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991.
Trines R Bingham R Silva LO Mendonça JT Shukla PK Mori WB 《Physical review letters》2005,94(16):165002
The interaction between broadband drift mode turbulence and zonal flows has been studied through the wave-kinetic approach. Simulations have been conducted in which a particle-in-cell representation is used for the quasiparticles, while a fluid model is employed for the plasma. The interactions have been studied in a plasma edge configuration which has applications in both tokamak physics and magnetopause boundary layer studies. Simulation results show the development of a zonal flow through the modulational instability of the drift wave distribution, as well as the existence of solitary zonal flow structures about an ion gyroradius wide, drifting towards steeper relative density gradients. 相似文献
992.
A conformally flat accelerated charge metric is found in an arbitrary dimension D. It is a solution of the Einstein-Maxwell-null fluid equations with a cosmological constant in D ≥ 4 dimensions. When the acceleration is zero, our solution reduces to the Levi-Civita-Bertotti-Robinson metric. We show
that the charge loses its energy, for all dimensions, due to the acceleration. 相似文献
993.
L. Krupnik A. Alonso E. Ascasibar T. Estrada C. Hidalgo B. van Milligen M. Ochando M. Pedrosa J. L. de Pablos V. Tribaldos A. Chmyga N. Dreval G. Deshko S. Khrebtov A. Komarov A. Kozachok V. Tereshin L. Eliseev A. Melnikov C. Silva 《Czechoslovak Journal of Physics》2005,55(3):317-339
Radial plasma potential profiles have been obtained in the TJ-II by the Heavy Ion Beam Probing (HIBP) diagnostics. Results show that the potential increases up to 1 kV near the magnetic axis in ECRH low-density plasmas. The secondary ion current profiles, which directly reflect the plasma density, are hollow. In low-density ECRH operation, radial electric fields are found to be positive in the plasma core, however, a reduction in these fields is observed with increasing density. Radial plasma potential profiles show evidence of structures in configurations with low-order rational surfaces. In particular, HIBP measurements have permitted characterization of the plasma potential profile during e-ITB formation. Experiments in TJ-II have shown that it is possible to modify the global confinement and edge plasma parameters with limiter biasing, illustrating the direct impact of radial electric fields on confinement properties. Plasma potential measurements by the HIBP diagnostic show a strong impact of heating method (ECRH versus NBI) on radial electric fields.Presented at the Workshop Electric Fields Structures and Relaxation in Edge Plasmas, Nice, France, October 26–27, 2004. 相似文献
994.
This paper analyzes the cooling process of a vertical thin plate originated by a fluid-saturated porous medium, taking into account the effects of both longitudinal and transversal heat conduction in the plate. Due to the finite thermal conductivity of the plate, a longitudinal temperature gradient arises within it, which prevents any similarity solution in the boundary layer, changing the mathematical character of the problem from parabolic to elliptic, for large values of the suitable Rayleigh number. The energy balance equations are reduced to a system of two differential equations with two parameters: the nondimensional plate thermal conductivity and the aspect ratio of the plate . In order to obtain the evolution of the temperature of the plate as a function of time and position, the coupled balance equations are integrated numerically for several values of the parameters, including the cases of very good and poor conducting plates. The results obtained, are compared with an asymptotic analysis based on the multiple scales technique carried out for the case of a very good conducting plate. There is at the beginning a fast transient in nondimensional time scale of order followed by a slow nondimensional time scale of order unity, which gives the evolution of the cooling process. Good agreement is achieved even for values of the conduction parameter of order unity. The asymptotic solution allows us to give closed form analytical solution for the plate temperature evolution in time and space. The overall thermal energy of the plate decreases faster for smaller values of . 相似文献
995.
We consider here a model of fluid-structure evolution
problem which, in particular, has been largely studied from the
numerical point of view. We prove the existence of a strong
solution to this problem. 相似文献
996.
997.
998.
M. I. B. Bernardi E. R. Leite E. Longo M. M. Conceiçăo A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2004,75(2):481-486
The color efficiency of ceramic glaze blue pigments obtained by the Pechini method was presented in this work. The fired pigments
and enameled samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), XRD, UV-VIS-NIR
spectroscopy and CIE-L*a*b* color-measurements. The pigments obtained by the Pechini method present a better solubility in
the molten glazes than the pigments obtained by the mechanical mixture of the precursor oxides.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
999.
1000.