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Interaction of hydrogen atom with (5, 5) single-walled carbon nanotube (SWNT) has been studied over the collision energy range from 1 to 30 eV using a molecular dynamics simulation method. In the energy interval of 1–3 eV, the hydrogen atom can be chemisorbed on the outer wall of the SWNT, provided the impact point is near a vertex carbon atom of a hexagon. The lowest incident energy needed for a hydrogen atom to pass through a hexagon ring on the SWNT is estimated to be 14 eV. Hydrogen atoms that enter into the SWNT would either be encapsulated in it to form endohedral H@tube complex, or escape out of it. The hole on the sidewall of the nanotube induced by the collision of hydrogen atom can be healed after relaxation for several picoseconds.

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The most important feature of a Self-Reconfigurable Robot (SRR) is that it is reconfigurable and self-repairing. At the centre of these capabilities is autonomous docking. One difficulty for docking is the alignment between two robots. Current strategies overcome this by integrating a mechanical guiding device within the connecting mechanism. This increases the robustness of docking but compromises the flexibility of reconfiguration. In this paper, we present a new autonomous docking strategy that can overcome the drawbacks of current approaches. The new strategy uses a novel hook-type connecting mechanism and multi-sensory guidance. The hook-type connecting mechanism is strong and rigid for reliable physical connection between the modules. The multisensory docking strategy, which includes visual-sensorguided rough positioning, Hall-sensor-guided fine positioning, and the locking between moving and target modules, guarantees robust docking without sacrificing reconfigurability. The proposed strategy is verified by docking between a worm-shaped robot and one target module, and docking among three moving robots to form a T-shaped configuration. The experimental results showed that the strategy is very effective.

PACS 72.25.Dc, 73.40.GkThe spin-dependent phase delay time of two-dimensional electrons through a magnetic-electric barrier structure with/without an external electric field has been systematically investigated. The dependence of electron spin polarization on the applied bias, the incident wave vector, the incident electron energy and the height of the electric barrier has been addressed. It is found that the magnetic-electric barrier structure exhibits significant spin polarization under an external electric field, especially for electrons with small energies, where the spin polarization also displays a considerable wave vector-dependent feature.