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Numerical verification of similar Cam-clay model based on generalized potential theory 被引量:2
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作者 钟志辉 杨光华 +2 位作者 傅旭东 温勇 张玉成 《Journal of Central South University》 SCIE EI CAS 2014年第12期4707-4713,共7页
From the mathematical principles, the generalized potential theory can be employed to create constitutive model of geomaterial directly. The similar Cam-clay model, which is created based on the generalized potential ... From the mathematical principles, the generalized potential theory can be employed to create constitutive model of geomaterial directly. The similar Cam-clay model, which is created based on the generalized potential theory, has less assumptions,clearer mathematical basis, and better computational accuracy. Theoretically, it is more scientific than the traditional Cam-clay models. The particle flow code PFC3 D was used to make numerical tests to verify the rationality and practicality of the similar Cam-clay model. The verification process was as follows: 1) creating the soil sample for numerical test in PFC3 D, and then simulating the conventional triaxial compression test, isotropic compression test, and isotropic unloading test by PFC3D; 2)determining the parameters of the similar Cam-clay model from the results of above tests; 3) predicting the sample's behavior in triaxial tests under different stress paths by the similar Cam-clay model, and comparing the predicting results with predictions by the Cam-clay model and the modified Cam-clay model. The analysis results show that the similar Cam-clay model has relatively high prediction accuracy, as well as good practical value. 展开更多
关键词 generalized potential theory similar Cam-clay model modified Cam-clay model numerical test PFC3D
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GENERALIZED THEORY OF NONLINEAR AND UNSTEADY MECHANICS AND APPLICATIONS TO PARTICLE PHYSICS
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作者 杨文熊 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1995年第1期27-35,共9页
In this paper we consider that the momentum of a free particle motion withhigh-level speed presenting nonlinear effects may be expanded by using Laurent seriesand then obtain the complete expression of nonlinear and u... In this paper we consider that the momentum of a free particle motion withhigh-level speed presenting nonlinear effects may be expanded by using Laurent seriesand then obtain the complete expression of nonlinear and unsteady momentum. These nonlinear and unsieady phenoniena of high-level speed may further expand to the theory of kinematics and it may be determined by Fredholm's integral equation of the first kind. In addition, according to the nonlinear and unsteady momentum obtained the relations of the nonlinear mechanics equations .work and energy, mass and energymay be derived.Finaly .this paper also calculates those experimental results which done in particle physics for mu-mesons u±and fast neutrons n, these results are in agreement with data perfectly. 展开更多
关键词 theory of generalized nonlinear mechanics characteristic speed.Laurent senes particle physics.μ±meson fast neutron
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SOLUTION TO A PARAMETRIC EQUATION WITH GENERALIZED BOUNDARY CONDITION IN TRANSPORT THEORY
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作者 王胜华 姚爱翔 《Acta Mathematica Scientia》 SCIE CSCD 1992年第4期435-442,共8页
This paper deals with the solution of a parametric equation with generalized boundary condiiton in transport theory. It gives the distribution of parameter (so called delta-eigenvalue [1]) with which the equation has ... This paper deals with the solution of a parametric equation with generalized boundary condiiton in transport theory. It gives the distribution of parameter (so called delta-eigenvalue [1]) with which the equation has non-zero solution. A necessary and sufficient condition for the existence of; he control critical eigenvalue delta0 is established. 展开更多
关键词 SOLUTION TO A PARAMETRIC EQUATION WITH GENERALIZED BOUNDARY CONDITION IN TRANSPORT theory Za
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Solubility study of hydrogen in direct coal liquefaction solvent based on quantitative structure–property relationships model
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作者 Xiao-Bin Zhang A.Rajendran +1 位作者 Xing-Bao Wang Wen-Ying Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第12期250-258,共9页
Direct coal liquefaction(DCL)is an important and effective method of converting coal into high-valueadded chemicals and fuel oil.In DCL,heating the direct coal liquefaction solvent(DCLS)from low to high temperature an... Direct coal liquefaction(DCL)is an important and effective method of converting coal into high-valueadded chemicals and fuel oil.In DCL,heating the direct coal liquefaction solvent(DCLS)from low to high temperature and pre-hydrogenation of the DCLS are critical steps.Therefore,studying the dissolution of hydrogen in DCLS under liquefaction conditions gains importance.However,it is difficult to precisely determine hydrogen solubility only by experiments,especially under the actual DCL conditions.To address this issue,we developed a prediction model of hydrogen solubility in a single solvent based on the machine-learning quantitative structure–property relationship(ML-QSPR)methods.The results showed that the squared correlation coefficient R^(2)=0.92 and root mean square error RMSE=0.095,indicating the model’s good statistical performance.The external validation of the model also reveals excellent accuracy and predictive ability.Molecular polarization(a)is the main factor affecting the dissolution of hydrogen in DCLS.The hydrogen solubility in acyclic alkanes increases with increasing carbon number.Whereas in polycyclic aromatics,it decreases with increasing ring number,and in hydrogenated aromatics,it increases with hydrogenation degree.This work provides a new reference for the selection and proportioning of DCLS,i.e.,a solvent with higher hydrogen solubility can be added to provide active hydrogen for the reaction and thus reduce the hydrogen pressure.Besides,it brings important insight into the theoretical significance and practical value of the DCL. 展开更多
关键词 Hydrogen solubility Liquefied solvents Predictive model Density generalized function theory Quantitative structure-property RELATIONSHIP
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Dynamic coupled thermo-hydro-mechanical problem for heterogeneous deep-sea sediments under vibration of mining vehicle
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作者 Wei ZHU Xingkai MA +1 位作者 Xinyu SHI Wenbo MA 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第4期603-622,共20页
Due to the influence of deep-sea environment,deep-sea sediments are usually heterogeneous,and their moduli of elasticity and density change as depth changes.Combined with the characteristics of deep-sea sediments,the ... Due to the influence of deep-sea environment,deep-sea sediments are usually heterogeneous,and their moduli of elasticity and density change as depth changes.Combined with the characteristics of deep-sea sediments,the thermo-hydro-mechanical coupling dynamic response model of heterogeneous saturated porous sediments can be established to study the influence of elastic modulus,density,frequency,and load amplitude changes on the model.Based on the Green-Lindsay generalized thermoelasticity theory and Darcy’s law,the thermo-hydro-mechanical coupled dynamic response model and governing equations of heterogeneous deep-sea sediments with nonlinear elastic modulus and density are established.The analytical solutions of dimensionless vertical displacement,vertical stress,excess pore water pressure,and temperature are obtained by means of normal modal analysis,which are depicted graphically.The results show that the changes of elastic modulus and density have few effects on vertical displacement,vertical stress,and temperature,but have great effects on excess pore water pressure.When the mining machine vibrates,the heterogeneity of deep-sea sediments has great influence on vertical displacement,vertical stress,and excess pore water pressure,but has few effects on temperature.In addition,the vertical displacement,vertical stress,and excess pore water pressure of heterogeneous deep-sea sediments change more gently.The variation trends of physical quantities for heterogeneous and homogeneous deep-sea sediments with frequency and load amplitude are basically the same.The results can provide theoretical guidance for deep-sea mining engineering construction. 展开更多
关键词 heterogeneous deep-sea sediment coupled thermo-hydro-mechanical Green-Lindsay generalized thermoelastic theory normal modal anlalysis dynamic re-sponse
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Generalized Odd-Even Mode Theory and Mode Synthesis Antenna Design Approach
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作者 Wen-Jun Lu 《Electromagnetic Science》 2024年第1期20-37,共18页
In this article,studies on the multimode excitation problem of waveguides and antennas,the balance/unbalance mech-anism and the balanced feeding techniques in dipole antenna systems are first briefly historically revi... In this article,studies on the multimode excitation problem of waveguides and antennas,the balance/unbalance mech-anism and the balanced feeding techniques in dipole antenna systems are first briefly historically reviewed.In this context,general-ized odd-even mode theory is advanced to quantitatively and approximately describe the mutual coupling effect between a feed line and an antenna.As is mathematically deduced and demonstrated,the modal parity mismatch between the feed line and the antenna should ultimately dominate the unbalance phenomenon in antenna systems.Thus,an elegant,closed-form formula is derived to ap-proximately calculate the“unbalance degree”of a straight dipole off-center fed by a symmetric twin-wire line.Design approaches for the simplest,linear,1-D multimode resonant antennas are introduced.Moreover,the“falling tone excitation”law gauged based on prototype dipoles is revealed and used to develop a mode synthesis design approach for microstrip patch antennas(MPAs)and 2-D sectorial electric dipole antennas.Design examples with distinctive radiation performance are presented and discussed.Finally,possible development trends of multimode resonant antennas are prospected. 展开更多
关键词 Generalized odd-even mode theory Modal parity mismatch Mode synthesis antenna design approach Multimode resonant antenna
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Modeling and analysis of azimuthal AVO responses from a viscoelastic anisotropic reflector 被引量:3
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作者 郭智奇 刘喜武 +1 位作者 符伟 李向阳 《Applied Geophysics》 SCIE CSCD 2015年第3期441-452,470,共13页
We propose a method for mOdeling azimuthal AVO responses from a fractured i reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the con... We propose a method for mOdeling azimuthal AVO responses from a fractured i reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the contrast in impedance and anelasticity i across interfaces, the intemal anisotropic propagation, the dispersion and attenuation along i the wave path, and tuning and interference. The results suggest that for large angles of incidence, the velocity dispersion and attenuation increase the amplitudes of PP waves from the top and decrease those from the bottom. For azimuthal responses at specific angles of incidence, the reflected wavetrains of PP waves tend to have longer duration with increasing azimuth. In contrast, model-converted PSV and PSH reflections show stable azimuthal features and are less affected by the reflector thickness. The amplitudes of PSV reflections increase with increasing azimuth; moreover, the waves have no reflection energy at 0° and 90° azimuth and maximum amplitude at 45° azimuth. 展开更多
关键词 REFLECTOR viscoelastic and anisotropic dispersion and attenuation generalized anisotropic Zoelopritz theory azimuthal AVO
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ELASTO-PLASTIC CONSTITUTIVE MODEL OF SOIL-STRUCTURE INTERFACE IN CONSIDERATION OF STRAIN SOFTENING AND DILATION 被引量:11
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作者 Aizhao Zhou Tinghao Lu 《Acta Mechanica Solida Sinica》 SCIE EI 2009年第2期171-179,共9页
The behavior of soil-structure interface plays a major role in the definition of soil-structure interaction. In this paper a bi-potential surface elasto-plastic model for soil-structure interface is proposed in order ... The behavior of soil-structure interface plays a major role in the definition of soil-structure interaction. In this paper a bi-potential surface elasto-plastic model for soil-structure interface is proposed in order to describe the interface deformation behavior,including strain softening and normal dilatancy. The model is formulated in the framework of generalized potential theory,in which the soil-structure interface problem is regard as a two-dimensional mathematical problem in stress field,and plastic state equations are used to replace the traditional field surface. The relation curves of shear stress and tangential strain are fitted by a piecewise function composed by hyperbolic functions and hyperbolic secant functions,while the relation curves of normal strain and tangential strain are fitted by another piecewise function composed by quadratic functions and hyperbolic secant functions. The approach proposed has the advantage of deriving an elastoplastic constitutive matrix without postulating the plastic potential functions and yield surface. Moreover,the mathematical principle is clear,and the entire model parameters can be identified by experimental tests. Finally,the predictions of the model have been compared with experimental results obtained from simple shear tests under normal stresses,and results show the model is reasonable and practical. 展开更多
关键词 generalized potential theory strain softening shear dilatancy INTERFACE constitutive model
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Influence of thermal contact resistance on dynamic response of bilayered saturated porous strata 被引量:3
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作者 WEN Min-jie TIAN Yi +2 位作者 WU Wen-bing WANG Kui-hua XIONG Hou-ren 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期1823-1839,共17页
Porous materials can be found in a variety of geophysical and engineering applications.The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significa... Porous materials can be found in a variety of geophysical and engineering applications.The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significant temperature difference at the interface.An attempt is made to study the thermo-hydro-mechanical coupling dynamic response of bilayered saturated porous strata with thermal contact resistance and elastic wave impedance.The corresponding analytical solutions for the dynamic response of bilayered saturated porous strata under a harmonic thermal load are derived by the operator decomposition method,and their rationality is verified by comparing them with existing solutions.The influences of thermal contact resistance,thermal conductivity ratio,and porosity ratio on the dynamic response of bilayered saturated porous strata are systematically investigated.Outcomes disclose that with the increase of thermal contact resistance,the displacement,pore water pressure and stress decrease gradually,and the temperature jump at the interface between two saturated porous strata increases. 展开更多
关键词 dynamic response bilayered saturated porous strata thermal contact resistance generalized thermoelastic theory elastic wave impedance
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On seismic strengthening area before strong and great shocks and its mechanism 被引量:2
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作者 宋治平 梅世蓉 尹祥础 《Acta Seismologica Sinica(English Edition)》 EI CSCD 1999年第3期298-305,共8页
By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock o... By systematically studying seismic strengthening areas before 85 earthquakes with M>=6.0 in China, some results have been extracted. 1) Earthquake active strengthening area exists universally before strong shock or great earthquake; 2) The size of the strengthening area and its appearing time will increase when the earthquake magnitude increases; 3) The rate between the size of seismic strengthening area and the size of the source region decreases when earthquake magnitude increases; 4) The appearing time of the earthquake active strengthening region in the eastern part of China is longer than that in the western part of China. The above characteristics have been preliminarily explained qualitatively and half-quantitatively by applying the strong body earthquake generating model and the hard inclusion theory. Then applying the seismic strengthening area, we have obtained long-term predictions of 2 earthquakes, so the seismic strengthening area before strong earthquake or great earthquakes is a universal phenomenon, which has some mechanical base. 展开更多
关键词 seismic activity seismic strengthening area strong body earthquake generating modelhard inclusion theory predicting practice
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Research on coupled thermo-hydro-mechanical dynamic response characteristics of saturated porous deep-sea sediments under vibration of mining vehicle 被引量:1
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作者 Wei ZHU Xinyu SHI +2 位作者 Rong HUANG Liyue HUANG Wenbo MA 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第9期1349-1362,共14页
The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining.Combined with the deep-sea environment,the coupled thermo-hydro-m... The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining.Combined with the deep-sea environment,the coupled thermo-hydro-mechanical problem for saturated porous deep-sea sediments subject to the vibration of the mining vehicle is investigated.Based on the Green-Lindsay(G-L)generalized thermoelastic theory and Darcy’s law,the model of thermo-hydro-mechanical dynamic responses for saturated porous deep-sea sediments under the vibration of the mining vehicle is established.We obtain the analytical solutions of non-dimensional vertical displacement,excess pore water pressure,vertical stress,temperature,and change in the volume fraction field with the normal mode analysis method,and depict them graphically.The normal mode analysis method uses the canonical coordinate transformation to solve the equation,which can quickly decouple the equation by ignoring the modal coupling effect on the basis of the canonical mode.The results indicate that the vibration frequency has obvious influence on the vertical displacement,excess pore water pressure,vertical stress,and change in volume fraction field.The loading amplitude has a great effect on the physical quantities in the foundation,and the changes of the physical quantities increase with the increase in loading amplitude. 展开更多
关键词 deep-sea sediment thermo-hydro-mechanical dynamic generalized thermoelastic theory normal mode analysis dynamic response characteristic
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An elasto-plastic constitutive model incorporating strain softening and dilatancy for interface thin-layer element and its verification 被引量:1
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作者 彭凯 朱俊高 +2 位作者 冯树荣 王荣 刘汉龙 《Journal of Central South University》 SCIE EI CAS 2012年第7期1988-1998,共11页
The mechanical behaviors of the interface between coarse-grained soil and concrete were investigated by simple shear tests under condition of mixed soil slurry (bentonite mixed with cement grout).For comparison,the in... The mechanical behaviors of the interface between coarse-grained soil and concrete were investigated by simple shear tests under condition of mixed soil slurry (bentonite mixed with cement grout).For comparison,the interfaces both without slurry and with bentonite slurry were analyzed.The experimental results show that different slurries exert much influence on the strength and deformation of soil/structure interface.Under mixed soil slurry,strain softening and shear dilatation are observed,while shear dilatation appears under the small normal stress of the interface without slurry,and shear contraction is significant under the condition of the bentonite slurry.The thickness of the interface was determined by analyzing the disturbed height of the sample with both simple shear test and particle flow code (PFC).An elasto-plastic constitutive model incorporating strain softening and dilatancy for thin layer element of interface was formulated in the framework of generalized potential theory.The relation curves of shear stress and shear strain,as well as the relation curves of normal strain and shear strain,were fitted by a piecewise function composed by hyperbolic functions and resembling normal functions.The entire model parameters can be identified by tests.The new model is verified by comparing the measured data of indoor cut-off wall model tests with the predictions from finite element method (FEM).The FEM results indicate that the stress of wall calculated by using Goodman element is too large,and the maximum deviation between the test data and prediction is about 45%.While the prediction from the proposed model is close to the measured data,and the error is generally less than 10%. 展开更多
关键词 simple shear test mixed soil slurry DILATANCY particle flow code generalized potential theory constitutive model FEM
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The study of slip line field and upper bound method based on associated flow and non-associated flow rules 被引量:2
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作者 Zheng Yingren Deng Chujian Wang Jinglin 《Engineering Sciences》 EI 2010年第3期21-40,共20页
At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line... At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line. It is proved that geotechnical materials do not abide by the associated flow rule. It is impossible for the stress characteristic line to conform to the velocity line. Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle, so that the velocity line must be studied by non-associated flow rule. According to limit analysis theory, the theory of slip line field is put forward in this paper, and then the ultimate beating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow nile individually. These two results are identical since the ultimate bearing capacity is independent of flow role. On the contrary, the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associat- ed flow rule is incorrect. 展开更多
关键词 slip line field upper bound method associated flow rule non-associated flow rule generalized plastic theory
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Wave reflection in semiconductor nanostructures 被引量:1
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作者 Feixiang Tang Yaqin Song 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2018年第3期160-163,共4页
Based on nonlocal thermoelastic theory, this article studies the reflection of waves in nanometersemi-conductor media. Firstly, the governing equations are established based on couplednonlocal elasticity theory, pl... Based on nonlocal thermoelastic theory, this article studies the reflection of waves in nanometersemi-conductor media. Firstly, the governing equations are established based on couplednonlocal elasticity theory, plasma diffusion equation, and moving equation. Then, using theharmonic method, the solution of the dissipation equation and the analytic expression of thereflection coefficient rate are obtained. Finally, the influences of nonlocal parameters on wavevelocities are showed graphically. It is found that after the introduction of nonlocal effect, thephase and group velocities all show the attenuation, and as the frequency increases, the nonlocalparameter is bigger, and the decay rate is faster. The reflection coefficient rate varies greatly withdifferent theories, with different reflection coefficient rates depending on the incident angle. 展开更多
关键词 Nonlocal theory Generalized thermoelastic theory Wave velocity Reflection coefficient rate
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Impact of openness, economic policy reform and regional shocks on trade and growth of Thailand: An econometric study 被引量:1
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作者 Thanet Wattanakul 《Chinese Business Review》 2009年第1期17-30,共14页
Thailand has currently enhanced and promoted intensive trade and investment liberalization and implemented long-term growth policy according with current regional economic integration, WTO obligations and globalizatio... Thailand has currently enhanced and promoted intensive trade and investment liberalization and implemented long-term growth policy according with current regional economic integration, WTO obligations and globalization. Nevertheless, several recent internal and external factors e.g. the massive SARS and avian flu outbreaks, the Indian Ocean tsunami devastation, the Asia financial crisis and domestic policy reforms (ICSEAD, 2006) have also impeded this policy. While the issues are important for Thailand and developing countries in Asia, only limited research has been undertaken to investigate them. The paper conducts a substantive quantitative study to contribute to these trade and development policy issues. A new econometric modelling policy method, namely the generalized gravity theory (Tran Van Hoa, 2004) is used to develop a simple flexible simultaneous-equation econometric model of Thailand's openness model with its seven major trade partners (ASEAN-4, Australia, the USA, the EU, China, Japan and India). Using data from the ICSEAD, the World Development Indicators and the Bank of Thailand databases, the paper reveals efficient and reliable empirical findings on trade-growth causality, trade determination including the impact of shocks and policy reform on trade and growth between Thailand and its major trade partners over the past two decades. The paper also provides evidence on the linkages between trade in goods, FDI and services and regional economic integration for more credible policy implications. 展开更多
关键词 trade and investment liberalization regional economic integration free trade agreements trade and growth causality generalized gravity theory modelling economic and trade policy
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Biexponential distribution of open times of a toy channel model
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作者 李翔 钟金金 +3 位作者 高学娟 吴宇宁 帅建伟 祁宏 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期41-47,共7页
The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexpone... The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexponential distribution of open times. One scheme is mathematically strict based on generator matrix theory, while the other one has a clear physical explanation according to an approximation process with numerical simulation of Markovian channel dynamics. Our comparison results suggest that even for biologically complex channels, in addition to carrying out a stochastic simulation, the strict theoretical analysis should be considered to understand the multiple exponential distributions of open times. 展开更多
关键词 ion channel biexponential distribution generator matrix theory Markovian simulation
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Thermal Wave Effect and Sintering Activation Energy at the Initial Stage of Field Assisted Sintering Process for Non-conductive Al_2O_3 Powders
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作者 ZHANG Long 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第6期1416-1421,共6页
The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was... The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process. 展开更多
关键词 field assisted sintering technique generalized thermoelastic theory thermal wave vacancy concentration difference sintering activation energy
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A nonlinear explicit dynamic GBT formulation for modeling impact response of thin-walled steel members
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作者 Duan Liping Zhao Jincheng 《Journal of Southeast University(English Edition)》 EI CAS 2018年第2期237-250,共14页
A nonlinear explicit dynamic finite element formulation based on the generalized beam theory(GBT)is proposed and developed to simulate the dynamic responses of prismatic thin-walled steel members under transverse impu... A nonlinear explicit dynamic finite element formulation based on the generalized beam theory(GBT)is proposed and developed to simulate the dynamic responses of prismatic thin-walled steel members under transverse impulsive loads.Considering the rate strengthening and thermal softening effects on member impact behavior,a modified Cowper-Symonds model for constructional steels is utilized.The element displacement field is built upon the superposition of GBT cross-section deformation modes,so arbitrary deformations such as cross-section distortions,local buckling and warping shear can all be involved by the proposed model.The amplitude function of each cross-section deformation mode is approximated by the cubic non-uniform B-spline basis functions.The Kirchhoff s thin-plate assumption is utilized in the construction of the bending related displacements.The Green-Lagrange strain tensor and the second Piola-Kirchhoff(PK2)stress tensor are employed to measure deformations and stresses at any material point,where stresses are assumed to be in plane-stress state.In order to verify the effectiveness of the proposed GBT model,three numerical cases involving impulsive loading of the thin-walled parts are given.The GBT results are compared with those of the Ls-Dyna shell finite element.It is shown that the proposed model and the shell finite element analysis has equivalent accuracy in displacement and stress.Moreover,the proposed model is much more computationally efficient and structurally clearer than the shell finite elements. 展开更多
关键词 generalized beam theory impact loading thin-walled steel member explicit dynamic integrations strain rate strengthening effect thermal softening effect
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Droplet Characterization Based on the Simulated Secondary Rainbows
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作者 Wenting Wang Jiayi Wang Yide Zhang 《Optics and Photonics Journal》 2021年第6期133-139,共7页
The droplet size, size distribution, refractive index, and temperature can be measured simultaneously by the rainbow technique. In the present work, the rainbow scattering diagram for a spherical droplet in the second... The droplet size, size distribution, refractive index, and temperature can be measured simultaneously by the rainbow technique. In the present work, the rainbow scattering diagram for a spherical droplet in the secondary rainbow region is simulated by the use of the generalized Lorenz-Mie theory. For achieving high spatial resolution in denser droplet sprays, a focused Gaussian beam is used. For droplet characterization, different inversion algorithms are investigated, which includes trough-trough (<em>θ</em><sub>min1</sub> and <em>θ</em><sub>min2</sub>) method and inflection-inflection (<em>θ</em><sub>inf1</sub> and <em>θ</em><sub>inf2</sub>) method. For the trough-trough algorithm, the absolute error of the refractive index is between −6.4 × 10<sup>−4</sup> and 1.7 × 10<sup>−4</sup>, and the error of the droplet radius is only between −0.55% and 1.77%. For the inflection-inflection algorithm, the maximum absolute error of the inverted refractive index is less than −1.1 × 10<sup>−3</sup>. The error of the droplet radius is between −0.75% and 5.67%. 展开更多
关键词 Particles Characterization Rainbow Pattern Generalized Lorenz-Mie theory
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Generalized non-linear strength theory and transformed stress space 被引量:63
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作者 YAO Yangping LU Dechun +1 位作者 ZHOU Annan ZOU Bo 《Science China(Technological Sciences)》 SCIE EI CAS 2004年第6期691-709,共19页
Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane... Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state. Keywords generalized non-linear strength theory (GNST) - transformed stress - constitutive model - application 展开更多
关键词 generalized non-linear strength theory (GNST) transformed stress constitutive model application
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