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

In optimization problems, different algorithms can be used to find the right solution. But when it comes to problems of medium and high complexity, such as difficult NPs, techniques known as Genetic Algorithms (GA) have a hard time converging or coming up with a solution. This article presents the implementation of a Virus System (VS, for its acronym in English Virus System), which is developed with a new approach to solve optimization problems simulating the way an organism is attacked by a virus. The VS analogy is applied to two types of problems, Onemax, of different bit lengths and deceptive functions (Deceptive Functions) with the aim of checking their operation and their convergence power. This method is compared to a GA inspired by the growth of marine corals. The VS has managed to achieve high precision results, with 100% convergence in both problems and with considerable improvements compared to those obtained with the GA.

With the increasing use of wind energy, the need arises to modify electrical power systems, due to the lack of inertia that characterizes renewable generation. It is proposed to emulate the inertial response of wind turbines to mitigate these effects caused by a configuration that prevents it from reacting to failures in the electrical network. To validate what is proposed, the application of virtual inertia is studied in the Los Cocos, Larimar 1, and Larimar 2 wind farms, which represent the highest percentage of wind generation in the Dominican Republic. To analyze the effect of the proposed configuration on the stability of the Interconnected National Electric System, the Power Factory DIgSILENT software was used, where simulations are carried out under different load parameters to obtain the curves of variation of the electrical frequency against different values of the constant inertia when a fault occurs due to disconnection of a generating plant. To apply virtual inertia to wind turbines, power electronics are used to inject active power into the electrical grid when a fault occurs in the electrical system. A dynamic model is developed based on the ROCOF (Rate of Change of Frequency) control whose objective is to inject active power into the system depending on the frequency variation. Performing simulations, it is found that applying virtual inertia greater stability is obtained in the electrical system and less chance of a possible collapse of the electricity system.

Nurses tend to perform multiple tasks simultaneously, the medication tasks being the most frequent where they transport heavy carts, which usually generates ex-haustion and causes a decrease in the quality of their work. The objective of this article is to develop a simulated prototype of a robot capable of following nurses during their journey on a flat surface, lightening their workload. This robot must be capable not only of following a particular person identified by means of an aruco marker on the back, but also have the ability to obtain information from the environment around them while following the person to act on environmental changes, and following the target even when disappearing from his vision zone momentarily when turning at different corners. The input of the system is the im-age of the marker, the coordinates of the center in pixels and distance to the ro-bot are computed by the identification algorithm. If the person is present, a P and PD controller is used for following. In case the user disappears for some reason from the camera, the robot makes a local path planning to the last global coordinate of the person extracted using the monocular camera and then a search system. The planning parameters are modified to pass through a door, this recognition is achieved through the YOLO v3 convolutional network. The localization of the robot is determined with the wheel odometry and when the target user gets around corners, the direction in which it was moving is deter-mined in order to follow it again. To analyze the performance of the proposed system, the CoppeliaSim software was used with the Pioneer 3-DX robot model, where various simulations are carried out under different scenarios to which the robot would actually be exposed.

Sustained oscillatory behaviors can emerge in both chemical and biological systems, although more frequently in the latter. In metabolic pathways, periodic oscillations to which functional importance is attributed to have been observed with periods of the order of minutes. This biochemical rhythmicity can be explained through the existence of an allosteric enzyme, which is considered the origin of the system's structural instability, promoting its evolution towards non-stationary dynamics such as sustained oscillations and chaos. This article presents a simple kinetic model of a hypothetical 4-step linear metabolic pathway with a positive feedback loop. The model allows the simulation of periodic behaviors for analyzing their triggering factors and underlying mechanisms. The oscillations arise due to the positive feedback for a narrow range of the inlet flux. The amplitude of the oscillations in metabolite concentrations depends on the oscillator’s distance, kinetic constants’ value, and the inlet flux. Under forced oscillatory inlet fluxes, more complex behaviors arise.

This article studies the possibility of compensating reactive electrical power (kVAr) in photovoltaic systems to reduce or cancel the surcharges caused by low power factor, since they represent an additional cost in the electricity bill. To compensate for the reactive electric power consumed in electrical systems it is necessary to use elements that produce this type of reactive power, so in this study we propose a method that compensates the reactive electric power demanded from the network next to the system Photovoltaic installed. The selected method was chosen based on studies between different technologies in the field of reactive electric power compensation such as inverters, capacitor banks among others, in addition, an electrical network analyser was used to record the behaviour of the connected load and thus evaluate The effectiveness of this method, when evaluating trends in reactive power consumption before and after implementing the selected method. The proposed method is applied in a real installation and its effectiveness is supported by economic savings by improving the power factor and by environmental savings by achieving a reduction in CO2 carbon dioxide emissions.

This article presents the results of a probabilistic seismic hazard analysis (PSHA) conducted for a site in the city of Santiago, located in the Dominican Republic. To perform the PSHA recent seismological data of the Septentrional fault (seismic source) is used to calibrate an earthquake recurrence model, and to compute the seismic hazard curves of several earthquake, ground motion, and structural response parameters of interest in earthquake engineering applications. The parameters studied include horizontal peak ground acceleration and 5% damping pseudo-acceleration response spectrum ordinates. The effect of uncertainty in the seismic fault rupture zone location is studied using a Monte Carlo analysis; for this purpose, the rupture location is treated as a random variable along the fault. The PSHA results are compared to the site design response spectrum with 2% exceedance probability in 50 years specified in the Dominican Republic building code. It is concluded that there is a 17% probability that the actual 2% exceedance spectrum ordinates are greater than those specified in the design spectrum due to uncertainties related to the attenuation law employed to relate earthquake source and ground motion characteristics at the site. Based on the attenuation model, the design spectrum at the site is consistent with the spectrums generated by a 7.9 (moment) magnitude earthquake, which is close to the 7.8 magnitude characteristic earthquake estimated in previous studies for the Septentrional fault.

In the design of the software and hardware architecture, dynamic reconfiguration is an important factor in obtaining flexible, robust and scalable systems. This process requires planning, selection and the recurrent use of methods and resources that allow solving the external and internal changes that occur in production. The research shows that dynamic and integrated environments are approaches to address the architectures of modern production systems, in this sense it is necessary to design mathematical models that incorporate dynamic re-configuration with a holistic philosophy as part of it, aspects currently considered when designing business solutions. This work considers a generic approach based on the philosophy of holonic systems and modern techniques of cyber-physical systems, as well as the use of the components of Industry 4.0, such as digital twins represented through systems at discrete events that allow monitoring and managing the desired behavior of a production system.

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La educación virtual se hace más fuerte cada día. La transición desde el aula de clases al uso de una plataforma en línea era solo cuestión de tiempo. Aun así, y a pesar de las tecnologías disponibles, la transición no ha sido fácil ni para docentes ni para estudiantes. La plataforma Moodle, así como los módulos que se añaden desde la comunidad del software libre, brindan al docente varios esquemas para diseñar preguntas, y también para elaborar documentos de evaluación o cuestionarios. Sin embargo, en el caso del diseño de evaluaciones en cursos de Ingenierías o Ciencias, se presentan ciertas dificultades con el manejo de fórmulas matemáticas, ya sea para el docente al momento de implementar la pregunta o para el estudiante al momento de responderla. En este trabajo se describen las principales herramientas disponibles para la creación de preguntas, y el diseño de evaluaciones en línea bajo la plataforma Moodle. Se discute la efectividad de estas herramientas, sus fortalezas, debilidades. El tópico es de relevancia actual y abre el camino hacia la reflexión y estudio de estas herramientas, y su repercusión en el proceso de enseñanza-aprendizaje. Se utiliza una metodología descriptiva y al mismo tiempo argumentativa. Resultados experimentales muestran la necesidad de tener herramientas fáciles de manejar por parte del docente, de rápido entendimiento para el estudiante y que sirvan de soporte al proceso educativo.