Results 1 - 10 of 1006
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[en] The bioclimatic belts are primarily each one of the thermoclimatic spaces delimited by bioindicators, recognizable in the terrestrial environment in altitudinal or latitudinal zonation. Such thermoclimatic spaces are delimited on determined values of the thermicity index or thermotypes (thermo, meso, supra, etc); in each of these, with respect to precipitation, diverse rainfall types or ombric variants (arid, semiarid, dry,...) are recognized. In western Europe, fifteen bioclimatic belts (thermotypes) are accepted
[en] This study sought to improve general understanding on rainfall timing in Nigeria. Observed monthly rainfall data for 38 meteorological stations, spanning 30 years was utilized, and the dates of onset and cessation of rainfall were estimated using Walter’s method. The interrelationships among the variables and the dependency of the amount of rainfall were calculated using Pearson’s moment correlation coefficient and multiple regression, respectively. The variance of the Standardized Anomaly Index (SAI) was used as a measure of spatial coherence. The study revealed divergent characteristics between the onset and the cessation of rainfall; progressing in opposite direction, with a very high latitudinal variation in each. Rainfall onset has a relatively high interannual variability, with an average CV of 21%, compared to 3.9% for cessation. Onset also has a larger spatial range of 137 days, compared to 82 days for cessation. Additionally, rainfall cessation was found to be more spatially coherent than the onset, but both revealed a weak spatial coherence. The relative spatial incoherence and high interannual variability of onset contrive to make it much less predictable than cessation. Interestingly, rainfall amount shows greater association with, and dependency on, onset, cessation, and rainy season length in stations of the extreme north, than in southern stations.
[en] Partial trend method (PTM) is an innovative and efficient trend analysis method, especially for sub-trends in different magnitudes. However, it depends on graphs and identifies trends subjectively, which limit the application for a large mass of data and cannot reveal significant variations from natural variability and randomness. To remedy these shortcomings, this paper applies a trend index derived from the PTM plot, and develops a nonparametric bootstrap approach to identify statistically significant trends. The improved PTM is used to detect trends of annual rainfall, monthly rainfall, monsoon rainfall, annual number of rainy days, and average intensity of daily rainfall in Hainan Island from 1950s to 2014. The Mann–Kendall test is also employed for a comparison purpose. The PTM reveals that, except at the Sanya station, annual rainfall and monsoon rainfall generally show an insignificant change in various magnitudes. Rainy days and daily rainfall intensity show a prevailing decreasing and increasing trend, respectively. The opposite trends explain the no trend in annual rainfall. The trends revealed by the PTM and the Mann–Kendall test show high consistency. This demonstrates that the PTM index combined with the nonparametric bootstrap method is a reliable technique. The improved PTM makes it flexible to detect overall and partial trends by graphical analysis, or detect significant trends for a mass of data by an index. Not limited to rainfall variables, this method is hoped to analyze trends in other fields.
[en] The aim is to compare plastic deformation capacities of flexure-controlled reinforced concrete members, as predicted by the Italian Seismic Code, Eurocode 8 and FEMA356. For completeness, recent studies in the literature are also referred to. The comparison is pursued in context with a nonlinear static analysis run on 2D frame structures. This allows to assess whether and to which extent plastic deformation capacities may be affected by variations in those quantities, such as shear span and/or axial load, depending on which plastic deformation capacities are generally given
[en] Full text : The plegicil-geographical researches had established the predominant development of definite non-anticlinal traps in some stages and oil deposits related with them. At the final stage of the Alpine tectonic cycle more favorable conditions rise for formation of paleogemorphological and structural-stractigraphical types of non-anticlinal traps due to relation with increase of the tectonic movements contrast and existence of numerous regional and local bakers in sedimentation. The complex history of the geotechnical development of the mentioned large tectonic units made the favorable conditions for formation of non-anticlinal traps of different in various stratigraphical complexes. Marine tangerines begun in the Early Cretaceous had led to accumulation of carbonaceous mainly, then sandy-clayey formations. The Middle Cretaceous is characterized with instability of the geotectonic regime
[en] The North Atlantic Oscillation (NAO) is the most significant large-scale mode of natural climate variability on the Northern Hhemisphere and Arctic Oscillation (AO) is its supplement. Both have large impacts on weather and climate in the North Atlantic region and surrounding continents including Europe. NAO and AO phases cause specific already defined changes in distribution of climate elements in wide area. The cross-correlation between daily precipitation data on stations in Serbia and NAO daily index plus AO daily index for the period 1951-2003 is analysed in this paper. Number of cross correlation coefficients have been calculated and the highest values were obtained for daily precipitation in Serbia with the AO index in winter, ranging from -0.44 to - 0.38. The analyses of trend for two periods 1961-2006 and 1980-2006 for the whole year and during winter months only, at 21 stations in Serbia have been performed, too. Very high positive trend for precipitation was obtained for many places in Serbia especially in Vojvodina. The results also indicate to non-homogeneities in the region and influence of NAO during winter.