SUMMARYTangent operators and design sensitivities are derived for transient non-linear coupled problems. The solution process and the formation of tangent operators are presented in a systematic manner and sensitivities for a generalized response functional are formulated via both the direct differentiation and adjoint methods. The derived formulations are suitable for finite element implementations. Analyses of systems, with materials that exhibit history dependent response, may be obtained directly by applying the analyses of transient %on-linear coupled systems. Rate-independent elastoplasticity is investigated as a case study and a problem with an analytical solution is analysed for demonstration purposes.

International audienceMost recent crowd simulation algorithms equip agents with a synthetic vision component for steering. They offer promising perspectives through a more realistic simulation of the way humans navigate according to their perception of the surrounding environment. In this paper, we propose a new perception/motion loop to steering agents along collision free trajectories that significantly improves the quality of vision-based crowd simulators. In contrast with solutions where agents avoid collisions in a purely reactive (binary) way, we suggest exploring the full range of possible adaptations and retaining the locally optimal one. To this end, we introduce a cost function, based on perceptual variables, which estimates an agent's situation considering both the risks of future collision and a desired destination. We then compute the partial derivatives of that function with respect to all possible motion adaptations. The agent then adapts its motion by following the gradient. This paper has thus two main contributions: the definition of a general purpose control scheme for steering synthetic vision-based agents; and the proposition of cost functions for evaluating the perceived danger of the current situation. We demonstrate improvements in several cases

No abstract

SUMMARYA systematic approach for the design of weakly coupled thermoelastoplastic systems is presented. The Newton-Raphson iteration method is used in the solution process so that analytic design sensitivity formulations may be efficiently derived via the direct differentiation technique. The derived formulations are suitable for finite element implementations. Analysis and sensitivity analysis capabilities are combined with numerical optimization to form an optimum design algorithm. To demonstrate the algorithm, we optimally design a weldment with respect to manufacturing and service life aspects.

No abstract

This paper addresses the problem of autonomous behaviors of virtual characters. We postulate that a behavior is regarded as autonomous when the actions performed by the agent result from the interaction between its internal dynamics and the environment, rather than being externally controlled. In this work, we argue that an autonomous behavior is an agent's solution to a given problem, which is obtained through a process of self-organization of the dynamics of a system that is composed of the agent's controller, its body and the environment. That process allows the emergence of complex behaviors without any description of actions or objectives. We show a technique capable of adapting an artificial neural network to consistently control virtual Khepera-like robots by means of simulated reproduction, with no measure of the robots' fitness. All the robots are either male or female, and they are capable of evolving different kinds of behaviors according to their own characteristics, guided solely by the environment's dynamics.

No abstract

No abstract