20,699 research outputs found
A parity-breaking electronic nematic phase transition in the spin-orbit coupled metal CdReO
Strong electron interactions can drive metallic systems toward a variety of
well-known symmetry-broken phases, but the instabilities of correlated metals
with strong spin-orbit coupling have only recently begun to be explored. We
uncovered a multipolar nematic phase of matter in the metallic pyrochlore
CdReO using spatially resolved second-harmonic optical anisotropy
measurements. Like previously discovered electronic nematic phases, this
multipolar phase spontaneously breaks rotational symmetry while preserving
translational invariance. However, it has the distinguishing property of being
odd under spatial inversion, which is allowed only in the presence of
spin-orbit coupling. By examining the critical behavior of the multipolar
nematic order parameter, we show that it drives the thermal phase transition
near 200 kelvin in CdReO and induces a parity-breaking lattice
distortion as a secondary order.Comment: 9 pages main text, 4 figures, 10 pages supplementary informatio
Experimental demonstration of tripartite entanglement and controlled dense coding for continuous variables
A tripartite entangled state of bright optical field is experimentally
produced using an Einstein-Podolsky-Rosen entangled state for continuous
variables and linear optics. The controlled dense coding among a sender, a
receiver and a controller is demonstrated by exploiting the tripartite
entanglement. The obtained three-mode position correlation and relative
momentum correlation between the sender and the receiver and thus the
improvements of the measured signal to noise ratios of amplitude and phase
signals with respect to the shot noise limit are 3.28dB and 3.18dB
respectively. If the mean photon number equals 11 the channel
capacity can be controllably inverted between 2.91 and 3.14. When is
larger than 1.0 and 10.52 the channel capacities of the controlled dense coding
exceed the ideal single channel capacities of coherent and squeezed state light
communication.Comment: 8 pages, 4 figure
Leader-following Consensus Control of a Distributed Linear Multi-agent System using a Sliding Mode Strategy
A distributed leader-following consensus control framework is proposed for a linear system. The linear system is first transformed into a regular form. Then a linear sliding mode is designed to provide high robustness, and the corresponding consensus protocol is proposed in a fully distributed fashion. When matched disturbances are present, it can be demonstrated that the system states reach the sliding mode in finite time and consensus can be achieved asymptotically using Lyapunov theory and the invariant set theorem. Simulation results validate the effectiveness of the proposed algorithm
Leader-following Consensus Control of a Distributed Linear Multi-agent System using a Sliding Mode Strategy
A distributed leader-following consensus control framework is proposed for a linear system. The linear system is first transformed into a regular form. Then a linear sliding mode is designed to provide high robustness, and the corresponding consensus protocol is proposed in a fully distributed fashion. When matched disturbances are present, it can be demonstrated that the system states reach the sliding mode in finite time and consensus can be achieved asymptotically using Lyapunov theory and the invariant set theorem. Simulation results validate the effectiveness of the proposed algorithm
Bayesian Credible Sets for a Binomial Proportion Based on One-Sample Binary Data Subject to One Type of Misclassification
Interval estimation for the proportion parameter in one-sample misclassified binary data has caught much interest in the literature. Recently, an approximate Bayesian approach has been proposed. This approach is simpler to implement and performs better than existing frequentist approaches. However, because a normal approximation to the marginal posterior density was used in the Bayesian approach, some efficiency may be lost. We develop a closed-form fully Bayesian algorithm which draws a posterior sample of the proportion parameter from the exact marginal posterior distribution. We conducted simulations to show that our fully Bayesian algorithm is easier to implement and has better coverage than the approximate Bayesian approach
Exact solution of gyration radius of individual's trajectory for a simplified human mobility model
Gyration radius of individual's trajectory plays a key role in quantifying
human mobility patterns. Of particular interests, empirical analyses suggest
that the growth of gyration radius is slow versus time except the very early
stage and may eventually arrive to a steady value. However, up to now, the
underlying mechanism leading to such a possibly steady value has not been well
understood. In this Letter, we propose a simplified human mobility model to
simulate individual's daily travel with three sequential activities: commuting
to workplace, going to do leisure activities and returning home. With the
assumption that individual has constant travel speed and inferior limit of time
at home and work, we prove that the daily moving area of an individual is an
ellipse, and finally get an exact solution of the gyration radius. The
analytical solution well captures the empirical observation reported in [M. C.
Gonz`alez et al., Nature, 453 (2008) 779]. We also find that, in spite of the
heterogeneous displacement distribution in the population level, individuals in
our model have characteristic displacements, indicating a completely different
mechanism to the one proposed by Song et al. [Nat. Phys. 6 (2010) 818].Comment: 4 pages, 4 figure
Distributed model predictive control for the atmospheric and vacuum distillation towers in a petroleum refining process
This paper develops a distributed model predictive control strategy for the atmospheric and vacuum distillation tower, which constitutes a key process involved in refining petroleum. When considering an MPC implementation, it is known that computational complexity can be reduced if the system is first decomposed into multiple smaller dimensional subsystems. Optimally exploiting the modern computer networks available in industry, a distributed model predictive control implementation is developed for the atmospheric and vacuum tower system, which is assumed to be part of a wider petroleum refining process comprised of a number of sub-systems connected in series. For each subsystem, given the availability of mutual communication channels between subsystems and by using an iterative calculation approach, it will be seen that Nash optimality can be achieved. A low-cost solution that is readily implementable online is seen to achieve the control objective. The effectiveness of the approach presented in the paper is validated by the results of nonlinear simulation experiments
Phase-retrieval algorithm for the characterization of broadband single attosecond pulses
Citation: Zhao, X., Wei, H., Wu, Y., & Lin, C. D. (2017). Phase-retrieval algorithm for the characterization of broadband single attosecond pulses. Physical Review A, 95(4), 8. doi:10.1103/PhysRevA.95.043407Recent progress in high-order harmonic generation with few-cycle mid-infrared wavelength lasers has pushed light pulses into the water-window region and beyond. These pulses have the bandwidth to support single attosecond pulses down to a few tens of attoseconds. However, the present available techniques for attosecond pulse measurement are not applicable to such pulses. Here we report a phase-retrieval method using the standard photoelectron streaking technique where an attosecond pulse is converted into its electron replica through photoionization of atoms in the presence of a time-delayed infrared laser. The iterative algorithm allows accurate reconstruction of the spectral phase of light pulses, from the extreme-ultraviolet (XUV) to soft x-rays, with pulse durations from hundreds down to a few tens of attoseconds. At the same time, the streaking laser fields, including short pulses that span a few octaves, can also be accurately retrieved. Such well-characterized single attosecond pulses in the XUV to the soft-x-ray region are required for time-resolved probing of inner-shell electronic dynamics of matter at their own timescale of a few tens of attoseconds
Faraday Rotation Correction for Passive Microwave Remote Sensing from Space
Faraday rotation (FR) is one of the main error sources for passive microwave remote sensing from space especially in frequencies less than or equal to 10.7 GHz. In this paper, Faraday rotation correction for the vertical brightness temperature at L band and the third Stokes parameter brightness temperature at 10.7 GHz are discussed. Two approaches are studied to remove the influence of FR: correction by auxiliary data and correction by polarimetric mode. At 1.4 GHz, correction by polarimetric mode performs better than correction by auxiliary data. At 10.7 GHz, correction by auxiliary data is feasible while polarimetric mode correction becomes invalid. We propose a new method of using TEC data released by international GNSS service (IGS) for correction. It has been proved that the residual correction errors are reduced. IGS data method greatly improves the correction accuracy
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