Tecnura

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Authors: Diego Alejandro Cowes, María Laura Salgán, Juan Ignacio Mieza, Martín Pedro Gómez

Contexto: La caracterización geoquímica de ma-teriales arqueológicos de obsidiana o vidrio volcá-nico, utilizado en el pasado para la confección de herramientas líticas, permite trazar su procedencia geológica e inferir formas de interacción y rangos de movilidad de antiguas poblaciones humanas. La caracterización de la composición geoquímica de la obsidiana por análisis de activación neutrónica per-mite determinar con un buen grado de certidumbre su procedencia; sin embargo, es una técnica costosa y destructiva, por lo que no es recomendable para piezas arqueológicas. Otras técnicas más accesibles como la fluorescencia de rayos X o la espectrometría de masas con plasma acoplado inductivamente han sido utilizadas con éxito para esta aplicación pero con un mayor nivel de incertidumbre. En este traba-jo se busca asistir al problema por medio del uso de otras técnicas no destructivas que pudieran ser apli-cables al patrimonio arqueológico Método: Se exploraron las propiedades mecánicas de una muestra de obsidiana a través de métodos de ultrasonido. Se evaluaron la velocidad de fase y ate-nuación de ondas longitudinales, y se cuantificó la densidad de las muestras por picnometría de gases, que posibilita determinar los módulos elásticos di-námicos. Además, se repitieron las mismas medicio-nes en probetas de vidrio de manufactura industrial Resultados: Se observó que la velocidad, la densi-dad y el módulo longitudinal son mayores para la muestra de vidrio industrial que para la muestra de obsidiana. Por otro lado, la atenuación resultó ser mayor para el caso de la obsidiana y se observó una mayor dependencia con la frecuencia. Conclusiones: Los resultados obtenidos demues-tran la capacidad del método para distinguir entre materiales con composición química diferente, por lo que sería viable para ser aplicado a estudios ar-queológicos. Además, las diferencias observadas en la atenuación muestran que el método también es sensible a la microestructura del material, por lo que aportaría información no accesible mediante técni-cas convencionales de arqueometría

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Authors: Edgar Orlando Ladino Moreno, César Augusto García Ubaque, María Camila García Vaca

Context: The article presents the friction coefficient calculation for pressure pipes, from Newton-Raph-son numerical method, under JavaScript source code for Android 4.0 or higher Methodology: The code development is based on Co-lebrook-White model for turbulent flows. The app also establishes the friction coefficient for laminar flows from the Poiseuille equation and determines the range for the enter flow in a transition zone (unstable flow). An algorithm of successive approximations was im-plemented for non-linear equation solution based on the relative roughness and Reynolds number. Results: In the Newton-Raphson method, if the ini-tial value moves away from zero or presents diffe-rent inflection points, the probability of divergence of the method increases significantly. To overcome this anomaly, a friction coefficient equal to 0.015 was proposed as initial (seed) value; thereby we gua-rantee the convergence for turbulent flows with an approximation of 0.0000001. The values calculated by the app were calibrated with the Excel analysis tool (Goal Seek). Conclusion: The app is available for free in GooglePlay Store, and is a tool to support educational pro-cesses and the professional field.

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Authors: José Soto Mejía, Guillermo Roberto Solarte Martínez, Luis Eduardo Muñoz Guerrero

Context: This research solves the problem of finding the optimal location point for a fleet of garbage co-llection vehicles, as well as their optimal routes in order to minimize the cost of garbage collection in 144 neighborhoods of the municipality of Dosque-bradas, Risaralda, Colombia, using 8 vehicles with homogeneous capacity of 25 tons which belong to the company Serviciudad. Methods: Firstly, a scanning heuristic (Ospina Toro, Toro Ocampo, & Orrego Cardozo, 2016) was used to find a good point of departure for the group of all the vehicles in order to generate good-quality initial routes. Then, these initial routes feed the modified genetic algorithm of Chu-Beasley (Solarte Martinez, Castillo Gaspar, & Rodriguez, 2015), taking into ac-count the load capacity of the vehicles. Finally, in search of an optimal result, the best result found in the previous step is treated again with a Tabu meta-heuristic (Bodas López, 2017). Results: A new methodology was designed and ca-lled hybrid CSGTR (Clustering, sweep, genetic y tabú routing), which allows to take advantage of clustering before vehicle routing (Rueda Bayona, Elles Pérez, Sánchez Cotte, González Ariza, & Ri-villas Ospina, 2017) and includs Heuristic models such as Scanning Technique and Metaheuristic mo-dels like the Chu-Beasley’s and Tabu Algorithm. The application of the CSGTR methodology allowed to reduce the time and costs of the routes of garbage trucks in the municipality of Dosquebradas, Risaral-da, Colombia. Conclusions: The hybrid methodology CSGTR, to solve the problem of location of vehicle fleets and generation of collection routes, is presented as an alternative approach with better results than the pre-vious approach.

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Authors: Eddy Roberto Cuty Clemente, Antonio David Mejía Regalado

Context: Among the sources of biodiesel, waste coo-king oil is a potential alternative fuel to reduce the emission of greenhouse gases from diesel engines without considerable technological changes Method: In this study, the experiments were perfor-med under stable conditions on a single-cylinder four-stroke diesel engine using three different blends of pure diesel fuel with biodiesel made from was-te cooking oil (B10, B20 and B30) and commercial diesel fuel B5. The engine ran at variable speed be-tween 1000–1600 rpm, at full load and variable en-gine loads corresponding to the effective power at 1600 rpm. Results: The experimental results show that smoke opacity of B10, B20, and B30 is lower compared to the commercial B5 at 0.3%, 24% and 46% respec-tively, when evaluated at nominal speed 1600 rpm and at full load. However, by increasing the engine load at a constant speed of 1600 rpm, smoke opacity reached its maximum value with B20 compared to other fuels used. Conclusions: It is feasible to use biodiesel made with waste cooking oil in blends with pure and commercial diesel to reduce the effects of toxic emissions such as particulate matter (soot) of die-sel engines on the environment. Therefore, recycling waste cooking oil significantly reduces environmen-tal problems.

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Authors: José Antonio Valero Medina, Beatriz Elena Alzate Atehortúa

Context: Nowadays, the images of the Earth surface and the algorithms for their classification are widely available. In particular, the algorithms are promising in the differentiating of cotton crops stages, but it is necessary to establish the capabilities of the different algorithms in order to identify their advantages, and disadvantages. Method: This paper describes the assessment process in which the Support Vector Machines (SVM) and random-forest technique (decision trees) are compa-red with the maximum likelihood estimation when differentiating the stages of cotton crops. A RapidEye satellite image of a geographic area in the municipa-lity of San Pelayo, Cordoba (Colombia), is used for the study. Using a set of sampling polygons, a ran-dom sample of 6000 pixels was taken (2000 training and 4000 for validating the classifications.) Confu-sion matrices, and R (data processing and analysis software) were used during the validation process Results: The maximun likelihood estimation presen-ted a correct classification percentage of 68.95%. SVM correctly classified 81.325% of the cases and the decision trees correctly classified 78.925%. The confidence test for the classifications showed non-overlapping intervals, and SVM obtained the highest values. Conclusions: It was possible to confirm the supe-riority of the technique based on support vector machines for the proposed verification zones. How-ever, this technique requires a number of classes that comprehensively represent the variations of the im-age (in order to guarantee a minimum number of support vectors) to avoid confusion in the classifi-cation of non-sampled areas. This was less evident in the other two classification techniques analysed.

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Authors: Álvaro Ervey Pulido Aponte, Hernán Mauricio Rivera Escobar, Jhon Jairo Espitia Pardo

Introduction: In Colombia, bovine ruminal content (BRC) is generally poured into water courses and open fields and, given its high organic load, its final disposal represents an environmental, economic, and social threat. To date, the implementation of te-chnologies that reduce the impact is limited. This is due, on the one hand, to the scarce characterization of the BRC, which is required for the construction of mathematical models of anaerobic digestion that explain the reduction of this bio-solid; and on the other hand, to the restricted application of control and supervision systems focused on the generation of by-products with potential use. Aim: To document the methods used in the develo-pment of control and monitoring system ot tempera-ture and pressure, for a discontinuous bio-digester at laboratory scale with biomass BRC Methods: The implementation of a distributed signal acquisition system and a web server interface were carried out; additionally, a dynamic model corres-ponding to the behavior of the anaerobic digestion system for this BRC biomass was identified Results: Using gravimetry and calorimetry, it was possible to characterize variables associated with the anaerobic digestion system with BRC. As for the control, the on-off controller kept the gas pressure in the desired range and the PI controller guaranteed the desired temperature of the process. Conclusion: It was possible to generate biogas from biomass BRC from basic schemes of characteriza-tion, supervision, and control of the process

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Authors: Edgar Orlando Ladino Moreno, Germán Ricardo Santos Granados, César Augusto García-Ubaque

Context: Describing mathematically the hydrau-lic behavior in control structures leads to nonlinear coupled differential equations, which do not have analytical solution in the majority of engineering problems. However, it is possible to obtain approxi-mate solutions from the finite volume method (FVM). This method converts a continuous medium with in-finite variables into a discrete medium with establi-shed geometries and certain boundary conditions. Methods: Using the Ansys Fluent 17.0 software, a 1:70 scale 2D numerical model was developed wi-thout considering the effect of stacks and abutments on the weir under permanent flow conditions of the control structure and the radial gate system of the El Quimbo dam. The hydrodynamic analysis of the structure was carried out under free surface condi-tions and with different hydraulic loads, for openings of 704 meters above sea level, 706.9 meters above sea level, 709.4 meters above sea level, 712 meters above sea level and 724.6 meters above sea level. Subsequently, the numerical model was validated based on the comparison between the numerical re-sults and the theoretical data made by both Ingetec and the tests in the physical model developed by the National University of Colombia in Manizales. Results: For a return period of 100 years, the numeri-cal model estimated a sheet of 0.0306 m correspon-ding to 2,143 m in the El Quimbo structure. With this arrangement, 80.7996 Liters per second entered the control volume and 80.7324 Liters per second left, gi-ving rise to a variation of 0.08316%. The largest water sheet variation of the numerical model with respect to the observed sheet is 3.1% (0.258 m), which co-rresponds to the increasing probable maximum for an opening of gates with elevation (724.6 m) and with a discharge of 290 lps. Similarly, the higher speeds developed by the flow in the landfill originate at the exit of the deflector, corresponding to the abscissa K0 + 5,19 m. According to the numerical model, it was determined that the impact of the jet in the channel is made with a maximum speed of 6.15 m/s. Conclusions: The relation between the hydraulic load with respect to the design load must not exceed 1.33, which agrees with that recommended by the USBR. Also, the cavitation condition found in the fast can be considered incipient cavitation. In land-fill design, the H/HD ratio directly affects the appea-rance of cavitation phenomena on the structure, the development of high velocities in the fast, the deflec-tor, and the discharge capacity of the landfill.

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Authors: Mauricio Becerra Fernández, Mauricio Milton Herrera Ramirez

Context: Capacity planning is one of the critical ele-ments in business decisions at any level since it is possible to respond to the fluctuating needs of the market through its correct configuration and alloca-tion. As in most decisions in the field of Industrial Engineering, in the processes of planning and pro-gramming of the capacity of the productive systems, there are some aspects that cannot be left aside: the costs related to each configuration, the relationship between the variables of allocation of resources, and the response to the requirements of the clients; these constitute the basis of the models applied in the pro-cesses related to the capacities in the organizational systems. Method: A model was developed using systems dy-namics, which allows to determine the number of personnel to respond to changes in demand; the best use of the capacity of the resources assigned to the service provision was sought according to the profi-tability of the business unit; and the behavior of the demand for services was simulated based on histori-cal data on the behavior of the system. Results: The proposed model allows to identify the capacities, and their respective calculations, invol-ved in the modeling. In addition, it is possible to contrast the behavior of the model (which seeks to maximize the use of available capacity by seeking the best configuration in the allocation of resources) without neglecting the profitability of the operation. This is of interest for the planning of the system, con-sidering the costs associated with the underutiliza-tion of the work force or the insufficient provision of the service to the client. Conclusions: The model presented in this research is a proposal for the analysis of operational capaci-ties in service providers that have several variables to consider, such as the use of human resources, the demand for diverse services attended by specialized personnel, different work days, and the use of spe-cific facilities. The search for the best configuration of the resources involved in this service provision allows companies to continually inquire about ob-taining better rates of use and profitability.

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Authors: Daniela Arias Lamos1, Laura Natalia Montaño Díaz, María Alejandra Velasco Sánchez, Jader Martínez Girón

Context: A study was made about the bioactive compounds of certain foods, while taking into ac-count the benefits they generate to human health Method: This article presents a bibliographic review of the different applications of functional foods and their application in agroindustry Results: It was found that bad eating habits can ge-nerate a deficit in the requirement of bioactive com-pounds important for the proper functioning of the organism. On the other hand, the demand and the trend of consumption of functional foods is getting bigger due to the multiple benefits and potential uses that can be obtained from them, along with the basic nutritional needs they cover. Conclusions: There is evidence of interest in conduc-ting new studies about obtaining this type of food. For this, new ingredients should be incorporated in food matrices, in order to preserve the bioactive compounds and that they perform their main func-tion (apart from nourish): to reduce or control va-rious diseases that may be chronic in some cases.

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Authors: Omar Iván Trejos Buriticá

Context: This article presents and analyzes the re-sults of a research carried out in a classroom, in the context of the learning of functional programming at university level in Systems Engineering and Com-puting program, from the application of the types of mathematical thinking and their use in the DrRacket programming language. The purpose was to establi-sh links between the types of mathematical thin-king and computer programming (for first-semester students). Methodology: For the development of the research, we worked with a group of first-year students, appl-ying the proposed methodology of mathematical thinking. The evaluations, based on the types of ma-thematical thinking, were made in another group that was receiving the subject by conventional methods. In this group only the evaluative tests were carried out; no monitoring of their learning was done. Results: The results show great advantages when ar-ticulating mathematics and computer programming within the context of a subject that gives meaning to both areas. Conclusions: It is concluded that functional pro-gramming is learned in an easier way when it is re-lated to the types of mathematical thinking and vice versa.

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Authors: Natalia Judith Marchevsky, Andrea Alejandra Giubergia, Néstor Hugo Ponce

Context: Environmental impact studies (EIS) are im-portant tools since they allow forecasting the conse-quences of the development of an extractive activity in the environment that surrounds it. The objective of this work is to perform the environmental impact as-sessment of “La Represa,” a flagstone quarry located in San Luis Province, Argentina Method: A double-entry matrix was used to assess the environmental impacts in the environment affec-ted by extractive activities. This matrix considers cer-tain qualities of environmental liabilities that are introduced in a function to generate an index ca-lled “Importance of Environmental Liability” (IM). By comparing these indices, it is possible to deter-mine the environmental impacts that are critical for the studied environment. Results: The analysis allowed to determine that the landscape is the only environmental element that has a critical negative impact in the vicinity of the exploitation of the quarry. However, there was evi-dence of an important improvement in the quality of life of the inhabitants of the area from this mining undertaking. Conclusions: The exploitation of flagstone is essen-tial for the maintenance of several families in the village of Riocito. However, it is advisable to take measures that can amortize the negative effect on the landscape of the place. This paper proposes some re-mediation and restoration options that could be im-plemented during and at the end of the operation.