Symmetry breaking and competition effect in phase transitions.

This study is started from a photon-magnon model with a competition effect of the level attraction and repulsion, its Hermiticity is mainly decided by a phase-dependent and asymmetric coupling factor, namelyφ = 0 for Hermitian andϕ=πfor non-Hermitian. Then an extensional study predicts the quantum critical behaviors using an Hermitian and even no-Hermitian photon-spins model with an additional second-order drive. The numerical results firstly indicate that this coupling phaseφcan function the protective effect on quantum phase transitions (QPTs), and the new tricritical points can not only be modulated by this nonlinear drive, but also be influenced by the dissipation and the collective decoherence. Secondly, this competition effect can also induce a reversal of the value of order parameters between the positive and negative. This study can also bring more important results of QPTs toward the issue of symmetry breaking and non-Hermiticity.

Intelligent Sensors for dc Fault Location Scheme Based on Optimized Intelligent Architecture for HVdc Systems.

We develop a probabilistic model for determining the location of dc-link faults in MT-HVdc networks using discrete wavelet transforms (DWTs), Bayesian optimization, and multilayer artificial neural networks (ANNs) based on local information. Likewise, feedforward neural networks (FFNNs) are trained using the Levenberg-Marquardt backpropagation (LMBP) method, which multi-stage BO optimizes for efficiency. During training, the feature vectors at the sending terminal of the dc link are selected based on the norm values of the observed waveforms at various frequency bands. The multilayer ANN is trained using a comprehensive set of offline data that takes the denoising scheme into account. This choice not only helps to reduce the computational load but also provides better accuracy. An overall percentage error of 0.5144% is observed for the proposed algorithm when tested against fault resistances ranging from 10 to 485 Ω. The simulation results show that the proposed method can accurately estimate the fault site to a precision of 485 Ω and is more robust.

On the tunneling time of ultracold atoms through a system of two mazer cavities.

We study the resonant tunneling of ultraslow atoms through a system of high quality microwave cavities. We find that the phase tunneling time across the two coupled cavities exhibits more frequent resonances as compared to the single cavity interaction. The increased resonances are instrumental in the display of an alternate sub and superclassical character of the tunneling time along the momentum axis with increasing energies of the incident slow atoms. Here, the intercavity separation appears as an additional controlling parameter of the system that provides an efficient control of the superclassical behavior of the phase tunneling time. Further, we find that the phase time characteristics through two cavity system has the combined features of the tunneling through a double barrier and a double well arrangements.