Study On The Non-steady Operation Of Bio-chemical Process Under Periodic Enforcement

Biological/chemical processes tend to exhibit high nonlinear characteristics.Unsteady operation utilizes this nonlinear dynamics to achieve process intensification.From a nonlinear analysis point of view,qualitative and quantitative studies of the enhanced effects of periodic operation on biological/chemical processes are performed.Periodic operations can be divided into internally self-oscillating processes and externally periodic forced processes.Both can be transformed into each other under certain conditions.Therefore,periodicity is discussed as a typical structure.The periodic structure of biological/chemical processes is a typical dissipative structural system.This makes classical thermodynamics,which is based on equilibrium state assumptions,ineffective in process description.Oscillation coupling may even produce chaotic behavior.In this dissertation,a kind of nonlinear transfer function(Laplace-Borel transform)is used to analyze the forced distabance of high-order nonlinear processes,and it is applied to biological fermentation analysis.In the analysis of the periodic operation of the process,the self-oscillatory behavior of the bioethanol fermentation process was studied.Then,the periodicity is used as a typical structure for theoretical exploration.The main research contents are as follows:(1)Using Laplace-Borel transform to study nonlinear processes analytically.The influence of the periodic perturbation of process parameters on the fermentation process of ethanol production was investigated and compared with the π-criterion.The study found that nonlinear analysis based on Laplace-Borel transformation can effectively predict highly nonlinear forced oscillation process.(2)The negative feedback effect of secondary metabolites during self-oscillating bio-fermentation results in spontaneous oscillations.The process of self-oscillation caused by Hopf bifurcation,the stability of self-oscillation and the elimination method for oscillations are studied.The theory and methods on computing out the self-oscillating trajectories are also studied.(3)Coupled oscillations can produce complex aperiodic state trajectories.The chaotic behavior caused by codimension-1 bifurcation such as period doubling or NS bifurcation is studied.Various process intensenfication methods by the coupling of internal self-oscillations and externally forced oscillatiory processes are investigated.(4)The necessary and sufficient conditions for the optimal periodic solution are studied through optimization theory and variational theory.The numerical methods for the optimal periodic solution are discussed:multi-variate shooting method,collocation method,and optimization method based on differential flatness.The optimal periodic control(OPC)method:extremeum-seeking method.Based on the viewpoint of process dynamic-inverse,the forced periodic operation is relevant to the internally self-oscillatory process,and the penicillin fermentation process is studied from the perspective of a periodic structure,in the hope of applying the optimal periodic solution of the drug delivery system.(5)The characteristics of periodic structures are studied.Analytical solution of the periodic structure and the chaotic behavior caused by the coupling of periodic structures are discussed.The periodic structure is discussed as a classic dissipative structure system,and its significance to thermodynamic theory,complex system theory and feedback system theory is marked.The significance of the chaotic behavior caused by periodic coupling is also marked.