent Talents in University (NCET)
文摘Currently, most of MT (magnetotelluric) data are still collected on sparse survey lines and interpreted using 2D inversion methods because of the field work cost, the work area environment, and so on. However, there are some 2D interpretation limitations of the MT data from 3D geoelectrical structures which always leads to wrong geological interpretations. In this paper, we used the 3D inversion method to interpret the MT sparse lines data. In model testing, the sparse lines data are the MT full information data generated from a test model and processed using the 3D conjugate gradients inversion code. The inversion results show that this inversion method is reasonable and effective. Meanwhile, we prove that for inversion results with different element parameters, the results by joint inversion of both the impedance tensor data and the tipper data are more accurate and closer to the test model.
文摘The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the turbulent coherent structure in the channel flow. Th is method contains three dimensional coupling difference scheme with high accur acy and high resolution, and the high order time splitting methods. Compared with the general spectral method, the method can be used to research turbule nt coherent structure under more general boundary conditions and in flow domains . In this paper, the generation and evolution of the turbulent coherent structur es ind uced by wall pulse in the channel flow are simulated, and the basic characterist ics and rules of the turbulent coherent structure are shown. Computational r esults indicate that a wall negative pulse is more convenient than the resonant three wave model.
基金supported by the National Natural Science Foundation of China(No.41474110)
文摘Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condition requires special treatment for the absorbing zone, and in three-dimensional (3D) modeling, it has to split each variable into three corresponding variables, which increases the computing time and memory storage. In contrast, the hybrid absorbing boundary condition (HABC) has the advantages such as ease of implementation, less computation time, and near-perfect absorption; it is thus able to enhance the computational efficiency of 3D elastic wave modeling. In this study, a HABC is developed from two-dimensional (2D) modeling into 3D modeling based on the I st Higdon one way wave equations, and a HABC is proposed that is suitable for a 3D elastic wave numerical simulation. Numerical simulation results for a homogenous model and a complex model indicate that the proposed HABC method is more effective and has better absorption than the traditional PML method.
文摘The compound KdV-Burgers equation and combined KdV-mKdV equation are real physical models concerning many branches in physics.In this paper,applying the improved trigonometric function method to these equations,rich explicit and exact travelling wave solutions,which contain solitary-wave solutions,periodic solutions,and combined formal solitary-wave solutions,are obtained.
文摘In the design of chemical processes,such as catalytic cracking of bitumen and heavy oil,the knowledge of phase behavior at the critical endpoint is essential.Based on the PR equation of state,the algorithm developed by Heidemann and Khalil for calculating critical properties was used to compute critical points.An algorithm for determining the equilibrium phase of the critical point using the tangent plane criterion was developed,and was used to calculate the critical endpoints of different mixtures,including non-polar,polar and associating systems.The critical endpoint,representing the type of the phase behavior,was employed to fit the interaction parameter of mixtures in critical state at high pressure.Lines of critical endpoints for ternary mixtures were also determined with the algorithm.
基金Supported by the National Natural Science Foundation of China(10571106) Supported by the Fundamental Research Funds for the Central Universities(10CX04044A)
文摘In this note,by combining the nice numerical performance of PR and HS methods with the global convergence property of FR method,a class of new restarting three terms conjugate gradient methods is presented.Global convergence properties of the new method with two kinds of common line searches are proved.
文摘In this paper, we extend the mapping deformation method proposed by Lou. It is used to find new exacttravelling wave solutions of nonlinear partial differential equation or coupled nonlinear partial differential equations(PDEs). Based on the idea of the homogeneous balance method, we construct the general mapping relation betweenthe solutions of the PDEs and those of the cubic nonlinear Klein-Gordon (NKG) equation. By using this relation andthe abundant solutions of the cubic NKG equation, many explicit and exact travelling wave solutions of three systemsof coupled PDEs, which contain solitary wave solutions, trigonometric function solutions, Jacobian elliptic functionsolutions, and rational solutions, are obtained.
基金Project (No. 10372088) supported by the National Natural Science Foundation of China
文摘This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field coupled media. This method was used to derive a series of exact three dimensional solutions which should be of great theoretical significance because most of them usually cannot be derived by other methods such as the transform method and the trial-and-error method. Further, many solutions are obtained in terms of elementary functions that enable us to treat more complicated problems easily. It is pointed out here that the method is usually only applicable to media characterizing transverse isotropy, from which, however, the results for the isotropic case can be readily obtained.
基金Under the auspices of Major Project of National Social Science Foundation of China(No.13&ZD027)National Natural Science Foundation of China(No.41201128,71433008)
文摘Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results revealed the spatial structure,composition structure,hierarchical structure,group structure,and control structure of Chinese city network,as well as its dynamic factors.The major findings are:1) the spatial pattern presents a diamond structure,in which Wuhan is the central city;2) although the invention patent knowledge network is the main part of the broader inter-city innovative cooperation network,it is weaker than the utility model patent;3) as the senior level cities,Beijing,Shanghai and the cities in the Zhujiang(Pearl) River Delta Region show a strong capability of both spreading and controlling technological knowledge;4) whilst a national technology alliance has preliminarily formed,regional alliances have not been adequately established;5) even though the cooperation level amongst weak connection cities is not high,such cities still play an important role in the network as a result of their location within ′structural holes′ in the network;and 6) the major driving forces facilitating inter-city technological cooperation are geographical proximity,hierarchical proximity and technological proximity.
文摘Proposed new cubic equation of state is more accurate than others in result and simple in form. The equation has been tried with 23 pure compounds including both polar and non-polar compounds. Experimental values of these compounds collected from various journals were compared with proposed model and found to be more accurate than other widely used cubic equations of state like SRK and Peng Robinson. The form of current EOS best suits to PVT data and total error is almost halved for a set of experimental data in the most cases.
基金Project(51038004) supported by the National Natural Science Foundation of China
文摘In order to verify the validity of finite element numerical simulation method for asphalt mixture, which consists of aggregates, mastic (where mastic is a kind of fine mixture composed of asphalt binder mixed with fines and fine aggregates) and air voids, based on three-dimensional (3D) heterogeneous specimen, X-ray computerized tomography (X-ray CT) was used to scan the asphalt specimens to obtain the real internal microstrnctures of asphalt mixture. CT images were reconstructed to build up 3D digital specimen, and the viscoelastic properties of mastic were described with Burgers model The uniaxial creep numerical simulations of three different levels of aggregate gradation were conducted. The simulation results agree well with the experimental results. The numerical simulation of asphalt mixture incorporated with real 3D microstructure based on finite element method is a promising application to conduct research of asphalt concrete. Additionally, this method can increase the mechanistic understanding of global viscoelastic properties of asphalt mixtures by linking the real 3D microstructure.