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[Keyword] saddle(8hit)

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  • Method for Estimating Scatterer Information from the Response Waveform of a Backward Transient Scattering Field Using TD-SPT Open Access

    Keiji GOTO  Toru KAWANO  Munetoshi IWAKIRI  Tsubasa KAWAKAMI  Kazuki NAKAZAWA  

     
    PAPER-Electromagnetic Theory

      Pubricized:
    2024/01/23
      Vol:
    E107-C No:8
      Page(s):
    210-222

    This paper proposes a scatterer information estimation method using numerical data for the response waveform of a backward transient scattering field for both E- and H-polarizations when a two-dimensional (2-D) coated metal cylinder is selected as a scatterer. It is assumed that a line source and an observation point are placed at different locations. The four types of scatterer information covered in this paper are the relative permittivity of a surrounding medium, the relative permittivity of a coating medium layer and its thickness, and the radius of a coated metal cylinder. Specifically, a time-domain saddle-point technique (TD-SPT) is used to derive scatterer information estimation formulae from the amplitude intensity ratios (AIRs) of adjacent backward transient scattering field components. The estimates are obtained by substituting the numerical data of the response waveforms of the backward transient scattering field components into the estimation formulae and performing iterative calculations. Furthermore, a minimum thickness of a coating medium layer for which the estimation method is valid is derived, and two kinds of applicable conditions for the estimation method are proposed. The effectiveness of the scatterer information estimation method is verified by comparing the estimates with the set values. The noise tolerance and convergence characteristics of the estimation method and the method of controlling the estimation accuracy are also discussed.

  • A Subspace Newton-Type Method for Approximating Transversely Repelling Chaotic Saddles

    Hidetaka ITO  Hiroomi HIKAWA  Yutaka MAEDA  

     
    LETTER-Nonlinear Problems

      Vol:
    E101-A No:7
      Page(s):
    1127-1131

    This letter proposes a numerical method for approximating the location of and dynamics on a class of chaotic saddles. In contrast to the conventional strategy of maximizing the escape time, our proposal is to impose a zero-expansion condition along transversely repelling directions of chaotic saddles. This strategy exploits the existence of skeleton-forming unstable periodic orbits embedded in chaotic saddles, and thus can be conveniently implemented as a variant of subspace Newton-type methods. The algorithm is examined through an illustrative and another standard example.

  • Transitional Dynamics and Quasi-Periodic Solution Observed in Two Asymmetrical Coupled Oscillators

    Kuniyasu SHIMIZU  Tetsuro ENDO  Takuya YOSHIMURA  

     
    PAPER-Nonlinear Problems

      Vol:
    E92-A No:1
      Page(s):
    270-278

    In this paper, we investigate the transitional dynamics and quasi-periodic solution appearing after the Saddle-Node (SN) bifurcation of a periodic solution in an inductor-coupled asymmetrical van der Pol oscillators with hard-type nonlinearity. In particular, we elucidate, by investigating global bifurcation of unstable manifold (UM) of saddles, that transitional dynamics and quasi-periodic solution after the SN bifurcation appear based on different structure of UM.

  • Device Design of SONOS Flash Memory Cell with Saddle Type Channel Structure

    Han-A-Reum JUNG  Kyoung-Rok HAN  Young-Min KIM  Jong-Ho LEE  

     
    PAPER

      Vol:
    E91-C No:5
      Page(s):
    736-741

    A new SONOS flash memory device with recess channel and side-gate was proposed and designed in terms of recess depth, doping profile, and side-gate length for sub-40 nm flash memory technology. The key features of the devices were characterized through 3-dimensional device simulation. This cell structure can store 2 or more bits of data in a cell when it is applied to NOR flash memory. It was shown that channel doping profile is very important depending on NOR or NAND applications. In NOR flash memory application, the localized channel doping under the source/drain junction is very important in designing threshold voltage (Vth) and suppression of drain induced barrier lowering (DIBL). In our work, this cell structure is studied not only for NAND flash memory application but also for NOR flash application. The device design was performed in terms of electrical characteristics (Vth, DIBL and SS) by considering device structure and doping profile of the cell.

  • A Uniform Asymptotic Expression for the Function Arising in the Wedge Scattering Problem

    Masao KODAMA  Hideomi TAKAHASHI  Kengo TAIRA  

     
    LETTER-Electromagnetic Theory

      Vol:
    E80-C No:6
      Page(s):
    831-833

    Scattering of a plane electromagnetic wave by a conducting wedge will be discussed. The former solution can not be applicable to all the transition regions when its parameter is constant. This study shows a new solution which consists of only one expression applicable to the shadow region, the illuminated region and the transition regions, and which has no parameter.

  • On Unstable Saddle-Node Connecting Orbit in a Planer Autonomous System

    Tetsushi UETA  Hiroshi KAWAKAMI  

     
    LETTER

      Vol:
    E79-A No:11
      Page(s):
    1844-1847

    We found a novel connecting orbit in the averaged Duffing-Rayleigh equation. The orbit starts from an unstable manifold of a saddle type equilibrium point and reaches to a stable manifold of a node type equilibrium. Although the connecting orbit is structurally stable in terms of the conventional definition of structural stability, it is structually unstable since a one-deimensional manifold into which the connecting orbit flows is unstable. We can consider the orbit is one of global bifurcations governing the differentiability of the closed orbit.

  • Global Dynamic Behaviour of a Parallel Blower System

    Hideaki OKAZAKI  Hideo NAKANO  Takehiko KAWASE  

     
    PAPER-Nonlinear Problems

      Vol:
    E78-A No:6
      Page(s):
    715-726

    A parallel blower system is quite familiar in hydraulic machine systems and quite often employed in many process industries. It is dynamically dual to the fundamental functional element of digital computer, that is, the flip-flop circuit, which was extensively studied by Moser. Although the global dynamic behaviour of such systems has significant bearing upon system operation, no substantial study reports have hitherto been presented. Extensive research concern has primarily been concentrated upon the local stability of the equilibrium point. In the paper, a piecewise linear model is used to analytically and numerically investigate its manifold global dynamic behaviour. To do this, first the Poincar map is defined as a composition boundary map, each of which is defined as the point transformation from the entry point to the end point of any trajectory on some boundary planes. It was already shown that, in some parameter region, the system exhibits the so-called chaotic states. The chaos generating process is investigated using the above Poincar map and it is shown that the map contains the contracting, stretching and folding operations which, as we often see in many cases particularly in horse shoe map, produce the chaotic states. Considering the one dimensional motions of the orbits by such Poincar map, that is, the stretching and folding operations, a one dimensional approximation of the Poincar map is introduced to more closely and exactly study manifold bifurcation processes and some illustrative bifurcation diagrams in relation to system parameters are presented. Thus it is shown how many types of bifurcations like the Hopf, period doubling, saddle node, and homoclinic bifurcations come to exist in the system.

  • Bifurcation Set of a Modelled Parallel Blower System

    Hideaki OKAZAKI  Tomoyuki UWABA  Hideo NAKANO  Takehiko KAWASE  

     
    PAPER

      Vol:
    E76-A No:3
      Page(s):
    299-309

    Global dynamic behavior particularly the bifurcation of periodic orbits of a parallel blower system is studied using a piecewise linear model and the one-dimensional map defined by the Poincare map. First several analytical tools are presented to numerically study the bifurcation process particularly the bifurcation point of the fixed point of the Poincare map. Using two bifurcation diagrams and a bifurcation set, it is shown how periodic orbits bifurcate and leads to chaotic state. It is also shown that the homoclinic bifurcations occur in some parameter regions and that the Li & Yorke conditions of the chaotic state hold in the parameter region which is included in the one where the homoclinic bifurcation occurs. Together with the above, the stable and unstable manifolds of a saddle closed orbit is illustrated and the existence of the homoclinic points is shown.