Nonlinear vibration of iced cable under wind excitation using three-degree-of-freedom model

High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force.In this paper,the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated.Considering the excitation caused by pulsed wind and the movement of the support,the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton's principle.By the Galerkin method,the partial differential equations are then discretized into ordinary differential equations.The method of multiple scales is then used to obtain the averaged equations of the iced cable,and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered.The numerical simulations are performed to investigate the dynamic response of the iced cable.It is found that there exist periodic,multi-periodic,and chaotic motions of the iced cable subjected to wind excitation.

Chiral Recognition and Resolution Based on Helical Polymers

Helical polymers have attracted a great deal of attention and been extensively investigated due to their various applications.One of the most importa nt applicati ons of helical polymers is chiral recog nition and resolutio n ofe nan tiomersforthe reas on that a pair of e nan tiomers is comm only with differe nt physiological and toxicological behaviors in biological systems.Helical polymers usually prese nt un expected high chiral recogniti on ability to a variety of racemic compo unds.Whatzs more,the chiral recog nition and resolution abilities of the system are depe ndent on the highly ordered helical structures of the helical polymers.This mini review mainly focuses on the recent progress in chiral recognition and resolution based on helical polymers.The synthetic methodology for helical polymers is firstly discussed briefly.Then recent advances of chiral recog nition and resoluti on systems based on helical polymers,especially polyacetylenes and polyisocya nides,are described.We hope this mini review will in spire more in terest in developing helical polymers and en courage further advances in chiral-related disciplines.