951 research outputs found

    Desarrollo de un modelo de producción, a fin de optimizar el proceso de fabricación del rodillo triturador Wobbler en la empresa Fundición Central S.A.

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    RESUMEN La presente tesis se realizó enfocándose en la empresa Fundición Central S.A. que se dedica a la fabricación de repuestos fundidos de alta resistencia al impacto, altas temperaturas y corrosión. Asimismo la empresa nos concedió la información precisa para el sustento respectivo. Dando inicio a la tesis, se procedió a obtener información con el personal técnico del Área Mecánica para luego validar en el mismo lugar de trabajo. Detectando así que el área de mecánica no cuenta con un modelo de producción para la fabricación de rodillos triturador wobbler ya que en la actualidad hay carencia de este modelo de fabricación. Se han detectado varias procesos que generan el problema, se identificó que por cada rodillo en los trabajos de mecanizado toman un tiempo de 1080 minutos a un costo de 360 dólares, también se observó que el área se encuentra con una mala distribución de maquinarias, el área en desorden y sucio, se destina tiempo valioso en actividades que no suman valor a la producción final. Se propone un planteamiento de mejora integral, se asignara el uso de metodología y herramientas de ingeniería, la elección adecuada de las mismas nos servirá para darnos cuenta cual nos da mayor interés para así obtener una adecuada mejora, por último se estandarizara procedimientos productivos, se reducirá tiempos, distancias y costos significativos para aumentar la producción. Comenzando por el capítulo 1 se describió la organización y su entorno, es ahí donde se determinó la realidad problemática y luego se busca las mejoras correspondientes. En el capítulo 2 desarrollaremos el marco teórico donde asignaremos metodología y herramientas para plantear las mejoras. En el capítulo 3 se describe actualmente la producción de rodillos wobbler que carece de un modelo de fabricación y para empezar el desarrollo de nuestro modelo, realizaremos un estudio del área en su estado actual para luego tomar las acciones correspondientes como oportunidad de mejora que nos permitan obtener los objetivos propuestos. En el capítulo 4 se validaran los resultados y recomendaciones de mejoras, indicando a continuación que se ve necesario reducir 10 procedimientos de producción que hacen un 40.57% del costo de material, también se reducen los procedimientos de producción en un 16% a demás se redujeron tiempos de producción en un 12.2% todo esto se demuestra con la propuesta de desarrollo de un modelo de producción que servirá para identificar, reducir y estandarizar los procedimientos innecesarios, minimiza costos, genera ganancias para la empresa.ABSTRACT This thesis was conducted focusing on the company Fundición Central S.A. which is dedicated to the manufacture of cast parts with high resistance to impact, high temperatures and corrosion. Also the company gave us the precise information for the respective support. Starting the thesis, we proceeded to obtain information with the technical staff of the Mechanical Area and then validate in the same place of work. Detecting that the area of mechanics does not have a production model for the manufacture of wobbler crusher rollers since there is currently a lack of this manufacturing model. Several processes that generate the problem have been detected, it was identified that for each roll in the machining works take a time of 1080 minutes at a cost of 360 dollars, it was also observed that the area is with a poor distribution of machinery, the untidy and dirty area, valuable time is spent on activities that do not add value to the final production. An integral improvement approach is proposed, the use of methodology and engineering tools will be assigned, the appropriate choice of these will help us to realize which one gives us the most interest in order to obtain an adequate improvement, finally, standardize productive procedures, It will reduce time, distance and significant costs to increase production. Starting with Chapter 1 described the Organization and its environment, is where it was determined the problematic reality and then seeks to appropriate improvements. In Chapter 2 we will develop the theoretical framework where we will assign methodology and tools to make improvements. Chapter 3 describes currently roll wobbler that lacks a model of manufacturing and production to begin the development of our model; we will carry out a study of the area in its current state to then take appropriate actions such as opportunity for improvement that will allow us to obtain the objectives. Chapter 4 validate the results and recommendations for improvements, then indicating it is necessary to reduce 10 production processes that make a 40.57% of the cost of material, also reduce the procedures of production 16% other reduced production in a 12.2 times % all this is demonstrated with the proposal for development of a production model that will serve to identify, reduce and standardize the unnecessary procedures, minimizing costs, generates profits for the company

    Infestação de ninfas de cigarrinhas - das - raízes altera a quantidade de compostos fenólicos em cana - de - açucar

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    Com a intensificação da colheita mecanizada da cana-de-açúcar sem queima da palhada, a cigarrinha-das-raízes Mahanarva fimbriolata (Stal, 1854) tornou-se uma das principais pragas da cultura, favorecida pelas condições de umidade e baixa variação de temperatura do solo. Poucos trabalhos são dedicados ao estudo da resposta da planta ao ataque deste inseto, dificultando o conhecimento de cultivares resistentes. Os compostos fenólicos são muito estudados por sua ação anti-herbivoria. A presente pesquisa foi conduzida com o objetivo de verificar se o ataque de ninfas de M. fimbriolata induz alterações na quantidade de fenóis totais em cana-de-açúcar. O experimento foi instalado em casa de vegetação, com condições de temperatura e umidade controladas, com delineamento inteiramente casualizado em esquema fatorial 3 X 2 X 4 e três repetições. Ninfas de segundo ínstar de M. fimbriolata foram inoculadas no sistema radicular das plantas, nos níveis: controle, 2-4 e 4-8 ninfas por vaso (primeira-segunda infestação, respectivamente). Os vasos foram cobertos com tela de nylon para isolar o efeito dos adultos, que eram mortos nos monitoramentos diários. Folhas e raízes foram coletadas e congeladas em nitrogênio líquido até a realização das análises. Plantas atacadas por ninfas de M. fimbriolata apresentaram maiores teores de fenóis totais em raízes e folhas. A cultivar SP80-1816 apresentou-se mais responsiva ao ataque das ninfas em raízes. A cultivar SP86-42 apresentou maiores teores de fenóis em raízes e folhas de plantas controle, podendo ser um indicativo da não-preferência dos insetos por esta variedade. O teor de compostos fenólicos parece não ser um bom marcador para identificar genótipos de cana-de-açúcar resistentes a ninfas de M. fimbriolata.The increased rate of sugarcane harvest without previous burn has provided a very favorable environment to the froghopper Mahanarva fimbriolata (Stal, 1854), with high moisture and low temperature variation. Few works have studied the response of sugarcane to this pest, so little is known about resistant cultivars. Plant phenolics are widely studied compounds because of their known antiherbivore effect. This research aims to determine if the attack of M. fimbriolata nymphs stimulates the accumulation of total phenolics in sugarcane. The experiment was carried out in greenhouse and arranged in completely randomized design, in a 3 X 2 X 4 factorial with three replications. Second instar nymphs of M. fimbriolata were infested at the following rates: control, 2-4 and 4-8 nymphs per pot (first-second infestations, respectively). Pots were covered with nylon net and monitored daily to isolate the effect of leaf sucking adults. Leaf and root samples were collected and kept frozen in liquid nitrogen until analyses. Infested plants showed higher levels of phenolics in both root and leaf tissues. In roots, the cultivar SP80-1816 accumulated more phenolic compounds in response to the infestation of M. fimbriolata. On the other hand, higher levels were found in leaves and roots of control plants of SP86-42, which might be an indication of a non-preference mechanism. The increase of total phenolics in sugarcane infested with root-sucking froghopper nymphs does not seem to be useful to detect the resistance to this pest

    Effect of a high protein/low glycaemic index diet on insulin resistance in adolescents with overweight/obesity-APREVIEWrandomized clinical trial

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    Background Pubertal insulin resistance (IR) is associated with increased risk of type 2 diabetes mellitus development in adolescents with overweight/obesity. Objectives The PREVIEW study was a randomized parallel trial assessing the change in IR, analyzed by Homeostatic Model Assessment of IR (HOMA-IR), at 2 years after randomization to a high protein vs a moderate protein diet in adolescents with overweight/obesity. It was hypothesized that a high protein/low glycaemic index diet would be superior in reducing IR compared to a medium protein/medium GI diet, in insulin resistant adolescents with overweight or obesity. Methods Adolescents with overweight/obesity and IR from the Netherlands, United Kingdom and Spain were randomized into a moderate protein/moderate GI (15/55/30En% protein/carbohydrate/fat, GI >= 56) or high protein/low GI (25/45/30En% protein/carbohydrate/fat, GI < 50) diet. Anthropometric and cardiometabolic parameters, puberty, dietary intake and physical activity (PA) were measured and effects on HOMA-IR were analyzed. Results 126 adolescents were included in this study (13.6 +/- 2.2 years, BMI z-score 3.04 +/- 0.66, HOMA-IR 3.48 +/- 2.28, HP n = 68, MP n = 58). At 2 years, changes in protein intake were not significantly different between timepoints or intervention groups and no effects of the intervention on IR were observed. The retention rate was 39%, while no compliance to the diets was observed. Conclusions The PREVIEW study observed no effect of a high protein/low GI diet on IR in adolescents with overweight/obesity and IR because of lack of feasibility, due to insufficient retention and dietary compliance after 2 years.Peer reviewe

    Associations of changes in reported and estimated protein and energy intake with changes in insulin resistance, glycated hemoglobin, and BMI during the PREVIEW lifestyle intervention study

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    BackgroundObserved associations of high-protein diets with changes in insulin resistance are inconclusive. Objectives We aimed to assess associations of changes in both reported and estimated protein (PRep; PEst) and energy intake (EIRep; EIEst) with changes in HOMA-IR, glycated hemoglobin (HbA1c), and BMI (in kg/m2), in 1822 decreasing to 833 adults (week 156) with overweight and prediabetes, during the 3-y PREVIEW (PREVention of diabetes through lifestyle intervention and population studies In Europe and around the World) study on weight-loss maintenance. Eating behavior and measurement errors (MEs) of dietary intake were assessed. Thus, observational post hoc analyses were applied.MethodsAssociations of changes in EIEst, EIRep, PEst, and PRep with changes in HOMA-IR, HbA1c, and BMI were determined by linear mixed-model analysis in 2 arms [high-protein-low-glycemic-index (GI) diet and moderate-protein-moderate-GI diet] of the PREVIEW study. EIEst was derived from energy requirement: total energy expenditure = basal metabolic rate × physical activity level; PEst from urinary nitrogen, and urea. MEs were calculated as [(EIEst - EIRep)/EIEst] × 100% and [(PRep - PEst)/PEst] × 100%. Eating behavior was determined using the Three Factor Eating Questionnaire, examining cognitive dietary restraint, disinhibition, and hunger. ResultsIncreases in PEst and PRep and decreases in EIEst and EIRep were associated with decreases in BMI, but not independently with decreases in HOMA-IR. Increases in PEst and PRep were associated with decreases in HbA1c. PRep and EIRep showed larger changes and stronger associations than PEst and EIEst. Mean ± SD MEs of EIRep and PRep were 38% ± 9% and 14% ± 4%, respectively; ME changes in EIRep and En% PRep were positively associated with changes in BMI and cognitive dietary restraint and inversely with disinhibition and hunger. ConclusionsDuring weight-loss maintenance in adults with prediabetes, increase in protein intake and decrease in energy intake were not associated with decrease in HOMA-IR beyond associations with decrease in BMI. Increases in PEst and PRep were associated with decrease in HbA1c.This trial was registered at clinicaltrials.gov as NCT01777893

    Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

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    The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.publishedVersio

    Event reconstruction for KM3NeT/ORCA using convolutional neural networks

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    The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino detector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower- or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

    Event reconstruction for KM3NeT/ORCA using convolutional neural networks

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    The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino de tector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower-or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.
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