A new computer graphics approach to parameter space design of control systems

This paper presents a new approach to parameter space design of linear multivariable control systems. The complete solution of a pole region assignment problem for single-input systems is obtained as an admissible region in then-dimensional parameter space of state feedback gains. We develop a new modeling technique for these admissible parameter space regions which is superior to previous ones because it permits unambiguous and efficient graphical display of slices in 2D and 3D subspaces. In an interactive computer graphics implementation, this method provides an environment where the influence of stability, performance, robustness, integrity, and control constraints on design parameters can be directly visualized and complex tradeoffs are resolved in an interactive way. By judicious combination of overlays, color, and/ or animation, admissible ranges of up to five or six design parameters can be displayed simultaneously. A sequential decomposition technique which selects slices for full parameter space design of lower dimensional subsystems such that the remaining eigenvalues are invariant is used for systems of arbitrarily high order. Parameter space design of unity rank feedback for multiinput systems is done in exactly the same fashion, while systematic sequential design of full rank feedback is achieved as the sum of dyadic stages to which the single-input modeling techniques apply. Examples are given for all presented methods to show the flexibility and potential as a computer-aided control system design framework with a novel integration of computer graphics technology.     

Dynamische Prozeßsimulation in der industriellen Praxis

Dynamic process simulation in industrial practice. Dynamic process simulation is gaining in importance in process development and plant design. In addition to simulation tools for steady state calculations and optimization, recent years have seen increased development of software tools suitable for dynamic simulation. In particular, dynamic process models have been developed for various unit operations at universities and in industry. Application of the models includes synthesis and analysis of the control structure, start-up and shut down, safety assessments, optimization, and training. In addition, dynamic flowsheet programs analogous to the steady state programs were developed. Wider use of these program systems requires increased flexibility, solving procedures, user interfaces, model library, interfaces to external programs, etc. The present article is intended not only to describe the state of the art and describe some typical applications, but in particular to examine the demands placed on dynamic process simulation and the simulators and to delineate the current limitations of dynamic process simulation from an industrial viewpoint.     

Optimal operation of distillation processes under uncertain inflows accumulated in a feed tank

A new method of optimizing the operation of distillation processes with uncertain inflow streams from upstream plants is discussed. The case considered is the streams that will be first accumulated in a tank before feeding to the column. To minimize the total amount of operating energy while keeping a stable column operation under these inflows, a novel decomposed optimization strategy consisting of two steps was used. For an optimal planning of the dynamic operation, a smooth feed flow policy to the column is developed in the first step by stochastic optimization under chance constraints by ensuring a predefined probability of holding the tank level inside the desired range. An easy-to-use method developed computes the maximum reachable probability of holding the constraints so that a feasible solution of the chance constrained problem can be guaranteed. Since the uncertainty in the inflow stream variability is absorbed in the stochastic optimization over the tank, the operation of the dowstream distillation column is deterministic. Therefore, in the second step, the reflux and reboiler duty policies of the column are developed by deterministic dynamic optimization. The optimal overall strategy is obtained by the maximized smoothness of the feed flow to the distillation column. The approach is applied to a pilot column, and the developed operating policies are implemented on the real plant by experiment.     

Carborane-Containing Matrix Metalloprotease (MMP) Ligands as Candidates for Boron Neutron-Capture Therapy (BNCT)

Based on the previously reported potent and selective sulfone hydroxamate inhibitors SC-76276, SC-78080 (SD-2590), and SC-77964, potent MMP inhibitors have been designed and synthesized to append a boron-rich carborane cluster by employing click chemistry to target tumor cells that are known to upregulate gelatinases. Docking against MMP-2 suggests binding involving the hydroxamate zinc-binding group, key H-bonds by the sulfone moiety with the peptide backbone residues Leu82 and Leu83, and a hydrophobic interaction with the deep P1’ pocket. The more potent of the two triazole regioisomers exhibits an IC₅₀ of 3.7 nM versus MMP-2 and IC₅₀ of 46 nM versus MMP-9.     

Experimental and theoretical studies of the steady-state and dynamic behaviour of packed columns

Experimental studies were made with the help of laboratory-scale distillation column. Concentration and temperature profiles were obtained at the steady-state operating point, and transition behaviour was observed after specific changes were made to relevant process variables. These results were compared with results obtained by means of simulation calculations. The mathematical model is explained in detail, as is the study method employed. The aim of this study was to obtain experimental verification of steady-state and dynamic calculation methods. It was found that the simulation results agreed closely with those obtained experimentally. The experimental findings thus confirmed the accuracy of the model and its underlying assumptions.     

Design and analysis of a state observer for the temperature front of a retification column

In order to achieve optimal energy-saving, load-dependent operation of rectification columns, development and implementation of model-based control concepts are necessary. This paper reports on the design and step-by-step testing of a state observer for the estimation of two state variables which cannot be measured directly, namely the vapour rate and the location of mass transfer zone (temperature front) in the stripping section of a production column. The procedure is described, and the relevant simulation and operation results are presented and discussed. Initial experience, gained when the concept was put into practical operation, is reported.