Dynamic Simulation of a Fe-Ga Energy Harvester Prototype Through a Preisach-Type Hysteresis Model.

This paper presents the modeling of an Fe-Ga energy harvester prototype, within a large range of values of operating parameters (mechanical preload, amplitude and frequency of dynamic load, electric load resistance). The simulations, based on a hysteretic Preisach-type model, employ a voltage-driven finite element formulation using the fixed-point technique, to handle the material nonlinearities. Due to the magneto-mechanical characteristics of Fe-Ga, a preliminary tuning must be performed for each preload to individualize the fixed point constant, to ensure a good convergence of the method. This paper demonstrates how this approach leads to good results for the Fe-Ga prototype. The relative discrepancies between experimental and computational values of the output power remain lower than 5% in the entire range of operating parameters considered.

Skeletal and dental effects produced by functional regulator-2 in pre-pubertal class II patients: a controlled study.

BACKGROUND: Whether skeletal effects are obtained by functional appliances in class II subjects is still controversial. In this regard, most of the available studies did not clearly identify the growth phases (i.e. pubertal or not) of the treated patients. This retrospective controlled study aimed at evaluating the skeletal and dental changes in class II subjects produced by the functional regulator (FR)-2 treatment during the pre-pubertal growth phase. METHODS: The data were derived from records obtained at a university dental clinic. A total of 17 treated subjects and a total of 17 untreated controls, all pre-pubertal, matched for malocclusion, age (8.8±1.5 years) and sex (18 females, 16 males), were included. The overall observational period was 1.6±0.8 years for both groups. RESULTS: Only minor skeletal changes with very little clinical relevance were seen after the observational period. Most of the changes produced by the FR-2 treatment were at the dental level including palatal tipping of the maxillary incisors and slight proclination of the mandibular incisors, both accounting for the noteworthy overjet reduction. CONCLUSIONS: The present study has shown that functional treatment of class II malocclusion by FR-2 appliance during the pre-pubertal growth phase is limited to modification at the dental level.