从“有机分散”到“新都市主义”

本文针对“有机分散”理论与“新都市主义”理论,对工业革命以后城市发展的不同见地,提出城市是在吸引与排斥的相对运动中获得发展,在集中与分散中取得平衡。     

Bohm Criterion for Collisionless Sheaths in Two-Ion-Species Plasmas

The sheaths of a plasma containing two species of positive ion generated in a low pressure discharge （- mTorr） are studied using a fluid model. It is shown anal...     

Investigation of the Parallel Flow in the Edge Plasma of EAST

The effects of the E × B drift and ballooning-like transport on the edge plasma in EAST tokamak are investigated with a simplified fluid model. The simulation results show that the E × B drift and ballooning-like transport affect the plasma behavior. When the toroidal field is reversed, at the low field side the density is much larger and temperatures （both electron and ion） are lower, and the profiles of the density and temperatures become more symmetric. With the ballooning-like transport considered, the spatial ballooning-like distribution at the low field side is not very important, but the magnitude affects the ratios of the inner/outer particle flux and energy as well as the E × B drift. At the top of the scrape-off layer, the Mach number exceeding 0.3 for the normal toroidal field and approaching 0.2 for the reversed toroidal field in the simulation are obtained when the drift and ballooning-like transport are included in the model.