Abstract In this paper, a real-time predictive filter is derived for nonlinear systems. The major advantage of this new filter over conventional filters is that it provides a method of determining optimal state estimates in the presence of significant error in the assumed (nominal) model. The new real-time nonlinear filter determines (“predicts”) the optimal model error trajectory so that the m...

A damage detection method is developed for nonlinear systems using model updating. The method uses a nonlinear discrete model of the system and the form of the nonlinearities to create an augmented linear model of the system. A modal analysis technique that uses forcing that is known but not prescribed is then used to solve for the modal properties of the augmented linear system after the onset...

We are interested in modelling Darwinian evolution, resulting from the interplay of phenotypic variation and natural selection through ecological interactions. Our models are rooted in the microscopic, stochastic description of a population of discrete individuals characterized by one or several adaptive traits. The population is modelled as a stochastic point process whose generator captures t...

This paper addresses the problem of obtaining models of nonlinear mechanisms for use in virtual prototyping systems. The objective of the described modeling procedure is to more accurately represent the feel of complex mechanisms in force feedback applications. The model structure selected for this study is a 2-order impedance model, with mass, damping, stiffness, and coulomb friction that vary...

In this paper, a sensor fault detection and isolation scheme for nonlinear systems is considered. A nonlinear diffeomorphism is introduced to explore the system structure and a simple filter is presented to ‘transform’ the sensor fault into a pseudo-actuator fault scenario. A sliding mode observer is designed to reconstruct the sensor fault precisely if the system does not experience any uncert...

A theory with experimental verifications has been developed to investigate the nonlinear behavior of comb drive actuators under applied external electrical potential and Joule heating effects. The nonlinear behavior originates from coupled effects of the beam structure under applied electrical potential with electrostatically induced tensile stress and thermally induced compressive stress. Deta...

A desirable characteristic for nonlinear vibration isolators is a high static stiffness and a low dynamic stiffness. A curved beam is a possible candidate for this role provided that the amplitude of vibration about the static equilibrium position is sufficiently small. However, for large amplitude oscillations, the nonlinear dynamics may have a detrimental effect. This paper considers the forc...

A glottal model based on physical constraints is proposed. The model describes the vocal fold as a simple oscillator, i.e. a damped mass-spring system. The oscillator is coupled with a nonlinear block, accounting for fold interaction with the airflow. The nonlinear block is modelled as a regressor-based functional with weights to be identified, and a pitch-synchronous identification procedure i...

We present a flexible, distributed and effective technique to model custom distortions of images. The main idea is to use a mass-spring model to create a flexible surface and to create distortions by changing the rest-lengths. A physical simulation works out the displacements of this particle grid. We provide intuitive tools to interactively design such nonlinear magnifications. In addition, ou...

The nanomechanical properties of gram-negative bacteria (Shewanella putrefaciens) were investigated in situ in aqueous solutions at two pH values, specifically, 4 and 10, by atomic force microscopy (AFM). For both pH values, the approach force curves exhibited subsequent nonlinear and linear regimens that were related to the progressive indentation of the AFM tip in the bacterial cell wall, inc...