本文在麻省理工学院(MIT)应力法则基础上考虑了中间应力的影响,采用剑桥应力法则,提出了一种连续临界状态塑性理论,从而改进了Naylor的计算模型。并建议用一种简单而直接的方法来确定椭圆形边界面的共轭点和限制点(cut off point)。该...本文在麻省理工学院(MIT)应力法则基础上考虑了中间应力的影响,采用剑桥应力法则,提出了一种连续临界状态塑性理论,从而改进了Naylor的计算模型。并建议用一种简单而直接的方法来确定椭圆形边界面的共轭点和限制点(cut off point)。该模型比修正的剑桥粘土模型具有很多优点,可用于很多土力学问题。展开更多
Using a 1.5-layer reduced-gravity nonlinear shallow-water equation model, we studied the effect of the meridional wind on the western boundary currents (WBC) at critical states with hysteresis courses. The results of ...Using a 1.5-layer reduced-gravity nonlinear shallow-water equation model, we studied the effect of the meridional wind on the western boundary currents (WBC) at critical states with hysteresis courses. The results of the simulation indicate that the WBC is prone to penetrating into the gap under northerly winds, and its path is more difficult to alter due to the larger interval between the two critical transition curves (C1P and C1L). For southerly winds, the WBC is prone to leaping across the gap, and its path is easier to alter due to the smaller interval between the two critical transition curves. The simulation results also indicate that the meridional winds over the southern region of the gap are the dominant factor determining the formation of the WBC. The dynamic mechanism influencing the transport of WBC near the gap is both Ekman transport and the blocking of Ekman transport. Ekman transport induced by northerly winds may reduce the transport of the WBC, causing the β-effect to dominate the meridional advection (promoting the penetration). Southerly winds, however, may enhance the transport of the WBC, causing the meridional advection to dominate the β-effect (promoting the leaping state). These results explain some structural features of the Kuroshio at the Luzon Strait.展开更多
Complex behavior in a selective aging simple neuron model based on small world networks is investigated. The basic elements of the model are endowed with the main features of a neuron function. The structure of the se...Complex behavior in a selective aging simple neuron model based on small world networks is investigated. The basic elements of the model are endowed with the main features of a neuron function. The structure of the selective aging neuron model is discussed. We also give some properties of the new network and find that the neuron model displays a power-law behavior. If the brain network is small world-like network, the mean avalanche size is almost the same unless the aging parameter is big enough.展开更多
A modified Olami Feder-Christensen model of self-organized criticality on a square lattice with the properties of small world networks has been studied.We find that our model displays power-law behavior and the expone...A modified Olami Feder-Christensen model of self-organized criticality on a square lattice with the properties of small world networks has been studied.We find that our model displays power-law behavior and the exponent τ of the model depends on φ,the density of long-range connections in our network.展开更多
Particle breakage has a significant influence on the stress-strain and strength behavior of rockfill material.A breakage critical state theory(BCST)was proposed to describe the evolution of particle breakage.The break...Particle breakage has a significant influence on the stress-strain and strength behavior of rockfill material.A breakage critical state theory(BCST)was proposed to describe the evolution of particle breakage.The breakage critical state line in the breakage critical state theory was correlated with the breakage factor,which was fundamentally different from that of the original critical state theory.A simple elastoplastic constitutive model was developed for rockfill in the frame of BCST.An associated flow rule was adopted in this model.Isotropic,contractive and distortional hardening rules were suggested in view of the particle breakage.It was observed that the proposed model could well represent the complex deformation behaviors of rockfill material,such as the strain hardening,post-peak strain softening,volumetric contraction,volumetric expansion,and particle breakage under different initial confining pressures.展开更多
The particle breakage during specimen compaction had more significant influence on the position of the breakage critical-state line(BCSL)of Tacheng rockfill material(TRM)in the e-lnp’plane than the particle breakage ...The particle breakage during specimen compaction had more significant influence on the position of the breakage critical-state line(BCSL)of Tacheng rockfill material(TRM)in the e-lnp’plane than the particle breakage during shearing,based on the large-scale triaxial compression tests on TRM in a wide range of densities and pressures.The state-dependent dilatancy and the plastic modulus were correlated to the breakage index,based on the formulations of the BCSL of TRM in the e-lnp’plane.The state-dependent model considering particle breakage was proposed for TRM within the framework of the generalized plasticity theory.The proposed model contained fourteen material constants.The test data of TRM from Group A were adopted to determine these material constants,while the test data from Group B were used independently to validate the model predictive capacity.The comparisons between model simulations and test data illustrated that the model with consideration of particle breakage could well represent the stress-strain behaviors of TRM,e.g.,the strain hardening and volumetric contraction behaviors at a loose state and the strain softening and volumetric expansion behaviors at a dense state,and also the particle breakage behaviors of TRM.展开更多
It is a challenge to suggest a constitutive model for describing the stress-strain behavior of sand-fines mixtures due to that these granular mixtures exhibited very complex behaviors at different densities, pressure...It is a challenge to suggest a constitutive model for describing the stress-strain behavior of sand-fines mixtures due to that these granular mixtures exhibited very complex behaviors at different densities, pressures and fines contents. In this study, an elastoplastic constitutive model within the framework of the bounding surface plasticity and critical state theories was proposed for sand-nonplastic-fines mixtures by using the concept of the equivalent-skeleton void ratio and equivalent-skeleton void-ratio state index. The proposed model with a set of material constants calibrated from a few tests could be used to model the fines-dependent and state-dependent behaviors of the sand-nonplastic-fines mixture including the strain- softening and volumetric-expansion behaviors in the drained triaxial compression tests, and also the effects of fines content on the critical state lines in both the deviatoric stress versus mean effective stress and the void ratio versus mean effective stress planes.展开更多
A comprehensive analysis of liquid fuel droplet evaporation at supercritical conditions is performed.The numerical model is based on complete time-dependent conservation equations,with a full account of variable therm...A comprehensive analysis of liquid fuel droplet evaporation at supercritical conditions is performed.The numerical model is based on complete time-dependent conservation equations,with a full account of variable thermophysical properties and vapor-liquid interfacial thermodynamics.And the model employs the Peng-Robinson(PR)equation of state(EOS).As a specific example,problems involving n-heptane droplet in nitrogen gas are investigated.The results indicate that the increase of ambient pressure and temperature results in the increase of surface temperature rise rate and surface regression rate.The transition from subcritical state to supercritical state can occur at the droplet surface when the droplet evaporates in a strongly supercritical environment.展开更多
文摘本文在麻省理工学院(MIT)应力法则基础上考虑了中间应力的影响,采用剑桥应力法则,提出了一种连续临界状态塑性理论,从而改进了Naylor的计算模型。并建议用一种简单而直接的方法来确定椭圆形边界面的共轭点和限制点(cut off point)。该模型比修正的剑桥粘土模型具有很多优点,可用于很多土力学问题。
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Nos. KZCX1-YW-12, KZCX2-YW-201)the National Natural Science Foundation of China (No. 90411013)+2 种基金the National Basic Research Program of China (973 Program, No. 2006CB403600)NSFC's Outstanding Youth Grant (No. 40888001)the 100-Talent Program of the CAS, and the Outstanding Youth Grant of Shandong Province
文摘Using a 1.5-layer reduced-gravity nonlinear shallow-water equation model, we studied the effect of the meridional wind on the western boundary currents (WBC) at critical states with hysteresis courses. The results of the simulation indicate that the WBC is prone to penetrating into the gap under northerly winds, and its path is more difficult to alter due to the larger interval between the two critical transition curves (C1P and C1L). For southerly winds, the WBC is prone to leaping across the gap, and its path is easier to alter due to the smaller interval between the two critical transition curves. The simulation results also indicate that the meridional winds over the southern region of the gap are the dominant factor determining the formation of the WBC. The dynamic mechanism influencing the transport of WBC near the gap is both Ekman transport and the blocking of Ekman transport. Ekman transport induced by northerly winds may reduce the transport of the WBC, causing the β-effect to dominate the meridional advection (promoting the penetration). Southerly winds, however, may enhance the transport of the WBC, causing the meridional advection to dominate the β-effect (promoting the leaping state). These results explain some structural features of the Kuroshio at the Luzon Strait.
基金National Natural Science Foundation of China under Grant No.10675060
文摘Complex behavior in a selective aging simple neuron model based on small world networks is investigated. The basic elements of the model are endowed with the main features of a neuron function. The structure of the selective aging neuron model is discussed. We also give some properties of the new network and find that the neuron model displays a power-law behavior. If the brain network is small world-like network, the mean avalanche size is almost the same unless the aging parameter is big enough.
文摘A modified Olami Feder-Christensen model of self-organized criticality on a square lattice with the properties of small world networks has been studied.We find that our model displays power-law behavior and the exponent τ of the model depends on φ,the density of long-range connections in our network.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.42071078,42171130,and 42201138)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010087)the State Key Laboratory Program of Frozen Soil Engineering of China(Grant No.SKLFSE201915).
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.106112015CDJXY200008)China Scholarship Council(Grant No.201306710022)
文摘Particle breakage has a significant influence on the stress-strain and strength behavior of rockfill material.A breakage critical state theory(BCST)was proposed to describe the evolution of particle breakage.The breakage critical state line in the breakage critical state theory was correlated with the breakage factor,which was fundamentally different from that of the original critical state theory.A simple elastoplastic constitutive model was developed for rockfill in the frame of BCST.An associated flow rule was adopted in this model.Isotropic,contractive and distortional hardening rules were suggested in view of the particle breakage.It was observed that the proposed model could well represent the complex deformation behaviors of rockfill material,such as the strain hardening,post-peak strain softening,volumetric contraction,volumetric expansion,and particle breakage under different initial confining pressures.
基金supported by the National Natural Science Foundation for Distinguished Young Scholar(Grant No.50825901)the 111 Project(Grant No.B13024)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT1125)the Project supported by the National Natural Science Foundation of China(Grant No.51379067)the Fundamental Research Funds for the Central Universities(Grant No.2011B14514)
文摘The particle breakage during specimen compaction had more significant influence on the position of the breakage critical-state line(BCSL)of Tacheng rockfill material(TRM)in the e-lnp’plane than the particle breakage during shearing,based on the large-scale triaxial compression tests on TRM in a wide range of densities and pressures.The state-dependent dilatancy and the plastic modulus were correlated to the breakage index,based on the formulations of the BCSL of TRM in the e-lnp’plane.The state-dependent model considering particle breakage was proposed for TRM within the framework of the generalized plasticity theory.The proposed model contained fourteen material constants.The test data of TRM from Group A were adopted to determine these material constants,while the test data from Group B were used independently to validate the model predictive capacity.The comparisons between model simulations and test data illustrated that the model with consideration of particle breakage could well represent the stress-strain behaviors of TRM,e.g.,the strain hardening and volumetric contraction behaviors at a loose state and the strain softening and volumetric expansion behaviors at a dense state,and also the particle breakage behaviors of TRM.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51509024 and 51678094)the Fundamental Research Funds for the Central Universities (Grant No. 106112015CDJXY200008)the Project funded by China Postdoctoral Science Foundation (Grant No. 2016M590864)
文摘It is a challenge to suggest a constitutive model for describing the stress-strain behavior of sand-fines mixtures due to that these granular mixtures exhibited very complex behaviors at different densities, pressures and fines contents. In this study, an elastoplastic constitutive model within the framework of the bounding surface plasticity and critical state theories was proposed for sand-nonplastic-fines mixtures by using the concept of the equivalent-skeleton void ratio and equivalent-skeleton void-ratio state index. The proposed model with a set of material constants calibrated from a few tests could be used to model the fines-dependent and state-dependent behaviors of the sand-nonplastic-fines mixture including the strain- softening and volumetric-expansion behaviors in the drained triaxial compression tests, and also the effects of fines content on the critical state lines in both the deviatoric stress versus mean effective stress and the void ratio versus mean effective stress planes.
基金supported by the National Natural Science Foundation of China(Grant No,50376003)
文摘A comprehensive analysis of liquid fuel droplet evaporation at supercritical conditions is performed.The numerical model is based on complete time-dependent conservation equations,with a full account of variable thermophysical properties and vapor-liquid interfacial thermodynamics.And the model employs the Peng-Robinson(PR)equation of state(EOS).As a specific example,problems involving n-heptane droplet in nitrogen gas are investigated.The results indicate that the increase of ambient pressure and temperature results in the increase of surface temperature rise rate and surface regression rate.The transition from subcritical state to supercritical state can occur at the droplet surface when the droplet evaporates in a strongly supercritical environment.
