The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

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

  • study of discrete test filters and finite difference approximations for the dynamic subgrid scale stress model
    Physics of Fluids, 1996
    Co-Authors: Fady Najjar, Danesh K Tafti
    Abstract:

    This paper investigates the effects of discrete test filters and finite‐difference approximations for large‐eddy simulations using the dynamic subgrid‐scale stress model. Discrete explicit test filters based on finite‐difference formulations have been constructed and the characteristics of their transfer function are studied. Several definitions of the scaling factor are investigated in the context of the discrete test filters. Two test filters, one based on a discrete representation of the top‐hat filter (A), and another based on a high‐order Filtering Operation (C) are evaluated in simulations of the turbulent channel flow at Reτ=180. It is found that filter A calculates a higher turbulent viscosity than filter C, which behaves more like a cutoff filter. For the same test Filtering Operation, the results are found to be sensitive to the ratio of the characteristic lengths of the test and grid filters. By testing two approximations to the convection terms based on second‐order central difference and a no...

  • Study of discrete test filters and finite difference approximations for the dynamic subgrid‐scale stress model
    Physics of Fluids, 1996
    Co-Authors: Fady Najjar, Danesh K Tafti
    Abstract:

    This paper investigates the effects of discrete test filters and finite‐difference approximations for large‐eddy simulations using the dynamic subgrid‐scale stress model. Discrete explicit test filters based on finite‐difference formulations have been constructed and the characteristics of their transfer function are studied. Several definitions of the scaling factor are investigated in the context of the discrete test filters. Two test filters, one based on a discrete representation of the top‐hat filter (A), and another based on a high‐order Filtering Operation (C) are evaluated in simulations of the turbulent channel flow at Reτ=180. It is found that filter A calculates a higher turbulent viscosity than filter C, which behaves more like a cutoff filter. For the same test Filtering Operation, the results are found to be sensitive to the ratio of the characteristic lengths of the test and grid filters. By testing two approximations to the convection terms based on second‐order central difference and a no...

Fady Najjar - One of the best experts on this subject based on the ideXlab platform.

  • study of discrete test filters and finite difference approximations for the dynamic subgrid scale stress model
    Physics of Fluids, 1996
    Co-Authors: Fady Najjar, Danesh K Tafti
    Abstract:

    This paper investigates the effects of discrete test filters and finite‐difference approximations for large‐eddy simulations using the dynamic subgrid‐scale stress model. Discrete explicit test filters based on finite‐difference formulations have been constructed and the characteristics of their transfer function are studied. Several definitions of the scaling factor are investigated in the context of the discrete test filters. Two test filters, one based on a discrete representation of the top‐hat filter (A), and another based on a high‐order Filtering Operation (C) are evaluated in simulations of the turbulent channel flow at Reτ=180. It is found that filter A calculates a higher turbulent viscosity than filter C, which behaves more like a cutoff filter. For the same test Filtering Operation, the results are found to be sensitive to the ratio of the characteristic lengths of the test and grid filters. By testing two approximations to the convection terms based on second‐order central difference and a no...

  • Study of discrete test filters and finite difference approximations for the dynamic subgrid‐scale stress model
    Physics of Fluids, 1996
    Co-Authors: Fady Najjar, Danesh K Tafti
    Abstract:

    This paper investigates the effects of discrete test filters and finite‐difference approximations for large‐eddy simulations using the dynamic subgrid‐scale stress model. Discrete explicit test filters based on finite‐difference formulations have been constructed and the characteristics of their transfer function are studied. Several definitions of the scaling factor are investigated in the context of the discrete test filters. Two test filters, one based on a discrete representation of the top‐hat filter (A), and another based on a high‐order Filtering Operation (C) are evaluated in simulations of the turbulent channel flow at Reτ=180. It is found that filter A calculates a higher turbulent viscosity than filter C, which behaves more like a cutoff filter. For the same test Filtering Operation, the results are found to be sensitive to the ratio of the characteristic lengths of the test and grid filters. By testing two approximations to the convection terms based on second‐order central difference and a no...

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

  • coupled vo2 oscillators circuit as analog first layer filter in convolutional neural networks
    Frontiers in Neuroscience, 2021
    Co-Authors: Elisabetta Corti, Joaquin Antonio Cornejo Jimenez, Kham M Niang, J Robertson, K E Moselund, Bernd Gotsmann, A M Ionescu, S Karg
    Abstract:

    In this work we present an in-memory computing platform based on coupled VO2 oscillators fabricated in a crossbar configuration on silicon. Compared to existing platforms, the crossbar configuration promises significant improvements in terms of area density and oscillation frequency. Further, the crossbar devices exhibit low variability and extended reliability, hence, enabling experiments on 4-coupled oscillator. We demonstrate the neuromorphic computing capabilities using the phase relation of the oscillators. As a application, we propose to replace digital Filtering Operation in a convolutional neural network with oscillating circuits. The concept is tested with a VGG13 architecture on the MNIST dataset, achieving remarkable performances of 95% in the recognition task.

  • coupled vo2 oscillators circuit as analog first layer filter in convolutional neural networks
    arXiv: Emerging Technologies, 2020
    Co-Authors: Elisabetta Corti, Joaquin Antonio Cornejo Jimenez, Kham M Niang, J Robertson, K E Moselund, Bernd Gotsmann, A M Ionescu, S Karg
    Abstract:

    In this work we present an in-memory computing platform based on coupled VO2 oscillators fabricated in a crossbar configuration on silicon. Compared to existing platforms, the crossbar configuration promises significant improvements in terms of area density and oscillation frequency. Further, the crossbar devices exhibit low variability and extended reliability, hence, enabling experiments on 4-coupled oscillator. We demonstrate the neuromorphic computing capabilities using the phase relation of the oscillators. As a application, we propose to replace digital Filtering Operation in a convolutional neural network with oscillating circuits. The concept is tested with a VGG13 architecture on the MNIST dataset, achieving performances of 95% in the recognition task.

Yu Juan-feng - One of the best experts on this subject based on the ideXlab platform.

Baruch Fischer - One of the best experts on this subject based on the ideXlab platform.

  • reconfigurable generation of high repetition rate optical pulse sequences based on time domain phase only Filtering
    Optics Letters, 2005
    Co-Authors: Jose Azana, N K Berger, Boris Levit, Baruch Fischer
    Abstract:

    We propose and demonstrate a fiber-based phase-only Filtering technique for programmable optical pulse shaping, in which the Filtering Operation is implemented in the time domain by means of an electro-optical (EO) phase modulator. The technique has been applied for generating customized ultrahigh-repetition-rate optical pulse sequences (>40GHz) from single input pulses by driving the EO phase modulator with a periodic electronic waveform (RF tone). The generated output pulses are replicas of the input pulse and both the repetition rate and the envelope profile of the generated sequences can be controlled and tuned electronically using this approach.