In order to weaken the bias flow in the submerged entry nozzle （SEN） with slide- gate, the rotating magnetic field was imposed. The numerical method was employed to investigate the effect of rotating magnetic field ...In order to weaken the bias flow in the submerged entry nozzle （SEN） with slide- gate, the rotating magnetic field was imposed. The numerical method was employed to investigate the effect of rotating magnetic field on the flow field in the SEN and the mold under different slide-gate opening ratios. Numerical results showed that when the slide-gate opening ratio is smaller than 100%, the flow field in the SEN and the mold become asymmetry and there is an obvious circulation under the slide- gate in the SEN. With increasing exciting current, the divergent angle of liquid steel at the SEN outlet increases, the impact depth of liquid steel in the mold decreases. With increasing slide-gate opening ratio, the impact depth of liquid steel in the mold increases and the required exciting current to weaken the bias flow should increase.展开更多
A gate valve is one of the main elements of a circular pipeline, but the flow characteristics around the gate valve are hardly known. In this study, clarification of the flow field in front of the gate valve model in ...A gate valve is one of the main elements of a circular pipeline, but the flow characteristics around the gate valve are hardly known. In this study, clarification of the flow field in front of the gate valve model in a pipe flow via flow visualization and PIV analysis was attempted. As a result, four kinds of steady necklace-type vortex systems, 2-vortex, 4-vortex, 6-vortex and 8-vortex systems, were clearly observed in a Reynolds number between 290 and 2130. In addition, the main vortex was observed in the Reynolds number range between 2130 and 4870 with difficulty. On this account, both the center position and vorticity in the main vortex are presented against Reynolds number.展开更多
Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrica...Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrical distribution of flow and temperature field in mold consequently,formation of vortex near the nozzle and entrapment of CC powder into the molten steel.etc,which have negative effect on process productivity and product quality.To suppress the uneven flow,electromagnetic swirling flow has been proposed to impose on the flow in submerged entry nozzle below the sliding gate.In this study the uneven flow developed by incompletely open sliding gate and the suppression of this uneven flow using electromagnetic swirling flow are numerically studied in round billet continuous casting of steel process.The improvement of the flow and temperature filed in the submerged entry nozzle and mold are investigated.It is found that:The uneven velocity in nozzle can be suppressed by electromagnetic swirling flow,and the flow and temperature field in mold be improved obviously;With the increase of electromagnetic swirling intensity,the effect of uneven flow can be almost completely suppressed.展开更多
Accurate short-term traffic flow prediction plays a crucial role in intelligent transportation system (ITS), because it can assist both traffic authorities and individual travelers make better decisions. Previous rese...Accurate short-term traffic flow prediction plays a crucial role in intelligent transportation system (ITS), because it can assist both traffic authorities and individual travelers make better decisions. Previous researches mostly focus on shallow traffic prediction models, which performances were unsatisfying since short-term traffic flow exhibits the characteristics of high nonlinearity, complexity and chaos. Taking the spatial and temporal correlations into consideration, a new traffic flow prediction method is proposed with the basis on the road network topology and gated recurrent unit (GRU). This method can help researchers without professional traffic knowledge extracting generic traffic flow features effectively and efficiently. Experiments are conducted by using real traffic flow data collected from the Caltrans Performance Measurement System (PEMS) database in San Diego and Oakland from June 15, 2017 to September 27, 2017. The results demonstrate that our method outperforms other traditional approaches in terms of mean absolute percentage error (MAPE), symmetric mean absolute percentage error (SMAPE) and root mean square error (RMSE).展开更多
基金financially supported by the National High Technical Research and Development Programme of China (No. 2009AA03Z530)the National Natural Science Foundation of China and Shanghai Baosteel (No. 50834010)+3 种基金the National Natural Science Foundation of China (Nos. 51174058, 51104047 and 51004035)111 Project (No. B07015)the Fundamental Research Funds for the Central Universities(No. N100409007)the Doctor Startup Foundation of Liaoning Province (No.20111009)
文摘In order to weaken the bias flow in the submerged entry nozzle （SEN） with slide- gate, the rotating magnetic field was imposed. The numerical method was employed to investigate the effect of rotating magnetic field on the flow field in the SEN and the mold under different slide-gate opening ratios. Numerical results showed that when the slide-gate opening ratio is smaller than 100%, the flow field in the SEN and the mold become asymmetry and there is an obvious circulation under the slide- gate in the SEN. With increasing exciting current, the divergent angle of liquid steel at the SEN outlet increases, the impact depth of liquid steel in the mold decreases. With increasing slide-gate opening ratio, the impact depth of liquid steel in the mold increases and the required exciting current to weaken the bias flow should increase.
文摘A gate valve is one of the main elements of a circular pipeline, but the flow characteristics around the gate valve are hardly known. In this study, clarification of the flow field in front of the gate valve model in a pipe flow via flow visualization and PIV analysis was attempted. As a result, four kinds of steady necklace-type vortex systems, 2-vortex, 4-vortex, 6-vortex and 8-vortex systems, were clearly observed in a Reynolds number between 290 and 2130. In addition, the main vortex was observed in the Reynolds number range between 2130 and 4870 with difficulty. On this account, both the center position and vorticity in the main vortex are presented against Reynolds number.
基金Item Sponsored by The Central Universities(N100409010)Project for Key Laboratory of Liaoning Province(LS2010065)"111 project" of Northeastern University,China(B07015)
文摘Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrical distribution of flow and temperature field in mold consequently,formation of vortex near the nozzle and entrapment of CC powder into the molten steel.etc,which have negative effect on process productivity and product quality.To suppress the uneven flow,electromagnetic swirling flow has been proposed to impose on the flow in submerged entry nozzle below the sliding gate.In this study the uneven flow developed by incompletely open sliding gate and the suppression of this uneven flow using electromagnetic swirling flow are numerically studied in round billet continuous casting of steel process.The improvement of the flow and temperature filed in the submerged entry nozzle and mold are investigated.It is found that:The uneven velocity in nozzle can be suppressed by electromagnetic swirling flow,and the flow and temperature field in mold be improved obviously;With the increase of electromagnetic swirling intensity,the effect of uneven flow can be almost completely suppressed.
基金Supported by the Support Program of the National 12th Five Year-Plan of China(2015BAK25B03)
文摘Accurate short-term traffic flow prediction plays a crucial role in intelligent transportation system (ITS), because it can assist both traffic authorities and individual travelers make better decisions. Previous researches mostly focus on shallow traffic prediction models, which performances were unsatisfying since short-term traffic flow exhibits the characteristics of high nonlinearity, complexity and chaos. Taking the spatial and temporal correlations into consideration, a new traffic flow prediction method is proposed with the basis on the road network topology and gated recurrent unit (GRU). This method can help researchers without professional traffic knowledge extracting generic traffic flow features effectively and efficiently. Experiments are conducted by using real traffic flow data collected from the Caltrans Performance Measurement System (PEMS) database in San Diego and Oakland from June 15, 2017 to September 27, 2017. The results demonstrate that our method outperforms other traditional approaches in terms of mean absolute percentage error (MAPE), symmetric mean absolute percentage error (SMAPE) and root mean square error (RMSE).
