The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform

Kihong Kim - One of the best experts on this subject based on the ideXlab platform.

  • Excitation of surface waves on the interfaces of general bi-isotropic media
    Optics express, 2016
    Co-Authors: Seulong Kim, Kihong Kim
    Abstract:

    We study theoretically the characteristics of surface waves excited at the interface between a metal and a general bi-isotropic medium, which includes isotropic chiral media and Tellegen media as special cases. We derive an analytical dispersion relation for surface waves, using which we calculate the effective index and the propagation length numerically. We also calculate the absorptance, the cross-polarized reflectance and the spatial distribution of the electromagnetic fields for plane waves incident on a bilayer system consisting of a metal layer and a bi-isotropic layer in the Kretschmann configuration, using the invariant Imbedding Method. The results obtained using the invariant Imbedding Method agree with those obtained from the dispersion relation perfectly. In the case of chiral media, the effective index is an increasing function of the chirality index, whereas in Tellegen media, it is a decreasing function of the Tellegen parameter. The propagation length for surface waves in both cases increase substantially as either the chirality index or the Tellegen parameter increases. In Tellegen media, it diverges to infinity when the effective index goes to zero, whereas in chiral media, it does when the parameters approach the cutoff values where quasi surface waves are excited. We investigate the characteristics of quasi surface waves excited when the chirality index is sufficiently large.

  • Invariant Imbedding theory of wave propagation in stratified anisotropic media
    2016 URSI International Symposium on Electromagnetic Theory (EMTS), 2016
    Co-Authors: Kihong Kim
    Abstract:

    We study wave propagation characteristics in stratified anisotropic media theoretically using the invariant Imbedding Method. We consider the cases where some component of the permittivity tensor is a periodic or random function of a space variable and investigate the photonic band gap structure and the Anderson localization phenomenon. We also consider the case where the tensor component in the longitudinal direction varies from positive to negative values and the associated mode conversion and resonant absorption phenomena.

  • Large enhancement of nonlinear Goos-Hänchen shifts and optical bistability due to surface plasmon excitations
    Journal of the Korean Physical Society, 2015
    Co-Authors: Kihong Kim
    Abstract:

    The Goos-Hänchen shift of p wave beams incident on a metal-nonlinear dielectric bilayer in the Kretschmann configuration is studied theoretically. The reflectance, the phase of the reflection coefficient and the Goos-Hänchen shift are calculated in a numerically precise manner by using the invariant Imbedding Method. The Goos-Hänchen shift has been found to be able to take both extremely large positive and negative values due to surface plasmon excitations and very strong bistability and unique hysteresis phenomena appear. In addition, several previous results on the intensity dependence of the Goos-Hänchen shift are pointed out to be erroneous.

  • Enhanced optical phase conjugation in nonlinear metamaterials.
    Optics express, 2014
    Co-Authors: Kihong Kim
    Abstract:

    Optical phase conjugation by degenerate four-wave mixing in nonlinear metamaterials is studied theoretically by solving the coupled wave equations using a generalized version of the invariant Imbedding Method. The phase-conjugate reflectance and the lateral shift of the phase-conjugate reflected beams are calculated and their dependencies on the frequency, the polarization, the incident angle, the material properties and the structure are investigated in detail. It is found that the efficiency of phase conjugation can be significantly enhanced due to the enhancement of electromagnetic fields in various metamaterial structures.

  • Invariant Imbedding theory for the scattering and absorption of electromagnetic waves by spherical bodies
    Journal of the Korean Physical Society, 2014
    Co-Authors: Sangbum Kim, Kihong Kim
    Abstract:

    We develop an invariant Imbedding Method for the computation of the electromagnetic scattering cross-section from three-dimensional spherical bodies. We demonstrate that we can precisely calculate quantities of interest in the scattering and the absorption of an incident plane wave in various situations, such as propagation through arbitrarily inhomogeneous media and multilayered structures. Examples include scattering by a Luneburg lens and by a spherical cavity enclosed in a spherical photonic crystal structure, the layers of which satisfy the Bragg conditions for the incident wavelengths. In the latter case, light confinement in a very small core with a radius of 1.55 µm with high quality factors at a level of 1.7 × 10^6 could be achieved.

Konstantin V. Koshel - One of the best experts on this subject based on the ideXlab platform.

  • A modification of the invariant Imbedding Method for a singular boundary value problem
    Communications in Nonlinear Science and Numerical Simulation, 2014
    Co-Authors: Konstantin V. Koshel, E. A. Ryzhov, V. N. Zyryanov
    Abstract:

    Abstract We consider a dynamically-consistent analytical model of a 3D topographic vortex. The model is governed by equations derived from the classical problem of the axisymmetric Taylor–Couette flow. Using linear expansions, these equations can be reduced to a differential sixth-order equation with variable coefficients. For this differential equation, we formulate a boundary value problem, which has a number of issues for numerical solving. To avoid these issues and find the eigenvalues and eigenfunctions of the boundary value problem, we suggest a modification of the invariant Imbedding Method (the Riccati equation Method). In this paper, we show that such a modification is necessary since the boundary conditions possess singular matrices, which sufficiently complicate the derivation of the Riccati equation. We suggest algebraic manipulations, which permit the initial problem to be reduced to a problem with regular boundary conditions. Also, we propose a Method for obtaining a numerical solution of the matrix Riccati equation by means of recurrence relations, which allow us to obtain a matrizer converging to the required eigenfunction. The suggested Method is tested by calculating the corresponding eigenvalues and eigenfunctions, and then, by constructing fluid particle trajectories on the basis of the eigenfunctions.

  • Influence of layer and anisotropic fluctuations of the refractive index on the beyond-the-horizon SHF propagation in the troposphere over the sea when there is an evaporation duct
    Atmospheric Propagation and Remote Sensing II, 1993
    Co-Authors: Konstantin V. Koshel, A. A. Shishkarev
    Abstract:

    On the basis of invariant Imbedding Method the disturbance theory for complex constants of the propagation is proposed. This approach allowed us to consider influence of layer and anisotropic fluctuations of refractive index on the beyond-the-horizon propagation in the adiabatic approximation at the existence of the evaporation duct. Finally, the paper considers some examples of the calculations and investigates stochastic effects.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

  • Influence of layer and anisotropic fluctuations of the refractive index on the beyond-the-horizon SHF propagation in the troposphere over the sea when there is an evaporation duct
    Waves in Random Media, 1993
    Co-Authors: Konstantin V. Koshel, A. A. Shishkarev
    Abstract:

    Abstract On the basis of the invariant Imbedding Method the disturbance theory for complex constants of propagation is proposed. This approach allows us to consider the influence of layer and anisotropic fluctuations of refractive index on the beyond-the-horizon propagation in the adiabatic approximation with the existence of an evaporation duct. Finally, the authors consider some examples of the calculations and investigate stochastic effects connected with the interaction between fluctuating and regular waveguides.

  • Application of invariant Imbedding Method to simulate numerically beyond-the-horizon propagation of SHF over the sea
    Atmospheric Propagation and Remote Sensing, 1992
    Co-Authors: Konstantin V. Koshel
    Abstract:

    The present paper studies beyond-the-horizon propagation ot SEF in evaporation d.uct in presence or strong anisotropic fluctuations or the refractivity index. Errective technique to obtain numerically complex eigen values is suggested. On the base or this approach the modeling Method. or SHF propagation in media with layer fluctuations o rerracti vity index is formed. Some examples or the influence oI'! fluctuations on beyond-the-horizon propagation are considers. A generalization or adia batic approximation ror opening systems with complex spectrum o eigen values and indefinite eigen runctions is suggested. Mechanism o exiting the evaporation duct by the high located SElF source is also discussed.

  • Application of invariant Imbedding Method to simulate numerically beyond-the-horizon propagation of SHF over the sea
    Journal of Electromagnetic Waves and Applications, 1992
    Co-Authors: Konstantin V. Koshel
    Abstract:

    The present paper studies beyond-the-horizon propagation of SHF in an evapo­ ration duct in the presence of strong anisotropic fluctuations of the refractivity index. An effective technique to obtain numerically complex constants of propagation is suggested. On the basis of this approach, the modelling Method of SHF propagation in media with layer fluctuations of refractivity index is formed. Finally, the paper considers some exam­ ples of the influence of fluctuations on beyond-the-horizon propagation. A generalization of the adiabatic approximation for opening systems with a complex spectrum of eigen­ values and indefinite eigenfunctions is suggested. On this basis of the rough solution obtained for the atmosphere with nonuniformity in the horizontal direction is revised. The mechanism of exiting the evaporation duct by the high-located SHF source is also discussed.

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

  • Quantum rearrangement scattering calculations using the invariant Imbedding Method
    The Journal of Chemical Physics, 1994
    Co-Authors: Yehuda B. Band, I. Tuvi
    Abstract:

    We derive an algorithm to calculate quantum transmission and reflection amplitudes (S‐matrix elements) for rearrangement reactions using the invariant Imbedding Method. Our approach can incorporate closed channels, treat complex potentials (to simulate decay), and can be used within an adiabatic representation (in which derivative coupling terms are present) or within a diabatic representation. The Method can also be used to determine bound‐state energies when only closed channels are present. The Method is demonstrated on a rearrangement problem with two coupled potential surfaces (four channels) as a function of energy in the energy region from the lowest channel threshold through the highest channel threshold.

  • Invariant Imbedding Method for multichannel Schrödinger equations with first derivative coupling
    The Journal of Chemical Physics, 1993
    Co-Authors: Y. B. Band, I. Tuvi
    Abstract:

    We derive and demonstrate an invariant Imbedding Method for calculating the S matrix for scattering problems involving a first derivative term in the Schrodinger equation for the relative motion. This Method can be used directly on scattering problems derived using molecular structure calculations that determine adiabatic potential energies and their derivative coupling matrix elements. A critical discussion of the procedures that transform from an adiabatic to a diabatic representation is presented.

Zonghai Chen - One of the best experts on this subject based on the ideXlab platform.

  • Online state of charge estimation and open circuit voltage hysteresis modeling of LiFePO4 battery using invariant Imbedding Method
    Applied Energy, 2016
    Co-Authors: Guangzhong Dong, Chenbin Zhang, Zonghai Chen
    Abstract:

    The SOC (state-of-charge) of Li-ion (Lithium-ion) battery is an important evaluation index in BMS (battery management system) for EVs (Electric Vehicles) and smart grids. However, the existing special OCV (open circuit voltage) characteristics of LiFePO4 batteries complicate the estimation of SOC. To improve the estimation accuracy and reliability for battery SOC and battery terminal voltage, an online estimation approach for SOC and parameters of a battery based on the IIM (invariant-Imbedding-Method) algorithm has been proposed. Firstly, by using the IIM algorithm, an online parameter identification Method has been established to accurately capture the real-time characteristics of the battery, which include the OCV hysteresis phenomena. Secondly, a dual IIM algorithm is employed to develop a multi-state estimator for SOC of the battery. Note that the parameters of the battery model are updated with the real-time measurements of the battery current and voltage at each sampling interval. Finally, the proposed Method has been verified by a LiFePO4 battery cell under different operating current conditions. Experimental results indicate that the estimation value based on the proposed IIM-based estimator converges to real SOC with an error of ±2%, and the battery model can simulate OCV hysteresis phenomena robustly with high accuracy.

Demetrios L. Antzoulakos - One of the best experts on this subject based on the ideXlab platform.

  • Waiting times for patterns in a sequence of multistate trials
    Journal of Applied Probability, 2001
    Co-Authors: Demetrios L. Antzoulakos
    Abstract:

    Let X n , n ≥ 1 be a sequence of trials taking values in a given set A , let ∊ be a pattern (simple or compound), and let X r ,∊ be a random variable denoting the waiting time for the r th occurrence of ∊. In the present article a finite Markov chain Imbedding Method is developed for the study of X r ,∊ in the case of the non-overlapping and overlapping way of counting runs and patterns. Several extensions and generalizations are also discussed.