The present work describes an alternative methodology for identification of aeroelastic stability in a range of varying parameters. Analysis is performed in time domain based on Lyapunov stability and solved by convex optimization algorithms. The theory is outlined and simulations are carried out on a benchmark system to illustrate the method. The classical methodology with the analysis of the system's eigenvalues is presented for comparing the results and validating the approach. The aeroelastic model is represented in state space format and the unsteady aerodynamic forces are written in time domain using rational function approximation. The problem is formulated as a polytopic differential inclusion system and the conceptual idea can be used in two different applications. In the first application the method verifies the aeroelastic stability in a range of air density (or its equivalent altitude range). In the second one, the stability is verified for a rage of velocities. These analyses are in contrast to the classical discrete analysis performed at fixed air density/velocity values. It is shown that this method is efficient to identify stability regions in the flight envelope and it offers promise for robust flutter identification.

OBJETIVOS: Avaliar o efeito protetor de diferentes doses de fenoterol (F) inalado sobre a broncoconstrição induzida por metacolina (M). TIPO DE ESTUDO: estudo duplo-cego e randomizado. LOCAL: Centro de referência. PARTICIPANTES: Nove crianças (7 a 15 anos) com asma leve ou moderada, alérgicas ao D. pteronyssinus. INTERVENÇÃO: As doses de F (25 ou 50 ou 100 ou 200 µg) foram administradas por inalação com circuito fechado (De Vilbiss 646). No primeiro dia determinou-se a concentração de M capaz de induzir queda de 20% nos valores de VEF1 (CP20VEF1). Nos dias subseqüentes, inalavam a dose de F pelo mesmo circuito medindo o VEF1 15 minutos após (referência). A seguir iniciavam a broncoprovocação pela concentração anterior à da CP20VEF1 do primeiro dia e prosseguiam até que houvesse queda de 20% no valor do VEF1 para a determinação do novo CP20VEF1. RESULTADOS: O F inalado na dose de 25 µg protegeu 2/9 crianças e na de 50 µg houve proteção de 4/9 crianças. Todos os pacientes foram protegidos com as doses de 100 e 200 µg. Não observamos relação entre a magnitude da broncodilatação e broncoproteção induzidas pela inalação do F. CONCLUSÕES: Nossos resultados sugerem que a dose de 100 µg de F é protetora da broncoconstrição em crianças com asma leve/moderada.

OBJECTIVE: To evaluate the protective effect of different doses of inhaled fenoterol (F) on bronchoconstriction induced by methacholine (M). DESIGN: randomized double-blind study. SETTING: Referrence center. PARTICIPANTS: 9 children (aged from 7 to 15 years old), with mild or moderate asthma and allergic to D. pteronyssinus. INTERVENTION: On the first day, the M concentration necessary to induce a 20% fall in the forced expiratory volume in the first second (FEV1; PC20FEV1) was determined using closed circuit inhalation (De Vilbiss 646). On subsequent days, the children inhaled a dose of F (25 or 50 or 100 or 200 µg) through the same circuit and, after 15 minutes the FEV1 was measured, becoming the basal value. Bronchoprovocation was then initiated using the concentration prior to the PC20FEV1 of the first day and continuing until there was a 20% fall in the FEV1. This concentration was the "new" PC20FEV1. RESULTS: F in a dose of 25 µg protected 2 of the 9 children, in a dose of 50 mg protected 4 of the 9 and in doses of 100 and 200 µg protected all children. We did not observe any relationship between the magnitude of the bronchodilation and bronchoprotection induced by the inhalation of F. CONCLUSIONS: Our results suggest that a dose of 100 µg of F is capable of inducing bronchoprotection in children with mild/moderate asthma.