With the deepening of exchanges between China and other countries,especially the proposal of the Belt and Road Initiative,more and more foreign students come to China to study,putting forward higher requirements for t...With the deepening of exchanges between China and other countries,especially the proposal of the Belt and Road Initiative,more and more foreign students come to China to study,putting forward higher requirements for the education and management of colleges and universities in China.In the process of implementing the strategy of"one belt and one road",language interaction is the basic prerequisite for achieving exchanges and cooperation among different countries.In the face of this situation,by analyzing the existing problems in the training of overseas students in higher vocational colleges in China under the background of"One Belt and One Road"strategy,in this paper,the construction of the Chinese learning mode for overseas students in higher vocational colleges was put forward,hoping to provide help for the training of overseas students and solve the problem of foreign students'language learning.展开更多
Extreme sensitivity to initial values is an intrinsic character of chaotic systems. The evolution of a chaotic system has a spatiotemporal structure containing quasi-periodic changes of different spatiotemporal scales...Extreme sensitivity to initial values is an intrinsic character of chaotic systems. The evolution of a chaotic system has a spatiotemporal structure containing quasi-periodic changes of different spatiotemporal scales. This paper uses an empirical mode decomposition (EMD) method to decompose and compare the evolution of the time-dependent evolutions of the x-component of the Lorenz system. The results indicate that the sensitivity of intrinsic mode function (IMF) component is dependent on initial values, which provides some scientific evidence for the possibility of long-range climatic prediction.展开更多
The influe nce of initiation modes on the explosive dispersion process of the multi-layer co mposite charge(MCC) was studied.Overpressure sensors and high-speed photography system were used to investigate the energy r...The influe nce of initiation modes on the explosive dispersion process of the multi-layer co mposite charge(MCC) was studied.Overpressure sensors and high-speed photography system were used to investigate the energy release process of an MCC with a specific structure.The shock wave pressure and explosive dispersion characteristics of the MCC under different initiation modes were compared.The forming and expanding process of the shock wave of the composite charge under different initiation modes was determined.The separation position of the shock wave and fireball interface was determined.The calculation formulas of the shock radius and overpressure of the composite charge are presented.The radius of the shock wave of the composite charge was significantly affected by the initiation mode.Moreover,the development process of the composite explosive fireball under different initiation modes was analyzed,the variation rules of the composite charge dispersion radius and fireball dispersion velocity with time were obtained under the different initiation modes,the explosion energy release rate of composite charge under simultaneous initiation modes was the highest,and the peak overpressure under the simultaneous initiation mode was 1.61 times that of central single-point initiation.展开更多
In order to simultaneously measure the initiation toughness of pure mode Ⅰ and mode Ⅱ cracks in one specimen,a large-size double-cracked concave-convex plate(DCCP)specimen configuration was proposed.Impacting tests ...In order to simultaneously measure the initiation toughness of pure mode Ⅰ and mode Ⅱ cracks in one specimen,a large-size double-cracked concave-convex plate(DCCP)specimen configuration was proposed.Impacting tests were implemented in the drop plate impact device.Strain gauges were employed to measure impact loads and crack initiation time.The corresponding numerical model was established by using the dynamic finite difference program AUTODYN,and the experimental-numerical method and ABAQUS code were utilized to obtain the initial fracture toughness of the crack.Using experiments and numerical research,we concluded that the DCCP specimen is suitable for measuring the initial fracture toughness of pure mode Ⅰ and mode Ⅱ cracks at the same time;the dynamic initiation toughness increases with the increase of loading rate and the crack initiation time decreases with increasing loading rate;the initiation toughness of mode Ⅱ crack is 0.5 times that of mode Ⅰ crack when subjected to the same loading rate.For the pre-crack in the vicinity of the bottom of a sample,when its length increases from 20 to 100 mm,the dynamic initiation toughness of the pure mode Ⅰ crack gradually decreases,and the longer the lower crack length is,the easier the crack would initiate,but the dynamic initiation toughness of pure mode Ⅱ crack varies little.展开更多
President Xi Jinping put forward that, "China will further push the open economy to a higher level by enlarging its scale, expanding its area, and deepening its degree." This proposal provides new perspectiv...President Xi Jinping put forward that, "China will further push the open economy to a higher level by enlarging its scale, expanding its area, and deepening its degree." This proposal provides new perspectives for RMB internationalization. The new path of RMB internationalization shall be achieved under the Belt and Road Initiative and be a new option that is di erent from the "Three-Stage Theory" and regional monetary cooperation. RMB internationalization can only be realized through a government-driven mode with Chinese characteristics which shows the fundamental di erence from the internationalization of other currencies such as the US Dollar, Euro and Japanese Yen. The Chinese government can realize the strategic objective of RMB internationalization through improving national governance, applying policies and tools for macroeconomic regulation, and implementing the Belt and Road Initiative, as well as the operation of its nancial industry, the Silk Road Fund(SRF), and that of regional banks like the Asian Infrastructure Investment Bank(AIIB) and the BRICS New Development Bank(NDB). RMB internationalization is an important objective of China's political and economic development. Efforts must be made to steadily promote market-oriented reform of the RMB exchange rate and its forming mechanism, and reform of capital account convertibility so that RMB can become the leading global reserve currency. Meanwhile, China will also undertake more responsibilities as a major power for stable development of the international economy and nance.展开更多
An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration ...An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration of a fully collapsed ring is considered as a real dumbbell shape with a line touch between two 'bells', instead of the dumbbell shape with a point touch of two diametrically opposite points. Calculations are performed assuming that the dominant effect on the plastic energy dissipation has the circumferential bending mode. For the linear strain-hardening materials it is found that theoretical predictions based on the above model for both propagation pressure and initiation nressure are in good agreement with experimental results of Kyriakides et al.展开更多
Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is...Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.展开更多
With the development of the society, cooperative teaching is no longer a new topic, but a new teaching ideology with great zeitgeist. Nowadays, each part of the society pays more and more attention to cooperative spir...With the development of the society, cooperative teaching is no longer a new topic, but a new teaching ideology with great zeitgeist. Nowadays, each part of the society pays more and more attention to cooperative spirit, cooperative consciousness and cooperative skills. As a kind of competence which is more important than knowledge, cooperation is becoming a rather important accomplishment of people, which is quite popular among them. For a long time, the traditional teaching mode in our country is neither helpful to the development of the main role of students', nor to the students' cooperative consciousness or competence. Therefore, during the new round of curriculum reform, changing the students' learning methods has been a focus of people. Under this background, we bring"cooperative learning in groups"into our class, and try to explore it from multiple angles.In this thesis, I will give advice to the cooperative teaching mode through analyzing the theoretical basis, teaching mode and teaching characteristics of the cooperative teaching in order that students' initiatives can be improved in cooperative teaching.展开更多
The effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids in a generalized thermoplastic half-space are studied by using the Lord-Shulman (L-S) model and the dual-phase-la...The effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids in a generalized thermoplastic half-space are studied by using the Lord-Shulman (L-S) model and the dual-phase-lag (DPL) model. The analytical solutions for the displacements, stresses, temperature, diffusion concentration, and volume fraction field with different values of the magnetic field, the rotation, the gravity, and the initial stress are obtained and portrayed graphically. The results indicate that the effects of gravity, rotation, voids, diffusion, initial stress, and electromagnetic field are very pronounced on the physical properties of the material.展开更多
A theoretical analysis of the lateral resonances in 1-3 piezocomposites with poling initial stress is conducted using the Bloch wave theory. Based on the linear piezoelectricity theory, theoretical formulations that i...A theoretical analysis of the lateral resonances in 1-3 piezocomposites with poling initial stress is conducted using the Bloch wave theory. Based on the linear piezoelectricity theory, theoretical formulations that include initial stress for the propagation of acoustic plane waves are made. Numerical calculations are performed to study the effects of the initial stress on the lateral mode frequencies and the stop band. It is found that lateral mode frequencies increase with the piezoelectricity of the piezocomposites, but decrease with the poling initial stress. The influence of the initial shear stress on the lateral mode frequencies is minimal, and can thus be neglected.展开更多
The reinforced concrete(RC) structural component might suffer a great damage under close-in explosion.Different from distant explosions, blast loads generated by the close-in explosion are non-uniformly distributed on...The reinforced concrete(RC) structural component might suffer a great damage under close-in explosion.Different from distant explosions, blast loads generated by the close-in explosion are non-uniformly distributed on the structural component and may cause both local and structural failure. In this study,an experimental study was conducted to investigate the dynamic responses of RC beams under doubleend-initiated close-in explosions. The experimental results show that the distribution of blast loads generated by the double-end-initiated explosion is much more non-uniform than those generated by single-point detonation, which is caused by the self-Mach-reflection effects. A 3 D finite element model was developed and validated in LS-DYNA by employing the modified K&C model. Intensive numerical calculations were conducted to study the influences of the initiation way, scaled distance and longitudinal reinforcement ratio on the dynamic responses and failure modes of RC beams. Numerical results show that the RC beam suffers greater damage as the cylindrical explosive is detonated at its double ends than the scenario in which the cylindrical explosive is detonated at its central point. RC beams mainly suffer flexural failure and flexure-shear failure under the double-end close-in explosion, and the failure modes of RC beams change from the flexural damage to flexure-shear damage as the scaled distance or the longitudinal reinforcement ratio decreases. The direct shear failure mode is not usually observed in the double-end-initiated explosion, since the intense blast loads is basically concentrated in the midspan of RC beam, which is due to self-Mach-reflection enhancement.展开更多
Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buck...Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buckling.A finite element model which can simulate the transformation of pipeline laid on a sleeper from vertical buckling to lateral buckling is established in this work.The parameters of sleeper affecting pipeline buckling modes are analysed,and a new kind of sleeper is proposed aimed at avoiding antisymmetric buckling.Results show that the lateral trigger force can avoid antisymmetric lateral buckling when acting between 1℃and 13℃before the critical buckling temperature.The range increases slightly with increasing trigger force.Compared with an ordinary sleeper,the proposed new sleeper with slider can reduce the critical buckling temperature by 25%,which significantly improves the success rate of sleepers.展开更多
In this paper we introduce the effect of initial stress on a magneto-thermoe- lastic functionally graded material (FGM) with Green Naghdi theory with energy dissipation. A system of PDE was obtained. The normal mode a...In this paper we introduce the effect of initial stress on a magneto-thermoe- lastic functionally graded material (FGM) with Green Naghdi theory with energy dissipation. A system of PDE was obtained. The normal mode analysis method is used to convert these equations into ODE and get the analytical solution to write expressions for displacements, temperatures, stresses. Some comparisons carried out to view the initial stress influence on the field variables. Numerical results are graphed to view the influence of initial stress. Some particular cases are deduced in this study.展开更多
Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element (FE) model of an all fracture mode (AFM) specimen was built for the study of 3-D mixed mode crack fracture beha...Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element (FE) model of an all fracture mode (AFM) specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors (SIFs) were calculated by the modified virtual crack closure integral (MVCCI) method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.展开更多
The present problem is concerned with the deformation of an infinite fibre-reinforced generalized thermoe-lastic medium with hydrostatic initial stress under the influence of mechanical force. The normal mode analysis...The present problem is concerned with the deformation of an infinite fibre-reinforced generalized thermoe-lastic medium with hydrostatic initial stress under the influence of mechanical force. The normal mode analysis is used to obtain the analytical expressions of the displacement components, force stress and temperature distribution. The numerical results are given and presented graphically for Green -Lindsay [4] theory of thermoelasticity. Comparisons are made in the presence and absence of hydrostatic initial stress and anisotropy.展开更多
文摘With the deepening of exchanges between China and other countries,especially the proposal of the Belt and Road Initiative,more and more foreign students come to China to study,putting forward higher requirements for the education and management of colleges and universities in China.In the process of implementing the strategy of"one belt and one road",language interaction is the basic prerequisite for achieving exchanges and cooperation among different countries.In the face of this situation,by analyzing the existing problems in the training of overseas students in higher vocational colleges in China under the background of"One Belt and One Road"strategy,in this paper,the construction of the Chinese learning mode for overseas students in higher vocational colleges was put forward,hoping to provide help for the training of overseas students and solve the problem of foreign students'language learning.
文摘Extreme sensitivity to initial values is an intrinsic character of chaotic systems. The evolution of a chaotic system has a spatiotemporal structure containing quasi-periodic changes of different spatiotemporal scales. This paper uses an empirical mode decomposition (EMD) method to decompose and compare the evolution of the time-dependent evolutions of the x-component of the Lorenz system. The results indicate that the sensitivity of intrinsic mode function (IMF) component is dependent on initial values, which provides some scientific evidence for the possibility of long-range climatic prediction.
文摘The influe nce of initiation modes on the explosive dispersion process of the multi-layer co mposite charge(MCC) was studied.Overpressure sensors and high-speed photography system were used to investigate the energy release process of an MCC with a specific structure.The shock wave pressure and explosive dispersion characteristics of the MCC under different initiation modes were compared.The forming and expanding process of the shock wave of the composite charge under different initiation modes was determined.The separation position of the shock wave and fireball interface was determined.The calculation formulas of the shock radius and overpressure of the composite charge are presented.The radius of the shock wave of the composite charge was significantly affected by the initiation mode.Moreover,the development process of the composite explosive fireball under different initiation modes was analyzed,the variation rules of the composite charge dispersion radius and fireball dispersion velocity with time were obtained under the different initiation modes,the explosion energy release rate of composite charge under simultaneous initiation modes was the highest,and the peak overpressure under the simultaneous initiation mode was 1.61 times that of central single-point initiation.
基金Projects(U19A2098,1210021843)supported by the National Natural Science Foundation of ChinaProject(2021SCU12130)supported by Fundamental Research Funds for the Central Universities,China+1 种基金Project(2021YJ0511)supported by the Sichuan Science and Technology Program,ChinaProjects(DESEYU202205,DESE202005)supported by the Open Fund of Key Laboratory of Deep Earth Science and Engineering,China。
文摘In order to simultaneously measure the initiation toughness of pure mode Ⅰ and mode Ⅱ cracks in one specimen,a large-size double-cracked concave-convex plate(DCCP)specimen configuration was proposed.Impacting tests were implemented in the drop plate impact device.Strain gauges were employed to measure impact loads and crack initiation time.The corresponding numerical model was established by using the dynamic finite difference program AUTODYN,and the experimental-numerical method and ABAQUS code were utilized to obtain the initial fracture toughness of the crack.Using experiments and numerical research,we concluded that the DCCP specimen is suitable for measuring the initial fracture toughness of pure mode Ⅰ and mode Ⅱ cracks at the same time;the dynamic initiation toughness increases with the increase of loading rate and the crack initiation time decreases with increasing loading rate;the initiation toughness of mode Ⅱ crack is 0.5 times that of mode Ⅰ crack when subjected to the same loading rate.For the pre-crack in the vicinity of the bottom of a sample,when its length increases from 20 to 100 mm,the dynamic initiation toughness of the pure mode Ⅰ crack gradually decreases,and the longer the lower crack length is,the easier the crack would initiate,but the dynamic initiation toughness of pure mode Ⅱ crack varies little.
文摘President Xi Jinping put forward that, "China will further push the open economy to a higher level by enlarging its scale, expanding its area, and deepening its degree." This proposal provides new perspectives for RMB internationalization. The new path of RMB internationalization shall be achieved under the Belt and Road Initiative and be a new option that is di erent from the "Three-Stage Theory" and regional monetary cooperation. RMB internationalization can only be realized through a government-driven mode with Chinese characteristics which shows the fundamental di erence from the internationalization of other currencies such as the US Dollar, Euro and Japanese Yen. The Chinese government can realize the strategic objective of RMB internationalization through improving national governance, applying policies and tools for macroeconomic regulation, and implementing the Belt and Road Initiative, as well as the operation of its nancial industry, the Silk Road Fund(SRF), and that of regional banks like the Asian Infrastructure Investment Bank(AIIB) and the BRICS New Development Bank(NDB). RMB internationalization is an important objective of China's political and economic development. Efforts must be made to steadily promote market-oriented reform of the RMB exchange rate and its forming mechanism, and reform of capital account convertibility so that RMB can become the leading global reserve currency. Meanwhile, China will also undertake more responsibilities as a major power for stable development of the international economy and nance.
基金Project supported by National Natural Science Foundation
文摘An analytical model of a ring with six yield hinges and two deformable arc segments is presented for. the prediction of the buckle propagation pressure and initiation pressure in offshore pipelines. The configuration of a fully collapsed ring is considered as a real dumbbell shape with a line touch between two 'bells', instead of the dumbbell shape with a point touch of two diametrically opposite points. Calculations are performed assuming that the dominant effect on the plastic energy dissipation has the circumferential bending mode. For the linear strain-hardening materials it is found that theoretical predictions based on the above model for both propagation pressure and initiation nressure are in good agreement with experimental results of Kyriakides et al.
文摘Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.
文摘With the development of the society, cooperative teaching is no longer a new topic, but a new teaching ideology with great zeitgeist. Nowadays, each part of the society pays more and more attention to cooperative spirit, cooperative consciousness and cooperative skills. As a kind of competence which is more important than knowledge, cooperation is becoming a rather important accomplishment of people, which is quite popular among them. For a long time, the traditional teaching mode in our country is neither helpful to the development of the main role of students', nor to the students' cooperative consciousness or competence. Therefore, during the new round of curriculum reform, changing the students' learning methods has been a focus of people. Under this background, we bring"cooperative learning in groups"into our class, and try to explore it from multiple angles.In this thesis, I will give advice to the cooperative teaching mode through analyzing the theoretical basis, teaching mode and teaching characteristics of the cooperative teaching in order that students' initiatives can be improved in cooperative teaching.
文摘The effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids in a generalized thermoplastic half-space are studied by using the Lord-Shulman (L-S) model and the dual-phase-lag (DPL) model. The analytical solutions for the displacements, stresses, temperature, diffusion concentration, and volume fraction field with different values of the magnetic field, the rotation, the gravity, and the initial stress are obtained and portrayed graphically. The results indicate that the effects of gravity, rotation, voids, diffusion, initial stress, and electromagnetic field are very pronounced on the physical properties of the material.
基金Project supported by the National Natural Science Foundation of China(Nos.90205030 and 10472088)
文摘A theoretical analysis of the lateral resonances in 1-3 piezocomposites with poling initial stress is conducted using the Bloch wave theory. Based on the linear piezoelectricity theory, theoretical formulations that include initial stress for the propagation of acoustic plane waves are made. Numerical calculations are performed to study the effects of the initial stress on the lateral mode frequencies and the stop band. It is found that lateral mode frequencies increase with the piezoelectricity of the piezocomposites, but decrease with the poling initial stress. The influence of the initial shear stress on the lateral mode frequencies is minimal, and can thus be neglected.
基金supported by the National Natural Science Foundations of China(Nos. 51622812, and 51427807)National Basic Research Program of China(No. 2015CB058003)China Postdoctoral Science Foundation(No. 2017M613379)
文摘The reinforced concrete(RC) structural component might suffer a great damage under close-in explosion.Different from distant explosions, blast loads generated by the close-in explosion are non-uniformly distributed on the structural component and may cause both local and structural failure. In this study,an experimental study was conducted to investigate the dynamic responses of RC beams under doubleend-initiated close-in explosions. The experimental results show that the distribution of blast loads generated by the double-end-initiated explosion is much more non-uniform than those generated by single-point detonation, which is caused by the self-Mach-reflection effects. A 3 D finite element model was developed and validated in LS-DYNA by employing the modified K&C model. Intensive numerical calculations were conducted to study the influences of the initiation way, scaled distance and longitudinal reinforcement ratio on the dynamic responses and failure modes of RC beams. Numerical results show that the RC beam suffers greater damage as the cylindrical explosive is detonated at its double ends than the scenario in which the cylindrical explosive is detonated at its central point. RC beams mainly suffer flexural failure and flexure-shear failure under the double-end close-in explosion, and the failure modes of RC beams change from the flexural damage to flexure-shear damage as the scaled distance or the longitudinal reinforcement ratio decreases. The direct shear failure mode is not usually observed in the double-end-initiated explosion, since the intense blast loads is basically concentrated in the midspan of RC beam, which is due to self-Mach-reflection enhancement.
基金financially supported by the National Science Fund for Distinguished Young Scholars of China (Grant No.51825904)。
文摘Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buckling.A finite element model which can simulate the transformation of pipeline laid on a sleeper from vertical buckling to lateral buckling is established in this work.The parameters of sleeper affecting pipeline buckling modes are analysed,and a new kind of sleeper is proposed aimed at avoiding antisymmetric buckling.Results show that the lateral trigger force can avoid antisymmetric lateral buckling when acting between 1℃and 13℃before the critical buckling temperature.The range increases slightly with increasing trigger force.Compared with an ordinary sleeper,the proposed new sleeper with slider can reduce the critical buckling temperature by 25%,which significantly improves the success rate of sleepers.
文摘In this paper we introduce the effect of initial stress on a magneto-thermoe- lastic functionally graded material (FGM) with Green Naghdi theory with energy dissipation. A system of PDE was obtained. The normal mode analysis method is used to convert these equations into ODE and get the analytical solution to write expressions for displacements, temperatures, stresses. Some comparisons carried out to view the initial stress influence on the field variables. Numerical results are graphed to view the influence of initial stress. Some particular cases are deduced in this study.
文摘Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element (FE) model of an all fracture mode (AFM) specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors (SIFs) were calculated by the modified virtual crack closure integral (MVCCI) method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.
文摘The present problem is concerned with the deformation of an infinite fibre-reinforced generalized thermoe-lastic medium with hydrostatic initial stress under the influence of mechanical force. The normal mode analysis is used to obtain the analytical expressions of the displacement components, force stress and temperature distribution. The numerical results are given and presented graphically for Green -Lindsay [4] theory of thermoelasticity. Comparisons are made in the presence and absence of hydrostatic initial stress and anisotropy.