82 research outputs found
Modelling the Selection of Waiting Areas on Subway Platforms Based on the Bacterial Chemotaxis Algorithm
Based on the bacterial chemotaxis algorithm, a new waiting-area selection model (WASM) is proposed that predicts well the pedestrian distribution in subway waiting areas. WASM regards passengers waiting on a subway platform as two-dimensional points and adopts an essential rejection factor to determine the target waiting area. Based on WASM, three experiments were carried out to explore how passenger volume, waiting-area capacity, and staircase position affect the number and distribution of waiting passengers. The experimental results show the following. 1) Regardless of the passenger flow, passengers prefer waiting areas that are between the stairs. 2) Setting proper capacity limits on waiting areas can help to improve subway transportation efficiency when passenger flow is relatively high. 3) The experimental results show that the closer the staircases, the more passengers are left stranded on the platform
Enhancement of the Fractional Quantum Hall State in a Small In-Plane Magnetic Field
Using a 50-nm width, ultra-clean GaAs/AlGaAs quantum well, we have studied
the Landau level filling factor fractional quantum Hall effect in a
perpendicular magnetic field 1.7 T and determined its dependence on
tilted magnetic fields. Contrary to all previous results, the 5/2 resistance
minimum and the Hall plateau are found to strengthen continuously under an
increasing tilt angle (corresponding to an in-plane
magnetic field 0 T). In the same range of
the activation gaps of both the 7/3 and the 8/3 states are found to increase
with tilt. The 5/2 state transforms into a compressible Fermi liquid upon tilt
angle , and the composite fermion series [2+],
1, 2 can be identified. Based on our results, we discuss the relevance of
a Skyrmion spin texture at associated with small Zeeman energy in
wide quantum wells, as proposed by Wjs ., Phys. Rev.
Lett. 104, 086801 (2010).Comment: 5+ pages, 3 figures, accepted for by Phy. Rev. Let
Proximity effect at superconducting Sn-Bi2Se3 interface
We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions
down to 250 mK and in different magnetic fields. A number of conductance
anomalies were observed below the superconducting transition temperature of Sn,
including a small gap different from that of Sn, and a zero-bias conductance
peak growing up at lower temperatures. We discussed the possible origins of the
smaller gap and the zero-bias conductance peak. These phenomena support that a
proximity-effect-induced chiral superconducting phase is formed at the
interface between the superconducting Sn and the strong spin-orbit coupling
material Bi2Se3.Comment: 7 pages, 8 figure
Anomalous Cooper pair interference on Bi2Te3 surface
It is believed that the edges of a chiral p-wave superconductor host Majorana
modes, relating to a mysterious type of fermions predicted seven decades ago.
Much attention has been paid to search for p-wave superconductivity in
solid-state systems, including recently those with strong spin-orbit coupling
(SOC). However, smoking-gun experiments are still awaited. In this work, we
have performed phase-sensitive measurements on particularly designed
superconducting quantum interference devices constructing on the surface of
topological insulators Bi2Te3, in such a way that a substantial portion of the
interference loop is built on the proximity-effect-induced superconducting
surface. Two types of Cooper interference patterns have been recognized at low
temperatures. One is s-wave like and is contributed by a zero-phase loop
inhabited in the bulk of Bi2Te3. The other, being identified to relate to the
surface states, is anomalous for that there is a phase shift between the
positive and negative bias current directions. The results support that the
Cooper pairs on the surface of Bi2Te3 have a 2\pi Berry phase which makes the
superconductivity p_x+ip_y-wave-like. Mesoscopic hybrid rings as constructed in
this experiment are presumably arbitrary-phase loops good for studying
topological quantum phenomena.Comment: supplementary material adde
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