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This work introduces a novel computational approach based on Principal Component Analysis (PCA) for dimensionality reduction of the solution space in optimisation problems with known linear interdependencies among solution variables. By creating synthetic datasets with deliberately engineered properties and applying PCA, the solution space’s remapping significantly reduces its dimensionality, leading to faster computation and more robust convergence in optimisation processes. We demonstrate this method by integrating it with a Genetic Algorithm (GA) for solving the optimal director distribution in liquid crystal (LC) devices, specifically addressing 2D and complex 3D spatial light modulator (SLM) structures such as twisted nematic liquid crystals (TN-LC) and parallel-aligned liquid crystal on silicon (PA-LCoS), respectively. The phase profiles obtained from the director vector distributions for horizontal and vertical high-frequency binary phase gratings closely match the theoretical values derived from minimising the traditional elastic Frank–Oseen functional via Euler–Lagrange equations. Beyond this specific application, our method offers a general framework for reducing computational complexity in optimisation problems by directly reducing the dimensionality of the solution space. This approach is applicable across various optimisation scenarios with well-known linear interdependencies among solution variables, enabling significant reductions in computational costs and improvements in robustness and convergence.

Introduction: Mental fatigue is a key factor in soccer that can affect physical performance. Mental fatigue protocols based on the Stroop test used in soccer involve extensive time, ranging from 10 to 30 min. Offering a protocol with a shorter duration that is more applicable in ecological situations seems to be an exciting challenge. Objective: To analyze the effects of a mental fatigue induction protocol (2 min Stroop test in its incongruent mode) on decision-making, response time, and technical execution accuracy in soccer players. Methods: A total of 18 semi-elite soccer male players, 25.83 (4.71) years from a Spanish soccer team, participated in this cross-sectional study. The 2 min incongruent Stroop test was used like mental fatigue protocol, followed by a specific analytical soccer task. The Wilcoxon signed-rank and Chi-squared tests were used to analyze the statistical differences. Results: A significant increase in participants’ response time after the fatigue protocol (p < 0.001; r = 0.878) was observed. Regarding the variables of correct decision (p = 0.457; r = 0.031) and technical execution accuracy (p = 1; r < 0.001), no significant differences were found. Additionally, no differences were observed between the first and second attempts of the 2 min incongruent Stroop test, in terms of execution accuracy, errors, or total words. Conclusions: The 2 min Stroop incongruent task may induce some degree of mental fatigue, leading to slower response time during certain technical tasks in semi-elite soccer players. However, this Stroop task was insufficient to promote significant changes in the accuracy of technical execution and the effectiveness of decision-making.

La optimización desempeña un papel crucial en la planificación y operación de los sistemas de gestión de energía, reduciendo costos y evitando pérdidas en su generación, disminuyendo, además, las emisiones de carbono. Lo anterior se da teniendo en cuenta el equilibrio entre oferta y demanda y el aprovechamiento de los recursos energéticos distribuidos (DER, por sus siglas en inglés). Este trabajo tuvo como objetivo proponer un esquema generalizado de comunidad energética, donde los generadores que componen una microrred suplen la demanda de esta o de las microrredes vecinas. Es de considerar que cada generador de energía tiene una función de costos asociada a esta, y existe una penalización, o costo de transmisión, cuando un DER, ubicado en una microrred definida, envía energía a la microrred vecina. Con el fin de abordar las restricciones, se propuso, como metodología de solución, un enfoque basado en juegos poblacionales, en conjunto con la técnica de relajación lagrangiana. Los resultados obtenidos fueron la aplicación del modelo y método de solución en tres diferentes escenarios. Además, se comparó el desempeño de la solución propuesta con la respuesta de un método de optimización convencional, logrando despachos similares y errores mínimos en comparación con la técnica tradicional. La investigación demostró que la combinación de conceptos de juegos poblacionales y técnicas de relajación lagrangiana permiten asumir restricciones que son de difícil manejo para la dinámica de replicadores. Finalmente, se concluye que el modelo es una buena herramienta para abordar problemas de gestión de energía que implican cumplir con la demanda por región en un escenario peer to peer.

Dynamic stiffness is a parameter of great importance for the assessment of the sound insulation properties of resilient materials commonly used under floating floors in dwellings. This work proposes a simplified approach that relies on an electro-mechanical circuit model for the determination of this parameter using a two-degree-of-freedom system of masses and springs. Unlike the method described in the standard ISO 9052-1, the proposed approach uses a single electrodynamic actuator both as an impulser and vibration sensor, thus reducing the instrumental requirements and yielding a more stable arrangement. By measuring the input electrical impedance of the mass-loaded actuator when coupled to a slab–material system it was possible to retrieve the mechanical mobility function thereof and thus obtain the dynamic stiffness of the material. Several materials were tested following the proposed approach, with results showing good agreement when compared to those obtained following the standardized procedure. In general, the preliminary research encourages the use of the proposed approach for characterization purposes.

This paper explores the potential of some remarkable power theories derived from Fryze’s approach to assessing waveform distortion contributions. The analysis is limited to a simplified system composed of one load and one voltage source connected by a point of common coupling. Finally, some keys to assess are proposed for two types of systems: strong networks (traditional distribution systems) and weak networks (islanded microgrids).

As an active mode of transportation, walking has proven to be an effective strategy to tackle environmental problems while improving health. The current paper highlights the main factors that either encourage or deter pedestrians in their daily trips by analyzing the arisen discussions in three different Focus Groups (FGs), which were later synthesized into factors ranking according to their positive or negative outcomes. The results help identify these factors and show how a variety of target groups (seniors, young adults, middle-aged adults, divided by male and female perspective) perceive the city in different ways: younger adults prioritize accessibility and quality of the infrastructure, females highlighted the insecurity suffered during nighttime trips, and older adults emphasized the relevance of street maintenance. Finally, the benefits of walking on physical and mental health are viewed positively amongst all target groups, considering walking as a means to help people reduce stress.

Context: This work presents different models based on artificial neural networks, among them NNARX, for estimating global solar radiation from UV index measurements. The objective is to determine the efficiency of the models studied to estimate global solar radiation in terms of the coefficient of determination (R2), the root-mean-square error (RMSE), and the mean absolute error (MAE). Methodology: It is divided into four stages: i) conformation of the training dataset (in this case, it uses a training set of 213.019 data collected over five years in the city of Pasto, Colombia, with the Davis Vantage Pro 2.0 station); ii) pre-processing of data to remove erroneous and unusual data; iii) definition of models based on recurrent and conventional artificial neural networks according to an analysis of topologies, e.g. NNFIR and NNARX; iv) training of the models and evaluation of the estimation efficiency through metrics such as R2, RMSE, and MAE. To validate the model, a new dataset collected during the last year was used, which was not included in the data training. Results: The global solar radiation estimation models based on NNARX show the best estimation efficiency compared to conventional neural networks. The NNARX221 model has an RMSE of 54,32 and a MAE of 18,06 w/m2. Conclusions: NNARX models are highly efficient at estimating global solar radiation, with a coefficient of determination of 0,9697 in the best of cases. The most efficient models are characterized by using two past times and the current UV index instant, and they feed from two past times of their own estimated radiation output. Furthermore, the numerical results show that the contribution of temperature and relative humidity is not relevant to improving the efficiency of the estimation of global solar radiation. These models can be particularly important since they only use measurements made with UV index sensors, which are less expensive than solar radiation ones.

In recent years, operation and control strategies in distribution systems have changed due to the increase in the connection of distributed generation sources (DGs). Small local networks with electricity users and DGs are known as microgrids. These microgrids can operate independently (islanded) or in collaboration (interconnected) with the main network or other microgrids. Some advantages of interconnected microgrids include the reduction of losses, an increase in reliability, and decentralized operation under fault conditions. Nevertheless, when a microgrid operates in islanded mode, its electrical characteristics change and, consequently, the severity of power quality disturbances can increase, as well as their negative impact on electronic devices (loads and DG devices). This paper presents a comprehensive literature review of existing studies on power quality disturbances in islanded microgrids and identifies the most relevant needs for future research on this topic. Detailed information is analyzed to compare the differences between disturbance levels in both interconnected and islanded microgrids. In the case of harmonic disturbances, the impact of the different microgrid configurations is also analyzed.

Recently, the different citation databases have updated their citation and positioning results. On this occasion, we want to show the readers of the Ingeniería e Investigación journal how our indicators have evolved in three of them.

Weed management is one of the most important aspects of crop productivity; knowing the amount and the locations of weeds has been a problem that experts have faced for several decades. This paper presents three methods for weed estimation based on deep learning image processing in lettuce crops, and we compared them to visual estimations by experts. One method is based on support vector machines (SVM) using histograms of oriented gradients (HOG) as feature descriptor. The second method was based in YOLOV3 (you only look once V3), taking advantage of its robust architecture for object detection, and the third one was based on Mask R-CNN (region based convolutional neural network) in order to get an instance segmentation for each individual. These methods were complemented with a NDVI index (normalized difference vegetation index) as a background subtractor for removing non photosynthetic objects. According to chosen metrics, the machine and deep learning methods had F1-scores of 88%, 94%, and 94% respectively, regarding to crop detection. Subsequently, detected crops were turned into a binary mask and mixed with the NDVI background subtractor in order to detect weed in an indirect way. Once the weed image was obtained, the coverage percentage of weed was calculated by classical image processing methods. Finally, these performances were compared with the estimations of a set from weed experts through a Bland–Altman plot, intraclass correlation coefficients (ICCs) and Dunn’s test to obtain statistical measurements between every estimation (machine-human); we found that these methods improve accuracy on weed coverage estimation and minimize subjectivity in human-estimated data.

Internet es el mayor medio de difusión de información y el mayor canal de prestación de servicios que existe actualmente. Debido a que el número de sus usuarios se mantiene en constante crecimiento, se debe procurar por la inclusión de aquellas características que velan por el aseguramiento del acceso a la información de toda la población, incluyendo a las personas con necesidades especiales. En este sentido, es necesario asegurar el cumplimiento de los estándares de accesibilidad propuestos por el World Wide Web Consortium (W3C) a través de las Pautas de Accesibilidad de Contenido Web (WCAG) y las Mejores Prácticas de Web Móvil (MWBP). Diferentes autores afirman que, incluso teniendo conocimientos de las falencias de accesibilidad de las aplicaciones existentes, los desarrolladores presentan problemas en su evaluación, al igual que en la valoración de la usabilidad. Si bien existe una guía para realizar dicha evaluación, esta no está completa y los elementos que definen la evaluación aún son incipientes. En este sentido, es importante definir un método que permita evaluar no solo la usabilidad, sino también la accesibilidad de las aplicaciones web y móviles, sobre todo, considerando aquellos usuarios que poseen necesidades especiales. Con base en lo anterior, en este trabajo se propone un método para la evaluación de usabilidad y accesibilidad para aplicaciones móviles, desarrollado en seis fases iterativas, las fases iniciales del método buscan asegurar el cumplimiento de los niveles de accesibilidad deseados según el W3C; seguidamente, se busca el cumplimiento de la usabilidad aplicando las fases restantes del método, obteniendo como resultados mejoras en cada iteración. Al usar el método para evaluar la aplicación “Diccionario de Neologismo”, se evidencia una mayor detección de fallas en la implementación del estándar de W3C y mejoras en las respuestas obtenidas por medio de encuestas de satisfacción.

Introducción: En este documento se presenta una metodología multiobjetivo aplicada al problema del Planeamiento de la Expansión de la Transmisión (PET) cuando se consideran las incertidumbres en la demanda y la generación eólica. Objetivo: Obtener planes de expansión robustos que minimicen los costos de inversión y maximicen el uso del recurso eólico, teniendo en cuenta su incertidumbre y la introducida por la demanda. Metodología: La metodología propuesta se basa en la Metodología de Escenario Reducido para representar estas incertidumbres. En la formulación de la metodología se consideraron: el modelo de red en DC, los planes de expansión que minimizan la inversión, la reducción en la carga y la generación eólica. Para obtener el algoritmo multiobjetivo, utilizado para minimizar los costos de expansión y la reducción de la energía eólica, se implementó un NSGA-II mejorado y un conjunto de planes óptimos de expansión de Pareto. Resultados: Se presenta el desempeño de los planes de expansión, los cuales fueron evaluados y comparados con trabajos anteriores para demostrar la solidez del enfoque propuesto. Todas las pruebas se realizaron en los sistemas Garver e IEEE de 24 nodos. Conclusiones: Al observar el número de veces que el plan de expansión lleva a cero el corte de carga y la energía eólica desperdiciada, con respecto a un valor establecido en este trabajo, se tiene que la metodología propuesta presenta un índice de rendimiento superior al 75,16% para el sistema Garver y al 98,97% para el sistema IEEE de 24 nodos.

We report the first recorded case of partial erythrism in a frog belonging to the family Dendrobatidae, Mindo Poison Frog Epipedobates darwinwallacei Cisneros-Heredia and Yánez-Muñoz, 2010. In February 2019, we found an individual in the valley of Mindo, province of Pichincha, Ecuador showing dorsal surfaces uniformly orange, throat and posterior surfaces of legs black, and ventral surfaces yellow. Despite the atypic colouration, its general morphology coincides with E. darwinwallacei, and individuals with typical colouration for the species were abundant syntopically. We include photographs comparing the erythristic individual and a typical colouration frog from the same area. We provide a brief review of chromatic atypic colourations reported in Dendrobatoidea.

In this work, the antibacterial activity of Laureliopsis philippiana (Looser) essential oil was studied, and its kinetic release performance using different surface-functionalized nanostructured porous silicon (nPSi) was analyzed. Experimental results showed the high inhibitory effect of Laureliopsis philippiana essential oil against Staphylococcus aureus and Klebsiella pneumoniae. In addition, the essential oil was successfully loaded into different kinds of functionalized nPSi. FTIR measurements indicated the formation of stable complexes in the nPSi functionalization process. Specifically, chemical oxidized nPSi (nPSi-Ox), 3-aminopropyltriethoxysilane functionalized nPSi (nPSi-APTS), undecylenic acid-functionalized nPSi (nPSi-UAc), chitosan (nPSi-Chi) and β-cyclodextrin (nPSi-βCD) polymer functionalization on nPSi were studied. nPSi-Ox, nPSi-APTS, and nPSi-UAc were covalent functionalization, and nPSi-Chi and nPSi-βCD were obtained by electrostatic attachment. The kinetic study demonstrated a controlled release of up to 4 h for all the samples following a quasi-Fickian diffusion mechanism. Moreover, the use of functionalized nPSi-APTS and nPSi-UAc structures allows a more controlled kinetic release of Laureliopsis philippiana essential oil in comparison to the rest of the functionalization, increasing its availability and exposure to the environment.

Upper limb impairment is one of the most common problems for people with neurological disabilities, affecting their activity, quality of life (QOL), and independence. Objective assessment of upper limb performance is a promising way to help patients with neurological upper limb disorders. By using wearable sensors, such as an egocentric camera, it is possible to monitor and objectively assess patients’ actual performance in activities of daily life (ADLs). We analyzed the possibility of using Deep Learning models for depth estimation based on a single RGB image to allow the monitoring of patients with 2D (RGB) cameras. We conducted experiments placing objects at different distances from the camera and varying the lighting conditions to evaluate the performance of the depth estimation provided by two deep learning models (MiDaS & Alhashim). Finally, we integrated the best performing model for depth-estimation (MiDaS) with other Deep Learning models for hand (MediaPipe) and object detection (YOLO) and evaluated the system in a task of hand-object interaction. Our tests showed that our final system has a 78% performance in detecting interactions, while the reference performance using a 3D (depth) camera is 84%.

In the COVID-19 era, a direct relationship has been consolidated between the concentration of the pollutant carbon dioxide (CO2) and indoor disease transmission. For reducing its spread, recommendations have been established among which air renewal is a key element to improve indoor air quality (IAQ). In this study, a low-cost CO2 measurement device was designed, developed, assembled, prototyped, and openly programmed so that the IAQ can be monitored remotely. In addition, this clonic device was calibrated for correct data acquisition. In parallel, computational fluid dynamics (CFD) modeling analysis was used to study the indoor air flows to eliminate non-representative singular measurement points, providing possible locations. The results in four scenarios (cross ventilation, outdoor ventilation, indoor ventilation, and no ventilation) showed that the measurements provided by the clonic device are comparable to those obtained by laboratory instruments, with an average error of less than 3%. These data collected wirelessly for interpretation were evaluated on an Internet of Things (IoT) platform in real time or deferred. As a result, remaining lifespan of buildings can be exploited interconnecting IAQ devices with other systems (as HVAC systems) in an IoT environment. This can transform them into smart buildings, adding value to their refurbishment and modernization.

This editorial note presents a review of the publication times and the reasons for the rejection of manuscripts submitted for evaluation to Ingeniería e investigación Journal. Some adjustments have been made recently to the editorial policy of the journal that we consider important to share with authors and readers.

Identificar los beneficios de la colaboración sigue siendo un gran desafío para muchas cadenas de suministro, entre ellas las relacionadas con el sector de mensajería expresa. En esta investigación, la medición colaborativa del desempeño para una cadena de suministros del sector de mensajería expresa, actuará como una herramienta de prueba para identificar el ambiente propicio para colaborar. Se utilizó información real de una empresa del sector con la cual se desarrolló una simulación Montecarlo como herramienta de ayuda a la toma de decisiones para la gestión de la cadena colaborativa, determinando la relación entre el número de socios colaboradores y el porcentaje de captación del mercado en los costos de distribución, la utilidad operativa y el grado de participación de los colaboradores en los procesos de la cadena de suministro. Este enfoque ayudará a estas cadenas de suministro a obtener el máximo beneficio de las relaciones de colaboración, el cual puede ser utilizado por empresas dedicadas al servicio y distribución de mensajería expresa que estén interesadas en la colaboración.

Recently the new results of Scimago Journal Rank-SJR, Journal Citation Report-JCR and Google Scholar Metrics for journals have been updated and published. This editorial note presents a comparative analysis of 2016 and 2017 SJR ranking, pointing out differences in journal performance.

In recent Editorial letters of Ingeniería e Investigación the performance of engineering scientific journals has been reviewed to provide information with regard to their ranking, which could be used by editors and authors for improving their productivity. Journal performance refers to the set of indicators that allow to compare quantitatively different journals. This editorial letter revisits the topic and formulates the following question: what are the difference in performance of engineering journals?

Solar energy is one of the most strategic energy sources for the world’s economic development. This has caused the number of solar photovoltaic plants to increase around the world; consequently, they are installed in places where their access and manual inspection are arduous and risky tasks. Recently, the inspection of photovoltaic plants has been conducted with the use of unmanned aerial vehicles (UAV). Although the inspection with UAVs can be completed with a drone operator, where the UAV flight path is purely manual or utilizes a previously generated flight path through a ground control station (GCS). However, the path generated in the GCS has many restrictions that the operator must supply. Due to these restrictions, we present a novel way to develop a flight path automatically with coverage path planning (CPP) methods. Using a DL server to segment the region of interest (RoI) within each of the predefined PV plant images, three CPP methods were also considered and their performances were assessed with metrics. The UAV energy consumption performance in each of the CPP methods was assessed using two different UAVs and standard metrics. Six experiments were performed by varying the CPP width, and the consumption metrics were recorded in each experiment. According to the results, the most effective and efficient methods are the exact cellular decomposition boustrophedon and grid-based wavefront coverage, depending on the CPP width and the area of the PV plant. Finally, a relationship was established between the size of the photovoltaic plant area and the best UAV to perform the inspection with the appropriate CPP width. This could be an important result for low-cost inspection with UAVs, without high-resolution cameras on the UAV board, and in small plants.

The results of the most recent evaluation of the Colombian scientific journals, performed by Colciencias resorting to the Colombian Bibliographic Index - Publindex, was released recently. Several discussions have been made on the consequences. This document presents and analysis with a different perspective: is there something that authors and editors could do in order to improve the ranking of the journals? The document presents data and analysis applicable to engineering scientific journals.

This editorial note summarizes the most recent results about ranking and bibliometric indicators of the Ingeniería e Investigación journal. Some novelties with regard to the inclusion in one of the Latin American indexes are resported.

Never before has Engineering needed more from the support of society and society needed more from the advances of Engineering than now. However, there is a feeling of demotivation among the students to pursue Engineering programs, thus other careers are more desirable such as Administration, Economics, Journalism, Law and Humanities. In the first place, this occurs partially because technology is generally available to everyone, that is, everyone is a regular user of it, thus confusing its daily use (connect and use solutions) with the background complexity for creating and implementing it. In the second place, potential engineering students expect education in technology with immediate practical activities and with the minimum of formal theory, because in summary everything is so easy to use that they think it is not necessary to make things difficult with a thoroughly understanding of how to conceive, manufacture, operate, perform and of the final disposition of equipment and technical systems. Finally, the frequent outcome of studying an Engineering career could be another reason, since recent graduates often do not have the skills and knowledge demanded by the labor market and are received with unattractive salaries, in addition to the discovery that graduates of other careers with little technical and engineering preparation use technologies and turn them into highly profitable businesses.

Nowadays, the world is in a transition towards renewable energy solar being one of the most promising sources used today. However, Solar Photovoltaic (PV) systems present great challenges for their proper performance such as dirt and environmental conditions that may reduce the output energy of the PV plants. For this reason, inspection and periodic maintenance are essential to extend useful life. The use of unmanned aerial vehicles (UAV) for inspection and maintenance of PV plants favor a timely diagnosis. UAV path planning algorithm over a PV facility is required to better perform this task. Therefore, it is necessary to explore how to extract the boundary of PV facilities with some techniques. This research work focuses on an automatic boundary extraction method of PV plants from imagery using a deep neural network model with a U-net structure. The results obtained were evaluated by comparing them with other reported works. Additionally, to achieve the boundary extraction processes, the standard metrics Intersection over Union (IoU) and the Dice Coefficient (DC) were considered to make a better conclusion among all methods. The experimental results evaluated on the Amir dataset show that the proposed approach can significantly improve the boundary and segmentation performance in the test stage up to 90.42% and 91.42% as calculated by IoU and DC metrics, respectively. Furthermore, the training period was faster. Consequently, it is envisaged that the proposed U-Net model will be an advantage in remote sensing image segmentation.

Continuing with the call for indexing Colombian Specialised Scientific Journals – Publindex, Colciencias recently published a report about its development. This editorial note from Engineering and Research Journal aims to show the readers some of the results from the process mentioned before, especially because such report has had limited access and, in general terms, authors do not know about it.

A popularização das novas tecnologias de fabricação digital vêm alterando os modos de produção da sociedade contemporânea. O compartilhamento aberto de informações, dentro de uma nova lógica produtiva, tem o potencial de mudar o sistema econômico vigente, e de até transformar os rumos da globalização em curso. O presente trabalho aborda um novo sistema construtivo de fonte aberta que utiliza a fabricação digital na produção de habitações de baixo custo. O projeto Casa Revista, desenvolvido no laboratório LAMO3D da FAU-UFRJ, tem como objetivo alimentar a renovação da produção independente de habitações, inserindo uma nova tecnologia construtiva no vocabulário popular e explorando seus potenciais. Baseado no sistema WikiHouse de construção, o projeto alia conhecimento global à produção local, tropicalizando o seu conteúdo. A experiência contou com a prototipagem em escala real de um primeiro modelo, usinado e montado por estudantes da graduação, a fim de testar a qualidade do sistema e sua viabilidade técnica de implementação como tecnologia social. O projeto mostrou-se intuitivo, de complexidade simples e rico em possibilidades de manipulação e aperfeiçoamento. São os projetos e tecnologias de fonte aberta que vêm promovendo o alargamento de usos do conhecimento por novos atores, gerando uma dispersão da produção. Cabe a nós arquitetos reconhecermos esse potencial e moldar suas infinitas possibilidades de aplicação.

In previous editorial letters, data regarding the Journal positioning, visibility and management have been presented. Regarding positioning in citational databases, in Pavas (2015), a comparison among the results in databases like Scimago Journal Rank (SJR), Journal Citation Report (JCR), and Google Scholar (GS) is shown. In Pavas (2016a), the h5 index of the Colombian engineering journals is highlighted. In terms of the journal’s visibility, in Pavas (2016b), indicators up to December 2016 are presented. The editorial team of Ingeniería e Investigación Journal (I&I for their initials in Spanish) wants to share with the authors and readers some of their recent results.

This study describes the use of erythrocytes (RBCs) of loggerhead turtles as in vitro models for evaluating their toxicity to methylmercury. Blood samples of loggerhead turtles that were born in the Colombian Caribbean were used. The LC50 of RBCs to methylmercury was determined at 96 h using methylmercury concentrations of 0.5–100 mg L−1. Next, the viability of the RBCs and the activity of the enzymes superoxide dismutase (SOD), glutathione S-transferase (GST), and lipid peroxidation by malondialdehyde (MDA) at 6 and 12 h of exposure to acute concentrations of 0, 1, and 5 mg L−1 were evaluated. The LC50 for loggerhead turtle RBCs was 8.32 mg L−1. The cell viability bioassay of RBCs exposed for 12 h only showed 100% cell viability. Increasing in vitro MeHg concentrations caused a corresponding increase in MDA concentration as well as decreases in the activities of SOD and GST. The RBCs represent an excellent model for ecotoxicological studies and SOD, GST, and MDA are biomarkers of environmental pollution and oxidative stress in loggerhead turtles. This was the first study conducted on loggerhead turtle where the response of RBCs to MeHg-induced oxidative stress is evaluated.

Scope management allows project managers to react when a project underperforms regarding schedule, budget, and/or quality at the execution stage. Scope management can also minimize project changes and budget omissions, as well as improve the accuracy of project cost estimates and risk responses. For scope management to be effective, though, it needs to rely on a robust work breakdown structure (WBS). A robust WBS hierarchically and faithfully reflects all project tasks and work packages so that projects are easier to manage. If done properly, the WBS also allows meeting the project objectives while delivering the project on time, on budget, and with the required quality. This paper analyzes whether the integration of a cost breakdown structure (CBS) can lead to the generation of more robust WBSs in construction projects. Over the last years, some international organizations have standardized and harmonized different cost classification systems (e.g., ISO 12006-2, ISO 81346-12, OmniClass, CoClass, UniClass). These cost databases have also been introduced into building information modeling (BIM) frameworks. We hypothesize that in BIM environments, if these CBSs are used to generate the project WBS, several advantages are gained such as sharper project definition. This enhanced project definition reduces project contradictions at both planning and execution stages, anticipates potential schedule and budget deviations, improves resource allocation, and overall it allows a better response to potential project risks. The hypothesis that the use of CBSs can generate more robust WBSs is tested by the response analysis of a questionnaire survey distributed among construction practitioners and project managers. By means of structural equation modeling (SEM), the correlation (agreement) and perception differences between two 250-respondent subsamples (technical project staff vs. project management staff) are also discussed. Results of this research support the use of CBSs by construction professionals as a basis to generate WBSs for enhanced project management (PM).

Power transformer failures have a significant impact on electrical systems reliability, as they compromise the electricity delivery. Failures impact the operational cost of electric utilities as they endanger the accomplishment of power commitments. Power transformer failure rate can be modeled from its health condition, which is determined from different condition parameters. This paper is aimed to compare different maintenance schemes that allow the asset to be available the longest possible time. The power transformer operation is represented considering actual electric load profiles and temperature. Electrical and thermal transformer parameters are taken from manufacturer tests and technical standards. An electrical-thermal model is employed to estimate the life span reduction and temperature changes. From life span and loading, the health condition is determined, so as the effects of different maintenance schemes. The failure rates are calculated for unmaintained conditions and different maintained schemes, allowing to determine their effects on transformer reliability. Optimal maintenance schemes are determined and the expected benefits in failure rate reduction, asset reliability and life span extension are presented. As a result, it was found that certain time-based maintenance schemes provide better transformer reliability performance in comparison to condition based schemes, allowing to reduce the interruptions and extending the life of the transformer.

Se revisa la visibilidad de la Revista Ingeniería e Investigación en diversas bases de datos.

La fibrilación auricular (FA) es la más común de la arritmia cardiaca y su prevalencia aumenta con la edad. Las arritmias cardiacas más peligrosas y complejas son el resultado del fenómeno conocido como reentrada. Se ha planteado que los músculos pectíneos proveen un sustrato para la actividad reentrante durante la FA. En estudios experimentales la vena cava ha sido asociada con actividad ectópica que promueve la generación de reentradas. En este trabajo se incorporaron los cambios generados por el remodelado eléctrico a un modelo de potencial de acción (PA) de miocito auricular, acoplado con un modelo tridimensional anatómicamente realista de aurícula humana con direccionamiento de fibras. Al aplicar un foco ectópico en la cercanía del ostium de la vena cava inferior se encuentra una relación entre esta actividad y la generación de reentradas en los músculos pectíneos. Una reentrada funcional que se repite en el tiempo es favorecida por la anatomía de los músculos pectíneos, las propiedades anisotrópicas y la distribución no uniforme en el tejido tridimensional. Se encontró la existencia de un camino de conducción preferencial que facilita la iniciación de reentradas afectando el esquema de conducción y la capacidad de inducción y desarrollo de arritmias.

Most construction managers use deterministic scheduling techniques to plan construction projects and estimate their duration. However, deterministic techniques are known to underestimate the project duration. Alternative methods, such as Stochastic Network Analysis, have rarely been adopted in practical contexts as they are commonly computer-intensive, require extensive historical information, have limited contextual/local validity and/or require skills most practitioners have not been trained for. In this paper, we propose some mathematical expressions to approximate the average and the standard deviation of a project duration from basic deterministic schedule information. The expressions’ performance is successfully tested in a 4100-network dataset with varied activity durations and activity durations variability. Calculations are quite straightforward and can be implemented manually. Furthermore, unlike the Project Evaluation and Review Technique (PERT), they allow drawing inferences about the probability of project duration in the presence of several critical and subcritical paths with minimal additional calculation.

Model-driven software product lines (MD-SPLs) are created from domain models which are transformed, merged and composed with reusable core assets, until software products are produced. Model transformation chains (MTCs) must be specified to generate such MD-SPLs. This paper presents a framework for creating platform-independent MD-SPLs; such framework includes a domain specific language (DSL) for platform-independent MTC specification and facilities platform-specific MTC generation of several of the most used model transformation frameworks. The DSL also allows product line architects to compose generation taking the need for model transformation strategy and technology interoperability into account and specifying several types of variability involved in such generation.

La Ingeniería de Software Basada en Componentes (CBSE) pretende mejorar la modularización del software y la inserción de preocupaciones arquitecturales. Refactorizar código Java legado con CBSE en mente requiere evaluar primero el cumplimiento del código legado con los principios de la programación por componentes. En este artículo presentamos un portafolio de reglas para evaluar el cumplimiento de la propiedad de Integridad de Comunicación en código Java legado; esta propiedad es una de las mayores fortalezas del enfoque CBSE. Proponemos estas reglas para identificar tipos componente y así proveer una medida de la construcción de componentes CBSE de una aplicación. Con el objetivo de ayudar a los desarrolladores y al personal responsable del mantenimiento de código legado cuando se hace necesario refactorizar sus aplicaciones, nuestro trabajo nos lleva a definir un conjunto de acciones de refactorización. En este artículo también presentamos resultados de pruebas, comparaciones y análisis de las salidas logradas luego de refactorizar varias aplicaciones Java.

Una trayectoria es un registro de la evoluciónde la posición de un objeto móvil. Por ejemplo,un vehículo que se mueve en el espacio durante unintervalo de tiempo. Una trayectoria se representamediante una secuencia de observaciones que indicanla posición y el tiempo en el que fue tomada cadaobservación. CB-SMoT es un algoritmo que identificalas partes de una trayectoria durante las cuales elobjeto mantuvo una velocidad promedio por debajode un límite dado. En este artículo se propone unaextensión para dicho algoritmo que permite identificarlas partes de una trayectoria durante las cualesel objeto mantuvo una velocidad promedio entre observacionespor debajo de un límite dado. Esto posibilitala identificación, por ejemplo, de violacionesa un límite de velocidad que no son advertidas porel algoritmo original. Para el estudio se usó el sistemade gestión de bases de datos PostgreSQL y losalgoritmos se implementaron en su lenguaje de programación,llamado PL/pgSQL. Además, se hicieronexperimentos con 100 trayectorias de vehículos conel propósito de mostrar la utilidad y la viabilidad de lapropuesta.

En este trabajo se presenta el estudio efectuado con el propósito de analizar la congruencia de los métodos de interpolación en la generación de mapas de ruido. Para esto, se realizaron mediciones del nivel de presión sonora equivalente de acuerdo con la resolución 0627 del Ministerio del Medio Ambiente, Vivienda y Desarrollo Territorial en dos áreas de la ciudad de Medellín. Para la obtención de las curvas de niveles de ruido se utilizaron los métodos de interpolación Kriging e IDW en el software SIG ArcGis. En el aplicativo se varió la configuración de los parámetros de entrada y se efectuó un análisis estadístico para determinar qué modelo presentaba resultados más precisos. Por último, se llevó a cabo una valoración del mapa de ruido obtenido comparándolo con la legislación colombiana.

The models to recreate traf c traces generated in a communications network can be used in predictions and estimates of traffic in order to optimize the use of network resources, one of these is the model On/Off, which allows describing the behavior of aggregate traf c by one or more sources of information. The importance of this article focuses on the impact that this model has been applied to various communications technologies, for this are evaluated and contrasted different types of documents proposed by several authors. Basedon the results, arguably Models On/Off are still in place for traf c modeling, and can be applied at any level of ISO/OSI model. Also, the results observed indicate that depending on the type of power On/Off (single or multiple) the approaches vary greatly, and the mathematical complexity that can have models with source multiplexing On/Off could be a constraint to take into account in its implementation.

This paper proposes k-means clustering algorithm to identify voltage sags patterns and group fault zones with similar impact in high and medium voltage electric. The proposed methodology comprises three stages. First, network modeling and faults simulation were performed in order to get information about voltage sags caused by faults in the transmission system. Voltage sags patterns were identified at the second stage by means of a k-means clustering algorithm, allowing the determination of fault zones. Using the power quality measurements data base of the major electricity utility of Bogotá, voltage sags were classified according to the previously determined voltage sags patterns. At the third stage of the methodology a comparison between simulated and measured sags is performed, allowing the identification of sags caused by faults.

Currently the impact of high efficient lighting devices such as compact fluorescent lamps (CFL) and light emitting diodes (LED) is an important concern for the electrotechnical community. This paper makes a contribution towards determining the impact of these devices on electric grid power quality and efficiency, proposed by means of applying FBD-power theory to the currents absorbed by CFLs and LEDs. An analysis of the waveform distortion regarding IEEE standard 519 and efficiency detriment quantification are presented.

Las técnicas de descomposición en sumas de cuadrados (SOS) permiten emplear métodos numéricos para probar la positividad de funciones polinómicas multivariables resolviendo problemas de programación en semidefinida. Teniendo en cuenta que generalmente es difícil encontrar funciones de Lyapunov para realizar análisis de estabilidad en sistemas no linea-les, con el uso de t técnicas SOS se utiliza una herramienta computacional para resolver este problema, planteando las condiciones de estabilidad como un problema SOS y obteniendo la solución con un toolbox de Matlab. Para mostrar el uso de esta herramienta se presentan ejemplos simples de los conceptos de SOS, análisis de estabilidad para sistemas no lineales polinomios, racionales, con incertidumbre en los parámetros y de sistemas conmutados con una aproximación en polinomio. Con dicha aproximación se encuentran funciones adecuadas para demostrar estabilidad asintótica para estos sistemas.

The aim of the present paper is to show the evident advantages of using simulation techniques in foundry technologies. The considerable save of time and economic resources that implies the use of this techniques has spread worldwide. As in Cuba the use is not extended to the foundries, we intend to demonstrate the possibilities of the use of simulation software for the development of casting technologies.

En respuesta a la necesidad de dar valor agregado a la leche producida en los municipios de Salamina, Aranzazu y Viterbo, del departamento de Caldas, se formuló un proyecto con el objetivo general de desarrollar quesos madurados con destino a los mercados nacional e internacional. Para ello, inicialmente se realizó un estudio de caracterización físico-química de la leche cruda proveniente de esos municipios, encontrándose que los estándares de calidad como densidad (1.030-1.033 g/l), extracto seco total (11.30%), y extracto seco desengrasado (8,30%) de la leche de los dos primeros se hallan en el rango considerado normal para la elaboración de quesos. Posteriormente, se desarrollaron los procesos productivos de los quesos Cammembert, Cheddar, Emmental, Gruyere y Gouda, en la Unidad Tecnológica de alimentos, de la Universidad de Caldas, bajo un diseño experimental de pre-experimento con una sola medición y utilizando las técnicas validadas actualmente para su elaboración; di- chos procesos fueron analizados con las características sensoriales y la evolución de los fenómenos de maduración (cambios de proteólisis y lipólisis). Entre los resultados obtenidos se destaca la estandarización de los procesos para quesos Cammem- bert, Cheddar y Gouda, que alcanzaron las mayores preferencias sensoriales y una maduración óptima verificada mediante pa- rámetros como grado de acidez, grado de maduración, acidez, porcentaje de proteína y humedad. De esta manera se pudo comprobar que es factible desarrollar algunos quesos madurados con leches procedentes de los municipios del norte de Caldas y transferir los resultados a sus centros de acopio para darle un mayor valor agregado a la producción de leche cruda a nivel semiindustrial.

The assumption of only main effects in Conjoint Analysis methods has created a debate whether to focus or not on the impact of interactions in determining the most prefered combination of attributes of a product. In this research a comparison of Conjoint Value Analysis CVA and Choice-Based Conjoint CBC surveys were undertaken to contrast them through utility scores, importance values of attributes and goodness-of-fit using ready to drink beverages as the subject. The main effects assumption in the CVA composition rule was compared to the interaction terms in the CBC one. Two scenarios were developed; the first one considered inner characteristics of the subject and a sample size of 250 respondents. The second one considered the presentation characteristics of the subject and a sample size of 150 respondents. The two higher total utility scores were obtained in the CBC using an interactive composition rule. In Scenario 1 a higher goodness-of-fit was found in the CBC, including significant interactions, in contrast with Scenario 2, where no interactions were found, and CVA had a higher goodness-of-fit.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and its prevalence increases with age. The most dangerous and complex arrhythmias are the result of a phenomenon known as reentry. In experimental studies, the vena cava has been associated with ectopic activity that promotes the generation of reentries. The changes caused by electrical remodeling in an atrial myocyte action potential model (AP), coupled with an anatomically realistic three-dimensional model of human atria with orientation fibers were incorporated in this work. When applying an ectopic focus to the nearby ostium of the inferior vena cava, a relationship between this activity and the generation of reentries in the pectinate muscles is found. A functional reentry repeated in time is favored by the pectinate muscles anatomy, the anisotropic properties and the non-uniform distribution in the three-dimensional tissue. The existence of a preferential conduction pathway facilitates the initiation of reentries affecting the conduction scheme. Therefore, the capacity of induction and development of arrhythmias are found.

In 2017, the aggregate electrification ratio in Indonesia has been achieving 92.8%. However, some rural areas such as in Maluku and Papua Islands still have low electrification ratio (~70%). One of the main problems in supplying electricity to rural areas in Indonesia is the geographical concern which consisted of islands leading to the difficulty of electricity grid development. In some areas, diesel power plant has been being built to supply the electricity. However, it causes another problem to transport the primary energy source to the targeted area which would increase the cost of electricity supply. Besides, it also needs investment cost to build transmission and distribution systems, as well as the maintenance expenses. To resolve this issue, a new scheme of battery-based Tabung Listrik or TaLis (DC-based power bank) and DC house system is proposed to be the solution to provide electricity to rural areas. The potential of local renewable energy sources such as biomass, hydro, wind, and solar could be utilized to be charging sources of batteries (TaLis). This study presents the TaLis prototype, DC house installation, supply chain process and charging scheme of TaLis, and cost comparison between the proposed system with other existing power systems such as communal PV farm and diesel power plant. We found that TaLis and DC house system provided the least cost of electricity production compared to other power systems, i.e. $0.88/kWh for TaLis and DC house system, $1.65/kWh for diesel power plant, and $1.47/kWh for communal PV farm. Implementation of this approach is expected to improve the welfare and quality of life of rural communities immediately.