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This paper presents an example of the advantages of using mathematical viability theory concepts and tools to study sustainable development issues. Instead of seeking optimal solutions according to a predefined value function, viability theory follows a inverse approach and does not postulate any a priori behaviours. Its methods and tools concern the set of all evolutions from a given situation that remain within a given set of constraints. An evolution is called viable (sustainable) if constraints are permanently satisfied. These constraints may be physical and as such imperative, or normative and consequently possibly modifiable. The aim of the paper is to show that the viability approach does not only encompass constraint satisfaction but also helps solve intertemporal optimisation problems. By applying a macroeconomic model generally used as a benchmark model to study theoretical issues of sustainable development we propose a new approach to assessing intergenerational equity. We describe two viability approaches to tackle the intergenerational equity issue: the first, proposed earlier by previous authors, concerns a minimal set of guaranteed rights for all generations; the second aims to minimize inequalities between generations while respecting resources and production constraints. Numerical computations have been performed to graphically display the solutions. [ABSTRACT FROM AUTHOR]

The cold spray process uses mainly the impact energy of the particles to achieve dense coatings. As the kinetic energy is directly linked to the particles velocity, it is crucial to maximize their acceleration to obtain a high deposition efficiency. The momentum transfert can be optimized by modifying the set of parameters of the spraying system and also by using a correct standoff distance. This paper describes a 2D numerical model used with Fluent software that permits to compute the behavior of a jet of titanium particles inside a supersonic flow. The results show that the maximum velocity is not obtained at the exit of the nozzle but 90 mm downstream. This is the standoff distance that must be used to optimize the spraying process. The accuracy of the numerical computations is checked by an experimental procedure and the variations of the coating thickness clearly show the drastic influence of the standoff distance on the deposition efficiency. [ABSTRACT FROM AUTHOR]

This paper presents the optimization of functional tolerancing by dispersions method, this later has made this evidence in manufacturing dimensions optimization. In this work the dispersions method on the basis of unknown variables is combined with the minimal transfer method for automatically the modelling of the functional requirements of a mechanical assembly. The simulation is constructed around two procedures. The first procedure executes the extraction of the functional requirements, the second procedure results in the optimization of the dispersions. The functional dimensions are synthesized by uses of the optimised values of the dispersions to compute the mean values and tolerances of the functional dimensions in the chains. They are in adequacy with the writing within the meaning of the ISO standard of the functional dimensions. [ABSTRACT FROM AUTHOR]

This paper presents a new approach of robust multi-objective optimization and multilevel for design of complex mechanical structures. This optimization is on two levels: system and elements. The robust multi-objective problem on system-level to be solved is with four cost functions: on the one hand the minimization of the global mass and displacement. in a fixed point of mechanical structure to be studied, arid on the other hand the maximization of the robustness respectively of the mass and displacement whereas the robust multi-objective problem on the element-level is with two cost functions: minimization of the element mass and maximization of its robustness. Contrary to the existing formulations, this new approach takes into account uncertainties on the design parameters on the system-level and on the element-level. Moreover, it answers the task sharing commonly used in industry field. [ABSTRACT FROM AUTHOR]

Abstract: Highly Active Anti-Retroviral Therapies (HAART) have proven to be extremely effective in improving and prolonging the patient''s life. Though, a concern arises since a long term drug intake induces many strong sides effects and reduces reactivity of the virus to any therapy. The purpose of the paper is to use numerical analysis and optimization tools to suggest improved therapies to handle HIV infection. The evolution of the infection is modelled by an ordinary differential equation system which includes both immune response and multi-drug effects. For a fixed time, one looks for a two drugs control strategy based on Pontryagine''s minimum principle with an objective function which takes into account three contributions: the viral load, the transient evolution of infection and the quantities of drug used. Simulations are carried out using an indirect optimization method along with Runge–Kutta adaptative stepsize algorithm. Numerical solutions to the optimality system are obtained and related histories are shown. The possibility of Scheduled Treatment Interruption is also examined. [Copyright &y& Elsevier]

The aim of this paper is to propose the wavelet analysis as an effective tool allowing to improve the sensitivity of scalar indicators (Kurtosis and crest factor) for the identification of mechanical faults inducing impulsive forces. Indeed, these indicators are very sensitive to the variations in temporal signal due to the periodic shocks caused by the defect. Nevertheless, their reliability is immediately limited by the presence of high level of random noise associated to a small gravity of the defect. Wavelet Multiresolution Analysis (WMRA) is proposed as a solution to this problem. Adapted for such objective, several of its parameters were chosen, even optimized. Initially, the proposed method is applied to simulated signal. For the experimental validation, several series of experiments were realized on ball and cylindrical roller bearings, on which various defects were caused. Measurements were taken with various configurations, 210 signals were measured at different sampling rates and rotation speeds on a laboratory test rig, the industrial application is carried out on a turbo alternator. [ABSTRACT FROM AUTHOR]

This paper presents a study devoted to the composite fabric shaping simulation in finite strain analysis. We introduce a new geometrical approach based on the fishnet method for which the deformation of a fabric mesh element consists in a pure trellis effect. Such a fabric mesh element is then defined by a curved quadrilateral whose edges are geodesic lines with the same length plotted onto the surface to drape. Given three vertices of the fabric mesh element on the surface, we propose an optimization algorithm to define the fourth vertex of the fabric mesh element. This algorithm allows us to drape the surface using an advancing front approach from the data of an initial impact point between the fabric and the surface and the initial fibre directions at this point. A numerical draping simulation example using this approach is given. To cite this article: H. Borouchaki, A. Cherouat, C. R. Mecanique 331 (2003). [Copyright &y& Elsevier]