Publications de Grégory François

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In batch chemical processing, dynamic optimization is the method of choice to reduce production costs while satisfying safety constraints and product specifications. Most of the standard optimization techniques are based on a model of the process, while it ...

The contribution of this article is to propose and experimentally validate an optimizing control strategy for power kites flying crosswind. The control strategy provides both path control (stability) and path optimization (efficiency). The path following part of the controller is capable of robustly following a reference path, despite significant time delays, using position measurements only. The path-optimization part adjusts the reference path in order to maximize line tension. It uses a real-time optimiz

This paper considers the minimization of batch time for an industrial inverse-emulsion polymerization reactor in the presence of uncertainty. A first optimization study resulted in the current industrial practice of a semi-adiabatic profile (isothermal operation followed by an adiabatic one), where the switching time between the two modes of operation is updated to meet the terminal constraint on reactor temperature, as well as a constraint on residual raw material levels. However, such a procedure requires

This article presents a kite control and optimization problem intended as a benchmark problem for advanced control and optimization. We provide an entry point to this exciting renewable energy system for researchers in control and optimization methods look ...

The experimental validation of a real-time optimization (RTO) strategy for the optimal operation of a solid oxide fuel cell (SOFC) stack is reported in this paper. Unlike many existing studies, the RTO approach presented here utilizes the constraint-adapta ...

The problem of steering a dynamical system toward optimal steady-state performance is considered. For this purpose, a static optimization problem can be formulated and solved. However, because of uncertainty, the optimal steady-state inputs can rarely be a ...

Dynamic optimization can be used to determine optimal input profiles for dynamic processes. Due to plant-model mismatch and disturbances, the optimal inputs determined through model-based optimization will, in general, not be optimal for the plant. Modifie ...

A batch process is characterized by the repetition of time-varying operations of finite duration. Due to the repetition, there are two independent “time” variables, namely, the run time during a batch and the batch index. Accordingly, the control and optimization objectives can be defined for a given batch or over several batches. This chapter describes the various control and optimization strategies available for the operation of batch processes. These include online and run-to-run control on the one hand,

Real-Time Optimization (RTO) via modifier adaptation is a class of methods for which measurements are used to iteratively adapt the model via input-affine additive terms. The modifier terms correspond to the deviations between the measured and predicted co ...

In practice, the quest for the optimal operation of energy systems is complicated by the presence of operating constraints, which includes the need to produce the power required by the user, and by the need to account for uncertainty. The latter concept in ...

The subject of real-time, steady-state optimization under significant uncertainty is addressed in this paper. Specifically, the use of constraint-adaptation schemes is reviewed, and it is shown that, in general, such schemes cannot guarantee process feasib ...

The material presented in this document is intended as a comprehensive, implementation-oriented supplement to the experimental optimization framework presented in [Bunin, G.A., Francois, G., Bonvin, D.: Feasible-side global convergence in experimental optimization. SIAM J. Optim. (submitted) (2014)]. The issues of physical degradation, unknown Lipschitz constants, measurement/estimation noise, gradient estimation, sufficient excitation, and the handling of soft constraints and/or a numerical cost function a

Real-time optimization (RTO) is a class of methods that use measurements to reject the effect of uncertainty on optimal performance. This article compares six implicit RTO schemes, that is, schemes that implement optimality not through numerical optimizati ...

Type 1 Patients with Diabetes (Type 1 PwDs) have to frequently adjust their insulin dosage to keep their Blood Glucose concentration (BG) within normal bounds. Meal intakes represent the most important disturbance that has to be accounted for. Its effect d ...

With an annual worldwide production well in excess of 100 million metric tons, synthetic polymers constitute a significant part of the modern chemical process industry. Polymer reactors - operated in continuous, batch, or semibatch mode - are therefore important processing units, but there are unique problems associated with controlling them effectively. The most significant characteristics of polymer reactors that make them one of the most challenging units to model, control, and optimize, are discussed in

Real-time optimization (RTO) methods use measurements to offset the effect of uncertainty and drive the plant to optimality. Explicit RTO schemes, which are characterized by solving a static optimization problem repeatedly, typically require multiple itera ...

A gradient-descent method for the run-to-run tuning of MPC controllers is proposed. It is shown that, with an assumption on process repeatability, the MPC tuning parameters may be brought to a locally optimal set. SISO and MIMO examples illustrate the char ...

This paper presents an overview of the recent developments of modifier-adaptationschemes for real-time optimization of uncertain processes. These schemes have the ability to reach plant optimality upon convergence despite the presence of structural plant-m ...

Blood glucose concentrations of patients with type 1 diabetes mellitus are subject to very high inter- and intra-patient variability. This variability may be detrimental to the reliability of the treatment, thus resulting in potentially frequent hypo- or h ...

Grégory François

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Measurement-based run-to-run optimization of batch processes : application to industrial acrylamide copolymerization

Real-Time Optimizing Control of an Experimental Crosswind Power Kite

Trajectory Following for the Optimization of a Batch Polymerization Reactor

Crosswind Kite Control - A Benchmark Problem for Advanced Control and Dynamic Optimization

Experimental Real-Time Optimization of a Solid Oxide Fuel Cell Stack via Constraint Adaptation

Equivalence between Neighboring-Extremal Control and Self-Optimizing Control for the Steady-State Optimization of Dynamical Systems

Modifier Adaptation for Run-to-Run Optimization of Transient Processes

Control and Optimization of Batch Chemical Processes

Use of Convex Model Approximations for Real-Time Optimization via Modifier Adaptation

Application of Real-Time Optimization Methods to Energy Systems in the Presence of Uncertainties and Disturbances

Input Filter Design for Feasibility in Constraint-Adaptation Schemes

Implementation techniques for the SCFO experimental optimization framework

Comparison of Six Implicit Real-Time Optimization Schemes

Preclinically assessed optimal control of postprandial glucose excursions for type 1 patients with diabetes

Control of Polymerization Processes

Use of Transient Measurements for Real-Time Optimization via Modifier Adaptation

Run-to-Run MPC Tuning via Gradient Descent

Run-to-run Adaptation of a Semi-Adiabatic Policy for the Optimization of an Industrial Batch Polymerization Process

Modifier Adaptation for Real-Time Optimization -- Methods and Applications

Estimating reliability of blood glucose concentration predictions in patients with type 1 diabetes mellitus