1,143 research outputs found

    The Role of Web Services at Home

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    The increase in computational power and the networking abilities of home appliances are revolutionizing the way we interact with our homes. This trend is growing stronger and opening a number of technological challenges. From the point of view of distributed systems, there is a need to design architectures for enhancing the comfort and safety of the home, which deal with issues of heterogeneity, scalability and openness. By considering the evolution of domotic research and projects, we advocate a role for web services in the domestic network, and propose an infrastructure based on web services. As a case study, we present an implementation for monitoring the health of an elder adult using multiple sensors and clients

    Goos-Haenchen and Imbert-Fedorov shifts for bounded wave packets of light

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    We present precise expressions of the spatial and angular Goos-Haenchen and Imbert-Fedorov shifts experienced by a longitudinally and transversally limited beam of light (wave packet) upon reflection from a dielectric interface, as opposed to the well-known case of a monochromatic beam which is bounded in transverse directions but infinitely extended along the direction of propagation. This is done under the assumption that the detector time is longer than the temporal length of the wave packet (wave packet regime). Our results will be applied to the case of a Gaussian wave packet and show that, at the leading order in the Taylor expansion of reflected-field amplitudes, the results are the same of the monochromatic case

    Generalized Bessel beams with two indices

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    We report on a new class of exact solutions of the scalar Helmholtz equation obtained by carefully engineering the form of the angular spectrum of a Bessel beam. We consider in particular the case in which the angular spectrum of such generalized beams has, in the paraxial zone, the same radial structure as Laguerre-Gaussian beams. We investigate the form of these new beams as well as their peculiar propagation properties

    Radially and azimuthally polarized non paraxial Bessel beams made simple

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    We present a method for the realization of radially and azimuthally polarized nonparaxial Bessel beams in a rigorous but simple manner. This result is achieved by using the concept of Hertz vector potential to generate exact vector solutions of Maxwell's equations from scalar Bessel beams. The scalar part of the Hertz potential is built by analogy with the paraxial case as a linear combination of Bessel beams carrying a unit of orbital angular momentum. In this way we are able to obtain spatial and polarization patterns analogous to the ones exhibited by the standard cylindrically polarized paraxial beams. Applications of these beams are discussed.Comment: 8 Pages, 4 Figure

    Classical optics representation of the quantum mechanical translation operator via ABCD matrices

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    The ABCD matrix formalism describing paraxial propagation of optical beams across linear systems is generalized to arbitrary beam trajectories. As a by-product of this study, a one-to-one correspondence between the extended ABCD matrix formalism presented here and the quantum mechanical translation operator is established

    Near field of an oscillating electric dipole and cross-polarization of a collimated beam of light: two sides of the same coin

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    We address the question of whether there exists a hidden relationship between the near-field distribution generated by an oscillating electric dipole and the so-called cross polarization of a collimated beam of light. We find that the answer is affirmative by showing that the complex field distributions occurring in both cases have a common physical origin: the requirement that the electromagnetic fields must be transverse