The Experts below are selected from a list of 105831 Experts worldwide ranked by ideXlab platform
Paul Terry - One of the best experts on this subject based on the ideXlab platform.
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Numerical Measurement of turbulent responses in drift-Alfvén turbulence
Physics of Plasmas, 1997Co-Authors: Eduardo Fernandez, Paul TerryAbstract:A drift-Alfven magnetoturbulence model that augments reduced magnetohydrodynamics with evolution of electron density under parallel compression and fluid advection has been studied Numerically. In the Alfvenic regime, Measurement of spectral transfer rates, frequency spectra, energy partitions, and the ensemble-averaged turbulent response reveals both Alfvenic and hydrodynamic characteristics. The rms turbulent frequency is Alfvenic, the energies are equipartitioned, and there is a fast, Alfven-time scale relaxation in the turbulent response. The mean frequency is hydrodynamic, with diamagnetic and eddy straining signatures, and there is an eddy straining decorrelation appearing as a distinct, long time scale branch in the turbulent response. The decay rates and relative fluctuation strengths associated with fast and slow time scale decorrelation are in good agreement with theoretical predictions that posit a Kolmogorov spectrum in the Alfvenic regime.
Eduardo Fernandez - One of the best experts on this subject based on the ideXlab platform.
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Numerical Measurement of turbulent responses in drift-Alfvén turbulence
Physics of Plasmas, 1997Co-Authors: Eduardo Fernandez, Paul TerryAbstract:A drift-Alfven magnetoturbulence model that augments reduced magnetohydrodynamics with evolution of electron density under parallel compression and fluid advection has been studied Numerically. In the Alfvenic regime, Measurement of spectral transfer rates, frequency spectra, energy partitions, and the ensemble-averaged turbulent response reveals both Alfvenic and hydrodynamic characteristics. The rms turbulent frequency is Alfvenic, the energies are equipartitioned, and there is a fast, Alfven-time scale relaxation in the turbulent response. The mean frequency is hydrodynamic, with diamagnetic and eddy straining signatures, and there is an eddy straining decorrelation appearing as a distinct, long time scale branch in the turbulent response. The decay rates and relative fluctuation strengths associated with fast and slow time scale decorrelation are in good agreement with theoretical predictions that posit a Kolmogorov spectrum in the Alfvenic regime.
Zuomin Dong - One of the best experts on this subject based on the ideXlab platform.
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load profile based empirical model for the lifetime prediction of an automotive pem fuel cell
International Journal of Hydrogen Energy, 2017Co-Authors: Xinfeng Zhang, Daijun Yang, Minghui Luo, Zuomin DongAbstract:Abstract The prediction of the lifetime of a PEM fuel cell under a specific electrical load profile is beneficial for automotive applications. An empirical lifetime prediction model coupled with an electrical load profile is presented based on an estimate of the degradation rate of the cell voltage. First, a cause and effect chain-based analysis of the PEM fuel cell's degradation process is presented. Second, a characteristic value is extracted and is treated as a Numerical Measurement of the effect of load profile on voltage degradation. The characteristic value is defined using both load current and load voltage. Third, an empirical model is proposed, modeling the voltage degradation rate as a linear function of the load profile's characteristic value. Finally, experimental data are used to fit the coefficients and validate the model.
Zhang Qilin - One of the best experts on this subject based on the ideXlab platform.
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A Study on Pre-tension Measurement of Membrane Structures
International Journal of Space Structures, 2005Co-Authors: Sun Zhanjin, Zhang QilinAbstract:Compared with the wide application of the membrane structures, the pretension measuring techniques for membrane structures have developed far more slowly. Further studies to search for a high-precision pretension measuring method which is reliable in theory and convenient for operation are not only necessary but also urgent. With the help of the finite element method, two important characteristics, the principles of "Stress Superposition" and "Stiffening Effect of Stress", are discovered and summarized in this article. The characteristics relate to the relationships between the pretensions of a stretched rectangular membrane with fixed boundaries around, the out-plane displacements at the central point of the membrane and the normal uniform loads applied on the membrane. Based on these two characteristics, a new method to measure the pretensions of membrane structures is proposed, which is called "Numerical Measurement" in this paper. In the final part of the paper, a series of experiments are reported to...
Xinfeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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load profile based empirical model for the lifetime prediction of an automotive pem fuel cell
International Journal of Hydrogen Energy, 2017Co-Authors: Xinfeng Zhang, Daijun Yang, Minghui Luo, Zuomin DongAbstract:Abstract The prediction of the lifetime of a PEM fuel cell under a specific electrical load profile is beneficial for automotive applications. An empirical lifetime prediction model coupled with an electrical load profile is presented based on an estimate of the degradation rate of the cell voltage. First, a cause and effect chain-based analysis of the PEM fuel cell's degradation process is presented. Second, a characteristic value is extracted and is treated as a Numerical Measurement of the effect of load profile on voltage degradation. The characteristic value is defined using both load current and load voltage. Third, an empirical model is proposed, modeling the voltage degradation rate as a linear function of the load profile's characteristic value. Finally, experimental data are used to fit the coefficients and validate the model.
