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Impact strength of composites with nano-enhanced resin after fire exposure
Reis, P. N. B.; Ferreira, J. A. M.; Zhang, Z. Y.; Benameur, T.; Richardson, M. O. W.Composite materials have been widely used in several engineering applications. However, there are very few studies about the effects of nanoclays on the impact strength of laminates after exposure to the fire. Therefore, this paper intends to study this subject and the impact performance was analysed by low velocity impact tests carried out at different incident impact energy levels. For better dispersion and i...
Effect of the micromoulding process conditions on polymer flow behavior within ...
Zhiltsova, T. V.; Oliveira, M. S. A.; Ferreira, J. A.; Vasco, Joel Oliveira Correia; Pouzada, A. S.; Pontes, A. J.Fast time to market along with high level of automation and versatility made microinjection moulding, by far, a favorite technique for the mass production of microplastic components. In the microimpressions, very high shear rates develop, eventually leading to excessive shear heating and consequently to less predictable flow behaviour comparing to conventional injection moulding. In this study, the flow behavio...
Residual stresses analysis in plasma dressed welded joints
Ramalho, A. L.; Ferreira, J. A. M.; Branco, C. M.The presence of residual stresses in a structure influences his behaviour. Fatigue strength of welded joints is significantly influenced by the presence of residual stresses, of flaws and notch sharpness at the weld toe. Plasma dressing at the weld toe is frequently used to remove flaws and to lessen the notch sharpness at the weld toe. With this re-melt, the stress field in the weld toe is also profoundly modi...
Randomized clinical trial comparing the efficacy of the vaginal use of metronid...
Leite,S.R.R.F.; Amorim,M.M.R.; Sereno,P.F.B.; Leite,T.N.F.; Ferreira,J.A.C.; Ximenes,R.A.A.A 7.4% vaginal extract of the Brazilian pepper tree (Schinus terebinthifolius Raddi) was compared with 0.75% vaginal metronidazole, both manufactured by the Hebron Laboratory, for the treatment of bacterial vaginosis, used at bedtime for 7 nights. The condition was diagnosed using the combined criteria of Amsel and Nugent in two groups of 140 and 137 women, aged between 18 and 40 years. Intention-to-treat analy...
Fatigue Behaviour of T Welded Joints Rehabilitated by Tungsten Inert Gas and Pl...
Ramalho, A.; Ferreira, J. A. M.; Branco, C. M.This paper concerns a fatigue study on the effect of tungsten inert gas (TIG) and plasma dressing in non-load-carrying fillet welds of structural steel with medium strength. The fatigue tests were performed in three point bending at the main plate under constant amplitude loading, with a stress ratio of R = 0.05 and a frequency of 7 Hz. Fatigue results are presented in the form of nominal stress range versus f...
Flux Tracking in delivery polymeric systems
Ferreira, J. A.; Oliveira, P. de; Silva, P. M. da; Simon, L.The dynamics of diffusive and stress-induced transport in polymeric delivery systems was investigated. Partial and ordinary differential equations were first written to describe drug release behaviors in Maxwell and Maxwell-Voigt materials. The time constants governing the flux and concentration responses of a permeating species were determined from a Laplace transform solution of the original model. A ”trackin...
Drug delivery: from a contact lens to the anterior chamber
Ferreira, J. A.; Oliveira, P. de; Silva, P. M. da; Murta, J. N.Mathematical models to describe drug concentration profiles of topically administered drug in the anterior chamber aqueous humor have been proposed by several authors. The aim of this paper is to present a mathematical model to predict the drug concentration in the anterior chamber when a therapeutical contact lens with the drug is entrapped in nanoparticles is used.
Coupled vehicle-skin models for drug release
Barbeiro, S.; Ferreira, J. A.http://www.sciencedirect.com/science/article/B6V29-4VM43XG-1/2/493993c9687e5ff240f132118604a862
Lifting solutions of quasilinear convection-dominated problems
Ferreira, J. A.; Mouro, A. P.; Oliveira, P.In certain cases, quasilinear convection-diffusion-reaction equations range from parabolic to almost hyperbolic, depending on the ratio between convection and diffusion coefficients. From a numerical point of view, two main difficulties can arise related to the existence of layers and/or the non-smoothness of the coefficients of such equations. In this paper we study the steady-state solution of a convection-do...
H1-second order convergent estimates for non Fickian models
Barbeiro, S.; Ferreira, J. A.; Pinto, L.In this paper we study numerical methods for integro-differential initial boundary value problems that arise, naturally, in many applications such as heat conduction in materials with memory, diffusion in polymers and diffusion in porous media. We propose finite difference methods to compute approximations for the continuous solutions of such problems. For those methods we analyze the stability and study the co...
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