The Experts below are selected from a list of 7893 Experts worldwide ranked by ideXlab platform

R Pierre - One of the best experts on this subject based on the ideXlab platform.

  • high order finite element methods for the computation of bending loss in optical waveguides
    Journal of Lightwave Technology, 2007
    Co-Authors: R Jedidi, R Pierre
    Abstract:

    The purpose of this paper is to develop high-order vectorial finite-element methods to characterize the bending loss in optical waveguides. In order to avoid the use of approximate models based on equivalent refraction index or conformal mapping, the fully vectorial Maxwell system is expressed in a general Orthogonal Coordinate system. Boundary reflections are circumvented by a proper adaptation of the perfectly matched layer technique. Application to bent rib optical waveguides in cylindrical Coordinates and bent circular fiber in toroidal Coordinates is presented. In the latter case, a suitable family of quadrangular finite elements has been developed and was shown to give interesting results, both in that situation and in the Cartesian Coordinate situation.

Reinhold Pregla - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of optical waveguide structures with general anisotropy in arbitrary Orthogonal Coordinate systems
    IEEE Journal of Selected Topics in Quantum Electronics, 2002
    Co-Authors: Reinhold Pregla
    Abstract:

    An extended algorithm for the analysis of arbitrary waveguide structures with general anisotropic materials is proposed and substantiated. This algorithm is based on generalized transmission line (GTL) equations which are developed here for numerical algorithms. For the purpose of analysis, a general modal matrix for the discretized transverse electric and magnetic fields is calculated. Furthermore, impedance/admittance transformation formulas are developed with the help of the GTL equations for longitudinal sections. The proposed algorithm is verified by numerical results.

J I Yanchao - One of the best experts on this subject based on the ideXlab platform.

  • a simple control method of active power filter in synchronous rotating reference Orthogonal Coordinate system
    Power system technology, 2006
    Co-Authors: J I Yanchao
    Abstract:

    A simple control method of voltage source shunt active power filters is proposed in the synchronous rotating reference Orthogonal Coordinate system. By use of d-q transformation, in this control method a three phase AC system is transformed into rotating Orthogonal Coordinate system and under the transformed Coordinate system the compensating current of active power filter is controlled by PI controller to make it trace the reference current. Using the proposed control method, the control system need not to be decoupled and the system voltage fluctuation can be well controlled by only a d-q transformation module and a low-pass filter, so this method is simple and the control strategy possesses good robustness. The correctness of theoretical analysis and the feasibility of the proposed control system are verified by simulation experiments.

R Jedidi - One of the best experts on this subject based on the ideXlab platform.

  • high order finite element methods for the computation of bending loss in optical waveguides
    Journal of Lightwave Technology, 2007
    Co-Authors: R Jedidi, R Pierre
    Abstract:

    The purpose of this paper is to develop high-order vectorial finite-element methods to characterize the bending loss in optical waveguides. In order to avoid the use of approximate models based on equivalent refraction index or conformal mapping, the fully vectorial Maxwell system is expressed in a general Orthogonal Coordinate system. Boundary reflections are circumvented by a proper adaptation of the perfectly matched layer technique. Application to bent rib optical waveguides in cylindrical Coordinates and bent circular fiber in toroidal Coordinates is presented. In the latter case, a suitable family of quadrangular finite elements has been developed and was shown to give interesting results, both in that situation and in the Cartesian Coordinate situation.

J. A. Tataronis - One of the best experts on this subject based on the ideXlab platform.

  • Conditions for existence of Orthogonal Coordinate systems oriented by magnetic field lines
    Journal of Geophysical Research, 2000
    Co-Authors: Anna Salat, J. A. Tataronis
    Abstract:

    In the study of Alfven waves and resonances in the magnetospheres of the Earth and other celestial bodies, Orthogonal, magnetic-field-aligned Coordinates (OF Coordinates) are widely used. Two of the Coordinates are constant on field lines, and the direction of the third is parallel to the direction of the ambient magnetic field. In dipolar fields or in nondipolar but still purely meridional axisymmetric fields the existence of such Coordinates is evident. OF Coordinates, however, are also used occasionally in magnetospheric configurations of more general “nontrivial” geometry where their existence is far from obvious. In the present paper it is proved that magnetic field configurations cannot support OF Coordinates wherever local shear of the magnetic field lines is present. The previously known condition that no field-aligned currents must exist further restricts the admissible geometry of the magnetic field. If the geometry is axisymmetric, a purely meridional or a purely azimuthal magnetic field is the only remaining OF compatible configuration. Therefore publications in which OF Coordinates are used together with “nontrivial” magnetic field configurations need a critical reassessment.