The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
P. Ola G. Persson - One of the best experts on this subject based on the ideXlab platform.
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SHEBA flux–profile relationships in the stable atmospheric boundary layer
Boundary-Layer Meteorology, 2007Co-Authors: Andrey A. Grachev, Christopher W. Fairall, Peter S. Guest, Edgar L Andreas, P. Ola G. PerssonAbstract:Measurements of atmospheric turbulence made during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) are used to examine the profile Stability functions of momentum, φ_ m , and sensible heat, φ_ h , in the stably stratified boundary layer over the Arctic pack ice. Turbulent fluxes and mean meteorological data that cover different surface conditions and a wide Range of Stability conditions were continuously measured and reported hourly at five levels on a 20-m main tower for 11 months. The comprehensive dataset collected during SHEBA allows studying φ_ m and φ_ h in detail and includes ample data for the very stable case. New parameterizations for φ_ m (ζ) and φ_ h (ζ) in stable conditions are proposed to describe the SHEBA data; these cover the entire Range of the Stability parameter ζ = z / L from neutral to very stable conditions, where L is the Obukhov length and z is the measurement height. In the limit of very strong Stability, φ _ m follows a ζ ^1/3 dependence, whereas φ_ h initially increases with increasing ζ, reaches a maximum at ζ ≈ 10, and then tends to level off with increasing ζ. The effects of self-correlation, which occur in plots of φ_ m and φ_ h versus ζ, are reduced by using an independent bin-averaging method instead of conventional averaging.
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SHEBA flux-profile relationships in the stable atmospheric boundary layer
Boundary-Layer Meteorology, 2007Co-Authors: Andrey A. Grachev, Christopher W. Fairall, Peter S. Guest, Edgar L Andreas, P. Ola G. PerssonAbstract:Measurements of atmospheric turbulence made during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) are used to examine the profile Stability functions of momentum, phi m, and sensible heat, phi h, in the stably stratified boundary layer over the Arctic pack ice. Turbulent fluxes and mean meteorological data that cover different surface conditions and a wide Range of Stability conditions were continuously measured and reported hourly at five levels on a 20-m main tower for 11 months. The comprehensive dataset collected during SHEBA allows studying phi m and phi h in detail and includes ample data for the very stable case. New parameterizations for phi m(zeta) and phi h(zeta) in stable conditions are proposed to describe the SHEBA data; these cover the entire Range of the Stability parameter zeta = z/L from neutral to very stable conditions, where L is the Obukhov length and z is the measurement height. In the limit of very strong Stability, phi m follows a zeta(1/3) dependence, whereas phi h initially increases with increasing zeta, reaches a maximum at zeta approximate to 10, and then tends to level off with increasing zeta. The effects of self-correlation, which occur in plots of phi m and phi h versus zeta, are reduced by using an independent bin-averaging method instead of conventional averaging.
Jean-marie Tarascon - One of the best experts on this subject based on the ideXlab platform.
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Rechargeable Li1 + xMn2O4/Carbon Cells with a New Electrolyte Composition
Journal of The Electrochemical Society, 1993Co-Authors: Dominique Guyomard, Jean-marie TarasconAbstract:To improve the high temperature performance of Li1+xMn2O4/C rocking-chair secondary batteries the authors searched for and identified a new electrolyte composition whose Range of Stability extends up to 4.9 V vs. Li at room temperature and 4.8 V vs. Li at 55° for the LixMn2O4 material. The behavior of the LiMn2O4 composite new electrolyte interface at high voltage (4.2 to 5.1 V vs. Li) shows the superposition of 2 phenomena: (i) an irreversible behavior due to a very slow electrolyte oxidation caused by the large surface area of C black (mixed with the LixMn2O4 active material to improve the conductivity) and (ii) 2 reversible Li deintercalation-intercalation processes in the LixMn2O4 spinel structure. To evaluate the kinetics of the high voltage phenomena, the behavior of the LiMn2O4/new electrolyte interface was studied as a function of time and temperature The electrolyte oxidative degradation is a well-stabilized reaction with nontime evolving kinetics, and with an activation energy close to 8 kcal/mol. The self-discharge mechanism is a local redox process involving electrolyte oxidation at the electrode surface and reversible intercalation of Li in the LixMn2O4 spinel structure. The effective Stability of this new electrolyte against oxidation allows for better performance of the authors' rocking-chair cells, in terms of cycle-life and self-discharge, over a wider temperature Range (-20 to 55°).
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Rechargeable Li[sub 1 + x]Mn[sub 2]O[sub 4]/Carbon Cells with a New Electrolyte Composition
Journal of The Electrochemical Society, 1993Co-Authors: Dominique Guyomard, Jean-marie TarasconAbstract:To improve the high temperature performance of Li1+xMn2O4/carbon rocking-chair secondary batteries we searched forand identified a new electrolyte composition whose Range of Stability extends up to 4.9 V vs. Li at room temperature and4.8 V vs. Li at 55°C for the LixMn2O4 material. The behavior of the LiMn2O4 composite new electrolyte interface at highvoltage (4.2 to 5.1 V vs. Li) shows the superposition of two phenomena: (i) an irreversible behavior due to a very slowelectrolyte oxidation caused by the large surface area of carbon black (mixed with the LixMn2O4 active material to improvethe conductivity) and (ii) two reversible Li deintercalation-intercalation processes in the LixMn2O4 spinel structure. Inorder to evaluate the kinetics of the high voltage phenomena, the behavior of the LiMn2O4/new electrolyte interface wasinvestigated as a function of time and temperature. The electrolyte oxidative degradation is a well-stabilized reaction withnontime evolving kinetics, and with an activation energy close to 8 kcal/mol. The self-discharge mechanism is a local redoxprocess involving electrolyte oxidation at the electrode surface and reversible intercalation of Li in the LixMn2O4 spinelstructure. The effective Stability of this new electrolyte against oxidation allows for better performance of our rocking-chaircells, in terms of cycle-life and self-discharge, over a wider temperature Range (–20 to 55°C).
Andrey A. Grachev - One of the best experts on this subject based on the ideXlab platform.
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SHEBA flux–profile relationships in the stable atmospheric boundary layer
Boundary-Layer Meteorology, 2007Co-Authors: Andrey A. Grachev, Christopher W. Fairall, Peter S. Guest, Edgar L Andreas, P. Ola G. PerssonAbstract:Measurements of atmospheric turbulence made during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) are used to examine the profile Stability functions of momentum, φ_ m , and sensible heat, φ_ h , in the stably stratified boundary layer over the Arctic pack ice. Turbulent fluxes and mean meteorological data that cover different surface conditions and a wide Range of Stability conditions were continuously measured and reported hourly at five levels on a 20-m main tower for 11 months. The comprehensive dataset collected during SHEBA allows studying φ_ m and φ_ h in detail and includes ample data for the very stable case. New parameterizations for φ_ m (ζ) and φ_ h (ζ) in stable conditions are proposed to describe the SHEBA data; these cover the entire Range of the Stability parameter ζ = z / L from neutral to very stable conditions, where L is the Obukhov length and z is the measurement height. In the limit of very strong Stability, φ _ m follows a ζ ^1/3 dependence, whereas φ_ h initially increases with increasing ζ, reaches a maximum at ζ ≈ 10, and then tends to level off with increasing ζ. The effects of self-correlation, which occur in plots of φ_ m and φ_ h versus ζ, are reduced by using an independent bin-averaging method instead of conventional averaging.
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SHEBA flux-profile relationships in the stable atmospheric boundary layer
Boundary-Layer Meteorology, 2007Co-Authors: Andrey A. Grachev, Christopher W. Fairall, Peter S. Guest, Edgar L Andreas, P. Ola G. PerssonAbstract:Measurements of atmospheric turbulence made during the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) are used to examine the profile Stability functions of momentum, phi m, and sensible heat, phi h, in the stably stratified boundary layer over the Arctic pack ice. Turbulent fluxes and mean meteorological data that cover different surface conditions and a wide Range of Stability conditions were continuously measured and reported hourly at five levels on a 20-m main tower for 11 months. The comprehensive dataset collected during SHEBA allows studying phi m and phi h in detail and includes ample data for the very stable case. New parameterizations for phi m(zeta) and phi h(zeta) in stable conditions are proposed to describe the SHEBA data; these cover the entire Range of the Stability parameter zeta = z/L from neutral to very stable conditions, where L is the Obukhov length and z is the measurement height. In the limit of very strong Stability, phi m follows a zeta(1/3) dependence, whereas phi h initially increases with increasing zeta, reaches a maximum at zeta approximate to 10, and then tends to level off with increasing zeta. The effects of self-correlation, which occur in plots of phi m and phi h versus zeta, are reduced by using an independent bin-averaging method instead of conventional averaging.
M.m. Silva - One of the best experts on this subject based on the ideXlab platform.
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A new current mode control process and applications
IEEE Transactions on Power Electronics, 1991Co-Authors: A.v. Anunciada, M.m. SilvaAbstract:A Stability analysis of constant frequency current mode power converters is presented. A current mode control method that overcomes the limited duty cycle Range of Stability is introduced. The authors present the application of the control method to half bridge and full bridge converters, and describe an improved performance uninterruptible power supply (UPS) based on the method. The UPS has only one power transformer and one power transistor bridge. The authors present detailed experimental results which confirm the advantages of the circuits.
Dominique Guyomard - One of the best experts on this subject based on the ideXlab platform.
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Rechargeable Li1 + xMn2O4/Carbon Cells with a New Electrolyte Composition
Journal of The Electrochemical Society, 1993Co-Authors: Dominique Guyomard, Jean-marie TarasconAbstract:To improve the high temperature performance of Li1+xMn2O4/C rocking-chair secondary batteries the authors searched for and identified a new electrolyte composition whose Range of Stability extends up to 4.9 V vs. Li at room temperature and 4.8 V vs. Li at 55° for the LixMn2O4 material. The behavior of the LiMn2O4 composite new electrolyte interface at high voltage (4.2 to 5.1 V vs. Li) shows the superposition of 2 phenomena: (i) an irreversible behavior due to a very slow electrolyte oxidation caused by the large surface area of C black (mixed with the LixMn2O4 active material to improve the conductivity) and (ii) 2 reversible Li deintercalation-intercalation processes in the LixMn2O4 spinel structure. To evaluate the kinetics of the high voltage phenomena, the behavior of the LiMn2O4/new electrolyte interface was studied as a function of time and temperature The electrolyte oxidative degradation is a well-stabilized reaction with nontime evolving kinetics, and with an activation energy close to 8 kcal/mol. The self-discharge mechanism is a local redox process involving electrolyte oxidation at the electrode surface and reversible intercalation of Li in the LixMn2O4 spinel structure. The effective Stability of this new electrolyte against oxidation allows for better performance of the authors' rocking-chair cells, in terms of cycle-life and self-discharge, over a wider temperature Range (-20 to 55°).
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Rechargeable Li[sub 1 + x]Mn[sub 2]O[sub 4]/Carbon Cells with a New Electrolyte Composition
Journal of The Electrochemical Society, 1993Co-Authors: Dominique Guyomard, Jean-marie TarasconAbstract:To improve the high temperature performance of Li1+xMn2O4/carbon rocking-chair secondary batteries we searched forand identified a new electrolyte composition whose Range of Stability extends up to 4.9 V vs. Li at room temperature and4.8 V vs. Li at 55°C for the LixMn2O4 material. The behavior of the LiMn2O4 composite new electrolyte interface at highvoltage (4.2 to 5.1 V vs. Li) shows the superposition of two phenomena: (i) an irreversible behavior due to a very slowelectrolyte oxidation caused by the large surface area of carbon black (mixed with the LixMn2O4 active material to improvethe conductivity) and (ii) two reversible Li deintercalation-intercalation processes in the LixMn2O4 spinel structure. Inorder to evaluate the kinetics of the high voltage phenomena, the behavior of the LiMn2O4/new electrolyte interface wasinvestigated as a function of time and temperature. The electrolyte oxidative degradation is a well-stabilized reaction withnontime evolving kinetics, and with an activation energy close to 8 kcal/mol. The self-discharge mechanism is a local redoxprocess involving electrolyte oxidation at the electrode surface and reversible intercalation of Li in the LixMn2O4 spinelstructure. The effective Stability of this new electrolyte against oxidation allows for better performance of our rocking-chaircells, in terms of cycle-life and self-discharge, over a wider temperature Range (–20 to 55°C).
