In mine ventilation networks, the reasonable airflow distribution is very important for the production safety and economy. Three basic problems of the natural, full-controlled and semi-controlled splitting were review...In mine ventilation networks, the reasonable airflow distribution is very important for the production safety and economy. Three basic problems of the natural, full-controlled and semi-controlled splitting were reviewed in the paper. Aiming at the high difficulty semi-controlled splitting problem, the general nonlinear multi-objectives optimization mathematical model with constraints was established based on the theory of mine ventilation networks. A new algorithm, which combined the improved differential evaluation and the critical path method （CPM） based on the multivariable separate solution strategy, was put forward to search for the global optimal solution more efficiently. In each step of evolution, the feasible solutions of air quantity distribution are firstly produced by the improved differential evolu- tion algorithm, and then the optimal solutions of regulator pressure drop are obtained by the CPM. Through finite steps iterations, the optimal solution can be given. In this new algorithm, the population of feasible solutions were sorted and grouped for enhancing the global search ability and the individuals in general group were randomly initialized for keeping diversity. Meanwhile, the individual neighbor- hood in the fine group which may be closely to the optimal solutions were searched locally and slightly for achieving a balance between global searching and local searching, thus improving the convergence rate. The computer program was developed based on this method. Finally, the two ventilation networks with single-fan and multi-fans were solved. The results show that this algorithm has advantages of high effectiveness, fast convergence, good robustness and flexibility. This computer program could be used to solve lar^e-scale ~eneralized ventilation networks o^timization problem in the future.展开更多
The evolution of the nonlinear wave groups in deep water is investigated through laboratory measurements and numerical analysis.Laboratory experiments are conducted in deep-water wave tank,focusing on the characterist...The evolution of the nonlinear wave groups in deep water is investigated through laboratory measurements and numerical analysis.Laboratory experiments are conducted in deep-water wave tank,focusing on the characteristics of breaking waves arising from the evolved wave train.Some quantitative results are obtained for the significant breaking wave train,including the surface elevation time series,the local geometry,and the energy dissipation.A nonlinear model for the evolution of the wave groups in deep water is developed by adding eddy viscosity dissipation terms in the High Level Irrotational Green-Naghdi(HLIGN)equations.The results of the simulation are compared with the laboratory measurements,and good agreement is observed for the evolved wave train.展开更多
Fourier transform infrared spectroscopy(FTIR)and Carbon-13 nuclear magnetic resonance(^(13)C NMR)techniques were applied to establish the molecular models of anthracite combusted at 490℃ and 690℃(490-C and 690-C).Th...Fourier transform infrared spectroscopy(FTIR)and Carbon-13 nuclear magnetic resonance(^(13)C NMR)techniques were applied to establish the molecular models of anthracite combusted at 490℃ and 690℃(490-C and 690-C).The evolution laws of functional groups were investigated based on the constructed models and quantitative changes calculated by FTIR results.The content of aromatic groups kept decreasing before 500℃;-CH_(3)/-CH_(2)-showed a rising trend during combustion;and the content of oxygen functional groups kept declining before 400℃.The chemical formulas of 490-C and 690-C were C_(217)H_(106)O_(12)N_(2)S_(2) and C_(201)H_(59)O_(8)N_(3)S_(2),respectively.690-C model was more compact than that of original anthracite and 490-C due to the spilt of carbon skeleton and the shedding of aliphatic chains during combustion.Total sulfur content in anthracite showed a sudden rise at 690℃ which could be attributed to the generation of organic thiophene;one more pyrrole in 690-C model resulted from the conversion of pyridine at such high temperature.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51134023)
文摘In mine ventilation networks, the reasonable airflow distribution is very important for the production safety and economy. Three basic problems of the natural, full-controlled and semi-controlled splitting were reviewed in the paper. Aiming at the high difficulty semi-controlled splitting problem, the general nonlinear multi-objectives optimization mathematical model with constraints was established based on the theory of mine ventilation networks. A new algorithm, which combined the improved differential evaluation and the critical path method （CPM） based on the multivariable separate solution strategy, was put forward to search for the global optimal solution more efficiently. In each step of evolution, the feasible solutions of air quantity distribution are firstly produced by the improved differential evolu- tion algorithm, and then the optimal solutions of regulator pressure drop are obtained by the CPM. Through finite steps iterations, the optimal solution can be given. In this new algorithm, the population of feasible solutions were sorted and grouped for enhancing the global search ability and the individuals in general group were randomly initialized for keeping diversity. Meanwhile, the individual neighbor- hood in the fine group which may be closely to the optimal solutions were searched locally and slightly for achieving a balance between global searching and local searching, thus improving the convergence rate. The computer program was developed based on this method. Finally, the two ventilation networks with single-fan and multi-fans were solved. The results show that this algorithm has advantages of high effectiveness, fast convergence, good robustness and flexibility. This computer program could be used to solve lar^e-scale ~eneralized ventilation networks o^timization problem in the future.
基金Projects supported by the National Natural Science Foundation of China(Grant No.11772099)the Heilongjiang Touyan Innovation Team Program,China.
文摘The evolution of the nonlinear wave groups in deep water is investigated through laboratory measurements and numerical analysis.Laboratory experiments are conducted in deep-water wave tank,focusing on the characteristics of breaking waves arising from the evolved wave train.Some quantitative results are obtained for the significant breaking wave train,including the surface elevation time series,the local geometry,and the energy dissipation.A nonlinear model for the evolution of the wave groups in deep water is developed by adding eddy viscosity dissipation terms in the High Level Irrotational Green-Naghdi(HLIGN)equations.The results of the simulation are compared with the laboratory measurements,and good agreement is observed for the evolved wave train.
基金supported by Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(Grant No.2019-KF-13)。
文摘Fourier transform infrared spectroscopy(FTIR)and Carbon-13 nuclear magnetic resonance(^(13)C NMR)techniques were applied to establish the molecular models of anthracite combusted at 490℃ and 690℃(490-C and 690-C).The evolution laws of functional groups were investigated based on the constructed models and quantitative changes calculated by FTIR results.The content of aromatic groups kept decreasing before 500℃;-CH_(3)/-CH_(2)-showed a rising trend during combustion;and the content of oxygen functional groups kept declining before 400℃.The chemical formulas of 490-C and 690-C were C_(217)H_(106)O_(12)N_(2)S_(2) and C_(201)H_(59)O_(8)N_(3)S_(2),respectively.690-C model was more compact than that of original anthracite and 490-C due to the spilt of carbon skeleton and the shedding of aliphatic chains during combustion.Total sulfur content in anthracite showed a sudden rise at 690℃ which could be attributed to the generation of organic thiophene;one more pyrrole in 690-C model resulted from the conversion of pyridine at such high temperature.
