The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform

K Char - One of the best experts on this subject based on the ideXlab platform.

  • half Integral Constant voltage steps in high tc grain boundary junctions
    Applied Physics Letters, 1993
    Co-Authors: E A Early, Alan F Clark, K Char
    Abstract:

    A novel effect from microwave radiation near 9.3 GHz applied to high‐TcYBa2Cu3O7−δ single grain boundary junctions was observed. In addition to the usual Shapiro steps resulting from the ac Josephson effect, Constant voltage steps with voltages halfway between the voltages of the Shapiro steps were present. The widths of these ‘‘half‐Integral’’ steps were measured as a function of microwave power, and the influence of a magnetic field was investigated. From previous results on high‐Tc grain boundary junctions and a comparison of the results presented here with single‐ and multiple‐junction effects in low‐Tc materials, we conclude that the half‐Integral steps are likely to be a result of grain boundaries being composed of multiple junctions in parallel.

E A Early - One of the best experts on this subject based on the ideXlab platform.

  • half Integral Constant voltage steps in high tc grain boundary junctions
    Applied Physics Letters, 1993
    Co-Authors: E A Early, Alan F Clark, K Char
    Abstract:

    A novel effect from microwave radiation near 9.3 GHz applied to high‐TcYBa2Cu3O7−δ single grain boundary junctions was observed. In addition to the usual Shapiro steps resulting from the ac Josephson effect, Constant voltage steps with voltages halfway between the voltages of the Shapiro steps were present. The widths of these ‘‘half‐Integral’’ steps were measured as a function of microwave power, and the influence of a magnetic field was investigated. From previous results on high‐Tc grain boundary junctions and a comparison of the results presented here with single‐ and multiple‐junction effects in low‐Tc materials, we conclude that the half‐Integral steps are likely to be a result of grain boundaries being composed of multiple junctions in parallel.

Alan F Clark - One of the best experts on this subject based on the ideXlab platform.

  • half Integral Constant voltage steps in high tc grain boundary junctions
    Applied Physics Letters, 1993
    Co-Authors: E A Early, Alan F Clark, K Char
    Abstract:

    A novel effect from microwave radiation near 9.3 GHz applied to high‐TcYBa2Cu3O7−δ single grain boundary junctions was observed. In addition to the usual Shapiro steps resulting from the ac Josephson effect, Constant voltage steps with voltages halfway between the voltages of the Shapiro steps were present. The widths of these ‘‘half‐Integral’’ steps were measured as a function of microwave power, and the influence of a magnetic field was investigated. From previous results on high‐Tc grain boundary junctions and a comparison of the results presented here with single‐ and multiple‐junction effects in low‐Tc materials, we conclude that the half‐Integral steps are likely to be a result of grain boundaries being composed of multiple junctions in parallel.

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

  • tuning pid and pi λ d δ controllers using the Integral time absolute error criterion
    International Conference on Information and Automation, 2008
    Co-Authors: Deepyaman Maiti, Ayan Acharya, Mithun Chakraborty, Amit Konar, R Janarthanan
    Abstract:

    Particle swarm optimization (PSO) is extensively used for real parameter optimization in diverse fields of study. This paper describes an application of PSO to the problem of designing a fractional-order proportional-Integral-derivative (PIlambdaDdelta) controller whose parameters comprise proportionality Constant, Integral Constant, derivative Constant, Integral order (lambda) and derivative order (delta). The presence of five optimizable parameters makes the task of designing a PIiquestDiquest controller more challenging than conventional PID controller design. Our design method focuses on minimizing the Integral time absolute error (ITAE) criterion. The digital realization of the deigned system utilizes the Tustin operator-based continued fraction expansion scheme. We carry out a simulation that illustrates the effectiveness of the proposed approach especially for realizing fractional-order plants. This paper also attempts to study the behavior of fractional PID controller vis-a-vis that of its integer-order counterpart and demonstrates the superiority of the former to the latter.

  • tuning pid and fopid controllers using the Integral time absolute error criterion
    arXiv: Other Computer Science, 2008
    Co-Authors: Deepyaman Maiti, Ayan Acharya, Mithun Chakraborty, Amit Konar, R Janarthanan
    Abstract:

    Particle swarm optimization (PSO) is extensively used for real parameter optimization in diverse fields of study. This paper describes an application of PSO to the problem of designing a fractional-order proportional-Integral-derivative (FOPID) controller whose parameters comprise proportionality Constant, Integral Constant, derivative Constant, Integral order (lambda) and derivative order (delta). The presence of five optimizable parameters makes the task of designing a FOPID controller more challenging than conventional PID controller design. Our design method focuses on minimizing the Integral Time Absolute Error (ITAE) criterion. The digital realization of the deigned system utilizes the Tustin operator-based continued fraction expansion scheme. We carry out a simulation that illustrates the effectiveness of the proposed approach especially for realizing fractional-order plants. This paper also attempts to study the behavior of fractional PID controller vis-a-vis that of its integer order counterpart and demonstrates the superiority of the former to the latter.

S W Wang - One of the best experts on this subject based on the ideXlab platform.

  • the origin of the half Integral Constant voltage steps in high tc grain boundary junction
    Physica C-superconductivity and Its Applications, 1995
    Co-Authors: H M Cho, S W Wang
    Abstract:

    Abstract Half-Integral Constant voltage steps have been observed recently on the I - V curve of the high- T c grain-boundary junctions in the low-frequency regime. Instead of the nonsinusoidal current phase relationship across the Josephson junction, we propose a phenomenological model that can satisfactorily explain the appearance of half-Integral Constant voltage steps. We regard the junction as being comprised of superconducting microbridges separated by normal regions. Those normal regions and current leakage might cause the junction to trap the magnetic flux and induce a circulating current. The results of numerical simulations, based on the model mentioned above, are in agreement with the I - V characteristics of the RF biased grain-boundary junctions. Moreover, we have made a detailed comparison of the numerical and experimental data for the microwave power dependence of the half-Integral steps.