24,697 research outputs found
Dynamics of delay induced composite multi-scroll attractor and its application in encryption
This work was supported in part by NSFC (60804040, 61172070), Key Program of Nature Science Foundation of Shaanxi Province (2016ZDJC-01), Innovative Research Team of Shaanxi Province(2013KCT-04), Fok Ying Tong Education Foundation Young Teacher Foundation(111065), Chao Bai was supported by Excellent Ph.D. research fund (310-252071603) at XAUT.Peer reviewedPostprin
Investigation of the Surface Adhesion Phenomena and Mechanism of Gold-Plated Contacts at Superlow Making/Breaking Speed
Surface adhesion phenomena of gold-plated copper contact materials are studied in conditions of nonarc load (5/15/25 V and 0.2/0.5/1 A) and superlow speed (25 and 50 nm/s) realized by a piezoactuator during the making and breaking processes. It is shown that softening and melting of local asperities leads to interface adhesion, which results from the joule heat generated by the contact resistance; it is determined that the change of contact force with time obeys the negative exponential distribution and the time constant is associated with the adhesion force directly. Based on the fitting experimental data, the relationship between the adhesion force F z and the contact resistance R d while breaking can be expressed as F z ∝ R d -1 , which indicates that the main component of contact resistance is the bulk resistance of weld nugget and the constriction resistance is negligible
High Chern number quantum anomalous Hall phases in graphene ribbons with Haldane orbital coupling
We investigate possible phase transitions among the different quantum
anomalous Hall (QAH) phases in a zigzag graphene ribbon under the influence of
the exchange field. The effective tight-binding Hamiltonian for graphene is
made up of the hopping term, the Kane-Mele and Rashba spin-orbit couplings as
well as the Haldane orbital term. We find that the variation of the exchange
field results in bulk gap-closing phenomena and phase transitions occur in the
graphene system. If the Haldane orbital coupling is absent, the phase
transition between the chiral (anti-chiral) edge state () and
the pseudo-quantum spin Hall state () takes place. Surprisingly, when
the Haldane orbital coupling is taken into account, an intermediate QSH phase
with two additional edge modes appears in between phases and .
This intermediate phase is therefore either the hyper-chiral edge state of high
Chern number or anti-hyper-chiral edge state of when the
direction of exchange field is reversed. We present the band structures, edge
state wave functions and current distributions of the different QAH phases in
the system. We also report the critical exchange field values for the QAH phase
transitions.Comment: 4 figure
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