Studies on Rubber-to-Nylon Tire Cord Bonding

ABSTRACT: Nylon tire cord (1680/2) was dipped in different adhesives based on resorcinol formaldehyde resin and latex (RFL) and was bonded to natural rubber-based compounds. The resin-rubber ratio in the RFL adhesive was optimized. The variation of pull-through load was studied by varying the drying and curing temperature of the dipped nylon tire cord. RFL adhesive based on vinylpyridine latex was found to have better rubber-to-nylon tire cord bonding, compared with the one based on natural rubber latex. Addition of a formaldehyde donor into the RFL adhesive/rubber compound improves adhesion.

A model of school behavior: tuition fees and grading standards

This paper uses a hybrid human capital / signaling model to study grading standards in schools when tuition fees are allowed. The paper analyzes the grading standard set by a profit maximizing school and compares it with the efficient one. The paper also studies grading standards when tuition fees have limits. When fees are regulated a profit maximizing school will set lower grading standards than when they are not regulated. Credit constraints of families also induce schools to lower their standards. Given that in the model presented competition is not feasible, these results show the importance of regulation of grading standards.

Série tirée des essais de mise en commun de termes en vrac se référant aux acteurs, aux notions empruntées au social, au politique, à l'education, à la terminologie courante de la muséologie adaptée aux présupposés de la muséologie sociale

POPULATION = Terme générique pour désigner l’adhésion d’une population, ou d’un groupe significatif de citoyens d’un territoire d’appartenance, au projet de muséologie sociale. Celle-ci se mesure par le degré de participation, d’implication et de vision partagée, d’interaction au sein de la collectivité territoriale, son fief. PARTICIPANTS = Sont les acteurs actifs au sein de la population adhérante, partie prenante au projet de muséologie social. La participation se mesure selon le degré d’implication dans le projet et de compréhension de celui-ci (Intérêt, gestion partagée, militance, volonté de capacitation...) COOPÉRANT = Par solidarité, par engagement, il s’insère dans le système de l’action ccopérative, possédant ses règles propres, offrant sa contribution à l’unité de production conciliant la dimension sociale (de la muséologie), son idée au regroupement de personnes désireuses de contribuer à la production commune de biens de qualité au service de la population dont ils sont issus.

Use of scrap tire rubber in place of SBS in modified asphalt as an environmentally correct alternative for Brazil

Reusing scrap tires has become a worldwide challenge, especially due to the great difficulty in finding ecologically and economically feasible ways to dispose of them. This has led to the creation of specific programs and legislation for reusing scrap tires. Research has shown that a certain percentage of scrap tire rubber can be added to asphalt compositions, and this has become a worldwide practice. This paper describes the properties of four asphalt compositions modified with scrap tire rubber (STR) prepared in the laboratory. These properties are then compared with those of asphalt modified with styrene butadiene styrene (SBS), a synthetic polymer and one of the most common modifiers, to verify the feasibility of using scrap tire rubber as a substitute for SBS. The scope of this study does not include an analysis of how STR affects end-of-life asphalt. The main findings indicate that STR is a potential substitute of SBS in paving material, and although it does not meet some of the standard specifications when compared with SBS, these issues can be overcome by proper care during storage and transportation. The substitution of SBS by STR also showed the potential for about 10% in expenditure savings. (C) 2012 Elsevier Ltd. All rights reserved.

The higher grading structure of the WKI hierarchy and the two-component short pulse equation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Grading and staging chronic hepatitis C and its relation to genotypes and epidemiological factors in brazilian blood donors

Progression of chronic hepatitis C is known to be associated with some factors, but influence of HCV genotypes is still controversial. Association between HCV genotypes and other risk factors was examined to determine which factors are associated with progression of infection. One hundred consecutive anti-HCV positive volunteer blood donors were evaluated for several risk factors, examined for HCV genotypes, and submitted to hepatic biopsy and biochemical exams.HCV genotyping were carried out in 89 patients and hepatic biopsy in 78. Transmission routes were found to be illicit intravenous drug use (26%), Gluconergan® use in a non-safe manner (48%) and blood transfusion (15%). HCV genotype was 1 in 45%, 3 in 40%, and it was not associated with the stage of fibrosis or with inflammatory activity. There was no significant association of factors related to infection, chronic alcohol use, or duration of illness, with progression of the lesion. There was a significant association of aminotransferase levels and the fibrosis stage. Univariate analysis showed that the age at contamination, patient's age, GT-gamma, and aminotransferase levels over three times the upper normal limits, were associated with fibrosis stages 2 to 4. Multivariate analysis detected age (odds ratio=1.19), and GT-gamma (odds ratio=2.02) as independent factors.

PRACTICAL LAND GRADING BASED ON LEAST SQUARES.

Practical methods for land grading design of a plane surface for rectangular and irregularly shaped fields based on a least squares analysis are presented. The least squares procedure leads to a system of three linear equations with three unknowns for determination of the best-fit plane. The equations can be solved by determinants (Cramer's rule) using a procedure capable of solution by many programmable calculators. The detailed computational process for determining the equation of the plane and a simple method to find the centroid location of an irregular field are also given. An illustrative example and design instructions are included to demonstrate the application of the design procedure.

Higher grading conformal affine Toda theory and (generalized) sine-Gordon/massive Thirring duality

Some properties of the higher grading integrable generalizations of the conformal affine Toda systems are studied. The fields associated to the non-zero grade generators are Dirac spinors. The effective action is written in terms of the Wess-Zumino-Novikov-Witten (WZNW) action associated to an affine Lie algebra, and an off-critical theory is obtained as the result of the spontaneous breakdown of the conformal symmetry. Moreover, the off-critical theory presents a remarkable equivalence between the Noether and topological currents of the model. Related to the off-critical model we define a real and local lagrangian provided some reality conditions are imposed on the fields of the model. This real action model is expected to describe the soliton sector of the original model, and turns out to be the master action from which we uncover the weak-strong phases described by (generalized) massive Thirring and sine-Gordon type models, respectively. The case of any (untwisted) affine Lie algebra furnished with the principal gradation is studied in some detail. The example of s^l(n) (n = 2, 3) is presented explicitly. © SISSA/ISAS 2003.

Energetic efficiency of an agricultural tractor in function of tire inflation pressure

The tire inflation pressure, among other factors, determines the efficiency in which a tractor can exert traction. It was studied the effect of using two tire inflation pressures, 110.4 kPa in the front and rear wheels, 124.2 kPa in the front wheel and 138 kPa in the rear wheels, the energetic efficiency of an agricultural tractor of 147 kW of engine power, in the displacement speed of 6.0 km.h-1, on track with firm surface, with the tractor engine speed of 2000 rpm. For each condition of the tire pressure, the tested tractor was subjected to constant forces in the drawbar of 45 kN and 50 kN, covering 30 meters. It was used a randomized complete block with a 2x2 factorial arrangement (tire pressure and drawbar power) with four replications, totaling 16 experimental units. Data were subjected to analysis of variance, using the Tukey test at 5% probability for comparison averages. The lowest hourly and specific fuel consumption, the lowest slippage of the wheelsets and the highest efficiency in the drawbar was obtained with the tire inflation pressure of 110.4 kPa in the front and rear tires of the tractor, highlighting that lower pressures improve energetic and operational performance of the tractor.

Influence of the surface treatment of tire rubber residues added in mortars

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Performance evaluation and phylogenetic characterization of anaerobic fluidized bed reactors using ground tire and pet as support materials for biohydrogen production

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tractor perfomance as a function of speed and seeder s tire inflation pressure

O desempenho de tratores agrícolas em condições de campo resulta da interação entre pneu e rodado, influenciado pela velocidade de deslocamento. O objetivo deste trabalho foi avaliar o desempenho de um trator agrícola sob diferentes pressões de inflação dos pneus da semeadora (518, 483, and 414kPa) e em duas marchas que proporcionaram velocidades de 3,0 e 6,0km h-1. O experimento foi realizado no campus de Jaboticabal da Universidade Estadual Paulista (UNESP). O delineamento experimental utilizado foi fatorial inteiramente casualizado (3x2), com quatro repetições. A força de tração foi influenciada pela marcha e pela potência exigida; no entanto, a pressão de inflação do pneu da semeadora não alterou esses parâmetros. Além disso, o consumo de combustível foi influenciado apenas pela marcha do trator. O consumo de energia foi maior com o aumento da velocidade, ocasionada pela mudança de marcha. A velocidade de deslocamento foi maior para a pressão de 518kPa, em razão da menor patinagem da semeadora promovida por essa pressão. A patinagem do trator não foi alterada pelos fatores testados.