Bacterial-foraging optimization algorithm for non-hazardous plant layouts

PresentationThe following article approaches a safe plant layout design problem based on a bacterial-foraging optimization algorithm. Our approach finds the position in the two dimensional plane for each main process unit and evaluates the possibility of secondary contention for pertinent units, in order to minimize capital costs associated to equipment loss, piping, secondary contention, and usage of area. Fire and Explosion hazard is considered as the relevant safety aspect for distribution, and it is assessed through Dow’s Fire and Explosion Index. The proposed solution approach provides an alternative to hard-optimization methods, by allowing greater flexibility in accounting for both safety and economic aspects, while providing high quality solutions in a limited computation time. The aim of our proposed solution approach is to provide support to expert decision-making during the early plant layout design steps. A case study based on an acrylic-acid production plant, which has been used by several other papers that appeared in the literature, serves the purposes of showing the appropriateness and effectiveness of the method

EVALUACIÓN DE RIESGOS FINANCIEROS EN EL MERCADO ELÉCTRICO COLOMBIANO

Este artículo presenta los resultados de adaptar técnicas financieras al cálculo de un portafolio de inversiones en el mercado eléctrico. Al definir políticas de inversión a largo plazo se propone usar los caudales medios de los ríos en el país para pronosticar el precio de la energía eléctrica. Luego un modelo de programación cuadrática con restricciones lineales es aplicado para determinar la estructura óptima del portafolio de inversiones y calculado el denominado “Value at Risk (VaR)”, o valoración del riesgo del mismo. Finalmente se presentan algunas recomendaciones acerca de otras metodologías a analizar en posteriores estudios, para resolver este mismo problema

Coupling sky images with radiative transfer models: a new method to estimate cloud optical depth

A method for retrieving cloud optical depth (τc) using a UCSD developed ground-based sky imager (USI) is presented. The radiance red–blue ratio (RRBR) method is motivated from the analysis of simulated images of various τc produced by a radiative transfer model (RTM). From these images the basic parameters affecting the radiance and red–blue ratio (RBR) of a pixel are identified as the solar zenith angle (θ0), τc, solar pixel angle/scattering angle (ϑs), and pixel zenith angle/view angle (ϑz). The effects of these parameters are described and the functions for radiance, Iλτc, θ0, ϑs, ϑz, and RBRτc, θ0, ϑs, ϑz are retrieved from the RTM results. RBR, which is commonly used for cloud detection in sky images, provides non-unique solutions for τc, where RBR increases with τc up to about τc = 1 (depending on other parameters) and then decreases. Therefore, the RRBR algorithm uses the measured Iλmeasϑs, ϑz, in addition to RBRmeasϑs, ϑz, to obtain a unique solution for τc. The RRBR method is applied to images of liquid water clouds taken by a USI at the Oklahoma Atmospheric Radiation Measurement (ARM) program site over the course of 220 days and compared against measurements from a microwave radiometer (MWR) and output from the Min et al. (2003) method for overcast skies. τc values ranged from 0 to 80 with values over 80, being capped and registered as 80. A τc RMSE of 2.5 between the Min et al. (2003) method and the USI are observed. The MWR and USI  have an RMSE of 2.2, which is well within the uncertainty of the MWR. The procedure developed here provides a foundation to test and develop other cloud detection algorithms

Removal of Azo Dyes Through a Natural Coagulant Obtained from Coffee Waste (coffea Arabica)

The present work evaluated the performance of coffee (Coffea Arabica) Caturra variety waste extracts for the removal of two azo dyes used in the textile industry. Ultrasonic extractions were performed to evaluate the effect of particle size and type of residue on the concentration of polyphenols in the extracts, finding that the dehydrated pulp with a particle diameter of 3.375 mm is the residue with the highest yield with 6.96 ± 0.08 milligrams of Gallic Acid in a gram of dry base (mgGAE/gBD); The extract of polyphenolic compounds was dosed in synthetic waters with azo dyes to test its efficacy as a coagulant, using a jar test by varying the doses and pH. It was found that the maximum removal for the acid red dye was 59.37 % of the acid red dye #88 (RD-88) at a concentration of 15 milligrams per liter (mg/L) of the natural coagulant at acid pH and 49.76 % of the acid yellow dye #36 (YD-36) at a concentration of 15 mg/L of the polyphenolic extract at neutral pH. Finally, the results obtained were compared with the performance of aluminum sulfate (AS), which achieved a 65.44% removal of YD-36 at a concentration of 15 mg/L at neutral pH and 95.04% of RD-88 at a concentration of 10 mg/L of metallic coagulant at acid pH. natural coagulants obtained from coffee residues have the potential to be used in the removal of cationic dyes by coagulation processes, it is necessary to carry out tests to optimize the process and improve the coagulant by means of chemical modifications and the use of complementary flocculants