Examinando por Materia "Multiobjective optimization"

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    Mineralization of cyanide originating from gold leaching effluent using electro-oxidation: multi-objective optimization and kinetic study
    (SPRINGER, 2020-01-01) Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    Abstract: This study examines the electro-oxidation (EO) of cyanide originating from an industrial plant´s gold leaching effluent. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes consisting of graphite (anode) and aluminum (cathode) was employed, operating in galvanostatic mode. Response Surface Methodology (RSM), based on a Box–Behnken experimental Design (BBD), was used to optimize the EO operational conditions. Three independent process variables were considered: initial cyanide concentration ([CN-]0 = 1000–2000 mg L-1), current density (J =7–107 mA cm-2), and stirring velocity (? = 250–750 rpm). The cyanide conversion (XCN-), Chemical Oxygen Demand (COD) removal percentage (%RCOD), and specific Energy Consumption per unit mass of removed cyanide (EC) were analyzed as response variables. Multi-objective optimization let to establish the most effective EO conditions ([CN-]0 = 1000 mg L-1, J = 100 mA cm-2 and ? = 750 rpm). The experimental data (XCN-, %RCOD, and EC) were fitted to second-order polynomial models with adjusted correlation coefficients (Radj2) of ca. 98, 99 and 87%, respectively. The kinetic analysis, performed at optimal EO operational conditions, allowed determination of time required to meet Colombian permissible discharge limits. The predictive capacity of kinetic expressions was verified against experimental data obtained for gold leaching effluent. Total cyanide removal and 96% of COD reduction were obtained, requiring EC of 71.33 kWh kg-1 and 180 min. The BOD5 (biological oxygen demand)/COD ratio increased from 4.52 × 10-4 to 0.5573, confirming effluent biodegradability after EO treatment. Graphic Abstract: [Figure not available: see fulltext.]The variation of cyanide (CN-), cyanate (CNO-) and ammonium (NH4 +) ions concentrations vs. time at alkaline conditions. EO operational conditions: [CN-]0 = 1000 mg/L, J = 100 mA/cm2 , ? = 750 rpm, [NaCl] = 0.15 M and pH 11.1. © 2020, Springer Nature B.V.
  • No hay miniatura disponible
    Ítem
    Mineralization of cyanide originating from gold leaching effluent using electro-oxidation: multi-objective optimization and kinetic study
    (SPRINGER, 2020-01-01) Dobrosz-Gómez I.; Gómez García M.Á.; Gaviria G.H.; GilPavas E.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    Abstract: This study examines the electro-oxidation (EO) of cyanide originating from an industrial plant´s gold leaching effluent. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes consisting of graphite (anode) and aluminum (cathode) was employed, operating in galvanostatic mode. Response Surface Methodology (RSM), based on a Box–Behnken experimental Design (BBD), was used to optimize the EO operational conditions. Three independent process variables were considered: initial cyanide concentration ([CN-]0 = 1000–2000 mg L-1), current density (J =7–107 mA cm-2), and stirring velocity (? = 250–750 rpm). The cyanide conversion (XCN-), Chemical Oxygen Demand (COD) removal percentage (%RCOD), and specific Energy Consumption per unit mass of removed cyanide (EC) were analyzed as response variables. Multi-objective optimization let to establish the most effective EO conditions ([CN-]0 = 1000 mg L-1, J = 100 mA cm-2 and ? = 750 rpm). The experimental data (XCN-, %RCOD, and EC) were fitted to second-order polynomial models with adjusted correlation coefficients (Radj2) of ca. 98, 99 and 87%, respectively. The kinetic analysis, performed at optimal EO operational conditions, allowed determination of time required to meet Colombian permissible discharge limits. The predictive capacity of kinetic expressions was verified against experimental data obtained for gold leaching effluent. Total cyanide removal and 96% of COD reduction were obtained, requiring EC of 71.33 kWh kg-1 and 180 min. The BOD5 (biological oxygen demand)/COD ratio increased from 4.52 × 10-4 to 0.5573, confirming effluent biodegradability after EO treatment. Graphic Abstract: [Figure not available: see fulltext.]The variation of cyanide (CN-), cyanate (CNO-) and ammonium (NH4 +) ions concentrations vs. time at alkaline conditions. EO operational conditions: [CN-]0 = 1000 mg/L, J = 100 mA/cm2 , ? = 750 rpm, [NaCl] = 0.15 M and pH 11.1. © 2020, Springer Nature B.V.
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    A multi-objective evolutionary approach to improve the environmental performance of a supply chain
    (Institute of Industrial Engineers, 2017-01-01) Ozden S.G.; Vélez-Gallego M.C.; Universidad EAFIT. Departamento de Ingeniería de Producción; Gestión de Producción y Logística
    The problem of improving the environmental performance of a supply chain without entailing excessive cost is becoming a frequent problem as companies face an increasing pressure from governments and customers for reducing the environmental impact of their activities. As the environmental improvement of an operating supply chain implies not only technology upgrading decisions, but also decisions regarding the structure of the supply chain itself
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    Optimization of V-Trough photovoltaic concentrators through genetic algorithms with heuristics based on Weibull distributions
    (Elsevier Ltd, 2018-02-15) Arias-Rosales A.; Mejía-Gutiérrez R.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
    Photovoltaic V-Troughs use simple and low-cost non-imaging optics, namely flat mirrors, to increase the solar harvesting area by concentrating the sunlight towards regular solar cells. The geometrical dispositions of the V-Trough's elements, and the way in which they are dynamically adjusted to track the sun, condition the optical performance. In order to improve their harvesting capacity, their geometrical set-up can be tailored to specific conditions and performance priorities. Given the large number of possible configurations and the interdependence of the multiple parameters involved, this work studies genetic algorithms as a heuristic approach for navigating the space of possible solutions. Among the algorithms studied, a new genetic algorithm named “GA-WA” (Genetic Algorithm-Weibull Arias) is proposed. GA-WA uses new heuristic processes based on Weibull distributions. Several V-Trough performance indicators are proposed as objective functions that can be optimized with genetic algorithms: (i) Ce? (average effective concentration); (ii) Cost (cost of materials) and (iii) Tsp (space required). Moreover, from the integration of these indicators, three multi-objective indices are proposed: (a) ICOE (Ce? versus Cost); (b) MICOE (Ce? versus Cost and Ce? versus Tsp combined) and (c) MDICOE (similar to MICOE but with discretization considerations). The heuristic parameters of the studied genetic algorithms are optimized and their capacities are explored in a case study. The results are compared against reported V-Trough set-ups designed with the interactive software VTDesign for the same case study. It was found that genetic algorithms, such as the ones developed in this work, are effective in the performance indicators improvement, as well as efficient and flexible tools in the problem of defining the set-up of solar V-Troughs in personalized scenarios. The intuition and the more holistic exploration of a trained engineer with an interactive software can be complemented with the broader and less biased evolutionary optimization of a tool like GA-WA. © 2017 Elsevier Ltd