Artículos en Revistas
Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/538
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Item Impact between spherical rigid bodies including frictional effects(International Journal of Numerical Method and Engineering, 2024-10-30) Sánchez, Eliana; Cosimo, Alejandro; Brüls, Olivier; Cardona, Alberto; Cavalieri, Federico J.This work presents a new contact element which allows to simulate the impact between spherical bodies assuming instantaneous local impact events by the classical Newton impact law and a rigid behaviour of the bodies. The geometrical properties of the spheres are described by a rigid body formulation with translational and rotational degrees of freedom. In addition, an extension of the non-smooth generalized α time integration scheme applied to multi-impact collisions including Coulomb’s friction is given. Six numerical examples are presented to evaluate the robustness and the performance of the proposed methodology.Item Non-smooth numerical solution for Coulomb friction and sliding, rolling and spinning resistance applied to flexible multibody system dynamics(Multibody System Dynamics, 2023-06) Sánchez, Eliana; Cosimo, Alejandro; Brüls, Olivier; Cardona, Alberto; Cavalieri, Federico J.This paper presents the general motion of a sphere in contact with a rigid planar rigid surface under rolling, sliding and spinning friction in the context of non-smooth contact dynamics. The equation of motion are solved by the non smooth generalized α implicit time integration scheme where the constrains at position and at velocity level are satisfied exactly without requiring to define any penalty parameter. The geometrical properties of the spheres are described by a rigid body formulation with translational and rotational degrees of freedom. The robustness and the performance of the proposed methodology is demonstrated by different examples including both flexible and/or rigid elements.Item A disjunctive model to analyze and redefne the logistic of replenishing goods of retailing stores(Optimization and Engineering, 2022-02-09) Flores, Julio Rolando; Cúnico, Maria Laura; Vecchietti, Aldo RodomiroThis paper analyzes the distribution logistics for a retail business that has hundreds of stores located long distances from their warehouses. Given narrow revenue margins, retail companies must optimize the cost of the merchandise delivery to its stores. In general, the structure of the distribution consists of warehouses that concentrate goods which are then delivered to the stores according to a replenishment policy that contemplates its characteristics and location. The cost of the distribution logistics is signifcant and deserves special consideration. This paper presents a disjunctive multi period model to redesign the logistic infrastructure of delivering goods from warehouses to stores located in a wide geographical region. In the model, a warehouse can be installed, closed, expanded or replaced by a cross-docking terminal. The objective function is to minimize the cost of the whole distribution operation. A case study is presented to show the model capabilities.Item Metamodel-based formalization of DEVS atomic models(Simulation, 2021-09-14) Blas, María Julia; Gonnet, SilvioThe Discrete-Event System Specification (DEVS) formalism is a modeling formalism based on systems theory that provides a general methodology for hierarchical construction of reusable models in a modular way. When concrete DEVS models are developed using programming languages, it is difficult to ensure they conform to their formal model. Hence, building an implementation of formal models in a way that ensures DEVS formalism correctness is not easy. In this paper, we improve the interplay of abstraction (i.e., formal specification) and concreteness (i.e., programming code implementation) in advancing the theory and practice of DEVS using a specific-designed metamodel. The main contribution is a novel conceptualization of classic DEVS with ports founded on existing approaches but, that also includes new improved elements related to the definition of atomic models. That is, our metamodel includes all the concepts and relationships needed to define the formal specification of DEVS atomic models. This allows us to define instances of our conceptualization that comply with the DEVS formal specification. To instantiate our metamodel, we propose a computer-aided environment that has been developed using the Eclipse Modeling Project. As an example, we show how our metamodel can be used to define the classic “switch” model. As a conclusion, we discuss how the final metamodel can be used to support interoperability with DEVS simulation tools.Item The role of ontologies in Smart Contracts : a systematic literature review(Journal of Industrial Information Integration, 2024-07) Alvarado Domínguez, Johnny; Gonnet, Silvio; Vegetti, MarcelaThe aim of this systematic literature review is to provide a comprehensive understanding of how ontologies address current Smart Contract challenges, identify application scenarios, and present tools and technologies associated with their use. This systematic literature review (SLR), following Kitchenham's methodology, analyses peerreviewed articles from 2015 to August 2022 from databases such as Scopus, IEEE, Science Direct, Springer Link and ACM. Of the 501 publications identified, 21 are selected for in-depth review based on inclusion, exclusion and quality assessment criteria. The results of this SLR show that ontologies provide solutions to the challenges faced by Smart Contracts mainly at the creation stage. They allow the terms of the contract and the roles of the parties to be defined. Ontologies also enable the development of Smart Contract templates. This facilitates their use by people without technical programming expertise. Despite these potential solutions to the challenges that Smart Contracts face throughout their lifecycle, they lack verification. This increases the vulnerabilities to which Smart Contracts are exposed. Developing validation and verification tools could facilitate using ontologies to create Smart Contracts for different real-world cases.Item Enriching UML statecharts through a metamodel : a model-driven approach for the graphical definition of DEVS atomic models(IEEE Latin America Transactions, 2023-01-11) Dalmasso, Fidel; Blas , María Julia; Gonnet, SilvioThe Discrete Event System Specification (DEVS) formalism provides a set of mathematical elements for modeling time-varying systems. However, when DEVS models are implemented in an executable representation (i.e., using a generalpurpose programming language), some deviation from the formalism is unavoidable. One way to bridge the gap between modeling and simulation theory and practice is to define new artifacts that support both views during the specification. When the specification is supported with a graphical representation, the formalization task is less complex and can be performed by nonexpert modelers. For DEVS atomic models, most common graphical representation is through UML statecharts. In this paper, we present a theoretical and practical metamodel for the definition of atomic models structured following the Classic DEVS with Ports formalization. Such a metamodel is the core of a model-driven approach used to develop a modeling software tool that employs enriched UML statecharts for the graphical representation of the DEVS behavior. In here, the traditional UML statechart representation is enriched with a set of new components with the aim to provide a broad definition of DEVS atomic models. The final software tool is deployed as a plugin for Eclipse Platform.Item Ontología para la representación de entidades con comportamientos basados en eventos(SADIO Electronic Journal of Informatics and Operations Research (EJS), 2022) Blas, María Julia; Gonnet, Silvio; Becker, Pablo; Olsina, LuisEl modelado de comportamientos dinámicos usando eventos como disparadores del cambio de estado de entidades es un área de interés en Modelado y Simulación (M&S). En este trabajo se presentan los términos, propiedades, relaciones y axiomas de ParticularEventCO (PEventCO) como un modelo semántico basado en la noción de eventos causados por el comportamiento de entidades. Esta ontología se encuentra situada en el nivel “Core” de la arquitectura FCDOntoArch, donde la ontología ThingFO define el nivel fundacional. El principal objetivo es lograr una representación del comportamiento de entidades dinámicas siguiendo un enfoque basado en eventos como complemento de las ontologías ya existentes en FCD-OntoArch. Luego, se detalla la forma en la cual los principales elementos del nivel fundacional han sido redefinidos en PEventCO. Además, se incluye la especificación formal del modelo haciendo uso de ConceptBase, junto con la instanciación de una prueba de concepto tomada del área de M&S.Item Estimation of quality variables in a continuous train of reactors using recurrent neural networks-based soft sensors(Chemometrics and Intelligent Laboratory Systems, 2024) Perdomo, Mariano Miguel; Clementi, Luis Alberto; Vega, Jorge RubénThe first stage in the industrial production of Styrene-Butadiene Rubber (SBR) typically consists in obtaining a latex from a train of continuous stirred tank reactors. Accurate real-time estimation of some key process variables is of paramount importance to ensure the production of high-quality rubber. Monitoring the mass conversion of monomers in the last reactor of the train is particularly important. To this effect, various soft sensors (SS) have been proposed, however they have not addressed the underlying complex dynamic relationships existing among the process variables. In this work, a SS based on recurrent neural networks (RNN) is developed to estimate the mass conversion in the last reactor of the train. The main challenge is to obtain an adequate estimate of the conversion both in its usual steady-state operation and during its frequent transient operating phases. Three architectures of RNN: Elman, GRU (Gated Recurrent Unit), and LSTM (Long Short-Term Memory) are compared to critically evaluate their performances. Moreover, a comprehensive analysis is conducted to assess the ability of these models to represent different operational modes of the train. The results reveal that the GRU network exhibits the best performance for estimating the mass conversion of monomers. Then, the performance of the proposed model is compared with a previously-developed SS, which was based on a linear estimation model with a Bayesian bias adaptation mechanism and the use of Control Charts for decision-making. The model proposed here proved to be more efficient for estimating the mass conversion of monomers, particularly during transient operating phases. Finally, to evaluate the methodology utilized for designing the SS, the same RNN architectures were trained to online estimate another quality variable: the mass fraction of Styrene bound to the copolymer. The obtained results were also acceptableItem An adaptive soft sensor for on-line monitoring the mass conversion in the emulsion copolymerization of the continuous SBR process(Macromolecular Reaction Engineering, 2023) Sanseverinatti, Carlos Ignacio; Perdomo, Mariano Miguel; Clementi, Luis Alberto; Vega, Jorge RubénSoft sensors (SS) are of importance in monitoring polymerization processes because numerous production and quality variables cannot be measured online. Adaptive SSs are of interest to maintain accurate estimations under disturbances and changes in operating points. This study proposes an adaptive SS to online estimate the mass conversion in the emulsion copolymerization required for the production of Styrene-Butadiene rubber (SBR). The SS includes a bias term calculated from sporadic laboratory measurements. Typically, the bias is updated every time a new laboratory report becomes available, but this strategy leads to unnecessarily frequent bias updates. The SS includes a statistic-based tool to avoid unnecessary bias updates and reduce the variability of the bias with respect to classical approaches. A control chart (CC) for individual determinations combined with an algorithmic Cusum is used to monitor the statistical stability of the average prediction error. The adaptive SS enables a bias update only when a loss of said statistical stability is detected. Several bias update methods are tested on a simulated industrial train of reactors for the latex production in the SBR process. The best results are obtained by combining the proposed CC-based approach with a previously developed Bayesian bias update strategy.Item Propuesta metodológica para evaluar distintos niveles de aprendizajes de un contenido específico de Física : un estudio de caso(Revista de Enseñanza de la Física, 2024) Enrique, ClaudioSe presenta una propuesta didáctica para evaluar distintos niveles de aprendizaje sobre un contenido específico de Física -el período de oscilación de un péndulo simple-, a partir de las expresiones escritas en un examen. La propuesta consistió en indagar los desempeños logrados por estudiantes de primer año de tres ingenierías y evaluar si sus desempeños fueron resultados de la disponibilidad de competencias cognitivas y metacognitivas propias de un sujeto experto o competente; si han sido significativos por haberlos retenido en su estructura cognitiva y transferirlos correctamente en dos preguntas sobre un mismo contenido; y si resultaron ser exitosos al aprobar dicho examen parcial. A través de la categorización correspondiente a estos tres enfoques y seguido por un análisis estadístico descriptivo e inferencial mediante tablas de contingencia y la prueba Chi–cuadrado de Pearson, los distintos resultados permitieron evaluar, desde otra perspectiva, distintos niveles de aprendizajes sobre el período de oscilación de un péndulo simple. Estos primeros resultados fueron muy prometedores al detectar y diferenciar cómo los aprendices respondieron las consignas en función de los distintos niveles de aprendizaje logrados en Física I para ingenierías.