A symbolic approach to nonlinearly perturbed heat equation

We consider a system described by the linear heat equation with adiabatic boundary conditions which is perturbed periodicaly. This perturbation is nonlinear and is characterized by a one-parameter family of quadratic maps. The system, depending on the parameters, presents very complex behaviour. We introduce a symbolic framework to analyze the system and resume its most important features.

Knightly Masculinity, Court Games and Material Culture in Late Medieval Portugal: The case of Constable Afonso (c. 1480–1504)

This article explores the ways in which gender was used in order to transform an exiled and uneducated illegitimate child into a prince. Our study revolves around a member of the royal family, Afonso (c.1480–1504), who was brought up in hiding by peasants and who later, as a teenager, was reincorporated into the court. We argue that the keys to this process of rehabilitation were, on one hand, family politics centred around different configurations and on the other, his introduction into a court environment marked by the ideals of chivalry. Within this dynamic, material culture played a key role, because it gave the prince all the visual attributes of his new status, as well as allowing him the means to create a new self. We shall briefly introduce Afonso and his family context in order to give an insight into his life within changing political and dynastic contexts. Then, we will analyse the expression of manhood in the Portuguese court, using the spectacles at the court as a basis for observation, thus relating gender to material culture in a courtly environment.

On The Use of Genetic Algorithms for Parameter Identification in Anaerobic Digestion Modelling

Anaerobic digestion (AD) of wastewater is a very interesting option for waste valorization, energy production and environment protection. It is a complex, naturally occurring process that can take place inside bioreactors. The capability of predicting the operation of such bioreactors is important to optimize the design and the operation conditions of the reactors, which, in part, justifies the numerous AD models presently available. The existing AD models are not universal, have to be inferred from prior knowledge and rely on existing experimental data. Among the tasks involved in the process of developing a dynamical model for AD, the estimation of parameters is one of the most challenging. This paper presents the identifiability analysis of a nonlinear dynamical model for a batch reactor. Particular attention is given to the structural identifiability of the model, which considers the uniqueness of the estimated parameters. To perform this analysis, the GenSSI toolbox was used. The estimation of the model parameters is achieved with genetic algorithms (GA) which have already been used in the context of AD modelling, although not commonly. The paper discusses its advantages and disadvantages.