Artículos de conferencia

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Browsing Artículos de conferencia by Subject "06 Agua limpia y saneamiento"

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    Arsenic-related cancer mortality in Northern Chile, 1989-98
    (LIPPINCOTT WILLIAMS & WILKINS, 2004) Bates, M; Marshall, G; Ferreccio, C; Smith, A
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    Dilatation and shearing in tectono-volcanic systems from poro-elasto-plastic models set in the Southern Andes Volcanic Zone context, inferences on geofluid flow
    (2022) Gerbault, Muriel; Saez, Felipe; Ruz Ginouves, Javiera; Cembrano, José; Iturrieta, Pablo; Hurtado, Daniel; Hassani, Riad; Browning, John
    Geothermal fields near volcanic complexes and active crustal-scale fault zones require an understanding of the mechanical interactions that control variations in pore fluid pressure at a crustal scale. Crustal faults can trigger and modify fluid flow depending mostly on their geometry and mechanical properties. In turn, fluid flow reduces normal stresses causing either shearing or dilation through the rock mass, concomitant with hydraulic fracturing or seismic fault reactivation. The Southern Andes Volcanic Zone (SAVZ) documents widespread geofluid migration through the crust within a bulk regional transpressive regime. We address here the key role of dilatational domains potentially hosting geothermal fluids, in close relation to shear zones, by using elasto-plastic and poro-elasto-plastic models. First we define models considering Drucker-Prager elasto-plasticity, that account for either: 1) an inflating magmatic cavity or 2) a dextral slipping fault zone ca. 4 km apart, to assess the rheological conditions leading to brittle failure of the bedrock around the fault zone and the cavity, respectively. This setup is applied to the San-Pedro Tatara volcanic complex in the SAVZ. Parametric tests of Young’s moduli and frictional strength provide not only the conditions for macro-scale shear failure, but also shows the development of diffuse domains of dilatational strain in the intervening bedrock. Both void opening and/or volumetric cracking may lead to an increase in porosity and/or permeability, allowing over-pressurized geofluids to migrate within these domains. Our results (Ruz Ginouves et al., JVGR, 2021) show that generally, shallow magma chambers (~< 4 km) and fault zones must be close enough to trigger bedrock failure of the other counterpart (< 4 km), unless the magma chamber is deeper than 10 km, the magma overpressure is high or the regional strength is very low. We argue that alternating strike-slip faulting and magmatic overpressure promote a variety of stress fields that may explain observations of transient fluid pathways on seemingly independent timescales along the Andean margin. To gain further insights into these processes, we develop a numerical scheme to quantify stress and fluid flow with a coupled poro-mechanical approach implemented using Python’s Opensource FEM library FeniCS. Benchmarks are first presented to validate our poro-elasto-plastic approach. Then a synthetic setup shows how fluids get channelized around a fault zone several days after an imposed fault slip motion. Preliminary results are discussed in comparison to a high enthalpy geothermal system associated with another volcanic complex in the SAVZ.
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    Hybrid modeling of froth flotation superficial appearance applying dynamic textures analysis
    (IEEE, 2008) Núñez Retamal, Felipe Eduardo; Cipriano, Aldo
    Flotation is one of the most complex processes in mining industry. In fact, non linear characteristics, large delays, significant disturbances and important unmeasurable variables make the process very difficult for automatic control. However, experimented operators are able to take adequate control actions based on superficial froth appearance by defining several operational states. To ensure the obtaining of technical and economical benefits, it is necessary to better identify different operational states from the froth superficial appearance. In this work we propose a hybrid characterization of the froth surface applying dynamic texture techniques and texture classification. Results show that the models obtained represent accurately the froth dynamics and our detection algorithm is able to detect efficiently different froth operational states.
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    Predictive control with fuzzy characterization of percentage of solids, particle size and power demand for minerals grinding
    (IEEE, 2001) Orchard, M.; Flores Moltedo, Andrés Ricardo; Munoz, C.; Cipriano, Aldo
    The application of fuzzy predictive control to solve the regulatory problem in mineral grinding plants is considered. The controlled variables are percentage of solids, particle sizes and power demand and the manipulated variables are water and fresh ore flows. The controller uses linear multivariable models and the fuzzy characterization of the controlled variables, to calculate the manipulated variables. Simulation results under typical disturbances show a better performance compared with the conventional predictive control.
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    Recession discharge from compartmentalized bedrock hillslopes: hydrogeological processes and solutions for model calibration
    (2024) Clement Roques; Ronan Abhervé; Marti, Etienne; Nicolas Cornette; Jean-Raynald de Dreuzy; David Rupp; Alexandre Boisson; Sarah Leray; Philip Brunner; John Selker
    Due to the difficulties of gathering relevant data of groundwater systems and the lack of fundamental physically-based understanding on the processes involved, the representation of groundwater flow heterogeneity in catchment- to regional-scale hydrological models is often overlooked. We often limit the representation of groundwater with simplified homogeneous and shallow aquifers where effective hydraulic properties are derived from global-scale database. This raises questions regarding the validity of such models to quantify the potential impacts of climate change, where subsurface heterogeneity is expected to play a major role in their short- to long- term regulation.We will present the results of a numerical modelling experiment designed to explore the role of the vertical compartmentalization of hillslopes on groundwater flow and recession discharge. We found that, when hydraulic properties are vertically compartmentalized, streamflow recession behaviour may strongly deviate from what is predicted by groundwater theory that considers the drainage of shallow reservoirs with homogeneous properties. We further identified the hillslope configurations for which the homogeneous theory derived from the Boussinesq solution approximately holds and, conversely, for those for which it does not. By comparing the modelled streamflow recession discharge and the groundwater table dynamics, we identify the critical hydrogeological conditions responsible for the emergence of strong deviations. We further present new solutions to better represent subsurface heterogeneity in catchment-scale models and calibrate hydraulic parameters that properly capture the groundwater and streamflow dynamics.