Facultad de Ingeniería

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The mechanism of methanol decomposition by CuO. A theoretical study based on the reaction force and reaction electronic flux analysis
(Springer, 2010-10) Ceron, Maria Luisa; Herrera, Barbara; Araya, Paulo; Gracia, Francisco; Toro-Labbé, Alejandro; Toro Labbé, Alejandro
A theoretical study of methanol decomposition using a model representing the initial step of the reaction CH3OH + CuO → CH2O + H2O + Cu is presented. Theoretical calculations using B3LYP/6-31 G along with Lanl2DZ pseudopotentials on metallic centers were performed and the results discussed within the framework of the reaction force analysis. It has been found that the reaction takes place following a stepwise mechanism: first, copper reduction (Cu+2 → Cu+ ) accompanies the oxygen transposition and then a second reduction takes place (Cu+ → Cu0 ) together with a proton transfer that produce formaldehyde and release a water molecule.
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.
Engineering sustainable energy systems: how reactive and predictive homeostatic control can prepare electric power systems for environmental challenges
(2017) Yanine, Fernando; Sanchez-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.
Reviewing homeostasis of sustainable energy systems: How reactive and predictive homeostasis can enable electric utilities to operate distributed generation as part of their power supply services
(2018) Yanine, Fernando; Barrueto, Aldo; Sanchez-Squella, Antonio; Tosso, Joshua; Córdova, Felisa M.; Rother, Hans C.
Homeostatic control (HC) of electric power systems (EPS), particularly those that fall into the distributed generation (DG) category, can enable utilities to broaden their power supply services in line with industry changes worldwide while at the same time safeguarding their customers’ power supply against environmental challenges. Such solutions are being considered nowadays by industry giants like ENEL, by far the largest electric power utility operating in Chile. ENEL is seeking to tap into the DG market with a microgrid solution that can be installed in every building that is part of its customer base. In order to accomplish this, such DG solutions should first and foremost behave like sustainable energy systems (SES). For this they ought to emulate homeostasis mechanisms present in all living organisms. Both reactive homeostasis (RH) and predictive homeostasis (PH) enable living organisms to respond early and proactively to internal changes in the grid-tied DG system as well as to environmental challenges and threats. Particularly PH does so by foreseeing when these are most likely to occur, adjusting their energy intake and expenditure accordingly to maintain a stable, efficient and sustainable equilibrium. Based on the above, this paper presents a theoretical approach with an empirical base for engineering sustainability in hybrid energy systems. The project is part of a joint research initiative between a small group of university researchers and ENEL Distribucion, formerly Chilectra1 of Chile to develop a commercial prototype to be implemented in apartment buildings being serviced by ENEL throughout Santiago. This is important in order to advance DG solutions implemented by utilities like ENEL Distribucion, to further EPS decentralization, offer a broad, more flexible and personalized spectrum of services and, at the same time, preparing them for growing environmental challenges and threats.
Smart Energy Systems: The Need to Incorporate Homeostatically Controlled Microgrids to the Electric Power Distribution Industry : An Electric Utilities’ Perspective
(2018) Yanine, Fernando; Cordova, Felisa M.; Barrueto, Aldo; Sahoo, Sarat Kumar; Sanchez-Squella, Antonio
For no one is a secret that nowadays electric power distribution systems (EPDS) are being faced with a number of challenges and concerns, which emanate not so much from a shortage of energy supply but from environmental, infrastructural and operational issues. They are required to preserve stability and continuity of operations at any time no matter what, regardless of what may occur in the surroundings. This is the true measure of what sustainable energy systems (SES) are all about and homeostaticity of energy systems seeks just that: to bring about a rapid, effective and efficient state of equilibrium between energy supply and energy expenditure in electric power systems (EPS). The paper presents the theoretical groundwork and a brief description of the model for the operation of SES and their role in energy sustainability, supported by theoretical and empirical results. The concept of homeostaticity in EPDS is explained, along with its role in SES.
Review and comparative study of single-stage inverters for a PV system
(2018) Kumar Sahoo, Sarat; Sukchai, Sukruedee; Yanine, Fernando
Energy from the sun is harnessed through a photovoltaic (PV) array in form of DC. This available DC voltage is converted into AC for industrial or domestic use as per the requirement. In some topologies the extracted DC voltage is stepped up to a higher level of DC using a boost or a buck-boost converter and then this stepped up DC voltage is converted into AC by the use of an inverter. However this process is pretty costly because of the larger number of components employed. An efficient alternative to this two-stage approach is the Single-Stage Inverter (SSI). SSI does the boosting of DC and inversion of the DC to AC using only a single circuit and hence the name Single-Stage Boost Inverter. SSBI give us the advantage of reduced and robust circuitry along with reliability and efficiency. This paper presents a review of the various (however not all) SSI topologies in PV systems.
Homeostaticity of energy systems: How to engineer grid flexibility and why should electric utilities care
(Faculty of Engineering and Natural Sciences, 2019) Yanine, Fernando; Sanchez-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.
Factibilidad técnico-económica de la producción de hidróxido de litio a pequeña escala a partir de salmueras
(Universidad Finis Terrae (Chile) Facultad de Ingeniería, 2019) Velásquez Carrasco, Catalina; Cabrera Álvarez, Víctor Benigno prof. guía
La electrificación de nuestro mundo está impulsando un fuerte aumento en la demanda de litio y sobre todo de hidróxido de litio, ya que es una materia prima vital para la acumulación energía en baterías de ión de litio. Hoy en día, aproximadamente el 60% de la producción mundial de compuestos de litio se extrae de salmueras, una práctica que evapora el agua, en promedio un millón de litros por tonelada de carbonato de litio equivalente producida. Debido a eso, esta investigación presenta un nuevo método para producir hidróxido de litio directamente a partir de salmueras, basado en la electrólisis, en el desierto de Atacama, Chile, enfocado en una minera a pequeña escala. Esta región presenta condiciones particulares de clima desértico donde el agua es escasa y para ayudar a resolver este problema del proceso de producción convencional, se planteó un proceso modificado, con un consumo eficiente de agua, para mejorar la sostenibilidad ambiental de la planta de producción. En este se analizó en términos generales la factibilidad técnico – económica de implementar esta nueva metodología y se encontró que el consumo de agua por kilogramo de producto se modificó de un millón de litros de agua[46] por tonelada de carbonato de litio equivalente producido a 2596 litros y el costo fijo del proceso se estima en aproximadamente 3 dólares por kilogramo. Finalmente, se puede decir que los resultados presentados pueden considerarse como pautas para abordar la optimización del proceso industrial para obtener el LiOH.
A fresh look at an old problem: saturation in the retail market and how it affects both retailers and consumers
(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 compare 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.
Low carbon energy thecnologies in sustainable energy systems
(Elsevier, 2021) Yanine, Fernando; Sanchez-Squella, Antonio; Barrueto, Aldo; Kumar Sahoo, Sarat; Cordova, Felisa; Shah, Dhruv; Parejo, Antonio; Rother, Hans
Low Carbon Energy Technologies for Sustainable Energy Systems examines, investigates, and integrates current research aimed at operationalizing low carbon technologies within complex transitioning energy economies. Scholarly research has traditionally focused on the technical aspects of exploitation, R&D, operation, infrastructure, and decommissioning, while approaches which can realistically inform their reception and scale-up across real societies and real markets are piecemeal and isolated in separate literatures. Addressing both the technical foundations of each technology together with the sociotechnical ways in which they are spread in markets and societies, this work integrates the technoeconomic assessment of low carbon technologies with direct discussion on legislative and regulatory policies in energy markets. Chapters address issues, such as social acceptance, consumer awareness, environmental valuation systems, and the circular economy, as low carbon technologies expand into energy systems sustainability, sensitivity, and stability. This collective research work is relevant to both researchers and practitioners working in sustainable energy systems. The combination of these features makes it a timely book that is useful and attractive to university students, researchers, academia, and public or private energy policy makers.
Design of smart socket for monitoring of IoT-based intelligent smart energy management system
(Springer, 2021) Rao, Challa Krishna; Kumar Sahoo, Sarat; Balamurugan, M.; Yanine, Franco Fernando
Smart socket is designed for collecting and sending the data from the various nodes in one field to other fields. Smart socket consists of the Arduino_Uno, XBee, sensors, gateway, computer, USB, and IDE. This works emphasis on design and development of smart socket with wireless capability, this can be used to collect the data from each electrical device by using sensors. An XBee transmitter and receiver node are used for data communication in wireless networks. Real-time data gathered at the central node can be used to prioritize and schedule the appliances. Then, the system analyzes the data to generate control commands to turn the devices attached to the smart socket on or off. This paper presents the operation and functions of smart socket in different sensor network topologies. The results show that the proposed smart socket can correctly read the data from the various nodes and also send it to different nodes of different parameters.
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-Misleh, 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.
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.
Deep learning aplicado para la detección de hemorragias y tumores cerebrales
(ATOZ: novas práticas em informação e conhecimento, 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
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; Sanchez-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.
Design of an EEG analytical methodology for the analysis and interpretation of cerebral connectivity signals
(Elsevier, 2022-02-20) Córdova, Felisa M.; Cifuentes, Hugo F.; Díaz, Hernán A.; Yanine, Fernando; Pereira, Robertino
The objective of this study is to design an Electroencephalographic (EEG) analytic methodology that allows to develop a variety of analysis and interpretations of brain signals. The initial phase considers the acquisition and filtering of EEG signals, the division into bands in data ranges, and the storage of EEG signals in a cloud data base. Then, an analytical phase considering descriptive, predictive and prescriptive analysis is accomplished. A sequence of analytic intermediate processing steps is done in order to render a graphic visualization of significant correlations between pairs of EEG channels. Pearson correlation is utilized to detect synchronic connectivity through the brain areas. Time series in nearly instantaneous time lapses are treated by using Hilbert Huang Transform. An experimental design by submitting a set of students to an abbreviated version Raven visual test is made providing results in correlation maps of cerebral connectivity
On a Pickup to Delivery Drone Routing Problem: Models and algorithms
(Elsevier, 2022-09-06) Gómez-Lagos, Javier; Rojas-Espinoza, Benjamín; Candia-Véjar, Alfredo
A new variant of the Pickup and Delivery Routing problem is presented. Given a set of customers, facilities, a depot, and a homogeneous fleet of drones, the Pickup to Delivery Drone Routing Problem (PDDRP) aims to find a drone scheduling such that a drone serves the customer’s order from a set of available facilities. Each drone starts in the depot, flies to pickup the customer’s order in a facility, and continues its flight to deliver the parcel to a customer. Then, the drone begins another service, and once its last service is completed, it returns to the depot. The objective is to minimize the makespan associated with the drone fleet. The layer of facilities forcing drones to visit one of them to pickup the parcel makes the problem different from traditional pickup and delivery routing problems. Three mixed-linear programming models are presented to obtain optimal solutions for the problem. The first model is related to the multiple Traveling Salesman Problem (m-TSP), the second is associated with the Parallel Machine Scheduling Problem (PMS), and the third was developed specifically for the new problem. Given the high computational complexity of the PDDRP, a Greedy Randomized Adaptive Search Procedure (GRASP) was designed to find near-optimal solutions when exact approaches cannot achieve (near) optimal solutions. Computational experiments show that a commercial solver could solve only small problem instances. GRASP can find reasonable solutions in a short time when medium and large instance sizes need to be solved. Finally, is shown that some routing problems for delivery, allowing truck-drone collaboration, could be formulated as an extension of PMS.
Scale E-portfolio for Higher Education
(North American Business Press, 2023-02-23) Zambrano, Carolina; Rojas, Dario; Friz, Miguel
Due to the COVID 19 pandemic, the integration of technologies in education accelerated. In this context, the Digital Portfolio is presented as a tool with characteristics that allow the development of various skills. Thus, the objective of this research was i) Design a scale to measure the usefulness of developing a digital portfolio in Education from the curricular, communicative, and informative aspects. In addition, ii) Validate the proposed scale by applying exploratory factor analysis. The design was instrumental and 271 Higher Education students participated. The scale was designed based on the literature review and validation was carried out by expert judges and cognitive interviews. The results indicate adequate validity and reliability indices; being made up of 22 items represented in 3 factors: 1) Development of Curricular Aspects, 2) Digital Communication, 3) Development of Digital Information. It is concluded that the scale can be useful to measure and make visible the characteristics and pedagogical potential of digital portfolios in Higher Education.

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