A simulation method to estimate closing forces in car-sealing rubber elements

The door-closing process can reinforce the impression of a solid, rock-proof, car body or of a rather cheap, flimsy vehicle. As there are no real prototypes during rubber profile bidding-out stages, engineers need to carry out non-linear numerical simulations that involve complex phenomena as well as static and dynamic loads for several profile candidates. This paper presents a structured virtual design tool based on FEM, including constitutive laws and incompressibility constraints allowing to predict more realistically the final closing forces and even to estimate sealing overpressure as an additional guarantee of noise insulation. Comparisons with results of physical tests are performed.

AFBC of coal with tyre rubber. Influence of the co-combustion variables on the mineral matter of solid by-products and on Zn lixiviation

The study focuses on the generation and distribution of mineral species in fly and bottom ashes. These were formed during a fluidised co-combustion of a fossil fuel (coal) and a non-fossil fuel (tyre rubber) in a small fluidised bed combustor (7cm x 70cm). The pilot plant had continuous fuel feed using varying ratios of coal and rubber. The study also focuses on the lixiviation behaviour of metallic elements with the assessement of zinc recovering.

La Acacia Melanoxylon R. Br., Acacia Negra en Galicia. Estudio Forestal

Estudio lo mas completo posible sobre la acacia melanoxylon, acacia negra, en la regi��n gallega, en sus aspectos forestales industrial.

Study of the effect of four warm mix asphalt additives on bitumen modified with 15% crumb rubber

Due to a growing concern over global warming, the bituminous mixture industry is making a constant effort to diminish its emissions by reducing manufacturing and installation temperatures without compromising the mechanical properties of the bituminous mixtures. The use of mixtures with tyre rubber has demonstrated that these mixtures can be economical and ecological and that they improve the behaviour of the pavements. However, bituminous mixtures with a high rubber content present one major drawback: they require higher mixing and installation temperatures due to the elevated viscosity caused by the high rubber content and thus they produce larger amounts of greenhouse gas emissions than conventional bituminous mixtures. This article presents a study of the effect of four viscosity-reducing additives (Sasobit��, Asphaltan A��, Asphaltan B�� and Licomont BS 100��) on a bitumen modified with 15% rubber. The results of this study indicate that these additives successfully reduce viscosity, increase the softening temperature and reduce penetration. However, they do not have a clear effect on the test for elastic recovery and ductility at 25 ��C.

Influence of proportion and particle size gradation of rubber from end-of-life tires on mechanical, thermal and acoustic properties of plaster-rubber mortars

This work presents the main experimental results obtained from the study of plaster test pieces and boards with addition of various volumetric rubber fractions from mechanical grinding of end-of-life tires (ELTs), in three different particle size gradations. It includes a description of the materials employed, and their proportions. The physical and mechanical properties, as well as the thermal conductivity and acoustic insulation properties are analyzed. Experimental results obtained for specimens with addition of recycled rubber are compared with similar ones, carried out on specimens of plaster of identical features without any addition, evaluating the influence of the particle size and mixture proportions. An improvement in thermal and acoustic performance has been obtained as well as a reduction in density, and as a result, some constructive applications for paving and slabs in rehabilitation works are proposed.

Asphalt rubber mixtures with warm mix asphalt additives

En los ��ltimos a��os, debido a la creciente preocupaci��n por el calentamiento global y el cambio clim��tico, uno de los retos m��s importantes a los que se enfrenta nuestra sociedad es el uso eficiente y econ��mico de energ��a as�� como la necesidad correspondiente de reducir los gases de efecto invernadero (GEI). Las tecnolog��as de mezclas semicalientes se han convertido en un nuevo e importante tema de investigaci��n en el campo de los materiales para pavimentos ya que ofrece una soluci��n potencial para la reducci��n del consumo energ��tico y las emisiones de GEI durante la producci��n y puesta en obra de las mezclas bituminosas. Por otro lado, los pavimentos que contienen polvo de caucho procedente de neum��tico fuera de uso, al hacer uso productos de desecho, ahorran energ��a y recursos naturales. Estos pavimentos ofrecen una resistencia mejorada a la formaci��n de roderas, a la fatiga y a la fisuraci��n t��rmica, reducen los costes de mantenimiento y el ruido del tr��fico as�� como prolongan la vida ��til del pavimento. Sin embargo, estas mezclas presentan un importante inconveniente: la temperatura de fabricaci��n se debe aumentar en comparaci��n con las mezclas asf��lticas convencionales, ya que la incorporaci��n de caucho aumenta la viscosidad del ligante y, por lo tanto, se producen mayores cantidades de emisiones de GEI. En la presente Tesis, la tecnolog��a de mezclas semicalientes con aditivos org��nicos (Sasobit, Asphaltan A, Asphaltan B, Licomont) se incorpor�� a la de betunes de alta viscosidad modificados con caucho (15% y 20% de caucho) con la finalidad de dar una soluci��n a los inconvenientes de mezclas con caucho gracias a la utilizaci��n de aditivos reductores de la viscosidad. Para este fin, se estudi�� si ser��a posible obtener una producci��n m��s sostenible de mezclas con betunes de alto contenido en caucho sin afectar significativamente su nivel de rendimiento mec��nico. La metodolog��a aplicada para evaluar y comparar las caracter��sticas de las mezclas consisti�� en la realizaci��n de una serie de ensayos de laboratorio para betunes y mezclas con caucho y con aditivos de mezclas semicalientes y de un an��lisis del ciclo de vida h��brido de la producci��n de mezclas semicalientes teniendo en cuenta la papel del aditivo en la cadena de suministro con el fin de cuantificar con precisi��n los beneficios de esta tecnolog��a. Los resultados del estudio indicaron que la incorporaci��n de los aditivos permite reducir la viscosidad de los ligantes y, en consecuencia, las temperaturas de producci��n y de compactaci��n de las mezclas. Por otro lado, aunque la adici��n de caucho mejor�� significativamente el comportamiento mec��nico de los ligantes a baja temperatura reduciendo la susceptibilidad al fen��meno de fisuraci��n t��rmica, la adici��n de las ceras aument�� ligeramente la rigidez. Los resultados del estudio reol��gico mostraron que la adici��n de porcentajes crecientes de caucho mejoraban la resistencia del pavimento con respecto a la resistencia a la deformaci��n permanente a altas temperaturas y a la fisuraci��n t��rmica a bajas temperaturas. Adem��s, se observ�� que los aditivos mejoran la resistencia a roderas y la elasticidad del pavimento al aumentar el m��dulo complejo a altas temperaturas y al disminuir del ��ngulo de fase. Por otra parte, el estudio reol��gico confirm�� que los aditivos estudiados aumentan ligeramente la rigidez a bajas temperaturas. Los ensayos de fluencia llevados a cabo con el re��metro demostraron una vez m��s la mejora en la elasticidad y en la resistencia a la deformaci��n permanente dada por la adici��n de las ceras. El estudio de mezclas con caucho y aditivos de mezclas semicalientes llevado a cabo demostr�� que las temperaturas de producci��n/compactaci��n se pueden disminuir, que las mezclas no experimentar��an escurrimiento, que los aditivos no cambian significativamente la resistencia conservada y que cumplen la sensibilidad al agua exigida. Adem��s, los aditivos aumentaron el m��dulo de rigidez en algunos casos y mejoraron significativamente la resistencia a la deformaci��n permanente. Asimismo, a excepci��n de uno de los aditivos, las mezclas con ceras ten��an la misma o mayor resistencia a la fatiga en comparaci��n con la mezcla control. Los resultados del an��lisis de ciclo de vida h��brido mostraron que la tecnolog��a de mezclas semicalientes es capaz de ahorrar significativamente energ��a y reducir las emisiones de GEI, hasta un 18% y 20% respectivamente, en comparaci��n con las mezclas de control. Sin embargo, en algunos de los casos estudiados, debido a la presencia de la cera, la temperatura de fabricaci��n debe reducirse en un promedio de 8 ��C antes de que los beneficios de la reducci��n de emisiones y el consumo de combustible puedan ser obtenidos. Los principales sectores contribuyentes a los impactos ambientales generados en la fabricaci��n de mezclas semicalientes fueron el sector de los combustibles, el de la miner��a y el de la construcci��n. Due to growing concerns over global warming and climate change in recent years, one of the most important challenges facing our society is the efficient and economic use of energy, and with it, the corresponding need to reduce greenhouse gas (GHG) emissions. The Warm Mix Asphalt (WMA) technology has become an important new research topic in the field of pavement materials as it offers a potential solution for the reduction of energy consumption and GHG emissions during the production and placement of asphalt mixtures. On the other hand, pavements containing crumb-rubber modified (CRM) binders save energy and natural resources by making use of waste products. These pavements offer an improved resistance to rutting, fatigue and thermal cracking; reduce traffic noise and maintenance costs and prolong pavement life. These mixtures, however, present one major drawback: the manufacturing temperature is higher compared to conventional asphalt mixtures as the rubber lends greater viscosity to the binder and, therefore, larger amounts of GHG emissions are produced. In this dissertation the WMA technology with organic additives (Sasobit, Asphaltan A, Asphaltan B and Licomont) was applied to CRM binders (15% and 20% of rubber) in order to offer a solution to the drawbacks of asphalt rubber (AR) mixtures thanks to the use of fluidifying additives. For this purpose, this study sought to determine if a more sustainable production of AR mixtures could be obtained without significantly affecting their level of mechanical performance. The methodology applied in order to evaluate and compare the performance of the mixtures consisted of carrying out several laboratory tests for the CRM binders and AR mixtures with WMA additives (AR-WMA mixtures) and a hybrid input-output-based life cycle assessment (hLCA) of the production of WMA. The results of the study indicated that the incorporation of the organic additives were able to reduce the viscosity of the binders and, consequently, the production and compaction temperatures. On the other hand, although the addition of rubber significantly improved the mechanical behaviour of the binders at low temperatures reducing the susceptibility to thermal cracking phenomena, the addition of the waxes slightly increased the stiffness. Master curves showed that the addition of increasing percentages of rubber improved the resistance of the pavement regarding both resistance to permanent deformation at high temperatures and thermal cracking at low temperatures. In addition, the waxes improved the rutting resistance and the elasticity as they increased the complex modulus at high temperatures and decreased the phase angle. Moreover, master curves also attest that the WMA additives studied increase the stiffness at low temperatures. The creep tests carried out proved once again the improvement in the elasticity and in the resistance to permanent deformation given by the addition of the waxes. The AR-WMA mixtures studied have shown that the production/compaction temperatures can be decreased, that the mixtures would not experience binder drainage, that the additives did not significantly change the retained resistance and fulfilled the water sensitivity required. Furthermore, the additives increased the stiffness modulus in some cases and significantly improved the permanent deformation resistance. Except for one of the additives, the waxes had the same or higher fatigue resistance compared to the control mixture. The results of the hLCA demonstrated that the WMA technology is able to significantly save energy and reduce GHG emissions, up to 18% and 20%, respectively, compared to the control mixtures. However, in some of the case studies, due to the presence of wax, the manufacturing temperature at the asphalt plant must be reduced by an average of 8��C before the benefits of reduced emissions and fuel usage can be obtained. The results regarding the overall impacts generated using a detailed production layer decomposition indicated that fuel, mining and construction sectors are the main contributors to the environmental impacts of manufacturing WMA mixtures.

www.professor.com.br : Experi��ncias do uso da tecnologia na vida profissional e pessoal de professores

Esta pesquisa investiga as experi��ncias dos professores nas S��ries Iniciais do Ensino Fundamental no Estado de S��o Paulo, sobre o uso do computador como uma ferramenta de trabalho, procurando identificar as rela����es que est��o construindo com o uso das tecnologias tanto na organiza����o e no planejamento de suas aulas quanto na constru����o dos saberes pedag��gicos que podem fazer com o uso do computador. Identificam-se nesse trabalho o acesso e o dom��nio que os professores t��m no dia-a-dia em rela����o ao computador (incluindo o acesso �� internet) e as experi��ncias que est��o realizando com o auxilio do computador e da internet. Foi utilizado o conceito de familiariza����o para an��lise da rela����o do professor com o computador.Foram realizadas entrevistas e aplicados question��rios aos professores que atuam nos sistemas de ensino p��blico e privado, no Estado de S��o Paulo, primeiro n��vel do Ensino Fundamental (1�� a 4�� s��ries / 2�� ao 5�� ano ), e aos alunos do curso de Pedagogia. O trabalho evidenciou que existe uma rela����o de familiariza����o dos professores, e esse n��vel passa pelo interesse e pela experi��ncia individual antes de passar para o lado profissional do uso do computador e internet na sala de aula. N��o h�� evid��ncias de resist��ncia ao uso do computador, as atividades com alunos avan��am �� medida que o professor se desenvolve no uso da tecnologia.(AU)

www.professor.com.br : Experi��ncias do uso da tecnologia na vida profissional e pessoal de professores

Esta pesquisa investiga as experi��ncias dos professores nas S��ries Iniciais do Ensino Fundamental no Estado de S��o Paulo, sobre o uso do computador como uma ferramenta de trabalho, procurando identificar as rela����es que est��o construindo com o uso das tecnologias tanto na organiza����o e no planejamento de suas aulas quanto na constru����o dos saberes pedag��gicos que podem fazer com o uso do computador. Identificam-se nesse trabalho o acesso e o dom��nio que os professores t��m no dia-a-dia em rela����o ao computador (incluindo o acesso �� internet) e as experi��ncias que est��o realizando com o auxilio do computador e da internet. Foi utilizado o conceito de familiariza����o para an��lise da rela����o do professor com o computador.Foram realizadas entrevistas e aplicados question��rios aos professores que atuam nos sistemas de ensino p��blico e privado, no Estado de S��o Paulo, primeiro n��vel do Ensino Fundamental (1�� a 4�� s��ries / 2�� ao 5�� ano ), e aos alunos do curso de Pedagogia. O trabalho evidenciou que existe uma rela����o de familiariza����o dos professores, e esse n��vel passa pelo interesse e pela experi��ncia individual antes de passar para o lado profissional do uso do computador e internet na sala de aula. N��o h�� evid��ncias de resist��ncia ao uso do computador, as atividades com alunos avan��am �� medida que o professor se desenvolve no uso da tecnologia.(AU)