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31.
S. Cecchini G. Giacomelli D. Haşegan G. Mandrioli O. Mariş L. Patrizii A. Plaian V. Popa L. Ştefanov V. Văleanu 《Astrophysics and Space Science》2000,273(1-4):35-41
The solar neutrino problem could arise from oscillation of one neutrinotype into a secondtype. Neutrinos would have a mass and there could be the possibility ofradiative neutrino decays. We discuss the search for neutrino decaysduring the 1999 solar eclipse: it involves the emitted visible photons,while neutrinos travel from the Moon to the Earth. The concept and themain characteristics of the NOTTE experiment are presented. 相似文献
32.
A variability survey on the shape of the light curve of the classical Cepheid DL Cas has been performed on the basis of Johnson
V photometry data covering about 38 years. The input parameters (mean magnitude, pulsation frequency and period, light curve
amplitude, harmonics amplitudes, Fourier type structural parameters) for our study were determined through the Fourier decomposition
technique applied to each data set. The analysis of the outcoming time series, using different and complementary methods,
seems to indicate the constancy of these parameters within the precision limits of the available data, although the hypothesis
of the presence of a low level variability cannot be excluded. The only exception is the pulsation period, which displays
a possible increasing trend with a rate of 0.109 ± 0.037 s yr−1. This trend may be, at least partly, an effect of the unequal precision of pulsation period estimated values, corresponding
to each considered data set.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
33.
A study of the orbital period variation of the W UMa system CK Bootis is made using an extended observational time base. The biperiodicity of the orbital period modulation is emphasized. Both detected periodicities (24.14 yr and 10.62 yr) cannot be explained through the light-time effect unless the companion would be a white dwarf as suggested by other authors, too. Moreover, we also argue that, nowadays at least, it seems that there is no causal relation between the orbital period variation and the recently discovered visual companion. Consequently, we infer that at least one of the two periodicities may be related to the magnetic activity cycles in the component stars of CK Boo, while the other periodicity could be related to the presence of a fourth companion in the system. 相似文献
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Hysteretic behaviour of reinforced concrete members is strongly dependent on local conditions such as quality of materials, workmanship, construction and design practice. Low strength concrete was found in most of the damaged concrete structures after the earthquakes that have hit Eastern Europe in the past 50 years. Quality of concrete had a great impact, especially on shear controlled reinforced concrete short columns. Existing models of the effective strength, stiffness and deformation capacity of structural members need to be confirmed locally by experimental research as the large data sets used to calibrate the analytical models comprise results obtained on specimens with various characteristics. In this study, effective stiffness and deformation models available in literature are compared with the results of an experimental testing program conducted by the authors to investigate the hysteretic response of reinforced concrete short columns with low concrete strength, designed and detailed according to the local practice in the past. The hysteretic behaviour of the specimens is presented together with a comparison of the experimental data with predicted values and conclusions on the suitability of the applied models are drawn. 相似文献
36.
Ovreiu Adriana Bianca Bărsoianu Iulian Andrei Nistor Constantin Nedelea Alexandru Comănescu Laura 《Natural Hazards》2019,99(1):117-140
Natural Hazards - Rockfalls represents a sudden, extremely important geomorphological hazard and may become a threat for people’s life, as well as goods and transport. The present study aims... 相似文献
37.
Alexandru T. Codilean Paul Bishop Trevor B. Hoey Finlay M. Stuart Derek Fabel 《地球表面变化过程与地形》2010,35(1):16-27
We use a numerical model describing cosmogenic nuclide acquisition in sediment moving through the upper Gaub River catchment to evaluate the extent to which aspects of source area geomorphology and geomorphological processes can be inferred from frequency distributions of cosmogenic 21Ne (21Nec) concentrations in individual detrital grains. The numerical model predicts the pathways of sediment grains from their source to the outlet of the catchment and calculates the total 21Nec concentration that each grain acquires along its pathway. The model fully accounts for variations in nuclide production due to changes in latitude, altitude and topographic shielding and allows for spatially variable erosion and sediment transport rates. Model results show that the form of the frequency distribution of 21Nec concentrations in exported sediment is sensitive to the range and spatial distribution of processes operating in the sediment's source areas and that this distribution can be used to infer the range and spatial distribution of erosion rates that characterise the catchment. The results also show that lithology can affect the form of the 21Nec concentration distribution indirectly by exerting control on the spatial pattern of denudation in a catchment. Model results further indicate that the form of the distribution of 21Nec concentrations in the exported sediment can also be affected by the acquisition of 21Nec after detachment from bedrock, in the diffusive (hillslope) and/or advective (fluvial) domains. However, for such post‐detachment nuclide acquisition to be important, this effect needs to at least equal the nuclide acquisition prior to detachment from bedrock. Copyright © 2009 John Wiley and Sons, Ltd. 相似文献
38.
Thébault H Rodriguez Y Baena AM Andral B Barisic D Albaladejo JB Bologa AS Boudjenoun R Delfanti R Egorov VN El Khoukhi T Florou H Kniewald G Noureddine A Patrascu V Pham MK Scarpato A Stokozov NA Topcuoglu S Warnau M 《Marine pollution bulletin》2008,57(6-12):801-806
The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify (137)Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured (137)Cs levels were found to be very low (usually < 1 Bq kg(-1) wet wt) (137)Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area. 相似文献
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