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A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltz-mann method with the Galilean-invariant momentum exchange method. The lateral migration and equilibrium of the particle are similar to the Segré-Silberberg effect in our numerical simulations. Surprisingly, two lateral equilibrium positions are observed corresponding to the releasing positions of the biconcave particle. The upper equilibrium positions signiflcantly decrease with the increasing Reynolds number, whereas the lower ones are almost insensitive to the Reynolds number. Interestingly, the regular wave accompanied by nonuniform rotation is exhibited in the lateral movement of the biconcave particle. It can be attributed to the fact that the biconcave shape in various postures interacts with the parabolic velocity distribution of the Poiseuille flow. A set of contours illustrate the dynamic flow field when the biconcave particle has successive postures in a rotating period. [ABSTRACT FROM AUTHOR]

In light of a quantum secure direct communication (QSDC) scheme using entanglement swapping [Chin. Phys. Lett. 22 (2005) 18], by introducing additional local operations for encoding, we propose a bidirectional QSDC (BQSDC) protocol, in which two legitimate users can simultaneously exchange their respective messages. The rule for the users to retrieve his/her partner's messages is derived explicitly in the most general case. Eve's commonly used attack method has been discussed and can be detected with the security checking process. [ABSTRACT FROM AUTHOR]

The complexity of signal controlled traffic largely stems from the various driving behaviors developed in response to the traffic signal. However, the existing models take a few driving behaviors into account and consequently the traffic dynamics has not been completely explored. Therefore, a new cellular automaton model, which incorporates the driving behaviors typically manifesting during the different stages when the vehicles are moving toward a traffic light, is proposed in this paper. Numerical simulations have demonstrated that the proposed model can produce the spontaneous traffic breakdown and the dissolution of the over-saturated traffic phenomena. Furthermore, the simulation results indicate that the slow-to-start behavior and the inch-forward behavior can foster the traffic breakdown. Particularly, it has been discovered that the over-saturated traffic can be revised to be an under-saturated state when the slow-down behavior is activated after the spontaneous breakdown. Finally, the contributions of the driving behaviors on the traffic breakdown have been examined. [ABSTRACT FROM AUTHOR]