Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the ...Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.展开更多
Due to the difficulty of controlling the process with inverse response and dead time,a Multi-objective Optimization based on Genetic Algorithm (MOGA) method for tuning of proportional-integral-derivative (PID) control...Due to the difficulty of controlling the process with inverse response and dead time,a Multi-objective Optimization based on Genetic Algorithm (MOGA) method for tuning of proportional-integral-derivative (PID) controller is proposed. The settings of the controller are valued by two criteria,the error between output and reference signals and control moves. An appropriate set of Pareto optimal setting of the PID controller is founded by analyzing the results of Pareto optimal surfaces for balancing the two criteria. A high order process with inverse response and dead time is used to illustrate the results of the proposed method. And the efficiency and robustness of the tuning method are evident compared with methods in recent literature.展开更多
The ratio between the reactivity of HC and NOx, i.e., φ = ∑kOH＋HC, [HCi] / （kOH＋No[NO] ＋ kOH＋NO2 [NO2]）, is used to study the chemistry of HOx radicals （HOE and OH） in the marine boundary layer （MBL）. Data...The ratio between the reactivity of HC and NOx, i.e., φ = ∑kOH＋HC, [HCi] / （kOH＋No[NO] ＋ kOH＋NO2 [NO2]）, is used to study the chemistry of HOx radicals （HOE and OH） in the marine boundary layer （MBL）. Data analysis shows that HOx production and OH/HO2 ratio strongly depend on φ. The OH radical concentration presents an ascending tendency in low φ region but a de- clining one in high ∞ region, while HO2 radical increases with increasing φ under low φ conditions but appears to be nearly constant with the variation of ∞ under high φ conditions. The observed OH/HO2 ratio shows a continuous decrease with the increase of φ. Model studies are conducted to illuminate the behavior of HOx radicals in different φ regions, and the results represent general agreement with the observed variations of HOx radicals and can well explain the observed behavior of HOx radicals. This study demonstrates that φ could be used as an efficient parameter to ascertain the behavior of HOx radicals in the clean marine boundary layer.展开更多
文摘Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.
基金National Natural Science Foundation of China (No.60504033)
文摘Due to the difficulty of controlling the process with inverse response and dead time,a Multi-objective Optimization based on Genetic Algorithm (MOGA) method for tuning of proportional-integral-derivative (PID) controller is proposed. The settings of the controller are valued by two criteria,the error between output and reference signals and control moves. An appropriate set of Pareto optimal setting of the PID controller is founded by analyzing the results of Pareto optimal surfaces for balancing the two criteria. A high order process with inverse response and dead time is used to illustrate the results of the proposed method. And the efficiency and robustness of the tuning method are evident compared with methods in recent literature.
文摘The ratio between the reactivity of HC and NOx, i.e., φ = ∑kOH＋HC, [HCi] / （kOH＋No[NO] ＋ kOH＋NO2 [NO2]）, is used to study the chemistry of HOx radicals （HOE and OH） in the marine boundary layer （MBL）. Data analysis shows that HOx production and OH/HO2 ratio strongly depend on φ. The OH radical concentration presents an ascending tendency in low φ region but a de- clining one in high ∞ region, while HO2 radical increases with increasing φ under low φ conditions but appears to be nearly constant with the variation of ∞ under high φ conditions. The observed OH/HO2 ratio shows a continuous decrease with the increase of φ. Model studies are conducted to illuminate the behavior of HOx radicals in different φ regions, and the results represent general agreement with the observed variations of HOx radicals and can well explain the observed behavior of HOx radicals. This study demonstrates that φ could be used as an efficient parameter to ascertain the behavior of HOx radicals in the clean marine boundary layer.
