Résumé : Nous avons mesuré la fréquence de formation de panaches dans une expérience de convection thermique à Pr >>1. Comme la viscosité du fluide utilisé varie fortement avec la température, les couches limites chaude et froide ont différentes épaisseurs et viscosités. Ceci entraîne des fréquences différentes pour ces couches. Il semblerait qu’il y ait une interaction directe entre les couche...

In the present study, vibration of cylindrical laminates with different layers and angles were studied. In order to actuate and polarize in radial direction, a piezoelectric layer was located at outer surface of composite shell. Laminates were assumed long enough so that plane strain state analysis in 2D can be used properly. In order to satisfy the boundary conditions, variables in terms of Fo...

The performance of a type of fuzzy sliding mode control is researched by considering the nonlinear characteristic of a missile-target interception problem to obtain a robust interception process. The variable boundary layer by using fuzzy logic is proposed to reduce the chattering around the switching surface then is applied to the interception model which was derived. The performances of the s...

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Related Articles Convection and reaction in a diffusive boundary layer in a porous medium: Nonlinear dynamics Chaos 22, 037113 (2012) Symmetry analysis and self-similar forms of fluid flow and heat-mass transfer in turbulent boundary layer flow of a nanofluid Phys. Fluids 24, 092003 (2012) Detuned resonances of Tollmien-Schlichting waves in an airfoil boundary layer: Experiment, theory, and dir...

A class of uncertain systems nonlinear in the input variable and driven by a dynamic actuator device is dealt with. We give sufficient conditions under which the feedback controller based on the “Sub-optimal” second-order slidingmode control algorithm can guarantee the attainment of a boundary layer of the sliding manifold. The relationship between the actuator parameters and the size of the bo...

Presented in this paper is an analytic approximation to the thermal-fluid problem involving mixed convective heat transfer from a rotating isothermal cylinder placed in a non-uniform stream shear flow. The approximation is obtained using a series expansion of the scaled boundary layer equations in terms of an appropriate boundary layer variable. The resulting approximation is valid both for sma...

This paper is the rst of a series of two, where we study the asymp-totics of the displacement in a thin clamped plate made of a rigid \monoclinic" material , as the thickness of the plate tends to 0. The combination of a polynomial Ansatz (outer expansion) and of a boundary layer Ansatz (inner expansion) yields a complete multi-scale asymptotics of the displacement and leads to optimal error es...

Sliding mode control is a nonlinear control technique, which is robust against some classes of uncertainties and disturbances. However, this control produces chattering which can cause instability due to unmodeled dynamics and can also cause damage to actuators or the plant. There are essentially two ways to counter the chattering phenomenon. One way is to use higher order sliding mode, and the...