5,717 research outputs found
Distributed Evaluation and Convergence of Self-Appraisals in Social Networks
We consider in this paper a networked system of opinion dynamics in
continuous time, where the agents are able to evaluate their self-appraisals in
a distributed way. In the model we formulate, the underlying network topology
is described by a rooted digraph. For each ordered pair of agents , we
assign a function of self-appraisal to agent , which measures the level of
importance of agent to agent . Thus, by communicating only with her
neighbors, each agent is able to calculate the difference between her level of
importance to others and others' level of importance to her. The dynamical
system of self-appraisals is then designed to drive these differences to zero.
We show that for almost all initial conditions, the trajectory generated by
this dynamical system asymptotically converges to an equilibrium point which is
exponentially stable
Misalignment diagnosis of a planetary gearbox based on vibration analysis
As a critical power transmission system, planetary gearbox is widely used in many industrial important machines such as wind turbines, aircraft turbine engines, helicopters. Early fault detection and diagnosis of the gearbox will help to prevent unexpected breakdowns of this important equip-ment. Misalignment is one of the major operating problems in the planetary gearbox which may be caused by inadequate system integration, variable operating conditions and differences of elastic deformations in the system. In this paper, the effect of varying degrees of installation misalignment of planetary gearbox are investigated based on vibration measurements using spectrum analysis and modulation signal bispectrum (MSB) analysis. It has shown that the misalignment can be diagnosed in the low frequency range in which the adverse effect due to co-occurrence of amplitude modula-tion and frequency modulation (AM-FM) effect is low compared with the components around meshing frequencies. Moreover, MSB produces a more accurate and reliable diagnosis in that it gives correct indication of the fault severity and location for all operating conditions. In contrast, spectrum can produce correct results for some of the operating conditions. Keywords: Planetary gearbox, Condition Monitoring, Misalignment, Modulation signal bispectrum
Entanglement Property and Monogamy Relation of Gerneralized Mixed W
We introduce a new class of multipartite entangled mixed states with pure
state decompositions of generalized W states, similar to Schmidt-correlated
states having generalized GHZ states in the pure state decomposition. The
entanglement and separability properties are studied according to PPT
operations. Monogamy relations linked to these states are also investigated.Comment: 8 page
Experimental Realization of Entanglement Concentration and A Quantum Repeater
We report an experimental realization of entanglement concentration using two
polarization-entangled photon pairs produced by pulsed parametric
down-conversion. In the meantime, our setup also provides a proof-in-principle
demonstration of a quantum repeater. The quality of our procedure is verified
by observing a violation of Bell's inequality by more than 5 standard
deviations. The high experimental accuracy achieved in the experiment implies
that the requirement of tolerable error rate in multi-stage realization of
quantum repeaters can be fulfilled, hence providing a practical toolbox for
quantum communication over large distances.Comment: 15 pages, 4 figures, submitte
Tunneling Qubit Operation on a Protected Josephson Junction Array
We discuss a protected quantum computation process based on a hexagon
Josephson junction array. Qubits are encoded in the punctured array, which is
topologically protected. The degeneracy is related to the number of holes. The
topological degeneracy is lightly shifted by tuning the flux through specific
hexagons. We also show how to perform single qubit operation and basic quantum
gate operations in this system.Comment: 8 pages, 4 figures. The published version in Phys. Rev.,
A81(2010)01232
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