The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was de...The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was determined by considering the maximum extrusion load and production efficiency.By taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was obtained.Results show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram displacement.As the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction increases.The exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment.展开更多
A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temper...A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus- tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central- ized model predictive control (MPC) technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre- sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro- duction rate while the setpoint tracking of the conventional proportional-integral (PI) controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari- ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceotable for both controlled variables.展开更多
The temporal and spatial growth behaviour of protein crystals, subject to different cooling strategies in protein crystallisation was investigated. Although the impact of temperature and cooling rate on crystal growth...The temporal and spatial growth behaviour of protein crystals, subject to different cooling strategies in protein crystallisation was investigated. Although the impact of temperature and cooling rate on crystal growth of small molecules was well documented, much less has been reported on their impact on the crystallisation of proteins. In this paper, an experimental set-up is configured to carry out such a study which involves an automatic temperature controlled hot-stage crystalliser fitted with a real-time imaging system. Linbro parallel crystallisation experiments(24-well plate) were also conducted to find the suitable initial conditions to be used in the hot-stage crystallisation experiments, including the initial concentration of HEW lysozyme solutions, precipitate concentration and pH value. It was observed that fast cooling rates at the early stage led to precipitates while slow cooling rates produced crystal nuclei, and very slow cooling rates, much smaller than for small molecules are critical to the growth of the nuclei and the crystals to a desired shape. The interesting results provide valuable insight as well as experimental proof of the feasibility and effectiveness of cooling as a means for achieving controlled protein crystallisation, compared with the evaporation approach which was widely used to grow single large crystals for X-ray diffraction study. Since cooling rate control can be easily achieved and has good repeatability, it suggests that large-scale production of protein crystals can be effectively achieved by manipulating cooling rates.展开更多
The purpose of this paper is to investigate the efficiency of the three way catalyst by testing the exhaust gases temperature difference (AT=Tinlet-Toutlet) at the inlet and outlet of the catalyst using different fu...The purpose of this paper is to investigate the efficiency of the three way catalyst by testing the exhaust gases temperature difference (AT=Tinlet-Toutlet) at the inlet and outlet of the catalyst using different fuel mixtures. The tests were carried out on a catalyst engine, under full load conditions, using as a fuel gasoline and ethanol mixtures. During the test the CO and HC emissions were measured in different engine speeds (1000, 2000 and 3000 rpm) and different fuel mixtures. The catalyst inlet (Ti) and outlet (To) temperatures were also monitored. It has been noticed that the use of ethanol as fuel results in the CO and HC decrease, with simultaneous temperature difference decrease (AT) at the catalyst when the engine function under full load conditions.展开更多
In rapid thermal processing of a semiconductor wafer, it is important to keep a given temperature rising speed of the wafer during the temperature rising process. We made an experimental apparatus to measure the tempe...In rapid thermal processing of a semiconductor wafer, it is important to keep a given temperature rising speed of the wafer during the temperature rising process. We made an experimental apparatus to measure the temperature rising speed of a ceramic ball of 2 mm in diameter heated with four halogen lamp heaters. The heating rate of the halogen lamp heaters was controlled by computer to keep a given temperature rising speed of 50 ℃/s with a controlling time interval of 0.1 s. We examined the effect of various heating control methods on the error of the temperature rising speed of the ceramic ball. We found that a combined method of control with prepared correlation and PID (proportional integral derivative) control is a good method to decrease the error of the temperature rising speed. The average error of the temperature rising speed is 0.5 ℃/s, and the repetition error is almost zero for the temperature rising speed of 50 ℃/s from 330 ℃ to 370 ℃. We also measured the effects of artificial control delay time and measuring error of the monitoring temperature on the error of the temperature rising speed.展开更多
基金the financial supports from the National Natural Science Foundation of China(No.52005244)the Scientific Research Fund of Hunan Provincial Education Department,China(Nos.18B285,18B552)+1 种基金the Natural Science Foundation of Hunan Provincial,China(Nos.2019JJ50510,2019JJ70077)Young Scholars Program of Furong Scholar Program,China.
文摘The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was determined by considering the maximum extrusion load and production efficiency.By taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was obtained.Results show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram displacement.As the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction increases.The exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment.
基金Supported by the Research Grants of the Research Council of Malaya
文摘A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus- tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central- ized model predictive control (MPC) technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre- sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro- duction rate while the setpoint tracking of the conventional proportional-integral (PI) controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari- ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceotable for both controlled variables.
基金Supported by the China One Thousand Talent Scheme,the National Natural Science Foundation of China under its Major Research Scheme of Meso-scale Mechanism and Control in Multi-phase Reaction Processes(91434126)the Natural Science Foundation of Guangdong Province(2014A030313228)+1 种基金benefited from early work funded by UK Engineering and Physical Science Research Council(EP/H008012/1EP/H008853/1)
文摘The temporal and spatial growth behaviour of protein crystals, subject to different cooling strategies in protein crystallisation was investigated. Although the impact of temperature and cooling rate on crystal growth of small molecules was well documented, much less has been reported on their impact on the crystallisation of proteins. In this paper, an experimental set-up is configured to carry out such a study which involves an automatic temperature controlled hot-stage crystalliser fitted with a real-time imaging system. Linbro parallel crystallisation experiments(24-well plate) were also conducted to find the suitable initial conditions to be used in the hot-stage crystallisation experiments, including the initial concentration of HEW lysozyme solutions, precipitate concentration and pH value. It was observed that fast cooling rates at the early stage led to precipitates while slow cooling rates produced crystal nuclei, and very slow cooling rates, much smaller than for small molecules are critical to the growth of the nuclei and the crystals to a desired shape. The interesting results provide valuable insight as well as experimental proof of the feasibility and effectiveness of cooling as a means for achieving controlled protein crystallisation, compared with the evaporation approach which was widely used to grow single large crystals for X-ray diffraction study. Since cooling rate control can be easily achieved and has good repeatability, it suggests that large-scale production of protein crystals can be effectively achieved by manipulating cooling rates.
文摘The purpose of this paper is to investigate the efficiency of the three way catalyst by testing the exhaust gases temperature difference (AT=Tinlet-Toutlet) at the inlet and outlet of the catalyst using different fuel mixtures. The tests were carried out on a catalyst engine, under full load conditions, using as a fuel gasoline and ethanol mixtures. During the test the CO and HC emissions were measured in different engine speeds (1000, 2000 and 3000 rpm) and different fuel mixtures. The catalyst inlet (Ti) and outlet (To) temperatures were also monitored. It has been noticed that the use of ethanol as fuel results in the CO and HC decrease, with simultaneous temperature difference decrease (AT) at the catalyst when the engine function under full load conditions.
文摘In rapid thermal processing of a semiconductor wafer, it is important to keep a given temperature rising speed of the wafer during the temperature rising process. We made an experimental apparatus to measure the temperature rising speed of a ceramic ball of 2 mm in diameter heated with four halogen lamp heaters. The heating rate of the halogen lamp heaters was controlled by computer to keep a given temperature rising speed of 50 ℃/s with a controlling time interval of 0.1 s. We examined the effect of various heating control methods on the error of the temperature rising speed of the ceramic ball. We found that a combined method of control with prepared correlation and PID (proportional integral derivative) control is a good method to decrease the error of the temperature rising speed. The average error of the temperature rising speed is 0.5 ℃/s, and the repetition error is almost zero for the temperature rising speed of 50 ℃/s from 330 ℃ to 370 ℃. We also measured the effects of artificial control delay time and measuring error of the monitoring temperature on the error of the temperature rising speed.