Electronic tongue-type sensor arrays are devices used to determine the quality of substances and seek to imitate the main components of the human sense of taste. For this purpose, an electronic tongue-based system makes use of sensors, data acquisition systems, and a pattern recognition system. Particularly, in the latter, machine learning techniques are useful in data analysis and have been used to solve classification and regression problems. However, one of the problems in the use of this kind of device is associated with the development of reliable pattern recognition algorithms and robust data analysis. In this sense, this work introduces a taste recognition methodology, which is composed of several steps including unfolding data, data normalization, principal component analysis for compressing the data, and classification through different machine learning models. The proposed methodology is tested using data from an electronic tongue with 13 different liquid substances; this electronic tongue uses multifrequency large amplitude pulse signal voltammetry. Results show that the methodology is able to perform the classification accurately and the best results are obtained when it includes the use of K-nearest neighbor machine in terms of accuracy compared with other kinds of machine learning approaches. Besides, the comparison to evaluate the methodology is made with different classification performance measures that show the behavior of the process in a single number.

The synthesis of undoped cobalt oxide and cobalt oxide with 4%nickel doping is studied in samples obtained through hydrothermal technique. After the final heat treatment at 300°C, X-ray diffraction analysis indicated the formation of cobalt spinel oxide with a complete replacement of nickel in the lattice. An average crystallite size of ~42 nm and ~31nm was found, as well as a particle size of ~ 20 nm and ~30 nm for Co3O4 and Co3-xNixO4, respectively. Structural parameters were established through Rietveld refinement with a good correspondence between the simulated and the experimental pattern with values of x2 = 1.25 and GOF = 0.90 for Co3O4. The energy band gap was found through UV-Vis spectroscopy in two different regions: Eg1 and Eg2 values vary between 1.54 and 2.04eV for samples doped with nickel. The SEM results indicated the formation of nanostructures with semi-cubic shape and irregular rods. Parameters such as crystal size, particle size, surface area, as well as morphology of the final product depend on doping.

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Cobalt oxide (Co3O4) nanoparticles were successfully prepared by sol–gel and hydrothermal methods for antibacterial and photocatalytic applications with the addition of 1%, 4% nickel (Ni), and reduced graphene oxide (rGO). The structural and morphological properties of the nanoparticles were obtained by XRD, TEM and FESEM techniques. Cobalt oxide showed typical crystallographic planes to cubic phase and particles with inferior diameter to 30 nm. The Ni-Co3O4 +rGO nanocrystals exhibit a band gap value of 2.0 eV. The bactericidal tests for S. aureus and E. coli revealed that the insertion rGO synthesized by the sol–gel method promoted the antimicrobial activity for both microorganisms. Afterward, the photocatalytic assay for the atrazine contaminant showed significant responses to pesticide removal attributed to the simultaneous adsorption and degradation process. In addition, the sol–gel process found a better response to Ni-Co3O4 in the presence of rGO, indicating a nanocomposite superior synergism.

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Este artículo puede compartirse bajo la licencia CC BY-ND 4.0 y se referencia usando el siguiente formato: P. García, J. Leon, L. Cardenas, JF. Giraldo, "Modelado numérico del proceso de secado solar de manzanas en el municipio de nuevo Colón-Boyacá," Rev. UIS Ing., vol. 17, no. 1, pp. [201][202][203][204][205][206][207][208] 2018. Doi: https://doi.org/10.18273/revuin.v17n1-2018019 Vol. 17, no. 1, pp. 201-208, enero-junio 2018 Revista UIS Ingenierías RESUMENEl secado de frutales caducifolios, como las manzanas, es un proceso en el cual se disminuye la cantidad de humedad contenida dentro del fruto. Además, se busca prolongar el tiempo en el que conserven propiedades organolépticas, físicas y químicas actas para el consumo humano, también este proceso tiene por objeto disminuir los desperdicios y generar una economía rentable en empresas agrícolas productoras de alimentos deshidratados. Según los estándares nacionales, en Colombia se pierde y se desperdicia el 58 % de las frutas y las verduras (6,1 millones de toneladas), mientras que en el mundo el promedio está en 45 % [1]. En Colombia, la región que tiene el mayor nivel de participación en la pérdida nacional es la Centro-oriental (Cundinamarca, Santander, Norte de Santander y Boyacá) con una participación del 1 millón de toneladas entre frutas y verduras. Este proyecto busca realizar una simulación del proceso de transferencia de calor presente en un secador solar de manzanas. En el proceso de secado de frutas intervienen diversas variables físicas, como la temperatura, la velocidad del aire, la humedad de la fruta, el tiempo de secado [12] y para garantizar una calidad óptima en la fruta se deben controlar dichas variables, los fenómenos de transferencia de calor a utilizar son: la convección de calor producida en el aire con los sólidos, la radiación del sol, y la conducción entre los sólidos que componen la estructura de un equipo secador. Existen diversos softwares que facilitan la elaboración de esta simulación como: Matlab o Python. Finalmente se presentan los resultados de las simulaciones realizadas para que con ellas se pueda continuar con el proceso de diseño del secador.PALABRAS CLAVE: Energía solar; secador de frutas; simulación numérica. ABSTRACTThe drying of fruits such as apples is a process in wich the amount of moisture is decreased. Furtheremore this process looks for to prolong the time wich the fruits preserve organolectic, physical and chemical properties for human consumption, this process also aims to reduce waste and generate a profitable economy in agricultural companies producing dehydrated foods. According to national standards, 58 % of fruits and vegetables are lost and wasted in Colombia, while in the world the average is 45 % [1]. In Colombia, the region with the highest level of participation

In the present research, the synthesis of cobalt oxide Co 3 O 4 was carried out using the sol-gel technique with subsequent heat treatment at 225 and 235 °C. The final product obtained was characterized by X-ray diffraction (XRD), showing a pure crystalline phase of Co 3 O 4 , cell parameters a=b=c=8.071 Å, and a volume of 525.7 Å 3 . The particle size was between 2.37 and 2.77 µm, which indicated that structural transformations from Co to Co 3 O 4 induced an increase in the particle size. Through Rietveld refinement, the interatomic distances and inclination angles of the Co 1 , Co 2 , and Co 3 polyhedra were analyzed in order to establish the structural behavior of cobalt oxide (II, III) at 235 °C. The UV-vis analysis allowed determining band gap (E g ) with values of 1.6 eV in the first region and 0.97 eV in the second. Scanning electron microscopy images showed that the particles agglomerated with increasing calcination temperature and exhibited larger particles. This work presents a detailed analysis of structural parameters of Co 3 O 4 using the Vesta software with Rietveld refinement data.

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