Artículos Ingeniería

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  • Publication
    Linking physical violence to women’s mobility in Chile
    (2023) Contreras, Hugo; Candia Vallejos, Cristian; Troncoso, Rodrigo; Ferres, Leo; Bravo, Loreto; Rodriguez-Sickert, Carlos
    Despite increased global attention on violence against women, understanding the factors that lead to women becoming victims remains a critical challenge. Notably, the impact of domestic violence on women’s mobility—a critical determinant of their social and economic independence—has remained largely unexplored. This study bridges this gap, employing police records to quantify physical and psychological domestic violence, while leveraging mobile phone data to proxy women’s mobility. Our analyses reveal a negative correlation between physical violence and female mobility, an association that withstands robustness checks, including controls for economic independence variables like education, employment, and occupational segregation, bootstrapping of the data set, and applying a generalized propensity score matching identification strategy. The study emphasizes the potential causal role of physical violence on decreased female mobility, asserting the value of interdisciplinary research in exploring such multifaceted social phenomena to open avenues for preventive measures. The implications of this research extend into the realm of public policy and intervention development, offering new strategies to combat and ultimately eradicate domestic violence against women, thereby contributing to wider efforts toward gender equity.
  • Publication
    Enhanced social connectivity in hybrid classrooms versus academic centrality in online settings
    (2023) Pulgar, Javier; Ramírez, Diego; Candia Vallejos, Cristian
    Social learning, the ability to perceive, interpret, and assess the behavior of one’s peers, is crucial for forming meaningful relationships and succeeding in various learning environments. Yet, the rise of online and hybrid settings poses new challenges to socialization. Here, we study the social interactions among 191 high school physics students in Chile, comparing online and hybrid classrooms that were assigned in the COVID-19 pandemic context. We found that students in hybrid settings were more connected and more likely to form casual relationships outside their immediate friend groups, which allowed them to gather new information from diverse sources. Along the same lines, in online classrooms, students who excelled in physics occupied more central positions in social networks. This trend was not evident in hybrid settings, suggesting that when social cues are limited, academic performance gains greater importance in establishing social hierarchies and potentially limiting access to diverse information. Our study highlights the importance of social interactions in educational contexts and raises questions about the impact of relational inaccessibility on virtual learning.
  • Publication
    Relevance of machine learning techniques in water infrastructure integrity and quality : a review powered by natural language processing
    (2023) García, José; Leiva-Araos, Andres; Diaz-Saavedra, Emerson; Moraga, Paola; Pinto, Hernan; Yepes. Víctor
    Water infrastructure integrity, quality, and distribution are fundamental for public health, environmental sustainability, economic development, and climate change resilience. Ensuring the robustness and quality of water infrastructure is pivotal for sectors like agriculture, industry, and energy production. Machine learning (ML) offers potential for bolstering water infrastructure integrity and quality by analyzing extensive data from sensors and other sources, optimizing treatment protocols, minimizing water losses, and improving distribution methods. This study delves into ML applications in water infrastructure integrity and quality by analyzing English-language articles from 2015 onward, compiling a total of 1087 articles. Initially, a natural language processing approach centered on topic modeling was adopted to classify salient topics. From each identified topic, key terms were extracted and utilized in a semi-automatic selection process, pinpointing the most relevant articles for further scrutiny, while unsupervised ML algorithms can assist in extracting themes from the documents, generating meaningful topics often requires intricate hyperparameter adjustments. Leveraging the Bidirectional Encoder Representations from Transformers (BERTopic) enhanced the study’s contextual comprehension in topic modeling. This semi-automatic methodology for bibliographic exploration begins with a broad topic categorization, advancing to an exhaustive analysis of each topic. The insights drawn underscore ML’s instrumental role in enhancing water infrastructure’s integrity and quality, suggesting promising future research directions. Specifically, the study has identified four key areas where ML has been applied to water management: (1) advancements in the detection of water contaminants and soil erosion; (2) forecasting of water levels; (3) advanced techniques for leak detection in water networks; and (4) evaluation of water quality and potability. These findings underscore the transformative impact of ML on water infrastructure and suggest promising paths for continued investigation.
  • Publication
    Pre-Andean deformation and its influence on the shortening of the Southern Precordillera, Mendoza, Argentina
    (2023) Gutierrez Seia, Milagros; Jara, Pamela; Bertoa del Llano, Macarena; Richard, Andrés; Lothari, Lucas; Giambiagi, Laura Beatriz
    Andean structures preserve evidence of previous periods of deformation along the proto-Pacific margin of Gondwana. Particularly, the Southern Precordillera, in the southern Central Andes, presents a combination of different structural domains and a double vergence related to the reactivation of pre-Andean structures. This combination and the superposition of deformational events make it difficult to understand the stratigraphic systems and the evolution of the region. This contribution presents detailed information about the structures and evolution of the Southern sector of the Precordillera, focusing on the control exerted by Paleozoic structures over the recent Andean deformation, and the deformational styles of this fold-and-thrust belt. Three main structural domains are recognized. The western domain is characterized by high-angle back-thrusts that concentrate the highest amount of uplift. The central domain is composed of reverse double-vergence faults, and high-angle strike-slip faults. The eastern domain is characterized by pure contractional deformation and only east-verging structures. Four deformational events are recorded and analyzed along the Southern Precordillera at 32°30′S: (1) an Early Paleozoic compressional event, (2) a Late Paleozoic compressional event, (3) a Triassic extensional event, and (4) the Cenozoic Andean compressional event. Our model for the Cenozoic deformation of the Southern Precordillera is restricted to three stages of deformation. During the first stage, Paleozoic west-verging faults are reactivated. The second stage implies reactivation of Paleozoic and Permian-Triassic structures and the generation of reverse Andean faults. The final stage consists of the generation of NE-SW Andean thrusts.
  • Publication
    Oscillation results for a nonlinear fractional differential equation
    (2023) Bosch, Paul; Rodríguez, José M.; Sigarreta, José M.
    In this paper, the authors work with a general formulation of the fractional derivative of Caputo type. They study oscillatory solutions of differential equations involving these general fractional derivatives. In particular, they extend the Kamenev-type oscillation criterion given by Baleanu et al. in 2015. In addition, we prove results on the existence and uniqueness of solutions for many of the equations considered. Also, they complete their study with some examples.
  • Publication
    A biomimetic smart kirigami soft metamaterial with multimodal remote locomotion mechanisms
    (2023) Silva, Benjamín; Govan, Joseph; Zagal, Juan Cristóbal; Grossi, Bruno; Roldan, Alejandro; Nunez, Alvaro S.; Acuña, Daniel; Palza, Humberto
    Several efforts have been made to develop walking smart soft robots through different strategies such as the use of complex aligned magneto-active materials. Here, we show a simple approach for the design of a smart soft robot using an elastomer film with randomly distributed ferrimagnetic nanoparticles able to be remotely controlled by a magnetic field. The magneto-active robot has a rotating-square kirigami geometry resulting in a flexible smart auxetic metamaterial (i.e., a negative Poisson-ratio structure). Alongside the standard translational locomotion on a smooth-surface under a steady magnetic force, the auxetic kirigami structure mimics the crawling-locomotion of worms over a high-roughness surface under an oscillatory horizontal field, even climbing vertical-obstacles. A theoretical understanding for this new locomotion mechanism stresses the relevance of the kirigami metamaterial design and the ferrimagnetic response of the particles. The soft robot can also transport a payload having weights higher than the weight of the smart elastomeric film. The smart auxetic structure further presents a rolling locomotion by properly orienting the magnetic field, meaning multiple remote locomotion mechanisms.
  • Publication
    Optimizing the wine transportation process from bottling plants to ports
    (2023) Basso, Franco; Contreras, Juan Pablo; Pezoa, Raúl; Troncozo, Alejandro; Varas, Mauricio
    The wine industry is a highly competitive sector for which any efficiency improvement in the wine supply chain plays a critical role in maintaining or increasing profitability. Literature shows several successful applications of operational research tools at each stage of the wine production process. However, unlike other stages, the transportation and distribution phase has not been given the same attention in the specialized literature. To bridge this gap, this article proposes an integer linear programming model to jointly determine a plan for the bottling and transportation of products to ports in order to minimize inventory, freight, and delay costs. This model can be optimally solved in less than one day for small instances of up to 25 jobs. In practice, however, some industrial instances can easily exceed 200 jobs, which precludes the use of this model to support decision-making. To cope with this issue, we devise a two-stage procedure that generates good-quality solutions for industrial-size instances of this problem in reasonable computing times. Particularly, we show that the GAP of the proposed heuristic solution is relatively low for a wide range of instances. Finally, a case study is conducted on a medium-sized Chilean winery we worked with, where the planning generated by the proposed heuristic reduces the costs corresponding to the transportation stage by 45.3% in the best case, compared to the initial planning of the winery.
  • Publication
    On the variable inverse sum deg index
    (2023) Molina, Edil D.; Bosch, Paul; Sigarreta, José M.; Tourís , Eva
    Several important topological indices studied in mathematical chemistry are expressed in the following way , where is a two variable function that satisfies the condition , denotes an edge of the graph and is the degree of the vertex . Among them, the variable inverse sum deg index , with , was found to have several applications. In this paper, we solve some problems posed by Vukičević [1], and we characterize graphs with maximum and minimum values of the index, for , in the following sets of graphs with vertices: graphs with fixed minimum degree, connected graphs with fixed minimum degree, graphs with fixed maximum degree, and connected graphs with fixed maximum degree. Also, we performed a QSPR analysis to test the predictive power of this index for some physicochemical properties of polyaromatic hydrocarbons.
  • Publication
    On new Milne-type inequalities and applications
    (2023) Bosch, Paul; Sigarreta, José M.; RODRIGUEZ GARCIA, JOSE MANUEL
    Inequalities play a major role in pure and applied mathematics. In particular, the inequality plays an important role in the study of Rosseland’s integral for the stellar absorption. In this paper we obtain new Milne-type inequalities, and we apply them to the generalized Riemann–Liouville-type integral operators, which include most of the known Riemann–Liouville integral operators.
  • Publication
    Necesidades arquitectónicas en viviendas de personas en situación de discapacidad
    (2023) Valderrama-Ulloa, Claudia; Bucarey, Viviana; Marchetti Juan Pablo
    Housing represents encounter, memories and security, but for people with disabilities some of its characteristics can become barriers to its full use. If disability is considered to be a poor relationship between environment and capacity. Housing may be inaccessible for this group of people. Based on the components of the International Classification of Functioning, Disability and Health, of the World Health Organization, and the application of 16 semi-structured interviews, this research analyzed the architectural barriers and identified the needs faced by people with Alzheimer, Parkison, blindness, children on the autism spectrum, the elderly, wheelchair users and people with deafness in relation to carrying out general tasks and demands, communication, mobility, self-care and domestic life inside the homes. Among the spaces with the greatest barriers are the bathroom and the kitchen for most of the cases analyzed. On the other hand, various strategies were observed that the interviewees use to cope with these barriers and increase their well-being or reduce the risks in the activities of daily living inside the dwellings.
  • Publication
    Microbial community and enzyme activity of forest plantation, natural forests, and agricultural land in chilean coastal cordillera soils
    (2023) Rivas, Yessica; Aponte, Humberto; Rivera-Salazar, Diego; Matus, Francisco; Martínez, Oscar; Encina, Carolina; Retamal-Salgado, Jorge
    Despite the global expansion of forest plantations in Chile, their effect on biology properties of soil has still been only scarcely studied. Land use change in the Chilean Coastal Cordillera (36° to 40° S) is mainly attributed to the conversion of native forest to agriculture and forest plantations (Eucalyptus globulus and Pinus radiata de Don). The aim of this paper was to evaluate the changes in microbial composition (PCR-DGGE) and enzyme activity after the substitution of a native forest (e.g., Nothofagus spp.) by fast-growing exotic species and cropping. The most important factors that influence the abundance and diversity of bacteria and the fungi community were the soil organic matter (SOM) content, phosphorous (P-Olsen), calcium (Ca), boron (B), and water-holding capacity. These variables can better predict the microbial community composition and its enzymatic activity in the surface Ah horizon. Land use change also affected chemical soil properties of biogeochemical cycles. However, to deeply understand the connection between chemical and physical soil factors and microbial community composition, more research is needed. On the other hand, the expansion of forest plantations in Chile should be subject to legislation aimed to protect the biological legacy as a strategy for forest productivity as well as the soil microbial biodiversity.
  • Publication
    Implementation of a course on disruptive technologies for nursing students in Chile
    (2023) Contreras Romo, Jorge Sebastián; Cepeda Salas, Andrés Octavio
    Several institutions and countries have recognized the need to integrate disruptive technologies in the training of health professionals. An elective course on disruptive technologies in health for nursing was developed, structured in 5 units: a) innovation in health and nursing, b) creation of apps and virtual environments, c) digital manufacturing for nursing, d) sensors and internet of things, and e) data science in health. For its implementation, the didactic model proposed by Jorba and Sanmartí was considered; and for the evaluation of the units and the impact of the course, Urquidi's extended model of technological adoption was used. Forty-four students participated (39 women and 5 men), with an average age of 23 years. According to the technology acceptance model, statistically significant differences were found between the pre- and post-intervention groups in all dimensions of the model (Wilcoxon test, p < 0.05). In addition, a positive correlation was found between ease of use, subjective norm and intention to use the technologies taught. The implementation of the disruptive technologies course proved to be effective in the development of technological skills among nursing students in Chile.
  • Publication
    Generation of soil maps permeability. Case study in two cantons of Loja province, Ecuador
    (2023) Espinosa Marín, Jorge Andrés; Rivera, Diego; Haro Prado, Renato
    The generation of permeability maps is based on the analysis and interpretation of geology, environmental morphology, land use, and slope, which enables the selection of sampling areas with similar characteristics. The method represents the integration of the physical characteristics of the study area and then determines the infiltration capacity differences in the most representative geopedologic units. In determining the basic data, minidisc infiltrometers were used to perform seventy-two infiltration tests in different types of soils with varying organic matter content, texture, soil structure, and vegetation cover, which showed the spatial variability that exists in two cantons of Loja province, Ecuador. In addition, it was observed that the infiltration rate depended mainly on the content of the organic matter in the soil and is consistent with information collected on permeability worldwide. In this study, generated pedotransfer function (FTP) coefficient of determination R. 0.78, the determination of the coefficient indicates a satisfactory estimate of the permeability with the variables that were analyzed; in addition, the methodology for assessing the permeability was suitable for the conditions of this investigation. For this reason, the method described here should be tested in other areas of the country with a greater number of field trials and with more variable contents of organic matter and soil textural classes.
  • Publication
    From co-location patterns to an informal social network of gig economy workers
    (2023) Pilatti, Gustavo; Candia, Cristian; Montini, Alessandra; Pinheiro, Flávio L.
    The labor market has transformed with the advent of the gig economy, characterized by short-term and flexible work arrangements facilitated by online platforms. As this trend becomes increasingly prevalent, it presents unique opportunities and challenges. In this manuscript, we comprehensively characterize the social networks of gig economy workers in each of the 15 cities studied. Our analysis reveals a scaling relationship between networks and the city population. In particular, we note the high level of modularity of the networks, and we argue that it results from the natural specialization of couriers along different areas of the cities. Furthermore, we show that degree and betweenness centrality is positively correlated with income but not with tenure. Our findings shed new light on the social organization of the gig economy workers and provide valuable insights for the management and design of gig economy platforms.
  • Publication
    Evaluación de la accesibilidad para sistemas de transporte subterráneo: análisis del metro de Santiago - Chile
    (2023) Navas, Liborio; Valderrama-Ulloa, Claudia; Ferrada, Ximena; Contreras, Jorge; Gimenez, Zulay
    Considerando que una parte importante de la población mundial vive con algún tipo de discapacidad y que la esperanza de vida aumenta, el hecho de tener un transporte accesible permitiría que las personas mejoraran su calidad de vida, accediendo a más oportunidades socioeconómicas. A partir de un diseño descriptivo mixto (cualitativo etnográfico y cuantitativo), este artículo presenta una herramienta de evaluación del nivel de accesibilidad en el uso del tren subterráneo para personas con discapacidad visual, física, cognitiva y auditiva. Se analizaron los datos de 30 estaciones del Metro de Santiago de Chile, estudiando el desplazamiento desde el exterior a la estación, la permanencia en zona de pagos y el desplazamiento hacia andenes y combinaciones. De los indicadores evaluados, los que tienen relación con el desplazamiento hacia el andén son los que presentan menores niveles de accesibilidad, ya que no responden a todas las necesidades para los distintos tipos de discapacidad analizados.
  • Publication
    Estimation of trip purposes in public transport during the COVID-19 pandemic: The case of Santiago, Chile
    (2023) Pezoa, Raúl; Basso, Franco; Quilodrán, Paulina; Varas, Mauricio
    The COVID-19 pandemic strongly affected the mobility of people. Several studies have quantified these changes, for example, measuring the effectiveness of quarantine measures and calculating the decrease in the use of public transport. Regarding the latter, however, a low level of understanding persists as to how the pandemic affected the distribution of trip purposes, hindering the design of policies aimed at increasing the demand for public transport in a post-pandemic era. To address this gap, in this article, we study how the purposes of trips made by public transport evolved during the COVID-19 pandemic in the city of Santiago, Chile. For this, we develop an XGBoost model using the latest available origin-destination survey as input. The calibrated model is applied to the information from smart payment cards during one week in 2018, 2020, and 2021. The results show that during the week of maximum restriction, that is, during 2020, the distribution of trips by purpose varied considerably, with the proportion of trips to work increasing, recreational trips decreasing, and trips for health purposes remaining unchanged. In sociodemographic terms, in the higher-income communes, the decrease in the proportion of trips for work purposes was much greater than that in the communes with lower income. Finally, with the gradual return to in-person activities in 2021, the distribution of trip purposes returned to values similar to those before the pandemic, although with a lower total amount, which suggests that unless relevant measures are taken, the low use of public transportation could be permanent.
  • Publication
    Discovering the Spread Patterns of SARS-CoV-2 in Metropolitan Areas
    (2023) Herrera Marín, Mauricio René; Vergara Perucich, Francisco; Aguirre-Núñez, Carlos; Godoy-Faúndez, Alex
    The spread of COVID-19 has been extensively studied, but the intricate dynamics of its transmission in interdependent and segregated urban areas, constrained by mobility restrictions, have not been completely understood yet. The pandemic's dynamic-adaptive nature implies that virus spread is influenced by diverse factors operating disparately in urban areas with distinct roles. This study investigates the dynamic spread patterns of COVID-19 in the Santiago Metropolitan Area (SMA), Chile, leveraging explanatory variables related to urban mobility, socio-spatial characteristics, segregation, and sanitary measures. Using publicly available mobility data, we used two indices—the Internal Mobility Index (capturing individual trips within a city’s commune), and the External Mobility Index (indicating trips crossing commune borders). These indices were derived from geolocation data recorded by the cellular telephone antenna network of the Telefónica company by tracking successive antenna transitions during trips. The analysis encompasses a three-stage pandemic pattern, corresponding to periods before, during, and after an initial lockdown in the pandemic's first year. Elastic-Net-Penalty regression models, skillful in both feature selection and managing highly correlated predictors while maintaining the interpretability of the models, are used. These models employ a combination of L1 (ridge) and L2 (lasso) regularized log-likelihood optimization. The ridge penalty functions by contracting the coefficients of correlated predictors, pulling them closer to each other. In contrast, the lasso method tends to choose one predictor and exclude the others. The analysis with these models unveils influences of various explanatory variable subsets throughout the pandemic. Importantly, the study provides evidence justifying the suboptimal outcomes of the dynamic quarantine imposed by authorities. Mobility restrictions were implemented without considering the intricate contextual factors, thus impacting vulnerable areas of the city adversely.
  • Publication
    Crowding on public transport using smart card data during the COVID-19 pandemic : New methodology and case study in Chile
    (2023) Basso, Franco; Hernández, Hugo; Frez, Jonathan; Leiva, Víctor; Pezoa, Raúl; Varas, Mauricio
    Most crowding measures in public transportation are usually aggregated at a service level. This type of aggregation does not help to analyze microscopic behavior such as exposure risk to viruses. To bridge such a gap, our paper proposes four novel crowding measures that might be well suited to proxy virus exposure risk at public transport. In addition, we conduct a case study in Santiago, Chile, using smart card data of the buses system to compute the proposed measures for three different and relevant periods of the COVID-19 pandemic: before, during, and after Santiago’s lockdown. We find that the governmental policies diminished public transport crowding considerably for the lockdown phase. The average exposure time when social distancing is not possible passes from 6.39 min before lockdown to 0.03 min during the lockdown, while the average number of encountered persons passes from 43.33 to 5.89. We shed light on how the pandemic impacts differ across various population groups in society. Our findings suggest that poorer municipalities returned faster to crowding levels similar to those before the pandemic.
  • Publication
    Comparing Methods for the Regionalization of Intensity−Duration−Frequency (IDF) Curve Parameters in Sparsely-Gauged and Ungauged Areas of Central Chile
    (2023) Sangüesa, Claudia; Pizarro, Roberto; Ingram, Ben; Ibáñez, Alfredo; Rivera, Diego; García-Chevesich, Pablo; Pino, Juan; Pérez, Felipe; Balocchi, Francisco; Peña, Francisco
    Estimating intensity−duration−frequency (IDF) curves requires local historical information of precipitation intensity. When such information is unavailable, as in areas without rain gauges, it is necessary to consider other methods to estimate curve parameters. In this study, three methods were explored to estimate IDF curves in ungauged areas: Kriging (KG), Inverse Distance Weighting (IDW), and Storm Index (SI). To test the viability of these methods, historical data collected from 31 rain gauges distributed in central Chile, 35° S to 38° S, are used. As a result of the reduced number of rain gauges to evaluate the performance of each method, we used LOOCV (Leaving One Out Cross Validation). The results indicate that KG was limited due to the sparse distribution of rain gauges in central Chile. SI (a linear scaling method) showed the smallest prediction error in all of the ungauged locations, and outperformed both KG and IDW. However, the SI method does not provide estimates of uncertainty, as is possible with KG. The simplicity of SI renders it a viable method for extrapolating IDF curves to locations without data in the central zone of Chile
  • Publication
    A New Highly Portable Simulator (SECMA) Based on Virtual Reality for Teaching Essential Skills in Minimally Invasive Surgeries
    (2023) Gúzman Montoto, José Ignacio; Herrera Marín, Mauricio René; Rodríguez Beltrán, Camilo Ignacio
    This study presents a new minimal access surgery training system, SECMA, and its constructive validation to determine its usefulness for training basic laparoscopic skills. SECMA is an affordable, highly portable, mobile virtual reality training tool for laparoscopic techniques that integrates the Oculus Quest with a mechanical interface for surgeon simulation of forceps using the hand controllers of these devices. It allows the execution of structured activities (supported by virtual scenarios simulating operating rooms developed in Unity), performance evaluation, and real-time data capture. Two experiments were carried out: 1) coordination; and 2) capture and transport, with a total of 21 individuals divided into two groups: a novice group (inexperienced) of 10 participants and an expert group (>100 endoscopic procedures) of 11 participants. Total task time score, right-hand speed, path length, and other metrics from several consecutive runs on the simulator were compared between experts and novices. Data automatically recorded by SECMA during the experiments were analyzed using hypothesis tests, linear regressions, analysis of variance, principal component analysis, and machine learning-supervised classifiers. In the experiments, the experts scored significantly better than the novices in all the parameters used. The tasks evaluated discriminated between the skills of experienced and novice surgeons, giving the first indication of construct validity for SECMA.