Controllable Goos-H\"{a}nchen shifts and spin beam splitter for ballistic electrons in a parabolic quantum well under a uniform magnetic field

The quantum Goos-H\"{a}nchen shift for ballistic electrons is investigated in a parabolic potential well under a uniform vertical magnetic field. It is found that the Goos-H\"{a}nchen shift can be negative as well as positive, and becomes zero at transmission resonances. The beam shift depends not only on the incident energy and incidence angle, but also on the magnetic field and Landau quantum number. Based on these phenomena, we propose an alternative way to realize the spin beam splitter in the proposed spintronic device, which can completely separate spin-up and spin-down electron beams by negative and positive Goos-H\"{a}nchen shifts.Comment: 6 pages, 6 figure

Correcting for the solar wind in pulsar timing observations: the role of simultaneous a nd l ow-frequency observations

The primary goal of the pulsar timing array projects is to detect ultra-low-frequency gravitational waves. The pulsar data sets are affected by numerous noise processes including varying dispersive delays in the interstellar medium and from the solar wind. The solar wind can lead to rapidly changing variations that, with existing telescopes, can be hard to measure and then remove. In this paper we study the possibility of using a low frequency telescope to aid in such correction for the Parkes Pulsar Timing Array (PPTA) and also discuss whether the ultra-wide-bandwidth receiver for the FAST telescope is sufficient to model the solar wind variations. Our key result is that a single wide-bandwidth receiver can be used to model and remove the effect of the solar wind. However, for pulsars that pass close to the Sun such as PSR J1022+1022, the solar wind is so variable that observations at two telescopes separated by a day are insufficient to correct the solar wind effect.Comment: accepted by RA

Bionic Design of the Surface Morphology of Rubber Bush Covered on Driving Drums

Driving drum uses friction force to transfer power in belt conveyor. By means of bionic technology, the surface morphology of driving drum's flexible cladding was researched to increase the frictional traction force in this paper. Taking tree frog and katydid as biological prototypes, the structural features and adhesion mechanisms of their epidermal pad attachment organs were studied. Imitating the shape and structure of the epidermal pads, based on the principle of function bionics, four new surface morphologies of drum’s bush were designed. The behavior of the bionic bush contacting to the belt was simulated with finite element analysis software. The results of contact analysis show that the bionic drum’s bushes can generate embedding and interlocking effect during the contact process. The contact form can be changed from plane or cambered surface contact to meshing contact to enhance the frictional traction of drums. Keywords: Epidermal pad; Surface morphology; Bionic design; Finite element analysis; Frictio