In this paper, we propose an interactive system for reconstructing human facial expression. In the system, a nonlinear mass-spring model is employed to simulate twenty two facial muscles’ tensions during facial expressions, and then the elastic forces of these tensions are grouped into a vector which is used as the input for facial expression recognition. The experimental results show that the ...

This paper shows how globally attractive limit cycle oscillations can be induced in a system with a nonlinear feedback element. Based on the same principle as the Van der Pol oscillator, the feedback behaves as a negative damping for low velocities but as an ordinary damper for high velocities. This nonlinear damper can be physically implemented with a continuous variable transmission and a spr...

This paper presents the initial investigation of nonlinear control for a magnetic spring. The combination of a magnet pair in repulsion and a magnet pair in attraction create a spring with a quadratic force curve. At its nominal position, it is a marginally stable system that has interesting vibration isolation properties. Non-linear control is shown to be effective in stabilising the system.

Charalampos Skokos Department of Mathematics and Center for Research and Applications of Nonlinear Systems, (CRANS), University of Patras, GR-26500 Patras, Greece and Research Center for Astronomy and Applied Mathematics, Academy of Athens, Soranou Efesiou 4 GR-11527, Athens, Greece Existence and Stability of Localized Oscillations in 1-Dimensional Lattices With Soft-Spring and Hard-Spring Pote...

Abstract: This paper provides new developments in the design of observers for nonlinear systems with unknown inputs. The proposed methods guarantee the error system stability and yield many additional degrees of freedom available to the designer. The algorithms for designing a nonlinear observer for nonlinear systems with unknown inputs is derived in detail. The proposed observers may be used f...

In this work, the equilibrium shape and dynamics of a primary cilium under flow are investigated by using both theoretical modeling and experiment. The cilium is modeled as an elastic beam that may undergo large deflection due to the hydrodynamic load. Equilibrium results show that the anchoring effects of the basal body on the cilium axoneme behave as a nonlinear rotational spring. Details of ...

Long flexible polymers undergo a coil to stretch transition (CST) in an elongational flow. Near the CST, a peak can be observed in the fluctuations of the size of a molecule (|R|). Solvent effects on the fluctuations are studied using Brownian dynamics simulations of a nonlinear spring force relation that can represent real molecules. Ignoring the influence of hydrodynamic interactions, a linea...

A nonlinear elastic foundation model has been developed to predict the mixed-mode (modes I and II) delamination failure of laminated composites. Two types of nonlinear elastic foundations were used to represent pure mode I and pure mode II components of the material failure ahead of the crack tip. One is a tension spring foundation for mode I component and the other is a shear spring foundation...