Advanced Mining Technology Center

Santiago, Chile

Advanced Mining Technology Center

Santiago, Chile
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Aguila-Camacho N.,University of Chile | Aguila-Camacho N.,Advanced Mining Technology Center | Le Roux J.D.,University of Pretoria | Duarte-Mermoud M.A.,University of Chile | And 3 more authors.
Journal of Process Control | Year: 2017

This paper presents the design and application of fractional single-input–single-output (SISO) controllers to a grinding mill circuit, which is a multiple-input–multiple-output (MIMO) process. Two kinds of controllers are presented: fractional order proportional-integral (FOPI) controllers, and a combination of FOPI and fractional order model reference adaptive controllers (FOMRAC). The parameters of the controller are tuned using off-line particle swarm optimization. In the presence of disturbances and process noise, the SISO fractional controllers achieve similar or better performance compared to linear model predictive control (LMPC). © 2017 Elsevier Ltd

Delpiano J.,University of Los Andes, Chile | Pizarro L.,University College London | Verschae R.,Advanced Mining Technology Center | Ruiz-del-Solar J.,Advanced Mining Technology Center | Ruiz-del-Solar J.,University of Chile
Applied Soft Computing Journal | Year: 2016

Optical flow methods are among the most accurate techniques for estimating displacement and velocity fields in a number of applications that range from neuroscience to robotics. The performance of any optical flow method will naturally depend on the configuration of its parameters, and for different applications there are different trade-offs between the corresponding evaluation criteria (e.g. the accuracy and the processing speed of the estimated optical flow). Beyond the standard practice of manual selection of parameters for a specific application, in this article we propose a framework for automatic parameter setting that allows searching for an approximated Pareto-optimal set of configurations in the whole parameter space. This final Pareto-front characterizes each specific method, enabling proper method comparison and proper parameter selection. Using the proposed methodology and two open benchmark databases, we study two recent variational optical flow methods. The obtained results clearly indicate that the method to be selected is application dependent, that in general method comparison and parameter selection should not be done using a single evaluation measure, and that the proposed approach allows to successfully perform the desired method comparison and parameter selection. © 2016 Elsevier B.V.

Aguila-Camacho N.,University of Chile | Aguila-Camacho N.,Advanced Mining Technology Center | Duarte-Mermoud M.A.,University of Chile | Duarte-Mermoud M.A.,Advanced Mining Technology Center
ISA Transactions | Year: 2013

This paper presents the application of a direct Fractional Order Model Reference Adaptive Controller (FOMRAC) to an Automatic Voltage Regulator (AVR). A direct FOMRAC is a direct Model Reference Adaptive Control (MRAC), whose controller parameters are adjusted using fractional order differential equations. Four realizations of the FOMRAC were designed in this work, each one considering different orders for the plant model. The design procedure consisted of determining the optimal values of the fractional order and the adaptive gains for each adaptive law, using Genetic algorithm optimization. Comparisons were made among the four FOMRAC designs, a fractional order PID (FOPID), a classical PID, and four Integer Order Model Reference Adaptive Controllers (IOMRAC), showing that the FOMRAC can improve the controlled system behavior and its robustness with respect to model uncertainties. Finally, some performance indices are presented here for the controlled schemes, in order to show the advantages and disadvantages of the FOMRAC. © 2013 ISA.Published by Elsevier Ltd. All rights reserved.

Vergara J.R.,University of Chile | Vergara J.R.,Millennium Institute of Astrophysics | Estevez P.A.,University of Chile | Estevez P.A.,Millennium Institute of Astrophysics | And 2 more authors.
Advances in Intelligent Systems and Computing | Year: 2016

In this work we propose an extension to Growing Neural Gas (GNG) for dealing with the spatiotemporal quantization of time series. The two main changes to the original GNG algorithm are the following. First, the basic unit of the GNG network is changed from a node to a linear segment joining two nodes. Secondly, temporal connections between neighboring units in time are added. The proposed algorithm called Segment GNG (SGNG) is compared with the original GNG and Merge GNG algorithms using three benchmark time series: Rössler, Mackey-Glass and NH3 Laser. The algorithms are applied to the quantization of trajectories in the state space representation of these time series. The results show that the SGNG outperforms both GNG and Merge GNG in terms of quantization error and temporal quantization error. © Springer International Publishing Switzerland 2016.

Duarte-Mermoud M.A.,University of Chile | Duarte-Mermoud M.A.,Advanced Mining Technology Center | Aguila-Camacho N.,University of Chile | Aguila-Camacho N.,Advanced Mining Technology Center | Gallegos J.A.,University of Chile
The Scientific World Journal | Year: 2013

A sufficient condition on the fractional integral of the absolute value of a function is given in this paper, which allows to assure the convergence of the function to zero. This result can be useful to assure the convergence of a function when it is hard to know its exact evolution, but conditions on its fractional integral can be stated. © 2013 Manuel A. Duarte-Mermoud et al.

Aguila-Camacho N.,University of Chile | Aguila-Camacho N.,Advanced Mining Technology Center | Duarte-Mermoud M.A.,University of Chile | Duarte-Mermoud M.A.,Advanced Mining Technology Center
ISA Transactions | Year: 2015

This paper presents the analysis of three classes of fractional differential equations appearing in the field of fractional adaptive systems, for the case when the fractional order is in the interval α∈(0,1] and the Caputo definition for fractional derivatives is used. The boundedness of the solutions is proved for all three cases, and the convergence to zero of the mean value of one of the variables is also proved. Applications of the obtained results to fractional adaptive schemes in the context of identification and control problems are presented at the end of the paper, including numerical simulations which support the analytical results. © 2015 ISA.

Milla F.,University of Chile | Milla F.,Advanced Mining Technology Center | Duarte-Mermoud M.A.,University of Chile | Duarte-Mermoud M.A.,Advanced Mining Technology Center
ISA Transactions | Year: 2016

Power System Stabilizer (PSS) devices are responsible for providing a damping torque component to generators for reducing fluctuations in the system caused by small perturbations. A Predictive Optimized Adaptive PSS (POA-PSS) to improve the oscillations in a Single Machine Infinite Bus (SMIB) power system is discussed in this paper. POA-PSS provides the optimal design parameters for the classic PSS using an optimization predictive algorithm, which adapts to changes in the inputs of the system. This approach is part of small signal stability analysis, which uses equations in an incremental form around an operating point. Simulation studies on the SMIB power system illustrate that the proposed POA-PSS approach has better performance than the classical PSS. In addition, the effort in the control action of the POA-PSS is much less than that of other approaches considered for comparison. © 2016 ISA.

Tassi F.,University of Florence | Tassi F.,CNR Institute of Geosciences and Earth Resources | Aguilera F.,Servicio Nacional de Geologia y Mineria | Benavente O.,University of Chile | And 11 more authors.
Chemical Geology | Year: 2016

This study presents the first geochemical data of fluid discharges collected from February 2010 to March 2015 from the Planchón-Peteroa-Azufre Volcanic Complex (PPAVC), located in the Transitional Southern Volcanic Zone (TSVZ) at the border between Argentina and Chile. During the study period, from January 2010 to July 2011, Peteroa volcano experienced phreatic to phreatomagmatic eruption possibly related to the devastating Maule earthquake occurred on February 27, 2010. The compositional dataset includes low temperature (from 43.2 to 102 °C) gas discharges from (i) the summit of Peteroa volcano and (ii) the SE flank of Azufre volcano, both marked by a significant magmatic fluid contribution, as well as bubbling gases located at the foothill of the Peteroa volcanic edifice, which showed a chemical signature typical of hydrothermal fluids. In 2012, strong compositional changes affected the Peteroa gases from the summit area: the acidic gas species, especially SO2, increased, suggesting an input of fluids from magma degassing. Nevertheless, the R/Ra and δ13C-CO2 values decreased, which would imply an enhanced contribution from a meteoric-hydrothermal source. In 2014-2015, the chemical and isotopic compositions of the 2010-2011 gases were partially restored. The anomalous decoupling between the chemical and the isotopic parameters was tentatively interpreted as produced by degassing activity from a small batch of dacitic magma that in 2012 masked the compositional signature of the magmatic fluids released from a basaltic magma that dominated the gas chemistry in 2010-2011. This explanation reliably justifies the observed geochemical data, although the mechanisms leading to the change in time of the dominating magmatic fluid source are not clear. At this regard, a geophysical survey able to provide information on the location of the two magma batches could be useful to clarify the possible relationships between the compositional changes that affected the Peteroa fluid discharges and the 2010-2011 eruptive activity. © 2016 Elsevier B.V.

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