B. Andres-Toro

Multiobjective optimization and multivariable control of the beer fermentation process with the use of evolutionary algorithms

This paper describes empirical research on the model, optimization and supervisory control of beer fermentation. Conditions in the laboratory were made as similar as possible to brewery industry conditions. Since mathematical models that consider realistic industrial conditions were not available, a new mathematical model design involving industrial conditions was first developed. Batch fermentations are multiobjective dynamic processes that must be guided along optimal paths to obtain good results. The paper describes a direct way to apply a Pareto set approach with multiobjective evolutionary algorithms (MOEAs). Successful finding of optimal ways to drive these processes were reported. Once obtained, the mathematical fermentation model was used to optimize the fermentation process by using an intelligent control based on certain rules.

Evolutionary path planner for UAVs in realistic environments

This paper presents a path planner for Unmanned Air Vehicles (UAVs) based on Evolutionary Algorithms (EA) that can be used in realistic risky scenarios. The path returned by the algorithm fulfills and optimizes multiple criteria which (1) are calculated based on properties of real UAVs, terrains, radars and missiles, and (2) are used to rank the solutions according to the priority levels and goals selected for each mission. Developed originally to work with only one UAV, the planner currently allows us to obtain the optimal path of several UAVs that are flying simultaneously. It works globally offline and locally online to recalculate a part of the path when an unexpected threat appears. Finally, the effectiveness of the solutions given by this planner has been successfully tested against a simulator that implements a complex model of the UAV and its environment.

Hybrid heuristic and mathematical programming in oil pipelines networks: Use of immigrants

We solve the problem of petroleum products distribution through oil pipelines networks. This problem is modelled and solved using two techniques: A heuristic method like a multiobjective evolutionary algorithm and Mathematical Programming. In the multiobjective evolutionary algorithm, several objective functions are defined to express the goals of the solutions as well as the preferences among them. Some constraints are included as hard objective functions and some are evaluated through a repairing function to avoid infeasible solutions. In the Mathematical Programming approach the multiobjective optimization is solved using the Constraint Method in Mixed Integer Linear Programming. Some constraints of the mathematical model are nonlinear, so they are linearized. The results obtained with both methods for one concrete network are presented. They are compared with a hybrid solution, where we use the results obtained by Mathematical Programming as the seed of the evolutionary algorithm.

Application of genetic algorithms and simulations for the optimization of batch fermentation control

Batch fermentations are dynamic processes that must be guided along convenient paths to obtain the desired results. Our research deals with the application of computers for advanced control of such processes. We selected beer fermentation, and started to investigate whether it is possible to optimize the process, taking as reference to be improved a real industrial fermentation. A good mathematical model is needed for that, and, as we refer to realistic industrial conditions, we had to develop a new one. Then we started optimization studies, exploring the adaptation of genetic algorithms for our problem. Good results are obtained, furnishing a promising ground for additional improvements. In this paper we describe the process, the new model, the optimization problem, and the solution by genetic algorithms.

Model Based Analysis of Seasickness Effects in a Fast Ferry

Abstract In a experimental research about increasing the comfort of a fast ferry, using moving flaps and a T-foil, mathematical models of heave and pitch motions of the ship have been determined. Besides this, knowledge about seasickness and waves has been gathered. This is important to determine good control of the actuators, to avoid or alleviate seasickness of passengers. However this is not all: it is also important to extract some criteria for the captain (manoeuvring), for ship designers and for actuators engineering. Taking advantage of the models obtained, a study of seasickness prediction has been done, and some interesting results have been obtained. Part of these results is also valuable as orientation for the control design. The general perspective of the paper, to tackle the evaluation problem, is an analogy with filters.

New results about model based study of seasickness in fast ferries

Abstract As part of a research on increasing the passengers comfort in fast ferries by using moving actuators, some study was devoted to the application of control-oriented models to predict seasickness. The key idea is to apply an analogy of three filters. In a previous paper, some criteria were presented concerning the captain, on how to avoid navigation parameters inducing seasickness, and also criteria were given for the ship designer. In this paper new results are presented, linking two seasickness indexes, and offering a frequency domain method to estimate the comfort of a ship from the beginning of the ship design.

First Principles Modelling Study for the Development of a 6 DOF Motions Model of a Fast Ferry

Abstract Proceeding along a research on the use of moving submerged appendages for motions smoothing of a fast ferry, now a 6 DOF motions model of the ship is needed for control studies, at least to be able to conduct experiments in a basin. During the first steps of the research, restricted to head seas, experience has been acquired about modelling heave and pitch motions. In addition, actuators such flaps and T-foil, have been modelled. Using the models of the ship motions and the actuators, a simulation environment has been developed for control design. After these results, the research faces now a more difficult challenge: to smooth the motions for every heading of the ship. The set of actuators increases with the addition of lateral fins. Experimental data are difficult to obtain: new experimental systems, involving the use of an autonomous scaled down replica of the ship, are under development. The source of data we have in this moment is a CFD program. The purpose of this paper is to combine physical reasoning and the CFD data, to develop the basis of a first 6 DOF motions model of the ship.

MULTIOBJECTIVE OPTIMIZATION OF DYNAMIC PROCESSES BY EVOLUTIONARY METHODS

Abstract The real-world optimisation of dynamic processes, such as batch processes, space applications and robotic problems, is usually a matter of several objectives and constraints. In many cases it is difficult to deal with such problems with conventional methods. Evolutionary methods provide an interesting alternative, with less programming and computational efforts. This paper presents four Evolutionary methods for solving complex multiobjective problems applied to an illustrative example: the optimisation and control of the industrial beer fermentation. The first method is based on aggregating functions, and the others adopt a Pareto set approach.

Advances in the 6 DOF motions model of a fast ferry

Abstract In the present stage of our research on the use of moving submerged appendages for motions smoothing of a fast ferry, a 6 DOF motions mathematical model of the ship for control studies is under development. This model is needed from the very beginning of the next experimental research, because we are going to use an autonomous scaled physical model of the ship, and we need to design a basic course control. The actuators for motion smoothing of the fast ferry are two transom flaps, two lateral fins and a T-foil. These actuators must be considered by the 6DOF model. In a previous paper we discussed a first principles approach to build the mathematical control-oriented model, using data from a CFD program. On the basis of these principles, now we present new developments of the 6DOF model. In particular, we study the ship dynamic behaviour for heading angles of 180°, 150° and 90°. Some hints are obtained to predict how the model will change for other heading angles.

APPLICATION OF AN OBJECT-ORIENTED EXPERT SYSTEM SHELL TO A FERMENTATION PROCESS

Abstract Our research deals with the intelligent supervision and control of batch fermentation processes. We built a pilot plant, with all the auxiliar electronics needed, for a MS-DOS computer to interact with the plant. We selected KAPPA-PC as the main platform to develop a real-time application. It is an object-oriented development environment, with the tools to define and manage class hierarchies including sets of rules, for intelligent functions. The shell works under MS-Windows, and is open to user-developed specific C code. After some experimental modelling, we determined models, and defined intelligent classes to simulate the plant, to control the process, and to supervise it, in real-time.