一类基因调控批式流加发酵的时滞切换系统多目标优化

Multi-Objective Optimization of Switched Time-Delay System in a Class of Fed-Batch Fermentation Based on Genetic Regulation

针对一类非耦联批式流加发酵生产1,3-丙二醇(1,3-PD)问题,综合考虑反应过程中存在的时间延迟及dha调节子的调控作用,得到了一个含细胞内外要素及调节子等各物质浓度变化的非线性时滞切换系统.为最大化1,3-PD产量的同时提高甘油的转化率,以甘油和碱的流加速率、切换时刻为决策变量,建立了包含时滞切换系统和状态不等式约束的多目标优化模型.利用Normal Constraint(NC)方法,将多目标优化转化为一系列单目标优化问题,讨论了含多个时滞量的梯度计算公式,构造了基于序列二次规划方法的数值优化算法(MPA-SQP).通过大规模优化计算.得到了有参考价值的Pareto解.

For an uncoupled microbial fed-batch fermentation process of glycerol to1,3-propanediol(1,3-PD),considering that the time delay in reaction process and the regulation of dha regulator,a nonlinear time-delay switched system model is established dominating the change of concentrations with comprehensive factors that both the intracellular and extracellular environments and regulators are involved.In order to maximize the yield of 1,3-PD and increase the conversion rate of glycerol at the same time,taking the switching time and the feeding rates of glycerol and alkali as decision variables,we present a multi-objective optimization problem involving the time-delay system and continuous state inequality constraints.For this multi-objective optimization problem,we convert it into a sequence of single-objective optimization problems by using the normal constraint method(NC).The formulas of gradient involving multiple delays are discussed.An algorithm based on sequential quadratic programming method(MPA-SQP)is described.Using the above algorithm,the valuable Pareto solutions are obtained by the large scale optimization calculations.