Browsing by Author "Bosch, Paul"
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Item A horizontal collaborative approach for planning the wine grape harvesting(2022) Basso, Franco; Varas, Mauricio; Bosch, Paul; Contreras, Juan Pablo; Pezoa, RaúlHorizontal collaboration is a strategy that has increasingly been used for improving supply chain operations. In this paper, we analyze the benefits of using a collaborative approach when optimally planning the wine grape harvesting process. Particularly, we assess how labor and machinery collaborative planning impacts harvesting costs. We model cooperation among wineries as a coalitional game with transferable costs for which the characteristic function vector is computed by solving a new formulation for planning the wine grape harvesting. In order to obtain stable coalitions, we devise an optimization problem that incorporates both rationality and efficiency conditions and uses the Gini index as a fairness criterion. Focusing on an illustrative case, we develop several computational experiments that show the positive effect of collaboration in the harvesting process. Moreover, our computational results reveal that the results depend strongly on the fairness criteria used. The Gini index, for example, favors the formation of smaller coalitions compared to other fairness criteria such as entropy.Item A New Genetic Algorithm Encoding for Coalition Structure Generation Problems(2020) Contreras, Juan Pablo; Bosch, Paul; Varas, Mauricio; Basso, FrancoGenetic algorithms have proved to be a useful improvement heuristic for tackling several combinatorial problems, including the coalition structure generation problem. In this case, the focus lies on selecting the best partition from a discrete set. A relevant issue when designing a Genetic algorithm for coalition structure generation problems is to choose a proper genetic encoding that enables an efficient computational implementation. In this paper, we present a novel hybrid encoding, and we compare its performance against several genetic encoding proposed in the literature. We show that even in difficult instances of the coalition structure generation problem, the proposed approach is a competitive alternative to obtaining good quality solutions in reasonable computing times. Furthermore, we also show that the encoding relevance increases as the number of players increases.Item Analysis of dengue fever outbreak by generalized fractional derivative(2020) Bosch, Paul; Gómez-Aguilar, J. F.; Rodríguez, José Manuel; Sigarreta, José MaríaIn this paper, we use the generalized fractional derivative in order to study the fractional differential equation associated with a fractional Gaussian model. Moreover, we propose new properties of generalized differential and integral operators. As a practical application, we estimate the order of the derivative of the fractional Gaussian models by solving an inverse problem involving real data on the dengue fever outbreak.Item Comment on “An algorithm for moment-matching scenario generation with application to financial portfolio optimization"(2018) Contreras, Juan Pablo; Bosch, Paul; Herrera, MauricioA paper by Ponomareva, Roman, and Date proposed a new algorithm to generate scenarios and their probability weights matching exactly the given mean, the covariance matrix, the average of the marginal skewness, and the average of the marginal kurtosis of each individual component of a random vector. In this short communication, this algorithm is questioned by demonstrating that it could lead to spurious scenarios with negative probabilities. A necessary and sufficient condition for the appropriate choice of algorithm parameters is derived to correct this issue.Item Dirichlet Type Problem for 2D Quaternionic Time-Harmonic Maxwell System in Fractal Domains(2020) Peña Pérez, Yudier; Abreu Blaya, Ricardo; Bosch, Paul; Bory Reyes, JuanWe investigate an electromagnetic Dirichlet type problem for the 2D quaternionic time-harmonic Maxwell system over a great generality of fractal closed type curves, which bound Jordan domains in . The study deals with a novel approach of -summability condition for the curves, which would be extremely irregular and deserve to be considered fractals. Our technique of proofs is based on the intimate relations between solutions of time-harmonic Maxwell system and those of the Dirac equation through some nonlinear equations, when both cases are reformulated in quaternionic forms.Item Estrategia de gestión energética: optimización del sistema de almacenamiento para un caso de estudio utilizando hidrógeno verde y baterias(Universidad del Desarrollo. Facultad de Ingeniería, 2022) Fernández Henríquez, Ignacio; Bosch, Paul; Reyes Bozo, LorenzoEste trabajo presenta una propuesta para optimizar un sistema de almacenamiento que utiliza hidrógeno verde de una manera no convencional en Chile. El objetivo de esta investigación es implementar una estrategia de gestión energética a través de un modelo matemático para la optimización de un sistema de almacenamiento de energía que utiliza hidrógeno verde y baterías, el cual, permite abastecer el consumo eléctrico de una demanda real para un caso de estudio en la ciudad de Calama. Para lograrlo se propone una aproximación cuantitativa, utilizando un modelo matemático que considera como datos de entrada condiciones climáticas y demanda energética, evaluado para cada estación dentro de un rango de una semana, codificado en AMPL y resuelto con CPLEX. Los datos muestran que, al implementar el modelo matemático, es posible abastecer la demanda eléctrica en su totalidad utilizando hidrógeno verde y baterías. En síntesis, es posible asegurar que la estrategia permite el uso correcto de los recursos, en base a la irradiación solar y la demanda, utilizando baterías e hidrógeno verde en diferentes proporciones según cada estación del año, demostrando una fuerte inclinación del uso de baterías y celda de combustible durante invierno y otoño.Item Feasibility and Cost Minimisation for a Lithium Extraction Problem(2019) Bosch, Paul; Contreras, J.P.; Saavedra-Rosas, J.In this paper we address the problem of allocating extraction pumps to wells, when exploiting lithium rich brines, as part of the production of lithium salts. The problem of choosing the location of extraction wells is defined using a transportation network structure. Based on the transportation network, the lithium rich brines are pumped out from each well and then mixed into evaporation pools. The quality of the blend will be based on the chemical concentrations of the different brines, originating from different wells. The objective of the problem is then to determine a pumping plan such that the final products have predefined concentrations, and the process is operated in the cheapest possible way. The problem is modelled as a combinatorial optimisation problem and a potential solution to it is sought using a genetic algorithm. The evaluation function of the genetic algorithm needs a method to determine feasible minimum cost flows for the proposed pumping alloca- tion, thus requiring the formulation of a blending model in a flow network for which a new iterative non-convex local optimisation algorithm is proposed. The model was implemented and tested to measure the algorithm’s efficiency.Item Generalized inequalities involving fractional operators of the Riemann-Liouville type(2021) Bosch, Paul; Carmenate, Héctor; Rodríguez, José Manuel; Sigarreta, José MaríaIn this paper, we present a general formulation of the well-known fractional drifts of Riemann-Liouville type. We state the main properties of these integral operators. Besides, we study Ostrowski, Szekely-Clark-Entringer and Hermite-Hadamard-Fej ´ er inequalities involving these general fractional operators.Item Inequalities on the Generalized ABC Index(2021) Bosch, Paul; Molina, Edil D.; Rodríguez, José Manuel; Sigarreta, José MaríaIn this work, we obtained new results relating the generalized atom-bond connectivity index with the general Randi´c index. Some of these inequalities for ABCα improved, when α = 1/2, known results on the ABC index. Moreover, in order to obtain our results, we proved a kind of converse Hölder inequality, which is interesting on its own.Item Jensen-type inequalities for m-convex functions(2022) Bosch, Paul; Quintana, Yamilet; Rodríguez, José M.; Sigarreta, José M.Inequalities play an important role in pure and applied mathematics. In particular, Jensen’s inequality, one of the most famous inequalities, plays the main role in the study of the existence and uniqueness of initial and boundary value problems for differential equations. In this work, we prove some new Jensen-type inequalities for m-convex functions and apply them to generalized Riemann-Liouvilletype integral operators. Furthermore, as a remarkable consequence, some new inequalities for convex functions are obtained.Item Mining EEG with SVM for Understanding Cognitive Underpinnings of Math Problem Solving Strategies(2018) Bosch, Paul; Herrera, Mauricio; López, Julio; Maldonado, SebastiánWe have developed a new methodology for examining and extracting patterns from brain electric activity by using data mining and machine learning techniques. Data was collected from experiments focused on the study of cognitive processes that might evoke different specific strategies in the resolution of math problems. A binary classification problem was constructed using correlations and phase synchronization between different electroencephalographic channels as characteristics and, as labels or classes, the math performances of individuals participating in specially designed experiments. The proposed methodology is based on using well-established procedures of feature selection, which were used to determine a suitable brain functional network size related to math problem solving strategies and also to discover the most relevant links in this network without including noisy connections or excluding significant connectionsItem Modeling the Spread of Tuberculosis in Semiclosed Communities(2013) Herrera, Mauricio; Bosch, Paul; Nájera, Manuel; Aguilera, XimenaWe address the problem of long-term dynamics of tuberculosis (TB) and latent tuberculosis (LTB) in semiclosed communities. These communities are congregate settings with the potential for sustained daily contact for weeks, months, and even years between their members. Basic examples of these communities are prisons, but certain urban/rural communities, some schools, among others could possibly fit well into this definition. These communities present a sort of ideal conditions for TB spread. In order to describe key relevant dynamics of the disease in these communities, we consider a five compartments SEIR model with five possible routes toward TB infection: primary infection after a contact with infected and infectious individuals (fast TB), endogenous reactivation after a period of latency (slow TB), relapse by natural causes after a cure, exogenous reinfection of latently infected, and exogenous reinfection of recovered individuals. We discuss the possible existence of multiple endemic equilibrium states and the role that the two types of exogenous reinfections in the long-term dynamics of the disease could playItem On Ostrowski Type Inequalities for Generalized Integral Operators(2022) Cruz, Martha Paola; Abreu-Blaya, Ricardo; Bosch, Paul; Rodríguez, José M.; Sigarreta, José M.It is well known that mathematical inequalities have played a very important role in solving both theoretical and practical problems. In this paper, we show some new results related to Ostrowski type inequalities for generalized integral operators.Item On the Generalized Laplace Transform(2021) Bosch, Paul; Carmenate García, Héctor José; Rodríguez, José Manuel; Sigarreta, José MaríaIn this paper we introduce a generalized Laplace transform in order to work with a very general fractional derivative, and we obtain the properties of this new transform. We also include the corresponding convolution and inverse formula. In particular, the definition of convolution for this generalized Laplace transform improves previous results. Additionally, we deal with the generalized harmonic oscillator equation, showing that this transform and its properties allow one to solve fractional differential equations.Item On the Inverse Degree Polynomial(2019) Bosch, Paul; Rodríguez, José Manuel; Rosario, Omar; Sigarreta, José MaríaUsing the symmetry property of the inverse degree index, in this paper, we obtain several mathematical relations of the inverse degree polynomial, and we show that some properties of graphs, such as the cardinality of the set of vertices and edges, or the cyclomatic number, can be deduced from their inverse degree polynomials.Item Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy(PLoS, 2017) Oses, Carolina; Olivares, Belen; Ezquer, Marcelo; Acosta, Cristian; Bosch, Paul; Donoso, Macarena; Leniz, Patricio; Ezquer, FernandoDiabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment.Item Propuesta metodológica para la determinación de etapas críticas en el diseño de un plan de aseguramiento y control de calidad en una campaña de perforación geológica(Universidad del Desarrollo. Facultad de Ingeniería, 2024) Triana Ramírez, Cora Yohana; Bosch, Paul; Valdés González, HéctorEste trabajo ofrece un análisis de las etapas cruciales que impactan los datos más relevantes producidos en los procesos de perforación comunes en las operaciones mineras del Norte de Chile. Dichos datos son proveídos a las áreas encargadas de construir el modelo geológico, el cual es la base para la valorización económica de un yacimiento minero. El objetivo de este trabajo es proponer una metodología para la definición de etapas críticas del proceso, aportando así a la garantía de la calidad de la información que ingresa al modelamiento y estimación de recursos de un yacimiento minero. Para lograrlo, se propone una aproximación mixta, cualitativamente basada en entrevistas semiestructuradas a 16 informantes claves para la comprensión de cómo y porqué se definen las etapas críticas, lo que además se complementó con una pauta cuantitativa para la evaluación de la criticidad de cada una de estas etapas. Posteriormente, se llevó a cabo un focus group para verificación y discusión de los hallazgos. De esta manera se determinan las etapas críticas, sobre los cuales se deben diseñar e implementar medidas efectivas de control. Los datos muestran que, al evaluar las 17 etapas preestablecidas, los siguientes se posicionan como las más críticas: perforación, geología, muestreo, análisis químico, preparación mecánica y almacenamiento e inventario de muestras; soportadas por un proceso de aseguramiento y control de calidad entendido como transversal a lo largo de la cadena de valor. Se evidencia la necesidad de sumar las siguientes 4 etapas que no se habían considerado en un principio: planificación y etapa de licitación y compromisos contractuales; base de datos; modelamiento geológico; estimación de recursos. Adicionalmente, se revela la necesidad de invertir recursos y esfuerzos en tecnología, infraestructura y en el involucramiento y capacitación del personal de todos los niveles; para el fortalecimiento de la garantía de los entregables en los procesos, y que estos cumplan a nivel auditable. En síntesis, la metodología propuesta, permite identificar las etapas más críticas y proponer de qué manera se logra que la información y las muestras generadas de la campaña de sondaje, sean auditables y aporten al cumplimiento de los estándares de las normas internacionales.