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911.
912.
The possibility of H3+ playing a role as a sink for noble gases has been investigated in the case of Argon. Elaborate quantum methods (ab initio Coupled Cluster and density functional BH&HLYP levels of theory) have been shown to reproduce the rotational constants within 0.3% together with the only known IR frequency on the test case of Ar…D3+. Dissociation energies of (Ar)n…H3+ as a function of cluster size, i.e. 7.2 (n=1), 3.7 (n=2), 3.6 (n=3), 1.6 (n=4), 1.7 (n=5) kcal/mol, follow the pattern established experimentally for (Ar)n…H3+ and (H2)n…H3+ series. Rotational constants and harmonic frequencies of (Ar)n…H3+ (n=1-3) are presented. 相似文献
913.
914.
Using a 2.5-D, time-dependent ideal MHD model in Cartesian coordinates, we carried out numerical simulations to investigate
the equilibrium and evolution properties of a magnetic configuration that consists of a coronal magnetic flux rope and a partly
open photospheric background field, which is equivalent to that produced by a two-patch magnetic source on the photospheric
surface. The axial and annular magnetic fluxes of the flux rope are given and fixed. The global magnetic configuration evolves
in response to three types of changes of the background field: decreasing of the distance between the two sources, shrinking
of the size of each source, and increasing of the shear in the closed component of the background field. As a result, the
geometrical parameters of the flux rope, i.e. the height of the rope axis, the half-width of the rope and the length of the
vertical current sheet below the rope, change due to the variation of the background field. It is shown that for a given coronal
magnetic flux rope in a partly open background field, the variation of the geometrical parameters of the flux rope displays
a catastrophic behavior, namely, there exists a critical point for each case, at which an infinitesimal change of the background
field leads to a loss of equilibrium, and thus a jump of the flux rope. The implication of such a catastrophe in solar active
phenomena is briefly discussed. 相似文献
915.
916.
917.
The possibility of using a nonlinear empirical atmospheric model for hybrid coupled atmosphere-ocean modelling has been examined
by using a neural network (NN) model for predicting the contemporaneous wind stress field from the upper ocean state. Upper
ocean heat content (HC) from a 6-layer ocean model was a better predictor of the wind stress than the (observed or modelled)
sea surface temperature (SST). Our results showed that the NN model generally had slightly better skills in predicting the
contemporaneous wind stress than the linear regression (LR) model in the off-equatorial tropical Pacific and in the eastern
equatorial Pacific. When the wind stresses from the NN and LR models were used to drive the ocean model, slightly better SST
skills were found in the off-equatorial tropical Pacific and in the eastern equatorial Pacific when the NN winds were used
instead of the LR winds. Better skills for the model HC were found in the western and central equatorial Pacific when the
NN winds were used instead of the LR winds. Why NN failed to show more significant improvement over LR in the equatorial Pacific
for the wind stress and SST is probably because the relationship between the surface ocean and the atmosphere in the equatorial
Pacific over the seasonal time scale is almost linear.
Received: 2 March 1999 / Accepted: 13 July 2000 相似文献
918.
A.J. Young † A.C. Fabian R.R. Ross Y. Tanaka 《Monthly notices of the Royal Astronomical Society》2001,325(3):1045-1052
The galactic black hole candidate Cygnus X-1 is observed to be in one of two X-ray spectral states: either the low/hard (low soft X-ray flux and a flat power-law tail) or high/soft (high blackbody-like soft X-ray flux and a steep power-law tail) state. The physical origin of these two states is unclear. We present here a model of an ionized accretion disc, the spectrum of which is blurred by relativistic effects, and fit it to the ASCA , Ginga and EXOSAT data of Cygnus X-1 in both spectral states. We confirm that relativistic blurring provides a much better fit to the low/hard state data and, contrary to some previous results, find the data of both states to be consistent with an ionized thin accretion disc with a reflected fraction of unity extending to the innermost stable circular orbit around the black hole. Our model is an alternative to those that, in the low/hard state, require the accretion disc to be truncated at a few tens of Schwarzschild radii, within which there is a Thomson-thin, hot accretion flow. We suggest a mechanism that may cause the changes in spectral state. 相似文献
919.
920.
Arnaud M. Aubourg E. Bareyre P. Br';ehin S. Caridroit R. de Kat J. Dispau G. Djidi K. Gros M. Lachièze-Rey M. Laigneau Y. Laurent B. Lesquoy E. Lavocat Ph. Magneville C. Mazeau B. Milsztajn A. Moscoso L. Pasquaud J. Paul B. Perrin P. Petibon J. Piret Y. Queinnec F. Rich J. Spiro M. de Trogoff J. Vigroux L. Zylberajch S. Ansari R. Cavalier F. Moniez M. Beaulieu J. P. Ferlet R. Grison Ph. Vidal-Madjar A. Adrianzyk G. Berger J. P. Burnage R. Delclite J. C. Kohler D. Magnan R. Richaud A. Guibert J. Moreau O. Tajahmady F. Baranne A. Maurice E. Prévôt L. Gry C. 《Experimental Astronomy》1994,4(3-4):279-296
Conclusion To summarize, the readout and the control system of the CCD mosaic camera are running since December 1991 at the La Silla Observatory (ESO). The overall performance of the camera has been good. About 12000 pictures (data and flat-fields) have been successfully registered up to now. We will report in the near future preliminary scientific results of the EROS experiment. 相似文献