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排序方式: 共有136条查询结果,搜索用时 31 毫秒
41.
Miroslav Gačić Vedrana Kovačević Simone Cosoli Andrea Mazzoldi Jeffrey D. Paduan Isaac Mancero-Mosquera Sadegh Yari 《Estuarine, Coastal and Shelf Science》2009
Surface patterns of the low-frequency current in a 20 × 30 km region in front of the Venice Lagoon were analysed from a 13-month-long HF radar data set. Surface circulation was related to prevalent wind regimes in the area and to the tidal flow through the lagoon inlet. Three different categories of wind-forcing were defined: bora (NE wind), sirocco (SE wind), and finally the category containing all other wind directions and calms (winds lower than 3 m/sec). Mean flow and vorticity spatial distributions were discussed for different wind conditions. The coastal area about 5 km wide is characterized by a flow field with maximum vorticity. Outside the coastal boundary layer the interior flow is part of the Adriatic basin-wide cyclonic circulation. Two counter-rotating vortices of the dimension of about 4–5 km were evidenced in the average flow field in front of the lagoon inlet (Malamocco inlet) in all situations except for the bora. The vortex-pair is probably associated with the tidal flow through the inlet. The bora wind induces a strong southward coastal jet detached from the coast by about 5 km homogenizing the flow and eliminating the dipole. The average coastal flow pattern in calm wind conditions was also analysed as a function of the strong inflow/outflow (currents in the inlet > 0.7 m s−1) from the lagoon inlet. In both cases the vorticity pattern is similar, with the negative vorticity to the left of the inlet and positive to the right looking seaward. 相似文献
42.
HD 6226 is a bright binary Be star at visual magnitude 6.81 (Hipparcos database). The emission and absorption phases occur
in cycles, which are probably not periodic. The suspected period of about 630 days (derived from photometric measurements)
is not confirmed by our spectroscopic survey. The latest emission phase developed in the beginning of 2003, then the emission
strength systematically decreased and disappeared between July 21, 2003 and August 4, 2003. The last (absorption) spectrum
was exposed on August 25, 2003. Unexpected very strong emission appeared in a spectrum exposed on October 28, 2003. A short-term
photometric brightening followed this “outburst”.
Long-term spectroscopic RV studies revealed a 2.615 d period modulated by a 29.7 d period (in the He I 6678 line), which perhaps
may be interpreted as orbital period of a binary. Nevertheless, the physical nature of the dominant short 2.615 d period is
not yet clear.
The last detected emission episode has changed considerably our view of the interesting object HD 6226. We hope this study
will reveal more details of the physical properties of the Be phenomenon. 相似文献
43.
The hypothetical final parameters of the Universe result from the model properties of the expansive non-decelerative universe and properties of the hypothetical primordial black holes. 相似文献
44.
The measure of inhomogeneity of the expansive nondecelerative Universe is obtained. 相似文献
45.
A way of computing the absorption cross-section for photons on electrons undergoing free-free transitions in magnetic plasma is described. Theoretical expressions for the free-free cross sections in magnetic plasma are given in a representation in which they can be easily compared with the classical results in the absence of the magnetic field. The results of numerical computations of these cross-sections are also presented and discussed. Finally the free-free cross-sections are averaged over the electron states in magnetic plasma in thermal equilibrium, yielding the opacity coefficient as a function of photons frequency. The results of numerical computations are given in graphical form. 相似文献
46.
Yoji Kondo Margherita Hack John B. Hutchings George E. McCluskey Jr. Miroslav Plavec Ronald S. Polidan 《Astrophysics and Space Science》1975,38(2):353-358
High-resolution ultraviolet spectrophotometry of the complex close binary systemβ Lyrae was performed with the Princeton Telescope Spectrometer onCopernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with the resolution of 0.2 Å (far-ultraviolet) and 0.4 Å (mid-ultraviolet). The far-ultraviolet spectrum is completely dominated by emission lines indicating existence of high temperature plasma in this binary. The spectrum ofthis object is unlike any other object observed fromCopernicus. It is believed that this high temperature plasma results from dynamic mass transfer taking place in this binary. The current results are compared with the OAO-2 Wisconsin Experiment Package observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; theCopernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole. 相似文献
47.
48.
On the basis of model properties of the expansive non-decelerative universe, the temperature at the end of the radiation era and of the present temperature of cosmic microwave background spectrum, the present parameters of our Universe can be determined.From model properties of the expansive non-decelerative universe and the temperature at the end of the radiation era follow: the hypothetical mass value of electron neutrino and the hypothetical values of the final parameters of the creative-expansive evolutionary phases of ultrastable expansive non-decelerative universes. 相似文献
49.
Thomas Foulon Ali Saeidi Romain Chesnaux Miroslav Nastev Alain Rouleau 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(1):74-86
The spatial distribution of soil shear-wave velocity and the fundamental period of vibration were selected as input parameters for the determination of potential seismic site effects in the Saguenay region, Canada. The methodology used in this study involved three clear steps. First, a 3D geological model of the surficial deposits was built taking into consideration the type, spatial distribution and thickness of the deposits. Second, representative average Vs values were determined for each of the major soil units. Finally, the average shear-wave velocity from the ground surface to bedrock (Vsav), the shear-wave velocity of the upper 30 m (Vs30) and the fundamental site resonance period (T0) were calculated over a regular grid for the study area. The results include the spatial distribution of the fundamental site resonance period, the average shear-wave velocity in the first 30 m of the ground and the spatial distribution of National Building Code of Canada seismic soil classes for the Saguenay region. 相似文献
50.
Pánisová Jaroslava Balázs Attila Zalai Zsófia Bielik Miroslav Horváth Ferenc Harangi Szabolcs Schmidt Sabine Götze Hans-Jürgen 《International Journal of Earth Sciences》2018,107(5):1713-1730
International Journal of Earth Sciences - Three-dimensional geophysical modelling of the early Late Miocene Pásztori volcano (ca. 11–10 Ma) and adjacent area in the Little... 相似文献