196,237 research outputs found
Controlling chaos with parametric perturbations
No full textWe consider the effects of parametric perturbation on the onset of chaos in different dynamical systems. Favoring or suppression of chaos was observed depending on the phase or the frequency of the periodic perturbation. A lowering of the threshold of chaos was observed in an electronic device simulating a Josephson-Junction model and the suppression of chaos was obtained in a bistable mechanical device. We showed that in case of spatial instability in a sample of liquid crystal, the action of the parametric perturbation is to modify the velocity and the onset of the defects. Considering that the emergence of defects precedes the threshold of spatio-temporal chaos, we infer that parametric perturbation can modify the threshold of chaos in this spatial dynamical system
Carelli P., Giocondo C., Murru M., Spazi e forme della comunicazione politica. Il manifesto nella campagna elettorale 2008, in I media e la città, «Comunicazioni sociali online», n.1, 2009
No full textEXPERIMENTAL-EVIDENCE OF SUPPRESSION OF CHAOS BY RESONANT PARAMETRIC PERTURBATIONS
No full textExperimental results are reported concerning the possibility of reducing and even suppressing chaoticity in a bistable magnetoelastic beam system by means of parametric periodic perturbations. The experimental parameters are chosen such that a strange attractor is observed. Then a parametric perturbation is added. When its frequency approaches some resonant value, laminar phases are observed of increasing duration up to complete regularization of the motion at exact resonance
Anchoring energy for nematic liquid crystals: contribution from the spatial variation of the elastic constants
No full text
The natural evolution of endoscopic approaches in skull base surgery: robotic-assisted surgery?
No full textThe current surgical trend is to expand the variety of minimally invasive approaches and, in particular, the possible applications of robotic systems in head and neck surgery. This is particularly intriguing in skull base regions. In this paper, we review the current literature and propose personal considerations on the role of robotic techniques in this field. A brief description of our personal preclinical experience on skull base robotic dissection represents the basis for further considerations. We are convinced that the advantages of robotic surgery applied to the posterior cranial fossa are similar to those already clinically experienced in other areas (oropharynx, tongue base), in terms of tremor-free, bimanual, precise dissection: the implementation of instruments for bony work and resolving current drawbacks will definitely increase the applicability of such a system in forthcoming years
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