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 r...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.展开更多
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 ...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.展开更多
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 u...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.展开更多
Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface ...Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface inside the devices play an important role in determining the working properties of the devices. By properly arranging device structures, surface charges originated from device fabrication can be exploited to produce a predetermined electric potential in the devices. Based on this fact, two structures that can lead to an asymmetric potential along their nanochannel are proposed for designing strong nonlinear devices. Further studies indicate that Ratchet effect brought by the asymmetric potential results in diode-like current-voltage characteristics of the devices. Through optimizing device parameters, zero threshold voltage can be achieved, which is desired for detecting applications. Moreover, since the devices are at nanoscale, simulation results reveal that used as rectifiers the working frequencies can be up to a few THz.展开更多
基金the Key Research Foundation of the Education Bureau of Hunan Province of China under Grant No.08A015the Natural Science Foundation of Hunan Province of China under Grant No.06JJ2014 and 04JJ40006the National Natural Science Foundation of China under Grant No.10575034
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11702034,11972298,and 11702218)the China Postdoctoral Science Foundation(Grant No.2019M663812)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant Nos.300102129104,3102018zy013,and 3102017jc01003)the Young Talent Fund of University Association for Science and Technology in Shaanxi,China(Grant Nos.20180503 and 20180501).
文摘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.
文摘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.
文摘Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface inside the devices play an important role in determining the working properties of the devices. By properly arranging device structures, surface charges originated from device fabrication can be exploited to produce a predetermined electric potential in the devices. Based on this fact, two structures that can lead to an asymmetric potential along their nanochannel are proposed for designing strong nonlinear devices. Further studies indicate that Ratchet effect brought by the asymmetric potential results in diode-like current-voltage characteristics of the devices. Through optimizing device parameters, zero threshold voltage can be achieved, which is desired for detecting applications. Moreover, since the devices are at nanoscale, simulation results reveal that used as rectifiers the working frequencies can be up to a few THz.
