Multiple reversals of vortex ratchet effects in a superconducting strip with inclined dynamic pinning landscape

Using time-dependent Ginzburg-Landau formalism,we investigate the multiple reversals of ratchet effects in an unpatterned superconducting strip by the tilted dynamic pinning potential.In the case of collinear sliding potential and Lorentz force,vortices are always confined in the channels induced by sliding potential.However,due to the inclination angle of sliding pinning potential with respect to the Lorentz force,vortices could be driven out of the channels,and unexpected results with multiple reversals of vortex rectifications are observed.The mechanism of multiple reversals of vortex rectifications is explored by analyzing different vortex motion scenarios with increasing ac current amplitudes.The multiple reversals of transverse and longitudinal ratchet effects can be highly controlled by ac amplitude and dynamic pinning velocity.What's more,at certain large current the ratchet effect reaches strongest within a wide range of pinning sliding velocity.

Chaotic Ratchet Effect for Bose-Einstein Condensed Atoms in 1D Optical Lattices

The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.

Low cycle fatigue behavior of zirconium−titanium−steel composite plate

The low cycle fatigue behavior of zirconium−titanium−steel composite plate under symmetrical and asymmetric stress control was studied.The effects of mean stress and stress amplitude on cyclic deformation,ratcheting effect and damage mechanism were discussed in detail.The results show that under symmetric stress control,the forward ratcheting deformation is observed.Under asymmetric stress control,the ratcheting strain increases rapidly with mean stress and stress amplitude increasing.Under high stress amplitude,the influence of mean stress is more significant.In addition,by studying the variation of strain energy density,it is found that the stress amplitude mainly promotes the fatigue damage,while the mean stress leads to the ratcheting damage.In addition,fractographic observation shows that the crack initiates in the brittle metal compound at the interface,and the steel has higher resistance to crack propagation.Finally,the accuracy of life prediction model considering ratcheting effect is discussed in detail,and a high-precision life prediction model directly based on mean stress and stress amplitude is proposed.

The Budget Execution Quality of Related Party Transactions: Evidence from Hong Kong

This paper proposes to use the related party transactions’(RPT)budget completion ratio(BCR)as indicator of RPT’s execution quality.This paper studies BCR by defining budget ceiling through RPTs announcement and comparing the amount disclosed in annual report as budget execution result.Through statistical analysis of 285 RPT announcements,we classify RPT’s BCR into four benchmark grades.This paper sums up the BCR of RPT from the samples,and deduces moral obligation and moral judgement curve(OJ curve)in terms of BCR.OJ curve is the real dynamic equilibrium after the struggle agency problems.From our statistical results,we verified that Weitzman’s ratchet effect exists in the budget formulation of RPTs,and it is a solid proof of Weitzman’s ratchet effect applied to real business scenarios.The empirical results show ratchet effect exists in BCR of RPTs before and after the change from GEM board listing to main board listing in Hong Kong(Transfer).This paper also finds that it is significant to find the estimated actual amount in the coming year through the budget completion ratio(BCR)of RPT from last year.This paper is a pioneer to examine the execution quality of RPT by the means of(i)Weitzman’s Truth Inducing Model,(ii)BCR,and(iii)SGR as well as(iv)estimated actual amount.

Spontaneous unidirectional rotation of a symmetric gear driven by spherical active particles

Time reversal asymmetry and spatial anisotropy are considered two prerequisites for Brownian ratchet.An intriguing realization can be achieved by placing an asymmetric gear in the suspension of motile rod-like bacteria.Usually,alignment interactions caused by anisotropic collisions or hydrodynamics would boost the ratchet effect.Here,we are concerned with a perfectly isotropic system,i.e.,symmetric gear immersed in a bath of spherical active Brownian particles.We find that,under certain conditions,kinetic symmetry-breaking arises spontaneously,i.e.,the symmetric gear keeps rotating in one direction.Unexpectedly,such ratchet phenomenon does not rely on the direct many-particle interactions and moreover the introduction of alignment interaction would counterintuitively prevent it from happening!Further investigation reveals that such spontaneous symmetry-breaking phenomenon shares similarities with the equilibrium phase transition of the Ising model.Our results provide new insights and enhance our understanding of the fundamental aspects of active ratchet phenomena.

Fiscal Pressure,Land Finance and Ratchet Effects of House Prices

In this paper,we focus on the issues of local governments’fiscal pressure,land finance and house prices,and systematically analyze how local governments’fiscal pressure and land finance lead to China’s ratcheting up of house prices.The results show that to release the fiscal pressure,local governments tend to increase land revenue and obtain high real estate related revenue by raising house prices.In this sense,the increase of the land transfer price will result in the increase of the cost of real estates,and eventually leading to the increase of house prices.That is to say,local governments’fiscal pressure will not only result in the increase of house prices directly but also consolidate the ratchet effects of house prices.

Biased transportations in a spatially asymmetric system at the nano-scale under thermal noise

Under the theory of ratchet effect for mesoand macro-scale systems, the additional perturbation with a long time correlation and the breaking of spatial inversion symmetry are two main ingredients to bring unidirected transportations. With the help of a simple model system, we show that a spatially asymmetric system of the nano-scale length may induce biased transportations under thermal noise.

A contract theory analysis to fiscal relations between the central and local governments in China

We use a contract theory/mechanism design framework to analyse the fiscal relations and reforms between the central and local governments in China,which are said to have made great contributions to economic growth since the‘economic reform’.First,we present the mechanism(a fiscal incentive contract model),which has created incentives for the development agent(local government),and clarify theoretically how the concept of bao(contract)works.We then comprehend the concept of bisai(contest)within the framework of the yardstick competition between local governments,and review the mechanism which encourages proper information revelation through intergovernmental comparison and competition.Lastly,we make a theoretical comparative analysis on the fiscal system reform(from the fiscal contracting system to the tax sharing system),from the perspective of how much room was left for the‘ratchet effect’in the dynamic relation between the central and local governments,and how it was solved(or mitigated)in the two fiscal systems.

Optomechanical ratchet resonators

We describe an optomechanical ratchet scheme to realize nonreciprocal transmission of a light field, which is based on the bias of the optical cavity’s frequency spectrum caused by mechanical ratchet interactions. This approach to break the time-reversal symmetry of light propagation is universally valid in various optomechanical systems with ratchet-oscillator structures. We discuss specifically the implementation of an on-chip Casimir-ratchet optomechanical protocol and demonstrate the optical nonreciprocity with an extremely high isolation ratio and flexible controllability, which does not require external additional optical engineering. Our study opens a door for manipulating flexibly light propagation by using mechanical ratchet resonators, and has potential applications in the on-chip integration of nonreciprocal devices and harness of lateral Casimir forces.