Dissipation

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Yi Wang - One of the best experts on this subject based on the ideXlab platform.

  • energy Dissipation processes in solar wind turbulence
    Astrophysical Journal Supplement Series, 2015
    Co-Authors: Yi Wang, Fusheng Wei, Xueshang Feng, Jie Zhang, T Sun, Pingbing Zuo
    Abstract:

    Turbulence is a chaotic flow regime filled by irregular flows. The Dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, Dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible Dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the Dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the Dissipation range, while the ambient solar wind turbulence reveals a monofractal Dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal Dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy Dissipation process.

  • energy Dissipation processes in solar wind turbulence
    arXiv: Space Physics, 2015
    Co-Authors: Yi Wang, Fusheng Wei, Xueshang Feng, Jie Zhang, T Sun, Pingbing Zuo
    Abstract:

    Turbulence is a chaotic flow regime filled by irregular flows. The Dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, Dissipation cannot be ultimately achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection are two possible Dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the Dissipation region scaling around a solar wind magnetic reconnection region. We find that the magnetic reconnection region shows a unique multifractal scaling in the Dissipation range, while the ambient solar wind turbulence reveals a monofractal Dissipation process for most of the time. These results provide the first observational evidences for the intermittent multifractal Dissipation region scaling around a magnetic reconnection site, and they also have significant implications for the fundamental energy Dissipation process.

Mehmood Nasir - One of the best experts on this subject based on the ideXlab platform.

  • Effect of hydrodynamic and transfer of oxygen on the physiology of Streptomyces pristinaespiralis in shake flasks
    2011
    Co-Authors: Mehmood Nasir
    Abstract:

    Dans le cadre de ce travail de thèse, la physiologie apparente de Streptomyces pristinaespiralis et plus spécifiquement la production de pristinamycines (déclenchement et concentration) a été reliée à son environnement hydrodynamique. Des cultures de S. pristinaespiralis ont été réalisées sous diverses conditions d'agitation et d'aération, en fioles lisses d'Erlenmeyer. Ces conditions engendrent des Dissipations volumiques comprises entre 0,55 et 14 kW.m-3 et des kLa compris entre 30 et 490 h-1. Partant du constat de la complexité combinée de l'hydrodynamique rencontrée dans les bioréacteurs et de la réponse cellulaire, nous avons développé une approche pluridisciplinaire et multiéchelle à l'interface entre génie des procédés et physiologie quantitative. La réponse physiologique apparente a été quantifiée en termes de croissance, consommation des substrats, morphologie et production. L'hydrodynamique des fioles agitées a été notamment décrite par utilisation de la simulation numérique des écoulements. Par l'utilisation originale d'un modèle de rupture, les diamètres des pelotes ont été corrélés à l'échelle de Dissipation de Kolmogorov. De plus, il a été montré que la Dissipation défavorisait la croissance des pelotes. Ainsi, par le découplage de l'agitation et de l'aération, il a été montré que la taille des pelotes, contrôlée par la turbulence, impactait directement la consommation d'oxygène et la quantité de pristinamycines produites. Par ailleurs, le déclenchement de la production, résultante d'une limitation en substrats azotés et d'un apport en oxygène suffisant, est déterminé conjointement par la quantité du transfert d'oxygène et par la Dissipation volumiqueDuring this study, the physiology of Streptomyces pristinaespiralis and more specifically the production of pristinamycins (induction and concentration) were related to its hydrodynamic environment. Cultures of S. pristinaespiralis were performed under various conditions of agitation and aeration in non baffled Erlenmeyer flasks. According to the operating conditions, the volume power Dissipation was from 0.55 to 14 kW.m-3 while kLa was from 30 to 490 h-1. Based on the observation of the complexity of both hydrodynamics encountered in bioreactors and of the cellular response, a multiscale and multidisciplinary approach between process engineering and quantitative physiology was developed. The apparent physiological response was quantified in terms of growth, substrates consumption, morphology and production. The hydrodynamics of the shake flasks was described using Computational Fluid Dynamics. Using an original break up model, the pellet diameters were correlated to the Kolmogorov Dissipation scale. Moreover, it was shown that pellet growth was slowed down by the Dissipation scale increase. Then, by decoupling the agitation and the aeration, it was shown that the pellets size, controlled by turbulence, impacted directly the consumption of oxygen and the concentration of pristinamycins. Furthermore, onset of pristinamycin production resulted in a limitation in nitrogen substrates as well as a sufficient oxygen supply which are determined by the oxygen transfer and the volume power dissipatio

  • Effets de l'hydrodynamique et du transfert d'oxygène sur la physiologie de Streptomyces pristinaespiralis lors de cultures en flacons agités
    HAL CCSD, 2011
    Co-Authors: Mehmood Nasir
    Abstract:

    During this study, the physiology of Streptomyces pristinaespiralis and more specifically the production of pristinamycins (induction and concentration) were related to its hydrodynamic environment. Cultures of S. pristinaespiralis were performed under various conditions of agitation and aeration in non baffled Erlenmeyer flasks. According to the operating conditions, the volume power Dissipation was from 0.55 to 14 kW.m-3 while kLa was from 30 to 490 h-1. Based on the observation of the complexity of both hydrodynamics encountered in bioreactors and of the cellular response, a multiscale and multidisciplinary approach between process engineering and quantitative physiology was developed. The apparent physiological response was quantified in terms of growth, substrates consumption, morphology and production. The hydrodynamics of the shake flasks was described using Computational Fluid Dynamics. Using an original break up model, the pellet diameters were correlated to the Kolmogorov Dissipation scale. Moreover, it was shown that pellet growth was slowed down by the Dissipation scale increase. Then, by decoupling the agitation and the aeration, it was shown that the pellets size, controlled by turbulence, impacted directly the consumption of oxygen and the concentration of pristinamycins. Furthermore, onset of pristinamycin production resulted in a limitation in nitrogen substrates as well as a sufficient oxygen supply which are determined by the oxygen transfer and the volume power DissipationDans le cadre de ce travail de thèse, la physiologie apparente de Streptomyces pristinaespiralis et plus spécifiquement la production de pristinamycines (déclenchement et concentration) a été reliée à son environnement hydrodynamique. Des cultures de S. pristinaespiralis ont été réalisées sous diverses conditions d'agitation et d'aération, en fioles lisses d'Erlenmeyer. Ces conditions engendrent des Dissipations volumiques comprises entre 0,55 et 14 kW.m-3 et des kLa compris entre 30 et 490 h-1. Partant du constat de la complexité combinée de l'hydrodynamique rencontrée dans les bioréacteurs et de la réponse cellulaire, nous avons développé une approche pluridisciplinaire et multiéchelle à l'interface entre génie des procédés et physiologie quantitative. La réponse physiologique apparente a été quantifiée en termes de croissance, consommation des substrats, morphologie et production. L'hydrodynamique des fioles agitées a été notamment décrite par utilisation de la simulation numérique des écoulements. Par l'utilisation originale d'un modèle de rupture, les diamètres des pelotes ont été corrélés à l'échelle de Dissipation de Kolmogorov. De plus, il a été montré que la Dissipation défavorisait la croissance des pelotes. Ainsi, par le découplage de l'agitation et de l'aération, il a été montré que la taille des pelotes, contrôlée par la turbulence, impactait directement la consommation d'oxygène et la quantité de pristinamycines produites. Par ailleurs, le déclenchement de la production, résultante d'une limitation en substrats azotés et d'un apport en oxygène suffisant, est déterminé conjointement par la quantité du transfert d'oxygène et par la Dissipation volumiqu

  • Effets de l'hydrodynamique et du transfert d'oxygène sur la physiologie de Streptomyces pristinaespiralis lors de cultures en flacons agités
    2011
    Co-Authors: Mehmood Nasir, Fick Michel, Olmos Eric, Delaunay Stéphane
    Abstract:

    Dans le cadre de ce travail de thèse, la physiologie apparente de Streptomyces pristinaespiralis et plus spécifiquement la production de pristinamycines (déclenchement et concentration) a été reliée à son environnement hydrodynamique. Des cultures de S. pristinaespiralis ont été réalisées sous diverses conditions d'agitation et d'aération, en fioles lisses d Erlenmeyer. Ces conditions engendrent des Dissipations volumiques comprises entre 0,55 et 14 kW.m-3 et des kLa compris entre 30 et 490 h-1. Partant du constat de la complexité combinée de l hydrodynamique rencontrée dans les bioréacteurs et de la réponse cellulaire, nous avons développé une approche pluridisciplinaire et multiéchelle à l interface entre génie des procédés et physiologie quantitative. La réponse physiologique apparente a été quantifiée en termes de croissance, consommation des substrats, morphologie et production. L hydrodynamique des fioles agitées a été notamment décrite par utilisation de la simulation numérique des écoulements. Par l utilisation originale d un modèle de rupture, les diamètres des pelotes ont été corrélés à l échelle de Dissipation de Kolmogorov. De plus, il a été montré que la Dissipation défavorisait la croissance des pelotes. Ainsi, par le découplage de l agitation et de l aération, il a été montré que la taille des pelotes, contrôlée par la turbulence, impactait directement la consommation d oxygène et la quantité de pristinamycines produites. Par ailleurs, le déclenchement de la production, résultante d une limitation en substrats azotés et d un apport en oxygène suffisant, est déterminé conjointement par la quantité du transfert d oxygène et par la Dissipation volumiqueDuring this study, the physiology of Streptomyces pristinaespiralis and more specifically the production of pristinamycins (induction and concentration) were related to its hydrodynamic environment. Cultures of S. pristinaespiralis were performed under various conditions of agitation and aeration in non baffled Erlenmeyer flasks. According to the operating conditions, the volume power Dissipation was from 0.55 to 14 kW.m-3 while kLa was from 30 to 490 h-1. Based on the observation of the complexity of both hydrodynamics encountered in bioreactors and of the cellular response, a multiscale and multidisciplinary approach between process engineering and quantitative physiology was developed. The apparent physiological response was quantified in terms of growth, substrates consumption, morphology and production. The hydrodynamics of the shake flasks was described using Computational Fluid Dynamics. Using an original break up model, the pellet diameters were correlated to the Kolmogorov Dissipation scale. Moreover, it was shown that pellet growth was slowed down by the Dissipation scale increase. Then, by decoupling the agitation and the aeration, it was shown that the pellets size, controlled by turbulence, impacted directly the consumption of oxygen and the concentration of pristinamycins. Furthermore, onset of pristinamycin production resulted in a limitation in nitrogen substrates as well as a sufficient oxygen supply which are determined by the oxygen transfer and the volume power DissipationNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Pingbing Zuo - One of the best experts on this subject based on the ideXlab platform.

  • energy Dissipation processes in solar wind turbulence
    Astrophysical Journal Supplement Series, 2015
    Co-Authors: Yi Wang, Fusheng Wei, Xueshang Feng, Jie Zhang, T Sun, Pingbing Zuo
    Abstract:

    Turbulence is a chaotic flow regime filled by irregular flows. The Dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, Dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible Dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the Dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the Dissipation range, while the ambient solar wind turbulence reveals a monofractal Dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal Dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy Dissipation process.

  • energy Dissipation processes in solar wind turbulence
    arXiv: Space Physics, 2015
    Co-Authors: Yi Wang, Fusheng Wei, Xueshang Feng, Jie Zhang, T Sun, Pingbing Zuo
    Abstract:

    Turbulence is a chaotic flow regime filled by irregular flows. The Dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, Dissipation cannot be ultimately achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection are two possible Dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the Dissipation region scaling around a solar wind magnetic reconnection region. We find that the magnetic reconnection region shows a unique multifractal scaling in the Dissipation range, while the ambient solar wind turbulence reveals a monofractal Dissipation process for most of the time. These results provide the first observational evidences for the intermittent multifractal Dissipation region scaling around a magnetic reconnection site, and they also have significant implications for the fundamental energy Dissipation process.

H Wei - One of the best experts on this subject based on the ideXlab platform.

  • estimation to the turbulent kinetic energy Dissipation rate and bottom shear stress in the tidal bottom boundary layer of the yellow sea
    Progress in Natural Science, 2007
    Co-Authors: Zhiyu Liu, H Wei
    Abstract:

    Abstract High frequency velocity fluctuations were measured by using an acoustic Doppler velocimeter (ADV) in the tidal bottom boundary layer (BBL) of the Yellow Sea (YS) for 25 h. The turbulent kinetic energy Dissipation rate and the bottom shear stress were estimated and analyzed. Results show that: (1) in the tidal BBL of the YS the variations of the Dissipation rate and the bottom shear stress during 25 h are (1.8 × 10−8−3.4× 10−5) W'kg−1 and 6.6 × 10−4−7.5 × 10 −1) N' m−2 respectively, indicating that there are strong Dissipations in the tidal BBL of the YS (2) in the well-mixed tidal BBL, the turbulence is mainly shear-induced locally and the production and Dissipation are generally in equilibrium (3) for the seas where the semidiurnal tidal current is dominant, both the Dissipation rate and the bottom shear stress exhibit a strong quarter-diurnal variation (4) the mean bottom drag coefficient C¯ (0.45) is 0.0017 (corresponding C¯d(1.00 = 0.0015), but it has significant variations (0.00050−0082). Th...

Delaunay Stéphane - One of the best experts on this subject based on the ideXlab platform.

  • Effets de l'hydrodynamique et du transfert d'oxygène sur la physiologie de Streptomyces pristinaespiralis lors de cultures en flacons agités
    2011
    Co-Authors: Mehmood Nasir, Fick Michel, Olmos Eric, Delaunay Stéphane
    Abstract:

    Dans le cadre de ce travail de thèse, la physiologie apparente de Streptomyces pristinaespiralis et plus spécifiquement la production de pristinamycines (déclenchement et concentration) a été reliée à son environnement hydrodynamique. Des cultures de S. pristinaespiralis ont été réalisées sous diverses conditions d'agitation et d'aération, en fioles lisses d Erlenmeyer. Ces conditions engendrent des Dissipations volumiques comprises entre 0,55 et 14 kW.m-3 et des kLa compris entre 30 et 490 h-1. Partant du constat de la complexité combinée de l hydrodynamique rencontrée dans les bioréacteurs et de la réponse cellulaire, nous avons développé une approche pluridisciplinaire et multiéchelle à l interface entre génie des procédés et physiologie quantitative. La réponse physiologique apparente a été quantifiée en termes de croissance, consommation des substrats, morphologie et production. L hydrodynamique des fioles agitées a été notamment décrite par utilisation de la simulation numérique des écoulements. Par l utilisation originale d un modèle de rupture, les diamètres des pelotes ont été corrélés à l échelle de Dissipation de Kolmogorov. De plus, il a été montré que la Dissipation défavorisait la croissance des pelotes. Ainsi, par le découplage de l agitation et de l aération, il a été montré que la taille des pelotes, contrôlée par la turbulence, impactait directement la consommation d oxygène et la quantité de pristinamycines produites. Par ailleurs, le déclenchement de la production, résultante d une limitation en substrats azotés et d un apport en oxygène suffisant, est déterminé conjointement par la quantité du transfert d oxygène et par la Dissipation volumiqueDuring this study, the physiology of Streptomyces pristinaespiralis and more specifically the production of pristinamycins (induction and concentration) were related to its hydrodynamic environment. Cultures of S. pristinaespiralis were performed under various conditions of agitation and aeration in non baffled Erlenmeyer flasks. According to the operating conditions, the volume power Dissipation was from 0.55 to 14 kW.m-3 while kLa was from 30 to 490 h-1. Based on the observation of the complexity of both hydrodynamics encountered in bioreactors and of the cellular response, a multiscale and multidisciplinary approach between process engineering and quantitative physiology was developed. The apparent physiological response was quantified in terms of growth, substrates consumption, morphology and production. The hydrodynamics of the shake flasks was described using Computational Fluid Dynamics. Using an original break up model, the pellet diameters were correlated to the Kolmogorov Dissipation scale. Moreover, it was shown that pellet growth was slowed down by the Dissipation scale increase. Then, by decoupling the agitation and the aeration, it was shown that the pellets size, controlled by turbulence, impacted directly the consumption of oxygen and the concentration of pristinamycins. Furthermore, onset of pristinamycin production resulted in a limitation in nitrogen substrates as well as a sufficient oxygen supply which are determined by the oxygen transfer and the volume power DissipationNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

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