2,919 research outputs found
The range of the tangential Cauchy-Riemann system on a CR embedded manifold
We prove that every compact, pseudoconvex, orientable, CR manifold of \C^n,
bounds a complex manifold in the sense. In particular, the
tangential Cauchy-Riemann system has closed range
Sampling Distributions of Random Electromagnetic Fields in Mesoscopic or Dynamical Systems
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 sampling pdfs, which differ significantly from the asymptotic
Gauss normal and ensemble pdfs when is relatively
small. By contrast, for the corresponding standardized quantities, Student ,
Fisher-Snedecor and root- sampling pdfs are obtained that exhibit
heavier tails than comparable Bessel 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
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.
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KINEMATIC CHARACTERISTICS OF LOWER EXTREMITY DURING 5OM BREATHHOLD OF FIN SWIMMING
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
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
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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