In the actual microbial fermentation process,excessive or insufficient substrate can produce inhibitory effects on cells growth.The artificial substrate feeding rules by past experiences have great blindness to keep s...In the actual microbial fermentation process,excessive or insufficient substrate can produce inhibitory effects on cells growth.The artificial substrate feeding rules by past experiences have great blindness to keep substrate concentration in a given appropriate range.This paper considers that alkali feed depends on pH value of the solution and glycerol feed depends on glycerol concentration of the solution in the uncoupled microbial fed-hatch fermentation process,and establishes a state-dependent switched system in which the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times are prior unknown.To maximize the yield of target product 1,3-Propanediol(1,3-PD),we formulate a switching optimal control problem with the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times as decision variables,which is a mixed-integer dynamic programming problem.For solving the mixed-integer dynamic programming problem,the control parametrization technique,the time scaling transformation and the embedded system technology are used to obtain an approximate parameter optimization problem.By using a parallel optimization algorithm,we obtain the optimal control strategies.Under the obtained optimal control strategies,the 1,3-PD yield at the terminal time is increased significantly compared with the previous results.展开更多
The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,gre...The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,greater losses in the system and unstable dynamic behavior.To eliminate these drawbacks,this paper introduces a two-phase connection of step up converter with uncoupled smoothing reactors.Detailed analysis,simulation and control strategy have been proposed in this paper to investigate the advantages of using such connection with uncoupled reactors.This paper is intended to prove that two-phase connection with uncoupled reactors helps increasing the output power of the converter,minimizing its output ripple and making its control easier and more efficient.It also increases the converter chopping frequency and consequently decreases the size of smoothing reactors and filters used in the system.Concerning the design of such converters,it requires a long working period of time with a significant cost and specific technical tests at nominal operating points.Therefore,simulation can essentially decrease economic and development costs.Using modulation and simulation software techniques(Simplorer,Simulink,and Matlab)throughout this paper helped simulation of very fast the converter behavior and accurate determination of its dynamic characteristics.Moreover,the paper deals with modulation of voltage control technique using Matlab and Simplorer,thus regulating the converter output current and voltage.Simulation results show that this control technique provides robust output current and voltage of step up converters and is more feasible for their chopper up conversion technique.展开更多
A new kind of problem for TVC vehicle spinning in the boost stage had been researched. The study of non-linear flying dynamics modeling and dynamic properties of TVC vehicles reveal dominant coupled factors that affec...A new kind of problem for TVC vehicle spinning in the boost stage had been researched. The study of non-linear flying dynamics modeling and dynamic properties of TVC vehicles reveal dominant coupled factors that affect the attitude stability and attitude precision of the pitch channel and yaw channel. The paper emphasizes the inertial delay coupled effects between vehicle＇s pitch servo system and yaw servo system, which have always been neglected. An uncoupled plan and control algorithm are put forward from the standpoint of engineering implementation to provide theoretical guidance and reference for further research on this complicated flying control.展开更多
基金This work is supported by the National Science Foundation of China(Grant Nos.11771008,11171050 and 11371164)the National Science Foundation for the Youth of China(Grant Nos.11201267,11301051,11301081 and 11401073)+3 种基金the Provincial Natural Science Foundation of Fujian(Grant No.2014J05001)the Fundamental Research Funds for Central Universities in China(Grant DUT15LK25)the China Scholorship Council(CSC,No.201506060121)Natural Science Foundation of Shandong Province,China(Grant No.ZR2017MA005).
文摘In the actual microbial fermentation process,excessive or insufficient substrate can produce inhibitory effects on cells growth.The artificial substrate feeding rules by past experiences have great blindness to keep substrate concentration in a given appropriate range.This paper considers that alkali feed depends on pH value of the solution and glycerol feed depends on glycerol concentration of the solution in the uncoupled microbial fed-hatch fermentation process,and establishes a state-dependent switched system in which the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times are prior unknown.To maximize the yield of target product 1,3-Propanediol(1,3-PD),we formulate a switching optimal control problem with the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times as decision variables,which is a mixed-integer dynamic programming problem.For solving the mixed-integer dynamic programming problem,the control parametrization technique,the time scaling transformation and the embedded system technology are used to obtain an approximate parameter optimization problem.By using a parallel optimization algorithm,we obtain the optimal control strategies.Under the obtained optimal control strategies,the 1,3-PD yield at the terminal time is increased significantly compared with the previous results.
文摘The basic configuration of step up converter usually used in photovoltaic solar systems to increase the DC voltage generated at their outputs suffers from some drawbacks just like high ripple in the output voltage,greater losses in the system and unstable dynamic behavior.To eliminate these drawbacks,this paper introduces a two-phase connection of step up converter with uncoupled smoothing reactors.Detailed analysis,simulation and control strategy have been proposed in this paper to investigate the advantages of using such connection with uncoupled reactors.This paper is intended to prove that two-phase connection with uncoupled reactors helps increasing the output power of the converter,minimizing its output ripple and making its control easier and more efficient.It also increases the converter chopping frequency and consequently decreases the size of smoothing reactors and filters used in the system.Concerning the design of such converters,it requires a long working period of time with a significant cost and specific technical tests at nominal operating points.Therefore,simulation can essentially decrease economic and development costs.Using modulation and simulation software techniques(Simplorer,Simulink,and Matlab)throughout this paper helped simulation of very fast the converter behavior and accurate determination of its dynamic characteristics.Moreover,the paper deals with modulation of voltage control technique using Matlab and Simplorer,thus regulating the converter output current and voltage.Simulation results show that this control technique provides robust output current and voltage of step up converters and is more feasible for their chopper up conversion technique.
文摘A new kind of problem for TVC vehicle spinning in the boost stage had been researched. The study of non-linear flying dynamics modeling and dynamic properties of TVC vehicles reveal dominant coupled factors that affect the attitude stability and attitude precision of the pitch channel and yaw channel. The paper emphasizes the inertial delay coupled effects between vehicle＇s pitch servo system and yaw servo system, which have always been neglected. An uncoupled plan and control algorithm are put forward from the standpoint of engineering implementation to provide theoretical guidance and reference for further research on this complicated flying control.
