Papers by Edgar Estupinan
Mathematics
This paper describes a comparison of three types of feature sets. The feature sets were intended ... more This paper describes a comparison of three types of feature sets. The feature sets were intended to classify 13 faults in a centrifugal pump (CP) and 17 valve faults in a reciprocating compressor (RC). The first set comprised 14 non-linear entropy-based features, the second comprised 15 information-based entropy features, and the third comprised 12 statistical features. The classification was performed using random forest (RF) models and support vector machines (SVM). The experimental work showed that the combination of information-based features with non-linear entropy-based features provides a statistically significant accuracy higher than the accuracy provided by the Statistical Features set. Results for classifying the 13 conditions in the CP using non-linear entropy features showed accuracies of up to 99.50%. The same feature set provided a classification accuracy of 97.50% for the classification of the 17 conditions in the RC.
World Tribology Conference IV, 2009
INVESTIGACION & DESARROLLO, 2018
El fin del superciclo de precios del cobre ha dejado de manifiesto el desafío de ser más riguroso... more El fin del superciclo de precios del cobre ha dejado de manifiesto el desafío de ser más rigurosos en el control de costos de producción en la industria minera, por lo cual se deben explorar nuevas estrategias que permitan contener y bajar los costos asociados a la gestión de activos físicos de mantenimiento. La División Ministro Hales de Codelco, se ha propuesto estar comparativamente en el primer cuartil de costos, lo que implica necesariamente dirigir esfuerzos en aquellos procesos que presentan baja disponibilidad y altos costos de mantenimiento, como lo es el proceso de tostación. El presente trabajo demuestra mediante un análisis de sensibilidad, la conveniencia de implementar un plan de mantenimiento basado en la confiabilidad, utilizando la metodología FMECA con el apoyo de herramientas matemáticas y estadísticas que permiten tener información más precisa sobre el esta do de los equipos, así como en la identificación de brechas y oportunidades de mejora de manera priorizada.
ISA Transactions, 2021
The lack of faulty condition data reduces the feasibility of supervised learning for fault detect... more The lack of faulty condition data reduces the feasibility of supervised learning for fault detection or fault severity discrimination in new manufacturing technologies. To deal with this issue, one-class learning arises for building binary discriminative models using only healthy condition data. However, these models have not been extrapolated to severity discrimination. This paper proposes to extend OCSVM, which is typically used for fault detection, to 3D printer fault severity discrimination. First, a set of features is extracted from a set of normal signals. An optimized OCSVM model is obtained by tuning the kernel and model hyperparameters. The resulting models are evaluated for fault detection and fault severity discrimination using a proposed performance evaluation approach. Experimental comparisons for belt-based faults in 3D printers show that the distance to the hyperplane has the information to discriminate the severity level, and its use is feasible. The proposed hyperparameter optimization technique improves the OCSVM for fault detection and severity discrimination compared to some other methods.
Applied Sciences, 2020
Prognostics and Health Management technologies are useful for early fault detection and optimizat... more Prognostics and Health Management technologies are useful for early fault detection and optimization of reliability in mechanical systems. Reciprocating compressors units are commonly used in industry for gas pressurization and transportation, and the valves in compressors are considered vulnerable parts susceptible to failure. Then, early detection of faults is important for avoiding catastrophic accidents. A feasible approach for fault detection consists in measuring the vibration signal for extracting useful features enabling fault detection and classification. In this research, a test-bed composed by two-stage reciprocating compressor was used for simulating a set of 13 different conditions of combined faults in valves and roller bearings. Three accelerometers were used for collecting the vibration signals for extracting three different types of features. These features were analyzed furthermore by using two random forest models to classifying the different faults. The first set...
Neurocomputing, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
BISTUA REVISTA DE LA FACULTAD DE CIENCIAS BASICAS, 2018
Los cambios y variaciones cada vez más frecuentes en los precios del cobre, dejan de manifiesto, ... more Los cambios y variaciones cada vez más frecuentes en los precios del cobre, dejan de manifiesto, la necesidad de que las empresas mineras sean cada vez más rigurosas en el control de costos de producción, manteniendo su competitividad en el mercado internacional. De esta manera, el uso e implementación de nuevas estrategias de mantenimiento están teniendo una mayor acogida, dado que pueden permitir contener y bajar los costos asociados a la producción. En este trabajo, se presenta el caso de una empresa minera de Chile, la cual se ha propuesto reducir significativamente sus costos de producción, lo que implica necesariamente dirigir esfuerzos en aquellos procesos que regularmente presentan baja disponibilidad y altos costos de mantenimiento, como lo es en este caso, el proceso de tostación. Por lo tanto, mediante un análisis de sensibilidad, se demuestra la conveniencia de implementar un plan de mantenimiento basado en la confiabilidad, utilizando la metodología FMECA, que con el ap...
BISTUA REVISTA DE LA FACULTAD DE CIENCIAS BASICAS, 2019
Los cambios y variaciones cada vez más frecuentes en los precios del cobre, dejan de manifiesto, ... more Los cambios y variaciones cada vez más frecuentes en los precios del cobre, dejan de manifiesto, la necesidad de que las empresas mineras sean cada vez más rigurosas en el control de costos de producción, manteniendo su competitividad en el mercado internacional. De esta manera, el uso e implementación de nuevas estrategias de mantenimiento están teniendo una mayor acogida, dado que pueden permitir contener y bajar los costos asociados a la producción. En este trabajo, se presenta el caso de una empresa minera de Chile, la cual se ha propuesto reducir significativamente sus costos de producción, lo que implica necesariamente dirigir esfuerzos en aquellos procesos que regularmente presentan baja disponibilidad y altos costos de mantenimiento, como lo es en este caso, el proceso de tostación. Por lo tanto, mediante un análisis de sensibilidad, se demuestra la conveniencia de implementar un plan de mantenimiento basado en la confiabilidad, utilizando la metodología FMECA, que con el...
Revista Facultad de Ingeniería, 2017
The pyrometallurgical copper extraction process generates 2.2 t of residues for each ton of produ... more The pyrometallurgical copper extraction process generates 2.2 t of residues for each ton of produced metal. Initially, this paper shows the physical and chemical characterization of a copper processing residue, followed by the procedure to obtain the gold and silver that are contained in the copper residue. The characterization of a white metal oxidized calcine indicates a high content of copper as cupric ferrite, and important values of gold and silver. Gold and silver concentrations were 38.5 g t-1 and 1085 g t-1, respectively. The gold was found scattered in cupric ferrite grains, while the silver was dissolved in a matrix of Cu-S in amounts between 1 % and 50 %. Cyanidation tests showed that 95 % gold recovery could be obtained with a concentration of 0.06 g l-1 KCN, a pH of 10.5, room temperature, and a residence time of 80 h. When the temperature was increased to 75 °C, and the other cyanidation parameters were maintained intact, the same recovery was obtained but with a short...
Lecture Notes in Computer Science
In several cases the vibration signals generated by rotating machines can be modeled as cyclostat... more In several cases the vibration signals generated by rotating machines can be modeled as cyclostationary processes. A cyclostationary process is defined as a non-stationary process which has a periodic time variation in some of its statistics, and which can be characterized in terms of its order of periodicity. This study is focused on the use of cyclic spectral analysis, as a tool to analyze second-order periodicity signals (SOP), such as, those who are generated by either localized or distributed defects in bearings. Cyclic spectral analysis mainly consists of the estimation of the random aspects as well as the periodic behavior of a vibration signal, based on estimation of the spectral correlation density. The usefulness of cyclic spectral analysis for the condition monitoring of bearings, is demonstrated in this paper, through the analysis of several sections of vibration data collected during an endurance test of one of the two main gearbox transmissions of a helicopter.
The work presented here is a theoretical study that describes two different schemes for the oil i... more The work presented here is a theoretical study that describes two different schemes for the oil injection system in actively lubricated main engine bearings. The use of active lubrication in journal bearings helps to enhance the hydrodynamic fluid film by increasing the fluid film thickness and consequently reducing viscous friction losses and vibrations. One refers to active lubrication when conventional hydrodynamic lubrication is combined with dynamically modified hydrostatic lubrication. In this case, the hydrostatic lubrication is modified by injecting oil at controllable pressures, through orifices circumferentially located around the bearing surface. The pressure distribution of the hydrodynamic fluid film in journal bearings is governed by the Reynolds equation, which is modified to accommodate the dynamics of active lubrication, and which can be numerically solved using finite-difference method. The computed bearing fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the reciprocating engine, obtained with the help of multibody dynamics (rigid components) and finite elements method (flexible components). The main equations that govern the dynamics of the injection for a piezo-actuated oil injector and a mechanical-actuated oil injector are presented in this study. It is shown how the dynamics of the oil injection system is coupled to the dynamics of the bearing fluid film through equations. The global system is numerically solved using as a case of study a single-cylinder combustion engine, where the conventional lubrication of the main bearing is modified by applying radial oil injection using piezo-actuated injection. The performance of such a hybrid bearing is compared to an equivalent conventional lubricated bearing in terms of the maximum fluid film pressures, minimum fluid film thicknesses and reduction of viscous friction losses.
This work describes in details the steps involved within the mathematical modelling of reciprocat... more This work describes in details the steps involved within the mathematical modelling of reciprocating linear compressors. The dynamics of the mechanical components are described with help of Dynamics of Multibody Systems (rigid components) and Finite Element Method (flexible components). Some of the mechanical elements are supported by fluid film bearings where the hydrodynamics interaction forces are described by Reynolds equation. Two approaches are investigated, i.e. short and infinite long bearings. The system of nonlinear equations are numerically solved, taking into account the lateral and tilting vibration of the centre of the crank. The behaviour of the orbits in the journal bearings is presented giving some insights into design parameters, as maximal oil film pressure, minimum oil film thickness and maximum vibration levels.
Journal of Vibration and Control, 2011
ABSTRACT The performance of main bearings in a combustion engine affects key functions such as du... more ABSTRACT The performance of main bearings in a combustion engine affects key functions such as durability, noise and vibration. Thus, with the aim of reducing friction losses and vibrations between the crankshaft and the bearings, the work reported here evaluates different strategies for applying controllable radial oil injection to main crankshaft journal bearings. In an actively lubricated bearing, conventional hydrodynamic lubrication is combined with controllable hydrostatic lubrication, where the oil injection pressures can be modified depending on the operational conditions. In this study, the dynamic behaviour of the main bearing of a medium-size engine is theoretically analysed when the engine operates with controllable radial oil injection and four different injection control rules. The theoretical investigation is based on a single-cylinder combustion engine model. The performance of the actively lubricated bearing is compared with the performance of the conventional lubricated bearing, giving some insights into the minimum fluid film thickness, maximum fluid film pressure, friction losses and maximum vibration levels.
Journal of Engineering for Gas Turbines and Power, 2004
In this paper the complete set of modified Reynolds’ equations for the active lubrication is pres... more In this paper the complete set of modified Reynolds’ equations for the active lubrication is presented. The solution of such a set of equations allows the determination of stiffness and damping coefficients of actively lubricated bearings. These coefficients are not just dependent on Sommerfeld number, as it would be the case of conventional hydrodynamic bearings, but they are also dependent on the excitation frequencies and gains of the control loop. Stiffness as well as damping coefficients can be strongly influenced by the choice of the control strategy, servo valve dynamics and geometry of the orifices distributed over the sliding surface. The dynamic coefficients of tilting-pad bearings with and without active lubrication and their influence on an industrial compressor of 391 Kg, which operates with a maximum speed of 10,200 rpm, are analyzed. In the original compressor design, the bearing housings are mounted on squeeze-film dampers in order to ensure reasonable stability marg...
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Papers by Edgar Estupinan