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

Objective: To evaluate the dissolved oxygen (DO) transfer rate in a Low Speed ​​Surface Aerator - LSSA, varying the power; and propose a geometric modification of the impellers, to improve the Standard Aeration Efficiency (SAE). Methodology: An LSSA was modeled through CAD software, and 3 LSSA prototypes were built, through a 3D printing process, modifying the original geometry of the impeller. Then pilot scale tests were carried out, using the LSSA coupled to a gear motor capable of generating 210 RPM. Finally, the oxygen transfers coefficients and the water aeration efficiency of the LSSA were determined by means of a mathematical model. Results: From the projections obtained, it was established that the proposed geometric modification increases the SAE by 20.3% and 29.8% for powers of 1 and 2 watts (W), respectively; keeping the standard oxygen transfer rate (SOTR) almost constant; furthermore, the proposed geometric shape and arrangement of the impellers seems to favor the contact time between the gas phase (air) and the liquid phase (water), improving the residence time of the trapped bubbles, evidence represented in the coefficients kLa (h-1). Conclusions: According to the results, it can be inferred that these LSSA type aerators can be optimized with a more efficient design, allowing to reduce the energy consumption associated with their operation, without penalizing the transfer of DO.

Objective: The main objective of this work was to determine the physical-mechanical properties of the waterproofed Compressed Sand Block (BTC) measuring 15×10×30 cm with two holes of 7 cm of diameter, with the recycling of crushed asphalt. Methodology: The design of raw material mixtures was carried out with the addition of 3 different percentages of crushed asphalt recycling (3, 6, and 9%), taking into account the parameters of the NTC-5324 standard for the characterization of the physical-mechanical properties. In this way, the blocks were subjected to absorption, load capacity, durability, and erosion tests. Results and conclusions: The results showed that compressed sand blocks are sustainable alternatives, with improved properties through the addition of recycled materials (crushed asphalt), thus reducing the vulnerability of the blocks to changes in humidity in regions where the blocks are required to masonry for construction are suitable for these types of environments.

Objective: Propose the analysis and monitoring of a chemical process sustained in the theoretical principles of a factorial method cataloged as principal component analysis (PCA), whose ultimate objective is to represent the original variables of the system. Methodology: Methodologically the data was analyzed in a more compact dimensional space, under the hypothesis of multivariate normality. A control chart based on the error prediction squares is constructed in the later phase to monitor the behavior of the successor variables once the ACP has been applied. Results: The results of the univariate control charts constructed from the t-scores of the individual components, in which the behavior of the variables contributing to the generation of alarm signals is exhibited, can be used as the basis for an auxiliary analysis based on the results provided by the univariate control charts. Conclusion: The results obtained corroborate that the three retained components explain a majority fraction of the original variability of the data cloud and that the control chart constructed from the sub-dimensions registers the existence of outliers or extreme values.

Objective: Implement a monitoring and control system with IoT technology to determine the behavior of environmental variables in poultry farming. Methodology: The research project is comprehensive, formally experimental and field explanatory type, consists in the implementation of a powerful wireless network based on LoRa technology for Internet of Things (IoT), the study of the physical variables that influence the breeding and production in an experimental farm with low energy consumption and affordable devices is carried out by means of gateway that sends data to the cloud through the transport protocol for message queuing (MQTT), such data are processed by the microcontroller that captures, sends and processes them with the help of a radio terminal station and sends them in real time. Five phases are established: identification of environmental variables, network design, programming, system testing and analysis and results. Results: Finally, an analysis of the data on how physical and environmental conditions can affect the process of poultry rearing in a confined environment is performed. Conclusions: The process of integrating devices and sensors with emerging technologies facilitates the poultry automation process to record and visualize the behavior of environmental conditions and allows centralizing the information with remote monitoring, reducing the costs of maintenance and monitoring the health of the animals, a situation that in the future will allow the technification of poultry farms.

Objective: Propose a measurement model within an IoT architecture, in order to establish which quality characteristics are the most convenient and necessary for the object network, taking as a reference the ISO / IEC 25000 hierarchical model of software quality. Methodology: For the design of the model, a systematic literature review was carried out that allowed obtaining evidence from scientific articles stored in digital repositories in order to quantify the quality attributes and determine the ideal metrics. As a starting point, a series of research questions and a survey were conducted with a group of experts with knowledge in IoT to determine which quality characteristics and sub-characteristics meet the necessary requirements. Results: It was evidenced that the results and resolution of research questions posed as well as the survey carried out by the group of experts for the validation of the model respond to the necessary criteria for a quality model. Furthermore, in order to facilitate the understanding of the model proposed here, a graphical representation is made by means of pre-conceptual schemas. Conclusions: Finally, such model it provides external metrics to measure attributes of quality characteristics in any area of ​​the IoT.

Objective: To design and develop a continuous simulation model based on System Dynamics to analyze reproductive parameters considering artificial insemination and reproductive policies aimed at sustainability in a dairy herd. Methodology: The procedure is classified into four stages: (I) Analysis of the behavior of the dairy herd and definition of the problem, (II) Description of processes and contextualization of a model, (III) Generation of the preliminary model, verification, validation and (IV) Analysis of results. Results: It was shown that using simulation tools it is possible to model the processes within the dairy herd. The effective detections of periods of heat constitute a determining factor in the application of policies of artificial insemination and in general in the sustainability of the herd. Therefore, using a reproductive biotechnology protocol, such as heat synchronization and fixed-term artificial insemination, are policies that mitigate the problems associated with reproductive problems. Conclusions: The use of system dynamics allowed us to have a holistic approach to the problem considering all the relevant variables to evaluate improvement policies. The model presented in the development of the research allowed evaluating different policies associated with animal management, meat exploitation in dry cows, and policies of continuous review on situations associated with the efficiency in the identification of cows in heat.

Objective: Identify the barriers in the management of the green supply chain in organizations. Methodology: A research scheme was systematized that included a search equation and exclusion criteria. The SCIENCE DIRECT database was used, where 1052 articles were found, of which 27 research articles were selected after applying the exclusion criteria and carrying out the review and selection process of these. Results: 57 barriers that occur in the different industries and organizations were characterized when implementing the green supply chain management, which were classified into 8 categories: financial, administrative or managerial, knowledge, technology and innovation, suppliers and customers , governmental, legislative and social and infrastructure; having as main barriers and more frequently the lack of commitment on the part of senior management, the information gap, insufficient social pressure, deficient legislation, costs and financial limitations that directly impact the management of the green supply chain. Conclusions: Based on the results of the research, it is concluded that there are multiple barriers to implement sustainable practices in the supply chain, which indicate the complex path to sustainability and that requires the effort and participation of all the actors involved in the supply chain. supply directly and indirectly, as well as external actors to organizations such as governments. Likewise, this research contributes to reducing uncertainty in the process of applying sustainable practices.

Objective: In this research, a load sled for equipment and supplies in the oil and gas sector was designed and simulated. Methodology: Initially, the geometry of the sled was defined based on the established restrictions, in which the magnitude and place of application of the forces in-service conditions were evaluated. Subsequently, the Pugsley method was used to find the safety factor to avoid static failure as a result of the application of loads. The geometric model, the discretization, and the simulation under estimated loads were generated using the finite element method and the computational resources of CAD/CAE software. Results: Finally, the results of the analysis were represented through stress, deformation, and safety factor plots, comparing with Pugsley's method to define the load to be carried by the structure. Conclusions: 2000Kgf was defined as the maximum load since it guarantees the safe use of the sled.

Objective: To implement the Kalman Filter for estimating the effective reproductive number R_t of CoViD-19 in Colombia and some of its most affected departments and cities, based on the observations of infected people reported by the National Institute of Health. Methodology: The tracking of R_t begins with the calibration and recalibration of the recovery rate by solving an optimization problem. Then, a heuristic is used to determine the covariances of noisy disturbances present in the model of R_t. Next, the Kalman Filter is applied to obtain realizations of the optimal estimate of R_t. Finally, Monte Carlo simulation is implemented to produce the mean trajectory of the optimal R_t with a confidence interval of 95%. Results: The tracking of R_t for the CoViD-19 was carried out in the departments of Atlántico, Antioquia and Valle del Cauca, the cities of Barranquilla and Bogotá, and in general in Colombia, in the periods of time determined by the peaks of infections that each particular territory experienced, showing coherence with the reality that each one suffered. Conclusions: The method to obtain the R_t that was used in this research provides an estimate of this number that is closer to reality compared to the calculation obtained from the deterministic SIR epidemiological model.

Objective: This article developed a modular type mechatronic system that allows the physical experimentation of the conveyor belt concept as part of an industrial manufacturing process. Methodology: The methodology that was used was "Design Thinking" with the purpose of making a prototype with additive manufacturing technologies using FDM type 3D printing. The mechanical design used FreeCAD, the firmware development was done for an Arduino Mega and the control software in Java language was developed in the Netbeans IDE. Results: The conveyor belt generated 22 mechanical parts assembled by direct couplings without screws, it used 406.1 g of PLA as material to print and it took 83 hours and 36 minutes of effective machine work. The operation of the band integrated to the electronic devices allowed the detection and classification of 6 colors in objects of 35 mm of edge. This is a system comparable to the Fischertechnik conveyor belt basic kit, but with the advantage that it can be replicated, expanded and optimized in each of the parts, because the entire design is available for free download. Conclusions: The development of low-cost and fully functional applications in Industry 4.0 was promoted with the use of 3D printing for the emulation of industrial processes, which can be part of the trends of educational innovation at different levels of schooling.