William A. Weigand

Computer Applications to Fermentation Processes

Publisher Summary This chapter discusses modeling, control, and parameter estimation for computer-coupled fermentors and, in particular, explores the area of fermentation optimization. The chapter presents, using the Purdue system as an example, a description of the important features of computer-coupled fermentors for use in academic and institutional environments, where usually more fundamental engineering questions are examined. The report by Dobry and Jost elaborated on the choices in design and system requirements of a computer-coupled fermentation system emphasizing features needed for industrial purposes. Similar feelings on this topic have been expressed by Jefferis. Also, much information on the efforts at standardizing the software and hardware interfaces for computer control can be found in the annual reports of workshops held by the Purdue Laboratory for Applied Industrial Control headed by T. J. Williams. The current system at Purdue was designed to permit considerable flexibility and accuracy with relative ease of operation.

Optimal output feedback control for systems with inaccessible state variables

Optimal linear control laws require the measurement of each and every state variable. However, in practice it is difficult to measure every state variable, and thus the optimal control is not widely accepted. This paper is concerned with overcoming this difficulty by considering the design of optimal linear regulator systems with some inaccessible state variables. Two methods leading to dynamic feedback control laws in terms of measurable output alone are developed. One of these methods is extended to time-varying problems.

Liapunov functional method for analysis of nonadiabatic tubular reactors with axial mixing and recycle

Abstract Sufficient conditions for stability of steady state are derived through Liapunovs direct method for a class of distributed-parameter systems and applied to nonadiabatic tubular reactors with axial mixing and recycle (NATRAMAR), for which previously only numerical results have been reported. Several sufficient conditions are presented in terms of system parameters and steady state profiles, system parameters and the exit conditions, or system parameters only. The last conditions involving system parameters only are very convenient since they do not require any solution of differential equations and are particularly useful since they show the manner in which the operating conditions of the reactor affect the stability of steady state.

Dose-effect curves and relative biophasic drug levels: Elucidation of these concepts and the illustration of their use for the determination of bioavailability, rate of absorption, and time course of pharmacological response

The theoretical basis for the development of dose-effect curves, linear dynamic models, and relative biophasic drug levels as derived from pharmacological response intensity is presented. The presentation is kept sufficiently rigorous to demonstrate the theoretical soundness of the concepts, yet each concept is clearly explained and related to physical experimental variables so as to be physically meaningful. The use of these concepts for the determination of bioavailability, rate of absorption, and time course of drug action is demonstrated.

Sufficient conditions for uniqueness and local asymptotic stability for a class of distributed parameter systems: non-adiabatic plug-flow tubular reactors with recycle and feedback control

An analysis of the stability of a non-adiabatic tubular reactor with feedback control, modelled by a plug-flow reactor in which axial dispersion of heat and mass is accounted for by recycle, is presented, A sufficient condition for local stability is developed in terms of system parameters and steady-state profiles. This condition is extended to a condition which is in terms of system parameters and outlet temperature only. Also, a unique stable steady-state criterion, which is in terms of system parameters only, is obtained. These conditions show that under certain assumptions the stability can always be proved for a suitable choice of controller settings.