Multiway partial least square (MPLS) to estimate impact localization in structures

This paper presents results from the application of Multiway Partial Least Square (MPLS) as a regressor tool in order to estimate the localization of impacts in an aircraft structure. MPLS is a technique that maximizes the covariance between the predictor matrix X and the predicted matrix Y for each component of the space. The structure can be considered as a small scale version of part of a wing aircraft. 574 experiments were performed impacting the wing over its surface and receiving vibration signals from nine sensors. Experiments are divided in four groups depending on their localization and probability of occurrence. A PLS model is build using three of these groups and tested using the remaining group. Results are presented, discussed and compared with results of other methods.Postprint (published version

Optimization systems developed to improve the yield on tungsten and tantalum extraction and reduce associated costs – the EU HORIZON 2020 Optimore project (grant no. 642201)

Peer ReviewedPostprint (published version

Case-based diagnosis of batch processes based on latent structures

The aim of this thesis is to present a methodological approach for the automatic monitoring of batch processes based on a combination of statistical models and machine learning methods. The former is used to model the process based on the relationships among the different monitored variables throughout time, while the latter is used to improve the diagnosis capabilities of the system. Statistical methods do not relate faulty observations with its root cause (they only list the subset of variables whose behaviour has been altered) and they lack of learning capabilities. By using case-based reasoning (CBR) for the diagnosis, faulty observations can be associated with more significant information (like causes). Statistical models also provide a new representation of the observations, on an orthogonal basis, that improves the use of the distance-based approaches of the CBR, giving a better performanceL'objectiu d'aquesta tesi és la de presentar un mètode automàtic per al monitoratge dels processos per lots basat en la combinació de models estadístics i mètodes d'aprenentatge automàtic. El primer s'utilitza per modelar el procés mitjançant les relacions més significatives entre les variables mesurades al llarg del temps, mentre que el segon s'utilitza per millorar la capacitat de diagnosi del sistema. Els mètodes estadístics no relacionen una observació amb falla amb l'origen d'aquesta al mateix temps que no tenen capacitat d'aprenentatge. El fet d'utilitzar raonament basat en casos per a la diagnosi permet relacionar les observacions amb falla amb informació més significativa (com seria la causa de la falla). Els models estadístics també proporcionen una nova representació de les observacions, en una base ortogonal, que facilita l'aplicabilitat dels mètodes basats en distàncies del raonament basat en casos, tot millorant-ne els resultats obtingut

Diagnosi basada en models tenint en compte els retards en xarxes de comunicació

Els mètodes de detecció, diagnosi i aïllament de fallades (Fault Detection and Isolation - FDI) basats en la redundància analítica (és a dir, la comparació del comportament actual del procés amb l’esperat, obtingut mitjançant un model matemàtic del mateix), són àmpliament utilitzats per al diagnòstic de sistemes quan el model matemàtic està disponible. S’ha implementat un algoritme per implementar aquesta redundància analítica a partir del model de la plana conegut com a Anàlisi Estructura

Multiway partial least square (MPLS) to estimate impact localization in structures

This paper presents results from the application of Multiway Partial Least Square (MPLS) as a regressor tool in order to estimate the localization of impacts in an aircraft structure. MPLS is a technique that maximizes the covariance between the predictor matrix X and the predicted matrix Y for each component of the space. The structure can be considered as a small scale version of part of a wing aircraft. 574 experiments were performed impacting the wing over its surface and receiving vibration signals from nine sensors. Experiments are divided in four groups depending on their localization and probability of occurrence. A PLS model is build using three of these groups and tested using the remaining group. Results are presented, discussed and compared with results of other methods

Multiway partial least square (MPLS) to estimate impact localization in structures

This paper presents results from the application of Multiway Partial Least Square (MPLS) as a regressor tool in order to estimate the localization of impacts in an aircraft structure. MPLS is a technique that maximizes the covariance between the predictor matrix X and the predicted matrix Y for each component of the space. The structure can be considered as a small scale version of part of a wing aircraft. 574 experiments were performed impacting the wing over its surface and receiving vibration signals from nine sensors. Experiments are divided in four groups depending on their localization and probability of occurrence. A PLS model is build using three of these groups and tested using the remaining group. Results are presented, discussed and compared with results of other methods

Granularity determination of activated sludge through on-line profiles by means of case-based reasoning

Aerobic granulation from floccular sludge is difficult to detect in first stages with the naked eye. This work proposes a combination of multi-way principal components and case-based reasoning to predict the granulation state of a sequencing batch reactor, based solely on the on-line registered profiles of common sensors (i.e. pH, dissolved oxygen and oxidation-reduction potential). The methodology is able to discriminate between two active sludge granularities (floccular and granular). Two different scenarios are presented: one in which both granularities are present, and another scenario for which the granular state is not initially available. Analysis reported pH as the key variable in the transition between both states according to its variation, and that, in general, the granularity of the process can be correctly predicted at the end of the anaerobic phase. This methodology improves process monitoring capabilities during granulation and is an on-line alternative to a microscope analysis before the batch release

Classification of sags according to their origin based on the waveform similarity

A statistical method for classification of sags their origin downstream or upstream from the recording point is proposed in this work. The goal is to obtain a statistical model using the sag waveforms useful to characterise one type of sags and to discriminate them from the other type. This model is built on the basis of multi-way principal component analysis an later used to project the available registers in a new space with lower dimension. Thus, a case base of diagnosed sags is built in the projection space. Finally classification is done by comparing new sags against the existing in the case base. Similarity is defined in the projection space using a combination of distances to recover the nearest neighbours to the new sag. Finally the method assigns the origin of the new sag according to the origin of their neighbour