Browsing by Author "Nunez, Felipe"

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    An event-driven simulator for multi-line metro systems and its application to Santiago de Chile metropolitan rail network
    (ELSEVIER, 2011) Grube, Pablo; Nunez, Felipe; Cipriano, Aldo
    Metros are the principal means of public transportation in many of the world s cities and continue to grow in the face of rising demand Expanding metro infrastructure is costly however and at a certain point becomes unsustainable When this occurs the only feasible solution is to Improve the train s management system by using either offline approaches such as pre-programming schedules which use historic information or online approaches which employ system status information obtained during operation A new planning or control system be it on or off line requires prior testing that usually involves conducting simulations This paper presents the design and implementation of an event-driven dynamic simulator for multi-line metro systems and its practical application for studying different operating strategies The simulator is based on object-oriented programming and is capable of interacting with Matlab programs written by the user to design and evaluate real-time control strategies This article describes the model upon which the simulator is based presents the user interface and demonstrates how to use the simulator for operating strategies evaluation in the Santiago de Chile multi-line metropolitan rail network (C) 2010 Elsevier BV All rights reserved
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    Fault tolerant measurement system based on Takagi-Sugeno fuzzy models for a gas turbine in a combined cycle power plant
    (ELSEVIER, 2011) Berrios, Rodrigo; Nunez, Felipe; Cipriano, Aldo
    A fault tolerant measurement system for a gas turbine in a combined cycle power plant, based on dynamic models, principal component analysis (PCA) and Q test, is presented. The proposed scheme makes use of a model-based symptom generator, which delivers fault signals obtained by using direct identification of parity relations and structured residuals. Symptoms are then analyzed in a statistical module achieving fault diagnosis and reconstruction of the faulty signals. The scheme presents as main advantage the ability of detecting faults in both input and output sensors due to its particular structure. Tests carried out on the gas turbine of the San Isidro combined cycle power plant in the V Region, Chile, show that Takagi-Sugeno fuzzy models present the best fitting performance and an acceptable computational cost in comparison with autoregressive exogenous. state space, and neural models. Real time software based on this scheme has been developed and connected to Osisoft PI System'. The software is running at Endesa Monitoring and Diagnosis Center in Santiago. Chile. (C) 2011 Elsevier B.V. All rights reserved.
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    Hierarchical hybrid fuzzy strategy for column flotation control
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) Nunez, Felipe; Tapia, Luis; Cipriano, Aldo
    Column flotation is widely used in the concentration of low grade ores. Often column flotation concentrate is the final product of a very complex circuit, and therefore control of the metallurgical performance has direct impact in the plant performance. Several control schemes has been implemented for the stabilization of column flotation process, including decentralized control. model predictive control and fuzzy approaches, which attempt to control froth depth, water bias and air holdup. At the same time many efforts have been oriented to improve process instrumentation, with the aim of providing better measurements for control purposes. Instrumentation improvements have made feasible the design of strategies focused on recovery and concentrate grade control. In this work we present the design and implementation of a new advanced controller for column flotation process. The controller was implemented in a 10 columns cleaning stage following a hierarchical scheme with two control levels: an improving level with the aim of metallurgical performance control of the whole process, and a stabilizing level in charge of the distribution of control actions in each column. The controller design was made based on a hybrid scheme with three different operation scenarios, defined by a recovery-concentrate grade domain partition. Results show that the controller is able to keep the process in the normal operation scenario 80% of the analyzed time; on the other hand, when the process was operated only with local control it achieved the normal operation scenario 43% of the analyzed time. Results also show that the controller is capable of increasing concentrate grade and recovery mean values, despite variations on feed grade; while reducing recovery and concentrate grade standard deviations. (C) 2009 Elsevier Ltd. All rights reserved.
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    Robust Gossiping for Distributed Average Consensus in IoT Environments
    (2019) Orostica, Boris; Nunez, Felipe
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    Visual information model based predictor for froth speed control in flotation process
    (PERGAMON-ELSEVIER SCIENCE LTD, 2009) Nunez, Felipe; Cipriano, Aldo
    Image processing sensors are emerging as an important measurement option in mineral processing, mainly due to their non-intrusive characteristics. Their principal application areas have been the determination of ore size distributions in grinding and froth features in flotation. The incorporation of visual information in control loops is the logical step. However, the excessive processing required brings a new problem that must be solve: to count with a strategy able to provide a measured value for each visual sensor in the plant. A first approach is to assign one computer to each sensor yielding a distributed architecture, but this means the implementation of a huge computer network. A more efficient alternative is alternated sampling, but the succeed of this option is limited to the existence of virtual sensors capable of give accurate values that must be use during the unsampled period. In this paper we begin by reviewing classical image processing algorithms used in flotation froth feature extraction. Then a new method is introduced for the characterization and recognition of visual information using dynamic texture techniques. Finally we developed a dynamic texture based virtual sensor for the prediction of froth speed in the unsampled period, tested with industrial data. (C) 2008 Elsevier Ltd. All rights reserved.