Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Context:  The process of digitizing wood samples for identification and study has become relevant over the past decade, so it is necessary to consider the photographic aspects that generate representation of the images with respect to the physical sample. Method: Ten woodable species were used with no less than 10 sampled trees, from each individual five 10 mm edge wooden cubes were ex-brought and photographed with a stereoscope with a 20X  under four luminosity protocols. In the process, the variation in color (under the coordinates L*, a* and b*), color differential (E*) and chroma (C*), in addition to the density and diameter of vessels, was evaluated. Results: The results showed that the brightness of 50% showed the greatest similarity to the colorimetry of the wood, obtaining values of E* less than 6 in all species and values of C* within the optimal range of 5 to 7. With respect to the anatomical part, the same behavior was given with the ten species, finding that the luminosity treatments at 25 and 50 % showed no significative differences, while the luminosities of 75 and 100% tended to underestimate the value. Conclusions: The treatment luminosity at 25% is ineffective by the darkening of the surface, while exposures to 75 and 100% tended to clarify the surface area and underestimate anatomical characteristics.

Context: The analysis of the complexity of the systems involves the evolution of the models that representation of reality, logistics has advanced from a business context to the supply chain, basic models of logistics with deterministic parameters must go represent real behavior, stochastic. In this context, the combination of inventory, location and routing models with a stochastic approach applied to supply chains appears. Method: A systematic review of the literature was developed in the bibliographic databases, ScienceDirect, ScholarGoogle, SpringerLink, Scopus, SemanticScholar, ResearchGate and Scielo, of the 72 referenced articles, 65 % between 2015 and 2019. Results: From the models identified and described, a taxonomy of the models is proposed and classified into 4 kinds, three dyadic models Location Inventory Problem (LIP), Inventory Routing Problem (IRP), Location Routing problem (LRP) and a triadic model Location Inventory Routing Problem (LIRP). The stochastic parameters used in the models, the types of models, the solution methods, the contemplated objective functions, and the number of echelons in the supply chain are established, from which taxonomies of the different types of models are proposed. Lines of work for future research is presented. Conclusions: The evolution from deterministic to stochastic models represents an increase in complexity which forces the development of new solution methods with ability to find feasible solutions. The development of models with news measurements of performance as environmental, social and humanitarian have been of recent interest. In the last period, triadic multi-product and multi-period models take on relevance.

Context: Cash flow is an essential element for decision-making within organizations, since knowing the cash flow of a period can determine if profits or losses are being generated. Therefore, it is vitally important to know the behavior of the cash flow to reduce the risk of presenting future cash deficits. Method: Se A bibliographic review was carried out identifying characteristics and variables that intervene in the cash flow of a common organization. In addition, a model is proposed that allows representing the behavior of cash flow in organizations using the variables found in the bibliographic review and which is developed using system dynamics. Results: A model was developed that is developed through system dynamics in which the cash flow variables are integrated, and in turn, allows the creation of simulation scenarios in which the cash flow variables are modified and the behavior of the flow is determined cash on time. Conclusions: With the correct parameterization of variables, using real figures and statements, it is possible to use the proposed model as an experimentation platform to evaluate the impact of implementing different policies aimed at maintaining the level of cash flow and evaluating its viability.

Context: Water treatment as an industrial process requires energy for its operation, so, in order to supply the electrical energy that requires the heating of the room in which the dosing process of chemical products is performed, the exploration of alternative energies was proposed through the determination of the environmental and financial viability of a heating system, which uses the heat of the thermal water from the Nevado del Ruiz volcano that reaches the Luis Prieto Gómez Plant. Method: A mixed type research was conducted by means of a field study to characterize the context of its use, a specialized advice to determine the heating system, and a bibliographic review to perform the financial analysis by cash flow, the environmental analysis by carbon footprint, and the sustainability of the proposal. Results: The context of the heat use was determined, and the thermal load required inside the room was characterized. Based on this characterization, it was established that a circuit system of tubular heat exchangers generated operational viability with an economic saving projection of 78 %, in comparison with a conventional system and a reduction of environmental impacts represented by a decrease of 3,25 annual tons of CO2 emitted into the atmosphere. Conclusions: The incorporation of energy sustainability for the generation of operating conditions for water treatment was achieved, starting from the conception of the use of thermal water as a renewable resource, together with the production of heat through a closed lifecycle, thus demonstrating a dialogue between the economic, environmental, and social spheres as required by sustainable development.

Context: Procurement is each time more important from the strategic point of view of the organizations. It has generated several tendencies in its management. The academic reflection about its evolution, from a traditional focus, which unique criteria of decision making is the cost, to achieve a level of strategic cooperation, invites to have an integral looked of this function in the supply chain context. Method: From the review of academic documents, we acquired relevant information and classified it in the issues antecedents, current state, and tendencies of the procurement function. These issues orientate the authors' reflections. Results: As two of the results of the reflection are the process transformation and the improvement of relationships with providers, achieving long term alliances needs; digitalization and its influence in the manner in which transactions occur; the validity of the purchasing analysis in maturity models; the integration present in the co-maker ship and the challenges related with sustainability and value recovering. Conclusions: Because of the strategic importance of procurement function to get competitive levels proposed by organizations, from the academic ambit, it should be a reflection and research permanent, especially about digitalization, dynamic supply chain, and sustainability. In this context, this document orientates the analysis related to advances in procurement function and present several of the future research topics in it.

Context: Micropiles are used as reinforcing or underpinning elements, a function that has been tested and analyzed by different authors. In Colombia, the use of this technique is limited to the geotechnics expert’s own concepts, which consists of empirical knowledge and successful experiences. Consequently, it is necessary to compile key variables and analytical and numerical methodologies for a better understanding of this technique. Method: This document presents a state of the art supported by articles and research aimed at analyzing and evaluating the behavior of micropiles as load capacity recovery elements in groups of piles with defects. Results: The findings identified in the consulted documents are synthesized as a theoretical support that will become a starting point for future research in this field of geotechnical engineering. Conclusions: It is possible to evidence that micropiles have a positive influence on the load recovery of existing foundations, thus demonstrating the importance of conducting field tests and analyses directly in Colombia, considering the specific strata of soils found in the country.

Context:  The imminent concern regarding greenhouse gas emissions associated with internal combustion engines has motivated both the industrial and academic sectors to propose reliable solutions in order to mitigate the adverse effects of thermal machines. Partial fuel substitution with biodiesel blends is a promising, convenient, and diverse technology that can contribute to minimizing emission levels. Method: This study incorporated an experimental test bench for a low-displacement diesel engine that enabled control of the operating conditions in order to evaluate thermal performance, fuel metrics, and emission levels. An algae oil biodiesel blend at replacement percentages of 5% (AB5) and 15% (AB15) was produced via a transesterification technique. The performance evaluation was centered on the impact of the variable compression ratio and torque ranges of the engine. Results: The implementation of algae oil as a biodiesel blend reduced the emission levels of CO, CO2, and HC by 40-95% compared to diesel standalone operation. In contrast, it boosted NOx emissions in a reasonable proportion (<45%). Further emission minimization of CO and HC could be reached by increasing the compression ratio, but CO2 and NOx emissions were negatively affected. Moreover, increasing the compression ratio intensified the combustion pressure while improving both fuel consumption and thermal performance. Contrarily, a higher algae oil content in the biodiesel blend reduced the in-cylinder pressure, thus increasing the fuel consumption and reducing the thermal performance. Conclusions: In conclusion, biodiesel implementation demonstrated to be a robust tool to mitigate the global emissions of the engine to a great extent. The negative results regarding thermal performance and fuel consumption are a consequence of the higher density and lower heating value. However, this can be partially offset by increasing the compression ratio of the engine. The exploration of hydrogen and hydroxy is strongly recommended to contribute to enhancing the overall performance of partial fuel substitution technologies.

Context: Battery modeling can be a complex activity if techniques based on chemical behavior are employed. To facilitate this, inverse modeling techniques have been used which are based on experimental curves and adjustments of circuit models. Different techniques are used for parameterization according to their complexity, accuracy, and convergence time.Method: This paper uses a particle swarm optimization algorithm to parameterize a dual-polarization model for a 18650-type lithium cell. The proposed methodology divides the problem into different optimization cases and proposes a localized search strategy based on the experience of the previous case.Results: The PSO algorithm allows adjusting the model parameters for each case analyzed. Dividing the problem by stages allows improving the global precision while reducing the convergence times of the algorithm. Based on the possible cases, it is possible to find the dynamics of each of the parameters as a function of the charge state.Conclusions: The proposed methodology allows reducing the parameterization times of the dual-polarization model. Due to the approximation generated by previous experiences, it is possible to reduce the swarm population and further decrease the convergence time of the process. Additionally, the methodology can be used with different optimization algorithms.

Context: The high consumption of pineapple worldwide requires that the market offer different commercialization alternatives, including minimally processed products. Undesirable changes in the product during storage can be reduced by its processing and packaging conditions. This work aimed to evaluate the effect of the type of packaging, the pretreatment, and the type of cut on fresh-cut pineapple quality parameters. Method: The pineapple was cut into 2 cm cubes and quarter slices of 1,5 cm thickness. Samples were stored in PET containers with or without an absorbent pad. The precooling of the samples was also evaluated. The quality properties of the fruit were evaluated during 14 days of storage. Results. The quarter slices showed less weight loss and maintained their color, vitamin C content, polyphenols, and antioxidant capacity, whereas the cut in cubes showed a better performance in terms of firmness. The use of absorbent pads accelerated the weight loss. Precooling did not show a significant effect in the response variables. Conclusions: The results obtained suggest that it is possible to maintain the quality properties of minimally processed pineapple of the MD2 variety when it is cut in quarter slices and packaged in PET containers, thus preserving the vitamin C content and phenolic compounds.

Context: Dissolved oxygen (DO) transfer is an important matter for water quality. Several devices have been designed to supply the required DO in some bodies of water during their treatment and restoration. However, these entail a high energy consumption, thus requiring the optimization of use parameters. Method: This work studies the effect of the power and number of paddles used in a horizontal axis aerator. Measurements were made on anoxic water samples using three mechanical aerating devices made up of 6, 12, and 24 paddles while varying the rotation speed from the supplied voltage. Results: The highest values obtained for the transfer coefficient KLa are reported by devices with a greater number of blades. Nevertheless, the Standard Aeration Efficiency (SAE) and the Standard Oxygen Transfer Rate (SOTR) efficiency reveal that the 6-paddle wheels are more energy-efficient. Conclusions: It is shown that DO transfer does not depend solely on the impacts associated with the number of paddles, and that the maximum transfer efficiency is obtained with a lower number of paddles. These results contribute to improving the understanding of the operation of these mechanical systems in terms of DO transfer.