Two-dimensional cellular automaton(CA)simulations of phase transformations of binary alloys during solidification were reported.The modelling incorporates local concentration and heat changes into a nucleation or grow...Two-dimensional cellular automaton(CA)simulations of phase transformations of binary alloys during solidification were reported.The modelling incorporates local concentration and heat changes into a nucleation or growth function,which is utilized by the automaton in a probabilistic fashion.These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification.The simulated results show that the final morphology during solidification is related with the cooling conditions.The established model can be used to evaluate the phase transformation of binary alloys during solidification.展开更多
Laser Schlieren device was established to observe Rayleigh-Bénard-Marangoni effect produced in thick liquid depth by the diffusion of binary liquid mixtures.A recorder and a camera separately recorded dynamic and...Laser Schlieren device was established to observe Rayleigh-Bénard-Marangoni effect produced in thick liquid depth by the diffusion of binary liquid mixtures.A recorder and a camera separately recorded dynamic and static convective flow patterns during experiment.According to different signs of Ma number and Ra number,different binary liquid mixtures were selected to investigate the RBM effect induced by different driven mechanism including density gradient or surface tension gradient or combination of both.Qualitative analysis to experiment results was presented.展开更多
The study deals with the numerical modeling of leachate distribution in the porous medium located under a municipal solid waste disposal landfill(MSWLF).The considered three-layer system is based on geological data ob...The study deals with the numerical modeling of leachate distribution in the porous medium located under a municipal solid waste disposal landfill(MSWLF).The considered three-layer system is based on geological data obtained from field measurements.For simplicity,the problem is investigated by assuming a two-component approach.Nevertheless,the heat produced by landfills due to biological and chemical processes and the thermal diffusion mechanism contributing to pollution transport are taken into account.The numerical modeling of the propagation of leachate in the considered layered porous medium is implemented for parameters corresponding to natural soil and for the case where disruption of the porous medium structure is due to cracks formation or erosion.The latter is accompanied by an increase in rock permeability.In this case,the emergence of multi-vortex flow in the layer of high permeability is observed to substantially influence the bottom layers and cause intensification of the leachate propagation.These effects should be taken into account when estimating the parameters and properties of materials required for the construction of solid waste disposal facilities.展开更多
The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kine...The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams, which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.展开更多
Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solu...Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solute flux fields in bulk liquid. The exact solutions for solute concentration and flux in bulk liquid were obtained using hyperbolic diffusion equations. The results show the transition from diffusion-limited to purely thermally controlled solidification with effective diffusion coefficient →0 and complete solute trapping KLNDM（v）→1 at v→vDb for any kind of solid-liquid interface kinetics. Critical parameter for diffusionless solidification and complete solute trapping is the diffusion speed in bulk liquid vDb. Different models for solute trapping at the interface with different interface kinetic approaches were considered.展开更多
The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereeva...The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.展开更多
Diffusion coefficients were determined for benzene, toluene, ethylbenzene, p-xylene, o-xylene, 1, 3, 5-trimethylbenzene in n -heptane and in n-octane at 303.2K to 333.2K. A new predictive equation for liquid diffusion...Diffusion coefficients were determined for benzene, toluene, ethylbenzene, p-xylene, o-xylene, 1, 3, 5-trimethylbenzene in n -heptane and in n-octane at 303.2K to 333.2K. A new predictive equation for liquid diffusion coefficients, based on Eyring's absolute rate theory, was proposed. The active energy of diffusion was determined from the active energy of viscosity. It had the advantage of being based entirely on theoretical considerations and involved no experimental curve-fitting parameters.展开更多
Diffusion is a ubiquitous physical phenomenon where thermodynamic nonequilibrium effects(TNEs) are outstanding issues. In this work, we employ the discrete Boltzmann method to investigate the TNEs in the dynamic proce...Diffusion is a ubiquitous physical phenomenon where thermodynamic nonequilibrium effects(TNEs) are outstanding issues. In this work, we employ the discrete Boltzmann method to investigate the TNEs in the dynamic process of binary diffusion. The main features of the distribution function in velocity space are recovered and discussed.It is found that, with the decreasing gradients of macroscopic quantities(such as density, concentration, velocity, etc.),both the local and global TNEs decrease with the time but increase with the relaxation time in a power law, respectively.展开更多
基金Project(50572013) supported by the National Natural Science Foundation of ChinaProject(G2000067104) supported by the National Basic Research Program of China
文摘Two-dimensional cellular automaton(CA)simulations of phase transformations of binary alloys during solidification were reported.The modelling incorporates local concentration and heat changes into a nucleation or growth function,which is utilized by the automaton in a probabilistic fashion.These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification.The simulated results show that the final morphology during solidification is related with the cooling conditions.The established model can be used to evaluate the phase transformation of binary alloys during solidification.
文摘Laser Schlieren device was established to observe Rayleigh-Bénard-Marangoni effect produced in thick liquid depth by the diffusion of binary liquid mixtures.A recorder and a camera separately recorded dynamic and static convective flow patterns during experiment.According to different signs of Ma number and Ra number,different binary liquid mixtures were selected to investigate the RBM effect induced by different driven mechanism including density gradient or surface tension gradient or combination of both.Qualitative analysis to experiment results was presented.
文摘The study deals with the numerical modeling of leachate distribution in the porous medium located under a municipal solid waste disposal landfill(MSWLF).The considered three-layer system is based on geological data obtained from field measurements.For simplicity,the problem is investigated by assuming a two-component approach.Nevertheless,the heat produced by landfills due to biological and chemical processes and the thermal diffusion mechanism contributing to pollution transport are taken into account.The numerical modeling of the propagation of leachate in the considered layered porous medium is implemented for parameters corresponding to natural soil and for the case where disruption of the porous medium structure is due to cracks formation or erosion.The latter is accompanied by an increase in rock permeability.In this case,the emergence of multi-vortex flow in the layer of high permeability is observed to substantially influence the bottom layers and cause intensification of the leachate propagation.These effects should be taken into account when estimating the parameters and properties of materials required for the construction of solid waste disposal facilities.
基金Financial supports by the NSFC(China)under the research projects(No.50071058 and No.59725101)by the CAS(China)-CNR(Italy)under an international collaboration agreement are gratefully acknowledged.
文摘The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams, which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.
文摘Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solute flux fields in bulk liquid. The exact solutions for solute concentration and flux in bulk liquid were obtained using hyperbolic diffusion equations. The results show the transition from diffusion-limited to purely thermally controlled solidification with effective diffusion coefficient →0 and complete solute trapping KLNDM（v）→1 at v→vDb for any kind of solid-liquid interface kinetics. Critical parameter for diffusionless solidification and complete solute trapping is the diffusion speed in bulk liquid vDb. Different models for solute trapping at the interface with different interface kinetic approaches were considered.
基金Project ( 2001AA218011) supported by the National High Technology Development "863" Program of China
文摘The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.
文摘Diffusion coefficients were determined for benzene, toluene, ethylbenzene, p-xylene, o-xylene, 1, 3, 5-trimethylbenzene in n -heptane and in n-octane at 303.2K to 333.2K. A new predictive equation for liquid diffusion coefficients, based on Eyring's absolute rate theory, was proposed. The active energy of diffusion was determined from the active energy of viscosity. It had the advantage of being based entirely on theoretical considerations and involved no experimental curve-fitting parameters.
基金Supported by the MOST National Key Research and Development Programme under Grant No.2016YFB0600805the China Postdoctoral Science Foundation under Grant No.2017M620757+1 种基金the Center for Combustion Energy at Tsinghua University,Natural Science Foundation of Hebei Province under Grant Nos.A2017409014,ZD2017001 and A201500111,FJKLMAA,Fujian Normal Universitythe UK Engineering and Physical Sciences Research Council under the Project UK Consortium on Mesoscale Engineering Sciences(UKCOMES)under Grant No.EP/L00030X/1
文摘Diffusion is a ubiquitous physical phenomenon where thermodynamic nonequilibrium effects(TNEs) are outstanding issues. In this work, we employ the discrete Boltzmann method to investigate the TNEs in the dynamic process of binary diffusion. The main features of the distribution function in velocity space are recovered and discussed.It is found that, with the decreasing gradients of macroscopic quantities(such as density, concentration, velocity, etc.),both the local and global TNEs decrease with the time but increase with the relaxation time in a power law, respectively.
