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Anastasios Sextos - One of the best experts on this subject based on the ideXlab platform.

  • anti symmetric mode excitation and seismic response of base isolated bridges under Asynchronous Input motion
    Soil Dynamics and Earthquake Engineering, 2018
    Co-Authors: Savvas Papadopoulos, Anastasios Sextos
    Abstract:

    Abstract This paper investigates the effect of Asynchronous earthquake ground motion on the transverse response of base-isolated bridges. In this context, the excitation of anti-symmetric modes of vibration under Asynchronous Input is examined and is statistically correlated with characteristic engineering demand parameters. Different ground motion scenarios are considered for various combinations of soil class, wave propagation velocity and loss of correlation patterns among different support motions, using a spectral representation method to generate m-variate, fully non-stationary, EC8 spectrum-compatible ground motion vector processes. It is shown that in the idealised case of the wave passage effect only, the detrimental effects of Asynchronous excitation are concentrated on the very last piers along the direction of the seismic waves. However, when loss of coherency is also taken into account in a more realistic scenario, the impact of spatial variability is significantly more uniformly distributed. Most importantly, the conditional probability of a detrimental increase in an EDP of interest (i.e., pier base bending moments and deck drift) under multi-support excitation given that an anti-symmetric mode is excited is not only uniform but also considerably high. This is a clear evidence that the local increase of seismic demand in the bridge studied is associated with the excitation of the first anti-symmetric mode of vibration.

  • effect of Asynchronous earthquake motion on complex bridges i methodology and Input motion
    Journal of Bridge Engineering, 2008
    Co-Authors: Nicholas J Burdette, Amr S Elnashai, Alessio Lupoi, Anastasios Sextos
    Abstract:

    Based on observed damage patterns from previous earthquakes and a rich history of analytical studies, Asynchronous Input motion has been identified as a major source of unfavorable response for long-span structures, such as bridges. This study is aimed at quantifying the effect of geometric incoherence and wave arrival delay on complex straight and curved bridges using state-of-the-art methodologies and tools. Using fully parametrized computer codes combining expert geotechnical and earthquake structural engineering knowledge, suites of Asynchronous accelerograms are produced for use in inelastic dynamic analysis of the bridge model. Two multi- degree-of-freedom analytical models are analyzed using 2,000 unique synthetic accelerograms with results showing significant response amplification due to Asynchronous Input motion, demonstrating the importance of considering Asynchronous seismic Input in complex, irregular bridge design. The paper, Part 1 of a two-paper investigation, presents the development of the Input motion sets and the modeling and analysis approach employed, concluding with sample results. Detailed results and implications on seismic assessment are presented in the companion paper: Effect of Asynchronous Motion on Complex Bridges. Part II: Results and Implications on Assessment.

Feng Ding - One of the best experts on this subject based on the ideXlab platform.

  • identification of non uniformly sampled data systems with Asynchronous Input and output data
    Journal of The Franklin Institute-engineering and Applied Mathematics, 2017
    Co-Authors: Li Xie, Huizhong Yang, Feng Ding
    Abstract:

    Abstract This paper considers the identification problem of non-uniformly sampled-data (NUSD) systems with Asynchronous Input and output data. By using the lifting technique, the lifted transfer function (L-TF) model of the Asynchronous NUSD systems is derived. Furthermore, an auxiliary model based recursive least squares (AM-RLS) algorithm is developed to directly identify the L-TF model. In order to avoid the causality constraint problem and improve the computational efficiency, a coupled AM-RLS algorithm is proposed to identify the subsystems of the L-TF model. The effectiveness of the proposed identification algorithms is validated by two simulation examples.

Perold W.j. - One of the best experts on this subject based on the ideXlab platform.

  • A single-clock Asynchronous Input COSL set-reset flip-flop and SFQ to voltage state interface
    'Institute of Electrical and Electronics Engineers (IEEE)', 2005
    Co-Authors: Fourie C.j., Perold W.j.
    Abstract:

    Although published research in COSL has stagnated, it remains a useful logic family for interfacing the much faster RSFQ family to hot-logic circuits. COSL has always been plagued by the absence of latches, and previous attempts at implementing such latches were clumsy. A new COSL Set-Reset flip-flop is discussed here, and results shown. This Asynchronous Input latch, which can also be configured as a T flip-flop, can function on a single-phase clock. It was also adapted to convert SFQ output pulses from RSFQ logic circuits to voltage state levels that can be viewed on standard laboratory oscilloscopes. Due to the Asynchronous nature of the Inputs, the RSFQ-COSL converter is also more reliable than earlier DRO-to-COSL elements. © 2005 IEEE.Conference Pape

W J Perold - One of the best experts on this subject based on the ideXlab platform.

  • a single clock Asynchronous Input cosl set reset flip flop and sfq to voltage state interface
    IEEE Transactions on Applied Superconductivity, 2005
    Co-Authors: C J Fourie, W J Perold
    Abstract:

    Although published research in COSL has stagnated, it remains a useful logic family for interfacing the much faster RSFQ family to hot-logic circuits. COSL has always been plagued by the absence of latches, and previous attempts at implementing such latches were clumsy. A new COSL Set-Reset flip-flop is discussed here, and results shown. This Asynchronous Input latch, which can also be configured as a T flip-flop, can function on a single-phase clock. It was also adapted to convert SFQ output pulses from RSFQ logic circuits to voltage state levels that can be viewed on standard laboratory oscilloscopes. Due to the Asynchronous nature of the Inputs, the RSFQ-COSL converter is also more reliable than earlier DRO-to-COSL elements.

Li Xie - One of the best experts on this subject based on the ideXlab platform.

  • identification of non uniformly sampled data systems with Asynchronous Input and output data
    Journal of The Franklin Institute-engineering and Applied Mathematics, 2017
    Co-Authors: Li Xie, Huizhong Yang, Feng Ding
    Abstract:

    Abstract This paper considers the identification problem of non-uniformly sampled-data (NUSD) systems with Asynchronous Input and output data. By using the lifting technique, the lifted transfer function (L-TF) model of the Asynchronous NUSD systems is derived. Furthermore, an auxiliary model based recursive least squares (AM-RLS) algorithm is developed to directly identify the L-TF model. In order to avoid the causality constraint problem and improve the computational efficiency, a coupled AM-RLS algorithm is proposed to identify the subsystems of the L-TF model. The effectiveness of the proposed identification algorithms is validated by two simulation examples.