4,309 research outputs found

    Investigations of Section Speed on Rural Roads in Podlaskie Voivodeship

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    © Published under licence by IOP Publishing Ltd. Excessive speed is one of the most important factors considered in road safety and not only affects the severity of a crash but is also related to the risk of being involved in a crash. In Poland the problem of speeding drivers is widely common. Properly recognized and defined drivers behaviour is the base for any effective activities taken towards road safety improvements. Effective enforcement of speed limits especially on rural road plays an important role but conducted speed investigations basically focus on spot speed omitting travel speed on longer sections of roads which can better reflect driver's behaviour. Possible solutions for rural roads are limited to administrative means of speed limitations, installations of speed cameras and police enforcement. However due to their limited proved effectiveness new solutions are still being sought. High expectations are associated with the sectional speed system that has recently been introduced in Poland and covered a number of national road sections. The aim of this paper is to investigate section speed on chosen regional and district roads located in Podlaskie Voivodeship. Test sections included 19 road segments varied in terms of functional and geometric characteristics. Speed measurements on regional and district roads were performed with the use of a set of two ANPR (Automatic Number Plate Recognition) cameras. Conducted research allowed to compare driver's behaviour in terms of travel speed depending on roads' functional classification as well as to evaluate the influence of chosen geometric parameters on average section speed

    Metamaterial-Inspired Efficient Electrically Small Antenna

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    Abstract—Planar two-dimensional (2D) and volumetric threedimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic-based EZ antennas are shown to be naturally matched to a 50 source, i.e., without the introduction of a matching network. It is demonstrated numerically that these EZ antennas have high radiation efficiencies with very good impedance matching between the source and the antenna and, hence, that they have high overall efficiencies. The reported 2D and 3D EZ antenna designs are linearly scalable to a wide range of frequencies and yet maintain their easy-to-build characteristics. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions. The EZ antennas systems may provide attractive alternatives to existing electrically-small antennas. Index Terms—Antenna efficiency, antennas, electrically small antenna (ESA), metamaterials. I

    Chairs' welcome

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    Microwave whirlpools in a rectangular-waveguide cavity with a thin ferrite disk

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    We study a three dimensional system of a rectangular-waveguide resonator with an inserted thin ferrite disk. The interplay of reflection and transmission at the disk interfaces together with material gyrotropy effect, gives rise to a rich variety of wave phenomena. We analyze the wave propagation based on full Maxwell-equation numerical solutions of the problem. We show that the power-flow lines of the microwave-cavity field interacting with a ferrite disk, in the proximity of its ferromagnetic resonance, form whirlpool-like electromagnetic vortices. Such vortices are characterized by the dynamical symmetry breaking. The role of ohmic losses in waveguide walls and dielectric and magnetic losses in a disk is a subject of our investigations

    On the Localization of One-Photon States

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    Single photon states with arbitrarily fast asymptotic power-law fall-off of energy density and photodetection rate are explicitly constructed. This goes beyond the recently discovered tenth power-law of the Hellwarth-Nouchi photon which itself superseded the long-standing seventh power-law of the Amrein photon.Comment: 7 pages, tex, no figure

    Cylindrical active coated nano-particles excited by electric and magnetic line sources

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    Cylindrical active coated nano-particles comprised of a silica nano-cylinder core covered with a plasmonic nano-shell are investigated with regard to their near- and far-field properties. The source of excitation is taken to be an electric or a magnetic line current, while three different plasmonic materials are employed for the nano-shells, namely silver, gold and copper. © 2011 EurAAP

    Numerical Study of the Near-Field and Far-Field Properties of Active Open Cylindrical Coated Nanoparticle Antennas

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    A very electrically small, active open cylindrical coated nanoparticle model is constructed, and its electromagnetic properties are investigated in the visible frequency band. Its optical response under both planewave and electric dipole antenna excitations shows very strong dipole behavior at its lowest resonance frequency. The scattering cross section at that dipole resonance frequency is increased by more than +50 dBsm for the planewave excitation. When the open structure is excited by a small current (I0 = 1 × 10−3 A) driven dipole antenna, the maximum radiated power of the composite nanoantenna can be increased by +83.35 dB over its value obtained when the dipole antenna radiates alone in free space. The behaviors under various locations and orientations of the dipole are explored. Dipole orientations along the cylinder axis and symmetric locations of the dipole produced the largest radiated power enhancements. © 2011, IEEE. All rights reserved

    Detailed performance characteristics of vertically polarized, cylindrical, active coated nano-particle antennas

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    The electromagnetic properties of active cylindrical coated nano-particle antennas are investigated. It is demonstrated that the active cylindrical coated nano-particle, whether illuminated by a plane wave or an electric Hertzian dipole (EHD) (small current) element, acts as a strong dipole radiator at its resonant frequency. It is shown that the plane wave scattering cross section could be increased by about 40 dBsm, and the maximum peak of the power radiated by an EHD element could be increased more than 65 dB in the presence of the active nano-particle over its value when radiating into free space. An array, constructed with four active cylindrical coated nano-particles and excited by an EHD element located at or near its center is also studied. Large directivity values, more than 8 dB, are obtained for particular array configurations and EHD locations. © 2012 by the American Geophysical Union

    Induction theorem analysis of resonant nanoparticles: Design of a huygens source nanoparticle laser

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    © 2014 American Physical Society. We propose an advanced formulation of standard antenna theory for the basic investigation and design of resonant nanoparticles. This methodology is based on transforming the original scattering problem into a radiation configuration by invoking the induction theorem. Then applying basic antenna theory principles, such as the suppression of any reactive power, the properties of the resonances are engineered. This nanoantenna approach has been validated by revisiting a number of well-known multilayered core-shell structures. It provides additional important physical insights into how the core-shell structures operate and it enables combinations of different resonant phenomena associated with them, e.g., plasmonic and high-Ï resonances, in an intuitive manner. Its efficacy is demonstrated by designing a multilayered nanoparticle that achieves lasing with a maximum directivity in the forward direction and a null in the backward direction, i.e., a Huygens source nanoparticle laser
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