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81.
A smooth 1-form on real projective space with vanishing integral along all geodesics is said to have zero energy. Such a 1-form is necessarily the exterior derivative of a smooth function. We formulate a general version of this theorem for tensor fields on real projective space and prove it using methods of complex analysis. A key ingredient is the cohomology of involutive structures. 相似文献
82.
We present several examples of homogeneous domains in complex space that do not have bounded realisations. The domains are equivalent to tubes over affinely homogeneous domains in real space. 相似文献
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Observations of an extremely elongated electron diffusion region occurring during fast reconnection are presented. Cluster spacecraft in situ observations of an expanding reconnection exhaust reveal a broad current layer ( approximately 10 ion skin depths thick) supporting the reversal of the reconnecting magnetic field together with an intense current embedded at the center that is due to a super-Alfvénic electron outflow jet with transverse scale of approximately 9 electron skin depths. The electron jet extends at least 60 ion skin depths downstream from the X-line. 相似文献
86.
The instability of a plane front between two phases of the same fluid (steam and water) in a porous medium is considered. The configuration is taken to be initially stationary with the more dense phase overlying the less dense phase. The frontal region is assumed sharp, so that macroscopic boundary conditions can be utilized. This assumption precludes the existence of dispersion instabilities. The stabilizing influence of phrase transition as well as the implication of different macroscopic pressure boundary conditions on the stability of the front are discussed and illustrated. 相似文献
87.
Two phase countercurrent steady-state flow through permeable media in one dimension is discussed. For steady-state countercurrent flow in water wet porous media, a saturation profile is predicted with the water saturation decreasing in the direction that the water phase is flowing. The de la Cruz and Spanos equations predict that the Muskat relative permeability curves for countercurrent flow will be less than the Muskat relative permeability curves for steady-state cocurrent flow. This result has immediate implications regarding the use of external drive techniques to determine relative permeabilities based on the Buckley-Leverett theory and Muskat's equations. These equations and current experimental evidence involving countercurrent flow indicate that Muskat's equations do not adequately describe the multiphase flow of immiscible fluids. 相似文献
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DeLyle Eastwood Martha Schulz Hendrick Myron H. Miller 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(4):293-302
Sodium-induced emission enhancement of transition metal resonance lines are measured in a d.c. plasma (DCP) for wavelengths from 210 to 395 nm. Systematic differences in enhancement are observed within individual spectra (Fe I, Ni I, Sc II), and the enhancement and the excitation potential of a line are found to be linearly related. Electron density and apparent temperature data lead to an interpretation of thiis energy dependence within the context of a recombining plasma in partial thermodynamic equilibrium. 相似文献
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