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A Sub-Hourly Precipitation Dataset from a Pluviographic Network in Central Chile
(MDPI, 2025-06-22) Sangüesa, Claudia; Ibañez, Alfredo; Pizarro, Roberto; Vidal-Silva, Cristian; Garcia-Chevesich, Pablo; Mendoza, Romina; Toledo, Cristóbal; Pino, Juan; Paredes, Rodrigo; Ingram, Ben
This data descriptor presents a unique high-resolution rainfall dataset derived from 14 pluviograph stations across central Chile’s Mediterranean region, covering variable peri- ods starting from between 1969 and 1992, up to 2009. The dataset provides continuous precipitation records at a 5 min temporal resolution, obtained through the digitization and processing of pluviograph strip charts using specialized software. This high temporal resolution is unprecedented for the region and enables detailed analysis of rainfall inten- sity, duration, and frequency patterns critical for hydrological research, climate studies, and water resource management in general. Each station’s data was subjected to quality control procedures, including manual validation and correction of digitization errors to ensure data integrity. The dataset reveals the significant temporal variability of rainfall in central Chile, capturing both short-duration high-intensity events and longer precipi- tation patterns. By making this dataset publicly available, we provide researchers with a valuable resource for studying rainfall behavior in a Mediterranean climate zone subject to significant climate variability and change. The dataset supports various applications, including the development of intensity–duration–frequency curves, analysis of rainfall erosivity, calibration of hydrological models, and investigation of precipitation trends in the context of climate change.
Análisis de canasta de mercado en supermercados mediante mapas auto-organizados
(Universidade Federal do Paraná, 2021-11-08) Cordero, Joaquín; Bolt, Alfredo José; Valle, Mauricio A.
Introducción: Una cadena importante de supermercados de la zona poniente de la capital de Chile, necesita obtener información clave para tomar decisiones. Esta información se encuentra disponible en las bases de datos, pero necesita ser procesada debido a la complejidad y cantidad de información, lo que genera una dificultad a la hora de visualizar. Método: Para este propósito, se ha desarrollado un algoritmo que utiliza redes neuronales artificiales, aplicando el método SOM de Kohonen. Para llevarlo a cabo, se han debido seguir ciertos procedimientos claves, como preparar la información, para luego utilizar solo los datos relevantes a las canastas de compra de la investigación. Luego de efectuado el filtrado, se tiene que preparar el ambiente de programación en Python para adaptarlo a los datos de la muestra, y luego proceder a entrenar el SOM con sus parámetros fijados luego de resultados de pruebas. Resultado: El resultado del SOM obtiene la relación entre los productos que más se compraron, posicionándolos topológicamente cerca, para conformar promociones y bundles, para que el retail mánager tome en consideración. Conclusión: En base a esto, se han hecho recomendaciones sobre canastas de compra frecuentes a la cadena de supermercados que ha proporcionado los datos utilizados en la investigación.
Application of dual descriptor to understand the activity of Cu/ZrO2 catalysts in the water gas shift reaction
(Springer Nature, 2017) Cerón, María Luisa; Calatayud, Mónica
A comparative theoretical study applying Dual Descriptor has been performed using Water Gas Shift reaction, catalyzed by copper supported on monoclinic and tetragonal zirconia. The Dual Descriptor and thermodynamic considerations were used to understand the structural effects that occur in the reaction when it is catalyzed by Cuon both zirconia phases. It was found that the formation of carbonates in the Cu supported on tetragonal zirconia dehydrogenates consistently with experimental results.
Applying multi-criteria analysis in a port system
(2017) Córdova, Felisa M.; Durán, Claudia
This work presents a study developed in a medium port system composed of 50 public and private actors interacting with their macro-environment, which can generate strategic synergistic relationships. In order to determine these synergistic links between their components, the strategic phrases contained in their missions are analysed and classified according to the multicriteria that are part of the macro-environment of each port actor: political, economic, social, technological, environmental, risk and learning. Likewise, new characterizations and classifications are proposed for groups and sub-groups of port actors. From absolute frequencies, Contingency Tables and the Chi-square test, quantitative results are obtained, which show the potential cases of strategic synergistic relations in the port system and the behavior of each group and sub-group of actors, as well as dependence / independence between every pair of criteria. Finally, it is verified that it is possible to use quantitative methods to analyze the strategic synergistic relationships between the actors of the port system.
Challenges to applying role playing in software engineering education: a taxonomy derived from a rapid literature review
(Springer, 2024-07) Hidalgo Barrientos, Mauricio Fernando; Astudillo, Hernán; Castro, Laura M.
Role Playing (RP) serves as an instructional approach to enrich the learning experience for students and boost their learning by the effective application of their theoretical knowledge within a practical context. In Software Engineering Education (SEE), the utilization of RP proves beneficial in fostering the development of skills such as teamwork, problem-solving, and critical thinking among students and aids them in comprehending the intricacies and hurdles inherent in software development, instilling the significance of collaborative efforts and effective communication. To use role playing effectively, SEE teachers need to understand the challenges that arise from using it. This paper presents a taxonomy, resulting from the analysis of a rapid review developed to identify these challenges: a thorough review of relevant articles indexed by well-known digital libraries (Web of Science, Scopus, and IEEE Xplore) which, after inclusion/exclusion criteria, yielded a total of 23 papers. This taxonomy provides an organized structure for understanding the challenges in implementing Role Playiing (RP) activities in the context of Software Engineering Education (SEE).
Deep learning aplicado para la detección de hemorragias y tumores cerebrales
(Universidade Federal do Paraná, 2021-12-01) Hidalgo Barrientos, Mauricio Fernando; Hayes Ortiz, Bryan Isaac; Delgadillo Vera, Ignacio; Goyo Escalona, Manuel
Introducción: Un problema que afecta a la salud en Chile se refiere a las patologías cerebrales, toma de exámenes y el alto tiempo de espera para la obtención de los resultados (retrasando el diagnóstico y tratamiento). Actualmente, los exámenes se envían al extranjero para ser procesados y el tiempo de espera juega en contra del paciente. Dada esta realidad, nuestro documento propone un modelo de deep learning para la predicción de imágenes cerebrales que permita obtener un diagnóstico previo, pero no definitivo, en virtud de disminuir el tiempo del proceso y, de ser necesario, priorizar a los pacientes cuya vida estaría potencialmente en riesgo. Métodos: El desarrollo utilizó un enfoque RAD iterativo y las imágenes se recogieron de Kaggle. Adicionalmente, se redimensiona el dataset para normalizar el tamaño y generamos nuevas imágenes utilizando “data augmentation”. Las imágenes fueron procesadas en redes convolucionales, indagando en distintas configuraciones para la red, su optimizador y la función de activación, hasta llegar a un modelo que consideramos razonable. Resultados: Con el modelo definitivo, los resultados superan el 80% de precisión en las predicciones y descubrimos que separar patologías (hemorragias y tumores) fue crucial para este resultado. Conclusiones: Hemos logrado una herramienta de diagnóstico previo, pero se debe continuar la investigación en virtud de aumentar la precisión. Un próximo paso considera ampliar el dataset con imágenes de otras fuentes y separar el modelo para analizar patologías de forma independiente. Motivamos a seguir investigando ya que este tipo de apoyo puede contribuir a salvar vidas.
Diseño y desarrollo de aplicación móvil para la clasificación de flora nativa chilena utilizando redes neuronales convolucionales
(Universidade Federal do Paraná, 2022-01-22) Muñoz Villalobos, Ignacio Andrés; Bolt, Alfredo José
Introducción: Las aplicaciones móviles, a través de la visión artificial, son capaces de reconocer especies vegetales en tiempo real. Sin embargo, las actuales aplicaciones de reconocimiento de especies no consideran la gran variedad de especies endémicas y nativas de Chile, tendiendo a predecir erróneamente. Esta investigación presenta la construcción de un dataset de especies chilenas y el desarrollo de un modelo de clasificación optimizado e implementado en una aplicación móvil. Método: La construcción del dataset se realizó a través de la captura de fotografías de especies en terreno y selección de imágenes de datasets en línea. Se utilizaron redes neuronales convolucionales para desarrollar los modelos de predicción de imágenes. Se realizó un análisis de sensibilidad al entrenar las redes, validando con k-fold cross validation y efectuando pruebas con distintos hiperparámetros, optimizadores, capas convolucionales y tasas de aprendizaje, para seleccionar los mejores modelos y luego ensamblarlos en un solo modelo de clasificación. Resultados: El dataset construido se conformó por 46 especies, incluyendo especies nativas, endémicas y exóticas de Chile, con 6120 imágenes de entrenamiento y 655 de prueba. Los mejores modelos se implementaron en una aplicación móvil, donde se obtuvo un porcentaje de acierto de aproximadamente 95% con respecto al conjunto de pruebas. Conclusiones: La aplicación desarrollada es capaz de clasificar especies correctamente con una probabilidad de acierto acorde con el estado del arte de la visión artificial y de mostrar información de la especie clasificada.
Energy homeostasis management strategy for building rooftop nanogrids, considering the thermal model and a HVAC unit installed
(Elsevier, 2022-02-04) Yanine, Fernando; Sánchez-Squella, Antonio; Barrueto, Aldo; Sahoo, Sarat Kumar; Parejo, Antonio; Cordova, Felisa M.
This paper presents a case study on power control and energy management for a 60 apartments’ residential building with solar generation and energy storage tied to the grid in Santiago, Chile. A new energy management algorithm based on energy homeostasis is designed for a small electro thermal generation system (nanogrid), with smart metering. The test bed employs supervisory control with energy management that regulates the temperature inside a large room by the action of an HVAC (Heating/Ventilating/Air Conditioning) unit. The main objective of supervisory control is to allow temperature comfort for residents while evaluating the decrease in energy cost. The study considers a room with rooftop grid-tie nanogrid with a photovoltaic and wind turbine generation plant, working in parallel. It also has an external weather station that allows predictive analysis and control of the temperature inside the abode. The electrical system can be disconnected from the local network, working independently (islanding) and with voltage regulation executed by the photovoltaic generation system. Additionally, the system has a battery bank that allows the energy management by means of the supervisory control system. Under this scenario, a set of coordination and supervisory control strategies, adapted for the needs defined in the energy management program and considering the infrastructure conditions of the network and the abode, are applied with the aim of efficiently managing the supply and consumption of energy, considering Electricity Distribution Net Billing Laws 20.571 and 21.118 in Chile (https://www.bcn.cl/historiadelaley/historia-de-la-ley/vista-expandida/7596/), the electricity tariffs established by the distribution company and the option of incorporating an energy storage system and temperature control inside the room. The results show the advantage of the proposed tariffs and the overall energy homeostasis management strategy for the integration of distributed power generation and distribution within the smart grid transformation agenda in Chile. Este artículo presenta un caso de estudio sobre control de potencia y gestión de energía para un edificio residencial de 60 departamentos con generación solar y almacenamiento de energía conectado a la red en Santiago, Chile. Se diseña un nuevo algoritmo de gestión energética basado en la homeostasis energética para un pequeño sistema de generación electrotérmica (nanogrid), con medición inteligente. El banco de pruebas emplea un control de supervisión con administración de energía que regula la temperatura dentro de una habitación grande mediante la acción de una unidad HVAC (Calefacción/Ventilación/Aire acondicionado). El objetivo principal del control de supervisión es permitir el confort de la temperatura para los residentes mientras se evalúa la disminución del costo de la energía. El estudio considera una habitación con nanorredes conectadas a la red en la azotea con una planta de generación fotovoltaica y eólica, trabajando en paralelo. También cuenta con una estación meteorológica externa que permite el análisis predictivo y control de la temperatura al interior de la morada. El sistema eléctrico se puede desconectar de la red local, trabajando de forma independiente (islanding) y con regulación de tensión ejecutada por el sistema de generación fotovoltaica. Adicionalmente, el sistema cuenta con un banco de baterías que permite la gestión de la energía a través del sistema de control de supervisión. Bajo este escenario, se aplican un conjunto de estrategias de coordinación y control supervisor, adaptadas a las necesidades definidas en el programa de gestión energética y considerando las condiciones de infraestructura de la red y del domicilio, con el objetivo de gestionar eficientemente el suministro y consumo de energía, considerando las Leyes de Facturación Neta de Distribución Eléctrica 20.571 y 21.118 de Chile (https://www.bcn.cl/historiadelaley/historia-de-la-ley/vista-expandida/7596/), las tarifas eléctricas establecidas por la empresa distribuidora y la posibilidad de incorporar un sistema de almacenamiento de energía y control de temperatura en el interior de la estancia. Los resultados muestran la ventaja de las tarifas propuestas y la estrategia general de gestión de la homeostasis energética para la integración de la generación y distribución de energía distribuida dentro de la agenda de transformación de redes inteligentes en Chile.
Engineering sustainable energy systems: how reactive and predictive homeostatic control can prepare electric power systems for environmental challenges
(Elsevier, 2017) Yanine, Fernando; Sánchez-Squella, Antonio; Barrueto, Aldo; Cordova, Felisa M.; Kumar Sahoo, Sarat
Nowadays electric power generation and distribution systems are being faced with a number of challenges and concerns which emanate not so much from a shortage of energy supply but from environmental and operational issues. They are required to respond to such challenges very rapidly and effectively so as to preserve stability and continuity of operations at any time, regardless of what may occur in the surroundings. This in fact is the true measure of what sustainable energy systems (SES) are all about, and homeostatic control (HC) of energy systems seeks just that: to enable energy systems to become highly efficient and effective very rapidly, by attaining a state of equilibrium between energy supply and energy expenditure in electric power systems (EPS) operation. To accomplish so they ought to imitate homeostasis mechanisms present in all living organisms. Ever since Cannon (1929, 1935) first introduced the concept, attention on homeostasis and its applications have been the sole patrimony of medicine and biology to find cures for diseases like diabetes and obesity. Nevertheless, homeostasis is rather an engineering concept in its very essence - even more so than in the natural sciences - and its application in the design and engineering of sustainable hybrid energy systems (SHES) is a reality. In this paper we present the groundwork that supports the theoretical model underlining the engineering of homeostasis in SHES. Homeostasis mechanisms are present in all living organisms, and thus are also applicable to EPS in order to enable and maintain a sustainable performance when EPS are linked to energy efficiency (EE) and thriftiness. In doing so, both reactive and predictive homeostasis play a substantive role in the engineering of such mechanisms. Reactive homeostasis (RH) is an immediate response of the SES to a homeostatic challenge such as energy deprivation, energy shortage or imbalance. RH entails feedback mechanisms that allow for reactive compensation, reestablishing homeostasis or efficient equilibrium in the system. Predictive homeostasis (PH), on the other hand, is a proactive mechanism which anticipates the events that are likely to occur, sending the right signals to the central controller, enabling SES to respond early and proactively to environmental challenges and concerns. The paper explores both concepts based on previous work in order to advance the research in the field of HC applied to electric power systems.
Essential minimum in Families of Lines
(Universidad Adam Mickiewicz; Facultad de Matemáticas y Ciencias de la Computación, 2025-09-24) Morales Inostroza, Marcos Isai
We apply general methods to produce upper bounds for the essential minimum of a specific family of height functions. In particular, the results shown in this article apply to the case of the Zhang-Zagier height. Furthermore, we can find intervals, where the images of these heights are dense. Our main tool to find upper bounds and intervals of density is a refinement of the classical Fekete-Szegö theorem due to Burgos Gil, Philippon, Rivera-Letelier and Sombra. El artículo consiste en acotar una invariante asociada a una altura dentro de variedades algebraicas, ultilizando herramientas de geometría aritmética, teoría de números y variable compleja. En general, las funciones alturas desempeñan un rol muy importante en muchas ramas de la matemática debido a que permite entender la distribución de los llamados small points que juegan un papel importante en la teoría de equidistribución.
Un estudio de disponibilidad léxica asociado a las áreas de aprendizaje y motivación por el aprendizaje
(Universidad Nacional Mayor de San Marcos; Instituto de Investigación de Lingüística Aplicada, 2023-07-27) Zambrano, Carolina; Agustin, Maria Pilar
Se presenta un estudio de disponibilidad léxica para los conceptos de aprendizaje y motivación por el aprendizaje en estudiantes de pedagogía. Para ello, los objetivos son los siguientes: i) cuantificar el léxico disponible usando los índices NPD, XR, IC e IDL, ii) analizar el léxico disponible usando grafos, y iii) categorizar el léxico disponible mediante asociaciones del tipo semántico-cognitivo. Se utilizó una metodología con un diseño mixto que integra análisis cuantitativo y cualitativo. Los resultados evidencian que se requiere mejorar el vocabulario sobre el aprendizaje. Asimismo, como resultado presentamos un esquema conceptual de categorizaciones, que para el concepto de aprendizaje se compone de las siguientes categorías: estrategias de estudio reproductivas, estrategias de estudio orientadas a la aplicación de los conocimientos, actores del sistema educativo, espacios del sistema educativo y elementos para la enseñanza-aprendizaje. Para el concepto motivación por el aprendizaje, las categorías son motivación a las metas, orientación por vocación y elementos para la enseñanza-aprendizaje
A fresh look at an old problem: saturation in the retail market and how it affects both retailers and consumers
(Indian Society for Education and Environment, 2019-05-28) Yanine, Fernando; Cordova, Felisa M.; Valenzuela, Lionel; Isla, Pablo
Objective: Traditional saturation analysis on competitive location decision science focuses on diminishing returns for incumbents and newcomers in a specific spatial location pertaining to commercial retail potential past a certain point of market saturation. Methods/Findings: This study looks at this problem but employs a different approach to the subject altogether, wherein saturation is no longer a variable affecting only retailers but one that affects both: the marginal utility of consumers and the revenue of retailers albeit differently. A new mathematical model is proposed based on selected papers, contributing new insight into an already widely discussed subject. Application: Analysis shows that it is important for competitive location decision-making to address saturation from both sides of the overall competitive location decision issue, not just from the retailers’ standpoint.
Grid-tied distributed generation systems to sustain the smart grid transformation: tariff analysis and generation sharing
(MDPI, 2020) Yanine, Fernando; Sánchez-Squella, Antonio; Barrueto, Aldo; Parejo, Antonio; Cordova, Felisa; Rother, Hans
In this paper a novel model is being proposed and considered by ENEL—the largest electric utility in Chile—and analyzed thoroughly, whereby electric power control and energy management for a 60-apartments’ residential building is presented as an example of the utility’s green energy program, part of its Smart Grid Transformation plan to install grid-tied distributed generation (DG) systems, namely microgrids, with solar generation and energy storage in Santiago, Chile. The particular tariffs scheme analysis shown is part of the overall projected tentative benefits of adopting the new scheme, which will require the utility’s customers to adapt their consumption behavior to the limited supply of renewable energy by changing energy consumption habits and schedules in a way that maximizes the capacity and efficiency of the grid-tied microgrid with energy storage. The change in behavior entails rescheduling power consumption to hours where the energy supply capacity in the DG system is higher and price is lower as well as curtailing their power needs in certain hourly blocks so as to maximize DG system’s efficiency and supply capacity. Nevertheless, the latter presents a problem under the perspective of ENEL’s renewable energy sources (RES) integration plan with the electric utility’s grid supply, which, up until now and due to current electric tariffs law, has not had a clear solution. Under said scenario, a set of strategies based on energy homeostasis principles for the coordination and control of the electricity supply versus customers’ demand has been devised and tested. These strategies which consider various scenarios to conform to grid flexibility requirements by ENEL, have been adapted for the specific needs of these types of customers while considering the particular infrastructure of the network. Thus, the microgrid adjusts itself to the grid in order to complement the grid supply while seeking to maximize green supply capacity and operational efficiency, wherein the different energy users and their energy consumption profiles play a crucial role as “active loads”, being able to respond and adapt to the needs of the grid-connected microgrid while enjoying economic benefits. Simulation results are presented under different tariff options, system’s capacity and energy storage alternatives, in order to ompare the proposed strategies with the actual case of traditional grid’s electricity distribution service, where no green energy is present. The results show the advantage of the proposed tariffs scheme, along with power control and energy management strategies for the integration of distributed power generation within ENEL’s Smart Grid Transformation in Chile.
Homeostaticity of energy systems: How to engineer grid flexibility and why should electric utilities care
(Faculty of Engineering and Natural Sciences, 2019) Yanine, Fernando; Sánchez-Squella, Antonio; Barrueto, Aldo; Kumar Sahoo, Sarat; Parejo, Antonio; Shah, Dhruv; Cordova, Felisa
Today’s power generation and distribution industry is being faced with a number of issues, from violent weather phenomena to earthquakes, fires and landslides; including acts of arson, terrorism and vandalism, all of which pose serious concerns for the sustainability of the distribution and supply of electricity. Electric utilities like ENEL are cognizant of this fact and know they must take action. Moreover, they are required by law to be prepared and act proactively to prevent service disruption, by responding to such challenges rapidly and effectively so as to preserve stability and continuity of operation. Homeostaticity of energy systems seeks just that: to bring about a rapid, effective and efficient state of equilibrium between energy supply and expenditure at all times, whatever the circumstances, to preserve stability of systems operation. The paper presents a prescriptive energy homeostaticity model being considered by ENEL as a means to further the incorporation of renewables in the electricity generation and distribution industry. The aim is to enhance control and energy management systems in distributed generation installations tied to the grid for urban and rural communities, in order to complement and diversify their electric power distribution services. The theoretical groundwork underlying the subject as well as other relevant contextual factors are also discussed and simulation results are presented under different tariff scenarios, and energy storage alternatives, in order to compare the proposed model with the actual case. Energy storage (ES) is found to be of paramount importance in the overall analysis of the results as it enhances and reinforces thriftiness on energy consumption.
Mapping kolb's learning style to roles in software development team
(Institute of Electrical and Electronics Engineers (IEEE), 2024-10-08) Hidalgo Barrientos, Mauricio Fernando; Rodriguez, Kattia; Astudillo, Hernán
The effective transfer and acquisition of necessary knowledge, methods, and attitudes pose significant challenges for Software Engineering Education. Furthermore, training in software development skills and knowledge currently lacks a clear set of techniques to link learning styles and preferences with development team roles. This paper characterizes the learning style of four traditional roles in software development (Analyst, Architect, Developer, and Project Manager) using Kolb's Learning Styles Inventory. Kolb's Learning Styles Test was administered to 110 software development practitioners (15 analysts, 18 architects, 50 developers, and 27 project managers). The test results show that, with some differences, architects and analysts have the Deciding style, while developers and project managers exhibit the Thinking style. Finally, in alignment with Kolb's learning strengths and challenges, this work provides a set of teaching strategies for each role based on their inferred learning styles.
Mathematical framework for the plastic flow of fine-grained solids, from yield to fracture
(Elsevier, 2024-12-15) Lagos, Miguel; Conte, Víctor
A newly proposed mathematical approach to plastic flow, holding from yield to fracture, of a fine-grained polycrystal with no voids or cracks is reviewed and applied to commercial steels. The formalism models the polycrystal by a continuum array of random deformable polyhedra leaving no voids between them, which can slide past each other along the shared faces when the shear stress resolved in the face plane exceeds a finite threshold. Grain reshaping for preserving matter continuity induces local forces assumed much weaker than those causing sliding. The relative velocity of adjacent sliding grains is taken as proportional to the local shear stress resolved in the common boundary plane. Explicit equations are derived for the plastic deformation, from yield to fracture. The analysis of mechanical tests of two commercial stainless steels is shown to illustrate how well the theory agrees with practice.
Mathematical model for the plastic flow and ductile fracture of polycrystalline solids
(Elsevier, 2024-01-25) Lagos, Miguel; Retamal, César; Valle, Rodrigo; Paredes, Rodrigo
It is mathematically shown that ductile fracture after finite plastic strain is a necessary consequence of the polycrystalline nature of the materials. A closed–form equation for the plastic strain to fracture of a fine–grained polycrystal with no voids is derived. The mathematical model for the plastic deformation is grounded on the physical hypothesis that adjacent grains slide with a relative velocity proportional to the local shear stress resolved in the plane of the shared grain boundary, when exceeds a finite threshold. Hence plastic flow is governed predominantly by the in–plane shear forces making grain boundaries to slide, and the induced local forces responsible for the continuous grain reshaping are much weaker. The process is shown to produce a monotonic hydrostatic pressure variation with strain that precludes a stationary flow. The hydrostatic pressure dependence on strain has two solutions. One of them leads to superplasticity, the other one is shown to diverge logarithmically at a finite fracture strain and then represents ductile behaviour. Emphasis is done in the mathematical aspects of the deformation of the polycrystal up to the initiation of fracture. Although theoretical predictions agree well with mechanical tests of commercial alloys, technical issues like the effects of the presence and evolution of porosity and other imperfections, or how fracture evolves after initiation are left for a more specific communication.
Oscillations and Waves
(Institute of Physics (AIP) Publishing, 2024-12-01) Lagos, Miguel; Paredes, Rodrigo; Elgueta, Milton; Molina, Mario
Oscillations and waves are prevalent in the realm of physical sciences, finding applications across a wide range of technical fields. Waves can be observed everywhere, primarily due to the fact that the lowest-energy states of most spatially extended physical systems tend to exhibit wave-like characteristics. Oscillation can be regarded as a fundamental component of wave motion. It is evident in various scenarios, such as the movement of a suspended object, subtle fluctuations in air pressure within a noisy environment, or the gentle ripples on the surface of a quiet pond. Even in more intricate systems, like the dynamics of the electromagnetic field, we consistently observe the tangible consequences of oscillations and waves. For this reason, it is highly desirable to introduce the study of physical systems governed by waves at an early stage, as it fosters a sense of comprehension regarding complex aspects of real-life phenomena. The issue at hand is that the conventional exploration of oscillations and waves requires mathematical techniques that are still unfamiliar to students at the introductory level. However, the next sections aim to provide a theoretical introduction to oscillations and waves without relying on advanced mathematics, ensuring that no physical rigor is sacrificed. The article seeks to help teachers motivate students with a special interest in science.
A PI + sliding-mode controller based on the discontinuous conduction mode for an unidirectional buck–boost converter with electric vehicle applications
(MDPI, 2021-10-18) Gonzalez, Ileana; Sanchez, Antonio; Langarica-Cordoba, Diego; Yanine, Fernando; Ramirez, Victor
This paper solves the buck–boost converter operation problem in the discontinuous conduction mode and the feeding a DC bus of a combined battery/solar-powered electric vehicle grid. Since the sun’s radiation has a very important effect on the performance of photovoltaic solar modules due to its continuous variation, the main task of the system under study is the regulation of the output voltage from an MPPT system located at the output of the panels in order to obtain a DC bus voltage that is fixed to 24 V. This is ensured via a double-loop scheme, where the current inner loop relies on sliding-mode control; meanwhile, the outer voltage loop considers a proportional–integral action. Additionally, the current loop implements an adaptive hysteresis logic in order to operate at a fixed frequency. The closed-loop system’s performance is checked via numerical results with respect to step changes in the load, input voltage, and output voltage reference variations.
Revealing the secrets of the number pi and copper number algorithms
(Mathematics and Technology, LLC, 2025-10-13) Silva Ulloa, Adrián
The present text constitutes a compilation of humanity's fervour to ascertain the enigmatic number pi, entitled "Revealing the secrets of the number pi and the algorithms of the copper number". In this essay, we seek to illuminate the hidden intricacies of this number, explore its potential connections with other numerical entities, investigate the alleged falsehoods associated with its proponents, and delve into more complex subjects by employing calculus, series, and contemporary technologies. The document's intention is to demonstrate the methods and justify the interesting procedures that lead to the solution of numerical problems, with a particular focus on the number pi. It is a valuable resource for mathematicians, computer scientists, and anyone with an interest in formulas or the human ingenuity behind their discovery. The author posits that each contribution of knowledge leads to a subsequent step, and the discovery of the so-called "absolutely convergent series" will allow the reader to devise an algorithm to find all the digits of pi.

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