The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Giacomo Gnudi - One of the best experts on this subject based on the ideXlab platform.
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A Dynamic Morphometric Model of the Normal Lung for Studying Expiratory Flow Limitation in Mechanical Ventilation
Annals of Biomedical Engineering, 2005Co-Authors: Paolo Barbini, C. Brighenti, Gabriele Cevenini, Giacomo GnudiAbstract:A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheobronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The model also accounts for the main mechanisms limiting expiratory flow (wave Speed Limitation and viscous flow Limitation), in order to reproduce satisfactorily, under dynamic conditions, the expiratory flow Limitation phenomenon occurring in normal subjects when the difference between alveolar pressure and tracheal pressure (driving pressure) is high. Several expirations characterized by different levels of driving pressure are simulated and expiratory flow Limitation is detected by plotting the isovolume pressure–flow curves. The model is used to study the time course of resistance and total cross-sectional area as well as the ratio of fluid velocity to wave Speed (Speed index), in conductive airway generations. The results highlight that the coupling between dissipative pressure losses and airway compliance leads to onset of expiratory flow Limitation in normal lungs when driving pressure is increased significantly by applying a subatmospheric pressure to the outlet of the ventilator expiratory channel; wave Speed Limitation becomes predominant at still higher driving pressures.
Paolo Barbini - One of the best experts on this subject based on the ideXlab platform.
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A Dynamic Morphometric Model of the Normal Lung for Studying Expiratory Flow Limitation in Mechanical Ventilation
Annals of Biomedical Engineering, 2005Co-Authors: Paolo Barbini, C. Brighenti, Gabriele Cevenini, Giacomo GnudiAbstract:A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheobronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The model also accounts for the main mechanisms limiting expiratory flow (wave Speed Limitation and viscous flow Limitation), in order to reproduce satisfactorily, under dynamic conditions, the expiratory flow Limitation phenomenon occurring in normal subjects when the difference between alveolar pressure and tracheal pressure (driving pressure) is high. Several expirations characterized by different levels of driving pressure are simulated and expiratory flow Limitation is detected by plotting the isovolume pressure–flow curves. The model is used to study the time course of resistance and total cross-sectional area as well as the ratio of fluid velocity to wave Speed (Speed index), in conductive airway generations. The results highlight that the coupling between dissipative pressure losses and airway compliance leads to onset of expiratory flow Limitation in normal lungs when driving pressure is increased significantly by applying a subatmospheric pressure to the outlet of the ventilator expiratory channel; wave Speed Limitation becomes predominant at still higher driving pressures.
Laren M. Tolbert - One of the best experts on this subject based on the ideXlab platform.
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temperature dependent characterization modeling and switching Speed Limitation analysis of third generation 10 kv sic mosfet
IEEE Transactions on Power Electronics, 2018Co-Authors: Shiqi Ji, Sheng Zheng, F. Wang, Laren M. TolbertAbstract:The temperature-dependent characteristics of the third-generation 10-kV/20-A SiC MOSFET including the static characteristics and switching performance are carried out in this paper. The steady-state characteristics, including saturation current, output characteristics, antiparallel diode, and parasitic capacitance, are tested. A double pulse test platform is constructed including a circuit breaker and gate drive with >10-kV insulation and also a hotplate under the device under test for temperature-dependent characterization during switching transients. The switching performance is tested under various load currents and gate resistances at a 7-kV dc-link voltage from 25 to 125 ˚C and compared with previous 10-kV MOSFETs. A simple behavioral model with its parameter extraction method is proposed to predict the temperature-dependent characteristics of the 10-kV SiC MOSFET. The switching Speed Limitations, including the reverse recovery of SiC MOSFET's body diode, overvoltage caused by stray inductance, crosstalk, heat sink, and electromagnetic interference to the control are discussed based on simulations and experimental results.
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analysis of the switching Speed Limitation of wide band gap devices in a phase leg configuration
European Conference on Cognitive Ergonomics, 2012Co-Authors: Zheyu Zhang, Laren M. Tolbert, Weimin Zhang, Fred Wang, Benjamin J. BlalockAbstract:Advanced power semiconductor devices, especially wide band-gap devices, have inherent capability for fast switching. However, due to the Limitation of gate driver capability and the interaction between two devices in a phase-leg during switching transient (cross talk), the switching Speed is slower than expected in practical use. This paper focuses on identifying the key limiting factors for switching Speed. The results provide the basis for improving gate drivers, eliminating interference, and boosting switching Speed. Based on the EPC2001 Gallium Nitride transistor, both simulation and experimental results verify that the limiting factors in the gate loop include the pull-up (-down) resistance of gate driver, rise (fall) time and amplitude of gate driver output voltage; among these the rise (fall) time plays the primary role. Another important limiting factor of device switching Speed is the spurious gate voltage induced by cross talk between two switches in a phase-leg. This induced gate voltage is not only determined by the switch Speed, but also depends on the gate loop impedance, junction capacitance, and operating conditions of the complementary device.
C. Brighenti - One of the best experts on this subject based on the ideXlab platform.
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A Dynamic Morphometric Model of the Normal Lung for Studying Expiratory Flow Limitation in Mechanical Ventilation
Annals of Biomedical Engineering, 2005Co-Authors: Paolo Barbini, C. Brighenti, Gabriele Cevenini, Giacomo GnudiAbstract:A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheobronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The model also accounts for the main mechanisms limiting expiratory flow (wave Speed Limitation and viscous flow Limitation), in order to reproduce satisfactorily, under dynamic conditions, the expiratory flow Limitation phenomenon occurring in normal subjects when the difference between alveolar pressure and tracheal pressure (driving pressure) is high. Several expirations characterized by different levels of driving pressure are simulated and expiratory flow Limitation is detected by plotting the isovolume pressure–flow curves. The model is used to study the time course of resistance and total cross-sectional area as well as the ratio of fluid velocity to wave Speed (Speed index), in conductive airway generations. The results highlight that the coupling between dissipative pressure losses and airway compliance leads to onset of expiratory flow Limitation in normal lungs when driving pressure is increased significantly by applying a subatmospheric pressure to the outlet of the ventilator expiratory channel; wave Speed Limitation becomes predominant at still higher driving pressures.
Gabriele Cevenini - One of the best experts on this subject based on the ideXlab platform.
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A Dynamic Morphometric Model of the Normal Lung for Studying Expiratory Flow Limitation in Mechanical Ventilation
Annals of Biomedical Engineering, 2005Co-Authors: Paolo Barbini, C. Brighenti, Gabriele Cevenini, Giacomo GnudiAbstract:A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheobronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The model also accounts for the main mechanisms limiting expiratory flow (wave Speed Limitation and viscous flow Limitation), in order to reproduce satisfactorily, under dynamic conditions, the expiratory flow Limitation phenomenon occurring in normal subjects when the difference between alveolar pressure and tracheal pressure (driving pressure) is high. Several expirations characterized by different levels of driving pressure are simulated and expiratory flow Limitation is detected by plotting the isovolume pressure–flow curves. The model is used to study the time course of resistance and total cross-sectional area as well as the ratio of fluid velocity to wave Speed (Speed index), in conductive airway generations. The results highlight that the coupling between dissipative pressure losses and airway compliance leads to onset of expiratory flow Limitation in normal lungs when driving pressure is increased significantly by applying a subatmospheric pressure to the outlet of the ventilator expiratory channel; wave Speed Limitation becomes predominant at still higher driving pressures.