Modélisation du pressage à chaud des panneaux de fibres de bois (MDF) par la méthode des éléments finis

Cette étude porte sur le développement d’un modèle mathématique-physique permettant de modéliser le pressage à chaud des panneaux de fibres de bois (MDF) pour les procédés en lot et en continu. Le système final est composé de trois équations différentielles : une pour la conservation de gaz, une pour la conservation de la vapeur d’eau et une pour la conservation d’énergie. On a introduit un terme de diffusion de la vapeur d’eau qui n’était pas considéré auparavant. Les variables d’état prédites sont la température, la pression gazeuse et la teneur en humidité. Le système d’équations a été résolu par la méthode des éléments finis en employant le logiciel MEF++ développé au GIREF à l’Université Laval. Les conditions aux limites utilisées durant la simulation sont du type Neumann non linéaire ou du type Dirichlet selon le type de pressage simulé. Afin de valider les résultats numériques en 2-D et 3-D donnés par ce modèle, on les a comparés avec les données obtenues d’un procédé en lot au laboratoire et en continu dans une industrie. À cet effet, des panneaux MDF d’épinette noire (Picea mariana (Mill.) BPS) ont été fabriqués et des mesures de température ont été prises à l’aide des thermocouples à la surface et au centre de l’ébauche. La pression gazeuse a aussi été déterminée lors du pressage à chaud avec une sonde de pression introduite à l’intérieur de l’ébauche. De plus, pour évaluer la teneur en humidité, sept modèles de sorption ont été extrapolés et comparés aux valeurs expérimentales provenant de la littérature. Le modèle de Malmquist donne la meilleure correspondance pour les humidités relatives considérées et a donc été utilisé. Les résultats numériques indiquent que la température, la teneur en humidité et la pression gazeuse prédites sont en accord avec les résultats expérimentaux pour les deux types de pressage considérés sans utiliser un facteur d’ajustement. On a conclu que le modèle mathématique-physique et la méthode des éléments finis ont un grand potentiel pour résoudre ce type de problème et aider ainsi à maîtriser la qualité des produits et les pertes lors de la fabrication. Il est fortement recommandé d’approfondir la recherche sur les valeurs des paramètres physiques impliqués dans ce procédé.This study describes a mathematical-physical model to predict temperature, gas pressure and moisture content during MDF hot pressing in batch and continuous processes. The final system is composed of three differential equations: gas conservation, water vapor conservation and energy conservation. This model introduced the moisture diffusion term which was not considered in the basis model. The system of equations was solved by the finite element method using the MEF++ software developed by the GIREF at Laval University. The boundary conditions used during simulation are of the Neumann or Dirichlet type depending on the process considered. In order to validate the numerical results in 2-D and 3-D, we compared them with experimental data obtained from the batch process in the pressing laboratory and from the continuous process in an industry. For this purpose, MDF panels of black spruce (Picea mariana (Mill.) BPS) were manufactured and temperature measurements made using thermocouples on the surface and the center of the mat. The gas pressure was also measured using a pressure probe located inside the mat. Moreover, in order to evaluate moisture content, seven sorption models were extrapolated and compared with experimental values from the literature. The Malmquist model gives the best correspondence for the relative humidities considered and was therefore used. The numerical results indicate that the predicted temperature, moisture content and gas pressure are in agreement with experimental results for the two processes considered without using an adjustment factor. We concluded that the mathematical-physical model and the finite element method have a great potential to solve this type of problem to control the quality of panels and the losses during manufacturing. It is strongly recommended to look further into research on the values of the physical parameters involved in this process

Paisagens, retratos e quadros: o Planalto Catarinense em Bulha D'Arroio e Amigo Velho

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Literatura.A presente dissertação configura, sob o viés da descrição e do descritivo, a leitura de fragmentos textuais selecionados dos livros de contos Bulha d´Arroio, de Tito Carvalho, publicado em 1936, e Amigo Velho, de Guido Wilmar Sassi, publicado em 1957. Objetiva-se identificar nas descrições o paisagismo geográfico, o universo humano e cultural capazes de representar o cotidiano da terra e da gente do Planalto de Santa Catarina em dois momentos históricos, econômicos e sociais diferenciados. Pretende-se, em primeiro lugar, verificar de que maneira a topografia, dominada pelo elemento "terra", está representada nos textos de ambos os escritores; em segundo, constatar a forma pela qual o descritivo e a descrição desenham as características físicas e psicológicas das personagens que integram o universo humano dos textos ficcionais selecionados; na seqüência, comprovar de que modo são usados os recursos da técnica descritiva nos quadros de usos e costumes mais significativos da cultura da região e, por último, tecer questionamentos e reflexões em torno das confluências e divergências entre os fragmentos descritivos presentes nos textos ficcionais de ambos os escritores

Diseño de una propuesta de un plan de mejoras para Quimicalzen Cía. Ltda. de la ciudad de Cuenca

La gestión de calidad permite identificar desviaciones presentes en las organizaciones, así como mantener una estructura ordenada en los procesos mediante la aplicación de herramientas y estandarización de los mismos, con el objetivo de lograr que esta perdure en el tiempo y conseguir una mejora continua. Actualmente las empresas afrontan situaciones de competencia con relación con los productos o servicios ofertados. Al no presentar una adecuada organización, planificación, no satisfacen las necesidades de los clientes y no cuentan con una meta establecida de acuerdo a la actividad económica correspondiente, los resultados pueden llegar a ser ineficientes y provocar pérdidas (Torres, 2021). QUIMICALZEN CÍA. LTDA., empresa especialista en tratamiento de agua presenta la necesidad de mejorar la estructura organizacional y contar con una planificación estratégica, por ello el presente trabajo tuvo como objeto diseñar una propuesta de un plan de mejoras. El presente estudio inició con el levantamiento de información para conocer la situación actual de la empresa mediante: matriz PESTEL, de factores internos y externos, matriz FODA y la herramienta adaptada del Test de Gestión Empresarial. Adicionalmente se aplicó encuestas a 20 clientes, para determinar con sustento aquellos problemas que presenta la empresa y a partir de ello realizar acciones pertinentes. El diseño del plan de mejoras constó de 13 acciones relacionadas con planificación estratégica, gestión de procesos, organización empresarial e implementación de indicadores para conocer el desarrollo de cada proceso existente. Finalmente, con la implementación del plan de mejoras la empresa presentó un porcentaje de crecimiento de 18,4% con respecto a la valoración del diagnóstico inicial.Quality management allows to identification deviations presented in organizations. Also, it helps to maintain an orderly structure in processes through the application of tools and standardization of documents, with the aim of ensuring that it lasts over time and achievecontinuous improvement. Companies currently face situations of competition in relation to the products or servicesoffered. By not presenting adequate organization, plaand nning, they do not satisfy the needs of the clients and they do not have an established goal according to the corresponding economic activity, the results can become inefficient and cause losses. QUIMICALZEN CÍA. LTDA., a company specializing in water treatment, presents the need to improve the organizational structure and have strategic planning. For this reason, the present work had the objective of designing a proposal for an improvement plan. The present study began with the collection of information to know the current situationof the company through: PESTEL matrix, internal and external factors, SWOT matrix and the adapted tool of the Business Management Test. Additionally, surveys were applied to 20 clients, to determine with support those problems that the company presentsand from there, carry out pertinent actions. The design of the improvement plan consisted of 13 actions related to strategic planning, process management, business organization and implementation of indicators to learn about the development of each existing process. Finally, with the implementation of the improvement plan, the company presented a growth percentage of 18.4% with respect to the assessment of the initial diagnosis.Ingeniero QuímicoCuenc

Evaluation of wood sorption models for high temperatures

Seven wood sorption models available in the literature were parameterized for prediction of equilibrium moisture content for temperatures up to 220ºC. The criterion used to evaluate the models is the uncorrected sum of squares of differences between the predicted equilibrium moisture content and experimental values published in literature for temperatures between 0ºC and 160ºC. The results show that the Malmquist model gave the best overall fit to experimental data for the relative humidities considered (40%, 52%, 65%, 75% and 85%). However, the García model performs better for temperatures between 110ºC and 155ºC at a relative humidity of 85%. Therefore, the choice of the sorption model depends on the specific hygrothermal conditions required by the user

Meu bairro na TV: um simulacro de comunicação comunitária na mídia convencional

An increasing number of television news programs are appropriating category “community communication” to define their productions. From 2009 to 2011, My Neighborhood on TV was on air, on TV Globo affiliate in Ceará, TV Verdes Mares, a clear example of this kind of appropriation from the CETV newscast. By highlighting various neighborhoods of Fortaleza, the project tried to incorporate features of communitarian communication in its line of approach, from a closer relationship with the audience and from an attendance policy solving everyday problems through mediation between people and government. This article examines whether this “”communitarianism” is in fact present on the CETV and seeks to understand the reasons and the political and social consequences of this mediation and these changes in CETV’s line of approach towards society.Keywords: community communication, mediation, power.É crescente o número de telejornais e quadros televisivos que se apropriam da categoria “comunicação comunitária” para definir suas produções. De 2009 a 2011, esteve no ar, na afiliada da TV Globo no Ceará, TV Verdes Mares, um exemplo claro desse tipo de apropriação: o quadro Meu Bairro na TV, do jornal CETV (1ª Edição). Ao dar destaque aos diversos bairros de Fortaleza, o projeto tentou incorporar características da comunicação comunitária em sua linha de abordagem, a partir de maior aproximação com seu público e uma política de atendimento e solução dos problemas cotidianos através da mediação entre povo e poder público. Este artigo analisa se esse “comunitarismo” está, de fato, presente no jornal e busca compreender motivos e consequências políticas e sociais dessa mediação e da mudança na linha de abordagem do CETV para a sociedade.Palavras-chave: comunicação comunitária, mediação, poder

Artificial Neural Networks in the prediction of insolvency. A paradigm shift to traditional business practices recipes

(Received: 2014/05/14 - Accepted: 2014/06/27)In this paper a review and analysis of the major theories and models that address the prediction of corporate bankruptcy and insolvency is made. Neural networks are a tool of most recent appearance, although in recent years have received considerable attention from the academic and professional world, and have started to be implemented in different models testing organizations insolvency based on neural computation. The purpose of this paper is to yield evidence of the usefulness of Artificial Neural Networks in the problem of bankruptcy prediction insolence or so compare its predictive ability with the methods commonly used in that context. The findings suggest that high predictive capabilities can be achieved  using artificial neural networks, with qualitative and quantitative variables

A cidade (in)segura e o impacto na produção da subjetividade de moradores da zona norte do Rio de Janeiro: um estudo exploratório

A literatura vigente tem apontado a violência como um problema de saúde pública, afetando a vida dos cidadãos, marcando-os com sentimentos de insegurança, medo e vulnerabilidade. O objetivo deste estudo é investigar que repercussões o fenômeno da insegurança tem gerado na produção de subjetividades, e como este sentimento pode influenciar o cotidiano dos indivíduos. Para obtenção dos dados foi utilizado um roteiro de entrevista semiestruturado, com 24 pessoas entrevistadas, de ambos os sexos, residentes da zona norte da cidade do Rio de Janeiro. A partir da análise do conteúdo das respostas colhidas, constatou-se que existe uma percepção distinta entre homens e mulheres a respeito da segurança/insegurança, mudanças nos hábitos cotidianos devido ao sentimento de insegurança, e criação de estratégias para lidar com esta problemática. Concluiu-se que embora cada um tenha uma percepção de sua realidade e do ambiente que os cerca, todos são afetados pelo fenômeno da violência

ENSINO DE GEOGRAFIA E EDUCAÇÃO AMBIENTAL MEDIADO PELO O USO DE TEXTUALIDADES IMAGÉTICAS (ORBITAIS) EXTRAÍDAS DO GOOGLE EARTH

Neste artigo são analisadas a relevância e potencialidades da sequência didática (SD) com foco específico na utilização de textualidades imagéticas do Google Earth e temática Educação Ambiental adotada em uma escola pública de Campo Grande (MS). O planejamento, construção e aplicação da SD tem caráter qualitativo, com delineamento empírico experimental. As imagens selecionadas mostram o lixão da cidade e a ocupação progressiva das áreas habitadas. Por meio delas, buscou-se identificar a aprendizagem com mudança conceitual e a superação de situações-limite dos estudantes no enfrentamento de problemas socioambientais encontrados em seu cotidiano. Dentre os resultados, foi possível constatar que a SD contribuiu não só para a construção e profusão dos conceitos geográficos, mas também se revelou como potencial ferramenta didático-pedagógica na Educação Ambiental

An exploration of grip force regulation with a low-impedance myoelectric prosthesis featuring referred haptic feedback

Abstract Background Haptic display technologies are well suited to relay proprioceptive, force, and contact cues from a prosthetic terminal device back to the residual limb and thereby reduce reliance on visual feedback. The ease with which an amputee interprets these haptic cues, however, likely depends on whether their dynamic signal behavior corresponds to expected behaviors—behaviors consonant with a natural limb coupled to the environment. A highly geared motor in a terminal device along with the associated high back-drive impedance influences dynamic interactions with the environment, creating effects not encountered with a natural limb. Here we explore grasp and lift performance with a backdrivable (low backdrive impedance) terminal device placed under proportional myoelectric position control that features referred haptic feedback. Methods We fabricated a back-drivable terminal device that could be used by amputees and non-amputees alike and drove aperture (or grip force, when a stiff object was in its grasp) in proportion to a myoelectric signal drawn from a single muscle site in the forearm. In randomly ordered trials, we assessed the performance of N=10 participants (7 non-amputee, 3 amputee) attempting to grasp and lift an object using the terminal device under three feedback conditions (no feedback, vibrotactile feedback, and joint torque feedback), and two object weights that were indiscernible by vision. Results Both non-amputee and amputee participants scaled their grip force according to the object weight. Our results showed only minor differences in grip force, grip/load force coordination, and slip as a function of sensory feedback condition, though the grip force at the point of lift-off for the heavier object was significantly greater for amputee participants in the presence of joint torque feedback. An examination of grip/load force phase plots revealed that our amputee participants used larger safety margins and demonstrated less coordination than our non-amputee participants. Conclusions Our results suggest that a backdrivable terminal device may hold advantages over non-backdrivable devices by allowing grip/load force coordination consistent with behaviors observed in the natural limb. Likewise, the inconclusive effect of referred haptic feedback on grasp and lift performance suggests the need for additional testing that includes adequate training for participants.http://deepblue.lib.umich.edu/bitstream/2027.42/116041/1/12984_2015_Article_98.pd