Ventilation system for drying out buildings after a flood: Influence of the air change rate on the drying process

It is currently considered that climate change caused by the intensification of the greenhouse effect will worsen extreme weather events such as floods. Indeed, floods are extreme weather events that are at risk of occurring more often and with greater intensity in the coming decades.

For historical reasons, particularly easier access to water supply, some of Portugal's most striking buildings were built near waterways and on floodplains and are therefore much more likely to suffer flooding. The occurrence of a flood can suddenly increase the moisture content in various building elements, which causes damage. It is very important that the moisture level of the walls is reduced as quickly as possible after a flood has occurred.

This article presents the results of a numerical analysis undertaken in a collaborative project involving the Institute for Research and Technological Development in Construction Sciences (ITeCons) and the Civil Engineering Department of the Faculty of Science and Technology of Coimbra University. The main objective was to perform a numerical simulation to validate the efficiency of a wall-base ventilation system as a technique to improve the drying out of walls of historical buildings after a flood. In this article we present the results of the latest investigations that have been carried out on the influence of the air change rate in the ventilation channels on the drying process.     

Ventilation system for drying out buildings after a flood: Influence of the building material

Portugal’s most striking buildings were usually built near waterways and on floodplains due to easier access to water supply. This proximity, besides causing an increased probability of pathologies due to rising damp also brings a higher exposure to the risk of flooding. After the occurrence of a flood, all building elements below the flood water level will remain with high water contents, with all the negative consequences that this fact can cause, namely, the degradation of the materials. Therefore, it is very important to promote the fast drying of these building elements to prevent worse consequences, either structural, safety, or heritage conservation. In a recent investigation undertaken under a collaboration project involving the University of Coimbra and University of Porto, an innovative treatment system to combat rising damp in historical buildings was developed: the wall-base ventilation system. Currently, investigations have focused on analyzing the technical feasibility of adapting this system for drying out walls of historical buildings after floods.     

A self-tuning control method for Wiener nonlinear systems and its application to process control problems

Many chemical processes can be modeled as Wiener models, which consist of a linear dynamic subsystem follow-ed by a static nonlinear block. In this paper, an effective discrete-time adaptive control method is proposed for Wiener nonlinear systems with uncertainties. The parameterization model is derived based on the inverse of the nonlinear function block. The adaptive control method is motivated by self-tuning control and is derived from a modified Clarke criterion function, which considers both tracking properties and control efforts. The un-certain parameters are updated by a recursive least squares algorithm and the control law exhibits an explicit form. The closed-loop system stability properties are discussed. To demonstrate the effectiveness of the obtained results, two groups of simulation examples including an application to composition control in a continuously stirred tank reactor (CSTR) system are studied.