Evaluation of the changes in working limits in an automobile assembly line using simulation

The aim of the work presented in this paper consists of the development of a decision-making support system, based on discrete-event simulation models, of an automobile assembly line which was implemented within an Arena simulation environment and focused at a very specific class of production lines with a four closed-loop network configuration. This layout system reflects one of the most common configurations of automobile assembly and preassembly lines formed by conveyors. The sum of the number of pallets on the intermediate buffers, remains constant, except for the fourth closed-loop, which depends on the four-door car ratio (x) implemented between the door disassembly and assembly stations of the car body. Some governing equations of the four closed-loops are not compatible with the capacities of several intermediate buffers for certain values of variable x. This incompatibility shows how the assembly line cannot operate in practice for x0,97 in a stationary regime, due to the starvation phenomenon or the failure of supply to the machines on the production line. We have evaluated the impact of the pallet numbers circulating on the first closed-loop on the performance of the production line, translated into the number of cars produced/hour, in order to improve the availability of the entire manufacturing system for any value of x. Until the present date, these facts have not been presented in specialized literature. © 2012 American Institute of Physics

Evaluación de las condiciones de trabajo en fincas cafeteras del Departamento del Quindío (Colombia)

Farmers in the rural area of the department of Quindío (Colombia) base their economy on agricultural and livestock work. This activity is often an informal and temporary economy, with precarious working conditions that give rise to occupational accidents and/or diseases. The objective of this study is to identify the occupational risks to which farm workers are exposed in 82 farms located in 4 municipalities of the department of Quindío. The study is descriptive-observational and quantitative. The occupational risks of working conditions found in the research were: 100% of workers handle hazardous agrochemicals inadequately, 80% do not have occupational health and safety activities or emergency plans, 72% have a demand for physical activity outdoors due to long working hours, and 65% are exposed to biological agents due to mosquito bites and accidents, among others. This study showed that farmers are exposed to poorly controlled occupational risks and do not have comprehensive social security protection or occupational risk promotion and prevention activities to improve working conditions and therefore their life quality.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarObjectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement EconòmicPostprint (published version

Impact of targeted attack on the spontaneous activity in spatial and biologically-inspired neuronal networks

We study the structural and dynamical consequences of damage in spatial neuronal networks. Inspired by real in vitro networks, we construct directed networks embedded in a two-dimensional space and follow biological rules for designing the wiring of the system. As a result, synthetic cultures display strong metric correlations similar to those observed in real experiments. In its turn, neuronal dynamics is incorporated through the Izhikevich model adopting the parameters derived from observation in real cultures. We consider two scenarios for damage, targeted attacks on those neurons with the highest out-degree and random failures. By analyzing the evolution of both the giant connected component and the dynamical patterns of the neurons as nodes are removed, we observe that network activity halts for a removal of 50% of the nodes in targeted attacks, much lower than the 70% node removal required in the case of random failures. Notably, the decrease of neuronal activity is not gradual. Both damage scenarios portray "boosts" of activity just before full silencing that are not present in equivalent random (Erdös-Rényi) graphs. These boosts correspond to small, spatially compact subnetworks that are able to maintain high levels of activity. Since these subnetworks are absent in the equivalent random graphs, we hypothesize that metric correlations facilitate the existence of local circuits sufficiently integrated to maintain activity, shaping an intrinsic mechanism for resilience

Comparison of Voltage Dip Characterization under Grid-Code Requirements: Application to PV Power Plants

Abstract. The Results and examples regarding the collected disturbances are also included in the paper, as well as a comparison with current Grid-Code requirements for renewable energy resources connected to the grid under the presence of disturbances

Social Network Reciprocity as a Phase Transition in Evolutionary Cooperation

In Evolutionary Dynamics the understanding of cooperative phenomena in natural and social systems has been the subject of intense research during decades. We focus attention here on the so-called "Lattice Reciprocity" mechanisms that enhance evolutionary survival of the cooperative phenotype in the Prisoner's Dilemma game when the population of darwinian replicators interact through a fixed network of social contacts. Exact results on a "Dipole Model" are presented, along with a mean-field analysis as well as results from extensive numerical Monte Carlo simulations. The theoretical framework used is that of standard Statistical Mechanics of macroscopic systems, but with no energy considerations. We illustrate the power of this perspective on social modeling, by consistently interpreting the onset of lattice reciprocity as a thermodynamical phase transition that, moreover, cannot be captured by a purely mean-field approach.Comment: 10 pages. APS styl

Desarrollo de una instalación experimental minieólica como estrategia de enseñanza-aprendizaje. Póster

Se ha desarrollado una plataforma didáctica que consiste en una instalación experimental de energías renovables. La instalación está formada por una planta híbrida eólico-solar. Esta plataforma ha sido diseñada por medio de un proyecto en el que han colaborado la Universidad de Castilla-La Mancha y el Instituto de Educación Secundaria Cencibel de Villarrobledo. La plataforma tiene suficiente flexibilidad como para ser empleada en distintos niveles de formación. De hecho, el objetivo de la misma es mejorar la metodologías de enseñanza actuales tanto en el Máster de Energías Renovables y Eficiencia Energética, como en los Ciclos Formativos de Formación Profesional. Asimismo, la formación de profesionales en este tipo de tecnologías es una apuesta de futuro para la construcción de un sistema energético más sostenible.Campus Mare Nostrum, Universidad Politécnica de Cartagena, Universidad de Murcia, Región de Murci

Exposición de los trabajadores de curtiembres, obras de construcción y salones de belleza de Armenia a contaminación ambiental laboral. Caso de estudio

El objetivo de esta investigación fue evaluar las condiciones de trabajo y salud de los trabajadores, de tres sectores de la economía de Armenia, Colombia (curtiembres, obras de construcción y salones de belleza), expuestos a agentes químicos y físicos. Se realizó un estudio observacional descriptivo de las condiciones de trabajo y salud de los trabajadores en sus entornos laborales, visitando 10 empresas por sector. La evaluación de las condiciones de trabajo en las obras de construcción dio un resultado Alto (riesgo elevado), al igual que en las curtiembres. Los salones de belleza obtuvieron una evaluación Media (riesgo medio)

Thermal decomposition of the acetone cyclic diperoxide in 1-octanol solution

The thermal decomposition reaction of acetone cyclic diperoxide (ACDP) in 1-octanol (OCT) solution, at the temperatures and initial concentration ranges of 130° -166 ºC and (0.94-3.00) x 10-2 mol/L , respectively, follows a pseudo-first order kinetic law. Acetone is the main organic decomposition product observed. The activation parameters values of the initial reaction step (ΔH# = 25.8 ± 0.3 kcal/mol; ΔS# = -19.1 ± 0.6 cal/mol K; Ea = 26.6 ± 0.3 kcal/mol), support a reaction mechanism which includes a homolytic rupture of one peroxidic bond of the ACDP molecule with participation of the solvent and involving a biradical intermediate.La reacción de descomposición térmica del diperóxido de acetona cíclico (ACDP) en solución de 1-octanol (OCT), en los rangos de temperatura y concentraciones iniciales de 130° -166 ºC y (0.94-3.00) x 10-2 mol/L respectivamente, sigue una ley cinética de seudo primer orden. La acetona es el principal producto de descomposición observado. Loa valores de activación de la etapa inicial (ΔH# = 25.8 ± 0.3 kcal/mol; ΔS# = -19.1 ± 0.6 cal/mol K; Ea = 26.6 ± 0.3 kcal/mol) apoyan un mecanismo de reacción que incluye una ruptura homolítica de un enlace peroxídico en la molécula del ACDP con participación del solvente y que involucra un birradical intermediario.Laboratorio de Estudio de Compuestos OrgánicosInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada