Transient Analysis and Motor Fault Detection using the Wavelet Transform

Peer ReviewedPostprint (updated version

Recycling of sludge from drinking water treatment as ceramic material for the manufacture of tiles

Currently, the main destination for sludge from Drinking Water Treatment Plants (DWTP) is its disposal in sanitary landfills. However, its chemical composition and physical properties make it suitable for use as a building material. In this work, the use of spray-dried DWTP sludge on the manufacture of cladding ceramic material for the production of tiles as an alternative to the final disposal of sludge is analysed. The work is based on an experimental study carried out on a laboratory scale. Clay and spray-dried DWTP sludge (average humidity of 3¿wt%) were mixed with different percentages of sludge (from 0 to 70¿wt%) to form a slurry to be extruded. Specimens were then fired up to 980¿°C. Chemical and mineralogical composition of raw materials was analysed. Technical properties of the ceramic samples were determined. The results obtained showed that the DWTP sludge became a powder with low organic content and a high-micronised calcareous content (14.4¿wt% calcium oxide). The ceramic samples had a high open porosity, which increases with the increase in sludge addition percentage. They also had a high dilatometric coefficient. Taking into account these two properties, a possible application of this material would be the manufacture of glazed tiles. The resulting ceramic material does not pose any environmental problem, far surpassing the NEN-7345 leaching test and accelerated degassing tests (outgassing PSS-01-702 and offgassing PSS-01-729 standards of the European Space Agency).Peer ReviewedPostprint (author's final draft

Identifying health status of wind turbines by using self organizing maps and interpretation-oriented post-processing tools

Identifying the health status of wind turbines becomes critical to reduce the impact of failures on generation costs (between 25–35%). This is a time-consuming task since a human expert has to explore turbines individually. Methods: To optimize this process, we present a strategy based on Self Organizing Maps, clustering and a further grouping of turbines based on the centroids of their SOM clusters, generating groups of turbines that have similar behavior for subsystem failure. The human expert can diagnose the wind farm health by the analysis of a small each group sample. By introducing post-processing tools like Class panel graphs and Traffic lights panels, the conceptualization of the clusters is enhanced, providing additional information of what kind of real scenarios the clusters point out contributing to a better diagnosis. Results: The proposed approach has been tested in real wind farms with different characteristics (number of wind turbines, manufacturers, power, type of sensors, ...) and compared with classical clustering. Conclusions: Experimental results show that the states healthy, unhealthy and intermediate have been detected. Besides, the operational modes identified for each wind turbine overcome those obtained with classical clustering techniques capturing the intrinsic stationarity of the data.Peer ReviewedPostprint (published version

Predicting hospital admissions to reduce crowding in the emergency departments

Having an increasing number of patients in the emergency department constitutes an obstacle to the admissions process and hinders the emergency department (ED)’s ability to deal with the continuously arriving demand for new admissions. In addition, forecasting is an important aid in many areas of hospital management, including elective surgery scheduling, bed management, and staff resourcing. Therefore, this paper aims to develop a precise prediction model for admissions in the Integral Healthcare System for Public Use in Catalonia. These models assist in reducing overcrowding in emergency rooms and improve the quality of care offered to patients. Data from 60 EDs were analyzed to determine the likelihood of hospital admission based on information readily available at the time of arrival in the ED. The first part of the study targeted the obtention of models with high accuracy and area under the curve (AUC), while the second part targeted the obtention of models with a sensitivity higher than 0.975 and analyzed the possible benefits that could come from the application of such models. From the 3,189,204 ED visits included in the study, 11.02% ended in admission to the hospital. The gradient boosting machine method was used to predict a binary outcome of either admission or discharge.This research was funded by Ministerio de Ciencia e Innovación Torres Quevedo grant number PTQ2021-012147.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarObjectius de Desenvolupament Sostenible::3 - Salut i Benestar::3.8 - Assolir la cobertura sanitària universal, en particular la protecció contra els riscos financers, l’accés a serveis de salut essencials de qualitat i l’accés a medicaments i vacunes segurs, eficaços, assequibles i de qualitat per a totes les personesPostprint (published version

EMA Fault Detection Using Fuzzy Inference Tools

Acoustic emission (AE) is one of the most important non-destructive testing (NDT) methods for materials, constructions and machines. Acoustic emission is defined as the transient elastic energy that is spontaneously released when materials undergo deformation, fracture, or both. This interdisciplinary book consists of 17 chapters, which widely discuss the most important applications of AE method as machinery and civil structures condition assessment, fatigue and fracture materials research, detection of material defects and deformations, diagnostics of cutting tools and machine cutting process, monitoring of stress and ageing in materials, research, chemical reactions and phase transitions research, and earthquake prediction.Peer ReviewedPostprint (published version

New mathematical model of an inverter-based generator for stability studies of microgrid Systems

A new mathematical model of a renewable generator, with a DC-AC interface, based on the concept of electrostatic machine is presented. This new model has a direct relationship between the DC and AC side. Moreover, it can be used for stability studies, taking into account the dynamics of the DC link and to find saturations and limits on the control signals.Peer ReviewedPostprint (author’s final draft

An mHealth intervention for the treatment of patients with an eating disorder: A multicenter randomized controlled trial

Objective: The current multicentre randomized controlled trial assessed the clinicalefficacy of a combined mHealth intervention for eating disorders (EDs) based on cog-nitive behavioral therapy (CBT).Method: A total of 106 ED patients from eight different public and private mentalhealth services in Spain were randomly assigned to two parallel groups. Patients ofthe experimental group (N = 53) received standard face-to-face CBT plus a mobileintervention through an application called “TCApp,” which provides self-monitoringand an online chat with the therapist. The control group (N = 53) received standard face-to-face CBT only. Patients completed self-report questionnaires on ED symp-tomatology, anxiety, depression, and quality of life, before and after treatment.Results: Significant reductions in primary and secondary outcomes were observedfor participants of both groups, with no differences between groups. Results alsosuggested that the frequency with which patients attended their referral mentalhealth institution after the intervention was lower for patients in the experimentalgroup than for those in the control group.Discussion: The current study showed that CBT can help to reduce symptoms relat-ing to ED, regardless of whether its delivery includes online components in additionto traditional face-to-face treatment. Besides, the additional component offered bythe TCApp does not appear to be promising from a purely therapeutic perspectivebut perhaps as a cost-effective tool, reducing thus the costs and time burden associ-ated with weekly visits to health professionals.The current study is part of a broader project titled “mHealth: Chal-lenges and opportunities for health systems” which receives funding from RecerCaixa of “La Caixa” Foundation.Peer ReviewedPostprint (author's final draft

80C537 Microcontroller remote lab for e-learning teaching

A remote microcontroller lab based on an 80C537 mock-up is presented. This paper presents a new way to interact with these kinds of systems via the Internet, giving the possibility for complete interaction. The Citrix Application Server is the platform which manages the debugging microcontroller software, and National Instruments LabVIEW 8 is used to develop the applications which allow the interaction between the system and the remote user. By means of LabVIEW web server, full remote interaction has been achieved. Our results suggest a new way to practise in laboratories without being present, yet retaining the feel of an actual laboratory environment.Postprint (published version

Closed-loop controller for eliminating the contact bounce in DC core contactors

The undesirable phenomenon of the contact bounce causes severe erosion of the contacts and, as a consequence, their electrical life and reliability are greatly reduced. On the other hand, the bounce of the armature can provoke re-opening of the contacts, even when they have already been closed. This paper deals with the elimination of the bounce in both contacts and armature of a commercial dc core contactor. This is achieved by means of a current closed-loop controller, which only uses as input the current and voltage of the contactor’s magnetizing coil. The logic control has been implemented in a low cost microcontroller. Moreover, the board control can be fed by either dc or ac, and either in 50 Hz or 60 Hz so as to extend its applicability. A set of data is obtained from the measurement of the position and velocity of the movable parts for different operating voltages, and the dynamic behavior of the contactor is discussed.Peer ReviewedPostprint (published version

Detection of Wind Turbine Failures through Cross-Information between Neighbouring Turbines

In this paper, the time variation of signals from several SCADA systems of geographically closed turbines are analysed and compared. When operating correctly, they show a clear pattern of joint variation. However, the presence of a failure in one of the turbines causes the signals from the faulty turbine to decouple from the pattern. From this information, SCADA data is used to determine, firstly, how to derive reference signals describing this pattern and, secondly, to compare the evolution of different turbines with respect to this joint variation. This makes it possible to determine whether the behaviour of the assembly is correct, because they maintain the well-functioning patterns, or whether they are decoupled. The presented strategy is very effective and can provide important support for decision making in turbine maintenance and, in the near future, to improve the classification of signals for training supervised normality models. In addition to being a very effective system, it is a low computational cost strategy, which can add great value to the SCADA data systems present in wind farms.Peer ReviewedObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.a - Per a 2030, augmentar la cooperació internacional per tal de facilitar l’accés a la investigació i a les tecnolo­gies energètiques no contaminants, incloses les fonts d’energia renovables, l’eficiència energètica i les tecnologies de combustibles fòssils avançades i menys contaminants, i promoure la inversió en infraestructures energètiques i tecnologies d’energia no contaminantObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.b - Per a 2030, ampliar la infraestructura i millorar la tecnologia per tal d’oferir serveis d’energia moderns i sos­tenibles per a tots els països en desenvolupament, en particular els països menys avançats, els petits estats insulars en desenvolupament i els països en desenvolupament sense litoral, d’acord amb els programes de suport respectiusObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (published version