Miscibility of Binary Bose-Einstein Condensate Mixture with Competing s- and p-Wave Interaction

Combining two Bose-Einstein condensates(BECs)may result in a miscible or immiscible mixture.In this study,we investigate the miscibility-immiscibility transition of binary BEC mixture trapped in an isotropic harmonic potential,with both inter-species s-wave and p-wave scattering interaction included.The mean-field Gross-Pitaevskii equations with p-wave interaction term are numerically solved to obtain the ground-state phase diagram.Due to the pwave interaction competing with isotropic s-wave interaction,the spatial density profile of binary BEC mixtures transforming from immiscible phase to miscible phase is observed.The p-wave interaction caused miscibility can be observed in current experiments of Bose-Bose mixture tuned near a p-wave Feshbach resonance.

dc Josephson Effect in s-Wave Superconductor/Ferromagnet Insulator/p-Wave Superconductor Junctions

The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor（s/FI/p） junctions are calculated as a function of temperature and the phase taking into account the roughness scattering effect at interface. The phase dependence of the Josephson current I （φ） between s-wave and px-wave superconductor is predicted to be sin（2φ）. The ferromagnet scattering effect, the barrier strength, and the roughness strength at interface suppress the dc currents in s/FI/p junction.

地震纵横波时差耦合作用的斜坡崩滑响应研究

运用离散元数值模拟技术,对北川新中崩滑体在具地域性和空间非均质性的地震纵横波时差耦合作用下产生崩滑破坏的动力全过程进行了研究,确定了该斜坡体在强震动力作用下产生崩滑破坏的形成机制及主控因素。研究表明:①对于新中崩滑体的先期崩滑破坏而言,由于其距离初始震中较远,故源自初始震源的地震纵横波到达该斜坡体的时差较长,为约15.21 s,而该斜坡体在地震纵波作用于斜坡体后8 s后即开始破裂,故其先期崩滑破坏是受到地震纵波产生的水平与竖向拉裂耦合作用所致,并以水平拉裂作用占优,而后期的抛射及运动过程则是受到地震纵横波的耦合作用所致;②对其发生先期崩滑的主控因素言,在地震构造组合机制、岩体结构与构造、斜坡岩体风化程度及物理力学参数等因素既定的情况下,地震纵波产生的水平与竖向拉裂耦合作用是诱发斜坡体产生初期崩滑破坏的主控因素,而斜坡所处地形(如高程差、沟谷延伸方向)则是促使破坏后的斜坡体形成后续碰撞解体及碎屑流等运动过程的控制诱发因素;③该斜坡体动力响应特征值的放大效应表明,其放大系数值从大到小依次是水平加速度>竖向加速度>水平速度>竖向速度,该结果与斜坡体发生先期崩滑破坏的形成机制及主控因素相符合,即地震纵波产生的水平加速度起到了优势破坏作用。以上研究为强震动力作用下的斜坡体先期崩滑破坏提供了新方法。

The Temporal Evolution of Shear-wave Splitting and Geoelectrical Anisotropy During Yongdeng Earthquake

The temporal evolution of shear-wave splitting and geoelectrical anisotropy of earth media during the preparation and occurrence of the Yongdeng MS5.8 earthquake is studied based on the digital seismic data and continuous magnetotelluric (MT) records. The results show that the direction of polarization of the fast S-wave gradually rotated from north by east to north by west before the Yongdeng earthquake and returned to north by east after the earthquake. Moreover, the time delay between the fast S wave and slow S wave increased to the largest until the earthquake occurred. On the other hand, the directions of geoelectrical principal axes also changed before earthquake, and exhibited identical characteristics in the frequency domain. The direction of the axis (pxy), which was originally perpendicular to the fault near station, varied from N17°to N15°before earthquake, and returned to north by east after the earthquake. Correspondingly, the change of pxy was most obvious in the period range of 160 s to 226 s, but the variation of pyx was less obvious. The focal mechanism solution of the earthquake showed that the direction of P-axis was N15°. Conclusions are: (1) The fast S-wave polarization, one of the geoelectrical principal axes and the P-axis were in agreement in orientation during earthquake preparation, which is the result of the alignment of EDA cracks; (2) The fact that the geoelectrical axes identically varied with frequency demonstrated that EDA is really widespread in the crust; (3) The variation of MT apparent resistivity also showed the existence of anisotropy and has its own features: The static anisotropy of resistivity is controlled by the tectonic conditions of the station, while the dynamic anisotropy is caused and affected by the seismic stress field; The resistivity along the axis parallel to the P-axis showed the most obvious variation, while the difference in variation with frequency shows that the variation of resistivity depends not only on direction but also on buried depth.

Three-dimensional velocity structure and tectonic characteristics of earthquake area in Yibin

In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal parameters and three-dimensional(3 D)body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography.Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures,which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region.Velocity structure of P-and S-waves in the Yibin area clearly shows lateral inhomogeneity.The distribution characteristics of the P-and S-waves near the surface are closely related to the geomorphology and geologic structure.The low-velocity anomaly appears at the depth of 15–25 km,which is affected by the lower crust current.The Junlian–Gongxian and Gongxian–Changning earthquake areas,which are the two most earthquake-prone areas in the Yibin region,clearly differ in earthquake distribution and tectonic characteristics.We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3 D bodywave velocity structures in the Yibin region.We found that although most seismicity in the Yibin area is caused by fluid injection,the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure.Fine-scale 3 D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium,seismogenic structure,and seismicity.