Examinando por Materia "Large scale systems"
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Ítem Maintenance policy optimisation for multi-component systems considering degradation of components and imperfect maintenance actions(Elsevier Ltd, 2018-10-01) Martinod R, R.M.; Bistorin, Oliver; Castaneda Heredia Leonel F.; Rezg, Nidhal; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)This article proposes a stochastic optimisation model in order to reduce the long-term total maintenance cost of complex systems. The proposed work is based on the following approaches: (i) optimisation of a cost model for complex multi-component systems consisting of preventive and corrective maintenance using reliability analysis, which faces two different maintenance policies (periodic block-type and age-based) and (ii) a clustering method for maintenance actions to decrease the total maintenance cost of the complex system. This work evaluates each maintenance policy and measures the effects on imperfect maintenance actions. Finally, the proposed optimisation model is applied to a numerical example which focuses on passenger urban aerial ropeway transport systems, in which the current maintenance policy has been evaluated, considering the established by the international regulation of passenger aerial cable cars. © 2018 Elsevier LtdÍtem Systematic exploration of signal-based indicators for failure diagnosis in the context of cyber-physical systems(Zhejiang University, 2019-01-01) Ruiz-Arenas S.; Rusák Z.; Horváth I.; Mejí-Gutierrez R.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Malfunction or breakdown of certain mission critical systems (MCSs) may cause losses of life, damage the environments, and/or lead to high costs. Therefore, recognition of emerging failures and preventive maintenance are essential for reliable operation of MCSs. There is a practical approach for identifying and forecasting failures based on the indicators obtained from real life processes. We aim to develop means for performing active failure diagnosis and forecasting based on monitoring statistical changes of generic signal features in the specific operation modes of the system. In this paper, we present a new approach for identifying emerging failures based on their manifestations in system signals. Our approach benefits from the dynamic management of the system operation modes and from simultaneous processing and characterization of multiple heterogeneous signal sources. It improves the reliability of failure diagnosis and forecasting by investigating system performance in various operation modes, includes reasoning about failures and forming of failures using a failure indicator matrix which is composed of statistical deviation of signal characteristics between normal and failed operations, and implements a failure indicator concept that can be used as a plug and play failure diagnosis and failure forecasting feature of cyber-physical systems. We demonstrate that our method can automate failure diagnosis in the MCSs and lend the MCSs to the development of decision support systems for preventive maintenance. © 2019, Zhejiang University and Springer-Verlag GmbH Germany, part of Springer Nature.Ítem Three-dimensional surface contouring of macroscopic objects by means of phase-difference images(OPTICAL SOC AMER, 2006-09-01) Prieto, Daniel Velasquez; Garcia-Sucerquia, Jorge; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaWe report a technique to determine the 3D contour of objects with dimensions of at least 4 orders of magnitude larger than the illumination optical wavelength. Our proposal is based on the numerical reconstruction of the optical wave field of digitally recorded holograms. The required modulo 2ir phase map in any contouring process is obtained by means of the direct subtraction of two phase-contrast images under different illumination angles to create a phase-difference image of a still object. Obtaining the phase-difference images is only possible by using the capability of numerical reconstruction of the complex optical field provided by digital holography. This unique characteristic leads us to a robust, reliable, and fast procedure that requires only two images. A theoretical analysis of the contouring system is shown, with verification by means of numerical and experimental results. © 2006 Optical Society of America.Ítem Towards the maintenance principles of cyber-physical systems(ASSOC MECHANICAL ENGINEERS TECHNICIANS SLOVENIA, 2014-01-01) Ruiz-Arenas, S.; Horváth, I.; Mejía-Gutiérrez, R.; Opiyo, E.Z.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Cyber-physical systems (CPSs) are rapidly proliferating in different applications. Their system features significantly differ from those of linear complex systems (LCSs). Consequently, they pose novel challenges with regard to ensuring the dependability of system operation. Maintenance of CPSs raises new theoretical and practical issues. To guarantee a high level of dependability, new and efficient system maintenance principles should be explored and operationalized in various contexts. This paper reports on the first results of the authors' work in this direction. A comprehensive literature review has been conducted with the objective of identifying the specific features of LCSs and CPSs. We analysed the major maintenance principles and approaches currently applied to complex systems to see how they can be applied to CPSs. We found that the existing maintenance principles have various relationships with CPSs: (i) some of them cannot be considered in the context of CPSs due to incongruent system features, (ii) some of them can be adapted due to certain partial congruencies, and (iii) some of them can be applied directly due to the congruency of some system features of LCSs with CPSs. It was also found and demonstrated through a number of practical examples that many specific maintenance principles need to be developed for CPSs. We assert that the system features of CPSs without parallel in LCSs primarily reveal what sort of new maintenance principles and approaches are needed. The ultimate goal of our on-going research is to define and test these new maintenance principles. In this paper, we identify and define these principles, starting from the unique system features of CPSs and aiming to develop a maintenance advisory system. © 2014 Journal of Mechanical Engineering. All rights reserved.