# Ingeniería y Ciencia, Vol. 16, Núm. 31 (2020)

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Ítem Determination of Kinetic Parameters in the Biosorption of Chromium (VI) in Aqueous Solution(Universidad EAFIT, 2020-06-19) Tejada-Tovar, Candelaria; Villabona-Ortíz, Angel; Ortega-Toro, Rodrigo; Universidad de CartagenaMás... The contamination of aquatic bodies by heavy metals is a growing environmental problem, making more critical the study and development of new technologies and materials that can be used for the removal of this type of pollutants. Thus, adsorption arises using residual materials as a sustainable alternative for the solution to this problem. In the present study, the use of plantain peels in the adsorption of Cr (VI) in a batchsystem is proposed, establishing the kinetics of the process at different temperature conditions, particle size and amount of adsorbent. The fit of the data was done using the theoretical models of pseudo-first-order,pseudo-second-order and Elovich. From the data, it is established that the pseudo-second-order and Elovich models show a better adjustment, so that the adsorption in the material occurs on two adsorption sites and that such process is related to chemical adsorption. The maximum adsorption capacity of Cr (VI) was found at a condition of 0.0306 g, 0.6775 mm and 55°C at a time of 420 min establishing the efficient use of plantain peels for the removal of the ion metallic in the studio.Más... Ítem Pore Structure Characteristics and Gas Storage Potential of the Cretaceous La Luna Formation, Middle Magdalena Valley Basin, Colombia(Universidad EAFIT, 2020-06-19) Casadiego-Quintero, Efraín; Rios-Reyes, Carlos Alberto; Fundación Universitaria Agraria de Colombia; Universidad Industrial de SantanderMás... The rocks of interest in the present study (mudstones) show inherently a heterogeneous pore-size distribution in the matrix. They can present organic and inorganic pores and the transport mechanism through pores is different, and, therefore, it is necessary to describe their organic and inorganic porosity. This work uses different microscopy techniques to characterize mudstones from the Galembo Member of the Cretaceous La Luna Formation, Middle Magdalena Valley Basin, Colombia. These rocks present several pore types, including interparticle pores due to flocculation of clay minerals, organoporosity due to burial and thermal maturity, intraparticle pores from organisms, intraparticle pores within mineral grains, and microchannels and microfractures. The existence of interconnected pores in such complex fracture-pore system provides effective pathways for primary gas migration and it also provides a storage space for the residual hydrocarbon in mudstones, which is important for the primary migration and storage in gas reservoir rocks. The pore connectivity is high and increases towards the top of the sedimentary sequence.Más... Ítem Correlation of Morphometric Variables for Landslides in the Combeima River Basin, Colombia(Universidad EAFIT, 2020-06-19) Santa-Ramírez, Gabriel; Cuevas-González, Juan; Leal-Villamíl, Julián; Muñoz-Ramos, Jader; Universidad del TolimaMás... This study was carried out in order to estimate the morphometric variables of the landslides found in Combeima river basin (Tolima, Colombia) and obtain possible statistical correlations. To obtain the morphometric characteristics of the landslides, we used a database with historical landslides, a RapidEye image from 2010 and an orthophotomosaic from 2009, where the landslides were visually identified. The morphometric characteristics were defined through a geographic information system and bivariate analyzes were ran between the morphometric variables to establish their correlations. The results allowed to identify 121 landslides, with an average area of 1,974.97 m2 and Birnbaum-Saunders type distribution. It was found that the slip area morphometric variable correlates with the total length (R2=0.9414), the length of the center line (R2=0.9368) and the width of the surface of rupture of this (R2=0.8915). These data could be used to infer the volume of the mass involved in the event and its potential effects . This result would allow the landslide area to be used as support in decision-making in the planning of the territory in the Combeima river basin.Más... Ítem Design of a Low Cost Control System for an Astronomical Observatory(Universidad EAFIT, 2020-06-19) Cuartas Restrepo, Pablo; Gaviria-Gómez, Natalia; Galvez-Serna, Julian; Universidad de AntioquiaMás... This work shows the engineering process carried out for the design of a low cost control system for an astronomical observatory. The work describes the implementation to adapt the equipment of the observatory to a Master Control System (MCS) and be able to use it remotely. The instruments and software required for the integration of the equipment as part of a robotic observatory are also described.Más... Ítem Modeling the Availability of a Repairable Series Structure with two Units(Universidad EAFIT, 2020-06-19) Rodríguez-Figueredo, Liliana; Calvache-Archila, Álvaro; Universidad Pedagógica y Tecnológica de ColombiaMás... When there is a structure with two serial components where each one owns a life time that is distributed exponentially and both of the components are repairable, it is established a renovation process, in which both components need to be working in order for the operation of the structure. It is observed that the renovation process evidences a semimarkovian behavior and it is shown that through this one, its availability function is one of the inquiries of a system of integral equations that is solved by a numerical method designed for that purpose. The novelty in this article is that it is considered a process whose state space includes repair time, which is useful in engineering applications.Más... Ítem Dπ-optimal designs for heteroscedastic nonlinear models: A robustness study(Universidad EAFIT, 2020-06-19) Patiño-Bustamante, Catalina; López-Ríos, Víctor; Universidad Nacional de ColombiaMás... Optimal designs are used to determine the best conditions where an experiment should be performed to obtain certain statistical properties. In heteroscedastic nonlinear models where variance is a function of the mean, the optimality criterion depends on the choice of a local value for the model parameters. One way to avoid this dependency is to consider an a priori distribution for the vector of model parameters and incorporate it into the optimality criterion to be optimized. This paper considers D-optimal designs in heteroscedastic nonlinear models when a prior distribution associated with the model parameters is incorporated. The equivalence theorem is extended by considering the effect of the prior distribution. A methodology for the construction of discrete and continuous prior distributions is proposed. It is shown, with an example, how optimal designs can be found from the constructed distributions with a greater number of experimental points than those obtained with a local value. The efficiency of the designs found is very competitive compared to the optimal local designs. Additionally, prior distributions of a scale family are considered, and it is shown that the designs found are robust to the choice of the prior distribution chosen from this family.Más... Ítem A Survey on Some Algebraic Characterizations of Hilbert’s Nullstellensatz for Non-commutative Rings of Polynomial Type(Universidad EAFIT, 2020-06-19) Reyes, Armando; Hernández-Mogollón, Jason; Universidad Nacional de ColombiaMás... In this paper we present a survey of some algebraic characterizations of Hilbert’s Nullstellensatz for non-commutative rings of polynomial type. Using several results established in the literature, we obtain a version of this theorem for the skew Poincaré-Birkhoff-Witt extensions. Once this is done, we illustrate the Nullstellensatz with examples appearing in noncommutative ring theory and non-commutative algebraic geometry.Más... Ítem The Notions of Center, Commutator and Inner Isomorphism for Groupoids(Universidad EAFIT, 2020-06-19) Ávila, Jesús; Marín, Víctor; Universidad del TolimaMás... In this paper we introduce some algebraic properties of subgroupoids and normal subgroupoids. we define other things, we define the normalizer of a wide subgroupoid H of a groupoid G and show that, as in the case of groups, this normalizer is the greatest wide subgroupoid of G in which H is normal. Furthermore, we provide definitions of the center Z(G) and the commutator G' of the groupoid G and prove that both of them are normal subgroupoids. We give the notions of inner and partial isomorphism of G and show that the groupoid I(G) given by the set of all the inner isomorphisms of G is a normal subgroupoid of A(G), the set of all the partial isomorphisms of G. Moreover, we prove that I(G) is isomorphic to the quotient groupoid G/Z(G), which extends to groupoids the corresponding well-known result for groups.Más...