2,919 research outputs found

    The range of the tangential Cauchy-Riemann system on a CR embedded manifold

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    We prove that every compact, pseudoconvex, orientable, CR manifold of \C^n, bounds a complex manifold in the C∞C^\infty sense. In particular, the tangential Cauchy-Riemann system has closed range

    Sampling Distributions of Random Electromagnetic Fields in Mesoscopic or Dynamical Systems

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    We derive the sampling probability density function (pdf) of an ideal localized random electromagnetic field, its amplitude and intensity in an electromagnetic environment that is quasi-statically time-varying statistically homogeneous or static statistically inhomogeneous. The results allow for the estimation of field statistics and confidence intervals when a single spatial or temporal stochastic process produces randomization of the field. Results for both coherent and incoherent detection techniques are derived, for Cartesian, planar and full-vectorial fields. We show that the functional form of the sampling pdf depends on whether the random variable is dimensioned (e.g., the sampled electric field proper) or is expressed in dimensionless standardized or normalized form (e.g., the sampled electric field divided by its sampled standard deviation). For dimensioned quantities, the electric field, its amplitude and intensity exhibit different types of Bessel KK sampling pdfs, which differ significantly from the asymptotic Gauss normal and χ2p(2)\chi^{(2)}_{2p} ensemble pdfs when ν\nu is relatively small. By contrast, for the corresponding standardized quantities, Student tt, Fisher-Snedecor FF and root-FF sampling pdfs are obtained that exhibit heavier tails than comparable Bessel KK pdfs. Statistical uncertainties obtained from classical small-sample theory for dimensionless quantities are shown to be overestimated compared to dimensioned quantities. Differences in the sampling pdfs arising from de-normalization versus de-standardization are obtained.Comment: 12 pages, 15 figures, accepted for publication in Phys. Rev. E, minor typos correcte

    Toward an intelligent high frequency AC distributed power system - Part II: Analytical modelling and experimental realization

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    High frequency AC (HFAC) distributed power systems (DPS), where electric power is delivered at up to multi-kHz via cables, is an alternative means to conventional centralized power systems. This paper explores the means by which real-time information can be achieved without installing additional physical communication channels on an existing 50 kHz current-fed HFAC DPS in lighting applications. A communication protocol is methodologically developed to facilitate robust and efficient inter-device real-time communication. In addition, analytical modelling for the current fed coupling circuit is presented. The utility of an intelligent HFAC DPS is demonstrated by experimental results from comprehensive circuit level implementation. Copyright © 2016 Praise Worthy Prize - All rights reserved

    KINEMATIC CHARACTERISTICS OF LOWER EXTREMITY DURING 5OM BREATHHOLD OF FIN SWIMMING

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    The purpose of this study was to determine the kinematic Characteristic of the lower extremity as well as the mono-fin during short distance fin swimming in Chinese fin swimmers. Eight Chinese fin swimmers were asked to perform 50m while holding the breath at maximum effort for three trials. One cycle of fin swimming motion at midway was videotaped. Two-dimensional analysis methods were employed to analyse the movement of fin swimrning. The vertical velocity and vertical acceleration of the fin tail, average velocity oftotal body centre of mass (COM), angular velocity of the thigh, and angular velocity of the shank were calculated and normalised for one cycle of fin swimming. Results showed that the peak value of horizontal velocity of the total body COM occurred when the fin tail reached its maximum downward velocity

    Structural Color Printing Based on Plasmonic Metasurfaces of Perfect Light Absorption

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    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage

    Kaluza-Klein towers for real vector fields in flat space

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    We consider a free real vector field propagating in a five dimensional flat space with its fifth dimension compactified either on a strip or on a circle and perform a Kalaza Klein reduction which breaks SO(4,1) invariance while reserving SO(3,1) invariance. Taking into account the Lorenz gauge condition, we obtain from the most general hermiticity conditions for the relevant operators all the allowed boundary conditions which have to be imposed on the fields in the extra-dimension. The physical Kaluza-Klein mass towers, which result in a four-dimensional brane, are determined in the different distinct allowed cases. They depend on the bulk mass, on the parameters of the boundary conditions and on the extra parameter present in the Lagrangian. In general, they involve vector states together with accompanying scalar states.Comment: 28 pages, 4 independent table
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