Machine Learning in Tribology

Tribology has been and continues to be one of the most relevant fields, being present in almost all aspects of our lives. The understanding of tribology provides us with solutions for future technical challenges. At the root of all advances made so far are multitudes of precise experiments and an increasing number of advanced computer simulations across different scales and multiple physical disciplines. Based upon this sound and data-rich foundation, advanced data handling, analysis and learning methods can be developed and employed to expand existing knowledge. Therefore, modern machine learning (ML) or artificial intelligence (AI) methods provide opportunities to explore the complex processes in tribological systems and to classify or quantify their behavior in an efficient or even real-time way. Thus, their potential also goes beyond purely academic aspects into actual industrial applications. To help pave the way, this article collection aimed to present the latest research on ML or AI approaches for solving tribology-related issues generating true added value beyond just buzzwords. In this sense, this Special Issue can support researchers in identifying initial selections and best practice solutions for ML in tribology

Application of LF-NMR measurements and supervised learning regression methods for improved characterization of heavy oils and bitumens

This work studies the physicochemical properties of unconventional hydrocarbon resources such as heavy oils and bitumens. The principal methods used in the research consisted of LF-NMR experiments, hypothesis testing, and statistical and data-driven modeling. The research output consists of several machine learning and analytical models capable of predicting heavy oil and bitumen viscosity and core sample water saturation with high accuracy. These results provide a strong case for in-situ LF-NMR applications in well logging

A novel bearing multi-fault diagnosis approach based on weighted permutation entropy and an improved SVM ensemble classifier

Timely and accurate state detection and fault diagnosis of rolling element bearings are very critical to ensuring the reliability of rotating machinery. This paper proposes a novel method of rolling bearing fault diagnosis based on a combination of ensemble empirical mode decomposition (EEMD), weighted permutation entropy (WPE) and an improved support vector machine (SVM) ensemble classifier. A hybrid voting (HV) strategy that combines SVM-based classifiers and cloud similarity measurement (CSM) was employed to improve the classification accuracy. First, the WPE value of the bearing vibration signal was calculated to detect the fault. Secondly, if a bearing fault occurred, the vibration signal was decomposed into a set of intrinsic mode functions (IMFs) by EEMD. The WPE values of the first several IMFs were calculated to form the fault feature vectors. Then, the SVM ensemble classifier was composed of binary SVM and the HV strategy to identify the bearing multi-fault types. Finally, the proposed model was fully evaluated by experiments and comparative studies. The results demonstrate that the proposed method can effectively detect bearing faults and maintain a high accuracy rate of fault recognition when a small number of training samples are available

Particles, air quality, policy and health

The diversity of ambient particle size and chemical composition considerably complicates pinpointing the specific causal associations between exposure to particles and adverse human health effects, the contribution of different sources to ambient particles at different locations, and the consequent formulation of policy action to most cost-effectively reduce harm caused by airborne particles. Nevertheless, the coupling of increasingly sophisticated measurements and models of particle composition and epidemiology continue to demonstrate associations between particle components and sources (and at lower concentrations) and a wide range of adverse health outcomes. This article reviews the current approaches to source apportionment of ambient particles and the latest evidence for their health effects, and describes the current metrics, policies and legislation for the protection of public health from ambient particles. A particular focus is placed on particles in the ultrafine fraction. The review concludes with an extended evaluation of emerging challenges and future requirements in methods, metrics and policy for understanding and abating adverse health outcomes from ambient particles

Optimización de procesos industriales con técnicas de Minería de Datos: mantenimiento de aerogeneradores y fabricación con tecnologías láser

En este trabajo se emplean técnicas de Minería de Datos para mejorar la eficiencia de dos procesos industriales: el diagnóstico de fallos en aerogeneradores y la fabricación de piezas metálicas de geometría compleja mediante tecnologías láser. Se mejora la validación experimental de estudios anteriores, en los que no se usó validación cruzada ni se tuvieron en cuenta algunas particularidades de los problemas analizados. Para el diagnóstico de fallos en aerogeneradores, se identifica la técnica de clasificación más adecuada para relacionar medidas de vibraciones con el tipo de fallo. Además, se define la métrica más adecuada para evaluar su precisión. Para la fabricación de piezas metálicas de geometría compleja, se estima la técnica de clasificación más adecuada para predecir la calidad superficial obtenida con pulido superficial láser, así como la técnica de regresión para predecir los errores en los distintos requerimientos geométricos de piezas obtenidas mediante microfresado 3D láser.Ministerio de Economía y Competitividad, proyecto TIN-2011-24046

Use of advanced analytics for health estimation and failure prediction in wind turbines

Tesi en modalitat de tesi per compendiThe energy sector has undergone drastic changes and critical revolutions in the last few decades. Renewable energy sources have grown significantly, now representing a sizeable share of the energy production mix. Wind energy has seen increasing rate of adoptions, being one of the more convenient and sustainable mean of producing energy. Research and innovation have helped greatly in driving down production and operation costs of wind energy, yet important challenges still remain open. This thesis addresses predictive maintenance and monitoring of wind turbines, aiming to present predictive frameworks designed with the necessities of the industry in mind. More concretely: interpretability, scalability, modularity and reliability of the predictions are the objectives —together with limited data requirements— of this project. Of all the available data at the disposal of wind turbine operators, SCADA is the principal source of information utilized in this research, due to its wide availability and low cost. Ensemble models played an important role in the development of the presented predictive frameworks thanks to their modular nature which allows to combine very diverse algorithms and data types. Important insights gained from these experiments are the beneficial effect of combining multiple and diverse sources of data —for example SCADA and alarms logs—, the easiness of combining different algorithms and indicators, and the noticeable gain in predicting performance that it can provide. Finally, given the central role that SCADA data plays in this thesis, but also in the wind energy industry, a detailed analysis of the limitations and shortcomings of SCADA data is presented. In particular, the ef- fect of data aggregation —a common practice in the wind industry— is determined developing a methodological framework that has been used to study high–frequency SCADA data. This lead to the conclusion that typical aggregation periods, i.e. 5–10 minutes that are the standard in wind energy industry are not able to capture and maintain the information content of fast–changing signals, such as wind and electrical measurements.El sector energètic ha experimentat importants canvis i revolucions en les últimes dècades. Les fonts d’energia renovables han crescut significativament, i ara representen una part important en el conjunt de generació. L’energia eòlica ha augmentat significativament, convertint-se en una de les millors alternatives per produir energia verda. La recerca i la innovació ha ajudat a reduir considerablement els costos de producció i operació de l’energia eòlica, però encara hi ha oberts reptes importants. Aquesta tesi aborda el manteniment predictiu i el seguiment d’aerogeneradors, amb l’objectiu de presentar solucions d’algoritmes de predicció dissenyats tenint en compte les necessitats de la indústria. Més concretament conceptes com, la interpretabilitat, escalabilitat, modularitat i fiabilitat de les prediccions ho són els objectius, juntament amb els requisits limitats per les de dades disponibles d’aquest projecte. De totes les dades disponibles a disposició dels operadors d’aerogeneradors, les dades del sistema SCADA són la principal font d’informació utilitzada en aquest projecte, per la seva àmplia disponibilitat i baix cost. En el present treball, els models de conjunt tenen un paper important en el desenvolupament dels marcs predictius presentats gràcies al seu caràcter modular que permet l’ús d’algoritmes i tipus de dades molt diversos. Resultats importants obtinguts d’aquests experiments són l’efecte beneficiós de combinar múltiples i diverses fonts de dades, per exemple, SCADA i dades d’alarmes, la facilitat de combinar diferents algorismes i indicadors i el notable guany en predir el rendiment que es pot oferir. Finalment, donat el paper central que SCADA l’anàlisi de dades juga en aquesta tesi, però també en la indústria de l’energia eòlica, una anàlisi detallada de la es presenten les limitacions i les mancances de les dades SCADA. En particular es va estudiar l’efecte de l’agregació de dades -una pràctica habitual en la indústria eòlica-. Dins d’aquest treball es proposa un marc metodològic que s’ha utilitzat per estudiar dades SCADA d’alta freqüència. Això va portar a la conclusió que els períodes d’agregació típics, de 5 a 10 minuts que són l’estàndard a la indústria de l’energia eòlica, no són capaços de capturar i mantenir el contingut d’informació de senyals que canvien ràpidament, com ara mesures eòliques i elèctriquesPostprint (published version

Technology 2002: the Third National Technology Transfer Conference and Exposition, Volume 1

The proceedings from the conference are presented. The topics covered include the following: computer technology, advanced manufacturing, materials science, biotechnology, and electronics

Maintenance Management of Wind Turbines

“Maintenance Management of Wind Turbines” considers the main concepts and the state-of-the-art, as well as advances and case studies on this topic. Maintenance is a critical variable in industry in order to reach competitiveness. It is the most important variable, together with operations, in the wind energy industry. Therefore, the correct management of corrective, predictive and preventive politics in any wind turbine is required. The content also considers original research works that focus on content that is complementary to other sub-disciplines, such as economics, finance, marketing, decision and risk analysis, engineering, etc., in the maintenance management of wind turbines. This book focuses on real case studies. These case studies concern topics such as failure detection and diagnosis, fault trees and subdisciplines (e.g., FMECA, FMEA, etc.) Most of them link these topics with financial, schedule, resources, downtimes, etc., in order to increase productivity, profitability, maintainability, reliability, safety, availability, and reduce costs and downtime, etc., in a wind turbine. Advances in mathematics, models, computational techniques, dynamic analysis, etc., are employed in analytics in maintenance management in this book. Finally, the book considers computational techniques, dynamic analysis, probabilistic methods, and mathematical optimization techniques that are expertly blended to support the analysis of multi-criteria decision-making problems with defined constraints and requirements

Fraud investigation in the extravirgin olive oil supply chain : Identification of vulnerable points and development of novel fraud detection methods

With the globalisation of the food supply system, food fraud can have international impacts, sometimes with far-reaching and lethal consequences. Extra virgin olive oil (EVOO) is considered one of the most frequently reported commodities, suffering from fraud. Knowledge about risk factors and precise laboratory and broad on-site screening methods will help to combat fraud in the EVOO supply chain network. The main objectives of this thesis are to develop strategies to combat fraud in the EVOO supply chains through knowledge about weak spots and underlying risk factors and the development of novel detection methods. To achieve these goals, firstly, the EVOO supply chain was assessed for their vulnerability using the SSAFE food fraud vulnerability assessment tool. These assessments indicate that the EVOO supply chain is fairly vulnerable. B2B companies and retailers in the EVOO supply chain are more vulnerable to fraud than olive oil producers and food manufacturers due to the additional vulnerability related to opportunities in time and place and a lack of control measures. Fraud vulnerability across the EVOO supply chain was not only determined by the place of the actor in the chain (node), but also by the scale and location of the companies. Four novel methods were developed in this thesis for EVOO authentication. Monochloropropanediol (MCPD) esters and glycidyl esters (GEs) analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS) was applied to defect EVOO adulteration with lower grade oils. The limit of fraud detection of lower grade olive oils in EVOO was 2% when using 3-MCPD esters, 5% for 2-MCPD esters and 13–14% for GEs. These results imply that the method is fairly useful for confirmatory analysis. However, 3-MCPD analysis by GC-MS/MS is currently a tedious and time-consuming method, it is not recommended to use this method to analyse a large number of suspect samples when a quick response is required. In addition, three rapid and non-destructive techniques were developed. The volatile organic compounds (VOCs) fingerprint analysis by proton transfer reaction-quadrupole ion guide time of flight-mass spectrometry in combination with multivariate statistics proved to be a promising screening methodology for the distinction of EVOO from its lower grade counterparts, as well as from other vegetable oils that are potential adulterants. In the one class classification evaluation, the k-nearest neighbours model presented the best results, which showed that more than 95% of oil samples were correctly predicted. For this most successful model, formic acid, dimethyl sulphide and hexenal are key compounds for the distinction of EVOO from the other oils. Except for the VOCs analysis, the spectral analysis by handheld near infrared spectroscopy combined with multivariate statistics also proved to be good methodology to discriminate EVOO from its lower grade counterparts. The EVOO samples were 100% correctly identified. Pomace olive oil (POO) was efficiently discriminated from EVOO, but 7% of the refined olive oil samples were predicted incorrectly. Furthermore, it was found that the relevant spectral information for the distinction of the oils strongly correlated with the degree of unsaturation of the oils as well as their levels of chlorophylls, carotenoids and moisture. In addition, a newly developed ultrasonic pulse echo system appeared to be a rapid and non-destructive method for the characterisation of vegetable oils. The ultrasonic velocity of EVOO differed significantly from those of POO and the oils of other botanical origin, but not from the velocity of refined olive oil. Furthermore, it was found that the underlying reason for the ultrasonic velocity differences between oils was the variation of the density and viscosity of the oils.  In conclusion, this study shows that the intermediaries between producers and consumers are more vulnerable to fraud due to the opportunities to commit fraud, as well as the greatest lack of adequate food fraud control measures. The results of this thesis also show that the newly developed methods cannot easily to be circumvented by fraudsters and they can be effectively applied for the distinction of EVOO from its lower grade counterparts and some vegetable oils. The insights in the weak spots in the EVOO supply chain network in combination with the newly developed fraud methods add to and reinforce the strategies to combat fraud in the EVOO supply chain. This all will help to ensure that consumers get what they are paying for and to fight unfair competition