Quasiperiodic Rings Research Articles

Mathematical modeling and dynamic analysis of insulated bearing-steel pedestal system under shaft current damage

The insulated bearing may be damaged when operating under the action of current. Firstly, a novel dynamic model of insulated bearing-steel pedestal system with shaft current damage is proposed, and the model is solved based on the Runge-Kutta algorithm. Then, the model is verified by the experimental results. Based on the solution results of the dynamic model, the influence of mass and damage on the vibration signal is analyzed, the effect of damage on the stability of the insulated bearing-steel pedestal system is studied, and the influence of radial clearance on the vibration characteristics of the insulated bearing-steel pedestal system is discussed. The results indicate that, the vibration acceleration signal of the pedestal shows a positive correlation with the mass m i and the mass m o. As the length of damage increases, a few points begin to leave the quasi-periodic ring, and the quasi-periodic ring in Poincaré map gradually breaks. The coupling effect of shaft current damage and radial clearance makes the insulated bearing-steel pedestal system easier to enter an unstable motion state.

Ring patterns generated by an expanding colloidal meniscus.

The drop-and-dry is a common technique allowing for creation of periodic nanoparticle (NP) structures for sensing, photonics, catalysis, etc. However, the reproducibility and scalability of this approach for fabrication of NP-based structures faces serious challenges due to the complexity of the simple, at first glance, evaporation process. In this work we study the effect of the spatial confinement on the NP self-assembly under slow solvent evaporation, when the air-liquid-substrate contact line (CL) expands from the center towards the walls of a cylindrical cell, forming a toroid. Using in situ video monitoring of the stick-slip CL motion, we find regular hydrodynamic perturbations in the meniscus, and reveal fine details of the formation of quasiperiodic rings of close packed NP layers. We report that drying of the toroidal NP droplet has a number of important differences from drying of the classical hemispherical colloidal drops. In toroidal drops we observe linear-in-time average meniscus motion, in contrast to the hemispherical drops where the meniscus moves as a square root of time. While both droplet geometries produce NP ring patterns, the ring width for the toroidal drop decreases with increasing ring radius, while it decreases with decreasing the radius of the hemispherical drop. We suggest that free ligands are the main cause of the Marangoni instabilities driving the periodic vorticity in the meniscus. In addition, we show that the usually ignored contact line tension may yield a considerable contribution to the CL pinning causing the CL slip-stick motion and the ring formation.

Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov–Casher effect

Abstract We propose strongly localized persistent spin current in one-dimensional defect-free quasiperiodic Thue–Morse rings with Aharonov–Casher effect. The results show that the characteristics of these localized persistent currents depend not only on the radius filling factor, but also on the strength of the spin–orbit interaction. The maximum persistent spin currents in systems always appear in the ring near the middle position of the system array whether or not the Thue–Morse rings array is symmetrical. The magnitude of the persistent currents is proportional to the sharpness of the resonance peak, which is dependent on the bandwidth of the allowed band in the band structure. The maximum persistent spin currents also increase exponentially as the generation order of the system increases.

High-Q filters with complete transports using quasiperiodic rings with spin-orbit interaction

A high Q filter with complete transports is achieved using a quasiperiodic Thue-Morse array of mesoscopic rings with spin-orbit interaction. As the generation order of the Thue-Morse array increases, not only does the Q factor of the resonance peak increase exponentially, but the number of sharp resonance peaks also increases. The maximum Q factor for the electronic filter of a Thue-Morse array is much greater than that in a periodic array, for the same number of the rings.

A renormalization group study of persistent current in a quasiperiodic ring

We propose a real-space renormalization group approach for evaluating persistent current in a multi-channel quasiperiodic Fibonacci tight-binding ring based on a Green's function formalism. Unlike the traditional methods, the present scheme provides a powerful tool for the theoretical description of persistent current with a very high degree of accuracy in large periodic and quasiperiodic rings, even in the micron scale range, which emphasizes the merit of this work.

On the critical level curvature distribution

The parametric motion of energy levels for non-interacting electrons at the Anderson localization critical point is studied by computing the energy level curvatures for a quasi-periodic ring with twisted boundary conditions. We find a critical distribution which has the universal random matrix theory form for large level curvatures |K| corresponding to quantum diffusion, although overall it is close to approximate log-normal statistics corresponding to localization. The obtained hybrid distribution resembles the critical distribution of the disordered Anderson model and makes a connection to recent experimental data.