To investigate the effect of unsaturated aliphatic hydrocarbons on PAHs （polycyclic aromatic hydrocarbons） formation, numerical analysis using detailed reaction mechanism is performed. For the carbon black produced ...To investigate the effect of unsaturated aliphatic hydrocarbons on PAHs （polycyclic aromatic hydrocarbons） formation, numerical analysis using detailed reaction mechanism is performed. For the carbon black produced by benzene feedstock, three kinds of unsaturated aliphatic hydrocarbons （acetylene, diacetylene, and vinylacetylene） are added. The detailed reaction mechanism which is proposed by Wang and Frenklach is consisted by 527 reactions and 99 chemical species. The formations of PAHs and nuclei are promoted by unsaturated aliphatic hydrocarbons addition. There exits optimal benzene/acetylene ratio （XA/XB = 0.50）, benzene/diacetylene mixture ratio （XD/XB = 0.60）, benzene/vinyl-acetylene mixture ratio （XV/XB = 0.25）. The formation of nuclei is most promoted by acetylene addition, and the benzene/acetylene mixture ratio is 0.50.展开更多
To better understand the fusion mechanism of heated carbon black, heat treatment is conducted for carbon black produced by benzene pyrolysis. The effects of （a） heating time, （b） heating temperature and （c） heat...To better understand the fusion mechanism of heated carbon black, heat treatment is conducted for carbon black produced by benzene pyrolysis. The effects of （a） heating time, （b） heating temperature and （c） heating rate on the aggregate shape and mean primary particle diameter of the carbon black are investigated using TEM （transmission electron microscopy）. The mean primary particle diameter does not change significantly when carbon black is heat treated. For short heating times and low heating temperatures, the aggregate shapes become simple when compared with those of non-heated carbon black, and shapes become complex with an increase in the heating time. Also, for low heating rates, the aggregate shapes become significantly simple when compared with those of non-heated carbon black. The results of this study suggest that sintering between primary particles is promoted under relatively low heating temperatures, and Ostwald ripening among aggregates is promoted under relatively high heating temperatures.展开更多
Grain growth,a competitive growth of crystal grains accompanied by curvature-driven boundary migration,is one of the most fundamental phenomena in the context of metallurgy and other scientific disciplines.However,the...Grain growth,a competitive growth of crystal grains accompanied by curvature-driven boundary migration,is one of the most fundamental phenomena in the context of metallurgy and other scientific disciplines.However,the true picture of grain growth is still controversial,even for the simplest(or‘ideal’)case.This problem can be addressed only by large-scale numerical simulation.Here,we analyze ideal grain growth via ultra-large-scale phase-field simulations on a supercomputer for elucidating the corresponding authentic statistical behaviors.The performed simulations are more than ten times larger in time and space than the ones previously considered as the largest;this computational scale gives a strong indication of the achievement of true steady-state growth with statistically sufficient number of grains.Moreover,we provide a comprehensive theoretical description of ideal grain growth behaviors correctly quantified by the present simulations.Our findings provide conclusive knowledge on ideal grain growth,establishing a platform for studying more realistic growth processes.展开更多
It was for me an unexpected,unhappy announcement,concerning the severe disease that the late Dr.Franz Oberwinkler had been diagnosed,sent from one of his former students in early February 2018.He suffered from a brain...It was for me an unexpected,unhappy announcement,concerning the severe disease that the late Dr.Franz Oberwinkler had been diagnosed,sent from one of his former students in early February 2018.He suffered from a brain tumor and passed away at home very suddenly,surrounded by his beloved family(Fig.1).展开更多
In this paper,we present solutions for the one-dimensional coupled nonlinear Schrödinger(CNLS)equations by the Constrained Interpolation Profile-Basis Set(CIP-BS)method.This method uses a simple polynomial basis ...In this paper,we present solutions for the one-dimensional coupled nonlinear Schrödinger(CNLS)equations by the Constrained Interpolation Profile-Basis Set(CIP-BS)method.This method uses a simple polynomial basis set,by which physical quantities are approximated with their values and derivatives associated with grid points.Nonlinear operations on functions are carried out in the framework of differential algebra.Then,by introducing scalar products and requiring the residue to be orthogonal to the basis,the linear and nonlinear partial differential equations are reduced to ordinary differential equations for values and spatial derivatives.The method gives stable,less diffusive,and accurate results for the CNLS equations.展开更多
文摘To investigate the effect of unsaturated aliphatic hydrocarbons on PAHs （polycyclic aromatic hydrocarbons） formation, numerical analysis using detailed reaction mechanism is performed. For the carbon black produced by benzene feedstock, three kinds of unsaturated aliphatic hydrocarbons （acetylene, diacetylene, and vinylacetylene） are added. The detailed reaction mechanism which is proposed by Wang and Frenklach is consisted by 527 reactions and 99 chemical species. The formations of PAHs and nuclei are promoted by unsaturated aliphatic hydrocarbons addition. There exits optimal benzene/acetylene ratio （XA/XB = 0.50）, benzene/diacetylene mixture ratio （XD/XB = 0.60）, benzene/vinyl-acetylene mixture ratio （XV/XB = 0.25）. The formation of nuclei is most promoted by acetylene addition, and the benzene/acetylene mixture ratio is 0.50.
文摘To better understand the fusion mechanism of heated carbon black, heat treatment is conducted for carbon black produced by benzene pyrolysis. The effects of （a） heating time, （b） heating temperature and （c） heating rate on the aggregate shape and mean primary particle diameter of the carbon black are investigated using TEM （transmission electron microscopy）. The mean primary particle diameter does not change significantly when carbon black is heat treated. For short heating times and low heating temperatures, the aggregate shapes become simple when compared with those of non-heated carbon black, and shapes become complex with an increase in the heating time. Also, for low heating rates, the aggregate shapes become significantly simple when compared with those of non-heated carbon black. The results of this study suggest that sintering between primary particles is promoted under relatively low heating temperatures, and Ostwald ripening among aggregates is promoted under relatively high heating temperatures.
基金supported by a Grant-in-Aid for Scientific Research(B)(No.16H04490)from the Japan Society for the Promotion of Science(JSPS)a Grant-in-Aid for Scientific Research(S)(No.26220002)from the Ministry of Education,Culture,Sports and Technology(MEXT),the Joint Usage/Research Center for Interdisciplinary Large-scale Information Infrastructures,the High Performance Computing Infrastructure in Japan.
文摘Grain growth,a competitive growth of crystal grains accompanied by curvature-driven boundary migration,is one of the most fundamental phenomena in the context of metallurgy and other scientific disciplines.However,the true picture of grain growth is still controversial,even for the simplest(or‘ideal’)case.This problem can be addressed only by large-scale numerical simulation.Here,we analyze ideal grain growth via ultra-large-scale phase-field simulations on a supercomputer for elucidating the corresponding authentic statistical behaviors.The performed simulations are more than ten times larger in time and space than the ones previously considered as the largest;this computational scale gives a strong indication of the achievement of true steady-state growth with statistically sufficient number of grains.Moreover,we provide a comprehensive theoretical description of ideal grain growth behaviors correctly quantified by the present simulations.Our findings provide conclusive knowledge on ideal grain growth,establishing a platform for studying more realistic growth processes.
文摘It was for me an unexpected,unhappy announcement,concerning the severe disease that the late Dr.Franz Oberwinkler had been diagnosed,sent from one of his former students in early February 2018.He suffered from a brain tumor and passed away at home very suddenly,surrounded by his beloved family(Fig.1).
文摘In this paper,we present solutions for the one-dimensional coupled nonlinear Schrödinger(CNLS)equations by the Constrained Interpolation Profile-Basis Set(CIP-BS)method.This method uses a simple polynomial basis set,by which physical quantities are approximated with their values and derivatives associated with grid points.Nonlinear operations on functions are carried out in the framework of differential algebra.Then,by introducing scalar products and requiring the residue to be orthogonal to the basis,the linear and nonlinear partial differential equations are reduced to ordinary differential equations for values and spatial derivatives.The method gives stable,less diffusive,and accurate results for the CNLS equations.
